MarBN steels, originally developed by Professor Fujio Abe at NIMS Japan, have undergone significant advancement in the UK through a series of government-funded collaborative projects (IMPACT, IMPEL, INMAP, IMPULSE, and IMPLANT). These initiatives have achieved several major milestones, including operational power plant trials, full-scale extruded pipe production, matching welding consumable development, and most notably, the creation of IBN-1—a new steel demonstrating 30-45% higher creep strength than Grade 92. However, like other creep strength-enhanced ferritic steels, IBN-1 shows reduced creep ductility under the lower stress conditions typical of operational use. Since adequate creep ductility is essential for component damage tolerance and effective in-service monitoring, this study investigates the effects of an alternative normalizing and tempering heat treatment on cast IBN-1. The research presents creep rupture test results showing improved ductility and analyzes the microstructural mechanisms responsible for this enhancement.