Study of surface roughness and hardness of low carbon nickel-chromium based alloy steels under high temperature (AISI sae8630, 3140 & 9310)
High temperature Tribology is an interesting and challenging area which deserves more attention on wear resistance. The present investigation relates to understanding the surface roughness and hardness by the effect of different operational conditions like wear pressure, sliding speed and ambient temperature on AISI SAE 8630, 3140, and 9310. Dry sliding wear tests have been carried out on the materials AISI SAE 8630, 3140, and 9310 under room temperature and also at high temperatures like 200°C, 400°C and 600°C on pin on disc type wear testing machine for 10,000 m sliding distance. The wear tests were carried out under the operational conditions of three sliding speeds like 1, 3 and 5 m/s, under the wear pressures of 0.125 MPa, 0.375 MPa and 0.625 MPa. Weight loss was recorded after each wear test. Hardness after wear was measured by micro hardness tester under 100 gm wear pressure. Roughness of the worn-out surface along the parallel & perpendicular was measured by roughness instrument.
 The present investigation was undertaken keeping in view the wear behaviour of metallic material influenced by the frictional force, which is turn, is governed by the hardness & oxidation kinetics of the mating surface on the high temperature wear. Nickel Chromium based alloys have been reported to be widely used as they combine several advantages such as abrasion, erosion & resistance to high temperature corrosive atmospheres. In this article a brief review of the performance of Nickel Chromium based alloy at different speeds, loads and temperatures has been made and compared with the room temperature.
 It is observed that the hardness of the worn out surface increased with an increase in the load and sliding speed due to work hardening at room temperature. Under low operational conditions, two body abrasive, under high operational conditions oxidative and under moderate operational conditions adhesive wear mechanisms are observed.
Effect of abrasive particle size on wear resistance in steels
Abstract The effects of abrasive particle size on wear resistance have been studied extensively. But, none of these studies is completely satisfactory for finding the relation between the abrasive particle size and wear rate. The abrasive wear resistance of non-heat-treated and heat-treated steels produced at broad range of different temperatures, have been determined by using a pin-abrasion machine having five abrasive papers ground on a small pin of the test materials. The mass loss of test material during abrasive wear was determined gravimetrically. The results for the non-heat-treated steels show that there is a parabolic relation between wear coefficient and abrasive particle size. This agrees with similar findings in the literature. There is a linear relationship between the abrasive wear resistance and hardness, depending on abrasive particle size. However, the relationships for the heat-treated steels show positive intercepts on the ordinate, depending on abrasive particle size. The relative wear resistance and hardness are related linearly for non-heat-treated steels, and this relationship does not depend on abrasive particle size. But, relative wear resistance for the heat-treated steels is dependent on abrasive particle size and the relationships for the heat-treated steels show positive intercepts on the ordinate. From the findings, the empirical mathematical wear resistance model as a function of abrasive particle size is derived. Additionally, the empirical equations of the relative wear resistance of these steels as a function of abrasive particle diameter are formulated.
Cavitation erosion of titanium carbide coatings on cemented carbides and other substrates
Abstract Cavitation erosion in titanium carbide (TiC) coatings precipitated by chemical vapour deposition on grey cast iron, high speed steel and four types of cobalt-based cemented carbides was investigated. In this connection a method to compare and evaluate the results for vibratory cavitation tests of surface-coated materials was developed. TiC precipitated faultlessly on cemented carbides is very effective in combating cavitation erosion. The surface topography of the coating together with pits, holes and adhesion between the grains and to the substrate have a great influence on the erosion rate.