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SS301 Heat Treatment
We have a Stainless steel material ss301/ 07x16H6 for an application. A Heat treatment cycle , Austenizing at 990 C, sub-Zero temperature treatment at -70 °C and Tempering at 400, was given by Customer to achieve Hardness 36 HRC min/ 900 M.Pa Y.S.
When the heat treatment was carried out of Dia. 20 mm, measured Hardness was 26 HRC & less.
Note:
As per literature, SS301 material cannot be hardened by heat treatment.
Kindly clarify , can we harden the above mentioned material to improve the Mechanical properties? If yes, what may be the cause for lesser hardness?
Engineer - India
January 9, 2009
The reason for your problem can be caused by the way of cooling down after heat treatment. SS should cool down as fast as possible from 900 C. because of the heat input is coming from outside, that's where the co parts in the SS wants to go so they stick to the surface. please check about +-3 mm under surface of pipe and I think your problem is solved. please let me know if I was right
regards Pim (heat treatment technician)
- Rotterdam, Holland
March 20, 2009
March 24, 2009
No, 301 can't be hardened by heat treatment. You can anneal it, and remove any hardening you got from cold working. But it is an austenitic stainless steel, NOT a martensitic, and only the martensitics can be hardened by heat treatment. (Well, except for A-286, which some of us classify as an iron based superalloy rather than a stainless steel.)
A really great introduction to stainless steels is publication # 9014 from the Nickel Institute, at nidi.org. Title is "Design Guidelines for the Selection and Use of Stainless Steels". A few minutes searching for, and downloading that nice free publication will prove well worth the time.
Lee Gearhart
metallurgist - E. Aurora, New York
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