Elevated Temperature Low-Cycle Fatigue Strength of Butt Welded AISI 316 Steel Pipes

Abstract

This paper reviews the experimental activities that were performed in recent years at the Department of Mechanical and Nuclear Engineering (DCMN) of the University of Pisa, mainly during research programs sponsored by the Italian Committee for Nuclear Energy (ENEA), in the field of life assessment under high temperature low-cycle fatigue and creep-fatigue conditions in AISI 316 weldments. These activities comprised tests on tubular, welded model structures of AISI 316, carried out in air, under either uniaxial or biaxial loading conditions, at 550°C and 650°C. Small smooth specimen testing was also performed mainly for characterizing the stress-strain behavior of the weldments. Extensive post-test analysis was focused on correlating the experimental results with life predictions based on commonly used or recently proposed design rules. Some of the main results have already been published but a complete report has not yet been delivered to the international literature. This paper is therefore aimed at giving a fairly complete picture of both the experimental results and the life prediction work.