Microstructure and mechanical properties of high speed steel after cyclic cryogenic treatment

The influence of cyclic cryogenic treatment on the microstructure and mechanical properties of W6Mo5Cr4V2 high speed steel was studied by XRD,TEM and mechanical properties test.The results show that,compared with single long time cryogenic treatment,the short time cyclic cryogenic treatment gain much lower c/a ratio and carbon content of martensite,and less residual austenite.After cyclic short time cryogenic treatment,a lot of new ultra-fine dispersed carbide particles precipitate on the twin bands and dislocation lines of martensite and the average carbide size decreases,and the mechanical properties improve significantly.Therefore,it is beneficial to increase the cryogenic treatment times in practical application.