AA7075-T6铝合金电阻点焊工艺参数优化研究

Optimisation of Process Parameters for Resistance Spot Welding of AA7075-T6 Aluminium Alloy

轻量化结构设计在保证了结构强度的前提下降低了整车质量,减少了能量消耗,成为汽车工业和航空航天的研究重点。本工作通过建立正交实验获取AA7075-T6铝合金的最佳焊接工艺参数。对接头进行拉伸剪切实验、金相观察和显微硬度测试,并对最优参数组合进行数值模拟,以研究焊接工艺参数对接头质量的影响。结果表明:当焊接时间为60 ms、焊接电流为17 kA、电极压力为0.22 MPa时,点焊接头的综合力学性能最好;焊接参数对电阻点焊接头力学性能的影响顺序为焊接时间>焊接电流>电极压力。焊接过程数值模拟得到的熔核尺寸与实验结果一致。焊接过程发生飞溅和熔核存在缩孔缺陷,导致接头的力学性能较差,失效模式为界面断裂。由于焊接过程接头显微组织发生变化,接头显微硬度变化呈“W”形。

The lightweight structural design has emerged as a prominent research priority in the automotive industry and aerospace sectors due to its capacity for reducing overall vehicle weight and energy consumption while ensuring structural strength.This work presented the optimal welding process parameters for AA7075-T6 aluminium alloy,which were determined through orthogonal experiments.Tensile shear tests,metallographic observations,and microhardness tests were performed on the joints,followed by numerical simulations of the optimal parameter combinations to investigate the impact of welding process parameters on joint quality.The results demonstrate that spot welded joints exhibit superior integrated mechanical properties when subjected to a welding time of 60 ms,a welding current of 17 kA,and an electrode pressure of 0.22 MPa.It was observed that the order of influence exerted by welding parameters on mechanical properties of resistance spot weld joints is as follows:welding time>welding current>electrode pressure.The nugget size obtained from numerical simulation aligns with experimental findings.Spattering and the shrinkage defects occur within the nugget during the welding process,leading to compromised mechanical properties in joints and interfacial fracture failure modes.Due to alterations in microstructure within joints during the welding process,microhardness exhibits a‘W’shape.