Effect of grain size on high strain rate deformation of rolled Mg-4Y-3RE alloy in compression

Artikel i vetenskaplig tidskrift, 2015

Magnesium alloys are widely used in automotive and aerospace industries, where they can be exposed to high strain rate conditions such as car crash and ballistic impact. Grain size is an important factor that can affect the mechanical behavior of magnesium alloys at high strain rates. Therefore, it is very important to evaluate the effects of grain size on the dynamic mechanical response of magnesium alloys under shock-loading conditions. In this research, texture evolution, microstructural changes and dynamic mechanical behavior of rolled Mg-4Y-3RE alloy samples, with grain sizes of 8, 25 and 46 mu m, deformed under compressive shock-loading are investigated. Dynamic shock loading tests were conducted using Split Hopkinson Pressure Bar at room temperature at a strain rate of 1200 s(-1). Texture measurements indicate development of a double-peak (00.2) basal texture in all the samples during shock loading. However, slightly higher intensities were observed for coarse-grained samples. Both strength and ductility were found to decrease with increasing grain size, while twining fraction and strain hardening rate increase with increasing grain size. The activity of double and contraction twins increased with increase in grain size. Furthermore, activation of pyramidal (c + a) slip system during the shock loading of the Mg-4Y-3RE alloy was confirmed using the 'g.b' analysis method.