A low-surface-roughness cold-rolled titanium foil and a method for producing the same

Abstract

The present application relates to the technical field of precision cold-rolled titanium foil material, and particularly relates to a low-surface-roughness cold-rolled titanium foil material and a preparation method thereof. The titanium foil material is prepared by the method. The method comprises the following steps: cold-rolling a pretreated titanium strip coil to a first intermediate thickness to obtain a first intermediate strip coil; after alkali washing the first intermediate strip coil, performing first full annealing treatment under a protective atmosphere to obtain an annealed first intermediate strip coil; cold-rolling the annealed first intermediate strip coil to a second intermediate thickness to obtain a second intermediate strip coil; after alkali washing the second intermediate strip coil, performing second full annealing treatment under a protective atmosphere to obtain an annealed second intermediate strip coil; after alkali washing the annealed second intermediate strip coil, cold-rolling to a finished product thickness to obtain a low-surface-roughness cold-rolled titanium foil material. The present application can prepare a cold-rolled titanium foil material with a surface roughness Ra of less than or equal to 0.15 microns, without the phenomenon of roll sticking and surface defects.

Description

Technical Field

[0001] This invention relates to the field of precision cold-rolled titanium foil technology, and in particular to a low surface roughness cold-rolled titanium foil and its preparation method. Background Technology

[0002] Titanium and its alloys are widely used in aerospace, chemical, and medical fields due to their excellent mechanical properties and chemical stability. Currently popular electronic products such as foldable screen phones typically use cold-rolled titanium foil as a backing, which places high demands on the mechanical properties of the cold-rolled titanium foil and imposes strict requirements on surface roughness. However, titanium has poor heat dissipation; using existing rolling processes, excessive heat can easily accumulate on the surface of the titanium coil during cold rolling, leading to rolling roller sticking and ultimately affecting product surface quality and production efficiency.

[0003] Currently, the conventional surface roughness Ra of precision cold-rolled titanium foil is ≥0.2μm. When the surface roughness Ra <0.2μm, especially Ra≤0.15μm, if the existing rolling process is used, it is easy to cause defects such as color difference lines, scratches and uneven gloss on the surface of cold-rolled titanium foil due to improper control of rolling deformation and rolling tension, as well as insufficient surface cleanliness.

[0004] Therefore, it is necessary to provide a low surface roughness cold-rolled titanium foil and its preparation method to solve the following problems: 1) solve the problem of rolling roller sticking that is easy to occur when cold-rolled titanium foil is rolled using existing rolling processes; 2) solve the problem that cold-rolled titanium foil with a surface roughness Ra≤0.15μm easily has color difference lines, scratches and uneven gloss on the finished product surface when rolled using existing rolling processes. Summary of the Invention

[0005] The purpose of this invention is to provide a cold-rolled titanium foil with low surface roughness and its preparation method. The specific technical solution is as follows: In a first aspect, the present invention provides a method for preparing a cold-rolled titanium foil with low surface roughness, comprising: Step S1: Cold roll the pretreated titanium strip coil to a first intermediate thickness to obtain a first intermediate strip coil; wherein, the total deformation of the rolling thickness is controlled to be <50%; Step S2: After alkali washing, the first intermediate strip roll is subjected to a first full annealing treatment under a protective atmosphere to obtain the annealed first intermediate strip roll; the annealing temperature used in the first full annealing treatment is T. 再 +100~T 再 +200℃, heat preservation time 1~3min; the T 再 This is the recrystallization temperature of the titanium strip coil; Step S3: Cold roll the annealed first intermediate strip coil to a second intermediate thickness to obtain a second intermediate strip coil; wherein, the total deformation of the rolling thickness is controlled to be <50%; Step S4: After alkali washing, the second intermediate strip roll undergoes a second full annealing treatment under a protective atmosphere to obtain the annealed second intermediate strip roll; the annealing temperature used in the second full annealing treatment is T. 再 +100~T 再 +200℃, heat preservation time is 1~3 minutes; Step S5: After alkali washing of the annealed second intermediate strip roll, it is then cold rolled to the finished thickness to obtain a cold-rolled titanium foil with low surface roughness, where the roughness Ra ≤ 0.15 μm; wherein, the roll weight is controlled to ≤ 3t, the rolling speed is controlled to be 60~150m / min, the thickness deformation per single pass is controlled to ≤ 15%, the total thickness deformation is controlled to ≤ 40%, and the rolling unit tension is controlled to ≤ 700N / mm. 2 The roughness of the rolls is gradually reduced from 0.5~0.6μm to [0.08μm, 0.15μm] according to the rolling sequence, and the rolls are changed after each rolling pass.

[0006] Optionally, in step S1, the thickness of the titanium strip roll is 0.5~0.7mm.

[0007] Optionally, in step S1, the pretreatment is a full annealing treatment under a protective atmosphere, with an annealing temperature of 780~800℃ and a holding time of 3~5min.

[0008] Optionally, the first intermediate thickness is 0.35~0.45mm.

[0009] Optionally, the second intermediate thickness is 0.15~0.25mm.

[0010] Optionally, the thickness of the finished product is 0.1~0.15mm.

[0011] Optionally, the titanium strip coil includes TA4 strip coil.

[0012] Optionally, the T 再 The temperature is 600~700℃.

[0013] Optionally, the preparation method of the low surface roughness cold-rolled titanium foil further includes step S6, in which the low surface roughness cold-rolled titanium foil is alkali-washed and then subjected to a third full annealing treatment under a protective atmosphere to obtain an annealed cold-rolled titanium foil; the annealed cold-rolled titanium foil is then straightened to obtain the finished product; wherein the annealing temperature used in the third full annealing treatment is T. 再 +50~T 再 +150℃, heat preservation time is 1~3 minutes.

[0014] In a second aspect, the present invention provides a low surface roughness cold-rolled titanium foil, which is prepared by the aforementioned method for preparing low surface roughness cold-rolled titanium foil; The low surface roughness cold-rolled titanium foil has a tensile strength ≥700 MPa, a yield strength ≥600 MPa, and an elongation ≥15%.

[0015] The application of the technical solution of the present invention has at least the following beneficial effects: (1) The present invention provides a method for preparing cold-rolled titanium foil with low surface roughness. Through the synergistic effect of steps S1 to S5, cold-rolled titanium foil with a surface roughness Ra≤0.15μm can be prepared without the phenomenon of sticking to the rolling roller, and without defects such as color difference lines, scratches and uneven gloss on the surface of the finished product. The specific principle is as follows: In addressing the issue of roll sticking during rolling, this invention strictly controls the thickness deformation of a single rolling pass to ≤15% in step S5. This prevents severe plastic deformation and mechanical interlocking between the titanium foil and the microscopic protrusions on the roll surface, improving the surface quality of the finished product. Simultaneously, it avoids excessive thickness deformation in a single rolling pass, which would generate excessive deformation heat in the titanium foil, increasing atomic diffusion and thus preventing roll sticking. Furthermore, this invention strictly controls the rolling speed in step S5 to 60~150 m / min to ensure a reasonable rolling speed and prevent roll sticking caused by excessive speed. If the rolling speed is too high, it easily generates a large amount of frictional and deformation heat during rolling, leading to a rapid increase in temperature in the rolling zone. This temperature increase reduces the yield strength of titanium and increases atomic diffusion, making roll sticking more likely. Finally, this invention strictly controls the rolling process by changing rolls after each pass in step S5. This not only effectively prevents roll sticking but also improves the surface quality of the finished product, avoiding defects such as color lines, scratches, and uneven gloss. In addressing defects such as color difference lines, scratches, and uneven gloss on the finished product surface, this invention, in step S5, controls the thickness deformation of a single rolling pass to ≤15% and the roll change rolling, which can improve the surface quality of the finished product. In addition, it also coordinates with multi-step alkaline washing treatment to achieve a clean treatment of the strip coil, which can also improve the surface quality of the finished product and avoid defects such as color difference lines, scratches, and uneven gloss on the finished product surface.

[0016] Furthermore, in step S5 of this invention, the single-pass rolling thickness deformation is controlled to be ≤15%, the total rolling thickness deformation is controlled to be ≤40%, and the rolling unit tension is controlled to be ≤700 N / mm. 2This allows for precise control of the finished product thickness within ±3μm after rolling, and the straightness of the coil after unloading can be controlled within 0~5mm. Furthermore, the cold-rolled titanium foil prepared using this invention has a surface roughness Ra≤0.15μm, exhibiting a very smooth surface with excellent optical reflection properties, facilitating processes such as electroplating, spraying, etching, or bonding. Moreover, a surface roughness Ra≤0.15μm significantly improves the corrosion resistance and chemical stability of the finished product. This is because a low-roughness surface has fewer micro-pits and cracks, greatly reducing the adhesion and hiding of corrosive media, avoiding pitting and crevice corrosion. Combined with the inherent corrosion resistance of titanium, this significantly enhances the corrosion resistance and chemical stability of the finished product.

[0017] (2) The low surface roughness cold-rolled titanium foil obtained by this invention has uniform overall performance, and its tensile strength is ≥700 MPa, yield strength is ≥600 MPa, and elongation is ≥15%. The specific principle is as follows: Regarding tensile strength, yield strength, and elongation, this invention, based on the synergistic cold rolling in steps S1, S3, and S5, and the synergistic annealing in steps S2, S4, and S6, can drive the titanium strip coil to undergo intense plastic deformation through synergistic cold rolling. This generates numerous deformation bands, shear bands, and dislocation entanglements within the coil, "cutting" the original coarse grains into many fine substructures with different orientations. These substructures recrystallize after synergistic annealing, forming new, strain-free, fine, and uniform equiaxed grains. The grain boundaries of these equiaxed grains become insurmountable barriers to dislocation movement, thereby significantly improving the yield strength and tensile strength of the finished low-surface-roughness cold-rolled titanium foil. In addition, these fine equiaxed grains can also improve the plasticity of the finished product, resulting in increased elongation.

[0018] Regarding the overall performance uniformity, the present invention, through the synergistic cold rolling and synergistic annealing processes in steps S1 to S6, can form fine and uniform equiaxed grain structures both inside and on the surface of the finished low-surface-roughness cold-rolled titanium foil, thus ensuring the overall performance uniformity of the finished product. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: A method for preparing a cold-rolled titanium foil with low surface roughness includes: Step S1: Cold roll the pretreated titanium strip coil (specifically TA4 strip coil) to a first intermediate thickness to obtain a first intermediate strip coil; wherein, the total deformation of the rolling thickness is controlled to be <50%; Step S2: After alkali washing, the first intermediate strip roll is subjected to a first full annealing treatment under a protective atmosphere to obtain the annealed first intermediate strip roll; the annealing temperature used in the first full annealing treatment is T. 再 +100~T 再 +200℃ (specifically 780℃), heat preservation time is 1~3min (specifically 2min); the T 再 The T is the recrystallization temperature of the titanium strip; 再 The temperature is 600~700℃; Step S3: Cold roll the annealed first intermediate strip coil to a second intermediate thickness to obtain a second intermediate strip coil; wherein, the total deformation of the rolling thickness is controlled to be <50%; Step S4: After alkali washing, the second intermediate strip roll undergoes a second full annealing treatment under a protective atmosphere to obtain the annealed second intermediate strip roll; the annealing temperature used in the second full annealing treatment is T. 再 +100~T 再 +200℃ (specifically 780℃), heat preservation time is 1~3min (specifically 1min); Step S5: After alkali washing, the annealed second intermediate strip coil is cold rolled to the finished thickness to obtain a low surface roughness cold-rolled titanium foil with a roughness Ra≤0.15μm (specifically 0.13~0.15μm); wherein, the coil weight is controlled ≤3t, the rolling speed is controlled 60~150m / min, the thickness deformation per single pass is controlled ≤15%, the total thickness deformation is controlled ≤40%, and the rolling unit tension is controlled ≤700N / mm. 2 The roll roughness is gradually reduced from 0.5~0.6μm to [0.08μm, 0.15μm] according to the rolling sequence (see Table 1). Rolls are changed after each rolling pass. The cold rolling process used in step S5 consists of seven passes, and the rolling deformation amounts used in the rolling sequence are 10%, 8%, 7%, 6%, 6%, 5% and 5% respectively.

[0021] Step S6: After alkaline washing, the low surface roughness cold-rolled titanium foil is subjected to a third full annealing treatment under a protective atmosphere to obtain annealed cold-rolled titanium foil; the annealed cold-rolled titanium foil is then straightened to obtain the finished product; wherein, the annealing temperature used in the third full annealing treatment is T. 再 +50~T 再 +150℃ (specifically 680℃), heat preservation time is 1~3min (specifically 1min).

[0022] The rolling temperature for cold rolling in steps S1, S3 and S5 is 20~40℃ (specifically, cold rolling is performed at room temperature).

[0023] In step S1, the thickness of the titanium strip roll is 0.5~0.7mm (specifically 0.70mm).

[0024] In step S1, the pretreatment is a full annealing treatment under a protective atmosphere, with an annealing temperature of 780~800℃ (specifically 800℃) and a holding time of 3~5min (specifically 3min).

[0025] The first intermediate thickness is 0.35~0.45mm (specifically 0.40mm).

[0026] The second intermediate thickness is 0.15~0.25mm (specifically 0.24mm).

[0027] The thickness of the finished product is 0.1~0.15mm (specifically 0.15mm).

[0028] Example 2: Unlike Example 1, the parameters that have changed are as follows: The first intermediate thickness is 0.38 mm; The second intermediate thickness is 0.20 mm; The finished product thickness in step S5 is 0.12 mm; the surface roughness Ra of the low surface roughness cold-rolled titanium foil is 0.11~0.15 μm, and the specific changes in roll roughness with rolling sequence are shown in Table 1.

[0029] The method of gradually reducing the roughness of the rolls in step S5 according to the rolling sequence is shown in Table 1. The cold rolling process used in step S5 consists of seven passes, and the rolling deformation amounts used in the rolling sequence are 10%, 9%, 8%, 7%, 6%, 5% and 5% respectively.

[0030] Comparative Example 1: Unlike Example 2, the cold rolling process used in step S5 consists of five passes, with the rolling deformation amounts being 16%, 12%, 10%, 6%, and 6% respectively, in the order of rolling.

[0031] Comparative Example 2: Unlike Example 2, the rolling speed is controlled at 170 m / min in step S5.

[0032] Comparative Example 3: Unlike Example 2, the alkaline washing in step S5 is omitted.

[0033] Comparative Example 4: Unlike Example 2, as shown in Table 1, in step S5, the roughness of the 6th and 7th passes of the rolling mill is controlled to be 0.15 μm and 0.15 μm respectively (the remaining 1 to 5 passes remain unchanged), and the roughness Ra of the resulting low surface roughness cold-rolled titanium foil is 0.16~0.20 μm.

[0034] Samples of the low surface roughness cold-rolled titanium foils prepared in Examples 1-2 and Comparative Examples 1-3 were taken for tensile strength, yield strength, and elongation tests, and the test results are shown in Table 2. The tensile strength, yield strength, and elongation were tested according to the GB / T 228 test method. Additionally, Table 2 also provides data on whether the low surface roughness cold-rolled titanium foils prepared in Examples 1-2 and Comparative Examples 1-3 exhibited roller sticking and surface defects. Data on roller sticking and surface defects were obtained visually.

[0035] Table 1. Variation of roll roughness as a step-by-step decrease according to rolling sequence. Table 2 Test Results From the data in Table 2, we know that: Compared with Comparative Examples 1-4, the present invention can prepare low surface roughness cold-rolled titanium foil with surface roughness Ra≤0.15μm using Examples 1-2. Not only does it not exhibit the phenomenon of sticking to the rolling roller, but it also does not show defects such as color difference lines, scratches and uneven gloss on the surface of the finished product. In addition, it has good tensile strength, yield strength and elongation properties.

[0036] Compared to Example 2, in Comparative Example 1, step S5 resulted in excessive thickness deformation during single-pass rolling, leading to roll sticking. This is because excessive thickness deformation during single-pass rolling causes the titanium foil to generate a large amount of deformation heat, increasing atomic diffusion capacity and thus causing roll sticking.

[0037] Compared to Example 2, controlling the rolling speed too high in step S5 of Comparative Example 2 resulted in roll sticking and surface defects (specifically, color difference lines, scratches, and uneven gloss). This is because excessively high rolling speeds easily generate a large amount of frictional and deformation heat during rolling, causing a sharp rise in the temperature of the rolling zone. This temperature increase reduces the yield strength of titanium and increases atomic diffusion capacity, making roll sticking more likely. In addition, excessively high rolling speeds can easily cause slippage during rolling, leading to surface defects.

[0038] Compared to Example 2, omitting the alkaline washing in step S5 in Comparative Example 3 resulted in surface defects (specifically, color difference lines, scratches, and uneven gloss). This is because omitting the alkaline washing leaves residual impurities on the coil surface unremoved, leading to surface defects after rolling.

[0039] Compared to Example 2, in step S5 of Comparative Example 4, the roughness of the 6th and 7th passes of the rolling mill is controlled to be 0.15 μm and 0.15 μm respectively, resulting in a surface roughness Ra of 0.16~0.20 μm, which is greater than 0.15 μm. This indicates that the cold rolling process used in step S5 not only requires gradually reducing the roughness of the rolls according to the rolling sequence, but also requires strict control of the roughness of the 6th and 7th passes to be less than 0.15 μm.

[0040] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the present invention's specification under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing a cold-rolled titanium foil with low surface roughness, characterized in that, include: Step S1: Cold roll the pretreated titanium strip coil to a first intermediate thickness to obtain a first intermediate strip coil; wherein, the total deformation of the rolling thickness is controlled to be <50%; Step S2: After alkali washing, the first intermediate strip roll is subjected to a first full annealing treatment under a protective atmosphere to obtain the annealed first intermediate strip roll; the annealing temperature used in the first full annealing treatment is T. 再 +100~T 再 +200℃, heat preservation time 1~3min; the T 再 This is the recrystallization temperature of the titanium strip coil; Step S3: Cold roll the annealed first intermediate strip coil to a second intermediate thickness to obtain a second intermediate strip coil; wherein, the total deformation of the rolling thickness is controlled to be <50%; Step S4: After alkali washing, the second intermediate strip roll undergoes a second full annealing treatment under a protective atmosphere to obtain the annealed second intermediate strip roll; the annealing temperature used in the second full annealing treatment is T. 再 +100~T 再 +200℃, heat preservation time is 1~3 minutes; Step S5: After alkali washing of the annealed second intermediate strip roll, it is then cold rolled to the finished thickness to obtain a cold-rolled titanium foil with low surface roughness, where the roughness Ra ≤ 0.15 μm; wherein, the roll weight is controlled to ≤ 3t, the rolling speed is controlled to be 60~150m / min, the thickness deformation per single pass is controlled to ≤ 15%, the total thickness deformation is controlled to ≤ 40%, and the rolling unit tension is controlled to ≤ 700N / mm. 2 The roughness of the rolls is gradually reduced from 0.5~0.6μm to [0.08μm, 0.15μm] according to the rolling sequence, and the rolls are changed after each rolling pass; In step S5, the cold rolling process involves seven passes. The rolling deformation amounts used in the rolling sequence are 10%, 8%, 7%, 6%, 6%, 5%, and 5%, with corresponding roll roughnesses of 0.6μm, 0.6μm, 0.5μm, 0.4μm, 0.2μm, 0.1μm, and 0.1μm, respectively. Alternatively, the rolling deformation amounts used in the rolling sequence are 10%, 9%, 8%, 7%, 6%, 5%, and 5%, with corresponding roll roughnesses of 0.5μm, 0.4μm, 0.3μm, 0.2μm, 0.15μm, 0.08μm, and 0.08μm, respectively.

2. The method for preparing low surface roughness cold-rolled titanium foil as described in claim 1, characterized in that, In step S1, the thickness of the titanium strip roll is 0.5~0.7mm.

3. The method for preparing low surface roughness cold-rolled titanium foil as described in claim 1, characterized in that, In step S1, the pretreatment is a full annealing process under a protective atmosphere, with an annealing temperature of 780~800℃ and a holding time of 3~5min.

4. The method for preparing low surface roughness cold-rolled titanium foil as described in claim 1, characterized in that, The first intermediate thickness is 0.35~0.45mm.

5. The method for preparing low surface roughness cold-rolled titanium foil as described in claim 1, characterized in that, The second intermediate thickness is 0.15~0.25mm.

6. The method for preparing low surface roughness cold-rolled titanium foil as described in claim 1, characterized in that, The thickness of the finished product is 0.1~0.15mm.

7. The method for preparing low surface roughness cold-rolled titanium foil as described in claim 1, characterized in that, The titanium strip coil includes TA4 strip coil.

8. The method for preparing low surface roughness cold-rolled titanium foil as described in claim 7, characterized in that, The T 再 The temperature is 600~700℃.

9. The method for preparing low surface roughness cold-rolled titanium foil as described in any one of claims 1 to 8, characterized in that, The process also includes step S6, where the low-surface-roughness cold-rolled titanium foil is alkali-washed and then subjected to a third full annealing treatment under a protective atmosphere to obtain an annealed cold-rolled titanium foil; the annealed cold-rolled titanium foil is then straightened to obtain the finished product; wherein the annealing temperature used in the third full annealing treatment is T. 再 +50~T 再 +150℃, heat preservation time is 1~3 minutes.

10. A cold-rolled titanium foil with low surface roughness, characterized in that, It is prepared by the method for preparing low surface roughness cold-rolled titanium foil as described in claim 9; The low surface roughness cold-rolled titanium foil has a tensile strength ≥700 MPa, a yield strength ≥600 MPa, and an elongation ≥15%.

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