Quarterly Publication Rs. 20 APRIL 2020 Weld 19 Bead 1 JOURNAL... · IWS DAY CELEBRATIONS 2020 The...
Transcript of Quarterly Publication Rs. 20 APRIL 2020 Weld 19 Bead 1 JOURNAL... · IWS DAY CELEBRATIONS 2020 The...
-
Quarterly Publication Rs. 20
APRIL 2020 Weld 19 Bead 1
-
Page 2 of 36
AROUND IWS
KNOWLEDGE SHARING
TECHNICAL PAPERS
THE JOURNAL OF
Regn. No. 41817 / 2002
QUARTERLY PUBLICATION
APRIL 2020 Weld: 19 Bead: 1
PRESIDENT
SHRI R PADMANABHAN
Immediate Past President
SHRI S BISWAS
Vice Presidents
SHRI HIMANSHU I GANDHI SHRI S PRABAKARAN
Dr S ARAVINDAN
Hon. Secretary
SHRI N RAJASEKARAN
Hon. Treasurer
Mrs. A SANTHAKUMARI
Members
Dr K Asokkumar Dr A Chandrasekhar
Shri A Maruthamuthu Dr. T Senthil Kumar
Shri G Rajendran Shri V Ganesh Sinkar
Shri M P Jain Dr Shashikantha Karinka
Shi M Kasinathan Shri Gyan Prakash Bajpai
Shri R Easwaran Dr G Padmanabham
Shri S M Agarwal Shri Muneesh Narain
Shri S M Bhat Dr T Prakash
Shri Amit Agarwal Dr S Shanavas
Dr V Balasubramanian Shri Naresh Malli Reddy
Shri T Baskaran Dr Yadaiah Nirsanametla
Dr N Murugan Shri A K Verma
Dr N Raju Dr P Sivaprakash
Editor in Charge Shri S. PRABAKARAN
ASSOCIATE EDITORS Shri Praveen Kumar Lakavat Shri R. Arivalagan
CO-ORDINATORS Dr. N Raju Shri A K Verma
PUBLISHED BY
On Behalf of IWS by
Shri N RAJASEKARAN Hon. Secretary (IWS)
INDIAN WELDING SOCIETY INSTITUTIONS BUILDING, KAILASAPURAM, TIRUCHIRAPPALLI – 620 014
INDIA Websites: www.iws.org.in www.iwsevents.com
E mail: [email protected]
http://www.iws.org.in/http://www.iwsevents.com/mailto:[email protected]
-
Page 3 of 36
-
Page 4 of 36
IWS DAY CELEBRATIONS 2020
The IWS Day 2020 was celebrated at the SK Mazumder Hall,
Institutions Building, BHEL Township, Tiruchirappalli on 14th
March 2020 by HQ and SZ.
Mr. S. Prabakaran, Vice President (IWS) presided over the
function and delivered the IWS day address to the members. In
his address, Mr.
Prabakaran informed
the gathering that in the next couple of days IWS will
inaugurate its Mangaluru Centre. He appreciated the
participants of the weld quiz and skill test conducted by IWS in
association with HRDC, BHEL, for the budding welders. He also
congratulated the winners of the competitions. He distributed
the prizes and certificates. Mr. Prabakaran also cut a cake to
mark the celebrations in the presence of the members.
The skill test was conducted on 12th March 2020 by Mr.
Shanmugam and Mr. Subramanian of HRDC BHEL under the
leadership of Mr. V Sivakumar, SDGM, HRDC. Mr. Prabakaran
thanked with mementos.
Earlier, Mr. S. Singaravelu, Zonal Vice Chairperson, IWS, SZ
welcomed the gathering. Mr. N Rajasekaran, Hon. Secretary,
IWS recalled the history of IWS and the past accomplishments.
Mrs. A. Santhakumari, Hon. Treasurer, IWS proposed the vote
of thanks. Mr. G Rajendran, Imm. Past Treasurer of IWS read
out the President’s Message. Mr. Arunan, Zonal EC member,
SZ announced the results of the quiz and skill test. Mr. N
Parameswaran conducted the proceedings and proposed the vote of thanks.
AROUND
-
Page 5 of 36
-
Page 6 of 36
AT ANNAMALAI NAGAR CENTRE
The Annamalai Nagar Centre celebrated the IWS day with a free workshop on
“Friction Based Joining Technologies” at CEMAJOR, Annamalai University. Prof. Dr
V Balasubramanian, Head, CEMAJOR and NGC member delivered the keynote
address and enlightened the members
about IWS.
Dr K Shanmugam, Dr P Sivaraj and other
senior members participated and
offered their felicitations.
**Reports are awaited from other centres and zones.
AWARDS & RECOGNITIONS
Prof. Dr V Balasubramanian & Dr P Sivaraj were conferred with Panthaki Memorial Award 2019 by IIW.
IWS JOURNAL congratulate the members and other members who received awards.
-
Page 7 of 36
LAUNCHING OF MANGALURU CENTRE
IWS added one more feather in cap by launching the Mangaluru Centre of IWS.
Indian Welding Society(IWS) Mangaluru centre has been inaugurated by Honorable Chancellor of Nitte
Deemed to be University and President of Nitte Education trust
Shri N. Vinaya Hegde on 16th March 2020 in the presence of Shri
S Gopinath, Past President, Shri S Prabakaran, Vice President,
Shri N Rajasekaran, Hon. Secretary, Shri G Rajendran, Former
Hon. Treasurer, Shri S Singaravelu, Zonal Vice Chairperson SZ,
office bearers of the local centre, officials of BEML KGF complex
and local industries.
Mr. Vinayak Hegde inaugurated the Mangaluru centre by
lighting the lamp with the dignitaries and unveiling of the
plaque. In his address, Shri Hegde stressed the need for
venturing into newer areas of technology that could provide
employment opportunities. He mentioned that the
mechanical engineering stream has to be restructured with
newer technological inputs to attract the best students.
Indian welding society (IWS) is a registered professional
body devoted to welding in India with its headquarters at
New Delhi and is
promoted by Welding
Professionals from
leading Fabrication
Industries, Academic
& Research Institutes
and progressive minded Welding Consumable & Equipment
Manufacturers. IWS has the national membership of over 3600 and has 65 life members in the
Mangaluru region. Hence it was felt necessary to form
Mangaluru centre to bring all the welding professionals working
in academics and industry together for interactions on a
common platform. The IWS Mangaluru centre is formed with
patronage of Shri N. Vinaya Hegde.
Shri S. Prabakaran Vice President, IWS and General Manager of
BHEL Tiruchy installed the office bearers of the centre and appreciated the initiatives taken by the
Mangaluru centre in attracting good number of life members.
Mr. N. Rajasekaran, Hon. Secretary, IWS offered his felicitation of the newly installed office bearers and
briefed about different activities of the Indian Welding Society. He assured the co-operation and
support from HQ for the centre.
-
Page 8 of 36
Shri S. Gopinath, Past President of IWS and former Executive
Director of BHEL Tiruchy gave an overview of the history of
development of Mangaluru Centre.
Earlier, Prof Shashikantha Karinka welcomed the gathering.
Prof. Muralidhara and Dr. Vijeesh Vijayan introduced the office
bearers, Mr. Divijesh performed invocation and Mr. Sudhir J
Shetty ended the programme with vote of thanks. Mr. Melwyn
Castelino compered the programme.
The office bearers of the centre installed in the inauguration
are Dr. Shashikantha Karinka Professor and Head of
Mechanical Engineering of NMAMIT as Chairman of the Centre,
Mr. MJ Shetty Managing Director of Lakshmi Cryogenics as Vice
Chairman of the Centre, Mr. Sudhir J. Shetty CEO of Varun
Engineering Corporation as Hon. Centre Secretary, Mr. Gajanan
S Hegde, Deputy General Manager of Mangalore Chemicals and Fertilizers Limited as Hon. Centre
Treasurer along with Executive Committee Members of the Centre.
It is proposed to have the local office in Nitte Education International at Pumpwell, Mangaluru.
-
Page 9 of 36
KNOWLEDGE SHARING ONE DAY SEMINAR ON “RECENT TRENDS IN WELDING TECHNOLOGY” BY IWS
MANGALURU CENTRE
Immediately after the inauguration, the Mangaluru Centre
conducted a one-day Seminar on “Recent Trends in Welding
Technology” by experts
from IWS. The event
attracted about 60
delegates from various industries and students from ITI,
Diploma and Engineering institutions. The resource persons of
the seminar are: Mr. G. Rajendran, Former Hon. Treasurer IWS
& former Addl. GM of BHEL, Mr. N. Rajasekaran, Hon.
Secretary, IWS & Deputy General Manager of BHEL Tiruchy,
Mr. Prashant Hegde, Sr. Manager Inspection department,
OMPL Mangaluru, Mr. S. Singaravelu, Zonal Vice
Chairperson, IWS South Zone & Former Addl. GM, BHEL and
Dr. G. Ravichandran, Former General Manager Welding
Research Institute & Adjunct Professor NMAMIT.
.
-
Page 10 of 36
STRUCTURED COURSES
The Southern Zone conducted its flagship course “Welding
Technology for Fresh Engineers Course (EC 056)” during
17.02.2020 – 23.02.2020. 26 students from various
engineering colleges and industries have attended the
course and got benefited by the heavily subsidized course.
Mr. S. Prabakaran, Zonal Chairman, IWS, SZ, inaugurated
the course and distributed the course materials to the
participants.
Mr. N Rajasekaran, Hon. Secretary, IWS offered his felicitations
and shared the genesis of the course. Mrs. A Santhakumari, Hon.
Treasurer, IWS welcomed the gathering. Mr. Pravin Kumar
Lakavath, Course Director & Hon. Treasurer, SZ, proposed the
vote of thanks.
On 23rd February 2020, Mr. N Rajasekaran, Hon. Secretary (IWS) distributed the certificates to the
participants and delivered the valedictory address. Mr. Praveen Kumar Lakavat, Course Director (IWS,
SZ) welcomed the gathering. Mr. G Rajendran former Treasurer offered his felicitations. Mr. N
Parameswaran, Zonal EC member of IWS, SZ proposed the vote of thanks. The participants expressed
that they got benefited from the course and thanked IWS for the noble initiative.
ONE DAY WORKSHOP ON “WELDING AUTOMATION FOR MODERN
MANUFACTURING SECTORS” BY BIT – IWS STUDENT FORUM
Welding automation plays a vital role in many manufacturing industries such as automotive, Aerospace,
Defence, Shipping, etc. To discuss on the latest trends in
welding automation, the BIT – IWS Student Forum under
financial support by IWS, organized the workshop on 14th
February 2020. Furthermore this workshop is exclusively
targeted to improve the knowledge of Young engineering
graduates and faculties and researchers from various
institutions in Southern Zone. 186 delegates attended
the one day event and got benefitted.
-
Page 11 of 36
The workshop was inaugurated by the chief Guest Dr. D. Kesavan, Assistant Professor from IIT Palakkad
and Mr. S. Praveen, Regional Manager from M/s. Fronius India limited.
Dr. M. Ravikumar, Professor HOD, Mech, BIT welcomes the gathering
of this workshop and Mr. D. Dinesh introduce the chief guest and
address the participants. Followed by the Four Technical sessions
related to the automation in welding and additive manufacturing in
laser welding, wire + arc additive manufacturing, robotics in TIG + MIG welding and Cold metal transfer
welding by Various experts. Vote of Thanks is proposed by Mr. G. Sundar Raju followed by certificate
distribution in valedictory function.
ONE DAY WORKSHOP ON “EMERGING TRENDS IN JOINING OF THIN SHEETS
AND EVALUATION” BY KSRCT – IWS STUDENT FORUM
The KSRCT – IWS Student Forum organised a One-day workshop on “EMERGING TRENDS IN JOINING OF
THIN SHEETS AND EVALUATION” on 18.02.2020 at the main building seminar hall of the college at
Tiruchengode. Mr. S. ADITHYA NAIR welcomed the gathering. Dr. K. MOHAN introduced the chief guests
Mr. N. RAJASEKARAN, Mr. S. SINGARAVELU and Mrs. A. SANTHAKUMARI. Dr. R. GOPALAKRISHNAN,
Principal presented a memento to Mr. S. SINGARAVELU and the faculty Mr. S. SAKTHIVEL presented a
memento to Mr. N. RAJASEKARAN and the faculty Dr. K. MOHAN
presented a memento to Mrs. A. SANTHAKUMARI.
The chief guest Mr. S. SINGARAVELU delivered the content on the
topic of “THIN SHEETS MATERIALS AND DEVELOPMENT “at 10.00
am. Then the chief guest Mrs. A. SANTHAKUMARI delivered the
content “SOLID STATE WELDING PROCESSES FOR THIN SHEETS” by
11.30 am. Finally, the chief guest Mr. N. RAJASEKARAN delivered
the topic of “ROBOTICS AND AUTOMATED PROCESSES “at 2.00 pm.
Ms. S. MONLISA thanked the guests, professors and pupils.
-
Page 12 of 36
TWO DAY NATIONAL WORKSHOP ON “AUTOMATION IN WELDING AND NON
DESTRUCTIVE TESTING” BY Dr NGPIT – IWS STUDENT FORUM
Dr. NGPIT – IWS Student Forum has conducted the
IWS Sponsored Workshop on “Automation in
Welding and Non Destructive Testing” from
13.03.2020 to 14.03.2020. The event has been
inaugurated by the chief guest Dr. N. Murugan,
Professor, PSG Tech, Mr. S. Singaravelu, Former
Additional General Manager BHEL and Mr. N.
Parameswaran, Former Sr. Deputy General
Manager, BHEL. Dr. S. Nandhakumar Professor
HOD, Mech welcomed the gathering of this workshop and Dr. K. Kalaiselvan, Professor of Mechanical
Engineering introduced the chief guest and addressed the participants. Dr. K. Porkumaran Principal
felicitated the gathering. Followed by the eight Technical sessions related to the automation in welding
and non-destructive testing by various experts. Vote of Thanks is proposed by Miss. Kavya Secretary-
Student forum followed by certificate distribution in valedictory function.
ONE DAY WORKSHOP ON “WELDING OF EMERGING POWER PLANT
MATERIALS” BY RIT – IWS STUDENT FORUM
Department of Mechanical Engineering, Ramco Institute of Technology and RIT - Indian Welding Society
Students Forum jointly organized a One day Workshop on Welding Emerging Power Plant Materials on
3rd February 2020 (Monday) to RIT – IWS students Members at Mechanical Seminar Hall, RIT,
Rajapalayam. Dr. S. Rajakarunakaran, HOD/Mech, Mr. S. Maharajan, AP/Mech, Mr. J. Jerold John Britto,
AP (S.G)/Mech coordinated the event. The program started with invocation “Tamil Thai Valthu”. Mr. S.
Maharajan, AP/Mechanical and RIT – IWS coordinator welcomed the gathering. Dr. P. Suresh Kumar,
Associate Professor/Mechanical presided over the function. The chief Guest of the Event Mr. N.
Rajasekaran, Hon. Secretary (IWS) & DGM (Unit II), Bharat Heavy Electricals Limited, Tiruchirappalli has
delivered the inaugural address. He narrated about RIT IWS and its unique function in organizing
technical talk and lectures in the past and assured that RIT IWS will organize technical talks, workshops
and seminars to students in future by assisting and providing eminent resource persons from BHEL and
WRI for conducting events. He mentioned the importance of welding in specific applications like
defence, boiler industries, constructions, railways, aircraft industry, under water welding. He also
explained the following privileges from IWS to RIT – IWS students’ forum.
• Student Forum Certificate from IWS to the institution
• IWS Membership ID Cards to all Student Members
• Financial Assistance of Rs. 10,000/- for one day Programme and Rs. 15,000/- for two days
programme on First Come First Served basis.
-
Page 13 of 36
• IWS Journal with technical articles as E-Journal for all
Members
• 5 free delegate s for the International events of IWS
from your student forum.
• Faculty Support for Seminars / Conferences /
Workshops / all lecture programmes from the panel
of Experts of IWS
• Support for Projects Works of the student
• Participation in lecture programme of Zones/Centres, free of cost/Highly subsidised rate by the
student members
• One copy of the Proceedings of IWS Events as complimentary copy to the library of the Institute.
The following topics were deliberated during the workshop.
S. No Name of the Expert and their Designation Topics to be delivered
1. Mr. S. Singaravelu, Consultant and Former AGM,
WTC, BHEL. Zonal Vice Chairman, IWS (South Zone) Advanced Materials for Power Plant Industries
2. Mr. N. Parameswaran, Former DGM, BHEL. Zonal
Executive Committee Member, IWS ( South Zone) Testing and Weldability of Stainless Steel
3. Mr. N. Rajasekaran, DGM, BHEL, Hon. Secretary,
IWS.
Processing of 9Cr-1Mo Steel and Welding
Defects
ONE DAY WORKSHOP ON “ADVANCES IN WELDING TECHNOLOGY & CAREER
OPPORTUNITIES’ FOR POLYTECHNIC STUDENTS
On the request from the alumni of the SSPTC, Sirkali, a One Day Free Workshop
on “Advances in Welding Technology & Career Opportunities” was conducted
at the college premises, for the final and 2nd year mechanical students. Mr. N
Rajasekaran, Hon. Secretary conducted the workshop. More than 140
students participated and got benefitted from the programme.
FREE LECTURE PROGRAMMES
SPIN ARC WELDING
Indian Welding Society joined hands with the Institution of Engineers, the Indian Institute of Welding,
Tiruchirappalli Branch & The Indian Institute of Metals in organising a lecture programme on “SPIN ARC
WELDING” by Mr. S V Prasad, Managing Director of Swastik Associates, and Tiruchy at the IEI building
on 21st January 2020.
-
Page 14 of 36
In his lecture Mr. Prasad said, “Spin arc welding utilises a unique weld torch in which the welding
electrode rotates in a circular motion at a high rate of speed.
Centrifugal force propels molten droplets across the arc creating a
consistent and sound weld bead. This enables high deposition rate
welding for significant increase in productivity”
He further said, “The process’s origins go back to the early 1980s
when Dick Roen, an engineer who worked with Martin Marietta,
had trouble welding certain aluminium alloys that were part of the solid rocket boosters for the space
programme. He invented the technology to weld hardened aluminium alloys literally in his basement.
Roen patented it in 1982, but that patent has since expired. The technology sat dormant for years until
several colleagues who knew Roen came together and formed Weld Revolution in 2012.
The technology, which works with any constant-voltage GMAW power source, is in the welding gun and
can be attached to any wire feeder. It’s designed for mechanized and robotic setups, and a kit is
available to adapt the system for hand welding. The gun itself has a motor that rotates the contact tip.
The controlled rotation occurs very quickly; typical settings are between 2,000 and 4,000 RPM. The
operator can set the spin diameter and speed.
As the spin diameter increases, the bead width increases. This process can be used for weld overlay or
surfacing also by varying the spin diameter. The system can rotate the wire clockwise or counter
clockwise, and which to choose usually depends on the weld direction to ensure the arc energy focuses
on the leading edge of the weld pool. If you’re welding left to right, you typically rotate the wire
clockwise; if you’re welding right to left, you rotate the wire counter clockwise.
One of the key benefits of the process is to be able to control the depth of penetration through the
rotation and the technology allows welding to occur out of position in more situations”.
Earlier Mr. S Singaravelu, zonal Vice Chairperson, SZ welcomed the gathering and introduced the
speaker Er. N. Rajasekaran, Hon. Secretary, IWS and Er. R Selvaraj, Hon. Secretary, IIW India, Tiruchy
branch felicitated the speaker.
DIGITAL IMAGE PROCESSING
On 4th February 2020, Mr. V Deepesh, Sr. Manager (NDT), BHEL
delivered a lecture on “Digital Image Processing – An Industrial
Radiographic Perspective” in the lecture programme jointly organised
by Indian Welding Society, Institution of Engineers, the Indian
Institute of Welding & The Indian Institute of Metals.
In his lecture he said, “With increased emphasis on product reliability
and with a generally renewed emphasis on cost control, it is natural that the NDT also should turn to
image processing as a potential method of improving the radiographic techniques. The questions being
asked usually concern the applicability of image processing for more certain detection of defects,
sometimes in the context of increasing the sampled population of an entire fabrication process at little
-
Page 15 of 36
increase in cost, sometimes in the context of making it possible for less experienced personnel to make
satisfactory examinations, sometimes simply in the context of obtaining better radiographic resolution.
In those applications where the principal desire is for higher throughput, the problem often becomes
one of automatic feature extraction and mensuration. Classically these problems can be approached by
means of either an optical image processor or an analysis in the digital computer. Optical methods have
the advantage of low cost and very high speed, but are often inflexible and are sometimes very difficult
to implement due to practical problems. Computerized methods can be very flexible, they can use very
powerful mathematical techniques, but usually are difficult to implement for very high throughput.
Recent technological developments in microprocessors and in electronic analog image analysers may
furnish the key to resolving the shortcomings of the two classical methods of image analysis”.
He further said, “Examples of applications of image processing to non-destructive testing include weld
inspection, dimensional verification of reactor fuel assemblies, inspection of fuel pellets for laser fusion
research, and, somewhat peripherally, medical radiography.
Digital image processing can contribute to an enhanced visualization. From endoscopic image
sequences, so called panoramic images can be computed, which show an overall view of a cavity and
allow for the check of an inspection result at a glance. By means of filtering and masking of the recorded
images, poorly exposed image portions, e.g. under exposed or over exposed, can be discarded. Thus
overall views with nearly homogeneous illumination level can be presented to the user”.
Earlier Er. S. Samidas, past chairman, IWS, SZ welcomed the gathering and introduced the speaker Er.
N. Rajasekaran, Hon. Secretary graced the occasion.
SKILL DEVELOPMENT IN WELDING
Mr. Venkatnarayanan, Chief Executive, Centroid Engineers India Pvt. Ltd.,
Coimbatore and Chairman of IWS, Coimbatore Centre delivered a lecture on
“Skill Development in Welding”, the contemporary topic on 18th February
2020. The well attended programme was organised by Indian Welding
Society, the Indian Institute of Welding, the Institution of Engineers, & The
Indian Institute of Metals. Following are the highlights of his lecture.
• Schooling does not assure employment but skill does.
• Skill development refers to the identification of skill gap and filling the gap to achieve the goal.
• Skill development is important in the overall development of a professional or a student.
He also explained in detail about various skill development initiatives of
Government of India. He also highlighted the role and services of AWS, WRI,
IIW, IIW (India), IWS, etc. in skill development for welding through various
programmes. Mr. R Selvaraj, Hon. Secretary of IIW India, Tiruchy felicitated the
speaker and presented the memento. Mr. N Rajasekaran, Hon. Secretary, IWS
graced the occasion.
-
Page 16 of 36
FEEDBACK From: MP Jain
Date: Mon, 6 Apr, 2020, 06:30
Subject: Re: IWS Journal Jan 2020 issue
To: Indian Welding Society
Cc: nrajas
Dear all at the editorial team of IWS Journal,
My compliments for bringing out an excellent edition of the journal. Its rich in content, visually appealing and well laid out. Keep the excellent
work going. MP Jain, New Delhi 9818279411.
From: yerriswamy wooluru
Date: Fri, 20 Mar, 2020, 10:05
Subject: Re: IWS Journals July 19 and Oct 19 Issues
To: Indian Welding Society
Dear Sir,
Thanks for sending the July 19 and Oct 19 issues of IWS journals…………….
………..I am very happy to note that Shri N Rajashekaran sir is Hon.Secretary, I would like to publish papers in the journal of IWS in association with
WRI engineers and researchers and use my expertise in Quality engineering as i did my PhD in Quality Engineering. (Robust Design and DOE) to
optimize welding process parameters of various welding Technologies over there.
Looking forward to associate with WRI experts and sharing my knowledge in preparation of journal articles.
Thanking you sir,
Dr. Yerriswamy Wooluru, Associate Professor, Industrial Engineering and Management Department, JSS Academy of Technical Education,
Bangalore, Karnataka state 560060, Mobile:9945065521
From: Honavar Electrodes Pvt. Ltd.
Date: Tue, Mar 17, 2020 at 2:29 PM
Subject: RE: IWS DAY 2020 - Message from President
To: ,
Mr. N. Rajasekaran,
Hon. Secretary (IWS).
Dear Mr. Rajasekaran,
Many thanks for your mail of the 13th instant with Greetings on the IWS Day 14th March 2020. I felt very happy after going through the inspiring
and informative message from our worthy President. It is so very heartening to read it.
a) Our Society has been chosen as the WINNER of PROFESSIONAL ASSOCIATION OF THE YEAR AWARD 2019 BY THE APAC association of Event Bank,
Singapore.
b) Starting an Add ON Course in welding technology for the mechanical engineering students.
c) Starting an Industry Based Elective in Welding with a Polytechnic in the south.
d) It is a novel idea to tap CSR funds under section 135 of Companies Act in the area of education, training and skill development through IWS.
Overall, all these efforts will enhance the status of IWS, and also win due recognition for Joining Technology on a very much wider plane from the
Government, Industry and Society. ……………………………………
……………I wish the President a highly successful term in leading the Society to greater heights.
Thanks & regards,
D. S. HONAVAR
DIRECTOR
HONAVAR ELECTRODES PVT. LTD.
-
Page 17 of 36
JOINING OF ALUMINIUM ALLOY TUBES WITH CARBON STEEL
TUBES BY MAGNETIC PULSE WELDING TECHNIQUE
1S. Muthukumaran, 2S. Malarvizhi, 3V. Balasubramanian & 4Bhavani Sankar Cherukuri 1, 2, 3 Centre for Materials Joining & Research (CEMAJOR)
Department of Manufacturing Engineering, Annamalai University 4Magpulse Technologies Private Limited, Peenya Industrial Estate, Bengaluru
Abstract
Joining of aluminium alloys with carbon mild steel using the fusion welding technique
is highly difficult because of the formation of solidification defects like, porosity, alloy
segregation, hot cracking, etc. To overcome these problems solid state welding
techniques such as explosive welding and magnetic pulse welding, can be used.
Magnetic pulse welding (MPW) is a solid-state welding process, in which joints are
made at overlap configuration at higher speed and cost effective. In this
investigation, dissimilar aluminium alloy AA 6063 T6 tube and Mild steel IS 1239 tube
were joined using MPW technique. A central composite design model was developed
for establishing the relationship between important MPW process parameters such
as stand-off distance (SoD), working length and voltage with the bonding strength
of the joints. Empirical relationships were established correlating the tensile shear
fracture load and interface hardness of the joints and MPW process parameters.
Response surface methodology was used for optimization of the MPW process
parameters. From the results, it is understood that the working length had significant
effect on the quality of magnetic pulse welded dissimilar joints.
Keywords: Magnetic Pulse Welding, Dissimilar Joint, Response Surface Methodology,
Tensile Shear Fracture Load.
1.0 INTRODUCTION
Lightweight construction and energy efficiency are having a strong impact on the new product
development (NPD). The recent engineering system should concentrate on developing the
ground-breaking lightweight design and, at the same time, the global environmental and
economic advantages of the entire product lifecycle (PLC). particularly for the automotive
industry the subject of lightweight design represents one of the most major innovation drivers
and technology trends [1]. The use of the steel and aluminium dual metallic welding structure
has become the preferred alternative to light weighting in industrial manufacturers, which surely
involves the connection between steel and aluminium. Researchers are from different countries
have perform exhaustive research on the connection between the structures of steel and
aluminium [2]. Much attention has been paid to joining different metals. In particular, steel and
-
Page 18 of 36
aluminium joining are key for fabricating multi component structures used in cars and ships [3].
In order to form a metallurgical bond, heating is required, but in the case of dissimilar-metal joints
(Al/Steel), a high heat input often leads to formation of brittle and continuous intermetallic
phases that might weaken the mechanical properties of the bond [4].
Magnetic Pulse Welding (MPW), which is considered as a ‘‘solid state welding process", Similar
to explosive welding [5], has increase the attention of the welding community since it enables to
join similar as well as dissimilar materials in microseconds, without the need for contact work
piece and welding consumables. MPW is closely analogous to explosive welding and relies on the
dynamic effects when the joining components collide at high impact speeds. When using the
cylindrical configuration, the parts to be joined are inserted concentrically into a coil shown in
Figure 1, leaving an acceleration gap. MPW uses an electromagnetic pulse of very short duration
(
-
Page 19 of 36
have greater influence on the tensile shear fracture load of the magnetic pulse welded joints were
identified.
2.2 Working limits of parameters
The experiment trial runs were carried out using 1 mm thick pipe of AA 6063 T6 and 1 mm pipe
of IS 1239 low carbon steel to find out feasible working limits of magnetic pulse welding
parameters. Different combination of parameters was used to carry out the trial runs. The welded
surface and weld quality were inspected to identify the working limits of the welding parameters
leading to the following observation. If the voltage was extended 12 kV there were the joint is
separated for, for voltage is greater than 16 kV, the flyer gets high deformation were observed
on the weld joints. If the voltage was less than 12 kV there were the joint is separated, for voltage
is greater than 16 kV aluminium tube is undergo higher deformation were observed on the
welded joints. If the stand-off distance was less than 0.5 mm the joint is separated (not welded)
for standoff distance greater than 2.5 mm the flyer aluminium gets (Impact placed) deformed. If
the working length was lower than 6.5 mm the joint is separated for working length greater than
8.5 mm the weld is separated were observed.
2.3 Development of design matrix
Based on the above condition the feasible limits of the parameters were chosen in a way that the
AA 6063t6 alloy and is 1239 should be welded without any weld defects. Among a wide range of
factors, three factors and fire levels central composite design matrix were selected to optimize
the experimental conditions Table -3 presents the range of factors consider and Table -4 shows
20 sets of coded conditions used to form design matrix. The method of designing such matrix is
introduced else were for the convenience of recording and processing experimental data, upper
and lower levels of the factors were coded as +1.682 and -1.682 respectively.
2.4 Experiments
The experiments solution heat treated AA 6063 T6 aluminium alloy of 1mm wall thickness the
length of 60mm, diameter- 30mm fixed and seam welded carbon steel of 1mm wall thickness the
length of 60mm as shown in Figure 1, lab joint consignation was prepared to fabricate MPW joints
and also SD is playing a manger change on steel tube diameter 27,26,25,24,23mm respectively.
The initial joint consignation was obtained by securing the tubes in position using High Density
Polyethylene (HDPE). The direction weld was normal to the aluminium positioned direction.
Single pulse was used to fabricate the joints.
The fabricated joints were sliced from the MPW joint by Electron Discharge Marching (EDM) to
attain required shape size, as shown in Figure 1(a). Each specimen three strips (samples)
prepared. Two tensile shear specimens were set to evaluate the tensile shear fracture load.
Photos of fabricated joints and samples are shown in Figure 2(b). Tensile shear fracture test was
carried out in an electromechanical controlled universal testing machine and the average values
of two results are presented in Table 4. One Sample were surface-ground using 120 grit size belt
with the help of a belt grinder, polished using grade 1000, grade 2000 and grade 2500 sandpaper.
-
Page 20 of 36
The specimens were further polished by using aluminium oxide. Macroscopic and microscopic
inspections are done by optical microscopy. The MPW joint profile (Macrographs and
Micrographs) as shown in Figure 3 and Figure 5.
2.5 Development of empirical relationship
Response surface methodology (RSM) is a collection of mathematical and statistical techniques
that is useful for analysing problems, in which a response of interest is influenced by several
variables and the objective is to optimize this response. The response function of the joint, tensile
shear fracture load (TSFL), is a function of Voltage (V), Stand-off distance (D), and Working length
(L) and it can be expressed as:
TSFL = f (V, D, L) (1)
The second order polynomial (regression) equation used to represent the response surface ‘Y’ is
given as:
Y = b0+∑bixi+∑biixi2+∑bijxixj+er (2)
and for three factors, the selected polynomial could be expressed as:
TSFL = { b0+ b1(V)+ b2(D)+ b3(L)+b11(V2) +b22(D
2) +b33(L2) +b12(VD) +b13(VL)+ b23(DL) } kN (3)
where b0 is the average of responses; bi and bij are the coefficients that depend on the respective
main and interaction effects of the parameters. In order to estimate the regression coefficients,
a number of experimental design techniques are available.
In this work, central composite design which precisely fits the second order response surface was
used. All the coefficients were obtained by applying central composite design using the Design
Expert statistical software package. After determining significant coefficients, the final
relationship was developed using only these coefficients. The empirical relationship to predict
tensile shear fracture load of magnetic pulse welded aluminium tube with carbon steel tubular
joints is given as:
TSFL = { -65.14 + 0.035 V + 8.88 D +1 6.85 L + 0.09 VD + 5×10-3VL - 0.85 DL - 9.96×10-3 (V)2
–1.14 (D)2 - 1.08636 (L)2 } kN
2.6 Checking adequacy of developed relationship
The capability of the developed relationship was tested using the analysis of variance technique
(ANOVA). In this technique, if the calculated Fratio value of the developed model is less than the
standard Fratio (from F-table) value at a desired level of confidence (95%), the model is adequate
within the confidence limit. The ANOVA test results are presented in Table 5. It is understood
that the developed relationship is passable at 95% confidence level.
The model F-value of 244.3 implies that the relationship is significant. There is only a 0.01%
chance that this large “model F-value” could occur due to noise. Values of “prob>F” less than
0.0500 indicate the relationship terms are significant. In this case, V, D, L, VD, VL, DL, V2, D2, and
-
Page 21 of 36
L2 are significant model terms. Values greater than 0.1000 indicate the relationship terms are not
significant. The “lack of fit F-value” of 1.39 implies that the lack of fit is not significant compared
to the pure error. Coefficient of determination “r2” is used to find how close the predicted and
experimental values lie. The value of “r2” for the above-developed relationship is also presented
in Table 5, which indicates high correlation existing between the experimental values and
predicted values. The “Pred. R-squared” of 0.99 is in reasonable agreement with the ‘adj R-
squared’ of 0.98. “Adeq precision” measures the signal to noise ratio.
3.0 OPTIMIZATION OF MPW PARAMETERS
The response surface methodology (RSM) was used as an optimization tool to search the
optimum values of the process variables. The empirical relationship developed in the previous
section was framed using the coded values. The optimization was done on coded values and then
converted to actual values. Design Expert statistical software package was used to optimize the
process variables. Under the optimum conditions, a maximum tensile shear fracture load of 2.359
kN was obtained.
Response surfaces were developed for the empirical relationship, taking two parameters in the
‘X’ and ‘Y’ axes and response in ‘Z’ axis. The response surfaces clearly indicate the optimal
response point. The optimum tensile shear strength of MP welded AA 6063 T6 to IS 1239 was
exhibited by the apex of the response surface, as shown in Figure 6(a, b & c).
Contour plots show distinctive circular mound shape which is indicative of possible independence
of factors with response to display the region of optimal factor settings. By generating contour
plots using software for response surface analysis, the optimum is located with reasonable
accuracy by characterizing the shape of the surface. If a contour patterning of circular shaped
contour occurs, it tends to suggest the independence of factor effects while elliptical contours
may indicate factor interactions. The optimum response for MP welded AA 6063 T6 tube to IS
1239 tube is shown in Figure 6 (d, e & f).
4.0 ANALYSIS OF RESPONSE GRAPHS AND CONTOUR PLOTS
RSM optimization technique developed 3D response surface graphs and contour plots are,
formed based on the developed model by considering one parameter in the middle level and the
other two parameters are variables.
Figure 4(a and d) shows the 3D response surface graph and contour plot, with increasing stand-
off distance at a given voltage, the TSFL fist increases to a maximum value and afterwards shown
a decrease. Standoff distance 0.5 mm to 1 mm and increase in voltage 12 kV to 15 kV, at the time
of collision, kinetic energy of the outer tube (AA 6063 T6) is lower due to lower standoff distance
due to that impact velocity is reduced and tensile shear fracture load is decreases. At standoff
distance 1 mm to 2 mm at a given voltage the maximum TSFL (2.35 kN) is achieved. In the case
the kinetic energy of the outer tube (AA 6063 T6) is increases at critical voltage converted to heat
by massive plastic deformation of the metals. This deformation affects the interface and vicinity,
-
Page 22 of 36
resulting in a significant temperature increase [11] and strain hardening effect also increases [12].
The temperature rise of the interface softens the metals [13], and in some cases, melts local
pockets or a thin continuous layer along the interface. In some cases, wavy interface morphology
appears with short-term periodicity. Standoff distance 2 mm to 2.5 mm at a given voltage, the
TSFL is decreases. In the case of increasing stand-off distance, it is directly proportional to the
angle of collision and kinetic energy of the flyer (aluminium). The plastically deformed metal with
increasing kinetic energy increasing the shearing effect and decreasing the stability of the flyer.
Its lead to decreases the TSFL. Figure 4 (b and e) shows 3D response surface graph and contour
plot, with increasing working length at a given voltage, the TSFL fist increases to a maximum value
and afterwards shown a decrease with working length is increases. Working length 6.5 mm to 7.5
mm and increase the TSFL, because of the flyer is at the open end and is located in the middle of
the field shaper or coil (where the magnetic flux density is maximum), this area is subjected to
the maximum magnetic pressure, concentrated on the centre of the coil and also the collision
velocity is higher. Its converted to heat by massive plastic deformation of the flyer metals.
Figure 4(c and f) shows the 3D response surface graph and contour plot, with increasing standoff
distance at a given working length, the TSFL fist increases to a maximum value and afterwards
shown a decrease.
The elements diffusion during MPW process by the high energy impact is expected. It is mainly
due to the sudden transformation from one metal to another one cross the interface that is the
primary term for the element diffusion. In addition, the permanent severe plastic deformation
for high velocity impact causes the transient process with high temperature and high pressure,
which makes for the mutual diffusion of basic elements across the interface. Therefore, more
than one factor simultaneously results in the basic elements diffusion during MPW process. One
small region was chosen to conduct the small region scanning energy spectrum analysis, as shown
in Figure 6 (b). The mass percent of Fe and Al elements are 21.18% and 78%, respectively. And
also, the multi-direction micro-cracks and the micro-apertures present in the transition zone, as
shown in the Figure 6 (a). The severe shear deformation by the high velocity collision causes high
density dislocations and its crossing and irreversible climbing, which produces dense voids and
vacancies. A little air in the initial gap is trapped and cannot escape in time during the MPW
process, which generates the voids. The transient melt and solidification process because of the
severe plastic deformation results in the micro-voids and high impact energy damages the welded
interface, as shown in the Figure 6(a).
5.0 CONCLUSIONS
1) An empirical relationship was developed to predict tensile shear fracture load (TSFL) of
magnetic pulse welded AA 6063 Al alloy tube with IS 1239 carbon steel tube using response
surface methodology. The developed relationship can be effectively used to predict the
TSFL of magnetic pulse welded joints at 95% confidence level.
2) A maximum TSFL of 2.398 kN was obtained under the welding condition of 13.14 kV, 1.62
-
Page 23 of 36
SoD, 7.32 L, which is the optimum MP welding condition for AA 6063 T6 with IS 1239 and
confirmed by RSM.
3) Working length has the greatest influence on TSFL, followed by applied voltage, and stand-
off distance.
4) The metallurgical joint consists of two interfaces, one transition zone and two basic metals.
The mutual diffusion of Fe and Al elements occurs across the interface and in the transition
zone. The multi-direction micro-cracks and the micro-apertures present in the transition
zone.
ACKNOWLEDGEMENTS
The first author wishes to record sincere thanks to M/s. Magpulse Technologies Pvt Ltd, Peenya Industrial Estate,
Bengaluru for the financial support provided through Magpulse Research Fellowship and also providing welding
facility to carry out this investigation.
References
[1] Jerome Kaspar, Michael Vielhaber. " Sustainable Lightweight Design – Relevance and Impact on the Product
Development & Lifecycle Process". Procedia Manufacturing 8 ( 2017 ) 409 – 416.
[2] Xu Zhidan, Cui Junjia, Yu Haiping, Li Chunfeng, " Research on the impact velocity of magnetic impulse welding of
pipe fitting". Materials and Design 49 (2013) 736–745
[3] Yusuke Aizawa, Junto Nishiwaki, Yohei Harada, Shinji Muraishi, Shinji Kumai. "Experimental and numerical analysis
of the formation behavior of intermediate layers at explosive welded Al/Fe joint interfaces". Journal of Manufacturing
Processes 24 (2016) 100–106
[4] Yu, H., Fan, Z., Li, C., "Magnetic pulse cladding of aluminum alloy on mild steel tube", Journal of Materials Processing
Technology (2013), http://dx.doi.org/10.1016/j.jmatprotec.2013.08.013.
[5] A. Stern, V. Shribman, A. Ben-Artzy, and M. Aizenshtein, " Interface Phenomena and Bonding Mechanism in
Magnetic Pulse Welding". JMEPEG (2014) 23:3449–3458 @ ASM International.
[6] R.N. Raoelison, N. Buiron, M. Rachik, D. Haye, G. Franz, " Efficient welding conditions in magnetic pulse welding
process". journal of Manufacturing Processes 14 (2012) 372–377.
[7] K.J. Lee, K. Shinji, A. Takashi, and T. Aizawa, Interfacial Microstruc- ture and Strength of Steel/Aluminum Alloy Lap
Joint Fabricated by Magnetic Pressure Seam Welding, Mater. Sci. Eng. A, 2007, 471(1-2), p 95–101.
[8]Lanza, M.; Lauro, A.; Scanavino, S.Fabrication and weldability in structures. AL Alumin. Alloys. 2001, 13,80–86.
[9] Haferkamp, H.; Niemeyer, M.; Dilthey, U.; Trager, G. Laser and electron beam welding of magnesium materials.
Weld. Cutt. 2000, 52, 178–180. Materials 2014, 7 3753
[10] Chudakov VA, Khrenov KK, Sergeeva YA, Gordan GN. The effect of temperature to which the material is heated on
the process of formation of intermetallic compound in magnetic pulse welding. Weld Prod 1980;27(9):23–5.
[11] Hampel H, Richter U. Formation of interface waves in dependence of the explosive welding parameters. In:
International conference on high energy rate fabrication, Leeds; 1981. p. 89–99.
[12] Szecket A. The triggering controlling of stable interface condition in explosive welding. Mater Sci Eng 1983;57:149–
54.
[13] Jaramillo D, Inal OT, Szecket A. On the transition from waveless to a wavy interface in explosive welding. J Mater
Sci 1987;22:3143–7.
-
Page 24 of 36
Table 1 Chemical composition wt% of the base metals
Material Si Mn Fe C Al
AA 6063 T6 0.25 0.5 0.3 98.6
IS 1239 1.4 98.34 0.2
Table 2. Mechanical properties of base metals
Materials 0.2% Yield strength Tensile strength (MPa) Hardness (HV 0.025 kgf)
Elongation in 50mm gauge length (%)
AA 6063 T6 214 240 83 12
IS 1239 320 442 125 20
Table 3: Important MPW parameters and their working range
No Parameter Notation Unit Levels
-1.682 -1.00 0 +1.00 +1.682
1 Voltage V kV 12 13 14 15 16
2 Stand-off-distance D mm 0.50 1.00 1.50 2.00 2.50
3 Working Length L mm 6.50 7.00 7.50 8.00 8.50
Table 4 Design matrix and experimental results
Expt. No Coded Values Actual Values TSFL (kN)
V D L V D L 1 -1 -1 -1 13 1 7 1.73
2 +1 -1 -1 15 1 7 1.5
3 -1 +1 -1 13 2 7 2.35
4 +1 +1 -1 15 2 7 2.32
5 -1 -1 +1 13 1 8 1.5
6 +1 -1 +1 15 1 8 1.3
7 -1 +1 +1 13 2 8 1.29
8 +1 +1 +1 15 2 8 1.25
9 -1.50 0 0 12 1.5 7.5 2.34
10 +1.50 0 0 16 1.5 7.5 2.07
11 0 -1.50 0 14 0.5 7.5 1.1
12 0 +1.50 0 14 2.5 7.5 1.76
13 0 0 -1.50 14 1.5 6.5 2.04
14 0 0 +1.50 14 1.5 8.5 0.90
15 0 0 0 14 1.5 7.5 2.1
-
Page 25 of 36
Table 5 ANOVA test results
Source Sum of squares df Mean square
F value P Value (Prob>F)
Model 4.36 9 0.48 244.3 < 0.0001 V-V 0.069 1 0.069 34.81 0.0002 D-D 0.38 1 0.38 193.64 < 0.0001 L-L 1.47 1 1.47 740.22 < 0.0001 V-D 0.016 1 0.016 8.17 0.0170 V-L 5E-5 1 5E-5 0.025 0.8770 D-L 0.36 1 0.36 182.18 < 0.0001 V2 1.43E-3 1 1.43E-3 0.72 0.4157 D2 1.18 1 1.18 593.35 < 0.0001 L2 1.06 1 1.06 536.07 < 0.0001
Residual 0.020 10 1.983E-3 Lack of fit 0.012 5 2.309E-3 1.39 0.3622 Pure error 8.283E-3 5 1.657E-3 Cor total 4.38 19
Standard Deviation 0.045 R-Squared 0.99
Mean 1.84 Adj R-Squared
0.99
C.V % 2.42 Pred R-Squared
0.98
Press 0.100 Adeq Precision
47.284
Fig 1 Dimensions of joint configuration (Unit: mm) Fig 2 Dimensions of TSFL specimen: (a) Schematic diagram of extraction of tensile specimens; (b) MPW extracted TSFL specimen
(a) (a)
(b) (b)
-
Page 26 of 36
Experiment No: 1 [ 13 kV, 1 SoD, 7 L]
Experiment No: 3 [ 13 kV, 2 SoD, 7 L]
Expt No: 4 [ 15 kV, 2 SoD, 7L]
Expt No: 9 [ 12kV, 1.5 SoD, 7.5 L]
Fig 3 Macrograph of some of the MPW joints
-
Page 27 of 36
TSFL
(a
)
(e) (b)
(f) (c)
(d) TS
FL
TSFL
-
Page 28 of 36
Fig 4 Contour plots and Response graphs for MPW AA 6063 T6 with IS 1239
Expt No Parameters Micrographs
200 X 500 X
2
V = 15 kV, D = 1 SoD, L = 7 L
3
V = 13 kV, D = 2 SoD, L = 7 L
4
V = 15 kV, D = 2 SoD, L = 7 L
9
V = 12 kV, D = 1.5 SoD, L = 7.5 L
Fig 5 Micrographs of some of the MPW joints
-
Page 29 of 36
Fig 6 MPW Interface Scanning Energy Spectrum Analysis Result
(a) (b)
-
Page 30 of 36
BEHAVIOUR OF LASER KEYHOLE WELDING INDUCED POROSITIES IN
THE CORROSIVE ENVIRONMENT
M. Umar & P. Sathiya*
Department of Production Engineering, National Institute of Technology, Tiruchirappalli, Tamilnadu, India-
620015.
*Corresponding Author: [email protected]; Tel.: +914312503510; Fax: +914312500133
ABSTRACT
In this work, the keyhole induced porosities were produced on a marine grade 5083
aluminium alloy using Yb: YAG laser beam welding process. In order to understand
the behaviour of those porosities with the corrosive medium, the surface containing
porosities were immersed in the chloride solution and its corrosion parameters were
observed using potentio dynamic polarization method. After corrosion, the corroded
surface was studied under scanning electron microscope and observed a curious
result that, on the corroded surface two porosities were affected by the chloride
solution and one remained undamaged. It was identified that the outer surface of
that intact porosity comprised of a higher concentration of Fe and Mn particles which
are cathodic. Hence, the intact porosity acted itself as a localized cathode and
induced selective dissolution of aluminium around it and prevented self-pitting. The
results indicated that, unlike the hydrogen gas porosities, the keyhole induced
porosity contains a higher amount of cathodic particles can remain undamaged even
in the corrosive environment.
Keywords: Aluminium; Laser Welding; Porosity; Corrosion; Atomic Force Microscopy.
1.0 INTRODUCTION
The AA5083 Aluminium alloys are the most widely used material in shipbuilding due to their
excellent corrosion resistance and the oxide layer (Al2O3) forming over the alloy surface protects
it from structural degradation [1, 2]. However, the heat added during welding of aluminium alloys
dramatically reduces its corrosion resistance by altering its metallurgical characteristics like
precipitation of anodic second phase particles such as Mg2Si and Al3Mg2 in the fusion zone (FZ)
and heat affected zone (HAZ). Application of laser beam welding (LBW) is one of the possible
alternates to minimize the common problems associated with other joining processes and still,
porosity remains a severe issue in LBW of AA5083 aluminium alloys. The keyhole induced porosity
is one of the two primary mechanisms associated with aluminium welding and the other
mechanism is driven by the low boiling-point elements such as magnesium and hydrogen. The
shape of these porosities are perfectly spherical and often seen in aluminium weldments if the
amount of hydrogen is not controlled [3-6]. Fuyong et al. [7] investigated the effect of casting
porosity on the corrosion and found that specimens have porosity experienced a higher corrosion
rate due to the partial breakdown of passive film and acceleration of micro-galvanic coupling.
mailto:[email protected]
-
Page 31 of 36
Zhang et al. [8] revealed the significance of porosity in long-term corrosion behaviour of coated
mild steel. It was observed that the porosity defects increased the rate of corrosion by decreasing
the stability of passive film and increasing the passive current density. Yafei et al. [9] have
reported the role of inclusions in pit initiation and propagation in pipeline steel. The inclusions
with distinctive compositions of Al-Mg-S-O-Ca were found to be responsible for the formation of
circular pits and the corrosion pits were similar to the pitting morphology of nanostructured Al-
Mg alloys in alkaline solution as reported by Mala and Constance [10].
Though the role of porosity in corrosion and its formation mechanisms were presented in the
previous studies, the behaviour of laser keyhole induced porosities in severe conditions have not
been reported elsewhere. Hence, in this work, the keyhole induced porosities were produced on
a 5083 aluminium alloy using LBW process and its interaction behaviour with the corrosive
medium was investigated. The surface consists of porosities were exposed in the 3.5% NaCl
solution and the data were obtained through the potentiodynamic polarization method.
Furthermore, the corrosion surface morphology was characterized using various advanced
microscopy techniques and the activities of porosity in the chloride solution were discussed.
2.0 MATERIALS AND METHODS
In order to produce the keyhole induced porosities, a butt joint was made on a 3 mm thick
AA5083-H111 alloy sheet using a 6-axis KUKA robot Yb: YAG laser beam welding machine with
the welding process conditions such as laser power of 2 kW, welding speed of 200 mm/min and
a spot diameter of 0.369 mm. Pure argon was used as a shielding gas with the flow rate of 20 lpm.
The weight % of major alloying elements existing in the base alloy are as follows: Cu (0.02), Si
(0.12), Fe (0.4), Mg (4.57), Mn (0.94), Cr (0.06), Ni (0.01), Ti (0.027), Zn (0.02) and balanced with
Aluminium. After welding, the samples were cut, ground, polished and etched with Poulton's
solution for microstructural evaluation. To obtain the corrosion parameters, the
potentiodynamic polarization test was performed in an IVIUM electrochemical workstation
equipped with a three-electrode system (reference, counter and working electrode). All the
electrodes were immersed in the 3.5% NaCl solution and the potential voltage was varied
between -1 V/SCE and +1 V/SCE with the scan rate of 1 mV/s. From the polarization curve, the
data were acquired in terms of corrosion potential (Ecorr) and pitting potential (Epit) and,
thereby, the width of the passive region (∆Epit) was calculated using the below-mentioned
equation:
∆Epit = Epit - Ecorr (mV) (Eq 1)
The microstructural and elemental features of the weld and porosity were observed before and
after corrosion using a scanning electron microscope (SEM) coupled with an energy dispersive
spectrometry (EDS). Atomic force microscopy (AFM) technique was used to examine the pitting
morphology of corroded surface as well as the porosity.
3.0 RESULTS AND DISCUSSION
It can be seen from Fig. 1 that the cold working process produced elongated grains in the base
metal (BM) microstructure with a nonuniform dispersion of second phase particles such as
Al3Mg2, Mg2Si, Al6Mn or Al6 (Fe,Mn) and α-Al(Mn,Fe)Si [4, 11-15]. The interface between FZ
-
Page 32 of 36
and BM experienced grain growth whereas the transformation of columnar dendrites to equiaxed
dendrites ensued from the fusion boundary to the weld pool centre was attributed by the
different heating/cooling rates. The temperature gradient (G) is maximum at the fusion boundary
and minimum at the weld centre. On the contrary, the grain growth rate (R) is minimum at the
fusion boundary and maximum at the weld centre [4-6]. As a result, the degree of undercooling
(G/R) gradually increases from the weld centre to the fusion boundary.
Fig. 1 SEM micrograph showing the existence of porosity in the CDZ of FZ.
This leads to the formation of equiaxed dendrites in the middle of the FZ and columnar dendrites
facing perpendicular to the fusion boundary [5]. The encircled portion in Fig.1 shows a keyhole
induced porosity entrapped at the columnar dendrite zone (CDZ) or bottom of the FZ during rapid
solidification. It is evident that a bubble (keyhole induced porosity) was formed during LBW due
to the instability of keyhole and moved to the rear side of the molten pool and stayed in at the
bottom of the FZ without getting collapsed with the reformed keyhole. This is due to the
recirculation flow of the molten pool at the front wall and insufficient temperature to float the
bubbles to the top surface of the molten pool [16]. Also, it is believed that the high thermal
gradient induced Marangoni flow is responsible for the recirculation at the melting front and
other researchers in [5,6,15,16] were reported similar mechanisms. These process induced
porosities are sized at the micron level and are often seen at the bottom as well as the toe of the
weld [5,6]. The approximate diameter of the porosity observed in this study was 62.102 μm and
it is comparable with previously reported results [6,12,15].
-
Page 33 of 36
Fig. 2 Potentiodynamic polarization curve.
Afterward, the FZ had porosities was exposed to the chloride solution and the electrochemical
measurements were taken. The corrosion parameters (Ecorr = -1050 mV, Epit = -728 mV, ∆Epit =
322 mV) were determined from the Tafel curve shown in Fig. 2. It is indicating that the stable
passive film and cathodic particles present on the weld surface reasonably delayed the pit
initiation though porosities were present. Since the cathodic elements have higher corrosion
potential than the alloy matrix, the cathodic particles present in the alloy surface usually resist
or delays pit initiation during corrosion [7,10].
Fig. 3 Corrosion mechanism and surface feature of porosities: (a) SEM image of the corroded
surface showing dissolved and intact porosity. (b) The 3-D image observed through AFM showing
unaffected surface of 3rd porosity. (c) Profile extraction curve is showing pit measurements.
The presence of Fe and Mn-rich particles or intermetallics (Al6(Fe,Mn)) on the 5083-alloy surface
induces localized cathodic reaction which increases the width of passive region and results in
noble corrosion resistance [17].
In addition, the corroded surface was studied under SEM and the resultant image is shown in Fig.
3a. It is evident that the alloy matrix had undergone localized alkaline corrosion and got corroded
severely than the porosities due to its anodic nature. The pits were formed at various sites and
propagated along the grain boundaries caused an intensive pitting attack through which the
substrate got corroded thoroughly. The shape and distribution of pits are related to the
electrochemical nature of the elements present in the alloy surface [17]. In Fig. 3a, the points 1
and 2 indicate the traces of porosities that are dissolved in the chloride solution and left a cup-
shaped depression whereas point 3 signifies a spherical porosity which remains undamaged.
According to the investigations [7-12], a porosity or an inclusion present on the alloy surface
induces severe localized corrosion and maximizes the rate of corrosion. The porosity formed
between the passive film and the substrate could act as a direct path for the chloride solution to
penetrate and interact with the subsurface and results in severe corrosion [8]. The former
-
Page 34 of 36
mechanism was evident in the case of porosities 1 and 2 in which the chloride solution used them
as a channel to reach the substrate and finally corroded the substrate as well as the porosities.
In order to verify the existence and surface features of unaffected porosity, the corroded surface
was analysed through AFM and the results are shown in Fig. 3(b-c). It is evident from the profile
extraction curve that (see Fig. 3c), there was no sign of pitting on the porosity surface and the
curve was somehow replicating the top surface of it. However, a very few micron level ups and
downs are there on the curve and the tribological features of porosity were responsible for that.
The surface of keyhole-induced porosities could be irregular due to the traces of fluid flow
present on the outer wall whereas the hydrogen-induced porosities have smooth surfaces [16].
Some deeper pits are evident in the nearby region (see Fig. 3b) and anodic dissolution of major
alloying elements such as Al and Mg could be caused it. The pits formed nearby porosities might
be attributed to the localized rise in pH around cathodic particles generating hydroxyl ions which
dissolve anodic inclusions [16].
Fig. 4 EDS analysis on the intact porosity. (a-f) Mapping results. (g and h) Point analysis result.
Still, the fact behind the existence of porosity 3 even after corrosion remained concealed until
the EDS analysis was performed on it. The Figs. 4(a-f) are showing the results of EDS mapping
-
Page 35 of 36
analysis and it is evident that the porosity surface comprised of a higher concentration of cathodic
particles like Fe and Mn whereas a minimal amount of Mg was detected on it. The vaporization
of Mg during keyhole welding could be the reason for it. The dispersion of Fe and Mn were
identical on the porosity surface (see Fig. 4e and 4f) while a random distribution of other
elements can be seen in Fig. 4(b-d). The former results were verified with the EDS point analysis
and it confirms that a higher amount of Fe (16.60 %) and Mn (10.45 %) particles were existing on
the porosity surface which is quite significant. The reason behind this accumulation of Fe and Mn
particles on the porosity surface were not clear at the moment. In general, the Fe and Mn
particles are cathodic in nature and resists the pit propagation intensely [10-12, 15]. Since the
outer surface of porosity contains a higher concentration of cathodic Mn and Fe particles, it acted
itself as a localized cathode and induced galvanic coupling between the porosity and aluminium
matrix which led to the selective dissolution of Al around it. This detrimental effect caused a
severe corrosion attack at the interface region and produced deeper pits [7,10]. Also, the
accumulation of oxide particles occurred at the interface region (see Fig. 4d) due to the oxygen
reduction on the porosity surface during cathodic reaction with the sequential growth of
hydroxide anion [7,10,12]:
O2 + 2H2O + 4e 4OH (Eq 2)
The migration of chloride ions from the solution towards the anodic sites was reported as a
significant factor in this occurrence [9]. Hence, based on the results observed, it is identified that
the keyhole induced porosity composed of cathodic particles can resist corrosion and remains
undamaged.
4.0 CONCLUSION
The keyhole induced porosities were produced on a marine grade 5083 aluminium alloy and the
interaction behaviour of those porosities with chloride the solution was analysed using various
microscopy techniques.
• The corrosion resistance of laser keyhole-induced porosities is different from hydrogen gas
porosity.
• The corrosion potential of porosities depending on its surface composition.
• The porosity comprised of a higher concentration of Fe and Mn particles can act as a
localized cathode and induce selective dissolution of aluminum around it and prevent self-
pitting.
• This study suggests that unlike the hydrogen gas porosity, the keyhole induced porosity
contains a higher amount of cathodic particles can remain undamaged in the alloy surface
even after corrosion.
ACKNOWLEDGMENT
The authors would like to express their most profound appreciation and sincere thanks to the
Department of Science and Technology - Science and Engineering Research Board (DST-SERB),
New Delhi, India, for financially supporting this entire research work, under the sponsored
research project sanctioned No.SB/EMEQ-168/2014, dated 29-01-2016.
-
Page 36 of 36
REFERENCES
[1] Elisa Canepa, Roberto Stifanese, Lorenzo Merotto, Pierluigi Traverso, Mar. Struct. 2018 59, 271.
[2] R. Goswami, S.B. Qadri, Mater. Lett. 2017, 200, 21.
[3] Yousuke Kawahito, HongzeWang, Scr. Mater. 2018, 154, 73.
[4] C. Menzemer, P.C. Lam, T.S. Srivatsan, C.F. Wittel, Mater. Lett. 1999, 41, 192.
[5] Lijin Huang, Dongsheng Wu, Xueming Hua, Shichao Liu, Zhao Jiang, Fang Li, HuanWang, Shaojian Shi, J. Manuf. Process.
2018, 31, 514.
[6] Fuyong Cao, Zhiming Shi, Guang-Ling Song, Ming Liu, Matthew S. Dargusch, Andrej Atrens, Corros. Sci. 2015, 94, 255.
[7] S.D. Zhang, J. Wu, W.B. Qi, J.Q. Wang, Corros. Sci. 2016, 110, 57.
[8] Yafei Wang, Guangxu Cheng, Wei Wu, Yun Li, Corros. Sci. 2018, 130, 252.
[9] Mala M. Sharma, Constance W. Ziemian, J. Mater. Eng. Perform. 2008, 17, 870.
[10] Weijia Gong, Hailong Zhang, Congfeng Wu, Hang Tian, Xitao Wang, Corros. Sci. 2013, 77, 391.
[11] S.J. Garcia Vergara, P. Skeldon, G.E. Thompson, H. Habazaki, Corros. Sci. 2007, 49, 3772.
[12] Gaosong Yi, Binhan Sun, Jonathan D. Poplawsky, Yakun Zhu, Michael L. Free, J. Alloys Compd. 2018, 740, 461.
[13] Ramasis Goswami, Ronald L. Holtz, Metall. Mater. Trans. A. 2013, 44A, 1279.
[14] R. Goswami, G. Spanos, P.S. Pao, R.L. Holtz, Mate. Sci. Eng. A. 2010, 527, 1089.
[15] Lijin Huang, Xueming Hua, Dongsheng Wu, Li Fang, Yan Cai, Youxiong Ye, J. Manuf. Process. 2018, 33, 43.
[16] Runqi Lin, Hui-ping Wang, Fenggui Lu, Joshua Solomon, Blair E. Carlson, Int. J. Heat Mass Trans. 2017, 108, 244.
[17] Mustafa Umar, Paulraj Sathiya, Adv. Eng. Mater. 2018, 1701147.
WE APPEAL TO EVERY MEMBER TO ENROLL ONE MORE
LIFE MEMBER TO IWS.
TO DOWNLOAD APPLICATION FORM VISIT TO OUR WEB
SITES
www.iws.org.in www. iwsevents.com
LET US JOIN IN THE MOVEMENT AND STRENGTHEN IWS