Quantitative study of W-alloyed 9-12 Cr steel microstructures using EBSD

Ferritic/martensitic steels for use in power generation, such as the modified 9-12 wt% Cr alloy P92, are required to withstand temperatures of 450-600 ◦ C or more for several decades. Under such conditions, one major failure mode is creep fracture, so reliable prediction of the growth lifetime of creep cracks is important. Lifetimes depend on many factors including temperature, specimen geometry and material microstructure. In the present paper, electron backscatter diffraction (EBSD) is used to quantify the microstructural differences between two steel samples that performed very differently in creep crack growth tests despite similar compositions and preparation routes.