Improved Creep Property of Super304H Steel with Minute Amounts of TiC/TiB₂ Nano-Particles at 600 °C and 330 MPa

Super304H steel, imbued with trace amounts of TiC/TiB₂ nano-particles, was fabricated to assess the influence of nano-particles on its creep properties under the condition of 600 °C/330 MPa. Our findings elucidate that the inclusion of trace TiC/TiB₂ led to a 21% improvement in the creep life of Super304H steel, while diminishing the creep rate from 6.6 × 10⁻⁵ h⁻¹ to 5.7 × 10⁻⁵ h⁻¹. The synergistic precipitation strengthening of the nano-scale Cu-rich phases, needle-like M₂₃C₆ phases, and NbN phases was primarily responsible for this exceptional creep resistance. During the long-term creep process, the nano-scale Cu-rich phase was very stable with little change. In the Super304H steel, M₂₃C₆ and NbN phases had a non-coherent interface and an orientation relationship of \({\left[001\right]}_{\text{NbN}}\) ${\left[001\right]}_{\text{NbN}}$ // \({\left[001\right]}_{{\text{M}}_{23}{\text{C}}_{6}}\) ${\left[001\right]}_{{\text{M}}_{23}{\text{C}}_6}$ . M₂₃C₆ and NbN phases in the Super304H steel incorporating minute TiC/TiB₂ nano-particles also had a non-coherent interface but a \({\left[\stackrel{-}{1}10\right]}_{\text{NbN}}\) ${\left[\stackrel{-}{1},10\right]}_{\text{NbN}}$ // \({\left[\stackrel{-}{2}33\right]}_{{\text{M}}_{23}{\text{C}}_{6}}\) ${\left[\stackrel{-}{2},33\right]}_{{\text{M}}_{23}{\text{C}}_6}$ orientation relationship. The M₂₃C₆ and NbN phases effectively impede the dislocation movement and were shown to increase the creep strength considerably.