Tensile Properties of Recrystallized and Unrecrystallized Tungsten at Elevated Temperatures

2016 ◽  
Vol 838-839 ◽  
pp. 272-277 ◽  
Author(s):  
Nobuatsu Tano ◽  
Junya Kobayashi ◽  
Goroh Itoh ◽  
Akira Kurumada ◽  
Shingo Mukae
Keyword(s):  
Strain Rate ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
High Heat ◽  
Testing Temperature ◽  
Total Elongation ◽  
Resistance Welding ◽  
Temperature Deformation ◽  
Environmental Embrittlement ◽  
Welding Processes

Tungsten has higher melting point than any other metals. Therefore, tungsten is applied to the electrode for resistance welding. The electrodes for resistance welding of tungsten are mainly used for fusing joining because they have high heat resistance and are hard to be alloyed with work metal pieces. However, the cracks on electrode surface occur during cyclic welding processes. In this study, to reveal the relationship between the elevated temperature deformation characteristics and fracture mechanism of recrystallized and unrecrystallized tungsten, tensile tests were carried out with varying strain rate and testing temperature. At 400°C, the total elongation at a strain rate of 1.4×10-1 s-1 in the recrystallized tungsten decreased more than the total elongation at the other strain rate. At 600°C, total elongation increased by approximately 10%, if the strain rate was increased from 1.4×10-3 s-1 to 1.4×10-1 s-1. Then, the recrystallized tungsten at the strain rate of 1.4×10-1 s-1 had more necking than that of 1.4×10-3 s-1. The may be caused by an environmental embrittlement due to oxygen in the high temperature atmosphere.

Modeling of the Plastic Characteristics of AA6082 for the Friction Stir Welding Process

2015 ◽  
Vol 639 ◽  
pp. 309-316
Author(s):  
Sergio Pellegrino ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Wolfgang Böhm ◽  
Hung Nguyen
Keyword(s):  
Friction Stir Welding ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Flow Behavior ◽  
Welding Process ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Friction Stir ◽  
Friction Stir Welding Process ◽  
Welding Processes

Focus of this paper is to model the plastic forming behavior of AA6082, in order to develop the numerical FE analysis of the friction stir welding processes and the simulation of subsequent forming processes. During the friction stir welding process, the temperatures reached are until 500 °C and have a fundamental role for the correct performance of the process so the material data has to show a temperature dependency. Because of the tool rotation a strain rate sensitivity of the material has to be respected as well. In this context, the general material characteristics of AA6082 were first identified for different stress states. For the uniaxial state the standard PuD-Al used in the automotive industry was applied, for the shear state the ASTM B831-05 was used and for biaxial states the ISO 16842 was exploited. To characterize the plastic flow behavior of the AA6082 at elevated temperatures tensile tests were performed according to DIN EN ISO 6892-2 from 25 °C until 500 °C with a strain rate from 0.1 s-1up to 6.5 s-1.

High Temperature Deformation Mechanism Maps of NiAl

2004 ◽  
Vol 449-452 ◽  
pp. 57-60
Author(s):  
I.G. Lee ◽  
A.K. Ghosh
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Deformation Mechanism ◽  
Calculation Method ◽  
Deformation Behavior ◽  
Tensile Tests ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Sizes ◽  
Temperature Strain

In order to analyze high temperature deformation behavior of NiAl alloys, deformation maps were constructed for stoichiometric NiAl materials with grain sizes of 4 and 200 µm. Relevant constitute equations and calculation method will be described in this paper. These maps are particularly useful in identifying the location of testing domains, such as creep and tensile tests, in relation to the stress-temperature-strain rate domains experienced by NiAl.

High-Temperature Mechanical Properties and Constitutive Modelling of Ti6Al4V Sheets

2016 ◽  
Vol 879 ◽  
pp. 2020-2025 ◽  
Author(s):  
Beatrice Valoppi ◽  
Stefania Bruschi ◽  
Andrea Ghiotti
Keyword(s):  
Elevated Temperature ◽  
Strain Rate ◽  
Flow Behavior ◽  
Hot Stamping ◽  
Tensile Tests ◽  
Testing Temperature ◽  
Constitutive Modelling ◽  
Arrhenius Model ◽  
High Temperature Mechanical Properties ◽  
Material Texture

In this paper, tensile tests were performed at elevated temperature and strain rate in order to investigate the plastic flow behavior, anisotropic characteristics and microstructural evolution of Ti6Al4V sheets under testing conditions similar to the ones experienced during hot stamping operations. It is shown that the Ti6Al4V anisotropic characteristics under the investigated forming conditions, different from the ones of the superplastic regime, are influenced by the variation of the material texture as a function of the testing temperature. The Ti6Al4V flow stress behavior was analyzed as a function of the deformation temperature and strain rate. Afterwards, the Arrhenius constitutive model was proposed to predict the flow behavior of Ti6Al4V sheets at elevated temperature and strain rate. The statistical analysis of its predictive capabilities suggests that the Arrhenius model guarantees a good accuracy in reproducing the flow behavior of Ti6Al4V sheets.

Mechanical Properties and Fracture Study of Alumina Dispersion Hardened Copper-Based Nano-Composite at Elevated Temperatures

2013 ◽  
Vol 829 ◽  
pp. 583-588 ◽  
Author(s):  
Ali Dalirbod ◽  
Yahya A. Sorkhe ◽  
Hossein Aghajani
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Fracture Surface ◽  
Yield Strength ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Testing Temperature ◽  
Optical Microscope ◽  
Tensile Fracture ◽  
Different Temperatures

Alumina dispersion hardened copper-base composite was fabricated by internal oxidation method. The high temperature tensile fracture of Cu-Al2O3 composite was studied and tensile strengths were determined at different temperatures of 600, 680 and 780 °C. Microstructure was investigated by means of optical microscope and field emission scanning electron microscope (FESEM) with energy dispersive spectroscopy (EDS). Results show that, ultimate tensile strength and yield strength of copper alumina nanocomposite decrease slowly with increasing temperature. The yield strength reaches 119 MPa and ultimate tensile strength reaches 132 MPa at 780 °C. Surface fractography shows a dimple-type fracture on the fracture surface of the tensile tests where dimple size increases with increasing testing temperature and in some regions brittle fracture characteristics could be observed in the fracture surface.

scholarly journals High Strain Rate Tensile Properties of Annealed 2 1/4 Cr-1 Mo Steel

1976 ◽  
Vol 98 (4) ◽  
pp. 361-368 ◽  
Author(s):  
R. L. Klueh ◽  
R. E. Oakes
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
High Strain Rate ◽  
Strain Rate ◽  
Tensile Properties ◽  
Elevated Temperatures ◽  
High Strain ◽  
Total Elongation ◽  
Major Effect ◽  
Dynamic Strain

The high strain rate tensile properties of annealed 2 1/4 Cr-1 Mo steel were determined and the tensile behavior from 25 to 566°C and strain rates of 2.67 × 10−6 to 144/s were described. Above 0.1/s at 25°C, both the yield stress and the ultimate tensile strength increased rapidly with increasing strain rate. As the temperature was increased, a dynamic strain aging peak appeared in the ultimate tensile strength-temperature curves. The peak height was a maximum at about 350°C and 2.67 × 10−6/s. With increasing strain rate, a peak of decreased height occurred at progressively higher temperatures. The major effect of strain rate on ductility occurred at elevated temperatures, where a decrease in strain rate caused an increase in total elongation and reduction in area.

Mechanical Behaviors of Alloy 617 with Varied Strain Rates at High Temperatures

2014 ◽  
Vol 783-786 ◽  
pp. 1182-1187
Author(s):  
Mattias Calmunger ◽  
Guo Cai Chai ◽  
Sten Johansson ◽  
Johan Moverare
Keyword(s):  
Strain Rate ◽  
Power Plants ◽  
Elevated Temperatures ◽  
Fracture Strain ◽  
Tensile Tests ◽  
Strain Rates ◽  
Mechanical Behaviors ◽  
Contrast Imaging ◽  
Alloy 617 ◽  
Nickel Base

Nickel base alloys due to their high performances have been widely used in biomass and coal fired power plants. They can undertake plastic deformation with different strain rates such as those typically seen during creep and fatigue at elevated temperatures. In this study, the mechanical behaviors of Alloy 617 with strain rates from 10-2/s down to 10-6/s at temperatures of 650°C and 700°C have been studied using tensile tests. Furthermore, the microstructures have been investigated using electron backscatter detection and electron channeling contrast imaging. At relatively high strain rate, the alloy shows higher fracture strains at these temperatures. The microstructure investigation shows that it is caused by twinning induced plasticity due to DSA. The fracture strain reaches the highest value at a strain rate of 10-4/s and then it decreases dramatically. At strain rate of 10-6/s, the fracture strain at high temperature is now smaller than that at room temperature, and the strength also decreases with further decreasing strain rate. Dynamic recrystallization can also be observed usually combined with crack initiation and propagation. This is a new type of observation and the mechanisms involved are discussed.

scholarly journals Advanced Use of a Split Hopkinson Bar Setup for the Extended Characterization of Multiphase Steel Sheets

2010 ◽  
Vol 638-642 ◽  
pp. 1065-1070
Author(s):  
Joost Van Slycken ◽  
Patricia Verleysen ◽  
Joris Degrieck
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
High Strain ◽  
Tensile Tests ◽  
Trip Steels ◽  
Split Hopkinson Tensile Bar ◽  
Steel Sheets ◽  
Split Hopkinson ◽  
Multiphase Steel

In this paper some highlights are presented of an integrated numerical and experimental approach to obtain an in-depth understanding of the high strain rate behavior of materials. This is illustrated by an investigation of the multiphase TRansformation Induced Plasticity (TRIP) steel. ‘Classic’ high strain rate tensile experiments using a split Hopkinson tensile bar setup are complemented with strain rate jump tests, tensile tests at elevated temperatures and interrupted experiments. High strain rate compression and three-point bending experiments are performed on the steel sheets as well. The results reveal the excellent energy-absorption properties in dynamic circumstances of TRIP steels. Advanced experimental setups using the Hopkinson principle provide indeed tools for validation of the material and structural properties of TRIP steels.

Strain Rate Sensitivity of Ultrafine Grained FCC- and BCC-Type Metals

2006 ◽  
Vol 503-504 ◽  
pp. 781-786 ◽  
Author(s):  
Johannes May ◽  
Heinz Werner Höppel ◽  
Matthias Göken
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Testing Temperature ◽  
Ultrafine Grain ◽  
Ultrafine Grain Size ◽  
Ultrafine Grained

The dependence of the strain rate sensitivity (SRS) of α-Fe and Al 99.5, as typical representatives of fcc- and bcc-type metals, on the testing temperature and with respect to the microstructure is investigated. In particular, the differences between conventional grain size (CG) and ultrafine grain size (UFG) are pointed out. UFG Al 99.5 generally shows an elevated SRS compared to CG Al 99.5. In case of α-Fe the SRS of the UFG state is decreased at room temperature, but increased at 200 °C, compared to the CG state. It is shown that the SRS also influences the ductility of UFG-metals in tensile tests.

Mechanical properties of a 20 vol % SiC whisker-reinforced, yttria-stabilized, tetragonal zirconia composite at elevated temperatures

1995 ◽  
Vol 10 (1) ◽  
pp. 113-118 ◽  
Author(s):  
S.E. Dougherty ◽  
T.G. Nieh ◽  
J. Wadsworth ◽  
Y. Akimune
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Tetragonal Zirconia ◽  
Tensile Tests ◽  
Engineering Properties ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Deformation Properties ◽  
Before And After

The high-temperature deformation behavior of a SiC whisker-reinforced, yttria-stabilized, tetragonal zirconia polycrystalline composite containing 20 vol % SiC whiskers (SiC/Y-TZP) has been investigated. Tensile tests were performed in vacuum at temperatures from 1450 °C to 1650 °C and at strain rates from 10−3 to 10−5 s−1. The material exhibits useful high-temperature engineering properties (e.g., ∼100 MPa and 16% elongation at T = 1550 °C and at a strain rate of ∼10−4 s−1). The stress exponent was determined to be n ≍ 2. Scanning electron microscopy was used to characterize the grain size and morphology of the composites, both before and after deformation. The grain size in the composite was initially fine, but coarsened at the test temperatures; both dynamic and static grain growth were observed. The morphology of ceramic reinforcements appears to affect strongly the plastic deformation properties of Y-TZP. A comparison is made between the properties of monolithic Y-TZP, 20 wt. % Al2O3 particulate-reinforced Y-TZP (Al2O3/Y-TZP), and SiC/Y-TZP composites.

scholarly journals Mechanical Investigations of ASTM A36 Welded Steels with Stainless Steel Cladding

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 844
Author(s):  
Pavaret Preedawiphat ◽  
Numpon Mahayotsanun ◽  
Keerati Sa-ngoen ◽  
Mai Noipitak ◽  
Pongsak Tuengsook ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Service Life ◽  
Power Plants ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Internal Stresses ◽  
Welded Steel ◽  
Steel Pipes ◽  
Welding Processes ◽  
Weld Cladding

The in-service life of ASTM A36 welded steel pipes in power plants is often shortened by ash corrosion. During the heating condition, the ash deposition on the welded steel pipes gradually reduces the thickness of the pipes, thus, reducing the lifetime. Instead of replacing the pipes with new ones, the cost could be significantly reduced if the lifetime could be further extended. Weld cladding was the method selected in this study to temporarily extend the service life of welded pipes. This paper performed the mechanical investigations of A36—A36 welded steel plates after coating the surfaces with 309L stainless steel with a cladding method. The residual stress was also tested to observe the internal stresses developed during the welding processes of A36—A36 specimens. The comparison between the coated and non-coated surfaces of welded steels was performed by using the tensile tests (at room and elevated temperatures), corrosion (pitting corrosion, intergranular corrosion, and weight-loss corrosion) tests, and wear (shot blasting) tests. The life-extension of both coatings was evaluated based on the tensile tests and the corrosion and wear tests provided the qualitative evaluations of the coating performance. The results showed that surfaces coated by cladding could be used to temporarily extend the life of ASTM A36 welded steel under the studied conditions.

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