The Study Of Warm Extrusion Forming On Microstructure And Mechanical Properties Of AZ31B Magnesium Alloy

The paper took AZ31B Magnesium Alloy as the research object,Through designing extrusion dies which is simple and applied,did extrusion experiment with two kind of AZ31B Magnesium Alloy bar which were cast and uniform annealed condition under the 6300KN hydraulic machine,and tested the sample on the microstructures and mechanical properties.The results of the study were as following:extrusion in the extrusion process,the intensity incrementΔσ_b of materials which were directly extruded is bigger than that of materials which were disposed evenly,When the extrusion ratio is 20,the maximum intensity increment of the former is 33.2MPa,the latter is only 9.5MPa.When extrusion temperature of the alloy increased from 250℃to 450℃,the grain grew up after extrusion,and the volume fraction of second phase decrease, the recrystallized grains got full deformation and more evenly distributed.At the same time,tensile strength reduced when the temperature was build-up, elongation percentage of materials which were directly extruded was enlarged obviously;And that of of materials which were disposed evenly was reduced obviously.By a variety of heat treatment and extrusion,the dynamic recrystallization happened to the products microstructure.The grains distinctly get smaller than that of before extrusion.Direct extrusion without heat treatment,when the grain of structure was lesser then extrusion with heat treatment,but the second phases were more,and structures were asymmetry.It's seen that the second phases were squeezed along the extrusion direction,formed thermal processing streamline. The grains after heat treatment and extrusion were bigger,but the structures were uniformity.The extrusion force of Magnesium Alloy which was disposed evenly is smaller than that of Magnesium Alloy which was directly extruded.