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Item Ultrasonic surface rolling process: Properties, characterization, and applications(MDPI, 2021) John, M.; Ralls, A.M.; Dooley, S.C.; Thazhathidathil, A.K.V.; Perka, A.K.; Kuruveri, U.B.; L Menezes, P.L.Ultrasonic surface rolling process (USRP) is a novel surface severe plastic deformation (SPD) method that integrates ultrasonic impact peening (UIP) and deep rolling (DR) to enhance the surface integrity and surface mechanical properties of engineering materials. USRP can induce gradient nanostructured surface (GNS) layers on the substrate, providing superior mechanical properties, thus preventing premature material failure. Herein, a comprehensive overview of current-state-of-the art USRP is provided. More specifically, the effect of the USRP on a broad range of materials exclusively used for aerospace, automotive, nuclear, and chemical industries is explained. Furthermore, the effect of USRP on different mechanical properties, such as hardness, tensile, fatigue, wear resistance, residual stress, corrosion resistance, and surface roughness are summarized. In addition, the effect of USRP on grain refinement and the formation of gradient microstructure is discussed. Finally, this study elucidates the application and recent advances of the USRP process. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Item Surface Modification of 6xxx Series Aluminum Alloys(MDPI, 2022) Kuruveri, U.B.; Bhat Panemangalore, P.; Kuruveri, S.B.; John, M.; L Menezes, P.L.Due to their superior mechanical properties, formability, corrosion resistance, and lightweight nature, 6xxx series aluminum (Al) alloys are considered as a promising structural material. Nevertheless, the successful application of these materials depends on their response to the external environment. Recently, designers considered the surface properties an equally important aspect of the component design. Due to this concern, these alloys are subjected to varieties of surface modification methodologies. Many methodologies are explored to modify the 6xxx series Al alloys sur-faces effectively. These methods are anodizing, plasma electrolytic oxidation (PEO), cladding, friction stir processing, friction surfacing, melting, alloying, and resolidification using high energy beams, etc. This review work discusses some of these methods, recent research activities on them, important process variables, and their role on the final properties of the surfaces. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Item Influence of Multi-directional Room-Temperature Forging Process on Microstructure and Mechanical Behaviour of Eutectic Al-12Si Alloy(Springer, 2022) Kumara, B.; Preetham Kumar, G.V.In the present work, the influence of multi-directional forging on the microstructure and mechanical behaviour of eutectic Al-12Si alloy at ambient temperature has been examined. The sample for multi-directional forging was prepared by melting and pouring the commercially available LM-6 aluminum alloy ingot into a casting die. Prior to the forging process, the samples were solutionized for 3 h at 525 °C and then cooled in water. Light optical microscopy and scanning electron microscopy were used to examine the microstructure of materials. Microstructural observations have shown that effectively broken coarse needle-shaped plates like silicon particles with an average size of 11.7 µm in length of as-cast samples into fine particles with an average size of 2.8 µm in length after three cycles of forging (9 passes) and are evenly distributed in the α-Al phase. After three cycles, the tensile strength of the as-cast sample is enhanced from 192 to 382 MPa, and its hardness is enhanced from 66.6 to 100.2 Hv, respectively. X-ray diffraction analysis of Al-12Si alloys revealed the existence of α-Al and eutectic silicon (Si) phases. The peak broadening is also noted in X-ray diffraction pattern of three cycles, samples with cumulative strains of 2.43, which confirms the reduction in silicon particle size and grain size. Facets and tearing ridges are observed on the tensile fracture surface of forged samples. The improvement in the mechanical properties of forged samples can be attributed to the evenly distributed silicon particles and the work hardening of the aluminum phase. © 2022, ASM International.Item Influence of Solid Lubricants on Microstructure and Tribological Performance of Nickel-Based Composite Coatings(Springer, 2022) Gudala, S.; Ramesh, M.R.; Siva Shanmugam, N.S.The present study investigates the microstructure and high-temperature tribological studies of solid lubricant encapsulated nickel alloy coatings developed by tungsten inert gas (TIG) cladding technique. The TIG current values of 90 A, 95 A, and 100 A were considered as process parameters. The microstructure of the coatings (coating A: NiCrSiB/WC/Ag/hBN, coating B: NiCrSiB/WC/MoS2/hBN) was characterized using the scanning electron microscopy, X-ray diffraction, X-ray energy dispersive spectroscopy and EBSD (electron backscatter diffraction) analysis. The dry sliding wear studies were conducted using a pin on disc apparatus, and the microhardness of the coating was assessed using Vicker’s indentation technique. The results show that coating A exhibited high hardness and excellent tribological properties than coating B. In particular, coating A presents the high average microhardness (950 HV), low coefficient of friction (0.34), and wear rate (2.96 × 1−3 mm3/N-m). Additionally, coating A showed three-fold higher hardness and a 2.43 times lower wear rate than the titanium substrate. The lubricant phases (Ag, BN, Mo2S3) and oxide phases (TiO, Ag2O, Ni (TiO3)) formed in both coatings were adequate to reduce the material loss. © 2022, ASM International.Item Optimization of Annealing Parameters for Ferritic Hot-Rolled IF Grade Steel(Springer, 2022) Kumar, D.S.; Sambandam, S.; Bhat, K.U.Ferritic hot rolling of low carbon steel is now widely adopted by steelmakers for reducing energy costs and increasing the yield. These ferritic hot-rolled coils carry forward different grain morphology and texture which result in variation in properties after cold rolling and annealing compared to austenitic hot-rolled coils. These ferritic hot-rolled coils require different annealing treatments based on the hot rolling temperature for better results. In the present work, a Nb–Ti stabilized interstitial free (IF) grade steel was hot rolled at two different temperatures in the ferritic regime in an industrial hot strip mill and was subsequently cold rolled. These cold-rolled sheets were subjected to different continuous annealing cycles with soaking temperatures varying from 740 to 820 °C on a thermo-mechanical simulator for optimization of temperatures and study its effect on microstructure and properties. These coils were compared with simulated conventional austenitic hot-rolled coils. Ferritic rolled coils show better elongation and a higher percentage of equiaxed grains indicating better formability. The optimum continuous annealing temperature was found to be a function of hot rolling temperature in the ferritic regime. Elongation and grain size increased with an increase in temperature in all the samples, but the ferritic rolled coils show faster change due to higher stored energy. Comparison of elongation and microstructure indicates that temperatures above 780 °C should be sufficient for achieving complete recrystallization in ferritic rolled samples, compared to 810 °C required in the conventional austenitic rolled sheets which is an industrial advantage. Based on simulation studies, full-scale plant continuous annealing was carried out under the optimized temperature conditions where microstructure and properties matched closely with the simulation results and electron backscatter diffraction (EBSD) analysis confirmed improved texture. © 2022, ASM International.Item Item An investigation was carried out to examine the influence of chromium content on the plane strain fracture toughness of austempered ductile iron (ADI). ADIs containing 0, 0.3 and 0.5 wt.% chromium were austempered over a range of temperatures to produce different microstructures. The microstructures were characterized by optical microscopy and X-ray diffraction. Plane strain fracture toughness of all these materials was determined and correlated with microstructure and chromium content. The chromium content was found to influence the fracture toughness through its influence on the processing window. Since the chromium addition shifts the processing window to shorter durations, the higher chromium alloys at higher austempering temperatures tend to fall outside of the processing window, resulting in less than optimum microstructure and inferior fracture toughness. A small chromium addition of 0.3 wt.% was found to be beneficial for the fracture toughness of ADI. © 2002 Elsevier Science B.V. All rights reserved.(Elsevier BV, Investigations on the fracture toughness of austempered ductile iron alloyed with chromium) Prasad Rao, P.; Putatunda, S.K.2003Item Ductile cast iron was austenitized at four different temperatures and subsequently austempered at six different temperatures. Plane strain fracture toughness was evaluated under all the heat treatment conditions and correlated with the microstructural features such as the austenite content and the carbon content of the austenite. Fracture mechanism was studied by scanning electron microscopy. It was found that the optimum austempering temperature for maximum fracture toughness decreased with increasing austenitizing temperature. This could be interpreted in terms of the microstructural features. A study of the fracture mechanism revealed that good fracture toughness is unlikely to be obtained when austempering temperature is less than half of the austenitizing temperature on the absolute scale. © 2002 Elsevier Science B.V. All rights reserved.(Elsevier BV, Investigations on the fracture toughness of austempered ductile irons austenitized at different temperatures) Prasad Rao, R.; Putatunda, S.K.2003Item SiC particulate reinforced A356 Al metal matrix composites were laser treated using pulsed Nd-YAG laser beam. The processing was carried out in air atmosphere at varying pulse energy (5 to 20 J) and scan rates (30 to 150 mm/sec). The samples were cut perpendicular to the track and they were characterized using optical microscopy, scanning electron microscopy and X-ray diffraction. Microstructure of laser treated region consists of regular succession of coarse and fine microstructure signifying the presence of low velocity bands. Transition from cellular/columnar dendritic to equiaxed dendritic structure has been observed. Microstructure of samples laser treated with specific energy greater than 13 kJ/cm2 show presence of Al 4C3 platelets. © 2004 Kluwer Academic Publishers.(Microstructural studies in low specific energy laser surface treated Al(A356)-SiCp composites) Bhat, K.U.; Surappa, M.K.2004Item The microstructure of a solidifying lead free Sn-3.5Ag solder alloy is found to be highly sensitive to the surface condition of the copper substrate. A transition from lamellar to fine fibrous eutectic structure is observed as the surface condition of the substrate is altered by increasing the surface roughness and application of flux. This is attributed to lowering of interfacial tension and improved wetting of the solidifying solder on the substrate material leading to a better contact at the metal/substrate interface. The results also indicated the importance of surface texture of the substrate and the application of the flux to the quality of the solder/substrate joint. © 2003 Elsevier Ltd. All rights reserved.(Elsevier Ltd, Effect of substrate surface texture and flux coating on the evolution of microstructure during solidification of lead free Sn-3.5Ag solder alloy) Prabhu, K.; Bali, R.; Ranjan, R.2004