Method for hot continuous rolling of commercial pure titanium without post-process annealing

Abstract

The present application belongs to the technical field of industrial pure titanium rolling, and relates to a hot continuous rolling method of industrial pure titanium without post-process annealing, comprising the following steps: (1) heating and keeping temperature of the industrial pure titanium slab; (2) rolling the industrial pure titanium slab by using a rough rolling mill to obtain an intermediate slab; (3) rolling the intermediate slab by using a finishing rolling mill to obtain an industrial pure titanium strip; (4) cooling the industrial pure titanium strip during the conveying process on a laminar flow cooling roller way, and winding the strip into an industrial pure titanium coil by using a coiling machine; and (5) quickly placing the industrial pure titanium coil into a hot coil area for slow cooling. The hot continuous rolling method of industrial pure titanium without post-process annealing can eliminate the annealing process before cold rolling of the industrial pure titanium strip, and directly perform pickling and cold rolling, so that the yield and production efficiency of the cold rolled titanium strip are improved, energy is saved, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of industrial pure titanium rolling technology, and relates to a hot continuous rolling method for industrial pure titanium that eliminates the need for subsequent annealing processes. In particular, it relates to a technology that industrial pure titanium produced on a hot continuous rolling production line does not require annealing before cold rolling. Background Technology

[0002] Titanium and titanium alloys possess properties such as high specific strength, high and low temperature resistance, corrosion resistance, non-magnetic nature, and non-toxicity. They are widely used in aerospace, aviation, marine, petroleum, chemical, metallurgical, power, construction, medical, and sports industries, and are known as "space metal," "marine metal," and "strategic metal." Cold-rolled titanium strip accounts for approximately 60% of the total titanium processed materials. It can be used directly or processed into welded pipes to manufacture plate heat exchangers and heat exchange tubes, with applications in oil refineries, coastal power plants, offshore drilling platforms, and seawater desalination.

[0003] Before implementing this invention patent, the traditional production process of cold-rolled titanium strip was as follows: titanium billet → heating → rough rolling on a hot strip mill or hot roll mill → finish rolling → coiling → annealing of hot-rolled titanium strip → shot blasting → pickling → cold rolling → degreasing → annealing of cold-rolled titanium strip → finishing. According to this process, the hot-rolled titanium strip produced on the hot strip mill or hot roll mill production line must first be annealed before entering the cold rolling production line. This prolongs the entire production time of cold-rolled titanium strip, reduces production efficiency, increases energy consumption, and raises production costs.

[0004] High production costs are a common technical challenge faced by the titanium processing industry. New technologies are urgently needed in the production of hot and cold rolled titanium strips to increase the output and efficiency of cold rolled titanium strips, save energy, and reduce production costs. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing an industrial pure titanium hot continuous rolling method that eliminates the need for subsequent annealing processes.

[0006] Specifically, the hot continuous rolling method for industrial pure titanium without post-process annealing of the present invention includes:

[0007] (1) Heating and heat-preserving industrial pure titanium slabs;

[0008] (2) An intermediate billet is obtained by rolling industrial pure titanium slabs using a roughing mill;

[0009] (3) The intermediate billet is rolled by a finishing mill to obtain industrial pure titanium strip;

[0010] (4) The industrial pure titanium strip is cooled during transportation on the laminar flow cooling roller conveyor and is wound into an industrial pure titanium coil by a coiler;

[0011] (5) Quickly place the industrial pure titanium coil into the hot coil area for slow cooling.

[0012] In the above-mentioned hot continuous rolling method for industrial pure titanium without post-process annealing, in step (1), the heating is carried out in a heating furnace, the heating rate is 18-28℃ / h, the heating temperature is 775-795℃, and the holding time is 160-190min.

[0013] The above-mentioned hot continuous rolling method for industrial pure titanium without subsequent annealing processes involves 5 passes in the rough rolling stage, with the following process parameters for each pass:

[0014] Rolling passes First round Second lane 3rd lane 4th lane 5th course Rolling temperature (°C) 766-786 761-781 757-777 751-771 746-766 Rolling speed (m / s) 3.5-4.5 3.9-4.9 4.1-5.1 4.5-5.5 5.6-6.6 Absolute reduction (mm) 23.8-32.3 30.7-40.0 28.2-37.3 24.8-33.9 22.5-31.7 .

[0015] The above-mentioned hot continuous rolling method for industrial pure titanium without post-process annealing, wherein the finishing rolling is performed using a 7-stand finishing mill, and the finishing rolling process parameters are as follows:

[0016] Rack number F1 F2 F3 F4 F5 F6 F7 Rolling temperature (°C) 710-730 703-723 694-714 686-706 677-697 663-683 650-670 Rolling speed (m / s) 1.5-1.7 1.8-2.0 2.7-2.9 3.5-3.7 4.4-4.6 5.1-5.3 5.7-5.9 Absolute reduction (mm) 10.5-14.8 6.8-10.6 4.3-6.3 2.5-3.6 1.3-2.0 0.6-1.2 0.5-0.8 .

[0017] In the above-mentioned hot continuous rolling method for industrial pure titanium without subsequent annealing, in step (4), the cooling rate is 2.096-2.169℃ / s, and the temperature after cooling is 620-640℃.

[0018] In the above-mentioned hot rolling method for industrial pure titanium without subsequent annealing, the temperature of the hot rolling zone is 550-650℃, and the slow cooling time is 24-48 hours.

[0019] The above-mentioned hot continuous rolling method for industrial pure titanium without subsequent annealing processes includes the following grades of industrial pure titanium: TA0, TA1, TA2, TA3, and TA4.

[0020] The above-mentioned hot continuous rolling method for industrial pure titanium without subsequent annealing process, wherein the industrial pure titanium slab is a forged titanium slab suitable for hot continuous rolling production or a titanium slab produced by an electron beam cooling furnace.

[0021] The above-mentioned hot continuous rolling method for industrial pure titanium without subsequent annealing processes uses a pusher furnace, a walking beam furnace, a trolley furnace, or a roller hearth furnace.

[0022] In the above-mentioned hot continuous rolling method for industrial pure titanium without subsequent annealing, the heating furnace is heated by coal gas, natural gas, or electricity.

[0023] The technical solution of the present invention has the following beneficial effects:

[0024] The present invention provides a hot continuous rolling method for industrial pure titanium without post-process annealing. By controlling process parameters such as the heating rate, heating temperature, holding time, rolling temperature, rolling speed, absolute reduction, cooling rate and coiling temperature of the industrial pure titanium strip, and cooling rate of the industrial pure titanium coil, the mechanical properties of hot-rolled (R)TA1, TA2, and TA3 industrial pure titanium strips meet the requirements of the annealed (M) state. Therefore, the annealing process before cold rolling of industrial pure titanium strip can be eliminated, and it can be directly pickled and cold rolled, thereby improving the output and production efficiency of cold-rolled titanium strip, saving energy, and reducing production costs. Detailed Implementation

[0025] To fully understand the purpose, features, and effects of this invention, the following detailed embodiments are provided. Except as described below, the process methods of this invention employ conventional methods or apparatus in the art. Unless otherwise specified, the terms and expressions used below have the meanings commonly understood by those skilled in the art.

[0026] When a range of values ​​is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0027] Specifically, the hot continuous rolling method for industrial pure titanium without post-process annealing of the present invention includes:

[0028] (1) Heating and heat-preserving industrial pure titanium slabs;

[0029] (2) An intermediate billet is obtained by rolling industrial pure titanium slabs using a roughing mill;

[0030] (3) The intermediate billet is rolled by a finishing mill to obtain industrial pure titanium strip;

[0031] (4) The industrial pure titanium strip is cooled during transportation on the laminar flow cooling roller conveyor and is wound into an industrial pure titanium coil by a coiler;

[0032] (5) Quickly place the industrial pure titanium coil into the hot coil area for slow cooling.

[0033] The present invention provides an industrial pure titanium hot continuous rolling method that eliminates the need for post-process annealing. The hot-rolled titanium strip produced on the hot continuous rolling production line does not require annealing and can be directly put into the cold rolling production line, thereby shortening the overall production time of cold-rolled titanium strip, improving production efficiency, reducing energy consumption, and lowering production costs.

[0034] In some preferred embodiments, the hot continuous rolling method for industrial pure titanium without subsequent annealing of the present invention includes the following steps.

[0035] (1) Heat and keep the industrial pure titanium slab warm.

[0036] To achieve high-quality, high-efficiency, and high-reliability heating of industrial pure titanium slabs, the heating rate is controlled at 18-28℃ / h, the heating temperature is controlled at 775-795℃, and the holding time is controlled at 160-190min, thus laying the technological foundation for finally achieving annealing without subsequent processes.

[0037] Practical experience has shown that if the heating rate of industrial pure titanium slabs is lower than 18℃ / h, the heating efficiency will decrease. Industrial pure titanium has a low thermal conductivity, approximately 1 / 4 that of nickel, 1 / 5 that of iron, and 1 / 14 that of aluminum. If the heating rate of industrial pure titanium slabs exceeds 28℃ / h, the internal and external temperature gradients of the slab will be large, easily generating thermal stress. High thermal stress poses a risk of slab breakage within the heating furnace. Taking all these factors into consideration, the optimal heating rate for industrial pure titanium slabs is determined to be 18-28℃ / h.

[0038] Titanium exhibits a strong affinity for oxygen at high temperatures. During the initial heating phase of industrial pure titanium slabs, an oxide film forms on the surface due to oxidation. When heated above 500℃, this titanium oxide film becomes porous, thickens, and is easily peeled off. Oxygen diffuses continuously into the substrate through the pores in the film, forming a hard and brittle layer inside the titanium, reducing its plasticity. Above 650℃, the titanium-oxygen reaction is intense; above 700℃, it also reacts with nitrogen, forming a surface absorbent layer. This absorbent layer deteriorates the deformation properties of industrial pure titanium. Therefore, to reduce the absorbent tendency of industrial pure titanium slabs and improve their thermoplasticity, heating should be performed at the lowest possible temperature. However, if the heating temperature is too low, the deformation resistance of the industrial pure titanium slab will increase, increasing the mill load. Considering all these factors, the heating temperature for industrial pure titanium slabs is determined to be 775-795℃.

[0039] Industrial pure titanium exists as a close-packed hexagonal α phase at room temperature, transforming into a body-centered cubic β phase at 882℃. Hot deformation in the β phase region increases grain size and decreases plasticity, while hot deformation in the α phase region, preferably at a low temperature, reduces grain size and increases plasticity. Determining the heating temperature of industrial pure titanium slabs to 775-795℃ ensures complete hot deformation within the α phase region, laying a solid technological foundation for achieving a uniform, fine-grained structure and high plasticity in the finished industrial pure titanium product.

[0040] If the holding time for industrial pure titanium slabs is less than 160 minutes, the temperature gradient across the slab cross-section will be large, easily generating thermal stress and hot cracks, leading to cracking defects during rolling. If the holding time is longer than 190 minutes, the gas-absorbing layer on the slab surface will thicken, increasing heating energy consumption. Taking all factors into consideration, the holding time for industrial pure titanium slabs is determined to be 160-190 minutes.

[0041] The grades of industrial pure titanium include, but are not limited to: TA0, TA1, TA2, TA3, and TA4.

[0042] Preferably, the industrial pure titanium slab has a thickness of 160-230 mm, a width of 1000-2100 mm, and a length of 5000-10000 mm. It is a forged titanium slab suitable for hot continuous rolling or a titanium slab produced by an electron beam cooling furnace.

[0043] Preferably, the heating is carried out in a heating furnace, which is a pusher furnace, a walking beam furnace, a trolley furnace, or a roller hearth furnace. The heating furnace uses coal gas, natural gas, or electricity for heating.

[0044] (2) The industrial pure titanium slab is rolled by a roughing mill to obtain an intermediate slab.

[0045] Preferably, the roughing process consists of 5 passes, and the process parameters for each pass are shown in Table 1.

[0046] Table 1. Rough rolling process parameters for industrial pure titanium slabs

[0047] Rolling passes First round Second lane 3rd lane 4th lane 5th course Rolling temperature (°C) 766-786 761-781 757-777 751-771 746-766 Rolling speed (m / s) 3.5-4.5 3.9-4.9 4.1-5.1 4.5-5.5 5.6-6.6 Absolute reduction (mm) 23.8-32.3 30.7-40.0 28.2-37.3 24.8-33.9 22.5-31.7

[0048] Practice has shown that if the rolling temperature of industrial pure titanium slabs is lower than the lower limit specified in Table 1, the deformation resistance and load of the roughing mill increase sharply, affecting equipment safety; if the rolling temperature is higher than the upper limit specified in Table 1, the grain size of industrial pure titanium increases and its plasticity decreases. Taking all the above factors into consideration, the rolling temperatures for the five passes of roughing industrial pure titanium slabs are determined to be 766-786℃, 761-781℃, 757-777℃, 751-771℃, and 746-766℃, respectively.

[0049] If the rolling speed of industrial pure titanium slabs is lower than the lower limit specified in Table 1, the rolling efficiency of the roughing mill will decrease, reducing output. If the rolling speed is higher than the upper limit specified in Table 1, it will not only increase the deformation resistance and load of the roughing mill, but also cause excessive local or overall temperature rise of the slab due to deformation heat effects, resulting in uneven microstructure and overall properties. Taking all the above factors into consideration, the rolling speeds for the five passes of roughing industrial pure titanium slabs are determined to be 3.5-4.5 m / s, 3.9-4.9 m / s, 4.1-5.1 m / s, 4.5-5.5 m / s, and 5.6-6.6 m / s, respectively.

[0050] If the absolute reduction of industrial pure titanium slab is lower than the lower limit specified in Table 1, grain inhomogeneity will occur, reducing plasticity. If the absolute reduction is higher than the upper limit specified in Table 1, it will not only increase the deformation resistance and load of the roughing mill, but also cause head-up phenomenon, and in severe cases, "roll wrapping" accidents may occur, leading to equipment hazards. Taking all the above factors into consideration, the absolute reduction of the five passes of roughing of industrial pure titanium slab is determined to be 23.8-32.3mm, 30.7-40.0mm, 28.2-37.3mm, 24.8-33.9mm, and 22.5-31.7mm respectively.

[0051] Preferably, the industrial pure titanium slab is rough rolled to obtain an intermediate slab with a thickness of 30-45 mm.

[0052] (3) The intermediate billet is rolled by a finishing mill to obtain industrial pure titanium strip.

[0053] Preferably, the finishing rolling is carried out using a 7-stand finishing mill, and the finishing rolling process parameters are shown in Table 2.

[0054] Table 2 Finishing process parameters for industrial pure titanium strip

[0055] Rack number F1 F2 F3 F4 F5 F6 F7 Rolling temperature (°C) 710-730 703-723 694-714 686-706 677-697 663-683 650-670 Rolling speed (m / s) 1.5-1.7 1.8-2.0 2.7-2.9 3.5-3.7 4.4-4.6 5.1-5.3 5.7-5.9 Absolute reduction (mm) 10.5-14.8 6.8-10.6 4.3-6.3 2.5-3.6 1.3-2.0 0.6-1.2 0.5-0.8

[0056] Practice has shown that if the rolling temperature of industrial pure titanium strip is lower than the lower limit specified in Table 2, the deformation resistance and load of each stand in the finishing mill will increase sharply, affecting equipment safety; if the rolling temperature is higher than the upper limit specified in Table 2, the grain size of the industrial pure titanium strip will increase and its plasticity will decrease. Taking all the above factors into consideration, the rolling temperatures of each stand in the finishing mill of industrial pure titanium strip are determined to be 710-730℃, 703-723℃, 694-714℃, 686-706℃, 677-697℃, 663-683℃, and 650-670℃, respectively.

[0057] If the rolling speed of industrial pure titanium strip is lower than the lower limit specified in Table 2, the rolling efficiency will decrease, reducing output. If the rolling speed is higher than the upper limit specified in Table 2, it will not only increase the deformation resistance and load of each stand in the finishing mill, but also cause excessive local or overall temperature rise of the industrial pure titanium strip due to deformation heat effect, resulting in uneven microstructure and overall properties. Taking all the above factors into consideration, the rolling speeds of each stand in the finishing mill of industrial pure titanium strip are determined to be 1.5-1.7 m / s, 1.8-2.0 m / s, 2.7-2.9 m / s, 3.5-3.7 m / s, 4.4-4.6 m / s, 5.1-5.3 m / s, and 5.7-5.9 m / s, respectively.

[0058] If the absolute reduction of industrial pure titanium strip is lower than the lower limit specified in Table 2, grain inhomogeneity will occur, reducing plasticity. If the absolute reduction is higher than the upper limit specified in Table 2, the deformation resistance and load of each stand in the finishing mill will increase, leading to potential equipment hazards. Taking all factors into consideration, the absolute reduction of each stand in the finishing mill for industrial pure titanium strip is determined to be 10.5-14.8 mm, 6.8-10.6 mm, 4.3-6.3 mm, 2.5-3.6 mm, 1.3-2.0 mm, 0.6-1.2 mm, and 0.5-0.8 mm, respectively.

[0059] Further preferred, the intermediate billet is rolled by a finishing mill to obtain an industrial pure titanium strip with a thickness of 2.0-8.0 mm and a width of 1000-2100 mm.

[0060] (4) The industrial pure titanium strip is cooled during transport on the laminar flow cooling roller conveyor and is wound into an industrial pure titanium coil by a coiler.

[0061] Preferably, the cooling rate is 2.096-2.169℃ / s, and the temperature after cooling is 620-640℃. This allows for reasonable control of the strength and improves the plasticity of the industrial pure titanium strip, which is one of the important measures to achieve annealing without subsequent processes. At the same time, the strength-plasticity product of the industrial pure titanium strip can be controlled within the optimal range.

[0062] Furthermore, practical experience has shown that when the cooling rate is less than 2.096℃ / s, the temperature after cooling will be higher than the target of 640℃; when the cooling rate is greater than 2.169℃ / s, the temperature after cooling will be lower than the target of 620℃. When the temperature after cooling is lower than 620℃, the strength of the industrial pure titanium strip increases while its plasticity decreases; when the temperature after cooling is higher than 640℃, the strength of the industrial pure titanium strip decreases while its strength-plasticity product decreases.

[0063] (5) Quickly place the industrial pure titanium coil into the hot coil area for slow cooling.

[0064] Preferably, the temperature of the hot-rolling zone is 550-650℃, and the slow cooling time is 24-48 hours.

[0065] By controlling the temperature of the hot-rolling zone and the slow cooling time within the above-mentioned range, this invention can reasonably control the strength of industrial pure titanium strip and improve its plasticity. It is one of the important measures to achieve the elimination of subsequent annealing processes. At the same time, it can control the strength-plasticity product of industrial pure titanium strip within the optimal range without reducing production efficiency.

[0066] Furthermore, practical experience has shown that when the temperature in the hot-rolling zone is below 550℃, the strength of the industrial pure titanium strip increases while its plasticity decreases; conversely, when the temperature in the hot-rolling zone is above 650℃, the strength and strength-ductility product of the industrial pure titanium strip decrease. When the slow cooling time is less than 24 hours, the microstructure of the industrial pure titanium strip becomes uneven, and its plasticity decreases; when the slow cooling time is longer than 48 hours, production efficiency is reduced.

[0067] The measured properties of TA1, TA2, and TA3 industrial pure titanium strips produced according to the industrial pure titanium hot continuous rolling technology of the present invention without post-process annealing are compared with the properties specified in GB / T 3621-2007 "Titanium and Titanium Alloy Plates" in Tables 3, 4, and 5, respectively.

[0068] Table 3 Comparison of Measured Performance and Standard Performance of TA1 Industrial Pure Titanium Strip

[0069]

[0070] Table 4 Comparison of Measured Performance and Standard Performance of TA2 Industrial Pure Titanium Strip

[0071]

[0072] Table 5 Comparison of Measured Performance and Standard Performance of TA3 Industrial Pure Titanium Strip

[0073]

[0074] As can be seen from Tables 3, 4 and 5, the hot-rolled (R)TA1, TA2 and TA3 industrial pure titanium strips produced according to the technology of this invention have yield strength Rp0.2, tensile strength Rm, elongation A and 105° cold bending performance, which meet the corresponding performance requirements of annealed (M) in GB / T 3621-2007 "Titanium and Titanium Alloy Plates". Therefore, the annealing process before cold rolling of industrial pure titanium strips can be eliminated, and they can be directly pickled and cold rolled, thereby improving the output and production efficiency of cold-rolled titanium strips, saving energy and reducing production costs.

[0075] As can be seen from Tables 3, 4, and 5, the hot-rolled (R)TA1, TA2, and TA3 industrial pure titanium strips produced according to the technology of this invention have superior cold bending performance. Specifically, the TA1 industrial pure titanium strip exhibits excellent cold bending performance at 105° and 180° d=0, while the TA2 and TA3 industrial pure titanium strips exhibit excellent cold bending performance at 105° and 180° d=T. The industrial pure titanium strips of this invention possess a moderate strength-ductility product, with the strength-ductility products of TA1, TA2, and TA3 being 12.8-19.9, 12.9-17.2, and 14.0-17.9 GPa·%, respectively.

[0076] Example

[0077] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments, unless otherwise specified, are performed according to conventional methods and conditions.

[0078] Example 1

[0079] This embodiment describes a hot rolling technology that eliminates the need for subsequent annealing processes when producing TA1 industrial pure titanium strip on a 1549mm hot rolling production line.

[0080] (1) Heating

[0081] A TA1 industrial pure titanium slab (EB slab) with a thickness of 160 mm, a width of 1235 mm, and a length of 7968 mm is loaded into a walking beam furnace heated by natural gas. The slab is heated to 793 °C at a heating rate of 20 °C / h and held at that temperature for 188 min.

[0082] (2) Rough rolling

[0083] After the EB billet exits the furnace, it is rough rolled according to the process in Table 6 to obtain an intermediate billet with a thickness of 30 mm.

[0084] Table 6. Rough rolling process parameters of TA1 industrial pure titanium billets in Example 1

[0085] Rolling passes First round Second lane 3rd lane 4th lane 5th course Rolling temperature (°C) 783 779 776 768 762 Rolling speed (m / s) 4.32 4.86 5.05 5.48 6.33 Absolute reduction (mm) 23.86 31.89 28.65 24.98 22.62

[0086] (3) Finish rolling

[0087] The intermediate billet enters the 7-stand finishing mill for rolling. The finishing mill process parameters are shown in Table 7.

[0088] Table 7. Finishing process parameters of TA1 industrial pure titanium strip in Example 1

[0089] Rack number F1 F2 F3 F4 F5 F6 F7 Rolling temperature (°C) 728 720 711 703 693 679 688 Rolling speed (m / s) 1.63 1.98 2.83 3.66 4.59 5.28 5.81 Absolute reduction (mm) 10.58 7.09 5.03 2.57 1.52 0.70 0.51

[0090] TAl industrial pure titanium strip with a thickness of 2.0 mm and a width of 1230 mm was obtained by rolling with a precision rolling mill.

[0091] (4) Cooling and winding of industrial pure titanium strips from TA1

[0092] The TA1 industrial pure titanium strip rolled from the finishing mill is cooled to 622°C at a cooling rate of 2.166°C / s during its transport on the laminar flow cooling roller conveyor, and is then wound into industrial pure titanium coils by a coiler. That is, the coiling temperature of the TA1 industrial pure titanium strip is 622°C.

[0093] (5) Cooling of TAl industrial pure titanium coil

[0094] The TA1 industrial pure titanium coil was quickly placed in the hot-rolling area for slow cooling for 39 hours, with the temperature of the hot-rolling area reaching 611℃.

[0095] (6) Properties of TAl industrial pure titanium strip

[0096] Table 8 compares the measured properties of TA1 industrial pure titanium strip produced by the hot continuous rolling technology for industrial pure titanium without post-process annealing according to this embodiment with the properties specified in GB / T 3621-2007 "Titanium and Titanium Alloy Plates".

[0097] Table 8. Comparison of the measured performance of TA1 industrial pure titanium strip in Example 1 with the standard.

[0098]

[0099] As can be seen from Table 8, the yield strength Rp0.2, tensile strength Rm, elongation A, and 105° cold bending performance of the hot-rolled (R) TA1 industrial pure titanium strip produced according to the technology of this embodiment meet the corresponding performance requirements of the annealed (M) state in GB / T3621-2007 "Titanium and Titanium Alloy Plates". Therefore, the annealing process before cold rolling of TA1 industrial pure titanium strip can be eliminated, and it can be directly pickled and cold rolled, thereby improving the output and production efficiency of TA1 cold-rolled titanium strip, saving energy, and reducing production costs.

[0100] As can be seen from Table 8, the hot-rolled (R)TA1 industrial pure titanium strip produced according to the technology of this embodiment has better cold bending performance, with excellent cold bending performance at 105° and 180° d=0. The TA1 industrial pure titanium strip of this embodiment has a moderate strength-ductility product (15.6 GPa·%).

[0101] Example 2

[0102] This embodiment describes a hot rolling technology that eliminates the need for subsequent annealing processes when producing TA2 industrial pure titanium strip on a 2250mm hot rolling production line.

[0103] (1) Heating

[0104] A TA2 industrial pure titanium slab (forged titanium slab) with a thickness of 180 mm, a width of 1925 mm, and a length of 6510 mm is loaded into a walking beam furnace heated by natural gas. The slab is heated to 788°C at a heating rate of 23°C / h and held at that temperature for 180 min.

[0105] (2) Rough rolling

[0106] After the forged titanium billet exits the furnace, it is rough rolled according to the process in Table 9 to obtain an intermediate billet with a thickness of 40 mm.

[0107] Table 9. Rough rolling process parameters of TA2 industrial pure titanium billet in Example 2.

[0108] Rolling passes First round Second lane 3rd lane 4th lane 5th course Rolling temperature (°C) 778 770 766 760 753 Rolling speed (m / s) 3.98 4.31 4.56 5.03 6.08 Absolute reduction (mm) 24.28 33.70 28.81 29.91 23.30

[0109] (3) Finish rolling

[0110] The intermediate billet enters the 7-stand finishing mill for rolling. The finishing mill process parameters are shown in Table 10.

[0111] Table 10. Finishing process parameters of TA2 industrial pure titanium strip in Example 2

[0112] Rack number F1 F2 F3 F4 F5 F6 F7 Rolling temperature (°C) 722 715 708 701 686 671 659 Rolling speed (m / s) 1.58 1.91 2.78 3.62 4.53 5.21 5.78 Absolute reduction (mm) 12.73 9.62 5.23 3.02 1.68 1.01 0.69

[0113] TA2 industrial pure titanium strip with a thickness of 6.0 mm and a width of 1920 mm was obtained by rolling with a precision rolling mill.

[0114] (4) Cooling and winding of TA2 industrial pure titanium strip

[0115] The TA2 industrial pure titanium strip rolled from the finishing mill is cooled to 628°C at a cooling rate of 2.103°C / s during its transport on the laminar flow cooling roller conveyor, and is then wound into industrial pure titanium coils by a coiler. That is, the coiling temperature of the TA2 industrial pure titanium strip is 628°C.

[0116] (5) Cooling of TA2 industrial pure titanium coil

[0117] The TA2 industrial pure titanium coil was quickly placed in the hot-rolling area for slow cooling for 32 hours, with the temperature of the hot-rolling area reaching 603℃.

[0118] (6) Performance of TA2 industrial pure titanium strip

[0119] Table 11 compares the measured properties of TA2 industrial pure titanium strip produced by the hot continuous rolling technology for industrial pure titanium without post-process annealing according to this embodiment with the properties specified in GB / T 3621-2007 "Titanium and Titanium Alloy Plates".

[0120] As can be seen from Table 11, the yield strength Rp0.2, tensile strength Rm, elongation A, and 105° cold bending performance of the hot-rolled (R)TA2 industrial pure titanium strip produced according to the technology of this embodiment meet the requirements of the comparison between the measured performance of TA2 industrial pure titanium strip and the standard in Example 2 of Table 11 of GB / T.

[0121]

[0122] The corresponding performance requirements of the annealed state (M) in 3621-2007 "Titanium and Titanium Alloy Sheets" can eliminate the annealing process before cold rolling of TA2 industrial pure titanium strip, and directly pickle and cold roll it, thereby improving the output and production efficiency of TA2 cold rolled titanium strip, saving energy and reducing production costs.

[0123] As can be seen from Table 11, the hot-rolled (R)TA2 industrial pure titanium strip produced according to the technology of this embodiment has better cold bending performance, and its 105° and 180° d=T cold bending is intact. The TA2 industrial pure titanium strip of this embodiment has a moderate strength-ductility product (15.3 GPa·%).

[0124] Example 3

[0125] This embodiment describes a hot rolling technology that eliminates the need for subsequent annealing processes when producing TA3 industrial pure titanium strip on a 2250mm hot rolling production line.

[0126] (1) Heating

[0127] A TA3 industrial pure titanium slab (forged titanium slab) with a thickness of 206 mm, a width of 1930 mm, and a length of 5730 mm was loaded into a walking beam furnace heated by natural gas. The slab was heated to 778 °C at a heating rate of 26 °C / h and held at that temperature for 163 min.

[0128] (2) Rough rolling

[0129] After the forged titanium billet exits the furnace, it is rough rolled according to the process in Table 12 to obtain an intermediate billet with a thickness of 43 mm.

[0130] Table 12 Rough rolling process parameters of TA3 industrial pure titanium billet in Example 3

[0131] Rolling passes First round Second lane 3rd lane 4th lane 5th course Rolling temperature (°C) 768 763 759 755 749 Rolling speed (m / s) 3.59 3.96 4.13 4.56 5.73 Absolute reduction (mm) 30.25 37.73 33.21 32.93 28.88

[0132] (3) Finish rolling

[0133] The intermediate billet enters the 7-stand finishing mill for rolling. The finishing mill process parameters are shown in Table 13.

[0134] Table 13. Finishing process parameters of TA3 industrial pure titanium strip in Example 3

[0135] Rack number F1 F2 F3 F4 F5 F6 F7 Rolling temperature (°C) 713 706 696 689 680 665 653 Rolling speed (m / s) 1.51 1.82 2.73 3.55 4.43 5.12 5.75 Absolute reduction (mm) 12.98 9.86 5.28 3.15 1.87 1.08 0.78

[0136] TA3 industrial pure titanium strip with a thickness of 8.0 mm and a width of 1920 mm was obtained by rolling with a precision rolling mill.

[0137] (4) Cooling and winding of TA3 industrial pure titanium strip

[0138] The TA3 industrial pure titanium strip rolled from the finishing mill is cooled to 636°C at a cooling rate of 2.099°C / s during its transport on the laminar flow cooling roller conveyor, and is then wound into industrial pure titanium coils by a coiler. That is, the coiling temperature of the TA3 industrial pure titanium strip is 636°C.

[0139] (5) Cooling of TA3 industrial pure titanium coil

[0140] The TA3 industrial pure titanium coil was quickly placed in the hot-rolling area for slow cooling for 28 hours, with the temperature of the hot-rolling area reaching 596℃.

[0141] (6) Performance of TA3 industrial pure titanium strip

[0142] Table 14 compares the measured properties of TA3 industrial pure titanium strip produced by the hot continuous rolling technology for industrial pure titanium without post-process annealing according to this embodiment with the properties specified in GB / T 3621-2007 "Titanium and Titanium Alloy Plates".

[0143] Table 14 Comparison of the measured performance of TA3 industrial pure titanium strip in Example 3 with the standard

[0144]

[0145] As can be seen from Table 14, the yield strength Rp0.2, tensile strength Rm, elongation A, and 105° cold bending performance of the hot-rolled (R) TA3 industrial pure titanium strip produced according to the technology of this embodiment meet the corresponding performance requirements of the annealed (M) state in GB / T3621-2007 "Titanium and Titanium Alloy Plates". Therefore, the annealing process before cold rolling of TA3 industrial pure titanium strip can be eliminated, and it can be directly pickled and cold rolled, thereby improving the output and production efficiency of TA3 cold-rolled titanium strip, saving energy, and reducing production costs.

[0146] As can be seen from Table 14, the hot-rolled (R)TA3 industrial pure titanium strip produced according to the technology of this embodiment has better cold bending performance, and its 105° and 180° d=T cold bending is intact. The TA3 industrial pure titanium strip of this embodiment has a moderate strength-ductility product (16.6 GPa·%).

[0147] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art should understand that these embodiments are merely illustrative of the invention and should not be construed as limiting its scope. It should be noted that any variations and substitutions equivalent to these embodiments should be considered to be covered within the scope of the claims. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for hot continuous rolling of industrial pure titanium without subsequent annealing processes, characterized in that, include: (1) Heating and heat preservation of industrial pure titanium slabs; (2) The industrial pure titanium slab is rolled using a roughing mill to obtain an intermediate slab; (3) The intermediate billet is rolled by a finishing mill to obtain industrial pure titanium strip; (4) The industrial pure titanium strip is cooled during transportation on the laminar flow cooling roller conveyor and is wound into industrial pure titanium coils by the coiler; The cooling rate is 2.096-2.169℃ / s, and the temperature after cooling is 620-640℃. (5) Quickly place the industrial pure titanium coil into the hot coil area for slow cooling; The temperature of the hot-rolling zone is 550-650℃, and the slow cooling time is 24-48 hours.

2. The industrial pure titanium hot continuous rolling method without post-process annealing as described in claim 1, characterized in that, In step (1), the heating is carried out in a heating furnace, the heating rate is 18-28℃ / h, the heating temperature is 775-795℃, and the holding time is 160-190min.

3. The industrial pure titanium hot continuous rolling method without subsequent annealing as described in claim 1, characterized in that, The roughing process consists of 5 passes, and the process parameters for each pass are as follows: 。 4. The industrial pure titanium hot continuous rolling method without subsequent annealing as described in claim 1, characterized in that, The finishing rolling is carried out using a 7-stand finishing mill, and the finishing rolling process parameters are as follows: 。 5. The industrial pure titanium hot continuous rolling method without subsequent annealing as described in claim 1, characterized in that, The grades of industrial pure titanium include: TA0, TA1, TA2, TA3, and TA4.

6. The industrial pure titanium hot continuous rolling method without post-process annealing as described in claim 1, characterized in that, The industrial pure titanium slab is a forged titanium slab suitable for hot continuous rolling or a titanium slab produced by an electron beam cooling furnace.

7. The method for hot continuous rolling of industrial pure titanium without subsequent annealing as described in claim 2, characterized in that, The heating furnace is a pusher furnace, a walking beam furnace, a trolley furnace, or a roller hearth furnace.

8. The industrial pure titanium hot continuous rolling method without post-process annealing as described in claim 2 or 7, characterized in that, The heating furnace is heated by coal gas, natural gas, or electricity.

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