220
W. Zhang et al.
instability expansion. At this stage, the specimen breaks rapidly, the material releases
a large number of AE signals, and the count value increases significantly, which is
consistent with the trend of Fig. 19.6. In addition, some studies have pointed out that if
materials with different properties are subjected to different heat treatment processes,
the acoustic emission source in the crack propagation stage will be inconsistent [19–
21]. To explore the AE source in each stage of this process, further research is required
Research to further determine the relationship between the AE signal and the fatigue
crack growth mechanism of different heat treatment processes and materials with
different properties.
19.4 Conclusion
1. The acoustic emission process of fatigue crack growth of TC4 titanium alloy
can be divided into three distinct stages, corresponding to the initiation zone,
steady-state extension zone and unstable fracture zone of fatigue crack. In the
crack initiation stage, the AE signal exhibits higher activity, and the amplitude of
the AE signal in the stable expansion stage decreases. It is presumed that due to
the increase in the dislocation density and the difficulty of dislocation movement,
the material in the crack instability expansion stage quickly breaks, and the AE
signal amplitude Significantly increased.
2. The count value reflects the three stages of crack propagation, and the energy
and duration correlation diagram reflects the material energy release mode. The
spectrum diagram of the AE signal indicates that the AE signal in this process is
mostly a burst signal.
3. The AE signal characteristics during the fatigue crack growth of TC4 titanium
alloy provide a basis for applying AE detection technology to the fatigue crack
damage detection and online monitoring.
Acknowledgements This work is financially supported by the Science and Technology Plan Project
of State Administration for Market Regulation (No. 2020MK175), also the Internal Research Project
of China Special Equipment Inspection and Research Institute (No. 2020QingNian02).
References
1. J.P. Zhong, Cracking (Higher education press, Beijing, 2014)
2. Z. Changwen, Ye. Hui, Li. Qiang, Acoustic emission characteristics of Q345 steel specimens
with different defects. Petro-Chem. Equip. 000(004), 5–9 (2013)
3. D. Soulioti, N.M. Barkoula, A. Paipetis et al., Acoustic emission behavior of steel fibre
reinforced concrete under bending. Constr. Build. Mater. 23(12), 3532–3536 (2009)
4. Z. Yihui, Z. Wenbin, X. Feiyun, Acoustic emission characteristics of Q235B steel plate tensile
damage test. Vibr. Shock 34(15), 156–161 (2015)
W. Zhang et al.
instability expansion. At this stage, the specimen breaks rapidly, the material releases
a large number of AE signals, and the count value increases significantly, which is
consistent with the trend of Fig. 19.6. In addition, some studies have pointed out that if
materials with different properties are subjected to different heat treatment processes,
the acoustic emission source in the crack propagation stage will be inconsistent [19–
21]. To explore the AE source in each stage of this process, further research is required
Research to further determine the relationship between the AE signal and the fatigue
crack growth mechanism of different heat treatment processes and materials with
different properties.
19.4 Conclusion
1. The acoustic emission process of fatigue crack growth of TC4 titanium alloy
can be divided into three distinct stages, corresponding to the initiation zone,
steady-state extension zone and unstable fracture zone of fatigue crack. In the
crack initiation stage, the AE signal exhibits higher activity, and the amplitude of
the AE signal in the stable expansion stage decreases. It is presumed that due to
the increase in the dislocation density and the difficulty of dislocation movement,
the material in the crack instability expansion stage quickly breaks, and the AE
signal amplitude Significantly increased.
2. The count value reflects the three stages of crack propagation, and the energy
and duration correlation diagram reflects the material energy release mode. The
spectrum diagram of the AE signal indicates that the AE signal in this process is
mostly a burst signal.
3. The AE signal characteristics during the fatigue crack growth of TC4 titanium
alloy provide a basis for applying AE detection technology to the fatigue crack
damage detection and online monitoring.
Acknowledgements This work is financially supported by the Science and Technology Plan Project
of State Administration for Market Regulation (No. 2020MK175), also the Internal Research Project
of China Special Equipment Inspection and Research Institute (No. 2020QingNian02).
References
1. J.P. Zhong, Cracking (Higher education press, Beijing, 2014)
2. Z. Changwen, Ye. Hui, Li. Qiang, Acoustic emission characteristics of Q345 steel specimens
with different defects. Petro-Chem. Equip. 000(004), 5–9 (2013)
3. D. Soulioti, N.M. Barkoula, A. Paipetis et al., Acoustic emission behavior of steel fibre
reinforced concrete under bending. Constr. Build. Mater. 23(12), 3532–3536 (2009)
4. Z. Yihui, Z. Wenbin, X. Feiyun, Acoustic emission characteristics of Q235B steel plate tensile
damage test. Vibr. Shock 34(15), 156–161 (2015)