热成形钢/T型镀锌螺母的电容储能凸焊接头组织及性能

Microstructure and Property of Capacitor-Discharging Projection Welding Joints of T-Type Galvanized Nuts to Hot-Stamping Steels

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和力学性能的影响规律,并分析了凸焊接头的组织演变、硬度分布、失效断裂模式以及断口形貌.结果表明:随着焊接电压的升高,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;凸焊接头的断裂模式为界面断裂模式、拔出断裂模式和拔出-界面断裂模式;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 T-type galvanized nuts to USIBOR1500 hot-stamped steels was analyzed by the capacitor discharging welding process(CDW).In this investigation,the effect of voltages on the welded physical attributes and the mechanical properties of joints were investigated.The hardness profiles,microstructure evolutions and failure modes of welded joints were studied.Results show that with the increase of welding voltages both the nugget diameter and the pull-out strength first increase and then decrease,while the weld point diameter varies slightly.The welded joints fail in three modes:interfacial failure mode(IF),pullout failure mode(PF)and PF-IF mode.Quasi cleavage fracture surface is observed on the fracture of IF mode.Slip separation and quasi cleavage fracture surface are found on the fracture of PF and PF-IF mode.Pronounced HAZ softening occurs on ICHAZ and SCHAZ zone due to the appearance of bainite,ferrite and tempered martensite.