Patent ID: 8535505

Claim:
A method for making a metallic cover, comprising: forming a preformed cover by drawing an aluminum alloy sheet, the aluminum sheet having a yield strength in a range from about 80 MPa to about 150 MPa, an elongation ratio in a range from about 15% to about 28%, and a hardness in a range from about 45 HV0.2 to about 70 HV0.2, the preformed cover having a bottom base and a plurality of side walls, and each of the side walls and the bottom base being connected by a curved-cornered edge; pressing the curved-cornered edge of the preformed cover into a sharp-cornered edge by a forming die; polishing the preformed cover; and anodizing the polished preformed cover to form the metallic cover wherein the aluminum alloy sheet has an inner structure including two regular portions and a sensitive portion sandwiched between the two regular portions, a width-thickness ratio of the sensitive portion is preferably to be 0<W/t<0.33, wherein W represents a width of the sensitive portion, and t represents a thickness of the aluminum alloy sheet.