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.
The sliding wear mechanisms of metals, mainly steels
Abstract Early studies of the dry and boundary lubricated wear of metals concentrated on the most catastrophic wear conditions, severe wear and scuffing. It was established how these states could be avoided by protective film formation. Subsequently studies away from these conditions have shown wear either by the removal of surface reaction films or by metal surface fatigue. This review traces these developments and places them in perspective.
A metallurgical approach to improved cavitation-erosion resistance
Although cavitation erosion in hydraulic systems is an old problem, the damage mechanism that culminates in material loss was not known with certainty until recently. An investigation is described that aimed at clarifying the damage mechanism in cavitation erosion and applying that knowledge to make hydraulic equipment more resistant to cavitation. Strong correlations were established between cyclic deformation (fatigue) parameters and cavitation-erosion rates. This identification facilitated the search for more resistant materials. Finite element modeling confirmed that localized impacts on metal surfaces produce fatiguelike deformations and damage accumulation. Among available materials, near-equiatomic alloys of nickel and titanium are anomalously resistant to low-cycle fatigue and thus should be very resistant to cavitation erosion. Experiments confirmed the expected erosion resistance. Building large machines entirely out of NiTi is impractical, however, and a way of selectively cladding common constructional materials is required. Because NiTi has not been fusion welded successfully to other alloys, explosive bonding of thin NiTi plates to structural steel was investigated. Excellent welds were achieved, and the erosion resistance of the resulting clads has been demonstrated. Comparisons are made to other erosion processes and to other erosion-resistant materials, and some applications to hydraulic devices are suggested.