Common arc welding methods:
1. Manual arc welding
Manual arc welding is one of the earliest and most widely used arc welding methods. It uses the coated electrode as the electrode and filler metal, and the electric arc burns between the end of the electrode and the surface of the workpiece to be welded. On the one hand, the coating can produce gas to protect the arc under the action of arc heat, 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 the slag is to produce physical and chemical reaction with the molten metal or add alloy elements to improve the weld metal energy. Manual arc welding equipment is simple, portable and flexible to operate. It can be used for welding short seams in maintenance and assembly, especially for welding 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. Submerged arc welding
Submerged arc welding (SAW) is a melting electrode welding method, in which the granular flux is used as the protective medium and the arc is buried under the flux layer. The welding process of submerged arc welding is composed of three links: 1. Apply sufficient granular flux evenly at the joints of weldments to be welded; 2. The conductive nozzle and the weldment are connected to two levels of welding power supply respectively to generate welding arc; 3 Automatically feed the welding wire and move the arc for welding.
The main characteristics of submerged arc welding are as follows:
① Unique arc performance
L High weld quality The slag has good air protection effect. The main component of the arc zone is CO2. The nitrogen content and oxygen content in the weld metal are greatly reduced. The welding parameters are automatically adjusted, the arc travel is mechanized, the molten pool exists for a long time, the metallurgical reaction is sufficient, and the wind resistance is strong, so the weld composition is stable, and the mechanical properties are good;
L Good working conditions, slag isolation arc light is conducive to welding operation; Mechanized walking, low labor intensity.
② The electric field strength of arc column is high, which has the following characteristics compared with MIG welding
L The equipment has good adjustment performance. Because of the high electric field strength and the high sensitivity of the automatic adjustment system, the stability of the welding process is improved;
L The lower limit of welding current is high.
③ High production efficiency Because the conductive length of the welding wire is shortened, the current and current density are significantly improved, so that the penetration ability of the arc and the deposition rate of the welding wire are greatly improved; Because of the heat insulation effect of flux and slag, the overall thermal efficiency is greatly increased, which greatly improves the welding speed.
