高强度挖掘机铲斗斗唇用钢力学性能及微观组织研究

Microstructure and Mechanical Properties of High-strength Excavator Bucket Lip Steel

利用淬火热膨胀仪、拉伸试验、金相显微镜、扫描电镜以及透射电镜对挖掘机铲斗斗唇用钢的相变规律、力学性能和微观组织进行了研究。结果表明：所研究的挖掘机铲斗拥有较好的淬透性,当冷速超过5℃/s时,就能完全获得马氏体,冷速为1~5℃/s时发生贝氏体相变;试验用钢拥有良好的力学性能,屈服强度为747 MPa,抗拉强度为961 MPa,伸长率为17.05%,-40℃下的冲击功为42k J;试验用钢的微观组织为回火马氏体,细小弥散的碳化物分布其上;透射电镜分析表明大颗粒的碳化物大小为200~300nm,为Cr的碳化物。

Based on hardening thermal expansion instrument,tensile test,metallographic microscope,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）,the phase change laws,mechanical properties and microstructure were studied on the excavator bucket lip steel.The study results show：there is a good hardenability of the digging bucket steel,when the cooling rate is over 5 ℃/s,it can get martensite completely,and the cooling rate is between 1 ℃/s and 5 ℃/s,bainite transformation occurs.There are good mechanical properties of the studied steel such as：the yield strength is 747.0MPa,the tensile strength is 961 MPa,and the elongation rate is 17.05%,and the impact value is 42 KJ under-40 ℃.Its microstructure is tempered martensite with micro and dispersion carbon distributing on it; TEM analysis results show that the larger particle is chromium carbide and the size of chromium carbide is 200-300 nm.