The effect of ferrochrome content in the initial charge on the structure, mechanical and tribotechnical properties of Fe–Cr–C sintered carbide steel
摘要
Peculiarities of 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, the decrease in the porosity of the sintered composite from 7.4 to 2.2% as well as the increase in the bending ultimate strength from 1100 to 1665 MPa and hardness from 66 to 76 HRA, respectively. Three phases in the phase composition of both sintered composites α‑Fe, γ‑Fe austenite, and carbide (Cr, Fe)7C3 were found according to the results of X‑ray phase analysis using the Rietveld method. The increase in the high-carbon ferrochrome content in the charge from 25 to 40% leads to a noticeable decrease in the matrix phase grains size of the composite. The results of tribological tests of the produced materials showed that during dry friction on ShKh15 steel, the friction coefficient was 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%) ferrochrome content provides significantly higher wear resistance (from 2.2 to 2.9 times) compared to the alloy obtained from the charge with 25% ferrochrome800 (FeCr800) under all contact pressures.