Precautions for welding Q355GNH weathering steel sheet

1、 Length of arc
The length of arc is related to the coating type and coating thickness of Q355GNH weathering steel sheet or electrode. However, short arc should be adopted as far as possible, especially low hydrogen Q355GNH weathering steel sheet or electrode. A long arc may cause porosity. The short arc can avoid harmful gases such as O2 and N2 in the atmosphere from invading the weld metal to form oxide and other harmful impurities, which will affect the welding quality of Q355GNH weathering steel sheet.

2、 Welding speed
The suitable welding speed is that Q355GNH weathering steel sheet or electrode diameter, coating type, welding current, heat capacity of the object to be welded, structure beginning and other conditions have corresponding changes, so no standard can be made.
Q355GNH weathering steel sheet maintains the appropriate welding speed, and the slag can cover the molten pool well, so that all kinds of impurities and gases in the pool can float out sufficiently, so as to avoid the formation of slag inclusion and porosity in the weld.
When Q355GNH weathering steel sheet is used for welding, if the moving speed of rod is too fast, the shrinkage stress will increase when the welding part is cooled, which will cause cracks in the weld.