新型双相高强钢点焊接头拉剪力学性能与组织分析

Shear mechanical property and microstructure of spot welded joint of a new dual-phase high strength steel

以新型双相高强钢为研究对象,采用不同的工艺参数进行正交试验,并对点焊接头进行拉伸测试,分析各因素对电阻点焊质量的影响;然后对点焊接头金相组织进行观察,分析新型双相高强钢点焊接头的失效模式和接头金相组织特征。结果表明,点焊接头抗剪载荷的最优工艺参数为:焊接电流8 k A,焊接时间15 cyc,电极力2k N,此时点焊接头的最大剪切力达到最大值。优质焊点在拉剪试验中最先从熔核边界附近开裂,随后延伸至母材部分,直至点焊接头全部断开。

The effect of various factors on the resistance spot welding quality of a new dual-phase high strength steel was analyzed by orthogonal test and shear test. The microstructure and mechanical properties of the spot welded joints were investigated by metallographic microstructure test. The failure mode and the metallographic microstructures of the joints were analyzed. The results show that the maximum shear stress of the spot welded joint reaches the maximum at the welding current of 8 kA,the welding time of 15 cyc and the electrode force of 2 kN. In the tensile test of high-quality welded joints,the crack initiates from the nugget near the border,then spreads to the base metal,until the spot welded joints fractures.