冷却速度对42CrMo环坯铸造二次枝晶臂间距及裂纹缺陷的影响

Effect of Cooling Rate on Secondary Dendrite Arm Spacing and Crack Defects of 42CrMo Casting

针对提出的铸辗连续成形新型工艺,从细化组织、提高铸件质量,避免裂纹缺陷方面考虑,分别对采用砂型和金属型的42CrMo铸造环件进行温度场、应力场的数值模拟,利用模拟结果,进行凝固冷却过程裂纹倾向性预测。得到铸坯冷却速度越大,在铸型内停留时间越长,铸件收缩量越大,热应力越大,形成裂纹的倾向性也越大。边角部是最容易形成裂纹的部位。同时通过对铸坯进行微观组织数值模拟,建立冷却速度与二次枝晶臂间距的函数关系,分析冷却速度对组织性能的影响,得到采用金属型铸造可获得比砂型铸造组织性能好的铸坯。通过对比两种铸造方式,确定采用金属型铸造在1 050℃左右温度下出模,可获得高质量无缺陷铸坯,可基本满足基于42CrMo环坯的铸辗连续成形工艺要求。分析结果可为预测铸件质量,试验研究提供理论参考。

Based on the proposed a new technology casting-rolling continuously forming of ring parts, it is considered to detail organization, improve the quality of castings, and avoid the crack defects. Numerical simulations of temperature field and stress field are taken respectively in 42CrMo of sand mold and metal mold casting, solidification cooling process and the crack tendency prediction is studied by using the simulation results. The greater cooling rate in the cast was, the longer the casting stayed in the mold and the bigger the casting shrinkage is, the greater thermal stress will became, the greater the inclination of forming crack isare. The part of the edge is the easier to form cracking. By the numerical simulation of the microstructure for the casting, the functions of the cooling velocity and the secondary dendrite arm spacing are established. The effect of cooling rate on the organization performance is analyzed. It is obtained that the casting performance is the better using the metal mold casting than using the sand mold casting. Comparing the two casting methods, it is identified that the higher quality and no defects casting may be got when casting temperature out of the mold about 1 050 ℃. It can be satisfied in technology requirement based on casting-rolling continuously forming of ring parts. Analysis results may provide a theoretical reference for forecast the quality of castings and experiments.