What are the applications of electric welding? What are the classifications of electric welding?

Submerged arc welding (including submerged arc surfacing and electroslag surfacing welding, etc.) is a method in which the arc is burned under the flux layer for welding. Its inherent welding quality is stable, welding productivity is high, no arc light and little smoke and dust, etc., making it the main welding method in the production of important steel structures such as pressure vessels, pipe sections, and box-shaped beams and columns. In recent years, although many new welding methods with high efficiency and high quality have emerged, the application field of submerged arc welding has not been affected in any way.

Submerged arc welding accounts for about 10% of the total amount of deposited metal by various fusion welding methods, and it has not changed much over the years.

In our country, welding operations need to be licensed, welders are the type of work that belongs to the access category, in the professional qualifications of skilled personnel, only five of the 81 types of work in the access category, welders are one of them, and the actual situation is that most of the industry practitioners are unlicensed operations. With the continuous standardization of technology and the relevant requirements of the industry, more and more people want to take a welding certificate, the advantage of the certificate is still very large, first of all, the salary of the certificate and the non-certificate are very different, often able to reach more than double or higher level. Therefore, the issue of short-term welder training has naturally become a concern for practitioners.

Welding as an industrial "tailor" is a very important means of processing in industrial production, the quality of welding plays a decisive role in the quality of the product, so, what is the future development of welding technology?

Industry outlook. With the development of production, welding is widely used in aerospace, aviation, nuclear industry, shipbuilding, construction and machinery manufacturing and other industrial sectors, in China's economic development, welding technology is an indispensable means of processing. After entering the 21st century, welding is an important part of the manufacturing industry, and the rapid development, so it has brought unprecedented development opportunities to the welding industry.

At present, China consumes 300 million tons of steel every year (about tons of welded structure), and needs about 750,000 welding machines, and the welding industry will continue to grow in the next 8 10 years.

The application range of electric welding is very wide, and now the development of science and technology is inseparable from electric welding, all kinds of factories, and enterprise maintenance, the construction of houses, are inseparable from electric welding, welders are still an important position in our country.

1. Arc welding.

Arc welding is currently the most widely used welding method. It includes: hand arc welding, submerged arc welding, tungsten gas arc welding, plasma arc welding, MIG/MAG welding, etc.

2. Resistance welding.

This is a class of welding methods that use resistance heat as energy source, including electroslag welding with slag resistance heat as energy source and resistance welding with solid resistance heat as energy source. Resistance welding includes: resistance spot welding, coating welding, seam welding, high-frequency welding, flash butt welding.

3. High-energy beam welding.

This type of welding method includes: electron beam welding and laser welding.

4. Brazing. The energy source for brazing can be either the heat of chemical reaction or indirect heat. It is the use of the melting point lower than the melting point of the welded material as the brazing metal, after heating to melt the brazing metal, by the capillary action of the brazing metal and into the joint contact surface of the gap into the wetting metal surface, so that the liquid phase and the solid phase diffuse each other to form a brazing joint.

5. Other welding methods.

These welding methods belong to different degrees of specialization, and their scope of application is narrow. It mainly includes electroslag welding and high-frequency welding with resistive heat as the energy source; Gas welding, pneumatic welding, and first-class welding with chemical energy as the welding energy source; Friction welding, cold pressure welding, ultrasonic welding, and diffusion welding with mechanical energy as the welding energy source.

Hand arc welding. Hand arc welding is a variety of arc welding.

It is one of the earliest developed welding methods and the most widely used welding method. It uses an externally coated electrode as an electrode and filler metal, and the arc is burned between the end of the electrode and the surface of the workpiece to be welded. Under the action of arc heat, the coating can produce gas to protect the arc on the one hand, and on the other hand, it can produce slag to cover the surface of the molten pool to prevent the interaction of the molten metal with the surrounding gas.

The more important role of slag is to produce physicochemical reactions with molten metals.

Or add alloying elements to improve the weld metal properties.

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

2.Tungsten gas arc welding.

This is a kind of non-MIG/MAG arc welding, which uses the electric arc between the tungsten electrode and the workpiece to melt the metal to form a weld. During the welding process, the tungsten electrode does not melt and only acts as an electrode. At the same time, argon or helium is fed 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 joining sheet metal and root welding due to its good control of heat input. This method can be used for joining almost all metals, but is particularly suitable for welding metals such as aluminium and magnesium, which form refractory oxides, as well as reactive metals such as titanium and zirconium. This welding method has a high quality weld seam but a slower welding speed compared to other arc welding.

3.MIG/MAG arc welding.

This welding method utilizes a continuously fed welding wire.

The arc burning between the workpiece and the workpiece is used as a heat source, and the gas shielded arc emitted from the torch nozzle is used for welding.

Plasma arcs have higher energy densities, temperatures, and plasma flow velocities than GTAW arcs, as well as greater penetration capacity. In addition, the plasma arc is not as divergent as the GTAW arc and is almost cylindrical. Therefore, plasma arc welding has many advantages over GTAW welding;

1. The plasma arc is cylindrical, and the size of its heating area is basically unrelated to the distance between the welding torch and the workpiece, so the influence of the distance between the welding torch and the workpiece on the quality of the weld is not as sensitive as GTAW, which is very beneficial to manual operation.

2. The plasma with high temperature, energy density and plasma flow force has a strong small hole effect, which is suitable for single-sided welding and double-sided forming. Plasma arc welding has a small heat-affected zone and a very ideal weld shape. The edges of the fuse lines on both sides of the weld are nearly parallel, reducing angular deformation.

3. The plasma arc with high energy density and fast flow rate has good stability and rigidity, and is not easy to deviate from the nearest point it points to, so it can be welded at high speed, and the alignment requirements of the joint are significantly reduced. The plasma arc weld is narrow and deep, and the energy utilization rate is high. Due to the high welding speed, the welding productivity is significantly increased.

Plasma arc welding is mainly used in the manufacture of welded pipes, the welding of small-size welds on thin plate parts and equipment, the welding of pipe root welds and the welding of thin-walled pipes. This welding method is also used in some areas of application of electron beam welding, which has the advantage of welding in the atmosphere and at a much lower cost of equipment compared to electron beam welding.

Plasma arc welding can be operated by manual welding or by automatic welding. This method can be used to weld all industrial metals. All GTAW plasma arcs must penetrate the melt pool, so weldable thicknesses range from 1 16 to 19 mm).

The specific thickness range of each material is also related to its specific composition. Fusion plasma arc welding, on the other hand, is used to weld materials with a thickness of . When multi-layer multi-pass welding is used, the maximum weldable thickness is infinite.

Filler wire is required for welding thick plates.

Characteristics of electrode arc welding.

1. The equipment is simple.

Low-cost electrode arc welding uses arc welding power supply with descending external characteristics and some simple tools, and the equipment structure is simple, which is convenient for on-site maintenance, maintenance and repair; The device is light and easy to move; The equipment is easy to use, install, and simple to operate; Low investment, low cost.

2. The process is flexible.

Adaptable electrode arc welding is suitable for the welding of carbon steel, alloy steel, stainless steel, cast iron, copper and its alloys, aluminum and its alloys, nickel and its alloys. Cables can be used to extend welding over long distances. It is suitable for welding different positions, joint forms, weldment thicknesses, single products or batch products, and complex structural weld parts.

For some irregular welds, welds that are not easy to achieve mechanized welding, and welding in narrow positions, electrode arc welding appears to be more flexible and adaptable.

3. High labor intensity and low efficiency.

The electrode arc welding used in electrode arc welding has a limited length and cannot be welded continuously, so the efficiency is low. Due to the manual operation, the labor of the workers is poor, the labor intensity is high, and the quality of the weld depends to a certain extent on the operation skill level of the welder.

Application of electrode arc welding.

It is widely used in the welding of carbon steel, alloy steel, heat-resistant steel, stainless steel, cast iron and non-ferrous metals. It is suitable for welding metal materials with different thicknesses and different positions, as well as for welding of dissimilar metals, and the welded joint can be equal to the strength of the workpiece (base metal). Therefore, it is one of the most widely used welding methods in welding production.

The equipment required for electrode arc welding is composed of AC (DC) welding machine, ground wire, welding wire, welding handle (welding tong), welding mask (with goggles), etc., among which the welding tongs have several specifications such as A, and their numerical values indicate the size of the current that can be withheld.

1. Fusion welding refers to the welding joint to the melting state under the action of high temperature during the welding process of Hu fiber. Since the welded workpieces are tightly adhered to each other, under the action of temperature field, gravity, etc., without pressure, the molten liquid of the two workpieces will be mixed. After the temperature is reduced, the molten part is condensed, and the two workpieces are firmly welded together to complete the welding method;

2. Pressure welding refers to the welding method that applies a certain pressure to the composite weldment in the heated or unheated state to make it produce plastic deformation or thaw pants vernalization, and through recrystallization and diffusion, the atoms on the two separated surfaces are connected to form metal bonds. There are many types of pressure welding, commonly used resistance welding, forging welding, contact welding, friction welding, gas pressure welding, cold pressure welding, and ** welding, all of which belong to the category of pressure welding;

3. Brazing refers to the welding method in which the brazing material and the weldment below the melting point of the weldment are heated to the melting temperature of the brazing material at the same time, and the liquid brazing material is used to fill the gap of the solid workpiece to make the metal connection. During brazing, the oxide film and oil stain on the contact surface of the base metal should be removed first, so as to facilitate the capillary tube to play a role after the brazing metal is melted, and increase the wettability and capillary fluidity of the brazing metal. According to the melting point of brazing metal, brazing is divided into hard brazing and soft brazing.