Heat treatments applied to ferritic, martensitic
and precipitation-hardening steels, and their effects on properties
may differ significantly from those for austenitic steels. Solution Annealing:
Stainless steels are solution annealed after processing and
hot working to dissolve carbides and sigma. Carbides are formed
during heating in the 425-900°C range or during slow cooling
through this range. Sigma is more likely to form in higher
chromium steels and in niobium- and molybdenum- containing
grades at temperatures below 900°C.
Temperatures for Heat Treatment: Euronorm, ASTM and other authorities normally require
solution treatment with rapid cooling. Specified ranges may
vary outside the following.
Stress Relief Guidlines:
Extent of stress relief depends on heat treatment times and
temperatures necessarily chosen to avoid harmful precipitates
(carbides, sigma, etc) in the particular steel.
300-425°C
Redistribution of high peak stresses only
425-600°C
Reduction of internal stresses that distort machined
parts
800-900°C
Substantial reduction of welding stresses
900-950°C
Stress relief and stabilization against intergranular
corrosion
1040°C+
Removal of heavy coldwork stresses by solution annealing
