Microstructure Evolution And Mechanical Properties Of Semi-solid Backward Extruded ZCuSn10P1 Copper Alloy Bushing

Metal semi-solid forming technology has the advantages of solidification forming and plastic forming,which can reduce defects such as shrinkage and shrinkage generated during the casting process,so it has been widely used.ZCu Sn10P1 tin bronze has the characteristics of good wear resistance,good corrosion resistance and excellent mechanical properties.It is widely used in the manufacture of equipment parts such as automobiles,high-speed rail and ships.Copper alloy bushings prepared by traditional casting methods are prone to problems such as inclusions,oxidation,and cracks,while semi-solid forming technology is expected to reduce copper alloy bushing parts defects and improve material utilization.In this paper,ZCu Sn10P1 copper alloy is used as the research object,the semi-solid slurry is prepared by SIMA method,and the sleeve is extruded by reverse extrusion,the influence of cold rolling deformation,isothermal temperature and holding time on the structure and mechanical properties of semi-solid shaft assembly was studied.In addition,the solution aging treatment of the semi-solid reverse extrusion sleeve was also carried out,focusing on the study of the effect of solution temperature on the structure and mechanical properties of the sleeve parts.The main research contents and conclusions of this article are as follows:(1)Designed and manufactured a set of reverse extrusion molds to form copper alloy bushing parts.According to the shape and size of the bushing parts,the back extrusion punch and the concave die were designed and proofread in detail,and the die manufacturing and trial die were carried out.The experiment proves that the structure of the bushing parts extruded by the reverse extrusion die and the reasonable forming process parameters is better,and there is basically no liquid phase segregation at the upper and bottom parts.(2)The effect of cold rolling deformation,isothermal temperature and holding time on the microstructure and mechanical properties of the back-extruded copper alloy bushing during the pulping process was studied.The result shows: with the increase of the deformation,the average grain size and shape factor of the solid phase particles of the bushing decrease first and then increase;the Brinell hardness increases first and then decreases,the tensile strength increases first and then decreases,and the elongation rate decreases first and then increase.With the increase of the temperature,the grain size gradually increases,and the shape factor decreases first and then increases;the Brinell hardness increases first and then decreases,the tensile strength increases first and then decreases,and the elongation rate has been increasing.With the increase of the holding time,the average grain size gradually increases,and the shape factor decreases first.The Brinell hardness and tensile strength both increase and then decrease,and the elongation rate gradually increases.When the deformation is 30%,the isothermal temperature is 900 ?,and the holding time is 20 minutes,the reverse extrusion sleeve parts have a more uniform structure and better mechanical properties,at this time,the grain sizes in the longitudinal direction(positions 1 to 4)were 60.60 ?m,60.28 ?m,59.51 ?m,and 61.10 ?m,the shape factors were 1.29,1.24,1.26,and 1.27,and the liquid phase ratios were 14.41%,14.37%,14.33%,14.30%,the longitudinal average Brinell hardness of the part is 137 HBW,the tensile strength is 407 MPa,and the elongation is 7.6%.(3)The effect of solid solution aging process on the structure and mechanical properties of the sleeve was studied.As the solution temperature gradually increases,the average grain size of the solid phase particles of the sleeve increases first and then decreases,and the shape factor decreases and then increases;brinell hardness increases first and then decreases;tensile strength first increases and then decreases,elongation gradually increases,and corrosion resistance increases first and then decreases.the best solution aging process is solution quenching at 700 ? for 1 hour and quenching at 350 ? for 1 hour.At this time,the grain size is 90.7 ?m,the shape factor is 1.35,the tensile strength is 422 MPa,and the elongation is 10.7%,brinell hardness is 152 HBW.(4)The solid solution aging treatment can effectively promote the diffusion and solid solution of Sn element in the semi-solid structure into the primary phase ?-Cu,the content of Sn element in the primary phase ?-Cu increases from 1.5% to 9.64%,the uniformity of the structure and composition of the sleeve is improved,the intercrystalline segregation is reduced,and the comprehensive performance of the material is improved.