Creep-fatigue interaction behaviour of a 15Cr-15Ni, Ti modified austenitic stainless steel as a function of Ti/C ratio and microstructure

The creep-fatigue interaction behaviour of a 15Cr-15Ni, Ti modified austenitic stainless steel has been characterized as a function of Ti/C ratio and microstructure. Creep-fatigue interaction behaviour has been investigated in this material, by introducing hold times with durations ranging from 1 to 10 min at peak tensile strain. The material was tested at 923 K in Ti/C ratios of 4 and 8 and in the solution annealed, cold worked and aged conditions. It has been ascertained that precipitation controls creep-fatigue interaction properties in this alloy. Carbides which precipitate on the grain boundaries in the solution annealed material are found to be beneficial to creep-fatigue interaction properties, while fine titanium carbides which precipitate in the matrix in cold worked and aged conditions of the alloy, have been found detrimental to creep-fatigue interaction properties.