1. The ultrahigh-toughness titanium alloy for the arc additive is characterized by comprising the following components in percentage by mass: 5.5-9.0% of Al, 5.5-9.0% of Zr, 0.5-3.0% of Sn, 0-3.0% of Cu, and the balance of Ti and inevitable impurities.

2. A method of manufacturing a titanium alloy structural member, comprising the steps of:

s1, according to the component system and the weight ratio of the titanium alloy in claim 1, designing and selecting pure titanium wires, pure aluminum wires, pure zirconium wires, pure tin wires and pure copper wires as raw materials, taking the pure titanium wires with the diameter of 3mm as a reference, calculating the diameters of the pure aluminum wires, the pure zirconium wires, the pure tin wires and the pure copper wires on the premise of ensuring the consistent length of each pure metal wire, and then preparing each pure metal wire;

s2, mixing pure titanium wires, pure aluminum wires, pure zirconium wires, pure tin wires and pure copper wires in a winding or bundling manner to prepare mixed wires;

s3, manufacturing a titanium alloy structural part by using a mixed wire by adopting an electric arc additive method;

s4, eliminating the titanium alloy structural part through vacuum annealing in the manufacturing process or after the titanium alloy structural part is manufactured

Residual stress in the steel.

3. The method of manufacturing a titanium alloy structural member according to claim 2, wherein: in step S3, the method for manufacturing a titanium alloy structural member by using an arc additive manufacturing method includes the specific steps of: the method comprises the steps of taking a pure titanium plate or a Ti-6Al-4V alloy plate as a substrate, adopting a manual tungsten argon arc welding method to stack, firstly stacking a transition layer with the thickness of 10mm, then stacking layer by layer until the target size of a titanium alloy structural member is reached, wherein the voltage is 10-15V and the current is 80-150A in the stacking process, adopting argon for protection, the flow of the argon is 8-20L/min, and machining and removing the substrate and the transition layer after stacking is completed.

4. The method of manufacturing a titanium alloy structural member according to claim 2, wherein: in step S4, the temperature of the vacuum annealing is 500-800 ℃, and the annealing time is 1 h.

5. The method of manufacturing a titanium alloy structural member according to claim 2, wherein: in step S4, when the section thickness of the titanium alloy structural part is larger than 50mm, vacuum annealing is carried out in the manufacturing process of the titanium alloy structural part; and when the section thickness of the titanium alloy structural part is not more than 50mm, performing vacuum annealing after the titanium alloy structural part is manufactured.

6. The method of manufacturing a titanium alloy structural member according to claim 2, wherein: the properties achieved for the titanium alloy structural member are as follows: r_m≥800MP、R_P0.2≥700MP、A≥15%、KV₂≥60J、K_IC≥120MPa·m^1/2、K_ISCC≥90MPa·m^1/2。

Background

The additive manufacturing technology has the advantages of near net shape forming, one-step forming and the like, and can manufacture large metal integral structural parts at one time. The electric arc additive manufacturing technology takes an electric arc as a heat source, takes wire materials as stacking raw materials, adopts a layer-by-layer overlaying mode to manufacture a metal solid component, and has the remarkable advantages of high forming speed, high density, small residual stress, low manufacturing cost and the like. The titanium alloy electric arc additive manufacturing structural member has wide application prospect in the field of key force bearing structures of aerospace, ships and marine equipment in the future.

With the development of fracture mechanics, a key force-bearing structure of titanium alloy is generally designed in a safety mode, and not only is enough strength required, but also higher plasticity and good toughness are required to be considered. Generally, the yield strength of the titanium alloy is not lower than 700MPa, the elongation is not lower than 15 percent, the impact toughness is not lower than 60J, and the fracture toughness is not lower than 100 MPa.m^1/2. The matching of strength, plasticity and toughness is increasingly regarded as an important technical index of titanium alloy performance.

At present, the traditional titanium alloy components are generally used for manufacturing the titanium alloy material by the electric arc additive manufacturing, the traditional titanium alloy components generally contain 2 wt% -10 wt% of beta stable elements, 2 wt% -50 wt% of beta phases are formed in the solidification process, harmful phases are easily separated out from the beta phases in the complex thermal history of the additive manufacturing, the plasticity and toughness of the material are reduced, and even cracking is caused in the manufacturing process. In addition, the size of a molten pool and a heat affected zone in the electric arc additive forming process is large, the heat accumulation in the forming process is high, large-size columnar crystals and a relatively obvious heat affected strip are often formed, the plasticity and toughness of the material are reduced, and the elongation of the alloy such as the electric arc additive Ti-6Al-4V and the like which is researched at present is generally not more than 15%.

Therefore, it is urgently needed to develop a novel ultrahigh-toughness titanium alloy to meet the common requirement of key force-bearing structural members for aerospace, ships and ocean engineering.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides an ultrahigh-toughness titanium alloy for arc additive manufacturing and a manufacturing method of a titanium alloy structural part.

In order to achieve the purpose, the invention adopts the specific scheme that:

an ultra-high toughness titanium alloy for arc additive manufacturing comprises the following components in percentage by mass: 5.5-9.0% of Al, 5.5-9.0% of Zr, 0.5-3.0% of Sn, 0-3.0% of Cu, and the balance of Ti and inevitable impurities.

A manufacturing method of a titanium alloy structural member comprises the following steps:

s1, according to the component system and the weight ratio of the titanium alloy in claim 1, designing and selecting pure titanium wires, pure aluminum wires, pure zirconium wires, pure tin wires and pure copper wires as raw materials, taking the pure titanium wires with the diameter of 3mm as a reference, calculating the diameters of the pure aluminum wires, the pure zirconium wires, the pure tin wires and the pure copper wires on the premise of ensuring the consistent length of each pure metal wire, and then preparing each pure metal wire;

s2, mixing pure titanium wires, pure aluminum wires, pure zirconium wires, pure tin wires and pure copper wires in a winding or bundling manner to prepare mixed wires;

s3, manufacturing a titanium alloy structural part by using a mixed wire by adopting an electric arc additive method;

and S4, eliminating residual stress in the titanium alloy structural component through vacuum annealing in the manufacturing process or after the titanium alloy structural component is manufactured.

Further, in step S3, the method for manufacturing the titanium alloy structural member by the arc additive manufacturing method specifically includes: the method comprises the steps of taking a pure titanium plate or a Ti-6Al-4V alloy plate as a substrate, adopting a manual tungsten argon arc welding method to stack, firstly stacking a transition layer with the thickness of 10mm, then stacking layer by layer until the target size of a titanium alloy structural member is reached, wherein the voltage is 10-15V and the current is 80-150A in the stacking process, adopting argon for protection, the flow of the argon is 8-20L/min, and machining and removing the substrate and the transition layer after stacking is completed.

Further, in step S4, the temperature of the vacuum annealing is 500-800 ℃, and the annealing time is 1 h.

Further, in step S4, when the cross-sectional thickness of the titanium alloy structural member is greater than 50mm, performing vacuum annealing during the manufacturing process of the titanium alloy structural member; and when the section thickness of the titanium alloy structural part is not more than 50mm, performing vacuum annealing after the titanium alloy structural part is manufactured.

Further, the properties achieved for the titanium alloy structural member are as follows: r_m≥800MP、R_P0.2≥700MP、A≥15％、KV₂≥60J、K_IC≥120MPa·m^1/2、K_ISCC≥90MPa·m^1/2。

The titanium alloy has a high phase transition point of about 1000-1040 ℃, and crystal grains are not easy to grow in the additive manufacturing process; the alloy has small cold and hot cracking tendency, and no cold and hot cracks exist when the thickness of the section of the structural part is not more than 120 mm; the stability of the structure at high temperature is good, and the impact toughness does not exceed 30% under the complex thermal history of additive manufacturing.

According to the invention, 5.5-9.0 wt% of Al element is added, the Al element can play an effective solid solution strengthening role in the titanium alloy, the (alpha + beta)/beta transformation point is improved, the Al element can be dissolved in the alpha phase in a solid manner, and a compound phase is not generated when the aluminum equivalent is less than 9 wt%, so that the strength of the titanium alloy can be improved, and the alloy can keep good plasticity;

the invention adds 5.5-9.0 wt% of Zr element, the crystal lattice type of Zr is completely the same as that of Ti, the atomic radius is also similar, the Zr element can form an infinite mutual solution in alpha Ti and beta Ti, which plays a role in solid solution strengthening, meanwhile, the Zr can promote the twin crystal deformation of the alloy, and has certain functions of ensuring the crack resistance of the material, improving the impact toughness and the fracture toughness.

The Sn element of 0.5-3.0 wt% is added, so that the strength of the alloy can be further improved, but the Sn element is easy to form Ti3Sn intermetallic compounds in the titanium alloy and has adverse effect on the plasticity and toughness, so that the adding amount of the Sn element is not more than 3.0 wt%.

According to the invention, 0-3.0 wt% of Cu element is added, the solid solubility of the Cu element in titanium is small, the Cu element does not play a role in beta stabilization generally, but forms Ti in the solidification process of electric arc additive₂Cu precipitationPhase, preventing grain growth.

The alloy only contains a small amount of or does not contain beta stable elements, and columnar crystals and heat affected strips are not easy to form in the additive manufacturing process, so that the plasticity of the alloy is improved.

Has the advantages that:

1. the titanium alloy in the present invention is a near- α titanium alloy, and contains alloy elements such as Al, Sn, Zr, and Cu. Wherein, the Al element is an alpha phase stable element, which can improve the strength and further improve the phase change point and prevent the abnormal growth of crystal grains; zr and Sn are neutral elements and have the effect of further improving the strength of the titanium alloy, wherein the Zr can also stabilize the additive manufacturing performance of the material and improve the crack resistance; the solubility of Cu in the titanium matrix is relatively low, typically as Ti₂Cu exists in a precipitated phase form, and can refine grains. The titanium alloy has high plasticity and toughness, and the matching property with the strength is kept consistent. The alloy has good technical application and market prospect in the fields of aerospace, ship, ocean engineering and the like.

2. The invention can adopt pure metal wires to directly perform electric arc material increase to manufacture a large structural part, can save the steps of alloy smelting, forging, wire drawing and the like, greatly shortens the manufacturing flow, improves the material yield, can obviously improve the manufacturing efficiency and reduces the manufacturing cost.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, belong to the scope of the present invention.

An ultra-high toughness titanium alloy for arc additive manufacturing comprises the following components in percentage by mass: 5.5-9.0% of Al, 5.5-9.0% of Zr, 0.5-3.0% of Sn, 0-3.0% of Cu, and the balance of Ti and inevitable impurities.

A manufacturing method of a titanium alloy structural member comprises the following steps:

s1, according to the component system and the weight ratio of the titanium alloy, designing and selecting pure titanium wires, pure aluminum wires, pure zirconium wires, pure tin wires and pure copper wires as raw materials, taking the pure titanium wires with the diameter of 3mm as a reference, calculating the diameters of the pure aluminum wires, the pure zirconium wires, the pure tin wires and the pure copper wires on the premise of ensuring the consistent length of the pure metal wires, and then preparing the pure metal wires;

s2, mixing pure titanium wires, pure aluminum wires, pure zirconium wires, pure tin wires and pure copper wires in a winding or bundling manner to prepare mixed wires;

s3, manufacturing a titanium alloy structural part by using a mixed wire by adopting an electric arc additive method; specifically, a pure titanium plate or a Ti-6Al-4V alloy plate is used as a substrate, a manual tungsten argon arc welding method is adopted for stacking, a transition layer with the thickness of 10mm is firstly stacked, then the transition layer is stacked layer by layer until the target size of a titanium alloy structural part is reached, the voltage is 10-15V and the current is 80-150A in the stacking process, argon is adopted for protection, the argon flow is 8-20L/min, and the substrate and the transition layer are machined and removed after the stacking is finished;

s4, eliminating residual stress in the titanium alloy structural member through vacuum annealing in the manufacturing process or after the manufacturing of the titanium alloy structural member is completed, wherein the temperature of the vacuum annealing is 500-800 ℃, and the annealing time is 1 h; when the section thickness of the titanium alloy structural part is more than 50mm, carrying out vacuum annealing in the manufacturing process of the titanium alloy structural part; and when the section thickness of the titanium alloy structural part is not more than 50mm, performing vacuum annealing after the titanium alloy structural part is manufactured.

In step S1, the method for calculating the diameter of the pure metal wire is described by taking a pure titanium wire and a pure aluminum wire as examples: the length of each pure titanium wire and the length of each pure aluminum wire are L, the mass of each pure titanium wire is w1, the radius of each pure titanium wire is d1, and the density of each pure titanium wire is rho 1; the pure aluminum wire has the mass of w2, the radius of d2 and the density of rho 2; then

Under the condition that w1, w2, rho 1, rho 2 and d1 (taking 3mm as d 1) are known, the diameter of the pure aluminum wire can be calculated.

Example 1

An ultra-high toughness titanium alloy for arc additive manufacturing comprises the following components in percentage by mass: 5.5 percent of Al5, 9.0 percent of Zr0, 0.5 percent of Sn0, and the balance of Ti and inevitable impurities.

The manufacturing method of the titanium alloy structural member (shell-and-tube heat exchanger shell with the section thickness of 15mm) comprises the following steps: calculating the diameter of the required wire material according to the weight ratio of the alloy, preparing pure metal wire materials, wherein the diameter of the titanium wire is 3.0mm, the diameter of the aluminum wire is 1.0mm, the diameter of the zirconium wire is 0.8mm, the diameter of the tin wire is 0.2mm, and preparing the wire materials into mixed wires in a bundling mode; and (3) manufacturing a shell of the shell-and-tube heat exchanger by using an electric arc as a heat source additive, wherein the electric arc parameters are as follows: voltage 12V, current 120A, argon flow 8L/min. After the structural member is manufactured, stress relief annealing is carried out, the annealing temperature is 500 ℃, and the annealing time is 1 h.

Example 2

An ultra-high toughness titanium alloy for arc additive manufacturing comprises the following components in percentage by mass: 9% of Al, 5.5% of Zr, 3% of Sn, 3% of Cu, and the balance of Ti and inevitable impurities.

The manufacturing method of the titanium alloy structural part (the titanium alloy propeller with the maximum thickness of the section of 80mm) comprises the following steps: calculating the diameter of the required wire material according to the weight ratio of the alloy, preparing pure metal wire materials, wherein the diameter of the titanium wire is 3.0mm, the diameter of the aluminum wire is 1.2mm, the diameter of the zirconium wire is 0.6mm, the diameter of the tin wire is 0.4mm, and the diameter of the copper wire is 0.4mm, and preparing the wire materials into mixed wires in a bundling mode; the titanium alloy propeller is manufactured by using electric arc as a heat source in an additive manufacturing mode, and the electric arc parameters are as follows: voltage is 12V, current is 120A, and argon flow is 20L/min; and carrying out once stress relief annealing at the annealing temperature of 500 ℃ for 1h every time 20kg of the materials are accumulated.

Example 3

An ultra-high toughness titanium alloy for arc additive manufacturing comprises the following components in percentage by mass: 6% of Al, 6% of Zr, 3% of Sn, and the balance of Ti and inevitable impurities.

The manufacturing method of the titanium alloy structural part (the titanium alloy high-pressure gas cylinder with the maximum thickness of the section of 80mm) comprises the following steps: calculating the diameter of the required wire material according to the weight ratio of the alloy, preparing pure metal wire materials, wherein the diameter of the titanium wire is 3.0mm, the diameter of the aluminum wire is 1.0mm, the diameter of the zirconium wire is 0.6mm, the diameter of the tin wire is 0.5mm, and preparing the mixed wire by mutually winding the wire materials. The method comprises the following steps of (1) manufacturing a titanium alloy high-pressure gas cylinder by using electric arcs as heat sources in an additive manufacturing mode, wherein the electric arc parameters are as follows: voltage 15V, current 100A, argon flow 12L/min. After the structural member is manufactured, stress relief annealing is carried out, the annealing temperature is 550 ℃, and the annealing time is 1 h.

Example 4

An ultra-high toughness titanium alloy for arc additive manufacturing comprises the following components in percentage by mass: 9% of Al, 6% of Zr, 2% of Sn, and the balance of Ti and inevitable impurities.

The manufacturing method of the titanium alloy structural part (the titanium alloy spherical shell with the maximum thickness of the section of 12mm) comprises the following steps: calculating the diameter of the required wire material according to the weight ratio of the alloy, preparing pure metal wire materials, wherein the diameter of the titanium wire is 3.0mm, the diameter of the aluminum wire is 1.2mm, the diameter of the zirconium wire is 0.6mm, the diameter of the tin wire is 0.4mm, and preparing the wire materials into mixed wires in a bundling mode; the titanium alloy propeller is manufactured by using electric arc as a heat source in an additive manufacturing mode, and the electric arc parameters are as follows: voltage is 12V, current is 120A, and argon flow is 10L/min; after the structural member is manufactured, stress relief annealing is carried out, the annealing temperature is 800 ℃, and the annealing time is 1 h.

Example 5

An ultra-high toughness titanium alloy for arc additive manufacturing comprises the following components in percentage by mass: 6% of Al, 9% of Zr, 3% of Sn, 3% of Cu, and the balance of Ti and inevitable impurities.

The manufacturing method of the titanium alloy structural part (the titanium alloy honeycomb structure with the maximum thickness of the section of 55mm) comprises the following steps: calculating the diameter of the required wire material according to the weight ratio of the alloy, preparing pure metal wire materials, wherein the diameter of the titanium wire is 3.0mm, the diameter of the aluminum wire is 1.0mm, the diameter of the zirconium wire is 0.8mm, the diameter of the tin wire is 0.5mm, the diameter of the copper wire is 0.4mm, and the pure metal wire materials are mutually wound to prepare a mixed wire. The titanium alloy honeycomb structure is manufactured by using electric arc as a heat source in an additive manufacturing mode, and the electric arc parameters are as follows: voltage 15V, current 150A, argon flow 15L/min. And carrying out once stress relief annealing at the annealing temperature of 500 ℃ for 1h every time 20kg of the materials are accumulated.

The titanium alloy structural members manufactured in examples 1 to 5 were subjected to performance tests, and the results thereof are shown in table 1.

Table 1 results of performance tests of titanium alloy structural members manufactured in examples 1 to 5

As can be seen from Table 1, the ultrahigh-toughness titanium alloy has both high plasticity and good toughness under the condition that the yield strength is higher than 740MPa, particularly has the room-temperature impact energy of more than 60J, is equivalent to or higher than a deformed titanium alloy forging with the same strength, and is very suitable for large structural members of ships and ocean engineering.

The foregoing is merely a preferred embodiment of the invention and is not to be construed as limiting the invention in any way. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.