DP590双相钢激光胶接点焊接头的疲劳强度分析

为对比分析DP590双相钢激光胶接点焊接头和激光点焊接头的疲劳强度,针对1.5mm厚的DP590钢板,以焊接功率、焊接时间、离焦量为变量,进行三因素三水平的激光点焊和激光胶接点焊正交实验,通过拉剪实验获得两种接头的失效载荷;应用方差分析方法辨析焊接工艺参数对两种接头焊接质量的影响程度;开展疲劳实验,建立接头的载荷-寿命曲线,并对胶接点焊接头进行疲劳断口分析。结果表明,胶接点焊接头的拉剪失效载荷和疲劳强度均大于点焊接头;对胶接点焊接头和点焊接头的力学性能影响最大的工艺参数分别是焊接功率、焊接时间;胶接点焊接头的疲劳裂纹主要起源于热影响区,疲劳裂纹扩展区存在明显的疲劳条带,瞬断区出现典型韧窝形貌。

Fatigue strength analysis of laser spot weld-bonded joints for DP590 dual-phase steel

The orthogonal experiment of laser spot welding and laser spot weld bonding was designed for 1.5 mm thick DP590 by using welding power, welding time and defocusing amount as variables. The tensile tests were made to obtain the tensile strength of two joints. The variance analysis of the mechanical properties were carried out to acquire the impact of various factors on the two joints. In order to achieve the load-life curves, fatigue test was practiced and the fatigue fracture of weld-bonded joints was analyzed. The results show that the tensile and fatigue strength of weld-bonded joints are higher than these of the spot welding joints. The process parameters that have the greatest influence on the mechanical properties of the weld-bonded joint and the spot welding joint are the welding power and the welding time. The fatigue cracks of weld-bonded joints initiate in the heat-affected zone, and there is obvious fatigue striation in the fatigue crack extension area and typical dimples appear in the instantaneous fracture zone.