Variations of the microstructure and mechanical properties of HP40Nb hydrogen reformer tube with time at elevated temperature

Materials & Design, Volume 32, Issue 4, April 2011, Pages 2507-2512

Technical Report

Variations of the microstructure and mechanical properties of HP40Nb hydrogen reformer tube with time at elevated temperature

C.J. Liu (a), Y. Chen (b)

cjliu@ecust.edu.cn

a Key Laboratory of Safety Science of Pressurized System, Ministry of Education, Meilong Road 130, Xuhui District, Shanghai 200237, PR China

b Shanghai Institute of Special Equipment Inspection and Technical Research, Shanghai 200262, PR China

Abstract

Although hydrogen reformer furnaces have been widely used in the petrochemical industry to produce hydrogen-rich gas from a mixture of hydrocarbons and steam at high temperature, degradation of material microstructure was frequently encountered in the tubes due to high temperature service, leading to their premature failure.

This paper attempts to address the variations of the microstructure and mechanical properties of HP40Nb hydrogen reformer tubes after aging treatment and long-term service at temperature of 900 °C.

Results demonstrated coarsening of the grain boundaries due to the precipitation of the chromium-rich carbides and the secondary carbides precipitated in the matrix after aging treatment and long-term service. The mechanical properties of the HP40Nb tube obviously degraded after short-term service and remained nearly unchanged. The interdendritic carbide content can be used as a key index for the life predication of the used tube since there was a linear relationship between the logarithm of carbide content and the logarithm of time.

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