%K Corrosive effects; Grain boundaries; Microstructure; Morphology; Pitting; Residual stresses; Scanning electron microscopy; Sodium chloride; Steel corrosion; Stress corrosion cracking, Behavior analysis; Chloride drip test; Comparatives studies; Corrosion behaviour; Drip tests; Microstructural analysis; Perlite thermal insulation; Ss304; Test parameters; U-bend, Thermal insulation
%X Austenitic stainless steel (ASS) structures are susceptible to stress corrosion cracking (SCC) in chloride-containing environments either in an exposed state or beneath a thermal insulation. This study aims to assess the impact of perlite thermal insulation on the SCC susceptibility of both SS304 as-received (AR) and sensitized (SEN) materials under applied test parameters, including chloride concentration and temperature. The experimental test was carried out for 28 days at 90 °C on SS304 AR and SEN ASS through the drip test as per ASTM C692. The U-bend test samples were prepared based on ASTM G30, positioned on a pipe spool, and shielded with perlite thermal insulation. The insulated U-bend samples were dripped with 3.5 wt of sodium chloride (NaCl) aqueous solution to simulate the actual corrosive environment. At the end of the test upon removal of insulation, wet blisters were observed on the U-bend samples where the rust staining occurred. Microstructure analysis revealed both sample types exhibited pitting and staining but with distinct characteristics. No cracking was observed after 28 days. The SEN samples were more susceptible to the applied test parameters than the AR sample. Both samples revealed voids in grain structure, but SEN revealed a deep void at the vicinity of grain boundary upon examination under a field emission scanning electron microscope (FESEM). In the AR sample, pits exhibited a wide and shallow morphology, whereas in the SEN sample, pits appeared narrow and deep because of heat sensitization-induced changes in microstructure, and non-uniform passive film formation. © 2024 Elsevier Ltd
%O cited By 0
%L scholars19707
%J Engineering Failure Analysis
%D 2024
%R 10.1016/j.engfailanal.2024.108054
%T Comparative study of corrosion behaviour and microstructural analysis of as-received and sensitized SS304 U-bend samples under perlite thermal insulation using chloride drip test
%V 159
%A S. Nuthalapati
%A K.E. Kee
%A M.C. Ismail
%A K. Jumbri
%A S.R. Pedapati