TRANSITION-METAL JOINTS FOR STEAM-GENERATORS - AN OVERVIEW

Citation
Ak. Bhaduri et al., TRANSITION-METAL JOINTS FOR STEAM-GENERATORS - AN OVERVIEW, International journal of pressure vessels and piping, 58(3), 1994, pp. 251-265
Citations number
NO
Categorie Soggetti
Engineering
ISSN journal
03080161
Volume
58
Issue
3
Year of publication
1994
Pages
251 - 265
Database
ISI
SICI code
0308-0161(1994)58:3<251:TJFS-A>2.0.ZU;2-1
Abstract
The transition metal joint (TMJ) between an austenitic stainless steel and a chromium-molybdenum (Cr-Mo) ferritic steel used widely in steam generators of power plants has for a long time presented problems rel ating to premature failures in service. The direct (bimetallic) TMJ pr esently in use is designed for a service life of about 200,000 h; but such TMJs with iron-base weld metals have been failing in service with in about one-third of their design lifetime, while their counterparts with nickel-base weld metals fail within about one-half of their desig n lifetime. The causes for such premature service failures of these TM Js are discussed in detail, leading to the development of improved TMJ s. One of the improved TMJs with a trimetallic configuration of austen itic stainless steel/Alloy 800/Cr-Mo ferritic steel is discussed in de tail, covering its development, characterisation and evaluation. Accel erated performance tests in the laboratory have indicated a four-fold improvement in the service life of the TMJ with this trimetallic confi guration compared to the bimetallic configuration. The metallurgical d etails of these studies are also discussed in this paper.