Welding Knowledge 6

Welding is a processing method that uses heat or pressure, or both, and with or without filler material, to achieve atomic bonding between workpieces. It typically refers to the welding of metals, a forming method that joins two separate objects into a single unit by applying heat or pressure to create interatomic bonding forces.

The physical essence of welding is to achieve a permanent connection between the materials (same or different) of the workpieces through heating or pressure. Based on process characteristics, welding methods are mainly divided into three categories: fusion welding, pressure welding, and brazing.

Welding technology is widely used in industries such as petrochemicals, power, aerospace, marine engineering, nuclear power engineering, microelectronics, bridges, ships, submarines, and various metal structures. Compared with riveting and casting, welding offers a series of advantages, including saving metal materials, reducing structural weight, simplifying processing and assembly procedures, producing welded joints with good density and high strength, good economic benefits, and improved working conditions.

The delayed gas shut-off time refers to the time after the welding arc extinguishes before the shielding gas supply is stopped. The purpose is to continue protecting the molten pool and high-temperature weld after welding, preventing them from reacting with harmful components in the air, thereby ensuring weld quality.

Specific Applications: Common Metals: For TIG welding (tungsten inert gas welding) of metals such as aluminum, stainless steel, and titanium, these materials are prone to oxidation at high temperatures, therefore requiring a longer gas lag time, typically 3-5 seconds.

General Range: The gas lag time is usually between 0.3 and 5 seconds; the specific time needs to be determined based on the welding material, thickness, and process requirements.