Sushanta Kumar Panigrahi

Bio: Sushanta Kumar Panigrahi is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Alloy & Microstructure. The author has an hindex of 28, co-authored 81 publications receiving 2594 citations. Previous affiliations of Sushanta Kumar Panigrahi include Indian Institute of Technology Roorkee & École centrale de Nantes.

Investigation into the micro deep drawing capabilities of a specially engineered refined aluminium alloy

Abstract: During miniaturisation, size of the part comes close to grain size of the material. There is an overall decrease in the total number grains undergoing deformation and most of these are surface grains. Therefore, microscale deformation is marked by abnormal stress-strain response which limits the manufacturing capabilities of microforming. Two distinct phenomena responsible for this are: (i) dominance of single crystal deformation behaviour, and (ii) increased strain localisation due to incompatibly between surface and core grains during deformation. The present work attempts to neutralise these effects by increasing the number of grains in the deformation zone. This has been achieved by engineering refined microstructure in the materials. To develop the refined microstructure, cryorolling followed by controlled annealing treatment has been employed. Microscale deformation behaviour and microforming capabilities of the refined material have been compared with its coarse-grained counterpart by analysing their tensile curves and by post-mortem study of micro deep drawn components over a wide range of sample thicknesses. Material with fully recrystallised, equiaxed, strain-free refined microstructure is found to have the best strain hardening response both in micro and macro deformation domains. This property is also reflected in the micro deep drawing capabilities of the same material.

Deformation Behaviour and Fracture Mechanism of Ultrafine-Grained Aluminium Developed by Cryorolling

Abstract: This chapter highlights the fundamental deformation and fracture mechanism of an engineered ultrafine-grained (UFG) material developed by a combination of cryorolling and short-annealing treatment. The UFG material developed by cryorolling possesses superlative tensile strength. However, the ductility and strain hardening potential of the material is found to be low, reducing its manufacturing capabilities. Controlled post-deformation annealing results in a combination of good strength and ductility. The anisotropic property of the material is also improved after short-term annealing. These properties have been attributed to the unique equiaxed, thermally stable microstructure comprising of high-angled nanometric grains. The various mechanical properties have been experimentally evaluated by performing the tensile test at all three different processing conditions (base, cryorolled, annealed) and the corresponding strain hardening potential, fracture behaviour and anisotropic properties have been systematically investigated. These properties have been correlated with the microstructural features of the material. This has been achieved by mechanical testing and characterisation of the material by employing transmission electron microscopy, fractographic analysis and determination of mechanical anisotropy coefficient (Lankford coefficient). Finally, a case study on the improved microforming abilities of UFG material over coarse-grained material has been presented.

Thermophysical properties of hybrid silica phenolic ablative composite: Theoretical and experimental analysis

Abstract: Silica phenolic ablative composites are used in many high-temperature applications like rocket/missile solid motor nozzles, space re-entry vehicles, and so forth. As ablative composite with lower thermal conductivity and density can save considerable cost, a hybrid silica phenolic ablative composite was developed by establishing a novel processing methodology using chopped silica fiber, phenolic resin, and hollow glass microsphere. The thermophysical properties of the developed hybrid composite are analyzed and established the scientific know-how. The developed composites, with 36% lower density, displayed 50% lower thermal conductivity and 50% lower thermal diffusivity than standard silica phenolic composite. Since a proper thermal conductivity model for a three-component composite with matrix, fiber, and hollow glass microsphere is not available, the most suitable model for the developed composite is established.

Nanostructured aluminium alloys produced by severe plastic deformation: New horizons in development

Abstract: In recent years, much progress has been made in the studies of nanostructured Al alloys for advanced structural and functional use associated both with the development of novel routes for the fabrication of bulk nanostructured materials using severe plastic deformation (SPD) techniques and with investigation of fundamental mechanisms leading to improved properties. This review paper discusses new concepts and principles in application of SPD processing to fabricate bulk nanostructured Al alloys with advanced properties. Special emphasis is placed on the relationship between microstructural features, mechanical, chemical, and physical properties, as well as the innovation potential of the SPD-produced nanostructured Al alloys.