Bhagwati Prasad Kashyap

Bio: Bhagwati Prasad Kashyap is an academic researcher from Indian Institute of Technology Bombay. The author has contributed to research in topics: Strain rate & Superplasticity. The author has an hindex of 31, co-authored 148 publications receiving 2796 citations. Previous affiliations of Bhagwati Prasad Kashyap include University of Manitoba & University of California, Davis.

Effect of Solid Die Equi-Channel Pressing Angle on β-Mg 17 Al 12 Phase Morphology and Mechanical Behavior of AZ80 Mg alloy

Abstract: The effects of die channel angle (Φ) in hot (~623 K) equi-channel angular pressing (ECAP) on microstructure, and tensile and compressive flow properties of AZ80 Mg alloy were investigated. Two solid ECAP dies, having Φ of (1) dual 60° and 120° in a single die and (2) 90° in another die, were designed for this purpose. Grain refinement with more than 40% reduction in average grain size along with submicron size second-phase β-precipitates was achieved after single-pass ECAP. A great variation in β-Mg17Al12 phase morphology with increasing flow stresses in tension and compression are found with decreasing value of angle Φ. There found an increasing effect on strain to failure with decrease in porosity and second-phase precipitate modification. However, there appears flow asymmetry between tension and compression with the latter exhibiting greater flow stress and strain to failure.

Effect of proportion on the flow stress of AlCu alloys at 540° C

Abstract: Al-Cu alloys have been extensively investigated for their strength and deformation behavior. In two-phase systems, the strength of an alloy is estimated by the sum of the strengths of the component phases in proportion to their volume fractions. The hardness values of the K and (Theta) phases present in two-phases present in two-phase Al-Cu alloys of various compositions have also indicated an increase in the hardness of the soft k phase and a decrease in the hard [Theta] phase with respect to the hardness of the corresponding single phase systems. A change in the proportion of the two phases in an alloy also influences the grain size, in which case, the evaluation of the effect of any one of these variables on the flow stress is complicated. However, high log(stress) - log(strain rate) curves with the flow stress being independent of such conditions, the effect of k/[Theta] - phase proportion in the Al-Cu alloys can be studied without being affected by grain size. Therefore, the effect of k/[Theta]-phase proportion on the flow stress in the Al-Cu alloys was investigated under such conditions in the present work.

Texture measurement in Zr-2.5%Nb pressure tubes for pressurized heavy water reactors

Abstract: Preferred orientation or crystallographic texture of Zr-2.5%Nb pressure tubes for a pressurized heavy water reactor (PHWR) affects all the critical in-reactor properties. The preferred orientation has to be measured to standardize the process route for getting the desired in-reactor properties. The quantitative determination involves determination of the complete pole figure and calculation of Kearns parameters from the pole figure data. Independently, neither the X-ray reflection nor the X-ray transmission technique can provide the full pole figure data. The literature reports only partial pole figures. Quantification of texture based on partial pole figures may lead to errors in estimation. For a complete pole figure determination, it is required to merge the data from both the reflection and the transmission techniques. This requires a special test setup that can combine the pole figure data obtained from the two techniques. In this paper, a methodology for determination of the complete pole figure with quantitative texture parameters for Zr-2.5%Nb pressure tubes is reported.

Friction Stir Processing of 2507 Super Duplex Stainless Steel: Microstructure and Corrosion Behaviour

Abstract: Friction stir processing (FSP) has been shown to be effective in the microstructural modification. In this study, 2507 super duplex stainless steel was subjected to multipass FSP and the processed samples were investigated. Refinement in grain size of both ferrite and austenite was observed in the stir zone of the processed samples. Increased number of passes led to further reduction in grain size. Anodic polarization studies in 3.5 wt% NaCl solution showed that the processed samples possessed improved corrosion resistance. The Mott-Schottky analysis confirmed that the charge carrier density in the passive oxide layer is decreased with decreasing grain size.

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Mechanical Behavior of Materials

Abstract: A balanced mechanics-materials approach and coverage of the latest developments in biomaterials and electronic materials, the new edition of this popular text is the most thorough and modern book available for upper-level undergraduate courses on the mechanical behavior of materials To ensure that the student gains a thorough understanding the authors present the fundamental mechanisms that operate at micro- and nano-meter level across a wide-range of materials, in a way that is mathematically simple and requires no extensive knowledge of materials This integrated approach provides a conceptual presentation that shows how the microstructure of a material controls its mechanical behavior, and this is reinforced through extensive use of micrographs and illustrations New worked examples and exercises help the student test their understanding Further resources for this title, including lecture slides of select illustrations and solutions for exercises, are available online at wwwcambridgeorg/97800521866758

Recent developments in stainless steels

Abstract: This article presents an overview of the developments in stainless steels made since the 1990s. Some of the new applications that involve the use of stainless steel are also introduced. A brief introduction to the various classes of stainless steels, their precipitate phases and the status quo of their production around the globe is given first. The advances in a variety of subject areas that have been made recently will then be presented. These recent advances include (1) new findings on the various precipitate phases (the new J phase, new orientation relationships, new phase diagram for the Fe–Cr system, etc.); (2) new suggestions for the prevention/mitigation of the different problems and new methods for their detection/measurement and (3) new techniques for surface/bulk property enhancement (such as laser shot peening, grain boundary engineering and grain refinement). Recent developments in topics like phase prediction, stacking fault energy, superplasticity, metadynamic recrystallisation and the calculation of mechanical properties are introduced, too. In the end of this article, several new applications that involve the use of stainless steels are presented. Some of these are the use of austenitic stainless steels for signature authentication (magnetic recording), the utilisation of the cryogenic magnetic transition of the sigma phase for hot spot detection (the Sigmaplugs), the new Pt-enhanced radiopaque stainless steel (PERSS) coronary stents and stainless steel stents that may be used for magnetic drug targeting. Besides recent developments in conventional stainless steels, those in the high-nitrogen, low-Ni (or Ni-free) varieties are also introduced. These recent developments include new methods for attaining very high nitrogen contents, new guidelines for alloy design, the merits/demerits associated with high nitrogen contents, etc.

Additively manufactured hierarchical stainless steels with high strength and ductility

Abstract: Many traditional approaches for strengthening steels typically come at the expense of useful ductility, a dilemma known as strength-ductility trade-off. New metallurgical processing might offer the possibility of overcoming this. Here we report that austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibit a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels. High strength is attributed to solidification-enabled cellular structures, low-angle grain boundaries, and dislocations formed during manufacturing, while high uniform elongation correlates to a steady and progressive work-hardening mechanism regulated by a hierarchically heterogeneous microstructure, with length scales spanning nearly six orders of magnitude. In addition, solute segregation along cellular walls and low-angle grain boundaries can enhance dislocation pinning and promote twinning. This work demonstrates the potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications.