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.

Simulations of Microstructure Evolution During Friction Stir Blind Riveting Using a Cellular Automaton Method

2017 ◽  
Author(s):  
Avik Samanta ◽  
Ninggang Shen ◽  
Haipeng Ji ◽  
Weiming Wang ◽  
Hongtao Ding ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Cellular Automaton ◽  
Microstructure Evolution ◽  
Deformation Gradient ◽  
Microstructural Analysis ◽  
Numerical Approach ◽  
Friction Stir ◽  
Large Gradient ◽  
Gradient Microstructure ◽  
Ca Model

Friction stir blind riveting (FSBR) is a novel and highly efficient joining technique for lightweight metal materials, such as aluminum alloys. The FSBR process induced large gradients of plastic deformation near the rivet hole surface and resulted in a distinctive gradient microstructure in this domain. In this study, microstructural analysis is conducted to analyze the final microstructure after the FSBR process. Dynamic recrystallization (DRX) is determined as the dominant microstructure evolution mechanism due to the significant heat generation during the process. To better understand the FSBR process, a two-dimensional Cellular Automaton (CA) model is developed to simulate the microstructure evolution near the rivet hole surface by considering the FSBR process loading condition. To model the significant microstructure change near the rivet hole surface, spatial distributed temporal thermal and mechanical loading conditions are applied to simulate the effect of the large gradient plastic deformation near the hole surface. The distribution grain topography and recrystallization fraction are obtained through the simulations, which agree well with the experimental data. This study presents a reliable numerical approach to model and simulate microstructure evolution governed by DRX under the large plastic deformation gradient in FSBR.

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.

Investigations on Microstructure Evolution and Deformation Behavior of Aged and Ultrafine Grained Al-Zn-Mg Alloy Subjected to Severe Plastic Deformation

2010 ◽  
Vol 667-669 ◽  
pp. 253-258
Author(s):  
Wei Ping Hu ◽  
Si Yuan Zhang ◽  
Xiao Yu He ◽  
Zhen Yang Liu ◽  
Rolf Berghammer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Microstructure Evolution ◽  
Deformation Behavior ◽  
Deformation Mechanisms ◽  
Mg Alloy ◽  
Ultrafine Grained

An aged Al-5Zn-1.6Mg alloy with fine η' precipitates was grain refined to ~100 nm grain size by severe plastic deformation (SPD). Microstructure evolution during SPD and mechanical behaviour after SPD of the alloy were characterized by electron microscopy and tensile, compression as well as nanoindentation tests. The influence of η' precipitates on microstructure and mechanical properties of ultrafine grained Al-Zn-Mg alloy is discussed with respect to their effect on dislocation configurations and deformation mechanisms during processing of the alloy.

scholarly journals Cellular Automaton Modeling of Phase Transformation of U-Nb Alloys during Solidification and Consequent Cooling Process

2019 ◽  
Vol 38 (2019) ◽  
pp. 567-575 ◽  
Author(s):  
Qingfu Tang ◽  
Dong Chen ◽  
Bin Su ◽  
Xiaopeng Zhang ◽  
Hongzhang Deng ◽  
...  
Keyword(s):  
Cellular Automaton ◽  
Microstructure Evolution ◽  
Optical Microscope ◽  
Phase Precipitation ◽  
Cooling Process ◽  
Dendrite Morphology ◽  
Ca Model ◽  
Measuring Experiment ◽  
Kinetics Of ◽  
Cast Microstructure

AbstractThe microstructure evolution of U-Nb alloys during solidification and consequent cooling process was simulated using a cellular automaton (CA) model. By using this model, ϒ phase precipitation and monotectoid decomposition were simulated, and dendrite morphology of ϒ phase, Nb microsegregation and kinetics of monotectoid decomposition were obtained. To validate the model, an ingot of U-5.5Nb (wt.%) was produced and temperature measuring experiment was carried out. As-cast microstructure at different position taken from the ingot was investigated by using optical microscope and SEM. The effect of cooling rate on ϒ phase precipitation and monotectoid decomposition of U-Nb alloys was also studied. The simulated results were compared with the experimental results and the capability of the model for quantitatively predicting the microstructure evolution of U-Nb alloys during solidification and consequent cooling process was assessed.

TEM Characterization of a 7042 Aluminum FSW Joint

2012 ◽  
Vol 186 ◽  
pp. 331-334
Author(s):  
Mateusz Kopyściański ◽  
Stanislaw Dymek ◽  
Carter Hamilton
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Dislocation Density ◽  
Severe Plastic Deformation ◽  
Base Material ◽  
Friction Stir ◽  
Tem Characterization ◽  
Equiaxed Grains

This research characterizes the changes in microstructure that occur in friction stir welded extrusions of a novel 7042 aluminum alloy. Due to the presence of scandium the base material preserved the deformation microstructure with elongated grains and fairly high dislocation density. The temperature increase with simultaneous severe plastic deformation occurring during friction stir welding induced significant changes in the microstructure within the weld and its vicinity. The weld center (stir zone) was composed of fine equiaxed grains with residual dislocations and a modest density of small precipitates compared to the neighbouring thermomechanically and heat affected zones where the density of small precipitates was much higher.

scholarly journals Microstructure Evolution and Mechanical Property Characterization of 6063 Aluminum Alloy Tubes Processed with Friction Stir Back Extrusion

JOM ◽  
2019 ◽  
Vol 71 (12) ◽  
pp. 4436-4444
Author(s):  
Suhong Zhang ◽  
Alan Frederick ◽  
Yiyu Wang ◽  
Mike Eller ◽  
Paul McGinn ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Microstructure Evolution ◽  
Electron Backscatter Diffraction ◽  
Deformation Gradient ◽  
Optical Microscope ◽  
Grain Structure ◽  
Frictional Heat ◽  
Friction Stir ◽  
Metal Extrusion ◽  
Backscatter Diffraction

Abstract Friction stir back extrusion (FSBE) is a technique for lightweight metal extrusion. The frictional heat and severe plastic deformation of the process generate an equiaxed refined grain structure because of dynamic recrystallization. Previous studies proved that the fabrication of tube and wire structures is feasible. In this work, hollow cylindrical billets of 6063-T6 aluminum alloy were used as starting material. A relatively low extrusion ratio allows for a temperature and deformation gradient through the tube wall thickness to elucidate the effect of heat and temperature on the microstructure evolution during FSBE. The force and temperature were recorded during the processes. The microstructures of the extruded tubes were characterized using an optical microscope, energy-dispersive x-ray spectroscopy, electron backscatter diffraction, and hardness testing. The process reduced the grain size from 58.2 μm to 20.6 μm at the inner wall. The microhardness of the alloy was reduced from 100 to 60–75 HV because of the process thermal cycle.

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.

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