The essence of flux work during welding
Ferrous and non-ferrous metals in general are one of the most important types of structural materials, they play an important role in almost all types of human activities. Often there is a need for a reliable connection of metal structural elements.
From numerous methods of its implementation, welding of metals gives a high-strength and reliable connection. There are many kinds and technologies. Arc welding and gas welding are very common among them, they are actively and widely used in construction, industrial production, work in the energy sector, etc.
Among the requirements for seams, it is important to protect the welding zone. The oxides formed during welding have a melting point higher than that of the metal, this significantly impairs the connection. The task of fluxes is to protect against oxides that degrade the properties of the seam joint and to form easily removable slags. This is achieved through the inclusion of chemicals in the formulations.
Therefore, being a rather complex composite material, the flux for welding protects the metal melt and the zone of action( arc or burner) from oxygen and nitrogen, making combustion more stable and powerful. It promotes the reduction of oxides, liquefies and lowers the temperatures of slags and their compounds, thereby creating the conditions for their ascent to the surface of the melt for subsequent removal.
In what form can be found a flux for welding?
Modern fluxes can be made in the form of a separate material or as an integral structure. Thus, the outer layer of the coating on the material of the welding rod forms the integral design of the welding electrode, which has become the standard and has become widespread.
Like an electrode, a welding wire with a flux is widely used in mechanized welding operations with and without protective gases. The wire is wound in bobbins, and the flux in it is located in the form of a core. It also performs the task of protecting the weld pool.
Another type of bobbin material for automatic and semi-automatic welding machines is a powder welding wire. Structurally, it consists of an electrode tube with a mixture of powder metal and flux inside. It is also a flux welding wire.
Flux also reduces the release of harmful dust and gases, increases the depth and power of the melt, thereby ensuring greater uniformity and quality of the seam. In addition, in fluxes there are special additives for obtaining a predetermined chemical purity, increasing the strength characteristics of joints, their alloying.
Application of fluxes - defined with types of work
Depending on the type of metals, different types of fluxes are used on the type of welding. Thus, the first group of fluxes is used for welding carbon and alloy steel. For steels of high-alloy fluxes of the second group are used. Accordingly, for non-ferrous metals and alloys, welding is carried out using a third, large group of fluxes.
For example, a specialized flux for welding aluminum in its composition can contain salts of sodium, potassium, lithium, barium. In addition, there is fluorspar in this flux. Silicon, manganese, magnesium, zinc and iron are also used in welding aluminum.
Of course, depending on the types of fluxes, electrodes and wires, the composition and the ratio of components change. But it should be noted and the presence of universal fluxes, some of them can be used to work with metals from other groups.
As already mentioned, numerous welding tasks are also solved using gas welding. The factor of its use is the smoothness and gradual heating of the connected metal parts. Especially useful is the use of gas welding in works requiring such gradualness.
For example, when working with cast irons and special and tool steels. As in the case of arc welding, fluxes for gas welding protect the melt from the formation of refractory oxides, promote the formation of slags with low melting points. Such slags form a thin protective surface film on the seam joint.
Therefore, in the case of gas welding, the following requirements are imposed on the fluxes: low density( should float on the surface of the melt), low melting( less melting temperatures of the metal), adhesion and fluidity in the melt, ease of reaction with oxide films and metal oxides( to form low-temperature slags) and safety for people and materials.
Since metals, as well as alloys, many, flux materials for gas welding alone, more than a hundred are known. Here, for example, silicon and boric acids, borax, and their multicomponent combinations are used.