Problems that are easily overlooked in welding

1.The welding construction does not pay attention to the selection of the best voltage

Phenomenon: during welding, the same arc voltage is selected regardless of the groove size, so that the required weld width and depth can not be achieved, and defects such as undercut, splash, air hole and so on appear.

Measures: select long arc or short arc according to different conditions to obtain good welding quality.

For example, when backing welding, short arc operation can obtain good penetration. When filling welding or cover welding, appropriately increase the arc voltage to obtain higher efficiency and fusion width.

2.Welding does not control welding current

Phenomenon: the welds of medium and thick plates are not beveled, the strength index decreases, can not meet the requirements, cracks occur, the performance of welded joints can not be ensured, and pose hidden dangers to the structure.

Measures: control welding current, allow floating 10 ~ 15%, groove blunt edge size is not more than 6 mm, when the plate thickness is more than 6 mm, groove welding should be done.

3.Ignore the coordinated use of welding speed and welding current

Phenomenon: when welding, the welding speed and welding current are not controlled。

When backing welding, because the root size is narrow, the welding speed is fast, the gas and slag are not discharged in time, resulting in slag and other defects.

Measures: select appropriate welding speed in combination with welding current, weld thickness, welding position and groove size, and select larger welding speed on the premise of ensuring that welding slag is easy to discharge and does not burn through.

4. The arc length is not controlled during welding

Phenomenon: arc length is not adjusted according to groove form, welding form, welding layer number and electrode type, and it is difficult to obtain high-quality weld due to improper use of arc length.

Measures: during welding, short arc operation shall be adopted and appropriate arc length shall be selected according to different conditions. For example, short arc shall be used for the first layer of V-groove to ensure penetration, and the second layer can be slightly longer to fill the weld. Short arc shall be used for small weld gap, and the arc can be slightly longer for large gap. No matter which welding method is adopted, attention shall be paid to keeping the arc length unchanged to ensure that the weld width and penetration are consistent.

5. Pay no attention to control welding deformation during welding

Phenomenon: when welding, we don't pay attention to control the deformation from the welding sequence, groove form and operation method, which leads to large deformation after welding, difficult to correct, increasing cost, and failure to effectively control the deformation of high-precision workpieces, resulting in the installation size can't meet the requirements。

Proper welding sequence and welding deformation control measures shall be taken.