Innovations to Enhance Rail Performance - Unife

Innovations to Enhance Rail Performance
UNIFE
INNOVATION FORUM – INFRASTRUCTURE
22 nd September 2010
Dr Jay Jaiswal
Corus Rail

Past & Present Rail Microstructures
1767 Cast Iron ~ 3%C; 200HB
1808 Wrought Iron 0.05%C; 174HB
1857 Bessemer Steel ~ 0.25%C; 182HB
100µm
1950 BS11 Normal (R220);
~0.55%C, 230HB
1970 Grade A (R260) 1985 MHT (R350HT)
280HB
350HB
Steel ~ 0.8%C
Current HE Grades (R400HT)
>400HB Steel ~ 0.9%C
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Past & Present Rail Microstructures
Key Aspects of Rail Developments Over last 200 years
• Increasing Steel Cleanness
• Increasing Weight of Rail Sections
Reduce Defects
• Increasing Carbon Content
• Increasing Hardness
Reduce Wear
• Longer lengths
– 120m hot rolled
– Several hundred m welded lengths
Reduce Joints/Welds
• The achievement of 2020/2030 transport visions demands more
innovations
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Innovations from Corus
• Corus has an outstanding record in bringing innovations into the industry – the key recent
innovations reducing LCC of track infrastructure
– Distinctive rail grades to combat key degradation mechanisms
– RAILCOTE - Coated rails to combat corrosion prone environments
– Semi-automatic weld restoration of discrete rail head defects
– Steel - Concrete Two Layer Railway Track - consistently supported S&C track form
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Addressing Rail Degradation
• Traditionally, selection of rail grades has been governed by the track
radius and the annual tonnage carried
• However, the introduction of various vehicle types and variations in
track support conditions indicate that the behaviour in curves with
similar radius & tonnage can be significantly different
• Hence, one of the rail grade selection criteria developed within the
Innotrack Project is based on observed degradation mechanism
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Innovative Rail Steel Grades – Corus MHH
10 mm
25 mm
x8000
• Corus 400 MHH (R370CrHT) is a well proven product with >300kt installed in major railways of
the world. The distinctive features compared to in-line heat treated rails are:
– Finer grain size from the controlled low temperature reheating, imparting toughness
– Finer pearlitic microstructure from the controlled cooling imparting high hardness to greater depths
– Much lower residual stresses in both the head and foot, imparting greater resistance to defects
• Corus 400 MHH grade is ideal for locations demanding greatest resistance to wear
Conditions
Longitudinal stresses (MPa) Saw cut test
Head Web Foot (mm)
Natural cooling before straightening +30 -20 +30 +0.2
Natural cooling after standard straightening +180 -160 +220 +1.8
Natural cooling after optimised straightening +140 -110 +190 +1.5
Off line heat treatment without straightening -86 +41 -30 -1.5
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Innovative Rail Steel Grades - Corus Bainitic Rail
Grade B320 Grade B360 Grade B440
• Corus B320 has been installed in Eurotunnel (4200m radius)
• Performance AFTER >250 MGT
R260 – Visible RCF Present
Corus B320 – Virtually No RCF Present
Increasing Hardness of Bainitic Grades
• Bainitic Rail Steels
• Conventional bainitic structure – Ferrite and Carbide
• Have been tried in the past but offered no real advantages
• Low-carbon carbide free structure – Ferrite and Austenite
• Control of composition & residual stress to eliminate risks from susceptibility to
Stress Corrosion Cracking
• Good performance in track tests in SNCF (B320), SBB (B360), Eurotunnel (B320)
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Latest Innovation in Rail Steel
Corus “High Performance” (HP) Rail
• Corus “High Performance” (HP) Rail
• Metallurgically Engineered Pearlitic Rail Steel
• Increased volume fraction of pearlitic cementite
• Increased strength of pearlitic ferrite
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Corus HP Steel – Test results
240,000
Current Pearlitic Steels Corus HP Lab Cast Corus HP BOS Cast
200
Number of Cycles to RCF Initiation
200,000
160,000
120,000
80,000
40,000
0
200 250 300 350 400 450
Steel Hardness, HB
Wear Rate (mg/m of slip)
160
120
80
40
0
200 250 300 350 400 450
Hardness (HB)
Current Pearlitic Steels
Corus HP Steels
• The traditional reliance on hardness for increased resistance to wear
and rolling contact fatigue has been successfully challenged through
judicious engineering of the pearlitic microstructure. HP steel offers:
–A STEP CHANGE improvement in resistance to rolling contact fatigue
– Increased wear resistance at lower levels of hardness
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Protecting Against Rail Corrosion
• Rail life is severely curtailed in locations such as level crossings, coastal lines, wet
tunnels, and stray current environments
• Traditionally a range of epoxy/polyester barrier coatings have been employed
– Limited success because of the damage caused by harsh rail handling
• Corus RAILCOTE is high purity zinc coating that has provided the best results
• Several test sites in Network Rail & RATP have already provided appreciable
increase in rail life
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The Innovative Discrete Defect Repair Process
• Complex Contact Conditions: even the best maintained railway networks develop
discrete defects –
– wheel burns, squats, Belgrospies …
• Network Rail Assessment: ~10,000 squats/wheel burns removed annually - ~6000 weld
repairable
– Average cost of replacement estimated at ~£2.5k per defect or ~£15 million annual
expenditure
• Application into the wider Railway World provides a very strong case for innovation of a
repair procedure
• Corus Discrete Defect Repair procedure has successfully met the Innovation challenge
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The Innovative Discrete Defect Repair Process
• Milling:
– Rapid excavation of defects to prescribed dimensions for consistency of quality
• Weld Repair:
– Innovation lies in the avoidance of preheating to the conventional temperature of 350 0 C
– Semi- automatic Open Arc Welding employing Flux Cored Arc Wire and controlled patterned
weave and energy input
• Grinding
– Rough milling followed by manual grinding to blend rail profiles
• The RESULT
– A COST EFFECTIVE & ROBUST weld repair with an extremely HIGH FATIGUE STRENGTH
– AVOIDS new AT WELDS or the need for RE-STRESSING
– A CONSISTENT & RAPID process to minimise loss of track availability
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Key Attributes Achieved
• CONSISTENT SUPPORT – Separate strong steel frame with high longitudinal stiffness
• MODULAR CONSTRUCTION – train load taken before base is ready
• REDUCED TRAFFIC DISRUPTION - Designed to open to line speed at handovers
• NO MAJOR CIVILS WORK - Two layer design with adjustment capability
• MINIMUM MAINTENANCE – Restricted to grinding & rail replacement through wear
• LOW FIRST COSTS - Installation costs comparable to conventional ballasted
installations provided time delay penalties are also accounted for.
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Conclusions
• Corus remains committed to directing its diverse metallurgical &
engineering expertise to develop innovative products & processes
for the rail transport sector
– Novel rail steels offer opportunities for significant reductions in LCC
– The novel Discrete Defect Repair procedure offers a much more
robust & cost effective process for repairing defects such as squats &
wheel burns
– A novel 2-layer track form offers a near “maintenance-free” S&C layout
• Further new innovations in the Pipeline
• Corus welcomes Infrastructure Managers for discussions on trials
of its innovative products
THANK YOU
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