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2023

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04

Summary of various welding technology knowledge, complete in 10 minutes!


Welding usually refers to the welding of metals. It is a forming method of connecting two separated objects into one body by generating atomic bonding force through heating, pressure, or both simultaneously.

Welding technology is widely used in machine manufacturing, shipbuilding industry, construction engineering, power equipment production, aviation and space industry industries. Welding technology also has some shortcomings, such as the non detachable welding structure, which brings inconvenience to maintenance; Welding stress and deformation may exist in welded structures; The microstructure and properties of welded joints are often uneven, and welding defect will occur.

Welding techniques mainly include fusion welding, pressure welding, and brazing. The following is an introduction to several welding techniques:

01

Arc welding

Arc welding technology can be divided into six welding methods: manual arc welding, submerged arc welding, gas tungsten arc welding, gas metal arc welding, plasma arc welding, and tubular wire arc welding. The following is the introduction of these six different welding methods:

1. Hand arc welding

Manual arc welding is one of the earliest and most widely used arc welding methods. It uses a coated electrode as the electrode and filler metal, and the arc burns between the end of the electrode and the surface of the workpiece being welded.

Coatings can generate gas to protect the arc under the action of arc heat, and on the other hand, they can generate slag to cover the surface of the molten pool, preventing the interaction between the molten metal and the surrounding gas. The more important role of slag is to react physically and chemically with the molten metal or add alloying elements to improve the energy of the weld metal.

The manual arc welding equipment is simple, lightweight, and flexible to operate. It can be used for welding short seams in maintenance and assembly, especially for welding difficult to reach areas. The use of corresponding welding rods for manual arc welding can be applied to most industrial carbon steel, stainless steel, cast iron, copper, aluminum, nickel and their alloys.

2. Submerged arc welding

Submerged arc welding is a consumable electrode welding method that uses granular flux as the protective medium and the arc is hidden beneath the flux layer. The welding process of submerged arc welding consists of three stages:

Evenly stack sufficient granular flux at the seam of the welding piece to be welded → connect the conductive nozzle and the welding piece to the welding power supply at two levels to generate a welding arc → automatically feed the welding wire and move the arc for welding.

Submerged arc welding has the characteristics of unique arc performance, high electric field strength of arc column, and high production efficiency; Flux participates in metallurgical reactions, Si and Mn are reduced, and part C is burned, limiting the removal of impurities S and P from H and preventing the generation of hydrogen pores.

Due to its large penetration depth, high productivity, and high degree of mechanical operation, submerged arc welding is suitable for welding long welds in medium and thick plate structures. It is widely used in shipbuilding, boilers and pressure vessels, bridges, overweight machinery, nuclear power plant structures, marine structures, weapons and other manufacturing sectors, and is one of the most commonly used welding methods in welding production today.

In addition to being used for connecting components in metal structures, submerged arc welding can also overlay wear-resistant or corrosion-resistant alloy layers on the surface of the base metal. With the development of welding metallurgy technology and welding material production technology, the materials that can be welded by submerged arc welding have evolved from carbon structural steel to low alloy structural steel, stainless steel, heat-resistant steel, and some non-ferrous metals, such as nickel based alloys, titanium alloys, copper alloys, etc.

3. gas tungsten arc welding

This is a kind of gas shielded arc welding with non melting electrode, which uses the arc between the tungsten electrode and the workpiece to melt the metal and form the weld. During the welding process, the tungsten electrode does not melt and only serves as an electrode. At the same time, argon or helium gas is fed into the nozzle of the welding torch for protection.

Additional metal can also be added as needed. Internationally known as TIG welding. Gas tungsten arc welding is an excellent method for connecting sheet metal and backing welding because it can control heat input well.

This method can be used for almost all metal connections, especially for welding metals such as aluminum and magnesium that can form refractory oxides, as well as active metals such as titanium and zirconium. This welding method has high weld quality, but compared with other arc welding, its welding speed is slower.