scholarly journals Study on High-Cycle Fatigue Behaviors and Fracture Mechanism of RuT450

2020 ◽  
Author(s):  
MengXiao Zhang ◽  
JianChao Pang ◽  
Meng Lingjian ◽  
Li Shouxin ◽  
Liu Qingyi ◽  
...  
Keyword(s):  
Cast Iron ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Prediction Method ◽  
Threshold Value ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Graphite Phase ◽  
Graphite Cast Iron ◽  
Different Temperatures

Fatigue failure is the most common failure mode of structural materials. In this study, the high-cycle fatigue properties at different temperatures, fracture surface morphologies and corresponding damage mechanisms of a widely used vermicular graphite cast iron RuT450 were investigated. It is found that the fatigue strength of RuT450 decreases with the increase of temperature, and the decreasing rate is affected by the change of morphology and content of graphite. In general, the cracks initiated from the graphite phase boundary and propagated through the pearlite lamellae. In addition, according to the change of matrix micro-structure and the slight change of graphite morphology at different temperatures, and combined with the change of crack propagation threshold value under different temperature conditions, a fatigue strength prediction method for vermicular graphite cast iron at different temperatures was proposed in this work, which has high prediction accuracy.

The Effects of Specimen Size on the Very High Cycle Fatigue Properties of FV520B-I

2015 ◽  
Author(s):  
Ming Zhang ◽  
Weiqiang Wang ◽  
Aiju Li
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Specimen Size ◽  
Fatigue Properties ◽  
Test Results ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Heat Effects ◽  
Very High

The authors researched the effects of specimen size on the very high cycle fatigue properties of FV520B-I through ultrasonic fatigue testing. The test results showed that the very high cycle fatigue mechanism was not changed and the fatigue properties declined as the specimen size increased. The S-N curve moved downward and the fatigue life decreased under the same stress level maybe due to the heat effects of large specimens in tests. The fatigue strength and the fatigue life were predicted by relevant models. The prediction of fatigue strength was close to test result, and the prediction of fatigue life was less effective compared with the previous prediction of small size specimen test results.

scholarly journals Effect of Carburizing and Nitriding on Fatigue Properties of 18Cr2Ni4WA Steel in Very High Cycle Fatigue Regime

2021 ◽  
Vol 45 (3) ◽  
pp. 207-215
Author(s):  
Zhenduo Sun ◽  
Dongbo Hou ◽  
Wei Li
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Internal Defect ◽  
Surface Fatigue ◽  
Very High Cycle Fatigue ◽  
The Relationship ◽  
Very High

The work aims to study the influence of carburizing and nitriding on fatigue properties of 18Cr2Ni4WA high strength steel in very high cycle fatigue regime. Very high cycle fatigue tests were carried out on 18Cr2Ni4WA Steel after carburizing and nitriding respectively. The micro morphology of fatigue fracture was observed by scanning electron microscope, the failure mode and failure mechanism were discussed. The relationship between fatigue life and defect size, FGA size, fish eye size of fracture was analyzed. The characteristic size of defects is evaluated by Gumbel, Weibull and GEV distribution functions, and a modified Akiniwa fatigue life prediction model considering the relationship between FGA size and inclusion size was established. The results showed that, nitriding and carburizing treatment improve the surface fatigue limit of the steel. The fatigue life decreases with the increase of internal defect size and FGA size. After carburizing and nitriding treatment, the internal fatigue strength of the specimen decreases slightly. When the failure probability is 99%, the internal defect sizes of nitrided specimens calculated by Weibull, Gumbel and GEV distributions are 141.5 μm, 148.4 μm and 211.7 μm respectively. The calculated internal defect sizes of carburized specimens are 47 μm, 67.8 μm and 40 μm respectively. Compared with the experimental data, the fatigue strength predicted by GEV is the most appropriate. carburizing and nitriding treatment can improve the surface fatigue strength of 18Cr2Ni4WA steel, but slightly reduce the internal fatigue strength. The prediction result of the new model is conservative when the failure probability is 99%, which is suitable for engineering application.

High cycle fatigue behavior of Al1070 alloy severely deformed by equal channel angular pressing process

2016 ◽  
Vol 232 (6) ◽  
pp. 514-519 ◽  
Author(s):  
Mohammad Bagher Limooei ◽  
Morteza Zandrahimi ◽  
Ramin Ebrahimi
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Equal Channel Angular Pressing ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Pure Aluminum ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Angular Pressing ◽  
Pressing Process

In the present work, equal channel angular pressing of commercial pure aluminum 1070 was performed up to 4 passes using route Bc. For equal channel angular pressing operation, a suitable die set was designed and manufactured. X-ray diffraction analysis was used to determine the microstructure of the equal channel angular pressing-ed material. The fracture surface morphology and microstructure after fatigue were investigated by scanning electron microscopy. Mechanical properties of the equal channel angular pressing-ed material were evaluated by hardness and tension tests. Also, cyclic deformation behavior of severe plastic deformation Al1070 has been studied and results show a significant variation in hardness, ultimate strength and fatigue properties in high cycle fatigue life. Coefficient of fatigue strength σ′f and Bridgman correction factor have been obtained by S-N curve and tension test specimens, respectively, and compared before and after equal channel angular pressing process. Also an useful relation has been derived between fatigue life ( Nf) and stress amplitude ( σa) in high cycle fatigue region. Results indicated that there was not clear relation between fatigue strength coefficient and true corrected fracture stress in this case.

High-Cycle Fatigue Properties of Carbon Steel and Work-Hardened Oxygen Free Copper in High Pressure Hydrogen

2014 ◽  
Vol 891-892 ◽  
pp. 575-580 ◽  
Author(s):  
Masanobu Kubota ◽  
Kota Kawakami
Keyword(s):  
High Pressure ◽  
Fatigue Strength ◽  
Carbon Steel ◽  
Detrimental Effect ◽  
High Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Slip Bands ◽  
Slip Deformation ◽  
Pressure Hydrogen

The high-cycle fatigue properties of 0.35% carbon steel and work-hardened oxygen-free copper in 10MPa hydrogen were studied. The fatigue limit of the carbon steel in hydrogen was almost the same as that in air. The fatigue strength at 107cycles of the copper was higher in hydrogen than in air. The fatigue life of both materials is longer in hydrogen than in air. The reason was the delays in the crack initiation and the early propagation of the cracks in hydrogen. For both materials, the detrimental effect on the fatigue strength due to the hydrogen environment was small, however, it was determined that hydrogen participates in the slip deformation. The morphology of the slip bands was specific in hydrogen. In the copper, the slip bands, which are non-viable in air, developed in hydrogen.

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