Influence Of Alloying On Microstructure And Properties Of H62 Brass

Brass is widely used in industry and life,such as radiators,submarine pipelines,water pipes,etc.,because it has good processing technology,corrosion resistance,mechanical properties,electric conduction and low prices and so on.But it has the dezincification corrosion phenomenon in the course of the use,resulting in mechanical properties of brass decrease and the service life greatly reduces,bringing the potential security risks.Therefore,the development of new components of high strength,corrosion-resistant brass has become the focus of the current research.In this paper,the mechanical properties and corrosion resistance of H62 brass are improved by adding Nd,Sm,B alloy elements and Nd and B elements by conventional casting method with H62 brass as the research object.In this paper,the effects of alloying,modification treatment and composit treatment on the microstructure and properties of H62 Brass have been studied by means of metallographic microscope XRD,SEM,EDS,tensile test,static corrosion experiments and electrochemical experiments.The main conclusions are as follows:The addition of rare earth Nd and Sm elements in the H62 brass increases the strength and hardness of the alloy.Adding 1.0wt.% Nd,compared with H62 brass,the tensile strength and hardness are increased by 17.2% and 62.5%,respectively.Adding 1.0wt.% Sm,the tensile strength,yield strength and Hardness are increased by 25.1%,50% and 78.1%,respectively,compared with H62 brass.After adding Nd and Sm in the H62 brass,the microstructure of the alloy is almost the same,which is composed of long strip or block ?-Cu0.64Zn0.36 phase and short rod-shaped ?'-CuZn phase.When the addition amount of Nd and Sm are 1.0wt.%,the average grain size of ?'-CuZn phase are 30?m and 20?m respectively,and the alloying structure are refined,but the effect of Sm on H62 brass is stronger than that of Nd.Nd and Sm elements are added to H62 brass,which changes the distribution and size of ?' phase.In brass,the strength and hardness of ?' phase are high,so the tensile strength and hardness of H62 brass are improved.After adding Nd or Sm elements,the corrosion potential of H62 brass is improved,the static corrosion rate and corrosion current density decrease,and the corrosion resistance is improved.Compared with H62 brass,the corrosion potential increases by 43.9% and the static corrosion rate and corrosion current density decrease by 31.3% and 1.8%,respectively when Nd addition was 1.0wt.%.When the amount of Sm is 1.0wt.%,The corrosion potential increases by 6.8%,and the static corrosion rate and corrosion current density decrease by 19.6% and 1.5%,respectively.The addition of B element in the H62 brass,the ?-Cu0.64Zn0.36 phase changes from elongated to equiaxed,?'-Cu Zn phase is lower than that of H62 brass and distributes at the grain boundary.When the addition amount of B element is 0.1wt.%,a small amount of equiaxed grains appears in the microstructure with an average grain size of 30?m.At this time,the plasticity of the alloy increases,the tensile strength and hardness decrease,compared with H62 brass,plasticity increases by 17.6%,tensile strength and hardness decrease by 10.1% and 12.5%.The atomic radius of B is far less than the atomic radius of Zn,when the brass occurs dezincification corrosion,B can fill the Zn vacancy,which can inhibit the corrosion of brass.When the B content is 0.05 wt.%,the corrosion potential of H62 brass is improved,the static corrosion rate and corrosion current density decrease,compared with H62 brass,the corrosion potential increases by 30.1%,the static corrosion rate and corrosion current density decrease by 27.6% and 4.5% respectively.When Nd and B are added to H62 brass,the plasticity of the alloy is improved,and the tensile strength and hardness decrease.Adding Nd and B to the brass,the ?'-Cu Zn phase is less than that of the H62 brass,the ?-Cu0.64Zn0.36 phase changes from long strip to dendritic.In brass,? phase is a face-centered cubic structure,and has a higher plasticity,so that the plasticity of the alloy increased.When the concentration of 0.05% B+0.2% Nd(wt.%),the tensile strength of the alloy is 320 MPa,the hardness is 56 HBW,the elongation is 42%,compared with H62,the tensile strength and hardness decrease by 5.3% and 12.5%,elongation increases by 23.5%.At this time,the corrosion potential of the alloy is improved,the corrosion rate and corrosion current density decrease,compared with H62 brass,the corrosion potential is increased by 35.0%,and the static corrosion rate and corrosion current density decrease by 32% And 3.1%.