Effect of Annealing Temperature on Microstructure and Properties of Thixo-Extruded Tin Bronze Bush

Abstract:

The thixo-extruded tin bronze bushing parts have been used for annealing treatment, and the effect of annealing temperature on the microstructure, element distribution, wear properties and mechanical properties of the thixo-extruded tin bronze bushing parts is studied. The result shows that after annealing treatment, Sn and P elements can diffuse from the liquid phase to the Cu matrix solid phase forming α-Cu solid solution. As the annealing temperature increases, the average grain size gradually increases, and the shape factor first decreases and then increases, Brinell hardness first increases and then decreases, wear rate and friction coefficient first increase and then decrease, tensile strength and elongation first increase and then decrease. The microstructure and comprehensive properties of the tin bronze bushing are the best, when annealing at 500 ℃ for 120 min. The shape factor is 1.26, the average grain size is 75.2 μm, the tensile strength is 423 MPa, and the elongation is 6.6%. The Brinell hardness is 141 HBW, the wear rate is 6%, and the friction coefficient is 0.48.

Key words:Copper alloy; Annealing treatment; Thixotropic extrusion; Microstructure; Mechanical properties