Heat treatment of AISI 321 stainless steel
Heat treatment of AISI 321 stainless steel
(OP)
According to ASME Code, section II, SA 240, heat treatment of material shall be in accordance with SA 480.
In the case of austenitic stainless steels, the material shall be solution annealed.
For Type 321 Ti-stabilized stainless steel, section 15.2.3 of SA 480 states that a stabilization anneal may be used in case solution a nealing temperature is higher than 1950°F and the steel is subsequently exposed to sensitizing conditions.
If this is not the case, it appears that AISI 321 stainless steel can be purchased in the solution annealed condition (no stabilization).
According to ASM Handbooks Type 321 stainless steel is to be given stabilization HT only if in contact with highly corrosive media.
Is this correct?
How would the steel be stabilized and resist to intergranular corrosion if it solution annealing isn't followe by stabilization, i.e. no specific heat treatment for Ti-carbides precipitation is applied?
In the case of austenitic stainless steels, the material shall be solution annealed.
For Type 321 Ti-stabilized stainless steel, section 15.2.3 of SA 480 states that a stabilization anneal may be used in case solution a nealing temperature is higher than 1950°F and the steel is subsequently exposed to sensitizing conditions.
If this is not the case, it appears that AISI 321 stainless steel can be purchased in the solution annealed condition (no stabilization).
According to ASM Handbooks Type 321 stainless steel is to be given stabilization HT only if in contact with highly corrosive media.
Is this correct?
How would the steel be stabilized and resist to intergranular corrosion if it solution annealing isn't followe by stabilization, i.e. no specific heat treatment for Ti-carbides precipitation is applied?





RE: Heat treatment of AISI 321 stainless steel
If not welding, use as is.
The problem is which treatment to apply after welding.
The most appropriate heat treatment would be in any case resolution treatment: but is it possible without incurring in unacceptable deformations?
Any other treatment would be less favorable for corrosion resistance, but may be needed for stress relieving of residuals welding stresses.
http://www.welding-advisers.com/
RE: Heat treatment of AISI 321 stainless steel
What Bagnamemto is querying is that why only for extremely corrosive media a stabilized solution annealing treatment is required? Also he goes on to ask, in case of normal corrosive media, where ordinary solution annealing is used, how the Ti carbides precipitate in prefernce to Cr carbides and in the case that the ss is not stabilized, how IGC resistance is built into the ss.
In my experience, again, it is the designers call. Depends on what maximum corrosion rates the material is designed for. In case of ordinary solution annealing, the Ti carbides do prefernetiall deposit in preference to Cr carbides, however not 100% of the Ti is utilized for the formation of carbides. Thus the material should show IGC resistance but not to the extent that wiould be desired if the medium was highly corrosive.
In any case, would be good to see what the experts on ss say to this query.
Thanks and regards
Sayee Prasad R CEng MWeldI MIOMMM
If it moves, train it...if it doesn't move, calibrate it...if it isn't written down, it never happened!
RE: Heat treatment of AISI 321 stainless steel
Previously when carbon levels were higher you could get enough carbon quenched into solution that it could precipitate as Cr23C6 if subsequently re-heated,as by welding.
Mills keep C and N low now to avoid the surface defects associated with TiN. The beneficial by-product of this is the lack of need for solution heat treatments to form TiC and TiN. If you're unsure, just look at the carbon level on the certification. If it's below 0.3%, it's an L grade anywway. It won't present chromium carbide problems.
RE: Heat treatment of AISI 321 stainless steel
RE: Heat treatment of AISI 321 stainless steel