Gas turbine and shroud for gas turbine

A gas turbine comprising a turbine stubshaft, a plurality of turbine disks coupled to said shaft by turbine stacking bolts, with spacer interposed therebetween, moving turbine blades planted in each of said disks, a shroud having a sliding surface in a spaced-apart relation to the tips of said moving blades, a distant piece connected to said disks by said bolts, a plurality of compressor disks coupled to said distant piece by compressor stacking bolts, compressor blades planted in each of said compressor disks, and a compressor stubshaft formed integrally with the first stage of said compressor disks, at least said turbine disks being made of martensitic steel having a wholly annealed martensitic structure and having a creep rupture strength of not less than 50 kgf/mm.sup.2 under the conditions of 450.degree. C. and 10.sup.5 and a V-notch Charpy impact strength of not less than 5 kgf-m/cm.sup.2 after having been held at 500.degree. C. for 10.sup.3 hours, said moving blade located at the downstream of combustion gas being made longer in length, said shroud being made of a heat-resistant case alloy having at least columnar grains directed inward from the sliding surface thereof, said heat-resistant cast alloy having a tensile strength of not less than 40 kgf/mm.sup.2 and an elongation of not less 5% both at a room temperature, a tensile strength of not less than 20 kgf/mm.sup.2 and an elongation of not less than 5% both at 760.degree. C., and a creep rupture time of not less than 10 hours under the conditions of 871.degree. C. and 5.5 kgf/mm.sup.2.

A gas turbine comprising a turbine stubshaft, a plurality of turbine disks coupled to said shaft by means of turbine stacking bolts, with spacers interposed therebetween, moving turbine blades planted in each of said disks, a ring-shaped shroud having segments provided with a sliding surface in a spaced-apart relation to the tips of said moving turbine blades, turbine nozzles for guiding high-temperature gas to said blades to rotate the same, a plurality of cylindrical burners for generating said high-temperature gas, a distant piece coupled to said disks by said bolts, a plurality of compressor disks coupled to said distant piece by compressor stacking bolts, compressor blades planted in each of said disks, and a compressor stubshaft formed integrally with said compressor disk located at a first stage, a portion of said shroud which portion faces the turbine blade located at the first stage being made of Ni-base cast alloy having a wholly austenitic structure and comprised by weight of 0.05 to 0.2% C, not more than 2% Si, not more than 2$ Mn, 17 to 27% Cr, not more than 5% Co, 5 to 15% Mo, 10 to 30% Fe, not more than 5% W, not more than 0.02% B, and the balance Ni and incidental impurities, other portion of said shroud which face said turbine blades located at the remaining stages being made of Fe-base cast alloy comprised by weight of 0.3 to 0.6 C, not more than 2% Si, not more than 2% Mn, 20 to 27% Cr, 20 to 30% Ni, 0.1 to 0.5% Nb, 0.1 to 0.5% Ti, and the balance Fe and incidental impurities, and at least a portion of said shroud which portion is in sliding relation to the tips of said blades having columnar grains directed inward from said sliding surface;

• said portion being made of a heat resistant alloy having a tensile strength of not less than 40 kgf/mm.sup.2 and an elongation of not less 5% both at a room temperature, a tensile strength of not less than 20 kgf/mm.sup.2 and an elongation of not less than 5% both at 760.degree. C., and a creep rupture time of not less than 10 hours under the conditions of 871.degree. C. and 5.5 kgf/mm.sup.2.