Corrosion behavior of UNS S31803 steel with changes in the volume fraction of ferrite and the presence of chromium nitride

Lacerda, José Carlos de; Cândido, Luiz Cláudio; Godefroid, Leonardo Barbosa

doi:10.1016/j.msea.2015.09.092

Cited by 23 publications

(9 citation statements)

References 31 publications

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“…Austenite is just like a barrier to defend external invasions [ 38 ]. Additionally, the precipitation of chromium nitrides was critical to the degradation of pitting corrosion resistance [ 43 , 44 ]. As these Cr 2 N precipitates are concentrated in Cr, N with a little Fe, Ni, and Mo, the Cr depleted region around Cr 2 N would be unable to prevent the pitting initiation [ 21 ].…”

Section: Resultsmentioning

confidence: 99%

Microstructure, Pitting Corrosion Resistance and Impact Toughness of Duplex Stainless Steel Underwater Dry Hyperbaric Flux-Cored Arc Welds

Shi

Shen

et al. 2017

Materials

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Duplex stainless steel multi-pass welds were made at 0.15 MPa, 0.45 MPa, and 0.75 MPa pressure, simulating underwater dry hyperbaric welding by the flux-cored arc welding (FCAW) method, with welds of normal pressure as a benchmark. The purpose of this work was to estimate the effect of ambient pressure on the microstructure, pitting corrosion resistance and impact toughness of the weld metal. The microstructure measurement revealed that the ferrite content in the weld metal made at 0.45 MPa is the lowest, followed by that of 0.75 MPa and 0.15 MPa. The analysis of potentiodynamic polarization tests at 30 °C and 50 °C demonstrated that the pitting corrosion resistance depends on the phases of the lower pitting resistance equivalent numbers (PREN), secondary austenite and ferrite. The weld metal made at 0.45 MPa had the best resistance to pitting corrosion at 30 °C and 50 °C with the highest PRENs of secondary austenite and ferrite. The weld metal made at 0.15 MPa displayed the lowest pitting corrosion resistance at 30 °C with the lowest PREN of secondary austenite, while the weld metal made at 0.75 MPa was the most seriously eroded after being tested at 50 °C for the lowest PREN of ferrite, with large cluster pits seen in ferrite at 50 °C. The impact tests displayed a typical ductile-brittle transition because of the body-centered cubic (BCC) structure of the ferrite when the test temperature was lowered. All the weld metals met the required value of 34 J at −40 °C according to the ASTM A923. The highest ferrite content corresponded to the worst impact toughness, but the highest toughness value did not correspond to the greatest austenite content. With the decreasing of the test temperature, the drop value of absorbed energy was correlated to the ferrite content. Additionally, in this work, the weld metal made at 0.45 MPa had the best combined properties of pitting resistance and impact toughness.

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Section: Resultsmentioning

confidence: 99%

Microstructure, Pitting Corrosion Resistance and Impact Toughness of Duplex Stainless Steel Underwater Dry Hyperbaric Flux-Cored Arc Welds

Shi

Shen

et al. 2017

Materials

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“…That is, the lower the fraction of pearlite, the slower the corrosion rate of steel in this study. Pitting corrosion tends to initiate by galvanic corrosion of ferrite and Fe 3 C [14,[18][19][20]; at the same time, pearlite is composed of ferrite and cementite. So pulsed electric current can increase the corrosion resistance of the plain carbon steels by decreasing the fraction of pearlite in this study.…”

Section: Resultsmentioning

confidence: 99%

Modification of Corrosion Resistance of the Plain Carbon Steels by Pulsed Electric Current

Gao

Liu

Zhou

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

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The fracture of pipelines caused by corrosion cracks and the resulting oil and gas leakage can lead to great environmental pollution and economic losses. These negative effects are due to serious corrosion of the plain carbon steels used for armor of flexible pipe in oil and gas transmission medium. However, corrosion resistance of carbon steel armors has yet to be improved. In this study, the relationship between corrosion resistance and pearlite fraction in the plain carbon steels has been investigated through the application of pulsed electric current. Based on immersion test and electrochemical measurement, pulsed electric current increases the corrosion resistance of the plain carbon steels by reducing the fraction of pearlite phase. Pitting corrosion, which tends to initiate by galvanic corrosion of ferrite and cementite, is therefore inhibited due to the decrease in pearlite fraction (mixture of ferrite and cementite) under electropulsing.

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“…An EBSD-SEM analysis of the samples submitted to D2 condition (Figure 10) showed the presence of CrN (mainly at ferrite grain boundaries, green color in Figure 10) and Cr 2 N. The sample from the heat treatment D2 was chosen because it favors the supersaturation of nitrogen in ferrite (total ferritization) and, consequently, the precipitation during the fast cooling. The CrN has a cubic NaCl structure (space group Fm-3m) 20 . The Cr 2 N has a trigonal structure forming a hexagonal subcell (spatial group P-31m) The electrolytic etching with oxalic acid (Figure 11) highlighted the presence of chromium nitrides at subgrain boundaries, as predicted by Ramirez et.…”

Section: Chromium Nitridementioning

confidence: 99%

Characterization of the Austenite Reformation Mechanisms as a Function of the Initial Ferritic State in a UNS S32304 Duplex Stainless Steel

et al. 2017

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Aiming to better understand the effects of heat treatment parameters on Ferrite-Austenite phase transformation in a 2304 duplex stainless steel different thermal cycles were applied to this steel in a quenching dilatometer. The obtained microstructures were characterized by optical microscopy, transmission electron microscopy and electron backscatter diffraction. It was noticed that the austenite formation mechanism is strongly dependent on initial ferritized state. If the initial structure is completely ferritized, the nitrogen supersaturated solid solution leads to chromium nitrides precipitation and the rate of austenite nucleation decreases. For higher cooling rates, the ferrite grain boundaries control the austenite nucleation rate. The higher the ferrite grain size, the lower the final austenite fraction. If the steel is cooled from a partial ferritized state, the ferrite-austenite phase boundaries work as austenite nucleation site and the austenite growth rate is favored due to the high interfacial energy and the austenitic structures becomes coarser.

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Corrosion behavior of UNS S31803 steel with changes in the volume fraction of ferrite and the presence of chromium nitride

Cited by 23 publications

References 31 publications

Microstructure, Pitting Corrosion Resistance and Impact Toughness of Duplex Stainless Steel Underwater Dry Hyperbaric Flux-Cored Arc Welds

Microstructure, Pitting Corrosion Resistance and Impact Toughness of Duplex Stainless Steel Underwater Dry Hyperbaric Flux-Cored Arc Welds

Modification of Corrosion Resistance of the Plain Carbon Steels by Pulsed Electric Current

Characterization of the Austenite Reformation Mechanisms as a Function of the Initial Ferritic State in a UNS S32304 Duplex Stainless Steel

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