文中探究了热成形钢USIBOR1500与T型镀锌螺母储能凸焊工艺，研究了焊接电压对凸焊接头几何属性、组织与性能的影响规律，并分析了凸焊接头微观组织演变、硬度分布、失效断裂模式以及断口形貌。结果表明，随着焊接电压升高，焊点直径变化较小，熔核直径先增大后减小，接头推出强度先升高后降低，接头断裂模式由界面断裂转变为拔出断裂或拔出-界面断裂，界面断裂为准解理断裂，拔出断裂和拔出-界面断裂同时具有滑移分离断裂和准解理断裂。热影响区软化发生在热成形钢侧不完全淬火区和回火区。

Resistance projection welding of speed nuts to USIBOR1500 hot-stamped steels was analyzed by the capacitor discharging welding process (CDW). In this investigation, mechanical properties, weld physical attributes and metallographical examinations were used to evaluate the suitable CDW conditions. Hardness characteristics, failure mode and fracture morphology were studied. With the increase of welding volts, nugget size and pull-out strength increase before expulsion, and failure mode changes to PF- and PF-IF mode from IF mode. Quasi cleavage fracture surface was observed on fracture of IF mode. Slip separation and quasi cleavage fracture surface were found on fracture of PF and PF-IF mode. Pronounced HAZ softening was observed on ICHAZ and SCHAZ zone due to the appearance of bainite, ferrite and tempered martensite.