Influence of heat treatment on slurry erosive wear resistance of Al6061 alloy

Material loss due to slurry erosion is a serious problem in many industrial applications like hydraulic turbines, slurry pumps, pipe lines, etc. where the ideal choice of engineering materials is a real challenge. Light weight aluminum alloys are finding wide applications in the field of aerospace, automobile, defence, etc. due to improved physical, mechanical and tribological properties. Among all available alloys Al6061 is extensively used owing to its reasonable strength and ease of processing. Currently these alloys are also explored as candidate materials for propeller blade of torpedoes where major failure occurs due to slurry erosive wear. In the light of the above present investigation is aimed to study the slurry erosive wear behavior of heat treated Al6061 alloy in 3.5%NaCl solution with sand particles slurry. The studies were carried out at different sand concentration (10–40%), varying rotational speed (500–1500 rpm), at different time duration (5–25 h) and varied impinging particle size (100–600 μm). The effect of heat treatment on erosive wear behavior of Al6061 alloy were studied by subjecting to solutionising at temperature of 530 °C for a duration of 2 h, followed by quenching in air, water and ice media. Both natural and artificial aging at 175 °C was performed on quenched samples from 4 to 10 h duration in steps of 2 h. The rate of material loss is found to be higher with increased sand concentration due to increased impinging action of sand particles. Increased speed of slurry rotation increases the velocity of impingement of sand particles on the surface of erodent and resulted in higher weight loss. Increased time duration up to 20 h, the wear rate increases. However, beyond this test duration, the wear rate attains a steady state with further increase in test duration. It is found that heat treatment has profound effect on slurry erosive wear resistance of Al6061 alloy. It is also observed that with increase in aging duration for all quenching medias studied there is a reduction in slurry erosive wear rate. However, ice as quenching media offers higher erosive wear resistance compared to water, air and unheat treated alloy. SEM studies were carried out on eroded surface to observe the mechanism of metal removal. The eroded surface also indicates that increased sand concentration, higher rotational speed and increased particle size resulted in severe damage on tested surfaces.