Al-mg-mn-sc - Zr Alloy Sheet Plane Mechanical Anisotropy Study

Al-Mg-Mn-Sc-Zr alloy is a structure material of high strength and plasticity, good welding property and corrosion resistance used widely in the area of aviation and spaceflight. With the development of aviation and spaceflight technology, the study of Al-Mg-Mn-Sc-Zr alloy sheet needs further improvement. The specimens' properties in different orientations is one of important aspects in application studies of such kind of alloy. In this work, the tensile mechanical properties, texture and microstructure of hot rolling and cold rolling specimens in different orientations were studied by means of tensile test, OM observation, XRD, SEM and TEM. The influence factors and principle of specimens' anisotropy were discussed from aspects of grain shape, crystallographic texture and precipitated phases. The results show that:1 The in-plane anisotropy (IPA%) of tensile mechanical properties were calculated, the result shows that strengths are higher at 30° and are lower at 45° . And Al-Mg-Mn-Sc-Zr alloy has significant anisotropy: the value of transverse direction plasticity ( α =90° )is larger than the longitudinal direction( a =0° ).2 Since Al₃(Sc, Zr) particals forming from Sc, Zr have strong effects of suppressing recrystallization, the alloy cold-rolled annealed sheets still retains the extended caky non-recrystallization structures along rolling direction. These visible directional non-recrystallization structures is one of important factors leading to anisotropy in alloy.3 The precipitated phase Al₃(Sc, Zr) cut by moving dislocation along the same plane may soften movable sliding surfaces, reduce slip system numbers, generate coarse slip and form dense slip band. The existing heterogeneity deformation(slip band) could weaken the longitudinal direction properties of alloy sheets then strengthen anisotropy and have an influence on inverse anisotropy .4 The analysis results of inverse pole figures indicate that the major texture of hot-rolling sheets is {110}<112> and minor texture is {311}<112>. The cold-rolling sheets have another weaker minor texture, which is {211}<111>. The texture (110)[li2| devoting to the anisotropy of alloy sheet were analyzed by means of approximate single crystal model with Schmid factor, and the major cause of o s anisotropy in Al-Mg-Mn-Sc-Zr alloy sheet is crystallographic texture.5 In this work, a new method, the bicrystal Schmid factor approximation dealing with the influence of Al-Mg-Sc alloy sheet material texture on material anisotropy was suggested. The results show that the new method is more valuable and perfect than the traditional single crystal Schmid factor approximation because it can explain and confirm the experiment result better.