Faculty Publications
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Item Burnishing of ultra high molecular weight poly ethylene(Elsevier Ltd, 2021) Ashish, V.; Prasanna Kumar Reddy, S.; Kannan, C.; Oyyaravelu, R.; Balan, A.S.S.Ultra-high molecular weight polyethylene (UHMWPE) has been a choice for knee and hip implants since a very long time due to its outstanding tribological properties. UHMWPE has many applications other than biomedical implants like hydrodynamic bearings and marine applications. The main objective of this research work is to enhance the surface properties of UHMWPE and eventually increase its life expectancy for the implants. For this purpose, the UHMWPE sheet has been milled to give it a required shape and then ball burnished with a carbide ball of 6mm diameter under two different environments viz. room and cryogenic with three different burnishing strategic patterns. A constant load of 150N is maintained by the tool on UHMWPE sample with a burnishing feed of 4000mm/min along with a step over a distance of 0.06mm after every pass for three different carefully chosen burnishing patterns. To understand the wear behaviour of the material, wear test has been performed on reciprocating wear testing machine with a stainless-steel ball as a pin for 6500 cycles in the medium of Hank's balanced salt solution (HBSS) as a lubricating agent and to maintain the pH value which is same as in the human body. The lowest average surface roughness (Ra=0.52μm) is reported for the second strategy pattern which gets burnished under the cryogenic environment. This sample also exhibited better wear resistance than other samples burnished under different environments and using different strategic patterns. © 2021 Elsevier Ltd. All rights reserved.Item Exploring grinding and burnishing as surface post-treatment options for electron beam additive manufactured Alloy 718(Elsevier B.V., 2020) Karthick Raaj, R.; Vijay Anirudh, P.; Karunakaran, C.; Kannan, C.; Jahagirdar, A.; Joshi, S.; Balan, A.S.S.Numerous additive manufacturing (AM) techniques have been developed over the past decade. Features like immense freedom of intricate part design and shorter lead time make AM routes promising for a wide range of applications spanning aerospace, marine and automobile sectors. Among the various metal AM processes, Electron Beam Additive Manufacturing (EBAM) is being widely explored to realise the potential of Ni-based superalloys and Ti alloys for varied high-performance applications. A novel attempt has been made in this paper to assess the surface integrity of as-built EBAM nickel-based superalloy 718 (AB) subjected to grinding (G), Low Plasticity Burnishing (LPB) and their sequential combination. Apart from their influence on sub-surface microstructures, the effect of process variables during the above post-treatments on the residual stress profiles was also investigated. Results revealed that G + LPB results in about 0.6 ?m lower surface roughness, 17% improved microhardness compared to AB + LPB, and higher compressive surface residual stress as compared to LPB processed EBAM samples. The sequential grinding and LPB - improved microhardness, was also found to extend about 500 ?m more when compared to the LPB process. The G + LPB, which is greatly influenced by the prior grinding, smoothens the surface and thus results in a better surface finish. Highest hardness, superior surface finish, reduced porosity and improved compressive residual stress were observed in samples that adopted the AB + G + LPB sequence over other samples, with the LPB step at 40 MPa yielding the best results. © 2020 Elsevier B.V.Item Effect of Cryogenics-Assisted Low-Plasticity Burnishing on Laser-Clad Stellite 6 over SS420 Substrate(Springer, 2020) Anirudh, P.V.; Kumar, B.; Girish, G.; Shailesh, S.; Oyyaravelu, R.; Kannan, C.; Balan, A.S.S.The influence of modern additive manufacturing methods, especially from the direct energy deposition (DED) processes to the coat-like finished components, is crucial under present industrial circumstances. DED induces several traits like enhanced mechanical, thermal properties in shorter lead time, which extend their adaptation for diverse applications including aerospace and automobile industries. Among the several DED processes, laser cladding has been a prospect that explores various capabilities of improving the wear resistance of cobalt-chromium (Co-Cr)-based alloys. Rather than fabricating the complete component using expensive alloys, laser cladding has paved an approach to deposit particles possessing superior qualities over the conventional material. This research work attempts to evaluate the surface integrity of SS420 when cladded with Stellite 6. The vertical face milling is executed on the cladded component surface to facilitate either low-plasticity burnishing (LPB) or cryogenic burnishing (CB) as sequential post-treatment processes. The effects of these post-treatments on the surface and subsurface microhardness, surface topography and residual stress profiles are elaborated. Increased surface and subsurface microhardness, as well as improved residual stress profiles, are observed with CB over LPB-processed specimen samples. © 2020, ASM International.Item Surface Characteristics of Low Plasticity Burnished Laser Directed Energy Deposition Alloy IN718(Springer, 2024) Mohanraj; Thanumoorthy, R.S.; Sekar, P.; Muthuchamy, A.; Bontha, S.; Balan, A.S.S.The research work focuses on a novel post-processing sequence to improve the surface integrity and residual stress characteristics of as-printed Inconel718 (IN718) samples. The as-printed IN718 samples are subjected to solution treatment at 1050 °C, two-step precipitation hardening (@ 720 °C for 8 h and @ 620 °C for 8 h), and low plasticity burnishing. Two different sequences were attempted. Sequence-1 involves solutionizing ? low plasticity burnishing followed by precipitation hardening, and sequence-2 includes solutionizing ? precipitation hardening followed by low plasticity burnishing. The experimental observations and detailed investigations revealed that the samples processed via sequence 2 exhibited a better surface finish. The microhardness of the samples of sequence 2 is 10% higher than their counterparts in sequence 1. The maximum residual stress of ?1375.33 MPa is obtained in sequence 1 as compared to the residual stress of ?1100.67 MPa in sequence 2. The influence of the processing sequences on the surface properties has been discussed in detail using the XRD and microstructural characterization supported with EBSD analysis. Graphic Abstract: (Figure presented.) © The Indian Institute of Metals - IIM 2024.Item Effect of burnishing strategies on surface integrity, microstructure and corrosion performance of wire arc additively manufactured AZ31 Mg alloy(KeAi Publishing Communications Ltd., 2025) Manjhi, S.K.; R, O.; Bontha, S.; Balan, A.S.S.AZ31 Mg alloy is an emerging material that has received considerable attention in aerospace, automotive, and temporary biodegradable implant applications owing to its attractive properties, such as low density, high specific strength, and biodegradability. Nevertheless, some shortcomings in Mg alloys are their low ductility, which is associated with challenging its manufacturing, and poor corrosion resistance associated with unreliable components. Therefore, a cold metal transfer wire arc additive manufacturing (CMT-WAAM) process is used to manufacture AZ31 Mg alloy and achieved 29.4 % ductility by controlling the gas porosity, keyhole porosity, and internal cracks. Further, severe plastic deformation is induced on the surface of deposited parts by low plasticity burnishing (LPB) with parallel and cross-pattern burnishing to modulate their surface to slow down the kinetics of the corrosion damage. The average surface roughness (Sa) of the cross-burnishing pattern is 0.235 ?m, which is 123.6 % lower than the parallel burnished and 261.7 % lower than the milled specimens. The residual stress (RS) of WAAM is 40 MPa with a tensile nature; however, it is drastically reduced and develops compressive RS of 45 MPa under a parallel burnishing pattern and 62 MPa under a cross-burnishing pattern. Moreover, LPB with cross pattern deformed ?395 ?m depth of WAAMed AZ31 workpiece, which is ?45 % higher than deformed depth (?272 ?m) by parallel pattern burnishing. The electrochemical corrosion rate of the WAAM specimen is 9.71 mm/year, and it is reduced to 1.82 mm/year under LPB caused by compressive residual stress and grain refinement. © 2024 The Authors