scholarly journals Grain Refinement Mechanism and Evolution of Dislocation Structure of Co–Cr–Mo Alloy Subjected to High-Pressure Torsion

2016 ◽  
Vol 57 (7) ◽  
pp. 1109-1118 ◽  
Author(s):  
Murat Isik ◽  
Mitsuo Niinomi ◽  
Huihong Liu ◽  
Ken Cho ◽  
Masaaki Nakai ◽  
...  
Keyword(s):  
High Pressure ◽  
Grain Refinement ◽  
Dislocation Structure ◽  
High Pressure Torsion ◽  
Refinement Mechanism

Microstructural Evolution and Grain Refinement in a Cu-Zr Alloy Processed by High-Pressure Torsion

2014 ◽  
Vol 783-786 ◽  
pp. 2635-2640 ◽  
Author(s):  
Jittraporn Wongsa-Ngam ◽  
Terence G. Langdon
Keyword(s):  
High Pressure ◽  
Grain Refinement ◽  
Microstructural Evolution ◽  
High Pressure Torsion ◽  
Electron Backscatter Diffraction ◽  
Grain Morphology ◽  
Grain Structure ◽  
Ultrafine Grain ◽  
Refinement Mechanism ◽  
Ultrafine Grain Structure

A copper alloy, Cu-0.1% Zr, was processed at room temperature by high-pressure torsion (HPT) in order to evaluate the microstructural evolution and grain refinement mechanism. Transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques were employed to measure the grain morphology, grain size distributions and the distribution of the misorientation angles. The results demonstrate that this processing procedure has a potential for producing an ultrafine-grain structure containing reasonably equiaxed grain with high-angle boundary misorientations. The grain refinement mechanism is primarily governed by dislocation activities.

scholarly journals Investigation of Grain Refinement Mechanism of Nickel Single Crystal during High Pressure Torsion by Crystal Plasticity Modeling

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 351
Author(s):  
Peitang Wei ◽  
Hao Zhou ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Wei Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Grain Refinement ◽  
Crystal Plasticity ◽  
High Pressure Torsion ◽  
Lattice Rotation ◽  
Deformation Method ◽  
Fine Grained ◽  
Nickel Single Crystal ◽  
Refinement Mechanism

The excellent properties of ultra-fine grained (UFG) materials are relevant to substantial grain refinement and the corresponding induced small grains delineated by high-angle grain boundaries. The present study aims to understand the grain refinement mechanism by examining the nickel single crystal processed by high pressure torsion (HPT), a severe plastic deformation method to produce UFG materials based upon crystal plasticity finite element (CPFEM) simulations. The predicted grain maps by the developed CPFEM model are capable of capturing the prominent characteristics associated with grain refinement in HPT. The evolution of the orientation of structural elements and the rotations of crystal lattices during the HPT process of the detected differently oriented grains are extensively examined. It has been found that there are mainly two intrinsic origins of lattice rotation which cause the initial single crystal to subdivide. The correlation between the crystallographic orientation changes and lattice rotations with the grain fragmentation are analyzed and discussed in detail based on the theory of crystal plasticity.

GRAIN REFINEMENT AND MICROSTRUCTURE EVOLUTION IN ALUMINUM A2618 ALLOY BY HIGH-PRESSURE TORSION

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Intan Fadhlina Mohamed ◽  
Seungwon Lee ◽  
Kaveh Edalati ◽  
Zenji Horita ◽  
Shahrum Abdullah ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Grain Refinement ◽  
Room Temperature ◽  
Rotation Speed ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Saturation Level ◽  
Microstructural Refinement ◽  
Average Grain Size

This work presents a study related to the grain refinement of an aluminum A2618 alloy achieved by High-Pressure Torsion (HPT) known as a process of Severe Plastic Deformation (SPD). The HPT is conducted on disks of the alloy under an applied pressure of 6 GPa for 1 and 5 turns with a rotation speed of 1 rpm at room temperature. The HPT processing leads to microstructural refinement with an average grain size of ~250 nm at a saturation level after 5 turns. Gradual increases in hardness are observed from the beginning of straining up to a saturation level. This study thus suggests that hardening due to grain refinement is attained by the HPT processing of the A2618 alloy at room temperature.

Application of High-Pressure Sliding for Grain Refinement of Al and Mg Alloys

2010 ◽  
Vol 667-669 ◽  
pp. 91-96 ◽  
Author(s):  
Kiyonari Tazoe ◽  
Shuji Honda ◽  
Z. Horita
Keyword(s):  
High Pressure ◽  
Strain Rate ◽  
Grain Refinement ◽  
High Pressure Torsion ◽  
Initial Strain Rate ◽  
Mg Alloys ◽  
Initial Strain ◽  
Mg Alloy ◽  
Al Alloy ◽  
Average Grain Size

An earlier study showed that high-pressure sliding (HPS) is effective for grain refinement of pure Al in a rectangular sheet form using the principle of high-pressure torsion. In this study, the HPS is applied for grain refinement of an Al-3%Mg-0.2%Sc alloy and an AZ61 Mg alloy. HPS was conducted under a pressure of 1 GPa with sliding distances of 10 to 30 mm at room temperature for the Al alloy and at 473 K for the Mg alloy The average grain size is ~300 nm for both the Al and Mg alloys, respectively. Tensile tests showed that a superplastic elongation of ~1500% is achieved in the Al-3%Mg-0.2%Sc alloy at 573 K with an initial strain rate of 3.3x10-3 s-1 and of ~600% in the AZ61 alloy at 573 K with an initial strain rate of 1x10-3 s-1.

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