Environmental Assisted Cracking Behavior of Sigmatized Super Duplex Stainless Steel in Oilfield Production Brine

Saithala, Janardhan Rao; Mahajanam, Sudhakar; Ubhi, H. S.; Atkinson, John D.

doi:10.5006/0696

Cited by 12 publications

(9 citation statements)

References 13 publications

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“…These samples have been compared with one left at as-received state (0% of r phase). The temperature of the oven was (850°C) because it is considered the critical temperature for r phase precipitation in SDSS ( Ref 10,28).…”

Section: Methodsmentioning

confidence: 99%

Detection of Secondary Phases in UNS S32760 Superduplex Stainless Steel by Destructive and Non-destructive Techniques

Argandoña¹,

Biezma

Berrueta³

et al. 2016

J. of Materi Eng and Perform

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Duplex stainless steels (DSS), with a microstructure of an approximately equal mixture of ferrite (a) and austenite (c) phases, are susceptible to the formation of undesirable phases if manufacturing processes are not carefully controlled. In particular, sigma phase (r) is a Cr-and Mo-rich intermetallic phase, formed generally when DSS are by the temperature range from 600 to 900°C, even for very short time periods. The precipitation of this phase induces detrimental effects in mechanical and corrosion resistance properties in the material, and even a low volume percentage of r phase can significantly affect these properties. The current paper presents the effect of thermal treatments on UNS S32760 superduplex stainless steel seamless tubes, applied in order to promote the precipitation of different r phase percentages in a ferrite/ austenite microstructure. The detection and quantification of the r phase using non-destructive ultrasounds testing has been one of the most relevant events of this study that contributes to improving the correlation of the results obtained using destructive and non-destructive techniques for the quantification of undesirable phases in superduplex seamless tubes during the manufacturing process.

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Section: Methodsmentioning

confidence: 99%

Detection of Secondary Phases in UNS S32760 Superduplex Stainless Steel by Destructive and Non-destructive Techniques

Argandoña¹,

Biezma

Berrueta³

et al. 2016

J. of Materi Eng and Perform

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“…The resistance of DSSs to SCC is markedly reduced by high temperature, low pH and high applied stress [ 4 ]. Constant deformation U-bend, constant load dead-weight, slow strain rate test (SSRT) and fracture mechanics techniques are commonly used for testing SCC susceptibility in aggressive solutions [ 5 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. In particular, SSRT method (ASTM 129) is performed under tensile loading at low strain rates (e.g., 10 −6 –10 −7 /s) [ 75 ].…”

Section: Corrosion Propertiesmentioning

confidence: 99%

“…The steel specimens aged at 675 °C for 10 h and at 900 °C for 4 h are particular vulnerable to SCC as revealed by very low tensile elongation of ~5%. More recently, Saithala et al [ 74 ] annealed UNS S32750 superduplex at 1080 °C, followed by aging at 850 °C from 45 s up to 12 min. They reported that low levels of σ-phase (less than 2 vol%) have little effect on the mechanical properties of SDSS exposed to a simulated oil field brine containing carbon dioxide/hydrogen sulfide.…”

Section: Corrosion Propertiesmentioning

confidence: 99%

Effect of Secondary Phase Precipitation on the Corrosion Behavior of Duplex Stainless Steels

2014

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Duplex stainless steels (DSSs) with austenitic and ferritic phases have been increasingly used for many industrial applications due to their good mechanical properties and corrosion resistance in acidic, caustic and marine environments. However, DSSs are susceptible to intergranular, pitting and stress corrosion in corrosive environments due to the formation of secondary phases. Such phases are induced in DSSs during the fabrication, improper heat treatment, welding process and prolonged exposure to high temperatures during their service lives. These include the precipitation of sigma and chi phases at 700–900 °C and spinodal decomposition of ferritic grains into Cr-rich and Cr-poor phases at 350–550 °C, respectively. This article gives the state-of the-art review on the microstructural evolution of secondary phase formation and their effects on the corrosion behavior of DSSs.

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“…However, its main drawback is the tendency to form detrimental phases at temperatures between 600 • C and 900 • C, being the cause of a significant loss of toughness and resistance to localized corrosion. One of the most known and representative detrimental phases is the precipitation of the sigma phase (σ), a Cr-and Mo-rich intermetallic compound [12][13][14][15][16][17][18][19][20][21]. This σ phase shows a tetragonal crystallographic structure with 32 atoms per unit cell [22] making possible a considerable increase in the resultant hardness, whereas a decrease in the toughness as well as elongation is also observed [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Effect of the Temperature in the Mechanical Properties of Austenite, Ferrite and Sigma Phases of Duplex Stainless Steels Using Hardness, Microhardness and Nanoindentation Techniques

Argandoña¹,

Palacio

Berlanga

et al. 2017

Metals

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Abstract:The aim of this work is to study the hardness of the ferrite, austenite and sigma phases of a UNS S32760 superduplex stainless steel submitted to different thermal treatments, thus leading to different percentages of the mentioned phases. A comparative study has been performed in order to evaluate the resulting mechanical properties of these phases by using hardness, microhardness and nanoindentation techniques. In addition, optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been also used to identify their presence and distribution. Finally, the experimental results have shown that the resulting hardness values were increased as a function of a longer heat treatment duration which it is associated to the formation of a higher percentage of the sigma phase. However, nanoindentation hardness measurements of this sigma phase showed lower values than expected, being a combination of two main factors, namely the complexity of the sigma phase structure as well as the surface finish (roughness).

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Environmental Assisted Cracking Behavior of Sigmatized Super Duplex Stainless Steel in Oilfield Production Brine

Cited by 12 publications

References 13 publications

Detection of Secondary Phases in UNS S32760 Superduplex Stainless Steel by Destructive and Non-destructive Techniques

Detection of Secondary Phases in UNS S32760 Superduplex Stainless Steel by Destructive and Non-destructive Techniques

Effect of Secondary Phase Precipitation on the Corrosion Behavior of Duplex Stainless Steels

Effect of the Temperature in the Mechanical Properties of Austenite, Ferrite and Sigma Phases of Duplex Stainless Steels Using Hardness, Microhardness and Nanoindentation Techniques

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