OSCILLATING WELDING METHOD
A method is provided for welding a substrate, in which an energy source and/or a material feed is or are moved in an oscillating motion over the surface of the substrate. The oscillating movement in a vertical and/or horizontal direction during welding results in smaller grains, which prevent the formation of fractures during welding.
This application is a continuation application of U.S. application Ser. No. 15/110,773, filed Jul. 11, 2016, and entitled “OSCILLATING WELDING METHOD”, which claims priority to PCT Application No. PCT/EP2014/053389, having a filing date of Feb. 21, 2014, based off of DE Application No. 102014200834.4 having a filing date of Jan. 17, 2014, the entire contents of which are hereby incorporated by reference.
FIELD OF TECHNOLOGYThe following relates to a welding method in which the welding beam is moved in oscillation.
BACKGROUNDDuring the laser deposition welding of nickel-based superalloys having a high proportion of metallic phase γ′, hot cracks can already form during solidification of the melt. By reducing the beam diameter of the laser with a circular intensity distribution, smaller grains are achieved and solidification cracks can be avoided, but this reduces the rate of deposition of the material.
SUMMARYAn aspect relates to a welding method which makes it possible to achieve small grains and high deposition rates.
An oscillating motion in the horizontal direction should cause the solidification front to change constantly so as to produce an oscillating solidification form. As a result of a constantly changing solidification function, the grain growth is interrupted during the solidification of the melt and the microstructure solidifies in fine-grained form. The fine-grained quality of the microstructure causes the welding residual stresses which thus remain to be distributed over the grain boundaries so as to avoid cracks in the weld seam or in the weld metal.
The welding method can be remelting or deposition welding. Both methods produce a melt and a solidification front.
Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
The figures and the description represent only exemplary embodiments of the invention.
The method is thus not limited to laser welding methods, but is also applicable for electron beam welding methods and other plasma welding methods with corresponding energy sources.
Material 8 is deposited onto a substrate 3, which, in the case of turbine blades or vanes, is a nickel-based or cobalt-based superalloy having a high γ′ proportion and therefore generally an alloy having poor weldability.
A welding bead 6, as part of the deposition weld, has already been generated.
In the case of a remelt method, the welding bead is the remelted region.
At those points where a laser, as an exemplary energy source 13, directs the laser beams 15 (
A powder nozzle, as the material feed 14, preferably feeds powder 8, with the powder 8 being melted, in this case by laser radiation 15. The material 8 is fed in the form of powder, but may also be fed as a wire. This laser radiation 15 is in particular pulsed.
The area to be welded is made up of a plurality of welding beads lying next to one another and if appropriate one above another and preferably has, in at least one direction, a length of greater than or equal to 4 mm.
The oscillating motion is preferably affected only in one plane.
The triangular shape 44; 31, 34; 43, 49, 55 is preferably an acute-angled triangle, with a height (in the direction of movement 2) of the triangular shape 44 preferably being at least twice the magnitude of the base 24.
An oscillating motion preferably proceeds as follows:
From a first starting point 21 (
In order that the laser radiation 15 continues to move along as a whole in the direction of movement 2, it then moves obliquely with respect to the direction of movement 2 in the direction of movement 2 in a first oblique direction 30 (
From there, the laser radiation 15 then moves forward again as far as a third deflection point 33. The third deflection point 33 lies downstream of the first starting point 21 in the direction of movement 2. A connecting line between points 21, 33 is parallel to the direction of movement 2. From there, the laser radiation 15 oscillates again at an angle with respect to the direction of movement 2 counter to the direction of movement 2 as far as a fourth deflection point 34.
The fourth deflection point 34 is level with the second starting point 31 in a perpendicular direction with respect to the direction of movement 2 and level with the second deflection point 23 in the direction of movement 2.
In a second perpendicular direction of movement 36 which is perpendicular with respect to the direction of movement 2, the laser radiation 15 moves back to the second starting point 31 of the triangular oscillating motion (
The further triangular oscillating motion proceeding from
From the fifth deflection point 43, the laser radiation 15 moves obliquely with respect to the direction of movement 2 counter to the direction of movement 2 in a third rearward motion 46 as far as a sixth deflection point 49. From the sixth deflection point 49, the laser radiation 15 oscillates perpendicularly with respect to the direction of movement 2 to the seventh deflection point 55.
Effectively, a triangular shape is always displaced in the direction of movement 2 for the course of the laser radiation 15, such that the triangular shapes overlap.
This represents only one procedure for the preferably triangular oscillation.
On account of embodiments of the invention, this procedure achieves improved material properties.
Although the present embodiments of 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.
Claims
1. A method for welding a substrate, comprising the following step:
- providing an energy source and a material feed;
- moving at least one of the energy source and the material feed horizontally in an oscillating motion with respect to a surface of the substrate, wherein the oscillating motion is done in one of a perpendicular and oblique direction with respect to a direction of motion of at least one of the energy source and the material feed such that a weld will overlap a previous weld and such that grain growth is interrupted during the solidification of the melt; and
- emitting energy and material with respect to the surface of a substrate, during the oscillating, thereby producing the weld on the surface of the substrate.
2. The method as claimed in claim 1, in which remelt welding takes place.
3. The method as claimed in claim 1, in which deposition welding takes place.
4. The method as claimed in claim 1, in which the energy source is moved in an oscillating motion at least once in a triangular shape with respect to the surface.
5. The method as claimed in claim 1, in which the energy source and the material feed are moved in an oscillating motion at least once at least partially in a triangular shape with respect to the surface.
6. The method as claimed in claim 1, in which the energy source and the material feed are moved in an oscillating motion at least once in a triangular shape with respect to the surface.
7. The method as claimed in claim 1, in which laser radiation is used as the energy source.
8. The method as claimed in claim 1, in which powder is fed via the material feed.
9. The method as claimed in claim 1, in which nickel-based or cobalt-based superalloys are used as the substrate.
10. The method as claimed in claim 1, in which use is made of a welding nozzle, which has the material feed wherein the material feed is a powder feed, and generation and supply of the energy wherein the energy is laser radiation.
11. The method as claimed in claim 1, in which the oscillating deflection is up to 2 mm.
12. The method as claimed in claim 1, in which the welded area is ≥4 mm in at least one orientation.
13. The method as claimed in claim 1, in which the energy source and/or material feed are moved repeatedly perpendicularly, with respect to the direction of movement.
14. The method as claimed in claim 1, in which the oscillating motion is effected only two-dimensionally.
Type: Application
Filed: Nov 20, 2018
Publication Date: Mar 28, 2019
Inventors: BERD BURBAUM (FALKENSEE), TORSTEN JOKISCH (NEUENHAGEN BEI BERLIN), MICHAEL OTT (MÜLHEIM AM DER RUHR)
Application Number: 16/196,524