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研究火车车钩用钢ZG25MnCrNiMo经过不同调质工艺处理后-40℃的冲击性能。分别用金相显微镜、扫描电镜和透射电子显微镜观察和分析钢的微观组织、低温冲击断口形貌和钢中碳化物的析出行为。结果表明,ZG25MnCrNiMo钢在910℃淬火、550℃回火2 h得到均匀回火索氏体组织,冲击功最大。冲击功随回火温度的升高而增大。低于550℃回火,钢中的碳化物主要在板条界面呈连续析出,-40℃冲击功低;550~650℃回火,铁素体呈等轴状且碳化物分布于晶内,表现出高的冲击性能。
Study the train coupler steel ZG25MnCrNiMo after different quenching process -40 ℃ impact performance. The microstructure, fracture morphology at low temperature and the precipitation behavior of carbides in steel were observed and analyzed by metallographic microscope, scanning electron microscope and transmission electron microscope respectively. The results show that the ZG25MnCrNiMo steel is tempered at 910 ℃ and tempered at 550 ℃ for 2 h to obtain uniform tempered sorbite structure with the largest impact energy. Impact energy increases with tempering temperature. When the temperature is lower than 550 ℃, the carbides in the steel are continuously precipitated at the slab interface, the impact energy is low at -40 ℃, and the alloy is tempered at 550-650 ℃. The ferrite is equiaxed and the carbides are distributed in the crystal, Show high impact performance.