汽车用几种先进高强钢焊点动态冲击性能研究

Study on Dynamic Mechanical Properties of Spot Welds for Advanced High Strength Steels

针对国内某钢厂生产的DP800、DP800-Z、22MnB5三种典型先进高强钢,开展了焊点的动态冲击性能研究。结果表明,随着焊接电流增大,基于焊点力学性能提升,其冲击载荷随位移量关系曲线由平滑向振荡形态变化,峰值冲击力与冲击功均呈单调增加趋势。当焊接电流增大至出现飞溅后,冲击力与冲击功又有所降低,与焊点准静态性能随电流参量的一般变化规律一致,动态冲击力高于静态载荷力。3种钢焊点的冲击失效模式为界面分离、焊核拔出、母材撕裂,在冲击模式下焊点呈现出更为明显的"脆化"趋向。通过建立3种钢焊点的动态冲击性能模型,可用于指导汽车零件点焊接头碰撞安全过程模拟分析,具有一定的工程价值。

In this paper,the dynamic impact properties of three typical advanced automobile high-strength steels,i.e. DP800,DP800-Z and 22 MnB5 produced by a steel plant in China were studied. The results show that with the increase of welding current and the improvement of mechanical properties of welding joints,the curve of impact load-displacement oscillates instead of changing smoothly. The peak impact force and impact energy both increase monotonously. When the welding current increases and welding spatters are generated,the impact force and impact energy decrease,which is consistent with the change of quasistatic performance of welding joints. The dynamic impact force is higher than the static load. The impact failure modes of three kinds of steel welding joints include interface separation,the pull-out of weld nugget and base metal tearing. Under the impact mode,the welding joints show more obvious characteristics of embrittlement. The dynamic impact performance model for three kinds of steel welding joints can be used to guide the impact safety analysis of the spot welding joints on automotive parts.