Intergranular Corrosion of UNS S31803 Heat Treated at 800 ℃ Varying Range Times

作     者：Najara Barros Dias Bianca Barros dos Santos Pedro Rupf Pereira Vlana 

作者机构：Chemical Engineering Departament Pitagoras College Linhares-ES 29901398 Brazil PROPEMM Programa de Pos-Graduacao em Engenharia Metalurgica e Materiais Federal Institute of Espirito Santo Vitoria-ES 29040780 Brazil 

出 版 物：《Journal of Chemistry and Chemical Engineering》 (化学与化工（英文版）)

年 卷 期：2015年第9卷第8期

页      面：503-508页

学科分类：080503[工学-材料加工工程] 08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

主　　题：Intergranular corrosion a phase DL-EPR pitting corrosion 

摘      要：The aim of this work is evaluate the intergranular corrosion on UNS S31803 steel, with heat treatments at 800 ℃, varying treatment times of 30 mins, 360 mins and 1,440 mins. The results confirm the formation of o phases and secondary austenite （γ2）. For the analysis of the influence of o and γ2 phases, metallographic analysis were conducted through optical microscopy, potentiokinetic reactivation electrochemical techniques and potentiodynamic polarization in NaCI 3.5% solution. Microstructural analysis has shown a formation of γ2 and o phase in heat treatment, due to diffusion of chromium and molybdenum from δ phase to y phase, precipitating on δ/γ and δ/δ interfaces. The DL-EPR （Double loop electrochemical potentiokinetic reactivation） results have shown an increase of the DOS （degree of sensitization） for long periods of time on heat treatment. The results of potentiodynamic polarization showed a reduction of the corrosion and pitting potentials, followed by an increase of the current density when the UNS S31830 steel is heat treated during long periods of time.