Effect of strain rate on true stress–true strain relationships of ultrafine-grained ferrite–cementite steels up to plastic deformation limit

2015 ◽  
Vol 626 ◽  
pp. 441-448 ◽  
Author(s):  
N. Tsuchida ◽  
H. Nakano ◽  
T. Okamoto ◽  
T. Inoue
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
True Strain ◽  
True Stress ◽  
Deformation Limit ◽  
Ultrafine Grained

Mechanical Aspects of Plastic Deformation of Nickel Based Superalloy

2013 ◽  
Vol 592-593 ◽  
pp. 724-727
Author(s):  
Andrzej Nowotnik ◽  
Paweł Rokicki ◽  
Paweł Pędrak ◽  
Slawomir Kotowski ◽  
Jan Sieniawski ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Flow Stress ◽  
Strain Rate ◽  
Deformation Process ◽  
True Strain ◽  
True Stress ◽  
Effect Of Temperature ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Nickel Based Superalloy

Variations of a true stress vs. true strain illustrate behaviour of materials during plastic deformation. Stress-strain relationship is generally evaluated by a torsion, compression and tensile tests. Results of these tests provide crucial information pertaining to the stress values which are necessary to run deformation process at specified temperature and cooling rate. Uniaxial compression tests at temperatures below the γ solvus were conducted on nickel based superalloy CMSX-4, to study the effect of temperature and strain rate on its flow stress. On the basis of received flow stress values activation energy of a high-temperature deformation process was estimated. Mathematical dependences (σpl -T i σpl - ἐ) and compression data were used to determine material constants. These constants allow to derive a formula that describes the relationship between strain rate, deformation temperature and true stress.

Study on Constitutive Modeling for Large Deformation Behavior of Polyethylene Considering Strain Rate Effect

2013 ◽  
Author(s):  
Sijia Zhong ◽  
Jianfeng Shi ◽  
Jinyang Zheng
Keyword(s):  
Strain Rate ◽  
Large Deformation ◽  
Constitutive Modeling ◽  
Deformation Behavior ◽  
True Strain ◽  
True Stress ◽  
Uniaxial Tensile ◽  
Pipeline System ◽  
Composite Effect ◽  
Time Deformation

Polyethylene (PE) pipes have been applied in transportation of key energy medium such as natural gas in the past decades. The mechanical property of PE is of great importance for better design and safer application of PE pipeline system. The large deformation behavior is a key character of PE, not only for its significant strain rate sensitivity, but also for localized necking process after yielding. In this paper, a new constitutive modeling method was proposed to charaterize the rate-denpendent large deformation behavior of PE, in which the true stress is regarded as a function of true stain and true strain rate alone. Uniaxial tensile tests of PE were conducted under various cross-head speeds, and a digital camera was used to record the real-time deformation of specimens. By separating the composite effect into respective effect of local true strain and strain rate on the local true stress in the necking region, a phenomenological model for describing the rate-dependent deformation behavior under uniaxial tension was ealstablished. Model results were validated and found in good agreement with experimental data.

True Stress and Shakedown Analysis of Pressure Vessel which under Cyclic Loading to Plastic Deformation

2014 ◽  
Vol 590 ◽  
pp. 8-12
Author(s):  
Xiao Liang Jia ◽  
Yi Liang Zhang ◽  
Jing Wang ◽  
Chun Bo Wang
Keyword(s):  
Plastic Deformation ◽  
Constitutive Model ◽  
Pressure Vessel ◽  
Axial Stress ◽  
Water Pressure ◽  
True Strain ◽  
Test System ◽  
True Stress ◽  
Plastic Shakedown ◽  
The Relationship

The aim of this study is to discuss the plastic shakedown and true stress of the cyclically loaded pressure vessel. A thin-walled cylinder pressure vessel is made according to actual working state and a water pressure test system is built. The vessel is loaded to different strain levels of plastic deformation first. Then it is loaded cyclically to shakedown state. The relationship between plastic strain and shakedown range is given based on numerous experiments. The constitutive model of the true stress-true strain of the vessel is obtained. The experimental results show that the ratcheting obviously occurred when the vessel is cyclically loaded to plastic deformation. The true stress-strain constitutive model which is presented in this paper can show appropriately the constitutive relation of the vessel when it is under multi-axial stress state. The application of uniaxial shakedown constitutive model has been demonstrated in this study.

Plastic Deformation Simulation of Sintered Ferrous Material in Cold-Forging Process

2018 ◽  
Vol 941 ◽  
pp. 552-557
Author(s):  
Yuki Morokuma ◽  
Shinichi Nishida ◽  
Yuichiro Kamakoshi ◽  
Koshi Kanbe ◽  
Tatsuya Kobayashi ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
True Strain ◽  
Fem Analysis ◽  
True Stress ◽  
Density Change ◽  
Cold Forging ◽  
Strain Diagram ◽  
Metal Part ◽  
Forging Process ◽  
Sintering Time

A cold forging process of Mo-alloyed sintered steel was simulated by finite element method (FEM) analysis considering density change in the process. Moreover, the effect of sintering time on the behavior of the densification and the plastic deformation of it in the cold-forging process was also investigated. Using the true stress-true strain diagram obtained by the compression test with a sintered specimen, the modified true stress-true strain diagram was derived for large plastic deformation analysis with the porous material model. The result of FEM analysis for the cold compression process of the sintered specimen revealed that the analysis can simulate the shape of the excessive metal part and density change of it. Also, it was found that local deformation becomes large and thus the excessive metal part extends with increasing sintering time although the difference in the true stress-true strain diagrams is negligible.

scholarly journals Effects of Temperature and Strain Rate on Plastic Deformation of Ultrafine-Grained Copper Prepared by Equal-Channel Angular Pressing

2014 ◽  
Vol 55 (10) ◽  
pp. 1525-1530 ◽  
Author(s):  
Satoshi Okubo ◽  
Hiroki Abe ◽  
Yoji Miyajima ◽  
Toshiyuki Fujii ◽  
Susumu Onaka ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Equal Channel Angular Pressing ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Effects Of Temperature

Superplastic Behavior of Friction-Stir Welded Joints of an Al-Mg-Sc Alloy with Ultrafine-Grained Microstructure

2016 ◽  
Vol 838-839 ◽  
pp. 338-343 ◽  
Author(s):  
Sergey Malopheyev ◽  
Sergey Mironov ◽  
Igor Vysotskiy ◽  
Rustam Kaibyshev
Keyword(s):  
Strain Rate ◽  
True Strain ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Sensitivity Coefficient ◽  
Friction Stir ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Superplastic Properties

The commercial Al-5.4Mg-0.2Sc-0.1Zr alloy was subjected to equal-channel angular pressing at 300°C to a true strain ~12 followed by cold rolling to a total thickness reduction of 80%. The ultrafine-grained sheets were joined by friction stir welding (FSW). To evaluate superplastic properties of the weldments, the tensile samples including all of the characteristic FSW microstructural zones were machined perpendicular to the welding direction and pulled up to failure in the temperature range of 400 to 500°C and at strain rates of 2.8×10-4 s-1 to 5.6×10-1 s-1. The friction-stir welded material exhibited excellent superplastic properties. The highest elongation-to-failure of ~1370% was recorded at a temperature of ~450°C and an initial strain rate of 5.6×10-2 s-1, where the strain rate sensitivity coefficient was about 0.64. The relationship between superplastic ductility and microstructure is discussed.

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