Taboos and measures for welding of steel structures

Phenomenon and harm

When welding, the same arc voltage is used regardless of the size of the base, filling, cover, and groove size. In this way, the required penetration depth and width may not be achieved, and defects such as undercuts, pores, and splashes may occur.

Prevention

Generally, for different situations, you should choose the corresponding long arc or short arc to get better welding quality and work efficiency. Obtaining higher efficiency and melting width can appropriately increase the arc voltage.

Inadvertent control of arc length during welding

Phenomenon and harm

When welding, the arc length is not adjusted properly according to the bevel form, the number of welding layers, the welding form, and the electrode type. Due to improper welding arc length, it is difficult to obtain high quality welds.

Prevention

In order to ensure the quality of the welding seam, short arc operation is generally used when welding, but the appropriate arc length can be selected according to different situations to obtain the optimal welding quality. For example, the first layer of the V-shaped groove butt and the corner joint should be applied. A shorter arc to ensure weld penetration and undercutting does not occur; the second layer can be slightly longer to fill the weld. When the gap is small, a short arc should be used. When the gap is large, the arc can be slightly longer and the welding speed will be faster. The overhead welding arc should be the shortest to prevent the iron from flowing underwater. In order to control the temperature of the molten pool during vertical welding and horizontal welding, a small current and short arc welding should also be used. In addition, no matter what kind of welding is taken during the movement, we must pay attention to keep the arc length basically the same, so as to ensure that the entire welding seam has the same width and depth.