Menu
Search
Filters
Close
Menu

In-Situ Determination Of The Degree Of Sensitization In Austenitic Stainless Steels

Picture for In-Situ Determination Of The Degree Of Sensitization In Austenitic Stainless Steels
Available for download

Austenitic stainless steels are widely used in refineries and petrochemical industries due to their good combination of properties such as workability, mechanical strength and corrosion resistance. However, one of the most important problems they show, and which can lead to failures in service, is the susceptibility to intergranular corrosion and intergranular stress corrosion cracking (IGSCC). When these materials are subjected to temperatures in the range from 500 ºC to 800 °C, the precipitation of chromium-rich carbides occurs preferentially at grain boundaries (GB).

Product Number: 51322-17805-SG
Author: Pablo M. Altamirano, Mariano A. Kappes, Martín A. Rodríguez
Publication Date: 2022
Industries: Corrosion Monitoring and Control , Coatings
$0.00
$20.00
$20.00

The present study reports an ongoing research to use a standardized electrochemical test for determining the degree of sensitization (DOS) of austenitic stainless steel components and equipment non-destructively in the field. DOS is understood as the higher rate of dissolution at the grain boundary region vs. the bulk grain, which is related to a chromium-depleted zone near the grain boundary. The double loop electrochemical potentiokinetic reactivation method (DL-EPR) was taken as a reference. Tests were performed in austenitic stainless steel type AISI 304 (UNS S30400). The main parameter calculated from the electrochemical test is Ir/Ia, the ratio of peak current during reactivation (backwards) and activation (forward) scans. It is assumed that DOS increases with Ir/Ia. However, cold work and inclusion content could affect the test results, hence potentially acting as false positives. These variables were included in the experimental matrix. Thermal aging time at 677 ºC, amount of cold work and inclusion content were varied to understand their effect on electrochemical response. The solution used for the tests contains sulfuric acid and thiocyanate ion, and common practice is to freshly prepare it just before the test. Measurements are usually performed under deaerated conditions. However, field deployment of the technique could be facilitated if naturally aerated solutions prepared in advance in a laboratory can be used. Hence, the influence of oxygen content in solution and the effect of solution aging on measured Ir/Ia was studied. A simple electrochemical cell was developed for field measurements, based on commercial falcon tubes and 3D-printed plastics parts.

The present study reports an ongoing research to use a standardized electrochemical test for determining the degree of sensitization (DOS) of austenitic stainless steel components and equipment non-destructively in the field. DOS is understood as the higher rate of dissolution at the grain boundary region vs. the bulk grain, which is related to a chromium-depleted zone near the grain boundary. The double loop electrochemical potentiokinetic reactivation method (DL-EPR) was taken as a reference. Tests were performed in austenitic stainless steel type AISI 304 (UNS S30400). The main parameter calculated from the electrochemical test is Ir/Ia, the ratio of peak current during reactivation (backwards) and activation (forward) scans. It is assumed that DOS increases with Ir/Ia. However, cold work and inclusion content could affect the test results, hence potentially acting as false positives. These variables were included in the experimental matrix. Thermal aging time at 677 ºC, amount of cold work and inclusion content were varied to understand their effect on electrochemical response. The solution used for the tests contains sulfuric acid and thiocyanate ion, and common practice is to freshly prepare it just before the test. Measurements are usually performed under deaerated conditions. However, field deployment of the technique could be facilitated if naturally aerated solutions prepared in advance in a laboratory can be used. Hence, the influence of oxygen content in solution and the effect of solution aging on measured Ir/Ia was studied. A simple electrochemical cell was developed for field measurements, based on commercial falcon tubes and 3D-printed plastics parts.

Product tags
Also Purchased
Picture for 97185 STABILIZATION AND SENSITIZATION
Available for download

97185 STABILIZATION AND SENSITIZATION OF STAINLES STEELS

Product Number: 51300-97185-SG
ISBN: 97185 1997 CP
Author: J. F. Grubb, J.R. Kearns
$20.00
Picture for Innovative And Sustainable Corrosion Protection Solutions For Foundation Structures Of Offshore Wind Turbines
Available for download

Innovative And Sustainable Corrosion Protection Solutions For Foundation Structures Of Offshore Wind Turbines

Product Number: 51322-17526-SG
Author: Frank Prenger, Kathrin Hesnaoui
Publication Date: 2022
$20.00

Metallic coatings as a protective coating are characterized by excellent corrosion protection behavior and show extreme resistance to mechanical loads as well. Pure metallic coatings or duplex systems are already being used successfully in other areas of offshore structures. For example, areas in the tidal water zone, such as boat landings, usually receive a duplex system consisting of thermal spayed coating and a fitting topcoat. Add-on parts are often protected exclusively by a metallic zinc coating. A thermal spray coating in the submerged zone thus represents a logical alternative to the organic topcoat system.
Picture for Inline Cathodic Protection Current Mapping - Applications
Available for download

Inline Cathodic Protection Current Mapping - Applications

Product Number: 51322-17629-SG
Author: Dennis Janda
Publication Date: 2022
$20.00

Inline cathodic protection current mapping is a unique method of assessing a pipeline’s cathodic protection. This is accomplished by measuring the actual current received by the pipeline continuously along the entire pipeline length. Unlike pipe to soil potentials, which can have a great deal of error in them due to forces often beyond our control, the CP mapping tool uses the physical properties of the pipe itself to measure the CP current. The pipe is a very stable part of the circuit, unlike the soil surrounding it.
Categories
Industry
Recently viewed
Popular tags
View all

Association for Materials Protection and Performance

© AMPP All Rights Reserved.
Membership Terms of Content Use
Contact Customer Support