Low cycle fatigue stress-strain relation model of cyclic hardening or cyclic softening materials

1996 ◽  
Vol 54 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Hong-Xue Shang ◽  
Hao-Jiang Ding
Keyword(s):  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Cyclic Softening ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Fatigue Stress ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
Relation Model

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

2015 ◽  
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.

scholarly journals Low-Cycle Fatigue Behaviour of a Ni-Based Single-Crystal Superalloy

2014 ◽  
Vol 891-892 ◽  
pp. 416-421 ◽  
Author(s):  
Mikael Segersäll ◽  
Johan Moverare ◽  
Daniel Leidermark ◽  
Kjell Simonsson
Keyword(s):  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Fatigue Behaviour ◽  
Single Crystal Superalloy ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Tension Compression Asymmetry

In this study, low-cycle fatigue (LCF) tests at 500 °C in the <001>, <011> and <111> directions have been performed for the Ni-based single-crystal superalloy MD2. All tests were carried out in strain control with Rε=-1. The <001> direction has the lowest stiffness of the three directions and also shows the best fatigue properties in this study followed by the <011> and <111> directions, respectively. It is well recognised that Ni-based single-crystal superalloys show a tension/compression asymmetry in yield strength and this study shows that a tension/compression asymmetry also is prevalent during LCF conditions. At mid-life, the <001> direction generally has a higher stress in tension than in compression, while the opposite is true for the <011> direction. For the <111> direction the asymmetry is found to be strain range dependent. The <011> and <111> directions show a cyclic hardening behaviour when comparing cyclic stress-strain curves with monotonic stress-strain curves. In addition, the <011> and <111> directions show a serrated yielding behaviour for a number of cycles while the yielding of the <001> direction is more stable.

Low-Cycle Fatigue Behavior of an Al-Mg-Si Alloy with and without a Small Addition of Sc

2010 ◽  
Vol 654-656 ◽  
pp. 938-941 ◽  
Author(s):  
Chihiro Watanabe ◽  
Ryoichi Monzen
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cyclic Hardening ◽  
Cyclic Softening ◽  
Strengthening Effect ◽  
Cycle Fatigue ◽  
Slip Bands ◽  
Transmission Electron ◽  
Peak Aging ◽  
Bearing Alloy

Low-cycle fatigue behavior of a wrought Al-0.8wt%Mg-0.7wt%Si alloy with and without 0.27wt%Sc has been investigated at room temperature under constant plastic-strain amplitudes. After peak-aging treatments, both the alloys had fine lath-shaped β' precipitates. In the Sc-containing alloy, spherical Al3Sc precipitates of about 11 nm in diameter were co-existed. The alloy with Sc exhibited cyclic hardening to saturation, while the alloy without Sc showed clear cyclic softening after initial hardening. Transmission electron microscopy observation revealed that slip band structures were developed in the Sc-free alloy. Within the slip bands, shearing of the β' precipitates by moving dislocations was often observed. The cyclic softening in the alloy without Sc can then be explained by a loss of precipitation strengthening effect through the precipitation destruction within strongly-strained slip bands. In the Sc-bearing alloy, owing to the existence of non-shearable Al3Sc precipitates, dislocations were uniformly distributed, resulting in the absence of the cyclic softening.

scholarly journals Influence of the surface morphology on the cyclic deformation behavior of HSD® 600 steel

2018 ◽  
Vol 165 ◽  
pp. 06010 ◽  
Author(s):  
Matthias W. Klein ◽  
Marek Smaga ◽  
Tilmann Beck
Keyword(s):  
Surface Morphology ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Cyclic Softening ◽  
Single Step ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Surface Morphologies

The presented research work investigates the fatigue properties in the low cycle fatigue (LCF) regime of the high manganese metastable austenitic High Strength and Ductility (HSD®) 600 TWIP steel dependent on its surface morphology. The steel features, according to its chemical composition following the alloying concept Mn-Al-Si-C and heat treatment, a fully austenitic microstructure that shows deformation induced twinning at ambient temperature. Due to this microstructural deformation mechanism, HSD® 600 steel has an outstanding combination of strength and formability. Besides monotonic deformation behavior, characterized by tensile tests, cyclic deformation behavior was investigated with varying the surface morphology of fatigue specimens. In order to create different surface morphologies, flat fatigue specimens were excised from larger sheets by waterjet-cutting. Depending on the surface morphology, further climb milling or up-climb milling in the gauge length was performed. The three investigated morphologies (asreceived with rolling skin, climb milled and up-climb milled) differed in roughness, initial residual stresses and initial phase compositions. For all variants, total strain controlled fatigue tests with stepwise increasing load amplitudes as well as total strain controlled single step tests were performed in the low cycle fatigue regime with a load ratio of Rε = -1 and a frequency of f = 0.2 Hz. Beside stress-strain hystereses, the changes in temperature ΔT and the magnetic properties ξ were measured. The magnetic properties directly correlate with the transformation from paramagnetic γ-austenite to ferromagnetic α’-martensite. The cyclic deformation behavior of the HSD® 600 steel in the LCF regime was characterized by cyclic softening until fracture at low total strain amplitudes but changed with increasing total strain amplitudes into initial cyclic hardening followed by cyclic softening. This initial cyclic hardening became more pronounced when the total strain amplitude increased. Furthermore, single step tests at lower total strain amplitudes showed a saturation state before fracture. A comparison between the monotonic and cyclic deformation behavior showed a significant difference of the stress levels at the same amounts of plastic deformation respectively. Nevertheless, the different surface morphologies led to different lifetimes at high total strain amplitudes but to similar lifetimes at lower total strain amplitudes.

Low Cycle Fatigue Behaviour of ODS Steels for Nuclear Application

2011 ◽  
Vol 465 ◽  
pp. 556-559 ◽  
Author(s):  
Ivo Kuběna ◽  
Tomáš Kruml ◽  
Benjamin Fournier ◽  
Jaroslav Polák
Keyword(s):  
Ferritic Steel ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Fatigue Behaviour ◽  
Cyclic Softening ◽  
Oxide Dispersion ◽  
Cycle Fatigue ◽  
Oxide Particles ◽  
Ods Steels

This study deals with the low cycle fatigue (LCF) behaviour of two steels strengthened by oxide dispersion. The ODS Eurofer steel shows cyclic softening, slower than in the case of the same steel without oxide particles. The 14Cr ODS ferritic steel is cyclically stable, even a slight cyclic hardening is observed at 650 °C. The reasons for this different behaviour lie probably in the less resistant matrix with a lot of weak subgrain boundaries in ODS Eurofer, because no clear difference in the oxide particles distribution was found.

Low Cycle Fatigue Behaviour of Al-Mg-Si Alloy AA6061 Processed by Equal Channel Angular Pressing

2012 ◽  
Vol 463-464 ◽  
pp. 97-101
Author(s):  
C.V. Venkatesh ◽  
S. Ganesh Sundara Raman ◽  
Chakkingal Uday
Keyword(s):  
Equal Channel Angular Pressing ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Fatigue Behaviour ◽  
Cyclic Softening ◽  
Cycle Fatigue ◽  
Angular Pressing ◽  
Processed Material ◽  
Number Of Passes

The low cycle fatigue (LCF) behaviour of aluminium-magnesium-silicon alloy AA6061 processed by equal channel angular pressing (ECAP) was studied. Solutionized specimens of the alloy were subjected to one, two and three passes of ECAP at room temperature using route Bc. Compared to the values of the solutionized material an overall increase in yield strength and ultimate tensile strength with decrease in % elongation is observed for the ECAP processed material. While the solutionized material exhibits cyclic hardening at all strain levels, the ECAP processed material shows different behaviour depending on the number of passes - stable response/cyclic softening/ softening followed by hardening. The ECAP processed material after three passes exhibit superior LCF lives at low strains presumably due to higher strength and large refinement of grains.

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