scholarly journals Experimental and Molecular Dynamic Study of Grain Refinement and Dislocation Substructure Evolution in HSLA and IF Steels after Severe Plastic Deformation

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1122
Author(s):  
Krzysztof Muszka ◽  
Dawid Zych ◽  
Paulina Lisiecka-Graca ◽  
Lukasz Madej ◽  
Janusz Majta
Keyword(s):  
New York ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Molecular Dynamic ◽  
Large Scale ◽  
Electron Backscatter Diffraction ◽  
Dislocation Substructure ◽  
Numerical Models ◽  
Microalloyed Steels ◽  
Dynamic Simulations

In this study, large-scale molecular dynamic simulations were performed to analyze the dislocation substructure interaction with various types of obstacles present in microalloyed steels during severe plastic deformation. Specifically, fully functional numerical models of the atomic upsetting test were developed, with particular emphasis on the presence of precipitates inside the microstructure grains. The obtained results compared with the microstructural tests, performed using Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscope (TEM) techniques, allowed for a more accurate assessment of the microstructure refinement mechanisms by means of the in-situ recrystallization effect in the deformed samples subjected to the multi-axis compression using the MaxStrain system (Dynamic Systems Inc., New York, NY, USA).

scholarly journals Polycrystal Simulation of Texture-Induced Grain Coarsening during Severe Plastic Deformation

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5834
Author(s):  
Chi Zhang ◽  
Laszlo S. Toth
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
Face Centered Cubic ◽  
Shear Texture ◽  
Grain Coarsening ◽  
Random Texture ◽  
Polycrystal Plasticity ◽  
Grain Fragmentation

During severe plastic deformation (SPD), there is usually extended grain fragmentation, associated with the formation of a crystallographic texture. The effect of texture evolution is, however, coarsening in grain size, as neighbor grains might coalesce into one grain by approaching the same ideal orientation. This work investigates the texture-induced grain coarsening effect in face-centered cubic polycrystals during simple shear, in 3D topology. The 3D polycrystal aggregate was constructed using a cellular automaton model with periodic boundary conditions. The grains constituting the polycrystal were assigned to orientations, which were updated using the Taylor polycrystal plasticity approach. At the end of plastic straining, a grain detection procedure (similar to the one in electron backscatter diffraction, but in 3D) was applied to detect if the orientation difference between neighboring grains decreased below a small critical value (5°). Three types of initial textures were considered in the simulations: shear texture, random texture, and cube-type texture. The most affected case was the further shearing of an initially already shear texture: nearly 40% of the initial volume was concerned by the coalescence effect at a shear strain of 4. The coarsening was less in the initial random texture (~30%) and the smallest in the cube-type texture (~20%). The number of neighboring grains coalescing into one grain went up to 12. It is concluded that the texture-induced coarsening effect in SPD processing cannot be ignored and should be taken into account in the grain fragmentation process.

scholarly journals Semi-Continuous Equal-Channel Angular Extrusion and Rolling of AA5083 and AZ31 Alloys

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1035 ◽  
Author(s):  
Vladimir Segal ◽  
Svetlana V. Reznikov ◽  
Nagendra Murching ◽  
Vincent H. Hammond ◽  
Laszlo J. Kecskes
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Large Scale ◽  
Equal Channel Angular Extrusion ◽  
Solution Treatment ◽  
Structure And Properties ◽  
Structural Refinement ◽  
Angular Extrusion ◽  
Lightweight Alloys ◽  
Technical Basis

This paper describes a new modification of equal-channel angular extrusion for the “pass-by-pass” semi-continuous (sc-ECAE) processing of lightweight alloys. Sc-ECAE leads to a multifold increase in productivity and decrease in costs, providing a technical basis for the commercialization of severe plastic deformation (SPD) on a large scale with massive volume production. The evolution of the structure and properties are analyzed for an aluminum alloy (AA) 5083 and a magnesium alloy AZ31 as model materials representing, respectively, the structural refinement under severe plastic deformation (SPD) via strain-induced formation of new grain boundaries and via dynamic recrystallization. For the first alloy, the microstructure after sc-ECAE is formed via ultrafine sub-grains, which are further transformed into sub-micrometer grains during post-ECAE rolling. The preliminary solution treatment of AA5083 is an important stabilizing factor for the achievement of high mechanical properties. For the second alloy, optimized sc-ECAE results in a remarkable structural refinement, and a good balance of properties is obtained with a low number of passes. However, additional rolling in the latter case leads to a degradation of the structure and properties.

Grain Refinement of Magnesium Alloys by CONFORM: A Continuous Severe Plastic Deformation Route?

2012 ◽  
Vol 706-709 ◽  
pp. 1781-1786 ◽  
Author(s):  
You Liang He ◽  
Fei Gao ◽  
Bao Yun Song ◽  
Rong Fu ◽  
Gui Ming Wu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Large Scale ◽  
Tensile Tests ◽  
Mg Alloys ◽  
Uniaxial Tensile ◽  
Batch Mode ◽  
Angular Pressing ◽  
Conform Process

Effective grain refinement through equal channel angular pressing (ECAP) for magnesium (Mg) alloys has been demonstrated by many researchers. Although with the capability to achieve superplasticity, the batch mode nature of this method and the required repetitive processing to attain ultrafine grained structure have prohibited it from being widely used in large-scale industrial production. In this study, a well-established metal forming method – the continuous extrusion forming (CONFORM) process – was employed as a severe plastic deformation route to refine the microstructure of Mg alloys. Cast Mg-3%Al-1%Zn (AZ31) rods were used as the feedstock and the cast structure (grain size of ~150 microns) was refined to ~1 micron afteronepass CONFORM extrusion. Uniaxial tensile tests of the as-extruded samples were conducted at a temperature of 473K and an elongation of ~200% was achieved under a strain rate of 1×10-4s-1. The significant grain refinement effect was attributed to the severe shear deformation occurred during the CONFORM process, which is very similar to ECAP but with even higher effective strains. The most important advantage of CONFORM over ECAP is that the former is a continuous route, so it is able to produce long products. It was also shown that CONFORM could be an additional forming method for Mg alloys to conventional rolling, forging and extrusion.

scholarly journals Understanding the Machinability of Austempered Ductile Iron (ADI)

2018 ◽  
Vol 925 ◽  
pp. 311-317 ◽  
Author(s):  
Dika Handayani ◽  
Robert C. Voigt ◽  
Kathy Hayrynen
Keyword(s):  
Plastic Deformation ◽  
Martensitic Transformation ◽  
Severe Plastic Deformation ◽  
Ductile Iron ◽  
Cutting Tool ◽  
Electron Backscatter Diffraction ◽  
Austempered Ductile Iron ◽  
Finish Machining ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Guidelines for production milling, turning and drilling of the standard grades of austempered ductile irons (ADI) have been established. Electron Backscatter Diffraction (EBSD) characterization has clearly shown that severe plastic deformation in the machining-affected-zone, ahead of and beneath the cutting tool, will cause strain-induced martensitic transformation of the austenite in the ausferrite structure that inhibits machinability. This phenomenon is particularly of concern during finish machining where small depths of cut are strongly influenced by surface martensite from prior machining passes.

Subsurface Microstructure and Crystallographic Texture in Surface Severe Plastic Deformation Processes

2017 ◽  
Author(s):  
Zhiyu Wang ◽  
Christopher Saldana ◽  
Saurabh Basu
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Crystallographic Texture ◽  
Deformation Process ◽  
High Speed ◽  
Surface Deformation ◽  
Electron Backscatter Diffraction ◽  
High Speed Imaging ◽  
Strain And Strain Rate ◽  
Deformed State

Severe plastic burnishing was investigated as a promising surface severe plastic deformation technique for generating gradient microstructure surfaces. The deformed state of oxygen free high conductivity copper workpieces during the surface deformation process was determined with high-speed imaging, this complemented by microstructure characterization using orientation image microscopy based on electron backscatter diffraction. Varying deformation levels in terms of both magnitude and gradient on the processed surface were achieved through control of the incident tool angle. Refined microstructures, including laminate grains elongated in the velocity direction and equiaxed sub-micron grains were observed in the subsurface and were found to be controlled by the combined effects of strain and strain rate in the surface deformation process. Additionally, crystallographic texture evolutions were characterized, showing typical shear textures predominately along the <110> partial fiber. The rotation of texture from original ideal orientation positions was related directly to the deformation history produced by sliding process. Based on these observations, a controllable framework for producing the processed surface with expected mechanical and microstructural responses is suggested.

The Effect of Severe Plastic Deformation Processing on Creep Properties of Metallic Materials

2015 ◽  
Vol 651-653 ◽  
pp. 639-644
Author(s):  
Jiri Dvorak ◽  
Petr Král ◽  
Vaclav Sklenička ◽  
Milan Svoboda ◽  
Marie Kvapilová
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Electron Backscatter Diffraction ◽  
Bulk Material ◽  
Creep Behaviour ◽  
Tensile Creep ◽  
Severe Plastic Deformation Processing ◽  
Processing Route ◽  
Creep Tests ◽  
Creep Properties

Processing by severe plastic deformation (SPD) may be defined as such metals forming procedure in which a very high strain is imposed on a bulk material. This paper investigates the effect of different equal channel angular pressing (ECAP) routes and number of ECAP passes on resulting microstructure, mechanical properties and creep behaviour of selected materials. The distinction between various ECAP routes (A, B and C) and the difference in number of ECAP passes applied may lead to variations both in the macroscopic distortions of the individual grains and in the capability to develop a reasonably homogeneous and equiaxed ultrafine-grained microstructure. Experimental materials were processed by ECAP at room temperature using a die with an internal angle of 90° between the two parts of the channel. The ECAP pressing was performed by different routes up to 12 ECAP passes. Tensile creep tests were conducted at temperatures 473 - 673 K and at different applied stresses on ECAP materials and, for comparison purposes, on their unpressed states. Microstructure of samples was characterized by scanning electron microscope (SEM) equipped with the electron backscatter diffraction (EBSD) unit. In conclusion, the ECAP processing route and number of applied ECAP passes could play an important role in creep behaviour and their effect may be different for particular materials. The highest differences in processing routes were revealed for materials especially at lower number of ECAP passes. However, a little apparent dependence of the creep properties was observed during subsequent pressing.

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