scholarly journals Determination of the Forming Limit for a ZIRLO™ Sheet with High Anisotropy

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5743
Author(s):  
Minsoo Kim ◽  
Seokmoo Hong
Keyword(s):  
Effective Stress ◽  
Effective Strain ◽  
Tensile Tests ◽  
Image Correlation ◽  
Dome Height ◽  
Forming Limit ◽  
Stress And Strain ◽  
Anisotropy Coefficient ◽  
Normal Anisotropy ◽  
R Value

In this study, the experimental two-dimensional forming limit diagram (FLD) data for a ZIRLO™ sheet, which is used in nuclear fuel rod support grids, were converted and presented as a triaxiality failure diagram (TFD). Most previous studies assumed ZIRLO™ to be isotropic when calculating the effective stress and strain. However, for highly anisotropic materials, the anisotropy should be considered for calculations of effective stress and strain; hence, in this study, they were calculated by introducing the normal anisotropy coefficient. To obtain this parameter of the ZIRLO™ specimens, tensile tests were performed on specimens with 0°, 45°, and 90° angles with respect to the rolling direction. It was observed that the average normal anisotropy coefficient measured during the tests was 4.94, which is very high. The von Mises isotropic and Hill 48 anisotropic yield criterion were applied to the FLD data that were experimentally determined using a limit dome height test and were converted into effective stress and effective strain. When the FLD is converted to TFD, the curve will increase in the top-right direction if the r-value is greater than 1, and this become more severe as the r-value increases. The TFD, which was converted considering the anisotropy, is almost the same to the TFD obtained using the digital image correlation method in the tensile tests of four specimens with different stress states. If anisotropy is not considered, then the formability is normally underestimated. However, a highly accurate TFD can be obtained with the method proposed in this study.

Experimental Study on the Mechanical Property and Forming Limit of Magnesium Sheet at Elevated Temperatures

2009 ◽  
Author(s):  
Y. Huang ◽  
J. Huang ◽  
J. Cao
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Dome Height ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Magnesium Sheet

Magnesium alloy sheet has received increasing attention in automotive and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. Most of work in the field has been working with the magnesium sheet after annealed around 350°C. In this paper, the as-received commercial magnesium sheet (AZ31B-H24) with thickness of 2mm has been experimentally studied without any special heat treatment. Uniaxial tensile tests at room temperature and elevated temperature were first conducted to have a better understanding of the material properties of magnesium sheet (AZ31B-H24). Then, limit dome height (LDH) tests were conducted to capture forming limits of magnesium sheet (AZ31B-H24) at elevated temperatures. An optical method has been introduced to obtain the stress-strain curve at elevated temperatures. Experimental results of the LDH tests were presented.

Creep Analysis of Orthotropic Rotating Cylinder

1980 ◽  
Vol 102 (4) ◽  
pp. 371-377 ◽  
Author(s):  
N. S. Bhatnagar ◽  
V. K. Arya ◽  
K. K. Debnath
Keyword(s):  
Strain Rate ◽  
Effective Stress ◽  
Anisotropic Material ◽  
Isotropic Material ◽  
Effective Strain ◽  
Angular Speed ◽  
Stress And Strain ◽  
Tangential Strain ◽  
Effective Strain Rate ◽  
Stress And Strain Rate

The stress and strain-rate distributions in the wall of a hollow thick-walled circular cylinder, rotating about its own axis with a constant angular speed, have been obtained using Norton’s law for the steady-state creep. The cylinder is assumed to be made of a homogeneous and orthotropic material. The numerical computations, for a number of steels and steel alloys commonly used to manufacture the cylinder, have been carried out for three cases of anisotropy. The effect of anistropy and of exponent n in creep law has been studied. It is observed that the stress and strain-rate distributions are significantly affected by the anisotropy of material and the value of exponent n. It is also noticed that the values of the effective stress for an anisotropic material for which the ratios of axial to tangential strain rate and of radial to tangential strain rate are equal to 1.2, are lower than the corresponding values for an isotropic material for which these ratios are 1.0. And, because of a power law between effective strain rate and effective stress, much lower values of the effective strain rate for the foregoing anisotropic material than those for the isotropic material will be obtained. Thus the use of the aforementioned anisotropic material may be beneficial for the manufacture of the cylinders because (i) it will result in a longer life for the cylinders (because of the lowest strain rate), or (ii) it will allow the cylinder to sustain larger forces without a risk of failure under creep.

The Extrusion Behavior of AZ31 Mg Alloys by Finite Element Simulation

2014 ◽  
Vol 906 ◽  
pp. 285-288
Author(s):  
Ping Li ◽  
Shou Ren Wang ◽  
Yong Wang ◽  
Guang Ji Xue
Keyword(s):  
Finite Element ◽  
Magnesium Alloy ◽  
Effective Stress ◽  
Effective Strain ◽  
Three Dimensional ◽  
Stress And Strain ◽  
Technical Parameters ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Extrusion Forming

The three-dimensional finite element (FE) numerical simulation of extrusion forming of AZ31 matrix magnesium alloy was analyzed in four extrusion velocities. The flow pattern and the influence of extrusion velocity for the temperature, the distribution of effective stress and strain of composites were analyzed. The results showed that, when the extrusion velocity increased from 1.5 mm/s to 4.5 mm/s, the heat flux under steady extrusion state would change from-2.77e+004 (Wm2) to 1.14e+005 (Wm2), meanwhile the effective stress and strain increased at first and then decreased, and the average effective strain and stress value were smallest when v = 4.5 mm/s. It showed that along with the increase of the extrusion velocity, the rise degree of the temperature increased and the distribution of the effective stress and strain tended to be more evenly. Finally, the best extrusion technical parameters of AZ31 magnesium alloy were determined, that was the extrusion velocity was equal to 4.5 mm/s when extrusion ratio was 25 and extrusion temperature was 350 °C.

A Study of Improving the Formability of the Commercial Pure Titanium Foils

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Jiaqi Zhu ◽  
Alex Nunnally ◽  
Jenn-Terng Gau ◽  
Siguang Xu
Keyword(s):  
High Velocity ◽  
Pure Titanium ◽  
Tensile Tests ◽  
Dome Height ◽  
Forming Limit ◽  
High Velocity Impact ◽  
Uniform Thickness ◽  
Forming Process ◽  
Velocity Impact ◽  
Commercial Pure Titanium

Abstract In order to obtain the optimum forming process for commercial pure titanium grade 2 foils, a series of tensile tests and micro scale limited dome height (µ-LDH) tests at four temperatures, and meso scale limited dome height tests (meso-LDH) with three punch speeds were conducted on the as-received foils with a thickness of 75 µm. The effects of temperature, geometry, and high-velocity impact were investigated to understand their influences on the formability of the foils. It has been found in the tensile tests that the formability can be improved by elevating temperatures; this has been validated by the µ-LDH tests. Based on forming limit diagrams (FLDs) of the meso-LDH specimens, the high-velocity impact forming process results in not only much better formability but also more uniform thickness distributions than the quasi-static. By analyzing the fractographical scanning electron microscope (SEM) pictures of the meso-LDH specimens, it has been proven that the formability of the foils by using high-velocity impact process is superior to the conventional process. Furthermore, high-velocity impact causes forming limit curve (FLC) to shift in the upper right direction on the right-hand side of FLD. Therefore, it is suggested forming the foils by using high-velocity impact forming process at the elevated temperature for obtaining a better formability and more uniform thickness distribution. It is also recommended to make the radius of the LDH hemisphere punch close to the smallest feature of the designed products for obtaining more accurate FLCs.

Characterization of Plastic Anisotropy of AA5182-O Sheets During Prestraining and Subsequent Annealing

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Kaifeng Wang ◽  
Bonan Zhou ◽  
Jingjing Li ◽  
John E. Carsley ◽  
Yang Li
Keyword(s):  
Electron Backscatter Diffraction ◽  
Plastic Anisotropy ◽  
Rolling Direction ◽  
Anisotropy Coefficient ◽  
Normal Anisotropy ◽  
Aluminum Alloy 5182 ◽  
Annealing Conditions ◽  
R Value ◽  
Value Changes ◽  
Backscatter Diffraction

This paper described the effects of prestraining and annealing on plastic anisotropy (r-value) of aluminum alloy 5182-O sheets including two prestrain paths and two annealing conditions. During the prestraining and annealing processes, r-value changed depending on prestrain paths and annealing conditions. Although there were slight changes of the normal anisotropy coefficient, r¯, during prestraining and annealing processes, the planar anisotropy coefficient, Δr, increased significantly, especially for the uniaxial prestrain condition. This could accelerate the development of earing during a sheet forming operation. Also, the corresponding sheet textures in rolling direction (RD)/TD plane after prestraining and annealing processes were observed through electron backscatter diffraction (EBSD) analysis to explain the r-value changes, where the viscoplastic self-consistent (VPSC) model was used to correlate the determined texture to measured r-values. It is found that the sheet texture also had significant changes relating to the prestrain paths and annealing conditions resulting in varied r-values.

scholarly journals Effect of Crystallographic Orientation and Grain Boundaries on Martensitic Transformation and Superelastic Response of Oligocrystalline Fe–Mn–Al–Ni Shape Memory Alloys

2021 ◽  
Author(s):  
A. Bauer ◽  
M. Vollmer ◽  
T. Niendorf
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundary ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grain Boundaries ◽  
Tensile Tests ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Grain Orientations ◽  
High Degree

AbstractIn situ tensile tests employing digital image correlation were conducted to study the martensitic transformation of oligocrystalline Fe–Mn–Al–Ni shape memory alloys in depth. The influence of different grain orientations, i.e., near-〈001〉 and near-〈101〉, as well as the influence of different grain boundary misorientations are in focus of the present work. The results reveal that the reversibility of the martensite strongly depends on the type of martensitic evolving, i.e., twinned or detwinned. Furthermore, it is shown that grain boundaries lead to stress concentrations and, thus, to formation of unfavored martensite variants. Moreover, some martensite plates seem to penetrate the grain boundaries resulting in a high degree of irreversibility in this area. However, after a stable microstructural configuration is established in direct vicinity of the grain boundary, the transformation begins inside the neighboring grains eventually leading to a sequential transformation of all grains involved.

scholarly journals Strength Enhancement of Superduplex Stainless Steel Using Thermomechanical Processing

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1094
Author(s):  
M. A. Lakhdari ◽  
F. Krajcarz ◽  
J. D. Mithieux ◽  
H. P. Van Landeghem ◽  
M. Veron
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Thermomechanical Processing ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strength Enhancement ◽  
Industrial Material ◽  
Superduplex Stainless Steel ◽  
The Impact ◽  
Strength Improvement

The impact of microstructure evolution on mechanical properties in superduplex stainless steel UNS S32750 (EN 1.4410) was investigated. To this end, different thermomechanical treatments were carried out in order to obtain clearly distinct duplex microstructures. Optical microscopy and scanning electron microscopy, together with texture measurements, were used to characterize the morphology and the preferred orientations of ferrite and austenite in all microstructures. Additionally, the mechanical properties were assessed by tensile tests with digital image correlation. Phase morphology was not found to significantly affect the mechanical properties and neither were phase volume fractions within 13% of the 50/50 ratio. Austenite texture was the same combined Goss/Brass texture regardless of thermomechanical processing, while ferrite texture was mainly described by α-fiber orientations. Ferrite texture and average phase spacing were found to have a notable effect on mechanical properties. One of the original microstructures of superduplex stainless steel obtained here shows a strength improvement by the order of 120 MPa over the industrial material.

scholarly journals Determination of Load-Carrying Capacity of C-Profile Glued Ti-Al Column under Temperature Environment

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3013
Author(s):  
Leszek Czechowski
Keyword(s):  
Carrying Capacity ◽  
Tensile Tests ◽  
Discrete Models ◽  
Image Correlation ◽  
Load Carrying Capacity ◽  
Lagrange Equations ◽  
Load Carrying ◽  
Different Temperatures ◽  
Influence Of Temperature On

The paper deals with an examination of the behaviour of glued Ti-Al column under compression at elevated temperature. The tests of compressed columns with initial load were performed at different temperatures to obtain their characteristics and the load-carrying capacity. The deformations of columns during tests were registered by employing non-contact Digital Image Correlation Aramis® System. The numerical computations based on finite element method by using two different discrete models were carried out to validate the empirical results. To solve the problems, true stress-logarithmic strain curves of one-directional tensile tests dependent on temperature both for considered metals and glue were implemented to software. Numerical estimations based on Green–Lagrange equations for large deflections and strains were conducted. The paper reveals the influence of temperature on the behaviour of compressed C-profile Ti-Al columns. It was verified how the load-carrying capacity of glued bi-metal column decreases with an increase in the temperature increment. The achieved maximum loads at temperature 200 °C dropped by 2.5 times related to maximum loads at ambient temperature.

scholarly journals Increase in Total Elongation Caused by Pure Shear Deformation in Ultra-Fine-Grained Cu Processed by Equal-Channel Angular Pressing

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 654
Author(s):  
Ryosuke Matsutani ◽  
Nobuo Nakada ◽  
Susumu Onaka
Keyword(s):  
Shear Deformation ◽  
Equal Channel Angular Pressing ◽  
Pure Shear ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Total Elongation ◽  
Local Deformation ◽  
Image Correlation ◽  
Fine Grained ◽  
Angular Pressing

Ultra-fine-grained (UFG) Cu shows little total elongation in tensile tests because simple shear deformation is concentrated in narrow regions during the initial stage of plastic deformation. Here, we attempted to improve the total elongation of UFG Cu obtained by equal-channel angular pressing. By making shallow dents on the side surfaces of the plate-like specimens, this induced pure shear deformation and increased their total elongation. During the tensile tests, we observed the overall and local deformation of the dented and undented UFG Cu specimens. Using three-dimensional digital image correlation, we found that the dented specimens showed suppression of thickness reduction and delay in fracture by enhancement of pure shear deformation. However, the dented and undented specimens had the same ultimate tensile strength. These results provide us a new concept to increase total elongation of UFG materials.

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