Conference Papers

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Author: search.filters.author.Ramesh, M.R.

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    Hot corrosion studies on as-received and HVOF sprayed Al2O 3+CoCrAlTaY on Ti-31 alloy in salt environment
    (Elsevier Ltd, 2013) Jegadeeswaran, N.; Ramesh, M.R.; Bhat, K.U.
    The present investigation is on the High Velocity Oxy-Fuel coating of Ti-31 alloy using fused, blended powder, Al2O3+CoCrAlTaY. Hot corrosion experiments were done on the coated and uncoated Ti-31 under a salt environment of 50% Na2SO4 and 50%V2O 5 at 800°C. Thermogravimetric cycles of 1 hour heating and 20 minute cooling was followed for hot corrosion study. After each cycle weight measurement was carried out. After hot corrosion, the samples were characterized using XRD and SEM/EDS. It was observed that the coated sample is more resistant to hot corrosion than uncoated sample. XRD and SEM analysis indicated that the surface is rich in oxides. Gravimetric analysis indicated that the sample weight gain was following a parabolic relationship with time. A damage mechanism is discussed for the hot corrosion damage of the samples. Presence of high level of chromium in HVOF sprayed coating imparts improved hot corrosion resistance at 800°C, in a molten salt environment of Na2SO4 + V 2O5. © 2013 The Authors. Published by Elsevier Ltd.
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    Fabrication of stainless steel based composite by metal injection moulding
    (Elsevier Ltd, 2018) Veeresh Nayak, C.; Ramesh, M.R.; Desai, V.; Kumar Samanta, S.K.
    Metal injection moulding (MIM) is large scale manufacturing method, for creation of complex shapes and miniature parts by a combination of plastic injection moulding with the flexibility in sintering of metal particulates. In current investigation binder comprised of paraffin wax, polyethylene glycol, stearic acid and low-density polyethylene are developed for moulding of composite powders of SS316L+WC-CrC-Ni, and sintered at 1200°C under hydrogen purged atmosphere. Composites are characterised with respect to rheological, thermal properties and microstructure by scanning electron microscopy, microhardness and density. Properties of sintering temperature and heating rate on the above properties have been evaluated to obtain a defect-free composite. © 2017 Elsevier Ltd.
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    Microstructure, mechanical and corrosion properties of accumulative roll bonded Mg-2%Zn/anodized Al-7075 composite
    (Elsevier Ltd, 2018) Anne, G.; Ramesh, M.R.; Shivananda Nayaka, H.S.; Arya, S.B.
    Multilayered composite of Mg-2%Zn/anodized Al-7075 was developed by accumulative roll bonding (ARB) of wrought Mg-2%Zn and anodized aluminium 7075 alloy. The Mg-2%Zn/anodized Al-7075 composite exhibited density of 2298 kg/m3 which is about 1.2 times lighter weight as compared to Al-7075 alloy. The electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) showed an average grain size of 1 μm and 0.73 μm in Mg-2%Zn and anodized Al-7075 layers respectively, and with high angle grain boundaries (HAGBs). Mechanical properties were evaluated by microhardness and tensile tests and found significant improvement in strength and hardness values as compared with Mg-2%Zn alloy after four pass ARB process. The multilayered composite shows better corrosion resistance as compared to rolled Mg-2%Zn alloy evaluated using using potentiodynamic polarization test. © 2017 Elsevier Ltd.
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    Studies on the role of HVOF coatings to combat erosion in turbine alloys
    (Elsevier Ltd, 2018) Prasanna, N.D.; Siddaraju, C.; Shetty, G.; Ramesh, M.R.; Reddy, M.
    Erosive wear is caused by the action of sliding or impact of solids, liquids, gases or the combination of these. Solid particle erosion is an important material degradation mechanism encountered in a number of engineering systems such as gas turbine engines, thermal power plants, coal slurry pipe lines. Erosive action results from the impact of particulates, such as coal ash, dolomite and un-burnt carbon particles on the surface of turbine. Super alloys developed for high temperature applications suffer from the drawback that the strength and the erosion-corrosion resistance at high temperature exhibited are poor. To improve the resistance property, one way would be the use of coatings on the super alloy component. Coatings take care of the problems related to erosion whereas the super alloys take care of the requirement of strength at elevated temperature. Various coatings have been highly attractive; however, High Velocity Oxy-fuel (HVOF) process, a family of thermal spray techniques uses kinetic energy of the burnt gases to soften and to propel the spray powder producing dense very low porosity, good inter-particle cohesion and well bonded coatings. In the present study successful attempts have been made to spray Stellite-6, 10%Al2O3+90%CoCrAlTaY and 25%Cr3C2-20(Ni-Cr)+75%NiCrAlY on three kinds of turbine alloys, namely Ti-6Al-4V, Co-based super alloy (Super co 605) and Fe-based special steel (MDN121).Microstructure and mechanical properties of the coatings have been characterized. Erosion tests for different conditions using Air-jet erosion test rig for different impingement angles have been studied in detail. From these studies it is observed that satellite-6 coating exhibits lower erosive rate compared to other two coating materials. The morphology of the eroded surface shows craters, groove formation in the binder matrix and carbide pull-out as the existing erosion mechanism. Higher erosion loss is observed for Al2O3+CoCrAlTaY coating. © 2018 Elsevier Ltd.
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    Effect of Lateral Vibrations during Directional solidification on Mechanical Properties of Al-18%wt Si Alloys
    (Elsevier Ltd, 2018) Ramesh Babu, N.; Ramesh, M.R.; Kiran Aithal, S.; Kotresh, K.
    Experimental Investigation on the effect of mold vibration on the mechanical properties of Al-18%WtSi have been carried out using Taguchi Technique, as the molten metal at 750°C is poured in to the insulated mold which is subjected to lateral vibrations, directional solidification takes place due to the presence of chill at the bottom which gives rise to a functionally graded alloy. Due to the excitation, silicon present in the molten metal precipitates along its length. The castings are prepared with varying chill materials and chill volumes without vibrations and with a vibrating frequency of 50Hz. ANOVA was applied to optimize the process parameters. Hardness and Tensile test for the samples was carried out. Improvements in the properties can be attributed to the grain refinement of the casting prepared under vibrations. © 2017 Elsevier Ltd.
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    Micro-mechanical characterization and wear performance of TiAlN/NbN PVD coated carbide inserts during End milling of AISI 304 Austenitic Stainless Steel
    (Elsevier Ltd, 2018) Varghese, V.; Dupadu, D.; Ramesh, M.R.
    A multi-layer TiAlN/NbN coated on tungsten carbide insert by physical vapor deposition method (PVD) was selected for studying tool wear performance during end milling of AISI 304 Austenitic stainless steel. Stainless steel AISI 304 belongs to the class of difficult to machine materials, which tends to work harden during machining. The coating has been studied for its micro-mechanical characteristics using SEM/EDS, XRD, 3D confocal microscope & Nano indentation. Characterization results revealed that TiAlN/NbN coatings was well deposited. Dry milling experiments were carried out to evaluate tool life & failure mechanisms of coated tool. It was shown that micro chipping and peeling of coatings were major wear mechanisms observed during dry end milling of AISI 304 using coated inserts. © 2017 Elsevier Ltd. All rights reserved.
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    Effect of machining process parameters on productivity rate and surface roughness of machined TiNiCo alloy
    (Elsevier Ltd, 2018) Soni, H.; Narendranath, S.; Ramesh, M.R.
    TiNiCo based shape memory alloy is an important alloy for biomedical applications such as bone staple due to their excellent biocompatibility, corrosion resistance, shape memory effect (SME) and pseudoelasticity (PE). Traditional machining of such kind of alloys is difficult due to their outstanding properties. Wire electro discharge machining (WEDM) is most suitable non-traditional machining process for machining of these alloys. Present study focuses on effect of WEDM process parameters on productivity rate and surface roughness. Pulse on time, servo voltage and wire speed were considered as WEDM process parameters with their five levels in the current study. Our observation exhibit that productivity rate and surface roughness increases with increasing pulse on time and both outputs decrease with increasing servo voltage while wire speed does not show much effect on productivity rate as well as surface roughness. © 2018 Elsevier Ltd. All rights reserved.
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    Performance of DLC coated tool during machining of MDN431 alloyed steel
    (Elsevier Ltd, 2018) V Badiger, P.V.; Desai, V.; Ramesh, M.R.
    Highly alloyed steel are widely used in manufacturing of turbine materials because of its high resistance to corrosion and oxidation. MDN 431 is one of such material manufactured by Midhani. It's having high hardness and strength which makes it hard-to-machine steel. DLC coating provide solution to this problem. DLC coating are developed using state of art PVD technique on the HSS tool. Turning process carried out on MDN431 steel using coated and uncoated HSS tool insert in both wet and dry condition. During the present investigation, speed, feed, and depth of cut varied according to full factorial design with level 3, consequently cutting forces, surface roughness (Ra) and tool wear were measured. The obtained results are optimized using factorial method for cutting forces and surface roughness. Using FFD method second order regression analysis carried out for each input variable and same compared with experimental values and found the developed model is with minimal error which supported by proof trials. Speed and depth of cut are inversely dependent on the cutting force and surface roughness whereas feed is opposite to it. Effect of DLC coating during machining of MDN431 is studied using optical profilometry in comparison with uncoated tool. © 2018 Elsevier Ltd.
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    Performance of Ti-multilayer coated tool during machining of MDN431 alloyed steel
    (American Institute of Physics Inc. subs@aip.org, 2018) V Badiger, P.V.; Desai, V.; Ramesh, M.R.
    Turbine forgings and other components are required to be high resistance to corrosion and oxidation because which they are highly alloyed with Ni and Cr. Midhani manufactures one of such material MDN431. It's a hard-to-machine steel with high hardness and strength. PVD coated insert provide an answer to problem with its state of art technique on the WC tool. Machinability studies is carried out on MDN431 steel using uncoated and Ti-multilayer coated WC tool insert using Taguchi optimisation technique. During the present investigation, speed (398-625rpm), feed (0.093-0.175mm/rev), and depth of cut (0.2-0.4mm) varied according to Taguchi L9 orthogonal array, subsequently cutting forces and surface roughness (Ra) were measured. Optimizations of the obtained results are done using Taguchi technique for cutting forces and surface roughness. Using Taguchi technique linear fit model regression analysis carried out for the combination of each input variable. Experimented results are compared and found the developed model is adequate which supported by proof trials. Speed, feed and depth of cut are linearly dependent on the cutting force and surface roughness for uncoated insert whereas Speed and depth of cut feed is inversely dependent in coated insert for both cutting force and surface roughness. Machined surface for coated and uncoated inserts during machining of MDN431 is studied using optical profilometer. © 2018 Author(s).
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    Parametric study of laminated composite material shaft of high speed rotor-bearing system
    (American Institute of Physics Inc. subs@aip.org, 2018) Gonsalves, T.H.; Mohan Kumar, G.C.; Ramesh, M.R.
    In this paper some of the important parameters that influence the effectiveness of composite material shaft of high speed rotor-bearing system on rotor dynamics are analyzed. The type of composite material composition, the number of layers along with their stacking sequences are evaluated as they play an important role in deciding the best configuration suitable for the high-speed application. In this work the lateral modal frequencies for five types of composite materials shaft of a high-speed power turbine rotor-bearing system and stresses due to operating torque are evaluated. The results are useful for the selection of right combination of material, number of layers and their stacking sequences. The numerical analysis is carried out using the ANSYS Rotor dynamic analysis features. © 2018 Author(s).