Effect of heat treatment on the microstructure of duplex stainless steel 2205

The Duplex stainless steel (DSS) is required to maintain its exceptional mechanical and corrosion resistance properties during its utilization. It is a dual micro-structured material consisting of d-ferrite and c-austenite in almost equal proportion as established by the international quality standards. It owes its exceptional properties to the optimum heat treatment and the partitioning of additional elements such as Cr, Mn, Mo, Ni, and N during its manufacturing. Unfortunately, due to drastic working conditions requiring elevated temperatures and sudden cooling, the DSS is subjected to noticeable phase equilibrium shifting and the formation of intermetallic phases. These changes are responsible for eventual weakness observed in most structures made with the DSS. To alleviate the inconvenience, the present paper focuses on the investigation of the effect of cooling method on the microstructure of the DSS exposed to solution annealing at a temperature of 1100 ℃. The DSS was cooled in the furnace and air and quenched in oil and water. The microstructure generated by the different cooling methods was assessed using the light optical microscopy (OM), scanning electron microscopy (SEM-EDS) and microhardness measurement. The initial lamellar structure transformed to clustered or blocky structure and intermetallic precipitates are revealed.