JP2016503126A5 - - Google Patents

Description

Workpiece with sufficient strain rate to heat the inner region of the workpiece adiabatically in the direction of the first orthogonal A axis of the workpiece, the main pressure in the work piece forging temperature in the workpiece forging temperature range Press forged to spacer height. As used herein, the primary pressure spacer height (major reduction spacer height) is the distance corresponding to the desired final forging dimensions for each orthogonal axis of the workpiece.

Workpiece in the direction of the second orthogonal B axis of the work piece in the first rough beating pressure, workpiece forging temperature in the first rough beating pressure spacer height in the workpiece forging temperature range (blocking reduction spacer height ) Is press forged. First rough beating pressure is a workpiece, is applied in order to return substantially to forging before the shape of the workpiece. Although the strain rate under the first roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, in a non-limiting embodiment, the total strain that occurs under the first roughing pressure is Adiabatic heating during the first roughing pressure may not occur because it may not be sufficient to heat the workpiece significantly adiabatically. The first roughing reduction spacer height is greater than the main reduction spacer height.

Workpiece is pressed forged in a third direction orthogonal axis C of the workpiece in the second rough beating pressure, the second rough beating pressure spacer height in the workpiece forging temperature in the workpiece forging temperature range . Second rough beating pressure is a workpiece, is applied in order to return substantially to forging before the shape of the workpiece. The strain rate under the second roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, but in a non-limiting embodiment, the total strain that occurs under the second roughing pressure is order to heat the workpiece to significantly adiabatically may not be sufficient, adiabatic heating during the second rough beating pressure may also not occur. The second roughing reduction spacer height is larger than the main reduction spacer height.

Workpiece with sufficient strain rate to heat the inner region of the workpiece adiabatically in the direction of the second orthogonal B-axis of the workpiece, the main pressure in the work piece forging temperature in the workpiece forging temperature range Press forged to spacer height.

Workpiece is pressed forged in a third direction orthogonal axis C of the workpiece in the first rough beating pressure, the first rough beating pressure spacer height in the workpiece forging temperature in the workpiece forging temperature range . First rough beating pressure is a workpiece, is applied in order to return substantially to forging before the shape of the workpiece. Although the strain rate under the first roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, in a non-limiting embodiment, the total strain that occurs under the first roughing pressure is Adiabatic heating during the first roughing pressure may not occur because it may not be sufficient to heat the workpiece significantly adiabatically. The first roughing reduction spacer height is greater than the main reduction spacer height.

Workpiece is pressed forged in a first direction orthogonal A axis of the workpiece in the second rough beating pressure, the second rough beating pressure spacer height in the workpiece forging temperature in the workpiece forging temperature range . Second rough beating pressure is a workpiece, is applied in order to return substantially to forging before the shape of the workpiece. The strain rate under the second roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, but in a non-limiting embodiment, the total strain that occurs under the second roughing pressure is order to heat the workpiece to significantly adiabatically may not be sufficient, adiabatic heating during the second rough beating pressure may also not occur. The second roughing reduction spacer height is larger than the main reduction spacer height.

The workpiece has a strain forging temperature within the workpiece forging temperature range in the direction of the third orthogonal C-axis of the workpiece under main pressure at a strain rate sufficient to adiabatically heat the inner region of the workpiece. And press forged to the height of the main reduction spacer.

Workpiece is press-forged in the first direction orthogonal A axis of the workpiece in the first rough beating pressure, the first rough beating pressure spacer height in the workpiece forging temperature in the workpiece forging temperature range . First rough beating pressure is a workpiece, is applied in order to return substantially to forging before the shape of the workpiece. Although the strain rate under the first roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, in a non-limiting embodiment, the total strain that occurs under the first roughing pressure is Adiabatic heating during the first roughing pressure may not occur because it may not be sufficient to heat the workpiece significantly adiabatically. The first roughing reduction spacer height is greater than the main reduction spacer height.

Workpiece is pressed forged in the direction of the second orthogonal B-axis of the workpiece in the second rough beating pressure, the second rough beating pressure spacer height in the workpiece forging temperature in the workpiece forging temperature range . Second rough beating pressure is a workpiece, is applied in order to return substantially to forging before the shape of the workpiece. The strain rate under the second roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, but in a non-limiting embodiment, the total strain that occurs under the second roughing pressure is order to heat the workpiece to significantly adiabatically may not be sufficient, adiabatic heating during the second rough beating pressure may also not occur. The second roughing reduction spacer height is larger than the main reduction spacer height.

Plotted calculated predictions of volume fraction of equilibrium alpha phase present in Ti-6-4, Ti-6-2-4-6, and Ti-6-2-4-2 alloys as a function of temperature It is a graph to do. 2 is a flow chart listing the steps of a non-limiting embodiment of a method for processing a titanium alloy according to the present disclosure. FIG. 3 is a schematic diagram of aspects of a non-limiting embodiment of a high strain rate multi-axis forging method that uses thermal management to treat a titanium alloy for particle size refinement; c), and 3 (e) represent non-limiting press forging steps, and FIGS. 3 (b), 3 (d), and 3 (f) are optional non-limiting aspects of the present disclosure. Represents limited cooling and heating steps. 1 is a schematic diagram of an embodiment of a prior art low strain rate multi-axis forging technique that is known to be used to refine the grain size of a small sample. FIG. FIG. 6 is a flow chart listing the steps of a non-limiting embodiment of a method for processing a titanium alloy according to the present disclosure, including primary orthogonal reduction to the final desired dimension of the workpiece and first and second roughing reductions. . Same as above Same as above 2 is a temperature-time thermomechanical process diagram for a non-limiting embodiment of a high strain rate multi-axis forging method according to the present disclosure. FIG. FIG. 2 is a temperature-time thermomechanical process diagram for a non-limiting embodiment of a multi-temperature high strain rate multi-axis forging method according to the present disclosure. FIG. 2 is a temperature-time thermomechanical process diagram for a non-limiting embodiment of a β transus high strain rate multi-axis forging method according to the present disclosure. 1 is a schematic diagram of aspects of a non-limiting embodiment of multiple upsetting and stretching methods for particle size refinement according to the present disclosure. FIG. 2 is a flow chart listing the steps of a non-limiting embodiment of a method for multiple upsetting and stretching processes of a titanium alloy to refine grain size according to the present disclosure. 2 is a photomicrograph of the microstructure of a commercially forged and processed Ti-6-2-4-2 alloy. 2 is a micrograph of the microstructure of a Ti-6-2-4-2 alloy processed by a thermally controlled high strain MAF embodiment described in Example 1 of the present disclosure. FIG. 3 is a photomicrograph depicting the microstructure of a commercially forged and processed Ti-6-2-4-6 alloy. 2 is a photomicrograph of the microstructure of a Ti-6-2-4-6 alloy processed by the thermally controlled high strain MAF embodiment described in Example 2 of the present disclosure. 4 is a micrograph of the microstructure of a Ti-6-2-4-6 alloy processed by the thermally controlled high strain MAF embodiment described in Example 3 of the present disclosure. In a micrograph of the microstructure of a Ti-6-2-4-2 alloy processed by a thermally controlled high strain MAF embodiment applying equal strain on each axis, described in Example 4 of the present disclosure. is there. Ti-6 treated by a thermally managed high strain MAF embodiment that uses roughing reduction and minimizes workpiece expansion after each primary reduction , as described in Example 5 of the present disclosure. It is a microscope picture of the microstructure of a 2-4-2 alloy. In a micrograph of the microstructure of the central region of a Ti-6-2-4-2 alloy processed by a thermally controlled high strain MAF embodiment utilized through β-transus MAF described in Example 6 of the present disclosure is there. In a micrograph of the microstructure of the surface area of a Ti-6-2-4-2 alloy processed by a thermally controlled high strain MAF embodiment utilized through β-transus MAF described in Example 6 of the present disclosure is there.

Aspects of the present disclosure relate to a non-limiting embodiment of a multi-axis forging process for titanium alloys that includes the application of high strain rates during the forging step to refine the grain size. These method embodiments are generally referred to in this disclosure as “high strain rate multi-axis forging” or “high strain rate MAF”. As used herein, the terms “ rolling ” and “hit” interchangeably refer to individual press forging steps in which a workpiece is forged between die surfaces. As used herein, the phrase “spacer height” refers to the dimension or thickness of a workpiece measured along one orthogonal axis after reduction along that axis. For example, after pressing forging pressure to the spacer height 4.0 inches along a particular axis, the thickness of the press-forged workpiece is measured along its axis becomes about 4.0 inches. The concept and use of spacer height is well known to those skilled in the art of press forging and need not be further described herein.

In a non-limiting embodiment, during press forging (28), the workpiece 24 is plastically deformed to a height in the range of 20% to 50% or reduction in another dimension, i.e., the dimension is within this range. Reduced to In another non-limiting embodiment, during press forging (28), the workpiece 24 is plastically deformed to a height in the range of 30% to 40% or reduction in another dimension.

A known ultra-low strain rate (0.001 sec- ¹ or less) multi-axis forging process is schematically depicted in FIG. In general, the multi-axis forging aspect is that after every three strokes (ie, “3 hits”) with a forging device (eg, may be free forging), the shape and size of the workpiece is the 3 hit cycle. Is approaching the shape and size of the workpiece just before the first hit. For example, a cube-shaped workpiece with a side of 5 inches is first forged with a first “hit” in the direction of the “a” axis, rotated 90 °, and with a second hit in the direction of the orthogonal “b” axis. After forging and then rotating 90 ° and forging with a third hit in the direction of the orthogonal “c” axis, the workpiece will resemble the starting cube and will contain approximately 5 inches of sides. In other words, the three-hit cycle transformed the cube in three steps along the cube's three orthogonal axes, but the result of repositioning the workpiece between individual hits and the selection under reduction during each hit. The overall result of the three forging deformations is to return the cube to its original shape and size.

In another non-limiting embodiment according to the present disclosure, a first press forging step (28) shown in FIG. 2 (a), also referred to herein as a “first hit”, comprises While the temperature is within the workpiece forging temperature range, the workpiece may be press forged to a predetermined spacer height with the top side down. As used herein, the term “spacer height” refers to the dimensions of the workpiece upon completion of a particular press forging reduction . For example, for a 5 inch spacer height, the workpiece is forged to a size of about 5 inches. In certain non-limiting embodiments of the disclosed method, the spacer height is, for example, 5 inches. In another non-limiting embodiment, the spacer height is 3.25 inches. Other spacer heights, such as less than 5 inches, about 4 inches, about 3 inches, more than 5 inches, or 5 inches up to 30 inches are within the scope of embodiments herein, but are within the scope of the present disclosure. Should not be considered as limiting. The spacer height is the capability of the forging furnace, and optionally the capability of the thermal management system according to a non-limiting embodiment of the present disclosure to maintain the workpiece at the workpiece forging temperature, as seen herein. Limited only by. Spacer heights of less than 3 inches are also within the scope of the embodiments disclosed herein, and such relatively small spacer heights are limited only by the desired properties of the final product. For example, the use of a spacer height of about 30 inches in the method according to the present disclosure can result in billet-sized (eg, 30 inches on a side) cubic shaped titanium having a fine, fine, or ultra fine particle size. Allows production of alloy forms. Conventional alloy billet-sized cubic shapes are used, for example, as workpieces that are forged into disks, rings, and case parts for aircraft or land turbines.

The predetermined spacer height to be used in various non-limiting embodiments of the method according to the present disclosure can be determined by one of ordinary skill in the art without undue experimentation in light of the present disclosure. The particular spacer height can be determined by one skilled in the art without undue experimentation. The specific spacer height depends on the sensitivity of the specific alloy to cracking during forging. Alloys that are more susceptible to cracking will require a larger spacer height, i.e., less deformation per hit to prevent cracking. Limitation of adiabatic heating also workpiece temperature, because should not exceed T _beta alloys in at least the last cycle of hits, must be considered in selecting a spacer height. In addition, forging press capacity limitations need to be considered when selecting the spacer height. For example, during the pressing of a 4 inch wide cubic workpiece, the cross-sectional area increases during the pressing step. Thus, the total load required to continue to deform the workpiece at the required strain rate increases. The load cannot be increased beyond the capacity of the forging press. Also, the workpiece geometry needs to be considered when selecting the spacer height. Large deformations can result in workpiece expansion. An excessively large reduction can result in relative flattening of the workpiece, so that subsequent forging hits in different orthogonal axis directions can result in bending of the workpiece.

As shown in FIG. 3 (c), aspects of a non-limiting embodiment of the multi-axis forging method (26) according to the present disclosure include adiabatically heating the workpiece 24 or at least an interior region of the workpiece 24, Using a strain rate sufficient to plastically deform the workpiece 24, the workpiece 24 is moved in the direction of the second orthogonal axis 48 of the workpiece 24 (B) to a workpiece forging within the workpiece forging temperature range. Including press forging at temperature (step 46). In a non-limiting embodiment, during press forging (46), the workpiece 24 is deformed to a plastic deformation under a 20% to 50% reduction in height or another dimension. In another non-limiting embodiment, during press forging (46), workpiece 24 is deformed to a plastic deformation of 30% to 40% reduction in height or another dimension. In a non-limiting embodiment, the workpiece 24 may be press forged in the direction of the second orthogonal axis 48 to the same spacer height used in the first press forging step (28) ( 46). In another non-limiting embodiment, the workpiece 24 may be press forged in the direction of the second orthogonal axis 48 to a different spacer height than that used in the first press forging step (28). Good. In another non-limiting embodiment, the interior region (not shown) of the workpiece 24 is adiabatically heated during the press forging step (46) to the same temperature as the first press forging step (28). In other non-limiting embodiments, the high strain rate used for press forging (46) is within the same strain rate range disclosed for the first press forging step (28).

As shown in FIG. 3 (e), aspects of an embodiment of the multi-axis forging method (26) according to the present disclosure may heat the workpiece 24 adiabatically or at least adiabatic the interior region of the workpiece. Using a ram speed and strain rate sufficient to heat and plastically deform the workpiece 24, the workpiece 24 is placed in the direction of the third orthogonal axis 58 of the workpiece 24 (C), the workpiece forging temperature. Including press forging at a workpiece forging temperature within the range (step 56). In a non-limiting embodiment, the workpiece 24 is deformed to a plastic deformation under 20% to 50% reduction in height or another dimension during press forging (56). In another non-limiting embodiment, during press forging (56), the workpiece is deformed to a plastic deformation under a 30% to 40% reduction in height or another dimension. In a non-limiting embodiment, the workpiece 24 has a third orthogonal axis at the same spacer height used in the first press forging step (28) and / or the second forging step (46). It may be press forged in the direction of 58 (56). In another non-limiting embodiment, the workpiece 24 may be press forged in the direction of the third orthogonal axis 58 to a different spacer height than that used in the first press forging step (28). Good. In another non-limiting embodiment according to the present disclosure, the interior region (not shown) of the workpiece 24 is adiabatically heated to the same temperature as the first press forging step (28) during the press forging step (56). Is done. In other non-limiting embodiments, the high strain rate used for press forging (56) is within the same strain rate range disclosed for the first press forging step (28).

異なる圧下は、異なるスペーサ高さを提供する鍛造装置内のスペーサを使用することによって、または当業者に既知である任意の代替的な方法によって実施することができる。 In a non-limiting embodiment according to the present disclosure, different reductions are used for A-axis hits, B-axis hits, and C-axis hits to provide equalized strain in all directions. Applying a high strain rate MAF to introduce equalized strain in all directions results in fewer cracks in the workpiece and more equiaxed alpha grain structure for the workpiece. For example, unequalized strain can be introduced into a cube workpiece by starting with a 4 inch cube forged at a high strain rate to a height of 3.0 inches on the A-axis. This reduction on the A axis causes the workpiece to expand along the B and C axes. If the second reduction in the B-axis direction reduces the B-axis dimension to 3.0 inches, more strain is introduced into the workpiece on the B-axis than on the A-axis. Similarly, subsequent hits in the C-axis direction that reduce the C-axis dimension to 3.0 inches will introduce more strain on the workpiece on the C-axis than on the A-axis or B-axis. . As another example, to introduce equalized strain in all orthogonal directions, a 4 inch cube workpiece is forged (“hit”) on the A axis to a height of 3.0 inches, 90 Rotated in degrees and hit on the B-axis to a height of 3.5 inches, then rotated 90 degrees and hit on the C-axis to a height of 4.0 inches. This latter sequence results in a cube that is about 4 inches on a side and contains strain equalized in each orthogonal direction of the cube. A general formula for calculating the reduction on each orthogonal axis of a cubic workpiece in high strain rate MAF is provided in Equation 1.
Equation 1: Strain = -ln (spacer height / starting height)
A general formula for calculating total strain is provided by Equation 2:

Different reductions can be performed by using spacers in the forging device that provide different spacer heights or by any alternative method known to those skilled in the art.

Referring now to FIG. 5 and considering FIG. 3, in a non-limiting embodiment according to the present disclosure, the process (70) for the production of ultrafine titanium alloy comprises β annealing the titanium alloy workpiece. (71), cooling the β-annealed workpiece 24 to a temperature below the β transus temperature of the titanium alloy of the workpiece (72), the workpiece 24 being in the α + β phase region of the titanium alloy of the workpiece Heating the workpiece to a workpiece forging temperature within a piece forging temperature range (73) and subjecting the workpiece to a high strain rate MAF (74), wherein the high strain rate MAF (74) is a workpiece to a different spacer height. Includes press forging reduction on the orthogonal axis of the piece. In a non-limiting embodiment of multi-axis forging (74) according to the present disclosure, the workpiece 24 is press-forged (75) to the primary reduction spacer height on the first orthogonal axis (A-axis). As used herein, the phrase “press forged to the primary reduction spacer height” means that the workpiece is along the orthogonal axis to the desired final dimension of the workpiece along the particular orthogonal axis. Refers to press forging. Thus, the term “primary reduction spacer height” is defined as the spacer height used to obtain the final dimension of the workpiece along each orthogonal axis. All press forging steps to the main reduction spacer height should occur using a strain rate sufficient to adiabatically heat the interior area of the workpiece.

After the workpiece 24 is press forged (75) to the primary reduction spacer height in the direction of the first orthogonal A-axis, as shown in FIG. 3 (a), the process (70) optionally includes thermal insulation of the workpiece. Further cooling the internally heated interior region (not shown) to a temperature at or near the workpiece forging temperature (step 76 shown in FIG. 3 (b)). The internal zone cooling time may range, for example, from 5 seconds to 120 seconds, 10 seconds to 60 seconds, or 5 seconds to a maximum of 5 minutes, and the required cooling time depends on the size, shape of the workpiece It will be appreciated by those skilled in the art that it depends on the composition and the characteristics of the environment surrounding the workpiece.

In a non-limiting embodiment, after press forging (75) to the main reduction spacer height on the A-axis (see FIG. 3), sometimes referred to herein as reduction “ A ”, and also applied when, after optional cooling of tolerance (76) and heating (77) step, subsequent press forging to rough beating pressure spacer height which may include an optional heating and cooling step, the workpiece " Applied on the B and C axes to “square-up”. The phrase "press forging ... rough beating pressure spacer height" is otherwise first rough beating pressure spacer height (78, (87), (96)) by press forging , And a second roughing reduction spacer ((81), (90), (99)), referred to herein as press forging, and any surface after press forging to the main reduction spacer height. Defined as a press forging step used to reduce or “square” the expansion that occurs near the center. Expansion at or near the center of any face results in a triaxial stress state being introduced into that face, which can lead to a crack in the workpiece. The step of press forging to the first reduction spacer height and the step of press forging to the second rough reduction spacer height are referred to herein as the first roughing reduction , the second roughing reduction , or simply the roughing reduction . also referred to as out pressure, the surface of the workpiece, as is flat or substantially flat before the next press forging to the main pressure spacer height along the orthogonal axes, used to deform the expanded surface It is done. Roughing reduction includes press forging to a spacer height greater than the spacer height used in each step of press forging to the primary reduction spacer height. The strain rates under all first and second roughing pressures disclosed herein may be sufficient to adiabatically heat the interior region of the workpiece, but in a non-limiting embodiment, total distortion occurs in the first and second rough beating pressure, because there may not be sufficient to heat the workpiece to significantly adiabatically, first rough beating pressure and the second insulation rough beating in pressure Heating may not occur. Since the roughing reduction is performed at a spacer height larger than that used in press forging to the main reduction spacer height, the strain applied to the workpiece under roughing pressure insulates the internal area of the workpiece. May not be sufficient to heat up. As can be seen, the incorporation of the first and second roughing pressures in the high strain rate MAF process is, in a non-limiting embodiment, of at least one cycle consisting of A— B—C— B— C—A— C . Resulting in a forging sequence, wherein A , B , and C include press forging to the primary reduction spacer height, and B, C, C, and A to the first or second rough reduction spacer height the method comprising pressing forging, or in another non-limiting embodiment, resulted in a -B-C- B -C-A- C consisting -A-B at least one cycle sequence of forging, a, B and C include press forging to the primary reduction spacer height, and B, C, C, A, A and B are press forging to the first or second rough reduction spacer height. Including Mu

Referring again to FIGS. 3 and 5, in a non-limiting embodiment, after the press forging step (75) ( A reduction ) to the primary reduction spacer height on the first orthogonal axis, and also when applied: acceptable optional cooling (76) and heating (77) after step, as described above, the workpiece is pressed forging the first rough beating pressure spacer height on B-axis (78). Although the strain rate under the first roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, in a non-limiting embodiment, the strain that occurs under the first roughing pressure is Adiabatic heating during the first roughing pressure may not occur because it may not be sufficient to heat the pieces significantly adiabatically. Optionally, the adiabatically heated inner region of the workpiece is cooled to a temperature at or near the workpiece forging temperature (79), while the outer surface area of the workpiece is at or near the workpiece forging temperature. Heat to near temperature (80). All cooling times and heating methods for A reduction (75) disclosed above and in other embodiments of the present disclosure allow steps (79) and (80) and the internal region of the workpiece to cool, Applicable to all optional subsequent steps of heating the outer surface area.

The workpiece is then press forged on the C-axis to a second roughing reduction spacer height that is greater than the main reduction spacer height (81). The first and second roughing reductions are applied to substantially return the workpiece to its pre-forged shape. The strain rate under the second roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, but in a non-limiting embodiment, the strain that occurs under the second roughing pressure is Adiabatic heating during the second roughing pressure may not occur because it may not be sufficient to heat the pieces significantly adiabatically. Optionally, the adiabatically heated inner region of the workpiece is cooled to a temperature at or near the workpiece forging temperature (82), while the outer surface area of the workpiece is at or near the workpiece forging temperature. Heated to near temperature (83).

The workpiece is then press forged to the main reduction spacer height in the direction of the second orthogonal axis, or B-axis (84). Press forging (84) to the main reduction spacer height on the B-axis is referred to herein as B reduction . After B reduction (84), optionally, the adiabatically heated inner region of the workpiece is cooled to a temperature at or near the workpiece forging temperature (85), while the outer surface region of the workpiece is It is heated to a temperature at or near the piece forging temperature (86).

Workpiece then on the C-axis, are pressed forging the first rough beating pressure spacer height greater than the main pressure spacer height (87). Although the strain rate under the first roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, in a non-limiting embodiment, the strain that occurs under the first roughing pressure is Adiabatic heating during the first roughing pressure may not occur because it may not be sufficient to heat the pieces significantly adiabatically. Optionally, the workpiece is cooled to a temperature at or near the workpiece forging temperature (88), while the outer surface area of the workpiece is heated to a temperature at or near the workpiece forging temperature (89).

The workpiece is then press forged (90) on the A-axis to a second roughing reduction spacer height that is greater than the main reduction spacer height. The first and second roughing reductions are applied to substantially return the workpiece to its pre-forged shape. The strain rate under the second roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, but in a non-limiting embodiment, the strain that occurs under the second roughing pressure is Adiabatic heating during the second roughing pressure may not occur because it may not be sufficient to heat the pieces significantly adiabatically. Optionally, the adiabatically heated inner region of the workpiece is cooled to a temperature at or near the workpiece forging temperature (91), while the outer surface area of the workpiece is at or near the workpiece forging temperature. Heated to near temperature (92).

The workpiece is then press forged to the main reduction spacer height (93) in the direction of the third orthogonal axis, or C-axis. Press forging (93) to the main reduction spacer height on the C-axis is referred to herein as C reduction . After C reduction (93), optionally, the adiabatically heated inner region of the workpiece is cooled to a temperature at or near the workpiece forging temperature (94), while the outer surface region of the workpiece is It is heated to the temperature at or near the piece forging temperature (95).

The workpiece is then press forged (96) on the A-axis to a first rough reduction spacer height that is greater than the primary reduction spacer height. Although the strain rate under the first roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, in a non-limiting embodiment, the strain that occurs under the first roughing pressure is Adiabatic heating during the first roughing pressure may not occur because it may not be sufficient to heat the pieces significantly adiabatically. Optionally, the adiabatically heated interior region of the workpiece is cooled to a temperature at or near the workpiece forging temperature (97), while the outer surface area of the workpiece is at or near the workpiece forging temperature. Heat to near temperature (98).

Workpiece then on the B-axis, are pressed forging the second rough beating pressure spacer height greater than the main pressure spacer height (99). The first and second roughing reductions are applied to substantially return the workpiece to its pre-forged shape. The strain rate under the second roughing pressure may be sufficient to adiabatically heat the internal region of the workpiece, but in a non-limiting embodiment, the strain that occurs under the second roughing pressure is Adiabatic heating during the second roughing pressure may not occur because it may not be sufficient to heat the pieces significantly adiabatically. Optionally, the adiabatically heated inner region of the workpiece is cooled to a temperature at or near the workpiece forging temperature (100), while the outer surface region of the workpiece is at or near the workpiece forging temperature. Heated to near temperature (101).

The process described above includes a repeated sequence of press forging to the primary reduction spacer height and then press forging to the first and second roughing reduction spacer heights. The forging sequence representing one total MAF cycle as disclosed in the non-limiting embodiment above can be expressed as A- B-C- B- C-A- C- A-B, Middle, underlined bold reduction (hit) is press forging to the main reduction spacer height, and underlined or non-bold reduction is the first or second roughing reduction . Including a press forging in the main pressure spacer height and the first and second rough beating pressure, all of the press forging pressure of MAF process according to the present disclosure is sufficient to heat the inner region of the workpiece adiabatically High strain rate, such as, but not limited to, a strain rate in the range of 0.2 sec- ^{1 to} 0.8 sec- ¹ , or 0.2 sec- ^{1 to} 0.4 sec- ^1. It will be understood that It is also understood that adiabatic heating may not occur substantially during the first and second roughing pressures due to the lower degree of deformation at these reductions compared to the primary reduction. Let's go. Also, as an optional step, intermediate continuous press forging reduction causes the adiabatically heated inner region of the workpiece to cool to or near the workpiece forging temperature, and the outer surface of the workpiece is It will also be understood that the thermal management system disclosed in the document is utilized to heat to or near the workpiece forging temperature. It is believed that these optional steps may be more beneficial when the method is used for larger size workpieces. Furthermore, embodiments of A -B-C- B -C-A- sequence of forging C -A-B to be described herein, at least 1.0 or at least 1.0 up to 3.5, It will be understood that it may be repeated in whole or in part until a total strain within a range of less than is achieved in the workpiece.

Expansion in the workpiece results from a combination of surface die lock and the presence of a higher temperature material near the center of the workpiece. As the expansion increases, the center of each face is gradually subjected to a triaxial load that can begin to crack. In the sequence A-B-C- B- C-A- C- A-B, the use of roughing reduction between each press forging to the main reduction spacer height reduces the tendency of crack formation in the workpiece. . In a non-limiting embodiment, when the workpiece is in the form of a cube, a first rough beating pressure spacer height for the first rough beating pressure is 40 to 60% larger spacer than the main pressure spacer height It may be relative to height. In a non-limiting embodiment, when the workpiece is in the form of a cube, a second rough beating pressure spacer height for the second rough beating pressure and 15-30% greater spacer than the main pressure spacer height It may be relative to height. In another non-limiting embodiment, the first rough beating pressure spacer height may be substantially equal to the second rough beating pressure spacer height.

FIG. 6 is a temperature-time thermomechanical process diagram for a non-limiting method of plastically deforming a workpiece above the β transus temperature and directly cooling to the workpiece forging temperature. In FIG. 6, a non-limiting method 200 can be used to produce a workpiece that includes a titanium alloy that has a slower α precipitation and growth rate than that of a Ti-6-4 alloy, for example, β that exceeds the β transus temperature 206 of the titanium alloy. Heating 202 to an annealing temperature 204 and holding or “ soaking ” the workpiece at a β annealing temperature 204 to form a full β titanium phase microstructure in the workpiece. In a non-limiting embodiment according to the present disclosure, after soaking 208, the workpiece may be plastically deformed 210. In a non-limiting embodiment, the plastic deformation 210 includes upset forging. In a non-limiting embodiment, the plastic deformation 210 includes upset forging to a true strain of 0.3. In a non-limiting embodiment, plastic deformation 210 includes thermally controlled high strain rate multi-axis forging (not shown in FIG. 6) at the β annealing temperature.

In FIG. 7, a non-limiting method 230 in accordance with the present disclosure includes heating 232 the workpiece to a β annealing temperature 234 that exceeds the β transus temperature 236 of the alloy, and the workpiece into the entire titanium alloy workpiece. Holding or soaking at a β annealing temperature 234 to form a phase microstructure. After soaking 238, the workpiece may be plastically deformed 240. In a limited embodiment, plastic deformation 240 includes upset forging. In another non-limiting embodiment, the plastic deformation 240 includes upset forging to a strain of 0.3. In another non-limiting embodiment, workpiece plastic deformation 240 includes high strain multi-axis forging (not shown in FIG. 7) at the β annealing temperature.

FIG. 8 shows that a workpiece comprising a titanium alloy is plastically deformed above the β transus temperature, cooled to the workpiece forging temperature, and at the same time thermally strained into the workpiece according to a non-limiting embodiment of the present specification. FIG. 4 is a temperature-time thermomechanical process diagram of an embodiment of a non-limiting method according to the present disclosure for using speed multi-axis forging. In FIG. 8, a non-limiting method 260 using thermally controlled high strain rate multi-axis forging for grain refinement of titanium alloys, the workpiece is subjected to a β annealing temperature that exceeds the β transus temperature 266 of the titanium alloy. Heating 262 to 264 and holding or soaking 268 the workpiece at a β annealing temperature 264 so as to form a full β phase microstructure in the workpiece. After the workpiece is soaked 268 at the β annealing temperature, the workpiece is plastically deformed 270. In a non-limiting embodiment, the plastic deformation 270 can include thermally managed high strain rate multi-axis forging. In a non-limiting embodiment, the workpiece is repeatedly high strained using an optional thermal management system as disclosed herein as the workpiece cools through the beta transus temperature. 272 is multi-axis forged at speed. FIG. 8 shows three intermediate high strain rate multi-axis forging 272 steps, but it will be understood that there can be more or fewer intermediate high strain rate multi-axis forging 272 steps if desired. Let's go. The intermediate high strain rate multi-axis forging 272 step is intermediate between the initial high strain rate multi-axis forging step 270 at the soaking temperature and the final high strain rate multi-axis forging step in the α + β phase region 274 of the titanium alloy. FIG. 8 shows one final high strain rate multi-axis forging step in which the temperature of the workpiece remains entirely within the α + β phase region. It will be appreciated that it can be performed in the α + β phase region for grain refinement. According to a non-limiting embodiment of the present disclosure, the at least one final high strain rate multi-axis forging step is performed entirely at a temperature within the α + β phase region of the titanium alloy workpiece.

In a non-limiting embodiment of the MUD method, the plastic deformation of the workpiece in the beta phase region of the titanium alloy is to stretch the titanium alloy workpiece, upset forging, and multiaxial forging at a high strain rate. At least one of them. In another non-limiting embodiment, the plastic deformation of the workpiece in the beta phase region of the titanium alloy includes a plurality of upset and stretch forgings according to a non-limiting embodiment of the present disclosure, wherein the workpiece is forged. Cooling to or near the temperature includes air cooling. In yet another non-limiting embodiment, the plastic deformation of the workpiece in the beta phase region of the titanium alloy upsets the workpiece to 30-35% reduction in another dimension, such as height or length. Including doing.

Example 4 In a non-limiting embodiment according to the present disclosure, a 4.0 inch cube-shaped Ti-6-2-4-2 alloy workpiece is β annealed at 1950 ° F. (1066 ° C.) for 1 hour. Then it was air cooled. After cooling, the β-annealed cube-shaped workpiece was heated to a workpiece forging temperature of 1700 ° F. (926.7 ° C.) and held for 1 hour. Two high strain rate MAF cycles (2 sequences of 3 A-B-C hits, 6 hits in total) were used at 1700 ° F. (926.7 ° C.). The time between consecutive hits was about 15 seconds. The forging sequence was an A hit to a 3 inch stop; a B hit to a 3.5 inch stop; and a C hit to a 4.0 inch stop. This forging sequence provides equal strain on all three orthogonal axes for every three hit MAF sequence. The ram speed was 1 inch per second. There was no control of the strain rate in the press, but for a 4.0 inch cube, this ram speed results in the least strain rate during the press of 0.25 sec- ¹ . Total strain per cycle, as of the preceding Example, less than forged to 3.25 inches pressure in each direction.

Example 5 In a non-limiting embodiment according to the present disclosure, a 4.0 inch cube-shaped Ti-6-2-4-2 alloy workpiece is β annealed at 1950 ° F. (1066 ° C.) for 1 hour. Then it was air cooled. After cooling, the β-annealed cube-shaped workpiece was heated to a workpiece forging temperature of 1700 ° F. (926.7 ° C.) and held for 1 hour. Six press forgings ( A , B , C , A , B , C ) to the main reduction spacer height were applied to the cube-shaped workpiece using the MAF according to the present disclosure. In addition, during each press forge to a 3.25 inch primary reduction spacer height, first and second roughing reductions were performed on the other axis to “square” the workpiece. . The overall forging sequence used is as follows, and the underlined bold hit is press forging to the main reduction spacer height: A- B-C- B- C-A- C- A -B- A- B-C- B- C-A- C .

Example 6 In a non-limiting embodiment according to the present disclosure, a 4.0 inch cube-shaped Ti-6-2-4-2 alloy workpiece is β annealed at 1950 ° F. (1066 ° C.) for 1 hour. Then it was air cooled. In accordance with an embodiment of the present disclosure, a thermally controlled high strain rate MAF containing 6 hits (2 A-B-C MAF cycles) at 1900 ° C. on the workpiece with a 30 second hold between each hit. It carried out in. The ram speed was 1 inch per second. There was no control of the strain rate in the press, but for a 4.0 inch cube, this ram speed results in the least strain rate during the press of 0.25 sec- ¹ . A sequence of 6 hits with an intermediate hold is designed to heat the surface of the piece through the β transus temperature during MAF, which can therefore be referred to as high strain rate MAF through transus. This process results in surface structure refinement and crack minimization during subsequent forging. The workpiece was then heated at 1650 ° F. (898.9 ° C.), ie below the β transus temperature, for 1 hour. A MAF according to an embodiment of the present disclosure containing 6 hits (2 A-B-C MAF cycles) was applied to the workpiece with about 15 seconds between hits. The first three hits (hits during the first ABC ABC MAF cycle) were performed using a 3.5 inch spacer height and the second three hits (second AB- C's MAF cycle hit) was performed using a 3.25 inch spacer height. The workpiece was heated to 1650 ° F. between a 3.5 inch spacer hit and a 3.25 inch spacer hit and held for 30 minutes. The smaller reduction (ie, the larger spacer height) used for the first three hits was designed to prevent cracking, because the smaller reduction collapses the boundary structure, which can lead to cracking. . The workpiece was reheated to 1500 ° F. (815.6 ° C.) for 1 hour. Next, the MAF according to embodiments of the present disclosure, a 15 seconds between each hit was applied using three A-B-C hits to 3.25 inches pressure (one MAF cycles) . This sequence under heavier reduction is designed to add additional work to the non-boundary structure. The ram speed for all hits described in Example 6 was 1 inch per second.

Claims (44)

A method for reducing the particle size of a workpiece made of titanium or a titanium alloy ,
Β annealing the workpiece;
Cooling the beta annealed workpiece to a temperature below the beta transus temperature of the titanium alloy;
Including multi-axis forging the workpiece, the multi-axis forging,
A workpiece forging temperature within a workpiece forging temperature range in the direction of the first orthogonal axis of the workpiece at a strain rate sufficient to adiabatically heat the inner region of the workpiece. Press forging with,
The workpiece is forged within a workpiece forging temperature range in a direction of a second orthogonal axis of the workpiece at a strain rate sufficient to adiabatically heat an internal region of the workpiece. Press forging at temperature,
The workpiece is forged within the workpiece forging temperature range in a direction of a third orthogonal axis of the workpiece at a strain rate sufficient to adiabatically heat the inner region of the workpiece. Press forging at temperature,
Repeating at least one of the press forgings until a total true strain within the range of at least 1.0 and less than 3.5 is achieved in the workpiece. The method of claim 1, wherein the strain rate used during press forging is in the range of 0.2 sec- ^{1 to} 0.8 sec- ¹ . The method of claim 1, wherein the titanium alloy comprises one of an α + β titanium alloy and a metastable β titanium alloy. The method of claim 1, wherein the titanium alloy comprises an α + β titanium alloy. 5. The method of claim 3 or 4 , wherein the titanium alloy comprises at least one of a grain pinning element and a beta stabilizer effective to reduce alpha phase precipitation and growth rate. The titanium alloys are Ti-6Al-2Sn-4Zr-6Mo alloy (UNS R56260), Ti-6Al-2Sn-4Zr-2Mo-0.08Si alloy (UNS R54620), Ti-4Al-2.5V alloy (UNS R54250). ), A Ti-6Al-7Nb alloy (UNS R56700), and a Ti alloy selected from Ti-6Al-6V-2Sn alloy (UNS R56620). The method of claim 1, wherein cooling the β-annealed workpiece comprises cooling the workpiece to room temperature .   The method of claim 1, wherein cooling the β annealed workpiece comprises cooling the workpiece to a temperature at or near the workpiece forging temperature. Β annealing the workpiece is a temperature within the range of the β transus temperature of the titanium alloy up to a maximum of 300 ° F. (166.7 ° C.) above the β transus temperature of the titanium alloy. The method according to claim 1, comprising subjecting to β annealing . Wherein the workpiece is annealed β, the workpiece, the time in the range of 5 minutes to 24 hours, comprising β annealing method according to claim 1.   The method of claim 1, further comprising plastically deforming the workpiece at a plastic deformation temperature in a β phase region of the titanium alloy prior to cooling the β annealed workpiece. The plastic deformation of the workpiece at the plastic deformation temperature in the β phase region of the titanium alloy includes stretching the workpiece, upsetting forging, and multi-axis forging at a high strain rate. The method of claim 11 , comprising at least one. The method of claim 11 , wherein the plastic deformation temperature is in the range of the β transus temperature of the titanium alloy to a temperature that exceeds the β transus temperature of the titanium alloy by a maximum of 300 ° F. (166.7 ° C.). Plastically deforming the workpiece includes multi-axis forging at a high strain rate, and cooling the workpiece is cooling the workpiece to the workpiece forging temperature in an α + β phase region of the titanium alloy. 12. The method of claim 11 , comprising multi-axis forging the workpiece at a high strain rate when doing so. The method of claim 11 , wherein plastically deforming the workpiece comprises upsetting and forging the workpiece to a strain within a range of 0.1 to 0.5.   The workpiece forging temperature ranges from a temperature that is lower than the β transus temperature of the titanium alloy by 100 ° F. (55.6 ° C.) to a temperature that is lower than the β transus temperature of the titanium alloy by 700 ° F. (388.9 ° C.). The method of claim 1, wherein During successive multiple press forgings,
Heating the outer surface of the workpiece to or near the workpiece forging temperature within the workpiece forging temperature range, the adiabatically heated inner region of the workpiece; The method of claim 1, further comprising cooling to a temperature at or near the workpiece forging temperature within a forging temperature range. The method of claim 17 , wherein the adiabatically heated interior region of the workpiece is cooled for a time in the range of 5 seconds to 120 seconds. The method of claim 17 , wherein heating the outer surface of the workpiece includes heating using one or more of flame heating, box furnace heating, induction heating, and radiant heating. The die of the forging furnace used to press forge the workpiece is heated to a temperature within the range of the workpiece forging temperature to a temperature that is 100 ° F. (55.6 ° C.) below the workpiece forging temperature. The method of claim 17 . The method of claim 1, wherein after a total true strain of at least 1.0 and less than 3.5 is achieved, the workpiece has an average alpha particle size in the range of 4 μm or less. Repeating at least one of the press forgings until the total true strain of at least 1.0 and less than 3.5 is achieved in the workpiece presses the workpiece at a second workpiece forging temperature. Forging, wherein the second workpiece forging temperature is in the α + β phase region of the titanium alloy of the workpiece, and the second workpiece forging temperature is lower than the workpiece forging temperature, The method of claim 1. A method for reducing the particle size of a workpiece made of titanium or a titanium alloy ,
Β annealing the workpiece;
Cooling the beta annealed workpiece to a temperature below the beta transus temperature of the titanium alloy;
Including multi-axis forging the workpiece, the multi-axis forging,
The workpiece is forged within a workpiece forging temperature range in the direction of the first orthogonal A-axis of the workpiece at a strain rate sufficient to adiabatically heat the interior region of the workpiece. Press forging to a primary reduction spacer height, which is a distance corresponding to the desired final forging dimension for each orthogonal axis of the workpiece at a temperature;
Press forging the workpiece in a direction of a second orthogonal B-axis of the workpiece to a first rough reduction spacer height greater than a main reduction spacer height at the workpiece forging temperature;
Press forging the workpiece in a direction of a third orthogonal C-axis of the workpiece to a second roughing reduction spacer height greater than the main reduction spacer height at the workpiece forging temperature;
The main reduction of the workpiece at the workpiece forging temperature in the direction of the second orthogonal B axis of the workpiece at a strain rate sufficient to adiabatically heat the internal region of the workpiece. Press forging to spacer height;
And said workpiece, said direction of said third orthogonal axis C of the workpiece, press forged into the workpiece forging the temperature first rough beating pressure spacer height,
Press forging the workpiece in the direction of the first orthogonal A-axis of the workpiece to the second roughing reduction spacer height at the workpiece forging temperature;
The main reduction of the workpiece at the workpiece forging temperature in the direction of the third orthogonal C-axis of the workpiece at a strain rate sufficient to adiabatically heat the internal region of the workpiece. Press forging to spacer height;
And said workpiece, said direction of said first orthogonal axis A of the workpiece, press forged into the workpiece forging the temperature first rough beating pressure spacer height,
Press forging the workpiece in the direction of the second orthogonal B-axis of the workpiece to the second roughing reduction spacer height at the workpiece forging temperature;
Repeating at least one of the preceding press forgings until a total true strain in the range of at least 1.0 and less than 3.5 is achieved in the workpiece. The method of claim 23 , wherein the strain rate used during press forging is in the range of 0.2 sec- ^{1 to} 0.8 sec- ¹ . 24. The method of claim 23 , wherein the titanium alloy comprises one of an α + β titanium alloy and a metastable β titanium alloy. 24. The method of claim 23 , wherein the titanium alloy comprises an α + β titanium alloy. 27. The method of claim 25 or 26 , wherein the titanium alloy includes at least one of a grain pinning element and a beta stabilizer that reduces alpha phase precipitation and alpha phase growth rate. The titanium alloys are Ti-6Al-2Sn-4Zr-6Mo alloy (UNS R56260), Ti-6Al-2Sn-4Zr-2Mo-0.08Si alloy (UNS R54620), Ti-4Al-2.5V alloy (UNS R54250). ), Ti-6Al-7Nb alloy (UNS R56700), and a Ti-6Al-6V-2Sn alloy (titanium alloy selected from UNS R56620), the method of claim 23. 24. The method of claim 23 , wherein cooling the beta annealed workpiece comprises cooling the workpiece to room temperature . 24. The method of claim 23 , wherein cooling the beta annealed workpiece comprises cooling the workpiece to the workpiece forging temperature. Β annealing the workpiece is a temperature within the range of the β transus temperature of the titanium alloy up to a maximum of 300 ° F. (166.7 ° C.) above the β transus temperature of the titanium alloy. 24. The method of claim 23 , comprising beta annealing at . Wherein the workpiece is annealed β, the workpiece, the time in the range of 5 minutes to 24 hours, comprising β annealing method according to claim 23. Prior to cooling the beta annealed workpiece to a temperature below the beta transus temperature of the titanium alloy, further comprising plastically deforming the workpiece at a plastic deformation temperature in a beta phase region of the titanium alloy. 24. The method of claim 23 . Plastically deforming the workpiece at a plastic deformation temperature in the β-phase region of the titanium alloy includes stretching, upsetting and multiaxial forging at a high strain rate. 34. The method of claim 33 , comprising at least one of the following. The plastic deformation temperature is in the range of the β transus temperature of the titanium alloy of the workpiece to a temperature that exceeds the β transus temperature of the titanium alloy of the workpiece by up to 300 ° F. (166.7 ° C.). 34. The method of claim 33 . Plastically deforming the workpiece includes multi-axis forging at a high strain rate, and cooling the β-annealed workpiece when the workpiece cools to the workpiece forging temperature. 34. The method of claim 33 , comprising multi-axis forging the workpiece at a high strain rate. 34. The method of claim 33 , wherein plastically deforming the workpiece comprises upsetting and forging the workpiece to a strain within a range of 0.1 to 0.5. The workpiece forging temperature ranges from a temperature that is lower than the β transus temperature of the titanium alloy by 100 ° F. (55.6 ° C.) to a temperature that is lower than the β transus temperature of the titanium alloy by 700 ° F. (388.9 ° C.). 24. The method of claim 23 , wherein: During successive press forgings, the outer surface area of the workpiece is heated to or near the workpiece forging temperature within the workpiece forging temperature range. 24. The method of claim 23 , wherein the adiabatically heated interior region is cooled to a temperature at or near a workpiece forging temperature within the workpiece forging temperature range. 40. The method of claim 39 , wherein the adiabatically heated interior region of the workpiece is cooled for a time in the range of 5 seconds to 120 seconds. 40. The method of claim 39 , wherein heating the outer surface of the workpiece comprises heating using one or more of flame heating, box furnace heating, induction heating, and radiant heating. The die of the forging furnace used to press forge the workpiece is heated to a temperature within the range of the workpiece forging temperature to a temperature that is 100 ° F. (55.6 ° C.) below the workpiece forging temperature. 40. The method of claim 39 . 24. The method of claim 23 , wherein after a total true strain of at least 1.0 and less than 3.5 is achieved, the workpiece has an average alpha particle size of 4 [mu] m or less. Repeating at least one of the press forgings until the total true strain of at least 1.0 and less than 3.5 is achieved in the workpiece presses the workpiece at a second workpiece forging temperature. Forging, wherein the second workpiece forging temperature is in an α + β phase region of the titanium alloy workpiece, and the second workpiece forging temperature is lower than the workpiece forging temperature. 24. The method according to 23 .

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