Effects of moisture in welding rods
Purpose of a welding flux is to keep nitrogen and
oxygen away from the molten metal and its secondary purpose is to drive out the
gasses generated and ensure good penetration of filler. any water vapour
contained in the flux coating can get dissolved in the weld in the form of
oxygen and Hydrogen lead to
Electrodes
for Shielded Metal Arc Welding (SMAW) or stick electrodes must be properly
stored in order to deposit quality welds. When stick electrodes absorb moisture
from the atmosphere, they must be dried in order to restore their ability to
deposit quality welds. Electrodes with too much moisture may lead to cracking
or porosity. Operational characteristics may be affected as well. Unexplained
weld cracking problems are experienced, or if the stick electrode arc
performance has deteriorated, it may be due to moisture in the electrode due to
poor storage methods or re-drying procedures.
When
the moisture present welding joint ma damaged due to following
1.
A greater amount of moisture in low hydrogen electrodes may cause porosity.
Detection of this condition requires x-ray inspection or destructive testing.
If the base metal or weld metal exceeds 550 MPa yield strength,
this moisture may contribute to under-bead or weld cracking.
2.
A relatively high amount of moisture in low hydrogen electrodes causes visible
external porosity in addition to internal porosity. It also may cause excessive
slag fluidity, a rough weld surface, difficult slag removal, and cracking.
3.
Severe moisture pickup can cause weld cracks in addition to under-bead
cracking, severe porosity, poor appearance and slag problems.
