scholarly journals Comparison of Impact Toughness in Simulated Coarse-Grained Heat-Affected Zone of Al-Deoxidized and Ti-Deoxidized Offshore Steels

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1783
Author(s):  
Henri Tervo ◽  
Antti Kaijalainen ◽  
Vahid Javaheri ◽  
Mohammed Ali ◽  
Tuomas Alatarvas ◽  
...  

The presence of acicular ferrite (AF) in the heat-affected zone (HAZ) of steels used offshore is generally seen as beneficial for toughness. In this study, the effects of varying fractions of AF (0–49 vol.%) were assessed in the simulated, unaltered and coarse-grained heat-affected zones (CGHAZ) of three experimental steels. Two steels were deoxidized, with one using Ti and the other using Al. The characterization was carried out by using electron microscopy, energy-dispersive X-ray spectrometry, electron backscatter diffraction and X-ray diffraction. The fraction of AF varied with the heat input and cooling time applied in the Gleeble thermomechanical simulator. AF was present in one of the Ti-deoxidized steels with all the applied cooling times, and its fraction increased with increasing cooling time. However, in other materials, only a small fraction (13–22%) of AF was present and only when the longest cooling time was applied. The impact toughness of the simulated specimens was evaluated using instrumented Charpy V-notch testing. Contrary to the assumption, the highest impact toughness was obtained in the conventional Al-deoxidized steel with little or no AF in the microstructure, while the variants with the highest fraction of AF had the lowest impact toughness. It was concluded that the coarser microstructural and inclusion features of the steels with AF and also the fraction of AF may not have been great enough to improve the CGHAZ toughness of the steels investigated.

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 406
Author(s):  
Samiha Saad ◽  
Zakaria Boumerzoug ◽  
Anne Laure Helbert ◽  
François Brisset ◽  
Thierry Baudin

The objective of this work is to study, on a copper wire, the effect of TiO2-nanoparticles on electrodeposited nickel. Both the microstructure and surface morphology (texture) of the coating were investigated. This deposit is obtained from baths of sulfated electroplating Watts. The Ni-TO2 composite coating is deposited at a temperature of 45 °C. The composite deposit is prepared by adding nanoparticles of TiO2 to the electrolyte. The characterization has been carried out by X-ray diffraction, scanning electron microscopy, microhardness measurements, and electron backscatter diffraction (EBSD). Vickers microhardness was used to characterize the mechanical properties of the electrodeposited nickel. The results showed the effects of the TiO2 on the composition, the surface morphology, and the hardness of the deposited layer. However, there was not an effect of TiO2 nanoparticles on texture.


2011 ◽  
Vol 11 (10) ◽  
pp. 4660-4666 ◽  
Author(s):  
Wolfgang Wisniewski ◽  
Carlos André Baptista ◽  
Matthias Müller ◽  
Günter Völksch ◽  
Christian Rüssel

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
D. Marušáková ◽  
C. Aparicio ◽  
R. Fukač

Abstract Alloy 800H is a candidate material for supercritical water-cooled reactors (SCWR), specifically for in-core components in Canadian-type SCWR, that will operate at a pressure of 25 MPa and a core temperature from 350 °C to 625 °C. To evaluate this, several exposures to supercritical water took place at 395 °C and 25 MPa in a supercritical water loop (SCWL). The duration of each exposure was 500, 150, and 1000 h. Scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD), in combination with Raman spectroscopy (RS) and X-ray diffraction (XRD), was used to evaluate the microstructure of alloy 800H after the exposures to supercritical water. All these methods confirmed the presence of magnetite and trevorite/chromite crystals, with a thickness of less than 1 μm, on the surface after each exposure. No significant change occurred after the second and third exposures. The matrix crystallography did not change during the exposures and demonstrated grain twinning with a grain size of 100–400 μm.


2016 ◽  
Vol 858 ◽  
pp. 147-150 ◽  
Author(s):  
Mojmír Meduňa ◽  
Thomas Kreiliger ◽  
Ivan Prieto ◽  
Marco Mauceri ◽  
Marco Puglisi ◽  
...  

The stacking faults (SFs) in 3C-SiC epitaxially grown on ridges deeply etched into Si (001) substrates offcut towards [110] were quantitatively analyzed by electron microscopy and X-ray diffraction. A significant reduction of SF density with respect to planar material was observed for the {111} planes parallel to the ridges. The highest SF density was found in the (-1-11) plane. A previously observed defect was identified as twins by electron backscatter diffraction.


2019 ◽  
Vol 52 (2) ◽  
pp. 415-427 ◽  
Author(s):  
T. Skippon ◽  
L. Balogh ◽  
M. R. Daymond

Two methods for measuring dislocation density were applied to a series of plastically deformed tensile samples of Zircaloy-2. Samples subjected to plastic strains ranging from 4 to 17% along a variety of loading paths were characterized using both electron backscatter diffraction (EBSD) and synchrotron X-ray line profile analysis (LPA). It was found that the EBSD-based method gave results which were similar in magnitude to those obtained by LPA and followed a similar trend with increasing plastic strain. The effects of microscope parameters and post-processing of the EBSD data on dislocation density measurements are also discussed. The typical method for estimating uncertainty in dislocation density measured via EBSD was shown to be overly conservative, and a more realistic method of determining uncertainty is presented as an alternative.


2008 ◽  
Vol 59 ◽  
pp. 86-91 ◽  
Author(s):  
Nele Van Caenegem ◽  
Kim Verbeken ◽  
Roumen H. Petrov ◽  
N.M. van der Pers ◽  
Yvan Houbaert

The shape memory behaviour of a Fe29Mn7Si5Cr based alloy has been investigated. Characterization of the martensitic transformation and the different structural constituents was performed using optical microscopy, X-ray diffraction (XRD) methods and electron backscatter diffraction (EBSD). The transformation temperatures and the shape recovery were determined by dilatometry on prestrained samples.


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