In resistance spot welding, groove shape has an important influence on joint performance. The groove shapes designed in this study are applied to a bimetal band-saw blade, which has theoretical and application value. Three groove shapes (straight, arc, and V-shaped) are designed on the backing bracket to weld WC-10Co and B318 steel. The welding process is imaged using a high-speed camera, and the distribution and change of heat in the welding process are compared and analyzed. The shear force, interfacial microstructure, and fracture surface are analyzed by shear tests, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, and the relationship among the heat distribution, interfacial microstructure, and shear force is investigated. The results show that the reaction duration and temperature distribution at various interfacial positions of the different groove shapes are heterogenous, leading to an uneven interfacial reaction. For short welding time, the straight joint with heat concentrated in the center of the interface has larger deformation and so larger shear force. For long welding time, the reaction layer forms at the interface. At the straight joint interface, the η phase is distributed more and aggregates, thereby decreasing the shear force. At the other two joint interfaces, the distribution is more eutectic and the η phase is relatively dispersed, so the shear force is higher. The maximum shear forces of the joints are 1068.2 N (straight), 1138.1 N (arc), and 1231.7 N (V-shaped). For short welding time, the metallurgical reaction of the interface is insufficient, and the joint fractures at the interface. For long welding time, the fracture usually starts from the cracks on the WC-Co side, then propagates to the interfacial reaction layer, and finally fractures at the steel side. The appearance of cracks, reaction layer, extrusion, and inclusions reduces the shear force of the joint.

在电阻点焊中，坡口形状对接头性能有重要影响。本研究设计的槽形应用于双金属带锯条，具有理论和应用价值。支撑架上设计了三种坡口形状（直线、圆弧和V形），用于焊接WC-10Co和B318钢。利用高速摄像机对焊接过程进行成像，对比分析焊接过程中热量的分布和变化。通过剪切试验、扫描电子显微镜和能量色散X射线光谱分析剪切力、界面微观结构和断裂表面，并研究热分布、界面微观结构和剪切力之间的关系。结果表明，不同凹槽形状的不同界面位置的反应持续时间和温度分布不均一，导致界面反应不均匀。对于较短的焊接时间，热量集中在界面中心的直接头变形较大，因此剪切力较大。对于较长的焊接时间，反应层在界面处形成。在直接头界面处，η 相分布更多并聚集，从而降低了剪切力。在另外两个接头界面处，分布更共晶，η相相对分散，因此剪切力更高。接头的最大剪切力为 1068.2 N（直线）、1138.1 N（弧形）和 1231.7 N（V 形）。焊接时间短，界面冶金反应不足，以及界面处的接头断裂。焊接时间长时，断裂通常从WC-Co侧的裂纹开始，然后扩展到界面反应层，最后在钢侧断裂。裂纹、反应层、挤压和夹杂物的出现降低了接头的剪切力。