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利用Gleeble 3500热力模拟试验机对22MnB5板材进行高温拉伸试验,研究了该材料在变形温度为700、800和900℃以及应变速率为0.01、0.1、1和10 s–1下的高温变形行为.在同一温度下,22MnB5的断裂应变随应变速率增加而呈现增加趋势,温度升高加剧这种趋势.建立了耦合损伤基于位错密度的统一黏塑性本构模型,该模型考虑了高温变形中损伤的演化规律,能够描述了应力–应变曲线后期的陡降段.利用遗传算法确定并优化该本构模型中的材料常数,所得材料常数确定的本构模型能够较好地预测22MnB5高温拉伸变形下的流变应力,并能较好地描述材料损伤演化规律.
The high temperature tensile test of 22MnB5 sheet was carried out by Gleeble 3500 thermal simulation test machine. The deformation behavior of 22MnB5 sheet at 700,800 and 900 ℃ and strain rate of 0.01, 0.1, 1 and 10 s-1 was studied. At the same temperature, the fracture strain of 22MnB5 increases with the increase of strain rate, and the increase of temperature aggravates this trend. A unified visco-plastic constitutive model of coupling damage based on dislocation density is established, which takes into account the damage in high temperature deformation Which can be used to describe the steep descent of the stress-strain curve in the later stage.Using genetic algorithm to determine and optimize the material constants in the constitutive model, the constitutive model obtained from the material constants can predict the high temperature tensile deformation of 22MnB5 Under the flow stress, and can better describe the evolution of damage law.