The Alstruc homogenization model for industrial aluminum alloys

Abstract

Wrought aluminum alloys are often given a homogenization heat treatment before extrusion or rolling. Foundry alloys are sometimes given a solution heat treatment before age hardening. The purpose is • to remove particles and segregation gradients that will give films or areas with low melting temperatures, in order to avoid tearing during extrusion and rolling; • to round off hard particles with sharp edges, which give poor ductility and holes in thin walled products; • to form secondary particles (dispersoids) for grain size control during extrusion and rolling; • to obtain a uniform distribution of alloying elements in solid solution before rolling, extrusion or age hardening. The Alstruc homogenization program gives semi-quantitative estimates of the changes in the microstructure during the later part of the heating stage and during the holding stage. The program has separate subroutines for AA3xxx (AlMnFe with Mg and Si), AA5xxx (AlMg with Fe, Si and Mn) and AA6xxx (AlMgSi with Fe, Mn and Cu) wrought alloys and for AlSi foundry alloys with Fe, Mg and Cu. The estimates of the changes in the microstructure during cooling are qualitative. This paper is compiled of three parts: Sections 1–5 present the program concept, Sections 6–8 present the results of the curve fitting and verification process for industrial alloys, and Section 9 presents interesting phase diagrams. Solidification Homogenization AA1xxx AA3xxx AA3xxx AA5xxx (AA5xxx) AA6xxx AA6xxx AA7xxx AlSi +++ AlSi +++