Component with compressive residual stresses, process for producing and apparatus for generating compressive residual stresses
View Patent ↗The inventive method discloses the local, adapted and controlled introduction of internal compressive stress in convex and concave regions, such as the root region of turbine blades, by means of at least two pressure generators.
1. A process for producing a turbine component, comprising:
shot peening a surface region of the component to produce a locally different compressive residual stress on the region by a first shot peening nozzle; and
shot peening the surface region to produce a smoothed surface finish by a second shot peening nozzle,
wherein the two shot peening nozzles are operated simultaneously and different peening pressures and shot diameters are used for the two shot-peening nozzles.
2. The process as claimed in claim 1 , wherein the surface region has a plurality of concavely curved and a convexly curved regions.
3. The process as claimed in claim 1 , wherein the second shot-peening nozzle is operated after the first shot-peening nozzle.
4. The process as claimed in claim 2 , wherein operating parameters for the shot-peening nozzle are selected from the group consisting of: peening pressure, peening abrasive size, peening abrasive material, peening angle of incidence, and peening blasting shape.
5. The process as claimed in claim 2 , wherein different parameters are set for the first and second nozzles and the concavely curved regions and a convexly curved regions are peened at the same time by multiple passes by the nozzles over the concavely and convexly curved regions.
6. The process as claimed in claims 1 , wherein the shot peen nozzles or the component are guided in a controlled way based on scanning of the component regions by a laser.
7. The process as claimed in claim 6 , wherein the second nozzle is operated using a lower peening pressure and a larger diameter shot than was used with the first nozzle.
8. The process as claimed in claim 7 , wherein the first nozzle contains shot of different size diameter.
9. The process as claimed in claim 8 , wherein the first and second nozzles contain shot of different material hardness.
10. The process as claimed in claim 9 , wherein the shot is made from ceramic or metal.
11. The process as claimed in claim 10 , wherein the component is a blade, a vane or a heat shield element.
12. The process as claimed in claim 11 , wherein the angle of incidence between a peening direction of a shot-peening nozzle and a curved surface of the component is between 80° and 85°.
13. The process as claimed in claim 2 , wherein in a first process step a shot-peening treatment of a region is performed using a defined peening pressure, and in a second process step the same region is peened using a lower peening pressure to shift the maximum of the compressive residual stress to the surface of the component.