Effects of Aluminum on Weldability of Nonoriented Electrical Steel Sheets

• Published in: ISIJ International Vol. 40; no. 1; pp. 77 - 83
• Main Authors: Kurosaki, Yousuke, Hirose, Kikuji, Shiozaki, Morio, Kohno, Rokuro, Miyazaki, Yasunobu, Ohara, Masahiro
• Format: Journal Article
• Language: English
• Published: Tokyo The Iron and Steel Institute of Japan 01.01.2000; Iron and Steel Institute of Japan
• Subjects: aluminum; Applied sciences; bead width; blowhole; convection; electrical steel; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Metals. Metallurgy; surface tension; weldability; Welding; Property composition relationship; Composition effect; Aluminium; Aluminium addition; Experimental study; Weldability; GTA welding; Convection; Electric furnace steel; Weld
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.40.77

The effects aluminum has on the weldability of nonoriented electrical steel sheets as related to blowholes and welding bead width was studied. The addition of aluminum to steel sheets decreased the numbers of blowholes and widened the welding bead width in Gas Tungsten Arc Welding. The following effect of aluminum in steel sheets on welding blowholes was observed. The organic components in the inorganic-organic coating applied on steel sheets gasified due to welding heat and CO gas was generated. The gas dissolved in weld pool and CO gas became dissolving C and O. Aluminum acted as a deoxidizer and decreased dissolving oxygen. CO gas which generated at solidification of the weld pool was decreased. As a result, the addition of aluminum in steel decreased blowholes. The effect of aluminum in steel sheets had on welding 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 annealing, oxide film formed on the cut surface during consumer annealing. Aluminum 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 aluminum in steel made the shape of welding bead shallow and wide. The driving force of convection in the weld pool of nonoriented electrical steel sheets was the surface tension because the penetration changed by the presence of oxide film on the surface in Al-free specimens even in laser welding in which electromagnetic force did not work.