Effect of extrusion ratio on mechanical properties of AZ31B alloy
(College of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040, China)
Abstract: By optical microscope and scanning electron microscopy(SEM), the mechanical properties were mea- sured, the effect of extrusion ratio on the mechanical properties of AZ31B alloy was studied. The result shows that, with the increase of extrusion ratio, the microstructure becomes more fine and homogeneous. At low extrusion ra- tio, the crystalline grain is refined with increasing the extrusion, the tensile strength of the alloy is improved. At high extrusion ratio, the strength doesn’t increase and has the tendency to reduce instead again. When the extrusion ratio is 19.7, the strength is 265MPa, and when the extrusion ratio is 400, the strength is 295.5MPa, which improves about 10%. The specific elongation and contraction of area fall down with the increase of extrusion ratio. By SEM, many cleavage steps, cleavage tongues, dimples and tear ridges were detected in the fractures, which shows obvious mixed-fracture mechanisms.
Key words: AZ31B Mg alloy； extrusion ratio； mechanical property