Controlling decarburization during hot rolling of rail steel
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CONTROLLING DECARBURISATION DURING HOT ROLLING OF RAIL STEEL by by S.P.SHENOY S.P.SHENOY C.E.O. 211, RAIKAR CHAMBERS, GOVANDI EAST, MUMBAI–400 088. INDIA. Tel. : 91-22-6797 8060 Fax : 91-22-2555 2459 Email : [email protected]Website : www.steelplantspecialities.com
Controlling decarburization during hot rolling of rail steel
Decarburization of steel during hot rolling makes the hot rolled products prone to low fatigue life. This is especially true in the case of hot rolled rail steel and automobile leaf springs. The presentation gives a practical technique to substantially reduce decarburisation and ensure uniform hardness of hot rolled steel. Prevention of welding / sticking of billets at high temperature, reduced scale pits on hot rolled material, reduced scaling and decarburisation due to billet over-heating in furnace and slightly increased yield are some of the other benefits enabled by use of this technique.
2. : SINCE 1985Solving Problems SystematicallyThrough
Innovative, customised products. 3. QUICK FACTS ABOUT SPS
Incorporated in 1985 by seasoned metallurgicalengineers from Indian
Institute of Technology, Mumbai. Manufactures range of products for
heat treatment, hotforging and hot rolling industries. ISO
certified. Sole supplier of specially developed niche products
toindustry leaders. 4. Cost Reductionthrough Protective coatings
that preventor minimize: Oxidation (scaling) & decarburization
duringhardening, normalizing, hot rolling & hotforging. Quench
cracking. Shot blasting / pickling operations. Rejections during
re-H/T 5. HHAARRMMFFUULL EEFFFFEECCTTSS OOFF OOXXIIDDAATTIIOONN
AANNDDDDEECCAARRBBUURRIISSAATTIIOONN1. Loss of dimension.2.
Deterioration of surface quality, i.e., pitting.3. Non-uniform
metallurgical transformationduring hardening.4. Lowered surface
hardness and strength.5. Reduced fatigue life of heat treated
product. 6. D PREVENTING
DEECCAARRBBUURRIISSAATTIIOONNSTEELAIRPROTECTIVE COATINGProtective
anti-scale coatings form a barrier on metal thatprevent reaction of
metal with oxygen.Hence, decarburisation is either prevented or
reduced. 7. CChhaarraacctteerriissttiiccss ooffEESSPPOONN
pprrootteeccttiivvee ccooaattiinnggssDo not react with metal.Do not
emit toxic fumes during storage, use orduring heating the coated
job.Non-hazardous.Economical.Method of application:Brushing,
Dipping or Spraying 8. CCaassee SSttuuddiieess 9. The red area
represents the depth of the decarburised layer.The effective depth
of decarburisation of high speed railis less than 0.3 mm. It can
only be used as the commonrail if the decarburised depth is between
0.31-0.49 mm.It can not be used if the depth is more than 0.5 mm
10. Billet coated on one side by spraying 11. Charging end of
furnace 12. The next illustration shows material saving ofmore than
10% in an expensive metal alloy hotrolling operation.Process
improvement of 50% was noted due toreduction in grinding.Huge
savings were made possible by use ofESPON anti-scale coating. 13.
SCALE PREVENTION = MATERIAL SAVING + PRODUCTIVITY IMPROVEMENTCR
Sheets4300 mm X 1100 mm X 4.5 mmANNEALING950C/30 mins./air-cool to
room temperatureHOT LEVELLING820C/60 mins.GRINDINGFINAL
THICKNESS3.7 mmCR Sheets4300 mm X 1100 mm X 4 mmUSE PROTECTIVE
COATINGANNEALING950C/30 mins./air-cool to room temperatureHOT
LEVELLING820C/60 mins.GRINDING REDUCED BY 50%FINAL THICKNESS3.7 mm
14. PRODUCTIVITY IMPROVEMENT DUE TO COATINGSTEEL PLATESANNEALSHOT
BLASTSHOT BLASTSHOT BLASTDESPATCHSTEEL PLATESANNEAL AFTER ESPON
COATINGSHOT BLASTDESPATCHAbove Details as confirmed by M/s. SAIL,
Rourkela Steel Plant, Rourkela. 15. SUMMARY1.High speed trains
provide challenges to controldecarburisation in the rails to a very
low level.2.Decarburisation reduces fatigue life of rails. It
cancause fatal accidents. Hence it is mandatory to
preventdecarburisation during hot rolling of rails.3.Use of ESPON
protective coating has provento be the most economical and
effective methodto prevent decarburisation. 16. Use ESPON
Protective Coatings.Thank you.S.P.
Shenoyinfo@steelplantspecialities.comwww.steelplantspecialities.com
