An improved life prediction strategy at elevated temperature based on pure creep and fatigue data: Classical strain controlled and hybrid stress-strain controlled creep-fatigue test

Creep-fatigue (CF) interaction is an important issue for designing the next generation power plants. Thus, strain-controlled CF tests (SCCFTs) and hybrid stress-strain controlled CF tests (HCCFTs) of 9Cr3Co3W1CuVNbB steel were conducted. The cyclic responses and creep behaviors in SCCFTs and HCCFTs were investigated. In addition, an improved CF life prediction method was proposed, and only pure creep and fatigue data were needed. Then, the relaxed stress in SCCFTs and the accumulated creep strain in HCCFTs were predicted. Moreover, the oxidation damage was incorporated into the non-linear interactions. The optimally predictive results of the studied material, Grade 91 steel, and 304 stainless steel were in & PLUSMN;3 error band with strain energy density exhaustion model.