Influence of Notch Sharpness on the Stress-Rupture Characteristics of Three Heat-Resisting Alloys with Varying Degree of Precipitation Hardenability, 17 Cr-13 Ni-3 W, LCN-155, A-286

Abstract

Influence of notch on the rupture strength in Creep Rupture Test (conducted so as to finish in around 1000 hours) of three heat resisting alloys with varying degrees of precipitation hardenability, 17 Cr-13 Ni-3W, LCN-155, A-286, either currently in use or expected to be used for parts of turbines or jet engines, was investigated.
Three different kinds of heat treatments were selected, which were: normal solution treatment, normal aging subseqent to the normal solution treatment, and aging at a temperature 100°C above the normal aging temperature subseqent to the normal solution treatment. In the meantime, three different shapes were chosen for specimen, which were: plain, or unnotched, V-notched (60°) with a tip radius of 1.25mm, and V-notched (60°) with a tip radius of 0.06mm.
The results show that the notch sensitivity is highly influenced by the mode of age hardenability of the material which, in turn, is greatly influenced by the stress concentration, and that it is important to stabilize the structure prior to actual service.