scholarly journals Effect of Strain Rate and Loading Direction on the Mechanical Properties of Ni-Cr-Al Superalloy Foam Fabricated by Powder Alloying Method

2020 ◽  
Vol 58 (6) ◽  
pp. 375-382
Author(s):  
Kyu-Sik Kim ◽  
Jung-Suk Bae ◽  
Jae-Sung Oh ◽  
Kee-Ahn Lee
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Strain Rate ◽  
Structural Characteristics ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Average Pore ◽  
Tensile Direction ◽  
Loading Direction ◽  
Al Foam

The powder-alloyed metallic sheet foam manufacturing process has the advantage of being able to control pore shape, size, and distribution more easily and homogeneously than conventional foam manufacturing processes. The effects of strain rate and tensile direction on the mechanical properties of Ni-Cr-Al superalloy foam fabricated by powder alloying method were investigated. As a result of structural characteristics obtained by X-ray tomography and scanning electron microscopy, average pore sizes were measured to be 2762.4 μm (normal direction), 2709.1 μm (rolling direction, RD), and 2518.4 μm (transverse direction, TD) respectively. The γ-Ni matrix and γ’-Ni3Al (which was evenly distributed in the strut) were identified as the main constituent phases of the Ni-Cr-Al foam used in this study. Tensile tests were conducted with strain rates of 10<sup>−2</sup> ~ 10<sup>−4</sup> s<sup>−1</sup> along the rolling and transverse directions. The results showed that the tensile strength in the RD direction was 1.84~2.01 MPa, and in the TD direction was 1.2~1.27 MPa. The elongation in the TD direction was higher (30~36%) than in the RD direction (17~22%). It is noteworthy that the effect of quasi-static strain rate on the tensile strength and elongation was negligible. However, the loading direction was found to change mechanical properties significantly. This study also discussed the deformation behavior of the Ni-Cr-Al superalloy foam through observations of the fracture surface, and realtime observations during tensile tests in different directions.

The Precise Determination of the Johnson–Cook Material and Damage Model Parameters and Mechanical Properties of an Aluminum 7068-T651 Alloy

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
B. Bal ◽  
K. K. Karaveli ◽  
B. Cetin ◽  
B. Gumus
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Physical Simulation ◽  
Damage Model ◽  
Rolling Direction ◽  
Stress Triaxiality ◽  
Material Model ◽  
Tensile Tests ◽  
Model Parameters ◽  
Element Analysis

Al 7068-T651 alloy is one of the recently developed materials used mostly in the defense industry due to its high strength, toughness, and low weight compared to steels. The aim of this study is to identify the Johnson–Cook (J–C) material model parameters, the accurate Johnson–Cook (J–C) damage parameters, D1, D2, and D3 of the Al 7068-T651 alloy for finite element analysis-based simulation techniques, together with other damage parameters, D4 and D5. In order to determine D1, D2, and D3, tensile tests were conducted on notched and smooth specimens at medium strain rate, 100 s−1, and tests were repeated seven times to ensure the consistency of the results both in the rolling direction and perpendicular to the rolling direction. To determine D4 and D5 further, tensile tests were conducted on specimens at high strain rate (102 s−1) and temperature (300 °C) by means of the Gleeble thermal–mechanical physical simulation system. The final areas of fractured specimens were calculated through optical microscopy. The effects of stress triaxiality factor, rolling direction, strain rate, and temperature on the mechanical properties of the Al 7068-T651 alloy were also investigated. Damage parameters were calculated via the Levenberg–Marquardt optimization method. From all the aforementioned experimental work, J–C material model parameters were determined. In this article, J–C damage model constants, based on maximum and minimum equivalent strain values, were also reported which can be utilized for the simulation of different applications.

Fracture Behaviors of the Rolled Isotactic Polypropylene

2014 ◽  
Vol 529 ◽  
pp. 237-241
Author(s):  
Juan Jia ◽  
Shuang Xin Liu ◽  
Dierk Rabbe
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Isotactic Polypropylene ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Total Elongation ◽  
Tensile Fracture ◽  
Tensile Sample ◽  
Fracture Surfaces ◽  
Fracture Behaviors

The mechanical properties of the rolled isotactic polypropylene and the morphology of fracture surfaces were measured and observed by tensile tests and the scanning electron microscopy. And then the tensile fracture behaviors along the rolling and transvers directions of the rolled samples were analyzed. After rolling, strong anisotropy mechanical properties occurred along the rolling and transverse directions: high tensile strength with low total elongation along the rolling direction and low tensile strength with high total elongation along the transverse direction. After tensile test, three characteristic structures were found on the fracture surfaces. The tensile fracture behavior of the rolled samples is: stress concentration happens on the edge of tensile sample and then fracture develops to the center part of the tensile sample. When the fracture is big enough, the tensile sample will be failed very quickly.

scholarly journals Asymmetry in the Mechanical Properties of Block Ni-Cr-Al Superalloy Foam Fabricated by the Combination of Powder Alloying and Hot Rolling Processes

2020 ◽  
Vol 58 (2) ◽  
pp. 103-111
Author(s):  
Kyu-Sik Kim ◽  
Min-Chul Shim ◽  
Man-Ho Park ◽  
Jung-Yeul Yun ◽  
Kee-Ahn Lee
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Tensile Properties ◽  
Hot Rolling ◽  
Structural Characteristics ◽  
Average Pore Size ◽  
Rolling Direction ◽  
Structural Features ◽  
Compressive Yield Strength ◽  
Average Pore

A block Ni-Cr-Al superalloy foam with dimensions of 300 mm (width direction, WD) × 500 mm (rolling direction, RD) × 60 mm (normal direction, ND) was fabricated using powder alloying, multi-sheet stacking, and hot rolling processes. The structural characteristics, microstructure, and mechanical asymmetry of the block Ni-based foam were investigated. Analysis of the structural features showed that the interfaces between the sheets had complex strut interactions, such as contacted (deformed) and intersected struts. The average pore size along the directions was measured to be 2569.6 μm (WD), 2988.1 μm (RD), and 2493.2 μm (ND). The average thickness of the strut was 340.8 μm, and the wall thickness of the strut was 27.7 μm. The elemental distributions in the struts were uniformly controlled, and the block foam consisted of γ (matrix) and γ ' (Ni<sub>3</sub>Al) phases. Tensile properties in the ND direction showed a yield strength of 0.175 MPa, tensile strength of 0.233 MPa, and elongation of 2.54%, while the tensile properties in the RD direction were 1.27 MPa (YS), 3.01 MPa (UTS), 8.92% (El.) respectively. The foam was observed to have a compressive yield strength of 0.795 MPa in the ND direction, and that of 2.18 MPa in the RD direction were obtained. The asymmetry and anisotropy of these mechanical properties could be explained by the difference in pore sizes along the direction, and the structural characteristics of the sheet interface generated by sheet stacking and rolling.

scholarly journals Influence of Hydrostatic Extrusion on the Mechanical Properties of the Model Al-Mg Alloys

2021 ◽  
Author(s):  
Aleksandra Towarek ◽  
Wojciech Jurczak ◽  
Joanna Zdunek ◽  
Mariusz Kulczyk ◽  
Jarosław Mizera
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Tensile Strength ◽  
Microstructural Analysis ◽  
Tensile Tests ◽  
Hydrostatic Extrusion ◽  
Microstructure Formation ◽  
Initial State ◽  
Degree Of Deformation ◽  
Al Mg Alloys

AbstractTwo model aluminium-magnesium alloys, containing 3 and 7.5 wt.% of Mg, were subjected to plastic deformation by means of hydrostatic extrusion (HE). Two degrees of deformation were imposed by two subsequent reductions of the diameter. Microstructural analysis and tensile tests of the materials in the initial state and after deformation were performed. For both materials, HE extrusion resulted in the deformation of the microstructure—formation of the un-equilibrium grain boundaries and partition of the grains. What is more, HE resulted in a significant increase of tensile strength and decrease of the elongation, mostly after the first degree of deformation.

scholarly journals Directionally-Dependent Mechanical Properties of Ti6Al4V Manufactured by Electron Beam Melting (EBM) and Selective Laser Melting (SLM)

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3603
Author(s):  
Tim Pasang ◽  
Benny Tavlovich ◽  
Omry Yannay ◽  
Ben Jakson ◽  
Mike Fry ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Electron Beam Melting ◽  
Rolling Direction ◽  
Laser Melting ◽  
Plate Rolling

An investigation of mechanical properties of Ti6Al4V produced by additive manufacturing (AM) in the as-printed condition have been conducted and compared with wrought alloys. The AM samples were built by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) in 0°, 45° and 90°—relative to horizontal direction. Similarly, the wrought samples were also cut and tested in the same directions relative to the plate rolling direction. The microstructures of the samples were significantly different on all samples. α′ martensite was observed on the SLM, acicular α on EBM and combination of both on the wrought alloy. EBM samples had higher surface roughness (Ra) compared with both SLM and wrought alloy. SLM samples were comparatively harder than wrought alloy and EBM. Tensile strength of the wrought alloy was higher in all directions except for 45°, where SLM samples showed higher strength than both EBM and wrought alloy on that direction. The ductility of the wrought alloy was consistently higher than both SLM and EBM indicated by clear necking feature on the wrought alloy samples. Dimples were observed on all fracture surfaces.

scholarly journals Mimicking the Mechanical Properties of Aortic Tissue with Pattern-Embedded 3D Printing for a Realistic Phantom

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5042
Author(s):  
Jaeyoung Kwon ◽  
Junhyeok Ock ◽  
Namkug Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
3D Printing ◽  
Mechanical Characteristics ◽  
Aortic Wall ◽  
Tensile Tests ◽  
Human Aorta ◽  
Aortic Tissue ◽  
Medical Field ◽  
Base Materials

3D printing technology has been extensively applied in the medical field, but the ability to replicate tissues that experience significant loads and undergo substantial deformation, such as the aorta, remains elusive. Therefore, this study proposed a method to imitate the mechanical characteristics of the aortic wall by 3D printing embedded patterns and combining two materials with different physical properties. First, we determined the mechanical properties of the selected base materials (Agilus and Dragonskin 30) and pattern materials (VeroCyan and TPU 95A) and performed tensile testing. Three patterns were designed and embedded in printed Agilus–VeroCyan and Dragonskin 30–TPU 95A specimens. Tensile tests were then performed on the printed specimens, and the stress-strain curves were evaluated. The samples with one of the two tested orthotropic patterns exceeded the tensile strength and strain properties of a human aorta. Specifically, a tensile strength of 2.15 ± 0.15 MPa and strain at breaking of 3.18 ± 0.05 mm/mm were measured in the study; the human aorta is considered to have tensile strength and strain at breaking of 2.0–3.0 MPa and 2.0–2.3 mm/mm, respectively. These findings indicate the potential for developing more representative aortic phantoms based on the approach in this study.

scholarly journals New Approach In The Properties Evaluation Of Ultrafine-Grained OFHC Copper

2015 ◽  
Vol 60 (2) ◽  
pp. 605-614 ◽  
Author(s):  
T. Kvačkaj ◽  
A. Kováčová ◽  
J. Bidulská ◽  
R. Bidulský ◽  
R. Kočičko
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Tensile Tests ◽  
Coarse Grained ◽  
Wear Behaviour ◽  
Ofhc Copper ◽  
Strain Rates ◽  
Ultrafine Grained ◽  
Reduction Of Area ◽  
Pin On Disk

AbstractIn this study, static, dynamic and tribological properties of ultrafine-grained (UFG) oxygen-free high thermal conductivity (OFHC) copper were investigated in detail. In order to evaluate the mechanical behaviour at different strain rates, OFHC copper was tested using two devices resulting in static and dynamic regimes. Moreover, the copper was subjected to two different processing methods, which made possible to study the influence of structure. The study of strain rate and microstructure was focused on progress in the mechanical properties after tensile tests. It was found that the strain rate is an important parameter affecting mechanical properties of copper. The ultimate tensile strength increased with the strain rate increasing and this effect was more visible at high strain rates$({\dot \varepsilon} \sim 10^2 \;{\rm{s}}^{ - 1} )$. However, the reduction of area had a different progress depending on microstructural features of materials (coarse-grained vs. ultrafine-grained structure) and introduced strain rate conditions during plastic deformation (static vs. dynamic regime). The wear behaviour of copper was investigated through pin-on-disk tests. The wear tracks examination showed that the delamination and the mild oxidational wears are the main wear mechanisms.

Transferability of the Gurson Damage Model Parameters with Charpy and Tensile Tests with Different Constrain Level

2009 ◽  
Vol 65 ◽  
pp. 19-31
Author(s):  
Ruben Cuamatzi-Melendez ◽  
J.R. Yates
Keyword(s):  
Strain Rate ◽  
Damage Model ◽  
Rolling Direction ◽  
Fracture Initiation ◽  
Tensile Tests ◽  
Model Parameters ◽  
Gurson Model ◽  
Finite Element Program ◽  
Element Program ◽  
Gurson's Model

Little work has been published concerning the transferability of Gurson’s ductile damage model parameters in specimens tested at different strain rates and in the rolling direction of a Grade A ship plate steel. In order to investigate the transferability of the damage model parameters of Gurson’s model, tensile specimens with different constraint level and impact Charpy specimens were simulated to investigate the effect of the strain rate on the damage model parameters of Gurson model. The simulations were performed with the finite element program ABAQUS Explicit [1]. ABAQUS Explicit is ideally suited for the solution of complex nonlinear dynamic and quasi–static problems [2], especially those involving impact and other highly discontinuous events. ABAQUS Explicit supports not only stress–displacement analyses but also fully coupled transient dynamic temperature, displacement, acoustic and coupled acoustic–structural analyses. This makes the program very suitable for modelling fracture initiation and propagation. In ABAQUS Explicit, the element deletion technique is provided, so the damaged or dead elements are removed from the analysis once the failure criterion is locally reached. This simulates crack growth through the microstructure. It was found that the variation of the strain rate affects slightly the value of the damage model parameters of Gurson model.

scholarly journals Experimental Investigation into Corrosion Effect on Mechanical Properties of High Strength Steel Bars under Dynamic Loadings

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hui Chen ◽  
Jinjin Zhang ◽  
Jin Yang ◽  
Feilong Ye
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Dynamic Loading ◽  
High Strength Steel ◽  
High Strength ◽  
Tensile Tests ◽  
Reinforcing Steel ◽  
Test Results ◽  
Cross Sectional ◽  
Steel Bars

The tensile behaviors of corroded steel bars are important in the capacity evaluation of corroded reinforced concrete structures. The present paper studies the mechanical behavior of the corroded high strength reinforcing steel bars under static and dynamic loading. High strength reinforcing steel bars were corroded by using accelerated corrosion methods and the tensile tests were carried out under different strain rates. The results showed that the mechanical properties of corroded high strength steel bars were strain rate dependent, and the strain rate effect decreased with the increase of corrosion degree. The decreased nominal yield and ultimate strengths were mainly caused by the reduction of cross-sectional areas, and the decreased ultimate deformation and the shortened yield plateau resulted from the intensified stress concentration at the nonuniform reduction. Based on the test results, reduction factors were proposed to relate the tensile behaviors with the corrosion degree and strain rate for corroded bars. A modified Johnson-Cook strength model of corroded high strength steel bars under dynamic loading was proposed by taking into account the influence of corrosion degree. Comparison between the model and test results showed that proposed model properly describes the dynamic response of the corroded high strength rebars.

scholarly journals Effects of Different Solid Solution Temperatures on Microstructure and Mechanical Properties of the AA7075 Alloy After T6 Heat Treatment

2019 ◽  
Vol 38 (2019) ◽  
pp. 892-896 ◽  
Author(s):  
Süleyman Tekeli ◽  
Ijlal Simsek ◽  
Dogan Simsek ◽  
Dursun Ozyurek
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solid Solution ◽  
Tensile Strength ◽  
Tensile Tests ◽  
Solution Temperature ◽  
T6 Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
Different Temperatures

AbstractIn this study, the effect of solid solution temperature on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment was investigated. Following solid solution at five different temperatures for 2 hours, the AA7075 alloy was quenched and then artificially aged at 120∘C for 24 hours. Hardness measurements, microstructure examinations (SEM+EDS, XRD) and tensile tests were carried out for the alloys. The results showed that the increased solid solution temperature led to formation of precipitates in the microstructures and thus caused higher hardness and tensile strength.

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