Welding

Definition and Process of Welding

• Welding is a fabrication process that joins materials using high heat to melt the parts together and allowing them to cool, causing fusion.
• It is distinct from brazing and soldering as it melts the base metal.
• A filler material is typically added to the joint to form a pool of molten material that cools to form a strong joint.
• Pressure may also be used to produce a weld.
• Welding requires a shield to protect the metals from contamination or oxidation.

Energy Sources for Welding

• Gas flame, electric arc, laser, electron beam, friction, and ultrasound can be used as energy sources for welding.
• Different energy sources have different applications and advantages.
• Gas metal arc welding (GMAW) and shielded metal arc welding (SMAW) are popular methods.
• Welding can be performed in various environments, including open air, underwater, and in outer space.
• Precautions are necessary to avoid hazards such as burns, electric shock, and exposure to poisonous gases and radiation.

Historical Development of Welding

• Forge welding was the only welding process until the end of the 19th century.
• Arc welding and oxy-fuel welding were among the first processes to develop.
• Manual methods like shielded metal arc welding became popular.
• Semi-automatic and automatic processes such as gas metal arc welding and flux-cored arc welding were developed.
• Laser beam welding, electron beam welding, and friction stir welding were invented in the latter half of the 20th century.

Early Examples of Welding

• The history of joining metals goes back several millennia.
• Glaucus of Chios is credited with inventing iron welding in ancient Greece.
• Forge welding was used in the construction of the Iron pillar of Delhi in India.
• Middle Ages brought advances in forge welding techniques.
• Vannoccio Biringuccio published a book that included descriptions of the forging operation.

Advancements in Welding Techniques

• Sir Humphry Davy discovered the short-pulse electrical arc in 1800.
• Russian scientist Vasily Petrov created the continuous electric arc in 1802.
• Metal electrodes were invented in the late 1800s.
• Coated metal electrodes and three-phase electric arc welding were proposed.
• Resistance welding and thermite welding were developed in the late 19th century.

Welding Data Sources