Rajesh K. Khatirkar
Visvesvaraya National Institute of Technology
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Featured researches published by Rajesh K. Khatirkar.
Science and Technology of Welding and Joining | 2016
Himanshu Vashishtha; Ravindra V. Taiwade; Rajesh K. Khatirkar; Ashwinkumar S. Dhoble
In the present investigation effect of austenitic fillers namely E308, E309 and E310 on microstructural and mechanical properties of ultra-low nickel austenitic stainless steel weldment was analysed. The WRC-1992 diagram has been used to predict δ-ferrite and solidification mode of weld metal. Microstructural exploration confers the variation in magnitude and morphologies of δ-ferrite for different Creq/Nieq ratio. It was observed that greater amount of δ-ferrite resulted in improved tensile strength. On the other hand, it lowered the impact strength of weld joint. The results indicated that E308 exhibits higher hardness and tensile strength, whereas E310 demonstrates higher impact strength and this may be attributed to the variation in δ-ferrite content and solidification mode. During tensile test joints failed in heat affected zone for all weld specimen. Surface morphology of fragmented specimens was analysed using scanning electron microscopy and different morphologies were recognised for samples failed before and after Strauss test.
Journal of Applied Physics | 2008
M. Ahmad; Mrugesh Desai; Rajesh K. Khatirkar
Copper ferrite thin films, radio-frequency sputtered at 200 W, on fused quartz substrates, postannealed at about 800 °C and slow cooled, exhibited a tetragonal copper ferrite phase, but with a preferred orientation of mainly a (311) or (400) peak. The films show a perpendicular coercivity of about 3000 Oe or more, almost two times the parallel coercivity. Magnetocrystalline anisotropy is the major cause of the high coercivity observed in these films. The perpendicular anisotropy of these films is attributed to the texture with the hard axis in the film plane as seen by texture measurement.
Materials and Manufacturing Processes | 2018
Jagesvar Verma; Ravindra V. Taiwade; Chandraprakash Reddy; Rajesh K. Khatirkar
ABSTRACT In the present study, dissimilar alloys such as Mg-AZ31B and Al-AA6061 were joined by friction stir welding using different rotational (560, 710, 860 and 1010 rpm) and transverse speeds (16 and 25 mm/min). Metallographic studies (by optical, scanning electron microscope, SEM, and energy dispersive spectrometer, EDS) revealed that the speed parameters mainly influenced the microstructure growth mechanism, which further affects the mechanical properties and corrosion behavior. The combined dynamic action of rotational to transverse speed recrystallized and plasticized the material and produced an alternative lamellar shear band of Al and Mg in the stir zone (SZ). Peak temperature and high rotational speed formed an oxide on the top region and also caused liquation and intermetallic (IMCs) formation. Tensile strength and hardness increased as per the Hall–Petch (fine grains) effect. Higher impact energy was found at moderate rotational and low transverse speeds due to the presence of more soft Al patches. Tensile fractographs showed a river-like pattern, which indicated the brittle nature of the joints. High rotational and high transverse speed illustrated higher tensile strength, while better corrosion resistance was observed in high rotational and low transverse speed.
Philosophical Magazine | 2017
Amit Kumar; Rajesh K. Khatirkar; Darshan Chalapathi; Nitish Bibhanshu; Satyam Suwas
Abstract In the present work, evolution of microstructure and crystallographic texture during cold rolling of two phase Fe–Cr–Ni alloy was investigated. Fe–Cr–Ni alloy (in initially solution annealed condition) was uni-directionally cold rolled in a laboratory rolling mill to different thickness reductions. Scanning electron microscopy was used to observe the changes in microstructure, while X-ray diffraction was used to investigate changes in crystallographic texture of austenite and ferrite (through changes in orientation distribution function). Crystallographic texture was also simulated using different crystal plasticity models (Full constraint Taylor, relaxed constraint Taylor (lath and pancake) and co-deformation Visco Plastic Self Consistent (VPSC)). With the increase in plastic deformation, there were morphological as well as crystallographic changes in the microstructure. Strong α-fibre (RD//〈1 1 0〉) texture was developed in ferrite, while brass ({1 1 0}〈1 1 2〉) and Goss ({1 1 0}〈0 0 1〉) was dominant in austenite after 80% cold rolling. The formation of brass type texture after deformation has been attributed to the formation of shear bands and presence of strong crystallographic texture in the initial solution annealed material. Both Taylor as well as VPSC models could not capture the changes in texture with deformation accurately. For ferrite: γ-fibre (ND//〈1 1 1〉) and for austenite: Cu ({1 1 2}〈1 1 1〉) component was always present in the simulated textures. Possible reason for this could be the pining effect of interface boundaries and non-incorporation of non-crystallographic shear banding in the Taylor and VPSC models.
Philosophical Magazine Letters | 2018
Amit Kumar; Aman Gupta; Rajesh K. Khatirkar; Satyam Suwas
Abstract Texture development during multi-step cross rolling of a dual-phase Fe–Cr–Ni alloy has been investigated. X-ray diffraction was used to investigate changes in crystallographic texture of both the constituent phases (austenite and ferrite) through changes in orientation distribution function. After deformation, rotated brass (rotated along φ1, i.e. the sample normal direction ND), along with a weak cube texture was observed in austenite, while a strong rotated cube texture was obtained in ferrite. Texture was also simulated for various strains using a co-deformation model by self-consistent visco-plastic (VPSC) formulation. Simulations showed strong rotated brass texture in austenite and a strongly rotated cube, α-fibre (sample rolling direction RD //<1 1 0>) and γ-fibre (ND //<1 1 1>) in ferrite after highest strain (εt = 1.6). VPSC models could not effectively capture the change in crystallographic texture during cross rolling. In ferrite, simulations showed an overestimation of γ-fibre component and an underestimation of rotated cube component. Simulated texture of austenite, on the other hand, showed an overestimation of rotated brass with an absence of cube component. The results are rationalised based on the possible role of shear banding and activation of non-octahedral slip system during cross rolling, both of which are not incorporated in conventional VPSC models.
Tribology - Materials, Surfaces & Interfaces | 2016
Avishkar Rathod; Sanjay G. Sapate; Rajesh K. Khatirkar
Hardfaced martensitic stainless steel alloy was deposited on mild steel substrate by flux cored arc welding method. The slurry abrasion studies of weld-deposited hardfaced steel were performed using slurry abrasion test rig with 250–300 μm silica sand particles. The effect of weld compositional gradation on the abrasive wear resistance of hardfaced stainless steel at a distance of 0.6, 1.2, 2.4, 3.0 and 3.6 mm from the top surface was studied. The observed abrasion rates were rationalized in terms of mass loss, hardness and distance from the top surface i.e. diluted surfaces beneath the top surface. The abrasive wear mass loss increased with increasing distance beneath the top surface, which was attributed to the coarsening and morphology change in martensite phase. The results of the present work indicated change in morphology of martensite with increase in the distance beneath the top surface. The operating abrasive wear mechanisms involved ploughing, microcutting and indentation.
Philosophical Magazine Letters | 2016
Shreyash Hadke; Manendra Singh Parihar; Satish Kumar Shekhawat; Rajesh K. Khatirkar
Abstract A new method, referred to as the cluster method, is proposed and tested for the reconstruction of pre-transformation microstructure in Ti–6Al–4V alloy. The cluster method begins by constructing clusters of daughter grains (room-temperature hcp α-phase) that have a high probability of being transformed from the same parent grain (high-temperature bcc β-phase). These clusters are then grown, and back-transformed to the parent grain orientations using the ‘summation of mutual misorientation angle method’ (SMMA method). The cluster method is validated by comparing the obtained results with the results of the SMMA and triplet methods.
Applied Mechanics and Materials | 2013
Avishkar Rathod; Sanjay G. Sapate; Rajesh K. Khatirkar
Wear by slurry abrasion is very expansive problem that must be taken into consideration while selecting the material for the transportation of slurry through pipeline. Abrasive wear generally occurs when abrasive slurries come in contact with the industrial engineering components or slurry transporting pipes. The abrasive particles carried by slurries eventually remove the material from the encountering surfaces which results in the early failure of the component in service. In present investigation an attempt is made to study the effect of load, slurry concentration, sliding distance on the abrasive wear behaviour of mild steel. The slurry abrasion experiments were carried out using slurry abrasion test apparatus with silica sand slurry. The findings of the present investigation indicate that slurry abrasion volume increased with slurry concentration, load and sliding distance, although the magnitude of increase was different in each case. The SEM observation of worn out surfaces revealed micro ploughing and micro cutting as wear mechanisms.
Materials Science Forum | 2011
Rajesh K. Khatirkar; Karri V. Mani Krishna; Leo Kestens; Roumen Petrov; Prita Pant; I. Samajdar
Ultra low carbon (ULC) steel samples were deformed in near plane-strain compression mode with different strains, strain rates and temperatures. Different aspects of microstructural developments, for deformed γ (ND//) and θ (ND//) fibre grains, were investigated using X-ray line profiles and high resolution electron diffraction. The study clearly showed increase in grain interior strain localizations and in-grain misorientation at the intermediate deformation temperature. This effect was more apparent in γ-fibre and can best be explained through orientation sensitive recovery. γ-fibre also demonstrated higher potential for increase in dislocation density. This was observed experimentally and simulated through discrete dislocation dynamic simulations. Higher textural softening with stronger increase in dislocation density and possible effects of orientation sensitive recovery appears to define the orientation dependent recovery in low carbon steels.
Materials Characterization | 2014
Rahul Unnikrishnan; K.S.N. Satish Idury; T.P. Ismail; Alok Bhadauria; Satish Kumar Shekhawat; Rajesh K. Khatirkar; Sanjay G. Sapate