TURBINE CASING

Abstract

A casing is formed from an alloy which contains, by mass, 0.08-0.20% C, 0.05-0.45% Si, 0.10-0.30% Mn, 0.80-1.40% Ni, 1.00-1.40% Cr, 1.20-1.60% Mo, 0.10-0.30% V, 0.06-0.10% Ti, 0.0005-0.0010% B, not more than 0.01% P, not more than 0.01% S, and not more than 0.005% Al, the balance being Fe and unavoidable impurity elements. The casing has excellent high-temperature strength, high toughness and excellent weldability, and is applicable to casings used in high-temperature high-pressure steam environments.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the balance between Mn and Ni in alloys shown in an embodiment of the present invention;

FIG. 2 is a diagram showing the balance between high-temperature strength enhancing elements and a toughness enhancing element in the alloys shown in the embodiment;

FIG. 3 is a diagram showing the balance between the content radio of the high-temperature strength enhancing elements to the toughness enhancing element and B in the alloys shown in the embodiment;

FIG. 4 is a structural diagram of a welding SR crack test specimen;

FIG. 5 is a diagram showing the relationship between Ni content and 566° C.×100,000 hr creep rupture strength;

FIG. 6 is a diagram showing the relationship between Ni content and fracture appearance transition temperature (FATT);

FIG. 7 is a structural sectional view of a high pressure steam turbine; and

FIG. 8 is a structural sectional view of a high/intermediate pressure integrated type steam turbine.

Claims

1. A casing formed from an alloy containing, by mass, 0.08-0.20% C, 0.05-0.45% Si, 0.10-0.30% Mn, 0.80-1.40% Ni, 1.00-1.40% Cr, 1.20-1.60% Mo, 0.10-0.30% V, 0.06-0.10% Ti, 0.0005-0.0010% B, not more than 0.01% P, not more than 0.01% S, and not more than 0.005% Al, the balance being Fe and unavoidable impurity elements.

2. A turbine casing wherein the casing as set forth in claim 1 is used for a turbine.

3. The turbine casing as set forth in claim 2, wherein the content ratio of Mn/Ni is in the range of 0.07-0.32.

4. The turbine casing as set forth in claim 2, wherein the content ratio of (Mo+V)/Ni is in the range of 0.93-2.38.

5. The turbine casing as set forth in claim 2, wherein the content ratio of (Mo+V)/Ni/B is in the range of 1000-5000.

6. A valve casing wherein the casing as set forth in claim 1 is used for a valve.

7. The casing as set forth in claim 1, wherein said alloy is a cast steel.

8. A casing formed from an alloy containing, by mass, 0.08-0.20% C, 0.05-0.45% Si, 0.10-0.30% Mn, 1.10-1.40% Ni, 1.00-1.40% Cr, 1.20-1.60% Mo, 0.10-0.30% V, 0.06-0.10% Ti, 0.0005-0.0010% B, not more than 0.01% P, not more than 0.01% S, and not more than 0.005% Al, the balance being Fe and unavoidable impurity elements.

9. A turbine casing wherein the casing as set forth in claim 8 is used for a turbine.

10. The turbine casing as set forth in claim 9, wherein the content ratio of Mn/Ni is in the range of 0.07-0.27.

11. The turbine casing as set forth in claim 9, wherein the content ratio of (Mo+V)/Ni is in the range of 0.93-1.73.

12. The turbine casing as set forth in claim 9, wherein the content ratio of (Mo+V)/Ni/B is in the range of 3500-5000.

13. A valve casing wherein the casing as set forth in claim 8 is used for a valve.

14. The casing as set forth in claim 8, wherein said alloy is a cast steel.

15. A steam turbine wherein the turbine casing as set forth in claim 2 is used.

16. A steam turbine wherein the valve casing as set forth in claim 6 is used.

17. A steam turbine wherein the turbine casing as set forth in claim 9 is used.

18. A steam turbine wherein the valve casing as set forth in claim 13 is used.

19. A casing formed from an alloy containing, by mass, 0.05-0.25% C, 0.05-0.75% Si, 0.10-0.30% Mn, 0.80-1.40% Ni, 0.50-2.00% Cr, 0.05-2.00% Mo, 0.05-0.50% V, 0.06-0.15% Ti, 0.0003-0.0030% B, not more than 0.01% P, not more than 0.01% S, and not more than 0.005% Al, the balance being Fe and unavoidable impurity elements, wherein the content ratio of Mn/Ni is in the range of 0.05-0.50, the content ratio of (Mo+V)/Ni is in the range of 0.71-3.16, and the content ratio of (Mo+V)/Ni/B is in the range of 200-5000.