Weldability and high temperature performance of welded joints of heat-resisting alloys

• Published in: Welding international Vol. 19; no. 5; pp. 349 - 356
• Main Author: Nishimoto, K
• Format: Journal Article
• Language: English
• Published: Cambridge Taylor & Francis Group 01.05.2005; Abington
• Subjects: Applied sciences; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Metals. Metallurgy; Welding; Temperature; High temperature; Welded joint; Welding; Weldability
• ISSN: 0950-7116; 1754-2138
• DOI: 10.1533/wint.2005.3426

The applications of various heat resisting alloys applications depend upon the service temperature and the environment in which they are employed; austenitic stainless steels are employed mainly in the temperature region of approximately 850-950 K and Fe-base, Co-base and Ni-base superalloys are employed for high-temperature use at more than approximately 950 K. Problems concerning the integrity of weld procedures and high-temperature performance of weld zones should be considered for the application of these heat-resisting alloys to welded structures. In fact, most heat resisting alloys have poor weldability compared with carbon and low-alloy steels and are subject to problems such as cracking during welding. Furthermore, there are many instances of deteriorating high-temperature performance of the weld zone due to changes in the microstructure which accompany welding. On the other hand, heat-resisting alloys are employed in severe high-temperature environments and it is highly possible that there will be an occurrence of fissures and deterioration due to deformation, creep damage, oxidation and carburising. There are many cases where materials which have been in service for extended periods have increased weld crack susceptibility. Repair welding of these requires further attention to be given to the possibility of weld cracks.