What are the functional characteristics of flux? A flux manufacturer explains.

Solder flux manufacturer to believe Submerged arc welding is also a type of arc welding. A defining characteristic of arc welding is the melting of the metal. If the molten metal is not protected from contact with air during the melting process, the weld seam will contain excess oxides, reduced alloying elements, and increased nitrides. To minimize the detrimental effects of oxygen and nitrogen, it is essential to shield the molten metal from the atmosphere throughout the welding process. In submerged arc welding, the gases and slag produced by the flux serve to isolate the liquid metal from the surrounding air.

Solder flux manufacturer to believe The main functions of flux are as follows:

1) Enhance the arc’s conductivity to facilitate arc initiation and maintain arc stability;

2) Forms slag to protect the transitioning molten droplet and the newly formed weld pool, covers the weld surface to prevent excessive cooling of the weld;

3) It has a metallurgical effect on the molten pool by deoxidizing the metal and slag through the reactions between ferromanganese and ferrosilicon;

4) Gold-doping effect: incorporate elements such as Si, Mn, Cr, Ni, and Mo.

Solder flux manufacturer to believe Types of submerged arc welding fluxes based on application (Applied base metals) can be classified into carbon steel fluxes, low-alloy steel fluxes, and stainless steel fluxes. According to the manufacturing method, they can be divided into non-fused fluxes and fused fluxes. Non-fused fluxes are further categorized into sintered fluxes and bonded fluxes (ceramic fluxes). Fused fluxes are produced by uniformly mixing raw materials according to a specified formulation, melting the mixture in a furnace, followed by water-cooling granulation and sieving to obtain the finished product. Sintered fluxes and bonded fluxes both belong to the category of non-fused fluxes; they are made by blending raw materials in specific proportions, adding a binder to form a wet feedstock, and then drying, pulverizing, and sieving the material. The difference lies in the fact that sintered fluxes are dried (sintered) at 400–1000°C, whereas bonded fluxes are dried at 350–400°C. Fused fluxes are characterized by uniform composition, high particle strength, low moisture absorption, and good storage stability, making them widely used in domestic production. However, a drawback is that deoxidizers and ferroalloys cannot be added to fused fluxes, as substantial losses occur during the melting process. In contrast, since non-fused fluxes do not undergo high-temperature melting during production, the addition of deoxidizers and ferroalloys results in almost no loss, allowing a large amount of alloying elements to be transferred from the flux into the weld metal, thereby compensating for the burn-off of alloying elements in the welding wire. Consequently, non-fused fluxes are often employed for welding high-alloy steels or for surfacing applications. Moreover, sintered fluxes exhibit excellent slag-removal properties, which is why they are commonly used in narrow-gap submerged-arc welding of thick-section workpieces.

Comparison of fluxes for melting and sintering:

Technical Performance 。 Solder flux manufacturer to believe Fused flux results in uniform welds with excellent rust resistance; however, the weld bead is uneven, slag tends to adhere easily, and the drying temperature is low. Sintered flux beads, on the other hand, are matte, slag removal is easy, the drying temperature is high, and the rust resistance is less sensitive.

Weldability 。 Solder flux manufacturer to believe Fusion welding fluxes have relatively uniform chemical compositions; their toughness is strongly influenced by the composition of the welding wire and the basicity of the flux; deoxidation is poor, alloying is difficult, and the composition of the weld metal changes only slightly. Sintered fluxes, on the other hand, readily produce high-toughness welds with significant compositional variation, excellent deoxidation, and the ability to incorporate alloying elements.