Technical Delivery Condition Doc. No. TDC-10B Rev 3 Heat Treatment Procedure for C12A

Castings Date 12-May-12 Page 1 of 2

Prepared by Approved by C Raja R Muruganantham Form No: GP-010-R1

1.0 Scope:

This procedure covers the heat treatment requirements including PWHT for ASTM A217 Gr. C12A castings.

2.0 Components:

Body, Bonnet, Cover, Disc, and all other casting

3.0 HT Furnace requirements: S No Equipment Requirement

1 Heat Treatment Furnace Electrical bogie hearth furnace

2 Thermocouple K type

3 Furnace calibration As per API 6A or ASTM A991

4 Frequency of calibration Furnace 1 year Thermocouple, Temperature controller and Recorders - 3 months

5 Loading Temperature 400C max.

6 Rate of heating 100C per hour maximum.

7 Rate of Cooling 70C per hour maximum

3.1 Minimum 2 thermocouples shall be attached to the furnace (one at the top and other at the

rear side of the furnace).

3.2 One metal attached thermocouple shall be deployed in each of the furnace heat zones on the castings for the entire heat treatment cycle and the data from this thermocouple shall be recoded in HT Chart.

4.0 Heat treatment details:

4.1 Heat treatment shall be performed after castings have been allowed to cool below the

transformation range. To achieve the mechanical properties, following quality heat treatment has proven to be advantageous.

J Viswanath 08/06/2013

Technical Delivery Condition Doc. No. TDC-10B Rev 3 Heat Treatment Procedure for C12A

Castings Date 12-May-12 Page 2 of 2

Prepared by Approved by C Raja R Muruganantham Form No: GP-010-R1

R3

S

No. Heat Treatment Soaking Temp Soaking Time Cooling Media

1 Normalizing* 1040C 1080C 1 hour per inch thickness (minimum 2 hour) Air Cool

*To ensure a martensite transformation of the whole cross-section (See also clause 5.5)

2 Tempering 760C 780C 1 hour per inch thickness (minimum 2 hour) Air Cool

3 Stress Reliving (PWHT) 730C - 755C 1 hour per inch thickness (minimum 2 hours) Furnace Cool

4.2 More than 2 times PWHT not permitted.

5.0 Placement of castings inside the furnace

5.1 Castings shall be placed on the grid which is placed on the furnace bed without touching

other castings as well as side walls of the furnace.

5.2 The castings shall be placed as an array and the minimum distance between the castings shall be 4 inches.

5.3 The gap between the door edge and furnace wall after closing the door shall be minimized

to reduce the heat loss as well as oxidation.

5.4 All the heat treatment shall be completed in a single stretch. The time gap between normalising and tempering shall be minimized as such as possible.

5.5 Castings shall be allowed to cool below 100C (approximately) after normalising before

subsequent heat treatment cycles to ensure complete transformation of Martensitic structure.

5.6 When the castings needs to be air cooled, they shall be unloaded from furnace without time

delay.

6.0 Records The following reports shall be forwarded to L&T along with casting during despatch

6.1 Heat treatment log (shall contain the all details of above mentioned HT details, component description, date, shift, loading & unloading time and temperature details)

6.2 Normalising and Tempering Heat Treatment Chart.

J Viswanath 08/06/2013