The Different Types of Welding Processes
There are many types of welding services used today used amongst amateurs and professionals alike. Given the versatility and proficiency required for welding applications, it’s no wonder welders must undergo serious training to become skilled in their craft. Since welding pertains to joining metal alloys, it’s important to see how welders utilize different practices for this purpose. Here are some of the different types of welding processes used for stainless steel and other metal alloy applications today.
Gas Tungsten Arc Welding (GTAW)
Gas Tungsten Arc Welding is a form of arc welding using a non-consumable tungsten electrode. Oxidation doesn’t affect the electrode or weld area via inert shielding gas—specifically argon or helium—and filler metal. When helium is used, it is known as heliarc welding, but the process is the same. Constant-current welding power supplies the electrical energy which conducts across the arc through ionized gas and metal vapors. GTAW is commonly used for stainless steel, aluminum, magnesium, and copper since the welder can complete stronger, higher quality welds.
Flux-Cored Arc Welding (FCAW)
Flux-cored arc welding is another type of arc welding in which a consumable tubular electrode containing a flux is continuously fed through a constant current welding power supply. External shielding gas is sometimes used but not necessary to complete the weld. The flux itself provides protection as it produces gaseous and liquid slag that shield it. Given its natural protective barriers, high welding speed, and portability, FCAW if often used in construction projects. While initially designed as an alternative to shielded metal arc welding, FCAW uses stick electrodes that reduce many restrictions fond in SMAW.
Shielded-Metal Arc Welding (SMAW)
SMAW is efficient for its manual arc welding process that uses consumable electrodes covered with a flux. Alternating or direct electrical currents from a welding power supply form an electric arc between the electrode and the joining metals. This melts the electrode and workpiece to form molten metal which then cools and forms a joint. Then, the flux coating disintegrates, leaving vapors that act as a shielding gas and provide a layer of liquid slag used to protect against atmospheric contamination. Since SMAW operations are simple yet require relatively few pieces of equipment, they are one of the most popular forms of welding today, especially in the maintenance and repair industries. Iron, stainless steel, aluminum, nickel, and copper are all usable with this method.
Gas Metal Arc Welding (GMAW)
Gas metal arc welding is the welding process by which electric arcs form between consumable MIG wire electrodes and workpiece metals. This type of welding heats the metals, causing them to melt and join. Shielding gas feeds through the welding gun and protects against atmospheric contamination. Whether automatic or semi-automatic, the constant current system uses four primary transfer methods to transfer metal: globular, short-circuiting, spray, and pulsed spray. The GMAW method was originally used for aluminum and non-ferrous metals but is currently used for steels due to its fast welding time and higher versatility. It is the most common form of industrial welding process given these benefits and the adaptability to robotic automation. Still, its lack of protective shield makes it unusable for outdoor processes.
Laser Beam Welding
Laser beam welding is a newer technique in which lasers join pieces of metal or thermoplastics. The beam acts as a concentrated heat source, allowing for narrow, deep welds and high welding rates. Laser beam welding processes are frequently used in high-volume applications, specifically in the automotive industry which frequently utilizes keyhole or penetration mode welding. High-power density results in smaller heat-affected zones and higher heating and cooling rates. Spot size can vary, and the penetration depth is proportional to the amount of power supplied and dependent on the focal point’s location. Laser beam welding is typically used on carbons steel, stainless steel, aluminum, and titanium, but the high cooling rates could lead to cracking.
Electron Beam Welding (EBM)
One type of fusion welding different from the other types of welding processes is electron beam welding. This process uses a beam of high-velocity electrons applied to join two materials. As the workpieces melt, the kinetic energy transforms into heat upon impact and joins the materials. The processes usually undergo vacuum conditions to prevent the electronic beam from dissipating. EBM applications are commonly thin-walled components in order to provide the perfect contact point and prevent movement during welding. Certain materials cannot undergo EBM processes given their melting points, like zinc, cadmium, magnesium, and any non-metal. Furthermore, the EBM process cannot join two dissimilar materials with different alloy compounds. Electronic beams can create a high-vacuum atmosphere and localize heating to a precise point if a lower melting point is directly accessible for the beam.
Submerged Arc Welding (SAW)
Submerged arc welding is a common process used when continuously feeding a consumable solid or tubular electrode and submerging the molten weld and arc zone under fusible flux. The flux then becomes conductive and provides current paths between the electrode and workpiece. As the thick layer of flux covers the molten metal, it prevents splatter and sparks. It also suppresses intense ultraviolet radiation and fumes. SAW processes are typically automatic and mechanized, but pressurized or gravity flux feed delivery methods exist as their limited to flat or horizontal-fillet welding positions. Currents range from 300 to 5000 A via single or multiple electrode wire variations. Direct and alternating current combinations are commonly used for SAW processes and other multiple-electrode systems.
At CMPI, we understand the importance of ASME welding services for any fabrication system. No matter the reason, we have you covered. We ensure reliability with our products and services for any industry, from food and beverage, to pharmaceuticals, to tank and vessel manufacturing. Rather than build a product to sell you, we want to act as an extension of your store. So, when your welding fabrications come into play, we take the best practices and considerations that fit your specific needs. Call us today with any lingering questions or concerns and we’re happy to get back to you. Otherwise, check out our various products and services on our website to see which ones work for you.
