scholarly journals A Coupled EBSD/TEM Analysis of the Microstructure Evolution of a Gradient Nanostructured Ferritic/Martensitic Steel Subjected to Surface Mechanical Attrition Treatment

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 140 ◽  
Author(s):  
Wenbo Liu ◽  
Xiao Jin ◽  
Bo Zhang ◽  
Di Yun ◽  
Piheng Chen
Keyword(s):  
Grain Boundaries ◽  
Transition Zone ◽  
Microstructure Evolution ◽  
Electron Backscatter Diffraction ◽  
Surface Region ◽  
Surface Mechanical Attrition Treatment ◽  
Ultrafine Grain ◽  
Tem Analysis ◽  
Mechanical Attrition ◽  
Rafm Steel

Surface mechanical attrition treatment (SMAT) was performed on a reduced ferritic/martensitic (RAFM) steel to form a nanostructured (NS) layer on the surface of the sample. Both electron backscatter diffraction (EBSD) and TEM were used to investigate the microstructure evolution during SMAT. The experimental results showed that there were three different zones after SMAT: (i) The “ultrafine grain” (UFG) zone, observed at the top-most surface region, (ii) the “transition zone” in which the original grains were fragmented under the severe plastic deformation and (iii) the “deformed zone” in which the original grains were simply deformed. The average grain sizes increased rapidly with the increase of depth, while the Vickers hardness decreased with the increase of depth, and this phenomenon could be explained in terms of boundary strengthening and dislocation strengthening. The number fractions of medium-angle grain boundaries (MAGBs) and medium-high-angle grain boundaries (MHAGBs) in UFG zones were larger than those in the transition zone and the deformed zone. However, the number fraction of the low-angle grain boundaries (LAGBs) was extremely small in all the zones after SMAT, especially in the transition zone.

Interface Microstructure of Diffusion Bonded Fe3Al/Al with Ultrafine Grain Layer

2010 ◽  
Vol 667-669 ◽  
pp. 1171-1175
Author(s):  
Jiang Wei Ren ◽  
Dong Li ◽  
Ai Dang Shan
Keyword(s):  
Transition Zone ◽  
Dissimilar Materials ◽  
Surface Mechanical Attrition Treatment ◽  
Ultrafine Grain ◽  
Atom Diffusion ◽  
Ultrafine Grains ◽  
Mechanical Attrition ◽  
Bonded Joint ◽  
Deformed Layer ◽  
Wide Transition

The influence of ultrafine grains produced by severe plastic deformation technology on the weldability of Fe3Al and Al dissimilar materials was investigated. An ultrafine grain layer was produced on Fe3Al intermetallic compound by surface mechanical attrition treatment. Then the SMATed Fe3Al was diffusion bonded with 1060Al at 550°C for 90 min in the vacuum of 10-3 Pa. The microstructures of surface ultrafine grain layer and transition zone at the interface of SMATed-Fe3Al/Al joint were observed by scanning electron microscopy. The grain size of surface ultrafine grains was characterized by X-ray diffractometry. The elements distribution at the interface and the phase constituents of transition zone were measured by energy disperse spectroscopy. The results showed that a deformed layer about 10-20 μm wide and surface nanocrystallines about 35nm were produced after 15 min surface mechanical attrition. SMATed Fe3Al was well bonded with Al and 11-30 µm wide transition zone formed. The transition zone consisted of FeAl and FeAl3 phases. The surface nanocrystallines helped the atom diffusion and the formation of diffusion bonded joint with rough surface and lower pressure.

scholarly journals Effect of Deformation Structure and Annealing Temperature on Corrosion of Ultrafine-Grain Fe-Cr Alloy Prepared by Equal Channel Angular Pressing

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Muhammad Rifai ◽  
Motohiro Yuasa ◽  
Hiroyuki Miyamoto
Keyword(s):  
Grain Boundaries ◽  
Equal Channel Angular Pressing ◽  
Annealing Temperature ◽  
Surface Region ◽  
Passivation Layer ◽  
Ultrafine Grain ◽  
Deformation Structure ◽  
Early Stages ◽  
Angular Pressing ◽  
The Stability

The effect of the deformation structure and annealing temperature on the corrosion of ultrafine-grain (UFG) Fe-Cr alloys with 8 to 12% Cr prepared by equal channel angular pressing (ECAP) was investigated with particular emphasis on the stability of the passivation layer. Fe-Cr alloys were processed by ECAP using up to eight passes at 423 K by the Bc route, followed by annealing at temperatures of 473 to 1173 K for 1 h. Passivity appeared in all alloys as a result of ECAP, and the stability of the passivation layer was evaluated by anodic polarization measurements in a 1000 mol·m−3 NaCl solution. The stability of the passivation layer increased as the degree of deformation became more extensive with successive ECAP passes, and distinct escalation occurred with the formation of a UFG microstructure. In the early stages of annealing at moderate temperatures, the stability of the passivation layer deteriorated, although no visible grain growth occurred, and this effect increased monotonically with increasing annealing temperature. The high degree of stability of the passivation layer on UFG alloys following ECAP can be attributed to the large number of high-angle nonequilibrium grain boundaries, which may lead to Cr enrichment of the surface region. The deterioration of the passivation layer in the early stages of annealing may be attributed to a change in the grain boundaries to an equilibrium state. The present results show that the superiority of as-ECAPed materials of the Fe-Cr alloy to recovered ones by heat treatment can be achieved with 8–10% Cr as observed in 20% Cr.

Influence of Surface Mechanical Attrition Treatment Attrition Media on the Surface Contamination and Corrosion of Magnesium

CORROSION ◽  
10.5006/0763 ◽  
2012 ◽  
Vol 69 (6) ◽  
pp. 527-535 ◽  
Author(s):  
D. Fabijanic ◽  
A. Taylor ◽  
K.D. Ralston ◽  
M.-X. Zhang ◽  
N. Birbilis
Keyword(s):  
Grain Refinement ◽  
Surface Composition ◽  
Optical Emission ◽  
Surface Contamination ◽  
Grain Structure ◽  
Surface Mechanical Attrition Treatment ◽  
Ultrafine Grain ◽  
Surface Residual Stress ◽  
Mechanical Attrition ◽  
Steel Balls

Surface mechanical attrition treatment (SMAT) is a mechanical peening process used to generate ultrafine grain surfaces on a metal. SMAT was carried out on pure magnesium using different attrition media (zirconia [ZiO2], alumina [Al2O3], and steel balls) to observe the effect on microstructure, surface residual stress, surface composition, and corrosion. Surface contamination from SMAT was characterized using glow discharge optical emission spectroscopy (GDOES). The SMAT process produced a refined grain structure on the surface of Mg but resulted in a region of elemental contamination extending ~10 μm into the substrate, regardless of the media used. Consequently, SMAT-treated surfaces showed an increased corrosion rate compared to untreated Mg, primarily through increased cathodic kinetics. This study highlights the issue of contamination resulting from the SMAT process, which is a penalty that accompanies the significant grain refinement of the surface produced by SMAT. This must be considered if attempting to exploit grain refinement for improving corrosion resistance.

scholarly journals MICROSTRUCTURE EVOLUTION AND DEFORMATION FEATURE OF AZ31 MAGNESIUM ALLOY DURING SEVERE PLASTIC DEFORMATION

2012 ◽  
Vol 06 ◽  
pp. 503-508
Author(s):  
LI-FENG HOU ◽  
YING-HUI WEI ◽  
XUE-FENG SHU
Keyword(s):  
Surface Layer ◽  
Magnesium Alloy ◽  
Microstructure Evolution ◽  
Az31 Magnesium Alloy ◽  
Surface Mechanical Attrition Treatment ◽  
Nanostructured Surface ◽  
Deformation Feature ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Refinement Process

A nanostructured surface layer was produced on commercially AZ31 magnesium alloy using surface mechanical attrition treatment (SMAT). The microstructure evolution and deformation feature along the depth of the treated surface layer were characterized by transmission electron microscope (TEM) investigations. The grain refinement process, accompanied by an increase in the surface layer, involves: the onset of twins; the formation of microbands associated with the dislocation slipping; the subdivision of microbands into low angle grains and then highly disoriented polygonal submicronic grains, and further breakdown into randomly oriented nanograins with progression of dynamic recrystallization.

scholarly journals Thermal Stability and Mechanical Properties of Al-Zn and Al-Bi-Zn Alloys Deformed by ECAP

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2043
Author(s):  
Hailong Jia ◽  
Yinan Piao ◽  
Kaining Zhu ◽  
Chaoran Yin ◽  
Wenqiang Zhou ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Grain Boundaries ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Ultrafine Grain ◽  
Thermally Induced ◽  
Ultrafine Grains ◽  
Angular Pressing ◽  
Transmission Electron ◽  
Ultrafine Grain Structure

It is well known that ultrafine grained and nanocrystalline materials show enhanced strength, while they are susceptible to thermally induced grain coarsening. The present work aims to enhance the thermal stability of ultrafine Al grains produced by equal channel angular pressing (ECAP) via dynamically precipitation. Detailed characterization by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) has been carried out to reveal the microstructural evolution during both ECAP and post-ECAP annealing. After five passes of ECAP, both Al-8Zn and Al-6Bi-8Zn alloys show an ultrafine grain structure together with dynamic precipitated nanoscale Zn particles along grain boundaries. Upon annealing at 200 °C, ultrafine grains in the Al-8Zn and Al-6Bi-8Zn alloys show a remarkable thermal stability compared to the Al-8Bi alloy, which is mainly due to the presence of nanoscale Zn precipitates along grain boundaries. The present work reveals that nanoscale Zn particles have a positive effect on preserving the ultrafine grains during annealing, which is useful for the design of UFG Al alloys with improved thermal stability.

scholarly journals Low cycle fatigue of 316L stainless steel processed by surface mechanical attrition treatment (SMAT)

2018 ◽  
Vol 165 ◽  
pp. 15002
Author(s):  
Zhidan Sun ◽  
Jianqiang Zhou ◽  
Delphine Retraint ◽  
Thierry Baudin ◽  
Anne-Laure Helbert ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Cyclic Loading ◽  
316L Stainless Steel ◽  
Electron Backscatter Diffraction ◽  
Low Cycle Fatigue ◽  
Surface Mechanical Attrition Treatment ◽  
Cycle Fatigue ◽  
Microstructure Change ◽  
Cyclic Behaviour ◽  
Mechanical Attrition

In this work, the effect of surface mechanical attrition treatment (SMAT) on the cyclic behaviour of a 316L stainless steel under low cycle fatigue (LCF) is investigated. The LCF results are presented in the form of cyclic stress amplitude evolution for both untreated and SMATed samples. In order to better understand the microstructure change due to cyclic loading, electron backscatter diffraction (EBSD) is used to characterize the microstructure of the SMATed samples before and after fatigue tests. A microstructure gradient is highlighted for samples after SMAT from the top surface layer in nanocrystalline grains to the interior region non-affected by impacts. Under LCF loading, new slip systems are activated in the work hardened region, whereas no plastic slip is activated in the nanostructured layer. The residual stresses generated by SMAT are measured using X-ray diffraction (XRD), and their relaxations under cyclic loading are studied by taking into account the microstructure change. The cyclic behaviour of the samples in different material states is interpreted based on these investigations.

Electron Backscatter Diffraction and Transmission Kikuchi Diffraction Analysis of an Austenitic Stainless Steel Subjected to Surface Mechanical Attrition Treatment and Plasma Nitriding

2015 ◽  
Vol 21 (4) ◽  
pp. 919-926 ◽  
Author(s):  
Gwénaëlle Proust ◽  
Delphine Retraint ◽  
Mahdi Chemkhi ◽  
Arjen Roos ◽  
Clemence Demangel
Keyword(s):  
Stainless Steel ◽  
Surface Properties ◽  
Electron Backscatter Diffraction ◽  
Plasma Nitriding ◽  
Surface Mechanical Attrition Treatment ◽  
Material Surface ◽  
Mechanical Attrition ◽  
Electron Backscatter ◽  
Nanocrystalline Layer ◽  
Backscatter Diffraction

AbstractAustenitic 316L stainless steel can be used for orthopedic implants due to its biocompatibility and high corrosion resistance. Its range of applications in this field could be broadened by improving its wear and friction properties. Surface properties can be modified through surface hardening treatments. The effects of such treatments on the microstructure of the alloy were investigated here. Surface Mechanical Attrition Treatment (SMAT) is a surface treatment that enhances mechanical properties of the material surface by creating a thin nanocrystalline layer. After SMAT, some specimens underwent a plasma nitriding process to further enhance their surface properties. Using electron backscatter diffraction, transmission Kikuchi diffraction, energy dispersive spectroscopy, and transmission electron microscopy, the microstructural evolution of the stainless steel after these different surface treatments was characterized. Microstructural features investigated include thickness of the nanocrystalline layer, size of the grains within the nanocrystalline layer, and depth of diffusion of nitrogen atoms within the material.

scholarly journals Mechanical Property of Duplex Stainless Steel with Nanostructured Layer by Surface Mechanical Attrition Treatment

2011 ◽  
Vol 682 ◽  
pp. 123-130 ◽  
Author(s):  
Liu Chen ◽  
Xiao Lei Xu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Property ◽  
Stainless Steel ◽  
Tensile Test ◽  
Duplex Stainless Steel ◽  
Electron Backscatter Diffraction ◽  
Annealed Sample ◽  
Surface Mechanical Attrition Treatment ◽  
Mechanical Attrition ◽  
Deformed Layer

A grain size gradient layer material was produced by means of surface mechanical attrition treatment on a UNS S32304 duplex stainless steel. In this study, the mechanical property was characterized by tensile test, while microstructure was investigated by transmission electron microscopy, scanning electron microscopy and electron backscatter diffraction. The deformed layer enhanced both the yield strength and maximum strength with large ductility retained, as revealed by tensile test that the yield stress of 30 minutes processed sample was 702 MPa as compared with 454 MPa of as-annealed sample. The elongation to failure, however, decreased from 0.41 to 0.27.

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