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.

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 AND LIFE PREDICTION OF A CAST COBALT-BASED SUPERALLOY

2012 ◽  
Vol 06 ◽  
pp. 251-256
Author(s):  
HO-YOUNG YANG ◽  
JAE-HOON KIM ◽  
KEUN-BONG YOO
Keyword(s):  
Fatigue Life ◽  
Strain Energy ◽  
Life Prediction ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Different Temperatures

Co -base superalloys have been applied in the stationary components of gas turbine owing to their excellent high temperature properties. Low cycle fatigue data on ECY-768 reported in a companion paper were used to evaluate fatigue life prediction models. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of Cobalt-based super alloy at different temperatures. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

Low Cycle Fatigue Characteristics of a Low-Thermal Expansion, High Strength Alloy (HAYNES 242 Alloy)

2011 ◽  
Author(s):  
L. M. Pike ◽  
S. K. Srivastava
Keyword(s):  
Thermal Expansion ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
High Strength ◽  
Wave Form ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Low Thermal Expansion ◽  
Long Range Ordering

HAYNES® 242® alloy, based primarily on the Ni-25Mo-8Cr system, derives its low thermal expansion characteristics from its composition and its high strength concomitant with high ductility from a long-range ordering reaction upon an aging heat treatment. This combination has enabled the alloy continually to find a challenging range of applications in the aerospace industry at up to 1300°F (704°C). These include seal rings, containment rings, duct segments, casings, rocket nozzles, etc. In conjunction with the creep strength and environmental resistance, the low cycle fatigue (LCF) behavior is an important material property affecting the service life of 242 alloy components. The low cycle fatigue behavior of 242 alloy was studied under fully reversed strain-controlled mode at 800°F (427°C), 1000°F (538°C), 1200°F (649°C) and 1400°F (760°C) using a triangular wave form with a frequency of 0.33 Hz. Results are presented in terms of cycles to crack initiation and failure. The magnitudes of fatigue lives at total strain range ≤ 0.7% at 800, 1000 and 1200°F are significantly greater than those of solid solution strengthened alloys. Additionally, stress-controlled LCF tests were performed at 1200°F (649°C) on 242 alloy as well as 909 alloy (for comparison). The paper will discuss the results of these two test programs.

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.

Influence of specimen diameter size on the deformation behavior and short-term strength range of an aluminum alloy

2020 ◽  
Vol 62 (4) ◽  
pp. 345-350
Author(s):  
Benjamin Seisenbacher ◽  
Richard Klösch ◽  
Gerhard Winter ◽  
Florian Grün
Keyword(s):  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Material Behavior ◽  
Cycle Fatigue ◽  
Mean Values ◽  
Strain Behavior ◽  
Specimen Diameter ◽  
Local Material

Abstract Components often manifest varied local behavior due to their manufacturing process. In order to be able to determine local material behavior in the best possible way, it is necessary to take specimens from the area under investigation. Due to constant developments in efficiency and lightweight construction, it is difficult to produce standard-compliant specimens from the examined area in a component. For this reason, specimens with smaller dimensions are often taken. Through the investigation of the influence of size in the area of high-cycle fatigue, it is well known that the size of a test specimen influences its lifespan. Not so much is known about the influence of specimen size on the behavior of material in the field of low-cycle fatigue (LCF). In this work, tensile, LCF and thermomechanical fatigue tests are performed using AlCu4PbMgMn with varied specimen geometries, the smallest test diameter being 3 mm, the largest 7.5 mm. The results of the tensile test show that the mean values of tensile strength for both diameters is within one percent. At LCF load and thermomechanical load, there are no or only slight deviations in deformation behavior. The low cycle fatigue behavior at RT is identical for both diameters. However, the results show that stress-strain behavior is the same for both test diameters, and fatigue behavior is the same, except in tests with high strain amplitudes and temperature.

Low Cycle Fatigue of Alloy 617 at 850 °C and 950 °C

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
J. K. Wright ◽  
L. J. Carroll ◽  
J. A. Simpson ◽  
R. N. Wright
Keyword(s):  
Strain Rate ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Solute Drag ◽  
Cycle Fatigue ◽  
Alloy 617 ◽  
Total Strain Range ◽  
Cycles To Failure

The low cycle fatigue behavior of Alloy 617 has been evaluated at 850 °C and 950 °C, the temperature range of particular interest for the intermediate heat exchanger on a proposed high-temperature gas-cooled nuclear reactor. Cycles to failure were measured as a function of total strain range and varying strain rate. Results of the current experiments compare well with previous work reported in the literature for a similar range of temperatures and strain rate. The combined data demonstrate a Coffin–Manson relationship, although the slope of the Coffin–Manson fit is close to −1 rather than the typically reported value of −0.5. At 850 °C and a strain rate of 10−3 /s Alloy 617 deforms by a plastic flow mechanism in low cycle fatigue and exhibits some cyclic hardening. At 950 °C for strain rates of 10−3–10−5 /s, Alloy 617 deforms by a solute drag creep mechanism during low cycle fatigue and does not show significant cyclic hardening or softening. At this temperature the strain rate has little influence on the cycles to failure for the strain ranges tested.

Low Cycle Fatigue Life Evaluation According to Temperature and Orientation in Nickel-Base Superalloy

2019 ◽  
Vol 814 ◽  
pp. 121-126
Author(s):  
In Kang Heo ◽  
Dong Hyun Yoon ◽  
Jae Hoon Kim
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Total Strain ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Materials Used ◽  
Nickel Base

Components of gas turbines must be extremely resistant to high temperatures, high stresses, high-temperature corrosion, and erosive environments. The materials used in these environmental conditions are mainly nickel-based superalloys. In this study, the low-cycle fatigue of the nickel-based superalloy Inconel 792 was examined. The total strain range of a gas turbine between 760 °C and 870 °C was considered as the parameter representing the actual gas turbine operation. In addition, tests were performed using a trapezoidal waveform of the total strain to reflect the operation-stop conditions of a gas turbine with frequent shutdowns. The results of the fatigue test were compared with the Coffin–Manson method and energy method. The fractured surface was analyzed using a scanning electron microscope (SEM).

Low-Cycle Fatigue Behavior of Internally Pressurized Boxes

1967 ◽  
Vol 89 (3) ◽  
pp. 427-435 ◽  
Author(s):  
M. R. Gross ◽  
R. E. Heise
Keyword(s):  
Aluminum Alloy ◽  
Yield Strength ◽  
Thick Plate ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Complex Structures ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Structural Applications

One phase of a continuing study of the low-cycle fatigue behavior of metals for deep submergence structural applications involves the validity of simple specimen results when applied to complex structures. As a part of this study, the low-cycle fatigue performance of twelve internally pressurized boxes was investigated. The boxes were constructed from 1-in-thick plate of six materials consisting of three steels, one aluminum alloy, and two titanium alloys. The boxes were cyclically pressurized at peak nominal stresses up to about 80 percent of the yield strength of the base metal. The results are compared with data previously obtained for simple laboratory specimens. The results of the box tests tend to confirm two general conclusions reached previously from simple specimen tests, that is: (1) Increases in low-cycle fatigue strength for a given life are not commensurate with increases in yield strength, and (2) low-cycle fatigue life is closely related to total strain range and appears to be independent of both structural metal and strength level in the life range of 1000 to 30,000 cycles.

Tensile and Fatigue Properties of Miniature Size Specimens of Sn-5Sb Lead-Free Solder

2016 ◽  
Vol 879 ◽  
pp. 2377-2382 ◽  
Author(s):  
Kyosuke Kobayashi ◽  
Ikuo Shohji ◽  
Hiroaki Hokazono
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Phase Boundary ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Total Strain ◽  
Effect Of Temperature ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Total Strain Range

Tensile and low cycle fatigue properties of Sn-5Sb (mass%) solder were investigated with miniature size tensile specimens. The effect of temperature and strain rate on tensile properties and the effect of temperature on low cycle fatigue properties were examined. Tensile strength increases with increasing strain rate regardless of temperature investigated. For elongation, the effect of temperature on it is negligible although it slightly increases with increasing strain rate. The low cycle fatigue life of Sn-5Sb obeys by the Manson-Coffin’s equation. The effect of temperature on the fatigue life is negligible in the temperature range from 25 oC to 150 oC. In the low cycle fatigue test with a high total strain range of 4%, cracking at phase boundary mainly occurs regardless of temperature investigated. In the case of a low total strain range of 0.4%, ductile fracture mainly occurs, and cracking at phase boundary with generation of grooves also occurs at high temperature.

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