Strain-Path Changes in Brass (Cu-20Zn)
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Metals are often exposed to multi-path loading in the forming process. Plastic deformed in more than one direction can have significant effects on microstructural evolution and mechanical behaviour. These mechanisms and behaviours are not completely understood at the present time, and needs to be investigated further and be incorporated into the current plasticity models.The intention of this work is to investigate the mechanical effects of strain-path changes, with different deformation modes and amounts of prestrain, for brass plates containing 80% Cu and 20% Zn. Two-step tensile tests with prestrain to 8% were performed for various angles of path change. Compression prestrain with subsequent tensile tension was performed with prestrains of 2% and 4%. Lastly, rolling prestrain to 4.6% and 9.7% with subsequent tension was performed at various angles of path change.The loading modes had a large influence on the observed effects of strain path changes in Cu-20Zn. Prestrain by rolling and compression showed distinct Bauschinger effects, however, unlike compression prestrain, rolling prestrain also reduced the strain hardening rate. The two-step tensile tests showed permanently increased yield strength upon reloading. Strain hardening plots of the subsequent loadings all had characteristics indicating substantial deformation twinning. This and other microstructural deformation mechanisms related to strain path changes are discussed with background in the state of the initial brass plates and other observations found in the literature.