<p>Post-weld normalizing and tempering offer a promising approach to preventing the notorious Type IV premature creep fracture in 9Cr steel weldments. While post-weld normalizing promotes microstructural homogenization, it also induces significant changes in the prior austenite grain (PAG) size in the weldments. Different post-weld normalizing schemes were designed to achieve PAG sizes with order-of-magnitude differences, thereby investigating their influence on creep lifetime. The results indicate that martensites with smaller PAGs transform into fine ferrites during tempering, while those with larger PAGs retain the elongated block structure of tempered martensite even after tempering. During creep, fine ferrites undergo plastic deformation, and creep cavities preferentially nucleate along ferrite grain boundaries, particularly near hard precipitates, leading to salient microcrack formation. In contrast, in tempered martensites with larger PAGs, cavities primarily nucleate and grow along PAG boundaries after creep exposure. Increasing the PAG size not only prevents the formation of fine ferrites but also reduces cavity nucleation sites, thereby prolonging creep life. However, excessively high normalizing temperature can lead to δ-ferrite retention, which degrades impact toughness.</p>