Anisotropy of mechanical properties and hardness homogeneity in the three orthogonal directions of a multi-directionally forged ZK60 Mg alloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2023-09, Vol.884, p.145552, Article 145552
• Main Authors: Jamali, A., Mahmudi, R.
• Format: Article
• Language: English
• Subjects: Anisotropy; Hardness homogeneity; Mg alloy; Multi-directional forging; Texture
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2023.145552

An extruded ZK60 Mg alloy was processed by multi-directional forging (MDF) for up to 9 passes at a temperature of 473 K. The microstructure, hardness homogeneity, texture, and mechanical properties of the alloy were examined on the transverse and longitudinal sections of the extruded and MDF-processed samples. Microstructural observations revealed that a fine-grained and homogeneous microstructure was achieved after 9 passes of MDF in all three mutually perpendicular planes (A, B, and C) of the processed billet. Mechanical properties were determined using the shear punch testing (SPT) method, and hardness homogeneity was studied by Vickers microhardness measurements. The ultimate shear strength (USS) decreased from 186.8 MPa in the as-extruded condition to 154.7 MPa after 3 MDF passes, due to the overcoming of texture softening to the strengthening by grain refinement. The ZK60 alloy showed anisotropic behavior in terms of USS and hardness, measured on the three A, B, and C planes after 3 and 6 MDF passes. The observed differences in the measured properties, however, almost vanished after 9 MDF passes because of homogeneity in the microstructure and texture. Vickers microhardness measurements revealed that the material has excellent uniformity in hardness throughout the billet after 9 MDF passes in all planes, due to a fully recrystallized homogeneous microstructure.