高锰铸钢的高温形变热处理及其组织和力学性能

High-temperature Thermo-mechanical Treatment and Resulting Microstructures and Mechanical Properties for High-manganese Cast Steel

高温形变热处理是将高温变形与淬火等热处理工序相结合以提高材料力学性能的热处理工艺。对含1.11%C、13.1%Mn、0.42%Si、0.047%P和0.006%S(质量分数)的高锰铸钢试样分别于1050℃保温2h水淬即水韧处理,和于1050℃压缩变形20%和25%再1050℃水淬即高温形变热处理。随后检测了试样的显微组织、力学性能和低周疲劳寿命。结果表明:与仅仅水韧处理的高锰铸钢相比,经高温形变热处理的高锰铸钢晶粒明显细小,孔洞等缺陷减少,并且随着压缩变形量的增大,钢的晶粒更加细小,组织更加致密,力学性能和低周疲劳寿命均大幅度提高。高温压缩变形25%的高锰铸钢的性能最佳,抗拉强度和断后伸长率分别达927MPa和50.7%,低周疲劳寿命较原始状态的钢提高了50%以上。

High-temperature thermo-mechanical treatment is a combination of high-temperature deformation with heat treatment operation such as quenching for the purpose of enhancing mechanical properties of material. The specimens of high-manganese cast steel containing 1.11%C, 13.1%Mn, 0.42%Si, 0.047%P and 0.006%S by mass were respectively heated for 2 h at 1 050 ℃ then water quenched, which is equivalent to water toughening, and reduced to deformation rates of 20% and 25% at 1 050 ℃ then water quenched from 1 050 ℃, which is equivalent to high-temperature thermo-mechanical treatment. After these, the specimens were tested for microstructures, mechanical properties and low-cycle fatigue life. The results showed that the steel subjected to high-temperature thermo-mechanical treatment exhibited obviously finer grains, less defects such as cavity and the others, and that with the increase in the deformation rates the steel gave even finer grains and even denser structure, as well as considerably increased mechanical properties and low-cycle fatigue life as compared with those of the steel subjected to water toughening alone. Moreover, the high-manganese cast steel high-temperature reduced to deformation rate of 25% developed the best mechanical properties, tensile strength and elongation being as high as 927 MPa and as 50.7% respectively, and low-cycle fatigue life increasing by 50% or more relative to that of the steel in original state.