Investigation of the sensitization and intergranular corrosion of tube-to-tubesheet welds of hyper duplex stainless steel using an electrochemical reactivation method

Kim, Hye Jin; Jeon, Soon-Hyeok; Kim, Soontae; Lee, Insung; Park, Yong Soo; Kim, Kwang-Tae; Kim, Young-Sub

doi:10.1016/j.corsci.2014.06.005

Cited by 73 publications

(25 citation statements)

References 42 publications

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“…Note that the reactivation current density peak was clearly absent from the solution-treated sample cooled rapidly (in water), indicating that in this condition the material was not sensitized, since the degree of Cr depletion was very limited, presenting a reduced Qr to Qa ratio (0.5 ± 0.1) [28] . This result suggests the presence of residual values inherent to the software and unavoidable deviations due to noises during measurements.…”

Section: Resultsmentioning

confidence: 99%

Effect of Cooling Rate on the Corrosion Behavior of As-Cast SAF 2205 Duplex Stainless Steel after Solution Annealing Treatment

Cronemberger

Nakamatsu

Mariano

et al. 2016

MSF

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The formation of intermetallic phases alters the properties of duplex stainless steel and is therefore a crucial factor in its performance. For example, the formation of sigma phase in duplex steel increases its brittleness and decreases its corrosion resistance because this phase consumes chromium and molybdenum in solid solution, thus leading to the depletion of these elements in the matrix. This study investigated the corrosion resistance of as-cast SAF 2205 duplex stainless steel after solution annealing treatment at 1100 °C for 240 minutes, under varying cooling rates. The objective was to evaluate the correlation between cooling condition, microstructural changes and corrosion resistance based on cyclic potentiodynamic polarization tests and double loop electrochemical potentiokinetic reactivation (DL-EPR) measurements. The results revealed a significant reduction in the corrosion resistance of a slowly cooled sample, which presented an increase in the degree of Cr (Qr / Qa) depletion resulting from the formation of sigma phase.

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Section: Resultsmentioning

confidence: 99%

Effect of Cooling Rate on the Corrosion Behavior of As-Cast SAF 2205 Duplex Stainless Steel after Solution Annealing Treatment

Cronemberger

Nakamatsu

Mariano

et al. 2016

MSF

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“…Tais precipitados apresentaram-se na forma de linhas escuras nos contornos de grãos ferríticos, conforme pode ser observado nas micrografias a seguir, obtidas via MEV (Figura 7). A morfologia dos precipitados assemelha-se a precipitados de nitreto de cromo encontrados por outros autores [4,5]. Outro fato pode reforçar a possibilidade de tais precipitados se tratarem realmente de nitretos de cromo: eles se apresentaram na ZTA das soldas de menores aportes, o que é característico do nitreto de cromo, uma vez que este se precipita quando as taxas de resfriamento são altas dificultando a difusão de elementos na ferrita e criando regiões saturadas.…”

Section: Microestrutura Da Zta Das Juntas Soldadasunclassified

Efeito Do Aporte Térmico E Do Gás De Proteção Sobre a Microestrutura De Juntas Soldadas Do Aço Inoxidável Superduplex Saf 2507 (Uns S32750)

Almeida¹,

Xavier²,

Marcelo³

et al. 2019

ABM Proceedings

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ResumoSuperduplex são aços inoxidáveis bifásicos de alta liga que, para alcançar suas excelentes propriedades mecânicas e de resistência à corrosão necessitam de um rígido controle sobre sua microestrutura, em especial sobre dois aspectos: relação ferrita/austenita e precipitação de fases deletérias. As transformações metalúrgicas que ocorrem durante o ciclo térmico de soldagem podem modificar tais aspectos e, consequentemente, causar grave degradação das propriedades destes materiais. Buscando contribuir na investigação de parâmetros adequados para a soldagem destes aços, o presente estudo tem como objetivo avaliar a influência do aporte térmico e do gás de proteção sobre tais transformações por meio da avaliação da microestrutural final de juntas soldadas. Para isto seis chapas do SAF2507 foram soldadas via processo GMAW utilizando três aportes diferentes (0,5; 1,5 e 2,2 kJ/mm) e dois gases de proteção distintos. Após a soldagem, a microestrutura das juntas foi caracterizada via microscopia óptica e microscopia eletrônica de varredura e os resultados mostraram que o aumento do aporte térmico elevou significativamente a quantidade de austenita tanto na ZTA quanto na ZF e que a utilização de gás de proteção contendo 2% de N causou aumento de até 17,9 pontos percentuais na quantidade média de austenita na ZF. Adicionalmente, observou-se que os dois menores aportes provocaram a precipitação de fases secundárias na ZTA, com morfologia semelhante à nitreto de cromo. Palavras-chave: Soldagem; Aços inoxidáveis bifásicos; Microestrutura; ZTA. THE EFFECT OF HEAT INPUT AND SHIELDING GAS ON THE MICROSTRUCTURE OF SAF 2507 (UNS S32750) SUPERDUPLEX STAINLESS STEEL WELDED JOINTS AbstractSuperduplex are biphasic stainless steels which, to achieve its excellent mechanical properties and corrosion resistance, require hard control on its microstructure, mainly on two aspects: ferrite-austenite ratio and deleterious phases. The metallurgical transformations which occur during the welding thermal cycle might modify these aspects and thus cause serious degradation of the properties of these materials. Seeking to contribute in research of appropriate parameters for welding of these steels, the current study aims to evaluate the influence of heat input and shielding gas on such transformations by evaluating the final microstructure of welded joints. Therefore, six SAF2507 plates were welded by GMAW process using three different heat input (0.5; 1.5 and 2.2 kJ/mm) and two different shielding gas. After welding, the microstructure of the joints were characterized by optical microscopy and scanning electron microscopy and the results showed that the increase in heat input significantly increased the amount of austenite in both HAZ and FZ and that the use of shielding gas containing 2%N caused increase of up to 17.9 percentage points in the average amount of austenite in FZ. Additionally, it was observed that the two smaller heat input caused the precipitation of secondary phases in the HAZ with morphology similar to chromium nitride.

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“…Only few references report on circumferential welds or the influence of welding position on weld properties of duplex and superduplex stainless steel pipes [3][4][5], and none of them have systematically studied the effect of welding positions. Therefore, this research work aims at studying the influence of different welding positions on both corrosion and mechanical properties as well as their influence on dilution and imperfections in duplex and superduplex stainless steel circumferential welds.…”

Section: Introductionmentioning

confidence: 99%

Effect of welding position on properties of duplex and superduplex stainless steel circumferential welds

et al. 2015

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The influence of welding position on properties of duplex and superduplex stainless steel welds was studied. Circumferential pipe welds were produced using mechanised gas metal arc welding in flat position, vertical up position and overhead position. Dilution, corrosion resistance, mechanical properties, microstructural features and weld imperfections were assessed and related to the welding position. Welds produced in flat and vertical up positions were less likely to produce porosity than those welded in overhead position, whilst underfill was not observed in overhead position welds. All the duplex pipe welds passed the corrosion test regardless of the welding position and showed sound microstructures. Under fixed arc energy conditions, welds produced in vertical up position showed the lowest dilution values whilst welds in flat position showed the highest. Excellent impact toughness values and cross tensile values were found regardless of the welding positions. Whenever possible, flat position is recommended as welds showed less proneness to porosity. Vertical up position is recommended as the second best choice.

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Investigation of the sensitization and intergranular corrosion of tube-to-tubesheet welds of hyper duplex stainless steel using an electrochemical reactivation method

Cited by 73 publications

References 42 publications

Effect of Cooling Rate on the Corrosion Behavior of As-Cast SAF 2205 Duplex Stainless Steel after Solution Annealing Treatment

Effect of Cooling Rate on the Corrosion Behavior of As-Cast SAF 2205 Duplex Stainless Steel after Solution Annealing Treatment

Efeito Do Aporte Térmico E Do Gás De Proteção Sobre a Microestrutura De Juntas Soldadas Do Aço Inoxidável Superduplex Saf 2507 (Uns S32750)

Effect of welding position on properties of duplex and superduplex stainless steel circumferential welds

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