Welding

Welding is a <a href="/facts/Fabrication_(metal)/7WLsJYXB">fabrication</a> process that joins materials, usually <a href="/facts/Metal/pqQVs8QU">metals</a> or <a href="/facts/Thermoplastic/5KJB8dwN">thermoplastics</a>, primarily by using high temperature to <a href="/facts/Melting/zhhDBo5V">melt</a> the parts together and allow them to cool, causing <a href="/facts/Fusion_welding/AM9H3ESg">fusion</a>. Common alternative methods include <a href="/facts/Solvent_welding/2ndqGfhN">solvent welding</a> (of thermoplastics) using chemicals to melt materials being bonded without heat, and solid-state welding processes which bond without melting, such as pressure, <a href="/facts/Cold_welding/30B1C0Wg">cold welding</a>, and <a href="/facts/Diffusion_bonding/I9oHjrfo">diffusion bonding</a>.
Metal welding is distinct from lower temperature bonding techniques such as <a href="/facts/Brazing/JBgswMLw">brazing</a> and <a href="/facts/Soldering/fod6dLHD">soldering</a>, which do not melt the base metal (parent metal) and instead require flowing a <a href="/facts/Filler_metal/bC80LdUf">filler metal</a> to solidify their bonds.
In addition to melting the base metal in welding, a filler material is typically added to the joint to form a pool of molten material (the <a href="/facts/Weld_pool/BBc13b1Y">weld pool</a>) that cools to form a joint that can be stronger than the base material. Welding also requires a form of shield to protect the filler metals or melted metals from being contaminated or <a href="/facts/Oxidation/Pyd5RVcj">oxidized</a>.
Many different energy sources can be used for welding, including a gas flame (chemical), an <a href="/facts/Electric_arc/1hUPPAG0">electric arc</a> (electrical), a <a href="/facts/Laser/jk6PTvvT">laser</a>, an <a href="/facts/Electron_beam_welding/4WqClz4q">electron beam</a>, <a href="/facts/Friction_welding/7d8gNbFT">friction</a>, and <a href="/facts/Ultrasound/31Pa5IH9">ultrasound</a>. While often an industrial process, welding may be performed in many different environments, including in open air, <a href="/facts/Underwater_welding/aKySNKtE">under water</a>, and in <a href="/facts/Outer_space/R3LRKyFs">outer space</a>. Welding is a hazardous undertaking and precautions are required to avoid <a href="/facts/Burn/EHdVoSxB">burns</a>, <a href="/facts/Electric_shock/LmUdx0Ew">electric shock</a>, vision damage, inhalation of poisonous gases and fumes, and exposure to <a href="/facts/Ultraviolet_radiation/kncBUqn5">intense ultraviolet radiation</a>.
Until the end of the 19th century, the only welding process was <a href="/facts/Forge_welding/5YKY05fW">forge welding</a>, which <a href="/facts/Blacksmith/StvqhmLx">blacksmiths</a> had used for millennia to join iron and steel by heating and hammering. <a href="/facts/Arc_welding/SFDgoY2g">Arc welding</a> and <a href="/facts/Oxy-fuel_welding/Vkucvxsy">oxy-fuel welding</a> were among the first processes to develop late in the century, and <a href="/facts/Electric_resistance_welding/zURpqzUh">electric resistance welding</a> followed soon after. Welding technology advanced quickly during the early 20th century, as world wars drove the demand for reliable and inexpensive joining methods. Following the wars, several modern welding techniques were developed, including manual methods like <a href="/facts/Shielded_metal_arc_welding/DHSg8UGJ">shielded metal arc welding</a>, now one of the most popular welding methods, as well as semi-automatic and automatic processes such as <a href="/facts/Gas_metal_arc_welding/1dgt9j4B">gas metal arc welding</a>, <a href="/facts/Submerged_arc_welding/IMFLk4ce">submerged arc welding</a>, <a href="/facts/Flux-cored_arc_welding/k4pK3cWm">flux-cored arc welding</a> and <a href="/facts/Electroslag_welding/D1NzoLxX">electroslag welding</a>. Developments continued with the invention of <a href="/facts/Laser_beam_welding/lomhBTaP">laser beam welding</a>, <a href="/facts/Electron_beam_welding/4WqClz4q">electron beam welding</a>, <a href="/facts/Magnetic_pulse_welding/LleVxuCB">magnetic pulse welding</a>, and <a href="/facts/Friction_stir_welding/2P4zFmVl">friction stir welding</a> in the latter half of the century. Today, as the science continues to advance, <a href="/facts/Robot_welding/rB9hq7up">robot welding</a> is commonplace in industrial settings, and researchers continue to develop new welding methods and gain greater understanding of weld quality.

Welding open-in-new

Welding