technical expertise for building stronger railways• flash butt welding • manual metal arc (mma)...
TRANSCRIPT
Technical Expertise for Building Stronger Railways Stephen Lewis Consultant, Rail Technologies – British Steel
Technical expertise for building stronger railways
Dr. Stephen Lewis
Contents
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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
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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
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Rail Welding
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Martensite – 101
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Heat affected zone (HAZ)
Weld deposit
Pearlitic parent rail
Pearlite
Martensite
Gauge corner restoration (GCR)
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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
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Gauge corner restoration
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Gauge corner restoration
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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
Technical expertise for building stronger railways
‘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
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No two flash butt welders are completely identical
What weld properties do we have to achieve?
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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
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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)
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• No cracks • No untempered martensite and • Compatible hardness to parent
What are we looking for?
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Microstructure at HAZ through transverse section
Weld failure investigations
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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
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Broken rail found Sample received Hardness testing
Fracture face Section area of interest Microscope analysis
Light Rail
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Light rail – Corrugation and wear surveying
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• 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
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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?
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