Turbine casing comprising a low-stress connection flange, and exhaust-gas turbine having such a turbine casing

1. A turbine casing for an exhaust-gas turbine, the turbine casing having a connection flange for bearing-casing-side attachment to a bearing casing, wherein the connection flange defines casing-connection bores that are mutually spaced in a circumferential direction wherein the connection flange further comprises: a clamping edge including a depression bottom, the depression bottom extending in the circumferential direction over an entire circumference of the connection flange and positioned in a radially inner edge region of the clamping edge, the depression bottom defining an annular depression and material recesses, wherein the material recesses have a depth into the depression bottom greater than a depth of the annular depression, and wherein the material recesses are positioned between mutually adjacent casing-connection bores, the material recesses oriented radially inward toward a central longitudinal axis of the turbine casing and oriented radially inward from a main body of the turbine casing.

2. The turbine casing as claimed in claim 1 , wherein the mutually spaced casing-connection bores in the connection flange are arranged in the circumferential direction along at least one circle.

3. The turbine casing as claimed in claim 2 , wherein the clamping edge is arranged adjacent to the casing-connection bores in a radial direction.

4. The turbine casing as claimed in claim 3 , wherein the adjacent casing-connection bores are surrounded, at least in one section, by connection webs arranged in a manner recessed in an axial direction of the turbine casing with respect to the clamping edge, wherein the material recesses provided between each case of two adjacent casing-connection bores are arranged in a manner recessed in an axial direction of the turbine casing with respect to the connection webs.

5. The turbine casing as claimed in claim 4 , wherein the clamping edge has, in a region between two adjacent casing-connection bores, a respective clamping edge recess that widens the annular depression.

6. The turbine casing as claimed in claim 5 , wherein a depth of the clamping edge recess coincides with a sum of the depth of the annular depression and a depth of the casing-connection bores provided in the annular depression, and wherein these depths extend in the axial direction of the turbine casing.

7. The turbine casing as claimed in claim 2 , wherein the turbine casing is of a multi-piece design.

8. The turbine casing as claimed in claim 7 , wherein the clamping edge forms a separate component of the turbine casing.

9. The turbine casing as claimed in claim 7 , wherein a heat shield and/or a nozzle ring forms a separate component of the turbine casing.

10. The turbine casing as claimed in claim 9 , wherein the clamping edge is part of the heat shield or of the nozzle ring.

11. An exhaust-gas turbine having the turbine casing as claimed in claim 1 .

12. The exhaust-gas turbine as claimed in claim 11 , wherein the exhaust-gas turbine has a bearing casing connected to the turbine casing, wherein the turbine casing is connected to the bearing casing by connection elements.

13. The exhaust-gas turbine as claimed in claim 12 , wherein the exhaust-gas turbine has clamping elements that are each pressed against the connection flange of the turbine casing and against the bearing casing by one or more connection elements.

14. The exhaust-gas turbine as claimed in claim 13 , wherein the clamping elements are pressed against the clamping edge.

15. The exhaust-gas turbine as claimed in claim 12 , wherein the connection elements are screws or threaded pins.