Tuesday, January 10, 2017

WELDING RODS -EFFECTS OF MOISTURE



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.

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