Coordination of submerged arc welding wire and flux

The welding process performance and chemical metallurgical performance of the flux is one of the main factors that determine the chemical composition and performance of the weld metal. Using the same welding wire and the same welding parameters, but the matching flux is different, the performance of the resulting weld will be great The difference. One kind of welding wire can be reasonably combined with a variety of fluxes, whether it is on low-carbon steel or low-alloy steel.

General requirements for flux 

a. The flux should have good metallurgical properties. When welding, it should be equipped with appropriate welding wire and reasonable welding technology. The weld metal should be able to obtain suitable chemical composition and good mechanical properties (compatible with the base metal). Strength and high plasticity, toughness) and strong resistance to cold cracks and hot cracks. 

b. The flux should have good manufacturability, stable arc combustion, and the slag should have a suitable melting point, viscosity and surface tension. The weld bead and the weld bead and between the weld bead and the base metal are fully fused, the transition is smooth, there is no obvious undercut, the slag removal is easy, the weld surface is well formed, and the harmful gas generated during the welding process is small. 

c. The flux must have a certain particle size and a certain particle strength to facilitate multiple recycling. The particle size of flux is divided into two types: the particle size of ordinary particle size flux is 2.5～0.45mm (8～40 mesh), which is used for ordinary submerged arc welding and electroslag welding; the particle size of fine particle size flux is 1.25～0.28mm ( 14～60 mesh), suitable for semi-automatic or fine wire submerged arc welding. Among them, the fine particles smaller than the specified particle size of 60 or less are not more than 5%, and the coarse particles above the specified particle size of 14 mesh are not more than 2%. 

d. The flux should have low water content and good moisture resistance. The mass fraction of the factory flux should not be greater than 0.10%. The flux should be placed for 24h under the environmental conditions of 25℃ and 70% relative humidity, and it will absorb moisture. The rate should not be greater than 0.15%. 

e. The content of mechanical inclusions (carbon particles, raw materials, ferroalloy beads and other impurities) in the flux should not be greater than 0.30% of the mass fraction of the flux; 

f. The flux should have a low content of S and P, generally S≤0.06 %,P≤0.08%.