Experimental study demonstrates optimal mechanical and corrosion properties at zero defocus in Q235 and 304 dissimilar steel welds, highlighting key parameters for laser welding.
Key Points
Investigate the effect of defocus amount on the microstructure, mechanical properties, and corrosion resistance of laser-welded joints between Q235 carbon steel and 304 stainless steel.
Welded Q235 carbon steel and 304 stainless steel using an EFE-LWM-1500 laser welding machine at a constant 1200 W power across five defocus settings: –10 mm, –5 mm, 0 mm, +5 mm, and +10 mm.
Characterized joint microstructure, phase composition, and tensile fracture using optical microscopy, X-ray diffraction, universal tensile testing, and scanning electron microscopy.
Assessed electrochemical corrosion resistance via an electrochemical workstation evaluating self-corrosion current density and capacitive arc radius.
A 0 mm defocus amount yielded the finest and most uniform weld grains, achieving a maximum tensile strength of 309.46 MPa with ductile fracture and a peak microhardness of 373.05 HV.
Corrosion resistance peaked at 0 mm defocus, exhibiting the largest capacitive arc radius and the lowest self-corrosion current density of 2.24×10⁻⁵ A/cm².