METHOD FOR MANUFACTURING HIGH STRENGTH ULTRAFINE GRAINED ALUMINUM ALLOY PLATE BY CGP (CONSTRAINED GROOVE PRESSING)

摘要

PURPOSE: A method is provided to manufacture a high strength ultrafine grained metal plate without change of alloy constituents and size by performing CGP using asymmetric irregular die and flat die on an aluminum alloy plate to make fine structure into crystal grains having diameter of 1 micrometer or less of high inclination grain boundaries. CONSTITUTION: In a method for manufacturing a high strength aluminum alloy plate, the method for manufacturing a high strength ultrafine grained aluminum alloy plate comprises the steps of (a) pressing ("irregularity pressing") the aluminum alloy plate using asymmetric irregular dies comprising an upper die on which a plurality of irregularities are repeatedly and uniformly formed, and a lower die on which corresponding irregularities to be overlapped with the upper die are formed; (b) pressing ("flat pressing") the alloy plate from the step (a) without displacement using a flat die; and (c) repeating irregularity pressing of the step (a) and flat pressing of the step (b) by rotating the alloy plate to an angle of 180 degrees so that upper and lower surfaces of the alloy plate from the step (b) are reversed, wherein the pressing is performed at a temperature of an ordinary temperature to 200 deg.C, height of the irregularities is equal to the initial thickness of the plate, an inclined surface angle of the irregularities is about 45 degrees and symmetrical side to side, all of height of the irregularities, width of the upper part of the irregularities and lower surface width between adjacent irregularities are same, and they are the same as the initial thickness of the plate, the pressing is performed at a pressing speed of 20 mm/sec or less, and a series of processing processes of the steps (a) to (c) are performed 4 times or more.