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Forge welding is a welding
Welding

Welding is a fabrication or sculpture process that joins materials, usually metals or thermoplastics, by causing coalescence . This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes used in conjunction with heat, or by itself,...
 process of heating two or more pieces of metal
Metal

In chemistry, a metal is a chemical element whose atoms readily lose electrons to form positive ions , and form metallic bonds between other metal atoms and ionic bonds between nonmetal atoms....
 and then hammering them together. 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
Industrial Revolution

The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture, manufacturing, production, and transportation had a profound effect on the socioeconomics and cultural conditions in United Kingdom....
, forge welding has been largely replaced.

Forge welding between similar materials is caused by solid-state diffusion
Diffusion

Molecular diffusion, often called simply diffusion, is a net transport of molecules from a region of higher concentration to one of lower concentration by random molecular motion....
.






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Forge welding is a welding
Welding

Welding is a fabrication or sculpture process that joins materials, usually metals or thermoplastics, by causing coalescence . This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes used in conjunction with heat, or by itself,...
 process of heating two or more pieces of metal
Metal

In chemistry, a metal is a chemical element whose atoms readily lose electrons to form positive ions , and form metallic bonds between other metal atoms and ionic bonds between nonmetal atoms....
 and then hammering them together. 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
Industrial Revolution

The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture, manufacturing, production, and transportation had a profound effect on the socioeconomics and cultural conditions in United Kingdom....
, forge welding has been largely replaced.

Forge welding between similar materials is caused by solid-state diffusion
Diffusion

Molecular diffusion, often called simply diffusion, is a net transport of molecules from a region of higher concentration to one of lower concentration by random molecular motion....
. This results in a weld that consists of only the welded materials without any fillers or bridging materials.

Forge welding between dissimilar materials is caused by the formation of a lower melting temperature eutectic between the materials. Due to this the weld is often stronger than the individual metals.

The temperature required to forge weld is typically 50 to 90 percent of the melting temperature, steel
Steel

Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight , depending on grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten....
 welds at a lower temperature than iron
Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
. The metal may take on a glossy or wet appearance at the welding temperature, care must be taken to avoid overheating the metal to the point that it gives off spark
Spark

A spark is a small airborne ember or particle of red-hot matter.Spark may also refer to:In science:* An electric spark, usually with a flash and a sharp noise, may be:...
s from rapid oxidation (burning).

Applications

One of the most famous applications of forge welding is in the production of pattern-welded
Pattern welding

Pattern welding is the practice in sword and knife making of forming a blade of several metal pieces of differing composition that are forge welding together and twisted and manipulated to form a pattern....
 blades. During the process a billet
Billet (manufacturing)

Billet refers to a cast semi finished product. It is also referred to as ingot, particularly for smaller sizes. A billet is typically cast to a rectangular, hexagonal or round cross section compatible with secondary processing, e.g....
 of steel is repeatedly drawn out, folded back and welded upon itself. Another lesser known application was the manufacture of shotgun barrels. Metal wire was spooled onto a mandrel
Mandrel

A mandrel is either an object used to shape machined work; a tool manufacturing that grips or clamps materials to be machined; or a tool component that can be used to grip other moving tool components....
, and then forged into a barrel that was thin, uniform, and strong. Often such objects are acid etched to expose the underlying pattern of metal which is unique to each item and adds to their aesthetic appeal.

Flux

Often a flux
Flux (metallurgy)

In metallurgy, a flux is a chemical cleaning agent which facilitates soldering, brazing, and welding by removing oxidation from the metals to be joined....
 is used to keep the welding surfaces from oxidizing and producing a poor quality weld. The flux also mixes with the oxides that do form and lowers the melting temperature and the viscosity
Viscosity

Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness"....
 of the oxides. This enables the oxides to flow out of the joint when the two pieces are beaten together. A simple flux can be made from borax
Borax

Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid....
, sometimes with the addition of iron filings.

Early examples of flux used different combinations and various amounts of iron
Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
 fillings, borax, sal ammoniac
Sal ammoniac

Sal ammoniac is a rare mineral composed of ammonium chloride, NH4Cl. It forms colorless to white to yellow-brown crystals in the Cubic class....
, balsam
Balsam

Balsam is a term used for various pleasantly scented plant products. These are oily or gummy oleoresins, usually containing benzoic acid or cinnamic acid, obtained from the exudates of various trees and shrubs and used as a base for some botanical medicines....
 of copaiba
Copaiba

Copaiba is a stimulant oleoresin obtained from the trunk of several pinnate-leaved South American leguminous trees . The thick, transparent exudate varies in color from light gold to dark brown, depending on the ratio of resin to essential oil....
, cyanide
Cyanide

A cyanide is any chemical compound that contains the nitrile , which consists of a carbon atom chemical bond to a nitrogen atom. Inorganic cyanides are hydrogen cyanide salts in which cyanide is generally the anion CN-....
 of potash
Potash

Potash is the common name given to potassium carbonate and various mined and manufactured salts that contain the element potassium in water-soluble form....
, and soda phosphate
Phosphate

A phosphate, an inorganic chemical, is a Salt of phosphoric acid. Inorganic phosphates are mining to obtain phosphorus for use in agriculture and industry....
. The 1920 edition of Scientific American
Scientific American

Scientific American is a popular science science magazine, published since August 28, 1845, making it one of the oldest continuously published magazines in the United States....
 book of facts and formulae indicates a frequently offered trade secret as using copperas, saltpeter
Potassium nitrate

Potassium nitrate is a chemical compound with the chemical formula PotassiumNitrogenOxygen3. A naturally occurring mineral source of nitrogen, KNO3 constitutes a critical oxidation component of black powder/gunpowder....
, common salt
Salt

A salt, in chemistry, is defined as the product formed from the neutralisation reaction of acids and base . Salts are ionic compounds composed of cations and anions so that the product is electrically electric charge ....
, black oxide
Oxide

An oxide is a chemical compound contaning at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides....
 of manganese
Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a Oxidation state in nature , and in many minerals....
, prussiate of potash, and "nice welding sand".

See also

  • Pattern welding
    Pattern welding

    Pattern welding is the practice in sword and knife making of forming a blade of several metal pieces of differing composition that are forge welding together and twisted and manipulated to form a pattern....


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