Investigation On The Microstructures And Mechanical Properties Of Mg-xAl-1Mn(x=1,3,6,9) Alloy Sheets

As the lightest metal structural material in industry now,magnesium alloys have been widely used in various fields,such as aerospace,transportation,electronics and so on.The application of cast magnesium alloys is more extensive,and the application of magnesium alloys is less.Because of the special HCP crystal structure,wrought magnesium alloys are poor in plasticity and have serious anisotropy,which leads to poor forming ability.It is not favorable to the subsequent processing and application of the sheets,thus hindering the development of wrought magnesium alloy and restricting the large-scale industrial application of magnesium alloy.Although a certain amount of rare earth element?RE?can be added to obtain high-performance magnesium alloy sheet,it is notapplied in large-scale industrial because of high cost.Therefore,the development of magnesium alloys with low cost and excellent mechanical properties at room temperature has become a hot topic in the research of magnesium alloys.In order to develop low-cost and high-performance magnesium alloy sheets.The microstructure and properties of Mg-xAl-1Mn?x=1,3,6,9?alloy sheets prepared by extrusion and hot rolling?SSR,LSR?is systematically studied,Which based on metallographic microscope?OM?,electron backscatter diffraction?EBSD?,scanning electron microscopy?SEM?,X ray diffraction?XRD?,tensile test and Erichsen test.The main results are as follows:?1?With the increase of Al content,the YS and UTS of the as-extruded sheet increased,and FE increased first and then decreased.When Al content was 6 wt.%,FE reached the maximum value,FE in ED,DD and TD directions was 23.2%,24.8%and20.1%respectively.The AM91 alloy exhibited excellent comprehensive mechanical properties.The YS in ED,DD and TD was 199 MPa,207 MPa and 220 MPa respectively.UTS was 308 MPa,307 MPa and 319 MPa respectively,FE was 20.9%,20.1%and 19.2%respectively,and the anisotropy is 7.7%.Moreover,the number of second phase increased with the increase of the Al content.Mg₁₇Al₁₂ phase only appeared in AM91.?2?With the increase of Al content,the YS and UTS of the as-SSRed sheet increased,and average FE increased first and then decreases.After annealing,the YS and UTS of AM31 alloy were higher than those of AM61.The FE of AM31 alloy was the highest,FE of RD,DD and TD was 21.5%,20.3%and 20.9%respectively.In addition,with the increase of Al content,IPA first decreased and then increased,which corresponded to texture changes.The texture of AM61 alloy was the weakest and the IPA value was the smallest,which was 8.4%.?3?With the increase of Al content,the Erichsen value of as-SSRed sheet increased first and then decreased.When the Al content is 3 wt.%,the Erichsen value was the largest,which is 2.4.After annealing,the Erichsen value increased obviously,and the trend was the same as the as-rolled sheets.When the Al content was 3 wt.%,the Erichsen value reached the maximum,which was 5.3.?4?With the increase of Al content,the texture of as-extruded sheets,as-SSRed sheets and SSR-annealed sheets first decreased and then increased.When the Al content was 6 wt.%,the texture was the weakest.?5?After annealing,the FE of AM91 LSR sheet was higher than that of SSR annealed sheet.FE in RD,DD and TD directions was 19.5%,21.8%and 20.0%,respectively.Moreover,the texture and anisotropy of LSR sheet after annealing were weaker,IPA was 5%.