Low Temperature Sensitization on the Orthogonal Surfaces of Prior Deformed AISI 304LN and Aged at 673 K to 873 K (400 A°C to 600 A°C)

This study investigates the sensitization behavior of AISI 304LN deformed previously by cold rolling (CR) to 5 pct to 25 pct reduction in thickness and aged at 673 K to 873 K (400 A degrees C to 600 A degrees C). The emphasis was on revealing the degree of sensitization (DOS) resulting from low-temperature sensitization (LTS) on the orthogonal surfaces and correlation thereof with the changes in various metallurgical properties caused by cold rolling. It was found that the DOS differs among the orthogonal surfaces such as the rolling surface (RS), transverse surface (TS), and cross transverse surface (CTS). RS showed lower DOS compared with CTS and TS. The differences in the DOS were attributed to the combined effect of deformation-induced martensite (DIM), grain size, and slip band formation. A deformation of 5 pct was critical to the susceptibility of AISI 304LN to intergranular (IGC) and transgranular corrosion (TGC). The sensitization kinetics was slow or saturated leading to desensitization beyond 5pct deformations at 773 K (500 A degrees C) and 873 K (600 A degrees C). It was, however, uniformly accelerated over 5 to 25 pct deformation when aged at 673 K (400 A degrees C).