scholarly journals Stress-induced detwinning and martensite transformation in an austenite Ni–Mn–Ga alloy with martensite cluster under uniaxial loading

IUCrJ ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 366-372 ◽  
Author(s):  
Long Hou ◽  
Ying Niu ◽  
Yanchao Dai ◽  
Lansong Ba ◽  
Yves Fautrelle ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Electron Backscatter Diffraction ◽  
Uniaxial Loading ◽  
Compression Stress ◽  
Compression Axis ◽  
Comprehensive Understanding ◽  
Training Process ◽  
The Hierarchical Structure ◽  
Schmid Factor ◽  
Backscatter Diffraction

Stress-induced martensitic detwinning and martensitic transformation during step-wise compression in an austenite Ni–Mn–Ga matrix with a martensite cluster under uniaxial loading have been investigated by electron backscatter diffraction, focusing on the crystallographic features of microstructure evolution. The results indicate that detwinning occurs on twins with a high Schmid factor for both intra-plate and inter-plate twins in the hierarchical structure, resulting in a nonmodulated (NM) martensite composed only of favourable variants with [001]NM orientation away from the compression axis. Moreover, the stress-induced martensitic transformation occurs at higher stress levels, undergoing a three-stage transformation from austenite to a twin variant pair and finally to a single variant with increasing compressive stress, and theoretical calculation shows that the corresponding crystallographic configuration is accommodated to the compression stress. The present research not only provides a comprehensive understanding of martensitic variant detwinning and martensitic transformation under compression stress, but also offers important guidelines for the mechanical training process of martensite.

scholarly journals Novel −75°C SEM cooling stage: application for martensitic transformation in steel

Microscopy ◽  
2020 ◽  
Author(s):  
Kaneaki Tsuzazki ◽  
Motomichi Koyama ◽  
Ryosuke Sasaki ◽  
Keiichiro Nakafuji ◽  
Kazushi Oie ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Electron Backscatter Diffraction ◽  
Dislocation Slip ◽  
In Situ Observation ◽  
Contrast Imaging ◽  
Cooling Stage ◽  
Electron Channelling ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Abstract Microstructural changes during the martensitic transformation from face-centred cubic (FCC) to body-centred cubic (BCC) in an Fe-31Ni alloy were observed by scanning electron microscopy (SEM) with a newly developed Peltier stage available at temperatures to  −75°C. Electron channelling contrast imaging (ECCI) was utilized for the in situ observation during cooling. Electron backscatter diffraction analysis at ambient temperature (20°C) after the transformation was performed for the crystallographic characterization. A uniform dislocation slip in the FCC matrix associated with the transformation was detected at −57°C. Gradual growth of a BCC martensite was recognized upon cooling from −57°C to −63°C.

scholarly journals Decoupling the Impacts of Strain Rate and Temperature on TRIP in a Q&P Steel

JOM ◽  
2022 ◽  
Author(s):  
Christopher B. Finfrock ◽  
Diptak Bhattacharya ◽  
Brady N. L. McBride ◽  
Trevor J. Ballard ◽  
Amy J. Clarke ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Strain Rate ◽  
Strain Hardening ◽  
Electron Backscatter Diffraction ◽  
Dislocation Slip ◽  
Transformation Induced Plasticity ◽  
High Strain Rate Deformation ◽  
The Individual ◽  
Backscatter Diffraction ◽  
Strain Hardening Rate

AbstractThe individual effects of strain rate and temperature on the strain hardening rate of a quenched and partitioned steel have been examined. During quasistatic tests, resistive heating was used to simulate the deformation-induced heating that occurs during high-strain-rate deformation, while the deformation-induced martensitic transformation was tracked by a combination of x-ray and electron backscatter diffraction. Unique work hardening rates under various thermal–mechanical conditions are discussed, based on the balance between the concurrent dislocation slip and transformation-induced plasticity deformation mechanisms. The diffraction and strain hardening data suggest that the imposed strain rate and temperature exhibited dissonant influences on the martensitic phase transformation. Increasing the strain rate appeared to enhance the martensitic transformation, while increasing the temperature suppressed the martensitic transformation.

Shape Recovery and ε - γ Transformation in Fe29Mn7Si5Cr SMA

2008 ◽  
Vol 59 ◽  
pp. 86-91 ◽  
Author(s):  
Nele Van Caenegem ◽  
Kim Verbeken ◽  
Roumen H. Petrov ◽  
N.M. van der Pers ◽  
Yvan Houbaert
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Recovery ◽  
Electron Backscatter Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Backscatter ◽  
Shape Memory Behaviour ◽  
Backscatter Diffraction

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.

Effect of Local Texture on the Orange Peel Defect in St14 Steel Sheet

2005 ◽  
Vol 495-497 ◽  
pp. 167-172
Author(s):  
Sheng Quan Cao ◽  
Jin Xu Zhang ◽  
Jian Sheng Wu ◽  
Jia Guang Chen
Keyword(s):  
Slip System ◽  
Steel Sheet ◽  
Electron Backscatter Diffraction ◽  
Orange Peel ◽  
Phase Zone ◽  
Coarse Grains ◽  
Schmid Factor ◽  
Ebsd Technique ◽  
Backscatter Diffraction ◽  
St14 Steel

In this paper, the ‘orange peel’ defect in the surface range of the st14 steel sheet has been investigated using the electron backscatter diffraction (EBSD) technique. It has been found that the ‘orange peel’ defect in the st14 steel sheet was resulted from the local coarse grains which were produced during hot-rolling due to the critical deformation in dual-phase zone; During deep drawing, the coarse grains with {100}<001> microtexture can slip on the {112}<111> slip system to form bulging and yields orange peel defects, while the coarse grains with {112}<110> orientation do not form the defect as the Schmid factor of {112}<111> slip system in it equals zero.

scholarly journals Understanding the Machinability of Austempered Ductile Iron (ADI)

2018 ◽  
Vol 925 ◽  
pp. 311-317 ◽  
Author(s):  
Dika Handayani ◽  
Robert C. Voigt ◽  
Kathy Hayrynen
Keyword(s):  
Plastic Deformation ◽  
Martensitic Transformation ◽  
Severe Plastic Deformation ◽  
Ductile Iron ◽  
Cutting Tool ◽  
Electron Backscatter Diffraction ◽  
Austempered Ductile Iron ◽  
Finish Machining ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Guidelines for production milling, turning and drilling of the standard grades of austempered ductile irons (ADI) have been established. Electron Backscatter Diffraction (EBSD) characterization has clearly shown that severe plastic deformation in the machining-affected-zone, ahead of and beneath the cutting tool, will cause strain-induced martensitic transformation of the austenite in the ausferrite structure that inhibits machinability. This phenomenon is particularly of concern during finish machining where small depths of cut are strongly influenced by surface martensite from prior machining passes.

scholarly journals Effect of Ultrasonic Nanocrystal Surface Modification on the Microstructure and Martensitic Transformation of Selective Laser Melted Nitinol

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3068 ◽  
Author(s):  
C.A. Biffi ◽  
P. Bassani ◽  
M. Nematollahi ◽  
N. Shayesteh Moghaddam ◽  
A. Amerinatanzi ◽  
...  
Keyword(s):  
Surface Modification ◽  
Martensitic Transformation ◽  
Functional Properties ◽  
Electron Backscatter Diffraction ◽  
Scanning Calorimetry ◽  
Austenitic Phase ◽  
Production Route ◽  
Microhardness Profile ◽  
Novel Applications ◽  
Backscatter Diffraction

Nitinol has significant potential for biomedical and actuating-sensing devices, thanks to its functional properties. The use of selective laser melting (SLM) with Nitinol powder can promote novel applications aimed to produce 3D complex parts with integrated functional performances. As the final step of the production route, finishing processing needs to be investigated both for the optimization of the surface morphology and the limit alteration of the Nitinol functional properties. In this work, the effect of an advanced method of surface modification, ultrasonic nanocrystal surface modification (UNSM), on the martensitic transformation and microstructure of SLM built Ni50.8Ti49.2 (at.%) was investigated. Scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry indicated that the UNSM process can generate stress-induced martensite, at least partially suppressing the martensitic transformation. The microhardness profile indicates that the UNSM process can affect the mechanical properties of the SLMed Nitinol sample in a range of up to approximately 750 μm in depth from the upper surface, while electron backscatter diffraction analysis highlighted that the initial austenitic phase was modified within a depth below 200 μm from the UNSMed surface.

scholarly journals Crystallographic orientation relationships in the α→γ′ martensitic transformation in an Fe–Mn–Al–Ni system

2018 ◽  
Vol 51 (4) ◽  
pp. 990-997 ◽  
Author(s):  
Juan Manuel Vallejos ◽  
César Enrique Sobrero ◽  
Martina Ávalos ◽  
Javier Walter Signorelli ◽  
Jorge Alberto Malarría
Keyword(s):  
Martensitic Transformation ◽  
Electron Backscatter Diffraction ◽  
Parent Phase ◽  
Product Phase ◽  
Orientation Relationships ◽  
Transformation Mechanism ◽  
Thermally Activated ◽  
Type Transformation ◽  
Wide Range ◽  
Backscatter Diffraction

The Fe43.5Mn34Al15Ni7.5 (at.%) alloy exhibits outstanding pseudoelastic behaviour over a wide range of temperatures. This alloy undergoes an unusual martensitic transformation from a disordered body-centred cubic (α) parent phase to a face-centred cubic (γ′) product phase. In the present work, the orientations of the parent and product phases for quenched samples were analysed by electron backscatter diffraction. Bain, Kurdjumow–Sachs, Pitsch, Nishiyama–Wassermann and Greninger–Troiano orientation relationships between the parent and product phases were compared with experimental results. The Pitsch relationship appears to be the most suitable to describe the α→γ′ martensitic transformation. This result provides experimental support to the dislocation-based heterogeneous Bogers–Burgers type transformation mechanism. No indications of variant selection were detected in the thermally activated transformations.

scholarly journals Deformation-Induced Grain-Interior α Precipitation and β Texture Evolution during the β-Processed Forging of a Near-β Titanium Alloy

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1405
Author(s):  
Tomonori Kitashima ◽  
Lingjian Meng ◽  
Makoto Watanabe
Keyword(s):  
Slip System ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Texture Intensity ◽  
Α Phase ◽  
Schmid Factor ◽  
Lower Temperature ◽  
Backscatter Diffraction

The effect of grain-interior α precipitation on the β texture evolution of the near-β Ti-6246 alloy during through-transus forging was investigated in two-step sequential forgings. The microstructure and texture were analyzed using scanning electron microscopy, electron-backscatter diffraction, and X-ray diffraction. The previous β forging was performed at 1253 K at 0.01/s, while the subsequent forging in the (α + β) region was conducted at 1073 K at 0.01/s. The forging in the β region facilitated the penetration of the interior α phase into β grains and reduced the formation of grain boundary α. The {001} texture intensity increased during the forging in the single β region. By contrast, the increase in the {001} texture intensity was moderate at a lower temperature (1073 K) because the Schmid factor (SF) value of the {110}<111> slip system drastically decreased, but those of the {112}<111> and {123}<111> slip systems increased before α precipitation. During α precipitation for all β forging ratios, the {110}<111> slip system was activated, resulting in a lowering of the {001} texture intensity. The lower the forging temperature before interior α precipitation under a constant total forging ratio, the more the {001} texture intensity was suppressed in the final β texture, accompanied by interior α precipitation.

In Situ Observation on the Deformation Behavior of Primary α-Ti in a Textured Ti-6Al-4V

2020 ◽  
Vol 993 ◽  
pp. 365-373
Author(s):  
Yun Xi Liu ◽  
Wei Chen ◽  
Zhi Qiang Li ◽  
Liang Liang Liu ◽  
Dong Liu
Keyword(s):  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Local Texture ◽  
Slip Bands ◽  
Texture Characteristics ◽  
Schmid Factor ◽  
Dislocation Behavior ◽  
Different Strains ◽  
Backscatter Diffraction

The tensile deformation process and dislocation behavior of primary α-Ti of Ti-6Al-4V were studied by the in-situ tensile test combined with EBSD (electron backscatter diffraction). The initiation, evolution and distribution of dislocation slips at different strains were discussed. The results showed that the microtexture of the material had a significant influence on slip behavior. Typically, basal and prismatic <a> slips initiated first, but the dominant slip type was related to the local texture characteristics. Sometimes, the basal and prismatic <a> slips could still initiate when their Schmid factors were relatively low, while the pyramidal slips usually need a higher Schmid factor to initiate. With the increase of strain, the second slip system inside one grain was activated to accommodate the plastic deformation. When the deformation was localized in a specific microtextured region, basal <a> slips were dominant, but eventually the crack initiated from the <c+a> slip bands inside the grain.

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