锻造对30CrNi2MoV钢在亚温淬火下组织与性能的影响

Effect of forging on microstructure and properties of 30CrNi2MoV steel under sub-temperature quenching

30CrNi2MoV钢是一种中碳合金钢,常用于制造高强韧性的大型锻件,广泛用于制造火电、核电等电站装备和大型冶金、矿山和运输装备中的承力和传动结构部件.为提高30CrNi2MoV钢的低温冲击韧性和室温强度,本文采用金相显微镜、扫描电子显微镜、拉伸机和硬度仪等方法对其进行组织观测、断口形貌分析和力学性能测试,研究了不同锻造方式对30CrNi2MoV钢的组织与力学性能的影响.结果表明:经过2次镦粗的30CrNi2MoV钢再经1次镦粗或1次镦粗+1次拔长两种锻造方式后能够有效细化且均匀晶粒,提高晶粒等轴性;与2次镦拔工艺的30CrNi2MoV钢相比,再经过1次镦粗或1次镦粗+1次拔长后其抗拉强度、延伸率和冲击韧性分别由1 043.6 MPa、35.65%和40.33 J提高至1 161.6和1 157.4 MPa、37.80%和36.13%、103和87 J.数据表明,30CrNi2MoV钢经过2次镦拔+1次镦粗工艺后,其组织与力学性能达到最好状态.

30 CrNi2 MoV steel is a medium-carbon alloy steel, which is commonly applied in the manufacture of large forgings with high strength and toughness. It is widely used in the manufacture of power and transmission components in power plant equipment and large-scale metallurgy, mining, and transportation equipment for thermal power and nuclear power plants. In order to improve the low-temperature impact toughness and room temperature strength of 30 CrNi2 MoV steel, effects of different forging methods on the microstructure and mechanical properties of 30 CrNi2 MoV steel were studied by using metallographic microscope, scanning electron microscopy, and tensile tester and hardness tester for microstructure observation, fracture morphology analysis, and mechanical properties tests, respectively. Results show that after two times pressing and one drawing + one upsetting process or two times pressing and one drawing + one upsetting + one stretching process, the 30 CrNi2 MoV steel can be effectively refined with uniform grain, and the equiaxiality of the grains can be improved. Compared with the 30 CrNi2 MoV steel with two times pressing and one drawing process, the tensile strength, elongation, and impact toughness increased from 1 043.6 MPa, 35.65%, 40.33 J to 1 161.6 MPa and 1 157.4 MPa, 37.80% and 36.13%, and 103 J and 87 J, respectively. The data indicates that the microstructure and mechanical properties of 30 CrNi2 MoV steel achieve the best state after the two times pressing and one drawing + one up-setting process.