Knowledge points about solder flux

Flux is a granular welding material. It melts to form slag and gas during welding, and plays a protective and metallurgical role for the molten pool. When welding, it melts to form slag and gas, and acts as a protective and metallurgical treatment for the molten metal.

Composition

Flux is composed of ores such as marble, quartz, fluorite, and chemical substances such as titanium dioxide and cellulose. Flux is mainly used for submerged arc welding and electroslag welding. When used to weld various steel and non-ferrous metals, it must be used in reasonable cooperation with the corresponding welding wire in order to obtain satisfactory welds.

Classification

There are many ways to classify fluxes, including classification according to usage, manufacturing method, chemical composition, welding metallurgical properties, etc. There are also classifications according to the acidity and alkalinity of fluxes and the granularity of fluxes. 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 refers to the welding, the chemical composition of the deposited metal and the chemical composition of the wire does not produce significant changes in the flux, neutral flux for multi-pass welding, especially for welding thickness greater than 25mm base material. 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 the base material with serious oxidation, it will produce porosity and weld cracking.

2、Active flux

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

a. As it contains deoxidizer, Mn and Si in the molten metal will change with the change of 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, active flux has a strong anti-cavitation ability.

3、Alloy flux

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

4、Fusion flux

Melting flux is a variety of mineral raw materials mixed in accordance with the given ratio, heated to more than 1300 degrees, melted and stirred evenly after the furnace, and then cooled sharply in water to granulate. Then it is dried, crushed, sieved and packaged for use.

5、Sintered flux

According to the given ratio of ingredients for dry mixing, and 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.

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