Influence of alloying element additions on tribological behaviour of sintered steels with high content in manganese-nickel

摘要

Manganese and nickel are alloying elements with a high hardenability. Manganese is an excellent substitute for nickel due to its low cost but presents a great affinity for oxygen. In this work, the friction and wear behaviour of sintered manganese-nickel steels, by a pin-on-disk test has been studied. The tests were made under dry conditions, 0.1 m/s and 10N as linear speed and applied load, respectively. Wear behaviour was evaluated against spherical pin of martensitic stainless steel (49 HRC). High manganese-nickel sintered steels were manufactured with two levels of carbon: 0.3 and 0.7 percent by weight. The unique level of addition of pure electrolytic manganese and different prealloyed manganese-nickel (80Mn/20Ni, 55Mn/45Ni and 25Mn/75Ni) was 4 percent by weight. All the compositions were prepared by dry mixing in ball mill and compacted at 700MPa using uniaxial pressing. The sintering was carried out at 1230 deg C in 90N_2/10H_2 as protective atmosphere. Density, porosity and hardness were evaluated. After sintering, all samples were polished at the same surface conditions and friction coefficients and wear rates have been measured. A complete microstructural study of the different steels and their transversal wear tracks was carried out. Deformations of ferritic areas, closed surface porosity and austenite-martensite transformation during wear test were detected. For materials with 0.7 percent C, the combined effect of carbon and manganese increases wear resistance.