Study On Preparation And Strengthening Process Of High-strength Wear-resistant Brass

High-strength wear-resistant brass is widely used in the manufacture of plunger pumps,automobile synchronizer gear rings for its excellent high strength and wear resistance.However,high-strength wear-resistant brass’s comprehensive performance requirements,as one of the key materials,are higher and higher with the rapid development of China’s construction machinery and automobile industry.In this study,high-strength wear-resistant brass with different compositions is designed,and the effects of alloying elements Si,Al,and Ni on its as-cast microstructure,wear-resistant phase growth,mechanical properties,and wear mechanism are studied.The microstructure and property evolution of the alloy during extrusion and cold drawing are studied by means of deformation treatment of high strength wear-resistant brass.In addition,MS-13brass is preferred as the object of study.The growth and evolution of wear-resistant phase and its effect on mechanical properties and wear mechanism are studied by solution and aging treatment at different temperatures.The results show that:（1）With the increase of Si content in high-strength wear-resistant brass,the number of the wear-resistant phase and its size in the alloy gradually increased.When the Si content is 1.3wt%,the mechanical properties and wear resistance of the alloy are the best,and the wear mechanism is mainly abrasive wear.With the increase of Mn element content,the number of wear-resistant phases increased significantly and segregated at the grain and phase boundaries.Al element exists in the form of solid solution in high-strength wear-resistant brass,which can refine the grain and significantly improve the mechanical properties of brass;The Ni rich phase with silicon manganese element in the high-strength wear-resistant brass,which can significantly improve the wear-resistant properties of brass.（2）Among the five types of high-strength wear-resistant brass that continues to be alloyed,MS-321 brass has the best mechanical properties and wear resistance,with a tensile strength of 490 MPa,an elongation of 7.5%,and a hardness of 147 HB.Its microstructure is that the abrasion phase particles whit strips and blocks are distributed on theα+βphase matrix,and tend to segregate on the phase boundary.Under the friction and wear conditions of this study,the wear rate and friction coefficient were 2.069×10^-14m³/N·m and 0.23,respectively.（3）After extrusion and cold drawing,the grains are refined,and the grains are elongated in the extrusion direction;the size of the wear-resistant phase is significantly reduced,and it is uniformly distributed in the matrix in the form of short rods and fine particles,and almost all along the direction of extrusion and cold drawing.Comprehensive mechanical properties and wear resistance have been improved.（4）As the solution temperature increases,the proportion ofβphase in the MS-13 brass matrix increases,and the distribution of the Mn₅Si₃phase particles in the matrix is more uniform and finer;Compared to the as-cast MS-13 brass,the mechanical properties and wear resistance is improved.When the solution temperature is 710℃,the mechanical properties and wear resistance are the best.On this basis,after aging treatment at different temperatures,the friction coefficient and wear rate of the alloy increase with increasing temperature.Aging treatment at 350℃,the wear resistance is the best,the hardness is increased by 10%,and the tensile strength is basically maintained constant.