Welding is a fabrication process that joins two or more materials by melting them together using high heat. The melted parts fuse and solidify as one piece when cooled, forming a strong bond.
Welding is one of the most common methods for permanently connecting metal parts in manufacturing, construction, and repair across many industries.
Welding involves three primary components:
A heat source: Generates enough heat to melt the base metals and the filler material. Common heat sources are flames (gas welding), electric arcs (arc welding), lasers, electron beams, and friction.
Base metals: The main pieces being joined. The edges of the base metals are melted during welding.
Filler material (consumable): Extra material used to fill gaps and create a strong joint. The filler material melts with the base metals.
The intense localized heat from the welding process causes the metals and filler material to intermix in the liquid state. As the metals cool and solidify, coalescence occurs, creating a solid joint called the weldment. Modern welding leverages concentrated energy sources that can generate temperatures from 2000°F to over 10,000°F at the point of contact.
Proper welding results in a seamless, permanent joint with strength equal to or greater than the original base metals. Welding is distinct from lower-temperature metal joining techniques like soldering, brazing, and adhesive bonding which do not melt and fuse the base materials.
History of Welding
Welding has a long history dating back thousands of years. The earliest examples come from the Bronze Age and Iron Age in Europe and the Middle East, where metals like copper, bronze, silver, gold, and iron were fused.
During the Bronze Age over 2000 years ago, small circular boxes were made by pressure welding lap joints together. In 3000 BC, Egyptians used charcoal to pressure-weld swords. Around 1500 BC, iron smelting became more common, and tools and weapons made of welded iron have been found dating back to 1000 BC.
In the Middle Ages, the art of blacksmithing was developed and many iron objects were produced by hammering pieces of iron together.
It wasn’t until the 19th century that modern welding processes were invented. In 1800, Sir Humphry Davy produced an electric arc between two carbon electrodes using a battery. In 1836, English chemist Edmund Davy discovered acetylene gas. The electric generator was invented in the mid-19th century, enabling developments in arc welding and oxy-fuel welding using acetylene.
World War I greatly increased the demand for welding. Arc welding was used extensively in shipbuilding and aeronautics in England and Germany. Automatic welding was introduced in 1920. In the early 1900s, new shielding gases were introduced to protect welds from atmospheric contamination.
Many new welding techniques were invented in the mid-20th century, including gas tungsten arc welding in 1941 and submerged arc welding in the 1930s. Further developments continued with innovations like laser beam welding and friction stir welding in the latter half of the century.
How Does Welding Work?
Welding works by joining two or more metals using heat, pressure, or both to produce a strong, permanent bond. The high heat melts the base materials and any filler material at the joint. When cooled, this forms a solid fusion between the metals.
There are over 90 welding processes but they fall into three main types:
- Arc Welding: Uses an electric arc to melt the metals. An electrode lead on the metals creates an arc when drawn away, generating heat.
- Gas Welding: Uses a gas flame from burning gases like acetylene. The torch is used to melt the metals.
- Laser Welding: Focuses a high-energy laser beam to fuse materials.
Welding is distinct from soldering and brazing which only melt a filler material without fusing the base metals. The welded joint can be stronger than the original metals due to metallurgical bonding.
Common Joint Configurations
There are five basic types of joints in welding:
- Butt Joints: Pieces aligned end-to-end in the same plane. Various edge preparations are used.
- Corner Joints: Pieces meeting at 90° like an L shape. Used in boxes or frames.
- Edge Joints: Pieces aligned with edges even. Used for sheet metals.
- Lap Joints: Overlapped pieces. Used for joining different thickness.
- Tee Joints: Perpendicular pieces like a T shape. Common in structures.
Joint design affects weld quality and cost. It determines the weld type needed to meet strength requirements.
Types of Welding Joints
There are many types of joints which differ based on the edge preparation:
Types Based on Penetration
- Partial Penetration: Weld does not penetrate full thickness.
- Full Penetration: Weld penetrates the full thickness of the joint.
Types Welds Based on Configuration
Butt Welds:
- Square Butt
- Single V
- Double V
- Single Bevel
- Double Bevel
- Single J
- Double J
- Single U
- Double U
- Flange Butt
Corner Welds:
- Closed Corner
- Open Corner
Edge Welds:
- Square Edge
- Bevel Edge
- J Edge
- U Edge
Lap Welds
- Fillet Lap
- Plug Lap
- Slot Lap
Tee Welds
- Fillet Tee
- Bevel Tee
- J Tee
Welds Based on Accessibility
Single-Sided Welds: Only accessible from one side.
Double-Sided Welds: Accessible from both sides.
Features of Completed Welds
- Weld Toe: Where weld metal meets base metal.
- Weld Root: Bottom of the weld joint.
- Weld Face: Exposed surface of the weld.
- Weld Reinforcement: Weld metal above the base metal.
Different Types of Welding
There are many welding processes used in various industries:
- Shielded Metal Arc Welding (SMAW): Uses a flux coated electrode to create an arc. Also known as stick welding.
- Gas Metal Arc Welding (GMAW): Feeds a wire electrode via a welding gun with inert gas. Also known as MIG welding.
- Flux-Cored Arc Welding: Uses a wire electrode with flux core instead of solid wire. Easier for outdoor use than MIG welding.
- Gas Tungsten Arc Welding (GTAW): Non-consumable tungsten electrode with inert gas shield. Also known as TIG welding. Excellent for non-ferrous metals.
- Submerged Arc Welding (SAW): Uses an arc beneath flux for deep weld penetration. Automated process used for thick materials.
- Electroslag Welding: Uses a conductive flux to create a molten slag pool as heat source to weld thick materials.
- Resistance Welding: Uses heat from electrical resistance and pressure to fuse metals. Includes spot, seam, and flash welding.
- Oxy-Fuel Welding: Burns fuel gases like acetylene with oxygen to create high temperature flame. Oldest welding process.
- Laser Beam Welding (LBW): Focuses a laser to melt and join metals with high accuracy and speed. Used to weld reactive and heat-sensitive metals.
- Electron Beam Welding (EBW): Focuses a beam of high-velocity electrons to melt and fuse materials in a vacuum. Limited to conductive materials.
- Friction Welding: Rotates one part against another under force to generate heat and plastically deform metals. Automatable process good for circular parts.
What are the Different Types of Weldings Used for?
Different welding processes are better suited for certain applications:
- SMAW: Versatile, portable, and inexpensive. Used for repair work and thick materials.
- GMAW: High deposition rate. Used extensively in manufacturing and fabrication. Good for thin materials.
- FCAW: Portable and good for outdoor use. Used for construction and fabrication.
- GTAW: High-quality welds for non-ferrous metals like aluminum and stainless steel. Used in aerospace, automotive, and artwork.
- SAW: High deposition rate and deep penetration. Used for thick materials like large structures and pressure vessels.
- LBW: Precise, clean welds with aluminum and reactive metals. Used in electronics and medical devices.
- EBW: Deep penetration vacuum welds for space, aviation, and nuclear applications.
- Friction Welding: Automatable process good for axles, flywheels, and other circular parts.
FAQs about Welding
What metals can be welded?
These metals are steel, stainless steel, aluminum, copper, nickel alloys, magnesium, titanium, and more.
What equipment is needed for welding?
The equipment needed depends on the welding process. At minimum, you need a heat source (welding torch, arc, laser, etc), filler material, shielding gas for some methods, welding helmet or goggles, protective clothing, and clamps.
Is welding safe?
Welding can be dangerous if proper safety precautions are not taken. Risks include electric shock, fire and explosion, ultraviolet and infrared radiation burns, fumes, and physical hazards from hot metal and equipment. Using protective gear and adequate ventilation is crucial.
How much does a welder make?
It’s around $45000 per year. Underwater welder’s average is $100,000 per year. Vary based on areas, skill level, certifications, and industry
How long does it take to become a certified welder?
Most welding certification programs take 6 months to 2 years to complete. This includes classroom learning and hands-on practice. Some fast-track programs can certify welders in just a few weeks.
What are the different types of welding certifications?
- American Welding Society (AWS)
- The American Society of Mechanical Engineers (ASME)
- There are certifications for specific processes like GTAW and GMAW
Is welding a good career?
Yes, welding is considered a good career path. Welders are in high demand and can make a good living, especially with specialized skills and certifications. It offers opportunities for advancement and good job security.
Is welding hard to learn?
Welding does require some innate skill and hand-eye coordination. However, the basics can be learned fairly quickly with proper training. Mastering advanced welding techniques takes years of practice though.
What are some everyday items made by welding?
Some common welded products include automobiles, aircraft, ships, buildings, bridges, power generators, pressure vessels, storage tanks, and pipes. Even things like shopping carts, furniture, and bicycles are welded.
What industries use welders?
Major industries that employ welders are construction, infrastructure, energy, aerospace, defense, maritime, automotive, and general manufacturing. Welders work on pipelines, oil platforms, ships, buildings, and heavy equipment.
Can you weld different types of metals together?
Yes, but welding dissimilar metals can be problematic because of differences in their physical properties. Special joint preparation and filler material selection is required.
What is the strongest welding joint?
Full penetration double-sided square butt welds typically provide the strongest joint. The weld penetrates the full thickness on both sides for maximum bonding area.
How long does a typical weld take to complete?
Weld times range from less than a minute to hours depending on the size and complexity. Small welds like tack welds take seconds while large groove welds on thick plate can take hours.
Can you weld things at home?
Yes, welders for home use are available at hardware stores starting around $100. SMAW and GTAW welders with small outputs can be used for DIY projects. Proper safety gear should always be worn.
What gases are used in welding?
Common shielding gases are argon, helium, carbon dioxide, and combinations like Ar/CO2. Fuel gases for oxy-fuel welding include acetylene, propane, propylene, and methylacetylene-propadiene.
How hot does welding get?
Welding can produce temperatures ranging from 2000°F to over 10,000°F at the point where the heat source contacts the metal. This extreme heat melts the base material.
Can you weld things underwater?
Yes, underwater welding is commonly done offshore and in wet environments. Special waterproof electrodes and other precautions are used to weld safely underwater.
Top Facts about “What Is Welding?”
- Welding played a major role in both World Wars by enabling mass production of weapons and vehicles.
- 90% of all manufactured goods rely on welding for production.
- The average salary for welders in the US is $44,190 per year.
- Welding has a lower entry barrier than machining or engineering, allowing more people to learn it.
- The top three markets in the welding world are China, India, and the US.
- Welding is used in many industries including construction, infrastructure, aviation, automotive, and shipbuilding.
- Welding has evolved to become highly automated using robots, resulting in increased productivity and precision.
- Modern welding is advancing with technology like laser and electron beam welding that leverages the concentrated energy of photons and electrons.
Welding is an essential fabrication technique with a long history and bright future. It leverages concentrated heat sources to fuse materials for stronger and more reliable joints. Welding is critical across manufacturing and enables our modern infrastructure and technologies.
While early welding used simple forging, modern processes allow precise and automated welds. As science continues to advance, welding will remain an indispensable tool for creating the structures and machines that build our world.