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利用光学显微镜、扫描电子显微镜、电子探针,并通过室温拉伸实验和冲击实验,分析了不同热处理工艺对重型履带板用NiCrMo中碳低合金钢的组织和性能的影响。结果表明,1000℃保温8 h的均匀化退火能明显改善实验合金铸态组织中碳元素的枝晶偏析;随着碳含量的增加,合金抗拉强度成直线上升,韧性下降明显。当淬火温度高于910℃之后,晶粒尺寸长大明显,强度和硬度随之降低;淬火温度超过970℃后,个别晶粒出现异常长大现象;在450～550℃回火后得到回火索氏体组织,强度随着回火温度的上升而下降,0.32%碳含量的抗拉强度从1340 MPa下降到1220 MPa;韧性随之增加,冲击韧性从40 J.cm-2上升到65 J.cm-2。
The effects of different heat treatment processes on microstructure and properties of NiCrMo medium carbon low alloy steels for heavy duty track shoes were analyzed by optical microscope, scanning electron microscope, electron probe and room temperature tensile test and impact test. The results show that homogenization annealing at 1000 ℃ for 8 h can obviously improve the dendritic segregation of carbon in the as-cast microstructure. With the increase of carbon content, the tensile strength of the alloy increases linearly and the toughness decreases obviously. When the quenching temperature is higher than 910 ℃, the grain size grows obviously and the strength and hardness decrease. When the quenching temperature exceeds 970 ℃, some grains grow abnormally. After tempering at 450-550 ℃, tempering Sorbite, the strength decreases with the increase of tempering temperature, the tensile strength of 0.32% carbon decreases from 1340 MPa to 1220 MPa; the toughness increases with the increase of impact toughness from 40 J.cm-2 to 65 J .cm-2.