scholarly journals Performance of Thermo-Mechanically Processed AA7075 Alloy at Elevated Temperatures—From Microstructure to Mechanical Properties

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 884 ◽  
Author(s):  
Seyed Vahid Sajadifar ◽  
Emad Scharifi ◽  
Ursula Weidig ◽  
Kurt Steinhoff ◽  
Thomas Niendorf
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Forming Process ◽  
Softening Mechanism ◽  
Rate Dependent ◽  
Heat Treated ◽  
Different Temperatures ◽  
Die Forming

This study focuses on the high temperature characteristics of thermo-mechanically processed AA7075 alloy. An integrated die forming process that combines solution heat treatment and hot forming at different temperatures was employed to process the AA7075 alloy. Low die temperature resulted in the fabrication of parts with higher strength, similar to that of T6 condition, while forming this alloy in the hot die led to the fabrication of more ductile parts. Isothermal uniaxial tensile tests in the temperature range of 200–400 °C and at strain rates ranging from 0.001–0.1 s−1 were performed on the as-received material, and on both the solution heat-treated and the thermo-mechanically processed parts to explore the impacts of deformation parameters on the mechanical behavior at elevated temperatures. Flow stress levels of AA7075 alloy in all processing states were shown to be strongly temperature- and strain-rate dependent. Results imply that thermo-mechanical parameters are very influential on the mechanical properties of the AA7075 alloy formed at elevated temperatures. Microstructural studies were conducted by utilizing optical microscopy and a scanning electron microscope to reveal the dominant softening mechanism and the level of grain growth at elevated temperatures.

50CrMo4 Steel-Determination of Mechanical Properties at Lowered and Elevated Temperatures, Creep Behavior, and Fracture Toughness Calculation

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
J. Brnic ◽  
M. Canadija ◽  
G. Turkalj ◽  
D. Lanc
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Effect Of Temperature ◽  
Uniaxial Tensile ◽  
Design And Manufacturing ◽  
Manufacturing Procedure ◽  
Short Time ◽  
Versus Strain

In this paper, some interesting, experimentally determined actualities referring to the 50CrMo4 steel are presented. That way, the mechanical properties of the material are derived from uniaxial tensile tests at lowered and elevated temperatures. Engineering stress versus strain diagrams for both mentioned temperatures, curves representing the effect of temperature on specimen elongation, and short-time creep curves are given. Notch impact energy test was also carried out. Taking into consideration the service life of the final product of the mentioned steel widely used in engine and machine technology, all of the mentioned data may be relevant during design and manufacturing procedure.

Hydraulic Bulge Tests of Magnesium Tubes at Elevated Temperatures

2009 ◽  
Vol 83-86 ◽  
pp. 1135-1142 ◽  
Author(s):  
Yeong-Maw Hwang ◽  
H.C. Chuang ◽  
B.J. Chen
Keyword(s):  
Magnesium Alloy ◽  
Elevated Temperatures ◽  
Testing Machine ◽  
Tube Hydroforming ◽  
Tensile Tests ◽  
Biaxial Stress ◽  
Tube Length ◽  
Uniaxial Tensile ◽  
Hydraulic Bulge ◽  
Different Temperatures

Evaluation of the formability of tubes is an important issue in tube hydroforming processes. Since tubular materials during tube hydroforming are under a biaxial even triaxial stress state, other biaxial-stress-based testing methods are needed. In this paper, uniaxial tensile tests at different temperatures are firstly employed to evaluate the material properties of magnesium alloy AZ61 tubes. A hydraulic bulge warm forming machine, which is used for hydraulic bulge tests with a fixed tube length, is also designed and manufactured. Using this self-designed testing machine, experiments of bulge tests of magnesium alloy AZ61 tubes at elevated temperatures are carried out. From the experimental results, the bulge formability of the magnesium alloy tubes at different temperatures is discussed.

Investigation of the joinability of the high-strength aluminum alloy AA7075 in shear-clinching processes

2021 ◽  
pp. 146442072110679
Author(s):  
S Wiesenmayer ◽  
M Merklein
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
High Strength ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
High Strength Aluminum Alloy ◽  
Heat Treated ◽  
Strength Alloy ◽  
Heating Up

Shear-clinching has proven to be a suitable technology for joining of high-strength materials. However, the mechanical properties of the upper joining partner are limited due to the high strains, which occur during the process. Therefore, shear-clinching of the high-strength aluminum alloy AA7075 in the T6 temper is not possible. Yet, the mechanical properties of hardenable alloys of the 7000 series can be influenced by a heat treatment. Thus, within the scope of this work, the joinability of the high-strength alloy AA7075 in shear-clinching processes in dependance of its temper is investigated. The as fabricated state F, the artificially aged T6 temper, a paint baked state and the naturally aged T4 temper are compared to the fully solution annealed W temper as well as to a retrogression heat-treated state. For retrogression heat treatment, a laser is used as heat source, heating up the alloy for a short term in order to only partially dissolve precipitations. The resulting mechanical properties are determined with uniaxial tensile tests. Moreover, the influence of the mechanical properties of AA7075 on the shear-clinching process, the joint formation and the resulting joint strength is analyzed.

Thermal and Loading Effects on Mechanical Properties of a Hot Isostatically Pressed Si3N4

1994 ◽  
Author(s):  
Jagannathan Sankar ◽  
Jayant Neogi ◽  
Suneeta S. Neogi ◽  
Marvln T. Dixie ◽  
Ranji Vaidyanathan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silicon Nitride ◽  
Elevated Temperatures ◽  
Heat Engine ◽  
Tensile Tests ◽  
Tensile Creep ◽  
Uniaxial Tensile ◽  
Creep Tests ◽  
Loading Effects

The effect of thermal soaking on the mechanical properties of a candidate material for advanced heat engine applications namely, hot isostatically pressed (HIPed) silicon nitride (GTEPY6) are reported here. Pure uniaxial tensile tests conducted at room and at elevated temperatures indicated that the tensile strength of this material dropped significantly after 1000°C. The residual tensile strength of PY6 material after thermal soaking at 1200° and 1300°C was also investigated. Test results showed that thermal soaking at 1200° and 1300°C increased the residual tensile strength. The thermal soaking time had a greater effect on the residual tensile strength at 1300°C. Tensile creep tests performed at 1200° and 1300°C showed that the steady state creep rate was influenced by both the temperature and the applied stress. The higher stress exponent in HIPed as compared to a sintered silicon nitride shows higher creep resistance in the case of HIPed materials.

Study on Mechanical Properties at High Temperatures and Microstructure of Mg-12Gd-3Y-0.5Zr Magnesium Alloy

2014 ◽  
Vol 997 ◽  
pp. 618-623 ◽  
Author(s):  
Tian Dong Cao ◽  
Xiao Ming Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
High Temperatures ◽  
Tensile Tests ◽  
Strengthening Mechanism ◽  
Heat Treated ◽  
Different Temperatures ◽  
Solution Strengthening ◽  
Tension Compression Asymmetry

In this paper, tensile tests were carried out on the as-rolled and heat-treated Mg-12Gd-3Y-0.5Zr magnesium alloy at different temperatures. Tendency of tensile strength vs temperature was investigated and strengthening mechanism was discussed. It shows that both as-rolled and heat-treated Mg-12Gd-3Y-0.5Zr magnesium alloy have good mechanical properties at high temperatures. The reason why they have poor tension-compression asymmetry was discussed by their texture analysis. It is indicated that solution strengthening and precipitation strengthening were main strengthening mechanisam, and RE additons improve their thermal stability which lead to their high tensile strength at high temperatures.

Microstructure and Mechanical Properties of Ti62421S High Temperature Titanium Alloy with Different Heat Treatments

2017 ◽  
Vol 898 ◽  
pp. 574-578
Author(s):  
Xiao Yun Song ◽  
Yong Ling Wang ◽  
Wen Jing Zhang ◽  
Wen Jun Ye ◽  
Song Xiao Hui
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Annealing Temperature ◽  
Elevated Temperatures ◽  
Annealing Treatment ◽  
Tensile Tests ◽  
Alloy Plate ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron ◽  
Different Temperatures

In this paper, three different double annealing treatments were applied on the 3mm-thick Ti-6Al-2Sn-4Zr-1Mo-2Nb-0.2Si (Ti62421S) alloy plate. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile tests were used to investigate the microstructure and mechanical properties under different temperatures of Ti62421S alloy. The results show that the content of primary α phase (αp) decreases while transformed β structure (βt) increases with the increasing first-stage annealing temperature. After double annealing treatment, ordered α2 phase particles precipitate within αp and the size increases with first annealing temperature. This leads to that with increasing first annealing temperature, ultimate tensile strength (UTS) at 600~650°C increases while elongation decreases. After 1000°C/1h/AC+ 750°C/2h/AC annealing, Ti62421S alloy plate exhibits superior combination of mechanical properties at room and elevated temperatures.

Effect of Heat Treatment Temperature on the Mechanical Properties of Custom-Made NiTi Closed Coil Springs

2020 ◽  
Vol 897 ◽  
pp. 35-40
Author(s):  
Thanate Assawakawintip ◽  
Rochaya Chintavalakorn ◽  
Peerapong Santiwong ◽  
Anak Khantachawana
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Tensile Tests ◽  
Treatment Temperature ◽  
Statistical Analyses ◽  
Outer Diameter ◽  
Heat Treated ◽  
Custom Made ◽  
Different Temperatures

To investigate the effects of different temperatures for heat treatment of custom-made NiTi closed coil springs. NiTi closed coil springs (50.8% Ni-49.2%Ti) were manually fabricated around a 0.9mm diameter mandrel and heat treated at temperatures of 400°C, 450°C, and 500°C for 20 minutes. The outer diameter of each specimen was measured to determine the effect of heat treatment temperature on spring geometry. Tensile tests were carried out to measure the force levels at 3, 6, 9, and 12 mm of spring extension. Non-parametric statistical analyses were done to assess and compare the effects of different temperatures of heat treatment on the custom-made orthodontic closed coil springs. Heat treatment at lower temperatures produced larger outer coil diameters than at higher temperatures. Raising the temperature of heat treatment produced significant increases in force levels by 13-18 g especially between 400°C and 500°C at spring extensions of 3, 6 and 9 mm. The highest superelastic ratio of 5.44 was found in the NiTi coil springs that were heat treatment at 500°C for 20 minutes which signifies superelastic tendencies. The mechanical properties of NiTi closed coil springs are influenced by the temperature of heat treatment. The NiTi closed coil springs that were heat treated at 500°C for 20 minutes produce appropriate force levels to display a superelastic tendency for orthodontic use.

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

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.

Comprehensive study on mechanical properties of coated biaxial warp-knitted fabrics

2021 ◽  
pp. 073168442110204
Author(s):  
Bin Yang ◽  
Yingying Shang ◽  
Zeliang Yu ◽  
Minger Wu ◽  
Youji Tao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Failure Modes ◽  
Least Squares Method ◽  
Tensile Tests ◽  
Tensile Creep ◽  
Base Layer ◽  
Sustained Load ◽  
Uniaxial Tensile ◽  
Membrane Structures ◽  
Knitted Fabrics

In recent years, coated fabrics have become the major material used in membrane structures. Due to the special structure of base layer and mechanical properties, coated biaxial warp-knitted fabrics are increasingly applied in pneumatic structures. In this article, the mechanical properties of coated biaxial warp-knitted fabrics are investigated comprehensively. First, off-axial tensile tests are carried out in seven in-plane directions: 0°, 15°, 30°, 45°, 60°, 75°, and 90°. Based on the stress–strain relationship, tensile strengths are obtained and failure modes are studied. The adaptability of Tsai–Hill criterion is analyzed. Then, the uniaxial tensile creep test is performed under 24-h sustained load and the creep elongation is calculated. Besides, tearing strengths in warp and weft directions are obtained by tearing tests. Finally, the biaxial tensile tests under five different load ratios of 1:1, 2:1, 1:2, 1:0, and 0:1 are carried out, and the elastic constants and Poisson’s ratio are calculated using the least squares method based on linear orthotropic assumption. Moreover, biaxial specimens under four load ratios of 3:1, 1:3, 5:1, and 1:5 are further tensile tested to verify the adaptability of linear orthotropic model. These experimental data offer a deeper and comprehensive understanding of mechanical properties of coated biaxial warp-knitted fabrics and could be conveniently adopted in structural design.

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

2014 ◽  
Vol 622-623 ◽  
pp. 273-278 ◽  
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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