A preparation method of TC16 titanium alloy elliptical cross-section wire for sports protective gear

Abstract

The present invention discloses a method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear. The method uses a TC16 titanium alloy coiled wire blank, which is crack-free when cold heading or cold forging with a forging ratio of 1:4, as the raw material. The chemical composition of the raw material must meet the requirements of GB / T 3620.1. The microstructure must also be characterized by fine and uniform primary α phases in both the transverse and longitudinal directions, with a surface roughness of ≤1.6μm. The wire blank is first subjected to multiple roller die cold drawing passes to obtain a circular cross-section wire blank. The wire blank is then preformed using a four-roll mill with a deformed elliptical hole. The wire is then finished using a combination of roller die cold drawing and four-roll mill rolling to obtain an elliptical cross-section wire of precise dimensions. Finally, the wire is heat treated to obtain the target product, and parameters such as deformation and hole shape are fully controlled throughout the process. The wire prepared by the present invention has high precision, good surface quality, and room temperature tensile properties that fully meet the requirements of sports protective gear. The wire also has good batch consistency and stability, making it easy to mass produce.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy wire processing, and specifically relates to a method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear. The elliptical cross-section wire obtained by the method is mainly used for making the mask cage of a protective helmet. Background Art

[0002] It's no secret that athletes playing sports like hockey, rugby, and baseball must wear protective helmets. These helmets include a visor cage to protect the wearer's face from impacts from sports equipment (e.g., bats, hockey pucks, baseballs, etc.). The visor cage must be constructed from elliptical metal wire of various specifications. These wires must be lightweight, weldable, have high dimensional accuracy, possess certain mechanical properties (tensile strength ≥800 MPa and yield strength ≥740 MPa), and exhibit minimal sensitivity to stress concentrations such as notches and deflections.

[0003] At present, the elliptical cross-section wire used to make mask cages is generally made of Gr.4. During its preparation, Fe and O elements are added, and the finished wire is stress-relieved and annealed. This can achieve a tensile strength of ≥800Mpa, but its yield strength can only meet the low-standard requirements at best. When subjected to a large impact load, it is easy to deform, which may cause facial injuries to athletes. Therefore, there is an urgent need to find a metal material to replace Gr.4 for making mask cages. The inventors have learned through extensive scientific research that the strength of TC16 titanium alloy can meet the above requirements. However, compared with Gr.4 elliptical cross-section wire, the difficulty in preparing TC16 alloy elliptical cross-section wire is that it needs to be cold-worked and heat-treated to regulate its structure and ensure its room temperature tensile properties. Gr.4 elliptical cross-section wire has a lower yield strength. Using traditional fixed die cold drawing can obtain wire with qualified cross-sectional dimensional accuracy. Cold drawing TC16 titanium alloy to elliptical cross-section wire is prone to surface scratches, and dimensional deviation control is difficult. At the same time, there is a problem of low material stability and easy twisting during the drawing process, and it is impossible to ensure the consistency of the head and tail dimensions of the entire coil of wire. Therefore, the above-mentioned traditional process method cannot stably and mass-produce TC16 titanium alloy elliptical cross-section wire.

[0004] In view of this, the inventors propose a method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear to overcome the defects of the prior art. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear. The preparation method first uses cold drawing to obtain a round wire blank, and then obtains a standard elliptical cross-section wire by combining drawing and rolling, thereby ensuring the dimensional accuracy and surface roughness of the product size. Finally, a vacuum heat treatment system is used to obtain an elliptical wire whose room temperature tensile strength meets the mechanical performance requirements of sports protective gear.

[0006] The purpose of the present invention is to solve the problem through the following technical solutions:

[0007] A method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear uses a TC16 titanium alloy coiled wire blank with no cracks when cold heading or cold forging with a forging ratio of 1:4 as a raw material. The chemical composition of the raw material should meet the requirements of the TC16 alloy in the GB / T3620.1 standard. The microstructure of the raw material is required to be equiaxed in both the transverse and longitudinal primary α phases and the surface roughness is ≤1.6μm. The preparation method comprises the following steps:

[0008] Step 1: Roller-die cold drawing of the raw material to obtain a round-section wire blank

[0009] At room temperature, the raw material is subjected to 6 to 10 drawing processes using a two-pass roller die drawing machine, and the deformation amount of each pass and the cumulative deformation amount are controlled to obtain a wire blank with a preset circular cross-section size;

[0010] Step 2: Flat-rolling pre-forming of the circular cross-section wire blank

[0011] A four-roll rolling mill is used with upper and lower rolls having a pass profile, and the circular cross-section wire blank obtained in step 1 is rolled using a modified elliptical pass profile to obtain a wire material with a nearly elliptical cross-section;

[0012] Step 3: Combined forming by roller die drawing and four-roll mill rolling

[0013] Design an elliptical vertical rolling pass on a single-piece adjustable roller die, and design a finished elliptical pass on a four-roll mill. First, use the single-piece adjustable roller die to process the long axis direction of the ellipse, and then use the elliptical hole of the four-roll mill to control the cross-sectional dimensional accuracy, so as to process the nearly elliptical cross-sectional wire obtained in step 2 into a standard elliptical cross-sectional wire.

[0014] Step 4: Forming heat treatment

[0015] Before heat treatment, the standard elliptical cross-section wire obtained in step 3 is first degreased and then annealed in a vacuum furnace to obtain a TC16 titanium alloy elliptical cross-section wire of the target size for sports protective gear.

[0016] Furthermore, during the drawing process in step 1, the deformation amount of each pass is 2.13% to 14.08%, and the cumulative deformation amount is 48.3% to 71.8%.

[0017] Furthermore, in the step 2, the height of the deformed elliptical hole = (the length of the minor axis of the target ellipse + 0.2 mm) / 2, the width of the hole = the length of the major axis of the target ellipse + 0.2 mm, the expansion angle = 33.5°~34°, the arc radius of the expansion angle = (0.8633~0.9731) × the length of the minor axis of the target ellipse; the top arc is a part of the standard elliptical curve, its major axis = the length of the major axis of the target ellipse + 0.2 mm, the minor axis = the length of the minor axis of the target ellipse + 0.2 mm, and the top arc angle = 112°~113°.

[0018] Furthermore, in step three, the pass profile of the single-piece adjustable roller die is set vertically to the rolling pass profile of the four-roll mill, and the pass profile of the four-roll mill is distributed on the upper and lower rollers, and the center lines of the pass profiles should coincide during the drawing and rolling process.

[0019] Furthermore, in the step three, the cumulative deformation of the nearly elliptical cross-section wire obtained in the step two to the standard elliptical cross-section wire is 18.19% to 18.42%, and the cumulative deformation of the raw material in the step one to the standard elliptical cross-section wire is 58% to 77%.

[0020] Furthermore, in step three, the height of the single-piece adjustable roller die pass = (long axis length of the target ellipse / 2) - (0.15-0.20) mm, the top arc is 1 / 4 of the circle, that is, the angle corresponding to the top arc of the pass is 90°, the arc radius = (0.9133-0.9538) ÷ 2 × the short axis length of the target ellipse, and the expansion angle = 45°.

[0021] Furthermore, in step three, the rolling pass height of the four-high rolling mill finished product = the target ellipse minor axis length / 2, the pass width = the target ellipse major axis length + 0.01 mm, and the pass curve is a standard elliptical curve.

[0022] Furthermore, the degreasing agent used in the degreasing treatment in step 4 is an aqueous metal rolling oil remover.

[0023] Furthermore, when forging the finished product in step three, an 80MN fast forging unit with a dual-operation linkage function is used for forging.

[0024] Furthermore, during the forming heat treatment in step 4, the heat treatment temperature is 780° C. to 820° C., the holding time is 1 hour to 2 hours, and the furnace is cooled to below 100° C. before being taken out of the furnace.

[0025] Furthermore, the TC16 titanium alloy elliptical cross-section wire produced by the preparation method has a size deviation within ±0.02 mm, a surface roughness ≤1.6 μm, a tensile strength of 800 MPa to 860 MPa, a yield strength ≥740 MPa, and an elongation ≥14%.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides a method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear. The method comprises the following steps: first, cold drawing a circular cross-section wire blank of a certain size through a two-roller die, and then processing the wire blank through a combination of drawing with a single adjustable roller die and rolling on a four-roll mill. During the processing, the pass shape and deformation are strictly controlled. As a result, the prepared C16 titanium alloy elliptical cross-section wire has high dimensional accuracy and good surface roughness. At the same time, by matching the cumulative deformation with the heat treatment system, the final product has good mechanical properties. According to actual tests, the tensile strength is 800 MPa to 860 MPa, the yield strength is ≥740 MPa, and the elongation is ≥14%. The preparation method can prepare a series of standard TC16 alloy wires with elliptical cross-sections, such as 4.2 mm (major axis) × 3 mm (minor axis) and 4 mm (major axis) × 2.8 (minor axis). Compared with the existing technology, the method has at least the following advantages:

[0028] First, the present invention adopts roller die cold drawing to obtain circular cross-section wire blanks. Roller die cold drawing can control the size of the wire blank and ensure the fullness of the forming hole of the elliptical cross-section. The surface quality of the roller die cold drawn wire is better than that of the traditional fixed die drawing surface, ensuring the surface roughness of the elliptical cross-section wire.

[0029] Secondly, the present invention adopts flat rolling preforming to roll the deformed elliptical cross-section wire according to the characteristics of the elliptical cross-section, and then adopts a combination of a single-piece adjustable roller die and a four-roll rolling mill to simultaneously process the major and minor axis directions of the elliptical cross-section. The roller die serves as a guide for the groove rolling of the four-roll rolling mill, which ensures the stability of the rolling process. The obtained elliptical cross-section wire has high dimensional accuracy and can prevent the elliptical cross-section from twisting during the processing process, thereby ensuring the consistency of the head and tail dimensions of the entire coil of wire.

[0030] Third, the present invention controls the cumulative deformation and heat treatment system of roller die cold drawing and elliptical cold drawing and rolling, and the room temperature tensile properties of the elliptical cross-section wire prepared thereby meet the mechanical property requirements of sports protective gear;

[0031] Fourthly, the process of the present invention is simple, and the TC16 titanium alloy elliptical cross-section wire prepared therefrom has good batch consistency and stability, and is particularly suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the invention.

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0034] Figure 1 This is a flow chart of a method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear according to the present invention;

[0035] Figure 2 These are typical transverse and longitudinal high-magnification micrographs of the raw material TC16 titanium alloy coiled wire blank of the present invention; wherein: (a) is a transverse 1000× micrograph, and (b) is a longitudinal 1000× micrograph;

[0036] Figure 3 Schematic diagrams of target elliptical cross-section dimensions of Examples 1 to 3 of the present invention; wherein: (a) is a schematic diagram of an elliptical cross-section of 4.2 mm × 3.0 mm, (b) is a schematic diagram of an elliptical cross-section of 4 mm × 2.8 mm, and (c) is a schematic diagram of an elliptical cross-section of 3.8 mm × 2.6 mm;

[0037] Figure 4 Schematic diagrams of three pass structures used in preparing 4.2 mm × 3.0 mm elliptical cross-section wire in Example 1 of the present invention; wherein: (a) is a diagram of a modified elliptical pass of a four-roll mill, (b) is a diagram of a pass of a single adjustable roller die, and (c) is a diagram of a finished rolling pass of a four-roll mill;

[0038] Figure 5 Schematic diagrams of three pass structures used in preparing 4 mm × 2.8 mm elliptical cross-section wire in Example 2 of the present invention; wherein: (a) is a diagram of a modified elliptical pass of a four-roll mill, (b) is a diagram of a pass of a single-piece adjustable roller die, and (c) is a diagram of a finished rolling pass of a four-roll mill;

[0039] Figure 6 Schematic diagrams of three pass structures used in preparing 3.8 mm × 2.6 mm elliptical cross-section wire in Example 3 of the present invention; wherein: (a) is a diagram of a modified elliptical pass of a four-roll mill, (b) is a diagram of a pass of a single adjustable roller die, and (c) is a diagram of a finished rolling pass of a four-roll mill;

[0040] Figure 7 This is a transverse high-magnification microstructure diagram of the TC16 titanium alloy elliptical cross-section wire finally prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0041] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of arrangements consistent with certain aspects of the present invention as detailed in the appended claims.

[0042] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.

[0043] See Figure 1 As shown, the present invention provides a method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear, wherein the raw material is: a TC16 titanium alloy coiled wire blank having no cracks when cold heading or cold top forging with a forging ratio of 1:4, the chemical composition of the wire blank should meet the requirements of TC16 alloy in GB / T 3620.1 standard, and the microstructure characteristics are that the primary α phase in the transverse and longitudinal directions are both equiaxed and fine and uniform (such as Figure 2 As shown), the surface roughness is ≤1.6μm, and the preparation method of the present invention specifically comprises the following steps:

[0044] Step 1: Roller-die cold drawing of the raw material to obtain a round-section wire blank

[0045] Specifically, under room temperature, the raw material is drawn 6 to 10 times using a two-pass roller die drawing machine, and the deformation of each pass is controlled to be 2.13% to 14.08%. At the same time, the cumulative deformation is required to be 48.3% to 71.8% to obtain a circular cross-section wire blank of preset size.

[0046] Step 2: Flat-rolling pre-forming of the circular cross-section wire blank

[0047] A four-roll mill with upper and lower rolls is used to roll the circular-cross-section wire blank obtained in step 1 using a modified elliptical pass profile to produce a wire with a near-elliptical cross-section. Specifically, the pass height of the modified elliptical hole is set to (target elliptical minor axis length + 0.2mm) / 2, the pass width is set to (target elliptical major axis length + 0.2mm), the expansion angle is set to 33.5° to 34°, and the arc radius of the expansion angle is (0.8633 to 0.9731) × target elliptical minor axis length. The top arc is a portion of the standard elliptical curve, with its major axis = target elliptical major axis length + 0.2mm, its minor axis = target elliptical minor axis length + 0.2mm, and the top arc angle = 112° to 113°. The modified elliptical holes are arranged symmetrically about the vertical centerline.

[0048] Step 3: Combined forming by roller die drawing and four-roll mill rolling

[0049] An elliptical vertical rolling hole profile is designed on a single-piece adjustable roller die, and a finished elliptical hole profile is designed on a four-roll mill. The long axis direction of the ellipse is first processed using the single-piece adjustable roller die, and then the cross-sectional size accuracy is controlled through the elliptical hole of the four-roll mill. That is, the long axis and short axis directions of the ellipse can be processed simultaneously by combining drawing and rolling, thereby processing the nearly elliptical cross-sectional wire obtained in step 2 into a standard elliptical cross-sectional wire. The single-piece adjustable roller die is used as a rolling guide to ensure the stability of the material during the rolling process, prevent torsion during the elliptical cross-sectional processing process, and ensure the consistency of the head and tail sizes of the entire coil of wire.

[0050] Specifically, the pass profile of the single-piece adjustable roller die is perpendicular to the rolling pass profile of the four-high mill, with the four-high mill pass profile distributed between the upper and lower rolls. During the drawing and rolling process, the centerlines of the pass profiles should coincide. The pass profile height of the single-piece adjustable roller die is (target ellipse major axis length / 2) - (0.15-0.20) mm, and the top arc of the pass profile is 1 / 4 of a circle, meaning the angle corresponding to the top arc of the pass profile is 90°. The arc radius is (0.9133-0.9538) ÷ 2 × the target ellipse minor axis length, and the pass profile expansion angle is 45°. The finished rolling pass profile height of the four-high mill is equal to the target ellipse minor axis length / 2, the pass profile width is equal to the target ellipse major axis length + 0.01 mm, and the pass profile curve is a standard elliptical curve. Both pass profiles are symmetrically arranged about the vertical centerline. During the forming process, the cumulative deformation of the nearly elliptical cross-section wire obtained in step 2 to the standard elliptical cross-section wire is 18.19% to 18.42%, while the cumulative deformation of the raw material in step 1 to the standard elliptical cross-section wire is 58% to 77%.

[0051] Step 4: Forming heat treatment

[0052] Before heat treatment, the standard elliptical cross-section wire obtained in step 3 is first degreased using a water-based metal rolling oil remover; then annealed in a vacuum furnace at a vacuum heat treatment temperature of 780°C to 820°C for 1 to 2 hours. The furnace is cooled to below 100°C and then removed from the furnace to obtain a TC16 titanium alloy elliptical cross-section wire of the target size for sports protective gear.

[0053] In order to further verify the efficacy of the cold drawing and rolling combination method of the present invention, the inventors conducted the following specific examples:

[0054] Example 1 (preparation of 4.2 mm × 3.0 mm elliptical cross-section wire, such as Figure 3 (shown in (a))

[0055] 1) TC16 titanium alloy Φ7.4mm round wire with uniform longitudinal and transverse structure was selected as raw material. The chemical composition met the requirements of TC16 alloy in GB / T3620.1 standard, and the surface roughness was ≤1.6μm. The wire was drawn using a two-pass roller die drawing machine at room temperature. After 10 drawing passes, a wire blank with a circular cross-section of Φ3.93mm was obtained. The cumulative deformation was 71.8%, and the deformation of a single pass was 2.98% to 14.08%.

[0056] 2) The wire blank obtained in step 1) is rolled using a four-roll mill with a modified elliptical pass to obtain a wire with a nearly elliptical cross-section. The rolling pass of the four-roll mill is distributed on the upper and lower rollers. The modified elliptical pass is as follows: Figure 4 As shown in (a), the die has a die height of h = 1.6 mm, a die width of b = 4.4 mm, a flare angle α = 34°, an arc radius r = 2.59 mm, a top arc that forms a portion of a 4.4 mm × 3.2 mm elliptical curve, and a top arc angle β = 112°. After rolling, the wire has a nearly elliptical cross-section, with dimensions of: minor axis 3.2 (+0.03, -0.03) mm × major axis (4.40-4.45) mm.

[0057] 3) The nearly elliptical cross-section wire prepared in step 2) is subjected to an elliptical vertical rolling pass designed on a single adjustable roller die, and then to a finished elliptical pass on a four-roll mill. The elliptical long axis is shaped by the single roller die, and the cross-sectional dimensional accuracy is controlled by the elliptical pass on the four-roll mill, resulting in a wire with a standard elliptical cross-section.

[0058] Specifically, the roller die pass and the four-high mill pass are perpendicular, and the four-high mill pass is distributed between the upper and lower rolls. The centerlines of the pass should coincide during the drawing and rolling process. The wire blank obtained in step 2) is rolled into a 4.2 mm × 3.0 mm elliptical wire with a minor axis of 3.2 (+0.03, -0.03) mm and a major axis of (4.40-4.45) mm, resulting in a cumulative deformation of 18.42%.

[0059] Single piece adjustable roller die hole type such as Figure 4 As shown in (b), the die has a die height of h = 1.9 mm, a die width of b = 3.83 mm, an expansion angle α = 45°, a top arc angle β = 90°, and an arc radius R = 1.37. The wire dimensions after roller drawing are: major axis 4.1 (+0.03, -0.03) mm × minor axis 3.2 mm to 3.25 mm.

[0060] The rolling pass of the finished product of the four-high rolling mill is as follows Figure 4 As shown in (c), the pass height h = 1.5mm, the pass width b = 4.21, and the pass profile is a standard 4.21mm × 3mm elliptical curve. The finished rolled wire dimensions are: major axis 4.2(+0.02, -0.02)mm × minor axis 3.0(+0.02, -0.02)mm; the cumulative deformation of the 7.4mm Φ elliptical wire rolled to a 4.2mm × 3mm diameter is 77%.

[0061] 4) The oval wire obtained in step 3) is first subjected to surface rolling oil removal using an aqueous metal degreaser, and then annealed in a vacuum furnace at 780°C for 2 hours. The furnace is cooled to below 100°C and then removed from the furnace to obtain the target product.

[0062] Example 2 (preparation of 4.0 mm × 2.8 mm elliptical cross-section wire, such as Figure 3 (shown in (b))

[0063] 1) TC16 titanium alloy Φ5.82 mm round wire with uniform longitudinal and transverse structure was selected as raw material. The chemical composition met the requirements of TC16 alloy in GB / T 3620.1 standard, and the surface roughness was ≤1.6 μm. The wire was drawn using a two-pass roller die drawing machine at room temperature. After 8 drawing passes, a wire blank with a circular cross-section of Φ3.7 mm was obtained. The cumulative deformation was 59.58%, and the deformation of a single pass was 2.13% to 13.43%.

[0064] 2) The wire blank obtained in step 1) is rolled using a four-roll mill with a modified elliptical pass to obtain a wire with a nearly elliptical cross-section. The rolling pass of the four-roll mill is distributed on the upper and lower rollers. The modified elliptical pass is as follows: Figure 5 As shown in (a), the die has a die height h = 1.5 mm, a die width b = 4.2 mm, a flare angle α = 33.75°, an arc radius r = 2.56 mm, a top arc that forms a 4.2 mm × 3.0 mm elliptical curve, and a top arc angle β = 112.5°. After rolling, the wire has a nearly elliptical cross-section with dimensions: minor axis 3.0 (+0.03, -0.03) mm × major axis (4.20-4.25) mm.

[0065] 3) The nearly elliptical cross-section wire prepared in step 2) is subjected to an elliptical vertical rolling pass designed on a single adjustable roller die, and then to a finished elliptical pass on a four-roll mill. The elliptical long axis is shaped by the single roller die, and the cross-sectional dimensional accuracy is controlled by the elliptical pass on the four-roll mill, resulting in a wire with a standard elliptical cross-section.

[0066] Specifically, the roller die pass and the four-high mill pass are perpendicular. The four-high mill pass is distributed between the upper and lower rolls, and the centerlines of the pass should coincide during the drawing and rolling process. The wire blank obtained in step 2) is rolled into a 4.0 mm × 2.8 mm elliptical wire with a short axis of 3.0 (+0.03, -0.03) mm and a long axis of (4.20-4.25) mm, resulting in a cumulative deformation of 18.19%.

[0067] Single piece adjustable roller die hole type such as Figure 5As shown in (b), the die has a die height of h = 1.8 mm, a die width of b = 3.6 mm, an expansion angle α = 45°, a top arc angle β = 90°, and an arc radius R = 1.32. The wire dimensions after roller drawing are: major axis 3.9 (+0.03, -0.03) mm × minor axis 3.0 mm to 3.05 mm.

[0068] The rolling pass of the finished product of the four-high rolling mill is as follows Figure 5 As shown in (c), the pass height h = 1.4mm, the pass width b = 4.01, and the pass profile is a standard 4.01mm × 2.8mm elliptical curve. The finished rolled wire dimensions are: major axis 4.0(+0.02, -0.02)mm × minor axis 2.8(+0.02, -0.02)mm. The cumulative deformation of the 5.82mm Φ elliptical wire rolled to a 4.0mm × 2.8mm diameter is 67%.

[0069] 4) The oval wire obtained in step 3) is first treated with an aqueous metal degreaser to remove rolling oil from its surface. The wire is then annealed in a vacuum furnace at 800°C for 1.5 hours. The furnace is cooled to below 100°C and the wire is removed from the furnace to obtain the target product.

[0070] Example 3 (Preparation of 3.8mm×2.6mm elliptical cross-section wire, such as Figure 3 (shown in (c))

[0071] 1) TC16 titanium alloy Φ4.84 mm round wire with uniform longitudinal and transverse structure was selected as raw material. The chemical composition met the requirements of TC16 alloy in GB / T 3620.1 standard, and the surface roughness was ≤1.6 μm. The wire was drawn using a two-pass roller die drawing machine at room temperature. After 6 drawing passes, a wire blank with a circular cross-section of Φ3.48 mm was obtained. The cumulative deformation was 48.30%, and the deformation of a single pass was 2.81% to 13.43%.

[0072] 2) The wire blank obtained in step 1) is rolled using a four-roll mill with a modified elliptical pass to obtain a wire with a nearly elliptical cross-section. The rolling pass of the four-roll mill is distributed on the upper and lower rollers. The modified elliptical pass is as follows: Figure 6 As shown in (a), the die has a die height h = 1.4 mm, a die width b = 4.0 mm, a flare angle α = 33.5°, an arc radius r = 2.53 mm, a top arc that forms part of a 4.0 mm × 2.8 mm elliptical curve, and a top arc angle β = 113°. After rolling, the wire has a nearly elliptical cross-section, with dimensions of: minor axis 2.8 (+0.03, -0.03) mm × major axis (4.0-4.05) mm.

[0073] 3) The nearly elliptical cross-section wire prepared in step 2) is subjected to an elliptical vertical rolling pass designed on a single adjustable roller die, and then to a finished elliptical pass on a four-roll mill. The elliptical long axis is shaped by the single roller die, and the cross-sectional dimensional accuracy is controlled by the elliptical pass on the four-roll mill, resulting in a wire with a standard elliptical cross-section.

[0074] Specifically, the roller die pass and the four-high mill pass are perpendicular. The four-high mill pass is distributed between the upper and lower rolls, and the centerlines of the pass should coincide during the drawing and rolling process. The wire blank obtained in step 2) is rolled into a 3.8mm x 2.6mm elliptical wire with a minor axis of 2.8 (+0.03, -0.03) mm and a major axis of (4.0-4.05) mm, resulting in a cumulative deformation of 18.41%.

[0075] Single piece adjustable roller die hole type such as Figure 6 As shown in (b), the die has a die height of h = 1.75 mm, a die width of b = 3.4 mm, an expansion angle α = 45°, a top arc angle β = 90°, and an arc radius R = 1.24. The wire dimensions after roller drawing are: major axis 3.7 (+0.03, -0.03) mm × minor axis 2.8 mm to 2.85 mm.

[0076] The rolling pass of the finished product of the four-high rolling mill is as follows Figure 6 As shown in (c), the pass height h = 1.3mm, the pass width b = 3.81, and the pass profile is a standard 3.81mm × 2.6mm elliptical curve. The finished rolled wire dimensions are: major axis 3.81(+0.02, -0.02)mm × minor axis 2.6(+0.02, -0.02)mm. The cumulative deformation of the 4.84mm Φ elliptical wire rolled to a 3.8mm × 2.6mm diameter is 58%.

[0077] 4) The oval wire obtained in step 3) is first subjected to surface rolling oil removal using an aqueous metal degreaser, and then annealed in a vacuum furnace at 820°C for 1 hour. The furnace is cooled to below 100°C and then removed from the furnace to obtain the target product.

[0078] Furthermore, in order to verify whether the internal structure of the wire prepared by the preparation method of the present invention is uniform, the inventors conducted the following experiments: Figure 7 In Example 3, the elliptical cross-section wire was prepared using the preparation method of the present invention. The TC16 elliptical wire exhibits a fine and uniform transverse high-magnification structure. To verify whether the mechanical properties of the elliptical cross-section wire prepared using the preparation method of the present invention meet the requirements for sports protective gear, samples were cut from the wires obtained in Examples 1 to 3 and tested for room temperature tensile properties. The results are shown in Table 1 below.

[0079] Table 1 Room temperature tensile properties of the wires of Examples 1 to 3

[0080]

[0081] In summary, through Figure 7 The data in Table 1 show that the TC16 titanium alloy elliptical cross-section wire prepared by the preparation method of the present invention has a fine and uniform internal structure, and has good tensile strength, yield strength and elongation, and the tensile strength is greater than 800 MPa, the yield strength is greater than 750 MPa, and the elongation is greater than 16%, which can fully meet the mechanical property requirements of sports protective gear. At the same time, the prepared elliptical cross-section wire has high dimensional accuracy and good surface quality.

[0082] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0083] It should be understood that the present invention is not limited to the above description and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing TC16 titanium alloy elliptical cross-section wire for sports protective gear, characterized in that: A TC16 titanium alloy coiled wire blank having no cracks when used for cold heading or cold forging with a forging ratio of 1:4 is used as a raw material. The chemical composition of the raw material should meet the requirements of the TC16 alloy in the GB / T 3620.1 standard. At the same time, the microstructure of the raw material is required to be that the primary α phase in both the transverse and longitudinal directions is equiaxed, and the surface roughness is ≤1.6μm. The preparation method comprises the following steps: Step 1: Roller-die cold drawing of the raw material to obtain a round-section wire blank At room temperature, the raw material is subjected to 6 to 10 drawing processes using a two-pass roller die drawing machine, and the deformation amount of each pass and the cumulative deformation amount are controlled to obtain a wire blank with a preset circular cross-section size; Step 2: Flat-rolling pre-forming of the circular cross-section wire blank A four-roll rolling mill is used with upper and lower rolls having a pass profile, and the circular cross-section wire blank obtained in step 1 is rolled using a modified elliptical pass profile to obtain a wire material with a nearly elliptical cross-section; Step 3: Combined forming by roller die drawing and four-roll mill rolling Design an elliptical vertical rolling pass on a single-piece adjustable roller die, and design a finished elliptical pass on a four-roll mill. First, use the single-piece adjustable roller die to process the long axis direction of the ellipse, and then use the elliptical hole of the four-roll mill to control the cross-sectional dimensional accuracy, so as to process the nearly elliptical cross-sectional wire obtained in step 2 into a standard elliptical cross-sectional wire. Step 4: Forming heat treatment Before heat treatment, the standard elliptical cross-section wire obtained in step 3 is first degreased and then annealed in a vacuum furnace to obtain a TC16 titanium alloy elliptical cross-section wire of the target size for sports protective gear.

2. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to claim 1, characterized in that: During the drawing process in step 1, the deformation amount of each pass is 2.13% to 14.08%, and the cumulative deformation amount is 48.3% to 71.8%.

3. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to claim 1, characterized in that: In the step 2, the height of the deformed elliptical hole is equal to (the length of the minor axis of the target ellipse + 0.2 mm) / 2, the width of the hole is equal to the length of the major axis of the target ellipse + 0.2 mm, the expansion angle is 33.5° to 34°, and the arc radius of the expansion angle is (0.8633 to 0.9731) × the length of the minor axis of the target ellipse; The top arc is a part of the standard elliptical curve, its major axis = the length of the major axis of the target ellipse + 0.2 mm, its minor axis = the length of the minor axis of the target ellipse + 0.2 mm, and the top arc angle = 112°~113°.

4. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to claim 1, characterized in that: In the step three, the pass of the single-piece adjustable roller die is set vertically to the rolling pass of the four-roll mill, and the pass of the four-roll mill is distributed on the upper and lower rollers, and the center lines of the pass should coincide during the drawing and rolling process.

5. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to claim 1, characterized in that: In the step three, the cumulative deformation of the nearly elliptical cross-section wire obtained in the step two to the standard elliptical cross-section wire is 18.19% to 18.42%, and the cumulative deformation of the raw material in the step one to the standard elliptical cross-section wire is 58% to 77%.

6. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to claim 1, characterized in that: In the step 3, the height of the single-piece adjustable roller die hole = (long axis length of the target ellipse / 2) - (0.15 to 0.20) mm, the top arc is 1 / 4 of the circle, that is, the angle corresponding to the top arc of the hole is 90°, the arc radius = (0.9133 to 0.9538) ÷ 2 × the short axis length of the target ellipse, and the expansion angle = 45°.

7. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to claim 1, characterized in that: In the step 3, the rolling pass height of the finished product of the four-high rolling mill is equal to the target ellipse minor axis length / 2, the pass width is equal to the target ellipse major axis length+0.01 mm, and the pass curve is a standard ellipse curve.

8. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to claim 1, characterized in that: The degreasing agent used in the degreasing treatment in step 4 is an aqueous metal rolling oil remover.

9. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to claim 1, characterized in that: During the forming heat treatment in step 4, the heat treatment temperature is 780° C. to 820° C., the heat preservation time is 1 hour to 2 hours, and the furnace is cooled to below 100° C. before being taken out of the furnace.

10. The method for preparing a TC16 titanium alloy elliptical cross-section wire for sports protective gear according to any one of claims 1 to 9, characterized in that: The TC16 titanium alloy elliptical cross-section wire produced by the preparation method has a size deviation within ±0.02 mm, a surface roughness of ≤1.6 μm, a tensile strength of 800 MPa to 860 MPa, a yield strength of ≥740 MPa, and an elongation of ≥14%.

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