page_title: Forge welding
section_title: Processes
hierarchical_section_title: Forge welding / Processes
caption_attribution_description: Français&#160;: Martinet du domaine du Fourneau Saint-Michel – Musée du Fer et de la metallurgie ancienne de Saint-Hubert (Belgique). English: Trip hammer of the St. Michael's Furnace property – Museum of Iron of Saint-Hubert (Belgium). Nederlands: Stoomhamer van het domein van Fourneau Saint-Michel – Ijzer Museum van Saint-Hubert (België). Walon: Maka do domin.ne do Fornê Sint-Michèl - Musée du fiêr di Sint-Houbêrt (Bèljike) / Maca do dominne do Fornea Sint-Mitchî, a Nåwinne
context_page_description: Forge welding is a solid-state welding process that joins two pieces of metal by heating them to a high temperature and then hammering them together. It may also consist of heating and forcing the metals together with presses or other means, creating enough pressure to cause plastic deformation at the weld surfaces. The process is one of the simplest methods of joining metals and has been used since ancient times. Forge welding is versatile, being able to join a host of similar and dissimilar metals. With the invention of electrical and gas welding methods during the Industrial Revolution, manual forge-welding has been largely replaced, although automated forge-welding is a common manufacturing process.
context_section_description: The most well-known and oldest forge-welding process is the manual-hammering method. Manual hammering is done by heating the metal to the proper temperature, coating with flux, overlapping the weld surfaces, and then striking the joint repeatedly with a hand-held hammer. The joint is often formed to allow space for the flux to flow out, by beveling or rounding the surfaces slightly, and hammered in a successively outward fashion to squeeze the flux out. The hammer blows are typically not as hard as those used for shaping, preventing the flux from being blasted out of the joint at the first blow.
  When mechanical hammers were developed, forge welding could be accomplished by heating the metal, and then placing it between the mechanized hammer and the anvil. Originally powered by waterwheels, modern mechanical-hammers can also be operated by compressed air, electricity, steam, gas engines, and many other ways. Another method is forge welding with a die, whereas the pieces of metal are heated and then forced into a die which both provides the pressure for the weld and keeps the joint at the finished shape. Roll welding is another forge welding process, where the heated metals are overlapped and passed through rollers at high pressures to create the weld. 
  Modern forge-welding is often automated, using computers, machines, and sophisticated hydraulic-presses to produce a variety of products from a number of various alloys. For example, steel pipe is often forge-welded during the manufacturing process. Flat stock is heated and fed through specially-shaped rollers that both form the steel into a tube and simultaneously provide the pressure to weld the edges into a continuous seam. 
  Diffusion bonding is a common method for forge welding titanium alloys in the aerospace industry. In this process the metal is heated while in a press or die. Beyond a specific critical-temperature, which varies depending on the alloy, the impurities burn out and the surfaces are forced together. 
  Other methods include flash welding and percussion welding. These are resistance forge-welding techniques where the press or die is electrified, passing high current through the alloy to create the heat for the weld. Shielded active-gas forge-welding is a process of forge welding in an oxygen-reactive environment, to burn out oxides, using hydrogen gas and induction heating.
caption: A mechanized trip hammer.
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