对工程机械用1 000 MPa级高强钢进行不同温度的淬火和回火热处理, 研究了热处理工艺对其力学性能和显微组织的影响, 并得到了试验钢较佳的淬火和回火温度。结果表明: 随着淬火温度升高, 试验钢的强度先增大后降低, 并在900 ℃时达到最大; 830 ℃以下淬火后, 组织中存在未溶铁素体, 组织为铁素体和板条马氏体; 900 ℃以上淬火后, 组织为板条马氏体; 随着回火温度的升高, 试验钢的强度下降, 塑、韧性提高, 当回火温度达到450 ℃以上时, 组织转变为回火索氏体, 冲击韧性大幅提高; 较优的热处理工艺为900 ℃淬火后在500 ℃回火。

Different quenching and tempering processes were carried out for 1 000 MPa high strengthen steel for construction machinery, the effects of heat treatment processes on microstructure and mechanical properties were studied, and better quenching temperature and tempering temperature were obtained. The results show that with the increase of quenching temperature, the strength of tested steel increased up to the maximum at 900 ℃ and then decreased. After quenching below 830 ℃, undissolved ferrite exited in microstructure and the microstructure was ferrite and plate martensite. After quenching above 900 ℃, the microstructure was plate martensite. With the increase of tempering temperature, the strength of tested steel reduced, and the toughness and ductility showed a increasing tendency. When tempering temperature was above 450 ℃, the microstructure transformed into tempered sorbite, and impact ductility sharply increased. The optimized heat treatment process was quenching at 900 ℃ and tempering at 500 ℃.