Effect of thermomechanical processing on microstructural evolution and deformation behaviour of polycrystalline magnesium under quasi-static and high strain rate conditions

摘要

The effect of thermomechanical processing on microstructure evolution and room temperature flow behaviour of polycrystalline magnesium in compression at strain rates of similar to 10(-2) and similar to 10(3) s(-1) was investigated. Different initial microstructures were produced by optimising rolling and annealing cycles. Prior to annealing for 1h at 350 degrees C, Mg samples were processed by two different treatments such as (i) hot rolling at 350 degrees C and (ii) hot rolling at 350 degrees C plus cold rolling at room temperature. Introduction of cold working step led to an increased fraction of hard oriented grains with a marginal grain size difference in post-annealed samples. A profound effect of thermomechanical processing on strain hardening rate as well as rate-sensitive flow behaviour of Mg was observed. The influence of prior processing history and strain rate on flow behaviour of Mg was clearly reflected in terms of texture strengthening/weakening phenomena and formation of microstructural deformation bands.