铝/钢异种材料点焊接头的力学性能分析

Mechanical Properties of Dissimilar Materials Spot Welded Joint of Aluminum and Steel

采用三相次级整流电阻焊机对铝／钢异种材料进行电阻点焊，研究了工艺参数对接头力学性能的影响．确定出了适合铝／钢异种材料点焊的工艺参数范围和最佳工艺点，对不同工艺参数下接头的拉剪断口形貌进行了分析，并分析了在最佳工艺参数下接头的硬度分布。结果表明：接头的拉剪强度随着焊接时间￡（2～16eye）、焊接电流（20~35kA）以及电极压力（4．8～7．8kN）的增大均为先增大后减小。熔核直径随着焊接时间和焊接电流的增加而增加，随着电极压力的增加而减小。当工艺参数为预压时间等于20cyc、t=8cycle、I=30kA、P-＇-6．8kN时，接头最大剪切力达6476N，形成纽扣断裂。从母材至镀锌钢热影响区，硬度值逐渐升高，在钢的热影响区硬度最大。

Three-phase secondary rectification spot welding machine has been adopted to join dissimilar materials of aluminum alloy and steel. The effect rules of process parameters on the mechanical properties of the welded joints was analyzed. The range of process parameters and optimum parameters were studied, the tensile shear morphology of the welded joints under different process parameters was analyzed and the distribution of hardness of the welded joint under optimum process parameters was analyzed. The results show that： with the increase of welding time t（2-16 cycle）, welding current （20- 35 leA） and electrode pressure （4.8-7.8 kN） the tensile shear strength of the welded joints first increases and then decreases. The nugget size increases with the increase of welding time and welding current. However, the nugget size decreases with the increase of electrode force. The maximum shearing force of 6476 N can be obtained under the parameters： squeeze time is 20 cycle, t=8 cycle, 1=30 kA, P-：-6.8 kN. The button pullout fractures. From the base material to the galvanized steel of heat-affected zone, the hardness gradually increases, and the heat-affected zone of the steel hardness is maximum.