Semi-Massive Nanocrystallised Composites: From the Process to Mechanical and Microstructural Investigations

2013 ◽  
Vol 762 ◽  
pp. 487-492 ◽  
Author(s):  
Laurent Waltz ◽  
Delphine Retraint ◽  
Arjen Roos
Keyword(s):  
Microstructural Characterization ◽  
Tensile Tests ◽  
Austenitic Steels ◽  
Surface Mechanical Attrition Treatment ◽  
Three Point Bending ◽  
Steel Sheets ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Refinement Mechanism ◽  
Duplex Process

The aim of the present study is first to describe an original process, the so called duplex process, whose feature is the coupling between the well-known SMAT (Surface Mechanical Attrition Treatment) and the traditional co-rolling. The first step of this process consists of SMA-Treatment of 316L stainless steel sheets to generate nanocrystalline layers on their top surfaces according to the grain refinement mechanism of austenitic steels which is well described in the literature. During the second step, three treated sheets are co-rolled at 550°C to obtain a semi-massive nanocrystallised multilayer structure with improved mechanical strength alternating nanocrystalline, transition and coarse grain layers. The second part of this work deals with the mechanical and the microstructural characterization of the as-obtained structures. Thus, sharp nanoindentation tests performed over the cross section of the laminates coupled with Transmission Electron Microscopy (TEM) confirm the presence of nanograins after the thermomechanical treatment. In addition, the enhanced yield strength demonstrated by tensile tests correlate well with the theoretical volume fractions of nanoand transition layers. The interface cohesion between the sheets is tested by three-point bending tests and the interface bonding is evaluated by microstructural observations.

scholarly journals Microstructural Investigation of Co-Rolled Nanocrystalline Stainless Steel Sheets

2011 ◽  
Vol 702-703 ◽  
pp. 127-130 ◽  
Author(s):  
Delphine Retraint ◽  
M. Zakaria Quadir ◽  
Wan Qiang Xu ◽  
Laurent Waltz ◽  
Michael Ferry
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Composite Structure ◽  
High Strength ◽  
Steel Plates ◽  
Surface Mechanical Attrition Treatment ◽  
Microstructural Investigation ◽  
Steel Sheets ◽  
Mechanical Attrition ◽  
Duplex Process

It is possible to produce a nanocrystalline, multilayered composite structure with enhanced mechanical properties by assembling three 316L surface nanostructured stainless steel plates by roll bonding. The Surface Mechanical Attrition Treatment (SMAT) was first used to generate nanocrystalline layers on the elementary plates so that their mechanical properties were improved. They were then assembled through co-rolling. A composite structure of nanocrystalline layers of high strength alternating with more ductile layers was obtained to achieve both high strength and ductility. Microscopy observations and EBSD measurements were carried out and the bonding interfaces were analysed in detail to explore the mechanisms involved during the SMAT/Co-rolling duplex process.

Microstructure and Properties of Surface Nanostructured Copper

2011 ◽  
Vol 328-330 ◽  
pp. 1606-1609
Author(s):  
Wan Ming Lin ◽  
Yin Hui Wei ◽  
Li Feng Hou
Keyword(s):  
Copper Plate ◽  
Surface Mechanical Attrition Treatment ◽  
Hardness Testing ◽  
Surface Layers ◽  
Materials Properties ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
The Matrix ◽  
Novel Method ◽  
Potentiodynamic Anodic Polarization

Surface nanocrystallization (SNC) is a novel method for improving materials properties. Nanostructured surface layers of about 20 μm thickness were produced in copper plate samples by means of surface mechanical attrition treatment (SMAT). The behaviors of the SMAT samples were investigated by using transmission electron microscopy (TEM), Vickers hardness testing and potentiodynamic anodic polarization tests. The experimental results showed that the longer the peening time was performed on the copper pate samples, the thicker the deformation layers formed. The microhardness results for the top surface layer of the copper plate sample are 1.723 GPa and 1.752 GPa for 45 and 60 min, respectively, which are about two times higher than that of the matrix. The primary passivate potential of nanocrystalline copper was more negative than that of coarse-grain copper.

Ultrasonic Surface Mechanical Attrition of Commercially Pure Ti to Induce Nanocrystalline Surface Layer

2010 ◽  
Vol 442 ◽  
pp. 152-157 ◽  
Author(s):  
M. Mansoor ◽  
J. Lu
Keyword(s):  
Pure Titanium ◽  
Nanocrystalline Structure ◽  
Surface Mechanical Attrition Treatment ◽  
X Ray Diffraction ◽  
Annealed Condition ◽  
X Ray ◽  
Commercially Pure ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Xrd And Tem

In the domain of incremental nanotechnology, surface mechanical attrition treatment is a technique which can transform superficial structure of a material to nanocrystalline without changing the chemical composition. This study is a part of the development and implementation of the technique by using ultrasonic vibrations. The material used is pure titanium in rolled and annealed condition. The nanocrystalline structure is characterized using X-ray diffraction (XRD), and transmission electron microscopy (TEM). The measured grain size is in the order of 5~60 nm. A correlation in the results of XRD and TEM is also discussed.

Nanostructured 316 Stainless Steel Prepared under Traction by Surface Mechanical Attrition Treatment

2009 ◽  
Vol 614 ◽  
pp. 201-206
Author(s):  
Xiao Fang Yang ◽  
Jian Lu
Keyword(s):  
Stainless Steel ◽  
Optical Microscope ◽  
Steel Sample ◽  
Surface Mechanical Attrition Treatment ◽  
Stainless Steel Sample ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Nanostructured Layer ◽  
Nanoindentation Measurement ◽  
Measurement Results

A nanostructured 316 austenitic stainless steel sample was prepared under traction using a new surface mechanical attrition treatment (SMAT) system. The microstructure of the surface layer of the SMATed sample was characterized using an optical microscope and transmission electron microscope (TEM). Microhardness on the cross-section was investigated by nanoindentation measurement. Results showed that a deeper nanostructured layer was obtained in comparison with that of the sample SMATed without traction.

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 Gradient Microstructure Design in Stainless Steel: A Strategy for Uniting Strength-Ductility Synergy and Corrosion Resistance

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2356
Author(s):  
Qiong He ◽  
Wei Wei ◽  
Ming-Sai Wang ◽  
Feng-Jiao Guo ◽  
Yu Zhai ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Strength ◽  
Back Stress ◽  
High Yield ◽  
Surface Mechanical Attrition Treatment ◽  
Steel Sheets ◽  
Mechanical Attrition ◽  
Gradient Microstructure ◽  
Nano Grains

Martensite transformation and grain refinement can make austenitic stainless steel stronger, but this comes at a dramatic loss of both ductility and corrosion resistance. Here we report a novel gradient structure in 301 stainless steel sheets, which enables an unprecedented combination of high strength, improved ductility and good corrosion resistance. After producing inter-layer microstructure gradient by surface mechanical attrition treatment, the sheet was annealed at high temperature for a short duration, during which partial reverse transformation occurred to form recrystallized austenitic nano-grains in the surface layer, i.e., introducing extra intra-layer heterogeneity. Such 3D microstructure heterogeneity activates inter-layer and inter-phase interactions during deformation, thereby producing back stress for high yield strength and hetero-deformation induced (HDI) hardening for high ductility. Importantly, the recrystallized austenitic nano-grains significantly ameliorates the corrosion resistance. These findings suggest an effective route for evading the strength–ductility and strength–corrosion tradeoffs in stainless steels simultaneously.

Surface Nanocrystallization of Zircaloy-4 by Surface Mechanical Attrition Treatment

2010 ◽  
Vol 658 ◽  
pp. 452-455 ◽  
Author(s):  
Cong Hui Zhang ◽  
Xiao Ge Duan ◽  
Lian Zhou ◽  
Xin Zhe Lan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Surface Hardness ◽  
Surface Mechanical Attrition Treatment ◽  
Dislocation Slip ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Average Grain Size ◽  
Mechanical Twins

A nanostructured surface layer was induced on zircaloy-4 by the method of surface mechanical attrition treatment (SMAT). X-ray diffraction and microhardness tester were applied to identify the average grain size and hardness of specimen processed for different duration, transmission electron microscopy and high-resolution transmission electron microscopy were adopted to observe the microstructure of specimen. The results showed that the surface hardness enhanced gradually and then stabilized with the processing duration increasing, while the average grain size declined gradually, to the minimum 20 nm at 15 min, then increased. The formation of nanocrystalline was due to the mechanical twins and dislocation slip.

scholarly journals Grain refinement at the nanoscale via mechanical twinning and dislocation interaction in a nickel-based alloy

2004 ◽  
Vol 19 (6) ◽  
pp. 1623-1629 ◽  
Author(s):  
N.R. Tao ◽  
X.L. Wu ◽  
M.L. Sui ◽  
J. Lu ◽  
K. Lu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Layer ◽  
Grain Refinement ◽  
Mechanical Twinning ◽  
Surface Mechanical Attrition Treatment ◽  
Dislocation Interaction ◽  
Inconel 600 ◽  
Transmission Electron ◽  
Refinement Mechanism

A nanostructured surface layer was formed on an Inconel 600 plate by subjecting it to surface mechanical attrition treatment at room temperature. Transmission electron microscopy and high-resolution transmission electron microscopy of the treated surface layer were carried out to reveal the underlying grain refinement mechanism. Experimental observations showed that the strain-induced nanocrystallization in the current sample occurred via formation of mechanical microtwins and subsequent interaction of the microtwins with dislocations in the surface layer. The development of high-density dislocation arrays inside the twin-matrix lamellae provides precursors for grain boundaries that subdivide the nanometer-thick lamellae into equiaxed, nanometer-sized grains with random orientations.

Thermal Stability of Nanocrystalline Ti6Al4V Produced by Surface Mechanical Attrition Treatment

2017 ◽  
Vol 898 ◽  
pp. 41-46
Author(s):  
Quan Tong Yao ◽  
Meng Nan Xing ◽  
Guang Lan Zhang ◽  
Wei Ping Tong
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Pure Titanium ◽  
Surface Mechanical Attrition Treatment ◽  
X Ray ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Nanocrystalline Layer ◽  
Thermal Stability Of ◽  
Scanning Electron

A pollution-free nanocrystalline layer was prepared on the surface of Ti6Al4V by surface mechanical attrition treatment (SMAT). The nanocrystalline samples were vacuum annealed at various temperatures and for different periods of time. The microstructure and thermal stability were characterized by X-ray (XRD), scanning electron microscopy (SEM) and, transmission electron microscopy (TEM). The results showed that the nanocrystalline Ti6Al4V presented a satisfactory thermal stability with the annealed temperature below 650°C. The critical growth temperature for nanocrystalline Ti6Al4V is 100°C higher than that for pure titanium.

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