Grain Evolution Character of Discal Parts by Roll Forming

2013 ◽  
Vol 749 ◽  
pp. 328-336
Author(s):  
Quan Lin Jin
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Titanium Alloy ◽  
Aluminum Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Grain Refinement ◽  
Grain Growth ◽  
Roll Forming ◽  
Alloy 6061

A study on grain evolution character of discal parts roll forming was carried out by means of experiment and numerical simulation. The discal part material is aluminum alloy 6061 and titanium alloy TC4. The roll forming temperature is 480-500 and 930-1020 for aluminum alloy 6061 and titanium alloy TC4, respectively. A digital double-sided roll forming machine was used for roll forming experiment of discal parts. The high frequency induction heating was used for disk heating, where the deformation zone is in the state of constant temperature. A numerical simulation of roll forming of the 6061 aluminum alloy disk was carried out. The simulated results include macroscopic deformation and various grain size evolution variables. The dynamic recrystallization, the dynamic and static grain growth were considered in the numerical simulation. The experimental and simulated results showed that there may appear not only the grain refinement due to dynamic recrystallization but also dynamic and static grain growth. It is different that from discal parts integrally forging there are the largest deformation, the highest strain rate and the best recrystallization and grain refinement in the zones contacted with the roll tools. In the zones far from the rollers, the strain rate is very low and average grain size increases until once again contact to the rollers and start new grain refinement.

Dynamic recrystallization kinetics and microstructure evolution of 7055 aluminum alloy during hot compression

2019 ◽  
Vol 116 (6) ◽  
pp. 605
Author(s):  
Tao Zhang ◽  
Huapu Sha ◽  
Lei Li ◽  
Shihong Lu ◽  
Hai Gong
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Grain Refinement ◽  
Microstructure Evolution ◽  
Large Strain ◽  
Small Strain ◽  
Small Strain Rate ◽  
7055 Aluminum Alloy

7055 aluminum alloy is widely used in manufacture of key components in fields of aerospace. Hot forming is the vital process for manufacture of components. Dynamic recrystallization (DRX) plays a significant role in grain refinement. Hot compressions and metallographic tests are conducted. Equations of DRX kinetics are fitted by least square method and finite element models (FEM) coupled with DRX kinetics equations are established to study the effects of forming parameters on microstructure evolution. The results show that true stress increases with ascending strain rate and decreases with ascending temperature. Large strain, small strain rate and high temperature are beneficial to sufficient DRX fraction and grain refinement. Deformation energy and thermally activated motion of atoms and molecules resulting from large strain and high temperature contribute to dynamic nucleation; meanwhile, small strain rate provides sufficient time for growth of recrystallized grains. The FEM results agree with experiments.

Physical Simulation of Dynamic Recrystallization Behavior of 7050 Aluminum Alloy

2008 ◽  
Vol 575-578 ◽  
pp. 1083-1085
Author(s):  
You Ping Yi ◽  
Yan Shi
Keyword(s):  
Grain Size ◽  
Aluminum Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Physical Simulation ◽  
Simulation Method ◽  
Strain Rate Range ◽  
Compression Tests ◽  
7050 Aluminum Alloy ◽  
Recrystallized Grain Size

This work aims to investigate the influence of hot deformation on dynamic recrystallization(DRX) behavior of 7050 aluminum alloy by means of physical simulation method. The hot compression tests were carried out on Gleeble 1500 machine in temperature range of 250-450°C and strain rate range of 0.01–10 s-1. Transmission electronic microscopy (TEM) was employed to observe and analyze the microstructure and DRX behavior in different deformation conditions. The results show that the effects of deformation temperature and strain rate on microstructural evolution of the alloy are remarkable. When temperature is lower than 350°C, only the dynamical recovery( DRV) occurs and typical sub-grains appear. In the range of 350-400°C, the incomplete DRX occurs and the recrystallized grain size increases with increasing temperature. The complete DRX occurs at 450°C and the fine equiaxied grains with high-angle boundaries develop resultantly. The DRX grain size increases as strain rate decreases. The desirable microstructure and properties can be obtained by optimizing the forging process parameters.

Modeling and Numerical Simulation Research on Hollow Steel Ingot Forging Process of Heavy Cylinder Forging

2013 ◽  
Vol 712-715 ◽  
pp. 627-632
Author(s):  
Min Liu ◽  
Qing Xian Ma
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Shear Zone ◽  
Grain Refinement ◽  
Steel Ingot ◽  
Effective Strain ◽  
Meridian Plane ◽  
Forging Process ◽  
Forming Load ◽  
Average Grain Size

Aiming at the disadvantages of low utilization ratio of steel ingot, uneven microstructure properties and long production period in the solid steel ingot forging process of heavy cylinder forgings such as reactor pressure vessel, a new shortened process using hollow steel ingot was proposed. By means of modeling of lead sample and DEFORM-3D numerical simulation, the deformation law and grain refinement behavior for 162 ton hollow steel ingot upsetting at different reduction ratios, pressing speeds and friction factors were investigated, and the formation rule of inner-wall defects in upsetting of hollow steel ingots with different shape factors was further analyzed. Simulation results show that the severest deformation occurs in the shear zone of meridian plane in the upsetting process of hollow steel ingot, and the average grain size in the shear zone is the smallest. As pressing speed increases, the forming load gradually increases and the deformation uniformity gets worse, while the average grain size decreases. An increase in friction factor can increase the peak value of effective strain, but it significantly reduces the deformation uniformity, increases the forming load and goes against grain refinement. Moreover, the four kinds of defects on the inner wall of steel ingot can be eliminated effectively by referring to the plotted defect control curve for hollow steel ingot during high temperature upsetting.

Research on Temperature Change and Microstructure Evolution of Bore in Steel Target Penetrated by Copper Jets

2010 ◽  
Vol 667-669 ◽  
pp. 641-646
Author(s):  
Hao Chen ◽  
Gang Tao
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Dynamic Recrystallization ◽  
Temperature Change ◽  
Microstructure Evolution ◽  
Channel Wall ◽  
Cooling Time ◽  
Steel Target

Copper fragments are found to adhere on penetration channel wall after copper jets penetrate steel target, and the research on it is helpful to know microstructure evolution of jets in the process of penetration and cooling time. This paper is based on the observation of bore in steel target penetrated by copper jets, and uses numerical simulation to study the process of copper jets penetration, then the change of temperature and grain size of jets adhered on penetration channel wall can be gotten, and the results agree with the observation of penetration channel wall taken by SEM. From the observations of copper and steel, we can get the conclusion that copper jets are not melted but have dynamic recrystallization in the process of penetration, then copper grain size increases obviously in cooling time, and twins are formed at the same time.

scholarly journals High-Temperature Deformation Behavior and Microstructural Characterization of Ti-35421 Titanium Alloy

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3623 ◽  
Author(s):  
Danying Zhou ◽  
Hua Gao ◽  
Yanhua Guo ◽  
Ying Wang ◽  
Yuecheng Dong ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Phase Region ◽  
Temperature Deformation ◽  
Β Phase ◽  
Α Phase

A self-designed Ti-35421 (Ti-3Al-5Mo-4Cr-2Zr-1Fe wt%) titanium alloy is a new type of low-cost high strength titanium alloy. In order to understand the hot deformation behavior of Ti-35421 alloy, isothermal compression tests were carried out under a deformation temperature range of 750–930 °C with a strain rate range of 0.01–10 s−1 in this study. Electron backscatter diffraction (EBSD) was used to characterize the microstructure prior to and post hot deformation. The results show that the stress–strain curves have obvious yielding behavior at a high strain rate (>0.1 s−1). As the deformation temperature increases and the strain rate decreases, the α phase content gradually decreases in the α + β phase region. Meanwhile, spheroidization and precipitation of α phase are prone to occur in the α + β phase region. From the EBSD analysis, the volume fraction of recrystallized grains was very low, so dynamic recovery (DRV) is the dominant deformation mechanism of Ti-35421 alloy. In addition to DRV, Ti-35421 alloy is more likely to occur in continuous dynamic recrystallization (CDRX) than discontinuous dynamic recrystallization (DDRX).

scholarly journals Strengthening of AA5754 Aluminum Alloy by DRECE Process Followed by Annealing Response Investigation

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 301 ◽  
Author(s):  
Przemysław Snopiński ◽  
Tomasz Tański ◽  
Klaudiusz Gołombek ◽  
Stanislav Rusz ◽  
Ondřej Hilser ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Dislocation Density ◽  
Grain Refinement ◽  
Grain Growth ◽  
Xrd Analysis ◽  
Strength Reduction ◽  
Electron Backscattered Diffraction

In this study, a dual rolls equal channel extrusion (DRECE) process has been applied for improving the mechanical properties of the 5754 alloy. Supplementary experiments involving metallography, electron backscattered diffraction (EBSD), and XRD tests were carried out to evaluate the effect of the DRECE process. XRD analysis showed that the maximum dislocation density was achieved after six DRECE passes, which were accompanied by the formation that is typical for low-strain structures. The increasing dislocation density, as well as grain refinement throughout DRECE deformation, resulted in an increase in the mechanical properties. Annealing of the as-deformed sample resulted in grain growth and strength reduction.

scholarly journals Constitutive Relationship for Hot Deformation of TB18 Titanium Alloy

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Qiang Fu ◽  
Wuhua Yuan ◽  
Wei Xiang
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Peak Stress ◽  
Constitutive Relationship ◽  
Flow Localization ◽  
Phase Zone

In the present work, the hot deformation behavior of TB18 titanium alloy was investigated by isothermal hot compression tests with temperatures from 650 to 880°C and strain rates from 0.001 to 10 s−1. The flow curves after friction and temperature correction show that the peak stress decreased with the temperature increase and the strain rate decrease. Three typical characteristics of flow behavior indicate the dynamic softening behavior during hot deformation. At a strain rate of 0.001∼0.01 s−1, the flow stress continues to decrease as the strain rate increases after the flow stress reaches the peak stress; the flow softening mechanism is dynamic recovery and dynamic recrystallization at a lower temperature and dynamic recrystallization at a higher temperature. The discontinuous yielding phenomenon could be seen at a strain rate of 1 s−1, dynamic recrystallization took place in the β single-phase zone, and flow localization bands were observed in the α + β two-phase zone. At a higher strain rate of 10 s−1, the flow instabilities were referred to as the occurrence of flow localization by adiabatic heat. Constitutive equation considering the compensation of strain was also established, and the results show high accuracy to predict the flow stress with the correlation coefficient of 99.2% and the AARE of 6.1%, respectively.

Grain Size in Mg Alloys: Recrystallization and Mechanical Consequences

2007 ◽  
Vol 558-559 ◽  
pp. 433-440 ◽  
Author(s):  
Matthew R. Barnett ◽  
Dale Atwell ◽  
Aiden G. Beer
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Mechanical Response ◽  
Deformation Twinning ◽  
Simultaneous Increase ◽  
The Impact ◽  
Strength And Ductility

The present paper examines the development of grain size during the recrystallization of magnesium alloys and the influence the grain size has on the mechanical response. In magnesium alloys grain refinement improves the strength-ductility balance. This simultaneous increase in both strength and ductility is ascribed to the impact the grain size has on deformation twinning. The mechanisms by which the grain size is established during hot working are shown to be conventional dynamic recrystallization followed by post-dynamic recrystallization. The role of alloying addition on both of these reactions is briefly considered.

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.

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