Effects of Inner Defects on Creep Damage and Crack Initiation for a Brazed Joint

2018 ◽  
Vol 37 (9-10) ◽  
pp. 863-872 ◽  
Author(s):  
Yun Luo ◽  
Chuanlong Wang ◽  
Wenchun Jiang ◽  
Yu Wan ◽  
Weiya Zhang ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Filler Metal ◽  
Damage Model ◽  
Creep Damage ◽  
Area Ratio ◽  
Creep Crack ◽  
Metal Thickness ◽  
Incomplete Filling ◽  
Defect Area ◽  
Brazed Joint

AbstractIn the brazing process, some brazing defects like semicircular or straight type are generated due to incomplete filling. In this paper, the creep damage and creep crack initiation (CCI) time of Hastelloy C276-BNi2 brazed joint with defects are investigated by a ductility exhaustion damage model. The effects of defect dimension and filler metal thickness are also discussed. The results show that the different defects have different creep damage distributions and CCI times. The maximum creep damage is located at the defect frontier due to the larger stress concentration. With the increase of semicircular defect radius and straight defect length, the CCI time decreases. The creep fracture is inclined to generate in semicircular defect for the smaller defect area ratio, while it is easy to generate in straight defect for the bigger defect area ratio. As the filler metal thickness increases, the CCI time increases. For the thicker filler metal, the creep crack is easy to initiate in semicircular defect.

Numerical Investigation on Creep Crack Growth of Brazed Joint Using Different Damage Models

2016 ◽  
Vol 853 ◽  
pp. 231-235
Author(s):  
Yun Luo ◽  
Qian Zhang ◽  
Wen Chun Jiang
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Rupture Life ◽  
Damage Model ◽  
Creep Crack Growth ◽  
Creep Damage ◽  
Initiation Time ◽  
Creep Crack ◽  
Damage Models ◽  
Brazed Joint

In this paper, four types of creep damage models (Kachanov-Robotnov, Liu-Murakami, Cocks-Ashby and Wen-Tu model) were used to study the creep crack growth (CCG) behavior in compact tension (CT) specimen of Hastelloy C-276/BNi-2 brazed joint. The results show that the creep damage model has a great influence on the CCG behavior of brazed joint. The crack-tip stress states, da/dt-C* curves, crack initiation time and rupture life are different for the different damage models. The Kachanov-Rabotnov model can lead to higher CCG rate and shorter rupture life, while the Cocks and Ashby model can reduce CCG rate and prolong the rupture life. The model order in terms of the CCG rate from high to low is K-R, L-M, W-T, C-A model, which is opposite order of crack initiation time. In the simulation of CCG of brazed joint, a precious damage model should be employed for life prediction.

Creep damage and crack initiation in P92–BNi2 brazed joint

2015 ◽  
Vol 72 ◽  
pp. 63-71 ◽  
Author(s):  
Wenchun Jiang ◽  
Weiya Zhang ◽  
Guodong Zhang ◽  
Yun Luo ◽  
Y.C. Zhang ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Creep Damage ◽  
Brazed Joint

scholarly journals Finite element simulation of creep crack growth using combined plastic-creep damage model

2016 ◽  
Vol 2 ◽  
pp. 825-831 ◽  
Author(s):  
Dong-Jun Kim ◽  
Kyung-Dong Bae ◽  
Han-Sang Lee ◽  
Yun-Jae Kim ◽  
Goon-Cherl Park
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Crack Growth ◽  
Damage Model ◽  
Creep Crack Growth ◽  
Creep Damage ◽  
Creep Crack ◽  
Element Simulation ◽  
Creep Damage Model ◽  
Plastic Creep

Creep crack growth behavior analysis of the 9Cr-1Mo steel by a modified creep-damage model

2017 ◽  
Vol 708 ◽  
pp. 68-76 ◽  
Author(s):  
Yu-Cai Zhang ◽  
Wenchun Jiang ◽  
Shan-Tung Tu ◽  
Xian-Cheng Zhang ◽  
You-Jun Ye
Keyword(s):  
Behavior Analysis ◽  
Crack Growth ◽  
Damage Model ◽  
Creep Crack Growth ◽  
Creep Damage ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Creep Crack ◽  
Creep Damage Model

Prediction of Creep Crack Growth for Modified 9Cr-1Mo at 600°C

2012 ◽  
Author(s):  
Nak Hyun Kim ◽  
Yun Jae Kim ◽  
Woo Gon Kim ◽  
Hyeong Yeon Lee
Keyword(s):  
Prediction Model ◽  
Crack Growth ◽  
Damage Model ◽  
Creep Crack Growth ◽  
Creep Damage ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Element Analysis ◽  
Creep Ductility ◽  
Creep Crack

This paper introduce theoretical creep crack growth prediction model and provides experimental validation of the approach for simulating creep crack growth using finite element analysis method, recently proposed by the authors. The FE creep damage model is based on the creep ductility exhaustion concept, and incremental damage is defined by the ratio of incremental creep strain and multi-axial creep ductility. A simple linear damage summation rule is applied. When accumulated damage becomes unity, element stresses are reduced to zero to simulate progressive crack growth. For validation, simulated results are compared with experimental data for a compact tension specimen of modified 9Cr-1Mo at 600°C under various loading levels. The simulated results agree well with experimental C*-da/dt data. The test data are also compared with theoretical CCG prediction model.

Analysis of Creep Crack Growth Behavior of the Brazed Joint Using Continuum Damage Mechanics Approach

2018 ◽  
Author(s):  
Yu-Cai Zhang ◽  
Wenchun Jiang ◽  
Shan-Tung Tu ◽  
Xian-Cheng Zhang ◽  
Guo-Yan Zhou
Keyword(s):  
Crack Initiation ◽  
Diffusion Zone ◽  
Damage Mechanics ◽  
Creep Crack Growth ◽  
Continuum Damage Mechanics ◽  
Crack Growth Behavior ◽  
Continuum Damage ◽  
Initiation Time ◽  
Creep Crack ◽  
Brazed Joint

Creep crack growth behavior of the Inconel625/BNi-2 brazed joint considering the diffusion zone at 650 °C was investigated by a continuum damage mechanics approach based on the finite element method. The results show that creep crack nucleate and develop at the region of the brazing filler metal. The crack initiates at about 0.2 mm ahead of the crack tip. When the load is 1000 N, the crack initiation time of the CT specimen is 1664 hour. While when the load is 1135 N, the crack initiation time is only about 891 hour. The simulated results correspond well with the experimental data, presenting that the used finite element method can accurately simulate the creep damage behavior of the brazed joint. When the mechanical properties of the diffusion zone are not considered, the crack initiation time and fracture time decrease significantly compared to the result with properties of the diffusion zone included, indicating that the result from the conventional simulating method without considering the diffusion zone is quite conservative compared to the experimental life of the component.

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