CN115386753B - Preparation method of WSTi6421 titanium alloy - Google Patents
Preparation method of WSTi6421 titanium alloy Download PDFInfo
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- CN115386753B CN115386753B CN202210983904.5A CN202210983904A CN115386753B CN 115386753 B CN115386753 B CN 115386753B CN 202210983904 A CN202210983904 A CN 202210983904A CN 115386753 B CN115386753 B CN 115386753B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K10/00—Welding or cutting by means of a plasma
- B23K10/02—Plasma welding
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C14/00—Alloys based on titanium
Abstract
The invention relates to a preparation method of WSTi6421 titanium alloy, which comprises the following steps: s1, mixing titanium sponge, zirconium sponge, tiSi intermediate alloy and AlNoNb ternary alloy particles, and pressing the mixture into a plurality of regular hexagon electrode rods; s2, welding the electrode rods pressed by the S2 into a consumable electrode by adopting a non-tungsten argon shield plasma welding method; and S3, placing the consumable electrode obtained in the S2 into a vacuum consumable arc furnace for three times of smelting to obtain the WSTi6421 alloy cast ingot. The method successfully breaks through the industrial 1-8 ton-grade large-specification ingot chemical composition uniformity control technology, controls the burning loss of aluminum element in the smelting process, avoids metallurgical defects such as high-melting-point molybdenum, chromium and niobium element non-fusion blocks and the like, and effectively solves the problems of composition segregation, impurity and gap element content control, batch stability and the like.
Description
Technical Field
The invention belongs to the technical field of titanium alloy preparation, and relates to a preparation method of WSTi6421 titanium alloy.
Background
The nominal component of the WSTi6421 alloy is Ti-6Al-4Mo-2Zr-1Nb, and the WSTi6421 alloy has higher room temperature strength and room temperature plasticity, excellent impact toughness, fracture toughness and fatigue property, and is a titanium alloy material with excellent comprehensive properties, which can be used for aerospace structural parts and engines. In order to ensure the high uniformity of the components of the WSTi6421 cast ingot, a special preparation process is adopted from the used intermediate alloy to the smelting process of the cast ingot. For example, electromagnetic suspension smelting is adopted to prepare high-uniformity AlNb intermediate alloy; controlling the granularity of the titanium sponge, the zirconium sponge and the intermediate alloy to ensure that each additive is uniformly mixed and distributed in the mixing process; and the special hexagonal die is used for preparing the electrode block, so that the gap difference between the crucible and the electrode block in the first smelting process is reduced, and the uniformity of the transverse components of the molten pool in the smelting process is provided. The three-time vacuum consumable smelting method is adopted to improve the component uniformity of the cast ingot; in addition, the special technology is adopted in the second smelting and the third smelting, so that the component uniformity of the cast ingot is further improved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a preparation method of a WSTi6421 titanium alloy, which solves the difficult problem of controlling the component uniformity of molybdenum which is an element easy to segregate and molybdenum which is a high-melting-point element and niobium in the WSTi6421 alloy.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the preparation method of the WSTi6421 titanium alloy is characterized by comprising the following steps of:
s1, mixing titanium sponge, zirconium sponge, tiSi intermediate alloy and AlNoNb ternary alloy particles, and pressing the mixture into a plurality of regular hexagon electrode rods;
s2, welding the electrode rods pressed by the S2 into a consumable electrode by adopting a non-tungsten argon shield plasma welding method;
and S3, placing the consumable electrode obtained in the S2 into a vacuum consumable arc furnace for three times of smelting to obtain the WSTi6421 alloy cast ingot.
Further, the S1 specifically is: the method comprises the steps of placing titanium sponge, zirconium sponge, tiSi intermediate alloy and AlMoNb ternary alloy particles in a mixer with a built-in baffle, mixing materials in a double-shaft reversing rotation mode for 50s-70s, placing the uniformly mixed raw materials at the lower part of a special hexagonal die, and pressing the uniformly mixed raw materials into 3 equilateral hexagonal electrode bars in a bidirectional secondary pressing mode by using an oil press, wherein the pressing strength is 25-30 MPa.
Furthermore, in the step S2, the number of the electrode rods is 3, and the welding paths of the contact surfaces of the electrode rods are welded in an annular mode.
Further, the third smelting in S3 specifically includes:
smelting for the first time: adopting current control, polishing the surface of an ingot after tapping, wherein the specification of the crucible is phi 160-640 mm;
smelting for the second time: the constant melting speed control is adopted, and the specification of the crucible is phi 220 mm-phi 850mm;
third smelting: the melting depth and the flow intensity of a molten pool are controlled, and the specification phi of the crucible is 280 mm-920 mm.
Further, the smelting process of the second smelting is divided into two stages: 90% before the smelting process, the smelting speed is 5 kg/min-22 kg/min; 10% after the smelting process, the smelting speed is gradually reduced in the form of a near inverse proportion function curve.
Further, the smelting process of the third smelting is divided into three stages: 10% before smelting process, controlling the depth of a molten pool at 0.2-0.5 m, and controlling the flow strength of the molten pool at 10-70 kg/s; 10-80% of the smelting process, wherein the depth of a molten pool is controlled to be 0.5-1.5 m, and the flow strength of the molten pool is 30-100 kg/s; feeding 20% of molten metal after the smelting process, gradually reducing the penetration at a rate of 0.02m/min, and enabling the flow intensity of a molten pool to be 10 kg/s-20 kg/s, wherein the total feeding time is not less than 50 min-200 min.
Further, the preparation of the almonds ternary alloy block in S1 specifically includes: al with the grain purity of 99.999%, mo with the powder purity of 99.99% and Nb with the grain purity of 99.95% are mixed according to the proportion of 5:3:2, a plurality of alloy blocks with the diameter of 100mm are prepared by adopting a hot isostatic pressing method after being uniformly mixed, high-uniformity AlNoNb intermediate alloy cast ingots are prepared by adopting an electromagnetic suspension smelting method through the plurality of alloy blocks, and the AlNoNb intermediate alloy cast ingots are crushed into grains with the particle size of 3 mm-5 mm by utilizing a metal crusher, wherein the single weight of the cast ingots is 10kg-15kg.
Further, the granularity of the titanium sponge in the step S1 is 5 mm-12.7 mm, the titanium sponge is 0-grade titanium sponge, the granularity of the zirconium sponge is 5 mm-8 mm, and the zirconium sponge is high-purity zirconium sponge.
Further, the WSTi6421 titanium alloy cast ingot comprises the following components in percentage by weight: 6.0 to 7.5 percent; mo:3.5 to 4.5 percent; zr:1.5 to 2.5 percent; nb:0.5 to 1.5 percent; o:0.08 to 0.15 percent, the balance being Ti and impurities, the total amount of impurity elements not exceeding 0.20 percent, the sum of the weight percentages of the components being 100 percent.
Further, the specification of the WSTi6421 alloy cast ingot of the S4 is phi 280 mm-phi 920mm.
Compared with the prior art, the invention has the following beneficial effects:
in order to ensure the high uniformity of the components of the WSTi6421 cast ingot, preparing a high-uniformity AlNb intermediate alloy by adopting electromagnetic suspension smelting; controlling the granularity of the titanium sponge, the zirconium sponge and the intermediate alloy to ensure that each additive is uniformly mixed and distributed in the mixing process; and the special hexagonal die is used for preparing the electrode block, so that the gap difference between the crucible and the electrode block in the first smelting process is reduced, and the uniformity of the transverse components of the molten pool in the smelting process is provided. The three-time vacuum consumable smelting method is adopted to improve the component uniformity of the cast ingot; in addition, during the second smelting and the third smelting, the composition uniformity of the cast ingot is further improved through controlling the depth of a molten pool and the flow intensity of the molten pool before the smelting process and after the smelting process. The longitudinal components of the cast ingot obtained by the method can be effectively controlled within 1000ppm, and the bar is inspected for beta spots at 25 ℃ below the phase transition point, so that metallurgical defects are not found; the preparation method successfully breaks through the industrial 1-8 ton-grade large-specification ingot chemical composition uniformity control technology, controls the burning loss of aluminum element in the smelting process, avoids metallurgical defects such as high-melting-point molybdenum, chromium, niobium element non-fusion blocks and the like, effectively solves the problems of composition segregation, impurity and gap element content control, batch stability and the like, and is suitable for industrial production of WSTi6421 titanium alloy ingots with the specification of phi 280-phi 920mm.
Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate principles of the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a diagram of the longitudinal 5-point chemical composition of an ingot obtained in example 3 of the present invention;
FIG. 2 is a graph showing the Al element content distribution at 9 points in the transverse direction of the ingot obtained in example 3 of the present invention;
FIG. 3 is a graph showing the elemental content distribution of Mo at 9 points in the transverse direction of an ingot obtained in example 3 of the present invention;
FIG. 4 is a graph showing the Zr element content at 9 points in the transverse direction of the ingot obtained in example 3 of the present invention;
FIG. 5 is a plot of Nb content at 9 points in the transverse direction of the ingot obtained in example 3 of the present invention;
FIG. 6 is a schematic illustration of a longitudinal 5-point sampling of a titanium alloy ingot obtained by the method of the present invention;
FIG. 7 is a schematic illustration of a transverse 9-point sampling of a titanium alloy ingot obtained by the method of the present invention;
wherein: 1. casting ingot; 2. a longitudinal sampling point; 3. and (5) transverse sampling points.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the invention. Rather, they are merely examples of devices that are consistent with aspects of the invention that are set forth in the following claims.
The present invention will be described in further detail below with reference to the drawings and examples for better understanding of the technical solutions of the present invention to those skilled in the art.
The preparation method of the WSTi6421 titanium alloy is characterized by comprising the following steps of:
s1, placing titanium sponge, zirconium sponge, tiSi intermediate alloy and AlNoNb ternary alloy particles in a mixer with a built-in baffle, mixing materials in a double-shaft reversing rotation mode for 50S-70S, placing the uniformly mixed raw materials at the lower part of a special hexagonal die, and pressing the uniformly mixed raw materials into 3 equilateral hexagonal electrode bars in a bidirectional secondary pressing mode by using an oil press, wherein the pressing strength is 25-30 MPa;
the preparation of the AlNb ternary alloy block specifically comprises the following steps: al with the grain purity of 99.999%, mo with the powder purity of 99.99% and Nb with the grain purity of 99.95% are mixed according to the proportion of 5:3:2, a plurality of alloy blocks with the diameter of 100mm are prepared by adopting a hot isostatic pressing method after being uniformly mixed, high-uniformity AlNoNb intermediate alloy cast ingots are prepared by adopting an electromagnetic suspension smelting method through the plurality of alloy blocks, and the AlNoNb intermediate alloy cast ingots are crushed into grains with the diameter of 3-5 mm by utilizing a metal crusher, so that the high uniformity of the ternary intermediate alloy is ensured, and no high-density inclusion exists. Wherein the single weight of the cast ingot is 10kg-15kg. The granularity of the titanium sponge in the step S1 is 5 mm-12.7 mm, the titanium sponge is 0-grade titanium sponge, the granularity of the zirconium sponge is 5 mm-8 mm, and the zirconium sponge is high-purity zirconium sponge.
S2, welding the 3 electrode rods pressed by the S2 into a consumable electrode by adopting a non-tungsten argon shield plasma welding method, wherein a welding path of the contact surface of the electrode rods adopts annular welding, so that the strength of the welding electrode is improved, and welding cracks are prevented from being generated;
s3, placing the consumable electrode obtained in the S2 into a vacuum consumable arc furnace for three times of smelting to obtain a WSTi6421 alloy cast ingot, wherein the three times of smelting specifically comprise:
smelting for the first time: adopting current control, polishing the surface of an ingot after tapping, wherein the specification of the crucible is phi 160-640 mm;
smelting for the second time: the constant melting speed control is adopted, the specification phi of the crucible is 220 mm-850 mm, and the smelting process of the second smelting is divided into two stages: 90% before the smelting process, the smelting speed is 5 kg/min-22 kg/min; 10% after the smelting process, the smelting speed is gradually reduced in the form of a near inverse proportion function curve.
Third smelting: the melting depth and the flow intensity of a molten pool are adopted to control, the specification phi of a crucible is 280 mm-920 mm, and the smelting process of the third smelting is divided into three stages: 10% before smelting process, controlling the depth of a molten pool at 0.2-0.5 m, and controlling the flow strength of the molten pool at 10-70 kg/s; 10-80% of the smelting process, wherein the depth of a molten pool is controlled to be 0.5-1.5 m, and the flow strength of the molten pool is 30-100 kg/s; feeding 20% of molten metal after the smelting process, gradually reducing the penetration at a rate of 0.02m/min, and enabling the flow intensity of a molten pool to be 10 kg/s-20 kg/s, wherein the total feeding time is not less than 50 min-200 min.
The WSTi6421 titanium alloy cast ingot comprises the following components in percentage by weight: 6.0 to 7.5 percent; mo:3.5 to 4.5 percent; zr:1.5 to 2.5 percent; nb:0.5 to 1.5 percent; o:0.08 to 0.15 percent, the balance being Ti and impurities, the total amount of impurity elements not exceeding 0.20 percent, the sum of the weight percentages of the components being 100 percent, and the specification of the WSTi6421 alloy cast ingot is phi 280mm to phi 920mm.
The following description is made in connection with specific technical processes:
example 1:
the invention relates to a preparation method of WSTi6421 titanium alloy, which comprises the following elements in percentage by weight: al:6.0 to 7.5 percent; mo:3.5 to 4.5 percent; zr:1.5 to 2.5 percent; nb:0.5 to 1.5 percent; o:0.08 to 0.15 percent, the balance being Ti and unavoidable impurities, the total amount of impurity elements not exceeding 0.20 percent, the sum of the weight percentages of the components being 100 percent.
The preparation method of the WSTi6421 titanium alloy specifically comprises the following steps:
step 1, batching and mixing:
the weight percentages of the elements are as follows: al:6.0 to 7.5 percent; mo:3.5 to 4.5 percent; zr:1.5 to 2.5 percent; nb:0.5 to 1.5 percent; o:0.08 to 0.15 percent, the balance being Ti and unavoidable impurities, the total amount of impurity elements not exceeding 0.20 percent, the sum of the weight percentages of the components being 100 percent. Alloy proportion is calculated, an AlMoNb ternary alloy with granularity of 3-5 mm, small-particle titanium sponge with granularity of 8-12.7 mm and small-particle zirconium sponge with granularity of 5-8 mm are respectively weighed and placed in a mixer with a built-in baffle, and a double-shaft reversing rotation mode is adopted for mixing, wherein the mixing time is 50-70 s.
Step 2, electrode rod pressing:
placing the uniformly mixed raw materials obtained in the step 1 at the lower part of a special hexagonal die, and pressing the uniformly mixed raw materials into 3 equilateral hexagonal electrode bars by using an oil press in a bidirectional secondary pressing mode, wherein the pressing strength is 25-30 MPa;
step 3, welding the consumable electrode:
clamping the electrode bars obtained in the step 2 by using a clamp, welding the 3 electrode bars pressed in the step 2 into a consumable electrode by using a non-tungsten argon shield plasma welding method, wherein the welding current between the electrode blocks is 250-500A, the welding voltage is 20-100V, and the welding strength of the welding electrode is improved by adopting annular welding on the contact surface welding path of the electrode blocks, so that welding cracks are prevented;
step 4,
Primary smelting: the specification phi of the crucible is 160mm, the vacuum degree before melting is less than or equal to 2.0Pa, the air leakage rate is less than or equal to 1.0Pa/min, the melting voltage is 28V, the melting current is 9kA, the arc stabilizing current is 6.0A, and the cooling time is 4h;
secondary smelting: the specification phi of the crucible is 220mm, the vacuum degree before melting is less than or equal to 1.8Pa, the air leakage rate is less than or equal to 0.8Pa/min, the melting speed is 8kg/min before the melting process, the melting speed is 10% after the melting process, the melting speed is gradually reduced in a form of a near inverse proportion function curve, and the cooling time is 5h.
Smelting for three times: the specification phi of the crucible is 280mm, the vacuum degree before melting is less than or equal to 1.8Pa, the air leakage rate is less than or equal to 0.5Pa/min, the melting tank depth is 0.2m at maximum before the melting process, and the flow strength of the melting tank is 20kg/s; 10-80% of the smelting process, wherein the depth of a molten pool is controlled to be 0.6m, and the flow intensity of the molten pool is 35kg/s; feeding 20% of molten alloy after the smelting process, gradually reducing the penetration at a rate of 0.02m/min, enabling the flow intensity of a molten pool to be 8kg/s, enabling the total feeding time to be not less than 60min, and cooling for 6h to obtain the WSTi6421 titanium alloy cast ingot with the phi 280mm specification.
Example 2:
the invention also provides a preparation method of the WSTi6421 titanium alloy cast ingot, which specifically comprises the following steps:
step 1, batching and mixing:
the weight percentages of the elements are as follows: al:6.0 to 7.5 percent; mo:3.5 to 4.5 percent; zr:1.5 to 2.5 percent; nb:0.5 to 1.5 percent; o:0.08 to 0.15 percent, the balance being Ti and unavoidable impurities, the total amount of impurity elements not exceeding 0.20 percent, the sum of the weight percentages of the components being 100 percent, calculating alloy proportion, respectively weighing AlMoNb ternary alloy with granularity of 3 to 5mm, small-particle sponge titanium with granularity of 8 to 12.7mm and sponge zirconium with granularity of 5 to 8mm, placing the three-dimensional alloy and the small-particle sponge titanium into a mixer with a built-in baffle, and mixing in a biaxial reversing rotation mode, wherein the mixing time is 50 to 70 seconds.
Step 2, electrode rod pressing:
placing the uniformly mixed raw materials obtained in the step 1 at the lower part of a special hexagonal die, and pressing the uniformly mixed raw materials into 3 equilateral hexagonal electrode bars by using an oil press in a bidirectional secondary pressing mode, wherein the pressing strength is 25-30 MPa;
step 3, welding the consumable electrode:
clamping the electrode rods obtained in the step 2) by using a clamp, welding the 3 electrode rods pressed in the step 2 into a consumable electrode by using a non-tungsten argon shield plasma welding method, wherein the welding current between the electrode blocks is 250-500A, the welding voltage is 20-100V, and the welding path of the contact surface of the electrode blocks adopts annular welding to improve the strength of the welding electrode and prevent welding cracks;
step 4,
Primary smelting: the specification phi of the crucible is 440mm, the vacuum degree before melting is less than or equal to 2.0Pa, the air leakage rate is less than or equal to 1.0Pa/min, the melting voltage is 30V, the melting current is 14kA, the arc stabilizing current is 9.0A, and the cooling time is 6h;
secondary smelting: the specification phi of the crucible is 560mm, the vacuum degree before melting is less than or equal to 1.8Pa, the air leakage rate is less than or equal to 0.8Pa/min, the melting speed is 13kg/min before the melting process, the melting speed is 10% after the melting process, the melting speed is gradually reduced in a form of a near inverse proportion function curve, and the cooling time is 8h.
Smelting for three times: the specification of the crucible is phi 640mm, the vacuum degree before melting is less than or equal to 1.8Pa, the air leakage rate is less than or equal to 0.5Pa/min, the melting tank depth is 0.2m at maximum before the melting process, and the flow strength of the melting tank is 30kg/s; 10-80% of the smelting process, wherein the depth of a molten pool is controlled to be 1.0m, and the flow intensity of the molten pool is 50kg/s; feeding 20% of the molten alloy after the smelting process, gradually reducing the penetration at a rate of 0.02m/min, enabling the flow intensity of a molten pool to be 10kg/s, enabling the total feeding time to be not less than 100min, and cooling for 8h to obtain the WSTi6421 titanium alloy cast ingot with the specification of phi 640 mm.
Example 3:
the invention also provides a preparation method of the WSTi6421 titanium alloy cast ingot, which specifically comprises the following steps:
step 1, batching and mixing:
the weight percentages of the elements are as follows: al:6.6%, mo:3.7%, zr:1.5%, nb:1.0%, si:0.27%, O:0.12 percent of Ti and unavoidable impurities, the balance being less than 0.40 percent of total impurity elements, wherein the sum of the weight percentages of the components is 100 percent, alloy proportions are calculated, the AlMoNb ternary alloy with the granularity of 3-5 mm is respectively weighed, the TiSi binary alloy with the granularity of 0.25-0.6 mm, the small-particle titanium sponge with the granularity of 8-12.7 mm and the zirconium sponge with the granularity of 5-8 mm are placed in a mixer with a built-in baffle, and the mixing time is 50-70 s by adopting a double-shaft reversing rotation mode.
Step 2, electrode rod pressing:
placing the uniformly mixed raw materials obtained in the step 1 at the lower part of a special hexagonal die, and pressing the uniformly mixed raw materials into 3 equilateral hexagonal electrode bars by using an oil press in a bidirectional secondary pressing mode, wherein the pressing strength is 25-30 MPa;
step 3, welding the consumable electrode:
clamping the electrode bars obtained in the step 2 by using a clamp, welding the 3 electrode bars pressed in the step 2 into a consumable electrode by using a non-tungsten argon shield plasma welding method, wherein the welding current between the electrode blocks is 250-500A, the welding voltage is 20-100V, and the welding strength of the welding electrode is improved by adopting annular welding on the contact surface welding path of the electrode blocks, so that welding cracks are prevented;
step 4,
Smelting for the first time: the specification phi of the crucible is 560mm, the vacuum degree before melting is less than or equal to 2.0Pa, the air leakage rate is less than or equal to 1.0Pa/min, the melting voltage is 22V, the melting current is 17kA, the arc stabilizing current is 12.0A, and the cooling time is 9h;
smelting for the second time: the specification phi of the crucible is 640mm, the vacuum degree before melting is less than or equal to 1.8Pa, the air leakage rate is less than or equal to 0.8Pa/min, the melting speed is 17kg/min before the melting process, the melting speed is 10% after the melting process, the melting speed is gradually reduced in a form of a near inverse proportion function curve, and the cooling time is 10 hours.
Third smelting: the specification phi of the crucible is 720mm, the vacuum degree before melting is less than or equal to 1.8Pa, the air leakage rate is less than or equal to 0.5Pa/min, the melting tank depth is 0.3m at maximum before the smelting process, and the flow strength of the melting tank is 50kg/s; 10-80% of the smelting process, wherein the depth of a molten pool is controlled to be 1.2m, and the flow intensity of the molten pool is 70kg/s; feeding 20% of molten alloy after the smelting process, gradually reducing the penetration at a rate of 0.02m/min, enabling the flow strength of a molten pool to be 15kg/s, enabling the total feeding time to be not less than 150min, and cooling for 10h to obtain the WSTi6421 titanium alloy cast ingot with the specification of phi 720 mm.
Example 4:
the invention also provides a preparation method of the WSTi6421 titanium alloy cast ingot, which specifically comprises the following steps:
step 1, batching and mixing:
the weight percentages of the elements are as follows: al:7.2%, mo:4.5%, zr:2.5%, nb:1.5%, si:0.35%, O:0.15 percent of Ti and unavoidable impurities, the balance being less than 0.40 percent of total impurity elements, wherein the sum of the weight percentages of the components is 100 percent, alloy proportions are calculated, the AlMoNb ternary alloy with the granularity of 3-5 mm is respectively weighed, the TiSi binary alloy with the granularity of 0.25-0.6 mm, the small-particle titanium sponge with the granularity of 8-12.7 mm and the zirconium sponge with the granularity of 5-8 mm are placed in a mixer with a built-in baffle, and the mixing time is 50-70 s by adopting a double-shaft reversing rotation mode.
Step 2, electrode rod pressing:
placing the uniformly mixed raw materials obtained in the step 1 at the lower part of a special hexagonal die, and pressing the uniformly mixed raw materials into 3 equilateral hexagonal electrode bars by using an oil press in a bidirectional secondary pressing mode, wherein the pressing strength is 25-30 MPa;
step 3, welding the consumable electrode:
clamping the electrode bars obtained in the step 2 by using a clamp, welding the 3 electrode bars pressed in the step 2 into a consumable electrode by using a non-tungsten argon shield plasma welding method, wherein the welding current between the electrode blocks is 250-500A, the welding voltage is 20-100V, and the welding strength of the welding electrode is improved by adopting annular welding on the contact surface welding path of the electrode blocks, so that welding cracks are prevented;
step 4,
Primary smelting: the specification phi of the crucible is 640mm, the vacuum degree before melting is less than or equal to 2.0Pa, the air leakage rate is less than or equal to 1.0Pa/min, the smelting voltage is 28V, the smelting current is 24kA, the arc stabilizing current is 16.0A, the cooling time is 10h, and the surface of an ingot is polished.
Secondary smelting: the specification phi of the crucible is 850mm, the vacuum degree before melting is less than or equal to 1.8Pa, the air leakage rate is less than or equal to 0.8Pa/min, the melting speed is 21kg/min before the melting process, the melting speed is 10% after the melting process, the melting speed is gradually reduced in a form of a near inverse proportion function curve, and the cooling time is 12h.
Smelting for three times: the specification phi of the crucible is 920mm, the vacuum degree before melting is less than or equal to 1.8Pa, the air leakage rate is less than or equal to 0.5Pa/min, the melting tank depth is 0.5m at maximum before the melting process, and the flow strength of the melting tank is 70kg/s; 10-80% of the smelting process, wherein the depth of a molten pool is controlled to be 1.5m, and the flow strength of the molten pool is 100kg/s; feeding 20% of molten alloy after the smelting process, gradually reducing the penetration at a rate of 0.02m/min, enabling the flow intensity of a molten pool to be 20kg/s, enabling the total feeding time to be not less than 200min, and cooling for 12h to obtain the WSTi6421 titanium alloy cast ingot with the specification of phi 920mm.
As shown in fig. 6 and 7, the samples and chemical component detection are carried out on the longitudinal head, the upper, the middle, the lower, the tail 5 points and the cross section 9 points of the WSTi6421 titanium alloy with the specifications of phi 280mm, phi 640mm, phi 720mm and phi 920mm prepared in the examples, namely, the longitudinal head, the upper, the middle, the lower, the tail 5 points and the cross section 9 points of the industrial large-scale ingot with the specifications of phi 280mm, phi 640mm, phi 720mm and phi 920mm, and the data show that the element component distribution uniformity of each part of the ingot is better, the element difference between the elements is less than or equal to 0.1 percent (weight percent wt%), and the ingot obtained by using the conventional smelting method is generally within 0.5 percent (weight percent wt%).
The results of the longitudinal 5-point chemical composition analysis of the phi 920mm specification WSTi6421 titanium alloy ingot obtained in example 4 are shown in fig. 1, wherein the longitudinal 5-point chemical composition is shown in table 1, and it can be seen from fig. 1 and table 1 that the ingot head, upper, middle, lower, and tail 5-point position sampling analysis, and the same ingot difference of Al element, mo element, zr element, and Nb element is 0.1%, (weight percent).
The 9-point chemical composition analysis results of the cross section of the WSTi6421 titanium alloy cast ingot with the specification of phi 920mm are shown in figures 2 to 5, and as can be seen from figures 2 to 5, the 9-point sampling analysis of the cross section of the five positions of the head, the upper part, the middle part, the lower part and the tail part of the cast ingot shows that the same ingot difference of Al element, mo element, zr element and Nb element is 0.1 percent (weight percent wt%).
TABLE 1 Phi 920mm specification WSTi6421 titanium alloy ingot longitudinal 5 Point chemical composition List
| Chemical element wt% | Al | Mo | Zr | Nb | Si | O |
| Head | 7.1 | 4.5 | 2.4 | 1.4 | 0.34 | 0.15 |
| Upper part | 7.2 | 4.5 | 2.4 | 1.5 | 0.34 | 0.15 |
| In (a) | 7.2 | 4.4 | 2.4 | 1.4 | 0.34 | 0.14 |
| Lower part(s) | 7.1 | 4.4 | 2.5 | 1.5 | 0.35 | 0.15 |
| Tail of tail | 7.1 | 4.4 | 2.4 | 1.4 | 0.35 | 0.15 |
The test result shows that the industrial-grade large-scale WSTi6421 titanium alloy cast ingot produced by the smelting process technology has uniform components and good batch stability, and is suitable for industrial production.
The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention.
It will be understood that the invention is not limited to what has been described above and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (4)
1. The preparation method of the WSTi6421 titanium alloy is characterized by comprising the following steps of:
s1, placing titanium sponge, zirconium sponge and AlNoNb ternary alloy particles in a mixer with a built-in baffle, mixing materials in a double-shaft reversing rotation mode, wherein the mixing time is 50S-70S, placing the uniformly mixed raw materials at the lower part of a hexagonal die, and pressing the uniformly mixed raw materials into 3 equilateral hexagonal electrode bars in a bidirectional secondary pressing mode by using an oil press, wherein the pressing strength is 25-30 MPa;
s2, welding the 3 electrode rods pressed in the S1 into a consumable electrode by adopting a non-tungsten argon shield plasma welding method, wherein a welding path of contact surfaces of the electrode rods adopts annular welding;
s3, placing the consumable electrode obtained in the S2 into a vacuum consumable arc furnace for three times of smelting to obtain a WSTi6421 alloy cast ingot, wherein the WSTi6421 titanium alloy cast ingot comprises the following components in percentage by weight: 6.0% -7.5%; mo:3.5% -4.5%; zr:1.5% -2.5%; nb:0.5% -1.5%; o:0.08% -0.15%, the balance being Ti and impurities, the total amount of impurity elements not exceeding 0.20%, the sum of the weight percentages of the components being 100%; the third smelting specifically comprises the following steps:
smelting for the first time: adopting current control, polishing the surface of an ingot after tapping, wherein the specification of the crucible is phi 160 mm-phi 640 mm;
smelting for the second time: adopting constant melting speed control, wherein the specification of the crucible is phi 220 mm-phi 850mm; the smelting process of the second smelting is divided into two stages: 90% before the smelting process, the smelting speed is 5 kg/min-22 kg/min; 10% after the smelting process, the smelting speed is gradually reduced in the form of an inverse proportion function curve;
third smelting: controlling the flow intensity of a molten pool by adopting the penetration, wherein the specification phi of a crucible is 280-920 mm; the smelting process of the third smelting is divided into three stages: 10% before the smelting process, controlling the depth of a molten pool to be 0.2-0.5 m, and controlling the flow strength of the molten pool to be 10-70 kg/s; in the stage of 10% -80% of the smelting process, the depth of a molten pool is controlled to be 0.5-1.5 m, and the flow strength of the molten pool is 30 kg/s-100 kg/s; feeding 20% of molten metal after the smelting process, gradually reducing the penetration at a rate of 0.02m/min, wherein the flow intensity of a molten pool is 10 kg/s-20 kg/s, and the total feeding time is 50 min-200 min.
2. The method for preparing a WSTi6421 titanium alloy ingot according to claim 1, wherein the preparing of the almonds ternary alloy particles in S1 specifically comprises: mixing Al with the particle purity of 99.999%, mo with the powder purity of 99.99% and Nb with the particle purity of 99.95% according to the specific gravity of 5:3:2, preparing a plurality of alloy blocks with the diameter of 100mm by adopting a hot isostatic pressing method after uniformly mixing, preparing a high-uniformity AlNoNb intermediate alloy cast ingot by adopting an electromagnetic suspension smelting method by adopting the alloy blocks, and crushing the AlNoNb intermediate alloy cast ingot into particles with the particle purity of 3 mm-5 mm by utilizing a metal crusher, wherein the single weight of the cast ingot is 10kg-15kg.
3. The preparation method of the WSTi6421 titanium alloy cast ingot according to claim 1, wherein the granularity of the titanium sponge in S1 is 5 mm-12.7 mm, the titanium sponge is 0-grade titanium sponge, the granularity of the zirconium sponge is 5 mm-8 mm, and the zirconium sponge is high-purity zirconium sponge.
4. The method for preparing the WSTi6421 titanium alloy cast ingot according to claim 1, wherein the specification of the WSTi6421 alloy cast ingot in S3 is phi 280 mm-phi 920mm.
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