PLASMA ARC DIAGNOSTICS TO CLARIFY HYDROGEN REDUCTION MECHANISMS DUE TO FLUORIDE ADDITION IN WELDING ARC

摘要

Fluoride-type flux ingredients have been proposed to reduce the amount of diffusible hydrogen and, thus, the occurrence of hydrogen cracking in steel welds. Fluorides are generally assumed to react with hydrogen in the arc atmosphere to form HF. With extremely low solubility in molten iron, HF is eliminated from the liquid weld pool. However, it is uncertain if HF formation is the only cause for hydrogen reduction in the steel weld metal. To investigate the hydrogen behavior in the presence of fluorides in the arc, the hydrogen concentration in an argon gas tungsten arc was determined by emission spectroscopy. According to the experimental results, two other potential roles of fluorides in hydrogen reduction should be considered. They are the HF transport and arc dilution.