Stainless steel has been widely used in the manufacture of metro car-body because of superior characteristics. But the traditional welding joints are prone to poor properties. Ultra-narrow gap laser welding (UNGLW) with low heat input can address property issues. However, due to the complicated parameter interaction in UNGLW, it is difficult to acquire the welding joint with excellent comprehensive properties and improve the welding efficiency simultaneously. For getting the glorious welding joint and improving efficiency, we combined response surface methodology (RSM) with multi-objective optimization to study the UNGLW process. The regressive mathematical models of four welding targets were established successfully. The influence rules of welding parameter interaction on welding targets were determined by RSM analysis. We obtained the optimal welding parameters and the optimized welding joint with excellent comprehensive properties by multi-objective optimization. The relationship between comprehensive property improvement and microstructure characteristics of the optimized welding joint was revealed. It is of great significance to improve the welding quality and efficiency of stainless steel welding joint in UNGLW.

由于其优越的特性，不锈钢已被广泛用于地铁车体的制造中。但是传统的焊接接头容易产生不良性能。低热量输入的超窄间隙激光焊接（UNGLW）可以解决性能问题。但是，由于UNGLW中复杂的参数交互作用，很难获得具有优良综合性能的焊缝并难以同时提高焊接效率。为了获得光荣的焊接接头并提高效率，我们将响应表面方法（RSM）与多目标优化相结合来研究UNGLW过程。成功建立了四个焊接目标的回归数学模型。通过RSM分析确定了焊接参数相互作用对焊接目标的影响规律。通过多目标优化，获得了综合性能优良的最优焊接参数和最优焊接接头。揭示了综合性能改善与优化焊接接头组织性能之间的关系。提高UNGLW不锈钢焊接接头的焊接质量和效率具有重要意义。