welded structures with improved mechanical properties almg alloys

摘要

An Al-Mg alloy sheet used for the production of welded structures of thickness above 2 mm and manufactured by semi-continuous casting has breaking strength Rm greater than 275 MPa, elongation A above 17.5, and product A x Rm above 6500. Preferred Features: The Al-Mg alloy comprises (in weight %): Mg 4.2-4.8; Mn less than 0.5; Zn less than 0.4, preferably 0.07-0.2; Fe 0.20-0.45; Si less than 0.3; optionally, Cr less than 0.15, Cu less than 0.25, Ti less than 0.2, and other elements less than 0.05 each and less than 0.15 in total; and Al the remainder. Mn+Zn is less than 0.7, preferably less than 0.2; and %Fe is greater than 0.5%Mn. The volumetric fractions of eutectic precipitates and dispersoids are above 0.7% and less than 1.5 times the fraction of eutectics, respectively. The sheet is fabricated without final annealing and the fabrication process includes hot rolling at a rolling exit temperature of 300-370 degrees C, preferably 320-360 degrees C. The width of the sheet is above 2200 mm. Independent claims are given for use of the Al-Mg alloy sheet for the fabrication of road and rail tanks, for road, rail and/or marine transport containers, for welded and/or forged car and lorry wheels, and for welded structures obtained by MIG or TIG welding with a bevel of around 45 degrees over about two-thirds of the thickness.