Study On The Microstucture And The Mechanical And Electrical Properties Of Copper-tin Alloy Wires Prepared By Heated-mold Continuous Casting Process

The metallic rods have excellent plastic workability prepared by heated-mold continuous casting process. Cu-Sn alloy rods were prepared by heated-mold continuous casting process. The structures evolution of Cu-Sn alloy in Heated-mold continuous casting process were researched in the paper. The wires were finally made by succedent cold drawing, the mechanical and electrical properties of As-Cast, As-Annealed and hard-drawn Cu-Sn alloy wires were tested and analyzed. The rules that influence the macroscopical representation of properties are explored by analyzing microcosmic structures and static loading fracture of the alloy in different states.The experimental results shown as follows:1 Cu-Sn alloy prepared by Heated-mold continuous casting has parallel tactic column crystals or single crystal structures at axial orientation, its grain size is several millimeter at landscape orientation and there is distinct cellular structures distributed inside; To compare with the alloy prepared by common metal mold casting, the tensile strength is lower about 12 % and percentage elongation is higher about 30% at room temperature .2 Through cold drawing, the cellular structure of Cu-0.3Sn alloy have no remarkable change. Then the tensile strength was increased evidently while the electrical conductivity decreased little. when deformation rate add up to 74%, the tensile strength can reach to about 387 MPa from 165MPa as casting and the electrical conductivity declined from72.8%IACS to 71.3%IACS.3 As the recrystallization annealing technics are used in the cold deformation process, it is discovered that the cellular structures is disappeared after the annealing treatment. The grains of the recrystallization after the cold deformation process become the continuous fibrous structures. When the deformation rate add up to 54%, the tensile strength reach to about 421MPa,meanwhile, the electrical conductivity is about 73.2% IACS . Through the intenerate experiments (annealed 2h at 300℃), the strength descends not more than 6%. To compare with the technics that the wires are prepared by direct hard draw ,through the technics that Cu-Sn alloy wires are prepared by heated-mold continuous casting add cold deformation add recrystallization annealing add cold deformation ,the tensile strength and electrical conductivity were obviously improved. It shows that the tensile strength, the electrical conductivity and the antintenerate properties of the Cu-0.3Sn alloy that made by the above method can reach the TB/T2809-2005 standards requirements of Cu-Sn alloy contact wires.