Role of compression direction on recrystallization behavior and texture evolution during hot deformation of extruded ZK60 magnesium alloy

摘要

Hot deformation behavior of as-extruded ZK60 magnesium alloy was investigated using uniaxial hot compression tests over the temperature range of 300-450 degrees C under strain rates of 0.001-1.0 s(-1) using a Gleeble((R)) 3500 available at the University of Waterloo. In order to take in account the effect of initial texture and microstructure on the hot deformation behavior of the alloy, compression tests were conducted in both the extrusion and radial directions (designated as ED and RD, respectively). The as received alloy exhibited an inhomogeneous microstructure featured by unrecrystallized elongated grains stretched along the extrusion direction, surrounded by equiaxed grains, with a typical fiber texture. Visual observation of the hot compressed samples showed that deformation along the radial direction led to pronounced anisotropic flow which reduced by increasing the deformation temperature or decreasing the strain rate. Processing maps determined from the compression tests predicted possible dynamic recrystallization (DRX) for both directions, specifically over the temperature regime of 400-450 degrees C which was confirmed by microstructural studies. It was observed that DRX grain size for both deformation directions is very close under identical deformation conditions; however, the final texture was strongly dependent on the deformation direction. While a weak and close to random texture was developed after deformation along the extrusion direction (ED), RD samples exhibited either similar texture to, the starting texture or a sharper texture. Such a behavior was attributed to the initial texture and DRX mechanism. (C) 2017 Published by Elsevier B.V.