Failure Analysis of Gas Collection Tubes Cracking in Hydrogen Production Reformer
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By means of OM, SEM and EPMA and grain size assessment, the cracking failure of gas collection tubes of hydrogen production reformer was investigated based on the process. In this paper, the damage characteristics of Incoloy 800H alloy under high temperature oxidation and the failure mechanism of cracking are explained. The microstructure characteristics of Incoloy 800H after servicing are analyzed. The general relationship theory between element segregation and material cracking is also analyzed. The results show that internal oxidation preferentially along grain boundaries and element segregation took place in the inner wall of Incoloy 800 H at high temperature, where the alloy might experience an evolution of reaction process such as internal oxidation, followed by carbide decomposition and then by carbide segregation, as a result, the precipitation strengthening effect was weakened and the grains were coarsened. During the whole process, the carbon content decreased, the high temperature creep resistance of grain boundary in melt zone decreased gradually, and the overall composite stress led to the initiation and propagation of cracking in Incoloy 800H alloy.
Hydrogen production reformer, Incoloy 800h alloy material, Microstructure, Element segregation, Cracking