Effect of heat treatment on corrosion behavior and microstructure of martensitic stainless steel prepared by selective laser melting
Effect of heat treatment on microstructure and corrosion behavior of Corrax(CX)stainless steel prepared by selective laser melting(SLM)was studied by means of optical microscope,electron backscatter diffraction technique,transmission electron microscopy and electrochemical testing.Firstly,SLM CX stainless steel was subjected to solution treatment at 900℃ for 1 h,followed by aging treatment at different temperatures(430-630℃)for 3 h.The results show that the relative density of the SLM CX samples after heat treatment reaches over 99%,indicating good densification effect.The electrochemical test results indicate that the selection of aging temperature has significant influence on the corrosion resistance of the SLM CX samples,and the corrosion traces on the surface of the samples have been improved to certain extent.The sample aged at 530℃ has the highest relative density(99.72%),the best corrosion resistance,the highest corrosion potential(-0.1851±0.013 V),and the lowest corrosion current density(0.1203±0.011 μA·cm-2).The corrosion resistance of the SLM CX samples after heat treatment is synergistically affected by relative density,grain size,grain boundary characteristic distribution and NiAl particle precipitation.
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