Effects of heat treatment on microstructure and mechanical properties of 75Cr1 saw blade steel

Quenching( 800-880 ℃) and tempering( 400-480 ℃) experiments were carried out on rolled 75Cr1 saw blade steel,and the microstructure and mechanical properties were analyzed by optical microscopy,electronic universal testing machine,impact tester and Rockwell hardness meter. The results show that microstructure of the quenched sample is composed of martensite and residual austenite. The martensite coarsens gradually with the quenching temperature raising. While increasing the quenching temperature from 800 ℃ to 880 ℃,the hardness is increased from 59 HRC to 68 HRC. Following the tempering temperature raising,microstructure of the samples gradually changes into tempered martensite and tempered martensite + tempered sorbite,the strength and hardness decrease,and the plasticity and toughness increase gradually. The optimum heat treatment process is 840 ℃ heating for 20 min then oil quenching and 460 ℃ tempering for60 min.