scholarly journals Influence of Crystallographic Texture on the High Cycle Fatigue of Extruded AZ31 Magnesium Alloy

2011 ◽  
Vol 690 ◽  
pp. 319-322 ◽  
Author(s):  
Ligia Nascimento ◽  
Sang Bong Yi ◽  
Jan Bohlen ◽  
Dietmar Letzig ◽  
Karl Ulrich Kainer
Keyword(s):  
Crystallographic Texture ◽  
High Cycle Fatigue ◽  
Electron Backscatter Diffraction ◽  
Fatigue Crack Initiation ◽  
Extrusion Direction ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Compression Tests ◽  
Initial Texture

The influence of crystallographic texture on high cycle fatigue behaviour has been studied using an extruded rectangular profile of the AZ31 (Mg-Al-3wt%-Zn-wt1%) alloy. The fatigue samples, cut at 0, 45 and 90° to the extrusion direction correspond to different initial textures. Besides high cycle fatigue tests, quasi-static tensile and compression tests were performed to assess the tension-compression asymmetries as a function of the initial texture. The micro-mechanisms of fatigue crack initiation were investigated using scanning electron microscopy and electron backscatter diffraction. Differences in the mechanical properties and the endurance limit for the different sample directions are related to the initial texture and, subsequently, the easiness or difficulty of slip/twinning.

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

2011 ◽  
Vol 295-297 ◽  
pp. 2386-2389 ◽  
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.

Influence of Ni5Zr Particles on Fatigue Property of Ni3Al Alloy

1994 ◽  
Vol 364 ◽  
Author(s):  
Gang Li ◽  
Jian-Ting Guo ◽  
Zhong-Guang Wang
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Al Alloy ◽  
Second Phase ◽  
Cycle Fatigue ◽  
Second Phase Particles ◽  
Minimum Stress

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).

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

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.

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

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.

Microstructural properties and mechanical behavior of magnesium/hydroxyapatite biocomposite under static and high cycle fatigue loading

2017 ◽  
Vol 52 (13) ◽  
pp. 1711-1722 ◽  
Author(s):  
AS Sabet ◽  
AH Jabbari ◽  
M Sedighi
Keyword(s):  
High Cycle Fatigue ◽  
Particle Distribution ◽  
Testing Machine ◽  
Hot Extrusion ◽  
Fatigue Loading ◽  
Stir Casting ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Compression Tests ◽  
Tension And Compression

In this study, magnesium/hydroxyapatite biocomposites having 2.5 and 5 wt% of hydroxyapatite have been fabricated using stir casting followed by hot extrusion method. Both microstructural and mechanical behaviors of these composites have been studied, which contain particle distribution, grain size, microhardness, tension, and compression tests. Then, high cycle fatigue tests were performed using a rotating-bending testing machine (under stress ratio of R = −1). The results indicate an acceptable particle distribution and grain refinement in the composites. Also, the microhardness of the composites has been increased in comparison with the pure extruded sample. The yield stress has been enhanced in both tension and compression tests by increasing the amount of reinforcement, while the maximum strain reduced. Moreover, the fabricated biocomposites revealed better overall high cycle fatigue life in comparison to pure Mg, and infinite life (>107 cycles) could be achieved in the composites. Scanning electron microscope images of the fracture surfaces showed that the agglomeration of hydroxyapatite particles is one of the most important criteria for crack initiation in the composites.

scholarly journals High-cycle Fatigue Behaviour of S460N Steel Grade Materials and Bolted Joints Processed by Laser Cutting

2018 ◽  
Vol 12 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Gabriele Zanon ◽  
Oreste S. Bursi ◽  
Paolo Scardi ◽  
Mirco D’Incau ◽  
Sergio Raso
Keyword(s):  
Material Properties ◽  
Laser Cutting ◽  
High Cycle Fatigue ◽  
Complex Geometry ◽  
Base Material ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Bolted Connections ◽  
Important Indicator

Background: Prompted by the EN 1090 standard, an important evolution has been observed in recent years about steel structures execution. Laser cutting is appealing for high machining speed and precision in implementation of details with complex geometry, but requires consideration for the effects of the inherent thermal process. Objective: The present study investigates the correlations between material properties altered by the laser cutting process and behaviour of the material and of structural joints subjected to high-cycle fatigue. Method: High-cycle fatigue tests on material samples and on structural bolted connections were carried out in order to correlate the structural response with material properties. For this purpose, hardness and residual stresses were analysed in depth, from the cutting surface inward and specimens processed using different laser cutting parameters and post-annealing treatments were investigated. Results: High-cycle fatigue tests on material samples and on structural bolted connections, processed by laser cutting, show a favourable fatigue behaviour of S460N steel, despite the high values of hardness on cut surface, in agreement with Eurocode 3 fatigue category FAT160 and FAT90, respectively for base material and drilled holes. Conclusion: Structural bolted connections made of S460N steel cut by laser exhibit a favourable fatigue behaviour. Local hardness is an important indicator, favourably complemented by the residual stress distribution to understand the effects of laser cutting and correlate them with the high-cycle fatigue behaviour.

scholarly journals Crack initiation and propagation mechanisms of an extruded dual-phase Magnesium-Lithium alloy in very high cycle fatigue regime

2021 ◽  
Author(s):  
Xiangyu WANG ◽  
Chao HE ◽  
Xue LI ◽  
YongJie Liu ◽  
Qingyuan Wang ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Extrusion Direction ◽  
Cyclic Plasticity ◽  
Dual Phase ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

Ultra-light Mg-Li alloy is a promising alloy in aerospace since it is known to the lightest structural alloy at present, but its fatigue behaviors remain to be explored. This work focuses on very-high cycle fatigue (VHCF) strength and small crack initiation behaviors of an extruded dual-phase Mg-Li alloy (LZ91). The fatigue strength of the LZ91 alloy at 109 cycles is about 78 MPa, and the fatigue ratio is approximately 0.46. Microstructure characterization demonstrates that fatigue crack tends to initiate from the β-Li phase-enriched region. The α-Mg phase, presenting <10−10 >  fiber texture with the basal plane, deforms hardly along the extrusion direction and acts as an enhanced phase compared with the β-Li phase. The deformation discrepancy localizes cyclic plasticity at the Li phase and finally leads to the fatigue crack initiation.

Characteristics of the Deformed and Recrystallised Grains Obtained after Hot Plane Strain Compression of a Model Fe-30wt%Ni Alloy

2004 ◽  
Vol 467-470 ◽  
pp. 21-26 ◽  
Author(s):  
F. Bai ◽  
P. Cizek ◽  
Eric J. Palmiere ◽  
Mark W. Rainforth
Keyword(s):  
Plane Strain ◽  
Crystallographic Texture ◽  
Hot Deformation ◽  
Electron Backscatter Diffraction ◽  
Orientation Dependence ◽  
Plane Strain Compression ◽  
Formation Mechanisms ◽  
Subgrain Structure ◽  
Compression Tests ◽  
Texture Characteristics

The development of physically-based models of microstructural evolution during hot deformation of metallic materials requires knowledge of the grain/subgrain structure and crystallographic texture characteristics over a range of processing conditions. A Fe-30wt%Ni based alloy, retaining a stable austenitic structure at room temperature, was used for modelling the development of austenite microstructure during hot deformation of conventional carbon-manganese steels. A series of plane strain compression tests was carried out at a temperature of 950 °C and strain rates of 10 s-1 and 0.1 s-1 to several strain levels. Evolution of the grain/subgrain structure and crystallographic texture was characterised in detail using quantitative light microscopy and highresolution electron backscatter diffraction. Crystallographic texture characteristics were determined separately for the observed deformed and recrystallised grains. The subgrain geometry and dimensions together with the misorientation vectors across sub-boundaries were quantified in detail across large sample areas and the orientation dependence of these characteristics was determined. Formation mechanisms of the recrystallised grains were established in relation to the deformation microstructure.

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

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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