scholarly journals Combination of dynamic transformation and dynamic recrystallization for realizing ultrafine-grained steels with superior mechanical properties

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Lijia Zhao ◽  
Nokeun Park ◽  
Yanzhong Tian ◽  
Akinobu Shibata ◽  
Nobuhiro Tsuji
Keyword(s):  
Mechanical Properties ◽  
Dynamic Recrystallization ◽  
Dynamic Transformation ◽  
Ultrafine Grained ◽  
Superior Mechanical Properties

scholarly journals Microstructure and Mechanical Properties of a Cold-Rolled Ultrafine-Grained Dual-Phase Steel

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1399 ◽  
Author(s):  
Zhiyi Pan ◽  
Bo Gao ◽  
Qingquan Lai ◽  
Xuefei Chen ◽  
Yang Cao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dual Phase Steel ◽  
Uniform Elongation ◽  
Processing Route ◽  
Dual Phase ◽  
Dp Steel ◽  
Ultrafine Grained ◽  
Superior Mechanical Properties ◽  
Cold Rolled ◽  
New Processing

A new processing route to produce Ultrafine-Grained Dual-Phase steel has been proposed, involving cold-rolling and subsequent intercritical annealing of a fibrous ferrite–martensite starting structure. Ultrafine-grained DP (UFG-DP) steel with an average ferrite grain size of about ~2.7 μm and an average martensite island size of ~2.9 μm was achieved. Tensile testing revealed superior mechanical properties (the ultimate tensile strength of 1267 MPa and uniform elongation of 8.2%) for the new DP steel in comparison with the fibrous DP steels. The superior mechanical properties are attributed to the influence of microstructure refinement on the work-hardening and fracture behavior.

Development of an Ultrafine Grained Ferrite in a Low C-Mn Steel Intensely Deformed under Hot Torsion

2004 ◽  
Vol 467-470 ◽  
pp. 1271-1276
Author(s):  
G. Azevedo ◽  
Ronaldo Barbosa ◽  
Dagoberto Brandão Santos
Keyword(s):  
Mechanical Properties ◽  
Grain Sizes ◽  
Dynamic Transformation ◽  
Ultrafine Grained ◽  
Size And Morphology ◽  
Hot Torsion ◽  
Hot Rolled ◽  
Mn Steel ◽  
Ferrite Grain Size ◽  
Torsion Deformation

In the last years, several studies concerning ultra refinement of ferrite grains have been conducted using different experimental techniques (ECAP, ARB, HPT). The aim of all investigations was to provide an optmized relationship between mechanical properties and microstructure of steels. The present work, likewise, deals with strain induced dynamic transformation of ferrite. Samples of low C-Mn steel were intensely deformed in hot torsion aiming at the production of ultrafine grains of ferrite thereby enhancing the mechanical properties when compared to hot rolled products. After soaking during 5min at 900°C, the samples were quenched and then reheated and submitted to hot torsion deformation at temperatures of 700 and 740°C. The torsion schedule consisted of 7 isothermal passes leading to a total strain of ≈1, generating an ultrafine microstructure with grain sizes of the order of 1µm. The shape of stress-strain curves so obtained suggested that ferrite refinement occurred by dynamic recrystallization. The various constituents present in the microstructure as well as ferrite grain size and morphology were examined by optical and scanning electron microscopy. Microhardness tests were performed to evaluate mechanical properties.

Mechanical Behaviors of Ultrafine Grained Metallic Materials

2007 ◽  
Vol 124-126 ◽  
pp. 1325-1328
Author(s):  
Dong Hyuk Shin ◽  
Duck Young Hwang ◽  
Jung Yong Ahn ◽  
Kyung Tae Park ◽  
Yong Suk Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Coarse Grained ◽  
Metallic Materials ◽  
Room Temperature Ductility ◽  
Ultrafine Grained ◽  
Superior Mechanical Properties ◽  
Ultrafine Grained Materials ◽  
The Relationship

Ultrafine grained materials fabricated by severe plastic deformation exhibit both superior and inferior mechanical properties, as the prominent structural materials, compared to coarse grained counterparts. The superior mechanical properties are ultrahigh strength and exceptional ductility at high temperatures (i.e., superplasticity). The inferior mechanical properties are lack of strain hardenability and room temperature ductility. In this study, the relationship between microstructure and mechanical properties of ultrafine grained materials fabricated by severe plastic deformation is investigated in order to provide insight broadening their future applicability.

Metallic Nanoneedles Arrays for TEM Sample Preparation “Lift-Out”

2012 ◽  
Author(s):  
Romaneh Jalilian ◽  
David Mudd ◽  
Neil Torrez ◽  
Jose Rivera ◽  
Mehdi M. Yazdanpanah ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Sample Preparation ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Beam System ◽  
Transmission Electron ◽  
Nanoneedle Array ◽  
Superior Mechanical Properties ◽  
And Performance

Abstract The sample preparation for transmission electron microscope can be done using a method known as "lift-out". This paper demonstrates a method of using a silver-gallium nanoneedle array for a quicker sharpening process of tungsten probes with better sample viewing, covering the fabrication steps and performance of needle-tipped probes for lift-out process. First, an array of high aspect ratio silver-gallium nanoneedles was fabricated and coated to improve their conductivity and strength. Then, the nanoneedles were welded to a regular tungsten probe in the focused ion beam system at the desired angle, and used as a sharp probe for lift-out. The paper demonstrates the superior mechanical properties of crystalline silver-gallium metallic nanoneedles. Finally, a weldless lift-out process is described whereby a nano-fork gripper was fabricated by attaching two nanoneedles to a tungsten probe.

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