Type 347 stainless steel has slightly improved corrosion resistance over type 321 stainless steel in strongly oxidizing environments. Type 347 stainless steel is stabilized with columbium, it is preferable for aqueous and low temperature environments due to its good resistance to intergranular attack. Both 347 stainless steel and 321 stainless steel offer good resistance to polythionic acid stress corrosion cracking, encountered in oil refineries. The high temperature oxidation resistance of 347 stainless steel is similar to that of 304 stainless steel. Useful to 1500°F.
