Quantitative analysis on friction stress of hot-extruded AZ31 magnesium alloy at room temperature

Mg alloy AZ31 with ∼79% (volume fraction of scattering less than 30°) basal-fiber texture through hot extrusion exhibits strong grain-size dependent yield strength. Samples with grain sizes varying from 4.5 to 22.3 μm were obtained by altering annealing time durations. The Hall-Petch relations of tension and compression are σ0.2 = 86+200d−1/2 and σ0.2 = 17 + 327d−1/2, respectively. Considering the correlation between grain orientation and deformation modes, a novel weighted average method of calculating friction stress σ0 was proposed, and results of calculation agreed with the experimental ones, which can reasonably understand the yielding behavior in tension and compression.