Patent Application
20250019813
The present invention belongs to the technical field of titanium alloy material preparation, and relates to a titanium alloy medium-thickness plate for special vehicles, in particular to a thermal processing method for improving high-speed impact resistance of two-phase titanium alloy.
In order to improve the maneuverability, fuel efficiency and transportability of special vehicles, there is an increasing demand to reduce the weight of armor structures used in various applications such as tanks and helicopters. The application of titanium alloy armor has received increasing attention since its high specific strength, excellent mechanical properties and good bulletproof performance. In order to maintain high strength of the titanium alloy plate for special vehicles while maximizing the high-speed impact resistance thereof, it is necessary to the strictly control the thermal forming process and the heat treatment process during the thermal processing process.
Patent application CN 109590330A (Apr. 9, 2019) disclosed a rolling method of TC4ELI titanium alloy large-width thick plate, which uses two stages of heat treatment-rolling to roll a TC4ELI large-width thick plate, specifies parameters such as heating schedule, total deformation amount and final rolling temperature of the two stages of heat treatment-rolling. The method is characterized in that the temperature is controlled in stepwise during the heating process, and the temperature is increased to above the phase-transition temperature at the last one third of heating time, so that the basket-weave microstructure can be obtained. However, the impact toughness of the basket-weave microstructure type is low, which is not conducive to bulletproof protection.
Patent application CN 104874604A (Sep. 2, 2019) disclosed a large-width titanium alloy plate rolling method, which specifies the heating temperature, deformation amount, final rolling temperature, and cooling method after rolling during the rolling process of the two-phase titanium alloy large-width plate. The method is characterized in that the final rolling temperature is not lower than 200° C. below the phase-transition point, and the plate is rapidly cooled by means of water-cooling after rolling. However, the method does not involve the control of the deformation temperature during the rolling process, and the plate will undergo thermal deformation after rolling, which cannot guarantee the plate shape.
Patent application CN 103230936A (Aug. 7, 2013) disclosed a rolling method of TC4 titanium alloy large-width medium-thickness plates, which obtained a TC4 wide plate with low anisotropy and high comprehensive performance by means of controlling the rolling process. The method is characterized in that after the temperature is reduced to 910-900° C. in the rolling process, the plate blank is reheated in the furnace for temperature compensation, and the rolling is performed after the temperature is increased to 930-950° C. The method adopts a method of temperature compensation high-temperature rolling to reduce the requirements for the capability of the rolling mill equipment, but this method will have a negative impact on the product's performance.
Patent application CN102172638A (Sep. 7, 2011) disclosed a rolling method for controlling a camber of a titanium and titanium alloy thin plate. After high-temperature control rolling, a multi-pass small-variation deviation rectification rolling is performed when the temperature is reduced below 650° C. for correcting the plate shape. Since the low deformation temperature, the method will not play a significant effect on improving the microstructure and properties of the plate.
The technical problems to be solved by the present invention are that the existing two-phase titanium alloy plate is low in strength and poor in high-speed impact resistance.
The technical solution adopted by the present invention to solve the technical problems is a thermal processing method for improving high-speed impact resistance of a two-phase titanium alloy, including the following steps of:
In the above step a, the two-phase titanium alloy is a titanium alloy of Ti-4Al-1.5Cr-0.5Mo for special bulletproof armor for special vehicles, and the slab blank is obtained by forging the titanium alloy by means of a process combining high-low temperature upsetting-drawing with extended drawing.
In the above step a, a stepped electric heating furnace is used for heating.
In step a, a size of the two-phase titanium alloy slab blank is as follows: a thickness of 100-140 mm, a width of 800-1200 mm, and a length of 1200-2500 mm.
A size of the above two-phase titanium alloy slab blank after transverse rough rolling is as follows: a thickness of 60-90 mm, a width of 1200-2200 mm, and a length of 1200-2500 mm.
A size of the above two-phase titanium alloy slab blank after longitudinal rolling is as follows: a thickness of 6-20 mm, a width of 1200-2500 mm, and a length of 4000-12000 mm.
In above step b, a reversing mill is used to roll.
In above step c, the solution heat treatment is to perform heat preservation for 1-2 hours at a temperature of 850-900° C.
In above step c, the aging treatment is to perform heat preservation for 8-12 hours at a temperature of 500-600° C.
The present invention has the following beneficial effects:
The present invention adopts a manner of sectional heating. A lower preheating temperature (less than 850° C.) is set to avoid cracking caused by too large internal and external temperature difference during the heating process of the slab blank from room temperature; the temperature of 1050-1070° C. in the heating section can make the overall temperature of the slab blank rise to the temperature required for deformation, being conducive to the microstructure change during rolling; the temperature of 1040-1060° C. in the soaking section can further homogenize the temperature of each part of the slab blank. In combination with the rolling process of the present invention, that is, after sectional heating, a method of two-stage rolling in β phase region and α+β two-phase region are adopted to reduce the anisotropy of the transverse and longitudinal properties of the finished plate.
The present invention adopts large reduction rolling in the first stage of the rolling process within the β-phase region with a rolling temperature ranging from 990 to 1030° C.; since the fact that the temperature is high, it can ensure that the rolling mill has the conditions for large reduction rolling, and meanwhile, the large reduction deformation can effectively crush the coarse grain structure with full section. The present invention adopts two-phase region rolling deformation in the second stage of the rolling process within the α+β two-phase region with a deformation temperature ranging from 900 to 990° C.; the deformation in the temperature range can enable the microstructure to be transformed from the Widmanstatten microstructure to the basketweave and lamellar microstructure, which is beneficial to improve the high-speed impact resistance.
At the same time, the present invention adopts rapid cooling after rolling to avoid the formation of the secondary a phase, ensuring the strength of the material. The present invention adopts solution heat treatment and aging treatment to strengthening the material, further improving the strength of the material. The present invention combines the rolling process with rapid cooling after rolling, solution heat treatment, and aging treatment, which can ensure high strength and excellent high-speed impact resistance of the product, greatly improving the protective performance of the material. The titanium alloy for the special vehicles treated by the thermal processing method of the present invention has a strength greater than or equal to 1200 MPa, and has a dynamic compressive strength greater than or equal to 1700 MPa under the condition of strain rate greater than 3000 s−1.
The technical solution of the present invention can be implemented according to the following method.
A thermal processing method for improving high-speed impact resistance of a two-phase titanium alloy, includes the following steps of:
The two-phase titanium alloy of the present invention is a titanium alloy of Ti-4Al-1.5Cr-0.5Mo for special bulletproof armor for special vehicles, and the slab blank is obtained by forging the titanium alloy by means of a process combining high-low temperature upsetting-drawing with extended drawing.
In order to better control the heating temperature, in the above step a, a stepped electric heating furnace is preferably used for heating.
The size of a forged blank is calculated based on the size of the finished product and the deformation amount required for thermal processing. Therefore, it is preferred that in the above step a, the size of the two-phase titanium alloy slab blank is as follows: a thickness of 100-140 mm, a width of 800-1200 mm, and a length of 1200-2500 mm. Controlling the size is to control the deformation amount at each stage of thermal processing, which is an important means to realize microstructure performance control. Therefore, preferably, the size of the above two-phase titanium alloy slab blank after transverse rough rolling is as follows: a thickness of 60-90 mm, a width of 1200-2200 mm, and a length of 1200-2500 mm; and the size after longitudinal rolling is as follows: a thickness of 6-20 mm, a width of 1200-2500 mm, and a length of 4000-12000 mm.
In order to facilitate the achievement of reversing rolling, in the above step b, a reversing mill is preferably used to roll.
In order to further enhance the performance of the two-phase titanium alloy, preferably in the above step c, the solution heat treatment is to perform heat preservation for 1-2 hours at 850-900° C., and the aging treatment is to perform heat preservation for 8-12 hours at 500-600° C.
The present invention provides a high-low temperature upsetting-drawing process combined with an extended drawing process, which is not a limitation of the present invention.
The original size of the ingot is (Φ600−Φ650) mm×(1900-2100) mm, and the process combining high-low temperature upsetting-drawing with extended drawing is as follows:
(1) First forging of double upsetting combined with double drawing at high-temperatures: the ingot is heated to perform heat preservation at a temperature of 1010-1200° C. for 4-8 hours, the initial forging temperature is higher than or equal to 1000° C., the final forging temperature is higher than or equal to 780° C., and a process of double upsetting and double drawing is adopted. The upsetting-drawing process control is as follows: the ingot is first upset until its height is 950-1050 mm, then is drew back to its original height, followed by returning the ingot into the furnace for heat preservation for 2-4 hours, and then the ingot is taken out for upsetting-drawing again, where the ingot is upset until its height is 950-1050 mm, then is drew back to the original height. The drawing is performed according to “octagon deformation” with a unilateral reduction of less than or equal to 50 mm, and the ingot is removed for surface cleaning after first forging.
(2) Second forging of upsetting-drawing combined with upsetting-extended drawing at low-temperatures: the first forged ingot is heated to perform heat preservation at a temperature of 900-980° C. for 4-8 hours, the initial forging temperature is higher than or equal to 900° C., the final forging temperature is higher than or equal to 720° C., and a process of one upsetting and one drawing is adopted, and then is subject to extended drawing after secondary upsetting. The first upsetting-drawing process control is as follows: the ingot is first upset until its height is 1050-1150 mm, then is returned into the furnace for heat preservation for 2-4 hours, and then the ingot is taken out and drew back to its original height, where the drawing is performed according to “octagon deformation” with a unilateral reduction of less than or equal to 50 mm. The second upsetting-extended drawing process control is as follows: the ingot is first upset until its height is 1250-1300 mm, then is returned into the furnace for heat preservation for 2-4 hours, and then the ingot is taken out for extended drawing, where the extended drawing is performed according to “tetragonal deformation”. The size of an obtained blank is controlled to be of a thickness of 100-140 mm, a width of 800-1200 mm width, and a length of 1200-2500 mm.
The technical solutions and effects of the present invention are further illustrated below with reference to practical embodiments.
a. A titanium alloy rolled blank for special vehicles was used, and a size thereof was as follows: a thickness of 111 mm, a width of 990 mm, and a length of 1500 mm. A stepped electric heating furnace was used to heat the blank, and the temperature and heat preservation time of each section met the following conditions: heat preservation was performed at 800° C. for 20 minutes in the preheating section, heat preservation was performed at 1050° C. for 15 minutes in the heating section, and heat preservation was performed at 1050° C. for 80 minutes in the soaking section.
b. After the blank was cooled to the rolling temperature, the roller cooling water and the phosphorus removal water were turned off, and then the blank was quickly conveyed to a reversing mill for reversing rolling. First, β phase rough rolling was performed with lateral spread and large reduction at a rolling temperature of 1000° C., and the size of the rolled blank was of a thickness of 55 mm, a width of 2000 mm, and a length of 1550 mm. Then the blank was reversed, its temperature was determined using a handheld infrared thermometer, and two-phase region rolling was performed when the temperature reached 970° C.; and the size of the rolled blank was of a thickness of 8 mm, a width of 2000 mm, and a length of 12000 mm.
c. The rolled armor titanium alloy plate was rapidly water-cooled to 190° C., followed by solution heat treatment at 850° C. for 2 hours, and the aging treatment was performed at 500° C. for 8 hours after completion of the solution heat treatment.
The rolled blank in step a maybe obtained, but is not limited to, by the following forging process:
(1) Original size of the ingot was ¢630 mm×2020 mm. First forging of double upsetting combined with double drawing at high-temperatures: the ingot was heated to perform heat preservation at a temperature of 1100° C. for 6 hours, the initial forging temperature was 1050° C., the final forging temperature was 820° C., and a process of double upsetting and double drawing was adopted. The upsetting-drawing process control was as follows: the ingot was first upset until its height was 1050 mm, then was drew back to its original height of 2020 mm, followed by returning the ingot into the furnace for heat preservation for 4 hours, and then the ingot was taken out for upsetting-drawing again, of which the ingot was upset until its height was 950 mm, then was drew back to the original height of 2020 mm, and a ingot having a octagon cross section was obtained, where a unilateral reduction was 30 mm. The ingot was removed for surface cleaning after first forging.
(2) Second forging of upsetting-drawing combined with upsetting-extended drawing at low-temperatures: the first forged ingot was heated to perform heat preservation at a temperature of 950° C. for 6 hours, the initial forging temperature was 920° C., the final forging temperature was 750° C., and a process of one upsetting and one drawing combined with secondary upsetting-extended drawing was adopted. The first upsetting-drawing process control was as follows: the ingot was first upset until its height was 1150 mm, then was returned into the furnace for heat preservation for 4 hours, and then the ingot was taken out and drew back to its original height of 2020 mm, of which the drawing was performed according to “octagon deformation” with a unilateral reduction of 50 mm. The second upsetting-extended drawing process control was as follows: the ingot was first upset until its height was 1300 mm, then was returned into the furnace for heat preservation for 3 hours, and then the ingot was taken out for extended drawing, where the extended drawing was performed according to “tetragonal deformation”. The size of an obtained blank was controlled to be of a thickness of 120 mm, a width of 1050 mm width, and a length of 4800 mm. After oxide skin on the surface was milled, the obtained blank was equally divided into three parts along its length direction, and a rolled plate with a size of a thickness of 111 mm, a width of 990 mm, and a length of 1500 mm was obtained.
The microstructure of the titanium alloy plate for special vehicles finally obtained in Embodiment 1 is shown as
a. A titanium alloy rolled blank for special vehicles was used, and a size thereof was as follows: a thickness of 120 mm, a width of 1000 mm, and a length of 1300 mm. A stepped electric heating furnace was used to heat the blank, and the temperature and heat preservation time of each section met the following conditions: heat preservation was performed at 750° C. for 20 minutes in the preheating section, heat preservation was performed at 1050° C. for 20 minutes in the heating section, and heat preservation was performed at 1050° C. for 90 minutes in the soaking section.
b. After the blank was cooled to the rolling temperature, the roller cooling water and the phosphorus removal water were turned off, and then the blank was quickly conveyed to a reversing mill for reversing rolling. First, β phase rough rolling was performed with lateral spread and large reduction at a rolling temperature of 1000° C., and the size of the rolled blank was of a thickness of 50 mm, a width of 2200 mm, and a length of 1350 mm. Then the blank was reversed, its temperature was determined using a handheld infrared thermometer, and two-phase region rolling was performed when the temperature reached 950° C.; and the size of the rolled blank was of a thickness of 8 mm, a width of 2200 mm, and a length of 9000 mm.
c. The rolled armor titanium alloy plate was rapidly water-cooled to 185° C., followed by solution heat treatment at 900° C. for 2 hours, and the aging treatment was performed at 600° C. for 12 hours after completion of the solution heat treatment.
The rolled blank in step a maybe obtained, but is not limited to, by the following forging process:
(1) Original size of the ingot was Ø610 mm×1950 mm. First forging of double upsetting combined with double drawing at high-temperatures: the ingot was heated to perform heat preservation at a temperature of 1150° C. for 5 hours, the initial forging temperature was 1100° C., the final forging temperature was 870° C., and a process of double upsetting and double drawing was adopted. The upsetting-drawing process control was as follows: the ingot was first upset until its height was 1000 mm, then was drew back to its original height of 1950 mm, followed by returning the ingot into the furnace for heat preservation for 4 hours, and then the ingot was taken out for upsetting-drawing again, of which the ingot was upset until its height was 1000 mm, then was drew back to the original height of 1950 mm, and a ingot having a octagon cross section was obtained, where a unilateral reduction was 50 mm. The ingot was removed for surface cleaning after first forging.
(2) Second forging of upsetting-drawing combined with upsetting-extended drawing at low-temperatures: the first forged ingot was heated to perform heat preservation at a temperature of 980° C. for 5 hours, the initial forging temperature was 930° C., the final forging temperature was 780° C., and a process of one upsetting and one drawing combined with secondary upsetting-extended drawing was adopted. The first upsetting-drawing process control was as follows: the ingot was first upset until its height was 1050 mm, then was returned into the furnace for heat preservation for 4 hours, and then the ingot was taken out and drew back to its original height of 1950 mm, of which the drawing was performed according to “octagon deformation” with a unilateral reduction of 50 mm. The second upsetting-extended drawing process control was as follows: the ingot was first upset until its height was 1250 mm, then was returned into the furnace for heat preservation for 3 hours, and then the ingot was taken out for extended drawing, where the extended drawing was performed according to “tetragonal deformation”. The size of an obtained blank was controlled to be of a thickness of 130 mm, a width of 1100 mm width, and a length of 4200 mm. After oxide skin on the surface was milled, the obtained blank was equally divided into three parts along its length direction, and a rolled plate with a size of a thickness of 120 mm, a width of 1000 mm, and a length of 1300 mm was obtained.
The microstructure of the titanium alloy plate for special vehicles finally obtained in Embodiment 2 is shown as
a. A titanium alloy rolled blank for special vehicles was used, and a size thereof was as follows: a thickness of 100 mm, a width of 1100 mm, and a length of 1400 mm. A stepped electric heating furnace was used to heat the blank, and the temperature and heat preservation time of each section met the following conditions: heat preservation was performed at 670° C. for 20 minutes in the preheating section, heat preservation was performed at 1050° C. for 15 minutes in the heating section, and heat preservation was performed at 1070° C. for 80 minutes in the soaking section.
b. After the blank was cooled to the rolling temperature, the roller cooling water and the phosphorus removal water were turned off, and then the blank was quickly conveyed to a reversing mill for reversing rolling. First, β phase rough rolling was performed with lateral spread and large reduction at a rolling temperature of 1000° C., and the size of the rolled blank was of a thickness of 50 mm, a width of 2200 mm, and a length of 1450 mm. Then the blank was reversed, its temperature was determined using a handheld infrared thermometer, and two-phase region rolling was performed when the temperature reached 950° C.; and the size of the rolled blank was of a thickness of 8 mm, a width of 2200 mm, and a length of 9500 mm.
c. The rolled armor titanium alloy plate was rapidly water-cooled to 150° C., followed by solution heat treatment at 850° C. for 2 hours, and the aging treatment was performed at 550° C. for 12 hours after completion of the solution heat treatment.
The rolled blank in step a maybe obtained, but is not limited to, by the following forging process:
(1) Original size of the ingot was Ø630 mm×2000 mm. First forging of double upsetting combined with double drawing at high-temperatures: the ingot was heated to perform heat preservation at a temperature of 1050° C. for 6 hours, the initial forging temperature was 1000° C., the final forging temperature was 820° C., and a process of double upsetting and double drawing was adopted. The upsetting-drawing process control was as follows: the ingot was first upset until its height was 1000 mm, then was drew back to its original height of 2000 mm, followed by returning the ingot into the furnace for heat preservation for 6 hours, and then the ingot was taken out for upsetting-drawing again, of which the ingot was upset until its height was 1000 mm, then was drew back to the original height of 2000 mm, and a ingot having a octagon cross section was obtained, where a unilateral reduction was 30 mm. The ingot was removed for surface cleaning after first forging.
(2) Second forging of upsetting-drawing combined with upsetting-extended drawing at low-temperatures: the first forged ingot was heated to perform heat preservation at a temperature of 950° C. for 6 hours, the initial forging temperature was 920° C., the final forging temperature was 750° C., and a process of one upsetting and one drawing combined with secondary upsetting-extended drawing was adopted. The first upsetting-drawing process control was as follows: the ingot was first upset until its height was 950 mm, then was returned into the furnace for heat preservation for 4 hours, and then the ingot was taken out and drew back to its original height of 2000 mm, of which the drawing was performed according to “octagon deformation” with a unilateral reduction of 50 mm. The second upsetting-extended drawing process control was as follows: the ingot was first upset until its height was 1200 mm, then was returned into the furnace for heat preservation for 3 hours, and then the ingot was taken out for extended drawing, where the extended drawing was performed according to “tetragonal deformation”. The size of an obtained blank was controlled to be of a thickness of 110 mm, a width of 1200 mm width, and a length of 4500 mm. After oxide skin on the surface was milled, the obtained blank was equally divided into three parts along its length direction, and a rolled plate with a size of a thickness of 100 mm, a width of 1100 mm, and a length of 1400 mm was obtained.
The microstructure of the titanium alloy plate for special vehicles finally obtained in Embodiment 3 is shown as
Mechanical properties of the alloy plates obtained in Embodiments 1 to 3 were tested (two samples were tested according to Chinese national standard), and the test results are shown in Table 1.
It can be seen from Table 1 that the average tensile strength of the alloy plate obtained in Embodiment 1 was 1286 MPa, and the average dynamic compressive strength reached 1883 MPa under the condition of strain rate greater than 3000 s−1. The average tensile strength of the alloy plate obtained in Embodiment 2 was 1350 MPa, and the average dynamic compressive strength reached 2023 MPa under the condition of strain rate greater than 3000 s−1. The average tensile strength of the alloy plate obtained in Embodiment 3 was 1232 MPa, and the average dynamic compressive strength reached 1809 MPa under the condition of strain rate greater than 3000 s−1. The two-phase titanium alloy for special vehicles prepared by the thermal processing process of the present invention has high strength and excellent high-speed impact resistance, greatly improving the protective performance of the alloy.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202110906649.X | Aug 2021 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2022/103831 | 7/5/2022 | WO |
