42CrMoVNb钢的热处理工艺优化及力学性能

Heat treatment process optimization and mechanical properties of 42CrMoVNb steel

利用单因素和正交试验对42CrMoVNb钢的热处理工艺进行了优化,利用洛氏硬度计、万能拉伸试验机和金属摆锤冲击试验机检测了相关的力学性能,研究了热处理工艺对42CrMoVNb钢组织和力学性能的影响。结果表明,42CrMoVNb钢的最优淬火回火工艺为860℃×20 min,油冷+440℃×150 min,空冷;经最优工艺处理后其组织为回火屈氏体基体上弥散分布着细小的碳化物颗粒,硬度、抗拉强度、屈服强度、屈强比、断后伸长率、断面收缩率和-20℃低温冲击吸收能量分别为44.5 HRC、1467 MPa、1357 MPa、0.93、10.5%、46%和27.1 J;力学性能满足14.9级高强度螺栓的技术指标要求。

Heat treatment process of 42CrMoVNb steel was optimized by single factor and orthogonal tests.The mechanical properties of the 42CrMoVNb steel were tested by Rockwell hardness tester,universal tensile testing machine and metal pendulum impact testing machine.The effect of heat treatment process on microstructure and mechanical properties of the 42CrMoVNb steel was studied.The results show that the optimal heat treatment process of the 42CrMoVNb steel is quenching at 860℃for 20 min,oil cooling and tempering at 440℃for 150 min,air cooling.The microstructure under the optimal heat treatment process is tempered troostite matrix dispersed with fine carbide particles,the hardness,tensile strength,yield strength,yield ratio,elongation after fracture,percentage reduction of area and impact absorbed energy at-20℃are 44.5 HRC,1467 MPa,1357 MPa,0.93,10.5%,46%and 27.1 J,respectively,which all meet the mechanical properties requirements of 14.9 grade high strength bolts.