50 Fun Facts About Welding

Until the late 19th century, what was the only welding process for iron and steel?

Forge welding, heating iron and hammering the pieces together, was the only welding method for millennia. The Iron Pillar of Delhi, from around 400 CE, was forge-welded.

The earliest known welding dates to which period?

The Bronze Age: small gold boxes made with pressure-welded lap joints survive from that period. Forge welding of iron came later, in the Iron Age.

Which scientist discovered the short-pulse electric arc in 1800, laying the groundwork for arc welding?

Humphry Davy presented the results in 1801 and rediscovered the continuous arc in 1808, unaware that Vasily Petrov had already done so in Russia.

Nikolay Benardos introduced the first practical arc welding method in 1881. What kind of electrodes did it use?

He developed it with Polish engineer Stanisław Olszewski in a French lab; they received a British patent in 1885. He called the process Elektrogefest.

The first patents for resistance welding, in 1885, went to which American inventor?

Elihu Thomson received the first resistance-welding patents in 1885 and kept improving the process for 15 years. His Thomson-Houston company merged into General Electric in 1892.

Oxygen-acetylene welding was first developed in 1903 by engineers from which country?

France's Edmond Fouché and Charles Picard developed it in 1903; acetylene itself had been discovered by Edmund Davy in 1836.

An oxy-acetylene flame burns at roughly what temperature?

An oxy-acetylene flame reaches about 3,500 °C (roughly 6,300 °F), the hottest common fuel-gas flame and well above an oxyhydrogen flame at around 2,800 °C.

What is the chemical formula of acetylene?

Acetylene is C2H2, systematically named ethyne, with a triple bond joining its two carbon atoms. It is usually produced from calcium carbide and water.

Around 1900, Oscar Kjellberg and Arthur Strohmenger introduced what innovation to arc welding?

The first coated electrodes: Kjellberg dipped iron wire in carbonates and silicates, Strohmenger used clay and lime, and Kjellberg went on to found ESAB.

What is the informal name for SMAW, the manual process that uses a flux-coated consumable electrode?

Stick welding: the welder hand-feeds a rod-shaped, flux-coated electrode, and the burning flux protects the weld. Its portability made it the staple process for field repair and maintenance work.

In stick welding, what two protective by-products come from the electrode's disintegrating flux coating?

Shielding gas and slag both keep atmospheric contamination out of the molten pool; the slag is chipped off afterwards.

MIG and MAG are subtypes of which process?

Gas metal arc welding covers both: MIG uses an inert gas, MAG an active one like CO2, and the arc forms between a consumable wire electrode and the workpiece.

Gas metal arc welding was developed in 1948 by which US research organisation?

The Battelle Memorial Institute in Columbus, Ohio developed gas metal arc welding in 1948. Early versions needed costly inert gas, so the process was first used mainly on aluminium and other non-ferrous metals.

The use of CO2 as a GMAW shielding atmosphere was developed in which year?

In 1953 carbon dioxide was introduced as a GMAW shielding gas. Far cheaper than argon or helium, it made the process economical for steel and drove its rapid spread.

TIG welding uses an electrode made of what?

A non-consumable tungsten electrode carries the arc while filler rod is added separately. TIG is slower and harder to master but ideal for thin stainless steel and aluminium.

Which shielding gas did Northrop's original 1941 TIG process use on magnesium aircraft parts?

Helium: Russell Meredith at Northrop devised the process in 1941 to weld the magnesium XP-56, and Linde sold it under the Heliarc name. Argon later became the usual shielding gas.

What is the melting point of the TIG-electrode metal, the highest of any element?

Tungsten melts at 3,422 °C (6,192 °F), the highest melting point of any element. It also has the lowest vapour pressure and the highest tensile strength of any pure metal.

Which noble gas is the most common inert shielding gas in welding?

Argon is chemically inert under almost all conditions and forms no confirmed stable compounds at room temperature, which is what makes it ideal for shielding.

In submerged arc welding, what is the arc 'submerged' beneath?

The flux is a mix of lime, silica, manganese oxide and calcium fluoride that becomes conductive when molten. The first patent dates from 1935.

Who invented friction stir welding at TWI in 1991?

Wayne Thomas devised it. A rotating non-consumable tool stirs the two pieces together in a solid state.

Electron-beam welding is usually performed in what environment?

The vacuum stops the beam scattering. German physicist Karl-Heinz Steigerwald built the first practical machine, operating from 1958.

Plasma arc welding was invented in 1957 by whom?

Robert Gage of Union Carbide invented plasma arc welding in 1957, the same year flux-cored arc welding debuted. Plasma cutting is a spin-off of the process.

Exothermic (thermite) welding heats metal using a reaction between a metal oxide and powdered what?

Powdered aluminium reduces the iron oxide in an aluminothermic reaction that yields molten iron at about 2,500 °C with no external power. Hans Goldschmidt patented the process in the 1890s.

Thermite welding is most widely used to join what?

The rail ends are preheated to orange heat with a torch so the molten steel is not chilled during the pour.

What temperature is the usual dividing line between soldering and brazing?

450 °C (840 °F) is the conventional boundary: below it the process is soldering, above it brazing. Both use a filler that melts below the base metal, unlike welding, which melts the parent metal.

In brazing, what draws the molten filler metal into the joint?

Capillary action pulls the molten filler into the gap; clearances of 0.03 to 0.08 mm give the best flow. Braze welding, by contrast, deposits filler without relying on capillary action.

Spot-welding electrodes are usually made from which low-resistance metal?

Copper-alloy electrodes conduct current well and carry off heat, so the metal melts only at the contact point between the sheets. Water cooling keeps the electrodes themselves from softening.

The modern welding helmet was first introduced in 1937 by which company?

Willson Products, a safety-equipment maker in Reading, Pennsylvania, introduced the modern welding helmet in 1937. Before that, welders relied on hand-held shields or simple goggles.

The first auto-darkening welding filter, Speedglas (1981), came from which country?

Sweden: Hornell International of Gagnef launched the Speedglas LCD shutter in 1981, darkening the instant its sensors detect the arc. 3M bought the company in 2004.

The painful eye condition welders call 'arc eye' is medically known as what?

Photokeratitis is essentially sunburn of the cornea from ultraviolet light. Skiers and mountaineers get the same condition, called snow blindness, from glare off snow.

The American Welding Society was founded in which year?

The American Welding Society was founded in 1919, when Comfort Adams brought industry leaders together after the First World War; he served as its first president.

Which shipbuilder launched the first ocean-going ship with an entirely welded hull, the Fullagar?

Cammell Laird of Birkenhead launched the Fullagar in 1920, the first ocean-going vessel with an entirely welded hull, after British yards turned to arc welding during the First World War.

How many welded Liberty ships did American yards build between 1941 and 1945?

2,710 Liberty ships came from 18 American shipyards between 1941 and 1945, roughly three every two days; welding rather than riveting made that pace possible.

Cambridge scientist Constance Tipper showed that Liberty ship fractures were caused by what?

The cracks did not start in the welds; below a certain temperature the steel simply switched from ductile to brittle.

Underwater hyperbaric welding was invented in 1932 by a metallurgist from which country?

Konstantin Khrenov. 'Wet' welding happens in the water itself; 'dry' hyperbaric welding uses a pressurised enclosure.

Welding was first attempted in space in 1969 by cosmonauts on which mission?

Soyuz 6's cosmonauts ran the Vulkan experiment in October 1969, testing electron-beam, plasma and consumable-electrode arc welding in a depressurised orbital module.

Cold welding, where clean metal surfaces bond in space, is blamed for a 1991 problem on which spacecraft?

Galileo's umbrella-like high-gain antenna jammed in April 1991 when several ribs stuck; cold welding of pins that had lost their lubricant was blamed, and the antenna never fully opened.

Which welding position is coded 4G in AWS welder qualification tests?

Overhead: AWS numbers the positions 1 flat, 2 horizontal, 3 vertical and 4 overhead, with G for groove and F for fillet welds, so a 4G test is a groove weld made from beneath the joint.

Ultrasonic welding of rigid plastics, patented in 1965, was first applied in which industry?

Toys: the toy industry was the first to adopt rigid-plastic ultrasonic welding. Robert Soloff and Seymour Linsley held the 1965 patent; Soloff had been sealing plastic films into bags at Branson Instruments.

The area next to a weld whose microstructure has been altered without melting is called what?

The heat-affected zone (HAZ) is base metal whose microstructure was changed by welding heat without melting. Hydrogen cracks there can appear up to two days after welding, so inspection is sometimes delayed.

Gas bubbles trapped in a solidified weld are a defect known by what name?

Porosity is the gas-inclusion defect; other weld defects include cracks, lack of fusion, incomplete penetration and undercutting.

In the AWS electrode classification E7018, what does the '70' indicate?

A minimum tensile strength of 70,000 psi: in E7018 the first two digits give weld-metal tensile strength in ksi, the '1' means all positions, and the '8' denotes a low-hydrogen, iron-powder coating.

On a welding symbol, what does a flag at the arrow-reference line junction mean?

Field weld: the flag tells the fabricator to make that weld on site rather than in the shop. A circle at the same junction means weld all around.

In arc welding, DC electrode positive (DCEP) is also known by what name?

Reverse polarity: the electrode is positive and the work lead negative. Most stick electrodes and solid-wire MIG welding run on DCEP, while TIG usually runs electrode negative, called straight polarity.

Which process joins materials by slamming them together under extremely high pressure?

Explosion welding: a detonation drives one plate onto the other so fast that the surfaces plasticise and bond with little heat, which is why it joins dissimilar metals such as aluminium to steel in ship hulls.

In what year was electroslag welding introduced?

1958: electroslag welding, developed at the Paton Institute in Kiev, was introduced that year, and its cousin electrogas welding followed in 1961. Both weld thick plate vertically in a single pass.

Roughly how many spot welds, mostly made by robots, does an ordinary car contain?

Several thousand spot welds go into an ordinary car, most of them made by industrial robots, which is why spot welding was the first big application of robot welding.

What is the name for the region of a weld where the filler metal was actually laid down?

The fusion zone is where filler and melted base metal solidified together; its properties depend mainly on the filler metal and its compatibility with the surrounding base material.

What is a small, short weld that holds parts in alignment before the final weld called?

Tack welds are small temporary welds that hold an assembly in alignment and resist distortion until the full weld is made; they are usually remelted and absorbed by the final pass.

Solvent welding joins thermoplastics using what instead of heat to melt the surfaces?

Chemicals melt the surfaces in solvent welding, one of several alternatives to fusion alongside solid-state methods like cold welding and diffusion bonding, which bond without melting.