搅拌摩擦焊多平面搅拌头对材料流动行为的影响

doi:10.3901/JME.2022.06.081

摘要/Abstract

摘要： 与传统熔化焊相比，搅拌摩擦焊(Friction stir welding,FSW)因温度梯度较小，可以减少焊接裂纹和残余变形，是一种极具前途的铝合金固相焊接方法。相同焊接工艺参数下，搅拌头是影响焊接热输入和材料流动的主要因素之一，决定焊缝的组织与性能。基于固体力学有限元法和A7N01铝合金材料本构方程，建立基于Deform软件搅拌摩擦焊刚黏塑性仿真模型，并通过焊接试验的测温曲线和试验缺陷完成了模型验证，对比分析了圆台、三平面、四平面搅拌头平面对搅拌摩擦焊稳态焊接阶段的温度场、峰值温度曲线和材料流动行为的影响。结果表明，多平面搅拌头的焊接热输入高于圆台搅拌头，在材料塑性流动范围、流动均匀性和有效焊缝等指标方面优于圆台搅拌头。搅拌头的平面特征在材料流动过程中能够起到明显的挤压作用，从而细化焊缝区的晶粒，提高焊接接头的力学性能。基于仿真和试验结果分析，揭示了焊接犁沟缺陷的成因，并提出了预防措施。

关键词: 搅拌摩擦焊, 多平面搅拌头, 材料塑性流动, 焊接热输入

Abstract: Compared with conventional fusion welding, Friction stir welding (FSW) is a very promising method for solid phase welding of aluminum alloys due to its low temperature gradient, which can reduce welding cracks and residual deformation. Under the same welding parameters, the stirring pin is one of the main factors affecting the welding heat input and material flow, which determines the microstructure and properties of welding seams. Based on solid mechanics finite element method (FEM) and A7N01 aluminum alloy material constitutive equation, this study simulated friction stir welding of an A7N01 weld using the Deform software. The rigid visco-plastic simulation model was verified by comparing with measured temperatures and observed defects in welding tests. Three kinds of stirring pins, namely cone, three-plane and four-plane, were designed. The model was then used to investigate the influence of three kinds of stirring pins on the temperature field, peak temperature curve and material flow behavior in the steady-state welding stage of friction stir welding. The results showed that the welding heat input of the multi-facets stirring pins (3P & 4P) was higher than that of the cone stirring pin (Y), and it was better than that of the cone stirring pin in terms of plastic flow range, flow uniformity and effective weld. The flow materials was strongly extruded by the sitrring pin facets, so as to refine the grain in the weld zone and improve the mechanical properties of the welded joint. Based on the simulation and test results, the causes of the welding furrow defects were revealed, and the preventive measures were put forward.

Key words: friction stir welding, multi-facets stirring pin, plastic flow of material, welding heat input

中图分类号:

TG156

杨智勇, 李武鹏, 李志强, 刘小龙, 李卫京. 搅拌摩擦焊多平面搅拌头对材料流动行为的影响[J]. 机械工程学报, 2022, 58(6): 81-90.

Yang Zhiyong, LI Wupeng, LI Zhiqiang, Liu Xiaolong, LI Weijing. Effect of Multi-facets Stirring Pin on Material Flow Behavior for Friction Stir Welding[J]. Journal of Mechanical Engineering, 2022, 58(6): 81-90.

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