Metallurgical flux is a material that has been used in metallurgical processes for thousands of years. It is a white, powdery material made of lime, borax or soda, with or without other additives. The purpose of this material is to draw impurities from the metals being melted and to help the metals alloy together.
Metallurgical flux works in a simple way. The flux is added to the metal being melted and will start to melt along with it, right at the surface. As the metal melts, liquid droplets form on the surface of the metal and the flux begins to dissolve in the liquid. As the flux is dissolved, it starts to break down and pull the impurities from the metal, pushing them away and creating bubbles that rise up to the surface. The impurities are then skimmed off the surface of the liquid metal before it is poured.
The flux also helps to bind the melted metals together during the process of alloying. When two or more metals are heated to their melting point and left in contact with each other, there is a danger that the metals will not incorporate properly, leading to metal flaws, weak spots and uneven melting. Metallurgical flux helps the metal to mix, bind and alloy together properly.
Metallurgical flux has been used in metal working since ancient times, with records showing that it was commonly used in the Roman Empire and medieval China. The flux would have been created by taking a natural stone, such as limestone, and crushing it into a powder. Additional materials, such as borax, salt or clay, were sometimes added to enhance the effect of the flux.
Today, metallurgical flux is mostly composed of either flux-coated electrodes or flux powder. Flux-coated electrodes are rods of metal, such as copper or stainless steel, which are coated with a layer of flux material. When melted, the flux will both dissolve and bind the metals together, helping to create a strong and uniform alloy. Flux powder is a combination of flux materials, pre-measured and blended together for easy use. This can be mixed with metals or used to coat electrodes before melting.
Metallurgical flux plays a vital role in many metal working processes. It is used in soldering and brazing, in smelting processes, and in welding to help union two or more metals together. Without the flux, these processes would be much more difficult, laborious and inefficient. In many cases it is not possible to achieve a strong and even finished product without the use of flux.
