Research of rolling regimes and mechanical properties of cold-rolled, annealed and welded semi-finished products from experimental alloys of Al-Mg system, economically alloyed by scandium

Abstract

Our paper shows the research results of thermodeformation machining of flat ingots made of experimental aluminium alloys, containing magnesium, scandium, rare-earth and transition metals. Relevance of the work aimed at creating the new Al-Mg system alloys, alloyed by scandium, and technologies for obtaining deformed semi-finished products from them using metal forming operations are shown. Regimes of hot and cold sheet rolling for obtaining strips with thickness 1-3 mm from these alloys were calculated and experimentally tested. Experimental research included the following steps: preparation of flat slabs with dimensions 28-150-300 mm for rolling; hot rolling at the temperature of 450 °C with total draw ratio about 6; cold rolling with total draw ratio about 5; annealing of cold-deformed semi-finished products at the temperature of 350 °C within 3 hours; argon-arc welding of the obtained strips along and across the direction of deformation; intergranular corrosion test; evaluation of mechanical properties of the samples. As a result, the nature and degree of corrosion destruction were studied and mechanical properties of deformed, annealed and welded semi-finished products from experimental alloys were determined. It is established that they have a high level of strength and plastic properties of the metal along, across and at an angle 45o relative to the direction of rolling. So tensile strength reaches the value 500-520 MPa for deformed samples, yield strength of metal 435-470 MPa, relative elongation 4.8-6.7%, and for annealed samples the values of the relative elongation increase and can reach 14.0-14.5% at the sufficiently high yield strength 357-369 MPa. Tests for intergranular corrosion of samples after welding showed high corrosion resistance of welded joints. The strength of the welded seam is 0.75-0.85 of the strength of the base metal. The results of research can be recommended for the development of technology for the manufacture of parts from flat products, including welded joints.