Influence of Temperature on the Strain Controlled Fatigue Behaviour of Alloy 690 Tube Material

2004 ◽  
Author(s):  
Guocai Chai ◽  
Ping Liu ◽  
Johan Frodigh
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Strain Hardening ◽  
Fatigue Crack Initiation ◽  
Cyclic Strain ◽  
Fatigue Behaviour ◽  
Tube Material ◽  
Influence Of Temperature ◽  
Alloy 690 ◽  
Influence Of Temperature On

Strain controlled fatigue tests for hot-extruded tube material of Alloy 690 (Sandvik Sanicro 69) have been performed at room temperature (RT) and at elevated temperature (204°C). The influences of temperature on the cyclic deformation behaviour and the fatigue life have been investigated. The influence of temperature on the fatigue life is relatively small in the temperature range investigated. However, the fatigue behaviour at elevated temperature is quite different from that at RT. A second cyclic strain hardening was observed at 204°C. The possible mechanisms have been investigated using transmission electron microscopy. Besides dislocation mechanism, the interactions between moving dislocations and stacking faults and between interstitial atoms and moving dislocations could also contribute to this secondary cyclic strain hardening. The formation of micro-twins during cyclic loading at 204°C and its influence on the cyclic stress-strain response were also discussed. Temperature affects both fatigue crack initiation and propagation behaviour. Increase in temperature promotes duplex slipping process, which causes the formation of striation.

High-strain low-endurance fatigue behaviour of AISI 1018 steel in reversed torsion

1969 ◽  
Vol 4 (1) ◽  
pp. 45-47 ◽  
Author(s):  
L J Nypan
Keyword(s):  
Fatigue Life ◽  
Shear Strain ◽  
Strain Hardening ◽  
Cross Section ◽  
High Strain ◽  
Circular Cross Section ◽  
Cyclic Strain ◽  
Fatigue Behaviour ◽  
Cyclic Shear ◽  
Hardening And Softening

Experiments in repersed torsion of AISI 1018 solid-steel specimens of circular cross-section are reported. Cyclic strain hardening and softening were observed. The relations between shear strain and fatigue life and between cyclic shear strees and strain are presented.

The Effect of Manufacturing Defects on the Fatigue Behaviour of Ti-6Al-4V Specimens Fabricated Using Selective Laser Melting

2014 ◽  
Vol 891-892 ◽  
pp. 1519-1524 ◽  
Author(s):  
Qian Chu Liu ◽  
Joe Elambasseril ◽  
Shou Jin Sun ◽  
Martin Leary ◽  
Milan Brandt ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Selective Laser Melting ◽  
Fatigue Crack Initiation ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Metallic Materials ◽  
Laser Melting ◽  
Manufacturing Defects ◽  
Materials Properties

Additive Manufacturing (AM) technologies are considered revolutionary because they could fundamentally change the way products are designed. Selective Laser Melting (SLM) is a metal based AM process with significant and growing potential for the manufacture of aerospace components. Traditionally a material needs to be listed in the Metallic Materials Properties Development and Standardization (MMPDS) handbook if it is to be considered certified. However, this requires a considerable amount of test data to be generated on the materials mechanical properties. Therefore, the MMPDS certification process does not lend itself easily to the certification of AM components as the final component can have similar mechanical properties to wrought alloys combined with the defects associated with traditional casting and welding technologies. These defects can substantially decrease the fatigue life of a fabricated component. The primary purpose of this investigation was to study the fatigue behaviour of as-built Ti-6Al-4V (Ti64) samples. Fatigue tests were performed on the Ti-6Al-4V specimens built using SLM with a variety of layer thicknesses and build (vertical or horizontal) directions. Fractography revealed the presence of a range of manufacturing defects located at or near the surface of the specimens. The experimental results indicated that Lack-of-Fusion (LOF) defects were primarily responsible for fatigue crack initiation. The reduction in fatigue life appeared to be affected by the location, size and shape of the LOF defect.

Observation of Fatigue Crack Initiation and Propagation for Carbon and Low-Alloy Steels in Oxygenated Water at Elevated Temperature

2006 ◽  
Author(s):  
Makoto Higuchi ◽  
Katsumi Sakaguchi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Elevated Temperature ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Low Alloy Steels ◽  
Test Conditions ◽  
Alloy Steels ◽  
Crack Initiation Life ◽  
Temperature Water

Low cycle fatigue life of structural materials in LWR plants decreases remarkably in elevated temperature water depending on strain rate, temperature, water chemistry and material properties. The maximum reduction rate in fatigue life for carbon and low alloy steels is over 100 in severe conditions. Fatigue life is composed of fatigue crack initiation life and consequent propagation life. It is important to know the proportion of crack initiation life to propagation life in water environment when developing a model to estimate fatigue crack initiation life. The beachmark imprinting method was used to monitor fatigue crack initiation and consequent propagation. Environmental test conditions varied widely from severely accelerated conditions of high temperature and dissolved oxygen to mild conditions of lower temperature and oxygen. Fatigue crack initiation life could be determined using the beachmark imprinting method for all test conditions. Based on obtained test results, the susceptibility of each parameter in NWC and the relationships between NWC/NW and environmental fatigue life correction factor Fen under various conditions are discussed, but a good relationship could not be detected due to widely scattered data and a model to predict fatigue crack initiation life could not be proposed.

Influence of Temperature on the Fatigue Life of a Quasi-isotropic Gr/Ep Laminate

2003 ◽  
Vol 25 (3) ◽  
pp. 11077
Author(s):  
EA Armanios ◽  
RB Bucinell ◽  
DW Wilson ◽  
KR Uleck ◽  
AJ Vizzini
Keyword(s):  
Fatigue Life ◽  
Influence Of Temperature ◽  
Influence Of Temperature On

scholarly journals INFLUENCE OF TEMPERATURE AND LOADING PROGRAM ON THE FATIGUE LIFE OF STEEL P91

2013 ◽  
Vol 7 (2) ◽  
pp. 93-98
Author(s):  
Stanisław Mroziński ◽  
Michał Piotrowski
Keyword(s):  
Fatigue Life ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Test Results ◽  
Influence Of Temperature ◽  
Program Type ◽  
Influence Of Temperature On ◽  
Two Temperatures ◽  
A Minor ◽  
The Impact

Abstract In this paper there are shown the results of low-cycle fatigue testing of steel P91 samples. During the testing there was conducted a fixed amplitude loading testing as well as programmed loading with various sequence degrees of the program. The testing was done in two temperatures: T=20°C and T=600°C. During the testing a cyclic steel weakening was observed without a clear period of stabilization. Greater changes of the cyclic properties were observed in temperature T=600°C. The influence of temperature on the fatigue life was determined in this paper. This influence is dependent on the degree of strain. It’s a minor one in the range of big strain and increases in the process of decreasing the degree of strain. Furthermore, the impact of the loading program type was determined on the test results and fatigue life calculations

Influence of temperature on low cycle properties of martensitic cast steel

2012 ◽  
Vol 59 (3) ◽  
pp. 329-342 ◽  
Author(s):  
Grzegorz Golanski ◽  
Stanisław Mrozinski ◽  
Krzysztof Werner
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Room Temperature ◽  
Cast Steel ◽  
Cyclic Softening ◽  
Influence Of Temperature ◽  
Influence Of Temperature On ◽  
Two Temperatures ◽  
Stabilization Period

The paper presents the results of research on low cycle properties of highchromium martensitic GX12CrMoVNbN9-1 (GP91) cast steel. The tests of fatigue strength were carried out at two temperatures: room temperature and at 600°C. At both temperatures the occurrence of cyclic softening of the cast steel was observed, revealing no clear stabilization period. Moreover, it has been proved that the fatigue life is influenced by the temperature which depends on the level of strain. The greatest influence was observed for the smallest strain levels applied in the research.

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