Defects that are easy to produce in the welding pipe are pores, hot cracks and undercuts.

1. Bubbles. Bubbles mostly occur in the center of the weld bead. Because hydrogen is hidden in the weld metal in the form of bubbles. Therefore, the measure to eliminate this defect is to remove the rust, oil, moisture and moisture of the welding wire and the weld. Secondly, the flux must be dried well to remove moisture. In addition, it is also very effective to increase the current, reduce the welding speed, and slow down the solidification speed of the molten metal.

2. Sulfur crack (crack caused by sulfur). When welding plates with a strong sulfur segregation zone (especially soft boiling steel), the sulfide in the sulfur segregation zone enters the weld metal to produce cracks. The reason is that the sulfur segregation zone contains low-melting iron sulfide and the presence of hydrogen in steel. Therefore, in order to prevent this, it is effective to use semi-killed steel or killed steel with less sulfur-containing segregation zone. Secondly, it is necessary to clean and dry the weld surface and flux.

3. Thermal cracks. In submerged arc welding, thermal cracks can occur in the weld bead, especially at the arc starting and extinguishing arc craters. In order to eliminate this kind of cracks, backing plates are usually installed at the arc starting and arc extinguishing positions, and at the end of the butt welding of the coil, the spiral welded pipe can be reversed and welded into the overlap welding. Hot cracks are most likely to occur when the weld stress is high, or when the si in the weld metal is high.

4. Involvement of welding slag. Involvement of welding slag is a part of welding slag remaining in the weld metal.

5. Poor weld penetration. The overlap of the inner and outer weld metal is not enough, and sometimes the weld is not penetrated. This situation is called insufficient penetration.

6. Undercut. Undercut is the appearance of a V-shaped groove at the edge of the weld along the center line of the weld. The undercut is produced when welding speed, current, voltage and other conditions are not appropriate. The welding speed is too high to cause undercut defects more easily than the current is not suitable.

Changsha Xiangjia Metal Materical Co., Ltd. the Steel Pipe Division of ADTO GROUP, is one of the leading manufacturers of steel products in China. We specializes in manufacturing all kinds of steel pipe in various grades and sizes. Years of production experience and manufacturing facilities who have a capacity of 200,000 tons per annual will ensure the good quality and competitive duration of our products.