Friction welding is based on the rapid introduction of heat, causing the temperature at the interface to rise sharply and leading to local softening. This article illustrates the basic principles of direct-drive rotational friction welding and inertia friction welding. Modeling the effective friction response of the materials is central to simulating the welding process. The article discusses a series of distinct frictional stages during continuous drive friction welding. Modeling of the evolution of the thermal field has been an important objective since the early days of rotational friction welding. The article describes analytical thermal models and numerical thermal models for rotational friction welding. It concludes with information on the modeling of residual stresses.

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 provides information on radial friction welding, which adopts the principle of rotating and compressing a solid ring around two stationary pipe. The process evolution of this welding is illustrated. The article also examines the equipment used and operating steps. It also illustrates a prototype of radial friction-welding machine and concludes with a discussion on applications that would be suitable for radial friction welding.

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 focuses on friction stir welding (FSW), where frictional heating and displacement of the plastic material occurs by a rapidly rotating tool traversing the weld joint. Much of the research activity early on pertained to issues related to understanding the process, such as learning about material flow, heat generation, microstructure development, and many other fundamental issues. The article summarizes the results of the research, describing the aspects of how FSW actually accomplishes sound joints in metals without melting them. It discusses the FSW process variations and the practical aspects of heat generation. The article provides information on the effect of welding on material properties and typical alloys in FSW applications. The alloys include 6061 aluminum, 5083 aluminum, 2xxx aluminum, and 7xxx aluminum alloys. The article concludes with a discussion on FSW equipment.

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.

This article lists the system parameters of the friction welding process and describes the four categories of monitoring and control of the manufacturing process. It discusses the monitoring methods of a rotary friction welded sample, for determining in-process quality of ferrous alloys, and dissimilar metals using acoustic emission. The article reviews the feasibility of detecting the presence of ferrite during microstructural evolution of friction welding of three austenitic stainless steels: 310, 304, and 255. It also explains the in-process quality control of friction welding.

Friction welding (FRW) is a solid-state welding process in which the heat for welding is produced by the relative motion of the two interfaces being joined. This article describes two principal FRW methods: direct-drive welding and inertia-drive welding. The direct-drive FRW uses a motor running at constant speed to input energy to the weld. The inertia-drive FRW uses the energy stored in a flywheel to input energy to the weld. The article summarizes some of the metals that have been joined by FRW and discusses the metallurgical considerations that govern the properties of the resulting weld. It also presents a schematic illustration of the effect of welding parameters on the finished weld nugget obtained when similar metals are welded using inertia-drive FRW equipment.

Friction welding (FRW) is a solid-state welding process in which the heat for welding is produced by the relative motion of the two interfaces being joined. This article provides an outline of the mechanisms of friction heating and discusses the two principal FRW methods: direct-drive welding and inertia-drive welding. It summarizes the similar and dissimilar metals that can be joined by FRW and discusses the metallurgical considerations that govern the properties of the resulting weld.

In the friction surfacing process, a rotating consumable is brought into contact with a moving substrate, which results in a deposited layer on the substrate. This article describes the process as well as the equipment used. It also provides information on the applications of the friction surface process.

Friction stir welding (FSW) involves plastic deformation at high strain rates and elevated temperatures with resultant microstructural changes leading to joining. This article provides a link between deformation and FSW process parameters and summarizes the results of experimental temperature measurements during FSW of various metals. It considers the physical explanation of the heat input during FSW and the possible methods of their estimation. The article presents the experimental results of two analytical models, supplemented by experimental/numerical flow models on material flow during FSW. The types of defects, processing parameters affecting the generation of these defects, and results of theoretical models and simulations to understand the formation and control of defects during FSW are discussed. The article concludes with information on the microstructure and its distribution produced during FSW.

The friction surfacing process enables deposition of a wide variety of high-specification materials with an ideal metallurgical bond onto a range of metal substrates. This article provides a process description and discusses the equipment used for, and the applications of, friction surfacing.

This article discusses the fundamentals of friction stir welding (FSW) and presents governing equations and an analytical solution for heat transfer. It provides the solutions for structural distortion in FSW. The article describes various techniques that have been adopted to solve the equations and simulate the FSW process. The techniques include modeling without convective heat transfer and modeling with convective heat transfer in a workpiece. The article concludes with information on active research topics in the simulation of FSW.

This article discusses the application of friction stir processing (FSP) and friction surfacing for tribological components. It describes the three critical aspects involved in the application of FSP for near-surface material modifications intended for tribological applications. These include tools, processing parameters, and machines. The article also discusses the equipment and processing parameters for friction surfacing. It describes various hybrid stir processing techniques that involve preheating of the workpiece material, especially relatively hard and high-strength ones. The article presents a partial list of surface-modification methods based on FSP. The partial list includes surface hardening, surface composites, and additive coating. The article also provides information on generation of residual stresses in metallic materials and alloys form different variants of FSP.