Production of Bulk Ultrafine Grained Steel through Severe Plastic Deformation

2010 ◽  
Vol 667-669 ◽  
pp. 583-588
Author(s):  
Mehdi Shaban Ghazani ◽  
Beitallah Eghbali
Keyword(s):  
Equal Channel Angular Pressing ◽  
Dynamic Strain ◽  
Final Size ◽  
Continuous Dynamic Recrystallization ◽  
Forward Extrusion ◽  
Angular Pressing ◽  
Element Simulation ◽  
Ultrafine Grained ◽  
Continuous Dynamic ◽  
Ultrafine Grained Steel

In the present research, a combined forward extrusion-equal channel angular pressing (FE-ECAP) was developed and used for production of bulk ultrafine grained steel in the high temperature conditions. In this method, two different deformation steps including forward extrusion and equal channel angular pressing takes place successively in a single die. The deformation process was performed at different deformation start temperatures (800, 930, and 1100 °C). In addition, 3D finite element simulation was used to predict the hot/warm deformation parameters such as strain and temperature variations within the samples during deformation. The results show that the EF-ECAP process is effective in refining the grains from initial size of 32 m to final size of 0.9 m after executing of extrusion and ECAP on as received samples. The main mechanisms of grain refinement were considered to be strain assisted transformation, dynamic strain-induced transformation, and continuous dynamic recrystallization.

Grain Refinement Mechanisms Oterative during Equal Channel Angular Pressing of Aluminium

2011 ◽  
Vol 702-703 ◽  
pp. 135-138
Author(s):  
Rampada Manna ◽  
N.K. Mukhopadhyay ◽  
G.V.S. Sastry
Keyword(s):  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Room Temperature ◽  
Lattice Rotation ◽  
Recrystallization Process ◽  
Continuous Dynamic Recrystallization ◽  
Angular Pressing ◽  
Subgrain Formation ◽  
Refinement Process ◽  
Continuous Dynamic

Grain refinement of aluminum deformed by equal channel angular pressing is strongly dependent on the amount of strain. The refinement process at low to high strain level involves elongation of the existing grains by shear deformation, their subdivision into bands and subgrain formation within bands, intersection of the bands during subsequent passes and finally conversion of the subgrains to grains by continuous dynamic recrystallization process. At room temperature the conversion of subgrains to grains takes place by progressive lattice rotation.

On the Influence of Mesh Size during Finite Element Simulation of Equal Channel Angular Pressing

2013 ◽  
Vol 773-774 ◽  
pp. 160-165
Author(s):  
Guan Yu Deng ◽  
C. Lu ◽  
Li Hong Su ◽  
Mao Liu ◽  
Pei Tang Wei ◽  
...  
Keyword(s):  
Finite Element ◽  
Equal Channel Angular Pressing ◽  
Texture Evolution ◽  
Mesh Size ◽  
Strain Condition ◽  
Angular Pressing ◽  
Element Simulation ◽  
Ultrafine Grained ◽  
Deformation Features ◽  
Ultrafine Grained Materials

Equal channel angular pressing (ECAP) has attracted a lot of interest due to its ability for fabrication of bulk ultrafine-grained materials. With the development of computer skills, the computer-aided methods become very important and useful in understanding the deformation mechanism of ECAP. In this study, the influence of mesh size during finite element simulations of ECAP has been examined based on the plane strain condition assumption. Four different meshes have been compared and these results indicate that Mesh 600 and Mesh 2400 fail to capture the deformation features of ECAP accurately. Large corner gaps develop in these two cases and the simulated strains are smaller than the analytical calculations. Similar results have been obtained between Mesh 6369 and Mesh 12000 and the predicted features of plastic deformation and texture evolution are consistent with the experimental results.

Microstructure Evolution in an Al-Cu-Mg-Ag Alloy during ECAP at 300°C

2011 ◽  
Vol 409 ◽  
pp. 41-46
Author(s):  
Marat Gazizov ◽  
Rustam Kaibyshev
Keyword(s):  
Dynamic Recrystallization ◽  
Equal Channel Angular Pressing ◽  
Microstructure Evolution ◽  
Solution Treatment ◽  
Total Strain ◽  
High Angle ◽  
Continuous Dynamic Recrystallization ◽  
Angular Pressing ◽  
Continuous Dynamic ◽  
Average Size

A novel Al-Cu-Mg-Ag alloy with small additions of zirconium and scandium was subjected to equal channel angular pressing (ECAP) by using route BC at 300°C to strains ranging from ~1 to ~12. Initially, the alloy was subjected to solution treatment followed by water quenching; subsequent overageing was carried out at 380°C for 3 h. It was shown that continuous dynamic recrystallization (CDRX) occurs during ECAP resulting in partially recrystallized structure; at a total strain of ~12, the portion of high-angle boundaries (HAB) attains 50 pct., average misorientation is ~25°. Crystallites having elongated shape and an average size of ~1 μm are evolved after a total strain of ~12.

Effect of Deformation Structure on Strength of a Low Alloyed Cu-Cr-Zr Alloy

2016 ◽  
Vol 879 ◽  
pp. 1332-1337 ◽  
Author(s):  
A. Morozova ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Strength Properties ◽  
Deformation Structure ◽  
Initial State ◽  
Continuous Dynamic Recrystallization ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Continuous Dynamic ◽  
Zr Alloy

The microstructure evolution and strength properties of a Cu-0.096%Cr-0.057%Zr alloy subjected to equal channel angular pressing (ECAP) at a temperature of 673 K via route BC to total strains of 1 to 4 were examined. The planar low-angle boundaries with moderate misorientations form within initial grains during the first ECAP passes. Upon further processing the misorientations of these boundaries progressively increase and the formation of new ultrafine grains occurs as a result of continuous dynamic recrystallization. Partially recrystallized ultrafine grained structure evolves at strains above 4. After straining to 4 the (sub) grain size attains 0.65 μm. The large plastic straining provides significant strengthening. The ultimate tensile strength increases from 190 MPa in the initial state to 420 MPa after 4 ECAP passes. A modified Hall-Petch analysis is applied to investigate the contribution of grain refinement and dislocation density to the overall strengthening.

Incremental Equal Channel Angular Pressing for Grain Refinement

2011 ◽  
Vol 674 ◽  
pp. 19-28 ◽  
Author(s):  
Andrzej Rosochowski ◽  
Lech Olejnik
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Equal Channel Angular Pressing ◽  
Angular Pressing ◽  
Process Implementation ◽  
University Of Technology ◽  
Element Simulation ◽  
Ultrafine Grained ◽  
Deformation Processes ◽  
The University

Creating a small amount of ultrafine grained metals by severe plastic deformation, for example using equal channel angular pressing, is possible in many research laboratories. However, industrial production of these materials is lagging behind because of the lack of industrially viable severe plastic deformation processes. One attempt to change this situation is based on the concept of incremental equal channel angular pressing developed by the University of Strathclyde and Warsaw University of Technology. The paper describes the path the researchers took to develop the process starting from finite element simulation, through tool design and process implementation, to material characterisation. Examples of various process configurations, which enable obtaining UFG bars, plates and sheets are given and possible future developments discussed.

Superplastic Behavior in Ultrafine-Grained Materials Produced by Equal-Channel Angular Pressing

2008 ◽  
Vol 579 ◽  
pp. 29-40 ◽  
Author(s):  
Cheng Xu ◽  
Megumi Kawasaki ◽  
Roberto B. Figueiredo ◽  
Zhi Chao Duan ◽  
Terence G. Langdon
Keyword(s):  
Equal Channel Angular Pressing ◽  
High Strain ◽  
Processing Method ◽  
Strain Rates ◽  
Bulk Materials ◽  
Superplastic Behavior ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials ◽  
Aluminum And Magnesium Alloys

Equal-channel angular pressing (ECAP) is a convenient processing method for refining the grain size of bulk materials to the submicrometer level. Metallic alloys processed by ECAP often exhibit excellent superplastic characteristics including superplasticity at high strain rates. This paper summarizes recent experiments designed to evaluate the occurrence of superplasticity in representative aluminum and magnesium alloys and in the Zn-22% Al eutectoid alloy.

Numerical Simulation of Microstructure Evolution in AZ31 Magnesium Alloy during Equal Channel Angular Pressing

2014 ◽  
Vol 609-610 ◽  
pp. 495-499
Author(s):  
Guo Cheng Ren ◽  
Xiao Juan Lin ◽  
Shu Bo Xu
Keyword(s):  
Finite Element ◽  
Magnesium Alloy ◽  
Equal Channel Angular Pressing ◽  
Microstructure Evolution ◽  
Element Model ◽  
Az31 Magnesium Alloy ◽  
Angular Pressing ◽  
Ecap Process ◽  
Element Simulation ◽  
3D Software

The microstructure and material properties of AZ31 magnesium alloy are very sensitive to process parameters, which directly determine the service properties. To explore and understand the deformation behavior and the optimization of the deformation process, the microstructure evolution during equal channel angular pressing was predicted by using the DEFORM-3D software package at different temperature. To verify the finite element simulation results, the microstructure across the transverse direction of the billet was measured. The results show that the effects strain and deformation temperatures on the microstructure evolution of AZ31 magnesium during ECAP process are significant, and a good agreement between the predicted and experimental results was obtained, which confirmed that the derived dynamic recrystallization mathematical models can be successfully incorporated into the finite element model to predict the microstructure evolution of ECAP process for AZ31 magnesium.

MULTI-SCALE FINITE ELEMENT SIMULATION OF SEVERE PLASTIC DEFORMATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1621-1626
Author(s):  
HYOUNG SEOP KIM
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Severe Plastic Deformation ◽  
Constitutive Model ◽  
Dislocation Cell ◽  
Ultrafine Grain ◽  
Angular Pressing ◽  
Element Simulation ◽  
Ultrafine Grain Size ◽  
Ultrafine Grained

The technique of severe plastic deformation (SPD) enables one to produce metals and alloys with an ultrafine grain size of about 100 nm and less. As the mechanical properties of such ultrafine grained materials are governed by the plastic deformation during the SPD process, the understanding of the stress and strain development in a workpiece is very important for optimizing the SPD process design and for microstructural control. The objectives of this work is to present a constitutive model based on the dislocation density and dislocation cell evolution for large plastic strains as applied to equal channel angular pressing (ECAP). This paper briefly introduces the constitutive model and presents the results obtained with this model for ECAP by the finite element method.

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