Limin SHEN
,
Jianming GONG
,
Yong JIANG
,
Luyang GENG
金属学报(英文版)
HP40Nb steel, used as a candidate material for ethylene cracking furnace tube, suffers creep and carburization damage from the complex environment of high temperature, high carbon potential and low oxygen partial pressure, and they lead to failure of the furnace tubes ahead of designed life. In order to investigate damage evolution under the complex condition, coupled creep damage and carburization damage constitutive equations were developed according to continuum damage mechanics theory. Based on the finite element ABAQUS code, user subroutines were developed for analyzing damage evolution of ethylene furnace tube under the action of coupled creep-carburization. The results show that carburization accelerates the damage process dramatically, damage value reaches the critical value along the inner surface after serving for 75,000 h under the action of creep-carburization, meanwhile the damage value is only 0.53 along the outer surface after operating the same time under the action of creep alone, which means that microcracks are generated along the inner surface under the action of coupled creep-carburization, fracture begins along the outer surface of tube under the action of creep alone.
关键词:
Damage prediction
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Xiancheng ZHANG
,
Jianming GONG
,
Sh
,
ong TU
材料科学技术（英文）
The thermomechanical behavior and the distribution of residual stresses due to thermal spraying of NiCoCrAlY coating were studied by thermomechanical finite element analysis. The effects of phase transformation due to solidifying process of coating particles, thickness and material properties of coating on the residual stresses were discussed. Results showed that residual stress decreases little with the stress relaxation due to the phase transformation. For the substrates with the same thickness, the residual stress increases with the increase in coating thickness. The state of
residual stresses relates to the material properties of coating and substrate closely. The stress-induced failure model of coating is also discussed.
关键词:
Coating
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