Rejuvenation of Inside Surface of Intergranular Corrosion-Damaged Type 304 Stainless Steel Tube through Laser Surface Melting

Abstract

The present paper describes an experimental study aimed at rejuvenation of internal surface of intergranular corrosion-damaged type 304 stainless steel tube through laser surface melting. In the present investigation, effectiveness of laser surface melting technique was experimentally demonstrated on the inside surface of type 304 SS tubular specimens, which is often the requirement in most of the industrial applications as the process fluid flows through tubes/pipes. The results of the study demonstrated that laser surface melting treatment of inner surface of intergranular corrosion-damaged type 304 stainless steel not only erased previous IGC damage, but also restored its degree of sensitization close to that of untreated condition. Laser surface-melted specimens successfully passed ASTM A262 practice E test, thereby not displaying susceptibility to intergranular corrosion. However, subsequent exposure to susceptible temperature (973 K) brought about enhancement in IGC susceptibility of laser rejuvenated surface of 304 stainless steel tube. As a logical extension of the experimental corrosion study, a laser beam maneuvering system was designed to carry out in situ laser surface melting treatment on the internal surface of tubular components. To the authors’ best knowledge, this type of laser beam maneuvering system has been designed first time to carry out laser surface melting for repair of intergranular corrosion inside the tubular parts. The results are important for rejuvenation of IGC-damaged in-service austenitic stainless steel components.