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51318-10574-A computational approach to assess the sensitization propensity of stabilized stainless steels

A computational approach to assess the sensitization propensities of titanium and niobium stabilized stainless steels was investigated.

Product Number: 51318-10574-SG
Author: Raghavan Ayer / Yunjo Ro / Ihho Park / Jaehyeok Shim / Jingak Nam / Jaewoong Kim
Publication Date: 2018
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$20.00
$20.00

A computational approach based on thermodynamic and kinetic calculations (using commercial software) to assess the sensitization propensities of titanium and niobium stabilized stainless steels (UNS S32100 and UNS S34700, respectively) was investigated. The thermodynamic part consisted of calculating the carbon and nitrogen solubilities in austenite in the stabilized steels and comparing them to the corresponding solubilities in the unstabilized grades to determine the effectiveness of the stabilizing elements in decreasing carbon supersaturation at the service temperature. The kinetic part of the analysis consisted of determining the precipitation rate of carbides and carbo-nitrides during extended service. In addition, detailed microstructural studies were performed on selected steels exposed to service to validate some of the computational results. The study revealed the critical role of nitrogen in these steels with respect to sensitization and how its role differs between the two steels. Quantitative insights from the study provide guidance to fine-tune existing ASTM composition specifications and defining of optimum steel chemistry window for improved resistance to sensitization. With future calibration studies with field samples, the calculations may also be effectively used to predict the sensitization potential of components in service based on the alloy chemistry and heat treatments prior to service.

Key Words: Stress Corrosion Cracking, SCC, UNS S32100(1), UNS S34700, ThermocalcTM, MatcalcTM, precipitation, carbides, nitrogen, PEELS

A computational approach based on thermodynamic and kinetic calculations (using commercial software) to assess the sensitization propensities of titanium and niobium stabilized stainless steels (UNS S32100 and UNS S34700, respectively) was investigated. The thermodynamic part consisted of calculating the carbon and nitrogen solubilities in austenite in the stabilized steels and comparing them to the corresponding solubilities in the unstabilized grades to determine the effectiveness of the stabilizing elements in decreasing carbon supersaturation at the service temperature. The kinetic part of the analysis consisted of determining the precipitation rate of carbides and carbo-nitrides during extended service. In addition, detailed microstructural studies were performed on selected steels exposed to service to validate some of the computational results. The study revealed the critical role of nitrogen in these steels with respect to sensitization and how its role differs between the two steels. Quantitative insights from the study provide guidance to fine-tune existing ASTM composition specifications and defining of optimum steel chemistry window for improved resistance to sensitization. With future calibration studies with field samples, the calculations may also be effectively used to predict the sensitization potential of components in service based on the alloy chemistry and heat treatments prior to service.

Key Words: Stress Corrosion Cracking, SCC, UNS S32100(1), UNS S34700, ThermocalcTM, MatcalcTM, precipitation, carbides, nitrogen, PEELS

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51318-10568-Quality & Performance Review of Duplex Stainless Steel Products – An End Users Perspective

Product Number: 51318-10568-SG
Author: Janardhan Rao Saithala / Gurram Bhaskar Rao / Manoj Suryanarayana / Talal Nebhani / Pedro Rincon / Nasser Behlani / Mohammed Ghafri / Amjad Kharusi
Publication Date: 2018
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