Abstract:The connection between the austenite transformation and pitting corrosion of lean duplex stainless steel LDX 2101 was investigated at different annealing temperatures in the range 950-1200 • C. Optical microscopy, scanning electron microscopy, and electrochemical techniques were employed in the present work. Results indicated that micro-sized ferrite and austenite grains, formed with the increase of annealing temperature, influenced the pitting corrosion resistance of the studied stainless steel. As the austenite phase transformed into ferrite, the micro-sized ferrite grains were produced in austenite domains with temperature increase from 1000 • C to 1100 • C, especially at 1050 • C. In these conditions, the corrosion resistance of LDX 2101 was reduced by the micro-sized ferrite grains. A further increase of annealing temperature to 1150 • C produced the presence of micro-sized austenite grains in the ferritic phase, due to an incomplete transformation of austenite to ferrite. They represent new sites for severe pitting attacks and therefore the corrosion resistance of LDX 2101 was the weakest. The sample annealed at 1200 • C, with few micro-sized austenite grains in the ferritic matrix, exhibited excellent corrosion resistance. Moreover, a schematic was used to illustrate the pitting corrosion of the samples annealed at different temperatures.
This paper presents corrosion failure analysis of 13Cr stainless steel (SS) in gas pipeline ingas pipeline, which was used as thermocouple protecting material (TPM). A portion of TMP faileddue to pitting corrosion under unknown circumstances. Scanning electron microscopy (SEM) andX-ray diffraction (XRD) are employed to characterize the scales and/or corrosion products near thefailed portion. Based on visual and microscopic analyses, reviewing the background information andthe thermodynamic calculation, the following rapid pitting corrosion failure sequences wereidentified: Once the pitting appeared, in addition to the gas leakage and expansion, the temperaturedrop should lead a small amount of water in dry gas to condense on the surface of TPM. On one hand,the high salinity produced water will corrode the thermocouple. On the other hand, the high salinityproduced water will pass into the annular space of TPM through the pitting because of the pressuredrop, and the water will stay on inner surface for more time than that of external surface, whichaccelerated pitting of TPM. More and more pitting appeared, and the surface roughness increased.The film-forming property of condensation water will also increase. So, the TPM will be scrappedsoon.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.