Effect of heat treatment on microstructure, mechanical properties and corrosion behavior of selective laser melted 15-5PH steel

摘要

Selective laser melting (SLM) is one kind of additive manufacturing process tofabricate metal parts through laser melting. A 15-5PH martensite steel was manufactured by SLM.The inuence of heat treatment on the mechanical and corrosion performance of 15-5PH martensitesteel was investigated. The specimens were underwent heat treatment by aging treatment (AT) andsolution treatment + aging treatment (ST+AT) respectively. The investigation involvedmicrostructure, microhardness, stretching behavior and electrochemical experiment. It was shownthat: After ST+AT, the cellular structure and microscopic segregation disappeared. The new NbC-(Mn, Si)O duplex particles (about 150 nm) precipitated out after ST+AT and the Cu-richnanoparticles (about 10nm) precipitated out after AT. The microhardness and tensile strength ofthe sample by AT was comparable to the samples by ST+AT, however the elongation increasedfrom 11% to 16% relative to the samples by ST+AT. The pitting resistance of the samples byST+AT decreased and the corrosion resistance was relatively worse, which was attributed to theprecipitation of NbC-(Mn, Si)O duplex particles. Moreover, the composition of passive film and itseffect with the heat treatment were discussed.