Faculty Publications
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Item Scratch and wear resistance of interstitial-free steel subjected to severe shot peening(SAGE Publications Inc., 2024) Sahoo, B.; Bhat K, U.; Rao, M.Surface integrity in terms of scratch and wear resistance is the major concern of any engineering component, which is attributed to most of the surface damages. A popular way of improving such behaviours is the mechanical treatment of the surface. The current investigation studied the improvement of scratch and wear properties by performing shot peening on the Ti–Nb stabilised interstitial free steel, a popular choice in automotive industries. The samples were shot-peened at different coverages. It was found that the shot-peened samples showed a superior scratch and wear behaviour as compared to as-received samples. The scratch hardness was improved by 2.4 times, the wear volume was decreased by 59.6%, and the wear rate was minimal for the 2000% peened sample. © Institute of Materials, Minerals and Mining 2024.Item Microstructural Features Intimated in Automotive Grade IF Steel Subjected to Conventional and Severe Shot Peening(Springer, 2024) Sahoo, B.; Udaya Bhat, K.A significant amount of interstitial-free or IF steel is used to manufacture automotive body parts due to its high ductility, high formability, and low yield strength. But, the major drawback of this steel is the lower surface hardness. The current investigation intended to enhance the surface hardness by employing shot peening at different coverages. The work also studied the microstructural features intimated after the treatment and its effect on the surface hardness. The optical and transmission electron microscopy (TEM) results showed a prominent grain refinement and dislocation hardening, which improved the micro-hardness to 2.5 times. Tri-junctions, sub-grains, twins, nanocrystalline regions, and several dislocation-induced microstructural features, like dislocation bands, dislocation forests, dislocation walls, dislocation cell structure, etc., were detected in the samples after peening. These features bear a beneficial impact on the surface hardness of the substrate. A spatial filter (Sobel filter) was used to refine the image and detect the presence of NbC precipitates near the grain boundary. Using Gatan DigitalMicrograph software, the thermal imaging technique effectively identified thinner grain boundaries near the segregation zone. © ASM International 2024.Item Tailoring the surface characteristics and mechanical behavior of Ti-Nb stabilized IF steel through controlled shot peening coverage(Elsevier Ltd, 2025) Sahoo, B.; Udaya Bhat, K.; Kumar, D.S.The rising demand for a qualitative surface opens a new window of research in the domain of mechanical surface treatment, known as severe shot peening, especially in the automotive industry. The effectiveness of this method is usually affiliated with various process parameters, of which peening coverage is the most sought-after. It is anticipated to elevate the surface characteristics by proficiently optimizing the peening coverage. On this ground, the current investigation tries to gather the beneficial effect of peening coverage on the surface properties of Ti-Nb stabilized interstitial-free steel subjected to severe shot peening by considering four different coverages (100 %, 500 %, 1000 %, and 2000 %). The work attempts to interpret the impact of peening coverage on grain refinement and dislocation-induced microstructures at different depths of the as-treated sample. The crossectional microscopy unveiled a prominent grain refinement hardening and dislocation hardening in 2000 % peening coverage up to a depth of 90–120 µm, firmly agreeing with the microhardness depth profile. The optical microscopy identified four zones of deformation (severe deformation, deformation, transition, and undeformed zone) in the sample treated with the highest coverage. The transmission electron microscopy demonstrated the dominance of certain dislocation-derived features like dislocation forest, dislocation cells, tangled dislocations, dislocation bands, nanocrystalline region, stress concentration region, etc., at the deformed zone of the treated samples. Interestingly, the trace of these features was detected at a greater depth for the highest-peened sample than the lowest-peened sample, affirming the beneficial aspect of higher peening coverage. The stored energy and thermal stability assessment in the as-received and as-treated sample was done in the differential scanning calorimeter, revealing the favorable impact of severe peening on the substrate. The surface topographical study in a 3D profilometer also unveils the variation in the surface roughness and functional volume parameters. The present investigation also analyzed the maximum depth and mean density of furrows to verify the severe plastic deformation in the as-treated sample. © 2024Item Elevated-Temperature Tribological Study of Interstitial-Free Steel Subjected to Shot Peening(Springer, 2025) Sahoo, B.; Bhat, K.U.The tribological behavior of steels at an elevated temperature plays a vital role in manufacturing processes like rolling, stamping, drawing, deep drawing, etc., where a prominent metal-to-metal contact demands a good wear resistance of the surface. The current investigation is based on improving the tribological behavior of interstitial-free steel by subjecting it to shot peening. The wear test was conducted at four different temperatures: 25, 100, 200, and 400 °C. The shot peening was done in two sets: conventionally shot peening and severe shot peening (SSP). The profile of the wear scar was analyzed in a profilometer, confirming the superiority of the SSPed sample in terms of smaller wear scar and lesser wear rate. Considering the temperature effects, the increase in wear resistance was more prominent at 400 °C due to the trace of thick oxide layers countering the ultrafine, fine oxide layers in the 200 and 100 °C wear conditions. The presence of protective ?-Fe2O3 layers and lubricative Fe3O4 layers was advantageous in the tribological aspect, contributing to the formation of a thinner wear scar and lower wear rate. A prominent trace of counter body material was also found in the debris generated at 400 °C wear condition. © ASM International 2024.