The effect of heat treatment on microstructure and mechanical properties of 27SiMn steel

Nine kinds of heat treatment process were developed in order to get the effect of heat treatment on the microstructure and the mechanical properties of 27SiMn steel,and its microstructure and mechanical properties were observed. The results show that tempering temperature and time have a great influence on the microstructure of 27SiMn; the tempering microstructure is mixed with tempering troostite and martensite when the tempering temperature is lower and time is shorter,while the tempering microstructure is the mixture of tempering troostite and sorbite when the tempering temperature is higher and time is longer. Besides,the tempering temperature and time also have a great influence on the mechanical properties of 27SiMn. When the tempering temperature is 450 ℃ and time is 45min,the maximum tensile strength is 1175 Mpa; when the tempering temperature is 490 ℃ and time is 75 min,the maximum tensile strength is 975 MPa. The comprehensive analysis shows that the optimum heat treatment process of 27SiMn steel is : quenching at475℃ and tempering under 900℃ for 75 min.