(1) manual arc welding

Select the manual arc welding electrode model, first should be in accordance with the principle of the main body metal strength suitable to determine the electrode series, that is, the two strength should be equal. When steel of different strength is connected, the welding rod series suitable for low-strength steel can meet the requirements of strength and other aspects and be more economical. Then combine the steel brand, the importance of the structure, welding position and welding rod process performance to choose the specific model. For general structure, E4303 is usually used when the steel is Q235A•F. Can meet the requirements. These two kinds of electrode coating are titanium calcium type, easy to grasp welding, its slag fluidity, easy to remove slag, and stable arc, moderate melting depth, little splash, welding wave neat, suitable for full position welding, welding power for ac or dc forward, reverse. For heavy duty crane beam, crane truss or similar structure, E4315 or E4316 is usually used when the steel is Q235B, Q235C or Q235D; The above three kinds of electrode coating are low hydrogen type, suitable for all position welding, welding power should be dc reverse connection. Low hydrogen electrode can reduce the content of hydrogen in the weld to avoid cold cracks, so the toughness of weld metal is good, and its brittleness transition temperature is close to that of killed steel.

(2) automatic submerged arc welding

Automatic submerged arc welding (asaw) is superior to manual welding because of the heat concentration of arc, so it has large melting depth, uniform weld quality, fewer internal defects, good plasticity and impact toughness. The quality of semi-automatic submerged arc welding is between automatic submerged arc welding and manual welding. In addition, automatic or semi-automatic submerged arc welding welding speed, high production efficiency, low cost, good labor conditions. However, their application is also limited by their own conditions, because the welder must move along the guide of the weld, so there must be certain operating conditions. Therefore, automatic or semi-automatic submerged arc welding is especially suitable for mass assembly and production of welding seams of beams, columns and plates.

The welding wire and flux used in automatic or semi-automatic submerged arc welding shall be compatible with the strength of the main metal, that is, the strength of the deposited metal shall be equal to that of the main metal. The welding wire shall meet the requirements of the national standard "steel wire for welding" (GB/T1300), and the flux shall be in accordance with the requirements of "carbon steel submerged arc welding flux" (GB/T5293) and "low alloy steel submerged arc welding flux" (GB/T12470). In general, Q235 steel USES H08 (welding 08) or H08A (welding 08 high) welding wire with medium manganese type HJ401 flux; 16Mn steel adopts H08A or H08MnA (welding 08. Manganese high) wire with high manganese type HJ402 flux; 15MnV steel adopts H08MnA or H10Mn2 (welding 10 manganese 2) wire with HJ402 flux.