Flux for submerged arc welding of TC4 titanium alloy, its preparation method, and its use

Abstract

The present invention provides a flux for submerged arc welding of TC4 titanium alloy, its preparation method and its use, which belongs to the technical field of welding materials. The powder is mixed with the mass fraction of BaCl2: 4.5%-5.5%, LiF: 1.8%-2.1%, NaF: 4.8%-5.1%, and the balance is CaF2. Method: Each raw material powder is mixed according to the powder ratio, stirred, and then a binder is added and further stirred to obtain a mixture, and the resulting mixture is first dried at a low temperature, then sintered at a high temperature, cooled to room temperature, and sieved to obtain the flux for submerged arc welding of TC4 titanium alloy. The flux of the present invention is used for submerged arc welding in combination with a wire for submerged arc welding of TC4 titanium alloy. The present invention scientifically adjusts the ratio of each component of the flux to optimize the viscosity, surface tension and fluidity of the slag. When combined with a wire for submerged arc welding of TC4 titanium alloy, it has excellent welding processing performance and mechanical properties.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority to a Chinese patent application with application number 202210025891.0, filed with the Chinese Patent Office on January 11, 2022, and titled "Flux for Submerged Arc Welding of TC4 Titanium Alloy, Its Preparation Method, and Its Use", and all of its contents are incorporated herein by reference.

[0002] The present invention belongs to the technical field of welding materials, and particularly relates to a flux for submerged arc welding of TC4 titanium alloy, its preparation method, and its use.

Background Art

[0003] TC4 titanium alloy is an important structural material and is widely used in fields such as aerospace, deep - diving machines, and weaponry due to its excellent comprehensive properties (low density, high specific strength, corrosion resistance, stable high - temperature resistance, etc.). Currently, gas metal arc welding and laser welding of filler wire are mainly used for the filler welding of thick - wall parts of TC4 titanium alloy. The above two welding methods can improve the welding efficiency by using a method of processing a groove with a narrow gap, but still need to use a one - pass multi - layer welding process. Not only is the significant improvement of its efficiency limited, but the probability of welding defects increases due to the filling of multiple passes during the welding process. At the same time, repeated heating multiple times may cause coarsening of the grains of the structure. Furthermore, the ultra - narrow gap welding technology also causes defects such as poor fusion of the side walls and slag mixing into the pores, so the requirements for welding equipment and processes are further increased. Therefore, in order to solve the current technical problems in the welding field of thick - wall titanium alloy, it is urgent to develop a welding material with a low probability of defect occurrence, high reliability, simplicity, and efficiency.

Summary of the Invention

Problems to be Solved by the Invention

[0004] To solve the above technical problems, the present invention provides a flux for submerged arc welding of TC4 titanium alloy, a preparation method thereof, and its use.

Means for Solving the Problems

[0005] To achieve the above object, the present invention provides the following technical solutions. The present invention provides a flux for submerged arc welding of TC4 titanium alloy prepared from a binder and powder materials. The above powder is mixed in a mass fraction of BaCl2: 4.5% - 5.5%, LiF: 1.8% - 2.1%, NaF: 4.8% - 5.1%, and the balance is CaF2.

[0006] Furthermore, the above binder is high-elastic potassium-sodium water glass, the elastic modulus is 2.8 - 3.1, and it is limited to a potassium-to-sodium ratio of 3:1.

[0007] Furthermore, the mass fraction of the binder in the above flux is limited to 3% - 5%.

[0008] Furthermore, the above powder is limited to be mixed in a mass fraction of BaCl2: 5%, LiF: 2%, NaF: 5%, and the rest is CaF2.

[0009] Furthermore, the mass percentage content of H in the above powder is ≤ 0.003%, the mass percentage content of N is ≤ 0.005%, the mass percentage content of O is ≤ 0.010%, the mass percentage content of S is ≤ 0.003%, and the mass percentage content of P is ≤ 0.003%.

[0010] The present invention provides a preparation method of the flux for submerged arc welding of TC4 titanium alloy described in the above technical solution. Step 1: Mix each raw material powder according to the powder ratio, stir dry for 3 - 5 minutes, then add the binder and continue stirring for another 4 - 6 minutes to obtain a mixture. Step 2: The mixture obtained in Step 1 is first dried at a low temperature, then sintered at a high temperature, cooled to room temperature, and then sieved to obtain a flux for submerged arc welding of TC4 titanium alloy.

[0011] Furthermore, the parameters of the low-temperature drying in Step 2 are limited to a temperature of 180 to 230°C and a time of 35 to 60 minutes.

[0012] Furthermore, the parameters of the high-temperature sintering in Step 2 are limited to a temperature of 700 to 900°C and a time of 50 to 70 minutes.

[0013] Furthermore, the sieve specification in Step 2 is limited to 10 to 80 meshes.

[0014] The present invention provides an application of the flux for submerged arc welding of TC4 titanium alloy described in the above solution for submerged arc welding of TC4 titanium alloy.

[0015] Furthermore, the flux for submerged arc welding of TC4 titanium alloy is restricted to be used in combination with the wire for submerged arc welding of TC4 titanium alloy.

[0016] Furthermore, for the welded joint after submerged arc welding of TC4 titanium alloy using the combination of the flux for submerged arc welding of TC4 titanium alloy and the wire for submerged arc welding of TC4 titanium alloy, the chemical composition and content of the deposited metal are as follows: C: ≤ 0.04 wt%, Al: 5.20 wt% - 5.45 wt%, V: 4.20 wt% - 4.80 wt%, Fe: 0.10 wt% - 0.20 wt%, Li: 0.15 wt% - 0.20 wt%, Mn: ≤ 0.015 wt%, P ≤ 0.01 wt%, S ≤ 0.02 wt%, N: ≤ 0.02 wt%, and the balance is Ti.

Advantages of the Invention

[0017] The advantages of the present invention compared with the prior art are as follows. The main means of adjusting the structure and performance of a titanium alloy submerged arc welding joint is to adjust the microstructure by changing the composition of the submerged arc welding wire and flux, and optimize the mechanical properties of the welding joint. The present invention proposes a flux for submerged arc welding of TC4 titanium alloy, compensates for the combustion loss of elements during the welding process, adds beneficial elements to the weld seam, and uses the submerged arc welding technology to perform efficient and high-quality welding of thick-walled titanium alloy parts, so as to realize the control of the structure and properties of the welding joint, and finally obtain a high-quality welding joint. The present invention scientifically adjusts the ratio of each component of the flux and optimizes the viscosity, surface tension and fluidity of the slag. When welded in combination with the wire for submerged arc welding of TC4 titanium alloy, the arc during welding is stable, there is less smoke and dust, slag removal is easy, the welding shape is beautiful, and the welding process performance and mechanical properties are excellent. The specific advantages are as follows.

[0018] 1) CaF2 in the present invention is mainly used to suppress the transfer of harmful elements such as H, O, N, etc. to the weld, control the S and P contents in the weld, help lower the melting point of the flux, and ensure the purity of the weld metal and the process performance of the flux. At the same time, CaF2 can also increase the slag permeability, lower the slag viscosity, and improve the slag removal performance. In addition, CaF2 also has the effect of increasing conductivity, improving the slag formation speed due to the generated high resistance heat, ensuring the fluidity of the slag, and insulating and protecting the molten pool in a timely manner. However, if there is too much CaF2, the conductivity will be too high, the slag viscosity will decrease, affecting the stability of the slag formation process, and thus affecting the formation of the weld.

[0019] 2) By adding BaCl2 to the flux, the slag generated can uniformly cover the surface of the welded metal, reduce the cooling rate of the welded metal, control the amount of α'-martensite, and obtain a good welding shape. With an appropriate content of BaCl2, it is ensured that the molten slag has an appropriate melting point and density, harmful impurities such as sulfur and phosphorus in the welded part are removed, the purity of the welded part is ensured, and thereby the impact toughness of the welded part is ensured. Furthermore, since BaCl2 has a lower melting point than BaF2, the welding heat input during the welding process can be reduced, thereby ensuring the refinement of the welded part structure. At the same time, the addition of BaCl2 significantly reduces the O and N contents in the welded part, ensuring the impact toughness of the welded part.

[0020] 3) Adding LiF to the flux can similarly lower the melting point of the flux and improve the process performance of the flux. Furthermore, by strictly controlling the content of metallic Li in the flux, the transformation temperature of the β-phase in the welded metal can be significantly increased, the residual β-phase can be refined, and the plasticity and toughness of the welded metal can be improved.

[0021] 4) The addition of NaF and LiF in the flux can combine with H in the welded part to form an overflow of HF gas, which is beneficial for reducing the partial pressure of H in the arc atmosphere, playing a role in dehydrogenation, and reducing the occurrence of cracks caused by hydrogen.

[0022] 5) By adding an appropriate content of highly elastic potassium-sodium water glass to the flux, the stability of the arc is improved and the alkalinity of the flux is increased. When the content of highly elastic potassium-sodium water glass in the water glass exceeds 5%, the hydrogen content in the welded part tends to increase significantly. Therefore, the mass fraction of highly elastic potassium-sodium water glass in the flux is controlled to be 3% - 5%.

Embodiments for Carrying out the Invention

[0023] Hereinafter, the present invention will be further described with reference to examples and drawings. Example 1: The flux for submerged arc welding of TC4 titanium alloy in this example is prepared from a binder and powder materials. Here, the powder is mixed in a mass fraction of BaCl2: 4.5%, LiF: 2.0%, NaF: 4.9%, and the balance is CaF2. The above binder is high-elastic potassium-sodium water glass, with an elastic modulus of 2.8 - 3.1, a potassium-to-sodium ratio of 3:1, and the H mass percentage content in the above powder ≤ 0.003%, N mass percentage content ≤ 0.005%, O mass percentage content ≤ 0.010%, S mass percentage content ≤ 0.003%, and P mass percentage content ≤ 0.003%.

[0024] The preparation method of the above flux is as follows: Step 1: Mix each raw material powder according to the powder ratio, perform dry stirring for 4 minutes, then add the binder and continue stirring for another 5 minutes to obtain a mixture. Step 2: First, dry the mixture obtained in Step 1 at a low temperature of 200°C for 45 minutes, then sinter it at a high temperature of 800°C for 60 minutes, cool it to room temperature, and then sieve it through an 80-mesh sieve to obtain the flux for submerged arc welding of TC4 titanium alloy.

[0025] Example 2 The flux for submerged arc welding of TC4 titanium alloy in this example is prepared from a binder and powder materials. Here, the powder is mixed in a mass fraction of BaCl2: 5%, LiF: 2.1%, NaF: 5.1%, and the balance is CaF2. The above binder is high-elastic potassium-sodium water glass, with an elastic modulus of 2.8 - 3.1, a potassium-to-sodium ratio of 3:1, the mass fraction of the above binder in the flux is 4%, and the H mass percentage content in the above powder ≤ 0.003%, N mass percentage content ≤ 0.005%, O mass percentage content ≤ 0.010%, S mass percentage content ≤ 0.003%, and P mass percentage content ≤ 0.003%.

[0026] The preparation method of the above flux is as follows: Step 1: Mix each raw material powder according to the powder ratio, perform dry stirring for 4 minutes, then add the binder and continue stirring for another 5 minutes to obtain a mixture. The mixture obtained in Step 1 is first dried at a low temperature of 200 °C for 45 minutes, then sintered at a high temperature of 800 °C for 60 minutes, cooled to room temperature, and then sieved through an 80-mesh sieve to obtain a flux for submerged arc welding of TC4 titanium alloy, which is carried out according to Step 2.

[0027] Application Example 1: The specific process of using the fluxes for submerged arc welding of TC4 titanium alloy in Examples 1 to 2 for submerged arc welding of TC4 titanium alloy is as follows. The fluxes for submerged arc welding of TC4 titanium alloy in Examples 1 to 2 and the wire for submerged arc welding of TC4 titanium alloy are used in combination to perform multi-pass multi-layer submerged arc welding. The base material is a TC4 titanium alloy plate with specifications of 300 mm × 200 mm × 30 mm. V-groove preparation is carried out, the single-side groove angle is 30°, the groove blunt end is 5 mm, the groove root gap is 10 mm, and a total of 12 passes of welding are completed to weld the test plate. The interpass temperature is controlled within 100 °C, and an alternating current welding power source is used. Table 1 shows the welding process parameters, Table 2 shows the chemical composition results of the weld metal in the welded joint, and Table 3 shows the mechanical property test results of the welded joint.

[0028]

Table 1

[0029]

Table 2

[0030]

Table 3

[0031] The above description of the embodiments is used only to assist in understanding the method of the present invention and its central concepts. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications are also included in the scope of the claims of the present invention. Various modifications to these embodiments will be readily 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. Therefore, the present invention should not be limited to the embodiments shown herein, but the broadest scope consistent with the principles and novel features disclosed herein should be given.

Claims

1. Prepared from a binder and a powder material, the powder being BaCl ２ : 4.5% - 5.5%, LiF: 1.8% - 2.1%, NaF: 4.8% - 5.1%, the balance being CaF ２ A flux for submerged arc welding of TC4 titanium alloy, characterized in that it is mixed in a mass fraction.

2. The flux for submerged arc welding of TC4 titanium alloy according to claim 1, characterized in that the binder is high-elastic potassium-sodium water glass and the potassium-to-sodium ratio is 3:

1.

3. The flux for submerged arc welding of TC4 titanium alloy according to claim 1, characterized in that the mass fraction of the binder in the flux is 3% - 5%.

4. The powder is BaCl ２ : 5%, LiF: 2%, NaF: 5%, the rest being CaF ２ A flux for submerged arc welding of TC4 titanium alloy according to claim 1, characterized in that it is mixed in a mass fraction.

5. The powder is BaCl ２ : 4.5%, LiF: 2.0%, NaF: 4.9%, the rest being CaF ２ A flux for submerged arc welding of TC4 titanium alloy according to claim 1, characterized in that it is mixed in a mass fraction.

6. The powder is BaCl ２ : 5%, LiF: 2.1%, NaF: 5.1%, the rest being CaF ２ A flux for submerged arc welding of TC4 titanium alloy according to claim 1, characterized in that it is mixed in a mass fraction.

7. The flux for submerged arc welding of TC4 titanium alloy according to claim 1, characterized in that the H mass percentage content in the powder ≤ 0.003%, the N mass percentage content ≤ 0.005%, the O mass percentage content ≤ 0.010%, the S mass percentage content ≤ 0.003%, and the P mass percentage content ≤ 0.003%. Claim 8 Step 1 of mixing each raw material powder according to the powder ratio, dry stirring for 3 to 5 minutes, then adding a binder and continuously stirring for another 4 to 6 minutes to obtain a mixture; The method for preparing a flux for submerged arc welding of TC4 titanium alloy according to any one of claims 1 to 7, characterized in that it is carried out according to Step 2 of first drying the mixture obtained in Step 1 at a low temperature, then sintering at a high temperature, cooling to room temperature, and then sieving to obtain a flux for submerged arc welding of TC4 titanium alloy. Claim 9 The use of a flux for submerged arc welding of TC4 titanium alloy according to any one of claims 1 to 7, characterized in that the flux is used for submerged arc welding of TC4 titanium alloy. Claim 10 The chemical composition and content of the weld metal of the welded part after submerged arc welding of TC4 titanium alloy, using the flux for submerged arc welding of TC4 titanium alloy and the wire for submerged arc welding of TC4 titanium alloy in combination, are: C: ≤ 0.04 wt%, Al: 5.20 wt% - 5.45 wt%, V: 4.20 wt% - 4.80 wt%, Fe: 0.10 wt% - 0.20 wt%, Li: 0.15 wt% - 0.20 wt%, Mn: ≤ 0.015 wt%, P ≤ 0.01 wt%, S ≤ 0.02 wt%, N: ≤ 0.02 wt%, and the balance is Ti. The use according to claim 9 is characterized by this.

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