Electric resistance welding (ERW) was invented at the end of the 19th century. It is a method of welding by applying pressure to the assembled weldment through electrodes and using the resistance heat generated by the contact surface of the joint and the adjacent area of the electric current. Electric resistance welding has high production efficiency, good quality, and low cost. It is easy to realize mechanization and automation. It is also suitable for a wide range of welding materials. It can not only weld steel materials, but also weld aluminum, copper and other non-ferrous metals and their alloys. With the development of aerospace, electronics, automobiles, household appliances and other industrial sectors, electric resistance welding has received more and more attention. However, due to the complexity of the resistance welding process, there are many parameters that affect its welding quality. In order to ensure the quality of the welded joints, further research and optimization of the relationship between welding parameters and welding quality are still needed.
1.1 Application of electric resistance welding in automobile manufacturing
In industrial applications, resistance spot welding is mainly used to weld thin metal plates and metal wire meshes, and thick plate welding is difficult to achieve spot welding because the heat flow is easier to conduct to the surrounding. At present, electric resistance spot welding is mainly used for thin plate welding in automobile manufacturing, and industrial robots have been applied to assembly production lines in production to realize the automation of the welding process.
As an important process in traditional automobile manufacturing, electric resistance welding has been widely used in the welding process of underbody, roof, door, side wall and body assembly. The body-in-white structure of a car is its main load-bearing structure.The quality of the whole vehicle plays a decisive role. Electric resistance spot welding is widely used in the manufacturing and welding of the body-in-white. Statistics show that there are about 4000 to 6000 resistance spot welding points on the body of each car. The quality of solder joints is very important in automobile manufacturing, because the quality of solder joints directly determines the quality of the white body, which in turn affects the manufacturing quality of the entire vehicle.
In addition, electric resistance welding has also been widely used in the production of auto parts. Electric resistance seam welding is used in automobile fuel tanks, resistance spot welding, seam welding and projection welding are used in the manufacture of automobile shock absorbers, and in the production of automobile rims. To the continuous flash butt welding.
1.2 Application of resistance welding in petrochemical industry
In the petrochemical industry, the transportation of chemical materials in the production of petroleum, natural gas, and petrochemical enterprises is accomplished through pipelines. Because the chemical industry has very strict requirements on pipeline steel pipes, seamless steel pipes are mainly used in early pipelines. With the development of steel smelting and welded pipe technology, the quality of electric resistance welded straight seam steel pipes (ERW welded pipe) has also been continuously improved. Due to the competitive advantage in manufacturing costs, it has been improved and applied in many predicted petrochemical industries to replace high-cost seamless steel pipes.
In recent years, although the application of high frequency electric resistance welded pipes in my country's oil and natural gas pipelines has gradually increased, there are still some problems in the welding defects and quality inspection of high frequency electric resistance welded pipes, and further research is still needed, which is also to a large extent The above has affected the promotion and application of resistance welded pipe, which is also an urgent problem to be solved in the domestic welded pipe industry.
1.3 Application of electric resistance welding in other industries
Electric resistance welding also has a wide range of applications in the home appliance manufacturing industry. Because it is suitable for welding thin steel plates and has high joint quality, it has been widely used in the manufacture of refrigerators, air conditioners, and washing machines.
In addition, electric resistance welding can also be used to assemble nickel-cadmium or nickel-metal hydride battery packs. When assembling the battery, the nickel strip can be welded to the battery electrode by resistance spot welding. Because the spot welding time is very short, it can prevent the battery from overheating during the connection process, while the traditional soldering is prone to overheating. In the medical field, dentists also use small resistance welding to repair metal molars.In addition, resistance welding is widely used in the manufacture of aircraft fuselages and the manufacture of food packaging cans in the food industry.
Tips: ASTM A53 Grade B is the grade in ERW high frequency welded pipe, divided into A and B grades. ASTM A53 Gr.B is more popular than other grades. These pipes can be bare pipes without any coating, or it may be Hot-Dipped or Zinc-Coated and manufactured by Welding or by a Seamless manufacturing process. In Oil and Gas, A53 grade pipes are used in the structural and non-critical applications.