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.

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.

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.

STUDY ON THE INFLUENCE LAWS OF MECHANICAL PROPERTIES ON STIFFNESS OF AUTOMOTIVE BODY PANELS

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1634-1639 ◽  
Author(s):  
LIHONG ZHAO ◽  
SHUYONG JIANG ◽  
ZHENG YI REN ◽  
HAIPING YU ◽  
YUYING YANG
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Strain Hardening ◽  
Shallow Shell ◽  
Anisotropy Parameter ◽  
Weight Coefficient ◽  
Great Accuracy ◽  
Strain Hardening Exponent ◽  
Forming Process ◽  
Auto Body

The criterion and research technique of auto body panels stiffness are introduced in this work, and the finite element models (FEM) of cylindrical shallow shell that could represent auto body panels are established. Simulations of forming, springback and stiffness on cylindrical shallow shell are carried out. The simulations show great accuracy with the experimental results. Extensive simulated results of the influence laws of material mechanical properties on stiffness are achieved, such as yield strength, strain-hardening exponent, Young's modulus, anisotropy parameter and strength coefficient. With comparison of the weight coefficient of material mechanical properties on stiffness, it can be concluded that the Yong's modulus, strain-hardening exponent and yield strength are key influencing factors of stiffness. With the analysis of distribution of the strain after cylindrical shallow shell forming, plastic deformation during the forming process resulting in work-hardening of the material is one of the main reasons for increasing stiffness.

Effects of Post Weld Heat Treatments (PWHT) on Friction Stir Welded AA2219-T87 Joints

2017 ◽  
Author(s):  
Mohammad W. Dewan ◽  
Muhammad A. Wahab ◽  
Khurshida Sharmin
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloys ◽  
Yield Strength ◽  
Solution Treatment ◽  
Welding Process ◽  
Alloying Elements ◽  
Age Hardening ◽  
Experimental Program ◽  
Friction Stir ◽  
Aging Period

Friction Stir Welding (FSW) offers significantly better performance on aluminum alloy joints compared to the conventional fusion arc welding techniques; however, plastic deformation, visco-plastic flow of metals, and complex non-uniform heating cycles during FSW processes, result in dissolution of alloying elements, intrinsic microstructural changes, and post-weld residual stress development. As a consequence, about 30% reduction in ultimate strength (UTS) and 60% reduction in yield strength (YS) were observed in defect-free, as-welded AA2219-T87 joints. PWHT is a common practice to refine grain-coarsened microstructures which removes or redistributes post-weld residual stresses; and improves mechanical properties of heat-treatable welded aluminum alloys by precipitation hardening. An extensive experimental program was undertaken on PWHT of FS-welded AA2219-T87 to obtain optimum PWHT conditions and improvement of the tensile properties. Artificial age-hardening (AH) helped in the precipitation of supersaturated alloying elements produced around weld nugget area during the welding process. As a result, an average 20% improvement in YS and 5% improvements in UTS was observed in age-hardened (AH-170°C-18h) specimens as compared to AW specimens. To achieve full benefit of PWHT, solution-treatment followed by age-hardening (STAH) was performed on FS-welded AA2219-T87 specimens. Solution-treatment (ST) helps in the grain refinement and formation of supersaturated precipitates in aluminum alloys. Age-hardening of ST specimens help in the precipitation of alloying elements around grain boundaries and strengthen the specimens. Optimum aging period is important to achieve better mechanical properties. For FS-welded AA2219-T87 peak aging time was 5 hours at 170°C. STAH-170°C -5h treated specimens showed about 78% JE based on UTS, 61% JE based on yield strength, and 36% JE based on tensile toughness values of base metal.

Investigation of the Effect of Heating-Lines on Tensional Mechanical Properties of Sheet Metal after Laser Forming

2011 ◽  
Vol 117-119 ◽  
pp. 1666-1671
Author(s):  
Ai Hui Luo ◽  
Wen Jiao Dan ◽  
Wei Gang Zhang
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Strength ◽  
Sheet Metal ◽  
Heat Affected Zone ◽  
Total Elongation ◽  
Laser Forming ◽  
Strain Hardening Exponent ◽  
Elongation Index ◽  
Hardening Coefficient

In this study，tensional mechanical properties of sheet metal with different heating-lines after laser forming are investigated. The basic mechanical properties of material (such as elastic modulus, yield strength, ultimate strength, TEI (total elongation index) and EIU (elongation index of uniform)) with different spacing between neighbored heating-lines and different heating-lines number are presented. The stress-strain curves are complied with a modified Swift law, where the hardening coefficient and strain hardening exponent of material are controlled by strain. The influence of heating-lines number on tensional mechanical properties of material is greater than that of the spacing between neighbored heating-lines. The results show that all mechanical properties are related to the distribution of microstructure in heat-affected zone after laser forming.

Study on the Variation of the Properties with Increasing of Bending Cycles of Coiled Tubing

2010 ◽  
Vol 146-147 ◽  
pp. 1369-1374
Author(s):  
Zong Yue Bi ◽  
Lin Yun Xian ◽  
Xiao Tian Jing
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Strain Hardening ◽  
Strain Hardening Exponent ◽  
Cycle Fatigue ◽  
Coiled Tubing ◽  
The One ◽  
Changing Tendency

The Variation of the mechanical properties of coiled tubing with increasing of the bending cycles was studied based on the fatigue bending cycle machine. The results show that the tensile strength had no significance changes during cycle fatigue. The yield strength and the force value was significantly decreased after 300 cycles, and the corresponding decreased magnitude linearly increased with the increasing of bending cycles. The changing tendency of strain hardening exponent on compression surface is different from the one on extruded surface. When the cycles increase from 100 to 600, the exponent on compression surface shows increases firstly, and decreases afterwards, However, the one on extruded surface shows decreases firstly, and increases afterwards. The yield strengths of the compression surface and extruded surface show the same changing tendency as strain hardening exponent.

Evaluation and Characterization of ASS316L at Sub-Zero Temperature

2019 ◽  
Author(s):  
Satyanarayana Kosaraju ◽  
Anil Kalluri ◽  
Swadesh Kumar Singh ◽  
Ahsan ul Haq
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Strain Hardening ◽  
Process Parameters ◽  
Salt Water ◽  
Strain Hardening Exponent

Abstract Austenitic Stainless-Steel grade 316L is one among the significant ASS grades which is most commonly used in various industry sectors. It has excellent corrosion resistance in ordinary atmospheric and also in more arduous environments such as salt water and environments where resistance to chloride corrosion is required. Whilst performing well when exposed to relatively high temperatures, this grade of Austenitic Stainless steel also maintains its strength and toughness at sub-zero temperatures, making this an excellent choice for various applications in industries sectors such as Marine, general construction, and water treatment. Therefore, present study focused on evaluating the mechanical properties such as ultimate tensile strength (UTS), yield strength (YS) and strain hardening exponent (n) are evaluated based on the experimental data obtained from the uniaxial isothermal tensile tests performed at an interval of −25 °C from 0 °C to −50 °C and at three orientations (0, 45, 90) degrees to the rolling direction and cross head velocity (3, 5, 7) mm/min were chosen. A total of 27 experiments have been planned based on design of experiments to conduct experiments. A mathematical model for the prediction of ultimate tensile strength (UTS), yield strength (YS) and strain hardening exponent (n) was developed using process parameters such as temperature, orientation and cross head velocities. Results have shown that mechanical properties can be predicted with a reasonable accuracy within the range of process parameters considered in this study.

Influence of Crystallographic Texture on Mechanical Properties in Cold Rolled 7XXX Series Al Alloys Used in Space Applications

2012 ◽  
Vol 710 ◽  
pp. 539-544 ◽  
Author(s):  
P. Ramesh Narayanan ◽  
Satyam Suwas ◽  
K. Sreekumar ◽  
Parameshwar Prasad Sinha ◽  
Srinivasa Ranganathan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Crystallographic Texture ◽  
Shear Banding ◽  
Rolling Direction ◽  
The Other ◽  
Space Applications ◽  
Plastic Strain Ratio

This paper covers the influence of crystallographic texture on the mechanical properties in two of the most important high strength Al-Zn-Mg family of aluminium alloys, viz., AA7075 and AFNOR7020 alloys, used in the Aerospace industry. AFNOR7020 Alloy developed a stronger texture compared to the other two alloys. S component of texture is stronger in AA7075 alloy whereas the Bs component is stronger in AFNOR7020 alloy. This is attributed to the shear banding which was found absent in the other alloy. The starting material, AA7075 in T7352 condition and AFNOR7020 in T652 condition show some degree of anisotropy of mechanical properties with regard to yield strength and ultimate tensile strength. Higher degree of deformation leads to more pronounced anisotropy in mechanical properties with regard to yield strength and ultimate tensile strength, with a maxima along the transverse direction. For the alloys, experimentally measured Plastic Strain Ratio, r value, which is a measure of the texture present in the material in the deformation conditions, agree well with the computed values with a maximum at 45oorientation to the rolling direction.

scholarly journals Mechanical Property Comparison of Ni–Cr–Mo Alloys Fabricated via One Conventional and Two New Digital Manufacturing Techniques

2021 ◽  
Vol 11 (19) ◽  
pp. 9308
Author(s):  
Kyung-Ran Yang ◽  
Takao Hanawa ◽  
Tae-Yub Kwon ◽  
Bong-Ki Min ◽  
Min-Ho Hong
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Face Centered Cubic ◽  
Percentage Elongation ◽  
Nickel Chromium ◽  
Identical Composition ◽  
Soft Metal ◽  
Manufacturing Techniques ◽  
Face Centered ◽  
Digital Processes

This study compared the microstructures and mechanical properties of nickel–chromium–molybdenum (Ni–Cr–Mo) alloys prepared from a single alloy with an identical composition using two new digital processes (selective laser melting (SLM) and soft metal milling (SMM)) and conventional lost-wax casting (LWC). Disc specimens were used to study the microstructures via various analytical methods, while dumbbell-shaped specimens were subjected to tension to determine the mechanical properties (n = 6). The SLM and SMM alloys showed a higher number of large and small pores, respectively, than the LWC alloy. A face-centered cubic (γ)-phased matrix was indexed for all three resultant alloys. The SLM and SMM alloys also showed more homogeneously distributed elements and finer grains (in particular, ultrafine grains in the SLM alloy) when compared to the LWC alloy. Meanwhile, the LWC alloy showed a statistically higher yield strength than the other two alloys (p < 0.001). Notwithstanding, all three resultant Ni–Cr–Mo alloys satisfied the ISO 22674 standard criteria for type 5 materials (yield strength: >500 MPa; percentage elongation: >2%; and elastic modulus: >150 GPa).

Effect of cold rolling on microstructural and mechanical properties of MG-7LI alloy

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040035
Author(s):  
Xiang Cai ◽  
Yanxin Qiao ◽  
Baojie Wang ◽  
Huiling Zhou ◽  
Yuxin Wang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Cold Rolling ◽  
Tensile Test ◽  
Rolling Direction ◽  
Scanning Electron

The influence of rolling on nanomechanical and mechanical behavior of Mg-7Li alloy was investigated by nanoindentation, tensile test and scanning electron microscopy (SEM), respectively. The [Formula: see text]-Mg phase elongated along the rolling direction and gradually cracked. As the rolling ratio increased from 3 to 10, the hardness of [Formula: see text]-Mg and [Formula: see text]-Li phase increased by 7.35% and 20.75%, respectively. The fracture of alloys changed from ductile fracture to quasi-cleavage fracture. The yield strength and ultimate tensile strength increased by 23 MPa and 12 MPa, respectively, while elongation reduced by 12.5%.

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