Technical Expertise for Building Stronger Railways• Flash butt welding • Manual metal arc (MMA)...

Technical Expertise for Building Stronger Railways Stephen Lewis Consultant, Rail Technologies – British Steel

Technical expertise for building stronger railways

Dr. Stephen Lewis

Contents

Technical expertise for building stronger railways 3

Introduction to Rail Technologies

Rail welding •  Gauge corner restoration (GCR) •  Flash butt welding •  Manual metal arc (MMA) welding •  Weld approvals and failures

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Light rail / Tramway •  Corrugation •  Intelligent maintenance

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3

4 Questions

Introduction to Rail Technologies


Lindsey Smith

Consultant Wheel Rail Interface Specialist

Sean Gleeson

Consultant Welding Specialist

Rob Lambert

Rail Technologies Manager

Brindusa Mironov

Consultant

Sandra Fretwell-Smith

Consultant

Arvid Cedervall

Consultant

Stephen Lewis

Consultant Wheel Rail Tribologist

Team expertise in: •  Materials testing •  Materials technology •  Welding technology •  Track monitoring / surveying •  Asset management

What we do


Rail Welding


Martensite – 101


Heat affected zone (HAZ)

Weld deposit

Pearlitic parent rail

Pearlite

Martensite

Gauge corner restoration (GCR)


Traditional GCR solutions •  Can result in untempered martensite •  Deliver poor weld integrity (spalling)

•  British Steel patented an improved process of robustly weld-repairing worn grooved rail

•  Eliminates high temperature pre-heat which would damage the polymer surrounding embedded rail

•  Suitable for in-track repair of embedded track to extend rail life

Gauge corner restoration


The flash butt welding process is sub-divided into: •  Initial flashing •  Pre-heating •  Final flashing •  Upsetting / Forging •  Post weld heat treatment (optional)

Many different varieties of welding machine •  AC / DC •  Fixed / mobile / semi-fixed •  Continuous flashing / pulsed flashing

Flash butt welding


‘Heating two rail ends electrically and forging them together to form a welded

joint’

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•  They may be manufactured by the same company, built by the same engineering team, be the same make and model, made on the same production line but ……

Flash butt welding


No two flash butt welders are completely identical

What weld properties do we have to achieve?


On-site macros HAZ and Hardness values

Approval Procedure: 1.  Weld process parameters 2.  External inspection of welded joint 3.  Slow bend tests 4.  Macro examination of longitudinal -

vertical sections 5.  Hardness measurements 6.  Fatigue testing

Weld approvals


Repair of a damaged section of rail head by: Excavating damaged area à weld filling the excavation à grinding back to profile •  A multi-layer weld completed as per BS EN 15594:2009 •  Excavation is filled with a minimum of 5 layers. •  Inspection and testing

Manual Metal Arc (MMA)


•  No cracks •  No untempered martensite and •  Compatible hardness to parent

What are we looking for?


Microstructure at HAZ through transverse section

Weld failure investigations


Lots of reasons welds can fail: •  Weld process failure •  Weld defects •  Rail defects •  Track conditions •  Residual stresses

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Weld failure investigation example


Broken rail found Sample received Hardness testing

Fracture face Section area of interest Microscope analysis

Light Rail


Light rail – Corrugation and wear surveying


•  Tramways often suffer from rail corrugation •  Usually mitigated by rail grinding •  Some networks use subjective assessment •  Some use a more scientific approach

•  Rail Technologies used specialist equipment to survey network •  Assess extent of corrugation •  Analyse and visualise data •  Define grinding priorities

•  Implemented a planned corrugation maintenance program •  Manage maintenance more cost effectively •  Targeting grinding in the short, medium and long term.

Shifting railways/tramways from a ‘find and fix’ philosophy towards one of ‘predict and prevent’ Corrugation Maps:

•  Mapping part or whole networks •  Maintenance and renewal strategies developed for the highest priority sections

Intelligent maintenance


Not drawn to scale

98

72

55 36

9 3 1193

5

3

Station B

10

23 12 6

70 6

159

11 50

26 91

11 24 36 86

4

42

8

162

Station C Station D Station E Station A Station F

440

11 4 4 5 5 340

4

Station 4 Station 2 Station 3 Station 1

505

5 15 4 5 8 507

41

640

7 450

45 595

120

56 109

598

34 13 8 9 26 15

10

10

10

Light

Corrugation Measurements

Moderate

Severe

Figures are distance in metres

Any questions?


Technical Expertise for Building Stronger Railways• Flash butt welding • Manual metal arc (MMA)...

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