scholarly journals Experimental and modelling study of the grain refinement of Fe-30wt%Ni-Nb austenite model alloy subjected to severe plastic deformation process

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
D. S. Svyetlichnyy ◽  
J. Majta ◽  
R. Kuziak ◽  
K. Muszka
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Satisfactory Agreement ◽  
Misorientation Angle ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Grain Structure ◽  
Model Alloy ◽  
Microstructure Development ◽  
Cycle Number

AbstractThis study addresses some aspects regarding a computer modelling based on three-dimensional Frontal Cellular Automata (FCA) for the simulation of ultrafine-grained (UFG) microstructure development in purpose-designed microalloyed austenite model alloy i.e. FCC structure. Proposed in the present study model is a step forward towards understanding the deformation and microstructure development mechanisms occurring during severe plastic deformation (SPD) processes with high accumulation of the plastic deformation effects in FCC structures. The analysed microalloyed austenite microstructures were developed due to SPD effects. Using the proposed computer model, based on three-dimensional FCA it has been shown that it is possible to predict some characteristics of the FCC microstructures such as the grain size and the distribution of the boundaries misorientation angle. These abilities were proved by the qualitative and quantitative comparisons of the modelling and SEM/EBSD results. The capabilities of the proposed model were tested using experimental results of the wire drawing processes. The paper presents the new original results of experimental studies of multi-staged MaxStrain technology with the microscopic investigation. Basing on data obtained from these studies, the dependencies of the evolution of grain structure and misorientation angle on the accumulative strain and cycle number were obtained in a form of approximation equations. The equations were implemented into the CA model, and MaxStrain technology was simulated. Comparison of the results obtained in experimental studies and simulations shows a satisfactory agreement. Industrial verification of the developed model as well shows a satisfactory agreement.

scholarly journals The grain structure refinement of metals and alloys under severe plastic deformation: experimental data and analysis of mechanisms

2020 ◽  
pp. 85-111
Author(s):  
T. V Ostanina ◽  
A. I Shveykin ◽  
P. V Trusov
Keyword(s):  
Experimental Data ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Structure Refinement ◽  
Experimental Studies ◽  
Functional Materials ◽  
Metals And Alloys ◽  
Grain Structure ◽  
Lattice Curvature ◽  
Fine Grained

Wide opportunities of using fine-grained materials as structural and functional materials with advanced physical and mechanical properties have proved the importance of improving the existing technology and creating new processing methods and treatment conditions for such ma-terials. At the same time, a preliminary theoretical analysis using mathematical models gives an opportunity to significantly reduce the cost of such experimental studies. Thus, it is necessary to develop multilevel models of polycrystalline metals and alloys based on crystal plasticity with the description of structure, deformation mechanisms and refinement at various scale levels. To con-struct a correct model of such a class, it is necessary to analyze information and arrange a large amount of experimental data about grain structure refinement. The article presents a review of the experimental studies describing and analyzing the grain structure refinement during severe plastic deformations of various metal alloys. The refine-ment mainly occurs at low temperatures that are a priori lower than the temperatures at which re-crystallization becomes an important factor and the solid-state phase transitions may take place. We have summarized the significant physical mechanisms of the grain refinement during cold deformation based on the arranged experimental data from the review. All the considered articles pay attention to the local accumulation of lattice dislocations inside the grains (in the form of flat clusters), which leads to the lattice curvature and separation of grains into cells. As a result of a further accumulation of dislocations in the walls, there comes an increase in misorientation of the neighboring cells. The curved lattice is unstable (it seems clear that the flat clusters become a source of such curvatures) and relaxes with the formation and movement of the partial disclina-tions, which leads to the rotation of the adjacent grain regions and creation of new grain bounda-ries. In addition, the mesoscale defects located at the junctions of the grains (including the boundary intersection disclinations), flat clusters of the dislocations of the orientational mismatch at the grain boundaries and partial dislocations in the grains have a significant effect on the frag-mentation. The articles about the severe plastic deformation at high temperatures are briefly de-scribed here. It is noted that recrystallization is the main mechanism of the fine-grained structure formation under these conditions. We suggest including the description of the discussed mechanisms in the multilevel con-stitutive material models. When new experimental data appear for a specific process of the severe plastic deformation, the considered refinement mechanisms can be added.

Severe plastic deformation of Al-1%Cu Alloy processed by a Simple Cyclic Extrusion Compression technique

2018 ◽  
Vol 1 (1) ◽  
pp. 77-90
Author(s):  
Walaa Abdelaziem ◽  
Atef Hamada ◽  
Mohsen A. Hassan
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Deformation Behavior ◽  
Cast Alloy ◽  
Surface Hardness ◽  
Grain Structure ◽  
Compression Technique ◽  
Cu Alloy ◽  
Cyclic Extrusion Compression

Severe plastic deformation is an effective method for improving the mechanical properties of metallic alloys through promoting the grain structure. In the present work, simple cyclic extrusion compression technique (SCEC) has been developed for producing a fine structure of cast Al-1 wt. % Cu alloy and consequently enhancing the mechanical properties of the studied alloy. It was found that the grain structure was significantly reduced from 1500 µm to 100 µm after two passes of cyclic extrusion. The ultimate tensile strength and elongation to failure of the as-cast alloy were 110 MPa and 12 %, respectively. However, the corresponding mechanical properties of the two pass CEC deformed alloy are 275 MPa and 35%, respectively. These findings ensure that a significant improvement in the grain structure has been achieved. Also, cyclic extrusion deformation increased the surface hardness of the alloy by 49 % after two passes. FE-simulation model was adopted to simulate the deformation behavior of the material during the cyclic extrusion process using DEFORMTM-3D Ver11.0. The FE-results revealed that SCEC technique was able to impose severe plastic strains with the number of passes. The model was able to predict the damage, punch load, back pressure, and deformation behavior.

Finite Element Simulation of Heat Transfer during Cryogenic Asymmetric Sheet Rolling of Aluminum Alloys

2016 ◽  
Vol 716 ◽  
pp. 692-699 ◽  
Author(s):  
Alexander Pesin ◽  
Denis Pustovoytov
Keyword(s):  
Heat Transfer ◽  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Severe Plastic Deformation ◽  
Grain Structure ◽  
Sheet Rolling ◽  
Fine Grain ◽  
Element Simulation ◽  
Alloy 6061

Aluminum and its alloys are widely used as structural materials in aerospace, automotive and other industries due to low density and high specific strength. Efficient way to increase strength and other properties of aluminum alloys is to form an ultra fine grain structure using severe plastic deformation methods. Cryogenic asymmetric sheet rolling under liquid nitrogen temperature is a process of severe plastic deformation that can be used to improve the aluminum alloys structure and properties. Prediction of sheet temperature during plastic deformation is very important. The temperature of sheet is changed due to the conversion of mechanical work of deformation into heat through sliding on contact surfaces. This paper presents the results of the finite element simulation of heat transfer during cryogenic asymmetric sheet rolling of aluminum alloy 6061. The effect of thickness reduction, rolling velocity and friction coefficient on the deformation heating and temperature field of aluminum alloy 6061 was found. The results of investigation could be useful for the development of the optimal treatment process of aluminum alloys by cryogenic severe plastic deformation to obtain the ultra fine grain structure and high strength properties.

Influence of Experimental Environment on the Enhancement of Ultra Fine Grain Structure with Optimum Ductility of Equal Channel Angular Pressed Copper

2014 ◽  
Vol 592-594 ◽  
pp. 410-415
Author(s):  
A.T. Vijayashakthivel ◽  
T.N. Srikantha Dath ◽  
B. Ravishankar
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Bulk Material ◽  
Grain Structure ◽  
Structural Refinement ◽  
High Deformation ◽  
Die Geometry ◽  
Angular Pressing ◽  
Fine Grain ◽  
Increased Strength

Strengthening the engineering material through Severe Plastic Deformation and associated structural refinement is an established practice. Among the Severe Plastic Deformation process, Equal Channel Angular Pressing (ECAP) assumes a significant place. In this, it is possible to attain even ultra fine grain (UFG) structure through high deformation in bulk material working mode. However ECAPed material suffers lack of ductility, structural inhomogenity and even thermodynamically unstable structure, as evidenced in the published literature on ECAP of copper. The present study on ECAP of commercial purity copper aimed to attain a structure of higher hardness by shedding little ductility is deviated from the past work; in this, commercial quality copper is ECAPed at 3000 C with a die geometry channel angle of 1100 and corner angle of 200 necessitating less local/working stress. During certain number of passes (six passes), the material experiences higher hardness with fair amount of ductility. The material does not exhibit any further strengthening beyond six passes, which is possibly due to dislocations annihilation/recovery. The increased strength and loss of ductility of the material results in degrading the material when it undergoes tenth pass.

Cellular Automaton Simulation of Microstructure Evolution for Friction Stir Blind Riveting

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Avik Samanta ◽  
Ninggang Shen ◽  
Haipeng Ji ◽  
Weiming Wang ◽  
Jingjing Li ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Cellular Automaton ◽  
Microstructure Evolution ◽  
Numerical Approach ◽  
Dislocation Dynamics ◽  
Grain Structure ◽  
Workpiece Material ◽  
Friction Stir ◽  
Ca Model

Friction stir blind riveting (FSBR) process offers the ability to create highly efficient joints for lightweight metal alloys. During the process, a distinctive gradient microstructure can be generated for the work material near the rivet hole surface due to high-gradient plastic deformation and friction. In this work, discontinuous dynamic recrystallization (dDRX) is found to be the major recrystallization mechanism of aluminum alloy 6111 undergoing FSBR. A cellular automaton (CA) model is developed for the first time to simulate the evolution of microstructure of workpiece material during the dynamic FSBR process by incorporating main microstructure evolution mechanisms, including dislocation dynamics during severe plastic deformation, dynamic recovery, dDRX, and subsequent grain growth. Complex thermomechanical loading conditions during FSBR are obtained using a mesh-free Lagrangian particle-based smooth particle hydrodynamics (SPH) method, and are applied in the CA model to predict the microstructure evolution near the rivet hole. The simulation results in grain structure agree well with the experiments, which indicates that the important characteristics of microstructure evolution during the FSBR process are well captured by the CA model. This study presents a novel numerical approach to model and simulate microstructure evolution undergoing severe plastic deformation processes.

scholarly journals Self-Similar Mode of Metals Fragmentation under Severe Plastic Deformation

2019 ◽  
Vol 64 (6) ◽  
pp. 487
Author(s):  
A. V. Khomenko
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Structure ◽  
Structural Defects ◽  
Boundary Density ◽  
Similar Mode ◽  
Self Similar ◽  
Metallic Specimen ◽  
Comparison Of The Results ◽  
Kinetics Of

In the framework of nonequilibrium evolution thermodynamics, the influence of additive fluctuations on the kinetics of structural defects under severe plastic deformation has been studied. The applied method is a new one for the description of fragmentation modes and corresponding self-organization processes. It is found that a fragmented metallic specimen demonstrates a self-similar behavior, which results in the formation of a grain structure with various grain sizes. Such a behavior takes place provided that the probability distribution for the grain boundary density has a power-law dependence. A comparison of the results obtained in the Itˆo and Stratonovich forms demonstrates the absence of qualitative changes in the behavior of the system.

Effect of Grain Boundary State on Diffusion and Diffusion-Controlled Processes in Ultrafine-Grained Materials Processed by Severe Plastic Deformation

2015 ◽  
Vol 5 ◽  
pp. 111-126
Author(s):  
Evgeny V. Naydenkin ◽  
Galina P. Grabovetskaya ◽  
I.P. Mishin
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
Experimental Studies ◽  
Boundary State ◽  
Diffusion Controlled ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials ◽  
And Diffusion

Experimental studies on the grain boundary diffusion and processes controlled by it in the ultrafine-grained metallic materials produced by various methods of severe plastic deformation are reviewed. Correlation between the increased diffusion permeability of grain boundaries and features of recrystallization and deformation development in these materials possessing the non-equilibrium state of grain boundaries formed during severe plastic deformation in the temperature range of T < 0.35Tm is demonstrated and analyzed.

The Effect of a Severe Plastic Deformation by Groove Pressing on the Grain Structure of the Al-Mg Alloy

2017 ◽  
Vol 743 ◽  
pp. 187-190 ◽  
Author(s):  
Evgeny N. Moskvichev ◽  
Vladimir V. Skripnyak ◽  
Dmitry V. Lychagin ◽  
Vladimir A. Krasnoveikin
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Structure ◽  
Mg Alloy ◽  
Rolled Sheet ◽  
Strength Increase ◽  
Electron Backscattered Diffraction ◽  
Before And After ◽  
Static Conditions

In this article, the effect of a severe plastic deformation (SPD) achieved by groove pressing (GP) on the grain structure and mechanical properties of a rolled sheet Al-Mg alloy was investigated. The study of the microstructure of the samples before and after processing was carried out by means of electron backscattered diffraction (EBSD). The mechanical properties of the samples were experimentally studied under uniaxial tension in quasi-static conditions, and microhardness testing was implemented. It was found that the conventional yield strength and ultimate tensile strength increase by the factor of 1.4 and 1.5, respectively; and the microhardness increases by approximately 2.7 times after four machining sequences of the rolled sheet alloy. A bimodal grain structure, consisting of two grain types with particular features, is formed in the samples after four machining sequences of GP.

Interface-driven microstructure development and ultra high strength of bulk nanostructured Cu-Nb multilayers fabricated by severe plastic deformation

2013 ◽  
Vol 28 (13) ◽  
pp. 1799-1812 ◽  
Author(s):  
Irene J. Beyerlein ◽  
Nathan A. Mara ◽  
John S. Carpenter ◽  
Thomas Nizolek ◽  
William M. Mook ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Strength ◽  
Microstructure Development ◽  
Image Position

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