摘要
A new severe plastic deformation(SPD)technique for improvement of the metallurgical properties of the magnesium alloys is presented.In this process,a cyclic extrusion compression angular pressing(CECAP)process is followed by an extrusion step in the outlet playing the role of additional back pressure.Therefore,more uniform and enhanced mechanical properties are expected in comparison with equal channel angular pressing(ECAP).In order to evaluate the effectiveness and capabilities of this new method,an AM60 magnesium alloy was processed.Finite element results exhibited a significant increase in strain values as well as uniform strain distribution for the new method.In addition,~110%increase in compressive stress was observed in new method compared to the conventional ECAP.Experimental results revealed a noticeable increase in the hardness and strength of the specimens processed by the new technique as a result of the formation of finer grains and more homogeneous microstructure with good distribution of refinedβ-phase along the boundaries.It may be concluded that the new process is very promising for future magnesium alloy products.
利用新型大塑性变形(SPD)技术提高镁合金的冶金性能。在此过程中,先进行循环挤压−压缩−角挤压(CECAP)过程,再在出口处进行挤压,起到附加背压的作用。因此,与等径角挤压(ECAP)相比,期望获得更加均匀和优异的力学性能。为了评价这种新方法的有效性和能力,对AM60镁合金进行加工。有限元分析表明,新方法的应变值和均匀应变分布均显著提高。此外,与传统的ECAP相比,新方法的压应力增加约110%。实验结果表明,经新工艺处理后,试样的硬度和强度均有显著提高,这是由于其晶粒细化,显微组织更加均匀,并且细化的β相沿晶界均匀分布。因此,该新工艺在未来镁合金生产中具有广阔的应用前景。
