Anisotropic, Strain Rate, and Stress State Effects of AZ31B

Tucker, M.T., Horstemeyer, M., Gullett, P., & Whittington, W. R. (2008). Anisotropic, Strain Rate, and Stress State Effects of AZ31B. Modeling & Simulation, Testing & Validation Conference. Warren, MI.

The anisotropic effects on the microstructure and mechanical response of rolled magnesium alloy Mg-3Al-1Zn (AZ31B) in the H24 condition have been quantified. Strong strain rate dependences on the compressive yield, hardening rate, and strain-to-failure were observed in the normal direction while the rolling and transverse directions exhibited no strain rate dependence on the yield strength, but did show a marked increase in hardening at a characteristic strain level. The microstructural characteristics associated with the different mechanical properties were also determined. These included the grain size distributions, particles size and geometrical distributions, and twin size distributions. It was determined that both the energy absorption and strain-to-failure were significantly increased when tested in the normal direction, most likely due to thermal softening during the adiabatic conditions of the test, but were relatively insensitive to strain rate in the rolling and transverse directions. Therefore, the texture of the material played a significant role in the plastic deformation at both quasi-static and high strain rates due to twin-slip interactions. Infrared camera images taken during adiabatic tests are also being analyzed to determine the amount of plastic work being converted to heat and to determine the effect of the temperature rise on the mechanical response of the material.