The Effect Of Heat Treatment On Torsion And Tensile Properties Of 65Mn Steel

In recent years,with the rapid development of the industry especially in the automobile and shipbuilding aspects,the performance requirements of the mechanical parts are also becoming more and more higher,such as torsion?bending etc.Through the test of 45 steel products which used to withstand torque of shaft parts in the work environment,we find it exists insufficient strength weakness then study the influential factors about the torsion properties especially in the heat treatment aspect.From the economic and practical working conditions,we use the heat treatment to enhance the torsion property of 65 Mn steel to improve the shortcoming.The test includes two steps:firstly is the same temperature quenching and tempering at different temperatures,secondly is different quenching temperature with same tempering temperatures.We study the change of microstructure and properties by metallographic observation and fracture analysis,finally compared with the 45 steel.At the same time,we use the tensile test as a supplementary test to characterize the material changes in shaping performance.The test shows:(1)On the premise of same quenching temperature,the torsional yield strength and torsional strength of 65 Mn steel are gradually decreasing with the increase of the tempering temperature;the tensile strength is also gradually decrease but moulding increases slowly;the tensile fracture types of materials also changes from brittle to ductile;(2)On the premise of the same tempering temperature,the change of different quenching temperature has no significant effect on the torsional behavior of 65 Mn steel.And with the increase of quenching temperature,the tensile fracture types changes from the brittle fracture to ductile brittle fracture;(3)The change of the torsion and tensile properties of the material is mainly affected by the tempering temperature;(4)The torsional strength of the 65 Mn is significantly stronger than the 45 steel in the quenched and tempered state,and the gap is 555Mpa;(5)The optimum heat treatment process for 65 Mn steel with the best torsion and tensile properties is 800? for the quenching temperature and 380?for the tempering temperature.