马氏体钢与高强低合金钢电阻 点焊组织结构演变分析

本文研究了马氏体钢与高强低合金钢电阻点焊接头微观组织结构演变,对厚度为1.2 mm的MS1400、HSLA420进行电阻点焊试验,通过改变焊接时间、电流、压力得到拉剪试样,利用力学性能试验机进行拉剪试验,通过产生拔出失效模式来确定较优的点焊工艺参数.分析较优参数下的焊件熔核区及两侧热影响区微观组织,发现熔核区完全马氏体化;热影响区则主要为铁素体、马氏体、粒状贝氏的混合组织;对接头进行硬度测试,发现各区域组织变化与显微硬度分布曲线基本一致.

Analysis on Microstructural Evolution of Resistance Spot Welding between Martensitic Steel and High-strength Low-alloy Steel

The paper addresses the microstructure evolution of dissimilar resistance spot welding between martensitic steel and high-strength low-alloy steel. Resistance spot welding tests were carried out on MS1400 and HSLA420 with a thickness of 1.2 mm. Shear samples were obtained by changing the welding time, current and pressure. Shear tests were carried out by a tensile testing machine. The better welding process parameters were determined by generating the pull-out failure mode. By analyzing the microstructure of fusion zone and heat-affected zone on both sides under better parameters, it is found that the fusion zone is completely martensitized. The heat-affected zone is mainly composed of mixed ferrite, martensite and granular bainite structure. The microhardness test of the joint shows that the microstructure changes in each region are basically consistent with the microhardness distribution curve.