Microstructure And Mechanical Properties Of ZCuSn10Pl Copper Alloy Bushings By Rheological Extrusion Casting

The application fields of copper alloys are expanding widely.Many defects,such as short life of the mold,large energy consumption,oxidation and suction etc,exist in the traditional liquid formation with its higher melting point.However,the semi-solid processing of copper alloys can reduce mold temperatures and energy consumption evidently.Moreover,the lifespan of mold and product performance is improved.As a consequence,the research and development of the semi-solid processing of copper alloys possesses important scientific significance and use value.In this paper,a new rheological squeeze casting process is developed by combining pulping process with direct squeeze casting process of cold rolled-remelting strain induced melt activation method.The shaft sleeve experiments of rheological squeeze casting Cu alloys ZCuSnlOP1 are carried out by adopting the mold that including inner springs and dam ring,which have made many attempts in the connect among quantitative pouring,pulping process and squeeze casting process.The article focuses on the axle box parts of Cu alloys ZCuSnlOPl,and the influence rules of formation process parameters on the microstructure and mechanical properties of parts of semi-solid slurry of squeeze casting Cu alloys ZCuSn10P1 are researched.The main research content and results as follows:(1)In the process of the rheological squeeze casting of the shaft sleeve parts,the liquid fraction of the tissue of the shaft sleeve parts increases along the direction of the filling,and the liquid fraction both inside and outside is higher than that of the center in the vertical direction of the filling.The uniformity of the tissue of the shaft sleeve parts becomes firstly better and then becomes worse with the increase of forming pressures.The uniformity of the tissue of the shaft sleeve improve with the increase of extrusion rate.The tissue of the shaft sleeve parts of rheological squeeze casting Cu alloys ZCuSn10P1 is most uniform when forming pressure is 250MPa and extrusion rate is 15mm/s.(2)The average grain size and shape factor of the primary solid phase reduces firstly and then increases with the increase of forming pressures.The average grain size and shape factor of the primary solid phase reduces with the increase of extrusion rate.The average grain size and shape factor of the primary solid phase of the tissue of the shaft sleeve parts,83.3 ?m and 1.59 respectively,is smallest when forming pressure is 250MPa and extrusion rate is 15mm/s.(3)The mechanical properties are better when the tissue is more uniform and the grain size of the primary solid phase is smaller.The mechanical property of the shaft sleeve parts increases firstly and then reduces with the increase of forming pressures.The mechanical property of the shaft sleeve parts is improved gradually with the increase of extrusion rate.The shaft sleeve parts have the best mechanical performance when forming pressure is 250MPa and extrusion rate is 15mm/s.The its strength of extension is 371.1MPa and ductility is 8.4%.Compared with liquid squeeze castings,its strength of extension and ductility increases by 55.9%and 83.3%respectively.(4)There many differences between the tensile fracture morphology of rheological squeeze castings and liquid squeeze castings.The liquid squeeze castings are brittle fracture,and its strength and ductility is lower.The fracture morphologies of the shaft sleeve parts of various process rheological squeeze castings Cu alloys are analogous,which belong to mix-typed fracture.The intergranular brittle fracture is easily produced in the area of more liquid phase among solid particles.The transgranular brittle fracture and ductile fracture are caused at the same time in the area of less liquid phase among solid particles.