Triaxial Compression on Semi-solid Alloys

Fatin N Altuhafi,Catherine O’Sullivan,Christopher M Gourlay,Te-Cheng Su,Peter Sammonds

doi:10.1007/s11661-021-06213-9

Abstract

Multi-axial compression of the mushy zone occurs in various pressurized casting processes. Here, we present a drained triaxial compression apparatus for semi-solid alloys that allow liquid to be drawn into or expelled from the sample in response to isotropic or triaxial compression. The rig is used to measure the pressure-dependent flow stress and volumetric response during isothermal triaxial compression of globular semi-solid Al-15 wt pct Cu at 70 to 85 vol pct solid. Analysis of the stress paths and the stress–volume data show that the combination of the solid fraction and mean effective pressure determines whether the material undergoes shear-induced dilation or contraction. The results are compared with the critical state soil mechanics (CSSM) framework and the similarities and differences in behavior between equiaxed semi-solid alloys and soils are discussed.

Highlights

IntroductionPRESSURIZED metal casting processes (e.g., high-pressure die casting and squeeze casting) and processes that combine deformation processing with solidification processing (e.g., twin-roll casting and semi-solid forging) have the potential to be the most cost-effective and least environmentally damaging metal processing routes
PRESSURIZED metal casting processes and processes that combine deformation processing with solidification processing have the potential to be the most cost-effective and least environmentally damaging metal processing routes
The change in solid fraction and the void ratio of the sample was calculated based on both the change in temperature of the sample and the volumetric change recorded during the compression stage, as the temperature of the sample during this stage was not constant

Summary

Introduction

PRESSURIZED metal casting processes (e.g., high-pressure die casting and squeeze casting) and processes that combine deformation processing with solidification processing (e.g., twin-roll casting and semi-solid forging) have the potential to be the most cost-effective and least environmentally damaging metal processing routes. Each of these processes applies multi-axial compression to the mushy zone, and the rheological response determines how the semi-solid material deforms in the die and/or how defects such as deformation-induced macrosegregation occur. There is a complex coupling between the rearrangement and/or deformation of the solid and flow of the liquid within the low permeability mush.[10,11]

Methods

Results

Discussion

Conclusion