Basic knowledge of flux cored wire arc welding

Basic knowledge of flux cored wire arc welding What is flux-cored arc welding? Flux-cored arc welding (FCAW) is a welding method that uses the arc between flux-cored wire and workpiece to heat. Under the action of arc heat, welding wire metal and workpiece are fused to form a molten pool, and after the arc moves forward, crystallization at the end of the molten pool forms a weld. What is flux-cored wire? What are the characteristics of the cartridge? Flux-cored wire is a kind of wire made by rolling thin steel strip into steel tube or special-shaped steel tube, filling the tube with certain components of powder, and drawing. The composition of the drug core is similar to that of the electrode coating, which is mainly composed of arc stabilizer, slagging agent, gassing agent, alloying agent, deoxidizing agent, etc. What is the function of the flux in the flux-cored wire? The function of the flux is similar to that of the electrode coating, and there are mainly the following kinds. ① Some components in the protective flux decompose and some melt! The decomposing flux gives off gas, which provides some or most of the protection. The molten flux forms a molten slag, which covers the surface of the droplet and the molten pool and is protected by liquid metal. ② Arc stabilizer in arc stabilizer cartridge can stabilize arc and reduce spatter rate. ③ Alloying some drug cores have alloying elements, which can make weld alloying. ④ The alloy elements of the deoxidation slag can react with the liquid metal. Improve the composition of weld metal, improve its mechanical properties. In addition, the covered slag can also reduce the cooling rate of the molten pool, prolong the existence time of the molten pool, which is beneficial to reduce the content of harmful gas in the weld and prevent porosity. What are the flux-cored arc welding types? Flux-cored arc welding is divided into two types: flux-cored gas shielded welding (FCAW-G) and self-shielded welding (FCAW-S), depending on whether external shielded gas is used. Gas shielded welding of flux-cored wire usually uses carbon dioxide or carbon dioxide plus argon as shielding gas, and the flux in the wire contains little gassing agent. This method is similar to the general gas shielded welding. There is no additional protective gas in self-protection welding. There are a large number of gassing agents in the flux, and the gas and slag decomposed by the gassing agent are used for protection. What are the advantages of flux-cored arc welding? Flux-cored arc welding has the following advantages. (1) High welding productivity high melting efficiency (up to 85%~90%), fast melting speed; For flat welding, the melting speed is 1.5 times that of manual arc welding, and for other welding positions, it is 3-5 times that of manual arc welding. ② Small splash, good weld forming drug core added arc stabilizer, so stable arc, small splash, good weld forming. Because the molten pool is covered with molten slag, the surface shape of weld is significantly better than that of carbon dioxide welding. (3) High welding quality Because of the slag gas combined protection, it can more effectively prevent harmful gas from entering the welding zone. In addition, the molten pool exists for a long time, which is conducive to gas precipitation, so the weld has low hydrogen content and good porosity resistance. (4) Strong adaptability Only need to adjust the composition of solder wire cored, can meet the requirements of different steel weld composition. What are the disadvantages of flux-cored arc welding? The shortcomings of flux-cored arc welding are as follows. Compared with gas shielded welding, the welding wire cost is higher and the manufacturing process is complicated. ② Wire feeding is difficult, it is necessary to use a wire feeding machine whose clamping pressure can be adjusted accurately. ③ The cartridge is easy to absorb moisture, so it is necessary to keep the welding wire strictly. ④ Slag removal is needed after welding. ⑤ More smoke and harmful gases are generated in the welding process, so ventilation should be strengthened. What protective gas is usually used in flux-cored arc welding? What are the characteristics of each? Flux cored wire arc welding usually uses pure carbon dioxide gas or carbon dioxide and argon gas as a shielding gas. The gas type needs to be selected according to the flux-cored wire used. Argon is easily ionized, so it is easy to achieve ejection transition in argon arc. When the argon content of gas mixture is not less than 75%, flux-cored arc welding can achieve stable jet transition. With the decrease of argon content, the penetration depth increases, but the arc stability decreases and the spatter rate increases. Therefore, the optimal gas mixture is 75%Ar+25%CO2. In addition, Ar+2%O2 can also be used for gas mixture. When pure CO2 gas is selected, due to the decomposition of CO2 gas under the action of arc heat, a large number of oxygen atoms are generated, and the oxygen atoms will oxidize manganese, silicon and other elements in the molten pool, leading to the burning of alloying elements. Therefore, welding wire with high manganese and silicon content is needed.铜焊丝,Copper Welding Rods,铝焊丝,aluminium welding wire,镍焊条,Nickel electrode,药皮焊条,Flux Coated Brazing Welding Rods