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通过扫描电镜(SEM)、透射电镜(TEM)观察及硬度、拉伸性能测试,利用正交实验方差分析,研究了不同回火温度对45CrNiMoV高强钢析出相形貌和力学性能的影响。结果表明,实验钢回火温度对强度和冲击功均有显著影响,550℃回火后强/硬度达到最高值,600℃以上回火强/硬度急剧下降;实验钢回火温度从570℃提高到640℃,析出的碳化物形貌由条杆状向球形演变,570℃回火后,析出的细小的球状碳化物对马氏体板条边界存在钉扎作用。640℃回火后,析出的碳化物已经无法钉扎住板条边界;实验钢最佳热处理工艺为880℃油淬保温45 min+590℃回火240 min。
The effects of different tempering temperatures on the morphology and mechanical properties of precipitates in 45CrNiMoV high strength steel were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and hardness and tensile properties tests using orthogonal experimental analysis of variance. The results show that the tempering temperature of experimental steel has a significant effect on the strength and impact energy. The tempering / hardness reaches the highest value after tempering at 550 ℃, and the tempering strength / hardness decreases sharply at 600 ℃. The tempering temperature of experimental steel increases from 570 ℃ At 640 ℃, the precipitated carbide morphology evolves from bar to sphere. After tempering at 570 ℃, the precipitated fine spherical carbides have a pinning effect on the martensite lath boundary. After tempering at 640 ℃, the precipitated carbide can not pinned the slab boundary. The optimum heat treatment process of the experimental steel is oil quenching at 880 ℃ for 45 min and 590 ℃ for 240 min.