SHAFT ELEMENT, METHOD FOR PRODUCING A SHAFT ELEMENT COMPOSED OF TWO DIFFERENT MATERIALS, AND CORRESPONDING TURBOMACHINE

Abstract

A shaft element of a turbomachine, in particular of a combined steam turbine, having at least two shaft subsegments integrally joined to each other by means of a weld, wherein different chemical and mechanical properties are inherent to the shaft subsegments, wherein the weld has a ratio of welding layer height to weld width of 1:14 to 1:2. A method produces a shaft element composed of two different materials having at least two shaft subsegments integrally joined to each other by means of a weld.

Claims

1. A shaft element of a turbomachine or of a combined steam turbine, comprising: at least two shaft sub-portions that are joined together in a materially integral manner by means of a weld seam, in the case of which dissimilar chemical and mechanical properties are inherent to these shaft sub-portions, wherein the weld seam has a weld pass height/weld seam width ratio of 1:14 to 1:2, wherein the first of the at least two shaft sub-portions is produced from a heat-resistant material 1CrMoV, 2CrMoV, 2CrMoNiWV, 10CrMoWVNbN, 10CrMoVNbN, 9CrMoCoBNbN, or 9Cr3Co3WNbBN.

2. The shaft element as claimed in claim 1, wherein the weld seam comprises a plurality of weld passes which in each case are generated by a single weld bead, so as to achieve a weld-pass heat treatment, or an intermediate-pass heat treatment, of the respective weld pass that lies therebelow, by way of the adjusted geometry of the respective weld bead.

3. The shaft element as claimed claim 1, wherein the weld seam comprises two axially opposite steep joint flanks which in each case in relation to a vertical have an opening angle of <1.5, so as to positively control a penetration of an input of thermal energy.

4. The shaft element as claimed in claim 1, wherein the further of the at least two shaft sub-portions is produced from a tough-at-cold-temperature material 2.0-4.0NiCrMoV, 2.0-4.0NiCrMoV Super Clean, or 2CrNiMo.

5. The shaft element as claimed in claim 1, wherein the further of the at least two shaft sub-portions is produced from a low alloyed heat-resistant material 1CrMoV, 2CrMoV, or 2CrMoNiWV, and the second material is of the type 10CrMoWVNbN, 10CrMoVNbN, 9CrMoCoBNbN, or 9Cr3Co3WNbBN.

6. A method for producing a shaft element (1) that is composed of two dissimilar materials, comprising: joining two shaft segments that are composed of dissimilar materials together in a materially integral manner by means of a weld seam so as to form the shaft element, wherein the weld seam is generated having a weld pass height to weld seam width ratio of 1:14 to 1:2, wherein the first of the at least two shaft sub-portions is produced from a heat-resistant material 1CrMoV, 2CrMoV, 2CrMoNiWV, 10CrMoWVNbN, 10CrMoVNbN, 9CrMoCoBNbN, or 9Cr3Co3WNbBN.

7. The method as claimed in claim 6, wherein weld passes of the weld seam are generated by only a single weld bead, so as to achieve a weld-pass heat treatment, or an intermediate-pass heat treatment, of the respective weld pass that lies therebelow, by way of the adjusted geometry of the respective weld bead.

8. The method as claimed in claim 6, wherein one shaft segment prior to welding, at least in a region of a welding flank, is pre-heated to a pre-heating temperature between 100 C. and 350 C., in order for a distribution of the thermal flow to be improved.

9. The method as claimed in claim 6, wherein the weld seam, or the individual weld beads of the weld passes, is/are generated by means of a welding rate of 30 mm/min to 450 mm/min.

10. The method as claimed in claim 6, wherein the weld seam, or the individual weld beads of the weld passes, is/are generated by means of an energy input per unit length of 5 kJ/cm to 30 kJ/cm.

11. The method as claimed in claim 6, wherein the weld seam, or the individual weld beads of the weld passes are subjected to a localized thermal treatment.

12. A turbomachine comprising: a shaft element as claimed in claim 1 wherein the shaft element revolves about an axial axis and has two shaft sub-portions of dissimilar materials, which are interconnected in a materially integral manner by a weld seam.

13. The shaft element as claimed in claim 3, wherein the opening angle is <1.

14. The method as claimed in claim 8, wherein the pre-heating temperature is between 150 C. and 300 C.

15. The method as claimed in claim 9, wherein the welding rate is 40 mm/min to 350 mm/min.

16. A turbomachine, comprising: a shaft element that revolves about an axial axis and has two shaft sub-portions of dissimilar materials, which are interconnected in a materially integral manner by a weld seam, wherein the shaft element is produced by the method of claim 6.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In the drawing:

[0057] FIG. 1 schematically shows a partial view of a shaft element of a steam turbine, in a transitional region between a medium-pressure turbine part and a low-pressure turbine part, having two shaft sub-portions which are composed of dissimilar materials and are joined together in a materially integral manner by means of a welded connection; and

[0058] FIG. 2 schematically shows the welded connection in a peripheral region of a first shaft segment of a heat-resistant material, and of a further shaft segment of a tough-at-cold-temperature material, of the shaft element shown in FIG. 1, wherein the first shaft segment configures the shaft sub-portion on the medium-pressure turbine part, and the further shaft segment configures the shaft sub-portion on the low-pressure turbine part.

DETAILED DESCRIPTION OF INVENTION

[0059] The shaft element 1 shown in FIG. 1 serves for receiving a multiplicity of blades (not illustrated), and is installed in such a manner in a turbomachine 2 (not shown in more detail) that said shaft element 1 during operation of the turbomachine 2 rotates about an axial rotation axis 3.

[0060] The turbomachine 2 in this exemplary embodiment is a combined steam turbine 4 (not shown in more detail) which is distinguished by a medium-pressure turbine part (not shown) and, adjacent downstream thereof, by a low-pressure turbine part (not shown).

[0061] The shaft element 1 in the axial direction 5 extends further along the axial rotation axis 3, from an entry region 6 of the combined steam turbine 4 through a medium-pressure region 7 of the combined steam turbine 4 by way of a low-pressure region 8 of the combined steam turbine 4 up to an exit region 10 of the combined steam turbine 4.

[0062] A first shaft portion 15 herein is located substantially in the medium-pressure region 7, and a further shaft portion 16 is disposed substantially in the low-pressure region 8, such that these shaft sub-portions 15 and 16 interact with an operating medium, largely super-heated steam, that perfuses the combined steam turbine 4 from the entry region 6 to the exit region 10.

[0063] The operating medium herein in the medium-pressure region 7 in particular has an operating temperature that is even higher than in the low-pressure region 8, such that the first shaft sub-portion 15 is thermally stressed to a higher degree than the further shaft sub-portion 16 of the shaft element 1.

[0064] However, the further shaft sub-portion 16 is mechanically stressed to a higher degree than the first shaft sub-portion 15 of the shaft element 1.

[0065] This necessitates that the first shaft portion 15 of the shaft element 1 should be produced from a material (not identified by a separate reference sign) that is more heat-resistant than that of the further shaft portion 16 of the shaft element 1.

[0066] The heat-resistant material used here is 1CrMoV.

[0067] Alternatively, however, the latter can also be replaced by one of the other heat-resistant materials 2CrMoNiWV, 10CrMoWVNbN, 10CrMoVNbN or 9CrMoCoBNbN, or 9Cr3Co3WNbBN, respectively.

Consequently, the further shaft portion 16 of the shaft element 1 should be produced from a material (not identified by a separate reference sign) that is tougher-at-cold-temperature than that of the first shaft portion 15 of the shaft element 1.

[0068] The tough-at-cold-temperature material used here is 2.0 NiCrMoV.

[0069] Alternatively, however, the latter can also be replaced by one of the other tough-at-cold-temperature materials 2.0-4.0NiCrMoV, 2.0-4.0NiCrMoV Super Clean, or 2CrNiMo.

[0070] In any case, the shaft element 1 is composed of a first shaft segment 20 (heat-resistant material) and of a further shaft segment 21 (tough-at-cold-temperature material), wherein the two different shaft segments are thermally joined, that is to say joined together in a materially integral manner by means of a welded connection 22.

[0071] FIG. 2 schematically and partially shows the construction of a weld seam 23 of the welded connection 22 by means of a peripheral region fragment 24 of the shaft element 1.

[0072] The welded connection 22, or the weld seam 23, respectively, is based on a narrow gap 25 between the first shaft segment 20 and the further shaft segment 21, the two latter being axially opposite one another and forming a welding joint 26.

[0073] Two joint flanks 29 and 30 which are formed by the shaft segments 20 and 21 are present on the welding joint 26, wherein each of the joint flanks 29 and 30 in relation to the vertical 31 has an opening angle 32 of only <1 (a merely exemplary indication). On account thereof, the effects of an undesirable thermal input into the neighboring material regions can be reduced. The opening angle 32 and thus the inclined positioning of the joint flanks, or of the welding flanks 29 and 30, respectively, herein are illustrated in an exaggerated manner.

[0074] The weld seam 23 that is configured according to the concept of the invention can now be further configured in an advantageous manner on the welding joint 26 thus prepared.

[0075] The weld seam 23 is distinguished in particular by a weld pass height/weld seam width ratio 35 of 1:14 to 1:2, wherein in the present case the weld pass height 36 is formulated by the thickness 37 of an individual weld bead 38, and the weld seam width 39 is formulated by the width 40 of the respective individual weld bead 38.

[0076] The weld pass height/weld seam width ratio 35 in this exemplary embodiment depends also on the joint width that varies in the direction of the vertical 31.

[0077] The thickness 37 of the weld pass height 36 herein is aligned in the direction of the vertical 31, and the width 40 of the weld seam width 39 extends transversely to this vertical 31.

[0078] A further particularity of the present welded connection 22, or of the weld seam 23, respectively, is derived in that each of the weld passes 41 has only a single weld bead 38. The heat treatment of the weld passes can thus be influenced in a particularly simple manner.

[0079] Each of the weld beads 38 herein in an exemplary manner has been generated at a welding rate of 100 mm/min at an energy input per unit length of 15 kJ/cm.

[0080] The welding flanks 29 and 30 herein in an exemplary manner have previously been pre-heated to a pre-heating temperature of 200 C., in order for an improved distribution of the thermal flow to be achieved.

[0081] While the invention has been illustrated and described in more detail by the preferred exemplary embodiment, the invention is not limited by this disclosed exemplary embodiment, and other variations can be derived therefrom by a person skilled in the art, without departing from the scope of protection of the invention.