Texture optimization based on crystal plasticity modeling to improve strength and control anisotropy in heat treated additive manufactured Al-Mn-Sc alloy

Abstract

Heat treatment is a common method used to control mechanical properties, but its effects on strength and anisotropy remain uncertain. Therefore, studying the microstructural evolution resulting from heat treatment and its impact on strength is essential for optimizing heat treatment processes to reduce anisotropy. While the HallPetch relation has demonstrated the influence of grain size on yield strength, the effect of grain orientation on strength is still unclear and does not adequately predict the anisotropy of strength. In this work, the relationship between grain orientation and strength anisotropy is elucidated through crystal plasticity modeling on the basis of experimental results. Two-dimensional geometry models were constructed from the electron back-scattered diffraction results of additive manufactured (AMed) and heat-treated samples. Crystal plasticity modeling was applied along various directions to assess the influence of texture on the anisotropy of strength. The modeling results indicated that the presence of grains with <100> and <102> orientations in the AMed Al-Mn-Sc alloy and of grains with <112> orientations in the heat-treated state are detrimental to the yield strength. To increase the yield strength and maintain the anisotropy of the yield strength within a 5 % range, the <100> texture was optimized to 43 % <110> and 57 % <113> textures. Consequently, the yield strength increased by 11 MPa along the building direction and 21 MPa along the transverse direction. This optimization approach effectively enhances the strength and reduces the anisotropy in AMed alloys under various conditions.