DEPENDENCE OF ACOUSTIC EMISSION FOR LOW STRENGTH STEELS UPON THE EMBRITTLEMENT AND THE PLASTIC ZONE REDUCTION AT THE CRACK TIP DURING CORROSION FATIGUE CRACK PROPAGATION

1993 ◽  
Vol 16 (4) ◽  
pp. 441-451 ◽  
Author(s):  
Z. F. Wang ◽  
J. Li ◽  
W. Ke ◽  
Z. Zhu
Keyword(s):  
Acoustic Emission ◽  
Fatigue Crack ◽  
Plastic Zone ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Crack Tip ◽  
Corrosion Fatigue Crack ◽  
Low Strength

Acoustic Emission Study of Corrosion Fatigue Crack Propagation Mechanism Identification

2014 ◽  
Vol 628 ◽  
pp. 20-23
Author(s):  
Hong Chang
Keyword(s):  
Acoustic Emission ◽  
Fatigue Crack ◽  
Magnesium Alloy ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Propagation Mechanism ◽  
Corrosion Fatigue Crack ◽  
X52 Steel ◽  
Crack Propagation Mechanism

Acoustic emission signals were continuously monitored during corrosion fatigue crack propagation for X52 steel in 3.5% NaCl and AZ31 magnesium alloy in 0.1%NaCl solution. There are different microstructure and corrosion fatigue crack propagation mechanism for X52 steel and AZ31B magnesium alloy. Combined with the existing research results of LY12CZ and 7075-T6 aluminum alloys, the acoustic emission waveform parameter, the frequency centroid ratio, was tried to use as a criterion to distinguish the corrosion fatigue crack propagation mechanism for anodic dissolution and hydrogen embrittlement. The results also show that the nature of the acoustic emission source determines the main characteristics of the signal parameters and waveforms, and little to do with the experimental material.

Fatigue Strength Assessment of a Structure Considering Corrosion Wastage and Corrosion Fatigue

2018 ◽  
Author(s):  
Norio Yamamoto ◽  
Tomohiro Sugimoto ◽  
Kinya Ishibashi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Life Assessment ◽  
Actual State ◽  
Corrosive Environment ◽  
Corrosion Fatigue Crack ◽  
Long Life

It is known that the fatigue strength decreases in corrosive environment and many experiments were carried out to comprehend the decrease in fatigue strength in corrosive environment. In order to comprehend the actual state, a cycle speed of fatigue test loads should correspond to a wave frequency. Therefore, an experiment in the long life region is practically difficult, then the corrosion fatigue data available for the life assessment of the structure is quite limited. In this study, the fatigue strength of the welded joints in long life service was evaluated according to the calculations of corrosion fatigue crack propagation subjected to the random loadings which followed an exponential distribution. In the crack propagation calculations, the progress of corrosion wastage from the plate surface and the resultant stress increase were considered simultaneously. In the high stress and the short life region, the decrease in fatigue strength due to the accelerated crack propagation in corrosive environment was dominant because the progress of corrosion wastage was little. On the other hand, in the low stress and the long life region, the decrease in fatigue strength became dull as longer the fatigue life because the corrosion fatigue crack propagation was suppressed by the corrosion wastage, but after that the fatigue strength showed the precipitous decrease due to the increase in stress resulted by the progress of corrosion wastage.

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