Author(s)

K. Natori, F. Nomura, Y. Arao & T. Tanaka

Abstract

The continuous ECAP process which can provide three-dimensional strain was developed in this study. A die with tri-axis crossed channels having channel angle φ of 90° and curvature ψ of 0° was created. As a result, continuous ECAP process via route Bc for AC4CH aluminium semi-solid alloy could be performed at 573K at pressing speed of 0.5mm/sec using the developed die. The continuous method cut the processing time in half compared to the non-continuously conventional method. The grains became fine from 100μm to approximately 2μm. Workpiece processed 8 passes exhibited four times higher toughness than as-cast alloy. Keywords: equal-channel angular pressing, severe plastic deformation, ultrafine grained, semi-solid cast, continuous process, Tri-RD-ECAP, Al-Si-Mg alloy. 1 Introduction The process of grain refinement in metal materials is generally known as the way to improve their strength and ductility without losing toughness. In recent years, much attention has been paid to methods which can give the grain refinement by severe deformation. The methods can improve the microstructure of alloy more energy efficient compared to rapid solidification, stirring during solidification, and heat treatment. Equal-Channel Angular Pressing (ECAP) is especially different from other kinds of the method such as using rolling and drawing, and is not restricted in bulk shape. This implies there is no limit for the amount of

Keywords

equal-channel angular pressing, severe plastic deformation, ultrafine grained, semi-solid cast, continuous process, Tri-RD-ECAP, Al-Si-Mg alloy.