Friction and wear properties of C67300 manganese brass under oil lubrication for application in piston pumps

The present work investigated primarily the friction and wear properties of annealed and cold-rolled C67300 manganese brass against the GCr15 steel (friction pair) under the conditions of different loads and speeds, as well as the oil lubrication. The microstructures, mechanical properties, and friction properties of annealed and cold-rolled C67300 manganese brass were characterized by a series of testing techniques. Experimental results show that the C67300 manganese brass is constituted of α-Cu solid solution matrix with a face-centered-cubic (FCC) structure, plus β'-CuZn with a B2 structure and ω-Mn5Si3 with a D88 structure. The microhardness (184 HV) and yield strength (410 MPa) of cold-rolled C67300 manganese brass are slightly higher than those of annealed alloy (137 HV and 345 MPa), which results in a ratio of microhardness to Young's modulus of the cold-rolled alloy (H/E=0.02) much higher than that of the annealed (H/E=0.014). The friction coefficients of both annealed and cold-rolled C67300 manganese brass decrease, with the increase of speed from 400 r/min to 700 r/min when fixing the applied load of 300 N, from f=0.06-0.07 to f=0.02. By contrast, the friction coefficients of both annealed and cold-rolled C67300 manganese brass increase with the applied load from 200 N to 500 N when fixing the speed of 400 r/min, as exampled by the fact that the friction coefficient of cold-rolled alloy increases f=0.03 to f=0.07. It is found that a relatively lower friction coefficient always appears in the cold-rolled alloy under any applied conditions, indicating that the cold-rolled C67300 manganese brass possesses a better wear resistance than the annealed. It is mainly ascribed to the fact that the H/E value (H/E=0.02) of cold-rolled C67300 manganese brass is much close to that of the friction pair of GCr15 steel (H/E=0.035), which is expected to improve the wear resistance of alloys by matching the H/E values of friction pairs well. © 2020, Science Press. All right reserved.