High frequency welding (HFW) is a type of solid resistance heat energy. Welding uses the resistance heat generated by high-frequency current in the workpiece to heat the workpiece to the welding area or nearby surface to reach a plastic state, and then applies (or does not apply) forging force to achieve the bonding of metals. Therefore, it is solid phase resistance welding. High-frequency welding: When high-frequency current passes through a metal conductor, two peculiar effects will be produced: skin effect and proximity effect. High-frequency welding uses these two effects to weld steel pipes. These two effects are used to achieve the effect of metal on the conductor. High frequency welding base. High-frequency welding uses the skin effect to concentrate high-frequency energy on the surface of the current workpiece; the proximity effect is used to control the position and range of the flow path of high-frequency current. The current is so fast that it can heat, melt and squeeze the edges of adjacent sheets in a very short time. High-frequency welding methods can be divided into contact high-frequency welding and high-frequency induction welding based on the heat generated by high-frequency current on the workpiece. In contact power frequency welding, high-frequency current passes through the workpiece through mechanical contact with the workpiece at the same time.
Resistance welding (ERW) is a method that uses a combination of electrodes to apply pressure to the workpiece and the welding current to create thermal contact with the joint surface and surrounding area through a resistor. Resistance welding is a method that relies on the thermal effect of current flowing through a resistor to heat the area around the contact surface of the workpiece, producing a molten or plastic state, thereby forming a metal bond. There are four main resistance welding methods: spot welding, seam welding, projection welding, and butt welding. Resistance welding uses pressureless filler metal welding. No other components are filled in the weld to resist the skin effect and proximity effect of high-frequency current. The plate is instantly heated to the welding temperature, and the weld is squeezed by the squeeze roller to form a forged structure. High-quality steel pipe welds require online or offline heat treatment to refine the structure of the weld area. The toughness of high-quality ERW pipe welds can reach the same level as the base material, which cannot be achieved by the submerged arc welding process.
