Browsing by Author "Mukunda, P.G."

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Correlation of Tribological Properties with Microstructure and Mechanical Properties of Graphite Cast Irons Centrifugally Cast for Engine Liner
(Springer India sanjiv.goswami@springer.co.in, 2014) Desai Gowda, H.S.; Mukunda, P.G.; Herbert, M.A.
This is a study of the influence of centrifugal process on the graphite morphology, mechanical and wear properties on flake graphite iron (FGI), spheroidal graphite iron (SGI) and compacted graphite iron (CGI). Melts of hypereutectic and almost of identical composition with or without melt treatment were centrifugally cast. The microstructure, mechanical and wear properties of these specimens were studied. In the microstructure for FG iron it has been observed that the centrifugal process produces flake size range class 2–3 (range 160–320 ?m) and graphite of flake type A by about 67.9 % (field %) and combined flakes of type B, C, D and E will be of 32.1 % (field %). While SGI has been observed to have 96.1 % nodules and 330.0 nodules per square millimeter. Similarly CGI has been seen to produce 52.0 % nodules and 113 nodules per square millimeter. SGI possess the highest tensile strength, rupture strain and hardness of 604 N/mm2, 6.1 %, 233 BHN respectively. Whereas FGI possess the least tensile strength, rupture strain and hardness of 303 N/mm2, 0.65 %, 185 BHN respectively among the irons. CGI has a tensile strength, rupture strain and hardness of 369 N/mm2, 1.2 % and 200 BHN respectively which lies in between those of FGI and SGI. During the wear test similar materials for both disk and pin combination show higher co-efficient of friction and wear rate than those for dissimilar material combinations. SGI disk and FGI pin combination show least wear. This combination would be ideally suited for engine liner and piston rings. © 2014, Indian Institute of Metals.
Effect of centrifugal and gravity casting technique over metallographic and mechanical properties of spheroidal graphite iron
(2013) Desai, Gowda, H.S.; Mukunda, P.G.; Herbert, M.A.
The mechanical properties of cast iron depend on the graphite morphology and characteristics of metallic matrix. In spheroidal graphite iron these properties are affected by the nodule count, nodule percentage, nodularity, nodules per square mm, nodule types and size distribution. In this work an attempt is made to study of the effect of centrifugal and gravity casting process on the morphology and mechanical properties. A comparison of microstructure and mechanical properties of specimens of the cast are studied. It has been observed that the centrifugal effect produces an increase in rupture strain but hardness is unaffected. In microstructure it has been observed that the centrifugal effect produces an increase in the number of bigger nodules and decrease in the number of smaller nodules and an increase of nodules per square mm. It has no effect on nodularity percentage. The centrifugal casting process produces better mechanical properties.
Effect of centrifugal and gravity casting technique over metallographic and mechanical properties of spheroidal graphite iron
(2013) Desai Gowda, H.S.; Mukunda, P.G.; Herbert, M.A.
The mechanical properties of cast iron depend on the graphite morphology and characteristics of metallic matrix. In spheroidal graphite iron these properties are affected by the nodule count, nodule percentage, nodularity, nodules per square mm, nodule types and size distribution. In this work an attempt is made to study of the effect of centrifugal and gravity casting process on the morphology and mechanical properties. A comparison of microstructure and mechanical properties of specimens of the cast are studied. It has been observed that the centrifugal effect produces an increase in rupture strain but hardness is unaffected. In microstructure it has been observed that the centrifugal effect produces an increase in the number of bigger nodules and decrease in the number of smaller nodules and an increase of nodules per square mm. It has no effect on nodularity percentage. The centrifugal casting process produces better mechanical properties.
Effect of combined grain refinement and modification on microstructure and mechanical properties of hypoeutectic, eutectic and hypereutectic Al-Si alloys
(Inderscience Publishers, 2015) Shivaprasad, C.G.; Kiran Aithal, K.; Narendranath, S.; Desai, V.; Mukunda, P.G.
The effect of melt treatment owing to the combined addition of grain refiner and modifier on the microstructure and mechanical properties of Al-Si alloys having 7% (hypoeutectic), 12% (eutectic) and 15% silicon (hypereutectic) is studied. 1 wt. % of Al-1Ti-3B Master alloy was used as grain refiner. For modification of eutectic Si, 0.2 wt. % of Al-10Sr Master alloy was added to hypoeutectic alloy and 0.4 wt. % is added to eutectic alloy as well as hypereutectic alloy. Furthermore, refinement of primary Si in hypereutectic alloy was achieved by addition of 0.04 wt. % of phosphorus. The goal of this investigation is to determine the influence of combined addition of grain refiner and modifier on mechanical properties and qualitatively correlate with the microstructural changes. © 2015 Inderscience Enterprises Ltd.
Effect of L/D ratio on Al-Si functionally graded material cast through centrifuge technique
(2011) Aithal, K.; Narendranath; Desai, V.; Mukunda, P.G.
Functionally Graded Material (FGM) is a class of material wherein the properties and structure are varied intentionally from one side to the other side of the specimen. This paper describes the effect of L/D (Length to Diameter) ratio of the cast on cast Al-Si FGM. The present study uses Al-17%wt Si to cast FGM's. The cast is evaluated for Microstructure and Hardness all along the length of the specimen. Three L/D ratios: 0.5, 1.0, 1.5 were cast using the Centrifuge Technique. The microstructures showed that enrichment of primary Si was largest in 1.5 ratio compared to other two. Hardness value of the cast at the upper and lower region were examined and found that gradient of hardness was more in 1.5 case. High volume percentage of primary Si was nearly 26% in the upper region and a hypoeutectic structure in the lower region. � (2011) Trans Tech Publications.
Effect of L/D ratio on Al-Si functionally graded material cast through centrifuge technique
(2011) Kiran Aithal, A.S.; Narendranath; Desai, V.; Mukunda, P.G.
Functionally Graded Material (FGM) is a class of material wherein the properties and structure are varied intentionally from one side to the other side of the specimen. This paper describes the effect of L/D (Length to Diameter) ratio of the cast on cast Al-Si FGM. The present study uses Al-17%wt Si to cast FGM's. The cast is evaluated for Microstructure and Hardness all along the length of the specimen. Three L/D ratios: 0.5, 1.0, 1.5 were cast using the Centrifuge Technique. The microstructures showed that enrichment of primary Si was largest in 1.5 ratio compared to other two. Hardness value of the cast at the upper and lower region were examined and found that gradient of hardness was more in 1.5 case. High volume percentage of primary Si was nearly 26% in the upper region and a hypoeutectic structure in the lower region. Â© (2011) Trans Tech Publications.
Effect of low temperature annealing on the wear properties of NITINOL
(2016) Mukunda, S.; Naths, N.; Herbert, M.A.; Mukunda, P.G.
NiTi shape memory alloy is a wonder material that is a solution looking for problems. The material finds wide biomedical applications like endodontic files for root canal treatment and cardiovascular stents. This material has rendered the surgical procedure simple compared to that with the existing Stainless Steel (SS) or titanium ones. NiTi as an endodontic file would cause less discomfort to the patients in comparison to that with far stiffer SS or titanium ones. Here nearly equi-atomic 50:50 commercial NiTi rods were subjected to low temperature aging at 300 to 450�C. The wear resistance of the as-received and the heat-treated samples was studied using adhesive wear tests on hardened steel counter face. Abrasive wear tests were run against Alumina disc to simulate the working of endodontic drills and files against dental hard and soft tissues. The abrasive wear resistance is expected to be proportional to the Vickers Hardness of the material and is high for the 450�C heat-treated sample. A correlation between the mechanical properties and microstructures of this material is attempted. � Published under licence by IOP Publishing Ltd.
Effect of low temperature annealing on the wear properties of NITINOL
(Institute of Physics Publishing michael.roberts@iop.org, 2016) Mukunda, S.; Naths, N.; Herbert, M.; Mukunda, P.G.
NiTi shape memory alloy is a wonder material that is a solution looking for problems. The material finds wide biomedical applications like endodontic files for root canal treatment and cardiovascular stents. This material has rendered the surgical procedure simple compared to that with the existing Stainless Steel (SS) or titanium ones. NiTi as an endodontic file would cause less discomfort to the patients in comparison to that with far stiffer SS or titanium ones. Here nearly equi-atomic 50:50 commercial NiTi rods were subjected to low temperature aging at 300 to 450Â°C. The wear resistance of the as-received and the heat-treated samples was studied using adhesive wear tests on hardened steel counter face. Abrasive wear tests were run against Alumina disc to simulate the working of endodontic drills and files against dental hard and soft tissues. The abrasive wear resistance is expected to be proportional to the Vickers Hardness of the material and is high for the 450Â°C heat-treated sample. A correlation between the mechanical properties and microstructures of this material is attempted. Â© Published under licence by IOP Publishing Ltd.
Effect of process parameters on centrifugally cast Al-Si FGM
(2016) Kiran, A.S.; Desai, V.; Narendranath, S.; Mukunda, P.G.
Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation. � The Minerals, Metals & Materials Society 2016.
Effect of process parameters on centrifugally cast Al-Si FGM
(2013) Aithal, S, K.; Desai, V.; Narendranath, S.; Mukunda, P.G.
Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation.
Effect of process parameters on centrifugally cast Al-Si FGM
(Springer International Publishing, 2016) Kiran Aithal, A.S.; Desai, V.; Narendranath, S.; Mukunda, P.G.
Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation. Â© The Minerals, Metals & Materials Society 2016.
Effect of process parameters on centrifugally cast Al-Si FGM
(Minerals, Metals and Materials Society 184 Thorn Hill Road Warrendale PA 15086, 2013) Kiran Aithal, K.; Desai, V.; Narendranath, S.; Mukunda, P.G.
Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation.
Evolution of microstructure and hardness of AL-SI functionally graded material cast through centrifuge technique using hypereutectic and eutectic Al-SI
(2011) Kiran Aithal, A.S.; Desai, V.; Narendranath; Mukunda, P.G.
Functionally Graded Materials (FGMs) are a new class of inhomogeneous materials wherein the composition and the microstructure is varied to alter the material property within a component. The present study is to fabricate a Functionally Graded Al-Si in-situ material and to characterize. Al-Si alloys with 17wt%Si (hyper eutectic) and 11.7wt%Si (eutectic) have been used to fabricate Al- Si FGMsby centrifuge casting process. The microstructural characteristics and hardness profiles of these FGMs have been evaluated. The study shows the structure of Al-Si samples produced by this method show Hyper eutectic through Eutectic to Hypo eutectic structure along their depth. It also reveals that hardness of the sample and the silicon content decrease steeply along the depth of the sample.
Experimental and Analytical Based Investigations on Machinability of High-Chrome White Cast Iron Using CBN Tools
(Springer, 2015) Ravi, A.M.; Murigendrappa, S.M.; Mukunda, P.G.
High-chrome white cast iron (HCWCI) is one of the hardest metals used in the process and mining industries faces tough challenge in metal cutting. Focusing on this issue, influence of cutting parameters (e.g., cutting speed, depth of cut, feed rate) on machinability characteristics (e.g., cutting forces, surface roughness, material removal rate, machining power) of HCWCI has been investigated by experimentally and analytically using cubic boron nitride (CBN) cutting tools. Experimentation is carried out in conjunction with the Taguchi techniques and the influence of each cutting parameter of the process has been analyzed by analytical tools; analysis of variance, regression technique and artificial neural networks (ANNs). The study reveals depth of cut has the highest contribution on the cutting forces, and cutting speed on surface roughness and machining power. The confirmation test identifies both regression and ANN techniques are the most effective tools to evaluate machinability characteristics of HCWCI. Further, the CBN cutting tool exhibits excellent performance in machining of HCWCI. © 2014, The Indian Institute of Metals - IIM.
Experimental investigation on thermally enhanced machining of high-chrome white cast iron and to study its machinability characteristics using Taguchi method and artificial neural network
(Springer-Verlag London Ltd, 2014) Ravi, A.M.; Murigendrappa, S.M.; Mukunda, P.G.
Machining of hard-to-wear materials such as high-chrome white cast iron (HCWCI) and high-manganese steels is an uphill task when conventional route followed. Alternatively, thermally enhanced machining (TEM) can be used to minimize the tooling cost very effectively. This paper presents the detailed study of TEM of HCWCI in which the effect of cutting parameters and surface temperature of the stock material on machinability characteristics (cutting forces and surface roughness) are analyzed using ANOVA and artificial neural network (ANN). The experimental work was conducted to follow Taguchi techniques. HCWCI is finding newer applications in mining; mineral processing industries were the workpiece in the machining studies using cobalt-based cubic boron nitride insert tool. Localized heat was added at the tool-work interface which softens the metal and eases the machining operation. The influences of the control factors on the process responses have been analyzed using analysis of variance (ANOVA), and the results are correlated using ANN. Linear regression was used to establish the relation between the control parameters and the process responses. The results show that TEM causes easy shearing of the material, leading to the reduction in cutting forces with expected improvement in tool life and surprisingly good surface finish. The confirmation tests suggest both second-order regression and ANN which are better predictive models for quantitative prediction of TEM of HCWCI, and ANN is more accurate of the two. Also, it was proved that oxy-LPG flame heating is an economical option compared to laser-heated machining in hard turning process. © 2014 Springer-Verlag London.
Experimental studies of flow patterns of different fluids in a partially filled rotating cylinder
(Isfahan University of Technology, 2009) Mukunda, P.G.; Rao, S.; Kiran Aithal, A.S.; Shrikantha, S.R.
An attempt has been made to investigate the various parameters affecting the fluid behaviour, partially filled in a rotating cylinder. When the cylinder is rotating at 'high' speed, a liquid forms a hollow cylinder. Different patterns are observed in the fluids for the rotatioal speeds below a critical speed. This study should give us some insight into molten metal behaviour during centrifugal casting. An extensive experimental investigation is required to obtain an appropriate functional relationship by knowing and understanding some dimensionless parameters. Here the effect of dimensionless parameters ? (which is 2 g/?2d, where g, ? and d denotes gravitational acceleration, container rotation rate and inner diameter of liquid cylinder) and G (number of times the gravity) was studied as variation of rotation speed, viscosity and aspect ratio of the mould.
Experimental study on rate of solidification of centrifugal casting
(2010) Madhusudhan; Narendranath, S.; Mohan Kumar, G.C.M.; Mukunda, P.G.
Centrifugal casting is a process of producing casting by causing molten metal to solidify in rotating moulds. The quality of the final casting is mainly depending upon the flow pattern of the molten metal and rate of solidification, which in term depends upon the rotational speeds of the mould. Experiments have been conducted by rotating a partially filled horizontal axis cylinder at different rotational speeds and also at different fluid temperatures. Cooling rates of the liquids were observed at different rotational speeds, which depend upon the relative movement between the inner surface of the rotating mould and the fluid. This study gives us some insight into the effect of rotational speed on solidification rate of centrifugal casting. Micro structures of centrifugally cast Al-12 Si castings are also exhibit the same behavior for different rotational speeds.
Inference of optimal speed for sound centrifugal casting of Al-12Si alloys
(2011) Rao, Agari, S.; Mukunda, P.G.; Rao, S.S.; Sudhakar, K.G.
True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds is discussed.
Inference of optimal speed for sound centrifugal casting of Al-12Si alloys
(2011) Rao, S.; Mukunda, P.G.; Rao, S.S.; Sudhakar, K.G.
True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds is discussed.
Inference of optimal speed for sound centrifugal casting of tin
(Metallurgical Society of CIM, 2009) Mukunda, P.G.; Rao, S.; Rao, S.S.
During centrifugal casting when a mould is rotated at low and very high speeds, defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guessing but based on experience. The defects in the casting are mainly due to the behaviour of the molten metal during the teeming and solidification process. The motion of molten metal at various speeds and its effect during casting are addressed in this paper. Tin is taken as an experiment fluid and its performance during various rotational speeds is discussed. The microstructures and hardness of all the castings are also investigated. © Canadian Institute of Mining, Metallurgy and Petroleum.