通过电阻点焊对2.0 mm厚DP780双相钢板进行焊接, 通过接头的焊接质量检验得到了较佳的焊接参数, 并研究了接头的显微组织、剪切力和显微硬度。结果表明: 较佳的点焊工艺参数为焊接压力5 kN, 焊接电流9～10.5 kA, 焊接时间320～400 ms; 在较佳的焊接工艺下, 点焊接头的熔合区主要为马氏体, 热影响区主要由尺寸较小的马氏体、铁素体和贝氏体组成; 当焊接电流为9.5 kA、焊接时间为400 ms、焊接压力为5 kN时, 点焊接头的剪切力和熔核直径均达到最大, 分别为32.58 kN和7.9 mm; 在相同的点焊时间和压力下, 随着焊接电流增大, 熔核区的显微硬度降低。

DP780 duplex stainless steel with thickness of 2.0 mm was welded by resistance spot welding, relatively good welding parameters were obtained by the welding quality testing, and the microstructure, shear force and microhardness of the spot welded joints were studied. The results show that the relatively good process parameters were the welding pressure of 5 kN, welding current of 9-10.5 kA, welding time of 320-400 ms. Under the relatively good welding process conditions, the fusion zone of the joint was mainly martensite and the heat affected zone was composed of martensite, ferrite and bainite. When the welding current was 9.5 kA, welding time was 400 ms, welding pressure was 5 kN, the shear force and the nugget diameter were the biggest, and they were 32.58 kN and 7.9 mm, respectively. At the same spot welding time and pressure, the microhardness of the fusion zone decreased with the increase of welding current.