scholarly journals Microstructure/Mechanical Characterization of Plasma Nitrided Fine-Grain Austenitic Stainless Steels in Low Temperature

Nitrogen ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 244-258
Author(s):  
Abdelrahman Farghali ◽  
Tatsuhiko Aizawa ◽  
Tomoaki Yoshino
Keyword(s):  
Microstructure Evolution ◽  
Stainless Steels ◽  
Nitrided Layer ◽  
Austenitic Stainless Steels ◽  
Uniaxial Tensile ◽  
Two Phase ◽  
Solute Content ◽  
Fine Grained ◽  
Applied Loading ◽  
Uniaxial Tensile Testing

Fine-grained austenitic stainless steels (FGSS) were plasma nitrided below 700 K to describe their microstructure evolution during the nitrogen supersaturation process and to investigate the post-stressing effect on the microstructure and mechanical properties of nitrided FGSS. Normal- and fine-grained AISI304 plates were nitrided at 623 K and 673 K to investigate the grain size effect on the nitrogen supersaturation process as well as the microstructure evolution during the nitriding process. Fine-grained AISI316 (FGSS316) wires were nitrided at 623 K to demonstrate that their outer surfaces were uniformly nitrided to have the same two-phase, refined microstructure with high nitrogen solute content. This nitrided FGSS316 wire had a core structure where the original FGSS316 core matrix was bound by the nitrided FGSS316 layer. The nitrided wire had higher stiffness, ultimate strength, and elongation in the uniaxial tensile testing than its un-nitrided wires. The core microstructure was refined and homogenized by this applied loading together with an increase of nitrided layer hardness.

scholarly journals Hydrogen-Assisted Fracture of Type 316L Tubing and Orbital Welds

2013 ◽  
Author(s):  
C. San Marchi ◽  
L. A. Hughes ◽  
B. P. Somerday ◽  
X. Tang
Keyword(s):  
Stainless Steels ◽  
Base Material ◽  
Austenitic Stainless Steels ◽  
Gaseous Hydrogen ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Testing ◽  
Type 316L ◽  
316L Austenitic Stainless Steel ◽  
Outside Diameter ◽  
Assisted Fracture

Austenitic stainless steels have been extensively tested in hydrogen environments. These studies have identified the relative effects of numerous materials and environmental variables on hydrogen-assisted fracture. While there is concern that welds are more sensitive to environmental effects than the non-welded base material, in general, there have been relatively few studies of the effects of gaseous hydrogen on the fracture and fatigue resistance of welded microstructures. The majority of published studies have considered welds with geometries significantly different from the welds produced in assembling pressure manifolds. In this study, conventional, uniaxial tensile testing was used to characterize tubing of type 316L austenitic stainless steel with an outside diameter of 6.35 mm. Additionally, orbital tube welds were produced and tested to compare to the non-welded tubing. The effects of internal hydrogen were studied after saturating the tubes and orbital welds with hydrogen by exposure to high-pressure gaseous hydrogen at elevated temperature. The effects of hydrogen on the ductility of the tubing and the orbital tube welds were found to be similar to the effects observed in previous studies of type 316L austenitic stainless steels.

Precipitation in Aged N-Containing Austenitic Stainless Steels

2007 ◽  
Vol 561-565 ◽  
pp. 2275-2278 ◽  
Author(s):  
Maribel L. Saucedo-Muñoz ◽  
Victor M. Lopez-Hirata
Keyword(s):  
Microstructural Evolution ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Solute Content ◽  
Interstitial Solute ◽  
Kinetics Of Precipitation ◽  
Kinetics Of

Three types of austenitic stainless steels JK2, JJ1 and JN1 were isothermally aged at temperatures from 873 to 1173 K for 10 to 1000 minutes in order to study the microstructural evolution. In general, the kinetics of precipitation for JN1 steel was faster than that of JJ1 steel, because of its higher interstitial solute content. The TTP diagrams showed that the intergranular precipitation of M23C6 and M2N preceded to the intragranular precipitation of M2N and M2N and η phase in JN1 and JJ1 steels, respectively.

Precipitation in Aged N-Containing Steels

2011 ◽  
Vol 172-174 ◽  
pp. 437-442
Author(s):  
Maribel L. Saucedo-Muñoz ◽  
Victor M. Lopez-Hirata
Keyword(s):  
Microstructural Evolution ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Solute Content ◽  
Interstitial Solute ◽  
Kinetics Of Precipitation ◽  
Kinetics Of

Three types of austenitic stainless steels JK2, JJ1 and JN1 were isothermally aged at temperatures from 873 to 1173 K for 10 to 1000 minutes in order to study the microstructural evolution. In general, the kinetics of precipitation for JN1 steel was faster than that of JJ1 steel, because of its higher interstitial solute content. The TTP diagrams showed that the intergranular precipitation of Cr23C6 and Cr2N preceeded to the intragranular precipitation of Cr2N and h phase in JN1 and JJ1 steels, respectively.

Improvement of Wear Resistances of AISI 316L Austenitic Stainless Steels by Anodic Nitriding

2012 ◽  
Vol 268-270 ◽  
pp. 269-274
Author(s):  
Yang Li ◽  
Liang Wang ◽  
Jiu Jun Xu ◽  
Ying Chun Shan
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
316L Stainless Steel ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Austenitic Stainless Steels ◽  
Strengthening Effect ◽  
Aisi 316L ◽  
Discharge System ◽  
Hardness Tester

The nitriding of AISI 316L stainless steels has been carried out at anodic potential in a space enclosed by an active screen that consists of two cylinders with different diameter. These two cylinders made up a hollow cathode in a discharge system. Nitriding experiments were carried out on AISI 316L stainless steel at 450°C for times ranging from 1 to 24h in ammonia atmosphere. The intensity of electron bombardment on the surface of sample was low due to the anodic sheath, the disadvantages attached to conventional plasma nitriding were completely avoided. The phase composition, the thickness and the surface topography of the nitrided layer, as well as its hardness, were investigated by X-ray diffraction, scanning electron microscopy and a micro-hardness tester. The surface microhardness values and the thickness of the hardened layers increased as the nitriding time increased. Tribology properties of the untreated and nitrided 316L stainless steel have been investigated using a ball-on-disc tribometer with AISI52100 ball as the counterface. The results showed wear resistance of the AISI 316L stainless steels were greatly increased by anodic nitriding, owing to the strengthening effect of expanded austenite formed in the modified surface layer.

Analyses of Texture and Deformation Mechanism in Fine-Grained Austenitic Stainless Steels by Electron Back Scatter Diffraction

2018 ◽  
Vol 941 ◽  
pp. 218-223
Author(s):  
Kyoichi Ishida ◽  
Taku Matsuo ◽  
Muneyuki Imafuku
Keyword(s):  
Phase Transformation ◽  
Stainless Steels ◽  
Tensile Deformation ◽  
Texture Evolution ◽  
Austenitic Stainless Steels ◽  
Plastic Instability ◽  
Electron Back Scatter Diffraction ◽  
Fine Grained ◽  
Α Phase ◽  
Work Hardening Rate

We investigated texture evolution features in fine-grained austenitic stainless steels (JIS-SUS304) under tensile deformation. Three kinds of fine-grained specimens having average grain sizes, d =0.5 μm, 2 μm and 9 μm were prepared. The mechanical properties and phase transformation behaviors of fine grained specimens were compared to those of commercially available SUS304 ( d =16 μm). Tensile test showed increase of yield and tensile strength and decrease of work hardening rate and significant martensitic phase transformation in earlier stage of deformation for 2 μm specimen. These results suggest that simultaneous progress of the dynamic recovery of dislocations in γ-phase and the evolution of harder α’-phase owe the elongation and hardening respectively in fine-grained specimen. From the result of texture analysis, the texture evolution process was different from for each specimen, although the final orientation was almost the same. At the plastic instability stage, an increase of {112}<111>γ phase and a decrease of {112}<113>α’ phase occurred simultaneously for fine-grained 2 μm specimen whereas the opposite tendency was observed for 16 μm specimen. Such a grain size dependence of texture affects an extra ductility of SUS304 at the latter stage of deformation.

scholarly journals Effect of thermo-mechanical processes on microstructure evolution in austenitic stainless steels

2019 ◽  
Vol 24 ◽  
pp. 110-117
Author(s):  
Giuseppe Napoli ◽  
Orlando Di Pietro ◽  
Giulia Stornelli ◽  
Andrea Di Schino
Keyword(s):  
Microstructure Evolution ◽  
Stainless Steels ◽  
Austenitic Stainless Steels
Sign in / Sign up

Export Citation Format

Share Document