High and Low Cycle Fatigue of Orthorhombic Ti-22Al-27Nb Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 589-594
Author(s):  
Masuo Hagiwara ◽  
A. Araoka ◽  
Satoshi Emura
Keyword(s):  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Lamellar Microstructure ◽  
Control Mode ◽  
Load Control ◽  
Cycle Fatigue ◽  
Lamellar Morphology ◽  
R Ratio ◽  
Fatigue Mechanism

The effect of the lamellar morphology on the high cycle fatigue (HCF) and low cycle fatigue (LCF) behavior of the Ti-22Al-27Nb alloy was investigated. The HCF tests were performed in air at an R ratio of 0.1 in the load-control mode, whereas the LCF tests were performed in vacuum at 923 K in the strain-controlled mode. The specimens with fine lamellar microstructure exhibited a better resistance to HCF than those with coarse lamellar microstructure. The microstructure-insensitive behavior was, however, observed in the LCF tests at 923 K. The fatigue mechanism was discussed based on the concurrent observation of the initiation facet and the underlying microstructure, and the TEM observations.

scholarly journals Effect of size of alpha phases on cyclic deformation and fatigue crack initiation during fatigue of an alpha-beta titanium alloy

2018 ◽  
Vol 165 ◽  
pp. 15006
Author(s):  
Qiaoyan Sun ◽  
Changsheng Tan ◽  
Lin Xiao ◽  
Jun Sun
Keyword(s):  
Fatigue Crack ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Lamellar Microstructure ◽  
Alpha Phase ◽  
Cycle Fatigue ◽  
Beta Titanium Alloy ◽  
Beta Titanium ◽  
Alpha Beta ◽  
Equiaxed Alpha

Alpha phase exhibits equiaxed or lamellar morphologies with size from submicron to microns in an alpha-beta titanium alloy. Cyclic deformation, slip characteristics and crack nucleation during fatigue in different microstructures of TC21 alloy (Ti-6Al-2Sn-2Zr-3Mo-1Cr-2Nb-0.1Si) were systematically investigated and analyzed. During low-cycle fatigue, equiaxed microstructure (EM) in TC21 alloy exhibits higher strength, ductility and longer low-cycle fatigue life than those of the lamellar microstructure (LM). There are more voids in the single lamellar alpha than the equiaxed alpha grains. As a result, voids more easily link up to form crack in the lamellar alpha phase than the equiaxed alpha phase. However, during high-cycle fatigue, the fine lamellar microstructure (FLM) shows higher fatigue limit than bimodal microstructure (BM). The localized plastic deformation can be induced during high-cycle fatigue. The slip bands or twins are observed in the equiaxed and lamellar alpha phases(>1micron), which tends to form strain concentration and initiate fatigue crack. The localized slip within nanoscale alpha plates is seldom observed and extrusion/intrusion dispersedly distributed on the sample surface in FLM. This indicates that FLM show super resistance to fatigue crack which bring about higher fatigue limit than BM.

A New Modified Contrast Method for Life Prediction in Combined Cycle Fatigue Test

2017 ◽  
Author(s):  
Lei Han ◽  
Cao Chen ◽  
Xiaoyong Zhang ◽  
Xiaojun Yan
Keyword(s):  
Turbine Blade ◽  
High Cycle Fatigue ◽  
Aerodynamic Force ◽  
Low Cycle Fatigue ◽  
Fracture Morphology ◽  
Combined Cycle ◽  
Full Scale ◽  
Cycle Fatigue ◽  
Contrast Method ◽  
Ultra High Cycle Fatigue

The combined high and low cycle fatigue (CCF) test on full scale turbine blade in the laboratory is an important method to evaluate the life. In fact, the low cycle fatigue which is usually caused by the centrifugal force can be confirmed easily. While, the high cycle fatigue which is usually caused by the vibration and aerodynamic force is often hard to determine. So the previous scholar has proposed the contrast method to determine the high cycle load in the field. This method utilizes the new and used blades to determine the high cycle within certain limits. While it can’t be applied effectively in the whole life range with the low cycle-high cycle-ultra high cycle fatigue theory raised. So this paper put forward the modified contrast method to realize the optimization. Firstly, the CCF tests are carried out on the turbine blade systematically. Then, the CCF damage properties, including the crack propagation, the fracture morphology and the dynamic characteristic are analyzed. Lastly, the new modified contrast method is proposed with the new coordinate axes, new fitting criterions and amend method. Through comparisons we conclude that: the new method is slightly complicated, but the evaluate precision has significantly increased. So it could be used to deal with data for CCF tests on full scale turbine blade in the future.

scholarly journals High Cycle Fatigue Appearance of 10wt% cr steel and Dissimilar Metal Weld

2021 ◽  
Vol 9 (VI) ◽  
pp. 2185-2202
Author(s):  
Hilal Ahmad Shah
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Cycle Fatigue ◽  
Crack Initiation And Propagation ◽  
R Ratio ◽  
Initiation And Propagation ◽  
Different Temperatures ◽  
Fracture Surface Analysis ◽  
Metal Weld

The present study deals with the high cycle fatigue (HCF) behavior of a ten wt% Cr steel at ambient also as high temperatures (300–853 K). S–N curves were created at unlike temperatures using an R-ratio of −1. Outcome of mean stress was established over and done with Haigh diagram at 853 K using different R-values. Fatigue life was found to decrease with upsurge in test temperature and stress amplitude. Fatigue life was attempted using Basquin equation. Detailed fracture surface analysis was performed to study the crack initiation and propagation modes towards empathetic the mechanisms of failure at different temperatures.

scholarly journals Effect of Sandblasting on Low and High-Cycle Fatigue Behaviour after Mechanical Cutting of a Twinning-Induced Plasticity Steel

2018 ◽  
Vol 165 ◽  
pp. 18002
Author(s):  
Antoni Lara ◽  
Mercè Roca ◽  
Sergi Parareda ◽  
Núria Cuadrado ◽  
Jessica Calvo ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Twip Steel ◽  
Low Cycle Fatigue ◽  
Load Ratio ◽  
Fatigue Behaviour ◽  
Cycle Fatigue ◽  
High Manganese ◽  
Amplitude Control ◽  
Cut Edge ◽  
Mechanical Cutting

In the last years, car bodies are increasingly made with new advanced high-strength steels, for both lightweighting and safety purposes. Among these new steels, high-manganese or TWIP steels exhibit a promising combination of strength and toughness, arising from the austenitic structure, strengthened by C, and from the twinning induced plasticity effect. Mechanical cutting such as punching or shearing is widely used for the manufacturing of car body components. This method is known to bring about a very clear plastic deformation and therefore causes a significant increase of mechanical stress and micro-hardness in the zone adjacent to the cut edge. To improve the cut edge quality, surface treatments, such as sandblasting, are often used. This surface treatment generates a compressive residual stress layer in the subsurface region. The monotonic tensile properties and deformation mechanisms of these steels have been extensively studied, as well as the effect of grain size and distribution and chemical composition on fatigue behaviour; however, there is not so much documentation about the fatigue performance of these steels cut using different strategies. Thus, the aim of this work is to analyse the fatigue behaviour of a TWIP steel after mechanical cutting with and without sandblasting in Low and High-Cycle Fatigue regimes. The fatigue behaviour has been determined at room temperature with tensile samples tested with a load ratio of 0.1 and load amplitude control to analyse High-Cycle Fatigue behaviour; and a load ratio of -1 and strain amplitude control to determine the Low-Cycle Fatigue behaviour. Samples were cut by shearing with a clearance value of 5%. Afterwards, a part of the cut specimens were manually blasted using glass microspheres of 40 to 95 microns of diameter as abrasive media. The results show a beneficial effect of the sandblasting process in fatigue behaviour in both regimes, load amplitude control (HCF) and strain amplitude control (LCF) tests, when these magnitudes are low, while no significant differences are observed with higher amplitudes. low-cycle fatigue, high-cycle fatigue, mechanical cutting, sandblasting, high manganese steel, TWIP steel

scholarly journals Fatigue life time modelling of Cu and Au fine wires

2018 ◽  
Vol 165 ◽  
pp. 06002
Author(s):  
Golta Khatibi ◽  
Ali Mazloum-Nejadari ◽  
Martin Lederer ◽  
Mitra Delshadmanesh ◽  
Bernhard Czerny
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Load Ratio ◽  
Life Time ◽  
Material Model ◽  
Cycle Fatigue ◽  
Rate Dependency

In this study, the influence of microstructure on the cyclic behaviour and lifetime of Cu and Au wires with diameters of 25μm in the low and high cycle fatigue regimes was investigated. Low cycle fatigue (LCF) tests were conducted with a load ratio of 0.1 and a strain rate of ~2e-4. An ultrasonic resonance fatigue testing system working at 20 kHz was used to obtain lifetime curves under symmetrical loading conditions up to very high cycle regime (VHCF). In order to obtain a total fatigue life model covering the low to high cycle regime of the thin wires by considering the effects of mean stress, a four parameter lifetime model is proposed. The effect of testing frequency on high cycle fatigue data of Cu is discussed based on analysis of strain rate dependency of the tensile properties with the help of the material model proposed by Johnson and Cook.

Transition From Low Cycle to High Cycle in Uniaxial Fatigue

2013 ◽  
Author(s):  
Mohamed E. M. El-Sayed
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Uniaxial Stress ◽  
Life Assessment ◽  
Elastic Behavior ◽  
Cycle Fatigue ◽  
Fatigue Life Assessment ◽  
Component Development

Fatigue is the most critical failure mode of many mechanical component. Therefore, fatigue life assessment under fluctuating loads during component development is essential. The most important requirement for any fatigue life assessment is knowledge of the relationships between stresses, strains, and fatigue life for the material under consideration. These relationships, for any given material, are mostly unique and dependent on its fatigue behavior. Since the work of Wöhler in the 1850’s, the uniaxial stress versus cycles to fatigue failure, which is known as the S-N curve, is typically utilized for high-cycle fatigue. In general, high cycle fatigue implies linear elastic behavior and causes failure after more than 104 or 105 cycles. However. the transition from low cycle fatigue to high cycle fatigue, which is unique for each material based on its properties, has not been well examined. In this paper, this transition is studied and a material dependent number of cycles for the transition is derived based on the material properties. Some implications of this derivation, on assessing and approximating the crack initiation fatigue life, are also discussed.

A Perspective on Fatigue Damage by Decoupling LCF and HCF Loads in a Type 316LN Stainless Steel

2015 ◽  
Vol 34 (5) ◽  
Author(s):  
Aritra Sarkar ◽  
A. Nagesha ◽  
R. Sandhya ◽  
M.D. Mathew
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Fatigue Damage ◽  
Strain Amplitude ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Applied Strain ◽  
Cycle Fatigue ◽  
316Ln Stainless Steel ◽  
Type 316Ln Stainless Steel

AbstractPrior low cycle fatigue (LCF) deformation in a 316LN austenitic stainless steel reduced the remnant high cycle fatigue (HCF) life as a function of the amount of LCF exposure and the applied strain amplitude. A critical LCF pre-damage was found necessary for an effective LCF-HCF interaction to take place.

Effects of Pre-Damage on HCF Behaviors of Ti-6Al-4V Alloy

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1994-2000
Author(s):  
Taewon Park ◽  
Shankar Mall ◽  
Thedore Nicholas
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Loading Test ◽  
Progressive Change ◽  
Loading Method ◽  
Step Loading ◽  
Damage Condition

The effects of pre-damage on the fatigue strength of Ti-6Al-4V were investigated by applying the low cycle fatigue(LCF) as a pre-damage prior to high cycle fatigue(HCF) test. The fatigue strengths were obtained by means of step-loading method. The pre-damage condition was decided as 900MPa, 0.5R, 50,000 cycles through LCF test, and was introduced before step-loading test. The fatigue strength of Ti-6Al-4V alloy derived from step-loading test without pre-damage was about 639MPa. The introduction of pre-damage deteriorates the fatigue strength about 6%. Progressive change in elongation with increasing cycles was observed. The strain accumulated by pre-damage varies the displacement in the next loading step, but afterward this doesn't change the displacement any more. The strain formed by pre-damage is thought to result in earlier failure and lower fatigue strength.

Sign in / Sign up

Export Citation Format

Share Document