Effect of Carburizing on Microstructure and Weldability of 35Cr-45Ni-Nb Alloys in the Ethylene Heating Furnace

Abstract

This paper presents the effect of carburizing phenomena on the microstructure and weldability of tube coils in the ethylene heating furnace. A tube coil material was used the Ni-base alloy grade 35Cr-45Ni-Nb. The specimens obtained from three different height levels of carburized tube were tested. The results from the SEM-EDS and microstructure analyses show that the carbon was concentrated in carburized tube and deposited in the solid solution and chromium carbide compound. The prediction of new weldability in the carburized tube with Nieq/Creq ratio can be used for welding repair in petrochemical industry.

Evaluation of creep rupture behaviour for weld joint and base metal of the Cr35Ni45Nb alloy

“…As the weldability of the ethylene pyrolysis furnace tubes is deteriorated due to microstructure deterioration [18,19], carburisation and oxidation [20] in the service process, many researchers have studied welding repair parameters of ethylene cracking furnace tubes after a long-term service [21][22][23]. As the weak part of the ethylene pyrolysis furnace tube, the microstructure and mechanical properties of the Cr35Ni45Nb alloy weld joint after service are rarely reported.…”