Preconditioning of charge trays and fixtures.

[arunmrao]

I have been recently asked by a user to suggest any preconditioning of charge trays and fixtures used in a carburizing furnace. The material used for this ASTM A297 Grade HU( C 0.5%, Ni 39%, Cr 19% Mo 0.5%). I shall be thankful if anyone could give me their experiences in extending the life of these fixtures and parts.

 

[Goahead]

Preconditioning here probably refers to a treatement applied to new cast trays to dissolve carbides and reduce segregation from casting. By reheating in the range 1800-2200F and above and then cooling rapidly, a high and uniform carbon content in the austenite is obtained, enhancing resistance to carburization.

http://www.welding-advisers.com/

 

[CalvinKelly]

Our experience is as a supplier of wrought alloys for trays and fixtures, since ~1945 ('53 officially). We are aware of no effective preconditioning treatment. Life of cast heat resistant alloy components depends very much on the quality of the casting, that is, the foundry source. Broken trays may be weld repaired for additional life with W86333 AC/DC covered electrodes (45Ni 25Cr 3Co 3Mo 3W, tradename RA333-70-16)

James Kelly

http://www.rolledalloys.com