Research Of Heat Treatment Of Spring Steel

With the development of modern transportation industry,there are increasing needs for weight and cost savings.Therefore,considerable efforts have been made in the development of high performance spring steels with higher strength and longer life.The microstructure evolution and properties transform of drawing pearlite steel wires were studied with the methods of morphological analysis,mechanics analysis and synthetic analysis.The main research results were as following:Different microstructures of 65 Mn steels have different spheroidizing mechanization of carbides during spheroidizing annealing.When the microstructure was drawing wires,the optimum spheroidizing temperature was 660°C,and the holding time was 15 h,and the spheroidizing rating was 5.When the structure was troostite,the optimum spheroidizing temperature was 730°C,and the holding time was 9h,and the spheroidizing rating was 5.Suitable spheroidizing annealing process can improve the mechanical properties of annealing and quenching of 65 Mn steel.The strength and hardness of the 65 Mn steel were reduced and the toughness was enhanced by the spheroidization experiments.The research shows that,the optimum tempering treatment temperature of 65 Mn was 450°C,and the holding time was 60 min,the tempered structure of 65 Mn was tempered troostite,The strength and ductile were proper.The tempering brittleness appeared when tempered at 400 °C,and tempering should be avoided at this temperature.The research content mainly aimed at the cracking and broken phenomenon of 65 Mn spring steel,and explored the cracking reasons and optimized the performance of 65 Mn with heat treatment process.The optimum spheroidizing temperature was 660°C,and the holding time was 15 h,then quenching oil and tempering treatment temperature of 65 Mn was 450°C,and the holding time was 60 min.