scholarly journals Relationship of the Microstructure and Toughness of the Coarse Grain Heat-Affected Zone of TiNbV Microalloyed Steels Based on Electron Backscatter Diffraction Analysis

2021 ◽  
Author(s):  
Han Yan ◽  
Di Zhao ◽  
Tongfu Qi ◽  
Xuesong Leng ◽  
Kuijun Fu
Keyword(s):  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Microalloyed Steels ◽  
Coarse Grain ◽  
Welding Heat Input ◽  
Electron Backscatter ◽  
Backscatter Diffraction

AbstractThe microstructure evolution and impact toughness of the coarse grain heat-affected zone (CGHAZ) of TiNbV microalloyed steels were investigated by using a thermal simulation test. The samples were treated with various simulated welding thermal cycles. The phase constituents and grain sizes were analyzed by using electron backscatter diffraction analysis. The microstructure of the CGHAZ of the treated samples consisted of ferrite, acicular ferrite, pearlite, and bainite. The samples have a higher impact toughness under a lower welding heat input. This is because the microstructure of the CGHAZ is dominated by the higher volume fraction of the high-angle grain boundaries of acicular ferrites. The presence of bainite and coarsening grains are two key factors deteriorating the toughness of the CGHAZ of TiNbV microalloyed steels. The volume fraction of bainite sharply increased as the welding heat input increased, leading to a decrease in the impact toughness of the CGHAZ. For a higher welding heat input, both the severe coarsening of the grain size and a higher bainite content would result in poor impact toughness.

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 ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Heat Affected Zone ◽  
Electron Backscatter Diffraction ◽  
Cooling Time ◽  
Coarse Grained ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
The Impact

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.

EBSD Characterization of Pure Iron Deformed by ECAE

2010 ◽  
Vol 638-642 ◽  
pp. 1995-2000 ◽  
Author(s):  
Reny Angela Renzetti ◽  
M.J.R. Sandim ◽  
Hugo Ricardo Zschommler Sandim ◽  
K.T. Hartwig ◽  
Heide H. Bernardi ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Softening Mechanism ◽  
Resolution Electron ◽  
Mean Grain Size ◽  
Electron Backscatter ◽  
Deformed State ◽  
The Mean ◽  
Backscatter Diffraction

Polycrystalline iron was deformed by eight ECAE passes using the route Bc to a total strain of 9.2. After deformation the material was annealed at temperatures up to 800oC. Scanning electron microscopy (SEM) and high-resolution electron backscatter diffraction (EBSD) were used to characterize both deformed and annealed structures. In the as-deformed state, the mean grain size is 650 nm and the volume fraction of high angle boundaries (VHAB) is 56%. Upon annealing there is a pronounced softening above 300oC. At the beginning of recrystallization, at about 400oC, the VHAB increases to 71%. The results indicate that discontinuous recrystallization is the main softening mechanism in severely deformed iron.

Mechanical Properties of the Heat Affected Zone of an X100 Grade Pipeline Steel

2013 ◽  
Vol 773-774 ◽  
pp. 795-802 ◽  
Author(s):  
Gui Ying Qiao ◽  
Ming Zheng ◽  
Yu Gu ◽  
Xiu Lin Han ◽  
Xu Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Pipeline Steel ◽  
Thermal Simulation ◽  
Peak Temperature ◽  
Coarse Grain ◽  
Fine Grained ◽  
Gleeble 3500

The microstructure and mechanical properties of an X100 grade pipeline steel were investigated by the thermal simulation tests performed on a Gleeble-3500 thermal simulator. The results show that the steel has excellent weldability. Even if the weld heat input gets 40 kJ mm-1, the low impact toughness energy in welding coarse grain heat affected zone (CGHAZ) is still higher than 200 J. Yet, an embrittlement zone emerges in inter-critical HAZ (ICHAZ) at the peak temperature of 750 °C, and the lowest strength appears in fine grained HAZ (FGHAZ) at the peak temperature of 950 °C. Moreover, the strength and toughness decrease with the increase of heat input.

scholarly journals Phase Analysis on Dual-Phase Steel Using Band Slope of Electron Backscatter Diffraction Pattern

2013 ◽  
Vol 19 (S5) ◽  
pp. 13-16 ◽  
Author(s):  
Jun-Yun Kang ◽  
Seong-Jun Park ◽  
Man-Been Moon
Keyword(s):  
Phase Analysis ◽  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Lattice Defect ◽  
Dual Phase ◽  
Dp Steel ◽  
Superior Result ◽  
Phase Discrimination ◽  
Electron Backscatter ◽  
Backscatter Diffraction

AbstractA quantitative and automated phase analysis of dual-phase (DP) steel using electron backscatter diffraction (EBSD) was attempted. A ferrite–martensite DP microstructure was produced by intercritical annealing and quenching. An EBSD map of the microstructure was obtained and post-processed for phase discrimination. Band slope (BS), which was a measure of pattern quality, exhibited much stronger phase contrast than another conventional one, band contrast. Owing to high sensitivity to lattice defect and little orientation dependence, BS provided handiness in finding a threshold for phase discrimination. Its grain average gave a superior result on the discrimination and volume fraction measurement of the constituent phases in the DP steel.

Equal-Channel Angular Pressing of NiAl

2010 ◽  
Vol 667-669 ◽  
pp. 39-44 ◽  
Author(s):  
Werner Skrotzki ◽  
Robert Chulist ◽  
Benoît Beausir ◽  
Matthias Hockauf
Keyword(s):  
Equal Channel Angular Pressing ◽  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Channel Angle ◽  
Brittle To Ductile Transition ◽  
Steel Jacket ◽  
Angular Pressing ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Scanning Electron

Equal-channel angular pressing (ECAP) was applied to polycrystalline NiAl at temperatures around the brittle-to-ductile transition temperature (BDTT). NiAl rods encapsulated in a steel jacket were ECAP-processed in a die with a channel angle of 120°. The microstructure and texture were characterized by electron backscatter diffraction with a scanning electron microscope. The volume fraction of the texture components typical for simple shear in the intersection plane of the channels changes in the range of the BDTT.

Effect of Phosphorus Contents on Texture and Grain Boundary Character for the Annealing High Strength Ti-IF Steels

2013 ◽  
Vol 652-654 ◽  
pp. 929-933 ◽  
Author(s):  
Xin Li Song ◽  
Kun Peng ◽  
P.P. Zhang ◽  
J.Y. Wu ◽  
J. Zhou ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Recrystallization Texture ◽  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Coincidence Site Lattice ◽  
High Strength ◽  
Fiber Texture ◽  
Grain Boundary Character ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The effect of phosphorus contents on texture and grain boundaries character for the high strength Ti-IF annealed for 120sec at 810oC are researched by electron backscatter diffraction technique（EBSD）. The recrystallization texture is approximated by the γ-fiber texture whose components are {111} and {111} orientation texture. The highest volume fraction of //ND texture is almost 80% for the sample containing 0.056%P. A large amount of coincidence site lattice(CSL) grain boundaries ∑3，∑5, ∑7，∑9，∑11 and ∑13b are obtained.

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