scholarly journals Investigation of the Dynamic Recrystallization of FeMnSiCrNi Shape Memory Alloy under Hot Compression Based on Cellular Automaton

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 469 ◽  
Author(s):  
Yu Wang ◽  
Xiaodong Xing ◽  
Yanqiu Zhang ◽  
Shuyong Jiang
Keyword(s):  
Flow Stress ◽  
Dislocation Density ◽  
Shape Memory Alloy ◽  
Dynamic Recrystallization ◽  
Cellular Automaton ◽  
Shape Memory ◽  
Dislocation Densities ◽  
Finite Growth ◽  
Solid Foundation ◽  
The Difference

Dynamic recrystallization (DRX) takes place when FeMnSiCrNi shape memory alloy (SMA) is subjected to compression deformation at high temperatures. Cellular automaton (CA) simulation was used for revealing the DRX mechanism of FeMnSiCrNi SMA by predicting microstructures, grain size, flow stress, and dislocation density. The DRX of FeMnSiCrNi SMA has a characteristic of repeated nucleation and finite growth. The size of recrystallized grains increases with increasing deformation temperatures, but it decreases with increasing strain rates. The increase of deformation temperature leads to the decrease of the flow stress, whereas the increase in strain rate results in the increase of the flow stress. The dislocation density exhibits the same situation as the flow stress. The simulated results were supported by the experimental ones very well. Dislocation density is a crucial factor during DRX of FeMnSiCrNi SMA. It affects not only the nucleation but also the growth of the recrystallized grains. Occurrence of DRX depends on a critical dislocation density. The difference between the dislocation densities of the recrystallized and original grains becomes the driving force for the growth of the recrystallized grains, which lays a solid foundation for the recrystallized grains growing repeatedly.

Microstructural and Fractographic Analysis of CuAlNi Shape Memory Alloy before and after Heat Treatment

2020 ◽  
Vol 405 ◽  
pp. 100-106
Author(s):  
Ivana Ivanić ◽  
Mirko Gojić ◽  
Stjepan Kožuh ◽  
Borut Kosec
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Fracture Surface ◽  
Shape Memory ◽  
Fractographic Analysis ◽  
Before And After ◽  
Different Temperatures ◽  
The Difference ◽  
Type Of Fracture ◽  
Scanning Electron

The paper presents comparison of microstructure and fracture surface morphology of the CuAlNi shape memory alloy (SMA) after different heat treatment procedures. The investigation was performed on samples in as-cast state and heat treated states (solution annealing at temperatures of 850 °C / 60’ / H2O and 920 °C / 60’ / H2O along with tempering at two different temperature 150 °C / 60’ / H2O and 300 °C / 60’ / H2O). The microstructure of the samples was examined by optical (OM) and scanning electron microscope (SEM) equipped with device for EDS analysis. The obtained fracture surfaces were examined by SEM. Optical and scanning electron microscopy showed martensitic microstructure in all investigated samples. However, the fractographic analysis of samples after tensile testing reveals significant changes in fracture mechanism. In both solution annealed states the results shows transgranular type of fracture, but after tempering at two different temperatures the difference is obvious. After tempering at 150 °C, along with transgranular type of fracture appear some areas with intergranular type of fracture. After tempering at 300 °C, fracture surface reveals completely intergranular type of fracture.

A STUDY OF DYNAMIC RECRYSTALLIZATION IN TA15 TITANIUM ALLOY DURING HOT DEFORMATION BY CELLULAR AUTOMATA MODEL

2009 ◽  
Vol 23 (06n07) ◽  
pp. 934-939 ◽  
Author(s):  
DONG HE ◽  
JING CHUAN ZHU ◽  
YANG WANG ◽  
YONG LIU
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Dislocation Density ◽  
Cellular Automata ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Temperature Filed ◽  
Ca Model ◽  
Grain Growth Model

The dynamic recrystallization (DRX) of TA 15 ( Ti -6 Al -2 Zr -1 Mo -1 V ) titanium alloy during the hot deformation process was studied by the Cellular Automata (CA) model which is base on the dislocation density theory. To build the CA model, the dislocation density model, dynamic recovery model, nucleation model and grain growth model were introduced and developed. The influences of strain rate on the microstructure evolution and flow stress character were investigated which shows that high strain rate leads to later DRX appearance, high flow stress peak value, small mean size of recrystallizing grains( R -grains) and low DRX percentage, but they have the similar Avrami curve. The characteristic of DRX process in a modeling non-uniform temperature filed (NTF) has been studied. All the simulation results show good agreement with the pioneer's work and experimental results.

Cellular Automaton Simulation and Experimental Observation of the Dynamic Recrystallization of Titanium Alloy TC11 with Varied Strain Rates

2012 ◽  
Vol 476-478 ◽  
pp. 71-74
Author(s):  
Zhi Fu Yang ◽  
Qing Yuan Meng ◽  
Yu Hang Jing
Keyword(s):  
Titanium Alloy ◽  
Dislocation Density ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Cellular Automaton ◽  
Experimental Observation ◽  
Hot Working ◽  
Strain Rates ◽  
Working Process ◽  
Loading Sequence

During the metal hot working process, the dislocation density will vary with strain and strain rate, and the variation of the dislocation density will affect the grain evolution subsequently. The cellular automaton (CA) method is an effective technique used to simulate the grain evolution of materials. In this work, a dynamic recrystallization (DRX) model of titanium alloy TC11 under varied strain rates was established by the use of cellular automaton method and verified by experimental observation. Two types of loading processes called “begin fast and then slowly” and “begin slowly and then fast” were simulated to investigate the titanium alloy TC11 grain evolution processes during hot working. The simulation results are in good coincidence with experimental data. Both cellular automaton simulation and experimental results show that the flow stresses and DRX transformation percentage during hot working process of the TC11 alloy are closely related not only to the strain rate but also to the loading sequence. Compared to the “begin slowly and then fast” loading sequence, the flow stress with the “begin fast and then slowly” loading sequence is relatively smaller under the same strain rates, and the DRX transformation percentage is relatively larger.

Modeling of Artificial Aurelia aurita Bell Deformation

2011 ◽  
Vol 45 (4) ◽  
pp. 165-180 ◽  
Author(s):  
Keyur B. Joshi ◽  
Alex Villanueva ◽  
Colin F. Smith ◽  
Shashank Priya
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Transient Behavior ◽  
Element Model ◽  
Aurelia Aurita ◽  
Thermal Coefficient ◽  
Power Cycle ◽  
Element Simulation ◽  
The Difference

AbstractRecently, there has been significant interest in developing underwater vehicles inspired by jellyfish. One of these notable efforts includes the artificial Aurelia aurita (Robojelly). The artificial A. aurita is able to swim with similar proficiency to the A. aurita species of jellyfish even though its deformation profile does not completely match the natural animal. In order to overcome this problem, we provide a systematic finite element model (FEM) to simulate the transient behavior of the artificial A. aurita vehicle utilizing bio-inspired shape memory alloy composite (BISMAC) actuators. The finite element simulation model accurately captures the hyperelastic behavior of EcoFlex (Shore hardness-0010) room temperature vulcanizing silicone by invoking a three-parameter Mooney-Rivlin model. Furthermore, the FEM incorporates experimental temperature transformation curves of shape memory alloy wires by introducing negative thermal coefficient of expansion and considers the effect of gravity and fluid buoyancy forces to accurately predict the transient deformation of the vehicle. The actual power cycle used to drive artificial A. aurita vehicle was used in the model. The overall profile error between FEM and the vehicle profile is mainly due to the difference in initial relaxed profiles.

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