Weld zone porosity elimination process of galvanized steel zero-gap lap joints in remote laser spiral welding

The remote Laser spiral welding was utilized to zero-gap lap welding of galvanized steel. The relationship between pores in the weld zone and process parameters were investigated. The combination of high keyhole velocity and small spiral spacing was found to be essential for eliminating porosity in the weld area. As the spiral pitch decreases from 0.7 mm to 0.3 mm, the porosity decreases rapidly from approximately 20% to 0%. When the spiral spacing of 0.3 mm, the porosity reaches an acceptable quality level of less than 1%. The porosity tends to decrease as the keyhole velocity increases from 3 m min(-1) to 9 m min(-1). At the spiral pitch of 0.3 mm and keyhole velocity of 9 m min(-1), the porosity in the weld area is almost completely suppressed. The peak shear strength of the spiral weld without porosity was 8819.8 N and the peak shear strength of the spiral weld with porosity was 5104.3 N. The tensile shear performance was increased by 72.8%. The low porosity caused by the spiral laser beam improves the tensile shear strength of the oscillating weld.