Microstructure And Properties Of 6Cr13 Martensitic Stainless Steel Under Different Rolling Reduction Rates

Ultra-high-strength martensitic stainless steel has great advantages in strength and hardness,and martensitic chromium steel cold-rolled sheets have a large number of applications in heavy industry and daily life.In this paper,the effect of cold rolling reduction rate on the content,size,distribution of carbides and mechanical properties of 6Cr13cold-rolled martensitic stainless steel sheet during heat treatment was studied,and the evolution rule of carbides during heat treatment was also discussed.The results lay the theoretical foundation for the production process and it has practical significance to improve the properties of martensitic stainless steel.The research results showed that cold rolling has the effect of refining grains and refining secondary carbides.With the increase of cold rolling reduction rate,the volume fraction of carbides after quenching treatment gradually decreases due to the increasing driving force of carbide dissolution.The volume fraction of carbides after tempering shows increasing trend with the increase of cold rolling reduction rate,but the value of carbides with cold rolling reduction rate of 67% is lower than that of carbides with cold rolling reduction rate of 50%.The volume fraction of carbides obviously increases with incremental tempering temperature.The tensile strength of the samples after quenching and tempering is improved by cold rolling.The mechanical properties of the samples with a cold rolling reduction rate of50% are the worst,and the samples with a cold rolling reduction rate of 67% show the best mechanical properties.The effect of cold rolling reduction rate of 33% on carbide precipitation behavior of the investigated steel sheet was discussed.Both lath martensite and twinned martensite are formed after tempering in the steel.The orientation relationship between retained austenite and martensite shows K-S and N-W relationships.The carbides precipitated at different positions are M₂₃C₆,and the ribbon axes are [1(?)0] and [(?)12].M₂₃C₆ are commonly precipitated at the incoherent interfaces between martensitic laths and twin ends.The two interactions between dislocations and carbides are cut-through mechanism and bypass mechanism,and the Orowan bypass mechanism is the main one.