HR3Calloy was treated with aging treatment and long-term aging at 650 ℃for 500 hto analyze influence of aging treatment on the microstructure and impact toughness.The results reveal that a few large bulky NbCrN phase an be observed with precipitation of a little tiny Z-phase particles at innergrain after aging treatment.More Z-phase is precipiated in alloy with aging treatment after long-term aging at 650 ℃ for 500 h

which improves the microhardness by dispersedly strengthening effects.Meanwhile

M

23

C

6

type carbides are coarsened along the grain boundaries

while some M

23

C

6

particles are distributed randomly inside the austenitic grain.The impact toughness values of HR3 Calloy with solid solution treatment or aging treatment are decreased after long-term aging

and the fracture morphologies of the notched impact specimens are characterized by intergranular fracture mode.