The effect of ferrochrome content in the initial charge on the structure, mechanical and tribotechnical properties of Fe–Cr–C sintered carbide steel

Peculiarities of the structure, phase composition, basic physicomechanical and tribological properties of sintered high chromium Fe–Cr–C alloys, produced from powder mixtures of iron–high-carbon ferrochrome with different ferrochrome content (25 and 40%) in the initial charge are presented. The increase in the ferrochrome content in the charge led to increase in the shrinkage of the samples during sintering and, accordingly, a decrease in the porosity of the sintered composite from 7.4 to 2.2% as well as an increase in the ben­ding ultimate strength from 1100 to 1665 MPa and hardness from 66 to 76 HRA, respectively. According to the results of X-ray phase analysis using the Rietveld method, three phases was found in the phase composi­tion of both sintered composites: a-Fe, austenitic γ-Fe phase and car­bide phase (Cr, Fe)7C3. It is shown that increase in the content of high-carbon ferrochrome in the charge from 25 to 40% leads to a noticeable decrease in the size of the matrix phase grains of the composite. The results of tribological tests of the produced materials, show that during dry friction on ShKh15 steel, the friction coefficient is within 0.4–0.5 and differs slightly for materials of different composition. At the same time, the composite produced from the charge with an increased (40%) content of ferro­chrome provides significantly higher wear resistance (from 2.2 to 2.9 times) compared to the alloy obtained from the charge with 25% FKh800 for all contact pressures.