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.

Grain Growth and β-Mg17Al12 Intermetallic Phase Dissolution During Heat Treatment and Its Impact on Deformation Behavior of AZ80 Mg-Alloy

Abstract: Microstructure evolution after solutionizing and ageing treatment of cast AZ80 Mg alloy were investigated using optical and scanning electron microscopy. Effect of these treatments on grain size, β-Mg17Al12 intermetallic phase, mechanical behavior, and flow asymmetry were investigated. The initial continuous network of β-phase found to be reduced after solutionizing. The dissolution of β-phase and simultaneous grain growth are found to be interrelated. Mechanical properties including yield strength, maximum strength (ultimate compressive strength), and maximum strain attainable in compressive found almost twice than the corresponding values obtained in tension. The asymmetry in compressive and tensile properties is found to decrease with grain size at certain solutionizing duration. Particular heat treatment found to offer best combination of tensile compressive flow properties in AZ80 Mg alloy. Aging under certain conditions found to minimize the strength asymmetry.

Microtextural evolution during superplastic deformation of AA 8090 Al–Li alloy

Abstract: A brief review of orientation imaging microscopy and an overview of the results of investigations related to textural evolution during superplastic deformation of a recent series of superplastic grade aluminium alloys, and specifically the results of the authors' study on microtextural evolution in AA 8090 Al–Li alloy, are presented. It was observed that the surface layer of the AA 8090 alloy sheet was dominated by S {011}〈634〉 type texture, whereas the midthickness layer was dominated by brass {011}〈211〉 type texture. In the course of superplastic deformation, textural weakening occurred, the rate and extent of which were different in the surface and centre regions, depending upon whether the two layers were deformed separately or as a composite in the full thickness tensile specimen. Textural weakening was generally more extensive at higher test temperatures and lower strain rates. Based on textural evolution and the presence of a large proportion of low angle boundaries, and their near eliminat...

Characterisation of dynamic recovery during hot deformation of spray formed Al-Li alloy (UL40) using processing map approach

Abstract: Processing maps, also known as power dissipation maps, for spray formed Al–Li alloy (UL40), encompassing a wide range of hot working temperature (375–575°C) and strain rate (3 × 10−4–101 s−1) have been developed. The constant true strain rate compression tests were carried out under isothermal conditions to generate the stress–strain data required for computing the efficiency of power dissipation η. The maps exhibit three distinct regimes. The two high efficiency (>55%) regimes occur at the low strain rates ( 1 s−1), and the other with moderate efficiency values (20–23%) occurs at the intermediate strain rate (10−1 s−1). The latter one has been interpreted to be associated with dynamic recovery (DRV) process while the other two regimes have been found to be associated with cracking processes. The DRV regime in the map has been characterised in terms of stress–strain response, microstructure and tensile ductility. The kinetic rate analysis carried out i...

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.