摘要
采用电阻点焊工艺对1.5 mm厚的镀锌钢板与高强钢板进行了连接试验。通过金相显微镜、扫描电镜、电子拉伸试验机以及硬度计等分析手段,研究了不同焊接电流对接头形貌和力学性能的影响。结果表明:采用电阻点焊工艺实现了镀锌钢与高强钢的可靠连接。当焊接电流为8 kA时,接头的拉剪载荷最大,为13.6 kN,随着焊接电流的继续增大,接头表面容易产生飞溅。接头高强钢侧热影响区由于回火马氏体和细晶马氏体的生成,出现了明显的软化区和硬化区,而镀锌钢侧有大量马氏体生成,热影响区硬度明显大于母材区。当焊接电流为4 kA时,接头断裂形式为界面断裂;当焊接电流为5~7 kA时,接头断裂形式主要为镀锌钢侧熔核被拔出;当焊接电流为8~10 kA时,接头断裂形式转变为高强钢侧熔核被拔出。
The connection tests of galvanized steel plate and high strength steel plate with thickness of 1.5 mm were carried out by using resistance spot welding. The effects of welding current on the morphology and mechanical properties of the joints were studied by using metallurgical microscope, scanning electron microscope, electronic tensile testing machine and hardness tester, etc. The results show that reliable connection between galvanized steel and high strength steel is achieved by using resistance spot welding. When the welding current is 8 kA, the tensile-shear load is the maximum, which is 13.6 kN. With the increase of welding current, welding spatter occurrs on the joint surface. Due to the formation of tempered martensite and fine grain martensite in the heat affected zone at the side of high strength steel, there is obvious softening and hardening zone. However, a lot of martensite forms at the side of galvanized steel, and the hardness of heat affected zone is obviously bigger than that of base metal. When the welding current is 4 kA, the fracture mode of the joint is the interface fracture. When the welding current is 5-7 kA, the fracture mode of the joint is mainly that the nugget at the side of galvanized steel is pulled out. When the welding current is 8-10 kA, the fracture mode of the joint transforms to that the nugget at the side of high strength steel is pulled out.
出处
《热加工工艺》
CSCD
北大核心
2017年第13期225-229,共5页
Hot Working Technology
基金
重庆市教育科学"十二五"规划2014年度课题(2014-GX-128)
重庆市教委科学技术研究项目(KJ1403005)
关键词
电阻点焊
镀锌钢
高强钢
微观组织
力学性能
resistance spot welding
galvanized steel
high strength steel
microstructure
mechanical properties