When is post weld heat treatment beneficial, and what treatments should be used?
There are no heat treatments in the 315-980° C (600-1800° F) range that are beneficial to duplex stainless steels. Postweld stress relief heat treatments are used with steels that are capable of forming martensite, but duplex stainless steels do not form martensite. The metallurgical condition of a duplex stainless steel will be severely damaged if it is exposed to the stress relief treatment applied to a carbon or alloy steel (a consideration in dissimilar welds). If the duplex stainless steel for whatever reason is exposed to conditions that lead to the formation of intermetallic phases, then the appropriate remedy is to heat treat the whole structure. The only heat treatment that works for duplex stainless steel is a full anneal above the minimum temperature listed in ASTM A 240, (1040°C (1900° F) in the case of 2205) and quench. When the construction cannot be annealed and quenched, the only remaining alternatives are to scrap the whole construction, or to cut out and replace the a
