Optimization of Laser Welding Parameters and Fixed Stress Span Design to Minimize Deformation in Ultra-Thin Ferritic Stainless Steel

Ultra-thin ferritic stainless steel, essential for applications such as proton exchange membrane fuel cells, presents challenges during pulsed laser welding due to thermal stresses causing deformation. This study explores the effects of welding parameters and clamp design on deformation through finite element simulations and experiments. Key parameters, including laser power (500–700 W), welding speed (6–14 mm/s), and pulse frequency (6–14 Hz), were systematically varied. Results revealed a non-linear relationship between these parameters and weld quality, with the optimal combination identified as a laser power of 600 W, welding speed of 10 mm/s, and pulse frequency of 10 Hz. Additionally, the fixed stress span applied by clamps significantly influenced stress–strain and displacement fields. For instance, residual stress decreased from 267 MPa at a 5 mm span to 189 MPa at a 20 mm span. Displacement values increased from 4.746 × 10⁻3 mm at 5 mm to 8.111 × 10⁻3 mm at 20 mm, while strain initially decreased but rose slightly from 1.648 × 10⁻3 at 10 mm to 1.719 × 10⁻3 at 15 mm. The 5 mm stress span was found optimal, producing a smooth and defect-free weld surface. This study bridges gaps in understanding the deformation mechanics of ultra-thin ferritic stainless steel, offering practical guidelines for optimizing laser welding parameters and clamp designs to achieve superior weld quality.