Low-cost preparation method of titanium alloy plate

Abstract

The invention belongs to the technical field of titanium alloy plate processing, and particularly relates to a low-cost preparation method of a titanium alloy plate, which comprises the following steps: carrying out shot blasting treatment on an EB casting blank produced by a titanium alloy vacuum consumable skull furnace; the titanium alloy EB casting blank is heated to 30-50 DEG C above the phase transformation point, the heat preservation time is t, then thinning rolling is carried out, and when the surface temperature is reduced to 50-100 DEG C below the phase transformation point, the titanium alloy EB casting blank is remelted and heated to 30-50 DEG C above the phase transformation point, and then rolling is carried out; after the titanium alloy plate blank obtained after thinning rolling is cooled, the surface of the plate is checked, and the position with cracks on the surface is locally ground; removing an oxide layer on the surface of the titanium alloy plate blank, chamfering, and spraying a coating on the surface of the plate blank; and the titanium alloy plate blank is heated to be 20-30 DEG C higher than the beta phase transformation point temperature, and rolling is carried out for multiple times. The processing cost and period of the material can be effectively reduced, the structure performance of the plate is guaranteed, and low-cost preparation of the plate is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy plate processing, and in particular relates to a low-cost preparation method of a titanium alloy plate. Background Art

[0002] Titanium alloys have been widely used in aerospace, aviation, navigation, chemical industry, energy and other fields due to their excellent properties such as high specific strength, high impact toughness and good corrosion resistance. There are two main conventional processing and preparation methods for titanium alloy plates. The first is to obtain finished plates by rolling forged slabs. During the processing, continuous deformation is required to ensure the organization of broken and grain refinement. The traditional process has many forging and rolling fires and long processing flow. In addition, due to the poor thermal conductivity and plasticity of titanium alloys, grinding and other means are required to solve the problems of cracking during the processing. All of the above lead to a series of problems such as high cost and low yield of titanium alloy plates during the processing. The second is to directly roll the EB ingot (the full name of EB is Electron Beam Melting) produced by the solidification furnace. This process omits the forging process and reduces the production cost. However, due to the poor plasticity of the ingot, large cracks will occur during the rolling process, and the plate after rolling will have problems such as uneven organization and coarse grains. Therefore, it is necessary to use the characteristics of titanium alloys to design a low-cost preparation method for titanium alloy plates. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a low-cost preparation method for titanium alloy plates. The present invention is centered around a low-cost preparation method for titanium alloy plates. Based on the original process of rolling plates with EB cast in a solidification furnace, high-speed shot blasting on the surface of the plate and small deformation thinning rolling above the phase change point are used to improve the surface structure of the plate, and a basket structure plate is obtained by accurately controlling the temperature and rolling speed in one-fire rolling, which solves the problems of high processing cost and long manufacturing cycle of traditional titanium alloy plate forging and rolling, and also avoids the problems of cracking and uneven structure of EB cast in a solidification furnace. The structure and performance of the plate are controlled by controlling the rolling temperature and speed.

[0004] In order to achieve the above technical objectives, the technical solution adopted by the embodiment of the present invention is: A low-cost preparation method for a titanium alloy plate comprises the following steps: Step S1, subjecting the EB ingot produced by the titanium alloy vacuum consumable shell furnace to shot blasting at a speed of 3-5 m / min to remove surface oxide scale and minor defects and deform the surface grains; Step S2, heating the titanium alloy EB ingot after shot blasting in step S1 to 30-50°C above the phase transition point, holding time t, then performing thinning rolling, each pass reduction amount is 8-12mm, rolling speed is 0.5-1m / s, when the surface temperature drops to 50-100°C below the phase transition point, returning to the furnace and heating to 30-50°C above the phase transition point before rolling; Step S3, after cooling the titanium alloy slab after thinning and rolling in step S2, inspect the surface of the slab and perform local grinding on the cracked parts of the surface; Step S4, removing the surface oxide layer of the titanium alloy slab after grinding in step S3, chamfering the edges, and spraying a coating with a thickness of 0.5 to 1 mm on the surface of the slab; Step S5, heating the titanium alloy slab after spraying in step S4 to a temperature 20°C to 30°C above the β phase transformation point, controlling the first pass reduction deformation to be 10 to 20 mm, the rolling speed to be 1 to 2 m / s, rotating 90° after the first pass and then rolling, controlling the second pass reduction deformation to be 10 to 20 mm, the rolling speed to be 1 to 2 m / s, rotating 90° after the second pass and then rolling, controlling the third pass reduction deformation to be 10 to 20 mm, the rolling speed to be 1 to 2 m / s s, after the third rolling pass is completed, the surface temperature of the plate is monitored in real time in each pass. If the surface temperature of the plate is 100~120℃ below the phase change point and has not started to rise relative to the previous plate temperature, the deformation of the next pass is controlled to be 12~15mm for rolling at a speed of 1~1.5m / s. If the surface temperature of the plate is 100~120℃ below the phase change point and has started to rise relative to the previous plate temperature, the deformation of each remaining pass is controlled to be 10~12mm for rolling at a speed of 0.2~0.5m / s.

[0005] Furthermore, when shot blasting is performed in step S1, the diameter of the steel shot and the shot blasting pressure are determined according to the alloy grade and the thickness of the plate. The diameter of the steel shot is 1-5 mm, and the shot blasting pressure is selected between 0.2-1 MPa. The entire plate surface is shot blasted 3-5 times to preliminarily crush the surface grains to achieve the purpose of reducing cracking during the rolling process.

[0006] Further, in step S2, the holding time t=EB ingot thickness×1-1.5, the unit of EB ingot thickness is mm, and the unit of holding time is min; During the thinning rolling in step S2, the total deformation does not exceed 20% of the initial thickness of the slab. The purpose is to further break up the surface grains, and at the same time, apply a small pre-deformation to the entire slab, preliminarily coordinate the deformation between the β grains, and reduce the cracking tendency in the subsequent rolling process.

[0007] The technical solution provided by the embodiment of the present invention has the following beneficial effects: The method for low-cost preparation of titanium alloy plates of the present invention adopts EB ingots for direct rolling, and gradually improves the surface structure of the slab by high-speed shot blasting on the surface of the slab and small deformation thinning rolling above the phase transition point. The forging process is omitted from the preparation process, so that the processing cost and time brought by forging can be reduced. In addition, the problem of large surface cracking caused by direct rolling of EB ingots is solved, and the processing costs such as grinding cracks during rolling can be reduced, and the yield rate is improved. In addition, by multiple reversing rolling above the phase transition point, the rolling temperature and speed are controlled below the phase transition point to complete the cross-phase transition point rolling of the plate to ensure the organizational properties of the titanium alloy plate. In summary, the preparation method of the present invention can effectively reduce the processing cost and processing cycle of the material, and can ensure the organizational properties of the plate, and realize low-cost preparation of the plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is the surface structure of the plate in step S3 after thinning and rolling in Example 1.

[0009] Figure 2 This is the rolling structure of the titanium alloy plate obtained by the preparation method of Example 1.

[0010] Figure 3 This is the rolling structure of the titanium alloy plate obtained by the preparation method of Comparative Example 1. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0012] Example 1 A low-cost preparation method for a titanium alloy plate comprises the following steps: Step S1, a new type of titanium alloy (by mass percentage, including the following components: Al: 5%-7%, Mo: 1%-2%, Cr: 1%-2%, V: 1%-2%, Zr: 2%-3%) EB ingot (β phase transformation point detected is 900-910°C, plate thickness is 170mm) is shot blasted at a speed of 3m / min to remove surface oxide scale and minor defects and deform surface grains, the diameter of the steel shot is 5mm, the shot blasting pressure is 0.7MPa, and the surface is shot blasted 5 times; Step S2, heating the titanium alloy EB ingot after shot blasting in step S1 to 950°C, holding time for 250min, then performing thinning rolling, each pass reduction amount is 8mm, rolling speed is 1m / s, when the surface temperature drops to 850°C, returning to the furnace and heating to 950°C and then rolling, rolling until the slab thickness is 140mm, the total deformation of the fire is 17.6%; The holding time t = EB billet thickness × 1~1.5, the unit of EB billet thickness is mm, and the unit of holding time is min; Step S3: After cooling the titanium alloy slab after thinning and rolling in step S2, check the surface of the slab and perform local grinding on the cracked parts of the surface. The surface structure of the actual slab after thinning is as follows: Figure 1 As shown; Step S4, removing the surface oxide layer of the titanium alloy slab after grinding in S3 and chamfering the edges, and spraying a coating with a thickness of 0.5 mm on the surface of the slab, wherein the coating adopts a glass protective lubricant; Step S5, heating the titanium alloy slab after spraying in step S4 to 930°C, controlling the first pass reduction deformation to be 15mm, the rolling speed to be 2m / s, rotating 90° after the first pass and then rolling, controlling the second pass reduction deformation to be 15mm, the rolling speed to be 2m / s, rotating 90° after the second pass and then rolling, controlling the third pass reduction deformation to be 15mm, the rolling speed to be 2m / s, after the third pass rolling is completed, real-time monitoring of the surface temperature of each pass of the plate, if the detection If the plate surface temperature is detected to be 800℃ (100~120℃ below the phase change point) and the plate temperature has not started to rise relative to the previous pass, the remaining deformation amount per pass is controlled to be 12mm for rolling at a speed of 1.5m / s. If the plate surface temperature is detected to be 800℃ (100~120℃ below the phase change point) and the plate temperature has started to rise relative to the previous pass, the remaining deformation amount per pass is controlled to be 10mm for rolling at a speed of 0.5m / s, and a plate with a thickness of 62mm is finally obtained. The plate structure is as follows Figure 2 The properties of the plate after double annealing at 880°C / 2h / air cooling + 800°C / 2h / air cooling are shown in Table 1.

[0013] Example 2 A low-cost preparation method for a titanium alloy plate comprises the following steps: Step S1, shot blasting TC21 titanium alloy EB ingot (β phase transformation point detected is 970-980℃, plate thickness is 160mm) at a speed of 3m / min to remove surface oxide scale and minor defects and deform surface grains, the diameter of the steel shot is 5mm, the shot blasting pressure is 0.7MPa, and the shot blasting is performed 5 times; Step S2, heating the titanium alloy EB ingot after shot blasting in step S1 to 1020°C, holding the ingot for 240 minutes, and then performing thinning rolling, with a reduction of 8 mm per pass and a rolling speed of 0.5 m / s. When the surface temperature drops to 900°C, returning the ingot to the furnace and heating it to 1020°C before rolling again, and rolling until the ingot thickness is 140 mm, and the total deformation of the fire is 17.6%; Holding time t = EB billet thickness × 1~1.5, the unit of EB billet thickness is mm, and the unit of holding time is min; Step S3, after cooling the titanium alloy slab after thinning and rolling in step S2, inspect the surface of the slab and perform local grinding on the cracked parts of the surface; Step S4, removing the surface oxide layer of the titanium alloy slab after grinding in step S3, chamfering, and spraying a coating with a thickness of 0.8 mm on the surface of the slab, wherein the coating adopts a glass protective lubricant; Step S5, heating the titanium alloy slab after spraying in step S4 to 1000°C, controlling the first pass of the pressing deformation to be 15mm, the rolling speed to be 2m / s, rotating 90° after the first pass and rolling again, controlling the second pass of the pressing deformation to be 15mm, the rolling speed to be 2m / s, rotating 90° after the second pass and rolling again, controlling the third pass of the pressing deformation to be 15mm, the rolling speed to be 2m / s, after the third pass of rolling is completed, real-time monitoring of the surface temperature of each pass of the plate, if the surface temperature of the plate is detected to be 860°C (between the phase transition point) If the plate surface temperature is detected to be 860℃ (100~120℃ below the phase change point) and the plate temperature does not start to rise relative to the previous pass, the remaining deformation amount per pass is controlled to be 12mm for rolling at a speed of 1.2m / s. If the plate surface temperature is detected to be 860℃ (100~120℃ below the phase change point) and the plate temperature starts to rise relative to the previous pass, the remaining deformation amount per pass is controlled to be 12mm for rolling at a speed of 0.5m / s. Finally, a plate with a thickness of 62mm is obtained. The properties of the plate after double annealing at 940℃ / 1h / air cooling + 600℃ / 4h / air cooling are shown in Table 1.

[0014] Example 3 A low-cost preparation method for a titanium alloy plate comprises the following steps: Step S1, shot blasting TC4 titanium alloy EB ingot (β phase transformation point detected is 980-990℃, plate thickness is 170mm) at a speed of 4m / min to remove surface oxide scale and minor defects and deform surface grains, the diameter of the steel shot is 5mm, the shot blasting pressure is 0.7MPa, and the shot blasting is performed 5 times; Step S2, heating the titanium alloy EB ingot after shot blasting in step S1 to 1020°C, holding time for 250min, then performing thinning rolling, with each pass reducing amount of 8mm and rolling speed of 0.5m / s. When the surface temperature drops to 920°C, returning to the furnace and heating to 1020°C above the phase change point, and then rolling, rolling until the slab thickness is 140mm, and the total deformation of the fire is 17.6%; Holding time t = EB billet thickness × 1~1.5, the unit of EB billet thickness is mm, and the unit of holding time is min; Step S3, after cooling the titanium alloy slab after thinning and rolling in step S2, inspect the surface of the slab and perform local grinding on the cracked parts of the surface; Step S4, removing the surface oxide layer of the titanium alloy slab after grinding in step S3, chamfering, and spraying a coating with a thickness of 0.8 mm on the surface of the slab, wherein the coating adopts a glass protective lubricant; Step S5, heating the titanium alloy slab after spraying in step S4 to 1010°C, controlling the first pass reduction deformation to be 15mm, the rolling speed to be 2m / s, rotating 90° after the first pass and then rolling, controlling the second pass reduction deformation to be 15mm, the rolling speed to be 2m / s, rotating 90° after the second pass and then rolling, controlling the third pass reduction deformation to be 15mm, the rolling speed to be 2m / s, after the third pass rolling is completed, real-time monitoring of the surface temperature of each pass of the plate, if If the plate surface temperature is detected to be 870℃ (100~120℃ below the phase change point) and the plate temperature has not started to rise relative to the previous pass, the remaining deformation amount per pass is controlled to be 12mm for rolling at a speed of 1m / s. If the plate surface temperature is detected to be 870℃ (100~120℃ below the phase change point) and the plate temperature has started to rise relative to the previous pass, the remaining deformation amount per pass is controlled to be 10mm for rolling at a speed of 0.5m / s, and a plate with a thickness of 62mm is finally obtained. The properties of the plate after double annealing at 950℃ / 2h / air cooling + 750℃ / 2h / air cooling are shown in Table 1.

[0015] Comparative Example 1 A new titanium alloy ingot with the same chemical composition as Example 1 (by mass percentage, including the following components: Al: 5%~7%, Mo: 1%~2%, Cr: 1%~2%, V: 1%~2%, Zr: 2%~3%) was used for conventional forging and rolling process, heated to 1150°C, two fires, two upsetting and two drawing, the deformation amount was 50%, and polishing was performed after each fire; heated to 880°C, 4 fires, one upsetting and one drawing for each fire, the deformation amount was 30%, and then two finished fires were performed to forge and draw into a slab. The surface oxide layer of the forged titanium alloy slab was milled off and chamfered, and a coating with a thickness of 0.5 mm was sprayed on the surface of the slab, and the coating used a glass protective lubricant. The first heat rolling is carried out at 940℃: the rolling process is 20mm per pass, after rolling to 90mm, it is cooled to room temperature for grinding, and then heated to 870℃ for second heat rolling, 10mm per pass, and rolled to a thickness of 62mm. The rolling structure is as follows Figure 3 The properties of the plate after double annealing at 880℃ / 2h / air cooling + 800℃ / 2h / air cooling are shown in Table 1.

[0016] Comparative Example 2 The conventional forging and rolling process is carried out using the TC21 titanium alloy ingot with the same chemical composition as in Example 2, heating to 1200°C, two fires, two upsettings and two pullings, the deformation is 45%, and grinding is performed after each fire; heating to 930°C, 5 fires, one upsetting and one pulling for each fire, the deformation is 30%, and then two finished fires are forged and pulled into a slab; the surface oxide layer of the forged titanium alloy slab is milled off and chamfered, and a coating with a thickness of 0.5mm is sprayed on the surface of the slab, and the coating adopts a glass protective lubricant; one fire rolling is carried out at 1020°C: the rolling process is 20mm per pass, and after rolling to 90mm, it is cooled to room temperature for grinding, and then heated to 870°C for two fire rolling, each pass 12mm, and rolled to a thickness of 62mm. The properties of the plate after double annealing at 940°C / 1h / air cooling + 600°C / 4h / air cooling are shown in Table 1.

[0017] Comparative Example 3 A conventional forging and rolling process was performed using a TC4 titanium alloy ingot with the same chemical composition as in Example 3. The ingot was heated to 1200°C, subjected to two fires, two upsets and two draws, with a deformation of 45%, and polished after each fire; heated to 940°C, subjected to six fires, with one upset and one draw in each fire, with a deformation of 35%, and then subjected to two finished fires for forging and drawing to form a slab; the surface oxide layer of the forged titanium alloy slab was milled off and chamfered, and a coating with a thickness of 0.5 mm was sprayed on the surface of the slab, and the coating used a glass protective lubricant; one fire rolling was performed at 940°C: the rolling process was 20 mm per pass, and after rolling to 90 mm, the ingot was cooled to room temperature for grinding, and then heated to 870°C for two fire rollings, with 12 mm per pass, and the ingot was rolled to a thickness of 62 mm. The properties of the plate after double annealing at 950°C / 2h / air cooling + 750°C / 2h / air cooling are shown in Table 1.

[0018] Table 1 Mechanical properties of 60 mm rolled plates of different titanium alloys

[0019] Depend on Figure 1 and Figure 2 It can be seen that the surface microstructure of Example 1 after thinning is significantly refined and is a Widmanstatten structure. Figure 2 The rolled structures of Example 1 and Comparative Example 1 are basically similar. The grains can be further broken by performing different reversing rolling during the rolling process, and the rolling temperature and rolling speed can be controlled to make the structure more uniform. The morphology of the rolled structures obtained by Example 1 of the present invention and Comparative Example 1 is basically the same.

[0020] From Table 1, it can be seen that compared with Comparative Example 1, the tensile strength of the plate prepared by low-cost processing in Example 1 is slightly lower than that of the plate prepared by the conventional process, but the plasticity and toughness are better than those of the conventional process. Combining Examples 2 and 3 and Comparative Examples 2 and 3, in general, the mechanical properties of the titanium alloy plate prepared by low-cost processing are not much different from those of the plate prepared by the conventional process.

[0021] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A low-cost preparation method for a titanium alloy plate, characterized in that: The following steps are involved: Step S1, subjecting the EB ingot produced by the titanium alloy vacuum consumable shell furnace to shot blasting at a speed of 3-5 m / min to remove surface oxide scale and minor defects and deform the surface grains; Step S2, heating the titanium alloy EB ingot after shot blasting in step S1 to 30-50°C above the phase transition point, holding time t, then performing thinning rolling, each pass reduction amount is 8-12mm, rolling speed is 0.5-1m / s, when the surface temperature drops to 50-100°C below the phase transition point, returning to the furnace and heating to 30-50°C above the phase transition point before rolling; Step S3, after cooling the titanium alloy slab after thinning and rolling in step S2, inspect the surface of the slab and perform local grinding on the cracked parts of the surface; Step S4, removing the surface oxide layer of the titanium alloy slab after grinding in step S3, chamfering the edges, and spraying a coating with a thickness of 0.5 to 1 mm on the surface of the slab; Step S5, heating the titanium alloy slab after spraying in step S4 to a temperature 20-30°C above the β phase transformation point, controlling the first pass reduction deformation to be 10-20mm, the rolling speed to be 1-2m / s, rotating 90° after the first pass and then rolling, controlling the second pass reduction deformation to be 10-20mm, the rolling speed to be 1-2m / s, rotating 90° after the second pass and then rolling, controlling the third pass reduction deformation to be 10-20mm, the rolling speed to be 1-2m / s After the third rolling pass is completed, the surface temperature of the plate is monitored in real time in each pass. If the surface temperature of the plate is 100~120℃ below the phase change point and has not started to rise relative to the temperature of the previous pass, the deformation of the next pass is controlled to be 12~15mm for rolling at a speed of 1~1.5m / s. If the surface temperature of the plate is 100~120℃ below the phase change point and has started to rise relative to the temperature of the previous pass, the deformation of each remaining pass is controlled to be 10~12mm for rolling at a speed of 0.2~0.5m / s.

2. The low-cost preparation method of the titanium alloy sheet according to claim 1, characterized in that: When the shot blasting is performed in step S1, the diameter of the steel shot and the shot blasting pressure are determined according to the alloy grade and the thickness of the plate. The diameter of the steel shot is 1-5 mm, and the shot blasting pressure is selected between 0.2-1 MPa. The entire plate surface is shot blasted 3-5 times.

3. The low-cost preparation method of titanium alloy sheet according to claim 1, characterized in that: In step S2, the holding time t=EB billet thickness×1-1.5, the unit of EB billet thickness is mm, and the unit of holding time is min; During the thinning rolling in step S2, the total deformation does not exceed 20% of the initial thickness of the slab.

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