Orientation Relationships between the δ-ferrite Matrix in a Duplex Stainless Steel and its Decomposition Products: the Austenite and the χ and R Frank-Kasper Phases

2008 ◽  
pp. 479-480 ◽  
Author(s):  
A. Redjaïmia ◽  
T. Otarola ◽  
A. Mateo
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Ferrite Matrix ◽  
Orientation Relationships ◽  
Decomposition Products ◽  
Δ Ferrite

scholarly journals Proton Irradiation Effects on Hardness and the Volta Potential of Welding 308L Duplex Stainless Steel

Micromachines ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Baolong Jiang ◽  
Qunjia Peng ◽  
Zhijie Jiao ◽  
Alex Volinsky ◽  
Lijie Qiao
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Transition Region ◽  
Proton Irradiation ◽  
Test System ◽  
Kelvin Probe ◽  
Simulation Code ◽  
Volta Potential ◽  
Δ Ferrite ◽  
Close Relationship

308L welding duplex stainless steel has been irradiated at 360 °C with 2 MeV protons, corresponding to a dose of 3 dpa at the maximum depth of 20 μm. Microhardness of the δ-ferrite and austenite phases was studied before and after proton irradiation using in situ nanomechanical test system (ISNTS). The locations of the phases for indentations placement were obtained by scanning probe microscopy from the ISNTS. The hardness of the δ-ferrite had a close relationship with the vacancy distribution obtained from the Stopping and Range of Ions in Matter (SRIM) Monte Carlo simulation code. However, the hardness of the austenite phase in the maximum damage region (17–20 μm depth) from the SRIM simulation was decreasing sharply, and a hardness transition region (>20 μm and <55 μm depth) was found between the maximum damage region (17–20 μm depth) and the unirradiated region (>20 μm depth). However, the δ-ferrite hardness behavior was different. A hardness of the two phases increased on the irradiated surface and the interior due to different hardening mechanisms in the austenite and δ-ferrite phases after a long time high-temperature irradiation. A transition region (>20 μm and <55 μm depth) of the Volta potential was also found, which was caused by the deeper transfer of implanted protons measured by scanning Kelvin probe force microscopy.

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).

scholarly journals On the M23C6-Carbide in 2205 Duplex Stainless Steel: An Unexpected (M23C6/Austenite)—Eutectoid in the δ-Ferritic Matrix

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1340
Author(s):  
Abdelkrim Redjaïmia ◽  
Antonio Manuel Mateo Garcia
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Geometrical Model ◽  
The Other ◽  
M23c6 Carbide ◽  
Interface Plane ◽  
Orientation Relationships ◽  
Ferritic Matrix ◽  
Σ Phase ◽  
M23c6 Carbides

This study is focused on isothermal and anisothermal precipitation of M23C6 carbides from the fully ferritic structure of the (γ + δ) austenitic-ferritic duplex stainless steel X2CrNiMo2253, (2205). During isothermal heat treatments, small particles of K-M23C6 carbide precipitates at the δ/δ grain-boundaries. Their formation precedes γ and σ-phases, by acting as highly potential nucleation sites, confirming the undertaken TEM investigations. Furthermore, anisothermal heat treatment leads to the formation of very fine islands dispersed throughout the fully δ-ferritic matrix. TEM characterization of these islands reveals a particular eutectoid, reminiscent of the well-known (γ-σ)—eutectoid, usually encountered in this kind of steel. TEM and electron microdiffraction techniques were used to determine the crystal structure of the eutectoid constituents: γ-Austenite and K-M23C6 carbides. Based on this characterization, orientation relationships between the two latter phases and the ferritic matrix were derived: cube-on-cube, on one hand, between K-M23C6 and γ-Austenite and Kurdjumov-Sachs, on the other hand, between γ-Austenite and the δ-ferritic matrix. Based on these rational orientation relationships and using group theory (symmetry analysis), the morphology and the only one variant number of K-M23C6 in γ-Austenite have been elucidated and explained. Thermodynamic calculations, based on the commercial software ThermoCalq® (Thermo-Calc Software, Stockholm, Sweden), were carried out to explain the K-M23C6 precipitation and its effect on the other decomposition products of the ferritic matrix, namely γ-Austenite and σ-Sigma phase. For this purpose, the mole fraction evolution of K-M23C6 and σ-phase and the mass percent of all components entering in their composition, have been drawn. A geometrical model, based on the corrugated compact layers instead of lattice planes with the conservation of the site density at the interface plane, has been proposed to explain the transition δ-ferrite ⇒ {γ-Austenite ⇔ K-M23C6}.

scholarly journals Microstructure evaluation of UNS S32205 duplex stainless steel friction stir welds

2013 ◽  
Vol 66 (2) ◽  
pp. 187-191 ◽  
Author(s):  
Tiago F. A. Santos ◽  
Ricardo R. Marinho ◽  
Marcelo T. P. Paes ◽  
Antonio J. Ramirez
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Ferrite Matrix ◽  
Optical Scanning ◽  
Friction Stir ◽  
Microstructure Evaluation ◽  
Transmission Electron ◽  
Steel Welds

UNS S32205 duplex stainless steel welds were performed by friction stir welding (FSW). Advancing and retreating sides showed distinct characteristics in the welded joint. The advancing side shows the strongest grain refinement which is corroborated by microhardness measurements. The microstructure characterization was carried out by optical, scanning and transmission electron microscopy. The thermomechanically affected zone displays austenite islands deformed in a ferrite matrix. The stir zone (SZ) showed a fine recrystallized microstructure providing an outstanding increase of hardness associated with better corrosion performance. Transmission electron microscopy and corrosion tests have corroborated the absence of intermetallic phases on welded joints.

scholarly journals Problems of Ferrite Content Determination

2020 ◽  
Vol 64 (2) ◽  
pp. 150-158
Author(s):  
Bálint Bögre ◽  
István Mészáros
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Ferrite Content ◽  
Super Duplex Stainless Steel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Content Determination ◽  
Heat Treated ◽  
Δ Ferrite ◽  
Cold Rolled

In this work five different methods – AC magnetometer, DC magnetometer, Feritscope, EBSD and X-ray diffraction - were compared with each other. These methods were used to determine the δ-ferrite content of samples. The limits, disadvantages and advantages of the applied methods were analyzed. The tested material was 2507 type super-duplex stainless steel. The samples were cold rolled and heat treated to modify their ferrite content.

Embrittlement Fracture in a 17-4 PH Stainless Steel after Aging at 400°C

2005 ◽  
Vol 486-487 ◽  
pp. 241-244 ◽  
Author(s):  
Wei You ◽  
Jung Hun Lee ◽  
Soo Keun Shin ◽  
Byung Hak Choe ◽  
Ung Yu Paik ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Stainless Steel ◽  
Precipitation Hardening ◽  
Lath Martensite ◽  
Ferrite Matrix ◽  
Spherical Particles ◽  
Solution Treated ◽  
Transmission Electron ◽  
Δ Ferrite

The embrittlement fracture mechanism caused by microstructural evolution of 17-4 PH stainless steel at long term aging was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The solution treated specimen consists largely of lath martensite with a small fraction of elongated δ-ferrite. The spherical particles existed a little in the martensite matrix, while no precipitates were present in the δ-ferrite at the solution treated specimen as non-aging. The precipitation of Fe-Cu in the δ-ferrite causes the aged hardening after long term aging accormpanied by decreases in elongation and charpy V-notch energy absorption. The increased fraction of brittle fracture on the fractured surface by impact and tensile test reveals that the embrittlement of the 17-4 PH alloys during long term aging is mainly caused by the precipitation hardening in the δ-ferrite matrix.

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