Small punch creep investigation of Eurofer97 and 14Cr oxide dispersion strengthened steel

Abstract

Small punch creep (SPC) testing represents an effective way to rapidly assess the creep performance of novel materials and potentially monitor degradation of in-service components. Recent progress in standardisation has also led to improvements in data analysis. However, estimation of equivalent uniaxial stresses is still somewhat challenging and has hindered wider usage of the small punch technique. In this study, the creep properties of two candidate materials for structural applications in future fusion reactors were assessed via SPC. These included the baseline structural material, Eurofer97, and a more recently developed 14Cr Oxide Dispersion Strengthened (ODS) steel (14YWT). Having been assessed at 550 °C, the 14YWT demonstrated superior creep life and significantly lower rates of deformation, but also exhibited reduced ductility. The Modified Chakrabarty (MCH) approach was employed to estimate equivalent uniaxial creep stresses. This methodology appeared to work well with the Eurofer97 but struggled when applied to 14YWT, making accurate estimation of the 14YWT performance difficult. Since the MCH approach was developed for ductile materials, its predictive capabilities may have been limited by the low ductility of 14YWT.

Keywords

• Small Punch Creep
• Eurofer97
• ODS Steel
• 14YWT
• SSTT