Austenitic-ferritic transition joint cracking under thermal fatigue loading

Abstract

The use of transition joints is connected with problems caused owing to differences between austenitic-ferritic thermal expansion coefficient, moderate oxidation resistance of the low-alloy ferritic steel, metallurgical deterioration caused by elevated temperature service, and decarburization. Additional factors that come out of pure operational conditions and stochastic parameters deteriorate the problem, which in some cases results in crack formation. The problem can be enhanced when crystallographic transitions occur at high temperatures. The focus of this paper is the study of failure in austenitic-ferritic transition joints in connection with simultaneous cell transition when the ferritic material temperature goes beyond the critical eutectoid temperature of the respective ferritic steel.