High Temperature Fatigue Crack Growth Tests for Mod.9Cr-1Mo Compact Tension Specimen at 20 Hz Loading Frequency

Mod.9Cr-1Mo steel (G91) is currently the favored structural material for several high temperature components of a Sodium-cooled Fast Reactor and it became a registered material for ASME Section III, Subsection NH in 2004. It was chosen as a candidate material as IHTS piping and heat exchangers for a KALIMER-600. While ASME Subsection NH provides some material properties of Mod.9Cr-1Mo steel for a design purpose at high temperature conditions, there is lack of material properties such as fatigue crack growth and creep crack growth especially for robust structural integrity evaluations. The creep-fatigue crack initiation and growth tests for a G91 tubular specimen including a machined defect have been performed by Kim and it was attempted to assess a high temperature crack behavior of Mod.9Cr-1Mo side plate specimen by Lee. The fatigue crack growth tests for Mod.9Cr-1Mo compact tension (CT) specimen were performed by Kim at some test conditions and further tests have been conducted at different test conditions in this study