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结合等温压缩实验获得的IN690合金本构关系,建立了该合金管热挤压过程的有限元模型,该模型考虑了坯料与模具的热传导、对流换热及摩擦功与塑性功的热转换.模拟结果表明:坯料在变形区附近温度开始升高,进入变形区内急剧升高,且在模孔出口靠近芯棒处温度达到最高,芯棒附近的温度大于挤压筒附近的温度;填充挤压阶段结束时出现最大温升.分析得到了工艺参数对出口温度的影响规律:挤压速度越大,出口温度越高,速度过慢将会使出口温度下降严重;坯料预热温度越高,出口温升越小;当摩擦因数小于0.04时,摩擦因数对出口温度影响很小,但摩擦因数大于0.1时出口温度明显升高.
Combined with the constitutive relation of IN690 alloy obtained by isothermal compression experiment, a finite element model of hot extrusion process of this alloy tube was established, which considered the heat conduction, convection heat transfer and heat transfer between friction work and plastic work of the billet and die. The results show that the temperature of the billets begins to increase near the deformation zone and rises sharply into the deformation zone. The temperature near the mandrel at the outlet of the die orifice reaches the highest temperature, and the temperature near the mandrel is higher than the temperature near the extrusion cylinder. The maximum temperature rise occurred at the end of the stage.The influence of the process parameters on the outlet temperature was analyzed.The higher the extrusion speed, the higher the outlet temperature and the slower the outlet temperature would cause the outlet temperature to drop seriously. The higher the preheating temperature, When the friction coefficient is less than 0.04, the friction coefficient has little effect on the outlet temperature, but the outlet temperature increases obviously when the friction coefficient is greater than 0.1.