A gradient wear-resistant band of a downhole titanium alloy drill rod, a drill rod and a preparation method

Abstract

The application discloses a gradient wear-resistant band of a downhole titanium alloy drill rod, a drill rod and a preparation method, and the preparation method comprises the following steps: S1, surface treatment of a joint base body of the titanium alloy drill rod; S2, preparation of a wear-resistant band on an outer layer of the joint of the titanium alloy drill rod, wherein the structure of the wear-resistant band comprises a bonding bottom layer, an intermediate layer and a wear-resistant layer from inside to outside; and S3, under the protection of a gas, the bonding bottom layer, the intermediate layer and the wear-resistant layer of the wear-resistant band are sequentially prepared on the joint base body of the titanium alloy drill rod; the graphene reinforced titanium-based gradient structure wear-resistant band is prepared on the joint base body of the titanium alloy drill rod by adopting an ultra-high-speed laser cladding process, and the wear-resistant band and the drill rod prepared by the preparation method. By the method, the in-situ generated wear-resistant band material layer is prepared on the titanium alloy base body surface, the dense metallurgical combination of the titanium alloy base body and the wear-resistant coating is realized, the wear resistance and the service life of the drill rod are improved, and the wear-resistant band has good corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of wear resistance in downhole titanium alloy drill pipes, specifically to a gradient wear-resistant band for downhole titanium alloy drill pipes, the drill pipe itself, and a method for its preparation. Background Technology

[0002] Currently, with the increasing demand for oil and gas energy, my country has intensified its exploration and development efforts for ultra-deep and extra-deep oil and gas resources. Most oilfields now have drilling depths exceeding 9000m and service temperatures exceeding 200℃. Conventional alloy steel drill pipes, due to their high density and heavy drill string load, result in high drilling loads. Furthermore, conventional steel drill pipes have poor resistance to hydrogen sulfide stress corrosion and carbon dioxide corrosion, leading to frequent drill string failures. Therefore, conventional steel drill pipes can no longer meet the demanding requirements of ultra-deep oil and gas resource exploration and development.

[0003] Titanium alloy drill pipes are suitable for ultra-deep well drilling due to their high specific strength, low density, low elastic modulus, fatigue resistance, and insensitivity to corrosive media such as hydrogen sulfide dioxide. However, during drilling, the drill pipe is in direct contact with the wellbore, resulting in very rapid wear and significantly increasing the cost of oilfield extraction. For traditional steel drill pipes, the current main method is to weld a wear-resistant strip with a thickness of not less than 2mm onto the drill pipe joint surface to effectively protect the joint. The wear-resistant strip material is generally hard alloy steel powder.

[0004] However, due to the significant differences in properties between steel and titanium alloys, existing cemented carbide steel wear-resistant strip materials and titanium alloy drill pipe materials have poor weldability, making effective bonding difficult through welding. Furthermore, welding generates significant heat input, easily causing stress cracking in both the substrate and the wear-resistant strip. The high dilution rate also reduces the performance of the wear-resistant layer, leading to post-weld cracking and spalling. In addition, since the hardness of titanium alloy drill pipe materials is generally 28-33 HRC, only half that of wear-resistant strip materials, during drilling, impact loads from collisions with the wellbore can easily cause the wear-resistant strip to crack or spall due to the eggshell effect. Therefore, there is an urgent need to develop wear-resistant strip materials and preparation methods suitable for titanium alloy drill pipes. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a gradient wear-resistant band for downhole titanium alloy drill pipe, the drill pipe itself, and a preparation method thereof. By employing an ultra-high-speed laser cladding method, an in-situ wear-resistant band material layer is generated on the surface of the titanium alloy substrate, achieving a dense metallurgical bond between the titanium alloy substrate and the wear-resistant coating. This improves the wear resistance and service life of the drill pipe, and the wear-resistant band also possesses excellent corrosion resistance.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing a gradient wear-resistant band for downhole titanium alloy drill pipe, the method comprising the following steps:

[0008] S1: Surface treatment of the joint substrate of titanium alloy drill pipe;

[0009] S2: A wear-resistant band is prepared on the outer layer of the joint of the titanium alloy drill pipe. The wear-resistant band structure consists of an adhesive underlayer, an intermediate layer and a wear-resistant layer from the inside out.

[0010] S3: Under the protection of gas, the bonding underlayer, intermediate layer and wear-resistant layer of the wear-resistant band are prepared sequentially on the joint substrate of the titanium alloy drill pipe;

[0011] The wear-resistant belt raw materials include TiC powder, Ti6Al4V titanium alloy powder and Co53-Brgo formed by partially reduced graphene oxide coated with Co53. The graphene-reinforced titanium-based gradient structure wear-resistant belt is prepared on the titanium alloy drill pipe joint substrate by using an ultra-high speed laser cladding process.

[0012] Furthermore, the surface treatment includes removing oil stains from the surface and grinding to a roughness of 10≤Ra≤25μm and an ellipticity of ≤0.5%.

[0013] Furthermore, the bonding substrate is made of Ti6Al4V titanium alloy powder and 20wt% to 30wt% Co53-Brgo, which are mixed and vacuum ball-milled for 5 to 6 hours, and then dried for 1 to 2 hours.

[0014] The intermediate layer is made of Ti6Al4V titanium alloy powder, 40wt% to 50wt% Co53-Brgo, and 1wt% to 2wt% TiC powder. After mixing, it is vacuum ball-milled for 6 to 7 hours and then dried for 1 to 2 hours.

[0015] The wear-resistant surface layer is made of 10wt% to 20wt% Ti6Al4V titanium alloy powder, Co53-Brgo, and 3wt% to 5wt% TiC powder. After mixing, it is vacuum ball-milled for 5 to 6 hours and then dried for 1 to 2 hours.

[0016] Furthermore, when preparing the bonding underlayer using high-speed laser cladding technology: under argon atmosphere protection, the gas flow rate is 21-26 L / min;

[0017] When preparing the intermediate layer and wear-resistant layer using high-speed laser cladding technology, a mixed atmosphere of argon and nitrogen is used for protection; among which,

[0018] When preparing the intermediate layer using high-speed laser cladding: it is protected by a mixed atmosphere of argon and nitrogen, wherein the nitrogen content is 1-2 ppm and the gas flow rate is 21-26 L / min;

[0019] When preparing the wear-resistant layer using high-speed laser cladding: it is protected by a mixed atmosphere of argon and nitrogen, wherein the nitrogen content is 2-3 ppm and the gas flow rate is 21-26 L / min.

[0020] Furthermore, when using ultra-high-speed laser cladding technology to clad the mixed powder onto the surface of the titanium alloy drill pipe joint substrate, the thickness of the bonding underlayer cladding is 0.3mm to 0.6mm. The ultra-high-speed laser cladding process parameters are: laser power of 2600 to 2700W, spot diameter of 1.2 to 1.4mm, scanning linear speed of 46 to 55m / min, overlap rate of 25 to 30%, and powder feeding rate of 15 to 17g / min.

[0021] The intermediate layer cladding thickness is 0.5mm to 0.8mm. The ultra-high speed laser cladding process parameters are: laser power of 2700 to 2800W, spot diameter of 1.3 to 1.5mm, scanning linear speed of 40 to 48m / min, overlap rate of 30 to 40%, and powder feeding rate of 18 to 20g / min.

[0022] The wear-resistant surface cladding thickness is 0.7mm~1.2mm; the ultra-high speed laser cladding process parameters are: laser power of 2700~2800W, spot diameter of 1.5~2.0mm, scanning linear speed of 35~42m / min, overlap rate of 40~50%, and powder feeding rate of 20~24g / min.

[0023] Furthermore, the partially reduced graphene oxide has 3 to 7 layers, a sheet size of 0.5 μm to 4 μm, a reduction degree of 71% to 80%, and is rich in functional groups such as hydroxyl groups.

[0024] Furthermore, in the TiC powder, the proportion of nano powder is 5wt% to 9wt%, the nano TiC particle size is 80nm to 120nm, the micro TiC particle size is 0.2μm to 0.6μm, and the powder purity is >99.6%.

[0025] Furthermore, the Ti6Al4V titanium alloy powder has a particle size of 60μm to 150μm, a D50 of 80 to 100μm, and a flowability of 35s / 100g ≤ 40s / 100g.

[0026] A gradient wear-resistant band for downhole titanium alloy drill pipe is prepared by the above-mentioned method for preparing gradient wear-resistant bands.

[0027] A downhole titanium alloy drill pipe, comprising the aforementioned gradient wear-resistant band.

[0028] Compared with existing technologies, the present invention has the following beneficial technical effects: The present invention provides a gradient wear-resistant band for downhole titanium alloy drill pipe, the drill pipe itself, and a preparation method thereof. By employing an ultra-high-speed laser cladding method, an in-situ wear-resistant band material layer is generated on the surface of the titanium alloy substrate, achieving a dense metallurgical bond between the titanium alloy substrate and the wear-resistant coating. This improves the wear resistance and service life of the drill pipe, and the wear-resistant band also possesses excellent corrosion resistance. The wear-resistant band of the present invention has strong bonding force, low internal residual stress, excellent resistance to impact load damage, and can effectively inhibit crack initiation in the wear-resistant band.

[0029] Furthermore, this invention features uniform laser energy density, rapid heating, a small heat-affected zone, a substrate melting depth below 70μm, minimal mutual dilution between the base material and the coating, and low residual stress. Compared to welding or conventional laser cladding processes, it is more effective in suppressing crack formation. The thickness of a single cladding layer is controllable within the range of 300–1200μm.

[0030] Furthermore, the wear-resistant tape bonding substrate powder of the present invention is Ti6Al4V powder, which is similar to the main component of titanium alloy drill pipe, making it easy to fuse and with strong bonding force. By adding / in-situ generating nano- and micro-sized ceramic reinforcing particles of different contents in the bonding substrate, intermediate layer, and wear-resistant surface layer, a gradient structure of composition, strength, structure, and hardness is achieved between the titanium alloy drill pipe joint substrate / bonding substrate / intermediate layer / wear-resistant surface layer. While ensuring high bonding force between the wear-resistant tape and the matrix material, the internal residual stress is reduced, effectively inhibiting crack initiation and avoiding large-area peeling of the wear-resistant tape under impact load due to the eggshell effect.

[0031] Furthermore, under the protection of a mixed gas of argon and nitrogen, the present invention uses an ultra-high-speed laser cladding process to prepare a graphene-reinforced titanium / cobalt-based gradient structure wear-resistant strip on a titanium alloy drill pipe joint substrate, which can significantly improve the strength and hardness of the wear-resistant strip and has high bonding strength with the substrate material.

[0032] Furthermore, the present invention uses added nano-TiC particles as heterogeneous nucleation sites, which promote nucleation during laser cladding, refine the grains of the wear-resistant band, and play a role in grain refinement, dispersion reinforcement and toughening.

[0033] Furthermore, the wear-resistant belt features a size gradient of reinforcing phases ranging from a few nanometers and tens of nanometers to micrometers, complementing each other and giving the drill pipe joint wear-resistant belt excellent resistance to impact wear, abrasion, and adhesive wear during service.

[0034] Furthermore, the addition of Co53-Brgo imbues the wear-resistant belt with the self-lubricating properties of graphene, improving its wear resistance. Simultaneously, it retains the excellent strength and toughness of graphene, enabling it to prevent crack initiation, stop cracking, deflect or bridge cracks, and extend the crack propagation path, thereby significantly enhancing the strength, toughness, and wear resistance of the wear-resistant belt. In drilling mud environments, its coefficient of friction is as low as 0.3.

[0035] Furthermore, this invention uses Ti6Al4V powder and Co53 as matrix materials, thus the wear-resistant belt combines the excellent corrosion resistance of titanium alloy and cobalt alloy materials. Test results show that the wear-resistant belt material in this invention has excellent corrosion resistance in high temperature, high pressure, high salt and high acid drilling mud media corrosive environment.

[0036] Furthermore, this invention employs vacuum ball milling during preparation to partially reduce graphene oxide nanosheets and coat the surface of Co53 alloy powder, forming Co53-Brgo. In the subsequent laser cladding process, the partially reduced graphene oxide and adjacent metal atoms share oxygen atoms, thereby enhancing the bonding force within the wear-resistant tape material. This method solves both the problem of graphene dispersion in wear-resistant tape materials and the problem of uneven mixing during ball milling due to graphene's low density. Detailed Implementation

[0037] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention.

[0038] Example 1:

[0039] A method for preparing a gradient wear-resistant band for downhole titanium alloy drill pipe, wherein in this embodiment, the wear-resistant band layer is a three-layer composite structure consisting of a bonding underlayer, an intermediate layer, and a wear-resistant surface layer;

[0040] Specifically, it includes:

[0041] Bonding substrate: Ti6Al4V titanium alloy powder and 20wt% Co53-coated partially reduced graphene oxide (Co53-Brgo) were mixed in a certain proportion and vacuum ball-milled for 5 hours, and then dried for 1 hour.

[0042] Intermediate layer: Ti6Al4V titanium alloy powder, 40wt% Co53-Brgo and 2wt% micro-nano TiC powder are mixed in proportion and vacuum ball-milled for 6 hours, and then dried for 1 hour.

[0043] Wear-resistant layer: 10wt% Ti6Al4V titanium alloy powder, Co53-Brgo and 5wt% micro-nano TiC powder are mixed in proportion and vacuum ball milled for 5 hours, and then dried for 1 hour.

[0044] Taking advantage of the principle that some metallic elements (Ni, Fe, Mo, Co) do not chemically react with nitrogen, a graphene-reinforced titanium-based gradient structure wear-resistant layer is prepared on a titanium alloy drill pipe joint substrate using an ultra-high-speed laser cladding process under the protection of a mixed gas of argon and nitrogen. This process enables the in-situ generation of AlN, VN, TiN, CrN, BN, and Si3N4 nano-reinforcing particles through active reactions of metallic elements Al, V, Ti, Cr, and non-metallic elements B, Si, and N.

[0045] When preparing the bonding underlayer using high-speed laser cladding, an argon atmosphere is used for protection, with a gas flow rate of 21 L / min. When preparing the intermediate layer using high-speed laser cladding, a mixed atmosphere of argon and nitrogen is used for protection, with a nitrogen content of 1 ppm and a gas flow rate of 21 L / min. When preparing the wear-resistant surface layer using high-speed laser cladding, a mixed atmosphere of argon and nitrogen is used for protection, with a nitrogen content of 2 ppm and a gas flow rate of 21 L / min.

[0046] Co53-Brgo is prepared using the following steps:

[0047] The partially reduced graphene oxide has 3 to 7 layers, a sheet size of 0.5 μm to 4 μm, a reduction degree of 71% to 80%, and is rich in functional groups such as hydroxyl groups;

[0048] The pre-prepared Co53 powder has the following composition: 0.07wt% C, 17.5wt% Cr, 3wt% Si, 2wt% Fe, 28wt% Mo, 3wt% Ni, and the remainder Co. The particle size range is 30μm to 60μm; the Rockwell hardness is 50.

[0049] The material was then placed in a vacuum ball mill and milled for 2 hours, followed by drying for 1 hour to prepare Co53-Brgo powder material with a particle size of 20μm to 65μm.

[0050] TiC micro / nano powder preparation:

[0051] The proportion of nanopowder is 9wt%, the nano TiC particle size is 80nm~120nm, the micro TiC particle size is 0.2μm~0.6μm, and the powder purity is >99.6%.

[0052] Ti6Al4V titanium alloy powder:

[0053] The particle size is 60μm~150μm, with 50% and more of the particles having a particle size (D50) of 80~100μm, and the flowability is 35s / 100g≤40s / 100g. Its composition meets the requirements of GB / T3620.1-2016 standard.

[0054] The in-situ generated AlN, VN, TiN, CrN, BN and Si3N4 nano-reinforcing particles have a grain size of 5nm to 40nm;

[0055] The specific steps of the preparation method are as follows:

[0056] The surface of the titanium alloy drill pipe joint substrate is cleaned of oil and ground to a roughness of 10≤Ra≤25μm and an ellipticity of ≤0.3%.

[0057] The mixed powder was clad onto the surface of the titanium alloy drill pipe joint substrate using an ultra-high speed laser cladding process. The bonding layer cladding thickness was 0.3 mm. The ultra-high speed laser cladding process parameters were: laser power 2600W, spot diameter 1.2 mm, scanning linear speed 46 m / min, overlap rate 25%, and powder feeding rate 15 g / min.

[0058] The intermediate layer cladding thickness is 0.5mm. The ultra-high speed laser cladding process parameters are: laser power 2700W, spot diameter 1.3mm, scanning line speed 40m / min, overlap rate 30%, and powder feeding rate 18g / min.

[0059] The wear-resistant surface cladding thickness is 1.2mm; the ultra-high speed laser cladding process parameters are: laser power 2800W, spot diameter 2.0mm, scanning linear speed 42m / min, overlap rate 50%, and powder feeding rate 24g / min.

[0060] The wear-resistant belt's bonding bottom layer, intermediate layer, and surface layer form a multi-dimensional composite gradient structure with compositional gradient, structural gradient, and hardness gradient.

[0061] Specifically, the composition of the bonding bottom layer, intermediate layer and surface layer of the wear-resistant belt is gradient. From the bonding bottom layer to the surface layer, the content of Ti6Al4V titanium alloy decreases layer by layer, while the content of Co53-Brgo wear-resistant cemented carbide, micro-nano TiC reinforcing particles, and in-situ generated AlN, VN, TiN, CrN, BN and Si3N4 nano ceramic reinforcing particles increase layer by layer.

[0062] The wear-resistant tape exhibits a gradient structure across its bonding substrate, intermediate layer, and surface layer, with the thickness increasing progressively from the bonding substrate to the surface layer. Within each intermediate and surface layer, the grain size of the reinforcing particles exhibits a gradient. The in-situ generated AlN, VN, TiN, CrN, BN, and Si3N4 nano-reinforcing particles have grain sizes ranging from 5 nm to 40 nm. The TiC micro / nano powder, after molding, has a grain size of 0.082 μm to 0.65 μm. Co53-Brgo powder material has grain sizes ranging from 21 μm to 100 μm. The wear-resistant tape also exhibits a gradient in hardness across its bonding substrate, intermediate layer, and surface layer. The surface hardness is 63 HRC, with a Vickers hardness of 780 HV. The intermediate layer has a Vickers hardness of 600 HV, and the bonding substrate has a Vickers hardness of 510 HV.

[0063] The surface of the wear-resistant belt was subjected to fluorescent penetrant nondestructive testing according to JB / T 4730.5-2005 standard, and no cracks or defects were found.

[0064] According to the SY / T 6948-2018 standard, the bonding strength test showed no peeling of the wear-resistant tape;

[0065] The simulated drilling density is 2.0 g / cm³. 3 The water-based drilling mud solution has a loading force of 10N, and the friction pair is custom-made. The wear rate of the conglomerate ball in the environment was 0.28 μm / h, and the friction coefficient was 0.38.

[0066] At a density of 1.8 g / cm³ 3 The oil-based drilling mud solution has a loading force of 10N, and the friction pair is custom-made. The wear rate of the conglomerate ball in the environment is 0.20 μm / h, and the friction coefficient is 0.3; under the impact load of 18J falling ball, the wear-resistant belt does not crack or peel off on site.

[0067] High temperature, high pressure, high salt, and high acidity:

[0068] At 160℃ and 35MPa, the density is 2.0 g / cm³. 3 The corrosion rate of the water-based drilling mud solution in a corrosive environment with a hydrogen sulfide partial pressure of 0.1 MPa and a carbon dioxide partial pressure of 1 MPa is 0.017 mm / a.

[0069] At 200℃ and 35MPa, the density is 2.0 g / cm³. 3 The corrosion rate of the water-based drilling mud solution in a corrosive environment with a hydrogen sulfide partial pressure of 0.1 MPa and a carbon dioxide partial pressure of 1 MPa is 0.020 mm / a.

[0070] In embodiments of the present invention, taking advantage of the principle that some metallic elements (Ni, Fe, Mo, Co) do not chemically react with nitrogen, a graphene-reinforced titanium / cobalt-based gradient structure wear-resistant band is prepared on a titanium alloy drill pipe joint substrate using an ultra-high-speed laser cladding process under the protection of a mixed gas of argon and nitrogen. This process enables the in-situ generation of AlN, VN, TiN, CrN, BN, and Si3N4 nano-ceramic reinforcing particles through active reactions of metallic elements Al, V, Ti, Cr, and non-metallic elements B, Si, and N. This significantly improves the strength and hardness of the wear-resistant band and provides high bonding strength with the substrate material.

[0071] Meanwhile, the in-situ generated AlN, VN, TiN, CrN, BN and Si3N4 nano-ceramic reinforcing particles and the added nano-TiC particles serve as heterogeneous nucleation sites, which promote nucleation during laser cladding, refine the grains of the wear-resistant band, and play a role in fine grain strengthening, dispersion strengthening and toughening.

[0072] Furthermore, through the reinforcement of the wear-resistant belt with particle sizes ranging from a few nanometers (AlN, VN, TiN, CrN, BN and Si3N4), tens of nanometers (AlN, VN, TiN, CrN, BN and Si3N4, TiC) to micrometers (TiC, Co53-Brgo), the advantages are complemented, giving the wear-resistant belt of the drill pipe joint good resistance to impact wear, abrasion and adhesive wear during service.

[0073] Example 2:

[0074] The wear-resistant belt is a three-layer composite structure consisting of an adhesive bottom layer, an intermediate layer, and a wear-resistant surface layer.

[0075] Specifically, it includes:

[0076] The bonding substrate is made of Ti6Al4V titanium alloy powder and 30wt% Co53-coated partially reduced graphene oxide (Co53-Brgo), which are mixed in a certain proportion and vacuum ball-milled for 6 hours, and then dried for 2 hours.

[0077] The intermediate layer is made of Ti6Al4V titanium alloy powder, 50wt% Co53-Brgo and 2wt% micro-nano TiC powder mixed in proportion and vacuum ball milled for 7 hours, and then dried for 2 hours.

[0078] The wear-resistant surface layer is made by mixing 10wt% Ti6Al4V titanium alloy powder, Co53-Brgo and 3wt% micro-nano TiC powder in a certain proportion and then vacuum ball milling for 5 hours and drying for 1 hour.

[0079] Taking advantage of the principle that some metallic elements (Ni, Fe, Mo, Co) do not chemically react with nitrogen, graphene-reinforced titanium-based gradient structure wear-resistant bands are prepared on titanium alloy drill pipe joint substrates using ultra-high-speed laser cladding technology under the protection of a mixed gas of argon and nitrogen. This process enables the in-situ generation of AlN, VN, TiN, CrN, BN, and Si3N4 nano-reinforcing particles through active reactions of metallic elements Al, V, Ti, Cr, and non-metallic elements B, Si, and N.

[0080] When preparing the bonding underlayer using high-speed laser cladding, an argon atmosphere is used for protection, with a gas flow rate of 26 L / min. When preparing the intermediate layer using high-speed laser cladding, a mixed atmosphere of argon and nitrogen is used for protection, with a nitrogen content of 2 ppm and a gas flow rate of 26 L / min. When preparing the wear-resistant surface layer using high-speed laser cladding, a mixed atmosphere of argon and nitrogen is used for protection, with a nitrogen content of 3 ppm and a gas flow rate of 26 L / min.

[0081] The characteristics of Co53-Brgo are as follows:

[0082] (1) The partially reduced graphene oxide has 3 to 7 layers, a sheet size of 0.5 μm to 4 μm, a reduction degree of 71% to 80%, and is rich in functional groups such as hydroxyl groups;

[0083] (2) The pre-made Co53 powder has the following composition: 0.07wt% C, 17.5wt% Cr, 3wt% Si, 2wt% Fe, 28wt% Mo, 3wt% Ni, and the remainder Co. The particle size range is 30μm to 60μm; the Rockwell hardness range is 50 to 54.

[0084] (3) Then put it into a vacuum ball mill for 3 hours and dry it for 2 hours to prepare Co53-Brgo powder material with a particle size of 20μm~65μm.

[0085] TiC micro / nano powder:

[0086] The proportion of TiC micro / nano powder is 5 wt%, the nano TiC particle size is 80 nm to 120 nm, the micro TiC particle size is 0.2 μm to 0.6 μm, and the powder purity is >99.6%.

[0087] The Ti6Al4V titanium alloy powder has a particle size of 60μm to 150μm, with 50% or more of the particles having a particle size (D50) of 80 to 100μm. Its flowability is 35s / 100g ≤ 40s / 100g, and its composition meets the requirements of GB / T3620.1-2016 standard. The generated AlN, VN, TiN, CrN, BN, and Si3N4 nano-reinforcing particles have a grain size of 5nm to 40nm.

[0088] In the specific preparation process:

[0089] First, the surface of the titanium alloy drill pipe joint substrate is cleaned of oil and ground to a roughness of 10≤Ra≤25μm and an ellipticity of 0.5%.

[0090] The mixed powder was clad onto the surface of the titanium alloy drill pipe joint substrate using an ultra-high-speed laser cladding process. The bonding layer cladding thickness was 0.6 mm. The ultra-high-speed laser cladding process parameters were: laser power 2700W, spot diameter 1.4 mm, scanning linear speed 55 m / min, overlap rate 30%, and powder feeding rate 17 g / min.

[0091] The intermediate layer cladding thickness is 0.8mm. The ultra-high speed laser cladding process parameters are: laser power 2800W, spot diameter 1.5mm, scanning line speed 48m / min, overlap rate 40%, and powder feeding rate 20g / min.

[0092] The wear-resistant surface cladding thickness is 0.7mm; the ultra-high speed laser cladding process parameters are: laser power 2700, spot diameter 1.5mm, scanning linear speed 35m / min, overlap rate 40%, and powder feeding rate 20g / min.

[0093] The wear-resistant belt's structure and performance indicators meet the following requirements: the bonding bottom layer, intermediate layer, and surface layer of the wear-resistant belt form a multi-dimensional composite gradient structure with compositional gradient, structural gradient, and hardness gradient. The composition of the bonding bottom layer, intermediate layer, and surface layer of the wear-resistant belt exhibits a gradient, with the content of Ti6Al4V titanium alloy decreasing layer by layer from the bonding bottom layer to the surface layer, while the content of Co53-Brgo wear-resistant cemented carbide, micro / nano TiC reinforcing particles, and AlN, VN, TiN, CrN, BN, and Si3N4 nano-ceramic reinforcing particles increasing layer by layer. The structure of the bonding bottom layer, intermediate layer, and surface layer of the wear-resistant belt exhibits a gradient, with the thickness increasing layer by layer from the bonding bottom layer to the surface layer. Between the intermediate layer and the surface layer, the grain size of the reinforcing particles within each layer exhibits a gradient, and they are generated in situ. The wear-resistant belt contains AlN, VN, TiN, CrN, BN, and Si3N4 nano-reinforcing particles with grain sizes ranging from 5 nm to 40 nm; TiC micro-nano powder with grain sizes ranging from 0.082 μm to 0.65 μm after molding; and Co53-Brgo powder with grain sizes ranging from 21 μm to 100 μm. The wear-resistant belt exhibits a gradient in hardness between the bonding underlayer, intermediate layer, and surface layer, with the surface hardness at 59 HRC and a Vickers hardness at 680 HV; the intermediate layer at 650 HV; and the bonding underlayer at 450 HV.

[0094] The surface of the wear-resistant belt was subjected to fluorescent penetrant nondestructive testing according to JB / T 4730.5-2005 standard, and no cracks or defects were found; the bonding strength test was conducted according to SY / T 6948-2018 standard, and the wear-resistant belt did not peel off.

[0095] (1) During simulated drilling:

[0096] The density is 2.0 g / cm³. 3 The water-based drilling mud solution has a loading force of 10N, and the friction pair is custom-made. The wear rate of the conglomerate ball in the environment was 0.26 μm / h, and the friction coefficient was 0.30.

[0097] The density is 1.8 g / cm³. 3 The oil-based drilling mud solution has a loading force of 10N, and the friction pair is custom-made. The wear rate of the conglomerate ball in the environment was 0.18 μm / h, and the friction coefficient was 0.25.

[0098] (2) Under the action of a 19J falling ball impact load, the wear-resistant belt does not crack or peel off on site.

[0099] (3) High temperature, high pressure, high salt and high acidity:

[0100] At 160℃ and 35MPa, the density is 2.0 g / cm³. 3 The corrosion rate of the water-based drilling mud solution in a corrosive environment with a hydrogen sulfide partial pressure of 0.1 MPa and a carbon dioxide partial pressure of 1 MPa is 0.018 mm / a.

[0101] At 200℃ and 35MPa, the density is 2.0 g / cm³. 3 The corrosion rate of the water-based drilling mud solution in a corrosive environment with a hydrogen sulfide partial pressure of 0.1 MPa and a carbon dioxide partial pressure of 1 MPa is 0.021 mm / a.

[0102] Example 3:

[0103] A drill pipe includes a wear-resistant layer, the wear-resistant layer being a three-layer composite structure consisting of a bonding underlayer, an intermediate layer, and a wear-resistant surface layer; specifically, the bonding underlayer is made of Ti6Al4V titanium alloy powder and 25wt% Co53-coated partially reduced graphene oxide (Co53-Brgo) mixed in a certain proportion and vacuum ball-milled for 5.5 hours, then dried for 1.5 hours. The intermediate layer is made of Ti6Al4V titanium alloy powder, 45wt% Co53-Brgo, and 1.5wt% micro / nano TiC powder mixed in a certain proportion and vacuum ball-milled for 6.5 hours, then dried for 1.5 hours. The wear-resistant surface layer is made of 15wt% Ti6Al4V titanium alloy powder, Co53-Brgo, and 4wt% micro / nano TiC powder mixed in a certain proportion and vacuum ball-milled for 5.5 hours, then dried for 1.5 hours. Utilizing the principle that some metallic elements (Ni, Fe, Mo, Co) do not chemically react with nitrogen, a graphene-reinforced titanium-based gradient structure wear-resistant band is prepared on a titanium alloy drill pipe joint substrate using an ultra-high-speed laser cladding process under the protection of a mixed argon and nitrogen gas. This process achieves in-situ generation of AlN, VN, TiN, CrN, BN, and Si3N4 nano-reinforcing particles through active reactions of metallic elements Al, V, Ti, Cr, and non-metallic elements B, Si, and N. When preparing the bonding underlayer using the high-speed laser cladding process, an argon atmosphere is used with a gas flow rate of 24 L / min. When preparing the intermediate layer using the high-speed laser cladding process, a mixed argon and nitrogen atmosphere is used with a nitrogen content of 1.5 ppm and a gas flow rate of 25 L / min. When preparing the wear-resistant surface layer using the high-speed laser cladding process, a mixed argon and nitrogen atmosphere is used with a nitrogen content of 2.5 ppm and a gas flow rate of 24 L / min.

[0104] The Co53-Brgo was prepared as follows: (1) The number of partially reduced graphene oxide layers was 3 to 7, the sheet size was 0.5 μm to 4 μm, the reduction degree was 71% to 80%, and it was rich in functional groups such as hydroxyl groups; (2) The pre-prepared Co53 powder composition was 0.07 wt% C, 17.5 wt% Cr, 3 wt% Si, 2 wt% Fe, 28 wt% Mo, 3 wt% Ni, and the remainder Co, with a particle size range of 30 μm to 60 μm and a Rockwell hardness range of 50 to 54; (3) It was then placed in a vacuum ball mill for ball milling for 2.5 hours and dried for 1.5 hours to prepare Co53-Brgo powder material with a particle size of 20 μm to 65 μm.

[0105] The TiC micro / nano powder contains 7 wt% nano powder, with nano TiC particles ranging from 80 nm to 120 nm in size and micro TiC particles ranging from 0.2 μm to 0.6 μm in size, and the powder purity is >99.6%.

[0106] Ti6Al4V titanium alloy powder has a particle size of 60μm to 150μm, with 50% and more of the particles having a particle size (D50) of 80 to 100μm, and a flowability of 35s / 100g ≤ 40s / 100g. Its composition meets the requirements of GB / T3620.1-2016 standard.

[0107] The in-situ generated AlN, VN, TiN, CrN, BN and Si3N4 nano-reinforcing particles have a grain size of 5nm to 40nm;

[0108] The preparation method is completed through the following steps:

[0109] Step 1: Remove oil stains from the surface of the titanium alloy drill pipe joint substrate and grind it to a roughness of 10≤Ra≤25μm and an ellipticity of ≤0.3%.

[0110] Step 2: The mixed powder is clad onto the surface of the titanium alloy drill pipe joint substrate using an ultra-high speed laser cladding process. The thickness of the bonding layer is 0.5 mm. The ultra-high speed laser cladding process parameters are: laser power 2650W, spot diameter 1.3 mm, scanning line speed 50 m / min, overlap rate 28%, and powder feeding rate 16 g / min.

[0111] Step 3: The intermediate layer cladding thickness is 0.7mm. The ultra-high speed laser cladding process parameters are: laser power 2750W, spot diameter 1.4mm, scanning line speed 45m / min, overlap rate 35%, and powder feeding rate 19g / min.

[0112] Step 4: The wear-resistant surface cladding thickness is 0.9mm; the ultra-high speed laser cladding process parameters are: laser power 2750W, spot diameter 1.8mm, scanning line speed 37m / min, overlap rate 45%, and powder feeding rate 22g / min.

[0113] The wear-resistant belt prepared under the above conditions meets the following requirements in terms of structure and performance indicators:

[0114] (1) The wear-resistant belt's bonding substrate, intermediate layer, and surface layer form a multi-dimensional composite gradient structure with compositional gradient, structural gradient, and hardness gradient. Specifically, ① the composition of the wear-resistant belt's bonding substrate, intermediate layer, and surface layer is gradient. From the bonding substrate to the surface layer, the content of Ti6Al4V titanium alloy decreases layer by layer, while the content of Co53-Brgo wear-resistant cemented carbide, micro-nano TiC reinforcing particles, and AlN, VN, TiN, CrN, BN, and Si3N4 nano-ceramic reinforcing particles increase layer by layer; ② the structure of the wear-resistant belt's bonding substrate, intermediate layer, and surface layer is gradient. From the bonding substrate to the surface layer, the thickness increases layer by layer; between the intermediate layer and the surface layer, the grain size of the reinforcing particles within each layer is gradient, and in situ... The generated AlN, VN, TiN, CrN, BN, and Si3N4 nano-reinforcing particles have grain sizes ranging from 5 nm to 40 nm; the TiC micro / nano powder has grain sizes ranging from 0.082 μm to 0.65 μm after forming; and the Co53-Brgo powder material has grain sizes ranging from 21 μm to 100 μm. ③ The hardness of the bonding underlayer, intermediate layer, and surface layer of the wear-resistant belt exhibits a gradient, with the surface hardness at 56 HRC and a Vickers hardness at 610 HV; the intermediate layer has a Vickers hardness of 500 HV; and the bonding underlayer has a Vickers hardness of 330 HV.

[0115] (2) The surface of the wear-resistant belt was subjected to fluorescent penetrant nondestructive testing according to JB / T 4730.5-2005 standard, and no cracks or defects were found;

[0116] (3) The bonding strength test was conducted according to the SY / T6948-2018 standard, and the wear-resistant belt did not peel off;

[0117] (4) In simulated drilling, the density is 2.0 g / cm³. 3 The water-based drilling mud solution has a loading force of 10N, and the friction pair is custom-made. The wear rate of the conglomerate spheres was 0.25 μm / h, and the friction coefficient was 0.27; at a density of 1.8 g / cm³, the wear rate was 0.25 μm / h. 3 The oil-based drilling mud solution has a loading force of 10N, and the friction pair is custom-made. The wear rate of the conglomerate ball in the environment was 0.17 μm / h, and the friction coefficient was 0.2.

[0118] (5) Under the action of a falling ball impact load of 18J, the wear-resistant belt does not crack or peel off on site;

[0119] (6) High temperature, high pressure, high salt, and high acidity:

[0120] At 160℃ and 35MPa, the density is 2.0 g / cm³. 3 The corrosion rate of the water-based drilling mud solution in a corrosive environment with a hydrogen sulfide partial pressure of 0.1 MPa and a carbon dioxide partial pressure of 1 MPa is 0.015 mm / a.

[0121] At 200℃ and 35MPa, the density is 2.0 g / cm³. 3 The corrosion rate of the water-based drilling mud solution in a corrosive environment with a hydrogen sulfide partial pressure of 0.1 MPa and a carbon dioxide partial pressure of 1 MPa is 0.019 mm / a.

[0122] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0123] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a gradient wear-resistant band in a downhole titanium alloy drill pipe, characterized in that, The preparation method includes the following steps: S1: Surface treatment of the joint substrate of titanium alloy drill pipe; S2: A wear-resistant band is prepared on the outer layer of the joint of the titanium alloy drill pipe. The wear-resistant band structure consists of an adhesive underlayer, an intermediate layer and a wear-resistant layer from the inside out. Under gas protection, the bonding underlayer, intermediate layer and wear-resistant layer of the wear-resistant band are sequentially prepared on the joint substrate of the titanium alloy drill pipe. The wear-resistant belt raw materials include TiC powder, Ti6Al4V titanium alloy powder and Co53-Brgo formed by partially reduced graphene oxide coated with Co53. The graphene-reinforced titanium-based gradient structure wear-resistant belt is prepared on the titanium alloy drill pipe joint substrate by using an ultra-high speed laser cladding process. The raw materials for preparing the bonding underlayer include Ti6Al4V titanium alloy powder and 20wt% to 30wt% Co53-Brgo; The raw materials for preparing the intermediate layer include Ti6Al4V titanium alloy powder, 40wt% to 50wt% Co53-Brgo, and 1wt% to 2wt% TiC powder; The raw materials for preparing the wear-resistant layer include 10wt% to 20wt% of Ti6Al4V titanium alloy powder, Co53-Brgo, and 3wt% to 5wt% of TiC powder; The Co53-Brgo is a composite material formed by coating Co53 alloy powder with partially reduced graphene oxide; When using ultra-high-speed laser cladding to clad the mixed powder onto the surface of the titanium alloy drill pipe joint substrate, the thickness of the bonding underlayer is 0.3mm to 0.6mm. The ultra-high-speed laser cladding process parameters are: laser power of 2600 to 2700W, spot diameter of 1.2 to 1.4mm, scanning linear speed of 46 to 55m / min, overlap rate of 25 to 30%, and powder feeding rate of 15 to 17g / min. When preparing the bonding underlayer using ultra-high-speed laser cladding, the atmosphere is protected by argon gas with a gas flow rate of 21 to 26L / min. When preparing the intermediate layer and wear-resistant layer using ultra-high-speed laser cladding technology, a mixed atmosphere of argon and nitrogen is used for protection. The intermediate layer cladding thickness is 0.5mm to 0.8mm. The ultra-high-speed laser cladding process parameters are: laser power of 2700 to 2800W, spot diameter of 1.3 to 1.5mm, scanning linear speed of 40 to 48m / min, overlap rate of 30 to 40%, and powder feeding rate of 18 to 20g / min. When preparing the intermediate layer using the ultra-high-speed laser cladding process, it is protected by a mixed atmosphere of argon and nitrogen, wherein the nitrogen content is 1 to 2ppm and the gas flow rate is 21 to 26L / min. The wear-resistant layer cladding thickness is 0.7mm~1.2mm; the ultra-high speed laser cladding process parameters are: laser power of 2700~2800W, spot diameter of 1.5~2.0mm, scanning linear speed of 35~42m / min, overlap rate of 40~50%, and powder feeding rate of 20~24g / min; when preparing the wear-resistant layer using the ultra-high speed laser cladding process: it is protected by a mixed atmosphere of argon and nitrogen, wherein the nitrogen content is 2~3ppm and the gas flow rate is 21~26L / min.

2. The method for preparing a gradient wear-resistant band for a downhole titanium alloy drill pipe according to claim 1, characterized in that, The surface treatment includes removing oil stains from the surface and grinding to a roughness of 10≤Ra≤25μm and an ellipticity of ≤0.5%.

3. The method for preparing a gradient wear-resistant band for a downhole titanium alloy drill pipe according to claim 1, characterized in that, When preparing the bonding underlayer, the titanium alloy powder and the Co53-Brgo are mixed and vacuum ball-milled for 5-6 hours, and then dried for 1-2 hours; When preparing the intermediate layer, the titanium alloy powder, the Co53-Brgo, and the TiC powder are mixed and then vacuum ball-milled for 6-7 hours, and then dried for 1-2 hours. When preparing the wear-resistant layer, the Ti6Al4V titanium alloy powder, the Co53-Brgo, and the TiC powder are mixed and vacuum ball-milled for 5 to 6 hours, and then dried for 1 to 2 hours.

4. The method for preparing a gradient wear-resistant band for a downhole titanium alloy drill pipe according to claim 1, characterized in that, The partially reduced graphene oxide has 3 to 7 layers, a sheet size of 0.5 μm to 4 μm, a reduction degree of 71% to 80%, and is rich in hydroxyl functional groups.

5. The method for preparing a gradient wear-resistant band for a downhole titanium alloy drill pipe according to claim 3, characterized in that, The TiC powder contains 5wt% to 9wt% nanoparticles, with nano-TiC particles ranging from 80nm to 120nm in size and micro-TiC particles ranging from 0.2μm to 0.6μm in size, and the powder purity is >99.6%.

6. The method for preparing a gradient wear-resistant band for a downhole titanium alloy drill pipe according to claim 3, characterized in that, The Ti6Al4V titanium alloy powder has a particle size of 60μm to 150μm, a D50 of 80 to 100μm, and a flowability of 35s / 100g ≤ 40s / 100g.

7. A gradient wear-resistant band for downhole titanium alloy drill pipe, characterized in that, It is prepared by the method of any one of claims 1 to 6.

8. A downhole titanium alloy drill pipe, characterized in that, Includes the gradient wear-resistant belt as described in claim 7.