scholarly journals Microstructural Control and Properties Optimization of Microalloyed Pipeline Steel

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1499
Author(s):  
Mohamed Soliman
Keyword(s):  
Electron Microscopy ◽  
Yield Strength ◽  
Strain Aging ◽  
Pipeline Steel ◽  
Processing Parameters ◽  
Strength Increase ◽  
Coiling Temperature ◽  
Transmission Electron ◽  
Lower Yield Strength ◽  
Physical Simulations

A series of physical simulations, with parameters resembling those of industrial rolling, were applied using a thermo-mechanical simulator on microalloyed bainitic pipeline steel to study the influence of varying the processing parameters on its microstructure evolution and mechanical properties. In this study, the austenitization temperature and roughing parameters were kept unchanged, whereas the parameters of the finishing stage were varied. The developed microstructures were studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is illustrated that selecting the appropriate cooling strategy (without altering the deformation schedule) can produce an optimized microstructure that breaks through the strength–ductility trade-off. Increasing the cooling rate after the finishing stage from 10 K·s−1 to 20 K·s−1 activated the microstructure refinement by effective nucleation of acicular ferrite and formation of finer and more dispersed martensite/austenite phase. This resulted in a remarkable enhancement in the ductility without compensating the strength. Furthermore, a pronounced strength increase with a slight ductility decrease was observed when selecting the appropriate coiling temperature, which is attributed to the copious precipitation associated with locating the coiling temperature near the peak temperature of precipitation. On the other hand, it was observed that the coiling temperature is the predominant parameter affecting the strain aging potential of the studied steel. Higher strain aging potentials were perceived in the samples with lower yield strength and vice versa, so that the differences in yield strength after thermo-mechanical treatments evened out after strain aging.

Characterization of spray-pyrolized superconducting YBaCuO thin films on single-crystal MgO by transmission electron microscopy

1990 ◽  
Vol 5 (8) ◽  
pp. 1605-1611 ◽  
Author(s):  
S. J. Golden ◽  
H. Isotalo ◽  
M. Lanham ◽  
J. Mayer ◽  
F. F. Lange ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Single Crystal ◽  
Processing Parameters ◽  
Transmission Electron ◽  
Film Substrate ◽  
Mgo Substrate

Superconducting YBaCuO thin films have been fabricated on single-crystal MgO by the spray-pyrolysis of nitrate precursors. The effects on the superconductive behavior of processing parameters such as time and temperature of heat treatment and film thickness were investigated. The superconductive behavior was found to be strongly dependent on film thickness. Films of thickness 1 μm were found to have a Tc of 67 K while thinner films showed appreciably degraded properties. Transmission electron microscopy studies have shown that the heat treatments necessary for the formation of the superconductive phase (for example, 950 °C for 30 min) also cause a substantial degree of film-substrate interdiffusion. Diffusion distances for Cu in the MgO substrate and Mg in the film were found to be sufficient to explain the degradation of the superconductive behavior in films of thickness 0.5 μm and 0.2 μm. From the concentration profiles obtained by EDS analysis diffusion coefficients at 950 °C for Mg into the YBaCuO thin film and for Cu into the MgO substrate were evaluated as 3 × 10−19 m2/s and 1 × 10−17 m2/s, respectively.

The Effect of Cryorolling on the Microstructure of Al-Cu-Mg Alloy

2016 ◽  
Vol 877 ◽  
pp. 188-193 ◽  
Author(s):  
Li Wei Quan ◽  
Wen Ning Mu ◽  
Lei Kang ◽  
Xiao Ma ◽  
Peng Han ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Yield Strength ◽  
Optical Microscopy ◽  
Room Temperature ◽  
Solution Treatment ◽  
Mg Alloy ◽  
Dislocation Loops ◽  
Transmission Electron

A precipitation hardenable Al-Cu-Mg alloy was cryorolled with liquid nitrogen followed solution treatment and then aged at 170 ̊C for different time. The microstructure was characterized by optical microscopy (OM) and transmission electron microscopy (TEM). Hardness and tensile strength were also tested. The dislocation loops in the cryorolled alloy are more than the room temperature rolled alloy. Meanwhile the hardness, yield strength and tensile strength are larger than the room temperature rolled alloy.

Slip Transition and Dislocation Structures in Off-Stoichiometric NiAl Single Crystals

1996 ◽  
Vol 460 ◽  
Author(s):  
R. Srinivasan ◽  
M. F. Savage ◽  
M. S. Daw ◽  
R. D. Noebe ◽  
M. J. Mills
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Yield Strength ◽  
Single Crystals ◽  
Compression Tests ◽  
Transmission Electron ◽  
Strength Curve ◽  
Slip Transition

ABSTRACTCompression tests have been performed on hard-oriented Ni-44A1 single crystals for several temperatures and strain levels. There is a slip transition from a<111> type slip to non-a<111> type slip which corresponds with the observation of yield points. Transmission electron microscopy studies provide evidence for decomposition of a<111> dislocations into a<101> and a<010> dislocations near the “knee” of the yield strength curve. The mechanism of this slip transition and the nature of the dislocation processes both below and above the “knee” are described.

TEM study of dislocation core configurations in Ni3(Al,l%Ta) deformed at high temperatures

1990 ◽  
Vol 48 (4) ◽  
pp. 474-475
Author(s):  
N. Baluc
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Yield Strength ◽  
Constant Strain Rate ◽  
Dislocation Core ◽  
Anomalous Increase ◽  
Weak Beam ◽  
Transmission Electron ◽  
Ordered Alloys ◽  
High Resolution Tem

The Ni3Al intermetallic compound of the ordered L12 structure with various alloying elements (such as Ta or Ti) reinforces most of the industrial superalloys which are designed for high temperature applications. Therefore, the understanding of its mechanical properties is of primary importance. The yield strength, measured in constant strain rate tests, exhibits an anomalous behaviour as a function of temperature: it increases up to a peak temperature above which it finally decreases. The anomalous increase has been extensively studied during the last 30 years, including weak-beam and high resolution transmission electron microscopy (TEM) observations and computer simulations. Numerous models have been proposed to explain this anomalous variation in which the structure of the dislocation core plays a fundamental role. A review of core effects on the plasticity of ordered alloys was given by Vitek (1985). In the present investigation, the Ni3(Al,l%Ta) phase was deformed at temperatures above the yield strength peak and the detailed core configurations of dislocations have been analyzed using weak-beam and high resolution TEM techniques.

Research on the Mechanism of Aging of Dual Phase Steel Produced by Continuous Annealing

2010 ◽  
Vol 97-101 ◽  
pp. 556-559 ◽  
Author(s):  
Hao Yu ◽  
Yong Lin Kang
Keyword(s):  
Electron Microscopy ◽  
Strain Aging ◽  
Room Temperature ◽  
Dual Phase Steel ◽  
High Strain ◽  
Continuous Annealing ◽  
Dual Phase ◽  
Transmission Electron ◽  
Aging Resistance ◽  
And Diffusion

The microstructure and properties of aging at room temperature of dual phase steel produced by continuous annealing were investigated by using mechanical property test, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). In order to know the mechanisms of aging of dual phase steel produced by this process, the relative theories of dissolution and diffusion of interstitials, dislocation and precipitation are proposed and discussed. From analysis, the results showed that dual phase steel produced by continuous annealing had high strain aging resistance after overaging.

scholarly journals Effect of Bainite to Ferrite Yield Strength Ratio on the Deformability of Mesostructures for Ferrite/Bainite Dual-Phase Steels

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5352
Author(s):  
Gui-Ying Qiao ◽  
Zhong-Tao Zhao ◽  
Xian-Bo Shi ◽  
Yi-Yin Shan ◽  
Gu Yu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Yield Strength ◽  
Strain Hardening ◽  
Pipeline Steel ◽  
Strain Hardening Exponent ◽  
Strength Increase ◽  
Dual Phase ◽  
Strength Ratio ◽  
Soft Phase ◽  
Deformation Compatibility

The strength and plasticity balance of F/B dual-phase X80 pipeline steels strongly depends on deformation compatibility between the soft phase of ferrite and the hard phase of bainite; thus, the tensile strength of ferrite and bainite, as non-negligible factors affecting the deformation compatibility, should be considered first. In this purely theoretical paper, an abstract representative volume elements (RVE) model was developed, based on the mesostructure of an F/B dual-phase X80 pipeline steel. The effect of the yield strength difference between bainite and ferrite on tensile properties and the strain hardening behaviors of the mesostructure was studied. The results show that deformation first occurs in ferrite, and strain and stress localize in ferrite prior to bainite. In the modified Crussard-Jaoul (C-J) analysis, as the yield strength ratio of bainite to ferrite (σy,B/σy,F) increases, the transition strain associated with the deformation transformation from ferrite soft phase deformation to uniform deformation of ferrite and bainite increases. Meanwhile, as the uncoordinated deformation of ferrite and bainite is enhanced, the strain localization factor (SLF) increases, especially the local strain concentration. Consequently, the yield, tensile strength, and yield ratio (yield strength/tensile strength) increase with the increase in σy,B/σy,F. Inversely, the strain hardening exponent and uniform elongation decrease.

Laser ablation of nanoparticles and nanoparticulate, thick Fe1.92Tb0.3Dy0.7 films

2010 ◽  
Vol 25 (9) ◽  
pp. 1733-1740 ◽  
Author(s):  
J. Ma ◽  
M.F. Becker ◽  
J.W. Keto ◽  
D. Kovar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Laser Ablation ◽  
Processing Parameters ◽  
Processing Conditions ◽  
Transmission Electron ◽  
Resistance To Oxidation ◽  
Mean Size ◽  
Scanning Electron

Two laser processes, flat plate ablation (FPA) and laser ablation of microparticle aerosols (LAMA), capable of producing nanoparticles and nanoparticulate thick films of Terfenol-D (Fe1.92Tb0.3Dy0.7) were investigated. The influence of processing parameters on the sizes, compositions, and morphologies of the nanoparticles produced using these processes were studied by transmission electron microscopy. The nanoparticles were used to deposit nanoparticulate films by supersonic impaction with thicknesses ranging from 4 to 50 μm, depending on processing conditions. The microstructures and properties of the films were studied using scanning electron microscopy and magnetometry. The LAMA process produced nanoparticles with a mean size and standard deviation (SD) of 8 to 10 nm ± 5 nm, depending on the type of gas used during synthesis. In contrast, nanoparticles produced using the FPA process exhibited a much broader size distribution varying from 5 to 150 nm and a much greater variation in compositions compared to the LAMA process. Films produced using LAMA also had lower levels of porosity compared to those produced using FPA as a result of the smaller, more uniform nanoparticles from which they were produced and the resulting higher impaction velocities. Compared to the FPA-produced films, the LAMA-produced films exhibited greater resistance to oxidation, higher magnetizations (13–15 emu/g versus 9–11 emu/g, depending on processing conditions) and lower coercivities (versus 41–59 Oe versus 80–110 Oe).

Improvement of Paint Hardening Response of a Novel Al-Mg-Si Alloy for Automotive Panel by Adding Zn and Pre-Ageing Matching

2014 ◽  
Vol 936 ◽  
pp. 1224-1228
Author(s):  
Zhi Hui Li ◽  
Li Zhen Yan ◽  
Yong An Zhang ◽  
Xi Wu Li ◽  
Feng Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Yield Strength ◽  
Aged Alloy ◽  
Artificial Ageing ◽  
Baking Process ◽  
Transmission Electron ◽  
Zn Addition ◽  
Average Grain Size ◽  
Back Scattering ◽  
Automotive Panel

In the present work, the microstructure and properties of a novel Al-0.90Mg-0.78Si alloy with Zn addition were investigated by electron back scattering diffraction (EBSD), high transmission electron microscopy (HREM), mechanical properties and Erichsen tests. The average grain size of the alloy after pre-ageing was about 20 μm. The yield strength and elongation of pre-aged alloy was 137 MPa and 30% respectively. The IE value of the alloy was 8.6 mm. After paint baking at 170 °C for 30 min, the increment of yield strength was about 100 MPa. GP(II) zones were formed in the alloy during paint baking process through adding Zn, which should play a very important role for improving paint hardening response. GP(II) zones and η ́ phases were formed after artificial ageing at 170 °C for 10 h.

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