NOS525钢旋转平双耳热锻模具失效分析及热处理工艺优化

Failure analysis and heat treatment process optimization of rotary flat binaural hot forging die for NOS525 steel

为解决某NOS525钢旋转平双耳热锻模具塌陷失效问题,结合其失效形式及部位,对所取试样的材料成分、硬度和金相组织、拉伸及冲击力学性能等进行了研究;同时,借助Deform-3D软件对锻造过程进行仿真;最后,结合失效形式及失效原因对该材料热处理工艺进行优化。试验和仿真结果表明,模具材料成分异常,且存在淬火过热和回火不充分现象,造成马氏体粗大,且有较多奥氏体残留,导致模具材料的强度、韧性、硬度不足,此外,在锻造过程中模具的高应力和高温集中区域与模具失效部位相吻合,最终,导致模具表面过早发生塌陷与龟裂失效。热处理优化后最终得到的最佳热处理温度为淬火温度为1090℃,三次回火温度分别为560、570和570℃,使材料的力学性能得到了显著提升。

To solve the problem of collapse failure for a NOS525 steel rotary flat binaural hot forging die,the material composition,hardness,metallographic organization,tensile properties and impact mechanical properties of the taken specimens were studied by combining the failure forms and parts.At the same time,the forging process was simulated by software Deform-3D.Finally,the heat treatment process of the material was optimized by combining the failure forms and the causes of failure.The experimental and simulation results show that the composition of die material is abnormal,and there are quenching overheating and tempering insufficiency phenomena,resulting in coarse martensite and more austenite residue,which leads to insufficient strength,toughness and hardness of die material.In addition,the high stress and temperature concentration area of the die in the forging process coincides with the failure part of the die,which leads to premature collapse and cracking failure of the die surface,finally.Thus,after heat treatment optimization,the best heat treatment temperature are the quenching temperature of 1090℃,and three tempering temperatures of 560,570 and 570℃,respectively,which improves the mechanical properties of the material,significantly.