n Sohrabi - Graduate student at school of metallurgy and materials science
s.f Kashani Bozorg - Associate professor at school of metallurgy and materials science, College of Engineering, University of Tehran, Tehran, Iran
m Sadeghi - Welding Engineer

In present study repair welding was accomplished on heat-resistant cast steel tube IN-519 which was utilized in hydrogen reformer furnace at 871 ◦C for 80000 hours. Gas tungsten arc welding (GTAW) was performed for repairing. Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffractometry (XRD) were carried out to study microstructure of the aged specimen. Heat affected zone (HAZ) of specimen selected from radiation zone (the place where torch’s flame are directly in contact with the tube, RZ) had cracks after welding and it is not desirable. In order to prevent cracking in repair welding of brittle zone, buttering was investigated. Buttering with Inconel 82 as filler could almost prevent cracking but it couldn’t be completely effective because of the result in bending test. Mechanical tests were performed in order to investigate the repair quality.

Heat resistant steel, buttering, elevated temperature