The Effect of Deformation on the Work Hardening Behaviour after Aging of Two Commercial Al-Mg-Si Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 261-266 ◽  
Author(s):  
Michal Kolar ◽  
Ketill Olav Pedersen ◽  
Sverre Gulbrandsen-Dahl ◽  
Thiemo Brüggemann ◽  
Knut Marthinsen
Keyword(s):  
Aging Time ◽  
Work Hardening ◽  
Natural Aging ◽  
Tensile Tests ◽  
Engineering Strain ◽  
Transmission Electron ◽  
Aging Response ◽  
Heat Treated ◽  
Work Hardening Rate ◽  
Commercial Aluminium

In order to investigate the effect of deformation on the aging response of Al-Mg-Si alloys, a series of tensile tests have been designed and carried out on two commercial aluminium alloys, i.e. AA6060 and AA6082. Extruded and solution heat treated specimens were pre-deformed 0%, 5%, and 10% (engineering strain), respectively followed by natural aging (NA). It was observed that the work-hardening rate increases with prolonged natural aging time and decreases with increasing pre-deformation prior to natural aging. The most significant effect of deformation was obtained for T4 temper i.e. after 1000 and 10000 minutes NA for the 6082 and 6060 alloy, respectively, when the amount of pre-deformation is 10%. A remarkable difference in work-hardening rate at the level of small plastic strains was observed compared to that of the material naturally aged for only 10 minutes. In addition to the tensile tests, transmission electron microscopy (TEM) has been used to characterize dislocation evolution for various combinations of pre-deformation and aging time.

Research on Fluctuations in Work Hardening Rate of a Fe-Mn-Al-C Steel

2015 ◽  
Vol 817 ◽  
pp. 288-292 ◽  
Author(s):  
Chao Zhao ◽  
Ren Bo Song ◽  
Lei Feng Zhang ◽  
Fu Qiang Yang ◽  
Shuai Qin
Keyword(s):  
Electron Microscopy ◽  
Work Hardening ◽  
True Strain ◽  
Rate Curve ◽  
Heat Treated Sample ◽  
Transmission Electron ◽  
Heat Treated ◽  
Treated Sample ◽  
Fluctuation Range ◽  
Work Hardening Rate

The fluctuations in the work hardening rate of a Fe-12Mn-10Al-0.7C (wt. %) steel have been investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The work hardening rate of the heat treated sample had a tendency of decrease with fluctuations. The first raise in the work hardening rate curve at about 2% true strain is attributed to the shearing of the small ferrite grains by austenite, and the deformation induced twinning can contribute to the raise and drop in the work hardening rate curve. The second fluctuation range at the true strain between 10% and 14% is mainly related to the activation of planar slip on the principle slip plane which is suppressed by twins in austenite.

scholarly journals On the Development of an Al4.8 wt% Cu Alloy Obtained from Recycled Aluminum Cans Designed for Thixoforming Process

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Ronan Miller Vieira ◽  
Gianni Ferreira Alves Moreira ◽  
André Itman Filho ◽  
Estéfano Aparecido Vieira
Keyword(s):  
Solution Heat Treatment ◽  
Natural Aging ◽  
Tensile Tests ◽  
Permanent Mold ◽  
Semisolid State ◽  
Globular Microstructure ◽  
Cu Alloy ◽  
Heat Treated ◽  
Aluminum Cans ◽  
Melting And Solidification

This work has focused on the development of a new aluminum alloy containing 4.8 wt% of Cu alloy obtained from recycled aluminium cans designed for thixoforming process. After the step of melting and solidification of the alloy in a metallic permanent mold, samples were solution heat treated at 525°C for times ranging from 2 h to 48 h, quenched in water and followed by natural aging. Results have shown the evolution of hardness so from them solubilization solution heat treatment was chosen for 24 h. The best condition for aging was 190°C during 3 h. With this data pieces were thixoforged at 580°C and 615°C corresponding, respectively, to solid fraction (fs) of 0.8 and 0.6. The optimized T6 temper was applied and tensile tests were performed. The mechanical properties obtained are compatible with those obtained for consolidated alloys processed in semisolid state (SS) and after T6 temper hardness increases from 95 HB to 122 HB and the best results were a tensile strength of 324 MPa ± 10 MPa, yield strength of 257 MPa ± 18 MPa, and an elongation of 7.1%  ±  1%. For alloys designed for thixoforming process, these results are in accordance with what was expected whereas globular microstructure, high ductility, and good performance under cyclic conditions are desirable.

scholarly journals Nondestructive Evaluation of Thermal Aging in Al6061 Alloy by Measuring Acoustic Nonlinearity of Laser-Generated Surface Acoustic Waves

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 38 ◽  
Author(s):  
Jihyun Jun ◽  
Hogeon Seo ◽  
Kyung-Young Jhang
Keyword(s):  
Mechanical Properties ◽  
Nondestructive Evaluation ◽  
Thermal Aging ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Tensile Tests ◽  
Acoustic Nonlinearity ◽  
Transmission Electron ◽  
Heat Treated ◽  
Elongation To Failure

The structures in high-temperature environments are prone to undergo hardening and embrittlement as a result of thermal aging; this can cause variations in their mechanical properties. Because these changes occur at the microstructural level, it is difficult to evaluate them through linear ultrasonic techniques. In this work, a surface acoustic wave (SAW) was used to measure and compare the acoustic nonlinearity and mechanical properties of Al6061 alloys heat-treated at 220 °C for different durations (0 min, 20 min, 40 min, 1 h, 2 h, 10 h, 100 h, 1000 h). The SAW was generated by a pulsed laser and then received by an interferometer. Moreover, the yield strength, ultimate strength, and elongation to failure were measured by tensile tests. The results demonstrate that the critical variations in the mechanical properties can be detected by monitoring the variation features in the acoustic nonlinearity. Transmission electron microscopy images were captured to observe the microstructural changes, which shows that the acoustic nonlinearity varied according to the change in the precipitation phase. This supports the acoustic nonlinearity measurement using the laser-generated SAW being an effective technique for the fully noncontact nondestructive evaluation of material degradations as well as changes in mechanical properties.

Precipitation Studies of Undeformed and ECAP-Deformed Al-4%Cu Alloys: Effects on Microstructure and Tensile Properties

2008 ◽  
Vol 584-586 ◽  
pp. 708-715 ◽  
Author(s):  
Erika Fernanda Prados ◽  
Vitor Luiz Sordi ◽  
Maurizio Ferrante
Keyword(s):  
Initial Conditions ◽  
Tensile Tests ◽  
Solution Temperature ◽  
Tensile Behaviour ◽  
Total Strength ◽  
Angular Pressing ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Heat Treated ◽  
Precipitation Heat

The present study is an assessment of the effects of precipitation heat treatments on tensile behaviour, work hardening (WH) characteristics and microstructural evolution of an Al-4%Cu alloy deformed by equal channel angular pressing (ECAP). Two ageing temperatures were employed (170 and 100oC) and their effect on strength and WH behaviour was compared with that exerted on the same alloy, but in two different initial conditions: quenched from solution temperature and slowly cooled before anneal. Grain and precipitate sizes of samples deformed by one and four ECAP passes and heat treated as described were measured employing transmission electron microscopy (TEM). It was concluded that the lower ageing temperature gives the best combination of strength and ductility, a high WH rate and, possibly, the smaller grain and precipitate sizes. The relative participation of the various hardening mechanisms to total strength was estimated from tensile tests and hardness measurements.

scholarly journals Microstructure development during thermomechanical treatment of Al-Mg-Si alloy

2002 ◽  
Vol 38 (3-4) ◽  
pp. 153-162 ◽  
Author(s):  
Z. Martinova ◽  
G. Zlateva
Keyword(s):  
Electrical Conductivity ◽  
Thermomechanical Treatment ◽  
Artificial Aging ◽  
Cold Deformation ◽  
Natural Aging ◽  
Tensile Tests ◽  
Prolonged Storage ◽  
Recovery Processes ◽  
Transmission Electron ◽  
Lower Aging Temperature

The effect of natural aging and 95% cold deformation on the microstructure evolution and aging characteristics in commercial Al - 1 mass % Mg2Si alloy subjected to thermomechanical treatment (TMT) was examined. Transmission electron microscopy observations, tensile tests and electrical conductivity measurements were carried out in order to correlate microstructural features to properties on each TMT step. It was established that pre-aging at room temperature affected the morphology of dislocation structure induced by next cold deformation. The observed transition from cellular to homogenous dislocation distribution was explained by the different stability of zones produced by pre-aging of different duration. Natural aging suppressed recovery processes during post-deformation artificial aging, especially after prolonged storage after quenching and at lower aging temperature. It influenced the morphology of precipitates produced by post deformation artificial aging also. The overall effect of TMT involving prior-deformation natural aging in the scheme, on hardness, tensile properties and electrical conductivity is discussed based on experimental microstruture observations.

scholarly journals FEATURES OF STRUCTURE FORMATION AND CHANGES IN THE MECHANICAL PROPERTIES OF CAST Al-Mg-Si-Mn ALLOY WITH THE ADDITION OF (Ti+Zr)

2015 ◽  
Vol 55 (4) ◽  
pp. 282 ◽  
Author(s):  
Oleksandr Trudonoshyn ◽  
Maxim Puchnin ◽  
Kostiantyn Mykhalenkov
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Ageing Time ◽  
Tensile Tests ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Scanning Electron

<p>The as-cast and heat-treated structure of permanent mould castings of AlMg<sub>5</sub>Si<sub>2</sub>Mn alloys with different contents of Ti has been investigated by differential scanning calorimetry, hardness and microhardness measurements, tensile tests and fractography analyses, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. We have established that α-Al dendrites can be nucleated on an Al-Ti substrate, and also that primary Mg<sub>2</sub>Si crystals can be nucleated on oxides, including oxides of Al and Ti compounds. The dependence of the change in mechanical properties on ageing time, and on the amount of Ti in the alloys, is shown.</p>

Plastic Behaviour of Copper Polycrystal Subjected to Fatigue-Tension Sequential Loading Tests

2006 ◽  
Vol 514-516 ◽  
pp. 897-900
Author(s):  
Wei Ping Jia ◽  
José Valdemar Fernandes
Keyword(s):  
Yield Stress ◽  
Work Hardening ◽  
Strain Path ◽  
Mechanical Tests ◽  
Dislocation Slip ◽  
Tension Tests ◽  
Transmission Electron ◽  
Mean Grain Size ◽  
Work Hardening Rate ◽  
Strain Path Change

Sequences of fatigue-tension tests were performed on copper polycrystal sheet, with 32µm mean grain size. The effect of strain path change on subsequent reloading yield stress as well as work hardening rate has been investigated. Dislocation microstructure was observed by transmission electron microscopy after mechanical tests. Under present conditions, it was found that fatigue prestraining caused the increase of reloading yield stress, larger amplitude of strain path change resulted in higher reloading yield stress and lower work hardening rate. Reloading tensile curves are independent of predeformation plastic strain amplitudes in both cases. Many isolated dislocation lines between cell walls have been detected for Φ=0° case when the subsequent tension strain amount is 5%, this can be well understood from the microscopic dislocation slip mechanisms. When the reloading tension tests have been done until rupture, dislocation structures become typical of monotonic tension without preloading. The correlation of mechanical properties and microstructural observations was discussed in this paper.

Effect of Aging Time to the Commercial Aluminum Alloy Modified with Zirconium Addition

2015 ◽  
Vol 819 ◽  
pp. 50-56 ◽  
Author(s):  
Zakariaa Mohd Syukry ◽  
Ismail Ahmad Badri
Keyword(s):  
Aluminum Alloy ◽  
Aging Time ◽  
Treatment Condition ◽  
Natural Aging ◽  
Heat Treatment Condition ◽  
Heat Treated ◽  
Aging Alloy ◽  
Cast Alloys ◽  
Alloy Cast ◽  
Zirconium Addition

The influence of heat treatment condition with addition of zirconium on the some properties of aluminum alloy has been investigated. The composition of aluminum alloy cast produce from this research was supplied from the foundry. The cast alloys were given a solutionizing treatment at 520°C followed by artificial aging at 175°C for a different period of time up to 10 hours. Hardness of heat treated aluminum alloy then were determined by comparing to the as cast and natural aging alloy. The addition of zirconium will improve the properties of the alloy in term of hardness and conductivity. Grain size of alloy has no significant effect when aging time increased together with zirconium addition.

scholarly journals Post-Heat Treatment and Mechanical Assessment of Polyvinyl Alcohol Nanofiber Sheet Fabricated by Electrospinning Technique

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mahir Es-saheb ◽  
Ahmed Elzatahry
Keyword(s):  
Polyvinyl Alcohol ◽  
Strain Rate ◽  
Young Modulus ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Gravimetric Analysis ◽  
Test Results ◽  
Electrospinning Technique ◽  
Transmission Electron ◽  
Heat Treated

Polyvinyl alcohol (PVA) sheets based nanofibers were produced by electrospinning technique. Postheat treatment of the produced PVA sheets with temperatures both below and above Tg to improve the mechanical properties of this material is conducted. The morphology, microstructures, and thermal degradation of the nanofibers sheets produced were investigated using scanning electron microscopy (SEM), transmission electron microscope (TEM), and thermal gravimetric analysis (TGA). Produced nanofibers are compact, and entangled with each other, with diameters from around 150 to 210. Some mechanical characteristics of the successfully produced PVA sheets, and heat-treated, are then conducted and assessed employing uniaxial tensile tests at different speeds ranging from 1 mm/min to 100 mm/min. The tensile test results obtained show that the PVA sheets are strain rate sensitive with increasing strength as the speed (i.e., strain rate) increases. The yield tensile stress ranges from 2.411 to 6.981 MPa, the ductility (i.e., elongation percent) from∼21 to 60%, and Young modulus ranges from 103 to 0.137 KPa. However, for heat-treated samples, it is found that the yield strength increases almost by∼35–40% more than the values of untreated cases with values reaching up to about 3.627–9.63 MPa.

Room Temperature Deformation Behavior of Inconel718

2005 ◽  
Vol 475-479 ◽  
pp. 677-680 ◽  
Author(s):  
Fang Bian ◽  
Guoyue Su ◽  
Fan Ya Kong ◽  
Ke Yang
Keyword(s):  
Grain Size ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Tensile Tests ◽  
True Stress ◽  
Temperature Deformation ◽  
Stress Strain ◽  
Limit Value ◽  
Heat Treated ◽  
Work Hardening Rate

The deformation behavior of Inconel718 at room temperature was studied by tensile tests. Three kinds of specimens were tested, including cold rolled, heat treated with grain size ASTM5 and heat treated with grain size ASTM7. The true stress-strain curves were obtained based on the tensile test records. The true stress-strain relation can express the room temperature deformation behavior, which can be described by equations similar to the Voce equation. The limit value of the work-hardening rate θ0 is very sensitive to the microstructure of the alloy.

Sign in / Sign up

Export Citation Format

Share Document