Austenitic-ferritic stainless steel containing niobium

Rem: Revista Escola de Minas

André Itman Filho²  Wandercleiton Da Silva Cardoso¹  Leonardo Cabral Gontijo¹  Rosana Vilarim Da Silva¹  Luiz Carlos Casteletti¹ 

[1] ,Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo Materials and Metallurgical Departament Vitória ES ,Brazil

关键词: Austenitic-ferritic stainless steels;    sigma phase;    Laves phase;    charge transfer resistance;    Aço inoxidável austeno-ferrítico;    fase sigma;    fase de Laves;    resistência de transferência de carga;   

DOI  :  10.1590/S0370-44672013000400010

来源: SciELO

【 摘 要 】

The austenitic-ferritic stainless steels present a better combination of mechanical properties and stress corrosion resistance than the ferritic or austenitic ones. The microstructures of these steels depend on the chemical compositions and heat treatments. In these steels, solidification starts at about 1450ºC with the formation of ferrite, austenite at about 1300ºC and sigma phase in the range of 600 to 950ºC.The latter undertakes the corrosion resistance and the toughness of these steels. According to literature, niobium has a great influence in the transformation phase of austenitic-ferritic stainless steels. This study evaluated the effect of niobium in the microstructure, microhardness and charge transfer resistance of one austenitic-ferritic stainless steel. The samples were annealed at 1050ºC and aged at 850ºC to promote formation of the sigma phase. The corrosion testes were carried out in artificial saliva solution. The addition of 0.5% Nb in the steel led to the formation of the Laves phase.This phase, associated with the sigma phase, increases the hardness of the steel, although with a reduction in the values of the charge transfer resistance.

【 授权许可】

CC BY   
 All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License