scholarly journals Quantitative Research on the Effect of Natural Aging on the Mechanical Properties and Bake Hardening Properties of AA6014 Alloy within Six Months

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 673
Author(s):  
Zhengwei Gu ◽  
Yuting Han ◽  
Ziming Tang ◽  
Lingling Yi ◽  
Ge Yu
Keyword(s):  
Mechanical Properties ◽  
Quantitative Research ◽  
Rolling Direction ◽  
Natural Aging ◽  
Tensile Tests ◽  
Strain Hardening Exponent ◽  
Bake Hardening ◽  
Microscopic Mechanism ◽  
N Value ◽  
Offset Yield Strength

This article is dedicated to quantitatively and systematically revealing the changes of mechanical properties and bake hardening properties of AA6014 alloy during six-month natural aging in detail. Three directions (0, 45, and 90° relative to the rolling direction) of the aluminum alloy sheets and 16 time points within six months were selected to conduct experiments. The change trend of six mechanical properties (0.2% offset yield strength, ultimate tensile strength, plastic extension at maximum force, elongation after fracture, and strain hardening exponent) were obtained by a large number of micro-hardness measurements and tensile tests. The results show that elongations along the three directions are basically the same and do not drop significantly with the progress of natural aging but fluctuate within a certain range. The trends of the n value during natural aging before and after bake hardening are opposite and bake hardening leads to ~0.07 decrease of the n value. The PLC phenomenon disappears after 90 days of natural aging, and the yield strengths along the three directions also stabilize; thus, it can be inferred that the cluster changes tend to stabilize after 90 days natural aging. The large and systematic dataset are clearly and intuitively presented, which can not only be used to provide data reference for industrial production of automobile manufacturers but also be used to reveal the microscopic mechanism of the natural aging process.

Quantitatively Investigate the Effects of Natural Aging on Mechanical Properties and Bake Hardening Behaviors of Al-Mg-Si Alloys

2021 ◽  
Vol 1032 ◽  
pp. 157-162
Author(s):  
Zheng Wei Gu ◽  
Yu Ting Han ◽  
Zi Ming Tang ◽  
Ge Yu
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Rolling Direction ◽  
Natural Aging ◽  
Strain Hardening Exponent ◽  
Detailed Data ◽  
Bake Hardening ◽  
Percentage Elongation ◽  
Offset Yield Strength ◽  
Aging Period

The effect of natural aging on mechanical properties and bake hardening behaviors of Al-Mg-Si alloys was quantitatively investigated by a series of tensile experiments along the rolling direction. The natural aging period is from three days to three months after heat treatment. As the results, within three months, along the rolling direction, 0.2% offset yield strength and ultimate tensile strength respectively increased from 97 MPa to 145 MPa, 210 MPa to 248 MPa. The strain hardening exponent n-value and the increment of yield strength after bake hardening respectively decreased from 0.2804 to 0.2186, 127 MPa to 89 MPa. The percentage elongation after fracture varies from 22% to 24% during natural aging and varies from 13% to 16% after bake hardening. A large amount of detailed data has been given, which quantitatively describes the change in mechanical properties and bake hardening behaviors of Al-Mg-Si alloys during natural aging.

Mechanical Properties at Elevated Temperatures of an S304H-Type Austenitic Stainless Steel Processed by Warm Rolling

2014 ◽  
Vol 922 ◽  
pp. 844-849 ◽  
Author(s):  
Zhanna Yanushkevich ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Warm Rolling ◽  
Rolling Temperature ◽  
Offset Yield Strength

The effect of multiple warm to hot rolling in the temperature interval of 673 – 1273 K on the microstructures and mechanical properties of an S304H-type austenitic stainless steel was studied. The structural changes during multiple rolling are characterized by the elongation of original grains towards the rolling direction and the development of new fine grains. The average spacing between high-angle boundaries in the transverse section of the rolled samples decreases from about 0.95 to 0.4 μm with decrease in the rolling temperature from 1273 to 773 K. The multiple rolling leads to significant strengthening as revealed by tensile tests at ambient and elevated temperatures. The offset yield strength evaluated at ambient temperature increased from 480 to 1120 MPa, while the rolling temperature decreased from 1273 to 673 K. The effect of the rolling temperature on the strength becomes less pronounced with an increase of the temperature of tensile tests.

scholarly journals Effect of Dissolution of η′ Precipitates on Mechanical Properties of A7075-T6 Alloy

2022 ◽  
Vol 60 (1) ◽  
pp. 83-93
Author(s):  
Young-We Kim ◽  
Yong-Hee Jo ◽  
Yun-Soo Lee ◽  
Hyoung-Wook Kim ◽  
Je-In Lee
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Solution Treatment ◽  
Aluminum Matrix ◽  
Natural Aging ◽  
Aging Treatment ◽  
Nucleation Site ◽  
Treatment Temperature ◽  
Solution Treatment Temperature ◽  
Bake Hardening

The effects of dissolution of the η′ phase by solution treatment on the mechanical properties of A7075-T6 alloy were investigated. Immediately after solution treatment of the T6 sheet at 450 oC or higher, elongation significantly increased and dissolution of the η′ phase occurred. η′ is the main hardening phase. After natural-aging, GPI, which is coherent with the aluminum matrix, was formed and strength increased. When bake hardening after natural-aging was performed, the yield strength slightly increased due to partial dissolution of the GPI and re-precipitation of the η′ phase. In contrast, after solution treatment at 400 oC, there was less elongation increase due to the precipitation of the coarse η phase at grain boundaries and low dissolution of the η′ phase. In addition, when bake hardening after natural-aging was performed, the yield strength decreased due to insufficient GPI, which is the nucleation site of the η′ phase. To promote reprecipitation of the η′ phase, the solution treatment temperature was set to a level that would increase solubility. As a result, the yield strength was significantly increased through re-precipitation of a large number of fine and uniform η′ phase. In addition, to increase the effect of dissolution, a pre-aging treatment was introduced and the bake hardenability can be improved after dissolution.

scholarly journals Anisotropy Study of Inconel 718 alloy at Sub-Zero temperatures

2020 ◽  
Vol 184 ◽  
pp. 01004
Author(s):  
L Jayahari ◽  
K Nagachary ◽  
Chandra Ch Sharath ◽  
SM Hussaini
Keyword(s):  
Mechanical Properties ◽  
Strain Hardening ◽  
Inconel 718 ◽  
Anisotropy Parameter ◽  
Tensile Tests ◽  
Strain Hardening Exponent ◽  
Inconel 718 Alloy ◽  
Normal Anisotropy ◽  
Axial Tensile ◽  
Forming Characteristics

There is an increase in demand for new alloys in aerospace, power generation and nuclear industries. Nickel Based super alloys are known for having distinctive properties which are best suitable for these industries. In this study Nickel based super alloy Inconel 718, is used. Over the many years of intense research and development, these alloys have seen considerable evolution in their properties and efficiency. Behaviour of materials and its forming characteristics can be precisely analysed by determining anisotropic behaviour and mechanical properties. In the present study, tried to analyse the mechanical properties of Inconel 718 like yield strength (Ys), ultimate tensile strength (UTS), strain hardening exponent (n) and strain hardening coefficient (k). Uni-axial tensile tests were conducted on specimens with various parameters such as orientations, temperature and Strain rate. Anisotropy of Inconel 718 alloy was measured based on measurable parameters. The normal anisotropy parameter (f) and planer anisotropy (Δr) were measured and observed that the anisotropy parametres are incresed with the decrease in temperature.

Effect of Fast Annealing on Microstructure and Mechanical Properties of Non-Oriented Al-Si Low C Electrical Steels

2007 ◽  
Vol 560 ◽  
pp. 29-34 ◽  
Author(s):  
Emmanuel Gutiérrez C. ◽  
Armando Salinas-Rodríguez ◽  
Enrique Nava-Vázquez
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Room Temperature ◽  
Tensile Tests ◽  
Rate Of Change ◽  
Uniaxial Tensile ◽  
Electrical Steels ◽  
Offset Yield Strength ◽  
Microstructure And Mechanical Properties ◽  
Increasing Temperature

The effects of heating rate and annealing temperature on the microstructure and mechanical properties of cold rolled Al-Si, low C non-oriented electrical steels are investigated using SEM metallography and uniaxial tensile tests. The experimental results show that short term annealing at temperatures up to 850 °C result in microstructures consisting of recrystallized ferrite grains with sizes similar to those observed in industrial semi-processed strips subjected to long term batch annealing treatments. Within the temperature range investigated, the grain size increases and the 0.2% offset yield strength decreases with increasing temperature. It was observed that the rate of change of grain size with increasing temperature increases when annealing is performed at temperatures greater than Ac1 (~870 °C). This effect is attributed to Fe3C dissolution and rapid C segregation to austenite for annealing temperatures within the ferrite+austenite phase field. This leads to faster ferrite growth and formation of pearlite when the steel is finally cooled to room temperature. The presence of pearlite at room temperature decreases the ductility of samples annealed at T > Ac1.

Fatigue Properties of Al-Li Plates Joined by Friction Stir Welding

2008 ◽  
Vol 385-387 ◽  
pp. 849-852 ◽  
Author(s):  
Pasquale Cavaliere ◽  
Francesco W. Panella ◽  
Antonio Squillace
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Testing Machine ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Control Mode ◽  
Fatigue Properties ◽  
Amplitude Control ◽  
Friction Stir

Al-Li alloys are characterized by a strong anisotropy in mechanical properties and microstructure with respect to the rolling direction. Plates of 2198 Al-Li alloy were friction stir welded by employing maximum rotation speed: 1000 rev/min and welding speed of 80 mm/min, both in parallel and orthogonal directions with respect to the rolling one. The joints mechanical properties were evaluated by means of tensile tests at room temperature. In addition, fatigue tests performed with a resonant electro-mechanical testing machine under constant amplitude control up to 250 Hz loading, were conducted in axial control mode with R(σmin/σmax)=0.33, for all the welding and rotating speed conditions. The fatigue crack propagation experiments were performed by employing single edge notched specimens.With the aim to characterize the weld performances, both the microstructure evolution at jointed cross sections, related to the welding variables, and the fractured surfaces were respectively analyzed by means of optical and scanning electron microscopy.

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.

scholarly journals Comparative Study on the Effects of Various Modified Admixtures on the Mechanical Properties of Styrene-Acrylic Emulsion-Based Cement Composite Materials

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 8 ◽  
Author(s):  
Tengjiao Wang ◽  
Jinyu Xu ◽  
Congjin Zhu ◽  
Weibo Ren
Keyword(s):  
Mechanical Properties ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Aluminium Oxide ◽  
Cement Composite ◽  
Tensile Tests ◽  
Hydration Reaction ◽  
Microscopic Mechanism ◽  
Acrylic Emulsion ◽  
Silane Coupling

This study carried out tensile tests at definite elongation, tensile and shear tests on 4 admixture-modified styrene-acrylic emulsion-based cement composites (SECCs), and measured the strength, deformation, and energy consumption indexes of test specimens, so as to investigate the influences of coalescing agent, plasticizer, silane coupling agent, and nanometer aluminium oxide on the bond, tensile, and shear mechanical properties of the test specimens. Additionally, the Field Emission Scanning Electron Microscope (FE-SEM) test and Mercury Intrusion Porosimetry (MIP) test were conducted on the composite material specimens, to analyze the microscopic mechanism of different admixtures in modifying the mechanical properties of the SECC. The results suggested that the addition of coalescing agent, plasticizer, silane coupling agent, and nanometer aluminium oxide improved the bond, tensile and shear properties of the SECC specimens to various degrees. Of them, the coalescing agent promoted the mutual cross-linking of organic polymers with inorganic products, and optimized the transition interface to enhance the comprehensive mechanical properties of the test specimens; by contrast, nanometer aluminium oxide developed secondary hydration reaction with the inorganic products, and refined the pore structure to modify the mechanical properties of test specimens. Therefore, both of them achieved significant modification effects. Typically, the optimal bond properties of FFAMC, PLMC, SCAMC, and NAMC test specimens were achieved at the coalescing agent, plasticizer, silane coupling agent, and nanometer aluminium oxide addition amounts of 4%, 1.5%, 3%, and 1%, respectively. Besides, the improving effects of different admixtures on the tensile property of SECC specimens followed the order of coalescing agent > nanometer aluminium oxide > plasticizer > silane coupling agent, with the optimal addition amounts of 4%, 1.5%, 1%, and 2%, respectively. In addition, the improving effects of different admixtures on the shear performance of SECC specimens followed the order of coalescing agent > nanometer aluminium oxide > silane coupling agent > plasticizer, with the optimal addition amounts of 4%, 1.5%, 1%, and 1%, respectively.

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 Recrystallization and Mechanical Behavior of High Mn and Low C Cold Rolled and Annealed Steel with TWIP Effect

2012 ◽  
Vol 715-716 ◽  
pp. 579-584 ◽  
Author(s):  
Dagoberto Brandao Santos ◽  
Berenice Mendonça Gonzalez ◽  
Elena V. Pereloma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Driving Force ◽  
Vickers Microhardness ◽  
Tensile Tests ◽  
Total Elongation ◽  
Strain Hardening Exponent ◽  
Twip Steels ◽  
Cold Rolled ◽  
Annealed Steel

ncreasing demand for automotive vehicles with reduced weight, improved crashworthiness and passengers safety has steamed the research of new Twinning Induced Plasticity (TWIP) steels. In this work the effect of annealing between 400 and 900°C on the microstructure and mechanical properties of hot and cold rolled 0.06C-24Mn-3Al-2Si-1Ni (wt%) steel with TWIP effect was investigated. The results have shown that steel exhibits fast recrystallization kinetics with a low amount of recovery, which results in a high driving force for the former. Mechanical properties were determined using Vickers microhardness and tensile tests. Tensile strength of 670 MPa with 54% of total elongation, and strain hardening exponent of 0.57 were reached after annealing at 900°C.

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