A TUBE MADE OF AN AUSTENITIC STAINLESS STEEL AND A METHOD FOR MANUFACTURING THEREOF

Abstract

The present disclosure relates to a tube made of an austenitic stainless steel comprising, in weight %, C0.080, 8.00Mn10.00, Si1.00, P0.030, S0.030, 19.00Cr21.50, 5.50Ni7.50, 0.15N0.40, Mo0.75, Cu0.75, which is balanced by Fe and normally occurring impurities. So far tubes made of an austenitic stainless steel comprising this composition of ingredients are welded. A major problem of welded tubes is the risk for cracking, where the weld zone is the preferential location for cracking. This is especially a problem for applications under extreme conditions like in the aircraft or aerospace industry. It is therefore an aspect of the present disclosure to provide a tube made of an austenitic stainless steel comprising the foresaid components which at least overcomes one of the foresaid problems. Furthermore, it is an aspect of the disclosure to provide tubes that have less weight as tube known from the state of the art but increases the security and lead to a higher standard in the aircraft and aerospace industry. At least one of the above aspects is solved by a foresaid tube, wherein that the tube is a seamless tube.

Claims

1. A tube made of an austenitic stainless steel comprising, in weight %, C0.080, 8.00Mn10.00, Si1.00, P0.030, S0.030, 19.00Cr21.50, 5.50Ni7.50, 0.15N0.40, Mo0.75, Cu0.75, balance Fe and normally occurring impurities, wherein the tube is a seamless tube.

2. The tube according to claim 1, wherein the tube is obtained by a method comprising the steps providing a melt 100 of an austenitic stainless steel comprising, in weight %, C0.080, 8.00Mn10.00, Si1.00, P0.030, S0.030, 19.00Cr21.50, 5.50Ni7.50, 0.15N0.40, Mo0.75, Cu0.75, balance Fe and normally occurring impurities; extruding a billet from the melt; hot forming of the billet into a tubular hollow; cooling the hollow; and cold forming the hollow into the tube.

3. The tube according to claim 2, wherein the cold forming is cold pilger milling or cold drawing.

4. The tube according to claim 3, wherein the tube is cold formed by cold pilger milling and the tube after cold pilger milling is cold drawn through a drawing die.

5. The tube according to claim 1, wherein the tube has an outer diameter of 40 mm or less and a wall thickness of 1.32 mm or less.

6. An aircraft with a fluid transmitting equipment, a fluid receiving equipment and a conduit in fluid communication with the fluid transmitting equipment and with the fluid receiving equipment for guiding a fluid between the fluid transmitting equipment and the fluid receiving equipment, wherein at least a section of the conduit is provided by the tube according to claim 1.

7. The aircraft according to claim 6, wherein the fluid transmitting equipment is a fuel reservoir, the fluid receiving equipment is an aircraft engine, and the conduit is a fuel line for guiding fuel between the fuel reservoir and the aircraft engine.

8. The aircraft according to claim 7, wherein the aircraft engine is a turbine.

9. The aircraft according to claim 6, wherein the fluid transmitting equipment is a hydraulic pump, the fluid receiving equipment is a hydraulic motor, and the conduit is a hydraulic line for guiding a hydraulic fluid between the hydraulic pump and the hydraulic motor.

10. The aircraft according to claim 9, wherein the hydraulic motor is a hydraulic actuator.

11. A method for manufacturing a tube comprising the steps: providing a melt of an austenitic stainless steel comprising, in weight %, C0.080, 8.00Mn10.00, Si1.00, P0.030, S0.030, 19.00Cr21.50, 5.50Ni7.50, 0.15N0.40, Mo0.75, Cu0.75, balance Fe and normally occurring impurities; extruding a billet from the melt; hot forming of the billet into a tubular hollow; cooling the hollow; and cold forming the hollow into the tube.

12. The method according to claim 11, wherein the hollow is cold formed by cold pilger milling, and wherein the tube after cold pilger milling is cold drawn.

13. The method according to claim 11, wherein the tube after cold forming is treated by ring autofrettage or ball autofrettage.

14. The method according to claim 13, wherein the tube after cold pilger milling is annealed at a temperature in a range from 400 C. to 460 C., and wherein during annealing the tube is kept in a controlled atmosphere.

15. A use of a tube according to claim 1 for guiding a fluid in an aircraft.

16. The method according to claim 12, wherein the tube after cold forming is treated by ring autofrettage or ball autofrettage.

17. The method according to claim 16, wherein the tube after cold pilger milling is annealed at a temperature in a range from 400 C. to 460 C., and wherein during annealing the tube is kept in a controlled atmosphere.

18. The method according to claim 11, wherein the tube after cold pilger milling is annealed at a temperature in a range from 400 C. to 460 C., and wherein during annealing the tube is kept in a controlled atmosphere.

19. The method according to claim 12, wherein the tube after cold pilger milling is annealed at a temperature in a range from 400 C. to 460 C., and wherein during annealing the tube is kept in a controlled atmosphere.

20. The aircraft according to claim 7, wherein the fluid transmitting equipment is a hydraulic pump, the fluid receiving equipment is a hydraulic motor, and the conduit is a hydraulic line for guiding a hydraulic fluid between the hydraulic pump and the hydraulic motor.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0060] Further advantages, features and applications of the present disclosure will become apparent from the following description of embodiments and the corresponding figures attached. The foregoing as well as the following detailed description of the embodiments will be better understood when read in conjunction with the appended drawings. It should be understood that the embodiments depicted are not limited to the precise arrangements and instrumentalities shown.

[0061] FIG. 1 is a schematic front view of an aircraft according to an embodiment of the present disclosure.

[0062] FIG. 2 is a schematic side view of an aircraft according to an embodiment of the present disclosure.

[0063] FIG. 3 is a flow chart of a method according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0064] FIG. 1 is a schematic front view of an aircraft 1 according to an embodiment of the present disclosure, wherein the fluid lines are tubes 2 according to an embodiment of the present disclosure. The fuel reservoirs 3 are arranged in the wings of the aircraft 1 being in fluid communication with the turbines 4 across the tubes 2.

[0065] FIG. 2 is a schematic side view of an aircraft 1 according to an embodiment of the present disclosure, wherein the hydraulic lines are tubes 2 according to an embodiment of the present disclosure. The hydraulic pump 5 is arranged in the body of the aircraft 1 being in fluid communication with the hydraulic actuator 6 across the tubes 2.

[0066] The hydraulic fluid is pumped from a reservoir (unembodied), by the hydraulic pump 5. In order to keep the hydraulic fluid clean, usually the hydraulic fluid is filtered (unembodied). Via fluid communication across the tubes 2 the hydraulic fluid reaches the hydraulic actuator 6 and the fluid power is turned into work by a piston. This power is then used to move a rudder.

[0067] FIG. 3 is a flow chart describing a method for forming a hollow into the tube 2 used in the applications described with reference to FIGS. 1 and 2. In a first step 100, a melt of an austenitic stainless steel is provided, wherein the austenitic stainless steel consists of, in weight %, C0.080, 8.00Mn10.00, Si1.00, P0.030, S0.030, 19.00Cr21.50, 5.50Ni7.50, 0.15N0.40, Mo0.75, Cu0.75, balance Fe and normally occurring impurities.

[0068] After extruding a billet from the melt in a second step 101, the billet is hot rolled 102 into a tubular hollow. Then the hollow is cooled to room temperature in step 103. In a penultimate step 104, the hollow is cold pilger milled into a tube. In a last step 105, the tube is cold drawn through a drawing dye.

[0069] For purposes of the original disclosure, it is noted that all features become apparent for a person skilled in the art from the present description, the figures and the claims even if they have only been described with reference to particular further features and can be combined either on their own or in arbitrary combinations with other features or groups of features disclosed herein as far as such combinations are not explicitly excluded or technical facts exclude such combinations or make them useless. An extensive, explicit description of each possible combination of features has only been omitted in order to provide a short and readable description.

[0070] While the disclosure has been shown in detail in the figures and the above description, this description is only an example and is not considered to restrict the scope of protection as it is defined by the claims. The disclosure is not restricted to the disclosed embodiments.

[0071] Modifications to the disclosed embodiments are apparent for a person skilled in the art from the drawings, the description and the attached claims. In the claims, the word comprising does not exclude other elements or steps and the undefined article a does not exclude a plurality. The mere fact that some features have been claimed in different claims does not exclude their combination. Reference numbers in the claims are not considered to restrict the scope of protection.

REFERENCE NUMERALS

[0072] 1 Aircraft [0073] 2 tube [0074] 3 fuel reservoir [0075] 4 turbine [0076] 5 hydraulic pump [0077] 6 hydraulic actuator [0078] 100 providing a melt of an austenitic stainless steel [0079] 101 extruding a billet from the melt [0080] 102 hot rolling of the billet into a tubular hollow [0081] 103 cooling step [0082] 104 cold pilger milling step [0083] 105 cold drawing step