| To develop a high property and low cost powder metallurgy Fe-C-Cu-Cr-Mn materials,the effect of Cu, Cr, Mn content on the microstructure and properties of powder metallurgyFe-C-Cu-Cr-Mn materials was studied through orthogonal design, cold pressing, sintering andheat treatment. The powder was mixed for2.5h by using mechanical mixing, was pressed byhomotaxial hydraulic machine, was sintered by mesh belt sintering furnace under N2-H2atmosphere; the density was measured by the electronic balance; the microstructure andfractography were studied by the optical microscope, X-ray diffraction, scanning electronmicroscope; the mechanical properties were tested by the electron universal test machine andswing beam impact testing machine, the following results were obtained:(1) The Cu, Cr, Mn has little influence on the flow velocity and apparent density, butmakes the material’s size expand in a different way, and lowers the sintering density.(2) Cu reduces the pore rate but the pore size is bigger; Cr increases the pore rate and thepore morphology is irregular; Mn closes the opening pore, reduces the pore rate and tends tobe like sphere. The ferrite content decreases, ferrite grain is smaller and the pearlite contentincreases with the increase of Cu; the pearlite layer distance is smaller, distribute moreuniformed with the increase of Cr; the ferrite content is less, the pearlite content is more,distributes more uniformed and has a better refining effect with the increase of Mn.(3) The hardness, tensile strength, elongation, impact toughness have a differentimprovement with the increase of Cu content; the hardness and tensile strength increase whilethe elongation and impact toughness decrease with the increase of Cr content; the hardnessincreases as the Mn content increases.(4) Fe-0.8C-3Cu-1.2Cr-0.3Mn performs the best comprehensive properties, whoseapparent density is3.025g/cm3, flow velocity is34.97s, sintering density is7.03g/cm3,hardness is56.9HRA, tensile strength is612.5MPa, elongation is1.8%, impact toughness is7.9J/cm2and size expansion is6.48%.To have a further optimize experiment, the microstructure and properties of powdermetallurgy Fe-0.8C-2Cu-0.5Mn under different Cr content were studied, using the sametesting and analysis method like orthogonal design, the following results were obtained: (1) With the increase of Cr content, the flow velocity becomes worse and the apparentdensity is greater; the green density and sintering density decrease and the spring back has aupraising tendency. The pearlite is smaller and its layer is more refining, even appearsgranulous pearlite; the hardness increases while dropping at the1.0%Cr content; the tensilestrength increases while dropping at the2.0%Cr content and its tendency is sharp; the impacttoughness decreases.(2) Material fracture has ductile nest, cleavage river pattern characteristic, but there is noapparent necking, fracture gives priority to cleavage, fracture belongs to brittle fracture.The wear property of the Fe-0.8C-2Cu-0.5Mn-(0-2.5%)Cr was studied by using the SRVIV micro friction and wear machine and the wear morphology was analyzed by the scanningelectron microscope, the following results were obtained:(1) With the increase of Cr content, the friction coefficient increases at first thendecreases when loading at30N, the friction coefficient decreases at first then increases whenloading at60N, the friction coefficient varies from0.80-0.86when loading at90N. The wearvolume has a varying change with the change of Cr content and the loading force; the wearvolume increases with the increase of the loading force.(2) Wear surface appears a lot of oxide when the Cr content is0%and2.5%, the wearmechanism is mainly oxide wear; wear surface appears different degree furrows and slightlayer flaking, the wear mechanism is mainly adhesive wear under0.5%,1%,1.5%,2%Crcontent; the adhesive wear pit is bigger and more serious with the increase of the loadingforce. |
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