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Constant power density boundaries showing the relationship between the focu...
Available to Purchase
in Introduction to High Energy Density Electron and Laser Beam Welding
> Welding Fundamentals and Processes
Published: 31 October 2011
Fig. 4 Constant power density boundaries showing the relationship between the focused beam diameter and the absorbed beam power for approximate regions of keyhole-mode welding, conduction-mode welding, cutting, and drilling
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Book Chapter
Introduction to High Energy Density Electron and Laser Beam Welding
Available to PurchaseSeries: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005627
EISBN: 978-1-62708-174-0
... constant power density boundaries, showing the relationship between the focused beam diameter and the absorbed beam power for approximate regions of keyhole-mode welding, conduction-mode welding, cutting, and drilling. absorbed beam power conduction-mode welding cutting drilling electron beam...
Abstract
This article provides a history of electron and laser beam welding, discusses the properties of electrons and photons used for welding, and contrasts electron and laser beam welding. It presents a comparison of the electron and laser beam welding processes. The article also illustrates constant power density boundaries, showing the relationship between the focused beam diameter and the absorbed beam power for approximate regions of keyhole-mode welding, conduction-mode welding, cutting, and drilling.
Book Chapter
Electromagnetic Problem Solutions
Available to PurchaseSeries: ASM Handbook
Volume: 4C
Publisher: ASM International
Published: 09 June 2014
DOI: 10.31399/asm.hb.v04c.a0005877
EISBN: 978-1-62708-167-2
... density, current density, magnetic field strength, and magnetic flux density. This article describes the behavior of the EMF by Maxwell's equations in integral or differential forms. It discusses the definition of potentials; methods of mathematical modeling; boundary conditions; and energy, power density...
Abstract
Electromagnetic problem solutions are based on the macroscopic theory of the continuous model for the electromagnetic field (EMF). It is described by a system of integral or partial differential equations for five vector quantities, namely, electric field strength, electric flux density, current density, magnetic field strength, and magnetic flux density. This article describes the behavior of the EMF by Maxwell's equations in integral or differential forms. It discusses the definition of potentials; methods of mathematical modeling; boundary conditions; and energy, power density, and electromagnetic forces.
Book Chapter
High-Temperature Superconductors for Wires and Tapes
Available to PurchaseSeries: ASM Handbook
Volume: 2
Publisher: ASM International
Published: 01 January 1990
DOI: 10.31399/asm.hb.v02.a0001114
EISBN: 978-1-62708-162-7
... in the a-b planes is orders of magnitude higher than current flow in the c -axis direction. The poor coupling between grains or the weak link mechanism is dominated by this current density anisotropy and grain-boundary-related problems such as precipitate or impurities along the grain boundaries...
Abstract
The discovery of the high-critical-temperature oxide superconductors has accelerated the interest for superconducting applications due to its higher-temperature operation at liquid nitrogen or above and thus reduces the refrigeration and liquid helium requirement. It also permits usage of the high-critical-temperature oxides in magnets or power applications in high-current-carrying wire or tape with acceptable mechanical capability. This article discusses the powder techniques mainly based on the production of an oxide powder precursor, which is then subjected to various processing, including powder-in-tube processing, vapor deposition processing, and melt processing. It further discusses the microstructural, anisotropy and weak link influences on these processes.
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005404
EISBN: 978-1-62708-196-2
... approximated to be similar to that of grain-boundary diffusion. With the dislocation cores serving as pathways for diffusion, the dislocation density contained within the material will have a significant impact on the pipe diffusion rates. Since the dislocation density is proportional to the stress squared...
Abstract
This article, to develop an understanding of the underlying mechanisms governing deformation at elevated temperatures, discusses the phenomenological effects resulting from temperature-induced thermodynamic and kinetic changes. It describes the deformation behavior of engineering materials using expressions known as constitutive equations that relate the dependence of stress, temperature, and microstructure on deformation. The article reviews the characteristics of creep deformation and mechanisms of creep, such as power-law creep, low temperature creep, power-law breakdown, diffusional creep, twinning during creep deformation, and deformation mechanism maps. It discusses the creep-strengthening mechanisms for most structural engineering components. The article provides a description of the microstructural modeling of creep in engineering alloys.
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005533
EISBN: 978-1-62708-197-9
..., and high power densities ( Ref 1 ). In some cases of surface hardening of massive parts with shallow case depths (typically less than 1 mm), it is possible to use self–quenching techniques (also called mass quenching). If the heated surface layer is sufficiently thin and its mass is appreciably small...
Abstract
This article describes the applications of induction heat treatment of metals, including normalizing, annealing, hardening, and tempering and stress relieving. It discusses the simulation techniques of the electromagnetic and thermal processes that occur during induction heat treating. The article explains the finite-difference method, finite-element method, mutual impedance method, and boundary-element method for the numerical computation of the induction heat treating processes. It also discusses the direct and indirect coupling approaches for coupling the electromagnetic and heat-transfer problems. Modern computer simulation techniques are capable of effectively simulating electromagnetic and thermal phenomena for many processes that involve electromagnetic induction. The article considers the challenges faced by developers of modern simulation software.
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005403
EISBN: 978-1-62708-196-2
... ) or Stüwe and Hertel ( Ref 28 ), can be employed as well. In contrast to the power law, they lead to a steady-state flow stress at large strains. However, they are unable to model the flow softening usually associated with DRX. Effect of Grain-Boundary Migration on the Dislocation Density A first...
Abstract
Recrystallization is to a large extent responsible for their final mechanical properties. This article commences with a discussion on static recrystallization (SRX) and dynamic recrystallization (DRX). The DRX includes continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX). The article discusses the assumptions and simplifications for the Avrami analysis. It describes the effects of nucleation and growth rates on recrystallization kinetics and recrystallized grain size based on the Johnson-Mehl-Avrami-Kolmogorov model for static recrystallization. The article reviews the kinetics of DRX with the aid of the Avrami relations. It considers the basic framework of the mesoscale approach for DDRX, including the three basic equations for grain size changes, strain hardening and dynamic recovery, and nucleation. The article explains the mesoscale approach for CDRX to predict microstructural evolutions occurring during hot deformation, along with an illustration of the main features of the CDRX mesoscale model.
Series: ASM Handbook
Volume: 4C
Publisher: ASM International
Published: 09 June 2014
DOI: 10.31399/asm.hb.v04c.a0005835
EISBN: 978-1-62708-167-2
... v q d V where P i is power in W, which is converted into heat inside the element: (Eq 9a) d P v = p v ( P , t ) d V where p v is volumetric power density in W/m 3 . This produces the change of the internal energy of the element per the unit of time...
Abstract
Induction heating is a combination of several interrelated physical phenomena, including heat transfer, electromagnetics, and metallurgy. This article presents a brief review of different heat transfer modes, namely, heat conduction, thermal radiation, and convection. It focuses on the specifics of induction heating and heat treating applications. The article discusses the nonlinear and interrelated nature of a particular heat transfer phenomenon, physical property, and skin effect. It also presents simple case studies and general physical laws governing different heat transfer modes. The article also discusses the basic concepts of direct current and alternating current circuits, and reviews the theory of electromagnetic fields.
Book Chapter
Additive Manufacturing of Tungsten, Molybdenum, and Cemented Carbides
Available to PurchaseSeries: ASM Handbook
Volume: 24
Publisher: ASM International
Published: 15 June 2020
DOI: 10.31399/asm.hb.v24.a0006583
EISBN: 978-1-62708-290-7
... section using a 200 W laser. They concluded that higher densities require higher laser powers. Wang et al. ( Ref 2 ) could increase the relative density to 99.1% by using a 400 W laser, plasma-spheroidized powder, a scan strategy with 67° layer rotation, and a support structure for preserving heat...
Abstract
Tungsten, molybdenum, and cemented carbide parts can be produced using several additive manufacturing technologies. This article classifies the most relevant technologies into two groups based on the raw materials used: powder-bed methods, such as selective laser melting, electron beam melting, and binder jet three-dimensional (3-D) printing, and feedstock methods, such as fused-filament fabrication and thermoplastic 3-D printing. It discusses the characteristics, processing steps, properties, advantages, limitations, and applications of these technologies.
Book Chapter
Effect of Irradiation on Stress-Corrosion Cracking and Corrosion in Light Water Reactors
Available to PurchaseSeries: ASM Handbook
Volume: 13C
Publisher: ASM International
Published: 01 January 2006
DOI: 10.31399/asm.hb.v13c.a0004147
EISBN: 978-1-62708-184-9
... for fast neutrons, versus 0.01 eV/nm for gamma radiation) ( Ref 55 ). Also, the neutron flux in LWRs (e.g., ∼1.03×10 9 rad/h core average and ∼1.68×10 9 rad/h peak in a BWR of 51 W/cm 3 power density) is also higher than the gamma flux (∼0.34×10 9 rad/h). Indeed, the moderate gamma levels present...
Abstract
This article examines the understanding of persistent material changes produced in stainless alloys during light water reactor (LWR) irradiation based on the fundamentals of radiation damage and existing experimental measurements. It summarizes the overall trends and correlations for irradiation-assisted stress-corrosion cracking. The article addresses the effects of various radiation factors on corrosion. These include radiation-induced segregation at grain boundaries, radiation hardening, mode of deformation, radiation creep relaxation, and radiolysis. The article discusses a variety of approaches for mitigating stress-corrosion cracking in LWRs, in categories of water chemistry, operating guidelines, new alloys, design issues, and stress mitigation. It concludes with a discussion on the irradiation effects of irradiation on corrosion of zirconium alloys in LWR environments.
Series: ASM Handbook
Volume: 4C
Publisher: ASM International
Published: 09 June 2014
DOI: 10.31399/asm.hb.v04c.a0005878
EISBN: 978-1-62708-167-2
...: (Eq 1) div ( λ grad T ) − ρ c ( v grad T ) = − p V where λ denotes the thermal conduction coefficient, ρ is density, c is specific heat, v is velocity, and p V is the volumetric power of heat sources, which in the case of induction heating are represented...
Abstract
Temperature is a typical parameter characterizing the heating level of any particle belonging to a heated body. The basic problem of heat transfer computation is associated with appropriate determination of heat transfer coefficients. This article provides a discussion on the basic equations, initial and boundary conditions, and multiple reflection phenomena of mathematical modeling. These boundary conditions include the Dirichlet, Neumann, and Henkel conditions.
Book Chapter
Additive Manufacturing of Copper and Copper Alloys
Available to PurchaseSeries: ASM Handbook
Volume: 24
Publisher: ASM International
Published: 15 June 2020
DOI: 10.31399/asm.hb.v24.a0006579
EISBN: 978-1-62708-290-7
... along columnar grain boundaries or perpendicular to the build direction, can also be present due to insufficient energy density in that region during scanning, and spherical gas pores can form from multiple mechanisms, including entrapped atomization gases inherent in the powder feedstock or through...
Abstract
This article is a detailed account of additive manufacturing (AM) processes for copper and copper alloys such as copper-chromium alloys, GRCop, oxide-dispersion-strengthened copper, copper-nickel alloys, copper-tin alloys, copper-zinc alloys, and copper-base shape memory alloys. The AM processes include binder jetting, ultrasonic additive manufacturing, directed-energy deposition, laser powder-bed fusion, and electron beam powder-bed fusion. The article presents a review of the literature and state of the art for copper alloy AM and features data on AM processes and industrial practices, copper alloys used, selected applications, material properties, and where applicable, compares these data and properties to traditionally processed materials. The data presented and the surrounding discussion focus on bulk metallurgical processing of copper components. The discussion covers the composition and performance criteria for copper alloys that have been reported for AM and discusses key differences in process-structure-property relationships compared to conventionally processed material. The article also provides information on feedstock considerations for copper powder handling.
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005432
EISBN: 978-1-62708-196-2
... M 0 is a pre-exponential constant, Q b is the activation energy, R is the gas constant, and T is absolute temperature. The driving pressure is either expressed as a direct function of dislocation density ( Ref 21 ) or of the energy of low-angle boundaries ( Ref 36 ). In either instance...
Abstract
This article examines how cellular automaton (CA) can be applied to the simulation of static and dynamic recrystallization. It describes the steps involved in the CA simulation of recrystallization. These include defining the CA framework, generating the initial microstructure, distributing nuclei of recrystallized grains, growing the recrystallized grains, and updating the dislocation density. The article concludes with information on the developments in CA simulations.
Book Chapter
Computational Modeling of Induction Melting and Experimental Verification
Available to PurchaseSeries: ASM Handbook
Volume: 4C
Publisher: ASM International
Published: 09 June 2014
DOI: 10.31399/asm.hb.v04c.a0005898
EISBN: 978-1-62708-167-2
... ) in the hydrodynamic boundary layer The law of cooling states that heat flux surface density q conv is proportional to the difference of temperature between the heated solid (or the wall) T body and cooling liquid (gas) T liquid : (Eq 2) q conv = α ( T body − T liquid...
Abstract
This article focuses on the basic turbulent flow, and the thermal, mass-transfer, and hydrodynamic phenomena for use in modeling physical processes during induction melting. It provides a discussion on transport phenomena equations that includes the approximation of convective terms in the transport equation and computational schemes for the fluid dynamics equation. The aspects of computational algorithms for specific magnetohydrodynamic problems with mutual influence of the magnetic field and melt flow due to the changing shape of the free surface are also considered. The article illustrates the application of the basic equations and approaches formulated for electromagnetic field and melt turbulent flow for the numerical study of an induction crucible furnace.
Book: Powder Metallurgy
Series: ASM Handbook
Volume: 7
Publisher: ASM International
Published: 30 September 2015
DOI: 10.31399/asm.hb.v07.a0006117
EISBN: 978-1-62708-175-7
... trapped within the grains as the grain boundary migrates and leaves the pores behind. As the pores trapped within the grains are difficult or impossible to remove, the ability to attain a high final density can be limited. A common requirement in sintering is a microstructure with high density (low...
Abstract
Sintering is a thermal treatment process in which a powder or a porous material, already formed into the required shape, is converted into a useful article with the requisite microstructure. Sintering can be classified as solid-state, viscous, liquid-phase, and pressure-assisted (or pressure) sintering. This article provides information on the mechanisms and theoretical analysis of sintering and focuses on the types, mechanisms, process and microstructural variables, computer simulation, stages, and fundamentals of densification and grain growth of solid-state sintering and liquid-phase sintering. It describes the models for viscous sintering and the methods used in pressure-assisted sintering, namely, uniaxial hot pressing, hot isostatic pressing, sinter forging, and spark plasma sintering.
Book Chapter
Modeling of Microstructure Evolution during the Thermomechanical Processing of Nickel-Base Superalloys
Available to PurchaseSeries: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005459
EISBN: 978-1-62708-196-2
... of the cells that are on the grain boundaries or next to second-phase particles (to describe PSN on carbides). This fraction was taken to be d ρ/ dt /1000 in the work of Goetz and Seetharaman. Nucleation is performed on those cells if their dislocation density has reached a critical value assumed to be ρ DR...
Abstract
This article summarizes the general features of microstructure evolution during the thermomechanical processing (TMP) of nickel-base superalloys and the challenges posed by the modeling of such phenomena. It describes the fundamentals and implementations of various modeling methodologies. These include JMAK (Avrami) models, topological models, and mesoscale physics-based models.
Book Chapter
Superconducting Materials
Available to PurchaseSeries: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003155
EISBN: 978-1-62708-199-3
... applied current density, J c , exists below which a material is superconductive. Figure 1 shows how these three factors are interrelated. Materials lying within the T c H c J c envelope boundary in Fig. 1 will be superconductive; outside the boundary, conduction is normal. Fig. 1...
Abstract
Superconductors are materials that exhibit a complete disappearance of electrical resistivity on lowering the temperature below the critical temperature. A superconducting material must exhibit perfect diamagnetism, that is, the complete exclusion of an applied magnetic field from the bulk of the superconductor. Superconducting materials that have received the most attention are niobium-titanium superconductors (the most widely used superconductor), A15 compounds (in which class the important ordered intermetallic Nb3Sn lies), ternary molybdenum chalcogenides (Chevrel phases), and high-temperature ceramic superconductors. This article provides an overview of basic principles of superconductors and the different classes of superconducting materials and their general characteristics.
Book Chapter
Effect of Neutron Irradiation on Properties of Steels
Available to PurchaseSeries: ASM Handbook
Volume: 1
Publisher: ASM International
Published: 01 January 1990
DOI: 10.31399/asm.hb.v01.a0001036
EISBN: 978-1-62708-161-0
... less than 1 eV). Such reactors produce a small flux of high-energy neutrons, and until recently, these neutrons were the only ones considered to cause the irradiation effects observed in power reactors. However, as discussed in the section “Irradiation Embrittlement” in this article, recent...
Abstract
Damage to steels from neutron irradiation affects the properties of steels and is an important factor in the design of safe and economical components for fission and fusion reactors. This article discusses the effects of high-energy neutrons on steels. The effects of damage caused by neutron irradiation include swelling (volume increase), irradiation hardening, and irradiation embrittlement (the influence of irradiation hardening on fracture toughness). These effects are primarily associated with high-energy (greater than 0.1 MeV) neutrons. Consequently, irradiation damage from neutrons is of considerable importance in fast reactors, which produce a significant flux of high-energy neutrons during operation. Irradiation embrittlement must also be considered in the development of ferritic steels for fast reactors and fusion reactors. Although ferritic steels are more resistant to swelling than austenitic steels, irradiation may have a more critical effect on the mechanical properties of ferritic steels.
Book Chapter
Additive Manufacturing of Cobalt Alloys
Available to PurchaseSeries: ASM Handbook
Volume: 24
Publisher: ASM International
Published: 15 June 2020
DOI: 10.31399/asm.hb.v24.a0006573
EISBN: 978-1-62708-290-7
... power, scan speed, hatch spacing, and scan pattern influence the porosity and grain structure of an AM part. Liverani et al. ( Ref 37 ) reported the effect of different combinations of power (90 and 126 W) and scan speed (700 and 1200 mm/s) on porosity formation in Co-Cr-Mo alloy. The final part density...
Abstract
Traditional processing methods for the part production of Co-Cr alloys include casting, powder metallurgy, and metal forming. However, the steps involved during materials processing followed by metal forming and machining are time consuming and fraught with processing variables. Three-dimensional (3D) printing enables rapid evolution in design, personalization, and so on. This article presents a brief description of some common additive manufacturing (AM) processes for the production of cobalt alloy parts, and provides a comparison between AM and conventional processing methods. The discussion is centered on process-microstructure-properties correlation in additively manufactured cobalt alloys and applications of these alloys.
Book Chapter
Computational Analysis of the Vacuum Arc Remelting (VAR) and Electroslag Remelting (ESR) Processes
Available to PurchaseSeries: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005510
EISBN: 978-1-62708-197-9
... in ESR are discussed as follows. VAR Process With dc power, Maxwell's equations reduce to a single equation for governing the distribution of the electric potential, ϕ, in the ingot: (Eq 1) Electric potential: ∇ • ( σ ∇ ϕ ) = 0 The following boundary conditions for current...
Abstract
This article provides an overview of the studies on computational modeling of the vacuum arc remelting (VAR) and electroslag remelting (ESR) processes. These models involve the axisymmetric analysis of the electromagnetic, flow, heat-transfer, and phase-change phenomena to predict the pool shape and thermal history of an ingot using two-dimensional axisymmetric models for VAR and ESR. Analysis of segregation of alloying elements during solidification that gives rise to macrolevel compositional nonuniformity in titanium alloy ingots is also described. The article discusses the important features of the control-volume-based computational method to review the unique aspects of the processes. Measurement of the properties of alloys and slags is explained and an analysis of the process variants for improving the predictive accuracy of the models is presented.
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