Evaluation of laser surface melting to mitigate chloride stress corrosion cracking in an austenitic stainless steel

Abstract

This thesis evaluates the ability of laser surface melting to mitigate chloride stress corrosion cracking (See) of type 304 stainless steel. The effects of laser surface melting on microstructure, mechanical state, and corrosion behavior were examined. The major effect of laser surface melting of 304 stainless steel was found to be the introduction of tensile residual stresses on the order of the yield strength in the surface of the laser-melted regions. Exposure of laser-melted coupons to boiling magnesium chloride at 154°C revealed that the residual stresses were sufficient to cause failure by see processes in the absence of an external load. It was concluded that unless measures could be found to eliminate or reverse the residual stresses introduced by the laser melting process, the technique is not viable for mitigating chloride see in these alloys.