Ti662 titanium alloy, smelting method and application

Abstract

The invention belongs to the technical field of titanium alloy smelting, and particularly relates to a Ti662 titanium alloy, a smelting method and application. Due to the fact that the redistribution coefficient K of the Cu element in the titanium alloy is equal to 0.2, a Ti662 cast ingot is prone to segregation in the smelting process, and the problem that beta spots are generated in the forging process is caused. Therefore, when the intermediate alloy is selected, the titanium-copper binary alloy with the lower copper proportion is selected as the raw material additive to improve the uniformity of the Cu element in the consumable electrode preparation process, and the Cu element in a cast ingot can be better alloyed and homogenized through two times of vacuum consumable electric arc melting; the problem that beta spots are generated in the deep processing process due to non-uniform components of the cast ingot is solved, and the Ti662 finished cast ingot with stable quality and uniform components is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy smelting, and specifically relates to a Ti662 titanium alloy, a smelting method and application. Background Art

[0002] Ti662 titanium alloy is a two-phase high-strength titanium alloy rich in β-stabilizing elements. It is developed by adding more β-phase stabilizing element V to TC4 titanium alloy, and adding 0.5% Cu and 0.5% Fe by mass. Among them, the V element makes the Ti662 titanium alloy have a significant solid solution strengthening effect, and trace Cu and Fe elements can further enhance the heat treatment strengthening ability of Ti662 titanium alloy. Due to its excellent mechanical properties, heat resistance and corrosion resistance, Ti662 titanium alloy is widely used in petrochemical, aviation industry, nuclear power generation and military industry.

[0003] Vacuum consumable arc melting (VAR) is a commonly used melting method for producing Ti662 titanium alloy ingots, which has the characteristics of high melting efficiency and good composition uniformity. At present, in the process of producing Ti662 titanium alloy ingots, it is found that β-spot defects are prone to occur in the ingots during the forging process; V element, as a β-spot stabilizing element of Ti662 titanium alloy ingots, hardly produces segregation during melting, but Cu, as an element that is easy to segregate, is prone to volatilization loss and segregation of Cu element during long-term melting. The β-spot defects generated in the Ti662 titanium alloy ingot during the forging process will directly affect the mechanical properties of the Ti662 titanium alloy ingot, and then affect the safety and reliability of the Ti662 titanium alloy during use. In the prior art, in order to eliminate the hidden dangers caused by the β-spots of Cu easily segregated elements during the melting process, the amount of ingot sawing is generally increased, which greatly reduces the ingot yield rate and increases the cost of raw materials.

[0004] Therefore, a smelting method for Ti662 titanium alloy ingots is urgently needed to solve the β-spot defects that occur in the existing smelting process. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a Ti662 titanium alloy, a smelting method and an application.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] On the one hand, the present invention provides a Ti662 titanium alloy, which includes, by weight percentage, Al: 5.5% to 5.9%, V: 5.5% to 5.9%, Sn: 2.1% to 2.4%, Cu: 0.35% to 1.00%, Fe: 0.35% to 1.00%, O: 0.15% to 0.19%, and the balance is Ti and unavoidable impurity elements.

[0008] On the other hand, the present invention provides a smelting method of Ti662 titanium alloy, the specific steps are as follows:

[0009] Step 1, calculate the weight of titanium sponge and master alloy according to weight percentage, then weigh and mix the materials, use 8000T hydraulic press to press electrode blocks with a specification of Φ480mm (1 / 2 circle), the pressure range is 6000-7000T, and the pressure holding time is 10-20s; multiple electrode blocks are welded by filling inert gas in a plasma welding box to form consumable electrodes, the inert gas pressure during welding is 15000-25000Pa, the welding voltage is 60-90V, the welding current is 460-600A, and the cooling time after welding is 30-60min;

[0010] Among them, the sponge titanium is 0A grade sponge titanium with a particle size of 3 to 12.7 mm; the particle size of the intermediate alloy aluminum bean is 5 to 11 mm, the particle size of Ti-32Fe is 1 to 6 mm, the particle size of Ti-80Sn is 2 to 10 mm, the particle size of Al-65V is 1 to 6 mm, the particle size of Ti-40Cu is 1 to 6 mm, and the particle size of TiO 2 The particle size is ≤45μm;

[0011] Step 2: placing the consumable electrode into a Φ580mm water-cooled copper crucible and using a vacuum consumable arc furnace to obtain a primary ingot by primary smelting, and removing the splashing of the head of the primary ingot and the volatile impurities attached to the surface; the specific parameters of the primary smelting are: the vacuum degree of the vacuum consumable arc furnace before melting is ≤5Pa, the smelting voltage is 30-36V, the smelting current is 10-15kA, the arc stabilization current is 5-12A, the arc stabilization change cycle is 4-8s, and the crucible water flow rate during the smelting process is 80-100m 3 / h; After smelting, the cooling time of the ingot in the furnace is 5 to 10 hours; when the surface temperature of the ingot is lower than 200℃, air cooling can be selected;

[0012] Step 3: In order to improve the uniformity of the composition of the head and bottom of the ingot, the primary ingot is turned around and placed in a Φ650mm water-cooled copper crucible, and a secondary smelting is performed in a vacuum consumable arc furnace, and shrinkage is supplemented to obtain a secondary ingot; the parameters for the secondary smelting are: the vacuum degree of the vacuum consumable arc furnace before melting is ≤5Pa, the smelting voltage is 30-36V, the smelting current is 14-20kA, the arc stabilization current is 8-14A, the arc stabilization change cycle is 4-8s, and the crucible water flow rate during the smelting process is 80-100m 3 / h, the feeding time is 3 to 4.5h, and the crucible water flow rate during feeding is 80 to 100m 3 / h;

[0013] It should be noted that the shrinkage feeding process is part of the secondary smelting process. Starting from the middle and late stages of smelting, the main parameters of normal smelting are adjusted to reduce the depth of the ingot riser, thereby improving the ingot yield rate.

[0014] Step 4: After the smelting is completed, the secondary ingot is cooled in an inert gas in the furnace at a pressure of 4000-6000 Pa. The cooling time of the ingot is greater than or equal to 6 hours (depending on the production situation, the furnace can be opened to take out the ingot after the cooling time of the ingot is greater than or equal to 6 hours), and finally a Ti662 titanium alloy ingot with uniform composition, no segregation and no defects is obtained.

[0015] On the other hand, the present invention provides a Ti662 titanium alloy, or the Ti662 titanium alloy prepared by the smelting method of the Ti662 titanium alloy, and its application in petrochemical industry, aviation industry, nuclear power generation and military industry.

[0016] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0017] Since the redistribution coefficient K of the Cu element in the titanium alloy is 0.2, segregation is very likely to occur in the Ti662 ingot during the smelting process, resulting in the β-spot problem generated during the forging process; therefore, when selecting the intermediate alloy, the present invention selects a titanium-copper binary alloy with a lower copper content as a raw material additive to improve the uniformity of the Cu element in the preparation process of the consumable electrode, and performs two vacuum consumable arc meltings. In this way, the Cu element in the ingot can be better alloyed and homogenized, and the problem of β-spots generated during deep processing due to uneven composition of the ingot is solved, thereby obtaining a Ti662 finished ingot with stable quality and uniform composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1 It is a schematic flow diagram of the smelting method of the present invention;

[0021] Figure 2 This is a schematic diagram of sampling from the outer circumference of an ingot according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of sampling nine points on the head and bottom cross sections of an ingot according to an embodiment of the present invention;

[0023] Figure 4 This is a metallographic diagram of the ingot prepared in Example 1;

[0024] Figure 5 This is a metallographic diagram of the ingot prepared in Example 2;

[0025] Figure 6 This is a schematic diagram of the metallographic structure of the ingot prepared in Example 3. DETAILED DESCRIPTION

[0026] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention as detailed in the appended claims.

[0027] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0028] To prove the preparation method of the present invention, the following examples are provided for verification:

[0029] It should be noted that the following examples use the raw material components shown in Table 1 to prepare Ti662 ingots with a specification of Φ650 mm.

[0030] Table 1

[0031]

[0032] Example 1

[0033] See also Figure 1 As shown, this embodiment provides a smelting method of Ti662 titanium alloy, and the specific steps are as follows:

[0034] Step 1, according to the weight percentage, the weight of the titanium sponge and the master alloy is calculated, and then the materials are weighed and mixed. The electrode block with a specification of Φ480mm (1 / 2 circle) is pressed on an 8000T hydraulic press, the pressure is 6000T, and the pressure holding time is 20s; multiple electrode blocks are welded by filling argon gas in a plasma welding box to form a consumable electrode with a mass of 3350kg. The argon gas pressure during welding is 15000-20000Pa, the welding voltage is 60-70V, the welding current is 550-600A, and the cooling time after welding is 30min;

[0035] Among them, the sponge titanium is 0A grade sponge titanium with a particle size of 3 to 10 mm; the particle size of the intermediate alloy aluminum bean is 5 to 8 mm, the particle size of Ti-32Fe is 2 to 4 mm, the particle size of Ti-80Sn is 3 to 6 mm, the particle size of Al-65V is 2 to 4 mm, the particle size of Ti-40Cu is 2 to 4 mm, and the particle size of TiO 2 The particle size is ≤45μm;

[0036] Step 2: placing the consumable electrode into a Φ580 mm water-cooled copper crucible and using a vacuum consumable arc furnace to obtain a primary ingot by a primary smelting; the specific parameters for the primary smelting are: the vacuum degree of the vacuum consumable arc furnace before melting is ≤5 Pa, the smelting voltage is 30-33 V, the smelting current is 13-15 kA, the arc stabilization current is 5-8 A, the arc stabilization change cycle is 4 s, and the crucible water flow rate during the smelting process is 80-90 m 3 / h; the cooling time of the ingot in the furnace after smelting is 5h;

[0037] Step 3: In order to improve the uniformity of the composition of the head and bottom of the ingot, the primary ingot is turned around and placed in a Φ650mm water-cooled copper crucible, and a secondary smelting is performed in a vacuum consumable arc furnace to obtain a secondary ingot after shrinkage compensation; the parameters for the secondary smelting are: the vacuum degree of the vacuum consumable arc furnace before melting is ≤5Pa, the smelting voltage is 30-33V, the smelting current is 17-20kA, the arc stabilization current is 8-10A, the arc stabilization change cycle is 4s, and the crucible water flow rate during the smelting process is 80-90m 3 / h, the feeding time is 4.5h, and the crucible water flow rate is 80~90m 3 / h;

[0038] Step 4: Cool the secondary ingot in the furnace by filling it with argon gas at a pressure of 4000-5000 Pa. The cooling time of the ingot is 8 hours, and finally a Ti662 titanium alloy ingot A with a size of Φ650 mm is obtained.

[0039] Example 2

[0040] See also Figure 1 As shown, this embodiment provides a smelting method of Ti662 titanium alloy, and the specific steps are as follows:

[0041] Step 1, calculate the weight of titanium sponge and master alloy according to weight percentage, then weigh and mix the materials, use 8000T hydraulic press to press electrode blocks with a specification of Φ480mm (1 / 2 circle), the pressure is 6500T, and the pressure holding time is 15s; weld multiple electrode blocks by filling argon gas in a plasma welding box to form a consumable electrode with a mass of 3350kg, the argon gas pressure during welding is 18000-23000Pa, the welding voltage is 65-75V, the welding current is 480-550A, and the cooling time after welding is 45min;

[0042] Among them, the sponge titanium is 0A grade sponge titanium with a particle size of 5 to 12.7 mm; the particle size of the intermediate alloy aluminum bean is 7 to 9 mm, the particle size of Ti-32Fe is 3 to 5 mm, the particle size of Ti-80Sn is 5 to 8 mm, the particle size of Al-65V is 3 to 5 mm, the particle size of Ti-40Cu is 4 to 5 mm, and the particle size of TiO 2 The particle size is ≤45μm;

[0043] Step 2: placing the consumable electrode into a Φ580 mm water-cooled copper crucible and using a vacuum consumable arc furnace to obtain a primary ingot by a primary smelting; the specific parameters for the primary smelting are: vacuum degree before melting in the vacuum consumable arc furnace ≤5 Pa, smelting voltage of 32-33 V, smelting current of 12-14 kA, arc stabilization current of 7-10 A, arc stabilization change cycle of 6 s, and crucible water flow rate of 85-95 m during smelting. 3 / h; the cooling time of the ingot after smelting is 7h;

[0044] Step 3: In order to improve the uniformity of the composition of the head and bottom of the ingot, the primary ingot is turned around and placed in a Φ650mm water-cooled copper crucible, and a secondary smelting is performed in a vacuum consumable arc furnace to obtain a secondary ingot after shrinkage compensation; the parameters for the secondary smelting are: the vacuum degree of the vacuum consumable arc furnace before melting is ≤5Pa, the smelting voltage is 32-34V, the smelting current is 15-18kA, the arc stabilization current is 10-12A, the arc stabilization change cycle is 7s, and the crucible water flow rate during the smelting process is 85-95m 3 / h, the feeding time is 4h, and the crucible water flow rate is 85~95m 3 / h;

[0045] Step 4: Cool the secondary ingot by filling it with argon gas at a pressure of 4500-5500 Pa. The cooling time of the ingot is 7 hours, and finally a Ti662 titanium alloy ingot B with a size of Φ650 mm is obtained.

[0046] Example 3

[0047] See also Figure 1 As shown, this embodiment provides a smelting method of Ti662 titanium alloy, and the specific steps are as follows:

[0048] Step 1, calculate the weight of titanium sponge and master alloy according to weight percentage, then weigh and mix the materials, use 8000T hydraulic press to press electrode blocks with a specification of Φ480mm (1 / 2 circle), the pressure is 7000T, and the pressure holding time is 10s; weld multiple electrode blocks in a plasma welding box with argon gas to form a consumable electrode with a mass of 3350kg. The argon gas pressure during welding is 20000-25000Pa, the welding voltage is 85-90V, the welding current is 460-480A, and the cooling time after welding is 60min;

[0049] Among them, the sponge titanium is 0A grade sponge titanium with a particle size of 3 to 12.7 mm; the particle size of the intermediate alloy aluminum bean is 9 to 11 mm, the particle size of Ti-32Fe is 4 to 6 mm, the particle size of Ti-80Sn is 8 to 10 mm, the particle size of Al-65V is 4 to 6 mm, the particle size of Ti-40Cu is 4 to 6 mm, and the particle size of TiO 2 The particle size is ≤45μm;

[0050] Step 2: placing the consumable electrode into a Φ580 mm water-cooled copper crucible and using a vacuum consumable arc furnace to obtain a primary ingot by a single smelting; the specific parameters for the single smelting are: vacuum degree before melting in the vacuum consumable arc furnace is ≤5 Pa, the smelting voltage is 33-36 V, the smelting current is 10-13 kA, the arc stabilization current is 10-12 A, the arc stabilization change cycle is 8 s, and the crucible water flow rate during the smelting process is 90-100 m 3 / h; the cooling time of the ingot after smelting is 10h;

[0051] Step 3: In order to improve the uniformity of the composition of the head and bottom of the ingot, the primary ingot is turned over and placed in a Φ650mm water-cooled copper crucible, and a secondary smelting is performed in a vacuum consumable arc furnace to obtain a secondary ingot after shrinkage compensation; the parameters for the secondary smelting are: the vacuum degree of the vacuum consumable arc furnace before melting is ≤5Pa, the smelting voltage is 33-36V, the smelting current is 14-16kA, the arc stabilization current is 12-14A, the arc stabilization change cycle is 8s, and the crucible water flow rate during the smelting process is 90-100m 3 / h, the feeding time is 3h, and the crucible water flow rate is 90~100m 3 / h;

[0052] Step 4: Cool the secondary ingot by filling it with argon gas at a pressure of 5000-6000 Pa. The cooling time of the ingot is 6 hours, and finally a Ti662 titanium alloy ingot C with a size of Φ650 mm is obtained.

[0053] In order to further verify the effectiveness of the technical solution provided by the present invention, the following tests were performed on the above-mentioned ingot A, ingot B, and ingot C respectively:

[0054] (1) The head, middle and bottom of the outer circumference of the prepared ingot A, ingot B and ingot C are respectively turned to obtain chips, such as Figure 2 As shown, the Cu component of the obtained chips was detected, and the detection results are shown in Table 2.

[0055] (2) Nine points (4 points on the circumference, 4 points at 1 / 2R, and 1 point at the center) of the head cross section of the prepared ingots A, B, and C were measured respectively. Figure 3As shown) and 9 points of the bottom cross section (4 points on the circumference, 4 points at 1 / 2R, and 1 point at the center, as shown Figure 3 The drilling debris was carried out (as shown in Table 3), and the Cu component of the obtained debris was detected. The detection results are shown in Table 3.

[0056] Table 2

[0057]

[0058] Table 3

[0059]

[0060]

[0061] In summary, it can be concluded from Table 1 and Table 2 that the range of Cu element in the circumferential direction of the prepared ingots A, B and C is within 0.006%; the range of Cu element in the 9-point sampling of the head section and the 9-point sampling of the bottom section is within 0.027%; that is, the Cu element in the ingots A, B and C prepared by the preparation method of the present invention is good in uniformity and composition, and no β spot defect is generated in the ingots during the forging process; and by metallographic observation of the ingots prepared in Examples 1 to 3, ingot A (see Figure 4 As shown), Ingot B (see Figure 5 As shown), ingot C (see Figure 6 The α phase and β phase of the titanium alloy are uniformly distributed. Therefore, the Ti662 titanium alloy ingot prepared according to the preparation method of the present invention meets the design requirements.

[0062] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0063] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A Ti662 titanium alloy, characterized in that: By weight percentage, it includes: Al: 5.5% to 5.9%, V: 5.5% to 5.9%, Sn: 2.1% to 2.4%, Cu: 0.35% to 1.00%, Fe: 0.35% to 1.00%, O: 0.15% to 0.19%, and the balance is Ti and unavoidable impurity elements.

2. The smelting method of the Ti662 titanium alloy according to claim 1, characterized in that: The specific steps are as follows: Step 1: Calculate the weight of titanium sponge and master alloy according to weight percentage, then weigh, mix, press electrode blocks and weld electrodes to form consumable electrodes; Step 2, using a vacuum consumable arc furnace to smelt the consumable electrode once to obtain a primary ingot; Step 3, turning the primary ingot around and performing secondary smelting in a vacuum consumable arc furnace, and feeding the ingot to obtain a secondary ingot; Step 4: After the secondary ingot is cooled, the desired Ti662 titanium alloy ingot is obtained.

3. The smelting method of Ti662 titanium alloy according to claim 2, characterized in that: In step 1, the sponge titanium is 0A grade sponge titanium, and the intermediate alloy is aluminum bean, Ti-32Fe, Ti-80Sn, Al-65V, Ti-40Cu and TiO2.

4. The smelting method of Ti662 titanium alloy according to claim 3, characterized in that: In step 1, the particle size of the titanium sponge is 3 to 12.7 mm, the particle size of the aluminum beans is 5 to 11 mm, the particle size of Ti-32Fe is 1 to 6 mm, the particle size of Ti-80Sn is 2 to 10 mm, the particle size of Al-65V is 1 to 6 mm, the particle size of Ti-40Cu is 1 to 6 mm, and the particle size of TiO2 is ≤45 μm.

5. The smelting method of Ti662 titanium alloy according to claim 2, characterized in that: In step 1, when pressing the electrode block, the pressure of the hydraulic press is 6000-7000T, and the pressure holding time is 10-20s.

6. The smelting method of Ti662 titanium alloy according to claim 2, characterized in that: In step 1, the electrode welding is performed by filling an inert gas in a plasma welding box, and the specific parameters are: the inert gas pressure is 15000-25000Pa, the welding voltage is 60-90V, the welding current is 460-600A, and the cooling time after welding is 30-60min.

7. The smelting method of Ti662 titanium alloy according to claim 2, characterized in that: In step 2, during the first smelting, the vacuum degree of the vacuum consumable arc furnace before melting is ≤5Pa, the smelting voltage is 30-36V, the smelting current is 10-15kA, the arc stabilization current is 5-12A, and the arc stabilization change period is 4-8s.

8. The smelting method of Ti662 titanium alloy according to claim 2, characterized in that: In step 3, during the secondary smelting, the vacuum degree of the vacuum consumable arc furnace before melting is ≤5Pa, the smelting voltage is 30-36V, the smelting current is 14-20kA, the arc stabilization current is 8-14A, the arc stabilization change cycle is 4-8s, the feeding time is 3-4.5h, and the crucible water flow rate is 80-100m 3 / h.

9. The smelting method of Ti662 titanium alloy according to claim 2, characterized in that: In step 4, after the smelting is completed, inert gas is filled for cooling, and the cooling time is greater than or equal to 6 hours.

10. Application of the Ti662 titanium alloy according to claim 1 or the Ti662 titanium alloy prepared by the smelting method of any one of claims 2 to 9 in petrochemical industry, aviation industry, nuclear power generation and military industry.

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