Study of intergranular corrosion mechanism of fiber laser welded 3-mm-thick Hastelloy C-276 sheet

摘要

Specimens of laser welded Hastelloy C-276 were immersed in the ASTM G-28 test solution to study the intergranular corrosion mechanism of BM, HAZ and WZ. The variation in concentration of molybdenum at different sub-zones within the respective BM, HAZ and WZ was found to be responsible for the formation of a galvanic couple consisting of cathode and anode. The rate of corrosion was found to increase with the rise in concentration gradient of molybdenum between cathode and anode. Compositional analysis showed that (concentration gradient)(WZ) (concentration gradient)(BM) (concentration gradient)(HAZ), hence, the (corrosion rate)(WZ) (corrosion rate)(BM) (corrosion rate)(HAz).