Dry Sliding Wear Behaviour of Oil Jet Peened Aluminium Alloy, AA6063-T6:
01 Nov 2010-Vol. 224, Iss: 11, pp 1189-1196
TL;DR: In this paper, the dry sliding wear characteristics of oil jet peened aluminium alloy, AA6063-T6, were investigated using scanning electron microscope images of the worn surfaces reveal the dominant adhesive and mild abrasive form of wear.
Abstract: Oil jet peening makes use of high-pressure oil jet to impart compressive residual stresses on the surface of metallic materials in order to improve the surface properties. This article reports the dry sliding wear characteristics of oil jet peened aluminium alloy, AA6063-T6. The presence of compressive residual stress and high hardness improves the wear resistance of oil jet peened surfaces. Changes in the hardness, surface morphology, and residual stress distribution due to peening affect the tribological behaviour. The initial and steady-state coefficient of friction are less in the treated samples compared to untreated samples. The scanning electron microscope images of the worn surfaces reveal the dominant adhesive and mild abrasive form of wear.
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TL;DR: In this paper, a novel surface modification process was developed for synthesizing a nanostructured surface layer and to impart compressive residual stresses on metallic materials in order to enhance the overall surface properties.
Abstract: A novel surface modification process namely controlled ball impact peening was developed for synthesizing a nanostructured surface layer and to impart compressive residual stresses on metallic materials in order to enhance the overall surface properties. This article demonstrates the microstructural evolution, surface hardening and introduction of the residual stresses in the ball impact peened aluminium alloy surfaces, AA6063-T6. Hardened steel balls were impinged in controlled manner inducing high strain rates on the aluminium samples which are precisely moved using independent programmable logic controlled linear actuators in the controlled ball impact peening process. Mechanical properties of the nanocrystalline surface layer were investigated using dynamic ultra micro-hardness tester. The hardness of the nanocrystalline surface layer is (~ 1.3 GPa) improved compared to the matrix (~ 0.58 GPa) and the depth of the hardened layer is about ~ 350 μm depending upon the peening conditions. The amount of compressive residual stress developed by the treatment is also studied using depth sensing indentation method. The surface compressive residual stresses induced in the ball impact peened samples is about 70–127% of yield strength of the target material depending upon the peening conditions. X-ray diffraction analysis and transmission electron microscope analysis revealed the formation of nanograin crystalline structure on the ball impact peened surface layer. The mean grain size of the peened sample determined by transmission electron microscope is about 8 ± 2 nm in the top surface layer. High strain rate and repeated directional loading imparted in the contact zone generates the various dislocation activities and microstructural features which were responsible for the formation of the randomly oriented nanostructured grains on the metallic materials. With increasing strain, the various microstructural features produced in the ball impact peened aluminium samples are deformation twins, multiple shear bands, high density dislocation and dislocation pile-up at the grain boundaries as investigated by transmission electron microscope. Grain refinement on the ball impact peened aluminium surfaces resulted in the formation of high density dislocation associated with the subdivision of original grains into subgrains. The peening coverage and number of overlapping impacts depend upon the sample travelling velocity, which in turn affects the hardness, compressive residual stresses induced and grain size formed for a given ball diameter and impact velocity.
23 citations
TL;DR: In this article, the authors performed unlubricated fretting tests on the oil jet peened and unpeened aluminium samples using ball-on-flat configuration at constant slip amplitude and at different applied normal loads.
14 citations
References
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52 citations