100 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.

In the 1983 film Flashdance, Alex Owens works by day as a steel mill welder in which American city?

Pittsburgh supplied many of the film's locations, and Jennifer Beals's welder-by-day heroine dreams of winning a place at the city's dance conservatory.

RMS Titanic's hull was held together by more than three million of which iron and steel fasteners?

Rivets held Titanic together because arc welding was still in its infancy, and the three million of them added more than 1,200 tonnes to the ship's weight.

Which comedian, nicknamed the Big Yin, was a welder in Glasgow's shipyards in the early 1960s?

Billy Connolly learned the boilermaker's trade at the Alexander Stephen and Sons yard in Linthouse, then gave it up late in the decade to become a folk singer.

Which Chicago sculpture, nicknamed The Bean, is made of 168 stainless steel panels welded together?

Cloud Gate was inspired by the look of mercury, and Anish Kapoor's 168 panels were polished until not a single join between them could be seen.

Which Spanish painter learned oxy-fuel welding from sculptor Julio González in the winter of 1927–28?

Pablo Picasso then collaborated with his teacher on the sculpture Woman in the Garden, which the two friends made between 1928 and 1930.

Welding galvanized steel can cause 'Monday morning fever', triggered by breathing the oxide of which metal?

Zinc is the protective layer on galvanized steel, and its fumes bring on flu-like symptoms that usually clear up within 24 to 48 hours.

Unimate, the first industrial robot, began welding parts onto cars in 1961 for which American company?

General Motors put the 4,000-pound arm to work at a New Jersey plant, sparing its workers a job that risked toxic fumes and lost limbs.

Welders mark cutting lines on steel with which soft mineral, whose marks stay visible under intense heat?

Soapstone is composed largely of talc and has been a carving medium for millennia, long before it found a place in the welding shop.

Which invisible radiation from a welding arc can sunburn uncovered skin after only a short time?

Ultraviolet light pours off an open arc so strongly that the neck and face burn too, which is why arc welders shield the whole face and not just the eyes.

Two pieces of metal laid edge to edge in the same plane form which of the five basic welding joints?

Butt joints suit automation: the two edges need so little preparation that they can be fed straight through automatic welding machines.

Which weld, roughly triangular in cross-section, joins two pieces of metal meeting at a right angle?

Fillet welds are so tied to their shape that the blueprint symbol for one is simply a small triangle.

What informal name do welders give the small pool of molten metal they steer along a joint?

Puddle behaviour follows the heat: the molten metal travels towards wherever the workpiece is hottest, and filler is added by dipping a rod into it.

What is the welding term for the small, unwanted droplets of molten metal thrown out around a weld?

Spatter does not weaken the joint, but it spoils the finish and adds cleaning costs, and too much current or too long an arc makes it worse.

As a welder moves the molten pool along a joint, the line of weld metal left behind is called what?

Bead width tells a gas welder how fast to travel: when the line grows too narrow, the torch is moving too quickly and has to slow down.

Which custom work-holding device clamps parts in exact position while they are welded?

Fixture design has to leave clearance for the torch to reach every joint, and robotic welding cells depend on one to hold each part in the same place.

Before welding thick steel, fabricators cut which angled edge so the weld reaches full depth?

Bevel edges let the weld reach right through the joint, and the thickest steel gets a J or U profile instead, which saves on filler metal.

A welding machine's duty cycle is the share of which time period it can run before overheating?

Ten minutes is the test window, so a welder rated at a 60% duty cycle can run for six minutes and then has to cool for four.

Damp welding rods can leave a steel weld prone to cracking because moisture releases which gas?

Hydrogen atoms are small enough to permeate solid steel, which is why welding rods are dried before use and special low-hydrogen types exist.

Auto-darkening welding helmets use a fast shutter based on which display technology?

Liquid crystal shutters, introduced in 1981, darken automatically the instant their sensors detect the bright welding arc.

Sheet metal thickness is traditionally given in which unit, where a bigger number means thinner metal?

Gauge numbers are not even consistent between metals: the same number means a different thickness in steel than in a nonferrous sheet.

Rolled metal thicker than about 6 mm is no longer classed as sheet and takes which name instead?

Plate is the heavy end of the scale, while at the other extreme the very thinnest sheets are classed as foil or leaf.

Aviation snips colour-code their grips: red cuts left and green cuts right, so which colour cuts straight?

Yellow marks the straight-cutting pair of these compound-leverage snips, which were first developed for cutting sheet in aircraft construction, hence the name.

In a sheet metal shop, which machine clamps a sheet along a straight line and folds it to an angle?

Brake users in Britain know the same bending machine as a sheet metal folder, or simply a folder.

Which tool lets a craftsperson roll flat sheet metal into compound curves, as on classic car panels?

English wheel work suits low volumes, so the tool survives in coachbuilding, car restoration, prototypes and aircraft skins.

What do carmakers call a car's welded sheet metal shell before any paint, engine or trim is added?

Body in white, or BIW, has a disputed origin: one account says early coachbuilt bodies were painted white before they received their final colour.

Which tool cuts sheet metal by punching out a rapid series of small pieces, with very little distortion?

Nibbler blades work like a tiny punch and die, removing small bits of metal and leaving a cut about 6 mm wide.

In sheet metal work, what is an edge folded flat back onto itself to hide burrs and add strength called?

Hem forming starts by bending the edge over to an acute angle, after which a flattening die presses it closed.

Which sheet metal process uses a punch to pull a flat blank into a die, forming a one-piece cup shape?

Deep drawing only earns the word 'deep' when the finished part is deeper than it is wide.

The 4130 steel tubing used for welded roll cages and bike frames takes its nickname from chromium and which metal?

Molybdenum supplies the 'moly' in chromoly, and the same 41xx family of steels turns up in gas bottles, flywheels and rifle barrels.

A powerful welding laser can vaporise a slender cavity down into the metal, known by which name?

Keyhole welding is a balancing act: the pressure of evaporating metal holds the cavity open while gravity and surface tension try to collapse it.

Which process passes sheet metal between two rotating discs that weld it in one continuous line?

Seam welding discs can keep rolling as each weld is made, or advance and pause for every weld in the intermittent version of the process.

Which pendulum test measures the energy a notched metal sample absorbs as it breaks?

Charpy testing dates from 1901, when Georges Charpy standardised an earlier pendulum method with a redesigned pendulum and a precisely notched specimen.

Which welding technique deposits a tough, wear-resistant metal layer onto a part such as a ploughshare?

Hardfacing roughly doubled the working life of ploughshares in one study, and it is used both on new parts and to rebuild worn ones.

What is the term for a weld made by melting the base metal alone, with no filler rod added?

Autogenous welds turn up in TIG work, where filler is normal but not required, and some other processes avoid filler altogether.

Which technique hammers a freshly made weld to relieve the stresses that build up as it cools?

Peening only eases stress at or near the weld's surface, and it hardens the metal too, a side effect that welders try to avoid.

Which weld defect leaves the base metal beside the weld thinner, reducing its cross-section and strength?

Undercut often comes from too much current, which melts the edges of the joint so they drain into the weld and leave a groove along its length.

What do welders call the unwanted deflection of a DC arc, often caused by magnetic forces around the weld?

Arc blow can begin at magnetic strengths as low as 10 gauss, and it tends to appear when the workpiece itself carries some residual magnetism.

What is the name for the hollow left at the end of a weld where the arc was broken off?

Crater cracks are the danger: they open up in the hollow when the welder ends the arc too early.

Which very hard form of steel, named after a German metallurgist, forms when hot steel is quenched?

Martensite honours Adolf Martens and can reach about 700 on the Brinell scale, far beyond the 400 or so of the hardest pearlitic steel.

Which Indian city has a famously rust-resistant pillar built by welding pieces of wrought iron together?

Delhi's pillar owes its rust resistance to a thin protective film that forms on its high-phosphorus iron.

Which ancient Greek historian credited Glaucus of Chios with discovering how to weld iron?

Herodotus gave Glaucus the credit, and the craftsman was known for an iron pedestal that he welded to hold a silver wine bowl at Delphi.

Which sword-making technique twists and folds layers of differing iron and steel into one decorated blade?

Pattern welding is often wrongly called Damascus steel, and it fell out of use in Europe by the end of the Viking era.

The Maurzyce Bridge, the world's first entirely welded road bridge, crosses a river in which country?

Poland's bridge showed what welding could save: Stefan Bryła's structure weighs 56 tonnes, where his earlier unwelded design would have topped 70.

Which Russian scientist created a continuous electric arc in 1802 and proposed using it to weld metals?

Vasily Petrov managed it by building the most powerful battery of his day, a voltaic pile of around 4,200 metal discs.

Which American sculptor, a wartime welder of locomotives and tanks, made the stainless steel Cubi series?

David Smith's Cubi XXVIII sold for $23.8 million in 2005, at the time a record for contemporary art at auction.

The verb 'weld' began in the 1590s as an altered form of which older verb meaning to boil or rise?

Well, as in water welling up from the ground, became 'weld' when a 'd' crept onto the end, possibly under the influence of its past form, 'welled'.

Miller Electric began in 1929 with a small arc welder built for rural power supplies in which US state?

Wisconsin remained home as Niels Miller's one-man operation in Appleton grew into one of the world's largest makers of arc welding equipment.

What name is given to the small pool of metal that melts and solidifies to form a spot weld?

Nugget size is what the operator is really setting: the voltage needed depends on the sheet's thickness and how large a fused spot is wanted.

Orbital welding, which circles an arc around a fixed tube, was invented to cure leaks on which rocket plane?

X-15 plumbing kept leaking fuel and hydraulic fluid, so Rodrick Rohrberg of North American Aviation devised a weld that travels right round the tube.

Which welded Liberty ship was launched in 1942 only 4 days and 15 hours after its keel was laid?

SS Robert E. Peary won a speed contest between shipyards, with around 250,000 parts assembled in under five days, though much fitting-out remained after launch.