Journal articles: 'Phase transformation, Duplex Stainless Steels, Dual Phase Steels'

1

Pohl, Michael, and Oliver Storz. "Sigma-phase in duplex-stainless steels." International Journal of Materials Research 95, no. 7 (July 1, 2004): 631–38. http://dx.doi.org/10.1515/ijmr-2004-0120.

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Abstract The ferritic-austenitic duplex-steels have a very complex precipitation and transformation behaviour, which requires professional treatment. Especially the precipitation of the σ-phase causes considerable changes with regard to the mechanical as well as the corrosive properties, which are to be considered during the treatment of the duplex-steels.

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Padilha, Angelo Fernando, D. J. M. Aguiar, and R. L. Plaut. "Duplex Stainless Steels: A Dozen of Significant Phase Transformations." Defect and Diffusion Forum 322 (March 2012): 163–74. http://dx.doi.org/10.4028/www.scientific.net/ddf.322.163.

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During processing or use, duplex stainless steels are subject to a great number of significant phase transformations, such as solidification, partial ferrite transformation to austenite, ferrite eutectoid decomposition to sigma phase plus austenite, chi phase precipitation, chromium carbide precipitation, chromium nitride precipitation, ferrite spinodal decomposition, phase dissolution during solution annealing, forming of two types (epsilon and alpha prime) of strain induced martensite, martensite reversion to austenite, ferrite and austenite recrystallization. This paper summarizes the phase transformations that occur (individually or combined) in duplex stainless steels and presents some new results.

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Cordeiro de Oliveira, Angela Maria, Ramón Sigifredo Cortés Paredes, Walmor Cardoso Godoi, and Sergio Luiz Henke. "Comparison between UNS S32101 and UNS S32205 hydrogenated." International Journal of Scientific Research and Management 9, no. 1 (January 29, 2021): 556–63. http://dx.doi.org/10.18535/ijsrm/v9i1.ec02.

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This work presents a study on the duplex stainless steels UNS S32101 and UNS S32205 when subjected to cathodic hydrogenation, to ascertain their behavior under the action of hydrogen. It was evaluated for embrittlement and phase transformations induced by hydrogen, in order to check whether nickel and molybdenum contents would improve resistance to the harmful effects of hydrogen. With the aid of optical (MO) and scanning electron microscopy (SEM), both hydrogen embrittlement in both steels after hydrogenation and degassing was evidenced, as well as pitting corrosion on UNS S32101 duplex stainless steel. It appears that hydrogen can induce the transformation of the austenitic phase (g) into the martensitic phase (α') in the two duplex stainless steels analyzed and it is verified that hydrogen can lead to the formation of sigma phase at room temperature in duplex stainless steel UNS type S32101

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Mészáros, István, Bálint Bögre, and Péter János Szabó. "Magnetic and Thermoelectric Detection of Sigma Phase in 2507 Duplex Stainless Steel." Crystals 12, no. 4 (April 10, 2022): 527. http://dx.doi.org/10.3390/cryst12040527.

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Duplex stainless steel has significantly broadened the range of applications of stainless steel. They have a dual-phase microstructure containing ferrite and austenite at approximately a 50–50% phase ratio. Their corrosion resistance is much better compared to the traditional austenitic stainless steel, especially in surroundings containing chloride ion. Moreover, the large stress yield of duplex steels offers significant advantages in structural applications. The ferrite phase in some duplex stainless steels is metastable due to its composition. Consequently, the ferrite can decompose to a secondary austenite and sigma phase due to heat input. The sigma phase is a hard and brittle intermetallic compound phase that significantly deteriorates the mechanical and corrosion-resistant properties of duplex stainless steel. The embrittlement can cause a safety risk in industrial applications. This paper is a preliminary study to investigate what physical properties can be used to obtain information on sigma-phase-induced embrittlement. In this work, the effect of plastic deformation and heat treatment was studied in the appearance of the sigma phase in 2507 duplex stainless steel. Magnetic saturation polarization and thermoelectric power measurements were used to monitor the microstructural changes due to cold rolling and heat treatment. It was found that the magnetic saturation polarization and thermoelectric power measurements can be effective tools for monitoring the sigma-phase formation in duplex stainless steels due to heat input. Their application helps to prevent the embrittlement problems caused by the sigma-phase formation in duplex stainless steel structures.

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Dabah, E., V. Lisitsyn, and D. Eliezer. "Performance of hydrogen trapping and phase transformation in hydrogenated duplex stainless steels." Materials Science and Engineering: A 527, no. 18-19 (July 2010): 4851–57. http://dx.doi.org/10.1016/j.msea.2010.04.016.

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Bassani, Paola, Marco Breda, Katya Brunelli, Istvan Mészáros, Francesca Passaretti, Michela Zanellato, and Irene Calliari. "Characterization of a Cold-Rolled 2101 Lean Duplex Stainless Steel." Microscopy and Microanalysis 19, no. 4 (May 31, 2013): 988–95. http://dx.doi.org/10.1017/s1431927613001426.

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AbstractDuplex stainless steels (DSS) may be defined as a category of steels with a two-phase ferritic–austenitic microstructure, which combines good mechanical and corrosion properties. However, these steels can undergo significant microstructural modification as a consequence of either thermo-mechanical treatments (ferrite decomposition, which causes σ- and χ-phase formation and nitride precipitation) or plastic deformation at room temperature [austenite transformation into strain-induced martensite (SIM)]. These secondary phases noticeably affect the properties of DSS, and therefore are of huge industrial interest. In the present work, SIM formation was investigated in a 2101 lean DSS. The material was subjected to cold rolling at various degrees of deformation (from 10 to 80% thickness reduction) and the microstructure developed after plastic deformation was investigated by electron backscattered diffraction, X-ray diffraction measurements, and hardness and magnetic tests. It was observed that SIM formed as a consequence of deformations higher than ~20% and residual austenite was still observed at 80% of thickness reduction. Furthermore, a direct relationship was found between microstructure and magnetic properties.

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Villalobos Vera, Doris Ivette, and Ivan Mendoza Bravo. "Effect of annealing temperature on the microstructure of hyperduplex stainless steels." Ingeniería Investigación y Tecnología 20, no. 2 (March 1, 2019): 1–6. http://dx.doi.org/10.22201/fi.25940732e.2019.20n2.024.

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Samples of hyperduplex stainless steels were produced experimentally and exposed to different conventional annealing heat treatments in order to obtain the microstructural balance of 50% ferrite and 50% austenite. To differentiate the ferrite and austenite from any secondary phase, selective etching was used and quantitative metallography was performed to measure the percentage of phases. Results showed that conventional annealing heat treatments promote the transformation from ferrite to sigma phase and secondary austenite, suggesting a higher occurrence of sigma phase in the experimental hyperduplex alloys compared to other duplex alloys due to the superior content of chromium and molybdenum. On the other hand, a balanced microstructure free of secondary phases was accomplished increasing the temperature of the annealing heat treatment, which allowed the transformation of ferrite into austenite during cooling.

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Calliari, Irene, Marco Breda, Claudio Gennari, Luca Pezzato, Massimo Pellizzari, and Andrea Zambon. "Investigation on Solid-State Phase Transformations in a 2510 Duplex Stainless Steel Grade." Metals 10, no. 7 (July 17, 2020): 967. http://dx.doi.org/10.3390/met10070967.

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Duplex and Super Duplex Stainless Steels are very prone to secondary phases formation related to ferrite decomposition at high temperatures. In the present paper the results on secondary phase precipitation in a 2510 Duplex Stainless Steel, heat-treated in the temperature range 850–1050 °C for 3–30 min are presented. The precipitation starts at grain boundaries with a consistent ferrite transformation for very short times. The noses of the Time–Temperature–Precipitation (TTP) curves are at 1000 °C for σ-phase and at 900 °C for χ-phase, respectively. The precipitation sequence involves a partial transformation of χ into σ, as previously evidenced in 2205 and 2507 grades. Furthermore, the experimental data were compared to the results of Thermo-Calc calculations. Understanding and ability to predict phase stability in 2510 duplex stainless steel is a key factor to design optimal welding processes that avoid any secondary phase precipitation in the weld bead as well as in the heat-affected zone.

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Calliari, Irene, Emilio Ramous, and Paola Bassani. "Phase Transformation in Duplex Stainless Steels after Isothermal Treatments, Continuous Cooling and Cold Working." Materials Science Forum 638-642 (January 2010): 2986–91. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.2986.

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This paper concerns the phase transformation induced by heat treatment and cold rolling in four duplex stainless steel. In 2205 and 2507 , during the isothermal heat treatments, chi-phase precipitates as small particles at the ferrite/austenite boundaries, followed by sigma precipitation. At the lowest temperature the formation kinetic of chi-phase is favoured, with the increasing of time and temperature a progressive transformation of chi to sigma occurs and the kinetic of sigma is favoured. During continuous cooling, the chi -phase appears at low cooling rates. In low Ni grades the grain boundaries precipitation of chromium nitrides were detected , but no sigma and chi. In 2101 the austenite transforms to martensite both after cold rolling and quenching

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Simon, Soma Csaba, and Balázs Varbai. "High Heat Input Welding of NSSC 2120 Type Lean Duplex Steel." Acta Materialia Transylvanica 5, no. 1 (April 1, 2022): 35–38. http://dx.doi.org/10.33924/amt-2022-01-08.

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Abstract Duplex stainless steels offer a high strength alternative to stainless steel, while providing excellent corrosion resistance, due to their dual-phase microstructure. This microstructure can be significantly influenced during welding, thus the maximum recommended heat input is usually 2.5 kJ/mm. In this research, we inspected the high heat input (3 kJ/mm) weldability of NSSC 2120 lean duplex stainless steel, which is designed and developed specifically for this purpose. The welds were evaluated by metallographic techniques and corrosion tests. It was found the NSSC 2120 grade can be welded with high heat input without deterioration in the phase balance and microstructure.

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Fan, Guang Wei, Jie Liu, Pei De Han, Guan Jun Qiao, and Jian Feng Yang. "Effect of Warm Processing Parameters on the Precipitation of γ'-Phase in 2205 Duplex Stainless Steels." Materials Science Forum 620-622 (April 2009): 165–68. http://dx.doi.org/10.4028/www.scientific.net/msf.620-622.165.

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Effect of the warm processing parameters (the strain rate, forming temperature and deformation degree ) on the γ' metastable phase transformation in 2205 duplex stainless steel has been studied. The γ' metastable phase was located within the ferrite phase. Dynamic recovery took place only within the γ phase, and dynamic recrystallization underwent for the ferrite phase. The γ' metastable phase transformation was affected by the deformation degree and about 15% deformation led to appearance of the γ' metastable phase. γ' metastable phase formation by the precipitation of intragranular γ' was favored by increasing ageing time, and the size and content of γ' metastable phase were related to deformation temperature and strain rates.

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Yurtisik, Koray, Suha Tirkes, Igor Dykhno, C. Hakan Gur, and Riza Gurbuz. "Characterization of duplex stainless steel weld metals obtained by hybrid plasma-gas metal arc welding." Soldagem & Inspeção 18, no. 3 (September 2013): 207–16. http://dx.doi.org/10.1590/s0104-92242013000300003.

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Despite its high efficiency, autogenous keyhole welding is not well-accepted for duplex stainless steels because it causes excessive ferrite in as-welded duplex microstructure, which leads to a degradation in toughness and corrosion properties of the material. Combining the deep penetration characteristics of plasma arc welding in keyhole mode and metal deposition capability of gas metal arc welding, hybrid plasma - gas metal arc welding process has considered for providing a proper duplex microstructure without compromising the welding efficiency. 11.1 mm-thick standard duplex stainless steel plates were joined in a single-pass using this novel technique. Same plates were also subjected to conventional gas metal arc and plasma arc welding processes, providing benchmarks for the investigation of the weldability of the material. In the first place, the hybrid welding process enabled us to achieve less heat input compared to gas metal arc welding. Consequently, the precipitation of secondary phases, which are known to be detrimental to the toughness and corrosion resistance of duplex stainless steels, was significantly suppressed in both fusion and heat affected zones. Secondly, contrary to other keyhole techniques, proper cooling time and weld metal chemistry were achieved during the process, facilitating sufficient reconstructive transformation of austenite in the ferrite phase.

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Kim, Yoon-Jun, L. Scott Chumbley, and Brian Gleeson. "Determination of isothermal transformation diagrams for sigma-phase formation in cast duplex stainless steels CD3MN and CD3MWCuN." Metallurgical and Materials Transactions A 35, no. 11 (November 2004): 3377–86. http://dx.doi.org/10.1007/s11661-004-0174-9.

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14

David, Charles, Fiona Ruel, Florent Krajcarz, Clément Boissy, Saghi Saedlou, and Vincent Vignal. "Effect of Grain Size on the Anodic Dissolution of Lean Duplex UNS S32202 Austenitic-Ferritic Stainless Steel." Corrosion 75, no. 12 (September 30, 2019): 1450–60. http://dx.doi.org/10.5006/3218.

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The effect of grain size on the anodic dissolution of lean duplex UNS S32202 dual-phase austenitic-ferritic stainless steel was evaluated. Grain coarsening was achieved by heat treatment, and grain size and grain boundary densities determined by automatic image analysis after etching. Potentiodynamic electrochemical testing in acidic chloride medium allowed isolating the anodic dissolution behavior of the crystallographic phases of the material. A relationship between grain boundary density (for grain sizes in the micrometer range) and dissolution rate has been found, showing that reducing grain size enhances active corrosion rates in environments that promote active behavior. This leads to new possibilities of industrial adjustment of the corrosion behavior of duplex stainless steels via grain size control.

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Narahari Prasad, S., K. Rajasekhar, and M. Chatterjee. "Influence of Composition and Processing on Properties of Stainless Steels." Advanced Materials Research 794 (September 2013): 117–23. http://dx.doi.org/10.4028/www.scientific.net/amr.794.117.

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Stainless steels, by virtue of their diversity in chemistry, microstructure and properties, find widespread applications ranging from domestic appliances to high technology sectors such as space, aeronautics, power, chemical and ordnance. Midhani has been at the forefront of material development over the past few decades and has produced several stainless steels, tailor made for specific critical applications. Subtle variations in chemistry or processing methodology have been exercised to achieve the desired microstructure and properties. In this context, influence of minor addition of austenitic stabilizing element on structure and properties on conventional ferritic stainless steel SS430 was studied. The chemistry modification changed the structure to dual phase, austenite ferrite structure, that responded to heat treatment by transformation of austenite to martensite. This dual phase structure after tempering enhanced the strength and toughness by 25% and 60% respectively. In the case of 13-8 Mo PH stainless steel, a modified two stage solution treatment and ageing resulted in enhancement of toughness by over 100% as compared to conventional single stage solution treatment and the improvement was attributable to refinement in martensitic sub-structure due to thermal cycling. With respect to SS 440C, a high carbon stainless steel, the performance is closely related distribution of primary carbide. Bearing directly manufactured from forged stock produced from ingot do not perform satisfactorily in view of massive primary carbides present in the form of stringers / bands. This problem was addressed by subjecting the forged stock to further working in the transverse orientation by ring rolling which brought about finer primary carbides. The present paper highlights some of the challenges and the modifications brought about to meet the specific needs.

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Schade, Christopher, and John Schaberl. "Development of High Performance Stainless Steel Powders." Materials Science Forum 534-536 (January 2007): 33–36. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.33.

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Advanced melting technology is now being employed in the manufacture of stainless steel powders. The new process currently includes electric arc furnace (EAF) technology in concert with Argon Oxygen Decarburization (AOD), High Performance Atomizing (HPA) and hydrogen annealing. The new high performance processing route has allowed the more consistent production of existing products, and has allowed enhanced properties, such as improved green strength and green density. This paper will review these processing changes along with the potential new products that are being developed utilizing this technology. These include high strength stainless steels such as duplex and dual phase as well as stainless steel powders used in high temperature applications such as diesel filters and fuel cells.

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Raabe, Dierk, Binhan Sun, Alisson Kwiatkowski Da Silva, Baptiste Gault, Hung-Wei Yen, Karo Sedighiani, Prithiv Thoudden Sukumar, et al. "Current Challenges and Opportunities in Microstructure-Related Properties of Advanced High-Strength Steels." Metallurgical and Materials Transactions A 51, no. 11 (September 5, 2020): 5517–86. http://dx.doi.org/10.1007/s11661-020-05947-2.

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Abstract This is a viewpoint paper on recent progress in the understanding of the microstructure–property relations of advanced high-strength steels (AHSS). These alloys constitute a class of high-strength, formable steels that are designed mainly as sheet products for the transportation sector. AHSS have often very complex and hierarchical microstructures consisting of ferrite, austenite, bainite, or martensite matrix or of duplex or even multiphase mixtures of these constituents, sometimes enriched with precipitates. This complexity makes it challenging to establish reliable and mechanism-based microstructure–property relationships. A number of excellent studies already exist about the different types of AHSS (such as dual-phase steels, complex phase steels, transformation-induced plasticity steels, twinning-induced plasticity steels, bainitic steels, quenching and partitioning steels, press hardening steels, etc.) and several overviews appeared in which their engineering features related to mechanical properties and forming were discussed. This article reviews recent progress in the understanding of microstructures and alloy design in this field, placing particular attention on the deformation and strain hardening mechanisms of Mn-containing steels that utilize complex dislocation substructures, nanoscale precipitation patterns, deformation-driven transformation, and twinning effects. Recent developments on microalloyed nanoprecipitation hardened and press hardening steels are also reviewed. Besides providing a critical discussion of their microstructures and properties, vital features such as their resistance to hydrogen embrittlement and damage formation are also evaluated. We also present latest progress in advanced characterization and modeling techniques applied to AHSS. Finally, emerging topics such as machine learning, through-process simulation, and additive manufacturing of AHSS are discussed. The aim of this viewpoint is to identify similarities in the deformation and damage mechanisms among these various types of advanced steels and to use these observations for their further development and maturation.

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Yoon, Hanme, Heon-Young Ha, Tae-Ho Lee, Sung-Dae Kim, Jae Hoon Jang, Joonoh Moon, and Namhyun Kang. "Pitting Corrosion Resistance and Repassivation Behavior of C-Bearing Duplex Stainless Steel." Metals 9, no. 9 (August 26, 2019): 930. http://dx.doi.org/10.3390/met9090930.

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The effects of C-substitution for part of the N content, on the pitting corrosion resistance and repassivation tendencies of duplex stainless steels (DSSs) were investigated. For this investigation, normal UNS S32205 containing N only (DSS-N) and the C-substituted DSS (DSS-NC) were fabricated. Microstructural analyses confirmed that the two DSSs had dual-phase microstructures without precipitates, and they possessed similar initial microstructure, including their grain sizes and phase fractions. Polarization and immersion tests performed in concentrated chloride solutions revealed that the DSS-NC was more resistant against stable pitting corrosion and possessed a higher repassivation tendency than the DSS-N. Furthermore, the corrosion pits initiated and propagated to a less corrosion resistant α phase. Polarization tests and corrosion depth measurements conducted in an HCl solution indicated that the DSS-NC exhibited lower galvanic corrosion rate between the α and γ phases than the DSS-N. Therefore, the growth rate of pit embryo was lowered in the DSS-NC, which shifted the potentials for the stable pit initiation and the pit extinction to the higher values.

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Kim, Sun Mi, Ji Soo Kim, Kwang Tae Kim, Kyung-Tae Park, and Chong Soo Lee. "Effect of Ce addition on secondary phase transformation and mechanical properties of 27Cr–7Ni hyper duplex stainless steels." Materials Science and Engineering: A 573 (June 2013): 27–36. http://dx.doi.org/10.1016/j.msea.2013.02.044.

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Juuti, Timo, Timo Manninen, Sampo Uusikallio, Jukka Kömi, and David Porter. "New Ferritic Stainless Steel for Service Temperatures up to 1050 °C Utilizing Intermetallic Phase Transformation." Metals 9, no. 6 (June 7, 2019): 664. http://dx.doi.org/10.3390/met9060664.

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A large number of thermodynamic simulations has been used to design a new Nb-Ti dual stabilized ferritic stainless steel with excellent creep resistance at 1050 °C through an optimal volume fraction of Laves (η) phase stabilized by the alloying elements Nb, Si and Mo. By raising the dissolution temperature of the phase, which also corresponds to the onset of rapid grain growth, the steel will better maintain the mechanical properties at higher service temperature. Laves phase precipitates can also improve creep resistance through precipitation strengthening and grain boundary pinning depending on the dominant creep mechanism. Sag tests at high temperatures for the designed steel showed significantly better results compared to other ferritic stainless steels typically used in high temperature applications at present.

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de Castro, José Adilson, Gláucio Soares da Fonseca, D. S. S. Almeida, L. C. R. Lopes, C. R. Xavier, and Elizabeth Mendes de Oliveira. "Effects of Heat Input Conditions on the Local Thermophysical Properties of Super Duplex Stainless Steels." Materials Science Forum 930 (September 2018): 317–21. http://dx.doi.org/10.4028/www.scientific.net/msf.930.317.

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The thermal properties of the super duplex stainless steels are strongly affected by the thermal history when welding procedure are applied leading to substantial changes on the mechanical properties of the welding region. The controlled dual phase microstructure (ferrite and austenite) guarantee excellent mechanical properties such as mechanical strength and corrosion resistance, in addition to small thermal expansion coefficient and high thermal conductivity. In this research a model able to predict the thermal history of the welding pieces coupled with local mechanical properties developed during welding procedure is developed. The model was verified by measured temperature profile and used to predict local properties such as grain size evolution, hardness and mechanical strength. An inverse method was implemented to obtain the parameters fitting for the grain growth evolution, hardness and yielding strength compatible with the final microstructure and grain size measured using SEM images and stereological techniques.

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Gennari, Claudio, Mattia Lago, Balint Bögre, Istvan Meszaros, Irene Calliari, and Luca Pezzato. "Microstructural and Corrosion Properties of Cold Rolled Laser Welded UNS S32750 Duplex Stainless Steel." Metals 8, no. 12 (December 18, 2018): 1074. http://dx.doi.org/10.3390/met8121074.

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The main goal of this work was to study the effect of plastic deformation on weldability of duplex stainless steel (DSS). It is well known that plastic deformation prior to thermal cycles can enhance secondary phase precipitation in DSS which can lead to significant change of the ferrite-austenite phase ratio. From this point of view one of the most important phase transformation in DSS is the eutectoid decomposition of ferrite. Duplex stainless steels (DSSs) are a category of stainless steels which are employed in all kinds of applications where high strength and excellent corrosion resistance are both required. This favorable combination of properties is provided by their biphasic microstructure, consisting of ferrite and austenite in approximately equal volume fractions. Nevertheless, these materials may suffer from several microstructural transformations if they undergo heat treatments, welding processes or thermal cycles. These transformations modify the balanced phase ratio, compromising the corrosion and mechanical properties of the material. In this paper, the microstructural stability as a consequence of heat history due to welding processes has been investigated for a super duplex stainless steel (SDSS) UNS S32750. During this work, the effects of laser beam welding on cold rolled UNS S32750 SDSS have been investigated. Samples have been cold rolled at different thickness reduction (ε = 9.6%, 21.1%, 29.6%, 39.4%, 49.5%, and 60.3%) and then welded using Nd:YAG laser. Optical and electronical microscopy, eddy’s current tests, microhardness tests, and critical pitting temperature tests have been performed on the welded samples to analyze the microstructure, ferrite content, hardness, and corrosion resistance. Results show that laser welded joints had a strongly unbalanced microstructure, mostly consisting of ferritic phase (~60%). Ferrite content decreases with increasing distance from the middle of the joint. The heat-affected zone (HAZ) was almost undetectable and no defects or secondary phases have been observed. Both hardness and corrosion susceptibility of the joints increase. Plastic deformation had no effects on microstructure, hardness or corrosion resistance of the joints, but resulted in higher hardness of the base material. Cold rolling process instead, influences the corrosion resistance of the base material.

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Pareige, C., S. Novy, S. Saillet, and P. Pareige. "Study of phase transformation and mechanical properties evolution of duplex stainless steels after long term thermal ageing (>20years)." Journal of Nuclear Materials 411, no. 1-3 (April 2011): 90–96. http://dx.doi.org/10.1016/j.jnucmat.2011.01.036.

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Sobol, Oded, Gert Nolze, Romeo Saliwan-Neumann, Dan Eliezer, Thomas Boellinghaus, and Wolfgang E. S. Unger. "Novel approach to image hydrogen distribution and related phase transformation in duplex stainless steels at the sub-micron scale." International Journal of Hydrogen Energy 42, no. 39 (September 2017): 25114–20. http://dx.doi.org/10.1016/j.ijhydene.2017.08.016.

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Brown, J. E., and G. D. W. Smith. "Atom probe studies of spinodal processes in duplex stainless steels and single- and dual-phase FeCrNi alloys." Surface Science Letters 246, no. 1-3 (April 1990): A174—A175. http://dx.doi.org/10.1016/0167-2584(90)90046-a.

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Brown, J. E., and G. D. W. Smith. "Atom probe studies of spinodal processes in duplex stainless steels and single- and dual-phase Fe-Cr-Ni alloys." Surface Science 246, no. 1-3 (April 1991): 285–91. http://dx.doi.org/10.1016/0039-6028(91)90428-u.

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Liu, Sijia, and Keesam Shin. "Effect of Ultrasonic Shot Peening on the Microstructure of Austenitic Stainless Steel 316 and Super Duplex Stainless Steel UNS S32750." Journal of Nanoscience and Nanotechnology 20, no. 11 (November 1, 2020): 6904–11. http://dx.doi.org/10.1166/jnn.2020.18813.

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Shot peening for nanocrystallization of the surface region is a good way of improving corrosion-, fatigue-, and wear-resistance, etc. of metallic parts (Lu, K., 2014. Making strong nanomaterials ductile with gradients. Science, 345(6203), pp.1455–1456). The technique has been widely used for various materials as a method of surface modification. SUS316 has excellent corrosion and oxidation resistance with good formability However, its application is limited by the low mechanical strength and hardness. S32750 (duplex stainless steel) is one of most used tubing materials for oil/gas delivery systems in a corrosive environment under high pressure (Nilsson, J.O., 1992. Super duplex stainless steels. Materials Science and Technology, 8(8), pp.685–700). Thus, improving corrosion resistance is a key for the wider application and better maintenance of S32750. In our study, the alloy S32750 was heat-treated at 1070°C to obtain a precipitation-free microstructure (γ and δ dual-phase structure). It was then ultrasonic shot peened and microstructures were analyzed for: (1) surface nanocrystallization, (2) effect of the treatment processing parameters, and (3) the determination of microstructural evolution and the effect of the shot peening process.

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Jia, Yandong, Xingyu Yin, Yulai Xu, and Gang Wang. "Effects of Heat Treatment on Microstructure and Mechanical Properties of a Transformation-Induced Plasticity-Aided Economical Duplex Stainless Steel." Metals 12, no. 12 (November 25, 2022): 2019. http://dx.doi.org/10.3390/met12122019.

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In order to obtain steel with high tensile strength and elongation and good pitting resistance, the economical duplex stainless steel with and without the addition of tungsten (W) was prepared in this paper. The comparison and distribution of the two phases were controlled by optimizing the heat treatment process. The highest product of tensile strength and elongation of Cr19 series duplex stainless steel (DSS) DSS were obtained after solution treatment at 1050 °C for 5 min, up to 58692 Mpa%(876 Mpa * 67%), when the area f.raction of α was about 50.7%. The addition of tungsten reduces tensile strength due to the increased area fraction of α at 1050–1150 °C. Finer grain size leads to higher tensile strength after solution treatment at 1050 °C. The microstructure is characterized by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The steels exhibit an excellent transformation-induced plasticity (TRIP) effect after the solution treated is at 1050 °C, which may primarily be due to the existence of a more unstable austenite phase. The TRIP effect acts through the phase transformation of γ to α′-M during high deformation, and the orientation relationship of {111}γ || {110}α′-M & <110>γ || <001>α′-M belongs to the standard variants of Nishiyama–Wassermann relationship.

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Astafurova, Elena, Galina Maier, Evgenii Melnikov, Sergey Astafurov, Marina Panchenko, Kseniya Reunova, Andrey Luchin, and Evgenii Kolubaev. "Temperature-Dependent Deformation Behavior of “γ-austenite/δ-ferrite” Composite Obtained through Electron Beam Additive Manufacturing with Austenitic Stainless-Steel Wire." Journal of Composites Science 7, no. 2 (January 22, 2023): 45. http://dx.doi.org/10.3390/jcs7020045.

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Temperature dependence of tensile deformation behavior and mechanical properties (yield strength, ultimate tensile strength, and an elongation-to-failure) of the dual-phase (γ-austenite/δ-ferrite) specimens, obtained through electron-beam additive manufacturing, has been explored for the first time in a wide temperature range T = (77–300) K. The dual-phase structures with a dendritic morphology of δ-ferrite (γ + 14%δ) and with a coarse globular δ-phase (γ + 6%δ) are typical of the as-built specimens and those subjected to a post-production solid–solution treatment, respectively. In material with lower δ-ferrite content, the lower values of the yield strength in the whole temperature range and the higher elongation of the specimens at T > 250 K have been revealed. Tensile strength and stages of plastic flow of the materials do not depend on the δ-ferrite fraction and its morphology, but the characteristics of strain-induced γ→α′ and γ→ε→α′ martensitic transformations and strain-hardening values are different for two types of the specimens. A new approach has been applied for the analysis of deformation behavior of additively fabricated Cr-Ni steels. Mechanical properties and plastic deformation of the dual-phase (γ + δ) steels produced through electron beam additive manufacturing have been described from the point of view of composite materials. Both types of the δ-ferrite inclusions, dendritic lamellae and globular coarse particles, change the stress distribution in the bulk of the materials during tensile testing, assist the defect accumulation and partially suppress strain-induced martensitic transformation.

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Viswanathan, V., and Nage Deepashri. "Influence of pH on Hydrogen Absorption in Duplex Stainless Steel." Advanced Materials Research 794 (September 2013): 592–97. http://dx.doi.org/10.4028/www.scientific.net/amr.794.592.

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With rising demands, oil and gas exploration of high-pressure high-temperature (HPHT) wells are increasing worldwide. Due to aggressiveness of HPHT environments, piping and equipments are constructed with high-strength corrosion resistant alloys (CRAs). Duplex stainless steel is one of the candidate alloys that offer high strength along with corrosion resistance. It possesses the advantages of both austenitic and ferritic stainless steels and hence, the name duplex or dual phase stainless steel. In order to control corrosion, cathodic protection is commonly being employed on the structures and equipment. Cathodic protection is accomplished by applying a direct current to the structure which causes the structure potential to change from the natural corrosion potential (Ecorr). The required cathodic protection current is supplied by sacrificial anode materials or by an impressed current system. Hydrogen embrittlement (HE) is an associated phenomenon, which results in the production of hydrogen ions, leading to its absorption in the protected metal and subsequent hydrogen embrittlement of metals and welds. To prevent this embrittlement, cathodic protection is closely studied in terms of finding the critical potential, pH, temperature etc. that does not cause hydrogen embrittlement. This paper describes the study carried out to find the role of pH on the absorption of hydrogen in Duplex Stainless steel. It has been observed that at a critical pH, hydrogen intake in the sample is very high, as compared to the pH below and above the critical pH. Critical pH observed for duplex stainless steel is a trade of between hydrogen evolution and absorption for given duplex structure.

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Maassen, S. F., H. Erdle, S. Pulvermacher, D. Brands, T. Böhlke, J. Gibmeier, and J. Schröder. "Numerical characterization of residual stresses in a four-point-bending experiment of textured duplex stainless steel." Archive of Applied Mechanics 91, no. 8 (March 19, 2021): 3541–55. http://dx.doi.org/10.1007/s00419-021-01931-3.

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AbstractThe resulting shapes in production processes of metal components are strongly influenced by deformation induced residual stresses. Dual-phase steels are commonly used for industrial application of, e.g., forged or deep-drawn structural parts. This is due to their ability to handle high plastic deformations, while retaining desired stiffness for the products. In order to influence the resulting shape as well as component characteristics positively it is important to predict the distribution of phase-specific residual stresses which occur on the microscale of the material. In this contribution a comparative study is presented, where two approaches for the numerical simulation of residual stresses are applied. On the one hand a numerically efficient mean field theory is used to estimate on the grain level the total strain, the plastic strains and the eigenstrains based on macroscopic stress, strain and stiffness data. An alternative ansatz relies on a Taylor approximation for the grain level strains. Both approaches are applied to the corrosion-resistant duplex steel X2CrNiMoN22-5-3 (1.4462), which consists of a ferritic and an austenitic phase with the same volume fraction. Mean field and Taylor approximation strategies are implemented for usage in three dimensional solid finite element analysis and a geometrically exact Euler–Bernoulli beam for the simulation of a four-point-bending test. The predicted residual stresses are compared to experimental data from bending experiments for the phase-specific residual stresses/strains which have been determined by neutron diffraction over the bending height of the specimen.

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Torres, Cristian, María Sofía Hazarabedian, Zakaria Quadir, Roy Johnsen, and Mariano Iannuzzi. "The Role of Tungsten on the Phase Transformation Kinetics and its Correlation with the Localized Corrosion Resistance of 25Cr Super Duplex Stainless Steels." Journal of The Electrochemical Society 167, no. 8 (May 15, 2020): 081510. http://dx.doi.org/10.1149/1945-7111/ab90af.

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Ran, Qingxuan, Wei Peng, Yulai Xu, Jun Li, Xueshan Xiao, Haifeng Yu, and Laizhu Jiang. "Self-repairing behavior of oxidation diffusion layer and phase transformation mechanism during tensile test of 19Cr duplex stainless steels with various Mn content." Corrosion Science 90 (January 2015): 535–43. http://dx.doi.org/10.1016/j.corsci.2014.10.046.

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Wang, Zhenhua, Wenyuan Ma, and Chengming Wang. "Effect of Strain Rate on Hot Ductility of a Duplex Stainless Steel." Advances in Materials Science and Engineering 2019 (August 5, 2019): 1–6. http://dx.doi.org/10.1155/2019/6810326.

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Duplex stainless steels (DSSs) often have bad hot workability. In this study, specimens of 2205 DSS were hot tensioned over a strain rate range from 0.005 s–1 to 50 s–1 to examine the hot ductility. The crack morphology was observed, and the dependence of hot ductility on the strain rate was analyzed. From 0.005 s–1 to 0.5 s–1, both the total elongation and the reduction in area increased with the strain rate. The reduction in area exhibited a small decrease when the strain rate was greater than 0.5 s–1. More than 85% of cracks formed between the ferrite and austenite, and no less than 70% of crack tips propagated between the ferrite and austenite. When the strain rate was increased from 0.005 s–1 to 0.5 s–1, dynamic recrystallization was promoted in the austenite, and the number fraction of low-angle grain boundaries in the ferrite was improved. The higher strain rate reduced the difference between ferrite and austenite in hardness, which improved the hot ductility. For 2205 DDS, the suggested strain rate is 0.5 s–1 and above to avoid surface and edge cracking during hot forging or hot rolling. The findings will be of value for the understanding of hot ductility of DSSs and other dual-phase alloys.

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Li, Yu, Shaoxiong Zhong, Hao Luo, Chun Xu, and Xiaoshuai Jia. "Intermediate stacking fault and twinning induced cooperative strain evolution of dual phase in lean duplex stainless steels with excellent cryogenic strength-ductility combinations." Materials Science and Engineering: A 831 (January 2022): 142347. http://dx.doi.org/10.1016/j.msea.2021.142347.

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Payares-Asprino, Carolina. "Prediction of Mechanical Properties as a Function of Welding Variables in Robotic Gas Metal Arc Welding of Duplex Stainless Steels SAF 2205 Welds Through Artificial Neural Networks." Advances in Materials Science 21, no. 3 (September 1, 2021): 75–90. http://dx.doi.org/10.2478/adms-2021-0019.

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Abstract Dual-phase duplex stainless steel (DSS) has shown outstanding strength. Joining DSS alloy is challenging due to the formation of embrittling precipitates and metallurgical changes during the welding process. Generally, the quality of a weld joint is strongly influenced by the welding conditions. Mathematical models were developed to achieve high-quality welds and predict the ideal bead geometry to achieve optimal mechanical properties. Artificial neural networks are computational models used to address complex nonlinear relationships between input and output variables. It is one of the powerful modeling techniques, based on a statistical approach, presently practiced in engineering for complex relationships that are difficult to explain with physical models. For this study robotic GMAW welding process manufactured the duplex stainless steel welds at different welding conditions. Two tensile specimens were manufactured from each welded plate, resulting in 14 tensile specimens. This research focuses on predicting the yield strength, tensile stress, elongation, and fracture location of duplex stainless steel SAF 2205 welds using back-propagation neural networks. The predicted values of tensile strength were later on compared with experimental values obtained through the tensile test. The results indicate <2% of error between observed and predicted values of mechanical properties when using the neural network model. In addition, it was observed that the tensile strength values of the welds were higher than the base metal and that this increased when increasing the arc current. The welds’ yield strength and elongation values are lower than the base metal by 6%, ~ 9.75%, respectively. The yield strength and elongation decrease might be due to microstructural changes when arc energy increases during the welding.

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Perulli, Patrizia, Michele Dassisti, and Giuseppe Casalino. "Thermo-Mechanical Simulation of Hybrid Welding of DP/AISI 316 and TWIP/AISI 316 Dissimilar Weld." Materials 13, no. 9 (May 1, 2020): 2088. http://dx.doi.org/10.3390/ma13092088.

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In this paper, hybrid laser-MAG (metal active gas) welding of twinning-induced plasticity (TWIP) and dual-phase (DP) steels with austenitic stainless steel (AISI316) was simulated by means of the finite element method. A thermo-mechanical model, which uses a 3D heat sources, was developed using the software Simufact Welding. The calculated dimensions, shape and distortion of the weld were compared with the experimental results, thence the model was validated. The metallurgical transformations for the DP steel were evaluated using the continuous cooling transformation (CCT) diagram and the calculated cooling rate. The numerical model predicted accurately the shape of the molten pool, the thermal cycles as well as the geometrical distortion of the butt weld. Therefore, the numerical model showed a good reliability and its potential for further development.

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Rodríguez, M. P., J. F. Almagro, J. Botella, and P. Valerga. "Cinéticas de transformación de fases a 850 ÂºC de aceros inoxidables dúplex clásicos (2205 y 2507) y de uno nuevo de bajo contenido en níquel y alto en manganeso (DBNi)." Boletín de la Sociedad Española de Cerámica y Vidrio 43, no. 2 (April 30, 2004): 237–42. http://dx.doi.org/10.3989/cyv.2004.v43.i2.511.

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Reyes, Arturo, Irene Calliari, Emilio Ramous, Michela Zanellato, and Mattia Merlin. "Secondary Phases Precipitation in the 2510 Duplex Stainless Steel." MRS Proceedings 1242 (2009). http://dx.doi.org/10.1557/proc-1242-s4-58.

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ABSTRACTA lot of duplex and super duplex stainless steels are prone to secondary phases but with different sequence and kinetic which depend on the chemical composition and thermo-mechanical history of the steel. In this paper the results of secondary phase's determination in a welding grade 2510 duplex steel, heat treated at 850–1050°C for 3–30 min are presented. The precipitation stars at grain boundaries with a consistent ferrite transformation for short times. The noses of the TTP curves are at 1000°C (sigma phase) and at 900°C (chi phase) with a partial transformation of chi to sigma, as evidenced in 2205 and 2507 grades.

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Matsumoto, Minami, Ken Kimura, and Natsuko Sugiura. "The influence of high-temperature oxidation on the phase distribution of metal substrate in duplex stainless steel." Oxidation of Metals, July 19, 2021. http://dx.doi.org/10.1007/s11085-021-10068-1.

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AbstractDuplex stainless steels (DSSs), which consist of ferrite and austenite phases, are widely used owing to their high strength and good corrosion resistance. However, the oxidation behavior of DSSs is extremely complicated because they have dual phases. In this study, changes in the scale and the metal substrate during oxidation were investigated. UNS S32101 (Fe-21.5%Cr–5%Mn–1.5%Ni–0.3%Mo–0.22%N), which is a typical type of DSS, was annealed at 1473 K for up to 36 ks in air. The microstructure of UNS S32101 consisted of austenite/ferrite phases, the ratio of which was 50:50 at room temperature. After oxidation, Cr, Mn-oxide formed predominantly. The metal substrate beneath the scale changed mostly to ferrite. In the same region, depletion of Mn and N concentrations resulted. The decrease in Mn was due to the formation of Cr, Mn-oxide. In addition, it was revealed that N content of the metal substrate decreased due to the formation of N2 gas along with the depletion of Mn. It was assumed that the decrease in Mn and N, which are austenite-stabilized elements, led to an increase in ferrite in the depletion area of Mn and N. From this result, it was expected that the compositional changes in the Mn/N depletion area were caused by the oxidation of steel.

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Journal articles on the topic 'Phase transformation, Duplex Stainless Steels, Dual Phase Steels'

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