TITANIUM ALLOY TURBINE BLADE
It is an objective of the present invention to provide an effective use of the friction stir processing (FSP) technology for Ti-alloy turbine blades with a long radial length, and provide a Ti-alloy turbine blade having both high erosion resistance and high long term reliability. There is provided a turbine blade made of an α-β titanium alloy having an average Vickers hardness of 320 Hv or less, the turbine blade having a leading edge, in which: the turbine blade includes, at the leading edge thereof, a first hardened surface region having a thickness of from 0.5 to 3.0 mm and having an average Vickers hardness of 340 Hv or more; and the first hardened surface region is formed by friction stir processing a surface region of the leading edge of the turbine blade.
1 . A turbine blade made of an α-β titanium alloy having an average Vickers hardness of 320 Hv or less, the turbine blade having a leading edge, the turbine blade including, at the leading edge thereof, a first hardened surface region having a thickness of from 0.5 to 3.0 mm and having an average Vickers hardness of 340 Hv or more, the first hardened surface region being formed by friction stir processing a surface region of the leading edge of the turbine blade.
2 . The turbine blade according to claim 1 , wherein
the turbine blade further includes, at the leading edge thereof, a second hardened surface region having an average Vickers hardness higher than that of the α-β titanium alloy,
the second hardened surface region is formed by the steps of:
removing a surface portion of a part of the first hardened surface region;
inserting a Ti alloy patch plate having an average Vickers hardness higher than that of the α-β titanium alloy into the remaining space left by the removal step; and
bonding by friction surface welding.
3 . The turbine blade according to claim 2 , wherein the second hardened surface region includes a third hardened surface region, the third hardened surface region being formed by friction stir processing a surface region of the second hardened surface region.
4 . The turbine blade according to claim 3 , wherein the third hardened surface region has an average Vickers hardness of 440 Hv or more.
5 . A turbine blade made of an α-β titanium alloy having an average Vickers hardness of 320 Hv or less, the turbine blade having a leading edge, the turbine blade including, at the leading edge thereof, a second hardened surface region having an average Vickers hardness higher than that of the α-β titanium alloy, the second hardened surface region being formed by the steps of:
removing a surface portion of a part of the leading edge of the turbine blade;
inserting a Ti alloy patch plate having an average Vickers hardness higher than that of the α-β titanium alloy into the remaining space left by the removal step; and
bonding by friction surface welding.
6 . The turbine blade according to claim 5 , wherein the second hardened surface region includes a third hardened surface region, the third hardened surface region being formed by friction stir processing a surface region of the second hardened surface region.
7 . The turbine blade according to claim 6 , wherein the third hardened surface region has an average Vickers hardness of 440 Hv or more.