Maraging steel sheet and manufacturing method thereof excellent in fatigue characteristics

摘要

[Summary] [challenge] I provide excellent maraging steel and manufacturing method thereof fatigue characteristics. A chemical components in weight%, C:% 0.01 or less, Ni: 8~19%, Co: 8~20%, Mo: 2~ 9%, Ti: 0.1~2%, Al: 0.15% or less, N: 0.003% or less, O: containing 0.0015% or less consists of the balance substantially Fe, the size of the nonmetallic inclusions 3 0μm is as follows. Above maraging steel, taper Tp = (D1-D2) × 100 / H is 5.0 to 25. 0%, high-diameter ratio Rh = H / D is 1.0 to 3.0, flatness ratio B = W1 / W2 is cast using a mold of 1.5 or less, Are readily prepared by applying the plastic working to the cast piece. The above maraging steel is, by making the Ti component segregation ratio and the Mo component segregation ratio each 1.3 or less, can further improve the fatigue strength.