Single crystal welding of directionally compacted materials

Patent metadata

Field	Value
Publication number	US-9458552-B2
Application number	US-201214115940-A
Country	US
Kind code	B2
Filing date	Apr 13, 2012
Priority date	May 9, 2011
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

A process for welding directionally solidified metallic materials is presented. Process parameters are targeted selected with respect to laser welding, advancement, laser power beam diameter and powder mass flow. The temperature gradient, which is fundamentally decisive for the single-crystal growth during laser cladding, may be set in a targeted manner.

First claim

The invention claimed is:

1. A process for a directional solidification of a weld seam during build-up welding of a substrate of a component, wherein the substrate is directionally solidified and comprises dendrites, and wherein the dendrites extend in a substrate dendrite direction, the process comprising:
performing a build up welding process on a surface of the substrate by repeated application, melting, and resolidification of at least a powder material,
wherein the build up welding is done according to process parameters comprising a feed rate, a laser power, a diameter of welding beam, and powder mass flow such that the process parameters lead to a local orientation of a temperature gradient on a solidification front during the process, and
wherein the local orientation of the temperature gradient on the solidification front is smaller than 45° with respect to the substrate dendrite direction of the dendrites in the substrate.

2. The process as claimed in claim 1 , wherein the feed rate is between 30 mm/min and 100 mm/min.

3. The process as claimed in claim 1 , wherein the laser power is between 200 W and 500 W.

4. The process as claimed in claim 1 , wherein the diameter of the welding beam on a surface of the substrate is between 3 mm and 6 mm.

5. The process as claimed in claim 1 , wherein a feed rate of the mass flow is between 300 mg/min and 600 mg/min.

6. The process as claimed in claim 1 , wherein a melt which is generated by supply of powder and/or material of the substrate is formed on and in the substrate, wherein the melt is covered completely by the welding beam or by a laser beam, and wherein the melt is overlapped.

7. The process as claimed in claim 6 , wherein the supply of the powder is applied in layers.

8. The process as claimed in claim 1 , wherein the substrate comprises a nickel-based superalloy, or comprises columnar grains, or comprises a single-crystal microstructure.

9. The process as claimed in claim 1 , wherein a diameter of powder particles is so small that the powder particles melt completely in the welding beam and have a high temperature.

10. The process as claimed in claim 9 , wherein the temperature of the melted powder particles is 20° C. above a melting temperature of the powder particles.

11. The process as claimed in claim 1 , wherein the welding beam comprises a laser beam.

12. The process as claimed in claim 1 , wherein a condition for the local orientation of the temperature gradient on the solidification front comprises:

1
λ

*
A
*

I
L

(

∂
T

∂
x

⁢

(

V
V

)

)

2

=

(

∂
T

∂
γ

⁢

(

V
V

)

)

2

+

(

1
λ

+

A
*

I
L

)

2

≥
0.707

=

cos
⁡

(

45
∘

)

A: Degree of absorption of the substrate,
I L : Welding beam intensity,
V V : Feed rate,
λ: Thermal conductivity of the substrate,
T: Temperature.

13. A process for a directional solidification of a weld seam during build-up welding of a substrate of a component, wherein the substrate is directionally solidified and comprises dendrites, and wherein the dendrites extend in a substrate dendrite direction, the process comprising:
depositing a powder material on the substrate;
subjecting at least the powder material to an amount of energy effective to melt the powder material;
solidifying the molten material to provide a directionally solidified weld;
wherein the depositing and subjecting steps are done according to process parameters selected from the group consisting of a feed rate, a laser power, a diameter of welding beam, powder jet focus, a powder mass flow, and combinations thereof such that the process produces a local orientation of a temperature gradient on a solidification front,
wherein a condition for the local orientation of the temperature gradient on the solidification front comprises:

1
λ

*
A
*

I
L

(

Assignees

• Arjakine Nikolai
• Bostanjoglo Georg
• Burbaum Bernd
• Gasser Andres
• Jambor Torsten
• Jokisch Torsten
• Linnenbrink Stefanie
• Mokadem Selim
• Ott Michael
• Pirch Norbert
• Wilkenhöner Rolf
• Fraunhofer Ges Forschung
• Siemens Ag

Inventors

• Arjakine Nikolai
• Bostanjoglo Georg
• Burbaum Bernd
• Gasser Andres
• Jambor Torsten
• Jokisch Torsten
• Linnenbrink Stefanie
• Mokadem Selim
• Ott Michael
• Pirch Norbert
• Wilkenhöner Rolf

Classifications

• B23K2203/50

  Operations & Transport · mapped topic

• F05D2300/605

  Crystalline · CPC title

• B23K26/32

  taking account of the properties of the material involved · CPC title

• B23K35/0244

  Powders, particles or spheres; Preforms made therefrom · CPC title

• F05D2230/232

  by welding · CPC title