scholarly journals Investigation of Thermally Induced Deterioration Processes in Cold Worked SAF 2507 Type Duplex Stainless Steel by DTA

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 937
Author(s):  
Tibor Berecz ◽  
Éva Fazakas ◽  
Enikő Réka Fábián ◽  
Péter Jenei ◽  
János Endre Maróti
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
Σ Phase ◽  
Hardness Tests ◽  
Strain Induced Martensite ◽  
Kissinger Plot ◽  
Cold Worked ◽  
High Degree

Thermally induced deterioration processes were studied in cold worked (up to 60% deformation) SAF 2507 type super-duplex stainless steel (SDSS) by differential thermal analysis (DTA). DTA results revealed two transformations. Parent and inherited phases of these transformations were examined by other methods too, such as micro-hardness tests, optical metallography and X-ray diffraction (XRD). Finally, these transformations were identified as the formation of α’- and σ-phases. Formation of strain-induced martensite (SIM) and recrystallization were not experienced until 1000 °C, despite high degree of cold working. Activation energies of the σ-phase precipitation and α’-phase formation were determined from the Kissinger plot, through DTA measurements—they are 275 and 220 kJ/mol, respectively—in good agreement with the values found in the literature.

Effect of Secondary Phase Precipitation on Impact Toughness of Duplex Stainless Steel

2017 ◽  
Vol 889 ◽  
pp. 138-142 ◽  
Author(s):  
Amit Powar ◽  
Amol Gujar ◽  
Niketan Manthani ◽  
Vinayak Pawar ◽  
Rajkumar Singh
Keyword(s):  
Stainless Steel ◽  
Impact Toughness ◽  
Duplex Stainless Steel ◽  
Solution Treatment ◽  
Secondary Phase ◽  
Phase Precipitation ◽  
X Ray Diffraction ◽  
Σ Phase ◽  
Material Solution ◽  
The Impact

Duplex Stainless Steel (DSS) combines good mechanical strength and ductility with moderate to good corrosion resistance in a variety of environments. DSS are prone to the formation of various intermetallic phases (σ, χ, π, R), carbides (M23C6) and nitrides (Cr2N), when it exposed to temperatures lower than 1000°C. This study focuses on effect of secondary phase precipitation on impact toughness of ASTM A182 DSS. Cylindrical bar of DSS was open die forged in the temperature range of 1200-1050°C. After the forging, the bar was slow cooled by covering it with ceramic wool. This leads to the formation of σ phase at the ferrite/austenite interfaces and significantly reduced the impact toughness of the material. Solution treatment was done at different temperature and effect on toughness studied. The microstructural changes produced as consequences of the distinct test condition have been analyzed by means of optical and electron microscopy, X-ray diffraction.

Effect of recrystallization on degree of sensitization in nickel free austenitic stainless steel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sourabh Shukla ◽  
Awanikumar P. Patil ◽  
Ashlesha Kawale ◽  
Anand Babu Kotta ◽  
Inayat Ullah
Keyword(s):  
Stainless Steel ◽  
Thermal Aging ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
Austenitic Stainless Steels ◽  
Content Type ◽  
High Deformation ◽  
Strain Induced Martensite ◽  
Degree Of Sensitization ◽  
Cold Worked

Purpose Effect of grain size on degree of sensitization (DOS) was been evaluated in Nickel free steel. Manganese and nitrogen contained alloy is a Ni-free austenitic stainless steels (ASS) having type 202 grade. The main purpose of this investigation is to find the effect of recrystallization on the DOS of stainless steel after the thermo-mechanical processing (cold work and thermal aging). Design/methodology/approach In the present investigation, the deformation of 202 grade analyzed using X-ray diffraction (XRD) and microstructural testing. Optical microstructure of Ni-free ASS has been done for cold worked samples with thermally aged at 900°C_6 h. Double loop electrochemical potentiodynamic reactivation test used for findings of degree of sensitization. Findings Ni-free ASS appears to be deformed more rapidly due to its higher stacking fault energy which gave results in rapid transformation from strain induced martensite to austenite in form of recrystallized grains, i.e. it concluded that as cold work percentage increases more rapidly recrystallization occurs. XRD results also indicate that more fraction of martensite formed as percentage of CW increases but as thermal aging reverted those all martensite to austenite. So investigation gives the conclusion which suggests that with high deformation at higher temperature and duration gives very less DOS. Originality/value Various literatures available for 300 series steel related to the effect of cold work on mechanical properties and sensitization mechanism. However, no one has investigated the effect of recrystallization through thermomechanical processing on the sensitization of nickel-free steel.

Influence of Sigma Phase Precipitation on Pitting Corrosion of 2507 Super-Duplex Stainless Steel

2010 ◽  
Vol 658 ◽  
pp. 380-383 ◽  
Author(s):  
Ying Han ◽  
De Ning Zou ◽  
Wei Zhang ◽  
Jun Hui Yu ◽  
Yuan Yuan Qiao
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Ambient Temperature ◽  
Duplex Stainless Steel ◽  
Pitting Corrosion ◽  
Super Duplex Stainless Steel ◽  
Phase Precipitation ◽  
Pitting Potential ◽  
Σ Phase ◽  
Pitting Corrosion Resistance

Specimens of 2507 super-duplex stainless steel aging at 850°C for 5 min, 15 min and 60 min were investigated to evaluate the pitting corrosion resistance in 3.5% NaCl solution at 30°C and 50°C. The results are correlated with the microstructures obtained with different aging time. The precipitation of σ phase remarkably decreases the pitting corrosion resistance of the steel and the specimen aged for 60 min presents the lowest pitting potential at both 30°C and 50°C. With increasing the ambient temperature from 30°C to 50°C, the pitting potential exhibits a reduction tendency, while this tendency is less obviously in enhancing the ambient temperature than in extending the isothermal aging duration from 5 to 60 min. SEM analysis shows that the surrounding regions of σ phase are the preferable sites for the formation of corrosion pits which grew up subsequently. This may be attributed to the lower content of corrosion resistance elements in these regions formatted with σ phase precipitation.

scholarly journals Mechanical, structural and tribological properties of superaustenitic stainless steel submitted at solution heat treatment

2015 ◽  
Vol 20 (1) ◽  
pp. 160-168 ◽  
Author(s):  
Fabiana Cristina Nascimento Borges ◽  
Willian Rafael de Oliveira ◽  
Jonas Kublitski
Keyword(s):  
Stainless Steel ◽  
Austenitic Steel ◽  
Instrumented Indentation ◽  
X Ray Diffraction ◽  
Superaustenitic Stainless Steel ◽  
Space Group ◽  
X Ray ◽  
Σ Phase ◽  
Bulk Data ◽  
Corrosive Environments

The superaustenitic stainless steel presents several technological applications, mainly in corrosive environments. The different phase precipitation might alter some of its mechanical properties. Such alterations affect several factors, including the working life of the material under adverse working conditions. In this study, Instrumented Indentation techniques, Tribology and X-ray diffraction (XRD) were used to evaluate alterations in regions close to the surface. The parameters analyzed were: hardness and elastic modulus (instrumented indentation), friction coefficient (tribology) and structural alterations of the unit cell of the identified phases (XRD - Rietveld Refinement). All properties analyzed were compared with those of common austenitic steel. The presence of σ-phase (space group P42mnm) and γ-austenite (space group Fm3m) were detected. Data analyzed indicated that the presence of σ-phase caused small alteration in properties such as hardness in regions close to the surface. In the regions farther from the surface (material bulk) data can be compared to that of conventional austenitic steel.

Examination of the Orientation Relationships between the Main Phases of Duplex Stainless Steel by EBSD

2007 ◽  
Vol 537-538 ◽  
pp. 297-302
Author(s):  
Tibor Berecz ◽  
Péter János Szabó
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Stainless Steels ◽  
Electron Backscatter Diffraction ◽  
Duplex Stainless Steels ◽  
Alloying Elements ◽  
Orientation Relationships ◽  
Σ Phase ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Duplex stainless steels are a famous group of the stainless steels. Duplex stainless steels consist of mainly austenitic and ferritic phases, which is resulted by high content of different alloying elements and low content of carbon. These alloying elements can effect a number of precipitations at high temperatures. The most important phase of these precipitation is the σ-phase, what cause rigidity and reduced resistance aganist the corrosion. Several orientation relationships have been determined between the austenitic, ferritic and σ-phase in duplex stainless steels. In this paper we tried to verify them by EBSD (electron backscatter diffraction).

Effect of Pre-Shot Peening on Plasma Nitriding Kinetics of Austenitic Stainless Steel

2013 ◽  
Vol 634-638 ◽  
pp. 2955-2959 ◽  
Author(s):  
Lie Shen ◽  
Liang Wang ◽  
Jiu Jun Xu ◽  
Ying Chun Shan
Keyword(s):  
Stainless Steel ◽  
Surface Layer ◽  
Austenitic Stainless Steel ◽  
Shot Peening ◽  
Plasma Nitriding ◽  
Nitrogen Diffusion ◽  
X Ray Diffraction ◽  
304 Austenitic Stainless Steel ◽  
Strain Induced Martensite ◽  
Kinetics Of

The fine grains and strain-induced martensite were fabricated in the surface layer of AISI 304 austenitic stainless steel by shot peening treatment. The shot peening effects on the microstructure evolution and nitrogen diffusion kinetics in the plasma nitriding process were investigated by optical microscopy and X-ray diffraction. The results indicated that when nitriding treatments carried out at 450°C for times ranging from 0 to 36h, the strain-induced martensite transformed to supersaturated nitrogen solid solution (expanded austenite), and slip bands and grain boundaries induced by shot peening in the surface layer lowered the activation energy for nitrogen diffusion and evidently enhanced the nitriding efficiency of austenitic stainless steel.

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