Oxidation Parameters of Oxide Dispersion-Strengthened Steels in Supercritical Water

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Sami Penttilä ◽  
Iva Betova ◽  
Martin Bojinov ◽  
Petri Kinnunen ◽  
Aki Toivonen
Keyword(s):  
Supercritical Water ◽  
Diffusion Coefficients ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Depth Profiles ◽  
Bulk Substrate ◽  
Ods Alloys ◽  
Constituent Elements ◽  
Oxidation Parameters ◽  
And Diffusion

The kinetic parameters of oxidation of two oxide dispersion strengthened (ODS) alloys, PM2000 and MA956, in supercritical water (SCW) are evaluated using an updated model that assumes that the growth of the outer layer is governed by the transport of interstitial cations through the inner layer. The model is able to reproduce quantitatively the depth profiles of individual constituent elements in the inner and outer layers, as well as in the diffusion/transition layer of the alloy between the inner layer and the bulk substrate. The rate constants and diffusion coefficients decrease with time, indicating oxide layer restructuring.

Corrosion behavior of a 304-oxide dispersion strengthened austenitic stainless steel in supercritical water

2015 ◽  
Vol 67 (3) ◽  
pp. 264-270 ◽  
Author(s):  
S. F. Li ◽  
Z. J. Zhou ◽  
L. F. Zhang ◽  
L. W. Zhang ◽  
H. L. Hu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Corrosion Behavior ◽  
Supercritical Water ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion

scholarly journals Structure and mechanical properties of Fe–Ni–Zr oxide-dispersion-strengthened (ODS) alloys

2015 ◽  
Vol 467 ◽  
pp. 205-213 ◽  
Author(s):  
K.A. Darling ◽  
M. Kapoor ◽  
H. Kotan ◽  
B.C. Hornbuckle ◽  
S.D. Walck ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Ods Alloys

Dislocation Dynamics in Intermetallic and Oxide Dispersion Strengthened (ODS) Alloys

2000 ◽  
Vol 652 ◽  
Author(s):  
Ulrich Messerschmidta ◽  
Susanne Gudera ◽  
Dietrich Häusslera ◽  
Martin Bartscha
Keyword(s):  
Flow Stress ◽  
Dynamic Behaviour ◽  
Diffusion Processes ◽  
Rate Sensitivity ◽  
Oxide Dispersion Strengthened ◽  
Dislocation Dynamics ◽  
Oxide Dispersion ◽  
Intermetallic Alloys ◽  
Wide Range ◽  
Ods Alloys

ABSTRACTIn situ straining experiments in a high-voltage electron microscope allow the observation of the dynamic behaviour of individual dislocations. Such experiments have been performed on the intermetallic alloys NiAl, NiAl containing 0.2 at% Ta, α-TiAl, and MoSi2, and the oxide dispersion strengthened (ODS) alloys INCOLOY MA956 and INCONEL MA754 in a wide range of temperatures. There are many similarities in the dynamic behaviour of dislocations in the different materials. In the intermetallic alloys, a transition occurs between low temperature mechanisms and a viscous motion in the temperature range of the flow stress anomaly. The viscous motion at high temperatures can be explained by diffusion processes in the dislocation cores, whichcan be described by the theory of the Cottrell effect. The diffusing species can be quite different, alloying components or intrinsic point defects like vacancies and antisite defects existing in the lattice or only in the dislocation cores. If the dislocations are straight and crystallographically oriented during their motion, they may be dissociated and move by a succession of glide and conservative climb between the partial dislocations. In the ODS alloys, the dislocations move between the oxide particles again in a viscous way. The relation between the dislocation dynamics and the strain rate sensitivity of the flow stress is discussed for thedifferent materials.

Compressive Deformation Behavior of the Ferritic Oxide Dispersion Strengthened Alloys at Elevated Temperatures

2007 ◽  
Vol 353-358 ◽  
pp. 412-415
Author(s):  
Shou Jiang Qu ◽  
Jie Cai Han ◽  
Song He Meng
Keyword(s):  
Strain Rate ◽  
Elevated Temperatures ◽  
Solidus Temperature ◽  
Rate Sensitivity ◽  
Oxide Dispersion Strengthened ◽  
Homogeneous Distribution ◽  
Oxide Dispersion ◽  
Pinning Effect ◽  
Transmission Electron ◽  
Ods Alloys

The compressive properties characterized as a function of the true stress-strain response of the ferritic oxide dispersion strengthened (ODS) alloys, fabricated by mechanical alloying, were examined at strain rates ranging from 0.01 to 0.5s-1. Based on the differential scanning calorimeter (DSC) analysis, the solidus temperature of the ferritic ODS alloys is 1446oC. Therefore, the compressive temperatures were chosen to be from 1050oC to 1300oC. Transmission electron microscopy (TEM) observation is indicative of the homogeneous distribution of the nano-yttria particles with the granularity of 100~200nm, which may exert a strong pinning effect on subgrains. The results indicate that flow stress of the ferritic ODS alloys enhances with decreasing compressive temperature and increasing strain rate. Investigation of the strain rate sensitivity exponent and apparent activation energy of the ferritic ODS alloys has been carried out in detail.

Comparison of Fracture Toughness Properties of Advanced Ferritic ODS-Alloys Based on 0.2T C(T) Specimen Tests

2016 ◽  
Author(s):  
Charles C. Eiselt ◽  
David T. Hoelzer ◽  
Yann de Carlan ◽  
Hieronymus Hein ◽  
Marta Serrano ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Master Curve ◽  
Extrusion Direction ◽  
Oxide Dispersion Strengthened ◽  
Growth Direction ◽  
Initiation Toughness ◽  
Oxide Dispersion ◽  
Crack Growth Direction ◽  
Ods Alloys

Based on the good experiences gained by using small specimens made of ferritic RPV materials, the Master Curve fracture toughness approach was applied to determine the fracture mechanical properties of oxide dispersion strengthened (ODS-) materials. A ferritic ODS-alloy (Fe-14Cr-1W-Ti-Y2O3) has been produced through the powder metallurgical production path via hot extrusion and hot isostatic pressing (HIP). Optimized oxide dispersion strengthened (ODS)-alloys have a promising potential to meet the foreseen requirements of components in future Gen IV power plants due to their high creep strength and swelling resistance under irradiation at elevated operational temperatures. The fracture toughness was characterized with mini 0.2T C(T) specimens in different material orientations (R-L / L-R) in the ductile-brittle and upper shelf region in the un-irradiated state, accounting especially for the ODS-material’s anisotropy as one key effect of manufacturing. Despite all tests were performed in orientation required by ASTM standards E 1921 and E 1820 not all validity criteria (e.g. height of yield strength, evenness of the crack, admissible K during testing or admissible stable crack growth) were met by the ODS-material: consequently, a valid T0 value and a standard-compliant Master Curve could not be determined for the ODS-material in the transition region especially in the respective R-L orientation, also due to a comparably low fracture toughness over the whole evaluated temperature range. Promising fracture toughness properties were obtained in the crack growth direction perpendicular to the prior main deformation (extrusion) direction, where a KJQ value of 196 MPa√m at T = 22°C was measured. Within the ductile regime, only a JQ = J0.2BL technical initiation toughness value could be calculated and at T = 22°C, a comparably large JQ of 137kJ/m2 is obtained for specimens with crack growth direction perpendicular to the extrusion direction, while in extrusion direction the toughness is again low. In addition two further ODS-materials (14YWT and PM2000) were tested and compared to the alloys above. Non-conformances of ODS relating to the material requirements in ASTM standards E1921 and E1820 were finally detected and explained.

scholarly journals Vacuum Hot Pressing of Oxide Dispersion Strengthened Ferritic Stainless Steels: Effect of Al Addition on the Microstructure and Properties

2020 ◽  
Vol 4 (3) ◽  
pp. 93
Author(s):  
Dharmalingam Ganesan ◽  
Prabhukumar Sellamuthu ◽  
Konda Gokuldoss Prashanth
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Hot Pressing ◽  
Crucial Role ◽  
Ostwald Ripening ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Ferritic Stainless Steels ◽  
Oxide Particles ◽  
Ods Alloys

The present article investigates the fabrication of oxide dispersion strengthened (ODS) ferritic stainless steel (FSS). Three different ODS alloys with three different Al contents were fabricated, where the presence of Al-based oxides play a crucial role in determining the size of the oxide particles. Due to Ostwald ripening, the samples with Al show coarser oxide particles compared to the alloy without Al, which hampers the density of the fabricated samples and, hence, have reduced hardness levels. The present results suggest that the composition of the oxide present in ODS plays a crucial role in determining the properties of these samples.

scholarly journals High Temperature Cyclic Plastic Response of New-Generation ODS Alloy

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 804
Author(s):  
Alice Chlupová ◽  
Ivo Šulák ◽  
Jiří Svoboda
Keyword(s):  
High Temperature ◽  
Oxide Dispersion Strengthened ◽  
Step Test ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Oxide Dispersion ◽  
Ods Alloys ◽  
New Generation ◽  
Near Future ◽  
Ods Alloy

The very recently developed coarse-grained new-generation oxide dispersion strengthened (ODS) alloys containing 5 vol.% homogeneously distributed yttrium nano-precipitates seems to be a promising oxidation-resistant structural material for applications at temperatures above 1000 °C. The primary aim of the present paper is the introduction of the new-generation oxide dispersion strengthened (ODS) alloy and the first testing of its high temperature fatigue properties at 800 °C, concurrently demonstrating a novel and very efficient methodology by using an incremental fatigue step test. The successful application of the methodology motivates the authors to test the fatigue properties of new generation ODS alloys at 1000–1200 °C in the near future.

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