scholarly journals Effect of Tempering Temperature on Very High Cycle Fatigue Behavior in Low-Alloy Steel, SNCM439

2008 ◽  
Vol 57 (9) ◽  
pp. 905-912 ◽  
Author(s):  
Kazuaki SHIOZAWA ◽  
Nobuhiro SHIBATA ◽  
Yasuhiro MARUYAMA
Keyword(s):  
Alloy Steel ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Low Alloy Steel ◽  
Tempering Temperature ◽  
Very High Cycle Fatigue ◽  
Very High

Very high cycle fatigue properties of Cr–Mo low alloy steel containing V-rich MC type carbides

2016 ◽  
Vol 651 ◽  
pp. 311-320 ◽  
Author(s):  
Weijun Hui ◽  
Yongjian Zhang ◽  
Xiaoli Zhao ◽  
Chao Zhou ◽  
Kaizhong Wang ◽  
...  
Keyword(s):  
Alloy Steel ◽  
High Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Low Alloy Steel ◽  
Very High Cycle Fatigue ◽  
Very High

scholarly journals Fractography and Crack Initiation of Very-High-Cycle Fatigue for a High Carbon Low Alloy Steel

2006 ◽  
Vol 324-325 ◽  
pp. 1113-1116 ◽  
Author(s):  
Cheng En Zhou ◽  
Gui An Qian ◽  
You Shi Hong
Keyword(s):  
Fracture Mechanics ◽  
Alloy Steel ◽  
Fatigue Failure ◽  
High Cycle Fatigue ◽  
Fatigue Cracks ◽  
Cycle Fatigue ◽  
Low Alloy Steel ◽  
Crack Origin ◽  
Very High Cycle Fatigue ◽  
Very High

Very-High-Cycle Fatigue (VHCF) is the phenomenon of fatigue damage and failure of metallic materials or structures subjected to 108 cycles of fatigue loading and beyond. This paper attempts to investigate the VHCF behavior and mechanism of a high strength low alloy steel (main composition: C-1% and Cr-1.5%; quenched at 1108K and tempered at 453K). The fractography of fatigue failure was observed by optical microscopy and scanning electron microscopy. The observations reveal that, for the number of cycles to fatigue failure between 106 and 4×108 cycles, fatigue cracks almost initiated in the interior of specimen and originated at non-metallic inclusions. An “optical dark area” (ODA) around initiation site is observed when fatigue initiation from interior. ODA size increases with the decrease of fatigue stress, and becomes more roundness. Fracture mechanics analysis gives the stress intensity factor of ODA, which is nearly equivalent to the corresponding fatigue threshold of the test material. The results indicate that the fatigue life of specimens with crack origin at the interior of specimen is longer than that with crack origin at specimen surface. The experimental results and the fatigue mechanism were further analyzed in terms of fracture mechanics and fracture physics, suggesting that the primary propagation of fatigue crack within the fish-eye local region is the main characteristics of VHCF.

scholarly journals Mechanical Properties and Very High Cycle Fatigue Behavior of Peak-Aged AA7021 Alloy

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1023 ◽  
Author(s):  
Byung-Hoon Lee ◽  
Sung-Woo Park ◽  
Soong-Keun Hyun ◽  
In-Sik Cho ◽  
Kyung-Taek Kim
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Solution Treated ◽  
Very High Cycle Fatigue ◽  
Peak Aged ◽  
Very High

The effect of heat treatment condition on non-Cu AA7021 alloy was investigated with respect to mechanical properties and very high cycle fatigue behavior. With a focus on the influence of heat treatment, AA7021 alloy was solution heat-treated at 470 °C for 4 h and aged at 124 °C. Comparing the results of solution-treated and peak-aged AA7021 alloy shows a significant increase in Vickers hardness and tensile strength. The hardness of AA7021 alloy was increased by 65% after aging treatment, and both tensile strength and yield strength were increased by 50~80 MPa in each case. In particular, this paper investigated the very high cycle fatigue behavior of AA7021 alloy with the ultrasonic fatigue testing method using a resonance frequency of 20 kHz. The fatigue results showed that the stress amplitude of peak-aged AA7021 alloy was about 50 MPa higher than the solution-treated alloy at the same fatigue cycles. Furthermore, it was confirmed that the size of the crack initiation site was larger after peak aging than after solution treatment.

Influence of Reinforcement Geometry on the Very High-Cycle Fatigue Behavior of Aluminium-Matrix-Composites

2015 ◽  
Vol 825-826 ◽  
pp. 150-157 ◽  
Author(s):  
Alexandra Müller ◽  
Anja Weidner ◽  
Horst Biermann
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

During technical operation, high performance materials are partially exposed to high frequency cyclic loading conditions. Furthermore, the small strains in the very high cycle fatigue (VHCF)-regime lead to accumulative damage which causes crack initiation related to an appropriate local deformation leading to final fatal fracture. At the same time, quite high requirements with regard to high number of cycles without any damage are demanded for many applications. Fields of application of these light-weight, but expensive materials, are e.g. in the automobile industry (e.g. engine blocks, cylinder heads, brakes).The fatigue behavior of Al-matrix composites (Al-MMCs) reinforced by alumina particles (15 vol.% Al2O3) or short fibers (20 vol.% Saffil), respectively, was already intensively studied in the LCF and HCF range. The present study is focusing on investigations in the very high cycle fatigue regime at stress amplitudes up to 140 MPa to reach fatigue life of about 1010 cycles. All experiments were carried out using an ultrasonic fatigue testing device under symmetric loading conditions (R=-1). Fatigue tests were accompanied by in situ thermography measurements to record the temperature of the whole specimen and to find “hot spots” indicating changes in microstructure and therefore the initiation or growth of cracks. Moreover, the resonant frequency as well as the damage parameter were evaluated to determine the beginning of damage. For a better understanding of the damage mechanism (matrix decohesion, matrix failure or failure of reinforcement) all fractured surfaces were investigated by scanning electron microscopy. The combination of these methods contributes to a better understanding of the underlying mechanism of damage in aluminum-matrix-composites.

The Influence of Microstructure Heterogeneities on the Very High Cycle Fatigue Behavior of Duplex Stainless Steel

2016 ◽  
Vol 258 ◽  
pp. 255-258
Author(s):  
Ulrich Krupp ◽  
Marcus Söker ◽  
Tina Waurischk ◽  
Alexander Giertler ◽  
Benjamin Dönges ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Ion Beam ◽  
Cyclic Plasticity ◽  
Cycle Fatigue ◽  
Heterogeneous Distribution ◽  
Very High Cycle Fatigue ◽  
Structural Applications ◽  
Very High

As being used for structural applications, where a high corrosion resistance is required, the fatigue behavior of duplex stainless steels (DSS) is governed by the partition of cyclic plasticity to the two phases, ferrite and austenite, respectively. Under very high cycle fatigue (VHCF) loading conditions, the heterogeneous distribution of crystallographic misorientations between neighboring grains and phases yields to a pronounced scatter in fatigue life, ranging from 1 million to 1 billion cycles for nearly the same stress amplitude. In addition, the relevant damage mechanisms depend strongly on the atmosphere. Stress corrosion cracking in NaCl-containing atmosphere causes a pronounced decrease in the VHCF life. By means of ultrasonic fatigue testing at 20kHz in combination with high resolution scanning electron microscopy, electron back-scattered diffraction (EBSD), focused ion beam milling (FIB) and synchrotron tomography, the microstructure heterogeneities were quantified and correlated with local fatigue damage. It has been shown that the fatigue process is rather complex, involving redistribution of residual stresses and three-dimensional barrier effects of the various interfaces. The application of a 2D/3D finite element model allows a qualitative prediction of the fatigue-damage process in DSS that is controlled by stochastic local microstructure arrangements.

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