(1. 青岛四方机车车辆股份有限公司，青岛 266111；
2. 中国科学院金属研究所 中国科学院核用材料与安全评价重点实验室，沈阳 110016)
摘 要: 为了准确预测异种不等厚铝合金电阻点焊熔核尺寸及表面形貌，本文综合考虑电阻点焊过程中电极与工件、工件与工件间接触面积的动态变化以及材料力学性能对接触电阻的影响，建立了较为完善的电阻点焊有限元模型，研究异种不等厚铝合金电阻点焊熔核形成机理以及电极圆角半径对接头形貌的影响规律。结果表明：熔核最先在焊点边缘形成，然后向中心扩展，随着焊接时间的延长，熔核截面由椭圆形向方形转变；电极圆角半径增大，点焊熔核尺寸、压痕深度和凸起高度增加。模型计算得到的熔核尺寸和焊点表面形貌与实验结果符合较好，验证了模型的有效性。
关键字: 铝合金；电阻点焊；数值模拟；熔核形状；表面形貌
（1. CRRC Qingdao Sifang Co., Ltd., Qingdao 266111, China;
2. CAS Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:In order to accurately predict the nugget size and surface morphology of the resistance spot welded dissimilar unequal thickness aluminum alloy joint, a finite element model was established. The dynamic contact between the electrode and the workpieces and the influence of mechanical behavior of the workpieces on the contact resistivity were considered in the model. The nugget formation mechanism of the aluminum alloy during resistance spot welding and the influence of corner radius of the electrode on the joint were analyzed. The calculated results show that the initial nugget forms at the edge of the weld point, then propagates to the center. With the welding time increasing, the cross section of the nugget changes from generally elliptical to square. Besides, the nugget size, the indentation depth and pile-up height increase with the corner radius of the electrode increasing. The effectiveness of the numerical model was verified by comparing the calculated result with experimental result.
Key words: aluminum alloy; resistance spot welding; numerical simulation; nugget shape; surface morphology
