Effect of Multi Directional Forging on the Microstructure and Mechanical Properties of Zn-24 wt% Al-2 wt% Cu Alloy

Abstract

Multi directional forging is an important process for producing fine grains in bulk materials by means of severe plastic deformation. Zn-Al alloy is used for making sleeves of plain bearings, but the presence of porosity degrades its usage in industrial application. In the present investigation, multi directional forging of Zn-24Al-2Cu alloy was carried out at 100 and 200 °C up to total strain of 0.6 and 1.2 respectively. Mechanical properties and microstructural characterization were carried out on the processed material. It was inferred that processing at 100 °C up to three passes increased ultimate tensile strength from 185 to 267 MPa with ductility of 14 %. The average grain size was reduced from 30 to 2 µm. In the case of samples processed at 200 °C up to six passes, the average grain size was reduced to 1 µm. The ultimate tensile strength increased to 276 MPa and ductility significantly improved to 21 %. The strength of the processed material increased due to strain hardening and grain refinement. Uniform distribution of various dispersed phases contributed to the enhancement of ductility during multi directional forging at 200 °C. Analysis of the fractured surface of the tensile samples revealed highly ductile nature of the fracture.