| In this paper,a new type of Cu-Ni-Sn alloy with a new ratio(Cu : Ni: Sn=88:6:6)was prepared and studied,and an orthogonal experiment with an orthogonal table of L25(56)was designed to study the amount of cold deformation and aging The influence of time and aging temperature on the hardness,strength and plasticity(elongation after fracture)of Cu-Ni-Sn alloy,so as to obtain the optimal heat treatment plan.And using Brinell hardness test,room temperature tensile test,metallographic experiment(OM),tensile fracture scanning electron microscope(SEM)experiment and X-ray diffraction phase(XRD)analysis and other material physical research methods,so as to systematically study The relationship between the properties and structure of Cu-Ni-Sn alloy and the amount of cold deformation,aging time and aging temperature,determine the law and mechanism of cold deformation,aging time and aging temperature on Cu-Ni-Sn alloy,and get the following in conclusion:1.The metallographic structure of the solid solution Cu-Ni-Sn alloy is uniform,the crystal grains are mainly equiaxed grains,and the average grain size is 44.07?m.The black substance is basically integrated into the matrix;the solid solution Cu-Ni-The tensile port SEM of the Sn alloy showed a large number of dark dimples and some white tearing edges around it,which belonged to a typical ductile fracture;the XRD analysis of the solid solution Cu-Ni-Sn alloy showed that there were mainly three phases,?-Cu phase,Ni17Sn3 phase and Cu Ni2 Sn phase.2.The Cu-Ni-Sn alloy has a strong deformation strengthening effect.The mechanical properties of the solid solution Cu-Ni-Sn alloy after cold rolling are tested,and it can be concluded that as the cold rolling deformation increases,the solid solution Cu-Ni-Sn alloy hardness,yield strength and tensile strength increase accordingly,elongation after fracture decreases,hardness increase can reach 51.2?101.6HBW,tensile strength increase can reach52.36?200.194 Mpa,yield strength increase can reach 4.45?129.21Mpa;the metallographic structure of the solid solution Cu-Ni-Sn alloy after cold rolling is mainly equiaxed grains and there are a large number of deformed grains(twins and elongated grains).The grains become finer and uneven,and there are a large number of dislocations in the grain boundaries;the SEM of the tensile port of the solid solution Cu-Ni-Sn alloy after cold rolling shows that: with the increase of the cold rolling deformation Large,dimples gradually become smaller and shallower,until there are none.The tensile fracture changes from ductile fracture to intergranular brittle fracture,which is basically in line with its mechanical properties;the XRD analysis of the solid solution Cu-Ni-Sn alloy after cold rolling shows that the phase is basically the same as that of the solid solution Cu-Ni-Sn alloy.The same,but the external force of cold deformation caused changes in the tin-poor and tin-rich areas,resulting in a change in the phase content(that is,the height of the peak in the XRD).With the increase of cold rolling deformation,the peak gap between Cu Ni2 Sn phase and Ni17Sn3 phase increases.3.Orthogonal range analysis method can get: For the hardness evaluation index,the factors that affect the hardness change of Cu-Ni-Sn alloy are: pre-deformation>aging time>aging temperature.For the strength evaluation index,the factors that affect the tensile strength of the Cu-Ni-Sn alloy are: pre-deformation>aging time>aging temperature;the factors that affect the yield strength of the Cu-Ni-Sn alloy are: pre-deformation>aging temperature>aging time.For the evaluation index of elongation after fracture,the factors affecting the change of elongation of Cu-Ni-Sn alloy after fracture are: aging temperature>pre-deformation>aging time.The orthogonal range analysis results of Cu-Ni-Sn alloy hardness,strength and elongation after fracture show that the best heat treatment process parameters are aging temperature360?,aging time 5h,and pre-deformation amount 40%.The Cu-Ni-Sn alloy was processed according to the best pre-deformation and aging process obtained by the orthogonal range analysis method,and its mechanical properties were tested,and the following data were obtained: hardness 288.8HBW,tensile strength 872.8Mpa,The yield strength is 250.2Mpa and the elongation after fracture is 25.2%.It can be seen that the hardness and strength have been significantly improved.The Cu-Ni-Sn alloy has better deformation strengthening and aging precipitation strengthening double strengthening effects,The hardness of Cu-Ni-Sn alloy which are better than solid solution Cu-Ni-Sn increased by 211.2%,the tensile strength increased by103.7%,the yield strength increased by 13.2%,the elongation after fracture decreased little,and the elongation after fracture decreased by 44.5% compared with the solid solution Cu-NiSn alloy.The analysis of the metallographic structure of Cu-Ni-Sn alloy shows that as the aging temperature increases,the grains are mainly equiaxed grains,the deformed grains gradually recover,the amplitude modulation decomposition accelerates,and the ? phase gradually precipitates and coarsens.The mechanical properties of Cu-Ni-Sn alloy reach the apex at 360?,and then the discontinuous precipitation phase transformation accounts for the main precipitation,and the mechanical properties of Cu-Ni-Sn alloy decrease.At the same temperature,the increase in the amount of cold deformation and the extension of the aging time are beneficial to speed up the amplitude modulation decomposition and increase the peak of the mechanical properties,and inhibit the discontinuous precipitation phase transition and recrystallization.The grain size basically tends to be the same,and the metallographic structure becomes more uniform.The SEM analysis of the tensile port of the Cu-Ni-Sn alloy shows that as the aging temperature and cold rolling deformation increase,the dimples gradually become smaller and shallower until they disappear,and the tensile port becomes a three-dimensional rock sugar pile This is the gradual transformation from ductile fracture to intergranular brittle fracture,and the plasticity decreases,which is basically in line with the mechanical properties of this treatment.The XRD analysis of Cu-Ni-Sn alloy shows that with the difference of aging time,the phase basically does not change much(Cu Ni10Sn3 phase is added),but the peak value of the object image is different.This is due to the increase of aging temperature.As a result,the content of precipitates has increased.A huge change occurs at 360°C.This is because the amplitude modulation decomposition reaches the apex and the discontinuous precipitation phase transition occupies the main precipitation phase transition position. |
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