Estimation of resistance to ductile fracture of weldments at ambient and elevated temperatures from tensile tests

In this work, in order to predict the forming failure of AZ31 magnesium alloy sheet in drawing process at elevated temperatures, a series of square cup tests at various temperatures and FE analyses were carried out. The critical damage values and the mechanical properties dependent on strain rates and temperatures were evaluated from uniaxial tensile tests and those were utilized to the forming failure prediction using FE analysis. Based on the plastic deformation history obtained from FE analysis and Cockcroft and Latham’s ductile fracture criterion, the fracture initiation time and location were predicted and verified with the experimental results.

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A research on the effect of retrogression and re-aging heat treatment on hot tensile properties of AA7075 aluminum alloys

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4051436 ◽

2021 ◽

pp. 1-23

Author(s):

Talha Sunar ◽

Dursun Ozyurek

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Ductile Fracture ◽

Room Temperature ◽

Elevated Temperatures ◽

Xrd Analysis ◽

Tensile Tests ◽

Heat Treatments ◽

Tensile Behaviour ◽

Heat Treated

Abstract Aluminium alloys are preferred in most industries due to the functional properties they provide. It is known that alloys that can be processed with heat treatments shows better mechanical properties. 7xxx series alloys can be processed vi heat treatments and are often used in environmental conditions such as extreme temperatures and corrosive environments. Corrosive sensitivities such as stress corrosion cracking (SCC) can be observed with the effect of working conditions. It is known that retrogression and re-aging (RRA) heat treatment provide corrosion resistance and decrease the SCC velocity. The purpose of this study is to examine the tensile behaviour of annealed and retrogression-re-aging (RRA) heat treated AA7075 alloys at elevated temperatures. The mechanical properties of the alloys were investigated by conducting tensile tests at room temperature (RT), 100, 200, and 300°C. Hardness tests were performed at room temperature on the samples which were taken from tensile test specimens after tensile tests. The potential effects of test temperature on mechanical and microstructural properties were examined. The annealed and RRA heat treated alloys were characterized by scanning electron microscope (SEM), and X-ray diffraction (XRD) analysis. As a result, an increase in strength and hardness of the RRA treated AA7075 alloys was observed. Ductility of the RRA alloy was lower compared to the annealed AA7075 alloy. Fracture surface examinations showed that there was a semi-ductile fracture below 200°C and ductile fracture at temperatures of 200 and 300°C. Ductility was observed to increase with increasing temperature.

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Mechanical and thermal stability of retained austenite in plastically deformed bainite-based TRIP-aided medium-Mn steels

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-021-00284-6 ◽

2021 ◽

Vol 21 (3) ◽

Author(s):

Aleksandra Kozłowska ◽

Adam Grajcar ◽

Aleksandra Janik ◽

Krzysztof Radwański ◽

Ulrich Krupp ◽

...

Keyword(s):

Electron Microscopy ◽

Thermal Stability ◽

Retained Austenite ◽

Elevated Temperatures ◽

Mechanical Performance ◽

Mechanical Stability ◽

Electron Backscatter Diffraction ◽

Cost Effective ◽

Tensile Tests ◽

Thermal Stability Of

AbstractAdvanced medium-Mn sheet steels show an opportunity for the development of cost-effective and light-weight automotive parts with improved safety and optimized environmental performance. These steels utilize the strain-induced martensitic transformation of metastable retained austenite to improve the strength–ductility balance. The improvement of mechanical performance is related to the tailored thermal and mechanical stabilities of retained austenite. The mechanical stability of retained austenite was estimated in static tensile tests over a wide temperature range from 20 °C to 200 °C. The thermal stability of retained austenite during heating at elevated temperatures was assessed by means of dilatometry. The phase composition and microstructure evolution were investigated by means of scanning electron microscopy, electron backscatter diffraction, X-ray diffraction and transmission electron microscopy techniques. It was shown that the retained austenite stability shows a pronounced temperature dependence and is also stimulated by the manganese addition in a 3–5% range.

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Microstructure and Mechanical Properties of Ti-6Al-4V Manufactured by SLM

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.651-653.677 ◽

2015 ◽

Vol 651-653 ◽

pp. 677-682 ◽

Cited By ~ 33

Author(s):

Anatoliy Popovich ◽

Vadim Sufiiarov ◽

Evgenii Borisov ◽

Igor Polozov

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Phase Composition ◽

Mechanical Behavior ◽

Ductile Fracture ◽

Elevated Temperatures ◽

Initial Material ◽

Laser Melting ◽

Microstructure And Mechanical Properties ◽

Before And After

The article presents results of a study of phase composition and microstructure of initial material and samples obtained by selective laser melting of titanium-based alloy, as well as samples after heat treatment. The effect of heat treatment on microstructure and mechanical properties of specimens was shown. It was studied mechanical behavior of manufactured specimens before and after heat treatment at room and elevated temperatures as well. The heat treatment allows obtaining sufficient mechanical properties of material at room and elevated temperatures such as increase in ductility of material. The fractography of samples showed that they feature ductile fracture with brittle elements.

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Experimental Investigation of Ti-6Al-4V with a Biaxial Tensile Test Setup at Elevated Temperature

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.622-623.273 ◽

2014 ◽

Vol 622-623 ◽

pp. 273-278 ◽

Cited By ~ 1

Author(s):

Marion Merklein ◽

Sebastian Suttner ◽

Adam Schaub

Keyword(s):

Elevated Temperature ◽

Elevated Temperatures ◽

Tensile Tests ◽

Advanced Materials ◽

Uniaxial Tensile ◽

Plastic Yielding ◽

Characterization Methods ◽

Specific Strength ◽

Biaxial Tensile ◽

Stress States

The requirement for products to reduce weight while maintaining strength is a major challenge to the development of new advanced materials. Especially in the field of human medicine or aviation and aeronautics new materials are needed to satisfy increasing demands. Therefore the titanium alloy Ti-6Al-4V with its high specific strength and an outstanding corrosion resistance is used for high and reliable performance in sheet metal forming processes as well as in medical applications. Due to a meaningful and accurate numerical process design and to improve the prediction accuracy of the numerical model, advanced material characterization methods are required. To expand the formability and to skillfully use the advantage of Ti-6Al-4V, forming processes are performed at elevated temperatures. Thus the investigation of plastic yielding at different stress states and at an elevated temperature of 400°C is presented in this paper. For this reason biaxial tensile tests with a cruciform shaped specimen are realized at 400°C in addition to uniaxial tensile tests. Moreover the beginning of plastic yielding is analyzed in the first quadrant of the stress space with regard to complex material modeling.

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Enhancing the Thermal and Mechanical Characteristics of Polyvinyl Alcohol (PVA)-Hemp Protein Particles (HPP) Composites

International Polymer Processing ◽

10.1515/ipp-2020-3974 ◽

2021 ◽

Vol 36 (2) ◽

pp. 137-143

Author(s):

S. A. Awad

Keyword(s):

Mechanical Properties ◽

Elevated Temperatures ◽

Composite Films ◽

Tensile Tests ◽

Mechanical Analysis ◽

Decomposition Temperature ◽

Scanning Calorimetry ◽

Solution Casting Method ◽

Protein Particles

Abstract This paper aims to describe the thermal, mechanical, and surface properties of a PVA/HPP blend whereby the film was prepared using a solution casting method. The improvements in thermal and mechanical properties of HPP-based PVA composites were investigated. The characterization of pure PVA and PVA composite films included tensile tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results of TGA and DSC indicated that the addition of HPP increased the thermal decomposition temperature of the composites. Mechanical properties are significantly improved in PVA/HPP composites. The thermal stability of the PVA composite increased with the increase of HPP filler content. The tensile strength increased from 15.74 ± 0.72 MPa to 27.54 ± 0.45 MPa and the Young’s modulus increased from 282.51 ± 20.56 MPa to 988.69 ± 42.64 MPa for the 12 wt% HPP doped sample. Dynamic mechanical analysis (DMA) revealed that at elevated temperatures, enhanced mechanical properties because of the presence of HPP was even more noticeable. Morphological observations displayed no signs of agglomeration of HPP fillers even in composites with high HPP loading.

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Investigation on Mechanism of Ductile Fracture of AA5754 Sheet

Materials Science Forum ◽

10.4028/www.scientific.net/msf.519-521.985 ◽

2006 ◽

Vol 519-521 ◽

pp. 985-990 ◽

Cited By ~ 3

Author(s):

Ji Dong Kang ◽

David S. Wilkinson ◽

J. David Embury ◽

Khalid Hussain

Keyword(s):

Ductile Fracture ◽

Sample Surface ◽

Tensile Tests ◽

Direct Chill ◽

Mechanical Tests ◽

Strain Mapping ◽

Sequence Of Events ◽

Fe Content ◽

Cone Type ◽

Shear Process

A number of mechanical tests and metallographic techniques have been used to investigate the mechanism of ductile fracture of AA5754 sheet. The sequence of events in the development of shear localization is clarified using in situ strain mapping on both the sample surface and through thickness direction during tensile tests. It is observed that the failure mode changes from cup-cone type to shearing with increasing Fe content in both continuous cast (CC) and direct-chill cast (DC) AA5754 sheets. However, this transition happens in CC with much lower Fe content than DC. As very little damage is found near the fracture surface, this suggests that damage may be a consequence of the shear process rather than a trigger that determines material ductility. For both CC and DC with same Fe content of 0.21%, fracture strain of CC is much lower than DC. It is postulated that this is due to the differences of particle distribution in these two materials, especially the increased fraction of stringer type structures which exist in CC material.

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Flow Behaviour and Ductile Fracture Toughness of a High Toughness Steel

2004 International Pipeline Conference, Volumes 1, 2, and 3 ◽

10.1115/ipc2004-0192 ◽

2004 ◽

Cited By ~ 3

Author(s):

S. Xu ◽

R. Bouchard ◽

W. R. Tyson

Keyword(s):

Flow Stress ◽

Ductile Fracture ◽

Tensile Tests ◽

Test Method ◽

Opening Angle ◽

Absorbed Energy ◽

Crack Propagation Resistance ◽

High Toughness ◽

Drop Weight ◽

Drop Weight Tear Test

This paper reports results of tests on flow and ductile fracture of a very high toughness steel with Charpy V-notch absorbed energy (CVN energy) at room temperature of 471 J. The microstructure of the steel is bainite/ferrite and its strength is equivalent to X80 grade. The flow stress was determined using tensile tests at temperatures between 150°C and −147°C and strain rates of 0.00075, 0.02 and 1 s−1, and was fitted to a proposed constitutive equation. Charpy tests were carried out at an initial impact velocity of 5.1 ms−1 using drop-weight machines (maximum capacity of 842 J and 4029 J). The samples were not broken during the test, i.e. they passed through the anvils after significant bending deformation with only limited crack growth. Most of the absorbed energy was due to deformation. There was little effect of excess energy on absorbed energy up to 80% of machine capacity (i.e. the validity limit of ASTM E 23). As an alternative to the CVN energy, the crack tip opening angle (CTOA) measured using the drop-weight tear test (DWTT) has been proposed as a material parameter to characterize crack propagation resistance. Preliminary work on evaluating CTOA using the two-specimen CTOA test method is presented. The initiation energy is eliminated by using statically precracked test specimens. Account is taken of the geometry change of the specimens (e.g. thickening under the hammer) on the rotation factor and of the effect of strain rate on flow stress.

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Tensile Deformation and Fracture in a Bulk Nanostructured Al-5083/SiCp Composite at Elevated Temperatures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.29-30.245 ◽

2007 ◽

Vol 29-30 ◽

pp. 245-248

Author(s):

F. Tang ◽

B.Q. Han ◽

Masuo Hagiwara ◽

Julie M. Schoenung

Keyword(s):

Elevated Temperatures ◽

Tensile Deformation ◽

Tensile Tests ◽

Nanostructured Composite ◽

Sic Particles ◽

Deformation And Fracture ◽

Ultrafine Grained ◽

Al 5083 Alloy

An ultrafine-grained Al-5083 alloy reinforced with 5 vol.% nano-sized β-SiC particles was fabricated with a powder cryomilling and consolidation technique. Tensile tests were conducted at temperatures from 298 to 773 K for this composite. The mechanisms for deformation and fracture of this nanostructured composite at various temperatures are discussed.

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Fatigue responses of cracked Ti/APC-2 nanocomposite laminates at elevated temperature

Journal of Composite Materials ◽

10.1177/0021998319883928 ◽

2019 ◽

Vol 54 (13) ◽

pp. 1705-1715

Author(s):

MHR Jen ◽

GT Kuo ◽

YH Wu ◽

YJ Chen

Keyword(s):

Mechanical Properties ◽

Elevated Temperature ◽

Composite Laminates ◽

Elevated Temperatures ◽

Tensile Tests ◽

Cyclic Tests ◽

Constant Length ◽

Nano Powder ◽

Strength And Stiffness ◽

Inclined Angle

The mechanical properties and fatigue responses of Ti/APC-2 neat and nanocomposites with inclined single-edged cracks due to tensile and cyclic tests at elevated temperature were investigated. Two types of composite laminates [Ti/(0/90)s/Ti] were fabricated with and without (W/WO) nanoparticles SiO2 of optimal 1 wt.%. The geometry and dimensions of specimens were L × W × t = 240 × 25 × 1.55 mm3. The cracks were of constant length 3 mm and width 0.3 mm. The inclined angles were 0°, 45°, and 60°. Both the tensile and cyclic tests were conducted at elevated temperatures 25℃ (RT), 100℃, 125℃, and 150℃. From the tensile tests we obtained the load vs. displacement curves for both types of laminates with varied inclinations at elevated temperatures. Next, we received the applied load vs. cycles curves for the same laminates with inclined cracks at the corresponding temperature due to cyclic tests. According to the experimental data of both tensile and cyclic tests the mechanical properties, such as strength, stiffness, and life, decreased as the temperature rises. The greater the inclined angles were, the greater the strength and stiffness were. Similarly, the fatigue life was in the same trend. However, the effect of inclined angle on mechanical properties was more strong than those of temperature. The mechanical properties of nanocomposite laminates were higher than those of neat composite laminates, but not significant. The main reason was that the enhancement of spreading nano-powder silica on the laminate interfaces did not effectively eliminate the stress intensity at the crack tip locally.

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