Cyclic Plasticity and Cyclic Creep in Austenitic-Ferritic Duplex Steel

2011 ◽  
Vol 465 ◽  
pp. 431-434
Author(s):  
Jaroslav Polák ◽  
Martin Petrenec ◽  
Jiří Man ◽  
Tomáš Kruml
Keyword(s):  
Creep Rate ◽  
Plastic Strain ◽  
Strain Amplitude ◽  
Cyclic Creep ◽  
Cyclic Stress ◽  
Plastic Strain Amplitude ◽  
Cyclic Plasticity ◽  
Stress Strain ◽  
Duplex Steel ◽  
Mean Stresses

Smooth specimens made from austenitic-ferritic duplex steel were subjected to constant stress amplitude loading with positive mean stresses. Hysteresis loops were recorded during the fatigue life and plastic strain amplitude and cyclic creep rate were determined. Fatigue hardening/softening curves, cyclic creep curves and cyclic stress-strain curves for different positive mean stresses were evaluated. Typical dislocation structures developed in both phases of the duplex steel were identified using TEM, compared with the saturated plastic strain amplitude and correlated with the decrease of the cyclic creep rate during cycling and the slope of the cyclic stress-strain curve.

Fatigue Behavior of Ferritic-Pearlitic-Bainitic Steel – Effect of Positive Mean Stress

2009 ◽  
Vol 417-418 ◽  
pp. 577-580
Author(s):  
Jaroslav Polák ◽  
Martin Petrenec
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Strain Amplitude ◽  
Fatigue Behavior ◽  
Cyclic Creep ◽  
Plastic Strain Amplitude ◽  
Fatigue Properties ◽  
Mean Stress ◽  
Bainitic Steel ◽  
The Mean

The fatigue properties of ferritic-pearlitic-bainitic steel using specimens produced from massive forging were measured in stress controlled regime with positive mean stress. The cyclic creep curves and cyclic hardening/softening curves were evaluated. The fatigue life was plotted in dependence on the mean stress and on the plastic strain amplitude. The principal contribution to the drop of the fatigue life with the mean stress is due to the increase of the plastic strain amplitude in cycling with mean stress.

Cyclic Stress in 316L Austenitic Stainless Steel at Low Temperatures

2007 ◽  
Vol 567-568 ◽  
pp. 401-404 ◽  
Author(s):  
Jaroslav Polák ◽  
Martin Petrenec ◽  
Jiří Man
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Plastic Strain ◽  
Strain Amplitude ◽  
Stress Component ◽  
Hysteresis Loops ◽  
Cyclic Stress ◽  
Plastic Strain Amplitude ◽  
Test Method ◽  
Step Test

Austenitic stainless steel was cycled at a series of temperatures in the interval from 296 K to 113 K. Constant plastic strain amplitude loading at different levels of plastic strain amplitude and testing similar to multiple step test method were applied at different temperatures. The stress amplitude was continually recorded and selected hysteresis loops were stored and later analyzed using statistical theory of the hysteresis loop. Effective stress component and probability density function as a function of temperature were evaluated. The results were discussed in terms of the temperature dependence of the cyclic yield stress and its sources.

Cyclic Deformation of Al-Mg Single Crystals with a Single Slip Orientation

2007 ◽  
Vol 561-565 ◽  
pp. 2213-2216
Author(s):  
Toshiyuki Fujii ◽  
Shizuma Uju ◽  
Chihiro Watanabe ◽  
Susumu Onaka ◽  
Masaharu Kato
Keyword(s):  
Plastic Strain ◽  
Single Crystals ◽  
Strain Amplitude ◽  
Strain Curve ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Plastic Strain Amplitude ◽  
Solid Solution Hardening ◽  
Plateau Stress ◽  
Single Slip

Fully reversed tension-compression fatigue tests were performed on solid-solutioned Al-0.7mass%Mg single crystals with a single slip orientation under constant plastic-strain amplitudes. Dislocation microstructures were quantitatively examined by transmission electron microscopy. The cyclic stress–strain curve (CSSC) exhibited three distinct regions with a short plateau region in the intermediate plastic-strain amplitude range, and the plateau stress was 26MPa. Characteristic microstructures were developed corresponding to the three regions in the CSSC. Vein structure was observed at the low strain-amplitude region. In the plateau regime, the persistent slip bands (PSBs) were observed. Labyrinth structure was also observed at the higher strain-amplitude region. The plateau stress, the cyclic flow stress of PSBs, can be explained by considering not only the Orowan bowing stress and the dipole passing stress of screw dislocations but also solid-solution hardening by Mg atoms.

Cyclic Plastic Response and Fatigue Life of Materials

2007 ◽  
Vol 348-349 ◽  
pp. 113-116 ◽  
Author(s):  
Jaroslav Polák
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Crack Growth ◽  
Strain Amplitude ◽  
Decisive Role ◽  
Cyclic Stress ◽  
Plastic Strain Amplitude ◽  
Short Crack ◽  
Plastic Response ◽  
Cyclic Plastic

Recently the decisive role of plastic strain amplitude for the initiation and the growth rate of short cracks has been demonstrated. The plastic strain amplitude can be related to the rate of short crack growth and also to the fatigue life. Since the cyclic stress-strain response of a material determines the plastic strain amplitude it influences basically its fatigue life. The experiments in stress and plastic strain controlled loading and short crack growth are presented and used to demonstrate the importance of the cyclic plastic response for the evaluation of the fatigue life.

Low-Cycle Fatigue of AISI 1010 Steel at Temperatures up to 1200°F (649°C)

1977 ◽  
Vol 99 (3) ◽  
pp. 432-443 ◽  
Author(s):  
C. E. Jaske
Keyword(s):  
Plastic Strain ◽  
Fatigue Resistance ◽  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cyclic Stress ◽  
Cyclic Life ◽  
Stress Strain ◽  
Plastic Strain Range ◽  
Tensile Hold

This program was undertaken to develop isothermal low-cycle fatigue information for AISI 1010 steel in air. Such information is needed to help predict acceptable conditions for equipment and structures operating at elevated temperatures. Tensile properties and cyclic stress-strain behavior were also developed. For lives between 103 and 106 cycles to failure, fatigue curves were developed at 70, 400, 600, 800, 1000, and 1200°F (21, 204, 316, 427,538, and 649°C). Data for these curves were obtained from constant-amplitude, fully reversed strain-cycling tests of axially loaded specimens. Results from the same experiments were used to define cyclic stress-strain curves at each of the above temperatures. Dynamic strain aging caused a maximum amount of cyclic hardening at 600°F (316°C). In terms of stress amplitude, the maximum fatigue strength was at 600°F (316°C). In terms of either total strain range or plastic strain range, the maximum fatigue resistance was at 400°F (204°C). At temperaures above 600°F (316°C), fatigue resistance decreased as temperature increased. Tensile hold periods caused a significant reduction in cyclic life at 800 and 1000°F (427 and 538°C) but had no noticeable effect on cyclic life at 600°F (316°C). Fatigue resistance was quantified in terms of power functions relating fatigue life to both plastic strain range and stress amplitude, and cyclic stress-strain response was quantified in terms of a power function relating stress amplitude to plastic strain amplitude. The method of strain-range partitioning provided good cyclic life predictions for the limited number of tensile hold-time experiments, although other types of hold periods were not evaluated.

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