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.

Aging response on the stress corrosion cracking behavior of wrought precipitation-hardened magnesium alloy

Abstract: Constant immersion testing and slow strain rate testing (SSRT) are conducted on wrought magnesium alloy in a 3.5 wt% NaCl solution. After solution annealing (SA) at 525 °C for 8 h, the alloy was isothermally aged at 210 °C for 15 h, 48 h, and 144 h to obtain underaged (UA), peak-aged (PA), and overaged (OA) microstructures, respectively. After 32 days of constant exposure in chloride solution, the SA and UA samples showed the lowest (~ 0.10 mg cm−2 day−1) and the highest (~ 0.20 mg cm−2 day−1) weight loss, respectively. SSRT was carried out at an initial strain rate of 10−6 s−1 in air and 3.5 wt% NaCl solution to investigate stress corrosion cracking (SCC) susceptibility. SCC susceptibility index was in the order PA > UA > SA > OA. Intergranular failure morphology on the fractured surface after SSRT in chloride solution can be attributed to micro-galvanic activity between grain boundary second phase and adjacent regions. Comparison of electrochemical measurements in unstressed and stressed conditions indicated two orders of magnitude difference in electrochemical resistance of the alloy.

Influence of Initial Microstructure on Microstructural Stability and Mechanical Behavior of Cryorolled A356 Alloy Subjected to Annealing

Abstract: In the present work, various heat treatment cycles are imposed on an A356 aluminum alloy to develop two different base microstructures, one with supersaturated aluminum matrix and the other with coarse and uniformly distributed precipitates. Both the developed materials are subjected to cryorolling and then isochronally annealed for 1 hour at various temperatures ranging from 373 K to 673 K (100 °C to 400 °C). The overall strength is maximum for the cryorolled material with supersaturated base microstructure due to the dominant dislocation strengthening and precipitation strengthening mechanisms. However, the cryorolled material with precipitated base microstructure is found to have superior microstructural stability with retained ultrafine-grained (UFG) microstructure up to the annealing temperature of 473 K (200 °C) due to effective grain boundary pinning by the precipitates. Also, the material retains about 85 pct of as-cryorolled strength with enhanced ductility even after annealing at 473 K (200 °C). A detailed investigation on the microstructural evolution of the material at various annealing temperatures along with their mechanical behavior is presented in this article.

Microstructure and Texture of Cold Rolled and Recrystallized CrNoNi Medium-Entropy Alloy

Abstract: An equiatomic CrCoNi medium-entropy alloy plate was heavily deformed by conventional cold rolling and subsequently annealed at different temperatures. Microstructure and texture evolution of the deformed and annealed sheets were investigated by electron backscatter diffraction and X-ray diffraction. Heavy cold rolling induces an alloy type α-fibre texture with major brass component. This type of texture is indicative of low stacking fault energy of the CrCoNi alloy. Annealing at 700 °C leads to a homogeneously recrystallized microstructure with ultrafine grains of about 800 nm average size. The volume fraction of different texture components is almost similar after annealing at different temperatures. However, the overall texture intensity after annealing is very weak. Finally, in order to understand the microstructure and texture evolution of the CrCoNi alloy, it is critically compared with other low stacking fault energy FCC materials.

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.