Precipitation hardened martensitic stainless steel, manufacturing method therefor, and turbine moving blade and steam turbine using the same
AssigneeMitsubishi Hitachi Power Systems, Ltd.
InventorsYuichi Hirakawa, Yoshikuni Kadoya, Hiroharu Ooyama, Tatsuya Furukawa, Naoto Tochitani
Life of this patent
Estimating the term…
Abstract
The precipitation hardened martensitic stainless steel is characterized by containing, in percent by weight, 12.25 to 14.25% Cr, 7.5 to 8.5% Ni, 1.0 to 2.5% Mo, 0.05% or less C, 0.2% or less Si, 0.4% or less Mn, 0.03% or less P, 0.005% or less S, 0.008% or less N, 0.90 to 2.25% Al, the balance substantially being Fe, and the total content of Cr and Mo being 14.25 to 16.75%. A turbine moving blade and a steam turbine are manufactured by using this martensitic stainless steel.
Claims13
A precipitation hardened martensitic stainless steel containing, in percent by weight, 12.25% to 14.25% Cr, 7.5% to 8.5% Ni, 1.0% to 2.5% Mo, 0.05% or less C, 0.2% or less Si, 0.4% or less Mn, 0.03% or less P, 0.005% or less S, 0.003% to 0.008% N, 1.36% to 2.25% Al, optionally Nb or Ta, the balance substantially being Fe,
- wherein the total content of Cr and Mo is 14.25% to 16.75%, and the total content of Nb and Ta is up to 0.01%, and
- wherein:
- a Cr equivalent=[Cr]+2[Si]+1.5[Mo]+5.5[Al]+1.75[Nb]+1.5[Ti], and
- a Ni equivalent=[Ni]+30[C]+0.5[Mn]+25[N]+0.3[Cu],
- wherein [Cr], [Si], [Mo], [Al], [Nb], [Ti], [Ni], [C], [N] and [Cu] each represents a content in percent by weight of the recited element, and
- wherein the Cr equivalent is less than 28.0, and the Ni equivalent is less than 10.5.
Dependencies are inferred from the claim text.