Process for producing duplex mode recrystallized high strength aluminum- lithium alloy products with high fracture toughness and method of making the same

摘要

A method of producing a recrystallized aluminum-lithium product having improved levels of strength and fracture toughness is disclosed. The method comprises the steps of: providing a lithium- containing aluminum base alloy comprised of 0.5 to 4.0 wt. % Li, 0 to 5.0 wt. % Cu, 0 to 5.0 wt. % Mg, 0.10 to 1.0 wt. % of a grain structure control element selected from the class consisting of Zr, Cr, Hf, Ti, V, Sc, and Mn, 0.5 wt. % max. Fe, and 5 wt. % max. Si, with the balance consisting essentially of aluminum and incidental elements and impurities; heating the body to a high presoak temperature to homogenize the alloy; cooling the alloy to a first hot working temperature; reheating the alloy, after hot working, back to a high annealing temperature; cooling the alloy to a second hot working temperature to produce a first product; reheating the alloy to a lower annealing temperature; and then cold working the alloy. The cold worked product is solution heat treated, quenched and aged to provide a substantially dual mode recrystallized sheet product having improved levels of strength and fracture toughness and further characterized by a fine grain structure adjacent the surface of the alloy product and a coarse grain structure in the interior thereof.