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The Pitting Behavior of Austenitic and Duplex Stainless Steels Under SO2 Environments with Cl- And F

Cyclic polarization measurements were used to illustrate the corrosion and passive behavior of the stainless steels under the tail gas conditions. Electrochemical behavior of stainless steels in SO2-saturated solutions with various concentrations of Cl- and F- was also studied.

Product Number: 51317--9241-SG
ISBN: 9241 2017 CP
Author: Zhu Wang
Publication Date: 2017
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$20.00
$20.00

With increasing concerns of air pollution the gaseous emission of sulfur from industries in the forms of SOx has been closely monitored and regulated by many countries to meet the requirement of at least 99.8% sulfur recovery. Technological and industrial efforts have been put up in the past several decades and many clean-up processes have been developed in which sulfur containing tail gases are typically contacted with absorbing solvent(s) to remove SO2 from power plants and refineries. However corrosion especially pitting and stress corrosion cracking risks has been reported previously under the condition with both SO2 and Cl- / F- contamination in the solvent. In this paper pitting risk of the austenitic stainless steels and duplex stainless steels under wet SO2 environments with Cl- and F- under high temperature and high pressure was investigated. Corrosion behavior of stainless steels was tested under SO2-saturated solutions with various concentration of Cl- and F- at 60 oC and 125oC by 30 days immersion using autoclave as well as high temperature and high pressure electrochemical measurements. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were also used to characterize the surface of stainless steels after corrosion. The pits were observed on the surface after the simulation tests. Surface analysis also showed that there was a high content of S element in the surface layer in which the main corrosion products FeSO4 were found. Cyclic polarization measurements were used to illustrate the corrosion and passive behavior of the stainless steels under the tail gas conditions. The service boundaries of Cl- and F- content for different types of stainless steels were established.

Key words: SO2, Stainless steel, Pitting, F-, Polarization curve

With increasing concerns of air pollution the gaseous emission of sulfur from industries in the forms of SOx has been closely monitored and regulated by many countries to meet the requirement of at least 99.8% sulfur recovery. Technological and industrial efforts have been put up in the past several decades and many clean-up processes have been developed in which sulfur containing tail gases are typically contacted with absorbing solvent(s) to remove SO2 from power plants and refineries. However corrosion especially pitting and stress corrosion cracking risks has been reported previously under the condition with both SO2 and Cl- / F- contamination in the solvent. In this paper pitting risk of the austenitic stainless steels and duplex stainless steels under wet SO2 environments with Cl- and F- under high temperature and high pressure was investigated. Corrosion behavior of stainless steels was tested under SO2-saturated solutions with various concentration of Cl- and F- at 60 oC and 125oC by 30 days immersion using autoclave as well as high temperature and high pressure electrochemical measurements. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were also used to characterize the surface of stainless steels after corrosion. The pits were observed on the surface after the simulation tests. Surface analysis also showed that there was a high content of S element in the surface layer in which the main corrosion products FeSO4 were found. Cyclic polarization measurements were used to illustrate the corrosion and passive behavior of the stainless steels under the tail gas conditions. The service boundaries of Cl- and F- content for different types of stainless steels were established.

Key words: SO2, Stainless steel, Pitting, F-, Polarization curve

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The Sensitisation Behaviour of Alloy UNS N08825 After Heat Treatment as Used in Clad Materials

Product Number: 51317--9459-SG
ISBN: 9459 2017 CP
Author: Helena Alves
Publication Date: 2017
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The aim of this paper is to present recent standard test corrosion data obtained in laboratory for alloy UNS N08825 after post weld heat treatment in comparison with as delivered (soft annealed) material.