Qualification: 
Ph.D, M.Tech, BE
Email: 
m_govindaraju@ch.amrita.edu

Dr. Govindaraju M. currently serves as Assistant Professor (Sr. Gr.) at the Department of Mechanical Engineering, Amrita School of Engineering, Coimbatore Campus. His areas of interest include Metallurgy & Material Science.

Thrust Area of Research

  • Materials and processing - Composites

Awards and Achievements

  • Received the University Second Rank in the undergraduate course, B. E. Metallurgical Engineering, from University of Madras, in the year 2001.
  • Received "Best Paper Presentation Award" in IEEE - International conference on advances Engineering and Technology - 2012 (ICAET-2012) organized at EGS Pillay Engineering College, Nagapattinam, Tamil Nadu on March 28 - 29, 2012, for the paper titled "Corrosion Behavior of Friction Welded AZ91D Magnesium Alloy in Carbonate Solution"

Teaching/Research Interests

Major Subjects Taught

  • Advanced materials and processing
  • Advances in Material Science and Characterization
  • Composite Materials and Processes

Research Interests

  • Materials Processing
  • Advanced Material and Material Joining
  • Powder Metallurgy

Publications

Publication Type: Journal Article

Year of Publication Title

2021

V. Pamula, Kalyan, K. Pavan, Vaira Vignesh R., and Dr. Govindaraj M., “Development and characterization of aluminum matrix composite reinforced with continuous stainless-steel fibers”, Materials Today: Proceedings, 2021.[Abstract]


Driven by energy conservation and environmental protection, present-day engineering applications focus on the effective usage of fossil fuels. Hence, industrial sectors perform extensive research on light-weighting of structures to improve efficiency. In this study, the aluminum matrix composite (AMC) is fabricated by reinforcing continuous stainless-steel (SS 304) fibers. The fabricated AMC is examined for its mechanical, metallurgical, and tribological properties. The results indicate a 6% enhancement in ultimate tensile strength, a 73% enhancement in hardness, and a 33% enhancement of wear resistance in developed AMC.

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2021

N. Udayan, Srinivasan, M. V., Vaira Vignesh R., and Dr. Govindaraj M., “Elimination of casting defects induced by cold box cores”, Materials Today: Proceedings, 2021.[Abstract]


One of the challenges of foundry industries is rejection of casting caused by porosity defects. Of the many factors, proper selection of core manufacturing process has higher impact on the reduction of porosity defects in castings. Cold box core making processes widely used by foundry industries to produce cores because of its good productivity and ability to produce complex designed cores. However, the probability of porosity defect in castings produced using cold box cores is higher than that of other processes. Globally, research is being carried out to solve the porosity defects in castings. However, complexity of the process and involvement of more process variables necessitate identification of root causes of the defects. This work aims at resolving the porosity defect in castings, when cold box core is used. Cores produced by furan core making process, which rarely results in porosity defects, was set as standard for testing the effectiveness of cores produced by cold box core making process. The results indicate that considerably high nitrogen content in the charge raw material in secondary iron making foundries enables reaction of metal with core (binder). Consequently, porosity arises in castings. The remedial measures to control the nitrogen content ensured casting rejections less than 7% in the foundry.

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2021

P. Kalyan Kota, Dr. Govindaraj M., and Vaira Vignesh R., “Metallurgical Characterization and Mechanical Properties of Solid-Liquid Compound Casting of Aluminum Alloy – Steel Bimetallic Materials”, Metals and Materials International (Accepted), 2021.

2020

G. M Keshav, Hemchandran, C. G., Dharsan, B., Pradhin, K., R Vignesh, V., and Dr. Govindaraj M., “Manufacturing of continuous fiber reinforced sintered brake pad and friction material”, Materials Today: Proceedings, 2020.[Abstract]


Copper-based brake pad material is fabricated by powder metallurgy methodology. The developed brake pad material has steel fibers and fly ash as reinforcement to increase the strength and hardness. A methodical approach is followed, where the microstructure is obtained and subsequently the micro hardness values were obtained. After which, wear test is conducted considering various parameters including sliding velocity, normal loads. The tribological parameters namely wear rate and coefficient of friction are evaluated. The wear mechanism of the developed material is deduced from advanced metallurgical characterization. The material is optimized for maximizing the performance by permuting different composition of materials and orientations of matrices.

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2020

A. Joe Alex, Dr. Padmanaban R., and Dr. Govindaraj M., “Effect of Fe particles on the microstructural evolution and mechanical properties of friction welded Al-Cu components”, Australian Journal of Mechanical Engineering, pp. 1–11, 2020.[Abstract]


Metals like aluminium (Al) and copper (Cu) are excessively used in electrical, automobile, nuclear, and structural applications because of their desirable electrical and mechanical properties. Joining of components made of pure Al and Cu is one of the challenging areas of research, because of the rapid oxidation characteristics of Al and intense formation of Al-Cu intermetallics in the joint interface. The existing welding techniques such as laser welding, metal inert gas welding, and arc welding have hardships in the development of joint between Al and Cu with desirable metallurgical and mechanical properties. Friction welding is a solid-state joining technique that utilises the frictional heat to develop the joint between the materials at relatively low temperatures. In this study, the effect of friction welding parameter on the microstructure and mechanical properties of friction welded pure Al and Cu were studied. Besides, the microstructural evolution in friction welding Al and Cu with Fe particle reinforcement was analysed. The elemental composition and phases were analysed using energy dispersive x-ray spectroscopy and x-ray diffraction analysis. The microstructural analysis revealed that Fe particles reduced the formation of Al-Cu intermetallic phases at the joint interface.

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2020

A. K. Raghav, Vaira Vignesh R., Kalyan, K. Pavan, and Dr. Govindaraj M., “Friction Welding of Cast Iron and Phosphor Bronze”, Journal of The Institution of Engineers (India): Series C, vol. 101, no. 2, pp. 347–354, 2020.[Abstract]


There is sometimes a need to fabricate machine parts that have the best properties of multiple materials while being economical at the same time. A prime example of such a scenario is with gears. Gears made out of cast iron are a poor choice because cast iron has poor impact resistance and is vulnerable to corrosion. The addition of phosphor bronze as an annulus to the cast iron hub in a composite gear provides the gear with those valuable resistances along with a superior intermeshing with mated gears. However, joining dissimilar materials such as cast iron to phosphor bronze is challenging when conventional welding techniques are employed. To overcome it, applying friction welding to join cast iron to phosphor bronze is focused in this thesis. The obtained results are analyzed and optimized for this particular combination of materials to facilitate their use in gears. The results show that there is an increased accumulation of graphite at the weld joints between cast iron and phosphor bronze for trials at higher (rotational) welding speeds, which leads to less favorable mechanical properties. At lower welding speeds, sound joints with acceptable mechanical and metallurgical properties were obtained.

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2020

M. Abdul Hadi Baig, Vaira Vignesh R., Dr. Padmanaban R., and Dr. Govindaraj M., “Characterization of AA5052-ZrO2 and AA5052-SiO2 Surface Composites Fabricated by Friction Stir Processing”, Songklanakarin Journal of Science and Technology. (Accepted) , 2020.

2020

R. K. Kannan, Vaira Vignesh R., and Dr. Govindaraj M., “Development and Tribological Characterization of Fly Ash Reinforced Iron based Functionally Gradient Friction Materials”, Engineering Review. (Accepted), 2020.

2020

M. B Bharathi, Vaira Vignesh R., Dr. Padmanaban R., and Dr. Govindaraj M., “Effect of friction stir processing and heat treatment on the corrosion properties of AZ31 alloy”, Australian Journal of Mechanical Engineering, pp. 1–10, 2020.[Abstract]


Magnesium alloys are widely used to lightweight the components in the automobile, aerospace, and electronics industries because of their low density and high specific strength. However, factors like low ductility, low mechanical strength, and high corrosion rate restrict the extensive use of the material. To utilise the alloy with improved mechanical and corrosion properties, friction stir processing followed by heat treatment was performed. The study explored the effect of ageing temperature and ageing time on the microstructure, mechanical and corrosion properties of friction stir processed AZ31 alloy. The results indicate that friction stir processing at TRS of 1200 rpm and TTS of 60 mm/min, followed by heat treatment augments the corrosion resistance of AZ31 alloy.

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2020

Dr. Govindaraj M., Chakkingal, U., Kalvala, P. Rao, Vaira Vignesh R., and Balasubramanian, K., “Investigations on the Creep behavior of friction-stir-processed magnesium alloy AE42”, Journal of Materials Engineering and Performance, vol. 29, pp. 3172–3182, 2020.[Abstract]


Magnesium alloy AE42 is a candidate material for high-temperature applications. However, as-cast AE42 alloy exhibits poor high-temperature creep properties because of the microstructure that shows a continuous network of b-Mg17Al12 and Al-RE precipitates along the boundaries of coarse a-Mg grains. In the current work, friction stir processing technique was adopted to refine the coarse as-cast structure of the AE42 alloy and break up the continuous network of b-Mg17Al12 and Al-RE precipitates. The creep properties of the parent material and friction-stir-processed specimens were determined by impression creep test at 150, 175, 200, 225 and 250 C. The results demonstrated that the presence of fragmented precipitates and the elimination of continuous network structure improved the creep resistance of the AE42 alloy. The metallurgical analysis revealed that no new precipitates were formed after friction stir processing and creep testing. From the data, it can be concluded that friction stir processing of AE42 alloy can lead to an increase in service temperatures from 150 to 225 C.

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2020

Dr. Govindaraj M., Megalingam, A., Murugasan, J., Vaira Vignesh R., Kota, P. Kalyan, A Ram, S., Lakshana, P., and V Kumar, N., “Investigations on the tribological behavior of functionally gradient iron-based brake pad material”, Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, vol. 234, no. 12, pp. 2474–2486, 2020.[Abstract]


In this study, a functionally gradient iron-based brake pad material was developed and the tribological behavior was studied. The functionally gradient specimen had more copper near the base plate and more abrasives towards the top, which provides excellent joint strength and serves the purpose of braking, respectively. The layers had a hybrid composition of metallic materials (Fe, Cu), and abrasives (silicon carbide and aluminum oxide) to improve the strength, wear resistance, and toughness. Graphite was added to stabilize the specimen's thermal and friction characteristics at high temperature. The microstructure, wear rate, and friction coefficient of the functionally gradient specimen and the conventionally sintered specimen were evaluated. The results indicate that the wear resistance of the functionally gradient specimen is higher than the wear resistance of conventional specimen.

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2020

Vaira Vignesh R., Dr. Padmanaban R., Kovukkal, M. D., and Dr. Govindaraj M., “Research and Development in Magnesium Alloys for Industrial and Biomedical Applications: A Review”, Metals and Materials International, vol. vol. 26, pp. 409-430, 2020.[Abstract]


Abstract: The work reviews the research and development status of magnesium alloy, with more attention to the methodologies and technologies adopted to improve the properties of AZ91 alloy. The drive force of utilizing magnesium alloys for automotive and biomedical application is light weightiness and biocompatibility respectively. However, the softness and high activity of magnesium alloys result in high wear and high corrosion rate respectively. One of the essential factors influencing the properties of magnesium alloy is its microstructure. Consequently, the grain size, morphology and distribution of phase constituents influence the properties of magnesium alloys. The modification of microstructure through processing route (hot working and cold working), heat treatment, and alloying elements improves the mechanical, corrosion, biocompatible, and tribological properties of magnesium alloys. Besides microstructural modification processes, addition of reinforcements, and coatings improves the properties of magnesium alloys. This article emphasis on the recent research on the technologies to improve the microstructure, hardness, tensile strength, ductility, yield strength, wear resistance, and corrosion resistance of magnesium alloy AZ91. Moreover, this review addresses the key issues hindering the applications of magnesium alloys for structural and biomedical applications. Graphic Abstract: [Figure not available: see fulltext.]. © 2019, The Korean Institute of Metals and Materials.

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2020

Vaira Vignesh R., Dr. Padmanaban R., and Dr. Govindaraj M., “Synthesis and Characterization of Magnesium Alloy Surface Composite (AZ91D - SiO2) by Friction Stir Processing for Bioimplants”, Silicon, vol. 12, 2020.[Abstract]


Magnesium shows potential for bioimplant applications because of its high biocompatibility and equivalent bone strength. However, the high corrosion rate of magnesium and magnesium alloys in the physiological environment results in the rapid evolution of H2 gas, which is lethal to the neighboring tissues. With an intention to reduce the corrosion rate, magnesium alloy AZ91D is reinforced with nanophase SiO2 to fabricate surface composite by friction stir processing. The metallurgical characterization reveals the refinement of grains, fine dispersion of β phase and nanophase SiO2 in the composite matrix. The surface characterization of the corrosion products depicts the formation of an adherent layer of corrosion products that are rich in calcium hydroxyapatite and calcium-magnesium phosphate. The combined consequence of metallurgical and corrosion phenomenon reduces the corrosion rate, aids bone growth, and augments implant-bone integration. The results demonstrate that AZ91D-SiO2 composite is an effective material for bioimplant applications. [Figure not available: see fulltext.]. © 2019, Springer Nature B.V.

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2019

T. Satish Kumar, Shalini, S., Dr. M. Ramu, and Dr. Govindaraj M., “Characterisation of AZ31/ZrO2 composites produced via stir casting”, Materials Research Express, vol. 6, no. 11, p. 1165d1, 2019.[Abstract]


AZ31Magnesium alloy reinforced with different vol% of ZrO2 particle composites have been produced by stir casting process. The effect of ZrO2 vol% on microstructure and mechanical properties of AZ31 alloy has been studied. Significant refinement in grain size was observed in ZrO2 reinforced composites. The hardness, Proof strength and tensile strength of the AZ31/ZrO2 composites increased with increase in addition of ZrO2 particle. However the ductility of the composite sample decreased with the addition of ZrO2 particles. The tensile fractured surface was analyzed using SEM to find the fracture mechanisms.

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2019

A. Aravind, Vaira Vignesh R., Dr. Padmanaban R., and Dr. Govindaraj M., “Study on the Mechanical and Corrosion behavior of AA 5052 Tailor Welded Blanks Fabricated using Friction Stir Welding”, Journal of Materials and Environmental Sciences, vol. 10, no. 7, pp. 624-636, 2019.[Abstract]


Friction stir welding is a unique and promising technique to produce joints with desirable mechanical strength and properties. Tailor welded blanks are processed by joining two plates of dissimilar thickness with relatively less mass. As tailor welded blanks offer higher strength at a minimal weight, the material consumption decreases making it more economically viable. In this study, the influence of the critical friction stir welding process parameters namely tool traverse speed, tool rotation speed and thickness mismatch ratio on the microhardness, corrosion rate, tensile strength (before and after corrosion) of AA5052 tailor welded blanks are investigated. The friction stir welding trials were conducted based on Box Behnken design at three levels of process parameters. Hybrid-Radial Basis Function based models were developed to explore the effect of process parameters on the properties. The optimum process parameters to obtain high tensile strength in AA5052 tailor welded blanks was found to be tool traverse speed of 60mm/min, the tool rotation speed of 850rpm and thickness mismatch ratio of 0.9.

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2019

Vaira Vignesh R., Dr. Padmanaban R., Dr. Govindaraj M., and G. Priyadharshini, S., “Investigations on the corrosion behaviour and biocompatibility of magnesium alloy surface composites AZ91D-ZrO2 fabricated by friction stir processing”, Transactions of the Institute of Metal Finishing (The International Journal of Surface Engineering and Coatings), vol. 97, no. 5, pp. 261-270, 2019.[Abstract]


In the current study, friction stir processing was applied as a methodology to produce surface composites of AZ91D magnesium alloy with ZrO2 particles. Microstructural evolution, microhardness profile and corrosion behaviour of the developed surface composite were analysed. The results indicate that the combined effect of friction stir processing and reinforcement of ZrO2 reduced the grain size, and fragmented and dispersed the secondary phases. The fine dispersion of ZrO2 particles contributed to the enhancement of cumulative surface potential, and hence the corrosion resistance of the developed surface composite. The analysis of post-corrosion test specimens revealed the formation of corrosion products that had similar composition to that of hydroxyapatite. The formation of such corrosion products is beneficial, as it contributes to corrosion resistance (stable and adherent layer) and biocompatibility. © 2019, © 2019 Institute of Materials Finishing Published by Taylor & Francis on behalf of the Institute.

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2019

Dr. Govindaraj M., Vaira Vignesh R., and Dr. Padmanaban R., “Effect of heat treatment on the microstructure and mechanical properties of the friction stir processed AZ91D magnesium alloy”, Metal Science and Heat Treatment, vol. 61, no. 5, pp. 311–317, 2019.[Abstract]


We study the microstructure and mechanical properties of friction stir processed AZ91D cast magnesium alloy under various conditions of heat treatment. It is shown that, in the initial as-cast state, the structure of the alloy contained a continuously networked β-phase with an average grain size of 150 μm. The friction stir processed (FSP) specimens had an average grain size of 12 μm and smooth grain boundaries. The subsequent heat treatment of the FSP specimens at various temperatures between 150°C and 250°C led to the appearance of numerous particles of the β-phase. The FSP specimens heat-treated at 200°C had finer grains, a larger number of fine particles of the β-phase, and better mechanical properties than any other specimens.

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2019

Vaira Vignesh R., Dr. Padmanaban R., Dr. Govindaraj M., and G. Priyadharshini, S., “Mechanical properties and corrosion behaviour of AZ91D-HAP surface composites fabricated by friction stir processing”, Materials Research Express, vol. 6, no. 8, 2019.[Abstract]


The biomedical applications of magnesium alloy AZ91D are limited because of the dendritic β-Mg17Al12 phase, which degrades the mechanical properties and corrosion resistance. To overcome this, friction stir processing is implemented to fabricate surface composite of AZ91D with hydroxyapatite as reinforcement. This results in refinement of grains and fragmentation of the β phase with homogeneous dispersion of hydroxyapatite in the composite. The combined effect of reinforcement of hydroxyapatite and fragmentation of the β phase resulted in simultaneous improvement in mechanical and corrosion properties. The various phases, surface morphology, and composition of the developed composite are analyzed using a transmission electron microscope and a scanning electron microscope before and after corrosion studies. The mechanism behind the improvement in the property of the developed composite is correlated with the characterization results. © 2019 IOP Publishing Ltd.

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2019

Vaira Vignesh R., Dr. Padmanaban R., and Dr. Govindaraj M., “Investigations on the surface topography, corrosion behavior, and biocompatibility of friction stir processed magnesium alloy AZ91D”, Surface Topography: Metrology and Properties, vol. 7, no. 2, 2019.[Abstract]


Magnesium and its alloys have been identified as potential biodegradable implant materials for orthopaedic applications considering their bone equivalent density, biocompatibility, and biodegradability. However, the rapid corrosion rate of magnesium alloys in the physiological environment is a severe problem. This study attempts to simultaneously improve the microhardness and reduce the corrosion rate of AZ91D alloy by friction stir processing. Magnesium alloy AZ91D is friction stir processed by varying the process parameters namely tool rotation speed and tool traverse speed. The effects of friction stir processing parameters on the microstructural evolution, surface topography, microhardness, and corrosion rate of AZ91D alloy are investigated using the hybrid models, which are developed by integrating the quadratic function and radial basis function. The results indicate that the optimum process parameters for friction stir processing of AZ91D alloy is 750 rpm and 45 mm min-1. Cytotoxicity test revealed that the biocompatibility of friction stir processed AZ91D alloy is in good agreement with the biocompatibility of the AZ91D alloy. © 2019 IOP Publishing Ltd.

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2018

K. Balasubramanian and Dr. Govindaraj M., “Simplification of High Temperature High Pressure Equipment and Technique for Advanced Materials Processing”, Materials Today: Proceedings, vol. 5, pp. 16158 - 16164, 2018.[Abstract]


Combining pressure and temperature for material processing remains a challenge; if combined and applied, the potential is high for advanced material processing. In addition to advanced powder materials processing and syntheses, complicated fabrications such as joining of dissimilar materials for aerospace, pressure assisted sintering are possible with combined high pressure high temperature technique. In this study, a simplified version of high pressure high temperature equipment is designed and built. The new system eliminates/simplifies complicated and costly equipment such as hot isostatic press. The system has capacity to apply maximum gas pressure of 100 MPa and attain temperature up to 1050 °C. In addition, different processing atmospheres (inert, reducing and vacuum) are possible in the system. Special purpose jigs and fixture are designed to accommodate various processes of synthesis, sintering, joining, hot isostatic pressing and densification etc. Sintering of powder compacts and loose powder were carried out to prove the system.

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2017

Dr. Govindaraj M., Ananthakrishnan, R., Khan, N., Magar, M., Nayakwade, C., Bardepur, R., and Balasubramanian, K., “Design of Special Adapters and Furnace for Hot Helium Leak Testing of Plasma Physics Components”, Materials Today: Proceedings, vol. 4, pp. 3652 - 3658, 2017.[Abstract]


Pressure and leak testing are the two most important quality control steps followed at the end of fabrication for the components of ITER, Plasma physics and its related fields. In the current project, an elaborate procedure and facilities for the hot helium leak testing has been established. A conventional vacuum furnace has been modified to accommodate the global leak testing of high technology Plasma physics and ITER components. Special adaptors were designed and fabricated for hot helium leak testing under pressure mode. These adapters have a transfer tube which can be used to carry the helium in and out of the component under testing, without disturbing the vacuum level in the furnace chamber. These adapters were fitted to the 2000 mm long ITER components and tested successfully at the operating temperature of 200 °C. High end vacuum fittings and sealing mechanisms were installed on the mating surfaces of the furnace, to achieve high vacuum in the order of 10-5 mbar. Provisions have been given to address the challenge of local leak detection by installing a Wilson seal to move from one end of the component to other end; in such a way that one side of the seal is at 200 °C temperature in vacuum, other side is at room temperature in atmospheric pressure. This enables to locate the leak by moving the component form one end to other.

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2015

B. Kiran Babu NADIKUDI, DAVIDSON, M. J., AKASAPU, N. Rao, and Dr. Govindaraj M., “Formability analysis of dissimilar tailor welded blanks welded with different tool pin profiles”, Transactions of Nonferrous Metals Society of China, vol. 25, pp. 1787 - 1793, 2015.[Abstract]


An attempt has been made to study the tailor welded blanks (TWBs) made by friction stir welding (FSW) with five different tool pin profiles. The formability of welded blanks was evaluated at constant FSW process parameters. It has been found that the welded blanks with square pin profile tool produced better formability properties as compared to other tool pin profiles. It was found that the pulsating action of the square pin profile is said to be the reason for this improvement. A microstructural evaluation performed on the blanks revealed that the stir zone created by taper cylindrical and stepped cylindrical tools was less homogeneous than that of the square tool, resulting in less formability. The limiting dome height (LDH) of square pin profile tool was found to be 14 mm while those of taper cylindrical and stepped cylindrical tools are 12.5 mm and 12.4 mm, respectively. More »»

2015

Dr. Govindaraj M., K, B., Chakkingal, U., and Rao, K., “Making ceramic- metal composite material by friction stir processing”, IOP Conference Series: Materials Science and Engineering, vol. 73, p. 012064, 2015.[Abstract]


Pressure and leak testing are the two most important quality control steps followed at the end of fabrication for the components of ITER, Plasma physics and its related fields. In the current project, an elaborate procedure and facilities for the hot helium leak testing has been established. A conventional vacuum furnace has been modified to accommodate the global leak testing of high technology Plasma physics and ITER components. Special adaptors were designed and fabricated for hot helium leak testing under pressure mode. These adapters have a transfer tube which can be used to carry the helium in and out of the component under testing, without disturbing the vacuum level in the furnace chamber. These adapters were fitted to the 2000 mm long ITER components and tested successfully at the operating temperature of 200 °C. High end vacuum fittings and sealing mechanisms were installed on the mating surfaces of the furnace, to achieve high vacuum in the order of 10-5 mbar. Provisions have been given to address the challenge of local leak detection by installing a Wilson seal to move from one end of the component to other end; in such a way that one side of the seal is at 200 °C temperature in vacuum, other side is at room temperature in atmospheric pressure. This enables to locate the leak by moving the component form one end to other. More »»

2014

A. C. Umamaheshw Rao, Vasu, V., Dr. Govindaraj M., and Srinadh, K. V. Sai, “Influence of Cold Rolling and Annealing on the Tensile Properties of Aluminum 7075 Alloy”, Procedia Materials Science, vol. 5, pp. 86 - 95, 2014.[Abstract]


The present work reports the effect of cold rolling and subsequent annealing at different temperatures on the tensile behavior of 7075 aluminum alloy. The cold rolling has been carried out in between 12-28% and was annealed at various temperatures in the range of 225-325°C for 5min. Hardness test and tensile tests were carried out to evaluate tensile and ductility parameters. All the tensile specimens were taken from the transverse direction of the cold rolled and annealed sample. It has been observed that the cold rolling has a significant effect on the increase in the yield strength and lowering the ductility of the alloy. It was also observed that the cold rolled samples, annealed at 275°C showed lower total elongation in the transverse direction, while for samples annealed at high temperatures the total elongation values were observed to be high. In general it is also observed that formability (UTS/σy) of cold worked and annealed samples were high when compared to cold worked samples. Fractographic study using SEM analysis was carried out for all the conditions. Failure took place by formation of dimples indicating ductile fracture More »»

2014

B. Kiran Nadikudi, Davidson, D. M. Joseph, A., R., K., B., and Dr. Govindaraj M., “Effect of differential heat treatment on the formability of aluminium tailor welded blanks”, Materials and Design, vol. 55, pp. 35–42, 2014.[Abstract]


Tailor welded blanks (TWBs) are blanks that are tailor made to suit the required function. They are made by joining blanks of different thicknesses, materials, coatings, etc. The forming behaviour of such TWBs will be different from the conventional blanks, as TWBs with different strength levels will be subjected to the same forming loads but will result in unequal deformation values. The present work is aimed at studying the formability behaviour of TWBs of two different materials namely AA6061 and AA2014. The blanks were made by friction stir welding process at different rotational speeds, welding speeds and tool tilt angles on a vertical head milling machine. The formability of the TWBs and the base materials has been studied before and after solution heat treatment and analysed with the help of Limiting Dome Height (LDH) test. A differential heat treatment approach has been followed, which is unique in this work. From the results, it was found that the formability of heat treated TWBs were higher than those of base materials and untreated TWBs. More »»

2014

Dr. Govindaraj M., Balasubramanian, K., Chackingal, U., and K. Rao, P., “Effect of Severe Plastic Deformation and Heat Treatment on Toughness of Magnesium Alloys”, Procedia Materials Science, vol. 6, pp. 37 - 42, 2014.[Abstract]


Severe plastic deformation by friction stir processing and subsequent heat treatment was carried out on cast magnesium alloys AZ91D and AE42 to obtain ultrafine precipitates size and enhance the toughness. The resultant toughness values were analyzed and correlated with microstructure. Toughness of magnesium alloys AE42 and AZ91D was doubled by friction stir processing followed by heat treatment. Ultrafine precipitates in the order of 0.1 to 0.5 micron were formed by the processing + heat treatment. Networked coarse structure was completely eliminated from cast alloys. Friction stir processing acted as severe plastic deformation and the inbuilt energy and dislocations due to the same was reason for the numerous ultrafine precipitates nucleation during the heat treatment. The precipitates were homogenously distributed in matrix. More »»

2013

Dr. Govindaraj M. and K, B., “Dissimilar Joining of Heat Treatable Copper alloy with Stainless Steel”, International Journal of Advanced Materials Manufacturing and Characterization, vol. 3, pp. 67-71, 2013.[Abstract]


A B S T R A C T Precipitation hardening stainless steel and copper chromium zirconium alloy are age hardening materials used in ITER, aerospace and plasma physics. Dissimilar vacuum brazing was carried after in solutionised condition to retain the maximum possible mechanical properties of both the alloys. A novel differential temperature vacuum brazing method coupled with heat treatment was evolved for the same and proved by experiments. The brazing experiment was carried out with a special heater + furnace assembly where the precipitation hardening stainless steel part was at 1040°C and copper chromium zirconium alloy part was at 980°C which where matching with solutionising temperature of both the alloys. Immediately after brazing (brazing cycle = solutionising cycle) the samples were quenched from brazing temperature by inert gas. Filler material used in the study was gold-18% nickel alloy. Aging treatment was carried out at 496°C for 4 hours after brazing. Parameters for maximum joint strength and maximum mechanical properties of precipitation hardening stainless steel and copper chromium zirconium alloy were arrived and discussed in detail. Resultant joint strength, microstructure and hardness results were included More »»

2012

K. Subbaiah, Manivasagam, G., Dr. Govindaraj M., and Rao, S. Koteswara, “Mechanical Properties of Friction Stir Welded Cast Al–Mg–Sc Alloys”, Transactions of the Indian Institute of Metals, vol. 65, 2012.[Abstract]


Friction Stir (FS) welding promises joints with low porosity, fine microstructures, and low vaporization of volatile elements compared with conventional welding techniques. FS weld was carried out on Vacuum Induction Melted 5 mm thick cast Aluminum–Magnesium–Scandium (Al–Mg–Sc) alloy plates. Microstructural evaluation revealed that due to FS welding, fine and fragmented dynamically recrystallized grains have been formed in the weld nugget. Tensile fracture occurred out side the weld zone. The tensile strength of the welded joint is more than the cast base metal. The hardness of the FS welded joint is less than the hardness of the cast base metal. The minimum hardness was located on the retreating side of the weld. These results clearly show that FSW process is amenable to join cast Al–Mg–Sc alloy. More »»

Publication Type: Book Chapter

Year of Publication Title

2021

Vaira Vignesh R., Dr. Padmanaban R., Dr. Govindaraj M., and G. Priyadharshini, S., “Corrosion protection of Magnesium Alloys in Simulated Body Fluids using Nanophase Al2O3”, in Corrosion Protection at the Nanoscale, (Accepted), Micro and Nano Technologies, Elsevier, 2021.[Abstract]


Friction stir processing is applied to fabricate magnesium alloy AZ91D surface composite reinforced with nanophase Al2O3 particles. The refined microstructure in the developed surface composite is induced by nanophase Al2O3 particles and recovery–recrystallization phenomenon by friction stir processing. The results of electrochemical corrosion test and immersion corrosion test reveal that the corrosion rate of the developed surface composite decreased in simulated body fluids. The study originally reports that the homogeneous dispersion of nanophase Al2O3 particles and formation of an adherent layer of corrosion products (calcium hydroxyapatite and calcium-magnesium phosphate) in the developed surface composite decrease the corrosion rate. Besides, the formation of these corrosion products that mimic the bone matrix would support bone growth and promote integration of implant bone.

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2019

S. R., Dr. M. Ramu, Dr. Govindaraj M., Karthikeyan K., and Veerasamy, S., “Performance Evaluation of Adhesive Spur Gear with the Influence of Properties of Adhesive”, in Advances in Computational Methods in Manufacturing, 2019, pp. 923-931.[Abstract]


The effect of adhesive properties on performance of spur gear made of adhesive system referred to as adhesive spur gear is investigated. In addition, the repair ability and reusability of adhesive spur gear towards sustainability are also investigated. Two-part epoxy adhesive system constituting resin and hardener was used to fabricate spur gear samples. In order to modify adhesive properties, the hardener to resin ratio was varied. The repair ability and reusability of spur gear made by the adhesive system were checked by breaking a few teeth of the adhesive spur gears and repaired by adhesive. The repaired gears were tested and compared with the performance of actual spur gears made of adhesive. The gears were tested by a gear test rig developed indigenously. The performance of the gears with different hardener to resin ratios was evaluated by monitoring the number of cycles. The results show that the number of cycles increases with decrease in hardener to resin ratio. This is due to the better strength of the adhesive system with the resin-rich formulation. There is not much difference in performance between repaired gear and the corresponding actual gear. This ensures the sustainability of adhesive gears over conventional polymer gears.

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Publication Type: Conference Proceedings

Year of Publication Title

2020

R. K. Kannan, Dr. Govindaraj M., and Vaira Vignesh R., “Development of Fly Ash based Friction Material for Wind Turbines by Liquid Phase Sintering Technology”, Journal of Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology (Published Online). 2020.[Abstract]


Fly ash based sintered materials are identified as potential brake pad materials for wind turbines. However, fly ash based friction materials fabricated through conventional techniques results in more porosity and undesirable tribological properties. This study attempts to develop liquid phase sintering technology for fly ash using Cu as a liquid phase sintering agent. The study presents a comprehensive analysis of the evolution of microstructure, microhardness, and tribological performance of the specimens sintered in Argon and Air environment.

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2019

P. Kesava Sai Srujan, Kaka, H. Krishna, Vaira Vignesh R., Kalyan, K. Pavan, Dr. Padmanaban R., and Dr. Govindaraj M., “Cost-effective manufacturing of piping components with consistent quality through continuous furnace brazing”, AIP Conference Proceedings, vol. 2128. AIP Publishing, p. 030006, 2019.[Abstract]


India is witnessing an incessant expansion in the establishment of manufacturing plants for the production of engineering components by local and foreign players. Adoption of innovative and advanced manufacturing methods improve components’ quality, meet international standards, increase export potential, and achieve “Make in India”. In the pressure vessel and compressor domain, development of suitable brazing technologies for joining piping components will result in properties (joint strength, fatigue strength, wear resistance, corrosion resistance) superior to conventionally welded piping components. For high-volume production, the most common equipment used for brazing is a continuous-type atmosphere-controlled furnace. The cost reduction realized is significant, as this technology is based on the continuous production line. Other advantages include consistency in quality and possibility of automation. This will secure a position for Indian Engineering Component Manufacturers at par with North American, European and Japanese counterparts. In this work, pipe components that are conventionally joined by welding process and amenable for brazing, are identified in terms of design and material (mainly steel based). Steel pipe components are joined by furnace brazing (continuous type) using copper alloy based filler material. The optimum brazing process parameters are established based on the obtained joint strength, corrosion resistance, and leak tightness.

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2019

R. K Kannan, Vaira Vignesh R., Kalyan, K. Pavan, Murugesan, J., Megalingam, A., Dr. Padmanaban R., and Dr. Govindaraj M., “Tribological performance of heavy-duty functionally gradient friction material (Cu-Sn-Fe-Cg-SiC-Al2O3) synthesized by PM route”, AIP Conference Proceedings, vol. 2128. AIP Publishing, p. 020004, 2019.[Abstract]


Copper-based sintered materials with ceramic reinforcements and solid lubricants are identified as potential brake pad materials for heavy-duty applications (wind turbine), because of their prime thermal and tribological properties. However, the presence of ceramic reinforcement reduces the joint strength between the brake pad and the substrate material. The reduction in joint strength may lead to catastrophic failure of the braking system in the wind turbines when brakes are applied suddenly. This study attempts to synthesize functionally gradient material (FGM), which has a gradient composition of the ceramic particles along the traverse section. FGM was synthesized layer by layer deposition of Cu, Fe, Sn, Cg, SiC, Al2O3 powders with gradient composition. Microstructure, phases, and microhardness of the specimen were analyzed. Tribological studies were performed to assess the wear rate and friction coefficient of the FGM at various loads. The surface morphology of the worn surface was characterized using field emission scanning electron microscope. The study investigated the wear mechanism of the FGM at various loads.

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Publication Type: Patent

Year of Publication Title

2017

Shantanu Bhowmik, Dr. Govindaraj M., Ajeesh G, and Dr. Sivakumar V., “Development of Light Weight Blast Proof Composite for Aviation, Space and Defence Structural Applications”, U.S. Patent 2017410463972017.

Publication Type: Conference Paper

Year of Publication Title

2012

Dr. Govindaraj M., Rao, P. K., Chakkingal, U., and K., B., “Effect of Distance between Passes in Friction Stir Processing of Magnesium Alloy”, in Advances in Materials and Processing, 2012.[Abstract]


Friction stir processing is applied for property improvement of cast alloys for last two decades and many developmental studies were carried out in this topic on various alloys. In the current work, friction stir processing was carried out on rare earth containing magnesium alloy AE42. This alloy was specially developed for automobile application as it has better creep resistance than commercial magnesium alloys. Multi-pass Friction Stir Processing was carried out with varying the distance between passes from 0.5 mm to 2.5 mm using 12 mm shoulder diameter tool. Pin was with conical (tapered) and flat configurations with 3 mm height. After processing, the resultant mechanical and metallurgical properties were evaluated. Microstructure was refined to 5 micron and the secondary phases were made in to tiny pieces of 0.5-1 micron and evenly distributed in the matrix. Continuous network of grain boundary which is reason for poor mechanical properties was eliminated. Mechanical properties were improved by 30%. The variation of mechanical properties of processed material with respect to variation of distance between passes was negligible from 1 mm to 1.5 mm for flat pin tool. More »»

2012

Dr. Govindaraj M., Rao, P. K., Uday, C., K., B., and Comondore, R., “Friction Stir Processed Rare Earth Containing Magnesium Alloy for High Temperature Application”, in Advances in Metallic Materials and Manufacturing Processes for Strategic Sectors, 2012.[Abstract]


Friction stir processing was performed on rare earth containing magnesium alloy AE42 with the aim of improving the mechanical properties. The resultant stir zone mechanical and metallurgical properties were analyzed to determine the application temperature of the zone. Stir zone microstructure was refined to 5 micron and the grain morphology was completely changed. Second phase intermetallics Al11RE3 Al2RE were refined to submicron level tiny pieces and homogenously distributed throughout magnesium matrix. As a major achievement, both toughness and strength of the stir zone was improved by 15 to 25%. High temperature properties up to 250°C were better than base metal. The stir zone was capable of withstanding more temperature and stress than the base metal. More »»

Research Projects

  • Development, field trial, pilot production and technology demonstration of sintered brake pads with improved performance for wind turbine applications suitable to India specific wind characteristics.
  • Development of Braze Joint between Carbon-Carbon (C-C) Composites and Titanium Alloy Ti6A14V

List of Ph. D. Students

Current: 5

  • Pavankalyan Kota [CB.EN.D.MEE18007-FT]
  • Rajesh Kannan K. [CB.EN.D*MEE19003-FT]
  • Gopinath Ckkravarthy [CB.EN.D*MEE19004- PT]
  • Srinivasan K. [CB.EN.DMEE19006-PT]
  • Sreeraj S. [CB.EN.D*MEE18012-PT]

Industrial Collaboration/ Consultancy

  • Alloy development works - for ARCI-Hyderabad
  • Indigenization work of pipe noise maker - for Indian Navy

Key Responsibilities at Amrita Vishwa Vidyapeetham

  • Setting up a self sustaining material processing facility for advanced materials
  • Doctoral dissertation
  • Undergraduate and post graduate courses

Membership in Professional Bodies

  • Life Member - Indian Institute of Metals

Other Achievements / Activities

  • BOS Member for Sri Eshwar College of Engineering