Improved steel/aluminum bonding in bimetallic castings by a compound casting process

• DOI: 10.1016/j.jmatprotec.2015.06.032
• Publication Date: 2015-07-08T00:40:31Z
• Authors: Wenming Jiang; Zitian Fan; Chi Li
• Keywords: Bimetallic strip; Bonding strength

Abstract Different surface treatment methods of steel inserts, including aluminizing, coating surface modifier as well as a combination of coating surface modifier and aluminizing (surface modifier + aluminizing), were introduced into the fabrication of carbon steel and ZL114A aluminum bimetallic castings during compound casting process. The aluminizing method slightly improved the bonding of the bimetallic casting compared with untreated method, and a gap at the interface was observed, leading to a poor bonding. In the case of the coating surface modifier method, the integrity of the interface was greatly increased because of the improvement of the incompatible between steel and aluminum, which indicated a mechanical bonding without a reaction layer, resulting in a limited improvement of the bonding. While the surface modifier + aluminizing method promoted a sound interface together with a metallurgical bonding, and a reaction layer with an irregular tongue-like morphology and an average thickness of approximately 30 μm was formed, which mainly consisted of Fe 2 Al 5 , FeAl 3 , Al 8 Fe 2 Si, and Al 2 Fe 3 Si 3 intermetallic compounds, resulting in a significant improvement of the bonding.