In Strong Weldable Aluminum-magnesium Scandium Alloy Sheet Preparation And Welding Performance Study

This study is a part of the key project of the national "tenth five" programme (item number: MKPT-2004-16ZD).This paper took Al-Mg-Mn-Sc-Zr alloys as object of reserch, and studied the influence of cast ingot homogenization heat treatment and machining heat treatment on microstructure, mechanical properties and welding performance of Al-Mg-Sc aluminum alloy plane under the manufacture conditions, by testing the hardness, mechanical properties, optical microscopy (OM), and transmission electron microscopy (TEM). The results show that:1) The Al-Mg-Mn-Sc-Zr as-cast alloy hardened during the process of uniform annealing. The change of alloy hardness was because of the decomposition of supersaturated solid solution including manganese, scandium and zirconium during the flash set. And the precipitated A16Mn , A13 (Sc, Zr) particles led to the increment of hardness.2) Al-Mg-Mn-Sc-Zr alloy reached the peak hardess after annealing for 6 hours at 300°C. So the best homogenization annealing temperature for this alloy is 300～350°C, and annealing for 6～8 hours.3) The proper start temperature of hot rolling for the Al-Mg-Mn-Sc-Zr alloy was 470°C, finishing temperature was 360°C, the amount of deformity should more then 67%, and the stabilization annealing treatment was 300～350°C/1h. At this condition, tensile strength, yield strength, and specific elongation of the alloy was 411MPa,293MPa and 14%, respectively.4) The strength of Al-Mg-Mn-Sc-Zr alloy came from solution strengthening of Mg, grain refinement strengthening led by addition of Sc and Zr, substructure strengthening, and the precipitation strengthening of A13(Sc, Zr),A16Mn.5) Using Al-Mg-Sc-Zr soldering wire as Welding fillings, the tensile strength and specific elongation of weld joint was 380MPa and >7%, respectively, and the tensile strength of weld joint reached 90% of the matrix.