Influence of Ni5Zr Particles on Fatigue Property of Ni3Al Alloy

AbstractIn this investigation, the influence of second phase particles on high cycle fatigue behavior of Ni3Al alloy is studied. A single phase Ni3Al-B alloy and a Ni3Al-B/Zr alloy with a few second phase particles (Ni5Zr) at the grain boundaries are selected for investigation. High cycle fatigue tests at room temperature with R (minimum stress/maximum stress) 0.1 are conducted in air and at 30 Hz. The results show that the second phase particles are detrimental to high cycle fatigue resistance. It may be explained in terms of the second phase particles promoting fatigue crack initiation. The characteristics of fracture surfaces are examined by Scanning Electron Microscopy (SEM).

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Effect of Plasma Nitriding on Ultra-High Cycle Fatigue Behaviors of Ti-6Al-4V

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.295-297.2386 ◽

2011 ◽

Vol 295-297 ◽

pp. 2386-2389 ◽

Cited By ~ 1

Author(s):

Ren Hui Tian ◽

Qiao Lin Ouyang ◽

Qing Yuan Wang

Keyword(s):

High Cycle Fatigue ◽

Plasma Nitriding ◽

Fatigue Behavior ◽

Fatigue Crack Initiation ◽

Fatigue Tests ◽

Fatigue Properties ◽

Cycle Fatigue ◽

Ultrasonic Fatigue ◽

Ultra High Cycle Fatigue ◽

Stress Ratios

In order to investigate the effect of plasma nitriding treatment on fatigue behavior of titanium alloys, very high cycle fatigue tests were carried out for Ti-6Al-4V alloy using an ultrasonic fatigue machine under load control conditions for stress ratios of R=-1 at frequency of ƒ=20KHz. Experiment results showed that plasma nitriding treatment played the principal role in the internal fatigue crack initiation. More importantly, plasma nitriding treatment had a detrimental effect on fatigue properties of the investigated Ti-6Al-4V alloy, and the fatigue strength of material after plasma nitriding treatment appeared to be significantly reduced about 17% over the untreated material.

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Effect of Aqueous Environment on High Cycle and Very-High-Cycle Fatigue Behavior for a Structural Steel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.462-463.355 ◽

2011 ◽

Vol 462-463 ◽

pp. 355-360

Author(s):

You Shi Hong ◽

Gui An Qian

Keyword(s):

Fatigue Strength ◽

Structural Steel ◽

High Cycle Fatigue ◽

Fatigue Behavior ◽

Fatigue Crack Initiation ◽

Fatigue Tests ◽

Aqueous Environment ◽

Cycle Fatigue ◽

Very High Cycle Fatigue ◽

Very High

In this paper, rotary bending fatigue tests for a structural steel were performed in laboratory air, fresh water and 3.5% NaCl aqueous solution, respectively, thus to investigate the influence of environmental media on the fatigue propensity of the steel, especially in high cycle and very-high-cycle fatigue regimes. The results show that the fatigue strength of the steel in water is remarkably degraded compared with the case tested in air, and that the fatigue strength in 3.5% NaCl solution is even lower than that tested in water. The fracture surfaces were examined to reveal fatigue crack initiation and propagation characteristics in air and aqueous environments.

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Effect of corrosion and sandblasting on the high cycle fatigue behavior of reinforcing B500C steel bars

Frattura ed Integrità Strutturale ◽

10.3221/igf-esis.42.2 ◽

2017 ◽

Author(s):

Marina C. Vasco ◽

Panagiota Polydoropoulou ◽

Apostolos N. Chamos ◽

Spiros G. Pantelakis

Keyword(s):

Mass Loss ◽

High Cycle Fatigue ◽

Fatigue Behavior ◽

Salt Spray ◽

Fatigue Tests ◽

Tensile Behavior ◽

Loading Frequency ◽

Reinforcing Steel ◽

Cycle Fatigue ◽

Steel Bars

In a series of applications, steel reinforced concrete structures are subjected to fatigue loads during their service life, what in most cases happens in corrosive environments. Surface treatments have been proved to represent proper processes in order to improve both fatigue and corrosion resistances. In this work, the effect of corrosion and sandblasting on the high cycle fatigue behavior reinforcing steel bars is investigated. The investigated material is the reinforcing steel bar of technical class B500C, of nominal diameter of 12 mm. Steel bars specimens were first exposed to corrosion in alternate salt spray environment for 30 and 60 days and subjected to both tensile and fatigue tests. Then, a series of specimens were subjected to common sandblasting, corroded and mechanically tested. Metallographic investigation and corrosion damage evaluation regarding mass loss and martensitic area reduction were performed. Tensile tests were conducted after each corrosion exposure period prior to the fatigue tests. Fatigue tests were performed at a stress ratio, R, of 0.1 and loading frequency of 20 Hz. All fatigue tests series as well as tensile test were also performed for as received steel bars to obtain the reference behavior. The results have shown that sandblasting hardly affects the tensile behavior of the uncorroded material. The effect of sandblasting on the tensile behavior of pre-corroded specimens seems to be also limited. On the other hand, fatigue results indicate an improved fatigue behavior for the sandblasted material after 60 days of corrosion exposure. Martensitic area reductions, mass loss and depth of the pits were significantly smaller for the case of sandblasted materials, which confirms an increased corrosion resistance.

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High-cycle fatigue tests of pretensioned concrete beams

PCI Journal ◽

10.15554/pcij67.1-02 ◽

2022 ◽

Vol 67 (1) ◽

Author(s):

Jörn Remitz ◽

Martin Empelmann

Keyword(s):

Fatigue Life ◽

High Cycle Fatigue ◽

Concrete Beams ◽

Fatigue Behavior ◽

Fatigue Tests ◽

Design Methods ◽

Test Results ◽

Cycle Fatigue ◽

Pretensioned Concrete ◽

Current Design

Pretensioned concrete beams are widely used as bridge girders for simply supported bridges. Understanding the fatigue behavior of such beams is very important for design and construction to prevent fatigue failure. The fatigue behavior of pretensioned concrete beams is mainly influenced by the fatigue of the prestressing strands. The evaluation of previous test results from the literature indicated a reduced fatigue life in the long-life region compared with current design methods and specifications. Therefore, nine additional high-cycle fatigue tests were conducted on pretensioned concrete beams with strand stress ranges of about 100 MPa (14.5 ksi). The test results confirmed that current design methods and specifications overestimate the fatigue life of embedded strands in pretensioned concrete beams.

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High Cycle Fatigue Behavior of Recycled Additive Manufactured Electron Beam Melted Titanium Ti6Al4V

Volume 2A: Advanced Manufacturing ◽

10.1115/imece2020-24194 ◽

2020 ◽

Author(s):

Melody Mojib ◽

Rishi Pahuja ◽

M. Ramulu ◽

Dwayne Arola

Keyword(s):

Electron Beam ◽

Fatigue Life ◽

Rough Surface ◽

High Cycle Fatigue ◽

Fatigue Behavior ◽

High Strength ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Initiation And Propagation ◽

Powder Recycling

Abstract Metal Additive Manufacturing (AM) has become a popular method for producing complex and unique geometries, especially gaining traction in the aerospace and medical industries. With the increase in adoption of AM and the high cost of powder, it is critical to understand the effects of powder recycling on part performance to move towards material qualification and certification of affordable printed components. Due to the limitations of the Electron Beam Melting (EBM) process, current as-printed components are susceptible to failure at limits far below wrought metals and further understanding of the material properties and fatigue life is required. In this study, a high strength Titanium alloy, Ti-6Al-4V, is recycled over time and used to print fatigue specimens using the EBM process. Uniaxial High Cycle Fatigue tests have been performed on as-printed and polished cylindrical specimens and the locations of crack initiation and propagation have been determined through the use of a scanning electron microscope. This investigation has shown that the rough surface exterior is far more detrimental to performance life than the powder degradation occurring due to powder reuse. In addition, the effects of the rough surface exterior as a stress concentration is evaluated using the Arola-Ramulu. The following is a preliminary study of the effects powder recycling and surface treatments on EBM Ti-6Al4V fatigue life.

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Effect of LCF Pre-Damage on Very High Cycle Fatigue Behavior of TC21 Titanium Alloy

10.20944/preprints201710.0182.v1 ◽

2017 ◽

Author(s):

Nie Baohua ◽

Zhao Zihua ◽

Ouyang Yongzhong ◽

Chen Dongchu ◽

Chen Hong ◽

...

Keyword(s):

Titanium Alloy ◽

Crack Initiation ◽

High Cycle Fatigue ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Fatigue Crack Initiation ◽

Mechanism Analysis ◽

Cycle Fatigue ◽

Very High Cycle Fatigue ◽

Very High

The effect of low cycle fatigue (LCF) pre-damage on the subsequent very high cycle fatigue (VHCF) behavior is investigated in TC21 titanium alloy. LCF pre-damage is applied under 1.8% strain amplitude up to various fractions of the expected life and subsequent VHCF properties are determined using ultrasonic fatigue tests. Results show that 5% of LCF pre-damage insignificantly affects the VHCF limit due to the absent of pre-crack, but decreases the subsequent fatigue crack initiation life estimated by Pairs’ law. Pre-cracks introduced by 10% and 20% of LCF pre-damage significantly reduce the subsequent VHCF limits. The crack initiation site shifts from subsurface-induced fracture for undamaged and 5% of LCF pre-damage specimens to surface pre-crack for 10% and 20% of LCF pre-damage specimens in very high cycle region. The fracture mechanism analysis indicate that LCF pre-crack will re-start to propagate under subsequently low stress amplitude when stress intensity factor of pre-crack is larger than its threshold. Furthermore, the predicted fatigue limits based on EI Haddad model for the LCF pre-damage specimens well agree with the experimental results.

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x-The Effect of Microstructure on the Corrosion Fatigue Property of A7N01P-T4 Aluminum Alloy Welding Joints

CORROSION ◽

10.5006/2805 ◽

2018 ◽

Vol 74 (11) ◽

pp. 1229-1236

Author(s):

Feng Xiao ◽

Jiangli An ◽

Hui Chen ◽

P. Li ◽

Wei Gao

Keyword(s):

Grain Boundaries ◽

Corrosion Fatigue ◽

Fatigue Property ◽

Short Crack ◽

Al Alloy ◽

Second Phase ◽

Test Results ◽

Second Phase Particles ◽

The Matrix ◽

Almost All

The corrosion fatigue short crack propagation (CFSCP) behavior of A7N01P-T4 Al alloy welded joints in 3.5 wt% NaCl solution has been investigated. The test results indicate that the CFSCP followed a cyclical type of growth. Microscopic study shows that almost all second-phase particles are distributed along the grain boundary areas. These particles were easily dissolved during the corrosion fatigue test, resulting in weak grain boundaries. Therefore, the fatigue short crack will grow along the winding grain boundaries. While the second-phase particles on the grain boundaries were the main factor to cause the intergranular crack. Transgranular cracking may occur to the coarse grains in the matrix, which indicate that grain size also has a strong influence on the CFSCP behavior of A7N01P-T4 Al alloy.

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Interactions between geometrical defects and microstructure during high cycle fatigue of polycrystalline aluminium with different grain sizes

MATEC Web of Conferences ◽

10.1051/matecconf/201816514004 ◽

2018 ◽

Vol 165 ◽

pp. 14004

Author(s):

Benoît Bracquart ◽

Charles Mareau ◽

Nicolas Saintier ◽

Franck Morel

Keyword(s):

Grain Size ◽

Fatigue Crack ◽

Crack Initiation ◽

High Cycle Fatigue ◽

Fatigue Behavior ◽

Fatigue Crack Initiation ◽

Cycle Fatigue ◽

Grain Sizes ◽

Average Grain Size ◽

Geometrical Defects

In this work, the influence of the geometrical defect size on the high cycle fatigue behavior of polycrystalline aluminium with different grain sizes is investigated, to better understand the role of internal length scales. Two sizes of grains and defect are used: 100 μm and 1000 μm, the grain size being controlled with thermomechanical treatments. Fully reversed stress-controlled fatigue tests are then carried out. According to fatigue test results, surface crack initiation is delayed when the grain size is reduced, while an approximation of the fatigue limit shows that it is not much influenced by the average grain size. The relative defect diameter (compared to the grain size) seems to be the leading parameter influencing fatigue crack initiation from a defect. Finally, Electron BackScattered Diffraction (EBSD) maps are collected for specimens with large grains and small defects. Fatigue crack initiation from a defect is found to be strongly impacted by the crystallographic orientation of the surrounding grain, crack initiation preferably occurring in crystals being favorably oriented for plastic slip.

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Effect of Stress Ratio and Loading Mode on High Cycle Fatigue Properties of Extruded Magnesium Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.891-892.557 ◽

2014 ◽

Vol 891-892 ◽

pp. 557-562

Author(s):

Kazuaki Shiozawa ◽

Atsushi Ikeda ◽

Tsuyoshi Fukumori

Keyword(s):

Magnesium Alloys ◽

Stress Ratio ◽

High Cycle Fatigue ◽

Stress Amplitude ◽

Fatigue Crack Initiation ◽

High Stress ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Loading Mode ◽

Amplitude Level

The aim of this study is to discuss an effect of stress ratio and loading mode on high cycle fatigue performances of extruded magnesium alloys. Axial loading fatigue tests under three conditions of stress ratio, R, of 0, -1 and-1.5, and also rotating bending fatigue tests have been performed in laboratory air at room temperature using hourglass shaped specimens of AZ31, AZ61, AZ80 and T5-treated AZ80 alloy. From the experimental results, some materials showed a specific stepwise S-N curve on which two knees appear. The shape of S-N diagram depended on a kind of tested materials, applied stress ratio and loading mode. It was suggested from the detail observation of fracture surface that fatigue crack initiation mechanism changed from a twin-induced failure mode at high stress amplitude level to a slip-induced one at low stress amplitude level. This transition was determined with the relation between the minimum stress during a fatigue cycle and the compressive yield stress at which deformation twin occurs.

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