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搅拌摩擦焊接焊后材料微观晶粒结构对构件焊后的力学性能有重要影响。在搅拌摩擦焊接数值模拟的基础上,采用蒙特卡洛模拟方法研究了焊后构件截面晶粒尺寸的分布规律。结果表明,在搅拌区域,母材受搅拌针作用后破碎细化的致密晶粒为初始生长形貌;在热力影响区,材料受到轴肩旋转拉伸的作用,跟踪材料的物质点可得到拉伸比例,并作用于母材晶粒,得到该区域初始晶粒的形貌;热影响区的晶粒变化表现为母材晶粒在温度场作用下的生长。蒙特卡洛迭代步数由材料边界扩展速度推导确定,其受材料经历的温度历程影响。研究结果与文献中晶粒尺寸的分布规律相符,验证了模型用于预测搅拌摩擦焊接晶粒生长的可行性。
The microstructure of the material after friction stir welding has an important influence on the mechanical properties of the components after welding. Based on the numerical simulation of friction stir welding, the distribution law of the grain size at the cross-section of the post-weld component was studied by the Monte-Carlo simulation method. The results show that in the stirring zone, the base material is broken and finely densified grains are the initial growth morphology in the base material. In the heat affected zone, the material is rotated and stretched by the shoulder, and the material points of the tracking material can be pulled Stretching ratio and acting on the base metal grains to obtain the morphology of the initial grains in the region; and the grain growth in the heat-affected zone shows the growth of the base material grains under the action of the temperature field. The Monte Carlo iteration step number is derived from the speed of material boundary expansion, which is affected by the temperature history experienced by the material. The research results are consistent with the distribution of grain size in the literature, which verifies the feasibility of the model for predicting grain growth in friction stir welding.