Method for rolling wide titanium belt at low cost through 18-roller single-stand rolling mill

Abstract

The invention relates to a low-cost method for rolling a wide-width titanium belt through an 18-roller single-stand rolling mill, and belongs to the technical field of titanium rolling. The method comprises the following steps that S1, preparation before rolling is conducted, specifically, an 18-roller rolling mill is selected, and the head and the tail of a hot-rolled titanium coil are welded with leading tapes and polished to be smooth; s2, cold rolling is conducted, specifically, the hot-rolled titanium coil is subjected to reciprocating multi-pass rolling on an 18-roller rolling mill; s3, degreasing treatment; s4, vacuum annealing; and S5, drawing, straightening and trimming to obtain the finished titanium coil. According to the method, the deformation characteristics of the 18-roller mill and the titanium coiled strip are combined, the effect that a hot coil is rolled into a cold-rolled finished product in one rolling process is achieved on the 18-roller mill, the deformation amount is larger than that of a 6-roller mill, and the rolling cost is lower than that of a 20-roller mill. Meanwhile, the mechanical property of the titanium plate coil is regulated and controlled through three-stage vacuum annealing, the strength difference between the inner coil and the outer coil of the titanium coil is reduced, and the strength fluctuation of the same coil can be controlled to be + / -15 MPa. The technical problems of small rolling deformation, poor plate shape control, low efficiency and high cost of the existing thin titanium strip rolling are solved.

Description

TECHNICAL FIELD

[0001] The application relates to a method for low-cost rolling of wide titanium strips by an 18-roller single-stand rolling mill, and belongs to the technical field of titanium rolling. BACKGROUND

[0002] Titanium has the advantages of low density, high specific strength, good corrosion resistance, excellent high-temperature performance and the like, and is widely used in the fields of aerospace, petrochemical industry, electronics and the like. Cold-rolled titanium strips account for about 12% of the total amount of titanium materials, have the characteristics of high technical content and great manufacturing difficulty, and are high-value-added products among titanium materials.

[0003] In the field of titanium strip cold rolling, a 6-roller rolling mill and a 20-roller rolling mill are two mainstream technical routes. The 6-roller rolling mill has the advantages of simple structure, low cost, flexible arrangement form, single machine reversibility and serial connection type continuous rolling, and is widely used in the rolling of medium-thick titanium strips. For example, the method for cold-rolling pure titanium strips disclosed in the domestic patent CN102002657A has the problems of excessive rolling pressure, insufficient reduction capacity, poor flatness control ability and the like when rolling thin titanium strips, and is prone to cause edge thinning and rib defects.

[0004] The 20-roller Sendzimir rolling mill is particularly suitable for rolling thin titanium strips by virtue of the tower-type roller system and small work roll support. For example, the method for rolling pure titanium strips by the Sendzimir 20-roller rolling mill disclosed in the domestic patent CN106734204A has the problems of difficult threading, long roll changing time of 4-6 hours, equipment cost of more than 3 times of the 6-roller rolling mill, poor economy when rolling medium-thick titanium strips and higher energy consumption than the 6-roller rolling mill. SUMMARY

[0005] The application solves the technical problems of small rolling deformation and poor flatness control of existing rolling thin titanium strips, and low efficiency and high cost.

[0006] The technical scheme adopted by the application to solve the technical problems is as follows: a method for low-cost rolling of wide titanium strips by an 18-roller single-stand rolling mill, comprising the following steps: S1. Pre-rolling preparation, select 18-roller mill according to the thickness specification of finished product titanium strip, and weld the head and tail of hot-rolled titanium coil with lead, polish the surface of the weld after welding; S2. Cold rolling, according to the finished product specification, the hot-rolled titanium coil is rolled on the 18-roller mill in multiple passes, and the deformation of the first pass is 7% to 12%, and the rolling speed is 60 to 80 m / min; then the deformation of the pass is increased to 15% to 18%, and the rolling speed is increased to 120 to 150 m / min, finally the pass reduction is gradually reduced, and the pass reduction is controlled at 7% to 10% in the last pass, and the rolling speed is reduced to 100 to 120 m / min; S3. Degreasing, the cold-rolled titanium coil obtained in step S2 is degreased on the degreasing line; S4. Vacuum annealing, the degreased titanium coil is annealed in a vacuum annealing furnace; S5. Tension leveling and edge trimming, the annealed titanium coil is tension leveled and edge trimmed on a leveling line to obtain the finished product titanium coil.

[0007] In the above method step S1, the roller system of the 18-roller mill is selected according to the thickness specification of the finished product titanium strip: when the thickness of the finished product titanium strip is 0.8 to 2.5 mm, the I roller system is selected, the work roll diameter is 170 to 140 mm, the work roll roughness is 0.3 to 0.5 μm, and the intermediate roll diameter is 380 to 345 mm; when the thickness of the finished product titanium strip is 0.3 to 0.8 mm, the II roller system is selected, the work roll diameter is 150 to 120 mm, the work roll roughness is 0.2 to 0.4 μm, and the intermediate roll diameter is 365 to 345 mm.

[0008] In the above method step S1, the emulsion concentration is 2.8% to 3.5%, and the emulsion temperature is 45 to 55℃.

[0009] In the above method step S1, the hot-rolled titanium coil is TA1, and the element mass fraction requirements are: C < 0.02%, N < 0.005%, H < 0.002%, O < 0.05%, Fe < 0.02%, and other impurity elements < 0.02%, the oxygen equivalent requirement is ≤0.08%, the oxygen equivalent calculation formula is: [O] = 2.5xN + 1.0xO + 0.7xC + 0.5xFe; and the hot-rolled titanium coil is in annealed and pickled state, the thickness specification is 2.8 to 6.0 mm, the thickness tolerance requirement is ±0.22 mm, the width specification is 1260 to 1530 mm; the mechanical property requirements are: yield strength R p0.2 : 160 to 280 MPa, tensile strength Rm: 280 to 400 MPa, elongation A after fracture > 50%, grain size 6.0 to 9.0; the lead material is TA1, the thickness difference between the lead and the hot-rolled titanium coil is ≤0.6 mm, the lead width is 30 to 50 mm wider than the hot-rolled titanium coil, and the lead length is 15 to 20 m.

[0010] Wherein, the front and rear tension of the rolling process in the above method step S2 refers to the yield strength R of the titanium coil p0.2 , the front tension is (0.3-0.5)xR p0.2 x thickness x width, and the rear tension is (0.2-0.4)xR p0.2 x thickness x width.

[0011] Further, the front and rear tension coefficients of the first pass and the last pass in the above method step S2 are respectively 0.3 and 0.2; when the thickness of the titanium coil is <0.6mm, the front and rear tension coefficients are respectively 0.4 and 0.3.

[0012] Wherein, the unwinding tension is (1.2-3.5)x thickness x width, and the winding tension is (1.5-4.0)x thickness x width.

[0013] Wherein, in the above method step S4, three-stage heating is adopted, in the first stage, the furnace temperature is raised to 200℃ at a speed of 100℃ / s and is kept for 6-8h, in the second stage, the furnace temperature is raised to 450-480℃ at a speed of 90-120℃ / s and is kept for 10-12h, and in the third stage, the furnace temperature is raised to 600-650℃ at a speed of 10-15℃ / s and is kept for 12-15h.

[0014] Wherein, in the above method step S4, the initial vacuum degree of the vacuum annealing furnace is ≤1x10 -2 Pa, and the vacuum degree in the heating process is required to be ≤5x10 -2 Pa.

[0015] Wherein, in the above method step S5, the tension of the straightening is (0.5-0.7)xR p0.2 x thickness x width, the deformation amount of the straightening is controlled according to 0.2%-0.5%, the deformation amount of the straightening of the titanium coil with a thickness of 0.3-1.0mm is 0.2%-0.30%, the straightening speed is 30-50m / min, the deformation amount of the straightening of the titanium coil with a thickness of 1.0-2.5mm is 0.35%-0.5%, and the straightening speed is 40-70m / min.

[0016] The beneficial effects of the present application are: (1) The present method combines the 18-roller rolling mill and the deformation characteristics of the titanium coil, and realizes the rolling of the hot coil to the cold rolling finished product in one rolling process on the 18-roller rolling mill, which has a larger deformation amount than the six-roller rolling mill and a lower rolling cost than the 20-roller rolling mill, and expands the cold rolling method of the titanium coil.

[0017] (2) The present method can cold roll the finished titanium coil with a width of 1250-1520mm and a thickness of 0.3-2.5mm by adjusting the composition, performance and structure of the hot-rolled titanium plate coil and designing the cold rolling process according to the characteristics of the 18-roller rolling mill.

[0018] (3) The method regulates the mechanical properties of the titanium plate roll through three-stage vacuum annealing, reduces the strength difference between the inner and outer rolls of the titanium roll, and can control the strength fluctuation of the same roll ±15MPa. DETAILED DESCRIPTION

[0019] The application will be further described below in combination with examples.

[0020] The method for low-cost rolling of wide titanium strip by an 18-roller single-stand rolling mill of the application comprises the following steps: S1. Pre-rolling preparation, selecting an 18-roller rolling mill according to the thickness specification of the finished titanium strip, and welding the head and tail of the hot-rolled titanium roll with a lead, and polishing the surface of the weld after welding to make it smooth; S2. Cold rolling, according to the finished product specification, the hot-rolled titanium roll is rolled on the 18-roller rolling mill in multiple passes, and the deformation of the first pass is 7% to 12%, and the rolling speed is 60 to 80 m / min; then the deformation of the pass is increased to 15% to 18%, and the rolling speed is increased to 120 to 150 m / min, finally the pass reduction is gradually reduced, and the pass reduction is controlled at 7% to 10% in the last pass, and the rolling speed is reduced to 100 to 120 m / min; S3. Degreasing, the cold-rolled titanium roll obtained in step S2 is subjected to degreasing treatment on a degreasing line; S4. Vacuum annealing, the titanium roll after degreasing is placed in a vacuum annealing furnace for annealing; S5. The annealed titanium coil is drawn, straightened and trimmed to obtain a finished titanium coil on a temper mill. Those skilled in the art can understand that the 18-roller mill reduces the working roller diameter by 40% compared with the 6-roller mill through the design of a small roller diameter + side support roller system, and cooperates with the segmented backing bearing side support to significantly reduce the rolling force. At the same time, the open rack design improves the threading efficiency by 50% compared with the 20-roller mill, and the roll changing time is shortened to 1 hour. The 18-roller mill avoids the horizontal deflection defect of the 6-roller mill through structural reconstruction, and breaks through the closed structure shackles of the 20-roller mill, and is widely used in the field of stainless steel continuous rolling and high-strength steel rolling. At present, there is no precedent of 18-roller cold rolling in the titanium strip field, so the 18-roller mill is preferably used for cold rolling the titanium strip. Step S1 is pre-rolling preparation, and the 18-roller mill is actually selected according to the thickness specification of the finished titanium strip, the mill roller system and the emulsion parameters are determined; at the same time, in order to ensure the smooth progress of rolling, the hot-rolled titanium coil needs to be welded with the leading strip in advance. Step S2 is rolling, which is realized by multiple passes of reciprocating rolling, and the rolling deformation and rolling speed are controlled to ensure the cold rolling quality. Specifically, the first pass rolling deformation is 7% to 12%, and the rolling speed is 60 to 80 m / min. The low rolling speed and small deformation improve the shape and thickness tolerance of the hot-rolled titanium coil, and improve the stability of the subsequent pass rolling. Then, the pass rolling deformation is increased to 15% to 18%, and the rolling speed is increased to 120 to 150 m / min. The high rolling speed and large pass deformation efficiently thin the titanium coil. Finally, the pass reduction is gradually reduced to control the rolling stability and thickness uniformity of the titanium coil. When the last pass, the pass reduction is controlled at 7% to 10%, and the rolling speed is reduced to 100 to 120 m / min to control the thickness tolerance of the finished titanium coil, and the whole coil is padded with paper to prevent layer injury due to unloading tension. Step S3 is degreasing treatment of the cold-rolled titanium coil obtained by cold rolling on the degreasing line to ensure the surface quality of the titanium strip. In step S4, the degreased titanium coil is placed in a vacuum annealing furnace, and three-stage heating is actually adopted to ensure the uniformity of the microstructure and properties of the titanium coil. Step S5 draws, straightens and trims to ensure that the titanium strip specification meets the requirements. In step S5, the thickness specification of the finished titanium coil is 0.3 to 2.5 mm, the thickness tolerance of the thickness of 0.3 to 0.8 mm is ±0.015 mm, the thickness tolerance of the thickness of 0.8 to 1.5 mm is ±0.03 mm, the thickness tolerance of the thickness of 1.5 to 2.5 mm is ±0.05 mm, the width specification is 1250 to 1520 mm, the yield strength R p0.2 : 160 to 300 MPa, the tensile strength R m : 280 to 420 MPa, and the elongation A after fracture > 46%, and the strength fluctuation of the same coil is ±15 MPa.

[0021] Preferably, the roller system of the 18-roller mill is selected according to the thickness specification of the finished titanium strip in step S1 of the above method: when the thickness of the finished titanium strip is 0.8-2.5 mm, the I roller system is selected, the working roller diameter is 170-140 mm, the working roller roughness is 0.3-0.5 μm, and the intermediate roller diameter is 380-345 mm; when the thickness of the finished titanium strip is 0.3-0.8 mm, the II roller system is selected, the working roller diameter is 150-120 mm, the working roller roughness is 0.2-0.4 μm, and the intermediate roller diameter is 365-345 mm. Those skilled in the art can understand that the present method actually selects different roller systems of the 18-roller mill according to the thickness of the titanium strip in order to ensure the rolling quality, specifically, when the thickness of the finished titanium strip is 0.8-2.5 mm, the I roller system is selected, the working roller diameter is 170-140 mm, the working roller roughness is 0.3-0.5 μm, and the intermediate roller diameter is 380-345 mm; when the thickness of the finished titanium strip is 0.3-0.8 mm, the II roller system is selected, the working roller diameter is 150-120 mm, the working roller roughness is 0.2-0.4 μm, and the intermediate roller diameter is 365-345 mm.

[0022] Preferably, the emulsion concentration is 2.8%-3.5% and the emulsion temperature is 45-55°C in step S1 of the above method. Those skilled in the art can understand that the emulsion concentration and temperature are controlled in order to better cooperate with the 18-roller mill and improve the rolling quality. Specifically, the emulsion concentration is preferably 2.8%-3.5% and the emulsion temperature is preferably 45-55°C.

[0023] Preferably, the hot-rolled titanium coil in step S1 of the above method is TA1, which has the following element mass fraction requirements: C < 0.02%, N < 0.005%, H < 0.002%, O < 0.05%, Fe < 0.02%, and other impurity elements < 0.02%, and the oxygen equivalent requirement is ≤0.08%, and the oxygen equivalent calculation formula is: [O] = 2.5xN + 1.0xO + 0.7xC + 0.5xFe; and the hot-rolled titanium coil is in an annealed and pickled state, the thickness specification is 2.8-6.0 mm, the thickness tolerance requirement is ±0.22 mm, and the width specification is 1260-1530 mm; the mechanical property requirements are: yield strength R p0.2 : 160-280 MPa, tensile strength Rm: 280-400 MPa, elongation A after fracture > 50%, and grain size 6.0-9.0; the lead-in material is TA1, the thickness difference between the lead-in and the hot-rolled titanium coil is ≤0.6 mm, the lead-in width is 30-50 mm wider than the hot-rolled titanium coil, and the lead-in length is 15-20 m. Those skilled in the art can understand that the present method further optimizes the grade and chemical composition of the hot-rolled titanium coil and the related performance parameters, which facilitates the comparison in the later stage.

[0024] Preferably, the front and rear tension of the rolling process in step S2 of the above method refers to the yield strength Rp0.2 of the titanium coil, the front tension is (0.3-0.5) x R p0.2 x thickness x width, and the rear tension is (0.2-0.4) x R p0.2 x thickness x width. Those skilled in the art can understand that the front and rear tension of the rolling process in the method is respectively: the front tension is (0.3-0.5) x R p0.2 x thickness x width, and the rear tension is (0.2-0.4) x R p0.2 x thickness x width.

[0025] Preferably, the front and rear tension coefficients of the first pass and the last pass in step S2 of the above method are respectively 0.3 and 0.2; when the thickness of the titanium coil is <0.6 mm, the front and rear tension coefficients are respectively 0.4 and 0.3. Those skilled in the art can understand that the front and rear tension coefficients of the first pass and the last pass in the method are preferably respectively 0.3 and 0.2, which ensures the stability of rolling and the thickness tolerance of the finished product. When the thickness of the titanium coil is <0.6 mm, the front and rear tension coefficients are respectively 0.4 and 0.3, which avoids the ribbing of the titanium coil.

[0026] Preferably, the degreasing speed in step S3 of the above method is controlled at 20-30 m / min, the speed is reduced by 30% in the 20 m of the head and tail of the coil; the unwinding tension is (1.2-3.5) x thickness x width, and the winding tension is (1.5-4.0) x thickness x width. Those skilled in the art can understand that the degreasing speed is controlled at 20-30 m / min, and the speed is reduced by 30% in the 20 m of the head and tail of the coil. The unwinding tension is (1.2-3.5) x thickness x width, and the winding tension is (1.5-4.0) x thickness x width. The coefficients of the unwinding tension and the winding tension are related to the thickness of the titanium coil: when the thickness is 0.3-0.4 mm, the unwinding tension coefficient is 3.5, and the winding tension coefficient is 4.0; when the thickness is 0.4-0.8 mm, the unwinding tension coefficient is 2.5, and the winding tension coefficient is 3.0; when the thickness is 0.8-1.5 mm, the unwinding tension coefficient is 2.0, and the winding tension coefficient is 2.5; when the thickness is 1.5-2.5 mm, the unwinding tension coefficient is 1.2, and the winding tension coefficient is 1.5. By controlling the unwinding tension, the winding tension and the degreasing speed, the stability of degreasing can be ensured while avoiding secondary scratches on the surface.

[0027] Preferably, the third-stage heating is used in the step S4, the furnace temperature is raised to 200°C at a speed of 100°C / s and kept for 6-8h in the first stage, the furnace temperature is raised to 450-480°C at a speed of 90-120°C / s and kept for 10-12h in the second stage, and the furnace temperature is raised to 600-650°C at a speed of 10-15°C / s and kept for 12-15h in the third stage. Those skilled in the art can understand that the furnace temperature is raised to 200°C at a speed of 100°C / s and kept for 6-8h in the first stage, the furnace temperature is raised to 450-480°C at a speed of 90-120°C / s and kept for 10-12h in the second stage, and the furnace temperature is raised to 600-650°C at a speed of 10-15°C / s and kept for 12-15h in the third stage, and the heating process requires that the vacuum degree in the furnace is less than or equal to 5x10-2Pa. The third-stage heating makes the temperature of the inner and outer circles of the titanium coil uniform through long-time keeping at the recrystallization temperature, and then the temperature is raised to above the recrystallization temperature to make the titanium coil recrystallize and soften, thereby ensuring the uniformity of the structure and properties of the titanium coil.

[0028] In the step S4, the initial vacuum degree of the vacuum annealing furnace is less than or equal to 1x10-2Pa, and the vacuum degree in the furnace during the heating process is less than or equal to 5x10-2Pa. -2 Pa, and the vacuum degree in the furnace during the heating process is less than or equal to 5x10-2Pa. -2 Pa, and the vacuum degree in the furnace during the heating process is less than or equal to 5x10-2Pa. -2 Pa, and the vacuum degree in the furnace during the heating process is less than or equal to 5x10-2Pa. -2 Pa to ensure the annealing quality.

[0029] Preferably, the drawing tension in the step S5 is (0.5-0.7)xR p0.2 x thickness x width, the drawing deformation is controlled according to 0.2%-0.5%, the drawing deformation of the titanium coil with a thickness of 0.3-1.0mm is 0.2%-0.30%, the drawing speed is 30-50m / min, the drawing deformation of the titanium coil with a thickness of 1.0-2.5mm is 0.35%-0.5%, and the drawing speed is 40-70m / min. Those skilled in the art can understand that, in order to obtain the titanium strip meeting the requirements, the drawing tension in the step S5 is preferably (0.5-0.7)xR p0.2 x thickness x width, the drawing deformation is controlled according to 0.2%-0.5%, the drawing deformation of the titanium coil with a thickness of 0.3-1.0mm is 0.2%-0.30%, the drawing speed is 30-50m / min, the drawing deformation of the titanium coil with a thickness of 1.0-2.5mm is 0.35%-0.5%, and the drawing speed is 40-70m / min.

[0030] Example 1 The incoming material is TA1 with the following chemical composition: C: 0.011%, N: 0.003%, H: 0.0010%, O: 0.040%, Fe: 0.011%, oxygen equivalent 0.06%. The incoming material has a thickness of 2.8 mm, a thickness tolerance of ±0.15 mm, a width of 1260 mm, a yield strength of 220 MPa, a tensile strength of 360 MPa, an elongation after fracture of 55%, and a grain size of 6.5. The 18-roller selection II roller system has a work roller diameter of 150 mm, a work roller roughness of 0.22 μm, and an intermediate roller diameter of 365 mm. The emulsion concentration is 3.2% and the emulsion temperature is 48°C. The head and tail of the hot-rolled titanium coil are welded with a lead, and the surface of the weld is polished after welding. The lead material is TA1, the lead thickness is 2.5 mm, the lead width is 1300 mm, and the lead length is 20 m. The cold-rolling pass process parameters are shown in the following table.

[0031]

[0032] The cold-rolled titanium coil is degreased on the degreasing line. The degreasing speed is 20 m / min, and the speed of the coil head and tail is 14 m / min. The unwinding tension is 1320 DaN, and the winding tension is 1512 DaN. The degreased titanium coil is placed in a vacuum annealing furnace and heated in three stages. In the first stage, the furnace temperature is raised to 200°C at a speed of 100°C / s for 6 h, in the second stage, the furnace temperature is raised to 450°C at a speed of 90°C / s for 10 h, and in the third stage, the furnace temperature is raised to 600°C at a speed of 10°C / s for 12 h. The vacuum degree in the furnace during the heating process is 2.5´10-2Pa. The annealed titanium coil is drawn, straightened, and trimmed on the leveling line to obtain the finished titanium coil. The drawing and straightening tension is 65 kN, the drawing and straightening deformation is 0.23%, and the drawing and straightening speed is 30 m / min. The finished titanium coil has a thickness of 0.3 mm, a thickness tolerance of ±0.013 mm, a width of 1520 mm, a yield strength of 275 MPa, a tensile strength of 384 MPa, an elongation after fracture of 52%, and a strength fluctuation of ±12 MPa.

[0033] Example 2 The incoming material is TA1 with chemical composition of C: 0.010%, N: 0.003%, H: 0.0009%, O: 0.036%, Fe: 0.010%, and oxygen equivalent of 0.06%. The thickness of the incoming material is 3.75 mm with a thickness tolerance of ±0.20 mm, the width is 1350 mm, the yield strength is 200 MPa, the tensile strength is 352 MPa, the elongation after fracture is 56%, and the grain size is 6.0. The 18-roller is selected as the Ⅱ roller system, the working roller diameter is 142 mm, the working roller roughness is 0.23 μm, and the intermediate roller diameter is 358 mm. The emulsion concentration is 3.2% and the emulsion temperature is 46°C. The head and tail of the hot-rolled titanium coil are welded with a lead, and the surface of the weld is polished smooth after welding. The lead material is TA1, the lead thickness is 3.5 mm, the lead width is 1380 mm, and the lead length is 18 m. The cold rolling pass process parameters are shown in the following table.

[0034]

[0035] The cold-rolled titanium coil is degreased on the degreasing line. The degreasing speed is 30 m / min, and the speed of the coil head and tail is 21 m / min. The unwinding tension is 1680 DaN, and the winding tension is 2025 DaN. The degreased titanium coil is placed in a vacuum annealing furnace for three-stage heating. In the first stage, the furnace temperature is raised to 200°C at a speed of 100°C / s for 8 hours, in the second stage, the furnace temperature is raised to 480°C at a speed of 120°C / s for 12 hours, and in the third stage, the furnace temperature is raised to 620°C at a speed of 15°C / s for 12 hours. The vacuum degree in the furnace during the heating process is 3.2´10-2Pa. The annealed titanium coil is drawn and straightened on the leveling line to obtain the finished titanium coil. The drawing and straightening tension is 92 kN, and the drawing and straightening deformation is 0.26%. The finished titanium coil has a thickness of 0.5 mm with a thickness tolerance of ±0.015 mm, a width of 1340 mm, a yield strength of 236 MPa, a tensile strength of 350 MPa, an elongation after fracture of 53%, and a strength fluctuation of ±13 MPa.

[0036] Example 3 The incoming material is TA1 with chemical composition of C: 0.011%, N: 0.003%, H: 0.0013%, O: 0.048%, Fe: 0.020%, and oxygen equivalent of 0.08%. The thickness of the incoming material is 6.0 mm with a thickness tolerance of ±0.22 mm, the width is 1530 mm, the yield strength is 280 MPa, the tensile strength is 400 MPa, the elongation after fracture is 52%, and the grain size is 9.0. The 18-roller is selected as the Ⅰ roller system, the working roller diameter is 170 mm, the working roller roughness is 0.42 μm, and the intermediate roller diameter is 380 mm. The emulsion concentration is 2.8% and the emulsion temperature is 53°C. The head and tail of the hot-rolled titanium coil are welded with a lead, and the surface of the weld is polished smooth after welding. The lead material is TA1, the lead thickness is 6.0 mm, the lead width is 1560 mm, and the lead length is 10 m. The cold rolling pass process parameters are shown in the following table.

[0037]

[0038] The cold-rolled titanium coil is degreased on the degreasing line. The degreasing speed is 20 m / min, the coil head and tail speed is 14 m / min. The unwinding tension is 4590 DaN, and the winding tension is 5740 DaN. The degreased titanium coil is placed in a vacuum annealing furnace for three-stage heating. The furnace temperature is raised to 200°C at a speed of 100°C / s for 7h in the first stage, to 460°C at a speed of 100°C / s for 12h in the second stage, and to 650°C at a speed of 12°C / s for 15h in the third stage. The vacuum degree in the furnace during the heating process is 4.5´10-2Pa. The annealed titanium coil is tension leveled and edge cut on the leveling line to obtain the finished titanium coil. The tension leveling tension is 560kN, the tension leveling deformation is 0.42%, and the tension leveling speed is 46m / min. The thickness of the finished titanium coil is 2.5mm, the thickness tolerance is ±0.05mm, the width is 1520mm, the yield strength is 289MPa, the tensile strength is 402MPa, the elongation after fracture is 49%, and the strength fluctuation of the same coil is ±15MPa.

Claims

1. A method for rolling wide titanium strips at low cost using an 18-roll single-stand rolling mill, characterized in that The steps include: S1. Pre-rolling preparation: select an 18-roll mill according to the thickness of the finished titanium strip and weld the hot-rolled titanium coils to the lead strips. After welding, the weld surface is polished smooth. S2. Cold rolling: The hot-rolled titanium coil is rolled on an 18-high rolling mill in multiple reciprocating passes according to the finished product specifications. The first pass has a rolling deformation of 7% to 12% and a rolling speed of 60 to 80 m / min. The rolling deformation is then increased to 15% to 18% and the rolling speed is increased to 120 to 150 m / min. Finally, the rolling reduction is gradually reduced, and the final pass has a rolling reduction of 7% to 10% and a rolling speed of 100 to 120 m / min. S3 degreasing, the cold-rolled titanium coil obtained in step S2 is degreased on the degreasing line; S4 vacuum annealing, the degreased titanium coil is placed in a vacuum annealing furnace for annealing; S5. Stretching, straightening and trimming: the annealed titanium coil is stretched, straightened and trimmed on a flattening line to obtain a finished titanium coil.

2. The method for rolling wide titanium strip with an 18-high single-stand mill at low cost according to claim 1, characterized in that: In step S1, the roll system of the 18-roll mill is selected according to the thickness specification of the finished titanium strip: when the thickness of the finished titanium strip is 0.8-2.5 mm, the roll system I is selected, the working roll diameter is 170-140 mm, the working roll roughness is 0.3-0.5 μm, and the intermediate roll diameter is 380-345 mm; when the thickness of the finished titanium strip is 0.3-0.8 mm, the roll system II is selected, the working roll diameter is 150-120 mm, the working roll roughness is 0.2-0.4 μm, and the intermediate roll diameter is 365-345 mm.

3. The method for rolling wide titanium strip with an 18-high single-stand mill at low cost according to claim 1, characterized in that: In step S1, the concentration of the emulsion is 2.8% to 3.5%, and the temperature of the emulsion is 45 to 55°C.

4. The method for rolling wide titanium strip with an 18-high single-stand mill at low cost according to claim 1, characterized in that: The hot-rolled titanium coil in step S1 is graded TA1, and its element mass fraction requirements are: C < 0.02%, N < 0.005%, H < 0.002%, O < 0.05%, Fe < 0.02%, other impurity elements < 0.02%, oxygen equivalent requirement ≤ 0.08%, oxygen equivalent calculation formula: [O] = 2.5xN + 1.0xO + 0.7xC + 0.5xFe; and the hot-rolled titanium coil is in annealed and pickled state, with a thickness specification of 2.8 to 6.0 mm, a thickness tolerance requirement of ± 0.22 mm, and a width specification of 1260 to 1530 mm; mechanical property requirements, yield strength R p0.2 : 160 ~ 280MPa, tensile strength Rm: 280 ~ 400MPa, elongation after fracture A> 50%, grain size 6.0 ~ 9.0; the leader material is TA1, the thickness difference between the leader and the hot-rolled titanium coil is ≤ 0.6mm, the leader width is 30 ~ 50mm wider than the hot-rolled titanium coil, and the leader length is 15 ~ 20m.

5. The method for rolling wide titanium strip with an 18-high single-stand rolling mill at low cost according to claim 1, characterized in that: The front and rear tensions of the rolling process in step S2 refer to the yield strength R of the titanium coil. p0.2 , front tension is (0.3~0.5)xR p0.2 x thickness x width, post tension is (0.2~0.4) x R p0.2 x thickness´ width.

6. The method for rolling wide titanium strip with an 18-high single-stand mill at low cost according to claim 5, characterized in that: In step S2, the front and rear tension coefficients of the first and last passes are 0.3 and 0.2 respectively; when the thickness of the titanium coil is less than 0.6 mm, the front and rear tension coefficients are 0.4 and 0.3 respectively.

7. The method for rolling wide titanium strip with an 18-high single-stand mill at low cost according to claim 1, characterized in that: In step S3, the degreasing speed is controlled at 20-30 m / min, and the speed is reduced by 30% at the beginning and end of the roll by 20 m; the unwinding tension is (1.2-3.5) x thickness x width, and the winding tension is (1.5-4.0) x thickness x width.

8. The method for rolling wide titanium strip with an 18-high single-stand mill at low cost according to claim 1, characterized in that: In step S4, three-stage heating is adopted. In the first stage, the furnace temperature is raised to 200°C at a rate of 100°C / s and kept warm for 6 to 8 hours. In the second stage, the furnace temperature is raised to 450 to 480°C at a rate of 90 to 120°C / s and kept warm for 10 to 12 hours. In the third stage, the furnace temperature is raised to 600 to 650°C at a rate of 10 to 15°C / s and kept warm for 12 to 15 hours.

9. The method for rolling wide titanium strip with an 18-high single-stand mill at low cost according to claim 1, characterized in that: The initial vacuum degree of the vacuum annealing furnace in step S4 is ≤1x10 -2 Pa, the heating process requires the vacuum degree in the furnace to be ≤5x10 -2 Pa.

10. The method for rolling wide titanium strips with an 18-high single-stand mill at low cost according to claim 1, characterized in that: The tension in step S5 is (0.5-0.7) x R p0.2 x thickness x width, the tensile deformation is controlled according to 0.2%~0.5%, the tensile deformation of titanium coil with thickness of 0.3~1.0mm is 0.2%~0.30%, the tensile speed is 30~50m / min, the tensile deformation of titanium coil with thickness of 1.0~2.5mm is 0.35%~0.5%, the tensile speed is 40~70m / min.

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