Influence of Initial Microstructure on Rheology of Al-Zn-Mg-Cu Alloy during Thermal Compression

2011 ◽  
Vol 314-316 ◽  
pp. 506-510
Author(s):  
Lei Xu ◽  
Guang Ze Dai ◽  
Xing Min Huang ◽  
Jun Wen Zhao ◽  
Jing Han
Keyword(s):  
Activation Energy ◽  
Aluminum Alloy ◽  
Steady State ◽  
Flow Stress ◽  
Strain Rate ◽  
Rheological Behavior ◽  
Extrusion Ratio ◽  
Thermal Compression ◽  
Initial Microstructure ◽  
Fine Grain

The rheological behavior of two kinds Al-Zn-Mg-Cu aluminum alloy with different extrusion ratio was studied by thermal compression in 300°C~450°C and in strain rate range of 0.01 s-1~10s-1 on Gleeble1500D simulator. The results show that: (1)the flow stress increases with deSuperscript textcreasing deformation temperature and increasing strain rate, and the initial microstructure influence the rheological behavior, the flow stress with fine grain is higher than that with coarse one except in strain rate 0.01s-1 and 0.1s-1 in 450°C owing to deformation easily with more grain boundary sliding in high temperature and low strain rate.(2)The flow stress of Al-Zn-Mg-Cu aluminum alloy during hot compression can be expressed as hyperbolic sine constitutive equation with Arrhenius parameter, the apparent steady state activation energy for hot compression with coarse grain is of 181.51kJ/mol, while that with fine grain is of 203.02kJ/mol.(3) The apparent steady state activation energy decreases with increasing temperature and strain rate, and the value of fine initial microstructure is higher than the low extrusion ratio rod commonly.

Effect of SN Additions on Superplasticity in Al-Mg-Mn-Sc Alloys

1999 ◽  
Vol 601 ◽  
Author(s):  
C. H. Henager ◽  
J. S. Vetrano ◽  
V. Y. Gertsman ◽  
S. M. Bruemmer
Keyword(s):  
Activation Energy ◽  
Flow Stress ◽  
Strain Rate ◽  
Stress And Strain ◽  
Strain Rates ◽  
Fine Grain ◽  
Heat Treated ◽  
Main Effect ◽  
Stress And Strain Rate ◽  
Stress Activation

AbstractIdentical Al-Mg-Mn-Sc alloys without and with 0.034-wt% Sn additions were fabricated, heat-treated, and tensile tested in a fine-grain (d < 6 pm) condition at four strain rates from 10−2 to 10−4 s−1 and at temperatures from 723K to 823K. Alloys with Sn additions exhibited reduced failure strains at 723K but higher failure strains at 823K for the slowest strain rates. The effect of Sn on flow stress, activation energy for flow stress, and strain rate exponent was explored and was found to be small. The main effect of Sn was suggested to be in reducing cavitation by allowing a redistribution of stress at critical hetero-junctions in the alloys.

Hot Deformation Behavior and Microstructure of 6069 Aluminum Alloy

2014 ◽  
Vol 788 ◽  
pp. 201-207 ◽  
Author(s):  
Hui Zhong Li ◽  
Jun Jiang ◽  
Min Deng ◽  
Xiao Peng Liang ◽  
Jie Ouyang
Keyword(s):  
Aluminum Alloy ◽  
Steady State ◽  
Flow Stress ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Constant Strain Rate ◽  
Strain Rates ◽  
Steady State Flow ◽  
State Flow

The deformation behavior and microstructure of 6069 aluminum alloy have been studied by isothermal compression at temperature ranging from 300°C to 450°C on Gleeble-1500 machine at strain rates from 0.01 to 10s-1. The results show that the deformation temperature and strain rate is essential to the flow characteristic, and the main deformation mechanism for 6069 aluminum alloy is dynamic recovery at low strain rates. The dynamic recrystallization take place at the strain rates of 10s-1 and deformation temperature ranges of 300~350°C. At constant strain rate, the flow stress and steady-state flow stress decrease with deformation temperature increasing. While at constant temperature, the flow stress and steady-state flow stress increase with increasing strain rate. The processing map at the strain of 0.7 is obtained and the map exhibits two safe deformation domains (300~350°C at 1~10s-1 and 380~450°C at 0.01~0.3s-1).

Comparative Study of the Dynamic Behavior of AA2519 Aluminum Alloy in T6 and T8 Temper Conditions

2019 ◽  
Author(s):  
Adewale Olasumboye ◽  
Gbadebo Owolabi ◽  
Olufemi Koya ◽  
Horace Whitworth ◽  
Nadir Yilmaz
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Stress Response ◽  
Flow Stress ◽  
Yield Strength ◽  
Strain Rate ◽  
High Strain ◽  
Second Phase ◽  
Strain Rates ◽  
High Strain Rates

Abstract This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.

Hot Deformation Behavior and Microstructure of U720Li Alloy

2013 ◽  
Vol 709 ◽  
pp. 143-147 ◽  
Author(s):  
Tao Wang ◽  
Zhao Li ◽  
Shu Hong Fu ◽  
Yong Zhang ◽  
Yu Xin Zhao ◽  
...  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Primary Phase ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Fine Grain ◽  
Lower Strain

The hot deformation behavior of U720Li was investigated by isothermal compression tests at temperature ranging from 1060-1180°C and strain rate from 0.001s-1 to 20s-1. The flow stress-strain curves and microstructures were investigated and a constitutive equation was established. It is found that flow stress is sensitive to stain rate and deformation temperature greatly. The higher stain rate resultes in a larger fluctuation in flow stress. The hot deformation activation energy is determined to be 552.8kJ/mol. Grain size increases with increasing temperature and decreases firstly and then increases with increasing strain rate. U720Li alloy should be deformed below the solve temperature of γ primary phase with lower strain rate in order to obtain the even and fine grain size.

scholarly journals Constitutive Behavior of an AA4032 Piston Alloy with Cu and Er Additions upon High-Temperature Compressive Deformation

2019 ◽  
Vol 51 (1) ◽  
pp. 467-481
Author(s):  
Suwaree Chankitmunkong ◽  
Dmitry G. Eskin ◽  
Chaowalit Limmaneevichitr
Keyword(s):  
Activation Energy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Base Alloy ◽  
True Strain ◽  
Constitutive Behavior ◽  
Compression Tests ◽  
Primary Si ◽  
Constitutive Parameters

Abstract Aluminum piston alloys of the AA4032 type are produced by direct-chill (DC) casting and subsequent forging; therefore, it is important to understand their thermomechanical behavior. In recent years, it was shown that additions of Cu and Er could improve mechanical properties of these alloys at room and high temperatures. In this work, we studied the constitutive behavior of AA4032-type alloys with and without Cu and Er additions. The experimental true stress–true strain curves were obtained by compression tests under various temperatures [683 K to 723 K (410 °C to 450 °C)] and strain rates (0.01 to 10 s−1) to determine constitutive parameters [strain-rate sensitivity, activation energy, and Zener–Hollomon (Z) parameter] for the hot deformation behavior of AA4032-type piston alloys with and without additions of Cu and Er. The flow stress decreased with increasing deformation temperature and decreasing strain rate. The results also showed that increasing the Cu content increased the flow stress over the applied range of deformation conditions due to solid-solution strengthening and the formation of primary Si particles, which led to an increase in the activation energy during hot deformation. Moreover, the main microstructural damage in the AA4032 alloy with 3.5 pct Cu was predominantly due to the cracking of primary Si particles. Additions of 0.4 pct Er and 3.5 pct Cu lower the activation energy of deformation, Q, as compared to the base alloy and the alloy with 3.5 pct Cu. The microstructures in the deformed specimens consisted of subgrains, recrystallized grains, and fine eutectic phases. The alloys containing Er demonstrated more polygonized grains at a low strain rate than the alloys without Er, indicating that Er hindered recrystallization development. The peak stress of the AA4032 alloy with 3.5 pct Cu alloy was higher than for the base AA4032 alloy and for the AA4032 alloy with 3.5 pct Cu and 0.4 pct Er additions, which was attributed to the prevalence of the work-hardening mechanism over the softening mechanism.

Modeling the Hot Deformation Behavior of 1565ch Aluminum Alloy

2016 ◽  
Vol 684 ◽  
pp. 35-41 ◽  
Author(s):  
S.V. Rushchits ◽  
E.V. Aryshensky ◽  
S.M. Sosedkov ◽  
A.M. Akhmed'yanov
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Static Recrystallization ◽  
Strain Rates ◽  
Strain Resistance ◽  
Hot Deformation Behavior ◽  
Zirconium Addition

The deformation behavior of 1565ch alloy under the plane-strain conditions in the temperature range of 350–490 оС and strain rates range of 0,1–10 s-1 is studied. The expression for steady flow stress as the functions of temperature of deformation and strain rate is obtained. It is established that 1565ch alloy with zirconium addition shows higher strain resistance and less tendency to dynamic and static recrystallization than AMg6.

Microstructure and Plasticity of Hot Deformed 5083 Aluminum Alloy Produced by Rapid Solidification and Hot Extrusion / Badania Mikrostruktury I Plastyczności Odkształcanego Na Gorąco Szybko-Krystalizowanego I Wyciskanego Stopu Aluminium 5083

2012 ◽  
Vol 57 (4) ◽  
pp. 1253-1259 ◽  
Author(s):  
T. Tokarski ◽  
Ł. Wzorek ◽  
H. Dybiec
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Flow Stress ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Temperature Range ◽  
Rapidly Solidified ◽  
5083 Aluminum Alloy ◽  
Conventionally Cast

The objective of the present study is to analyze the mechanical properties and thermal stability for rapidly solidified and extruded 5083 aluminum alloy (RS). Compression tests were performed in order to estimate flow stress and strain rate sensitivity relation for 5083 alloy in the temperature range of 20°C to 450°C. For the comparison purposes, conventionally cast and extruded industrial material (IM) was studied as well. Deformation tests performed at room temperature conditions show that rapidly solidified material exhibits about 40% higher yield stress (YS=320 MPa) than conventionally cast material (YS=180 MPa), while the deformation at 450°C results in significant decrease of flow stress parameters for RS material (YS=20 MPa) in comparison to IM material (YS=40 MPa). Strain rate sensitivity parameter determined for high temperature conditions indicates superplasticity behavior of RS material. Structural observations show that under conditions of high-temperature deformation there are no operating recrystallization mechanisms. In general, grain size below 1µm and size of reinforcing phases below 50 nm is preserved within the used deformation temperature range.

scholarly journals Dynamic Mechanical Response of Biomedical 316L Stainless Steel as Function of Strain Rate and Temperature

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
Woei-Shyan Lee ◽  
Tao-Hsing Chen ◽  
Chi-Feng Lin ◽  
Wen-Zhen Luo
Keyword(s):  
Activation Energy ◽  
Stainless Steel ◽  
Flow Stress ◽  
Strain Rate ◽  
Thermal Activation ◽  
316L Stainless Steel ◽  
Rate Sensitivity ◽  
Thermal Activation Energy ◽  
Work Hardening Rate ◽  
Stress Work

A split Hopkinson pressure bar is used to investigate the dynamic mechanical properties of biomedical 316L stainless steel under strain rates ranging from 1 × 103 s-1to 5 × 103 s-1and temperatures between25∘Cand800∘C. The results indicate that the flow stress, work-hardening rate, strain rate sensitivity, and thermal activation energy are all significantly dependent on the strain, strain rate, and temperature. For a constant temperature, the flow stress, work-hardening rate, and strain rate sensitivity increase with increasing strain rate, while the thermal activation energy decreases. Catastrophic failure occurs only for the specimens deformed at a strain rate of 5 × 103 s-1and temperatures of25∘Cor200∘C. Scanning electron microscopy observations show that the specimens fracture in a ductile shear mode. Optical microscopy analyses reveal that the number of slip bands within the grains increases with an increasing strain rate. Moreover, a dynamic recrystallisation of the deformed microstructure is observed in the specimens tested at the highest temperature of800∘C.

Effect of Directional Grain Structure and Strain Rate on Impact Properties and Dislocation Substructure of 6061-T6 Aluminum Alloy

2014 ◽  
Vol 626 ◽  
pp. 50-56
Author(s):  
Woei Shyan Lee ◽  
Mao Hung Liu
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Dislocation Substructure ◽  
Grain Structure ◽  
Strain Rates ◽  
Multiplication Rate ◽  
Impact Properties ◽  
Transverse Specimen ◽  
Longitudinal Specimen

The effect of directional grain structure and strain rate on the impact properties and dislocation substructure of 6061-T6 aluminum alloy is studied. Impact tests are performed at strain rates ranging from 1x103 to 5x103s-1 using a split Hopkinson pressure bar system. Cylindrical specimens are prepared from the rolled plates in longitudinal direction, transverse direction and through-thickness direction, respectively. The results show that the flow stress is strongly dependent on the strain rate and displays complex variations with grain structure direction. The flow stress increases with increasing strain rate. For all tested strain rates, the flow stress is the highest in the transverse specimen, followed by the through-thickness specimen and longitudinal specimen. However, at the strain rate of 5x103s-1, the flow stress in longitudinal specimen is higher than that in through-thickness specimen due to the change of dislocation multiplication rate. The plastic flow occurs within the deformation regions, and becomes more pronounced at high strain rates, especially for the longitudinal specimen. Dislocation density increases markedly with increasing strain rate. Strengthening effect is the highest in the transverse specimen, followed by the longitudinal specimen and through-thickness specimen.

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