3.1.1. AISI 304L
It is well known ([1] and references there in) that on high-grade alloys such as the stainless steels and Ni-based alloys, material loss rates due to corrosion can be significantly accentuated when the passivity of the material is breached by a mechanical factor.
Macrographs in Fig. 3 show in-service failures of AISI 304L pipelines caused by chlorides in the presence of impinging particles and/or turbulent flow. Wall thinning mechanisms due to erosion–corrosion (Fig. 3a) and cavitation (Fig. 3b), respectively, can be observed. The 304L stainless steel piping exhibited wall thinning and leaking on one side of the joint, but not on the other. No signal of corrosion was observed on the external surface of the piping. This indicates that the failure was caused by internal erosion–corrosion [10]. Although complete information on operating conditions was not provided by the chemical plant which supplied the specimens, probable causes of the erosion include high velocity flow, the presence of particles in suspension and weld bead protrusion. The eroded pattern suggests that cavitation also aggravated the erosive process [11].