Acoustic damping characterization and microstructure evolution during creep of a martensitic stainless steel

Abstract

Creep-induced microstructural evolution of a martensitic stainless steel, JIS-SUS403, subjected to tensile creep at 873 K, was studied by monitoring the shear-wave attenuation and the velocity using electromagnetic acoustic resonance (EMAR). Taken into account was the observation that the contact-less transduction based on the magnetostrictive effect was the key establishing monitoring of microstructural change in the bulk. The attenuation coefficient shows a peak at around 20% and a minimum value at 50% of the creep life, being independent of the applied stress. This novel phenomenon is interpreted as resulting from microstructure changes, especially, dislocations' recovery, which is supported by TEM observations for dislocation structure. Thus, it was possible to use this EMAR assessment method to assess the progress of damage in metals and predict their remaining creep life. ©2007 The Society of Materials Science.