Plastic Flow Instabilities of L12 Ni3(Si,Ti) Alloys at Intermediate Temperature

2002 ◽  
Vol 17 (3) ◽  
pp. 705-711 ◽  
Author(s):  
H. Honjo ◽  
Y. Kaneno ◽  
H. Inoue ◽  
T. Takasugi
Keyword(s):  
Strain Rate ◽  
Plastic Flow ◽  
Flow Behavior ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Lattice Diffusion ◽  
Intermediate Temperature ◽  
Fine Grained ◽  
Ti Alloys ◽  
Temperature Strain

The serrated plastic flow of L12 Ni3 (Si,Ti) alloys at intermediate temperature was investigated by tensile tests in terms of the effects of temperature, strain rate, composition, and microstructure. Serrated plastic flow was most strongly observed at 473 K and at a strain rate of 1.6 × 10–4 s–1. Correspondingly, the maximum stress amplitude and the lowest (negative) strain-rate sensitivity were observed at 473 K. Serrated plastic flow took place irrespective of boron doping and was more significant in a fine-grained Ni3 (Si,Ti) alloy. The static aging at 473 K resulted in reduced flow stress. The activation energy for serrated plastic flow was estimated to be about 57 kJ mol–1, suggestive of being smaller than that for lattice diffusion of solutes. The serrated plastic flow behavior of Ni3 (Si,Ti) alloys was compared with that of L12 Co3Ti alloys, and is qualitatively explained on the basis of the dynamics of solutes in the core of a dissociated screw dislocation.

Modeling of the Plastic Characteristics of AA6082 for the Friction Stir Welding Process

2015 ◽  
Vol 639 ◽  
pp. 309-316
Author(s):  
Sergio Pellegrino ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Wolfgang Böhm ◽  
Hung Nguyen
Keyword(s):  
Friction Stir Welding ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Flow Behavior ◽  
Welding Process ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Friction Stir ◽  
Friction Stir Welding Process ◽  
Welding Processes

Focus of this paper is to model the plastic forming behavior of AA6082, in order to develop the numerical FE analysis of the friction stir welding processes and the simulation of subsequent forming processes. During the friction stir welding process, the temperatures reached are until 500 °C and have a fundamental role for the correct performance of the process so the material data has to show a temperature dependency. Because of the tool rotation a strain rate sensitivity of the material has to be respected as well. In this context, the general material characteristics of AA6082 were first identified for different stress states. For the uniaxial state the standard PuD-Al used in the automotive industry was applied, for the shear state the ASTM B831-05 was used and for biaxial states the ISO 16842 was exploited. To characterize the plastic flow behavior of the AA6082 at elevated temperatures tensile tests were performed according to DIN EN ISO 6892-2 from 25 °C until 500 °C with a strain rate from 0.1 s-1up to 6.5 s-1.

Influence of Number of Passes in ECAP on Superplastic Behavior in a Magnesium Alloy

2008 ◽  
Vol 584-586 ◽  
pp. 170-175 ◽  
Author(s):  
Roberto B. Figueiredo ◽  
Terence G. Langdon
Keyword(s):  
Strain Rate ◽  
Tensile Testing ◽  
Flow Behavior ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Tensile Tests ◽  
Superplastic Behavior ◽  
Angular Pressing ◽  
Zk60 Alloy ◽  
Number Of Passes

Tensile tests were carried out at 473 K with initial strain rate of 10-4 s-1 in samples of a ZK60 alloy (Mg-5.5% Zn-0.5% Zr) processed by different number of passes using Equal-Channel Angular Pressing (ECAP). The measured superplastic elongations ranged from ~930% to a record of ~3050%. The flow behavior was found to vary with the number of passes of ECAP. It is shown that strain-hardening due to grain growth and the evolution of the strain rate sensitivity with the strain determines the flow behavior and final elongations. The results are consistent with theories of plastic flow in tensile testing.

scholarly journals Effect of Anisotropy, Temperature, Strain Rate on deep drawing using Conical Die

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Ajay Kumar Choubey ◽  
C. Sasikumar
Keyword(s):  
Strain Rate ◽  
Flow Behavior ◽  
Rate Sensitivity ◽  
Blank Holder ◽  
Conical Die ◽  
Ansys Apdl ◽  
Stress And Strain Rate ◽  
Temperature Strain ◽  
Punch Pressure

This paper covers the role of anisotropy, temperature, and strain rate on the flow behavior of the material when a conical die is used instead of conventional blank holder. The effect of anisotropy was investigated using Lankford’s coefficient (r) in three directions (0°, 45°, and 90°). The effect of working temperatures (Room temperature, 100°C - 300°C) on drawing stress and strain rate sensitivity on punch pressure were also investigated in detail. ANSYS APDL was used to investigate the effects of temperature, strain rate and anisotropy. The simulation results have confirmed that the strain variation in the direction of r0 and r45 are more than the variation of r90.

A Study on the Flow Behavior of 42CrMo Steel under Hot Compression by Thermal Physical Simulations

2010 ◽  
Vol 108-111 ◽  
pp. 494-499
Author(s):  
Ying Tong ◽  
Guo Zheng Quan ◽  
Gang Luo ◽  
Jie Zhou
Keyword(s):  
Strain Rate ◽  
Flow Behavior ◽  
Rate Sensitivity ◽  
Strain Hardening Exponent ◽  
Forming Process ◽  
Material Parameters ◽  
Basic Model ◽  
42Crmo Steel ◽  
Plastic Forming ◽  
Physical Simulations

This work was focused on the compressive deformation behavior of 42CrMo steel at temperatures from 1123K to 1348K and strain rates from 0.01s-1 to 10s-1 on a Gleeble-1500 thermo-simulation machine. The true stress-strain curves tested exhibit peak stresses at small strains, after them the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. And the stress level decreases with increasing deformation temperature and decreasing strain rate. The values of strain hardening exponent n, and the strain rate sensitivity exponent m were calculated the method of multiple linear regression, the results show that the two material parameters are not constants, but changes with temperature and strain rate. Then the two variable material parameters were introduced into Fields-Backofen equation amended. Thus the constitutive mechanical discription of 42CrMo steel which can accurately describe the relationships among flow stress, temperature, strain rate, strain offers the basic model for plastic forming process simulation.

High Temperature Deformation Mechanism Maps of NiAl

2004 ◽  
Vol 449-452 ◽  
pp. 57-60
Author(s):  
I.G. Lee ◽  
A.K. Ghosh
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Deformation Mechanism ◽  
Calculation Method ◽  
Deformation Behavior ◽  
Tensile Tests ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Sizes ◽  
Temperature Strain

In order to analyze high temperature deformation behavior of NiAl alloys, deformation maps were constructed for stoichiometric NiAl materials with grain sizes of 4 and 200 µm. Relevant constitute equations and calculation method will be described in this paper. These maps are particularly useful in identifying the location of testing domains, such as creep and tensile tests, in relation to the stress-temperature-strain rate domains experienced by NiAl.

Effect of Consolidation and Sintering Parameters on the Mechanical Responses of Nanocrystalline Al-Fe Alloy Processed by Mechanical Alloying

2015 ◽  
Vol 719-720 ◽  
pp. 87-90
Author(s):  
Muneer Baig ◽  
Hany Rizk Ammar ◽  
Asiful Hossain Seikh ◽  
Mohammad Asif Alam ◽  
Jabair Ali Mohammed
Keyword(s):  
Mechanical Alloying ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Compressive Loading ◽  
Rate Sensitivity ◽  
Testing Temperature ◽  
Fine Grained ◽  
Mechanical Responses ◽  
Wide Range ◽  
High Frequency Induction

In this investigation, bulk ultra-fine grained and nanocrystalline Al-2 wt.% Fe alloy was produced by mechanical alloying (MA). The powder was mechanically milled in an attritor for 3 hours and yielded an average crystal size of ~63 nm. The consolidation and sintering was performed using a high frequency induction sintering (HFIS) machine at a constant pressure of 50 MPa. The prepared bulk samples were subjected to uniaxial compressive loading over wide range of strain rates for large deformation. To evaluate the effect of sintering conditions and testing temperature on the strain rate sensitivity, strain rate jump experiments were performed at high temperature. The strain rate sensitivity of the processed alloy increased with an increase in temperature. The density of the bulk samples were found to be between 95 to 97%. The average Vickers micro hardness was found to be 132 Hv0.1.

High Strain Rate Superplasticity in a Zr and Sc Modified 7075 Aluminum Alloy Produced by ECAP

2008 ◽  
Vol 584-586 ◽  
pp. 164-169 ◽  
Author(s):  
Krystof Turba ◽  
Premysl Malek ◽  
Edgar F. Rauch ◽  
Miroslav Cieslar
Keyword(s):  
Aluminum Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Rate Sensitivity ◽  
7075 Aluminum Alloy ◽  
Fine Grained ◽  
Angular Pressing ◽  
Average Grain Size ◽  
Elongation To Failure

Equal-channel angular pressing (ECAP) at 443 K was used to introduce an ultra-fine grained (UFG) microstructure to a Zr and Sc modified 7075 aluminum alloy. Using the methods of TEM and EBSD, an average grain size of 0.6 1m was recorded after the pressing. The UFG microstructure remained very stable up to the temperature of 723 K, where the material exhibited high strain rate superplasticity (HSRSP) with elongations to failure of 610 % and 410 % at initial strain rates of 6.4 x 10-2 s-1 and 1 x 10-1 s-1, respectively. A strain rate sensitivity parameter m in the vicinity of 0.45 was observed at temperatures as high as 773 K. At this temperature, the material still reached an elongation to failure of 430 % at 2 x 10-2 s-1. These results confirm the stabilizing effect of the Zr and Sc additions on the UFG microstructure in a 7XXX series aluminum alloy produced by severe plastic deformation.

Multilevel Analysis of Strain Rate Effect on Visco-Damage Evolution in Short Random Fiber Reinforced Polymer Composites

2021 ◽  
Vol 36 (2) ◽  
pp. 213-218
Author(s):  
M. D. D. Boudiaf ◽  
L. Hemmouche ◽  
M. A. Louar ◽  
A. May ◽  
N. Mesrati
Keyword(s):  
Strain Rate ◽  
Damage Evolution ◽  
Glass Fibers ◽  
Rate Sensitivity ◽  
Polymeric Composite ◽  
Tensile Tests ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Fiber Reinforced ◽  
Stress Levels

Abstract In this study, the strain rate sensitivity of a discontinuous short fiber reinforced composite and the strain rate effect on the damage evolution are investigated. The studied material is a polymeric composite with a polyamide 6.6 matrix reinforced with oriented randomly short glass fibers at a 50% weigh ratio (PA6.6GF50). Tensile tests at low and high strain rate are conducted. In addition, interrupted tensile tests are carried out to quantify the damage at specific stress levels and strain rates. To perform the interrupted tensile tests, an intermediate fixture is realized via double notched mechanical fuses with different widths designed to break at suitable stress levels. The damage is estimated by the fraction of debonded fibers and matrix fractures. Based on the experimental observations, it is concluded that the ultimate stress and strain, and the damage threshold are mainly governed by the strain rate. Furthermore, it is established that the considered composite has a non-linear dynamic behavior with a viscous damage nature.

High-Temperature Mechanical Properties and Constitutive Modelling of Ti6Al4V Sheets

2016 ◽  
Vol 879 ◽  
pp. 2020-2025 ◽  
Author(s):  
Beatrice Valoppi ◽  
Stefania Bruschi ◽  
Andrea Ghiotti
Keyword(s):  
Elevated Temperature ◽  
Strain Rate ◽  
Flow Behavior ◽  
Hot Stamping ◽  
Tensile Tests ◽  
Testing Temperature ◽  
Constitutive Modelling ◽  
Arrhenius Model ◽  
High Temperature Mechanical Properties ◽  
Material Texture

In this paper, tensile tests were performed at elevated temperature and strain rate in order to investigate the plastic flow behavior, anisotropic characteristics and microstructural evolution of Ti6Al4V sheets under testing conditions similar to the ones experienced during hot stamping operations. It is shown that the Ti6Al4V anisotropic characteristics under the investigated forming conditions, different from the ones of the superplastic regime, are influenced by the variation of the material texture as a function of the testing temperature. The Ti6Al4V flow stress behavior was analyzed as a function of the deformation temperature and strain rate. Afterwards, the Arrhenius constitutive model was proposed to predict the flow behavior of Ti6Al4V sheets at elevated temperature and strain rate. The statistical analysis of its predictive capabilities suggests that the Arrhenius model guarantees a good accuracy in reproducing the flow behavior of Ti6Al4V sheets.

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