Effects of Chromium Addition Forms on Microstructure and Properties of Powder Metallurgy Sintering Fe-2Cu-3Cr-0.8C Alloy

Chromium element was added into raw material powder in the forms of pure Cr powder, commercial low carbon Cr-Fe powder and self-made mechanically alloyed Cr-Fe powder, respectively. The powders were pressed at 700 MPa and sintered at 1 200℃ for 1.5 h, and then Fe-2Cu-3Cr-0.8C alloy was obtained. The effects of chromium addition forms on the microstructure and properties of the alloy were studied. The results show that the microstructures of sintered samples were composed of pearlite and a small amount of ferrite and carbides with different adding forms of chromium. When added with the mechanically alloyed Cr-Fe powder, the sintered sample showed a homogeneous microstructure, and had relatively more pearlite; the sample had a relatively high compact degree with the sintering density of 7.07 g·cm^-3; the sintered sample had excellent comprehensive mechanical properties with the hardness of 95 HRB and tensile strength of 488 MPa; the morphology of tensile fracture was mainly dimple, and the fracture form was a ductile-brittle mixed fracture with ductile fracture as the main fracture; the sample had the least corrosion mass loss, indicating that the sample had the best corrosion resistance.