Welding classification

Commonly used is electric and gas welding, as well as laser welding, brazing, heat welding, electron beam welding, explosion welding, etc.

17 welding methods

1. hand arc welding

Hand arc welding is a variety of arc welding methods in the development of the earliest, and is still the most widely used method of welding. It is coated with paint on the outside of the electrode as the electrode and filler metal, the arc is burned between the end of the electrode and the surface of the workpiece to be welded. Paint in the arc heat on the one hand can produce gas to protect the arc, on the other hand, can produce slag to cover the surface of the molten pool, to prevent the molten metal and the surrounding gas interaction. Slag more important role is to produce physical and chemical reaction with the molten metal or add alloying elements to improve the properties of the weld metal.

Hand arc welding equipment is simple, lightweight, * work flexible. Can be applied to the maintenance and assembly of the welding of short seams, in particular, can be used for hard to reach parts of the welding. Hand-arc welding with the corresponding electrodes can be applied to most industrial carbon steel, stainless steel, cast iron, copper, aluminum, nickel and its alloys.

2. tungsten gas-shielded arc welding

This is a non-melting pole gas-shielded arc welding, is the use of tungsten electrode and the arc between the workpiece to make the metal melt and form a weld. Welding process tungsten electrode does not melt, only the role of the electrode. At the same time by the torch nozzle into the argon or helium for protection. Additional metal can also be added as needed. In the international commonly known as TIG welding.

TIG welding is an excellent method of joining sheet metal and base welding because of the well controlled heat input. This method can be used to join almost all metals, especially for welding aluminum, magnesium, metals that can form refractory oxides, as well as titanium and zirconium, such as active metals. The weld quality is high, but the welding speed is slow compared to other arc welding methods.

3. melting pole gas shielded arc welding

This welding method is the use of continuous feeding of the wire and the workpiece between the burning arc as a heat source, by the torch nozzle gas shielded arc to carry out welding.

Molten electrode gas shielded arc welding usually used shielding gas: argon, helium, CO2 gas or a mixture of these gases. Argon or helium as a shielding gas is called fusion inert gas shielded arc welding (in the international abbreviation for MIG welding); inert gas and oxidizing gas (O2, CO2) mixture of gas as a shielding gas, or CO2 gas or CO2 + O2 mixture of gas as a shielding gas, or CO2 gas or CO2 + O2 mixture of gas as a shielding gas, collectively referred to as the melting electrode activated gas-shielded arc welding (in the international abbreviation for MAG welding). In the international abbreviation for MAG welding).

The main advantage of MAG welding is that it is easy to carry out a variety of positions of the welding, but also has a faster welding speed, high deposition rate. Melting pole active gas shielded arc welding can be applied to most major metals, including carbon steel, alloy steel. Fused electrode inert gas shielded welding is suitable for stainless steel, aluminum, magnesium, copper, titanium, zirconium and nickel alloys. Arc spot welding is also possible using this welding method.

4. plasma arc welding

Plasma arc welding is also a kind of non-melting pole arc welding. It is the use of the electrode and the workpiece between the compression arc (called forward transfer arc) to achieve the welding. The electrode used is usually tungsten. Generate plasma arc plasma gas can be argon, nitrogen, helium or a mixture of the two. It is also protected by an inert gas through the nozzle. Welding can be added filler metal, can also not add filler metal.

Plasma arc welding welding, because of its arc straight, energy density, and thus the arc penetration ability. Plasma arc welding welding hole effect, for a certain thickness range of most of the metal can not open the bevel butt joints, and can ensure that the penetration and weld uniformity. Therefore, plasma arc welding has high productivity and good weld quality. However, plasma arc welding equipment (including nozzles) is more complex, the control of welding process parameters require higher.

Tungsten gas shielded arc welding can be welded most of the metal, can be used plasma arc welding. Compared with it, for 1mm below the very thin metal welding, plasma arc welding can be easier to carry out.

5. Tubular wire arc welding

Tubular wire arc welding is also the use of continuous feeding of the wire and the workpiece between the burning arc as a source of heat for welding, can be considered a type of melting electrode gas shielded welding. The wire used is a tubular wire with various components of flux inside the tube. When welding, plus shielding gas, mainly CO2. flux thermal decomposition or melting, play a slag protection pool, penetration of alloy and stabilize the arc and other roles.

Tubular wire arc welding in addition to the advantages of the above melting electrode gas shielded arc welding, due to the role of the flux in the tube, so that it has more advantages in metallurgy. Tubular wire arc welding can be applied to most ferrous metals in a variety of joints. Tube wire arc welding in some industrially advanced countries have been widely used.

"Tubular wire" that is now called "flux-cored wire" - posters note

6. resistance welding

This is a class of welding methods, including resistance heat as the energy source. Energy source of a class of welding methods, including slag resistance heat as the energy source of electroslag welding and solid resistance heat as the energy source of resistance welding. Because the electroslag welding has more unique characteristics, it is placed in the back of the introduction. Here mainly introduces several solid resistance heat as the energy source of resistance welding, mainly spot welding, seam welding, convex welding and butt welding.

Resistance welding is generally the workpiece in a certain electrode pressure and the use of electric current through the workpiece when the resistance of the heat generated by the two workpieces between the contact surface melting and realize the connection of the welding method. Usually use a large current. Pressure is always applied during the welding process in order to prevent an arc from occurring on the contact surface and to forge the weld metal.

When this type of resistance welding is carried out, the surface quality of the workpiece to be welded is of paramount importance for obtaining consistent weld quality. Therefore, the electrode and the workpiece and the workpiece and the workpiece contact surface must be cleaned before welding.

Spot welding, seam welding and convex welding gore is the welding current (single-phase) is large (thousands to tens of thousands of amperes), short energization time (a few weeks wave to a few seconds), the equipment is expensive, complex, high productivity, and therefore suitable for mass production. Mainly used for welding thin plate assemblies with thickness less than 3mm. Various types of steel, aluminum, magnesium and other non-ferrous metals and their alloys, stainless steel, etc. can be welded.

7. Electron beam welding

Electron beam welding is a concentrated high-speed electron beam bombardment of the surface of the workpiece when the heat generated by the welding method.

Electron beam welding, electron beam generated by the electron gun and accelerated. Commonly used electron beam welding: high vacuum electron beam welding, low vacuum electron beam welding and non-vacuum electron beam welding. The first two methods are carried out in a vacuum chamber. Welding preparation time (mainly vacuum time) is longer, the size of the workpiece is limited by the size of the vacuum chamber.

Electron beam welding and arc welding, compared with the main characteristics of the weld depth, melt width is small, high purity of the weld metal. It can be used in both very thin material precision welding, but also can be used in very thick (up to 300mm) component welding. All metals and alloys that can be melt welded by other welding methods can be welded by electron beam welding. It is mainly used for welding products that require high quality. It can also solve the welding of dissimilar metals, easily oxidized metals and refractory metals. But not suitable for high-volume products.

8. Laser welding

Laser welding is the use of high-power coherent monochromatic photon stream focused laser beam as a heat source for welding. This welding method usually have continuous power laser welding and pulsed power laser welding.

Laser welding has the advantage that it does not need to be carried out in a vacuum, while the disadvantage is that the penetration is not as strong as electron beam welding. Laser welding can be performed with precise energy control, thus enabling the welding of precision micro devices. It can be applied to many metals, especially to solve some difficult to weld metal and dissimilar metal welding.

9. brazing

Brazing energy can be chemical reaction heat, can also be indirect heat. It is the use of melting point than the melting point of the material to be welded metal as brazing material, after heating the brazing material melting, * capillary action of the brazing material and into the gap between the contact surface of the joints, wetting of the welded metal surface, so that the liquid phase and the solid phase of the mutual diffusion and the formation of brazed joints. Therefore, brazing is a solid-phase and liquid-phase welding method.

Brazing heating temperature is low, the base material does not melt, and do not need to apply pressure. But before welding must take certain measures to remove the welded workpiece surface oil, dust, oxide film, etc.. This is to make the workpiece wettability, to ensure that the quality of the joint is an important guarantee.

The liquid phase line humidity of brazing material is higher than 450 ℃ and lower than the melting point of the base metal, known as hard brazing; lower than 450 ℃, known as soft brazing.

Based on the heat source or heating method brazing can be divided into: flame brazing, induction brazing, brazing in the furnace, dip brazing, resistance brazing.

Brazing because the heating temperature is relatively low, so the performance of the workpiece material has less impact on the weldment stress deformation is also small. But the brazed joints are generally lower strength, heat resistance is poor.

Brazing can be used for welding carbon steel, stainless steel, high-temperature alloys, aluminum, copper and other metal materials, but also can be connected to dissimilar metals, metals and non-metals. Suitable for welding joints that are not loaded or working at room temperature, especially suitable for precision, miniature, and complex multi-brazed weldments.

10. Electroslag welding

Electroslag welding is a slag resistance heat as the energy source of the welding method. Welding process is carried out in the vertical welding position, in the assembly gap formed by the two end faces of the workpiece and both sides of the water-cooled copper slide. The welding process utilizes the resistance heat generated by the current passing through the slag to melt the end of the workpiece.

Based on the shape of the electrode used in welding, electroslag welding is divided into wire electrode slag welding, plate electrode slag welding and fusion nozzle slag welding.

The advantages of electroslag welding are: the thickness of the workpiece can be welded (from 30mm to more than 1000mm), high productivity. Mainly used in the section butt joints and butyl joints welding.

Electroslag welding can be used for a variety of steel structure welding, can also be used for casting group welding. Electroslag welding joints due to heating and cooling are slower, the heat affected zone is wide, coarse microstructure, toughness, so after welding generally have to be normalized.

11. High-frequency welding

High-frequency welding is a solid resistance heat as an energy source. Welding the use of high-frequency current in the workpiece resistance heat generated by the workpiece weld area surface heating to melt or close to the plastic state, and then apply (or not) the top of the forging force to achieve the combination of metals. Therefore, it is a solid-phase resistance welding method.

High-frequency welding according to the high-frequency current in the workpiece to produce heat can be divided into contact high-frequency welding and induction high-frequency welding. Contact high-frequency welding, high-frequency current through mechanical contact with the workpiece and into the workpiece. Induction high-frequency welding, high-frequency current through the workpiece external inductor ring coupling effect and produce inductive current in the workpiece.

High-frequency welding is a highly specialized welding method, to be equipped with special equipment according to the product. High productivity, welding speed up to 30m/min. mainly used in the manufacture of pipe longitudinal seam or spiral seam welding.

12. gas welding

Gas welding is a gas flame as a heat source of a welding method. The most widely used is to acetylene gas as fuel oxygen - acetylene flame. Because the equipment is simple and easy to use, but the gas welding heating speed and productivity is low, the heat-affected zone is large, and easy to cause large deformation.

Gas welding can be used for many ferrous metals, non-ferrous metals and alloys. Generally applicable to maintenance and single piece of thin plate welding.

13. gas pressure welding

Gas pressure welding and gas welding, gas pressure welding is also a gas flame as a heat source. Welding the two butt of the end of the workpiece heated to a certain temperature, and then apply enough pressure to obtain a solid joint. It is a solid phase welding.

Gas pressure welding without filler metal, commonly used in railroad track welding and steel welding.

14. Blast * blast welding

Blast * blast welding is also a chemical reaction heat as the energy source of another solid-phase welding method. But it is the use of explosives * explosions * explosions generated by the energy to realize the metal connection. Under the action of the blast wave, two pieces of metal in less than a second can be accelerated by the impact of the formation of a metal bond.

In a variety of welding methods, burst * explosion welding can be welded to the widest range of dissimilar metal combinations. Can be used burst * explosion welding will be metallurgically incompatible with the two metals welded into a variety of transition joints. Explosive*fry welding is mostly used for cladding flat plates with a fairly large surface area, and is an efficient method for manufacturing composite plates.

15.friction welding

Friction welding is a solid-phase welding with mechanical energy as energy source. It is the use of mechanical friction between the two surfaces of the heat generated to achieve the connection of metals.

The heat of friction welding is concentrated at the joint surface, so the heat affected zone is narrow. Pressure must be applied between the two surfaces, in most cases the pressure is increased at the termination of heating, so that the hot metal by the top of the forging and bonding, and generally the bonding surface does not melt.

Friction welding productivity is high, in principle, almost all can be hot forging metal can be friction welding. Friction welding can also be used for dissimilar metal welding. To apply to the cross-section of a round workpiece with a maximum diameter of 100mm.

16. ultrasonic welding

Ultrasonic welding is also a mechanical energy as the energy source of solid-phase welding method. Ultrasonic welding, welding workpiece in the lower static pressure, from the acoustic pole issued by the high-frequency vibration can make the joint surface to produce a strong crack friction and heated to the welding temperature and the formation of the bond.

Ultrasonic welding can be used for most of the metal materials between the welding, can realize the metal, dissimilar metals and metal and non-metal welding. It can be applied to the repeated production of metal joints of wires, foils or thin sheet metal joints up to 2-3mm.

17. diffusion welding

Diffusion welding is generally a solid-phase welding method using indirect heat as an energy source. Usually in a vacuum or protective atmosphere. Welding so that the two surfaces of the welded workpiece at high temperature and high pressure contact and insulation for a certain period of time, in order to achieve the inter-atomic distance, through the atomic plain mutual diffusion and bonding. Welding not only need to clean the surface of the workpiece oxides and other impurities, and surface roughness should be below a certain value to ensure the quality of welding.

Diffusion welding on the properties of the welded material almost no harmful effects. It can weld a lot of the same and dissimilar metals and some non-metallic materials, such as ceramics.

Diffusion welding can weld complex structures and workpieces with large differences in thickness.