Research on Cold-Rolled Bimetal of High-Tin Aluminum Alloy and Steel

Bimetal of high-tin aluminum alloy and steel was fabricated by cold-rolling process; microstructure, bonding strength and bonding mechanism for bonding interface of the bimetal were investigated under cold-rolling and recrystallization annealing state, respectively. Experimental results indicate that tin phase of bimetal in cold-rolling state shows a belt type distribution, however, it, in recrystallization annealing state, is uniformly distributed just like some “isolated islands”. A well bonding interface, between layers of high–tin aluminum alloy and pure aluminum, can be obtained, and it is difficult to distinguish one layer from the other; but the interface, between layers of low-carbon steel back and pure aluminum, is clear and uneven. And meanwhile, bonding mechanism of bimetal interface, in cold-rolling state, is cold pressure welding and mechanical occluding, But it, in recrystallization annealing state, is cold pressure welding, mechanical occluding, and metallurgic bonding. After recrystallization annealing, at 350°C for 2h,the bonding strength of bimetal approaches to 92.4MPa, which is about 26% higher than that of cold-rolling state.

Texture strengthening of copper electrical conductors

SummaryCommercial tough-pitch copper of high grade has been used to correlate the texture of wires to their tensile strength. Twentyfour samples were prepared by cold drawing of copper wires in one direction for four different reductions in area and subjecting them to different temperatures of preliminary and final annealings. The texture of these samples was calculated by the method of inverse pole figures. The final annealing temperature was found to be the factor affecting the texture of the wire irrespective of the pre-annealing temperature. It was found that Young's modulus depends mainly on the texture of the wire, while the other mechanical properties depend more on the grain size and the annealing state. The values of electrical resistivities of all wires are isotropic with respect to texture.