12Cr Alloy steel for a turbine rotor

Abstract

A turbine rotor material, that has sufficient corrosion resistance and stress corrosion cracking resistance and appropriate strength and toughness in a good balance, and a manufacturing method thereof are provided. The turbine rotor material is a 12Cr alloy steel that contains: C of 0.01 to 0.10%, Si of 0.01 to 0.50%, Mn of 0.1 to 1.0%, Cr of 9 to 13%, Ni of 2 to 7%, Mo of 0.3 to 3%, N of 0.01 to 0.10%, all in weight percent, and remains of Fe and incidental impurities.

What is claimed is:  
     
         1 . A 12Cr alloy steel for a turbine rotor, containing: C of 0.01 to 0.10%, Si of 0.01 to 0.50%, Mn of 0.1 to 1.0%, Cr of 9 to 13%, Ni of 2 to 7%, Mo of 0.3 to 3%, N of 0.01 to 0.10%, all in weight percent, and remains of Fe and incidental impurities.  
     
     
         2 . A 12Cr alloy steel for a turbine rotor as claimed in  claim 1 , further containing any one or more of rare earth elements of 0.003 to 0.03%, Ca of 0.001 to 0.009% and B of 0.0005 to 0.005%, all in weight percent.  
     
     
         3 . A 12Cr alloy steel for a turbine rotor as claimed in  claim 1  or  2 , wherein a quantity of impurity elements of said incidental impurities is controlled so as to contain: P of 0.0012% or less, S of 0.005% or less, Al of 0.015% or less, As of 0.008% or less, Sn of 0.008% of less and Sb of 0.005% or less, all in weight percent.  
     
     
         4 . A 12Cr alloy steel for a turbine rotor as claimed in  claim 1  or  2 , wherein a Cr equivalent weight shown by “[Cr %]+2[Si %]+1.5[Mo %]−2[Ni %]−[Mn %]−15[C %+N %]” is −2.0 or more and +8.0 or less.  
     
     
         5 . A 12Cr alloy steel for a turbine rotor as claimed in  claim 3 , wherein a Cr equivalent weight shown by “[Cr %]+2[Si %]+1.5[Mo %]−2[Ni %][Mn %]−15[C %+N %]” is −2.0 or more and +8.0 or less.  
     
     
         6 . A manufacturing method of a 12Cr alloy steel for a turbine rotor as mentioned in  claim 1  or  2 , wherein, in a manufacturing process of said alloy steel, there is carried out neither an adjustment of chemical components in a solidifying process of molten metal when said molten metal, adjusted to predetermined chemical components, is cast in a mold for making a steel ingot nor a re-smelting treatment of said steel ingot once solidified.  
     
     
         7 . A manufacturing method of a 12Cr alloy steel for a turbine rotor as mentioned in  claim 3 , wherein, in a manufacturing process of said alloy steel, there is carried out neither an adjustment of chemical components in a solidifying process of molten metal when said molten metal, adjusted to predetermined chemical components, is cast in a mold for making a steel ingot nor a re-smelting treatment of said steel ingot once solidified.  
     
     
         8 . A manufacturing method of a 12Cr alloy steel for a turbine rotor as mentioned in  claim 4 , wherein, in a manufacturing process of said alloy steel, there is carried out neither an adjustment of chemical components in a solidifying process of molten metal when said molten metal, adjusted to predetermined chemical components, is cast in a mold for making a steel ingot nor a re-smelting treatment of said steel ingot once solidified.  
     
     
         9 . A manufacturing method of a 12Cr alloy steel for a turbine rotor as mentioned in  claim 1  or  2 , wherein, in a heat treatment process of said alloy steel, there are carried out tempering treatments two times or more in a temperature range of 500 to 700° C. after a quenching treatment.  
     
     
         10 . A manufacturing method of a 12Cr alloy steel for a turbine rotor as mentioned in  claim 3 , wherein, in a heat treatment process of said alloy steel, there are carried out tempering treatments two times or more in a temperature range of 500 to 700° C. after a quenching treatment.  
     
     
         11 . A manufacturing method of a 12Cr alloy steel for a turbine rotor as mentioned in  claim 4 , wherein, in a heat treatment process of said alloy steel, there are carried out tempering treatments two times or more in a temperature range of 500 to 700° C. after a quenching treatment.  
     
     
         12 . A manufacturing method of a 12Cr alloy steel for a turbine rotor as mentioned in  claim 5 , wherein, in a heat treatment process of said alloy steel, there are carried out tempering treatments two times or more in a temperature range of 500 to 700° C. after a quenching treatment.  
     
     
         13 . A turbine rotor made of an alloy steel mentioned in  claim 1  or  2 .  
     
     
         14 . A turbine rotor made of an alloy steel mentioned in  claim 3 .  
     
     
         15 . A turbine rotor made of an alloy steel mentioned in  claim 4 .  
     
     
         16 . A turbine rotor made of an alloy steel mentioned in  claim 5 .  
     
     
         17 . A turbine rotor made of an alloy steel mentioned in  claim 6.