Welding means by heating or pressurizing, or both;
With or without filler material;
A process that enables the bonding between two separated metal surfaces to form a permanent connection.
Today, let me show you a variety of welding methods!
There are 17 kinds in total. How many do you know?
1. Manual arc welding
Manual arc welding is one of the earliest and still widely used welding methods among various arc welding methods.
It uses the coated electrode as the electrode and filler metal, and the arc burns between the end of the electrode and the surface of the workpiece to be welded.
Under the action of arc heat, on the one hand, the coating can produce gas to protect the arc, on the other hand, it can produce slag to cover the surface of the molten pool to prevent the interaction between the molten metal and the surrounding gas.
The more important role of slag is to produce physical and chemical reactions with molten metal or add alloying elements to improve the properties of weld metal.
Manual arc welding equipment is simple, light and flexible.
It can be applied to the welding of short joints in maintenance and assembly, especially for the welding of parts that are difficult to reach.
Manual arc welding with corresponding electrodes can be applied to most industrial carbon steel, stainless steel, cast iron, copper, aluminum, nickel and their alloys.
2. Gas tungsten arc welding
This is a non melting electrode gas shielded arc welding, which uses the arc between tungsten electrode and workpiece to melt the metal and form weld.
In the welding process, the tungsten electrode does not melt and only acts as an electrode.
At the same time, argon or helium is sent into the nozzle of the welding torch for protection. Additional metals can also be added as needed.
It is commonly known as TIG welding in the world.
Gas tungsten arc welding is an excellent method for connecting sheet metal and backing welding because it can well control heat input.
This method can be used to connect almost all metals, especially for welding metals such as aluminum and magnesium, which can form refractory oxides, and active metals such as titanium and zirconium.
This welding method has high weld quality, but its welding speed is slower than other arc welding.
3. Gas metal arc welding
This welding method uses the arc burning between the continuously fed welding wire and the workpiece as the heat source and the gas shielded arc ejected by the torch nozzle for welding.
The commonly used shielding gases for GMAW are argon, helium, CO2 or a mixture of these gases. When argon or helium is used as shielding gas, it is called MIG welding (hereinafter referred to as MIG welding in the world);
When the mixture of inert gas and oxidizing gas (O2, CO2) is used as the shielding gas, or when CO2 gas or CO2 + O2 mixture is used as the shielding gas, or when CO2 gas or CO2 + O2 mixture is used as the shielding gas, it is collectively referred to as MIG welding (internationally referred to as MAG welding).
The main advantage of GMAW is that it can weld at various positions conveniently.
At the same time, it also has the advantages of fast welding speed and high deposition rate.
GMAW is applicable to most major metals, including carbon steel and alloy steel.
MIG welding is suitable for stainless steel, aluminum, magnesium, copper, titanium, zirconium and nickel alloys.
This welding method can also be used for arc spot welding.
4. Plasma arc welding
Plasma arc welding is also a non melting electrode arc welding.
It uses the compressed arc (called forward transfer arc) between the electrode and the workpiece to realize welding.
The electrodes used are usually tungsten electrodes.
The plasma gas for generating plasma arc can be argon, nitrogen, helium or a mixture of the two.
It is also protected with inert gas through the nozzle.
Filler metal may or may not be added during welding.
When plasma arc welding, because of its straight arc and high energy density, it has strong arc penetration ability.
The keyhole effect produced by plasma arc welding can be butt jointed without groove for most metals within a certain thickness range, and can ensure the uniformity of penetration and weld.
Therefore, plasma arc welding has high productivity and good weld quality.
However, plasma arc welding equipment (including nozzle) is relatively complex, and the control requirements of welding process parameters are high.
Plasma arc welding can be used for most metals that can be welded by tungsten gas shielded arc welding.
In contrast, it is easier to weld extremely thin metal below 1mm with plasma arc welding.
5. Tubular wire arc welding
Tubular welding wire arc welding also uses the arc burning between the continuously fed welding wire and the workpiece as the heat source for welding, which can be considered as a type of GMAW.
The welding wire used is tubular welding wire, which is filled with flux of various components.
When welding, add shielding gas, mainly CO2.
The flux decomposes or melts when heated, which plays a role in slagging, protecting the solution pool, alloying and stabilizing the arc.
In addition to the advantages of the above-mentioned GMAW, tubular wire arc welding has more advantages in metallurgy due to the action of flux in the pipe.
Tubular wire arc welding can be applied to the welding of most ferrous metal joints.
Tubular wire arc welding has been widely used in some industrial advanced countries.
“Tubular welding wire” is now called “flux cored welding wire”.
6. Resistance welding
This is a kind of welding method with resistance heat as energy, including electroslag welding with slag resistance heat as energy and resistance welding with solid resistance heat as energy.
Since electroslag welding has more unique characteristics, it will be introduced later.
This paper mainly introduces several resistance welding with solid resistance heat as energy, mainly including spot welding, seam welding, projection welding and butt welding.
Resistance welding is generally a welding method that makes the workpiece under a certain electrode pressure and uses the resistance heat generated when the current passes through the workpiece to melt the contact surface between the two workpieces to realize the connection.
Larger currents are usually used.
In order to prevent arcing on the contact surface and to forge the weld metal, pressure must always be applied during welding.
In this kind of resistance welding, the surface of the workpiece to be welded is of primary importance to obtain stable welding quality.
Therefore, the contact surface between electrode and workpiece and between workpiece and workpiece must be cleaned before welding.
The contradiction between spot welding, seam welding and projection welding is that the welding current (single-phase) is large (thousands to tens of thousands of AMPS), the power on time is short (several cycles to several seconds), the equipment is expensive and complex, and the productivity is high, so it is suitable for mass production.
It is mainly used for welding thin plate components with thickness less than 3mm.
All kinds of steel, aluminum, magnesium and other non-ferrous metals and their alloys and stainless steel can be welded.
7. Electron beam welding
Electron beam welding is a method of welding with the heat energy generated when the concentrated high-speed electron beam bombards the surface of the workpiece.
During electron beam welding, the electron beam is generated and accelerated by the electron gun.
Common electron beam welding includes 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.
The welding preparation time (mainly vacuum pumping time) is long, and the workpiece size is limited by the size of vacuum chamber.
Compared with arc welding, electron beam welding is characterized by large weld penetration, small weld width and high weld metal purity.
It can be used not only in the precise welding of very thin materials, but also in the welding of very thick (up to 300mm thick) components.
All metals and alloys that can be melt welded by other welding methods can be welded by the electron beam.
It is mainly used for welding products with high-quality requirements.
It can also solve the welding of dissimilar metals, easily oxidized metals and refractory metals.
But it is not suitable for mass production.
8. Laser welding
Laser welding is a kind of welding using laser beam focused by high-power coherent monochromatic photon flow as heat source.
This welding method usually includes continuous power laser welding and pulse power laser welding.
The advantage of laser welding is that it does not need to be carried out in vacuum, while the disadvantage is that the penetration is not as strong as electron beam welding.
Laser welding can carry out accurate energy control, so it can realize the welding of precision micro devices.
It can be applied to many metals, especially to solve the welding of some difficult to weld metals and dissimilar metals.
The energy of brazing can be chemical reaction heat or indirect heat energy.
It uses the metal whose melting point is lower than the melting point of the material to be welded as the solder, and melts the solder after heating, capillary action will put the solder and into the gap of the contact surface of the joint, wet the surface of the metal to be welded, and make the liquid phase and solid phase diffuse each other to form a brazed joint.
Therefore, brazing is a solid-phase and liquid-phase welding method.
The brazing heating temperature is low, the base metal does not melt, and there is no need to apply pressure.
However, before welding, certain measures must be taken to remove the oil stain, dust, oxide film, etc. on the surface of the parts to be welded.
This is an important guarantee for the good wettability of the workpiece and ensuring the quality of the joint.
When the liquidus humidity of solder is higher than 450 ℃ and lower than the melting point of base metal, it is called brazing;
Below 450 ℃, it is called soft soldering.
According to different heat sources or heating methods, brazing can be divided into flame brazing, induction brazing, furnace brazing, dip brazing, resistance brazing, etc.
During brazing, the heating temperature is relatively low, so it has little effect on the properties of workpiece materials and the stress and deformation of weldments are also small.
However, the strength of brazed joints is generally low and the heat resistance is poor.
Brazing can be used to weld carbon steel, stainless steel, superalloy, aluminum, copper and other metal materials.
It can also connect dissimilar metals, metals and non metals.
It is suitable for welding joints with little load or working at room temperature, especially for precision, micro and complex weldments with multiple brazing joints.
10. Electroslag welding
Electroslag welding is a welding method using the resistance heat of slag as energy.
The welding process is carried out in the vertical welding position and in the assembly gap formed by the end faces of the two workpieces and the water-cooled copper sliding blocks on both sides.
During welding, the resistance heat generated by the current through the slag is used to melt the end of the workpiece.
According to the electrode shape used in welding, electroslag welding is divided into wire electroslag welding, plate electroslag welding and nozzle electroslag welding.
Electroslag welding has the advantages of large thickness of weldable workpiece (from 30mm to more than 1000mm) and high productivity.
It is mainly used for welding butt joints and T-joints on cross sections.
Electroslag welding can be used for the welding of various steel structures and the assembly welding of castings.
Due to the slow heating and cooling, wide heat affected zone, coarse microstructure and toughness of electroslag welded joint, normalizing treatment is generally required after welding.
11. High frequency welding
High frequency welding takes solid resistance heat as energy.
During welding, the resistance heat generated by high-frequency current in the workpiece is used to heat the surface of the welding area of the workpiece to the molten or close plastic state, and then the upsetting force is applied (or not applied) to realize the metal bonding.
Therefore, it is a solid-state resistance welding method.
High frequency welding can be divided into contact high frequency welding and induction high frequency welding according to the way that high frequency current generates heat in the workpiece.
When contacting high-frequency welding, high-frequency current is transmitted to the workpiece through mechanical contact with the workpiece.
During induction high-frequency welding, the high-frequency current generates induced current in the workpiece through the coupling effect of the induction coil outside the workpiece.
High frequency welding is a highly specialized welding method, and special equipment shall be equipped according to the products.
High productivity, welding speed up to 30m / min.
It is mainly used for welding longitudinal seam or spiral seam when manufacturing pipes.
12. Gas welding
Gas welding is a welding method using gas flame as heat source.
The most widely used is the oxygen acetylene flame with acetylene gas as fuel.
Because the equipment is simple and easy to use, but the heating speed and productivity of gas welding are low, the heat affected zone is large, and it is easy to cause large deformation.
Gas welding can be used for welding many ferrous metals, nonferrous metals and alloys.
It is generally applicable to maintenance and single sheet welding.
13. Pneumatic welding
Like gas welding, gas pressure welding also takes gas flame as heat source.
When welding, heat the ends of two butt jointed workpieces to a certain temperature, and then apply sufficient pressure to obtain a firm joint.
It is a solid-state welding.
Pneumatic welding without filler metal is often used for rail welding and reinforcement welding.
14. Explosive welding
Explosive welding is also another solid-state welding method with chemical reaction heat as energy.
But it uses the energy produced by explosive explosion to realize metal connection.
The impact of the metal can be accelerated to form a wave in less than two seconds.
Among various welding methods, the combination of dissimilar metals that can be welded by explosive welding is the widest.
Explosive welding can be used to weld two metals that are incompatible in metallurgy into various transition joints.
Explosive welding is mostly used for covering flat plates with considerable surface area. It is an efficient method for manufacturing composite plates.
15. Friction welding
Friction welding is solid-phase welding with mechanical energy as energy.
It uses the heat generated by mechanical friction between two surfaces to realize the connection of metals.
The heat is concentrated on the narrow welding surface.
Pressure must be applied between the two surfaces.
In most cases, the pressure is increased at the end of heating, so that the hot metal is combined by upsetting.
Generally, the joint surface does not melt.
Friction welding has high productivity.
In principle, almost all metals that can be hot forged can be friction welded.
Friction welding can also be used for the welding of dissimilar metals.
It shall be applicable to workpieces with a maximum diameter of 100mm with a circular cross-section.
16. Ultrasonic welding
Ultrasonic welding is also a solid-state welding method with mechanical energy as energy.
When ultrasonic welding is carried out, under low static pressure, the high-frequency vibration emitted by the sound pole can produce strong crack friction on the joint surface and heat it to the welding temperature to form a joint.
Ultrasonic welding can be used for the welding between most metal materials, and can realize the welding between metal, dissimilar metal and metal and non-metal.
It can be applied to the repeated production of wire, foil or sheet metal joint less than 2-3mm.
17. Diffusion welding
Diffusion welding is generally a solid-state welding method with indirect heat energy as energy.
It is usually carried out under vacuum or protective atmosphere.
During welding, the surfaces of the two welded parts shall be contacted under high temperature and high pressure and kept warm for a certain time, so as to achieve the distance between atoms and combine through simple mutual diffusion of atoms.
Before welding, not only the oxide and other impurities on the workpiece surface need to be cleaned, but also the surface roughness should be lower than a certain value to ensure the welding quality.
Diffusion welding has almost no harmful effect on the properties of the material to be welded.
It can weld many same and dissimilar metals and some non-metallic materials, such as ceramics.
Diffusion welding can weld workpieces with complex structure and great thickness differences.