12%Cr耐热钢裂纹萌生临界变形量

Critical deformation amount of crack initiation for 12%Cr heat-resistant steel

以12%Cr耐热钢为研究对象,基于Gleeble-3800D热模拟试验机进行高温拉伸实验,得到不同变形温度和应变速率下的高温拉伸真应力-真应变曲线。结果显示:应变速率越大、温度越低时材料的抗拉强度及屈服强度越大;由高温拉伸断口微观组织可知,温度越高、应变速率越小,材料的塑性越好。结合高温拉伸实验与数值模拟方法确定了12%Cr耐热钢热锻过程中的临界损伤值,并进一步将裂纹萌生临界损伤值转化为实际热锻的临界变形量,建立了12%Cr耐热钢在给定变形温度和应变速率条件下热锻成形过程中的临界变形量模型,并在500 N液压机上进行了镦粗工艺验证,为超超临界转子锻造成形工艺提供了理论参考。

For 12%Cr heat-resistant steel,the high-temperature tensile experiments were conducted by thermal simulation test machine Gleeble-3800D,and the high-temperature tensile true stress-true strain curves at different deformation temperatures and strain rates were obtained.The results show that the higher the strain rate and the lower the temperature,the greater the tensile strength and yield strength of material.The microstructure of high-temperature tensile fracture indicates that the higher the temperature and the lower the strain rate,the better the plasticity of material.By combining the high-temperature tensile experiments and numerical simulation methods,the critical damage value during the hot forging process of 12%Cr heat-resistant steel was determined,and the critical damage value for crack initiation was further converted into the actual critical deformation amount during the hot forging process.A critical deormation amount model for the hot forging process of 12%Cr heat-resistant steel under the given deformation temperature and strain rate conditions was established,and the upsetting process was verified by 500 N hydraulic press,which provides the relevant theoretical references for the forging process of ultra-supercritical rotors.