Effects of aluminum on weldability of nonoriented electrical steel sheets

The effects aluminum has on the weldability of nonoriented electrical steel sheets as related to blowholes and welding bead width was studied. The add ition of aluminum to steel sheets decreased the numbers of blowholes and wi dened the welding bead width in Gas Tungsten Arc Welding. The following eff ect of aluminum in steel sheets on welding blowholes was observed. The orga nic components in the inorganic-organic coating applied on steel sheets gas ified due to welding heat and CO gas was generated. The gas dissolved in we ld pool and CO gas became dissolving C and O. Aluminum acted as a deoxidize r and decreased dissolving oxygen. CO gas which generated at solidification of the weld pool was decreased. As a result, the addition of aluminum in s teel decreased blowholes. The effect of aluminum in steel sheets had on wel ding bead width was as follows. Oxygen has been known to make the shape of welding bead deep and narrow. In the case of welding after consumer anneali ng, oxide film formed on the cut surface during consumer annealing. Aluminu m deoxidized the dissolved oxygen which penetrated from the oxide film into the weld pool at the time of welding. As a result, the addition of aluminu m in steel made the shape of welding bead shallow and wide. The driving for ce of convection in the weld pool of nonoriented electrical steel sheets wa s the surface tension because the penetration changed by the presence of ox ide film on the surface in Al-free specimens even in laser welding in which electromagnetic force did not work.