Study On The Preparation And Strengthening Process Of CuZnSiMnAl/Ni High Strength Wear Resistant Brass

High strength and wear resistant brass can adapt to harsh working conditions,and is often used in the manufacture of piston pumps,automotive synchronizer gear rings and other parts.With the rapid development of China's automobile industry and construction machinery,the strength and wear resistance of high strength and wear resistant brass materials are required to be higher and higher.In order to improve the strength and wear resistance of high strength and wear resistance brass alloy,the effects of different Al/Ni content,hot extrusion and cold stretching,solution and aging treatment on the microstructure and properties of high strength and wear resistance brass alloy were studied in this paper.The research results mainly include the following aspects:(1)When the theoretical zinc equivalent is constant,with the increase of Al content,the solution strengthening effect becomes stronger,and the?phase and strengthening phase in the alloy are refined.The strengthening phase of Mn₅Si₃ is hollow hexagonal primary Mn₅Si₃ and lamellar eutectic Mn₅Si₃,respectively.The mechanical properties of the alloy such as strength and hardness are improved,while the friction coefficient and wear rate are decreased.The hardness,tensile strength,yield strength and elongation of the alloy are 194 HB,655 MPa,435MPa and 4.3%,respectively.The friction coefficient and wear rate are 0.236 and 1.541×10^-13m³/(N·m),respectively.Compared with the as-cast state,the hardness of the 3.6 wt.%Al alloy decreases by 7%,the tensile strength,yield strength and elongation increase by 13.7%,11.5%and 291%,respectively,and the friction coefficient and wear rate decrease by 13.6%and 9.9%,respectively.(2)In as-cast state,with the increase of Ni content,the strengthening phases in the microstructure of CuZnSiMn alloy gather,and the mechanical properties and wear resistance of the alloy decrease.After hot extrusion treatment at 550?and 72.25 extrusion ratio,the strengthening phase distribution in the alloy microstructure is uniform and the aggregation phenomenon disappears.With the increase of Ni content,the mechanical properties and wear resistance of the alloy are improved.When the Ni content is 2.0 wt.%,the best properties are reached.The hardness,tensile strength,yield strength and elongation increased by 8.2%,30.8%,2.5%and 292%,respectively,while the friction coefficient and wear rate decreased by 1.1%and 27.3%,respectively.When the Ni content is 2.0 wt.%,the mechanical properties and wear resistance of the hot extruder alloy are improved.Compared with the extruder alloy,when the Ni content is 2.0 wt.%,the microstructure of the hot extruder alloy is finer.Hardness,tensile strength and yield strength were increased by 38.7%,20.6%and 182.8%,respectively.Elongation,friction coefficient and wear rate were decreased by 70.9%,1.9%and 10.7%,respectively.Therefore,the best alloy for high strength and wear resistance of CNZn Si MnNi series brass is the hot extrusion+cold tensile alloy(MS6t)of 2.0wt.(3)The MS6t alloy with the best properties was selected for solution treatment.With the increase of solution temperature,the strengthening phases in the alloy microstructure increased,and the?phase first refined and then became thicker.When the solution temperature was 710?,the?phase microstructure was the smallest and the strengthening phase precipitated the most,and the mechanical properties and wear resistance of the alloy reached the best.Compared with MS6t alloy without solution treatment,the hardness,tensile strength and elongation of the alloy after solution treatment at 710?are increased by 3.3%,9.8%and 97.5%,respectively,while the yield strength,friction coefficient and wear rate are decreased by 31.7%,1.5%and 15.2%,respectively.MS710s alloy treated by solution treatment at 710?was selected for aging treatment at different temperatures.As the aging temperature increased,the volume fraction of?phase increased,and the volume fraction of?phase in the alloy microstructure was the smallest at the minimum aging temperature of 350?.Compared with MS710s alloy without aging treatment,The hardness,tensile strength and yield strength were increased by 4.1%,1.5%and 12.4%respectively,and the mechanical properties reached the optimum.Compared with MS710s alloy without aging treatment,the wear resistance of MS710s alloy is the best when aging temperature is 400?,friction coefficient and wear rate decrease by 5%and 4.8% respectively.