Effect of Creep in Low-Cycle Fatigue of Pressure Vessel Steel

1970 ◽  
Vol 92 (1) ◽  
pp. 67-73 ◽  
Author(s):  
J. Dubuc ◽  
A. Biron
Keyword(s):  
Pressure Vessel ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Tests ◽  
Pressure Vessel Steel ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Vessel Steel ◽  
The Mean ◽  
Mean Strain

Low-cycle fatigue tests have been carried out at 2 cpm on a pressure vessel steel at 350 deg C (662 deg F). The total strain range was fixed for each test and the minimum (or mean) strain in some cases was constant (zero minimum value), in others increased uniformly in time at a predetermined rate. It was found that variations in the mean strain up to 0.5 percent/hour had no significant influence on the results.

Effect of Mean Stress and of Mean Strain in Low-Cycle Fatigue of A-517 and A-201 Steels

1970 ◽  
Vol 92 (1) ◽  
pp. 35-51 ◽  
Author(s):  
J. Dubuc ◽  
J. R. Vanasse ◽  
A. Biron ◽  
A. Bazergui
Keyword(s):  
Plastic Strain ◽  
Pressure Vessel ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
The Mean ◽  
Mean Strain

A number of low-cycle fatigue tests has been carried out at room temperature on two materials commonly used in pressure vessel fabrication. For strain-controlled tests, the influence of different mean strains is studied; similarly, the effect of varying the mean stress is analyzed for stress-controlled tests. Relations involving elastic and plastic strain ranges, and the variations of strains or stresses during the fatigue tests are discussed.

Effect of Relative Mean Strain in High-Temperature Low-Cycle Fatigue of a Stainless Steel

1975 ◽  
Vol 97 (4) ◽  
pp. 238-242 ◽  
Author(s):  
Thang Bui-Quoc ◽  
Andre Biron
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Axial Strain ◽  
Constant Strain Rate ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
The Mean ◽  
Mean Strain

The effect of the relative mean strain in the low-cycle fatigue of a stainless steel (AISI 304) in air at 650°C and at a constant strain rate (4 × 10−3s−1) is studied. Two modes of strain measurement (axial and diametral) were used separately in nonzero mean strain experiments with controlled axial strain in real time. The effect of the relative mean strain on the fatigue life has been found to be negligible in the range of lives 200 ⩽ N ⩽ 10,000 cycles when the mean strain does not exceed 1.5 times the total range. This effect, however, becomes important when the mean strain is several times the total strain range. In addition, for N < 200 cycles at failure, the effect of even a small value of the mean strain appears to be significant. The extension of a method previously developed is presented for establishing the high-temperature fatigue behavior under isothermal conditions with positive mean strain. On the basis of the results of a short-term tensile test, the technique gives predictions in good agreement with experimental data.

Low Cycle Fatigue Damage in Pressure-Vessel Materials

1963 ◽  
Vol 85 (4) ◽  
pp. 539-545 ◽  
Author(s):  
J. G. Sessler ◽  
Volker Weiss
Keyword(s):  
Pressure Vessel ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Property Changes ◽  
Failure Life ◽  
Damage Processes ◽  
The Relationship ◽  
Mean Strain ◽  
Strain Cycling

Strain-controlled tension-compression fatigue tests were performed on the ASTM pressure vessel steels, A302 and A225, to study the damage processes that lead to failure in low cycle fatigue. The measurements of static property changes in partially cycled specimens, and hysteresis loop effects obtained during cycling, were utilized to reflect the pattern of damage accumulation. In addition, strain cycling tests were conducted on these materials to assess the applicability of the relationship Nf=εF−ε0εTR2 as proposed by Manson [4] and Coffin [5] and modified by Sachs, et al. [6]. The experimental data obtained were in good agreement with the failure life and the effect of mean strain as predicted by the foregoing equation. Accordingly, a positive mean strain (prestrain in tension) reduces fatigue life, since the fracture strain available for cycling is reduced by the amount of the prestrain. The damage studies indicated, however, that this equation cannot be used to describe the progress of damage during strain cycling. Rather, it appears that damage is governed by at least two, possibly interdependent, processes; namely, the loss of available ductility due to strain hardening and the formation and growth of cracks which finally determine failure. Both processes are reflected in the remaining ductility after partial cycling. At present, it is not clear how the two processes combine to yield the experimentally confirmed relationship, Nf=εF−ε0εTR2.

HIGH TEMPERATURE LOW CYCLE FATIGUE AND FRACTURE CHARACTERISTIC IN TWO SINGLE CRYSTAL SUPERALLOYS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2892-2897
Author(s):  
J. J. YU ◽  
Z. H. WANG ◽  
X. F. SUN ◽  
T. JIN ◽  
H. R. GUAN ◽  
...  
Keyword(s):  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Tests ◽  
Total Strain ◽  
Stress Axis ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Refractory Elements ◽  
Fatigue And Fracture

Total strain controlled low cycle fatigue tests were conducted at 1173K for DD32 and SRR99 alloys. With the increase of total strain range, the stress amplitude of DD32 alloy improved more fleetly than that of SRR99 alloy. At total strain ranges less than or equal to 1.0%, the low cycle fatigue life of DD32 alloy was greater than that of SRR99 alloy. It was shown that the higher content of refractory elements in DD32 alloy resulted in a remarkable improvement of LCF properties compared to SRR99 alloy. The crack propagation perpendicular to the stress axis occurred in transgranular mode in both alloys. DD32 alloy presented more ductile character than SRR99 alloy.

Low Cycle Fatigue Behavior of Alloy 800H Base Metal and Weldments at 700°C

2018 ◽  
Author(s):  
Seon-Jin Kim ◽  
Rando Tungga Dewa ◽  
Woo-Gon Kim ◽  
Eung-Seon Kim
Keyword(s):  
Base Metal ◽  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Fatigue Tests ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Alloy 800H ◽  
Total Strain Range

Alloy 800H is currently being considered as one of the near-term candidate materials for design and construction of some major high temperature components of a very high temperature reactor (VHTR). System start-ups and shut-downs as well as power transients will produce low-cycle fatigue loadings of components. The aim of this work is to study the low cycle fatigue behavior of Alloy 800H base metal and weldments at 700°C. The weldment specimens were machined from gas tungsten arc welding (GTAW) butt-welded plate such that the loading direction was oriented transverse to the welding direction. Fully reversed total-strain controlled low-cycle fatigue tests have been performed at total strain ranges of 0.6, 0.9, 1.2 and 1.5%. For all the low-cycle fatigue tests, triangular test waveforms with a constant strain rate of 10−3/s were applied. Low-cycle fatigue testing was conducted in accordance with ASTM Standard E606 on servo-hydraulic test machines. And also, creep-fatigue experiments were carried out at 700°C employing 0.6% total strain range and 10−3/s strain rate using trapezoidal waveform with tension hold time. The main focus is to characterize the low-cycle fatigue properties for Alloy 800H weldment specimens from the cyclic deformation behavior and fatigue fracture behavior. The cyclic deformation behavior was influenced by total strain range and material property. The fatigue life was decreased with increasing the total strain range for both base metal and weldment. However, the lives of weldment specimens have a longer life than that of base metal at lower total strain ranges. It was also observed that creep effects play a significant role in fatigue life reduction.

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