乙烯裂解炉管焊接接头鼓胀高温寿命研究及失效分析

Life and failure analysis of bulging ethylene pyrolysis furnace tube working in high temperature

在高温服役过程中,炉管及焊接接头等工作部分会出现鼓胀问题。通过蠕变试验和有限元数值模拟技术,对比分析了鼓胀对炉管长期服役寿命的影响,同时通过对炉管的化学成分、金相及抗拉强度进行分析得到其差异的原因。通过对鼓胀和未鼓胀试样进行服役温度下的单轴蠕变试验,得到蠕变曲线,通过数据拟合得到改进K-R本构模型的材料损伤参数;利用有限元方法进行了蠕变损伤分析和寿命预测。2种试样的化学成分分析和拉伸性能分析表明材质不合格为其失效的主要原因之一;利用SEM对组织进行分析,发现炉管在高温下服役会发生渗碳,造成局部温度过高,导致材料的耐高温能力下降造成鼓胀,最终导致材料的失效。

In high temperature service process,the furnace tubes may bulge.The effect of bulge on life of furnace tubes was studied through uniaxial creep test and finite element numerical simulation,meanwhile,the causes of differences were studied from the aspects of chemical composition,metallographic examination,tensile strength analysis.Through of creep test of bulging and non-bulging specimen,the creep curves were got,and the parameters of modified K-R constitutive model were got by fitting to the data.The life and damage were studied by finite element numerical simulation using modified K-R constitutive model.The chemical composition and tensile performance analysis of the two samples were implemented,and the results showed that the unqualified material was one of the main reasons of the failure.The SEM organization analysis showed that the carburizing of furnace tubes would occur in high temperature service,causing that the local temperature was too high,resulting in the bulge and failure of the furnace tubes.