Effect of truncated cone billet on single-step back extrusion forming process of magnesium alloy wheel

Abstract

Magnesium (Mg) alloy wheels formed by single-step back extrusion currently faced with the phenomenon of coarse grains at the spokes, insufficient recrystallization, and easy cracking at the upper rim, which seriously affects the service performance and yield of the wheel. Based on the actual production process conditions of Mg alloy wheels, this paper simplifies the numerical model of the wheel back extrusion and proposes a truncated cone billet for wheel back extrusion by analyzing the streamline in the current wheel forming process. Research indicates that during the forming process of the cylindrical billet, the upper edge material of the billet fills the rim, the lower edge material fills the lower rim, and the lower core material forms the wheel spokes. Compared with cylindrical billets, truncated cone billets can increase the effective strain, dynamic recrystallize volume fraction and refine grains at the spokes and the lower rim. Simultaneously, the truncated cone billets can improve the fluidity at the rim, making the rim filling easier and reducing the cracking tendency at the upper rim. The truncated cone billet is of great significance to the back extrusion forming of Mg alloy wheels.

Keywords

• Magnesium alloy wheel
• Single-step back extrusion
• Truncated cone billet
• Numerical simulation