Haz Formation And Analysis In Flux Assisted Gtaw

Abstract

The effect of Silicon dioxide (SiO2) powder on weld bead geometry, Heat affected zone (HAZ), and micro-hardness of SS304 grade Austenitic stainless steel weld was investigated. SiO2 improves the weld bead penetration with a simultaneous reduction in bead width. The improvement in penetration results from arc constriction and reversal of Marangoni flow. The results demonstrate SiO2 flux can increase the heat density by arc constriction and Marangoni convection. The temperature in HAZ reaches above the recrystallization temperature and consequently leads to the formation of new grains. The new grains formed in HAZ are of a very large size as compared to parent metal grains. Due to Larger grains, the micro-hardness in HAZ area was found to be less than weld metal and base metal zone. Increased heat density by using SiO2 flux increased the size of Heat Affected Zone. KeywordsActive TIG, Marangoni convection, arc constriction,