Hongyuan FANG
,
Chenglei FAN
,
Jianguo YANG
,
Ming LI
,
Zhen LUO
,
Xianzhong HOU
材料科学技术（英文）
A new type of compound conduit is designed and the finite element method (FEM) is applied to analyze the mechanical performance of a typical compound conduit. The results of the numerical simulation confirm that the distributions of the strain, stress and the flexure distortion of the conduit are reasonable under the working conditions, and the stress and strain are continuous at the interface of the crust and the pipe liner. The conduit can endure 7.4 times of the working load before break, which fits well with that of the experiment and means that the conduit has good ability to bear overload. The peak value of the flexure distortion of the conduit (6 m) is about 3 mm in the middle bottom of the pipeline, which also accords well with that of the experiment.
关键词:
Compound conduit
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null
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null
,
null
Liang ZHANG
,
Xuesong LIU
,
Linsen WANG
,
Ping WANG
,
Hongyuan FANG
金属学报(英文版)
To investigate fatigue crack initiation characteristics of Al-Zn-Mg alloy welded joint, notched specimens were used in fatigue test for the base metal, welding bead and heat affected zone (HAZ). The fatigue fracture surface near the fatigue crack initiation site was observed by scanning electron microscope (SEM). The results show that the differences of fatigue crack initiation life among base metal, welding bead and HAZ are not obvious. Inhomogeneity in microstructure and mechanical performance of HAZ influences the fatigue crack initiation life. The ratio of fatigue crack initiation life (Ni) to fatigue failure life (N f)Al-Zn-Mg alloy|Welded joint|Fatigue crack initiation|Life prediction for the base metal, welding bead and HAZ of A7N01 aluminium alloy welded joint are 26.32%, 40.21% and 60.67%, respectively. Fatigue crack initiation life can be predicted using a uniform model. Observation of fatigue fracture surfaces shows that for the welding bead a fatigue crack initiates from the smooth surface due to the welding process, the blowhole in HAZ causes fatigue crack and the crushed second phase particles play an important role in fatigue crack initiation for the base metal.
关键词:
Al-Zn-Mg alloy
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null
,
null
,
null
Hongyuan FANG
,
Jianguo YANG
,
xiuyu YU
材料科学技术（英文）
Microstructure and interface reactions of Al2O3 joints brazed by Cu-Zn-Ti alloy were studied by using SEM, EDS and XRD. The effects of brazing temperature and Ti content on interfacial reactions and microstructure were investigated, and the action of adding Zn into brazing alloy was also studied. TiO, Ti3Al and CuTi were formed at the interface of ceramics and the filler metal, while CuTi, Cu3Ti and alpha -Cu were found in the brazing. The thickness of the reaction layer increased with increasing of brazing temperature, under the same brazing process, the thickness increased with the Ti content.
关键词:
Hongyuan FANG
,
Li WANG
,
Yiyu QIAN
材料科学技术（英文）
Fatigue crack propagation life of ball grid array (BGA) soldered joints during thermal cycling loading was investigated by fracture mechanics approach using finite element analysis. The relationships between the strain energy release rate (G) acid crack size (a), thermal cycle numbers (N) can be derived. Based on the relationships, fatigue life of the soldered joints was determined. The results showed that crack propagation life was higher than crack initiation life. Therefore, it appears that it is more appropriate to predict the fatigue life of soldered joints using the fracture mechanics method.
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