Abstract:
Abstract. Studies performed earlier show that the thermal shock loading has influence, together
with the normal service loadings, in the fatigue life of some critical welded joints present in the
exhaust systems of naval gas turbines [1-2]. In order to prevent the fatigue crack propagation that
was verified in service [3], a recently developed ultrahigh-strength austenitic stainless steel was
selected (Cr-Mn steel - number 1.4376) and its mechanical properties and the fatigue resistance are
under study. This new material could replace, locally, the current material used in the main structure
of the exhaust system (AISI 316L). Experimental data are shown. The temperature measured at the
critical locations was about 350ºC and the pressure applied in the system was calculated through a
Computational Fluid Dynamics simulation (CFD), whose results are presented in the paper. The
stresses induced by the loadings will be important to estimate the lifetime from the fatigue
resistance tests (S-N curves) that will be performed, at 350ºC, in butt and T-welded joints of AISI
316L stainless steel with Cr-Mn austenitic stainless steel.