贺地求　袁蒙　赖瑞林

摘   要：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.

关键词：马氏体先进高强钢;高强低合金钢;电阻点焊;微观组织

中图分类号：TG 453                       文献标志码：A

Analysis on Microstructural Evolution of Resistance Spot Welding

between Martensitic Steel and High-strength Low-alloy Steel

HE Diqiu1，2，YUAN Meng1，LAI Ruilin3

（1. College of Mechanical and Electrical Engineering ，Central South University，Changsha 410083，China;

2. State Key Laboratory of High Performance Complex Manufacturing，Central South University，Changsha 410083，China;

3. State Key Laboratory of Powder Metallurgy，Central South University，Changsha 410083，China）

Abstract：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.

Key words：martensitic advanced high-strength steel;high-strength low-alloy steel;resistance spot welding;microstructure

馬氏体先进高强度钢（MS-AHSS）与其他先进高强钢不同之处在于其具有单一的马氏体微观组织结构，只存在少量的铁素体或贝氏体，虽塑性较差，但具有较高的强度. 高强低合金钢（HSLA-AHSS）是一类在普通碳素钢基础上，添加了低于3%的合金元素的高强钢，其强度较相同碳含量碳素钢有明显提高，是为适应大型构件轻量化、提高可靠性及节约钢材的需求发展而来的[1-2].

车身焊接方法之中，电阻点焊应用最为广泛，其在先进高强钢焊接上的应用成为人们研究的热点. Sobhani[3]等人研究了双相不锈钢DSS2304与马氏体钢MS1200异种钢电阻点焊，发现熔核尺寸是控制拉拔模式下拉拔失效分数、承载能力的关键因素;Shirmohammadi[4]等人发现，经不同初始热处理下马氏体钢AISI420电阻点焊熔核区与母材组织基本相同，主要……