What is welding used for What is the role of welding?

The main purpose of welding is to join small metal materials into large ones (according to drawings or required dimensions), or to make the required geometry by joining (welding).

Welding, also known as welding, is a manufacturing process and technology that joins metals or other thermoplastic materials such as plastics by means of heat, high temperature or high pressure.

Welding achieves the purpose of bonding through the following three ways:

1. Fusion welding - heat the workpiece to be joined to make it partially melted to form a molten pool, the molten pool will be joined after cooling and solidifying, and the melt filler can be added to assist if necessary, it is suitable for the welding of various metals and alloys, without pressure.

2. Pressure welding - the welding process must apply pressure to the weldment, which belongs to the processing of various metal materials and some metal materials.

3. Brazing - using metal materials with lower melting point than the base metal as brazing metal, using liquid brazing metal to wet the base metal, filling the joint gap, and diffusion with the base metal to achieve link weldments. It is suitable for the welding of various materials, and also suitable for the welding of different metals or dissimilar materials.

Hello, welding is the purpose of merging two identical materials, or two different things, together through welding.

What kind of welding are you talking about? There are many kinds of welding, and the materials for welding are also different, but in general, the two materials are welded together.

1. Protective effect: the gas, slag or directly input protective gas generated by the welding material during welding will isolate the molten metal from the outside air and prevent the metal from being oxidized or nitrided.

Thus playing a protective role.

2. Metallurgical effect: During the welding process, a series of chemical and metallurgical reactions occur between the welding material and the molten metal, which can transition beneficial alloying elements to the weld on the one hand, and exclude impurities such as sulfur, phosphorus, oxygen, nitrogen and hydrogen in the weld on the other hand, so that the weld can obtain the required chemical composition, improve the structure and improve the performance.

3. Filling: As a filler metal, the welding material can fill the groove on the weldment after melting to form a solid weld.

4. Improve the performance of the welding process: the welding material can stabilize the arc, reduce the spatter, improve the welding seam forming, and improve the performance of the welding process.

1. Electrode arc welding

Principle - an arc welding method for welding with manually operated electrodes. A stable burning arc established between the electrode and the weldment is used to melt the electrode and weldment, resulting in a strong welded joint. It belongs to the joint protection of gas slag.

Main features - flexible operation; Low assembly requirements for the welded joint; Wide range of weldable metal materials; Low welding productivity; Weld quality dependence (depends on the welder's operational skills and on-site performance).

Application - Widely used in shipbuilding, boilers and pressure vessels, machinery manufacturing, building structures, chemical equipment and other manufacturing and maintenance industries. It is suitable for welding of various metal materials, various thicknesses and various structural shapes (in the above industries).

2. Submerged arc welding (automatic welding):

Principle – The arc burns under the flux layer. A weld is formed by melting the wire, flux, and base metal (weldment) using the heat generated by the burning arc between the wire and the weldment. Slag protection.

Main features - high welding productivity; Welding seam***; Low welding cost; good working conditions; Difficult to weld in a spatial position; High requirements for the assembly quality of weldments; It is not suitable for welding thin plates (when the welding current is less than 100A, the arc stability is not good) and short welds.

Application——Widely used in shipbuilding, boilers, bridges, lifting machinery and metallurgical machinery manufacturing. Submerged arc welding can be used for weldments where the weld can be kept in a horizontal position or the angle of inclination is not large. The thickness of the plate should be greater than 5 mm (burn-through resistant).

Welded carbon structural steel, low-alloy structural steel, stainless steel, heat-resistant steel, composite steel, etc.

3. Carbon dioxide gas shielded welding (automatic or semi-automatic welding):

Principle: Melting electrode arc welding method using carbon dioxide as shielding gas. Atmospheric protection.

Main features - high welding productivity; Low welding cost; Small welding deformation (arc heating concentration); High welding quality; Simple operation; High spatter rate; It is difficult to solder with AC power; Poor wind resistance; Non-ferrous metals that are susceptible to oxidation cannot be welded.

4. MIG MAG welding (molten inert gas active gas shielded welding):

MIG welding principle - an arc welding method that uses inert gas as shielding gas and welding wire as melting electrode. The shielding gas is usually argon or helium or a mixture of them. MIG uses inert gas, MAG adds a small amount of active gas, such as oxygen, carbon dioxide, etc., to the inert gas.

5. TIG welding (tungsten inert gas shielded welding).

Principle - under the protection of inert gas, the arc heat generated between the tungsten electrode and the weldment is used to melt the base metal and the filled welding wire (or without filling the welding wire) to form a welding seam. The electrode does not melt during the welding process.

6. Plasma arc welding.

Principle - with the help of the water-cooled nozzle on the arc constraint effect, obtain a high energy density plasma arc for welding.

The electrode is a metal wire used in arc welding, which is mainly composed of a welding core and a skin, and the welding core is a metal core that is coated with a coating in the electrode.

In manual welding, the solder core is both an electrode and a filler metal, and the outer surface of the metal core is covered with a chemical coating, which is a coating layer that is pressed on the surface of the solder core. It is composed of a variety of ores, ferroalloys, cellulose and binders, and its function is mainly to conduct welding current, and melt itself with the combustion of the arc and enter the molten pool on the surface of the weldment and the weldment capacity as a whole, filling the gap between the welded workpieces.