Research On Rheological Squeeze Casting Process Of CuSn10P1 Axle Sleeve Parts

CuSn10P1 alloy has the advantages of high strength,large modulus of elasticity,low friction coefficient,good wear and corrosion resistance,etc.In addition,the addition of phosphorus can deoxidize and purify the melt and produce a hard compound Cu₃P phase,which improves the hardness and wear resistance of the alloy.However,tin bronze is prone to defects such as shrinkage cavities and shrin kage during solidification,resulting in low compactness microstructure,and low overall performance of parts.The semi-solid processing technology can induce the nucleation of the primary phase in the alloy melt by the action of external field force,and form a slurry in which a certain proportion of solid phase particles are suspended in the liquid phase.In addition,obtain a casting,which has fine crystal grains,uniform structure,and small solidification shrinkage,to improve the overall performance of CuSn10P1 alloy.In this paper,the CuSn10P1 alloy axle sleeve is taken as the research object.Based on the melt-constrained flow nucleation pulping process,a one-cavity six-mode semi-solid rheological extrusion-casting test is carried out by using a bottom-injection extruder to study the casting process.Study on the influence of mold structure,rheological extrusion process parameters on the microstructure and properties of the bushing.In addition,the combination of rheological extrusion casting and micro-feeding strengthening process,the effect of micro-feeding strengthening treatment on semi-solid rheological extrusion forming the axle sleeve is investigated.The low forming pressure of the semi-solid rheological extrusion casting will result in low compactness of the axle sleeve microstructure,increased defects,and poor uniformity of the microstructure;when the extrusion rate is constant,as the forming pressure increases,the microstructure uniformity of axle sleeve and grain refinement are improved.When the forming pressure is constant,as the extrusion rate decreases,the microstructure distribution is uniform,the grain refinement degree is better,and the liquid phase agglomeration phenomenon disappears.When the forming pressure is 200 MP a and the extrusion rate is 17 mm/s,the outer axle sleeve of the mold has the best comprehensive performance,and the tensile strength,elongation and Brinell hardness are 466.29 MPa,13.40%and 154 HBW,respectively.Compared with the microstructure and properties of the axle sleeves at different forming positions,it is known that there are a large number of coarse grains in the microstructure of the axle sleeve in the middle position of the casting;while equiaxed or near-spherical crystals dominate the microstructure of the axle sleeve in the outer position.The particles are round and distributed.The mechanical properties of the axle sleeves at different positions are obviously different.The strength of the axle sleeve on the outer side of the castin g is higher than the middle position,and the hardness of the axle sleeve in the middle position of the casting is higher than the outer position.When the process parameters are forming pressure 200 MPa and extrusion rate 17 mm/s,the tensile strength,el ongation and Brinell hardness of the axle sleeve at the intermediate position of the casting are 385.05 MPa,11.5%,180HBW,respectively.Comparing the casting with the axle sleeve at the outer position,the tensile strength and elongation increased by 21.10%and 16.52%,respectively,while the Brinell hardness decreased by 14.44%.The microstructure and properties of liquid extrusion casting and semi-solid rheological extrusion casting show that there are coarse dendrites in the microstructure of liquid extrusion-cast CuSn10P1 alloy axle sleeve and the microstructure of the axle sleeves is evenly poor.The semi-solid rheological extrusion casting prepared by melt-constrained flow-induced nucleation process has fine and uniform microstructure,which is main ly equiaxed or nearly spherical.The tensile strength,elongation and Brinell hardness of the outer axle sleeve of liquid extrusion casting are 357.2 MPa,6.2%and 120 HBW,respectively;when the forming pressure is 200 MPa and the extrusion rate is 17 mm/s,semi-solid rheological extrusion forming the outer axle sleeve performance is 30.54%,116.12%and 28.33%higher than the liquid extrusion casting performance.The micro-feeding strengthening treatment can eliminate the microstructure defects near the inner wall of the axle sleeve,increase the density of the microstructure,and improve the uniformity of the microstructure of the axle sleeve.When the forming pressure is 200 MPa and the extrusion rate is 17 mm/s,the tensile strength and elongation of the outer axle sleeve applying the micro-feeding process are 453.21MPa and 13.1%,respectively,which is equivalent to the un-applied micro-feeding.However,the Brinell hardness of the outer axle sleeve was increased from 154 HBW when micro-feeding was not applied to 176 HBW when micro-feeding was applied,which was increased by 14.29%.