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基于Greenwood-Johnson理论,采用Gleeble-1500D热模拟实验机,对U75V重轨钢连续冷却转变过程中珠光体转变的相变塑性进行研究。通过测定不同加载应力下的膨胀曲线,对总变形中的组成应变,即热应变、相变应变、弹性应变、相变塑性应变进行分离,建立重轨钢相变塑性模型方程,通过数值模拟对热处理工艺进行优化。计算结果表明,重轨钢U75V在珠光体相变过程中,热应变在总应变中占80%以上;相变塑性应变在总应变中所占比例的最大值随应力而增加,当加载应力为-45MPa、相变在577.1℃结束时,相变塑性应变占总应变的比例最大可达到12.5%。
Based on the Greenwood-Johnson theory, the phase transition plasticity of pearlite during the continuous cooling transformation of U75V heavy rail steel was studied by Gleeble-1500D thermal simulation machine. By measuring the expansion curve under different loading stress, the compositional strain, ie, thermal strain, phase transformation strain, elastic strain and phase transformation plastic strain in the total deformation are separated, and the plastic deformation model of the heavy rail steel is established. By numerical simulation, Heat treatment process optimization. The calculated results show that the thermal strain in the heavy rail steel U75V accounts for more than 80% of the total strain in the pearlite transformation. The maximum value of the plastic strain in the total strain increases with the stress. When the loading stress is -45MPa, phase transformation at 577.1 ℃ at the end of the phase strain plastic strain ratio of up to 12.5% of the total strain.