感应淬火后大型齿条残余应力的有限元模拟

Finite Element Simulation of Residual Stress of Large-Scale Gears after Induction Hardening

对G35CrNiMo钢大型齿条的3种感应淬火工艺下的温度变化曲线、显微组织进行了分析,采用盲孔法并结合逐层剥离法测得齿条不同区域的残余应力;建立了齿条的有限元模型和电磁感应与热传导的耦合模型,模拟了齿条的残余应力分布,并与试验结果进行了对比。结果表明:淬火温度较高时,齿条淬硬层中产生较大的热应力,导致齿条在淬火过程中开裂;采用先气淬、后水淬的工艺后淬硬层的温度差降低,热应力减小,有效避免了淬火开裂;齿条表面的最大瞬态拉应力出现在325℃等温线附近,沿齿条方向和垂直于齿条方向的应力大小非常接近,且计算结果与试验结果非常吻合。

Temperature change curves and microstructures of G35 CrNiMo steel large-scale gears under three induction hardening processes were analyzed.The residual stresses in different regions of gears were measured by blind-hole method combined with dissection method.The finite element model and coupling model of electromagnetic induction and thermal conduction were established.The residual stress distribution of gears was simulated and compared with the experiment results.The results show that high thermal stress appeared in the quenching layer at high quenching temperature,which led to cracking during quenching.The temperature gradient of the quenching layer decreased after gas quenching and followed by water quenching,and the thermal stress decreased;the quenching cracking could be avoided effectively.The maximum transient stress on the surface of gears appeared near the 325℃isotherm line.The stress in the rack direction and perpendicular to the rack direction were close,and the calculated results were consistent with the experimental results.