Flux is a granular welding material. During welding it melts to form slag and gas and plays a protective and metallurgical role for the molten pool. When welding, it is able to melt to form slag and gas, playing a protective and metallurgical treatment of the molten metal.

Ingredients

The flux consists of ores such as marble, quartz and fluorite and chemicals such as titanium dioxide and cellulose. Flux is mainly used in submerged arc welding and electroslag welding. When used to weld various steels and non-ferrous metals, it must be used in reasonable conjunction with the corresponding welding wire in order to obtain a satisfactory weld.

Classification

There are many ways to classify fluxes, according to the use, manufacturing methods, chemical composition, welding metallurgical properties, etc., but also according to the acidity and alkalinity of the flux, the granularity of the flux classification. No matter which classification method, are only from a certain aspect to reflect the characteristics of the flux, can not contain all the characteristics of the flux.

Commonly used classification methods are:

1. Neutral flux

Neutral flux is a flux that does not produce significant changes in the chemical composition of the deposited metal and the chemical composition of the wire after welding, neutral flux is used for multi-pass welding, especially for welding base materials with a thickness greater than 25mm. Neutral flux has the following characteristics.

a. The flux basically does not contain SiO2, MnO, FeO and other oxides.

b. The flux has no oxidation effect on the weld metal.

c. When welding base materials with severe oxidation, porosity and weld channel cracks will occur.

2. Activated flux

Active flux refers to the addition of a small amount of Mn, Si deoxidizer flux. It can improve the ability to resist porosity and cracking. Active flux has the following characteristics.

a. Due to the presence of deoxidising agents, the Mn and Si in the molten metal will change with the change in arc voltage. As Mn, Si increase will improve the strength of the molten metal, reduce the impact toughness. Therefore, when multi-channel welding, the arc voltage should be strictly controlled.

b. The active flux has a strong anti-cavitation ability.

3. Alloy fluxes

Alloy fluxes add more alloying components for the transition of alloying elements, most alloy fluxes are sintered fluxes. Alloy flux is mainly used for welding of low alloy steel and wear-resistant overlays.

4. Melting flux

Melting flux is a mixture of raw materials of various minerals in a given proportion, heated to over 1300 degrees, melted and stirred evenly and then discharged from the furnace, and then cooled sharply in water to make granulation. It is then dried, crushed, sieved and packaged for use. The domestic molten flux grade uses "HJ", the first number after it indicates the content of MnO, the second number indicates the content of SiO2 and CaF2, and the third number indicates different grades of the same type of flux.

5. Sintered solder

According to the given proportion of ingredients for dry mixing, then add binder (water glass) for wet mixing, and then granulation, and then sent to the drying oven curing, drying, and finally sintered by about 500 degrees. The domestic sintered flux grade is indicated by "SJ", followed by the first digit indicating the slag system, and the second and third digits indicating different grades of the same slag system.