Hot stretch straightening of high strength age hardened metallic form and straightened age hardened metallic form

• US 8,834,653 B2
• Filed: 07/02/2013
• Issued: 09/16/2014
• Est. Priority Date: 07/28/2010
• Status: Active Grant

• Current Assignee: ATI Properties Incorporated (Allegheny Technologies Incorporated)
• Original Assignee: ATI Properties Incorporated (Allegheny Technologies Incorporated)
• Inventors: Bryan, David J.
• Primary Examiner(s): Roe, Jessee
• Application Number:
  US13/933,222
• Publication Number:
  US 20130291616A1
• Time in Patent Office: 441 Days
• Field of Search: 148/645, 148/646, 148/670
• US Class Current: 148/645
• CPC Class Codes: B21D 3/12 by stretching with or without twisting by twisting only B21D11/14
• CPC Class Codes: C22F 1/183 of titanium or alloys based thereon
• CPC Class Codes: Y10T 428/12299 Workpiece mimicking finished stock having nonrectangular or noncircular cross section

Abstract

A method for straightening an age hardened metallic form includes heating an age hardened metallic form comprising one of a titanium alloy, a nickel alloy, an aluminum alloy, and a ferrous alloy to a straightening temperature of at least 25° F. below the age hardening temperature, and applying an elongation tensile stress for a time sufficient to elongate and straighten the form. The elongation tensile stress is at least 20% of the yield stress and not equal to or greater than the yield stress at the straightening temperature. The straightened form deviates from straight by no greater than 0.125 inch over any 5 foot length or shorter length. The straightened form is cooled while simultaneously applying a cooling tensile stress that balances the thermal cooling stress in the metallic form to thereby maintain a deviation from straight of no greater than 0.125 inch over any 5 foot length or shorter length.

Claims

1. A method for straightening an age hardened metallic form selected from one of a metal and a metal alloy, comprising:

heating an age hardened metallic form to a straightening temperature,

wherein the straightening temperature is in a straightening temperature range from 0.3 of a melting temperature in kelvin (0.3 T_m) of the age hardened metallic form to 25°

F. (13.9°

C.) below an aging temperature used to harden the age hardened metallic form;

applying an elongation tensile stress to the age hardened metallic form for a time sufficient to elongate and straighten the age hardened metallic form to provide a straightened age hardened metallic form,

wherein the straightened age hardened metallic form deviates from straight by no greater than 0.125 inch (3.175 mm) over any 5 foot length (152.4 cm) or shorter length; and

cooling the straightened age hardened metallic form while simultaneously applying a cooling tensile stress to the straightened age hardened metallic form,

wherein the cooling tensile stress is sufficient to balance a thermal cooling stress in the alloy and maintain a deviation from straight of no greater than 0.125 inch (3.175 mm) over any 5 foot length (152.4 cm) or shorter length of the straightened age hardened metallic form.

2. The method of claim 1, wherein the elongation stress is at least 20% of a yield stress and not equal to or greater than the yield stress of the age hardened metallic form at the straightening temperature.

3. The method of claim 1, wherein the straightened age hardened metallic form deviates from straight by no greater than 0.094 inch (2.388 mm) over any 5 foot length (152.4 cm) or shorter length of the straightened age hardened metallic form.

4. The method of claim 3, wherein the cooling stress is sufficient to balance a thermal cooling stress in the alloy and maintain a deviation from straight of no greater than 0.094 inch (2.388 mm) over any 5 foot length (152.4 cm) or shorter length of the straightened age hardened metallic form.

5. The method of claim 1, wherein the straightened age hardened metallic form deviates from straight by no greater than 0.25 inch (6.35 mm) over any 10 foot (304.8 cm) length of the straightened age hardened metallic form.

6. The method of claim 1, wherein the age hardened metallic form comprises a material selected from the group consisting of a titanium alloy, a nickel alloy, an aluminum alloy, and a ferrous alloy.

7. The method of claim 1, wherein the age hardened metallic form is a form selected from the group consisting of a billet, a bloom, a round bar, a square bar, an extrusion, a tube, a pipe, a slab, a sheet, and a plate.

8. The method of claim 1, wherein the straightening temperature is in a range from 200°

F. (111.1°

C.) below the age hardening temperature used to harden the age hardened metallic form up to 25°

F. (13.9°

C.) below the age hardening temperature used to harden the age hardened metallic form.

9. A method for straightening an age hardened metallic form selected from one of a metal and a metal alloy, comprising:

heating an age hardened metallic form to a straightening temperature,

wherein the straightening temperature is in a straightening temperature range from 0.3 of a melting temperature in kelvin (0.3 T_m) of the age hardened metallic form to 25°

F. (13.9°

C.) below an aging temperature used to harden the age hardened metallic form;

applying an elongation tensile stress to the age hardened metallic form for a time sufficient to elongate and straighten the age hardened metallic form to provide a straightened age hardened metallic form,

wherein the elongation stress is at least 20% of a yield stress and not equal to or greater than the yield stress of the age hardened metallic form at the straightening temperature; and

wherein the straightened age hardened metallic form deviates from straight by no greater than 0.125 inch (3.175 mm) over any 5 foot length (152.4 cm) or shorter length; and

cooling the straightened age hardened metallic form while simultaneously applying a cooling tensile stress to the straightened age hardened metallic form,

wherein the cooling tensile stress is sufficient to balance a thermal cooling stress in the alloy and maintain a deviation from straight of no greater than 0.125 inch (3.175 mm) over any 5 foot length (152.4 cm) or shorter length of the straightened age hardened metallic form.

10. The method of claim 9, wherein the straightened age hardened metallic form deviates from straight by no greater than 0.094 inch (2.388 mm) over any 5 foot length (152.4 cm) or shorter length of the straightened age hardened metallic form.

11. The method of claim 10, wherein the cooling stress is sufficient to balance a thermal cooling stress in the alloy and maintain a deviation from straight of no greater than 0.094 inch (2.388 mm) over any 5 foot length (152.4 cm) or shorter length of the straightened age hardened metallic form.

12. The method of claim 9, wherein the straightened age hardened metallic form deviates from straight by no greater than 0.25 inch (6.35 mm) over any 10 foot (304.8 cm) length of the straightened age hardened metallic form.

13. The method of claim 9, wherein the age hardened metallic form comprises a material selected from the group consisting of a titanium alloy, a nickel alloy, an aluminum alloy, and a ferrous alloy.

14. The method of claim 9, wherein the age hardened metallic form is a form selected from the group consisting of a billet, a bloom, a round bar, a square bar, an extrusion, a tube, a pipe, a slab, a sheet, and a plate.

15. The method of claim 9, wherein the straightening temperature is in a range from 200°

F. (111.1°

C.) below the age hardening temperature used to harden the age hardened metallic form up to 25°

F. (13.9°

C.) below the age hardening temperature used to harden the age hardened metallic form.