DESENSITISATION OF AUSTENITIC STAINLESS STEELS USING lASER SURFACE MELTING

AbstractSensitised types 304 and 316 stainless steels were laser surface melted using a Nd–YAG laser of 300 W power and 9 ms pulse width at a traverse speed of 2.5 mm s–l. Pulse energy, pulse repetition rate, and gas atmosphere were varied to give 24 different laser melting conditions. The melted specimens were tested according to ASTM A262 practice A (electrolytic etch test), and ASTM A262 practice E (immersion for 24 h in boiling Cu–CuS04 solution followed by a Ubend test) in order to assess the intergranular corrosion (IGC) resistance. The micro hardness values across the unmelted/melted region were measured and impact tests, with sensitised subsize specimens laser surface melted at the notch, were carried out. The results indicate that on lasersurface melting the sensitised microstructure disappeared and also that the specimens possessed higher IGC resistance. This is attributed to the creation of a desensitised microstructure of 200 μm thickness with dendritic–cellular structure and a heat affected z...