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.

1. CONTROLLING DECARBURISATION
DURING HOT ROLLING
OF RAIL STEEL
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SS..PP..SSHHEENNOOYY
C.E.O.
211, RAIKAR CHAMBERS, GOVANDI EAST,
MUMBAI–400 088. INDIA.
Tel. : 91-22-6797 8060 Fax : 91-22-2555 2459
Email : info@steelplantspecialities.com
Website : www.steelplantspecialities.com

2. : SINCE 1985
Solving Problems Systematically
Through
• Innovative, customised products.

3. QUICK FACTS ABOUT SPS
 Incorporated in 1985 by seasoned metallurgical
engineers from Indian Institute of Technology, Mumbai.
 Manufactures range of products for heat treatment, hot
forging and hot rolling industries. ISO certified.
 Sole supplier of specially developed niche products to
industry leaders.

4. Cost Reduction
through Protective coatings that prevent
or minimize:
 Oxidation (scaling) & decarburization during
hardening, normalizing, hot rolling & hot
forging.
 Quench cracking.
 Shot blasting / pickling operations.
 Rejections during re-H/T

5. HHAARRMMFFUULL EEFFFFEECCTTSS OOFF OOXXIIDDAATTIIOONN AANNDD
DDEECCAARRBBUURRIISSAATTIIOONN
1. Loss of dimension.
2. Deterioration of surface quality, i.e., pitting.
3. Non-uniform metallurgical transformation
during hardening.
4. Lowered surface hardness and strength.
5. Reduced fatigue life of heat treated product.

6. D PREVENTING DEECCAARRBBUURRIISSAATTIIOONN
STEEL
AIR
PROTECTIVE COATING
Protective anti-scale coatings form a barrier on metal that
prevent reaction of metal with oxygen.
Hence, decarburisation is either prevented or reduced.

7. CChhaarraacctteerriissttiiccss ooff
EESSPPOONN pprrootteeccttiivvee ccooaattiinnggss
Do not react with metal.
Do not emit toxic fumes during storage, use or
during 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 rail
is less than 0.3 mm. It can only be used as the common
rail 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

12. Charging end of furnace

15. The next illustration shows material saving of
more than 10% in an expensive metal alloy hot
rolling operation.
Process improvement of 50% was noted due to
reduction in grinding.
Huge savings were made possible by use of
ESPON anti-scale coating.

16. SCALE PREVENTION = MATERIAL SAVING + PRODUCTIVITY IMPROVEMENT
CR Sheets
4300 mm X 1100 mm X 4.5 mm
ANNEALING
950ºC/30 mins./
air-cool to room temperature
HOT LEVELLING
820ºC/60 mins.
GRINDING
FINAL THICKNESS
3.7 mm
CR Sheets
4300 mm X 1100 mm X 4 mm
USE PROTECTIVE COATING
ANNEALING
950ºC/30 mins./
air-cool to room temperature
HOT LEVELLING
820ºC/60 mins.
GRINDING REDUCED BY 50%
FINAL THICKNESS
3.7 mm

17. PRODUCTIVITY IMPROVEMENT DUE TO COATING
STEEL PLATES
ANNEAL
SHOT BLAST
SHOT BLAST
SHOT BLAST
DESPATCH
STEEL PLATES
ANNEAL AFTER ESPON COATING
SHOT BLAST
DESPATCH
Above Details as confirmed by M/s. SAIL, Rourkela Steel Plant, Rourkela.

21. SUMMARY
1.High speed trains provide challenges to control
decarburisation in the rails to a very low level.
2.Decarburisation reduces fatigue life of rails. It can
cause fatal accidents. Hence it is mandatory to prevent
decarburisation during hot rolling of rails.
3.Use of ESPON protective coating has proven
to be the most economical and effective method
to prevent decarburisation.

22. Use ESPON Protective Coatings.
Thank you.
S.P. Shenoy
info@steelplantspecialities.com
www.steelplantspecialities.com