For years, the problem of joining pieces of metal together had plagued our ancestors.  Bolts, rivets, and screws are all good, but they were not as strong as a fused joint.  There must have been a better way to create a joint between metal sections.  Since ancient civilizations knew that metals could melt, they knew there must be a way to fuse metals together to create a strong but seamless joint.  The process of welding was born.  Today welding has expanded into itself in many ways, becoming one of the most vital manufacturing and the single most essential construction process today (Cary pg. 1).  Welding is defined as “to unite (metallic parts) by heating and allowing the metals to flow together or by hammering or compressing with or without previous heating” (Merriam-Webster 2003).

Arc welding refers to "the process that uses an electric arc to join the metals being welded (Integrated Publishing 2003)".  The most typical variety of welding done today is shielded metal arc welding (Geary pg. 41).  There are several different variations of arc welding used.  These deviations can split this area down based on whether an electrode is consumed in the process (Cary pg. 22).  The basic principle is that a wire or rod either just transfers electricity or transfers electricity and melts to join in the weld as a filler metal.  This creates the difference in consumable and non-consumable electrodes.  As an AC or DC power supply gives power to the electrode, an electrical circuit is created by connecting a “hot cable” to the work and striking the electrode against the work.  As the electricity jumps to the work piece from the end of the electrode, the user pulls the electrode back just enough to keep an arc and to allow the metal from the electrode to jump to the work through the arc (Lincoln Electric Co. 2003).  This distance is usually around the diameter of the electrode (Mohler pg. 102).  As the electrode covering melts, a gas is created.  This gas is there to shield the arc from the outside, as well as keeping oxygen out so that the weld does not oxidize.  The flux that also melts as the electrode melts covers the weld to protect it from oxidation after the welding is done (Geary pg. 42).  The temperature of the arc reaches over 6000°F which melts the electrode and the edges of the metal workpiece.  Only around half of the heat created is actually transferred to the metal piece, while the rest is lost into the environment (Galvey, Marlow pg. 109).

A general schematic of an arc welding system. Lincoln Electric Company. (2003). Arc-welding fundamentals. Retrieved November 22, 2003 from http://content.lincolnelectric.com/graphics/knowledge/articles/content/arcweldfund1.jpg

History: 3000 B.C. It was around this time that the Sumerians joined metals together in a “hard soldering” process to create swords for battle.  In the tomb of Queen Pu-abi, several gold artifacts buried with her show signs of being brazed.  Also around this time, the Egyptian culture used charcoal fires to turn iron ore into sponge iron.  This was then beaten to weld the particles together, creating some of the first accounts of “pressure welding” (Sapp 2003).

Vulcan brings humans the knowledge of metallurgy. Timeless Myths. (2003). Roman Dieties. Retrieved December 1, 2003 from http://www.timelessmyths.com/classical/gallery/vulcan.jpg

1000 B.C.

        The first forge welding came along around 1000 B.C. (Sapp 2003).  This process involves heating the metals and then using pressure to bond the pieces together (Fogg 1997).  An archeological dig found iron and bronze artifacts that had been forge welded and dated from this time.  Four boxes made of gold were also found around this time in Ireland.  These boxes showed evidence of being pressure welded on some of the joints.  This was done through a hammering process that fused the pieces together (Sapp 2003).                                        

60 A.D.

        Around 60 A.D., an author named Pliny wrote about some of the information that he knew about welding.  He wrote about the brazing process for gold at this time and talked of the salts that were used for a flux mixture (Sapp 2003).  Brazing is defined as, “a process intended to permanently join two or more metals/materials together to form a single assembly by heating them in the presence of a filler metal that begins to melt above 450° C (840° F)” (Kay 2003).  Flux is a material used to melt and keep the metal from oxidizing (Fogg 1997).  Pliny also goes on to describe a way to determine how easily a metal will braze by looking at the metals color after it oxidizes (Sapp 2003).

400 A.D.

        The Iron Pillar in Delhi, India, is a monument to welding technology itself.  Created around 400 A.D. and weighing around six tons, this giant column is around 25 feet tall and 16 inches in diameter at the base.  Formed from iron billets, this column was fused together by forge welds.  This pillar is even more impressive when one realizes that the iron obtained for use at this time was harvested from meteors, and only in small quantities (Sapp 2003).

1776

        A scientist named Antoine Lavoisier discovered in 1776 that if an atmosphere were made entirely of oxygen, a metal could be burnt in that environment.  This experiment with oxygen lead to a belief that oxygen could be used to cut metals.  This left over metal oxide could also be melted at lower temperatures, showing a change in the state of the metal (Sapp 2003).

1801       Sir Humphrey Davy was also a leading scientist in the production of modern welding practices.  In 1802, Sir Humphrey created the first human created electric arc.  He used high voltage electricity and a pair of carbon rods and produced a change in one that jumped to the other.  This is now the basis for what is now known as arc welding (Hoyle 2003).  1846         A British scientist named James Nasmyth develops a uniform convex curve to the sides of metal pieces to be welded.  By doing this, the adhesion between the two metals starts at the middle and works its way out.  This helps in expelling the flux and other impurities out of the joint, instead of trapping them in which makes the joint weaker (Nasmyth 1997).

Sir Humphrey Davy Bachman, Michal. (2003). Davy, sir humphery. Retrieved December 1, 2003 from http://www.jergym.hiedu.cz/~bachmanm/images/davy.jpg

1856

        James Joule begins to experiment with a relatively new form of  power called electricity.  Through his experiments, James develops the first arc welding techniques in history (Roberge 2003).

1881

        A man named Augusta De Meritens used a form of arc welding to adhere two lead plates together to made a battery.  He worked along with another man named Nikolai N. Bendaros, who would later gain the patent for this welding process.  Known as carbon arc welding, Bendaros and another Russian scientist, Stanislaus Olszewski, would obtain patents for this variation of arc welding in various countries, including America and Britain in the next few years.  This type of welding would gain in popularity at the end of the 19th century and into the first years of the 20th century (Cary pg. 9).

1886

        Bendaros receives a patent from Russia for a form of carbon arc welding that actually could cut metal.  The process was named "Electrohefest" after the Greek god of Fire and Blacksmithing, Hephaestus (Sapp 2003).

1890

        C.L. Coffin discovers a method of transferring metal from a metal electrode to the joint to fill the gap in the joint.  For his work, Coffin was able to patent his idea, which was the first to use a metal electrode (Cary pg. 9).

1900         The refining of electrodes is still apparent in 1900, with different coatings being added to the bare metal electrodes.  Strohmenger developed a coating of clay or lime.  This helped to stabilize the arc better than a bare electrode.  Oscar Kjelberg also developed a coating around this time.  His electrodes consisted of short iron rods with a thick coating of carbonates and silicates to insulate the rod (Welding.com 2003).  By doing this, the coating would melt and protect the weld from oxygen and nitrogen (Sapp 2003). 1905

Oscar Kjelberg ESAB Welding and Cutting Products. (2003). The ESAB story. Retrieved December 1, 2003 from http://www.esabna.com/graphics/oscar.jpg

        After testing different types of electrolytic condensers and rectifiers, L. W. Chubb develops a way to join aluminum sheets together using charged wires to create an arc when the plates were close to each other while working for Westinghouse Electric and Manufacturing.  He also created a way to fuse copper plates together in the same way (Sapp 2003).

1907

        Two German-American Welding Companies begin in the United States.  One of which, called the Siemund-Weinzell Electric Company, actually received a patent for a method of arc welding.  These businesses were the first to bring arc welding into the United States (Sapp 2003).
        Also at this time the first adjustable voltage DC welding machine was created by the Lincoln Electric Company (Sapp 2003).  By being able to adapt the power, the machine could be used in many more projects that needed more or less power.

1908

1909

        A scientist named Schonner invents the first welding system that used plasma.  Known as plasma arc welding, the process used swirling gases to maintain a small, concentrated arc to gain better penetration (Sapp 2003).      

1912

        Strohmenger creates an electrode that leaves behind a pure metal as a filler.  Welded joints are now protected from the corrosive environment around them.  The electrodes are created by wrapping asbestos around the metal rod and then coating the whole thing with sodium silicate (Sapp 2003).

1919       After World War I, the Wartime Welding Committee changes their name to the American Welding Society.  This organization was created to help welding and related technologies grow and flourish.  Also in this year, alternating current was discovered by C. J. Holslag as another form of electricity (Welding.com 2003). 1920's         Various types of electrodes are produced for different applications.  For most grades of steel, a mild steel electrode could be used.  This kind typically had around 0.20% carbon content or less.  High-carbon, steel alloy, and copper electrodes were also produced in this decade (Cary pg. 10).

Welding during wartime. American Welding Society. (2002). A pictorial history of welding as seen through the pages of the Welding Journal. Retrieved December 2, 2003 from http://www.aws.org/about/photo/hist_pho10.jpg

1920
   
        P. O. Nobel develops automatic welding using direct current power.  The voltage of the arc would be used to control how fast the machine would go (Sapp 2003).

1926    H. M. Hobart and P. K. Devers experiment with welding in different atmospheres.  Using argon and helium gases, the two worked to create a way to produce a good weld while using a bare electrode.  Having the electrode come through the middle of a nozzle that was blowing out a shielding gas to create a quality weld.  This research became a basis for gas metal arc welding (Welding.com 2003).         Also at this time, two men named Alexander and Langmuir work with welding in a pure hydrogen environment.  Beginning with carbon electrodes and moving to tungsten, the pair found that the hydrogen would become atomic hydrogen and would exit the arc producing a very hot flame (Welding.com 2003).  After writing a paper on the results, Langmuir termed this variation of arc welding Atomic Hydrogen Arc Welding (Sapp 2003).

An example of gas metal arc welding. NRCC Welding Department. (2000). Welding Processes Taught at NRCC. Retrieved December 2, 2003 from http://www.nr.vccs.edu/nrcc2/%7EWelding/images/newwelding2.jpg

1930

        A new form of arc welding was developed named stud welding (Sapp 2003).  This process is defined as  "an arc welding process which produces coalescence of metals by heating them with an arc between a metal stud or similar part and the work piece" (Arcon Welding, LLC. 2003).  When the pieces have been heated to a certain temperature, they are pressed together which fuses them together (Arcon Welding, LLC. 2003).

        During this time, submerged arc welding also came into existence (Sapp 2003).  Also known as SAW, this variation of arc welding uses an arc to melt and join the metals, but the arc is actually protected by a grainy flux and the molten slag.  There is no shielding gas need because the arc and the joint are not exposed to the open environment (Kou pg. 22-23).

1942

        In trying to find a way to weld magnesium and stainless steels, P. H. Pavlecka and Russ Meredith develop gas tungsten arc welding.  This allowed for the possibility for a all-welded aircraft, created by Northrup Aircraft Incorporated.   The reason this was such a great improvement was because the aircraft would weigh less and be cheaper to make (Sapp 2003).

1948         The Air Reduction Company comes up with the procedure of Inert Gas Metal Arc Welding (Sapp 2003).  This type of arc welding uses an arc between the continuous electrode and the molten metal pool.  The arc is protected from the environment by a shielding gas that creates a cloud around the arc allowing no impurities into the weld pool (Robot-welding.com 2001).         Also in this year, shielded inert gas metal arc welding was developed by the Linde Air Products Company (Sapp 2003).  It is defined as "an arc welding process with an arc between a covered electrode and the weld pool (Cary pg. 124).  The shielding gas comes from the covering of the electrode burning away to form a gas cloud (Cary pg. 124).

An inert gas metal arc weld being made. TWI Ltd. (1999). Solid wire MIG welding. Retrieved December 2, 2003 from http://www.twi.co.uk/j32k/twiimages/jk42.jpg

1953

        A refined gas metal arc welding process is developed, consuming an electrode and using carbon dioxide as a shielding gas.  These modifications produced a high temperature arc, used a higher current, and the electrodes could be larger in diameter than before (Sapp 2003).

1958

        The Soviet Union introduces electroslag welding to the world at the Brussels World Fair in Belgium.  The process had been invented and used years earlier, bu the process had been refined by scientists in the Ukraine in later years.  After this, electroslag welding would be used in the United States to weld on diesel engines because of its ability to weld thick metals (Cary pg. 11).

1961

         A new form of welding is produced called Electrogas welding.  Developed by the Arcos Corporation, this process used some of the same principles and equipment as electroslag welding, but consumed a gas in order to work.  The slag does not cover the electrode in this case and a shielding gas is used to protect the weld (Cary pg. 12).

Gas Tungsten Arc Welding          Also known as GTAW, TIG, or WIG, this welding process is described by Sindo Kou, author of Welding Metallurgy as “a process that melts and joins metals heating them with an arc established between a nonconsumable tungsten electrode and the metals” (Kou pg. 13).  This type of arc welding requires no physical pressure and uses a gaseous cloud to shield the weld, usually argon or helium gas.  This is where the acronym TIG (Tungsten Inert Gas) and WIG (Wolfram Gas Welding) come from (wolfram is the German word for tungsten).  Used mainly for the metals that are difficult to weld or non-ferrous based metals, such as magnesium and aluminum (Cary pg. 72).         There are several advantages to GTAW as well.  The welds created by the GTAW process are of high quality and can be achieved in almost every alloy or metal.  Secondly, the welds need little or no cleaning after they are finished.  The precision of the welds is increased due to the fact that the welder can see the arc and the weld pool easily.  The idea that no filler material is transferred during welding; there is a minimal amount of spatter.  Welding of this type can be done in numerous positions, and there is no slag produced to leave impurities in the weld (Cary pg. 73).

Hawks, Val. (2003). Gas tungsten arc welding (TIG). Retrieved November 18, 2003 from http://class.et.byu.edu/mfg130/processes/descriptions/thermaljoining/tigwelding1.jpg

Plasma Arc Welding         This process, also known as PAW, is defined as, “and arc welding process that uses a constricted arc between a nonconsumable electrode and the weld pool (transferred arc) or between the electrode and the constricting nozzle” (Cary pg. 84).  Shielded comes from two different gases.  One comes from the ionized gas being emitted from the torch itself, and the other comes from some other outside source (Cary pg. 84).  The shielding gases help to concentrate the arc to a smaller area, allowing for better penetration than GTAW .  The electrode in this case does not stick out past the nozzle, so a "high frequency generator" is used to gain the primary arc between the electrode and the gas nozzle (Kou pg. 17).  As the gasses begin to come out, they push the arc down to the workpiece for the weld to begin (Kou pg. 18).         The advantages to this type of arc welding are numerous.  The fact that the gases help to maintain arc stability at different lengths make it a great process for beginners.  The fact that in other welding practices a person could contaminate the weld by touching it with the electrode is easily avoided in this case.  The electrode is inside of the nozzle so it cannot touch the weld and the arc length is not as short as is the case in GTAW.  However, PAW is not without some drawbacks.  The requirement for several different setting of gas and orifice pressures and the positions of the electrode among other things makes this variation of welding very complex (Kou pg. 18).  Also, the need for numerous amounts of extra equipment, such as a control center, raises cost when compared to GTAW (Kou pg. 19).

Robot-welding.com. (2001). Plasma arc welding. Retrieved November 24, 2003 from http://www.robot-welding.com/images/plasmaarcwelding.gif

Carbon Arc Welding         Carbon arc welding is a type of arc welding that is characterized by the use of electrodes that are made of carbon rather than a metal.  Though the process does not require a shielding gas, the carbon electrodes do break down fairly quickly which creates a carbon gas shield.  A filler metal is not needed, but for most applications is generally used.  A unique aspect of this type of welding is that a person can use two electrodes at the same time.  There are holders that accommodate both electrodes as well.  In this application, one electrode can move against the other to create a pilot arc.  With one electrode set at an angle, the apex is a soft source of high temperature heat, around 8-9000°F (Cary pg. 96).  This process can be used to join sheet steel. copper, and aluminum (Houldcroft pg. 67).        Some advantages of this welding type lie in the fact that thinner metals can be welded together without the need for a filler metal.  Galvanized steel can also be welded using this process.  For this, a bronze filler rod is used and placed between the base metal and the arc.  This also applies to repairing cast iron parts.  Also, the process can be used in all positions that a weld is needed (Cary pg. 94).

Arc Controls, Inc. (2003). Capabilities. Retrieved December 1, 2003 from http://www.arccontrols.com/images/cncburnx.jpg

Stud Welding         Developed in the 1930's, stud welding is defined as a process of arc welding in which "permits rapid attachment of studs and other fasteners to a structure without piercing the structure metal" (Galvery, Marlow pg. 211).  There is no filler metal, and shielding gas, flux, or a ceramic shield around the stud are all optional.  Once the metals on the stud and the base piece are heated enough to be joined, they are pressed together in order to fuse them together.  The stud is sometimes encased on the end with a ceramic cuff in order to protect the arc and the welding surfaces from the surrounding environment.  For some though, this form of arc welding is not a true variation of it.  Stud welding uses principles from arc welding and from forge welding.  An arc is used to heat the metal, but then a force is used to adhere the pieces together (Cary pg. 97).         In comparison to drilling and tapping, stud welding in superior.  The base metal is not weakened and a water tight seal is not destroyed, as is the case with drilling and tapping.  Also, costs and time are minimized when compared to the other two.  Robots are now being used to place and set the studs, which also decreases time.  Every position can be welded from, but vertical and overhead positions are not easily done.  A variety of metals can be used as well, not just ferrous metals (Cary pg. 97).

Contract Connections Ltd. (2001). Studwelding. Retrieved December 1, 2003 from http://www.contractconnections.co.nz/images/s4.jpg

Atomic Hydrogen Welding

        This process involves injecting hydrogen into extreme heat in the arc, the temperature makes the hydrogen gas (H₂) and breaks it down into its simplest form, which would be two hydrogen atoms (Houldcroft pg. 187).  The arc is formed between two tungsten electrodes, not between the metal workpiece and the electrodes as in other types of arc welding (Cary pg. 102).  This process absorbs energy away from the arc, but gives it back as the hydrogen recombines as it contacts the metal work surface.  The procedure uses the heat from the reaction to heat the metal.  The temperature of the flame reaches 3700°C and can then be used for welding .  The arc in this case does not have much  of an effect on the weld except it can increase the temperature some as the electrodes get closer to the weld pool.  The transformer for this operation is generally around 300 volts, so caution is needed (Houldcroft pg. 187).

            For years hydrogen arc welding was used for hard-to-weld metals such as nickel-base alloys and high alloy steels.  The hydrogen used helped reduce gas bubbles in the weld, which provided a seam with fewer pores.  This makes a much stronger weld because more metal is holding the pieces together.  The hydrogen is also good due to the fact that other gases cannot enter the weld pool because it is protected by the stream of hydrogen gas (Cary pg. 103).  This process has been almost overshadowed by inert-gas arc welding (Houldcroft pg. 187).

Magnetic Rotating Arc Welding             Developed in the 1970's, magnetic rotating arc welding is also known as magnetarc welding or magnetically impelled arc butt (MIAB) welding .  It is defined as "an arc welding process in which an arc is created between the butted ends of tubes and propelled around the weld joint by a magnetic field, followed by an upsetting operation (Cary pg. 103)."  The procedure is a mixture of arc and forge welding with a gas shielding operation added on.  This method of welding by clamping the parts to be joined into the machine.  Next, the two pieces are pushed together and electricity is applied to them.  As they are separated, an arc is started.  When the arc is established, a magnetic coil around the weld repels the arc, which pushes it around the perimeter of the piece (Cary pg. 103).  The arc runs around the piece at a speed close to 50 meters a second.  At this speed the arc looks as though it is a circle of light between the pieces (Diverse Technologies 2003).  After the arc has run around the piece for a determined amount of time, the two pieces are pressed together to join them (Cary pg. 103).                This process is now very popular in mass production situations. The entire system is fast, can be automated, and requires less energy than other types of welding.  The parts do not need to be cylindrical and the welds are repeatable with high quality and little deformities (Cary pg. 105).  Also, this welding does not expel as much metal as does other forms of welding, which makes MIAB welding more efficient.  The drawback comes from the fact that the arc only heats the edges of the pieces, not the middle.  This means that only a certain thickness of metal can be welded in this fashion and that solid pieces of metal cannot be joined (Houldcroft pg. 136).

Andrews, Dick. (2001). MIAB welding. Retrieved December 2, 2003 from http://www.twi.co.uk/j32k/twiimages/faqrea001f1.gif

Shielded Metal Arc Welding         Sometimes called stick electrode welding or SMAW, this type of arc welding started off as a bare metal rod used to keep an arc  going between the metal piece and the electrode.  The problem with the process in the past was due to the lack of any sort of flux or shield gas to protect the weld from the environment.  The first flux covered electrode came about in 1900 and was created by Oscar Kjelberg.  It was coated with a mixture of rust and lime.  Coverings were modified and improved though out the century (Houldcroft pg. 23).  The procedure is very simple in SMAW.  A covered electrode is held in the electrode holder that is attached to a power supply cable.  The workpiece is connected to the other power cable.  The electrode passes the current through to the workpiece and supplies a filler metal to the weld pool.  The end of the electrode and the flux coating melt as the electrode is heated.  The melted flux provides a gaseous protection for the weld (Kou pg. 11).                        This welding variation is the most popular of recent times.  The flexibility of stick welding allows it to be used in all positions for a wide variety of thicknesses and equipment costs are very low (Cary pg. 125).  The simplicity and mobility of this operation allows for it to be used in maintenance, repair, and field construction.  The gas that is created in this welding is not pure enough to weld reactive metals such as aluminum and titanium.  The covering has a tendency to fall off when high currents are used due to the electrode overheating.  Another disadvantage is that the electrode is used up in the process and has to be changed periodically, which increases time (Kou pg. 13).

Hawks, Val. (2003). Shielded metal arc welding. Retrieved December 2, 2003 from http://class.et.byu.edu/mfg130/processes/descriptions/thermaljoining/smawwelding1.jpg

Gas Metal Arc Welding             Also known as Metal Inert Gas (MIG) welding or GMAW, this system of welding was developed to weld metals thicker than 1/4" that Tungsten Inert Gas (TIG) welding could not weld.  In its infancy, MIG welding was limited to only thick metal applications.  Eventually some refinements were made and the possibilities for welding various metals was gained (Geary pg. 49).  This welding procedure is very close to TIG welding in that a inert shielding gas is used to protect the weld and the arc is maintained between the electrode and the workpiece (Geary pg. 48).  The difference comes from the fact that the electrode is consumed in MIG welding.  The electrode is actually a long wire that is fed through a hole in the tip of the handle that carries the current to the workpiece and supplies a filler metal (Geary pg. 50).         The fact that the electrode is continuous makes the welds that are produced very good in quality.  There is no need to start and stop to replace an electrode as in SMAW and long welds can be completed in one step.  The entire process can be automated and all welding positions can be used on any thickness of metals.  The process is easy to learn and there is little or no spatter and no slag is created in MIG welding which makes surface preparation for painting very easy.  However, the system used in MIG welding is more expensive and is less portable than some other types of welding, such as SMAW.  The gun is large and the cable is stiff which makes welding tight spaces hard and the gun's size makes it hard to see the arc, which leads to poor welds.  Another disadvantage lies in the fact that MIG welding outside requires certain conditions.  The breeze must not exceed 5 miles per hour with no screen or the shielding gas will blow away and will not protect the weld (Galvery, Marlow pg. 135).

Hawks, Val. (2003). Gas metal arc welding. Retrieved December 2, 2003 from http://class.et.byu.edu/mfg130/processes/descriptions/thermaljoining/migwelding1.jpg

Flux Cored Arc Welding             This variation of arc welding consists of a hollow metal electrode that is filled with flux.  The same principle applies here as in other types of welding.  As the flux heats up, it breaks down into a shielding gas that can protect the weld by itself or can help an auxiliary gas (Kou pg. 22).  Flux cored arc welding (FCAW) is actually a variation of gas metal arc welding but is based on how the electrode is set up.  Some of the variations that use auxiliary gases, there are two types.  One of these uses the flux from the inside of the electrode as the only source of flux.  The other type uses alloys and powdered iron to gain in productivity with a loss in the flux amount.  The wire is continuos and is fed through the handle.  It maintains an arc between the workpiece and the electrode, with a shield gas provided by the disintegration of the flux ingredient or by a nozzle on the handle.  The metal part of the electrode supplies a filler metal to the weld pool (Cary pg. 154).             The advantages to FCAW is that it can weld several different thicknesses of metal with the same electrode by adjusting the power supply to that application.  The process is easier to accomplish than SMAW and the weld pool can be controlled very well, which could come from the fact that a gas nozzle is not always needed and the arc can be easily seen.  The welding system is used to meet codes on various vital welds on items such as boilers, pressure vessels, and structural steel.  This method also can be used to create quality welds on oxidized or scaled metals.  Windy conditions also do not affect this form of welding (Galvery, Marlow pg. 167).  However, this welding technique does require a slag removal process, which adds time, and creates a lot of fumes and smoke that require more ventilation than other forms of welding (Galvery, Marlow pg. 168).

Robot-welding.com. (2001). Arc welding processes. Retrieved December 2, 2003 from http://www.robot-welding.com/images/fcaw.gif

Submerged Arc Welding             Submerged arc welding is a little different than most other forms of welding because the arc and the end of the electrode are not visible to the operator.  Both are kept under a pile of granular flux.  The most common use for this welding system is by machines, but there are semi-automatic versions.  The machine is used to begin the arc and provides the electrode by feeding it to the weld area from around a spool.  The flux is in a grain form and is distributed in front of the weld path (Galvery, Marlow pg. 212).  The system can also be set up with two electrodes placed vertically side by side, vertically one in front and one in back, or in a v-shaped to speed the process up.  Some of the flux is melted in the welding process which produces a slag that helps protect the weld from the environment and from cooling.  Some joints up to 3" wide can be welded in one pass.  This method is usually done in a flat position and is great for ships and bridges where long welds are needed (Galvery, Marlow pg. 213).             The slag in this case helps to create a pure and strong weld.  With the arc covered up, spatter and heat loss into the surrounding environment is not a problem.  Alloy and metal powders can be added to the flux grains in order to help fill the seam (Kou pg. 23).  Not a lot of smoke is produced if any and no protection is needed to shield from the light from an arc.  The system is automated easily and there is not a lot of skill needed for the process (Cary pg. 166).  The slag produced limits submerged arc welding to only to a flat position.  The heat that is produced by the weld stays in the metal longer due to the flux coating which can increase distortion of the metals (Kou pg. 24).

Hawks, Val. (2003). Submerged arc welding. Retrieved December 2, 2003 from http://class.et.byu.edu/mfg130/processes/descriptions/thermaljoining/sawwwelding1.jpg

Electroslag Welding             Also known as ESW, electroslag welding is a method where a primary arc is used at first to heat the slag and is then smothered by the conductive slag.  The heat is then generated by the slag resisting the electricity passing between the consumed electrode and the work.  It is usually used to weld steel in a vertical position and was used widely in the Soviet Union in the 1940's (Cary pg. 177).  This is not an arc welding process however, though an arc is briefly ignited in the beginning stages.  Past this, there is not arc involved in the procedure (Cary pg. 180).  The thickness limit for this welding process reaches up to 30".  Extreme heat helps to gain this type of penetration, and multiple electrodes can be used to speed up this process (Galvery, Marlow pg. 203).  In the 1970's, electroslag welding became a popular choice for welding metals that were very thick.  These applications include parts for bridges, buildings, ships, and pressure vessels (Cary pg. 178).             The positive side of electroslag welding is that very thick metals can be joined and multiple electrodes can be used to complete a weld in a single pass (Galvery, Marlow pg. 204).  The heat is held in the weld longer and gas bubbles are allowed to escape from the weld pool before it cools.  The entire process is automatic and once it starts it does not stop until the weld is complete.  For large or thick pieces of stock, electroslag welding is the quickest way to join the pieces together (Cary pg. 181).  There is very little work that needs to be done to prepare the joints prior to welding and the distortion of the metal is relatively low.  The drawbacks come from the fact that the system is very complicated and only works on flat or vertical joints.  Also some of the instruments used in this procedure have to be cooled with a constant water supply (Galvery, Marlow pg. 204).

EPRI Journal. (2003). New Technology Allows Greater Control Over Weld Deposit. Retrieved December 2, 2003 from http://www.epri.com/journal/images/265_CntrldWld_display.jpg

   Electrogas Welding

          Electrogas welding (EGW) uses a constant arc to melt the electrode and the base metal and a guide tube, if one is used.  Te molten metal then is accumulated between two molding shoes.  When the metal solidifies, the two pieces are joined together.  Shielding comes from either and auxiliary resource or from the coverings on the electrode disintegrating (Cary pg. 188).  Once the process has started, it should not stop until the weld is completed.  An operator is needed only to make sure the arc stays in the middle of the seam (Cary pg. 189).  This method can only be used in certain applications though.  The work must be within 15° of vertical or else it will not work correctly (Cary pg. 190).

This is a master chart of Arc Welding and Related Methods



Integrated Publishing. (2003). Arc Welding. Retrieved December 3, 2003 from
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Arc Welding in Industry:

        Welding has many different uses in industry.  Most everything bought today has some sort of welded joint in it.  Many diverse areas of industry are using this process of metal to metal cohesion.  Arc welding variations are used in items from aircraft and rocket engines to small pipes.  These are commonly used when a strong, high quality weld is needed.  Also, this type of welding can weld several different metals well, even aluminum and magnesium (Cary pg. 85).  The construction industry uses this type quite often, especially to attach different metallic things, such as electrical conduit, pipes, and other such items, to a metal framework (Cary pg. 102).  This variety of welding is also used in remote locations easily because it is portable and cheap (Cary pg. 142).  Welding are all around us every day.  Supetankers, bulldozers, water towers, some boats and patio furnature, cars, and even buildings consist of some type of weldment (Cary pg. 1).