How to choose flux cored wire?

Advantages and disadvantages of flux-cored wire.

Compared with solid welding wire, flux-cored welding wire has the following advantages:

①The welding speed is fast. In downward welding and horizontal welding, the flux cored wire speed is about 10% faster than that of solid core wire. Especially in vertical welding and overhead welding, high current welding can be used according to the role of powder, so it can be Increase welding speed by more than twice.

②All-position welding is possible. The solid core welding wire requires a welder with high welding skills during horizontal welding or upward welding, which will generate a large amount of spatter, so it is only suitable for thin plate welding, but the flux cored wire covers the welding part because it generates sufficient welding slag. , So it is suitable for welding in all positions.

③Small splash. Compared with solid welding wire, the flux cored wire has less spatter, and will not block the nozzle of the welding gun when it is used continuously. The workability is good. The flux arc of the flux cored wire is soft, the welding workability is good, and it is easy to operate.

However, the flux-cored wire also has some disadvantages compared to the solid wire: the deposition efficiency is low. After welding, the flux-cored wire produces a large amount of welding slag, so the deposition efficiency is about 88%, while the solid wire has no welding slag and melts. The application efficiency is about 95%; the amount of smoke is large, and the flux cored wire is relatively large during the welding process; the price is expensive, calculated in kilograms, although the price of the flux cored wire is more expensive, but from the perspective of improving productivity If calculated, it can save costs.

Flux-cored wire has the advantages of good welding process performance, good weld seam quality, strong adaptability to steel, etc., and has broad application prospects. Flux-cored wire can be used to weld various types of steel structures, including low carbon steel, low alloy high strength steel, low temperature steel, heat resistant steel, stainless steel and wear resistant surfacing. The protective gases used are CO2 and Ar + CO2. The former is used for ordinary structures, and the latter is used for important structures. Flux cored welding wire is suitable for automatic or semi-automatic welding, either DC or AC power supply. The selection principles of common flux cored wires are as follows:

(1) Flux cored welding wire for low carbon steel and high strength steel
This kind of welding wire has many varieties and large amounts. Most of them are titanium type slag systems. They have good welding processability and high welding productivity. They are mainly used in shipbuilding, bridge, construction, vehicle manufacturing and other departments. There are many varieties of flux cored wire for low carbon steel and low alloy high strength steel. From the weld strength level, flux cored wire of 490MPa level and 590MPa level has been widely used; from the performance point of view, some focus on process performance, some Focusing on the mechanical properties and crack resistance of the weld, some are suitable for all-position welding including downward vertical welding, and some are dedicated to fillet welds.

(2) Flux-cored welding wire for stainless steel
Stainless steel flux-cored welding wire has the characteristics of good process performance, stable mechanical performance and high production efficiency. It has been used in petrochemical, pressure vessel, shipbuilding and engineering machinery industries in recent years. At present, there are more than 20 varieties of stainless steel flux-cored wire. In addition to chromium-nickel-based stainless steel flux-cored wire, there are chromium-based stainless steel flux-cored wire. Welding wire diameter has several specifications such as 0.8, 1.2, 1.6, etc., which can meet the welding needs of stainless steel thin plate, medium plate and thick plate. Most of the protective gas used is CO2, and a mixed gas of Ar + (20-50)% CO2 can also be used.

(3) Flux-cored wire for wear-resistant surfacing
In order to increase the wear resistance or obtain some special properties on the metal surface, a certain amount of alloying elements need to be transitioned from the welding wire, but the welding wire is difficult to manufacture because of its large carbon content and alloying elements. With the advent of flux-cored wire, these alloy elements can be added to the flux core, and it is easy to manufacture. Therefore, the use of flux-cored wire for submerged arc surfacing wear-resistant surface is a common method and has been widely used. In addition, alloying elements are added to the sintered flux, and the surfacing layer of the corresponding composition can also be obtained after surfacing. It is matched with solid core or flux cored welding wire to meet different surfacing requirements.