The plasma carburizing process is basically a low-pressure carburizing process making use of a high-voltage electrical field applied between the load to be treated and the furnace wall producing activated and ionized gas species responsible for carbon transfer to the workpieces. This article begins with an overview of the theoretical background and the range and limitations of glow-discharge plasma. It describes the plasma carburizing process, which is carried out with methane or propane. Plasma carburizing processes of sinter metals and stainless steels, and the influence of current pulse length on carbon input of low-pressure carburizing process are also described. The article presents the basic requirements and process parameters to be considered in plasma carburizing equipment. It also exemplifies a still-working plasma process in industrial measure.

This article provides members of the thermal spray community with practical recommendations for the safe installation, operation, and maintenance of gas equipment used in the thermal spray process. It focuses on safety issues concerning gas equipment used in conjunction with thermal spray equipment at consumer sites. The article covers the gas sources (bulk or gaseous), the piping (hard and soft) leading to the gas console or the torch, and the specific safety devices used to help ensure safe operation. It discusses the characteristics and safety hazards of gases such as oxygen, compressed air, nitrogen, helium, argon, carbon dioxide, hydrogen, acetylene, kerosene, propylene, propane, and natural gas. The article also provides information on the maintenance and safety practices involved in the plumbing configurations of cylinder gas supply units and bulk gas supply units.

Oxyfuel gas cutting (OFC) includes a group of cutting processes that use controlled chemical reactions to remove preheated metal by rapid oxidation in a stream of pure oxygen. This article discusses the operation principles and process capabilities of the OFC. It reviews the properties and compositions of fuel types such as acetylene, natural gas, propane, propylene, and methyl-acetylene-propadiene-stabilized gas. The article describes the effects of OFC on base metal, including carbon and low-alloy steels, cast irons, and stainless steels. It provides information on light cutting, medium cutting, heavy cutting, and stack cutting. The article informs that the basic oxyfuel method can be modified to allow gas cutting of metals, such as stainless steel and most nonferrous alloys, that resist continuous oxidation.

This article contains a table that lists the properties of various fuel gases, namely, acetylene, hydrogen, methane, methyl acetylene propadiene, propane, propylene, and natural gas. It discusses shielding gases, their mixtures and uses in gas metal arc welding, flux cored arc welding, gas tungsten arc welding, and plasma arc welding.

Oxyfuel gas welding (OFW) is a manual process in which the metal surfaces to be joined are melted progressively by heat from a gas flame, with or without a filler metal. This article discusses the capabilities, advantages, and limitations of OFW. It describes the role of gases, such as oxygen, acetylene, hydrogen, natural gas, propane, and proprietary gases, in OFW. The article discusses the important elements of an OFW system, such as gas storage facilities, pressure regulators, hoses, torches, related safety devices, and accessories. It describes the sequence for setting up a positive-pressure welding outfit. The article provides information on forehand welding and backhand welding, as well as various joints used. It concludes with a discussion on repairs and alterations, as well as the safety aspects.

Flame hardening is a heat treating process in which a thin surface shell of a steel part is heated rapidly to a temperature above the critical temperatures of the steel. The versatility of flame-hardening equipment and the wide range of heating conditions obtainable with gas burners, often permit flame hardening to be done by a variety of methods. These include the spot or stationary method, progressive method, spinning method, and the combination progressive-spinning method. This article provides information on fuel gases used in flame hardening and their selection criteria for specific applications. It also discusses operating procedures and control requirements for flame hardening of steel.

Torch brazing utilizes a fuel gas flame as a heat source for the brazing process. This article discusses the advantages, limitations, applications, and key techniques of torch brazing, and presents an overview of the equipment used.

Torch soldering utilizes a fuel gas flame as the heat source in the soldering process to produce a leak-tight assembly with some degree of mechanical strength. This article describes the advantages, limitations, and applications of torch soldering. It reviews the equipment used and the basic heating techniques required for the soldering.

This article discusses the important characteristics of fluidized beds. The total space occupied by a fluidized bed can be divided into three zones: grid zone, main zone, and above-bed zone. The article discusses the various types of atmospheres of fluidized beds, such as oxidizing and decarburizing atmosphere; nitrocarburizing and nitriding atmosphere; carburizing and carbonitriding atmosphere; and chemical vapor deposition atmosphere. External resistance heating, external combustion heating, internal resistance heating, direct resistance heating, submerged combustion heating, and internal combustion heating can be used to achieve the heat input for a fluidized bed. The article also describes the operations, design considerations, and applications of fluidized-bed furnaces in heat treating. Thermochemical surface treatments, such as carburizing, carbonitriding, nitriding, and nitrocarburizing, are also discussed. Finally, the article reviews the principles and applications of fluidized-bed heat treatment.

Low-pressure carburizing (LPC) is one of the most popular case-hardening processes and is applied to increase the fatigue limit of dynamically loaded components. It takes place in a pressure range between 5 and 15 mbar (4 and 11 torr) and at temperature range between 870 and 1050 deg C. The LPC process runs in two different types of equipment: single-chamber furnaces and treatment chambers. This article reviews the use of simulation software for prediction of carbon profiles and typical quality control procedures. It describes the physical principles and typical applications of LPC.

This article describes the effects of furnace atmospheric elements on steels. These elements are air, water vapor, molecular nitrogen, carbon dioxide, and carbon monoxide. The article provides useful information on six groups of commercially important prepared atmospheres classified by the American Gas Association on the basis of method of preparation or on the original constituents employed. These groups are designated and defined as follows: Class 100, exothermic base; Class 200, prepared nitrogen base; Class 300, endothermic base; Class 400, charcoal base; Class 500, exothermic-endothermic base; and Class 600, ammonia base. These are subclassified and numerically designated to indicate variations in the method by which they are prepared. The article also contains a table that lists significant furnace atmospheres and their typical applications.

This article discusses the fundamentals and applications of localized heat treating methods: induction hardening and tempering, laser surface transformation hardening, and electron-beam heat treatment. The article provides information about equipment and describes the selection of frequency, power, duration of heating, and coil design for induction hardening. The article also discusses the scope, application, methods, and operation of flame hardening.

Case hardening is defined as a process by which a ferrous material is hardened in such a manner that the surface layer, known as the case, becomes substantially harder than the remaining material, known as the core. This article discusses the equipment required, process variables, carbon and hardness gradients, and process procedures of different types of case hardening methods: carburizing (gas, pack, liquid, vacuum, and plasma), nitriding (gas, liquid, plasma), carbonitriding, cyaniding and ferritic nitrocarburizing. An accurate and repeatable method of measuring case depth is essential for quality control of the case hardening process and for evaluation of workpieces for conformance with specifications. The article also discusses various case depth measurement methods, including chemical, mechanical, visual, and nondestructive methods.

This article discusses the operating principles, types, and applications of shearing and slitting of different forms of steel, including plates, flat sheets, bars, coiled sheet and strips. In addition, it provides a detailed account of the cutting methods such as oxyfuel gas cutting, plasma arc cutting, oxygen arc cutting, laser beam cutting, and air carbon arc cutting and gouging, describing their process capabilities, equipment used, operating principles and parameters, and factors affecting their efficiency.

This article illustrates the role that fracture mechanics can play in failure analysis. It describes the important failure criteria as relations between design and materials factors, which are used to correlate fracture mechanics analysis to the observations of a failure analysis. Descriptions include an indication of how the factors are typically evaluated. The article also provides information on subcritical fracture mechanics. Finally, a group of failure analysis examples explain how fracture mechanics parameters can be determined and how they may be fitted into an overall failure investigation.