The invention relates to the technical field of non-
ferrous metals, in particular to a high-strength weldable aluminum
alloy for vehicle bodies and a preparation method thereof. The
alloy comprises: 4.8-6.6wt.% of Zn, 1.0-2.0wt.% of Mg, 0.08-0.16wt.% of Zr, 0.03-0.06wt.% of Sc, 0.01-0.03wt.% of Ti, less than 0.15wt.% of Fe, less than 0.15wt.% of other unavoidable
impurity elements, each of which is not less than 0.05wt.%, and the balance Al. The preparation method consists of: subjecting a cast
ingot obtained by semicontinuous
casting to uniform annealing at 200-220DEG C for 2h, then conducting furnace heating to 470-480DEG C and performing
thermal insulation for 8h, then conducting hot
extrusion and online water-crossing
quenching, then performing heat preservation at 480-490DEG C for 1-3h, and conducting
solution treatment, performing water
quenching, then carrying out heat preservation at 130-160DEG C for 12-24h and conducting aging treatment. By adding elements Zr, SC and Ti, a lot of Al3Zr(Sc, Ti) dispersed phase is generated in the
alloy to play a role of inhibiting recrystallized grains from nucleating and growing and obstructing
dislocation migration, thereby obtaining excellent strength and
toughness. The high-strength weldable aluminum alloy can be suitable for production of high-strength light structural parts for vehicle bodies.