Abstract Fibre laser spot (circular) welds (LSW) in dual phase DP780 steel grade were produced with fusion areas equivalent to conventional resistance spot welds (RSW) using different fibre laser parameters. Shear tensile properties show significantly higher loads in fibre laser spot welds primarily because of the combined strength of spot size, and hard microstructures in the fusion zone and heat-affected zone (HAZ). Greater HAZ softening is observed at high heat inputs. The transition of failure mode from interfacial to pull-out and the corresponding strength value is primarily controlled by the weld size. The crack initiation site and propagation mechanism were observed to be different for interfacial and pull-out failure. The increased HAZ softening with increase heat input was quantified with nano-indentation hardness measurement technique.

中文翻译：

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激光功率对双相钢激光点焊机械性能的影响

摘要 使用不同的光纤激光参数，在双相 DP780 钢种中进行光纤激光点（圆）焊（LSW），其熔合面积与传统电阻点焊（RSW）相当。剪切拉伸性能在光纤激光点焊中显示出明显更高的负载，这主要是因为光斑尺寸的综合强度以及熔合区和热影响区 (HAZ) 中的硬微结构。在高热输入下观察到更大的 HAZ 软化。失效模式从界面到拔出的转变以及相应的强度值主要由焊缝尺寸控制。观察到裂纹萌生位置和扩展机制对于界面和拉出故障是不同的。随着热输入的增加，热影响区软化的增加通过纳米压痕硬度测量技术进行量化。