In the flux-cored arc welding (FCAW) process, the heat for welding is produced by an electric arc between a continuous filler metal electrode and a workpiece. This article discusses the advantages and disadvantages and applications of the FCAW process. It schematically illustrates the semiautomatic FCAW equipment used in the gas-shielded FCAW process. The article discusses the manufacture of flux-cored electrodes and the classification of electrodes, such as carbon and low-alloy steel electrodes, stainless steel electrodes, and nickel-base electrodes. The functions of common core ingredients in FCAW electrodes are listed in a table.

This article describes the process features, advantages, limitations, and applications of the flux cored arc welding (FCAW) as well as the equipment used in the process. Base metals, namely, carbon and low-alloy steels, stainless steels, and nickel-base alloys, welded by the FCAW process are reviewed. The article illustrates the manufacturing process for the electrodes used in FCAW and outlines the classification of carbon and low-alloy steel, stainless steel, and nickel-base electrodes.

Repair and maintenance of parts and components is carried out as a logical procedure that ensures the production of a usable and safe component or it can be approached haphazardly. This article describes the requirements and repair techniques of arc and oxyfuel welding processes to repair weld defects and structural failures. It further discusses the preliminary assessment and base-metal preparation involved in weld repair. Furthermore, the article provides information on the general repair guidelines that are followed to ensure successful weld repairs of both ferrous (carbon steels, cast irons, and stainless steels) and nonferrous (titanium) base metals.

Submerged arc welding (SAW) is suited for applications involving long, continuous welds. This article describes the operating principle, application, advantages, limitations, power source, equipment, and fluxes in SAW. It reviews three different types of electrodes manufactured for SAW: solid, cored, and strip. The article highlights the factors to be considered for controlling the welding process, including fit-up of work, travel speed, and flux depth. It also evaluates the defects that occur in SAW: lack of fusion, slag entrapment, solidification cracking, and hydrogen cracking. Finally, the article provides information on the safety measures to be followed in this process.

This article provides a discussion on the operation of various methods and sensors that have been used or have the potential to be used for on-line, real-time monitoring of localized corrosion. These include the electrochemical noise (ECN) method, nonelectrochemical methods, the galvanically coupled differential flow cell, galvanically coupled crevice cell, coupled multielectrode sensor, and electrochemical biofilm activity sensor.

Shielded metal arc welding (SMAW), commonly called stick or covered electrode welding, is a manual welding process whereby an arc is generated between a flux-covered consumable electrode and a workpiece. This article discusses the advantages and limitations and applications of the SMAW process and describes the equipment used. It provides information on various coated electrodes used in the SMAW process, including mild and low-alloy steel-covered electrodes, stainless steel covered electrodes, and nickel and copper alloys covered electrodes. It reviews weld schedules and procedures, as well as the variations of the SMAW process. The article concludes with information on the special applications of the SMAW process and safety considerations.

This article addresses consumable selection and procedure development for the welding of stainless steels. The WRC-1992 diagram and the Schaeffier diagram, are used to illustrate the rationale behind many filler-metal choices. The article discusses the basic metallurgy and base metals of five major families of stainless steels: martensitic stainless steels, ferritic stainless steels, austenitic stainless steels, precipitation-hardening (PH) stainless steels, and duplex ferritic-austenitic stainless steels. Stainless steels of all types are weldable by virtually all welding processes. The article describes the common arc welding processes with regard to procedure and technique errors that can lead to loss of ferrite control with the common austenitic stainless steel weld metals that are designed to contain a small amount of ferrite for protection from hot cracking. The arc welding processes include shielded-metal arc welding, gas-tungsten arc welding, and gas-metal arc welding.

This article describes general welding characteristics such as weld microstructure and weldability. The correlations of preheating and postweld heat treatment practices with carbon contents and welding characteristics of martensitic stainless steels are reviewed. The article contains a table that lists the electrodes and welding rods suitable for use as filler metals in the welding of martensitic stainless steels. It provides specific arc welding procedural recommendations for the commonly welded martensitic stainless steels. Martensitic stainless steel joining methods such as laser-and electron-beam welding, resistance welding, flash welding, and friction welding, are discussed.

Arc welding methods can be classified into shielded metal arc welding, flux-cored arc welding, submerged arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, plasma-metal inert gas (MIG) welding, and electroslag and electrogas welding. This article provides information on process capabilities, principles of operation, power sources, electrodes, shielding gases, flux, process variables, and advantages and disadvantages of these arc welding methods. It presents information about the arc welding procedures of hardenable carbon and alloy steels, cast irons, stainless steels, heat-resistant alloys, aluminum alloys, copper and copper alloys, magnesium alloys, nickel alloys, and titanium and titanium alloys.

Resistance welding (RW) encompasses a group of processes in which the heat for welding is generated by the resistance to the flow of electrical current through the parts being joined. The three major resistance welding processes are resistance spot welding (RSW), resistance seam welding (RSEW), and projection welding (PW). This article addresses the considerations for using these processes to join specific types of materials. It discusses the process variations, applicability, advantages, and limitations of these resistance welding processes. The article provides information on flash welding, high-frequency resistance welding, and capacitor discharge stud welding. It concludes with a discussion on resistance welding of stainless steels, aluminum alloys, and copper and copper alloys.

Cast iron can be described as an alloy of predominantly iron, carbon, and silicon. This article discusses the classification of cast irons, such as gray cast iron, white cast iron, malleable cast iron, ductile cast iron, and compacted graphite iron. It reviews the various special techniques, such as groove face grooving, studding, joint design modifications, and peening, for improving the strength of a weld or its fitness for service. The article discusses the need for postweld heat treatment that depends on the condition of the casting, possible distortion during subsequent machining, the desired finish of the machined surfaces, and prior heat treatment. It describes various welding process for welding cast irons, including oxyfuel welding, braze welding, shielded metal arc welding, gas metal arc welding, and gas-tungsten arc welding.

Plasma arc welding (PAW) can be defined as a gas-shielded arc welding process where the coalescence of metals is achieved via the heat transferred by an arc that is created between a tungsten electrode and a workpiece. This article focuses on the operating principles and procedures, current and operating modes, advantages, disadvantages, and applications of PAW. It discusses the personnel and equipment requirements, as well as the joints used in the process. The power source, plasma control console, water cooler, welding torch, and gas supply system for the plasma and shielding gases are also reviewed.

Electric arc cutting is used on ferrous and nonferrous metals for rough severing, such as removing risers or scrap cutting, as well as for more closely controlled operations. This article describes the operating principles, equipment selection, process variables, and safety measures recommended for plasma arc cutting and air carbon arc cutting. Special applications of electric arc cutting, including shape cutting, gouging, and underwater cutting, are also discussed. The article provides information on other electric arc cutting methods, namely, the exo-process and oxygen arc cutting. It concludes with information on the seldom-used electric arc cutting methods, such as shielded metal arc cutting, gas metal arc cutting, and gas tungsten arc cutting.

Plasma arc welding (PAW) can be defined as a gas-shielded arc welding process where the coalescence of metals is achieved via the heat transferred by an arc that is created between a tungsten electrode and a workpiece. This article discusses the melt-in mode and the keyhole mode of the PAW process, as well as the advantages and disadvantages. It describes the components of a basic PAW system, namely the power source, plasma control console, water cooler, welding torch, and gas supply system for the plasma and shielding gases. The article provides information on the applications of the PAW process and discusses the typical components and joints used. It concludes with information on personnel requirements and safety issues.

This article explores the use of the electrochemical and nonelectrochemical techniques for measuring the corrosion behavior of buried metals and the types of probes used. The electrical resistance technique is the main nonelectrochemical technique used for measuring corrosion rate. Electrochemical techniques discussed include linear polarization resistance, electrochemical noise, harmonic distortion analysis, electrochemical impedance spectroscopy, and hydrogen permeation. The principles of operation for the corrosion measuring techniques are described along with examples of their use in soils.

Plasma-metal inert gas (MIG) welding can be defined as a combination of plasma arc welding (PAW) and gas-metal arc welding (GMAW) within a single torch, where a filler wire is fed through the plasma nozzle orifice. This article describes the principles of operation and operating modes of plasma-MIG welding. It discusses the advantages and disadvantages of the plasma-MIG process. The article describes the components, including power sources and welding torches, of equipment used for the plasma-MIG process. It provides information on inspection and weld quality control and troubleshooting techniques. The article concludes with a discussion on the applications of the plasma-MIG process.

This article presents a brief history and the uses of the anodic protection technique. It compares anodic and cathodic protection and describes the design considerations of the anodic protection system. The article discusses the specific requirements of equipment required for anodic protection. It also explains the applications and economic aspects of anodic protection, with examples.

This article describes the process, advantages, limitations, applications, and equipment used for shielded metal arc welding (SMAW). It provides information on the types of electrodes, weld schedules, and welding procedures. The article explains the electrodes used in the SMAW process that have different compositions of core wire and a variety of flux-covering types and weights. It includes information on gravity and firecracker welding and discusses dry and wet types of underwater welding. Finally, the article reviews the safety considerations to be followed during SMAW.