H13热作模具钢感应加热循环过程的数值模拟

Numerical simulation on induction heating cycle process of H13 hot-work die steel

基于热作模具钢热疲劳试验国家标准,建立了H13钢热疲劳感应加热循环过程的多物理场耦合数值模型,研究了感应加热循环过程中试样温度的演变规律和应力累积现象,并对试样热疲劳寿命进行预测。研究表明,在感应加热循环过程中,试样心表的温度演变规律存在明显差异。由于集肤效应和试样形状的影响,加热结束时,最大温差出现在试样圆周面与小平面交界部位,约为210℃,最小温差出现在试样有效加热区域的中心,约为85℃;随感应加热循环次数增加,试样的等效应力和最大主应力均呈现累积效应,尤其是试样的拐角部位,经20次循环后其等效应力提高了6%,该处为热疲劳主裂纹的形成和扩展部位;结合数值模拟结果和应变疲劳寿命预测模型,对H13钢热疲劳寿命进行预测发现,试样热疲劳寿命随感应加热循环次数的增加而减小;模拟结果与实验结果吻合,表明本文建立的数值模型可为热疲劳行为的研究提供新的方法和思路。

Based on the national standard of hot-work die steel thermal fatigue testing, a multi-field coupled numerical model of H13 steel thermal fatigue testing was established to evaluate the temperature variations rule and the stress accumulation phenomenon of the sample during the induction heating cycle. Furthermore, the thermal fatigue life of the H13 steel sample was predicted. The results indicate that there is a significant difference in the temperature variations between the center and surface of the sample during the induction heating cycle. Due to the influence of skin effect and the geometry of the sample, at the end of heating stage, the maximum temperature difference （ about 210 ℃ ） occurs at the junction of the circumferential surface and the longitudinal plane （ point P2 ） , and the minimum temperature difference （almost 85 ℃ ） exhibits at the center of the effective heating areas. With the increasing induction heating cycles, both the effective stress and the maximum principal stress of the sample present an accumulation phenomenon, especially in the corner of the sample, where the effective stress has increased by 6% after twenty induction heating cycles and the formation and extension of the thermal fatigue main crack also occurs here. In addition, combined the predicted results with the strain fatigue life prediction model, the predicted thermal fatigue life of H13 steel shows a decreasing trend with the increasing the induction heating cycle number. The predicted results agree well with the experimental ones, which indicate that the numerical model established in this investigation can provide a new method to investigate the thermal fatigue behavior.