Experimental and Finite-Element Method Study of Zn-22Al Alloy Pipe Hot Extrusion Using a Porthole Die

Abstract

To reduce the pollution caused by lead alloys, environmentally friendly alloys are selected to fabricate metal tubes for delay detonators. Zn-22Al alloy was selected in this study as the tube metal because of its high environmental friendliness and low cost. The first step in metal tube production is to prepare a pipe. In this study, the Zn-22Al alloy was hot extruded using a porthole die. A finite-element method (FEM) was used to optimize the porthole-die extrusion of the Zn-22Al alloy pipes. The flow stress data for the alloy in the temperature range of 200-350 °C and strain rate range of 0.1-10 s−1 were measured. The FEM results showed that two stages existed for any random position of the interface during porthole die extrusion, viz., the bonded interface-forming period, and the post-bonded period. The dead-metal zones existed at the corners between the container and die face and between the bottom and sidewall of the welding chamber. The effects of the extrusion temperature and the chamber height of the die on the welding quality index were studied. Pipes with an outer diameter of 18 mm and an inner diameter of 10 mm were fabricated successfully by the hot-extrusion method at 200 °C using a porthole die with a chamber height of 15 mm.