2nd South Africa Metal Casting Conf. - Foundry-Planet Ltd. · M. E. Moussa a,*, M. A. Waly a, A. A....

M. E. Moussa a,*, M. A. Waly a, A. A. Nofal a

By

aCasting Technology Lab. , Manufacturing Technology Dept., CMRDI

2nd South Africa Metal Casting Conf. March 14-17, 2017

* [email protected]

Casting technology and development of magnesium alloys

for industrial applications

• Experience of CMRDI in Mg Casting Technology

Outlines

• The Future Trends

• Magnesium Alloys as Engineering Materials

Magnesium Alloys as Engineering Materials

• Lightweight alloys ( density ~1.8 g/cm3). • High specific strength. • Good castability & machinability. • High damping properties. • Good weldability under inert gases. • Low corrosion resistance (Implant applications) • Integrated recycling possible.

Benefits

•Melt oxidation and burning. • Low corrosion resistance (electrode potential v = -2.31 V). • Limited cold workability and toughness (hcp structure). • Limited creep resistance (Tm =650°C).

Drawbacks

Major

alloying

element,

Al

Secondary

alloying

element,

Zn

wt% of major

element,

9.4-8.6 wt%

wt% of

secondary

element,

1.4-0.6 wt%

Alloying element Letter

Aluminum

Copper

Rare earth

metals

Thorium

Zirconium

Lithium

Manganese

Silver

Silicon

Yttrium

Zinc

A

C

E

H

K

L

M

Q

S

W

Z

AZ91C-T4

Designation for

similar alloys

registered

ASTM,C

solution

heat-

treated of

The alloy

Note: heat-treatment conditions are specified similar to those of Al alloys.

ASTM Designation System of Magnesium Alloys

Magnesium Alloys Development

Sand casting

Applications of Magnesium Alloys

Automotive Applications Non Automotive Applications

Cam cover

Door-Lupo

Steering wheel

Transmission

housing Bone plates

Camera housings

Laptop housings Airplanes


Transfer case

Mg=11.4 kg

Steel=15.6 kg

Wt. Reduction= 28%

Instrument panel

Mg=1.8 kg

Steel=5 kg

Wt. Reduction= 64%

Car seat frame

Mg=1.8 kg

Steel=5 kg

Wt. Reduction= 64%

Lift gate

Mg=3.2 kg

Steel=5.5 kg

Wt. Reduction= 42%

Steering column

Mg=1.4 kg

Steel=2.3 kg

Wt. Reduction= 40%

Steering wheel core

Mg=0.9 kg

Steel=1.4 kg

Wt. Reduction= 33%

Door inner

Mg=5.4 kg

Steel=8.2 kg

Wt. Reduction= 33%

Engine

Mg=16 kg

Al=22 kg

Cast iron=60 kg

Wt. Reduction=22 to 70%

Magnesium alloys must be melted under covering and cleaning fluxes, to avoid oxidation losses and to remove inclusions. Protective Methods

Melting flux

• Closed crucible- A mixture of

chlorides such as (20% KCl, 50%

Mg2Cl, and 15% CaF2)

•open crucible- A mixture of

chlorides such as (55% KCl, 34%

Mg2Cl, 9% BaCl2 and 2% CaF2 )

•5–10% of MAGREX 60

Flux-less melting

• A protective gases mixture such

as

Sulfur hexafluoride, SF6 + CO2 or

Hydrofluoro carbon gas + CO2

Melting Process

Magnesium Melting

Poor Protection Good Protection

(CO2+ 1Vol.%SF6)

Magnesium Melting

Graphite crucible Steel crucible

Magnesium Casting Technology Sand casting

Sand Mixture

Magnesium Casting Technology

High pressure die casting

Cold chamber machine Hot chamber machine

Low pressure die casting Semi-solid casting Lost foam casting

©2003 B

roo

ks/

Co

le, a

div

isio

n o

f T

ho

mso

n L

earn

ing,

Inc.

T

ho

mso

n L

earn

ing

™ i

s a

trad

emar

k u

sed h

erei

n u

nder

lic

ense

.

Microstructure of cast alloys

Grain Refinement

Microstructure of Cast Alloys

Al-Free Alloys

Such as ZE41, ZK60

A low level of zirconium

has been identified as

an efficient grain refiner

Al-Containing Alloys

Such as AZ91, AM50

Several methods such as superheating,

carbon addition, the elfinal process,

solute elements (Sr, B, Ca, Sb, Ce), particles addition (Al4C3 , AlN, SiC)

and agitation treatment.

Note, The effective grain refiners for the Al- Containing Mg alloys still remain as an active research topic.

Grain Refinement of Mg Alloys

Experience of CMRDI in Mg Casting Technology

Grain refinement of AZ91 magnesium alloy under solidification

of ultrasonic treatment ) M.Sc. Thesis “2007-2010”

With UST and B addition

Without UST


Effect of Ceramic Mould Cavity Thickness on the Microstructure

and Hardness of AZ91 Magnesium Alloy (internal project since 2011)

Wax pattern

tree

Primary

ceramic layer

Secondary

ceramic layer

Back-up

ceramic layer

Cast

product

Ceramic Mould Dewaxing

Goal: the removal of the wax pattern

leaving a hollow shell.

Operating conditions:

• Steam temperature 180°C.

• Working pressure 9 bar.

• Applied time 45 minutes.

Q

Q

Q

Q

Q Q

Q

Steam autoclave

Mould preheating furnace

Ceramic Mould Fireing

Goal: transfer of amorphous type of ceramic

binder layer into a crystalline+ removal of

volatiles matters (waxes remains).

Operating conditions: Shells are fired at 900 oC

for 3 hours and then furnace cooled.

Melting and Casting

(Pouring temp. = 720 ± 10 oC)

(Preheating temp. = 300 ± 10 oC)

Protective gases inlet

(CF3CH2F, HFC-134a+ CO2)

Melt

Electrical resistance

furnace

XRD Pattern

0

1000

2000

3000

4000

5000

6000

7000

8000

20 25 30 35 40 45 50 55 60

Angle, 2θ (Deg.)

Inte

nsi

ty,

(a.

u)

Mg

◊ Mg17 Al12

5mm

10 mm

20 mm



and Hardness of AZ91 Magnesium Alloy. Mould

thickness

(internal project since 2011)

Gra

in s

ize,

µm

Ceramic mould cavity thickness, mm



and Hardness of AZ91 Magnesium Alloy.


Bri

nell

hard

ness

, H

B

Ceramic mold cavity thickness, mm



and Hardness of AZ91 Magnesium Alloy.


M V Without treatment

Casting technology of Mg-3Zn-0.8Ca under application of

mechanical vibration (MV) and ultrasonic vibration (USV) (internal project since 2012)


USV

Conventional casting

200X

Semi-solid casting

of AZ91+1wt%Ca


Semi solid casting of AZ91-1wt%Ca (internal project since 2012)

Without protection

Protection with addition

of 2wt% CaO

Under protective gases

mixture


Casting Technology of Non-Flammable Magnesium AZ91 Alloy



Casting Technology of Non-Flammable Magnesium AZ91 Alloy

(internal project since 2014) A

ver

ag

e si

ze o

f α

Mg g

rain

Ultrasonic

generator


The combined effect of high-intensity ultrasonic treatment (HIUST)

and 0.3 wt.%Ca addition on modification of primary Mg2Si and

mechanical properties in the hypereutectic Mg–5 wt.%Si alloy PhD Thesis “2011-2015”

wi

wo

Switch of Switch on

F= 21.45 KHz،

PMax. =5 KW

Without

HIUST

With HIUST

TP = 800 oC TP = 800 oC, Vt= 90 s

Cavitation

Micro-jets

Shock waves Acoustic streaming

Dendritic

morphology of

primary Mg2Si

Polyhedral shape of

primary Mg2Si

Combined effect HIUST & 0.3 Ca addition on Mg-5 wt.%Si

Cavition bubble

growth in negative

pressure (tension

portion)

Cavition bubble

collapse in postive

pressure

(compression

portion)

Maximum bubble size

(a) Without treatment

(b) HIUST

(c) 0.3wt.%Ca addition

(d) Combined HIUST&0.3wt.%Ca addition

The chemical composition of prepared alloy (wt.%)


Without HIUST HIUST, 800 oC

Primary Mg2Si

Mg halos

Eutectic

(Mg2Si+Mg)

HIUST

Without

HIUST 0.3 wt.%Ca addition Combined effect of

HIUST&0.3 wt.%Ca

addition



A 90% decrease in average size of

primary Mg2Si could be achieved with

HIUST+ 0.3 wt%Ca addition.

Without

treatment

With HIUST

With 0.3wt.%Ca

addition

With combined

HIUST&

0.3wt.%Ca

addition

FESEM Micrograph, EDS Line Scan & Elemental Mapping of

Mg, Si & Ca (without & with HIUST)

PM+CM: HIUST+Ca Addition (Tensile Properties)

60% increase in UTS and a 70% increase in elongation could be

achieved with HIUST+ 0.3 wt%Ca addition.

PM+CM: HIUST+Ca Addition (Vickers Hardness)

50% increase in hardness could be achieved with

HIUST+ 0.3 wt%Ca addition.

PM+CM: HIUST+Ca Addition (Wear Properties at V= 0.3 m/s for 10 min)

Publications of Our Team in CMRDI in Field of Casting Technology &

Development of Mg Alloys

(1) The UST has a significant effect on the grain refinement of primary αMg grains

and improvement of mechanical properties for the AZ91 magnesium alloy during

the solidification process.

(2) Investment casting is a feasible process to produce casting of AZ91 magnesium alloy

under condition of using zirconia as primary layer to avoid any reaction with AZ91

magnesium alloy.

(3) Semisolid casting is a feasible process to produce casting of AZ91+1wt.%Ca

magnesium alloy with using slope cooling plate.

(4) Ultrasonic and mechanical vibration treatment obviously modified the

microstructure of Mg-3Zn-0.8Ca biodegradable alloy. Grain refinement was

obtained under these conditions.

(6) The combined effect of HIUST & Ca addition has a significant effect on the

modification and refinement of primary Mg2Si and improvement of mechanical

properties for the hypereutectic Mg–5wt.%Si alloy

(5) The addition of 2 wt.% CaO is the effective way to improve the ignition and

oxidation resistance of AZ91 magnesium alloy

Conclusions

The Future Trends

Liquid metal treatment of Mg alloys via HIUST, MV and chemical additions.

Casting technology and development of Mg alloys via semi-solid casting, lost

foam casting and investment casting.

Development of Mg alloys for different application such as automotive, airplanes

and implants.

Technology transfer and cooperation between CMRDI and industry sector in

Egypt.

Current researches

M. Sc. Thesis

PhD Thesis

Preparation and characterization of magnesium based alloys for

bone substitution

A novel biodegradable Mg-based alloys for osseous regeneration

Long term researches

2nd South Africa Metal Casting Conf. - Foundry-Planet Ltd. · M. E. Moussa a,*, M. A. Waly a, A. A....

Documents

Transcript of 2nd South Africa Metal Casting Conf. - Foundry-Planet Ltd. · M. E. Moussa a,*, M. A. Waly a, A. A....