What precautions should be taken in the operation of submerged arc welding

Submergedarc welding is a kind of welding method which takes the arc as the heat source and carries out arc combustion in the welding state. Dueto the deep penetration, high productivity and high degree of mechanization of arc welding, it is suitable for welds of medium and heavy plate structure. Submerged arc welding is one of the most widely used welding methods in welding production, but it can only be welded at the flat welding position.

The main welding parameters of submerged arc welding include: welding current, arc voltage, welding speed, wire diameter and wire extension length. The welding materials for submerged arc welding include welding wire and flux, which shall be selected according to the mechanical properties and chemical composition of the base metal, groove form, thickness, process conditions and structural dimensions.Welding wire and flux matching with steel strength can be selectedfor low alloy steel and low carbon steel, and other standard requirements shall be met at the same time. Carbon steel H08A and H08MnA welding wires, high manganese and high silicon flux, or H08MnA and H10Mn2 welding wires, matched with low fierce manganese free flux.

Low alloy high strength steel welding wire shall be used for low alloyhigh strength steel, and sintering flux can also be used when medium fierce medium silicon or low manganese medium smelting flux is selected.

For the welding of heat-resistant steel, the welding with composition similar to that of steel shall be selected. For the selection offlux, low-temperature heat-resistant steel and corrosion-resistantsteel can be selected as alkaline medium silicon or low silicon type flux, and high-alloy steel such as high alkalinity alloy steel or sintering bonding welding shall be selected to reduce the combustion of alloy elements and increase more alloy elements. In addition, the influence of various technical factors should also be considered.

The surface quality of welding wire, such as diameter deviation, surface hardness and curvature uniformity, will affect the stability and quality of welding process.Therefore, the welding wire shall be checked and the bending shall be eliminated before loading. Dry before use. The particle size of flux affects the air permeability and has a certain impact on the weldformation and internal quality. When the flux size remains unchanged,if the welding current is increased, the arc will be unstable and the weld surface and edge will be uneven. The larger the current is, the larger the flux particle size should be.

The welding speed has an effect on the width and depth of penetration.When other conditions remain unchanged, the welding speed decreases significantly with the increase of welding speed. The increase of arcbackward angle is conducive to the metal flow in the molten pool, sothe depth increases slightly.