Development of the continuous process method for ECAP using a tri-axis rotary die and microstructural evolution of semi-solid aluminium alloy

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.

Improvement in toughness of semi-solid light metal by the ECAP process

“…Flemings [1] of MIT began research on casting in the semi-solid state for the reduction of solidification shrinkage, compositional segregation, and cavities in the early 1970s. It was observed in our papers [2,3] that semi-solid casting, i.e., the homogenization of heating distribution by means of a stirring operation and high cooling rate, provides a reduction in micropores, spheroidizing of the primary phase, and grain refinement. Several investigations have been conducted on semisolid casting using both aluminum cast and wrought alloys.…”