Charpy impact properties of 9CrODS ferritic steels

The toughness of 9CrODS steels was evaluated by using an instrumented Charpy impact test machine, focusing on various processes such as hot-forging and hot-rolling. The upper-shelf energy (USE) of the hot-forged specimens is superior; their full-size USE converted from the miniaturized specimen lies within the published data for ODS steels, whereas hot-rolling leads to poor toughness. The total absorbed energy was separated into the energies for crack initiation and propagation. The hot-forged 9CrODS steels provide similar crack initiation energy to ferritic/martensitic steels (FMSs); their low absorbed energy is attributed to a limited amount of crack propagation energy induced by plastic deformation.