2524-T3铝合金回填式搅拌摩擦点焊过程的数值模拟

Numerical Simulation of 2524-T3 Aluminum Alloy in Refill Friction Stir Spot Welding

目的分析焊接接头温度场、应力场的分布情况,并着重讨论焊接转速对接头孔洞分布规律的影响。方法基于ABAQUS有限元分析软件,对2524-T3铝合金回填式搅拌摩擦点焊过程进行了模拟,分析了焊接过程中材料内部温度场、应力场及焊点底部孔洞的变化情况,并在此基础上采用小孔法对焊点周围残余应力进行了测量,与模拟结果进行了对比分析。结果焊接转速由2200 r/min提高至3000 r/min,焊接过程达稳定摩擦时焊接温度由489℃增至518℃。焊接结束时焊件表面残余应力数值均在100~200MPa,与实际小孔法测得数值吻合良好。结论焊接转速的提高导致焊接过程中各阶段峰值温度提高,在焊件横截面还可观察到沿厚度方向存在较大的温度梯度。接头孔洞数量随焊接转速先下降后上升,在焊接转速为2800 r/min时,孔洞数量达最少。另外,焊件表面残余应力呈四周对称分布,并在压紧环外径处出现最大值。

The paper aims to analyze distribution of temperature field and stress field of welded joints, and discuss the influences of rotational speed on the distribution of joint voids emphatically. Based on ABAQUS finite element analysis software, the refill friction stir spot welding process of 2524-T3 aluminum alloy was simulated to analyze the process of welding temperature field, stress field and internal changes of the voids at the bottom of the joint. On this basis, the residual stress around the joint was measured by the blind-hole method, and compared with the simulation results. As the welding speed increased from 2200 r/min to 3000 r/min, the welding temperature increased from 489 ℃ to 518 ℃ when the welding process reached stable friction. At the end of the welding, the residual stress values of the welding parts were 100-200 MPa, which was in good agreement with the actual values measured by the blind-hole method. The increase of the rotational speed leads to the increase of the peak temperature during welding. A large temperature gradient along the thickness direction can be observed in the cross-section of the workpiece. The number of joint voids increases first and then decreases with the rotational speed. And the number of voids is the smallest when the rotational speed is 2800 r/min. In addition, the residual stress on the welding surface is distributed symmetrically around, and the maximum value appears at the external diameter of the clamp.