Effects of Backpressure Thixo-Backward Extrusion and Remelting Temperature on Microstructural Evolution and Mechanical Properties of Tin Bronze Bushings
摘要
The study investigates the effects of remelting temperature on the microstructure and mechanical properties of ZCuSn10P1 alloy bushings fabricated via the Back pressure Thixo-Backward Extrusion process. Semi-solid billets were prepared using a cold rolling-induced strain-induced melt activation route, which involved pre-annealing, multi-stage cold rolling with intermediate annealing, and subsequent semi-solid remelting. Under a constant remelting time of 29 min, the semi-solid slurry was treated at different remelting temperatures to obtain copper alloy semi-solid billets, followed by back pressure Thixo-backward extrusion to form the final bushing components. The microstructure, elemental distribution, phase composition, Brinell hardness, tensile strength and elongation were characterized in different regions of the bushings. The aim was to identify the most suitable remelting parameters to reduce solid–liquid segregation and elemental inhomogeneity, thereby improving microstructural uniformity and enhancing the mechanical performance of the bearing bushings. The results showed that, under all remelting conditions, the bushing consisted of a triphasic structure comprising α-Cu, Cu3P and Cu41Sn11. Remelting at 930 °C for 29 min resulted in the least solid–liquid segregation, minimal elemental inhomogeneity and the most favorable microstructural uniformity. The lowest average Brinell hardness measured was 115 HBW, while the highest tensile strength reached 397 MPa. Elongation was 9.8%, slightly lower than the 10.2% obtained at 920 °C for 29 min.