Method and apparatus for welding workpieces of high-temperature superalloys

1. A method for welding a workpiece of high-temperature superalloy, comprising:

applying a welding filler to a workpiece surface by a heat input zone;

supplying the welding filler into the heat input zone by a supply zone;

moving the heat input zone and the supply zone in relation to the workpiece surface; and

choosing a welding parameter so that a cooling rate during solidifying is at least 8000 Kelvins per second,

wherein the workpiece comprises a γ′-containing nickel-based superalloy and the welding filler is a γ′-forming nickel-based superalloy material,

wherein the welding parameter is selected from the group consisting of: a welding power, speed of a welding process, and a diameter of the heat input zone,

wherein the speed of the welding process is at least 250 mm/min,

wherein a welding beam comprising a laser is applied on the workpiece surface to produce the heat input zone,

wherein a laser power is selected in a range of 100 W to 300 W, and

wherein a diameter of a laser beam is 500 μm to 800 μm.

2. The method as claimed in claim 1 , wherein a weld seam is produced by applying the welding filler layer by layer, and wherein a previously applied layer is remelted in less than half of its layer thickness.

3. The method as claimed in claim 2 , wherein the heat input zone and the supply zone are moved in relation to the workpiece surface along a welding direction for each layer, and wherein welding directions of successive layers are turned with respect to one another.

4. The method as claimed in claim 1 , wherein the heat input zone and the supply zone are moved in relation to the workpiece surface along a welding direction on a path oscillating around the welding direction.

5. The method as claimed in claim 1 , wherein a heat treatment is applied after applying the welding filler.

6. The method as claimed in claim 1 , wherein the laser comprises an Nd-YAG laser with λ=1.06 μm.

7. The method as claimed in claim 1 , wherein a polycrystalline weld seam is achieved.

8. A welding apparatus for welding a workpiece of high-temperature superalloy, comprising:

a heat source for producing a heat input zone on a workpiece surface;

a supplying device for supplying a welding filler into the heat input zone;

a transporting device for moving the heat source and the supplying device in relation to the workpiece surface; and

a control unit for setting a welding parameter so that a cooling rate during solidifying is at least 8000 Kelvins per second,

wherein the control unit sets the welding parameter that is selected from the group consisting of: a welding power, speed of a welding process, and a diameter of the heat input zone, and

wherein the workpiece comprises a γ′-containing nickel-based superalloy and the welding filler is a γ′-forming nickel-based superalloy material.

9. The welding apparatus as claimed in claim 8 , wherein the control unit moves the heat source and the supplying device in relation to the workpiece surface with a speed of at least 250 mm per minute.

10. The welding apparatus as claimed in claim 8 , wherein the control unit moves the heat input zone and the supply zone in relation to the workpiece surface along a welding direction on a path oscillating around the welding direction.

11. The welding apparatus as claimed in claim 8 , wherein a weld seam is produced by applying the welding filler layer by layer along a welding direction, and wherein the control unit turns welding directions of successive layers with respect to one another.

12. The welding apparatus as claimed in claim 8 , wherein the heat source comprises a 300 W laser.

13. The welding apparatus as claimed in claim 12 , wherein the laser comprises an Nd-YAG laser with λ=1.06 μm.