Modeling of Low Cycle Behavior of P92 Steel Based on Cyclic Plasticity Constitutive Equations

Strain controlled uniaxial low cycle fatigue (LCF) tests of P92 steel were conducted at strain amplitudes of 0.4%, 0.6% and 0.8% in fully reversed manner with strain rate of 1.0×10-3s-1 at high temperature of 650 °C. Cyclic softening behavior was studied and time-independent cyclic plasticity model was used to represent the cyclic mechanical behavior of this steel. Material parameters were determined step by step at higher strain amplitude of 0.8%, experimental data with lower strain amplitude were used to validate the extrapolation of the model. Comparison of the simulated and experimental results shows that the proposed model can give a reasonable prediction of stress-strain hysteresis loop for P92 steel at high temperature.

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Low Cycle Fatigue Behavior of Original Ferritic P92 Steel at High Temperature: Experiments and Simulations

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2015-45353 ◽

2015 ◽

Cited By ~ 2

Author(s):

Xiaowei Wang ◽

Jianming Gong ◽

Yong Jiang ◽

Yanping Zhao

Keyword(s):

Plastic Material ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Constant Strain Rate ◽

Cyclic Softening ◽

Isotropic Hardening ◽

Cycle Fatigue ◽

Stress Strain ◽

P92 Steel ◽

Softening Behavior

Low cycle fatigue tests of original ferritic P92 steel at high temperatures and different strain amplitudes were conducted to investigate its cyclic softening behavior and fracture behavior. LCF tests of strain amplitudes ranging from ±0.2% to ±0.8% were performed in fully reversed manner with constant strain rate at 600 °C and 650 °C. In order to represent the different hysteresis stress-strain curves and the cyclic softening behavior of P92 steel, a cyclic plastic material model was used. In the model, improved nonlinear isotropic hardening parameter was proposed to make better simulation of the cyclic softening behavior. Based on the simulated stress-strain hysteresis loops, an energy-based life prediction model was used to predict the low cycle fatigue life. When compared with experimental responses, the simulations and predicted life were found to be quite reasonable. Low cycle fatigue fractography of the P92 steel was also observed, and it was found to be associated with the different strain amplitudes imposed on the specimen, the larger strain amplitude the more amounts of crack initiation sites could be found.

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Characterization of Low Cycle Fatigue Performance of New Ferritic P92 Steel at High Temperature: Effect of Strain Amplitude

steel research international ◽

10.1002/srin.201400246 ◽

2015 ◽

Vol 86 (9) ◽

pp. 1046-1055 ◽

Cited By ~ 22

Author(s):

Xiaowei Wang ◽

Jianming Gong ◽

Yanping Zhao ◽

Yanfei Wang ◽

Minghao Yu

Keyword(s):

High Temperature ◽

Temperature Effect ◽

Strain Amplitude ◽

Low Cycle Fatigue ◽

Fatigue Performance ◽

Cycle Fatigue ◽

P92 Steel ◽

High Temperature Effect

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High-Temperature Low-Cycle Fatigue Behavior of MarBN at 600 °C

Journal of Pressure Vessel Technology ◽

10.1115/1.4031724 ◽

2016 ◽

Vol 138 (4) ◽

Cited By ~ 8

Author(s):

Richard A. Barrett ◽

Eimear M. O'Hara ◽

Padraic E. O'Donoghue ◽

Sean B. Leen

Keyword(s):

High Temperature ◽

Low Cycle Fatigue ◽

Kinematic Hardening ◽

Fatigue Behavior ◽

Strain Range ◽

Material Model ◽

Cyclic Softening ◽

Cyclic Strength ◽

Cycle Fatigue ◽

Viscoplastic Material

This paper presents the high-temperature low-cycle fatigue (HTLCF) behavior of a precipitate strengthened 9Cr martensitic steel, MarBN, designed to provide enhanced creep strength and precipitate stability at high temperature. The strain-controlled test program addresses the cyclic effects of strain-rate and strain-range at 600 °C, as well as tensile stress-relaxation response. A recently developed unified cyclic viscoplastic material model is implemented to characterize the complex cyclic and relaxation plasticity response, including cyclic softening and kinematic hardening effects. The measured response is compared to that of P91 steel, a current power plant material, and shows enhanced cyclic strength relative to P91.

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A Comparison of Amplitude-and Time-Dependent Cyclic Deformation Behavior for Fully-Austenite Stainless Steel 316L and Duplex Stainless Steel 2205

Materials ◽

10.3390/ma14195594 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5594

Author(s):

Shaohua Li ◽

Wenchun Jiang ◽

Xuefang Xie ◽

Zhilong Dong

Keyword(s):

Stainless Steel ◽

Duplex Stainless Steel ◽

Cyclic Deformation ◽

Deformation Behavior ◽

Structural Integrity ◽

Low Cycle Fatigue ◽

Cyclic Softening ◽

Plastic Strain Amplitude ◽

Cyclic Plasticity ◽

Stainless Steel 316L

Austenite and duplex stainless steels are widely used in engineering, and the latter exhibits a more excellent combination of mechanical properties and corrosion resistance due to the coexistence of austenite and ferrite and higher nitrogen. However, fatigue failure still threatens their structural integrity. A comprehensive comparison of their cyclic deformation behavior is a major foundation to understand the role of duplex-phase microstructure and nitrogen in the safety assessment of engineering components. Thus, in this paper, the cyclic deformation behavior of fully-austenitic stainless steel 316L and duplex stainless steel 2205 was studied by a series of low cycle fatigue tests with various strain amplitudes, loading rates and tensile holding. A theoretical mechanism diagram of the interaction between nitrogen and dislocation movements during cyclic loads was proposed. Results show that the cyclic stress response of 2205 was the primary cyclic hardening, followed by a long-term cyclic softening regardless of strain amplitudes and rates, while an additional secondary hardening was observed for 316L at greater strain amplitudes. Cyclic softening of 2205 was restrained under slower strain rates or tensile holding due to the interaction between nitrogen and dislocations. The cyclic plasticity of 2205 started within the austenite, and gradually translated into the ferrite with the elevation of the cyclic amplitude, which lead to a decreased hardening ratio with the increase in amplitude and a shorter fatigue life for a given smaller plastic strain amplitude.

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A Unified Viscoplastic Model for High Temperature Low Cycle Fatigue of Service-Aged P91 Steel

Journal of Pressure Vessel Technology ◽

10.1115/1.4025618 ◽

2014 ◽

Vol 136 (2) ◽

Cited By ~ 19

Author(s):

R. A. Barrett ◽

T. P. Farragher ◽

C. J. Hyde ◽

N. P. O'Dowd ◽

P. E. O'Donoghue ◽

...

Keyword(s):

High Temperature ◽

Power Plants ◽

Low Cycle Fatigue ◽

Kinematic Hardening ◽

Fatigue Behavior ◽

Material Model ◽

Cyclic Softening ◽

Flow Rule ◽

Cycle Fatigue ◽

Hyperbolic Sine

The finite element (FE) implementation of a hyperbolic sine unified cyclic viscoplasticity model is presented. The hyperbolic sine flow rule facilitates the identification of strain-rate independent material parameters for high temperature applications. This is important for the thermo-mechanical fatigue of power plants where a significant stress range is experienced during operational cycles and at stress concentration features, such as welds and branched connections. The material model is successfully applied to the characterisation of the high temperature low cycle fatigue behavior of a service-aged P91 material, including isotropic (cyclic) softening and nonlinear kinematic hardening effects, across a range of temperatures and strain-rates.

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Quantitative Evaluation of Dislocation Structure Induced by Cyclic Plasticity

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.345-346.49 ◽

2007 ◽

Vol 345-346 ◽

pp. 49-52 ◽

Cited By ~ 1

Author(s):

Tsuyoshi Mayama ◽

Katsuhiko Sasaki ◽

Yoshihiro Narita

Keyword(s):

Cyclic Loading ◽

Quantitative Evaluation ◽

Strain Amplitude ◽

Dislocation Structure ◽

Evaluation Method ◽

Cyclic Hardening ◽

Cyclic Softening ◽

Cyclic Plasticity ◽

Loading Test ◽

Loading Tests

In the present study, a new approach is conducted to evaluate dislocation structure induced by cyclic plasticity. First, cyclic plastic loading tests are carried out up to 100 cycles with three different small strain amplitudes on SUS316L stainless steel at room temperature. The test result presents the dependence of the strain amplitude on cyclic hardening and softening behaviors. Specifically, it is found that the cyclic loading test with strain amplitude of 0.25% shows both cyclic hardening and cyclic softening, while the cyclic loading tests with strain amplitudes of 0.75% and 1.0% show no cyclic softening. Secondly, the dislocation structures of the specimens after cyclic loading are observed by using a transmission electron microscope (TEM), and this observation reveals that the dislocation structure after cyclic loading test depends on the strain amplitude. Finally, a quantitative evaluation method of the dislocation structure is also proposed. The TEM images are converted into binary images and the resolution dependence of the generated binary image is used to visualize the characteristics of the dislocation structure. The relationship between strain amplitudes of cyclic plasticity and dislocation structure organization is clarified by the evaluation method. Finally, the heterogeneity of the dislocation structure is discussed.

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Benchmarks for Accelerated Cyclic Plasticity Models with Finite Elements

Metals ◽

10.3390/met10060781 ◽

2020 ◽

Vol 10 (6) ◽

pp. 781

Author(s):

Jelena Srnec Novak ◽

Francesco De Bona ◽

Denis Benasciutti

Keyword(s):

Low Cycle Fatigue ◽

Kinematic Model ◽

Fatigue Loading ◽

Element Model ◽

Cyclic Plasticity ◽

Softening Behavior ◽

Acceleration Technique ◽

Acceleration Techniques ◽

Material State ◽

Number Of Cycles

In numerical simulations of components subjected to low-cycle fatigue loading, the material cyclic plasticity behavior must be modelled until complete stabilization, which occurs approximately at half the number of cycles to failure. If the plastic strain per cycle is small, a huge number of cycles must be simulated, which results into a huge and thus unaffordable simulation time. Acceleration techniques for shortening this time are useful, although their accuracy needs to be checked. This work aims to compare different approaches (nonlinear kinematic with “initial” and “stabilized” parameters and combined nonlinear kinematic and isotropic with the speed of stabilization fictitiously increased). It considers two benchmarks taken from the literature, in which the material has opposite cyclic behaviors (hardening, softening). A plane finite element model can be used in both benchmarks, thus permitting a simulation up to complete stabilization. Results confirm that the common approach of considering only the kinematic model (calibrated on “initial” or “stabilized” material state) from the very first cycle could lead to relevant errors. The acceleration technique based on a fictitious increase in the speed of stabilization leads to accurate results. Guidelines for calibrating this technique on a material’s hardening or softening behavior are, finally, proposed.

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Numerical implementation of a multiaxial cyclic plasticity model for the Local Strain method in low cycle fatigue

Theoretical and Applied Fracture Mechanics ◽

10.1016/j.tafmec.2015.04.005 ◽

2015 ◽

Vol 80 ◽

pp. 111-119 ◽

Cited By ~ 6

Author(s):

C. Madrigal ◽

A. Navarro ◽

V. Chaves

Keyword(s):

Low Cycle Fatigue ◽

Local Strain ◽

Cyclic Plasticity ◽

Plasticity Model ◽

Numerical Implementation ◽

Cycle Fatigue ◽

Cyclic Plasticity Model ◽

Strain Method

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Effects of Thermal Exposure on Low Cycle Fatigue Behavior of Ti600 Titanium Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.118-120.611 ◽

2010 ◽

Vol 118-120 ◽

pp. 611-615

Author(s):

Teng Yu ◽

Lei Wang ◽

Yong Qing Zhao ◽

Yang Liu

Keyword(s):

Titanium Alloy ◽

Strain Amplitude ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Thermal Exposure ◽

Cyclic Softening ◽

Total Strain ◽

Total Strain Amplitude ◽

Cycle Fatigue ◽

Α2 Phase

Effects of thermal exposure on low cycle fatigue behavior of Ti600 alloy were investigated by LSCM, SEM and TEM. The results demonstrated that both the NTE specimens and the TE specimens showed the cyclic softening, within a total strain amplitude range from ±0.45% to ±1.00%. Since the α2 phase precipitated in the αp phase during thermal exposure, the resistance of fatigue crack propagation of αp phase could be increased by the precipitation of α2 phase. Therefore, the low cycle fatigue (LCF) lives of Ti600 alloy after thermal exposure were longer than those without thermal exposure, at the same total strain amplitude.

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