Search Results for direct heat source

Three types of energy are used primarily as direct heat sources for fusion welding: electric arcs, laser beams, and electron beams. This article reviews the physical phenomena that influence the input-energy distribution of the heat source for fusion welding. It also discusses several simplified and detailed heat-source models that have been used in the modeling of arc welding, high-energy-density welding, and resistance welding.

This article provides general information on the definition, purposes, and quench equipment for direct-forge quenching (DFQ) and direct heat treatment (DHT) processes that are widely used in automotive and various other mechanical industries. It discusses the technological advances in these processes and their ability to produce high-quality components at low production cost from microalloyed steels. Further, the article describes the influence of carbon contents on toughness of microalloyed direct heat treated steels. It focuses on the DFQ and DHT steel technologies applied in continuous rolling mills to produce various DHT steels for machining and cold forming applications.

This article reviews the classical models for the pseudo-steady-state temperature distribution of the thermal field around moving point and line sources. These include thick- and thin-plate models and the medium-thick-plate model. The analytical solutions to the differential heat flow equation under conditions applicable to fusion welding are provided. The article also provides an overview of the factors affecting heat flow in a real welding situation using the analytical modeling approach because this makes it possible to derive relatively simple equations that provide the required background for an understanding of the temperature-time pattern.

Friction welding (FRW) can be divided into two major process variations: direct-drive or continuous-drive FRW and inertia-drive FRW. This article describes direct-drive FRW variables such as rotational speed, duration of rotation, and axial force and inertia-drive FRW variables such as flywheel mass, rotational speed, and axial force. It lists the advantages and limitations of FRW and provides a brief description on categories of applications of FRW such as batch and jobbing work and mass production. A table of process parameters of direct-drive FRW systems relative to inertia-drive FRW systems is also provided.

This article briefly reviews the physical phenomena that influence the input-energy distribution. It discusses the several simplified and detailed heat source models used in the modeling of arc welding, high-energy-density welding, and resistance welding processes.

This article provides an overview of the components of a resistance welding machine. It focuses on the single-phase control system and medium-frequency direct current system of resistance welding. The article also includes information on their feedback systems, rectification systems, and power sources.

Distortion, encompassing all irreversible dimensional changes, is of two main types: size distortion and shape distortion. This article provides an overview of the nature and causes of distortion and discusses the process and material aspects of distortion specific to steels and tool steels. It also discusses the prediction of distortion and residual stresses by heat treatment simulation for optimizing production processes. The advantages and limitations of heat treatment simulation are also described.

This article provides the basics of overall quench process distortion. It describes the influence of quenching processes on the generation of distortion. Examples for the distortion behavior of different types of components are presented. Then, comparisons between different quenching processes are provided. The article presents some possibilities for minimization of shape changes by the quenching process itself. Several suggestions are given for quenching processes in evaporating fluids. An example is provided for out-of-roundness reduction for rings by well-defined inhomogeneous quenching in a gas nozzle field. Another example shows how intensive and high-speed quenching can help to reduce the bending of shafts with an asymmetrical cross-section. The last example shows the result when external loads and nonsymmetric quenching act together. The article also presents test samples for the judgment about distortion potential arising from heat treatment equipment.

This article presents a detailed account of directed-energy deposition (DED) processes that are used for additive manufacturing (AM) of metallic materials. It begins with a process overview and a description of the components of DED systems followed by sections providing information on the process involved in DED and the materials used for DED. The postprocessing applied to the material after deposition is then covered. The article discusses the properties of metallic materials produced by using DED and ends with a discussion on applications for DED processes in various industries.

This article summarizes how the tensile properties of several key metal alloy systems commonly used in additive manufacturing (AM) compare against their traditionally manufactured counterparts, which process parameters can be manipulated to enable more optimized performance, the role that process-induced artifacts play in influencing tensile behavior, and how postprocessing can be employed to overcome any anomalies induced during manufacture. Popular specific grades include type 316L and 17-4PH stainless steels, AlSi10Mg, Scalmalloy, Inconel 625 and 718, H13 tool steel, Ti-6Al-4V, and cobalt-chromium.

This article is a compilation of tables summarizing the fusion welding process. Included in the article is a table that presents the various fusion welding and cutting processes and their applications. Information on the general characteristics of arc welding processes is tabulated. The article also contains a list of the various criteria for selecting the suitable welding process for carbon steels.

Laser deposition involves the articulation of a laser beam and the introduction of material into the beam path to fuse the material onto a substrate or into a functional shape. It can be divided into two broad categories: cladding and near-net shape processing. This article provides a discussion on the material combinations, characteristics of laser cladding, and the comparison with arc cladding. It reviews the characteristics and applications of near-net shape processing and explains the process involved in powder bed methods and direct powder methods.

This datasheet provides information on composition limits, fabrication characteristics, processing effects on physical and mechanical properties, and applications of the high-strength extrusion aluminum alloy 6069.

This article provides information on the practice considerations for the inertia and direct-drive rotary friction welding processes. It presents the tooling and welding parameter designs of these processes. The article discusses the welding of different material family classes to provide a baseline for initial development of a welding parameter set. Common material family classes, including steels, nonferrous metals, and dissimilar metals, are discussed.

Fusion-based additive manufacturing (AM) processes rely on the formation of a metallurgical bond between a substrate and a feedstock material. Energy sources employed in the fusion AM process include conventional arcs, lasers, and electron beams. Each of these sources is discussed, with an emphasis on their principles of operation, key processing variables, and the influence of each source on the transfer of heat and material. Common energy sources used for metals AM processes, particularly powder-bed fusion and directed-energy deposition, are also discussed. Brief sections at the end of the article discuss the factors dictating the choice of each of these energy sources and provide information on alternative sources of AM.

Friction welding (FRW) is a solid-state welding process that uses the compressive force of the workpieces that are rotating or moving relative to one another, producing heat and plastically displacing material from the faying surfaces to create a weld. This article reviews practice considerations for the two most common variations: inertia welding and direct-drive friction welding. Direct-drive friction welding differs from inertia welding, primarily in how the energy is delivered to the joint. The article discusses the parameter calculations for inertia welding and direct-drive friction welding. It provides information on friction welding of carbon steels, stainless steels, aluminum-base alloys, and copper-, nickel-, and cobalt-base materials.

This article reviews the performance of power electronics components, namely, power rectifiers, insulated-gate bipolar transistors, metal-oxide semiconductor field-effect transistors, diodes, and silicon-controlled rectifiers. It provides information on induction heating power supplies with multiple heat stations, such as switching units and multiple (zone) outputs. The article describes power supply operational control and power supply protection circuits. It details duty cycle, power factor, and harmonics of power supplies. The article also describes system parameters, software analysis-calculations, human analysis-decisions, multiple system arrangements, and zone control systems for power supply selection. It provides information on the maintenance of induction power supplies, detailing the safety precautions to be taken and the need for routine inspection and servicing.

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.