The effect of aging treatment at 400-500℃ for different times on the microstructure and pitting resistance of Custom455 martensitic age-hardening stainless steel was investigated using OM,XRD,TEM and electrochemical methods.The results show that the microstructure of the ageing-treated steels consists of lath martensite and reversed austenite,and with the change of aging temperature and time,the second phase particles such as Cu-rich phases and Ni3Ti with varying amount and size will be precipitated.For a given aging time,while the aging temperature increased,the amount of reversed aus-tenite will also gradually increase,however the amount and size of Ni3Ti,e-Cu and other second-phase particles will not change obviously,so that the pitting corrosion resistance of the steel increased;when the aging temperature rises to 600℃,a large number of the second-phase particles of Ni3Ti,e-Cu and oth-ers precipitate out,which leads to a decrease in the pitting corrosion resistance of the steel.When the ag-ing temperature is consistent while the aging time rises to 3 h,the amount of reversed austenite in the steel does not change significantly,but the amount and size of Ni3Ti,ε-Cu and other second-phase parti-cles change significantly with the increasing aging time,which also leads to a decrease in the pitting cor-rosion resistance of the steel.
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