Resistência a corrosão e ao pite do aço inoxidável austenítico AISI 316l com adições de nióbio
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Data
2021-10-08
Autores
Rolin, Vitor Silveira
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Universidade Estadual Paulista (Unesp)
Resumo
O aço inoxidável AISI 316L apresenta boas propriedades mecânicas e resistência à corrosão em uma vasta faixa de meios corrosivos, sendo amplamente utilizado em diversas aplicações, porém esses aços podem sofrer com corrosão por pites. A suscetibilidade ao pite atrai diversos estudos sobre adições de diferentes elementos nesses aços inoxidáveis, com intuito de melhorar sua resistência a esse mecanismo de corrosão. O presente trabalho tem como objetivo avaliar a influência da adição de nióbio, na proporção de 0,1%, 0,2% e 0,4% em peso na resistência à corrosão por pites do aço inoxidável austenítico AISI 316L na condição bruta de fundição (não tratada) e após tratamento de solubilização. As amostras foram submetidas a ensaios eletroquímicos, para obtenção do potencial de circuito aberto, potencial de pites, curvas de polarização potenciodinâmica, resistência à polarização e taxa de corrosão. A superfície das amostras foi analisada, sendo a distribuição e o tamanho dos pites de corrosão determinados por microscopia eletrônica de varredura (MEV). Para a caracterização mecânica foram realizados testes de desgaste microabrasivo e microdureza. Com a análise dos dados notou-se que a faixa de composição do nióbio adicionado aos aços inoxidáveis austeníticos AISI 316L brutos de fundição não promoveu mudanças significativas no comportamento corrosivo e nas propriedades mecânicas. Os materiais solubilizados mostraram uma diminuição na dureza e um aumento da resistência a corrosão por pites e ao desgaste microabrasivo. O Aço experimental solubilizado com a concentração de 0,1% de Nb demonstrou a maior resistência a corrosão por pites, enquanto a adição de 0,4% de Nb proporcionou a maior resistência ao desgaste microabrasivo.
AISI 316L stainless steel has good mechanical properties and corrosion resistance in a wide range of corrosive media, being widely used in various applications, but these steels can suffer from pitting corrosion. The susceptibility to pitting attracts several studies on additions of different elements to these stainless steels, with the aim of improving their resistance to this corrosion mechanism. The present work aims to evaluate the influence of the addition of niobium, in the proportion of 0.1%, 0.2% and 0.4% by weight on the pitting corrosion resistance of AISI 316L austenitic stainless steel in the raw as cast condition (untreated) and solution heat treatment. The samples were subjected to electrochemical tests to obtain the open circuit potential, pitting potential, potentiodynamic polarization curves, polarization resistance and corrosion rate. The surface of the samples was analyzed, and the distribution and size of the corrosion pits were determined by scanning electron microscopy (SEM). For the mechanical characterization microabrasive wear and microhardness tests were performed. With the analysis of the data, it was noticed that the composition range of niobium added to as cast AISI 316L austenitic stainless steels did not promote significant changes in corrosive behavior and mechanical properties. The solution heat treatedmaterials showed a decrease in hardness and an increase in resistance to pitting corrosion and microabrasive wear. The experimental steel solubilized with a concentration of 0.1% of Nb showed the greatest resistance to pitting corrosion, while the addition of 0.4% of Nb provided the greatest resistance to microabrasive wear
AISI 316L stainless steel has good mechanical properties and corrosion resistance in a wide range of corrosive media, being widely used in various applications, but these steels can suffer from pitting corrosion. The susceptibility to pitting attracts several studies on additions of different elements to these stainless steels, with the aim of improving their resistance to this corrosion mechanism. The present work aims to evaluate the influence of the addition of niobium, in the proportion of 0.1%, 0.2% and 0.4% by weight on the pitting corrosion resistance of AISI 316L austenitic stainless steel in the raw as cast condition (untreated) and solution heat treatment. The samples were subjected to electrochemical tests to obtain the open circuit potential, pitting potential, potentiodynamic polarization curves, polarization resistance and corrosion rate. The surface of the samples was analyzed, and the distribution and size of the corrosion pits were determined by scanning electron microscopy (SEM). For the mechanical characterization microabrasive wear and microhardness tests were performed. With the analysis of the data, it was noticed that the composition range of niobium added to as cast AISI 316L austenitic stainless steels did not promote significant changes in corrosive behavior and mechanical properties. The solution heat treatedmaterials showed a decrease in hardness and an increase in resistance to pitting corrosion and microabrasive wear. The experimental steel solubilized with a concentration of 0.1% of Nb showed the greatest resistance to pitting corrosion, while the addition of 0.4% of Nb provided the greatest resistance to microabrasive wear
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Palavras-chave
AISI 316L, Adição de nióbio, Potencial de corrosão, Dureza, Desgaste, Niobium addition, Corrosion potential, Hardness, Wear