Search Results for state

Eutectoid and peritectoid transformations are classified as solid-state invariant transformations. This article focuses primarily on the structures from eutectoid transformations with emphasis on the classic iron-carbon system of steel. It reviews peritectoid phase equilibria that are very common in several binary systems. The addition of substitutional alloying elements causes the eutectoid composition and temperature to shift in the iron-carbon system. The article graphically illustrates the effect of various substitutional alloying elements on the eutectoid transformation temperature and effective carbon content. The partitioning effect of substitutional alloying elements, such as chromium, manganese, and silicon, in pearlitic steel is also illustrated.

This article describes the fundamental aspects of three nondestructive evaluation (NDE) methods of solid-state welds in terms of operation principles. These methods are radiography, ultrasound, and eddy current methods. The article provides examples of these NDE techniques performed on various types of flaws resulting from solid-state welding processes.

This article provides a fundamentals-based description of solid-state resistance projection welding. It details simple analytical tools to understand the variety of mechanisms that occur during resistance projection welding. Factors relating to the quality of solid projection are discussed, in addition to an explanation of the mechanisms of bonding for solid projection welding. The article reviews how these mechanisms are affected by heat balance, current profile, and mechanical characteristics of the welding equipment. It also presents the design of projection welding mechanical systems.

This article discusses three distinct mechanisms of bonding for solid-state (forge) welding processes, namely, contaminant displacement/interatomic bonding, dissociation of retained oxides, and decomposition of the interfacial structure. It explains the processes that can be characterized as having two stages: heating and forging. The article also includes a table that illustrates weld strengths as a function of annealing temperature for a range of materials.

This article discusses the mechanical properties of soft-interlayer solid-state welds and the implications of these behaviors to service stress states and environments. It illustrates the microstructure of as-deposited coatings and solid-state-welded interlayers. The article reviews factors that affect the tensile loading of strength of soft-interlayer welds: the interlayer thickness, the interlayer strain, and the interlayer fabrication method. It also provides information on stress-corrosion cracking of interlayers and stress behavior of these interlayers during shear and multiaxial loading.

Solid-state transformations occurring in a weld are highly nonequilibrium in nature and differ distinctly from those experienced during casting, thermomechanical processing, and heat treatment. This article provides a description of the special factors affecting transformation behavior in a weldment. It reviews the heat-affected and fusion zones of single-pass and multi-pass weldments. The article also includes a discussion on the welds in alloy systems, such as stainless steels and aluminum-base, nickel-base, and titanium-base alloys.

This article focuses on the analyzing and modeling of stress-strain behavior of polycrystals of pure face-centered cubic (fcc) metals in the range of temperatures and strain rates where diffusion is not important. It presents a phenomenological description of stress-strain behavior and provides information on the physical background, alternative interpretations, and directions of research. The quantitative description of strain hardening of fcc polycrystals is provided. The article also discusses the modeling of stress-strain behavior in body-centered cubic metals, hexagonal metals, stage IV work hardening, and the various classes of single-phase alloys.

This article describes the mechanism, advantages and disadvantages, fundamentals, capabilities, variations, equipment used, and weldability of metals in solid-state welding processes, including diffusion bonding, explosion welding, friction welding, ultrasonic welding, upset welding, and deformation welding.

Solidification processing is one of the oldest manufacturing processes, because it is the principal component of metal casting processing. This article discusses the fundamentals of solidification of cast iron. Undercooling is a basic condition required for solidification. The article describes various undercooling methods, including kinetic undercooling, thermal undercooling, constitutional undercooling, and pressure undercooling. For solidification to occur, nuclei must form in the liquid. The article discusses the various types of nucleation: homogeneous nucleation, heterogeneous nucleation, and dynamic nucleation. It reviews the classification of eutectics based on their growth mechanism: cooperative growth and divorced growth. The article concludes with a discussion on the solidification structures of peritectics.

This article describes the high-temperature solid-state welding process used to join members of similar or dissimilar materials by three stages, namely, primary bonding, bond-surface extension, and elimination of the original joining surface. It lists the various advantages and disadvantages of the high-temperature solid-state welding process. The article discusses important process parameters for high-temperature solid-state welding, such as temperature, pressure, welding time, and welding atmosphere. It concludes with information on the application of the process in the fields of aerospace and nuclear engineering.

This article describes low-temperature solid-state welding processes in relation to the interlayer fabrication method, welding method, and welding parameters. The interlayer fabrication method is used to produce vacuum coated interlayers, electrodeposited interlayers, and foil interlayers. The article discusses welding methods, including uniaxial compression and hot isostatic pressing. The article provides information on the effect of base-metal surface finish on the tensile strength of joints solid-state welded using silver interlayers in tabular form and addresses the surface cleaning steps of base-metals.

Solid-state welding (SSW) processes are those that produce coalescence of the faying surfaces at temperatures below the melting point of the base metal being joined without the addition of brazing or solder filler metal. This article discusses the fundamentals of welding and joining materials via the application of a nonmelting process. The specific processes usually associated with the nonmelting process are discussed.

Solid-state transformations occurring in a weld are highly nonequilibrium in nature and differ distinctly from those experienced during casting, thermomechanical processing, and heat treatment. This article focuses on welding metallurgy of fusion welding of steels and highlights the fundamental principles that form the basis of many of the developments in steels and consumables for welding. Examples in the article are largely drawn from the well-known and relatively well-studied case of ferritic steel weldments to illustrate the special physical metallurgical considerations brought about by the weld thermal cycles and by the welding environment. The article provides information on welds in other alloy systems such as stainless steels and aluminum-base, nickel-base, and titanium-base alloys.

Soft-interlayer solid-state welds that join stronger base metals have unique mechanical properties that are of fundamental interest and may be of critical importance to designers. This article discusses the mechanical properties of soft-interlayer solid-state welds and the implications of these behaviors to service stress states and environments. It describes the tensile loading of soft-Interlayer welds in terms of the effect of interlayer thickness on stress, interlayer strain, time-dependent failure, effect of base-metal properties, and effect of interlayer fabrication method. The article concludes with a discussion on multiaxial loading.

A number of nondestructive evaluation (NDE) methods, such as radiography, ultrasound, and eddy current, are available to detect flaws in solid materials. This article describes the fundamental aspects of these NDE methods in terms of operation principles. It presents some examples of the methods performed on various types of flaws resulting from solid-state welding processes.