Patent Application
20180274366
The following relates to the production of steel or titanium products, in particular from the high-temperature range, wherein for welding use is made of a precipitation-hardening nickel-based alloy, and to a component.
When overhauling low-pressure blades of steam turbines made of steel or titanium, the following measures are taken, depending on the degree of damage:
1 Time-limited continued operation of the damaged blade—insofar as permissible—with a new inspection interval and with the drawback that owing to the removal of material the natural frequency of the blade is different and also the efficiency is impaired.
2 Replacing the blade with a substitute blade or new part, in the event that the degree of damage does not permit continued operation.
3 Repairing the blade by welding using a cobalt-based alloy which is very resistant to water droplet erosion. Owing to the poor suitability for welding, processing is very difficult and onerous. The large difference in material properties between the repair material and the base material can lead to residual stresses, cracks and even spalling.
4 As for 3, but with a primer, which does however make the process more demanding.
An aspect relates to solving the aforementioned problems.
Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
A method is disclosed for producing, in particular for repairing, a component (1′, 1″) having a substrate (4), in particular turbine blades made of steel or titanium, in particular made of martensitic or precipitation-hardening chromium-rich steels, with a localized deposition weld (7) or with an affixed shaped part (10), in which a precipitation-hardening nickel-based alloy is used as the localized deposition weld (7) or as the shaped part (10), in which a laser powder deposition weld or an arc deposition weld is performed.
A component (1′, 1″) is disclosed, in particular produced having a substrate (4) made of steel or titanium, in particular made of martensitic or precipitation-hardening chromium-rich steels, and having only locally material of a precipitation-hardening nickel-based alloy, in which a laser powder deposition weld or an arc deposition weld is performed.
Nickel-based materials, in the precipitation-hardened state after suitable heat treatment, can be very resistant to water droplet erosion and moreover are distinguished by their good weldability in comparison to the cobalt-based group of materials. An onerous primer is not required.
The welding can preferably be performed using suitable methods such as laser welding or arc welding.
The deposition weld can advantageously have just one layer.
Another possibility is to braze in place shaped parts (inserts).
Nickel-based superalloys with the precipitation hardening on the basis of γ′ are known from gas turbine engineering, in which precipitation-hardening nickel-based alloys are also again used to repair these alloys (like-for-like repair).
Unexpectedly, the combination of precipitation-hardening nickel-based alloys and substrate 4 made of steel or titanium, this meaning titanium and titanium alloys as material, (
The shaped part 10 (insert) which is welded or brazed in or on is then also made of a precipitation-hardening nickel-based alloy.
The shaped part 10 or the deposition weld is heat-treated prior to or after connection. The insert 10 and the substrate 4 are joined by simple material bonding and then have a connection layer or brazing layer 13 (
When a shaped part 10 is brazed in place for the new production or repair of a component 1″, it is possible to use any desired brazing material, wherein the shaped part 10 also has a precipitation-hardening nickel-based alloy.
Preferably, the method is used to produce or repair leading edges of turbine blades, in particular of steam turbines.
The nickel-based alloy as a deposition weld 7 or as a shaped part 10 is preferably present only locally in or on the substrate 4 of the component 1′, 1″.
Deposition welding 7 is performed in particular by laser powder deposition welding or by arc deposition welding.
The precipitation-hardening nickel-based alloy preferably has the following composition:
a chromium content (Cr) of 10 wt % to 21 wt %
and/or
a niobium content (Nb) of 0.1 wt % to 5.5 wt %
and/or
a molybdenum content of 0.1 wt % to 3.3 wt %,
in particular IN 718.
The nickel-based alloy that is used preferably has a γ′ fraction≤50%, in particular≤40%, most particularly≤30%.
The deposition weld 7 preferably has just one layer.
X20Cr13, X5CrNiCuNb16−4 or TiAl6V4 are preferably used as the material for the substrate 4.
Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 219 351.9 | Oct 2015 | DE | national |
This application claims priority to PCT Application No. PCT/EP2016/071260, having a filing date of Sep. 9, 2016 based off of German application No. 102015219351.9 having a filing date of Oct. 7, 2015, the entire contents of both of which are hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/071260 | 9/9/2016 | WO | 00 |
