scholarly journals Control of Laves Precipitation in a FeCrAl-based Alloy Through Severe Thermomechanical Processing

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2939
Author(s):  
Jiyun Zheng ◽  
Yuzhen Jia ◽  
Peinan Du ◽  
Hui Wang ◽  
Qianfu Pan ◽  
...  
Keyword(s):  
Thermomechanical Processing ◽  
Shear Bands ◽  
Rolling Direction ◽  
Heat Stability ◽  
Structure Type ◽  
Fecral Alloy ◽  
Cell Structures ◽  
The Matrix ◽  
Deformation Textures ◽  
Hot Rolled

In recent years, the development of nuclear grade FeCrAl-based alloys with enhanced accident tolerance has been carried out for light water reactor (LWR) fuel cladding to serve as a substitute for zirconium-based alloys. To achieve excellent microstructure stability and mechanical properties, the control of precipitation particles is critical for application of FeCrAl-based alloys. In this paper, the effect of thermomechanical processing on the microstructure and precipitation behavior of hot-rolled FeCrAl alloy plates was examined. After hot rolling, the FeCrAl alloy plates had typical deformation textures. The rolling direction (RD) orientation gradually rotated from <100> to <110> along with increasing reduction. Shear bands and cell structures were formed in the matrix, and the former acted as preferable nucleation sites for crystallization. Improved deformation helped to produce strain-induced precipitation. The plate with 83% reduction had the most homogeneous and finest precipitation particles. Identification results by TEM indicated that the Laves precipitation was of the Fe2Nb-type crystal structure type, with impurities including Mo, Cr, and Si. The plate with uniform Laves particles displayed favorable heat stability after a long period of aging at 800 °C. The microstructure evolution of the aged sample was also observed. The deformation microstructure and the strain-induced precipitation mechanism of FeCrAl alloys are discussed.

Shear Localization and Microstructure Evolution in AlMgMnEr Alloy during Dynamic Deformation

2014 ◽  
Vol 915-916 ◽  
pp. 638-642
Author(s):  
Jia Ming Yin ◽  
Bo Long Li ◽  
Zuo Ren Nie
Keyword(s):  
Strain Rate ◽  
Microstructure Evolution ◽  
Dynamic Deformation ◽  
Shear Bands ◽  
Rolling Direction ◽  
Boundary Spacing ◽  
The Matrix ◽  
Matrix Region ◽  
Localized Shear Deformation ◽  
Gleeble 3500

The dynamic mechanical property and microstructure evolution in localized shear deformation was investigated in the Al-5.6%Mg-0.75%M-0.25%Er alloy cold rolled to 80% reduction by using Gleeble 3500 compression at the strain rate of 0.01~500s-1. The results show that both a critical strain rate and strain were required for the formation of local shear band under high strain rate compression. The initial Lamellar Boundaries (LBs) in the matrix region are parallel to the rolling direction (RD), with average boundary spacing of 0.25μm; The LBs within the shear bands region have a angle of 20° with RD, whose boundary spacing is ranging from 0.1 to 0.2μm. The LBs gradually rotate to an angle of 20° with RD and finally become wavy shape during the dynamic deformation.

scholarly journals Quantitative assessment of microstructural inhomogeneity by thickness of hot-rolled plates made of cold-resistant low-alloy steel for Arctic applications

2020 ◽  
pp. 41-49
Author(s):  
A. A. Kazakov ◽  
D. V. Kiselev ◽  
O. V. Sych ◽  
E. I. Khlusova
Keyword(s):  
Volume Fraction ◽  
Thermomechanical Processing ◽  
Rolling Direction ◽  
Accelerated Cooling ◽  
Subgrain Structure ◽  
Plate Steel ◽  
Long Distance ◽  
Microstructural Heterogeneity ◽  
Hot Rolled ◽  
Rolled Plates

A technique to assess microstructural anisotropy assessing by the thickness of the plate steel based on the texture analysis of the image has been developed. This technique provides for the anisotropy assessment at two dimensional levels: in the short-distance and long-distance neighborhoods, which characterize the elongation along the rolling direction of fine and coarse structural constituents, respectively. The practical approval results of this technique in the study of the microstructural heterogeneity of ferritic-bainitic steels over the thickness of 25–70 mm hot-rolled plates have been presented. It has been shown that the proposed anisotropy criteria in combination with the volume fraction of coarse packet-block regions of lath bainite as well as regions of bainite without an internal developed subgrain structure adequately estimate the microstructural heterogeneity over the thickness of plate steel and can be used for a detailed interpretation of the two-stage thermomechanical processing technology with accelerated cooling including taking into account the metallurgical inheritance of the slab.

scholarly journals An Insight into Amorphous Shear Band in Magnetorheological Solid by Atomic Force Microscope

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4384
Author(s):  
Mohd Aidy Faizal Johari ◽  
Asmawan Mohd Sarman ◽  
Saiful Amri Mazlan ◽  
Ubaidillah U ◽  
Nur Azmah Nordin ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Shear Band ◽  
Shear Bands ◽  
Test Duration ◽  
Phase Imaging ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Matrix ◽  
Relaxation Stress ◽  
Band Deformation

Micro mechanism consideration is critical for gaining a thorough understanding of amorphous shear band behavior in magnetorheological (MR) solids, particularly those with viscoelastic matrices. Heretofore, the characteristics of shear bands in terms of formation, physical evolution, and response to stress distribution at the localized region have gone largely unnoticed and unexplored. Notwithstanding these limitations, atomic force microscopy (AFM) has been used to explore the nature of shear band deformation in MR materials during stress relaxation. Stress relaxation at a constant low strain of 0.01% and an oscillatory shear of defined test duration played a major role in the creation of the shear band. In this analysis, the localized area of the study defined shear bands as varying in size and dominantly deformed in the matrix with no evidence of inhibition by embedded carbonyl iron particles (CIPs). The association between the shear band and the adjacent zone was further studied using in-phase imaging of AFM tapping mode and demonstrated the presence of localized affected zone around the shear band. Taken together, the results provide important insights into the proposed shear band deformation zone (SBDZ). This study sheds a contemporary light on the contentious issue of amorphous shear band deformation behavior and makes several contributions to the current literature.

Microstructure and Texture Evolution in Nickel during Accumulative Roll Bonding

2016 ◽  
Vol 879 ◽  
pp. 454-458 ◽  
Author(s):  
Jia Qi Duan ◽  
Md Zakaria Quadir ◽  
Michael Ferry
Keyword(s):  
Grain Boundaries ◽  
Accumulative Roll Bonding ◽  
Texture Evolution ◽  
Shear Bands ◽  
Rolling Direction ◽  
Sample Surface ◽  
Deformation Texture ◽  
Roll Bonding ◽  
Equiaxed Grains ◽  
Electron Back Scattered Diffraction

Microstructure and texture evolution of commercially pure Ni processed by accumulative roll-bonding (ARB) up to eight cycles were studied using electron back scattered diffraction (EBSD). During ARB processing, the original coarse equiaxed grains were gradually transformed into refined lamellar grains along the rolling direction (RD). Shear bands started forming after three cycles. The fraction of low angle grain boundaries (LAGBs) increased after the first and second cycle because of orientation spreading within the original grains. However, their fraction decreased with the evolution of high angle grain boundaries (HAGBs) during subsequent deformations, until saturation was reached after six cycles. Overall, the typical deformation texture components (S, Copper and Brass) were enhanced up to six ARB cycles and then only Copper was further strengthened. At higher cycles a higher Copper concentration was found near sample surface than the interiors due to a high frictional shear of ARB processing.

scholarly journals Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing

2017 ◽  
Vol 62 (1) ◽  
pp. 321-326 ◽  
Author(s):  
J. Górka
Keyword(s):  
Thermomechanical Processing ◽  
Control Process ◽  
Base Material ◽  
Structural Defects ◽  
Accelerated Cooling ◽  
Internal Stresses ◽  
Mechanical Control ◽  
Thin Foils ◽  
Precipitation Processes ◽  
The Matrix

Abstract This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by dispersive (Ti,Nb)(C,N) precipitates (being between several and less than twenty nanometers in size). In arc welding, depending on a welding method and linear energy, an increase in the base material in the weld is accompanied by the increased concentration of hardening microagents in the weld. The longer the time when the base material remains in the liquid state, the greater the amount of microagents dissolved in the matrix. During cooling, such microagents can precipitate again or remain in the solution. An increase in welding linear energy is accompanied by an increase in the content of hardening phases dissolved in the matrix and, during cooling, by their another uncontrolled precipitation in the form of numerous fine-dispersive (Ti,Nb)(C,N) precipitates of several nm in size, leading to a dislocation density increase triggered by type 2 internal stresses.

Study on the Microstructure and Texture of Warm Rolled ZK60 Magnesium Alloy Sheet

2012 ◽  
Vol 557-559 ◽  
pp. 1344-1348
Author(s):  
Hong Mei Chen ◽  
Hua Shun Yu ◽  
Guang Hui Min ◽  
Yun Xue Jin
Keyword(s):  
Shear Bands ◽  
Rolling Direction ◽  
Rolling Process ◽  
Warm Rolling ◽  
Alloy Sheet ◽  
Rolling Temperature ◽  
Rolling Reduction ◽  
Basal Pole ◽  
Zk60 Alloy ◽  
Twin Roll

The microstructure and macrotexture of ZK60 alloy sheet were investigated through OM and XRD, which were produced by twin roll casting and sequential warm rolling. Microstructure of twin roll cast ZK60 alloy changed from dendrite structure to fibrous structure with elongated grains and high density shear bands along the rolling direction after warm rolling process at different rolling parameters. The density of shear bands increased with the decreasing of the rolling temperature, or the increasing of per pass rolling reduction. Dynamic recrystallization could be found during the warm rolling process at and above 350oC, and many fine grains could be found in the shear band area. The warm rolled ZK60 alloy sheet exhibited strong (0001) basal pole texture. The formation of the shear bands tends to cause the basal pole tilt slightly to the transverse direction after warm rolling. The intensity of (0001) pole figure increased with the decreasing of rolling temperature, or the increasing of per pass rolling reduction.

Structural Effects of Thermomechanical Processing on the Static and Dynamic Responses of Powder Metallurgy Fe-Mn-Si Based Shape Memory Alloys

2016 ◽  
Vol 97 ◽  
pp. 153-158 ◽  
Author(s):  
Elena Mihalache ◽  
Bogdan Pricop ◽  
Radu Ioachim Comăneci ◽  
Marius Gabriel Suru ◽  
Nicoleta Monica Lohan ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Structural Changes ◽  
Thermomechanical Processing ◽  
Mechanical Analysis ◽  
Dynamic Responses ◽  
Surface Areas ◽  
Specimen Holder ◽  
Hot Rolled

Fe-14Mn-6Si-9Cr-5Ni (wt. %) shape memory alloys (SMAs) were produced by powder metallurgy (PM) combined with Mechanical Alloying (MA). The specimens were pressed and sintered under Ar atmosphere from as blended powders as well as from mixtures of as blended and 10, 20, 30 and 40 vol. % MA’ed powders, respectively. The five groups of sintered specimens were hot-rolled, spark-erosion cut and solution treated at five temperatures (923, 1023, …, 1373K/ 300 s/ water). Tensile loading-unloading tests were performed in order to obtain stress-induced martensite at different pre-straining degrees. The static responses of the twenty five types of specimens were evaluated by means of the surface areas under unloading curve (E2) and between loading and unloading curves (E1) which were used for determining static internal friction, Q-1. The dynamic responses of the undeformed specimens were determined by Dynamic Mechanical Analysis (DMA) performed at room temperature with a three-point-bending specimen holder in strain sweep mode. The structure of the twenty five specimens was analyzed X-ray diffraction. The effects of MA fraction were correlated with static and dynamic responses via structural changes.

scholarly journals Measurement of the Anisotropic Dynamic Elastic Constants of Additive Manufactured and Wrought Ti6Al4V Alloys

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 638
Author(s):  
Ofer Tevet ◽  
David Svetlizky ◽  
David Harel ◽  
Zahava Barkay ◽  
Dolev Geva ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Elastic Constants ◽  
Electron Backscatter Diffraction ◽  
Mechanical Design ◽  
Rolling Direction ◽  
Micro Computed Tomography ◽  
Phase Layer ◽  
Anisotropic Elastic ◽  
Hot Rolled ◽  
Pulse Echo

Additively manufactured (AM) materials and hot rolled materials are typically orthotropic, and exhibit anisotropic elastic properties. This paper elucidates the anisotropic elastic properties (Young’s modulus, shear modulus, and Poisson’s ratio) of Ti6Al4V alloy in four different conditions: three AM (by selective laser melting, SLM, electron beam melting, EBM, and directed energy deposition, DED, processes) and one wrought alloy (for comparison). A specially designed polygon sample allowed measurement of 12 sound wave velocities (SWVs), employing the dynamic pulse-echo ultrasonic technique. In conjunction with the measured density values, these SWVs enabled deriving of the tensor of elastic constants (Cij) and the three-dimensional (3D) Young’s moduli maps. Electron backscatter diffraction (EBSD) and micro-computed tomography (μCT) were employed to characterize the grain size and orientation as well as porosity and other defects which could explain the difference in the measured elastic constants of the four materials. All three types of AM materials showed only minor anisotropy. The wrought (hot rolled) alloy exhibited the highest density, virtually pore-free μCT images, and the highest ultrasonic anisotropy and polarity behavior. EBSD analysis revealed that a thin β-phase layer that formed along the elongated grain boundaries caused the ultrasonic polarity behavior. The finding that the elastic properties depend on the manufacturing process and on the angle relative to either the rolling direction or the AM build direction should be taken into account in the design of products. The data reported herein is valuable for materials selection and finite element analyses in mechanical design. The pulse-echo measurement procedure employed in this study may be further adapted and used for quality control of AM materials and parts.

scholarly journals The Significant Impact of Carbon Nanotubes on the Electrochemical Reactivity of Mg-Bearing Metallic Glasses with High Compressive Strength

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2989 ◽  
Author(s):  
Lou ◽  
Cheng ◽  
Zhao ◽  
Misra ◽  
Feng
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Corrosion Resistance ◽  
Metallic Glasses ◽  
Fracture Strain ◽  
Amorphous Material ◽  
Shear Bands ◽  
The Matrix ◽  
Superior Mechanical Properties ◽  
Pressure Die Casting

Here, we elucidate the significant impact of carbon nanotubes (CNTs) on the electrochemical behavior of Mg-based amorphous composite materials that were reinforced with CNTs while using pressure die casting. The addition of 3 vol % CNTs led to an increase in the compressive strength of Mg-based amorphous material from 812 MPa to 1007 MPa, and the fracture strain from 1.91% to 2.67% in the composite. Interestingly, the addition of CNTs significantly contributed to the enhancement of corrosion resistance of Mg-based glass by ~30%. The superior mechanical properties are primarily related to the fact that the addition of CNTs hindered the growth of shear bands (cracks), while the high corrosion resistance is related to inferior wettability and the bridging effect between adherent corrosive oxide film and the matrix that provided enhanced corrosion resistance.

Structure and Mechanical Properties of Asymmetrically Rolled IF Steel Sheet

2010 ◽  
Vol 654-656 ◽  
pp. 1255-1258 ◽  
Author(s):  
Dmitry Orlov ◽  
Rimma Lapovok ◽  
László S. Tóth ◽  
Ilana B. Timokhina ◽  
Peter D. Hodgson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Steel Sheet ◽  
Rolling Direction ◽  
If Steel ◽  
Asymmetric Rolling ◽  
Cold Rolled ◽  
Hot Rolled ◽  
If Steel Sheet

As-received hot-rolled 5.6 mm thick IF steel sheet was symmetrically/asymmetrically cold rolled at room temperature down to 1.9 mm. The asymmetric rolling was carried out in monotonic (an idle roll is always on the same side of the sheet) and reversal (the sheet was turned 180º around the rolling direction between passes) modes. Microstructure, texture and mechanical properties were analysed. The observed differences in structure and mechanical properties were modest, and therefore further investigation of the effects of other kinds of asymmetry is suggested.

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