scholarly journals Quantitative Description of Duplex Stainless Steels Microstructure Using Selective Etching

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1750
Author(s):  
Aleksandr Sergeevich Fedorov ◽  
Andrey Igorevich Zhitenev ◽  
Darya Andreevna Strekalovskaya ◽  
Aleksandr Aleksandrovich Kur ◽  
Alexey Aleksandrovich Alkhimenko
Keyword(s):  
Stainless Steels ◽  
Volume Fraction ◽  
Quantitative Description ◽  
Integrated Approach ◽  
Selective Etching ◽  
Duplex Stainless Steels ◽  
Parameters Estimation ◽  
Metallographic Analysis ◽  
Secondary Phases ◽  
Metallic Inclusions

The properties of duplex stainless steels (DSSs) depend on the ferrite–austenite ratio, on the content of secondary phases and on the contamination with non-metallic inclusions. To assess the quality of DSSs, it is necessary to use an integrated approach which includes controlling for the volume fraction, the morphology and the distribution of all phases and non-metallic inclusions. Samples of several grades of DSSs were obtained using various heat treatments, such as solution annealing and quenching from 1050 to 1250 °C to obtain different amounts of ferrite and to provoke annealing at 850 °C to precipitate σ-phase. As a result, a metallographic technique of phase analysis in DSSs based on selective etching and subsequent structure parameters estimation according to ASTM E1245 was developed. We demonstrated that the developed method of quantitative analysis based on selective etching and metallographic analysis according to ASTM E1245 allows us to obtaining much more accurate results, compared to the point count method described in ASTM E562 and to the XRD method.

scholarly journals Quantitative Description of the Microstructure of Duplex Stainless Steels Using Selective Etching

2021 ◽  
Vol 3 (1) ◽  
pp. 4
Author(s):  
Aleksandr Fedorov ◽  
Andrey Zhitenev ◽  
Darya Strekalovskaya ◽  
Aleksandr Kur
Keyword(s):  
Stainless Steels ◽  
Quantitative Description ◽  
Distribution Patterns ◽  
Selective Etching ◽  
Duplex Stainless Steels ◽  
Quantitative Phase Analysis ◽  
Solution Annealing ◽  
Secondary Phases ◽  
Σ Phase ◽  
Metallographic Technique

: The properties of duplex stainless steels (DSSs) depend on the ferrite–austenite ratio and on the contents of secondary phases. Therefore, it is necessary to control the volume fractions, morphologies, and distribution patterns of all phases. The phases in the samples were identified using thermodynamic modeling and scanning electron microscopy. Investigated specimens were obtained after different heat treatments, such as solution annealing and quenching from 1050 to 1250 °C to obtain different amounts of ferrite and annealing at 850 °C to precipitate the σ-phase. Therefore, a metallographic technique for assessing the phases in DSSs based on selective etching and subsequent analysis according to ASTM E 1245 was developed. It was shown that the developed method of quantitative analysis based on selective etching and metallographic assessment according to ASTM E 1245 allows obtaining much more accurate results compared to the proposed ASTM E 562 method, which correlates well with the XRD quantitative phase analysis.

Effect of Secondary Phases Precipitation on Corrosion Resistance of Duplex Stainless Steels

2016 ◽  
Vol 879 ◽  
pp. 1495-1500 ◽  
Author(s):  
Luca Pezzato ◽  
Mattia Lago ◽  
Katya Brunelli ◽  
Marco Breda ◽  
Enrico Piva ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Stainless Steels ◽  
Room Temperature ◽  
Volume Fraction ◽  
Secondary Phase ◽  
Duplex Stainless Steels ◽  
Secondary Phases ◽  
Critical Range ◽  
Pitting Corrosion Resistance ◽  
Equivalent Number

Duplex Stainless steels (DSS) are biphasic austeno-ferritic steels in which the best combination of mechanical and corrosion resistance properties is achieved for almost equal volume fraction of the phases. These steels are classified according to their pitting corrosion resistance, assessed by the PREN index (Pitting Resistance Equivalent Number) which, although qualitatively, is widely employed as comparison. The present work is aimed to study the pitting resistance of four DSS grades (SAF 2101, 2304, 2205 and 2507) in the as-received condition and after isothermal aging in the critical range 750°C-900°C, to highlight the effect of secondary phases precipitation on the corrosion behavior. The materials were potentiodynamically tested in artificial seawater (pH7) at room temperature and the corresponding Critical Pitting Temperatures (CPT) were determined according to ASTM G150. Secondary phase precipitation mainly affected the lean duplex grades whereas the high-alloyed DSS were more stable even if large precipitation occurred.

The Fatigue Properties of Duplex Stainless Steels: Role of Microstructure

2008 ◽  
Vol 378-379 ◽  
pp. 101-114 ◽  
Author(s):  
Jean Bernard Vogt
Keyword(s):  
Fatigue Resistance ◽  
Stainless Steels ◽  
Load Transfer ◽  
Volume Fraction ◽  
Low Cycle Fatigue ◽  
Fatigue Behaviour ◽  
Cyclic Softening ◽  
Duplex Stainless Steels ◽  
Fatigue Properties

The paper analyzes the role of microstructure on the low cycle fatigue behaviour of duplex stainless steels. The alloys are investigated in their as received condition and after ageing at 475°C. The fatigue resistance and the cyclic accommodation of these DSS are strongly controlled by the volume fraction of α and γ "phases which is related to the chemical composition in particular nitrogen. It is shown that DSS with a high fraction of austenite present a good combination of fatigue resistance and cyclic softening especially in the aged condition. The mutual interaction between ferrite and austenite referred to load transfer is beneficial for increasing the fatigue resistance. Alloying with nitrogen appears to be a promising way to master an optimised microstructure leading to high mechanical resistant DSS.

Measuring secondary phases in duplex stainless steels

JOM ◽  
2009 ◽  
Vol 61 (1) ◽  
pp. 80-83 ◽  
Author(s):  
I. Calliari ◽  
K. Brunelli ◽  
M. Dabalà ◽  
E. Ramous
Keyword(s):  
Stainless Steels ◽  
Duplex Stainless Steels ◽  
Secondary Phases

Effects of W substitution on the precipitation of secondary phases and the associated pitting corrosion in hyper duplex stainless steels

2012 ◽  
Vol 544 ◽  
pp. 166-172 ◽  
Author(s):  
Soon-Hyeok Jeon ◽  
Soon-Tae Kim ◽  
In-Sung Lee ◽  
Ji-Soo Kim ◽  
Kwang-Tae Kim ◽  
...  
Keyword(s):  
Pitting Corrosion ◽  
Stainless Steels ◽  
Duplex Stainless Steels ◽  
Secondary Phases

The Analysis and Research of Secondary Phases Generated during Isothermal Aging of Duplex Stainless Steels

2012 ◽  
Vol 193-194 ◽  
pp. 411-417 ◽  
Author(s):  
Kai Lin ◽  
Hong Qi Shi ◽  
Li Qun Ma ◽  
Yi Ding
Keyword(s):  
Stainless Steels ◽  
Isothermal Aging ◽  
Heat Treating ◽  
Duplex Stainless Steels ◽  
Secondary Phases ◽  
Factors Affecting ◽  
Σ Phase ◽  
Α Phase ◽  
The Right ◽  
Χ Phase

The properties and precipitation rules of secondary phases generated during isothermal aging of duplex stainless steels and factors affecting the precipitates were reviewed in this article. These secondary phases include carbides(M23C6,M7C3), nitrides(Cr2N,CrN) and intermetallic phases(σ-phase, χ-phase, Fe3Cr3Mo2Si2, R-phase, π-phase, α′-phase). With the right understanding about the phases, the aim is the suitable heat-treating processes would be chose to avoid the unfavorable influences of secondary phases.

Effects of Antibacterial Treatment Temperature on the Properties of Copper-Bearing Antibacterial Duplex Stainless Steels

2012 ◽  
Vol 486 ◽  
pp. 289-296 ◽  
Author(s):  
Hong Liang Xiang ◽  
Jin Chun Fan ◽  
Dong Liu ◽  
Pei Pei Guo
Keyword(s):  
Passive Film ◽  
Stainless Steels ◽  
Antibacterial Effect ◽  
Volume Fraction ◽  
Antibacterial Properties ◽  
Treatment Temperature ◽  
Antibacterial Treatment ◽  
Duplex Stainless Steels ◽  
The Matrix ◽  
The Stability

Antibacterial copper-rich phases such as ε-Cu were precipitated in copper-bearing antibacterial duplex stainless steels after antibacterial treatment. In this paper, the effects of antibacterial treatment on the corrosion resistance properties of copper-bearing antibacterial duplex stainless steels were investigated by electrochemical methods. The film-cover method was used to antibacterial tests.The results showed that as the antibacterial treatment temperature increased in the rang of 540~580 , the copper-rich precipitates grew faster and evolved from granular into rod-like. With the proportion of rod-like copper-rich phases in matrix increased, the resistant to pitting corrosion decreased and the positions of copper-rich phase precipitated were apt to become pitting nucleation source.The presence of ε-Cu and other copper-rich phases in passive film reduced the overall potential and passive film resistance, decreasing the stability of passive film. Antibacterial test showed that with the treatment temperature increased, the volume fraction and the uniformity of the distribution of copper-rich precipitates in the matrix first increased, then decreased, resulting in the changes in antibacterial properties of the steels, and 560 obtained the best antibacterial effect.

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