Wear-resistant surfacing flux-cored wire suitable for rotary excavating teeth and preparation method and welding method of wear-resistant surfacing flux-cored wire

Abstract

The invention discloses a wear-resistant surfacing flux-cored wire suitable for rotary excavating teeth and a preparation method and a welding method of the wear-resistant surfacing flux-cored wire. The flux-cored wire comprises an outer skin and a flux core, and the flux core is composed of, by mass, 0.1%-0.3% of C, 15%-20% of CrN, 5%-10% of Ti, 0.8%-1.5% of Mn, 0.6%-1.2% of Si, 5%-10% of V, 0.9%-1.3% of Mo, 3%-10% of Nb, 0.2%-0.5% of Al and the balance Fe. According to the MAG surfacing technology for the rotary excavating tooth through the flux-cored wire, the service life of the MAG surfacing technology is prolonged to 1.5-1.8 times of that of a traditional product in granite stratum continuous operation, the single-time construction maintenance cost of single equipment is reduced by 25%-30%, the comprehensive drilling efficiency is improved by 20%, and the MAG surfacing technology is high in stability and suitable for batch production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of welding materials, and relates to a wear-resistant surfacing flux-cored wire suitable for a rotary digging tooth. BACKGROUND

[0002] In the field of modern industrial manufacturing, the rotary digging tooth, as a core component of a geological drilling device, directly determines the efficiency and reliability of rock and soil drilling operations. In the prior art, the tooth body base material of the rotary digging tooth is usually made of alloy materials such as 42CrMo and 35CrMnSi. Although such materials have certain strength at room temperature, they will exhibit significant performance degradation at high temperature (such as when the tooth body temperature rises sharply due to continuous operation), with a hardness drop of 30% to 50% and a toughness reduction of 40% to 60%, thereby causing rapid wear and fracture. In addition, the traditional surfacing process usually directly clads the wear-resistant layer on the conical surface of the tooth body. This full-coverage cladding method introduces residual thermal stress as high as 300 MPa to 500 MPa, resulting in insufficient interfacial bonding strength between the surfacing layer and the base material, and the surfacing layer is prone to cracking and peeling under impact load.

[0003] The above defects result in an average service life of the rotary digging tooth of only 50 to 80 hours, with a replacement frequency of once every 2 meters of drilling, which requires downtime for maintenance, thereby causing downtime accounting for 25% to 35% of the total construction cycle, seriously affecting the project progress and increasing the maintenance cost. Although the prior art attempts to improve wear resistance by embedding hard alloy (such as YG15C material), such a solution has limitations such as high processing difficulty, high cost, and insufficient impact resistance. At the same time, the control of carbides in traditional surfacing materials is difficult, and coarse eutectic carbides (such as M7C3) are easily formed, resulting in increased brittleness of the surfacing layer and a high crack occurrence rate under complex working conditions.

[0004] In addition, in existing surfacing materials, excessive carbon content leads to a sharp increase in eutectic carbide precipitation, and the beneficial effects of nitrogen are not fully utilized. Research shows that nitrogen can refine the size of eutectic carbides, reduce their growth space and time, and reduce the connection between carbides, while promoting the fragmentation and dissolution of carbides during hot working, thereby improving the strength and toughness matching of the material. Therefore, developing a wear-resistant surfacing flux-cored wire by optimizing alloy composition (such as introducing nitrogen, tungsten, and other elements to control the morphology and distribution of carbides) and improving the cladding process has important practical significance for improving the service life of the rotary digging tooth and avoiding peeling failure of the surfacing layer due to cracking. SUMMARY

[0005] The first objective of this invention is to provide a wear-resistant flux-cored wire suitable for rotary drilling teeth, which solves the problems of insufficient wear resistance, low bonding strength between the weld overlay and the substrate, and easy detachment due to thermal stress cracking in the existing rotary drilling teeth welding materials.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned wear-resistant flux-cored wire suitable for rotary drilling teeth.

[0007] A third objective of this invention is to provide the above-described welding method for wear-resistant flux-cored wires used in rotary drilling teeth.

[0008] The first technical solution adopted in this invention is a wear-resistant surfacing flux-cored wire suitable for rotary drilling teeth, comprising an outer sheath and a flux core, wherein the flux core is composed of the following components by mass percentage: The powder composition is as follows: C powder 0.1%~0.3%, CrN powder 15%~20%, Ti powder 5%~10%, Mn powder 0.8%~1.5%, Si powder 0.6%~1.2%, V powder 5%~10%, Mo powder 0.9%~1.3%, Nb powder 3%~10%, Al powder 0.2%~0.5%, with the balance being Fe; the powder particle size is not greater than 200μm.

[0009] The first technical solution of this invention is also characterized by: The core consists of the following components by mass percentage: C powder 0.1%~0.3%, CrN powder 17%~20%, Ti powder 7%~10%, Mn powder 0.8%~1.5%, Si powder 0.6%~1.2%, V powder 7%~10%, Mo powder 0.9%~1.3%, Nb powder 5%~10%, Al powder 0.2%~0.5%, with the balance being Fe.

[0010] The outer sheath is made of H08A low carbon steel strip, with a thickness of 0.4mm~0.55mm and a width of 7mm~11mm.

[0011] The filling rate of the outer layer of Chinese herbal medicine core is 23%~27%.

[0012] The second technical solution adopted in this invention is a method for preparing wear-resistant flux-cored wire for rotary drilling teeth, which is implemented according to the following steps: Step 1: Weigh the raw material powders according to their mass percentages; Step 2: Mix the raw material powders evenly; Step 3: Clean the outer skin and roll it into a U-shape; Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth.

[0013] The second technical solution of the present invention is further characterized by: The mass percentages of each component in the raw material powder in step 1 are as follows: C powder 0.1%~0.3%, CrN powder 15%~20%, Ti powder 5%~10%, Mn powder 0.8%~1.5%, Si powder 0.6%~1.2%, V powder 5%~10%, Mo powder 0.9%~1.3%, Nb powder 3%~10%, Al powder 0.2%~0.5%, with the balance being Fe; the particle size of the raw material powder is no greater than 200μm.

[0014] The specific steps of step 2 are as follows: Place the powder in a heating furnace and keep it at 110℃~150℃ for 2h~4h to remove moisture. Then put it into a powder mixer and mix for 1h~3h to obtain uniform core powder.

[0015] In step 3, the outer skin is H08A low carbon steel strip, with a thickness of 0.4mm~0.55mm and a width of 7mm~11mm; The cleaning method is as follows: Wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains; place the cleaned H08A low carbon steel strip into a tube furnace and keep it at 150℃~230℃ for 1h~2h to ensure the surface of the steel strip is clean.

[0016] In step 4, the fill rate is 23%~27%; The specific steps of drawing are as follows: after the U-shaped outer skin is closed, it is drawn through the drawing die to reduce the diameter step by step, and the final diameter is controlled to be 1.2mm~1.6mm; after the drawing is completed, the wire is placed in a tube furnace and kept at 150℃~230℃ for 1h~2h. After cooling, the surface is wiped with anhydrous ethanol.

[0017] The third technical solution adopted in this invention is a welding method for wear-resistant surfacing flux-cored wire suitable for rotary drilling teeth. The rotary drilling teeth are surfacing using the above-mentioned wear-resistant surfacing flux-cored wire suitable for rotary drilling teeth. The welding process is as follows: MAG welding is used, the welding current is 140A~180A, the welding voltage is 19V~23V, the welding speed is 0.21m / min~0.25m / min, and the shielding gas is a mixture of Ar and CO2, wherein Ar is 80 vol% and CO2 is 20 vol%.

[0018] The beneficial effects of this invention are: This invention relates to wear-resistant surfacing flux-cored wire for rotary drilling rigs. Through a precise Al / Si ratio, it achieves efficient deoxidation, exhibits high process stability when used with conventional MAG welding equipment, and is suitable for mass production. Rotary drilling rigs using the wire of this invention for surfacing have a service life 1.5 to 1.8 times longer than traditional products in continuous operations in granite formations, reduce single-unit maintenance costs by 25% to 30%, and increase overall drilling efficiency by 20%. Attached Figure Description

[0019] Figure 1This is a metallographic microstructure of the wear-resistant weld overlay layer prepared under the process conditions of Example 5 in this invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] This invention applies to wear-resistant weld overlay flux-cored wire for rotary drilling teeth, comprising an outer sheath and a flux core, wherein the flux core is composed of the following components by weight percentage: The powder consists of 0.1%~0.3% C powder, 15%~20% CrN powder, 5%~10% Ti powder, 0.8%~1.5% Mn powder, 0.6%~1.2% Si powder, 5%~10% V powder, 0.9%~1.3% Mo powder, 3%~10% Nb powder, and 0.2%~0.5% Al powder, with the balance being Fe; the particle size of the powder in the core is no greater than 200μm.

[0022] The outer sheath is made of H08A low carbon steel strip, with a thickness of 0.4mm~0.55mm and a width of 7mm~11mm.

[0023] The filling rate of the outer layer of Chinese herbal medicine core is 23%~27%.

[0024] In the optimized formulation, the core consists of the following components by mass percentage: The composition is as follows: C powder 0.1%~0.3%, CrN powder 17%~20%, Ti powder 7%~10%, Mn powder 0.8%~1.5%, Si powder 0.6%~1.2%, V powder 7%~10%, Mo powder 0.9%~1.3%, Nb powder 5%~10%, Al powder 0.2%~0.5%, with the balance being Fe.

[0025] This invention is applicable to wear-resistant weld overlay flux-cored wire for rotary drilling teeth. Based on the synergistic effect of various alloying elements in the microstructure and performance control of the weld overlay, a balance between wear resistance, crack resistance, and mechanical properties is achieved through precise proportioning. The specific effects are as follows: Carbon (C) is the core element controlling the microstructure of the weld overlay. Its synergistic effect with elements such as Cr, Ti, V, and Nb determines the type and distribution of hard phases. C can combine with Cr dissociated from CrN to form high-hardness M7C3 type carbides, and react with Ti, V, and Nb to generate ultra-hard phases such as TiC, VC, and NbC (microhardness exceeding 2000 HV). These carbides constitute a wear-resistant skeleton, significantly improving the ability to resist abrasive wear. At the same time, reasonable control of C (0.1%~0.3%) can avoid brittleness caused by excessive carbide aggregation, ensuring a balance between strength and toughness in the weld overlay.

[0026] CrN, as a composite reinforcing phase, possesses the dual functions of Cr and N. Cr can form a dense Cr2O3 oxide film on the surface of the weld overlay, blocking hydrogen permeation to reduce the risk of hydrogen-induced cracking and improving corrosion resistance under humid conditions. N combines with Ti to form TiN, or synergistically with Cr to form the CrN hard phase. These nitrides not only have high hardness (CrN hardness is approximately 1800 HV) but also excellent thermal stability, making them resistant to decomposition under high-temperature drilling conditions. An addition of 15%~20% CrN ensures the formation of a sufficient amount of nitride-carbide composite reinforcing phase, while simultaneously enhancing the matrix strength through solid solution strengthening.

[0027] Ti optimizes microstructure and properties through multiple mechanisms. As a highly reactive element, Ti preferentially reacts with oxygen and sulfur to form stable compounds, purifying the molten pool and reducing harmful impurities. It combines with C and N to form TiC and TiN, with TiC and TiN forming a synergistic "dual hard phase" structure that is uniformly distributed in the matrix to resist abrasive cutting. At the same time, Ti can refine primary carbide grains, avoiding brittleness caused by coarse phases. An addition of 5% to 10% can achieve a balance between strengthening and toughness.

[0028] The core function of vanadium (V) is to form an ultra-high hardness VC phase (microhardness 2300-2800 HV), whose hardness is far higher than that of traditional M7C3 carbides. As the V content increases (5%~10%), the volume fraction of VC increases, significantly improving wear resistance. In addition, V can refine austenite grains, allowing VC to be evenly distributed in the eutectic structure. Its weakening effect on the toughness of the matrix is ​​significantly less than that of coarse carbides, achieving a balance between high wear resistance and high toughness.

[0029] As a strong carbide-forming element, Nb mainly forms highly stable NbC (melting point up to 3480℃), which is not prone to coarsening at high temperatures, effectively hindering grain growth and improving the thermal stability of the weld overlay. Adding 0.5%~10% Nb can form multi-component composite carbides with VC and TiC, further optimizing the uniformity of the hard phase distribution and enhancing the weld overlay's resistance to plastic deformation.

[0030] As a powerful deoxidizer, Al can preferentially react with free oxygen in the molten pool to generate Al2O3, reducing porosity and oxide inclusions. At the same time, Al can refine ferrite grains and promote grain boundary strengthening. An addition of 0.2% to 0.5% can purify the molten pool while improving the oxidation resistance and impact toughness of the weld overlay.

[0031] The role of Mn is focused on optimizing the mechanical properties of welds: 0.8%~1.5% Mn enhances the strength and hardness of the matrix through solid solution strengthening, while inhibiting the precipitation of brittle phases and ensuring the balance of strength and toughness of the weld overlay; as a weak deoxidizing element, Mn can help remove trace amounts of oxygen, reduce welding defects, and improve joint density.

[0032] Si mainly plays a role in metallurgical purification and microstructure regulation: as a powerful deoxidizer, it reacts with FeO to generate silicate slag, avoiding the formation of brittle oxides; at the same time, it promotes the transformation of columnar crystals to equiaxed crystals, improves the uniformity of the weld overlay microstructure, and an addition of 0.6%~1.2% can effectively reduce inclusions and porosity defects.

[0033] Mo enhances performance through a dual mechanism: on the one hand, it promotes the formation of a composite oxide film containing MoO3 on the surface, which synergistically enhances corrosion resistance and oxidation resistance with Cr2O3; on the other hand, it refines grains through solid solution strengthening, improves matrix hardness and high-temperature stability, and forms a complementary strengthening effect with Cr and V. An addition of 0.9% to 1.3% can significantly improve the comprehensive mechanical properties of the weld overlay.

[0034] This invention is applicable to the composition of wear-resistant weld overlay flux wire for rotary drilling teeth, in which CrN (15%~20%) serves as the core nitride hard phase, synergistically forming TiN with Ti (5%~10%) and VN with V (5%~10%), and combined with Nb (0.5%~10%) to form the NbN / NbC hard phase, constructing a multi-component nitride-carbide reinforced system; low C (0.1%~0.3%) can inhibit the agglomeration of coarse carbides, and Mo (0.9%~1.3%) further refines the microstructure, making the hardness of the weld overlay layer stable at 60HRC~63HRC. In the quartz sand abrasive wear test, the wear resistance is improved by more than 35% compared with the traditional Cr~Mo system, especially suitable for drilling in hard formations such as basalt and granite; Mn (0.8%~1.5%) and Si (0.6%~1.2%) synergistically improve the toughness of the matrix, and with the deoxidation and purification effect of Al (0.2%~0.5%) (inclusion content ≤0.03%), Nb element refines the grains (average grain size ≤8μm), reducing the crack incidence of the weld overlay to below 2.0%, the impact energy at -40℃ ≥55J, and the bonding strength with the tooth base material reaches 560MPa~590MPa. The impact spalling resistance is significantly better than that of traditional high carbon weld overlay systems.

[0035] In summary, through three major mechanisms—"carbide-nitride synergistic enhancement," "metallurgical purification," and "grain refinement"—the elements achieve a balance between high hardness, high bonding strength, excellent wear resistance, and thermal shock resistance in the weld overlay, making it suitable for complex geological drilling conditions.

[0036] This invention relates to a method for preparing wear-resistant weld overlay flux-cored wire for rotary drilling teeth. The wire is obtained through powder drying and mixing, steel strip treatment, and drawing. Specifically, it is implemented according to the following steps: Step 1: Weigh the following raw material powders according to their mass percentages: C powder 0.1%~0.3%, CrN powder 15%~20%, Ti powder 5%~10%, Mn powder 0.8%~1.5%, Si powder 0.6%~1.2%, V powder 5%~10%, Mo powder 0.9%~1.3%, Nb powder 3%~10%, Al powder 0.2%~0.5%, with the balance being Fe; The particle size of the raw material powder is no greater than 200μm.

[0037] Step 2: Place the powder in a heating furnace and keep it at 110℃~150℃ for 2h~4h to remove moisture. Then put it into a powder mixer and mix for 1h~3h to obtain uniform core powder.

[0038] Step 3: Clean the outer skin and roll it into a U-shape; The outer sheath is made of H08A low-carbon steel strip, with a thickness of 0.4mm~0.55mm and a width of 7mm~11mm; The cleaning method is as follows: Wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains; place the cleaned H08A low carbon steel strip into a tube furnace and keep it at 150℃~230℃ for 1h~2h to ensure the surface of the steel strip is clean.

[0039] Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth. The fill rate is 23%~27%; The specific steps of drawing are as follows: after the U-shaped outer skin is closed, it is drawn through the drawing die to reduce the diameter step by step, and the final diameter is controlled to be 1.2mm~1.6mm; after the drawing is completed, the wire is placed in a tube furnace and kept at 150℃~230℃ for 1h~2h. After cooling, the surface is wiped with anhydrous ethanol. The drawing process passes through drawing dies with diameters of 1.9mm~2.3mm, 1.7mm~2.1mm, 1.5mm~1.9mm, and 1.4mm~1.8mm in sequence.

[0040] A welding method for wear-resistant surfacing flux-cored wire suitable for rotary drilling teeth is described above. The welding process is as follows: MAG welding is used, the welding current is 140A~180A, the welding voltage is 19V~23V, the welding speed is 0.21m / min~0.25m / min, and the shielding gas is a mixture of Ar and CO2, wherein Ar is 80 vol% and CO2 is 20 vol%.

[0041] The weld overlay layer obtained after welding rotary drilling teeth using the wear-resistant weld overlay flux wire of this invention was tested, and the results are as follows: The hardness of the weld overlay is 60HRC-64HRC, and the bonding strength with the substrate is 550MPa-630MPa. It shows no cracks after 40-60 cycles of water-cooled thermal shock tests at 600℃. In the quartz sand abrasion test, the weight loss after 5 minutes of wear is ≤0.045g. Its wear resistance is 30%~40% higher than that of traditional welding wire. It can operate continuously for ≥200 hours without failure in granite formation drilling. It is suitable for drilling in hard formations and significantly extends the service life of rotary drilling teeth.

[0042] Example 1 The wear-resistant surfacing flux-cored wire for rotary drilling teeth in this embodiment includes an outer sheath and a flux core. The flux core is composed of the following components by mass percentage: 0.1% C powder, 15% CrN powder, 5% Ti powder, 0.8% Mn powder, 0.6% Si powder, 5% V powder, 0.9% Mo powder, 5% Nb powder, 0.2% Al powder, and the balance is Fe. The outer sheath is made of H08A low carbon steel strip, with a thickness of 0.4mm and a width of 7mm; the filling rate of the drug core in the outer sheath is 23%.

[0043] The above-mentioned method for preparing wear-resistant welded flux-cored wire for rotary drilling teeth is implemented according to the following steps: Step 1: Weigh the following raw material powders according to their mass percentages: The powder composition is as follows: C powder 0.1%, CrN powder 15%, Ti powder 5%, Mn powder 0.8%, Si powder 0.6%, V powder 5%, Mo powder 0.9%, Nb powder 5%, Al powder 0.2%, with the balance being Fe; the particle size of all powders is no greater than 200 μm. Step 2: Mix the raw material powders evenly; Specifically, the powder is placed in a heating furnace and kept at 110°C for 2 hours to remove moisture. Then, it is placed in a mixer and dry-mixed for 1 hour to obtain uniform core powder. Step 3: Clean the outer skin and roll it into a U-shape; The cleaning method is as follows: Wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains, and place it in a tube furnace to keep it at 150°C for 1 hour to ensure that the steel strip surface is clean. Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth. The fill rate is 23%; The specific steps of drawing are as follows: After the U-shaped outer skin is closed, it is drawn and reduced in diameter through drawing dies in succession, with diameters of 1.9mm, 1.7mm, 1.5mm and 1.4mm, to finally obtain a semi-finished wire with a diameter of 1.2mm; after drawing, the wire is placed in a tube furnace and kept at 150℃ for 1 hour. After cooling, the surface is wiped with anhydrous ethanol to obtain the finished wire.

[0044] The wear-resistant flux-cored wire for rotary drilling teeth prepared by the above preparation method was used to surface the rotary drilling teeth. The welding process was as follows: MAG welding was used, the welding current was 140A, the welding voltage was 19V, the welding speed was 0.21m / min, and the shielding gas was a mixture of Ar and CO2, in which Ar was 80 vol% and CO2 was 20 vol%.

[0045] Post-weld testing showed that the hardness of the weld layer reached 60HRC, the bonding strength with the substrate was 550MPa, no cracks were found after 40 cycles of 600℃ water-cooled thermal shock test, and the weight loss in 2 minutes of quartz sand abrasion test was 0.015g, with wear resistance 30% higher than that of traditional welding wire.

[0046] Example 2 The wear-resistant surfacing flux-cored wire suitable for rotary drilling teeth in this embodiment includes an outer sheath and a flux core. The flux core is composed of the following components by mass percentage: 0.2% C powder, 17% CrN powder, 7% Ti powder, 1.2% Mn powder, 0.9% Si powder, 7% V powder, 1.1% Mo powder, 3% Nb powder, 0.3% Al powder, and the balance is Fe. The outer sheath is made of H08A low carbon steel strip, with a thickness of 0.5mm and a width of 8mm; the filling rate of the drug core in the outer sheath is 24%.

[0047] The above-mentioned method for preparing wear-resistant welded flux-cored wire for rotary drilling teeth is implemented according to the following steps: Step 1: Weigh the following raw material powders according to their mass percentages: The powder composition is: 0.2% C powder, 17% CrN powder, 7% Ti powder, 1.2% Mn powder, 0.9% Si powder, 7% V powder, 1.1% Mo powder, 3% Nb powder, 0.3% Al powder, with the balance being Fe; the particle size of all powders is no greater than 200 μm. Step 2: Mix the raw material powders evenly; Specifically, the powder is placed in a heating furnace and kept at 120°C for 2.5 hours to remove moisture. Then, it is placed in a mixer and dry-mixed for 1.5 hours to obtain a uniform core powder. Step 3: Clean the outer skin and roll it into a U-shape; The cleaning method is as follows: wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains, and place it in a tube furnace to keep it at 180℃ for 1.2 hours to ensure that the steel strip surface is clean; Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth. The fill rate is 24%; The specific steps of drawing are as follows: After the U-shaped outer skin is closed, it is drawn and reduced in diameter through drawing dies in succession, with diameters of 2.0mm, 1.8mm, 1.6mm and 1.5mm, to finally obtain a semi-finished wire with a diameter of 1.3mm; after drawing, the wire is placed in a tube furnace and kept at 150℃ for 1 hour. After cooling, the surface is wiped with anhydrous ethanol to obtain the finished wire.

[0048] The wear-resistant flux-cored wire for rotary drilling teeth prepared by the above preparation method was used to surface the rotary drilling teeth. The welding process was as follows: MAG welding was used, the welding current was 150A, the welding voltage was 20V, the welding speed was 0.22m / min, and the shielding gas was a mixture of Ar and CO2, in which Ar was 80 vol% and CO2 was 20 vol%.

[0049] Post-weld testing showed that the hardness of the weld layer reached 61 HRC, the bonding strength with the substrate was 570 MPa, no cracks were found after 45 water-cooled thermal shock tests at 600℃, and the weight loss in 3 minutes of quartz sand abrasion test was 0.028 g, with wear resistance improved by 33% compared to traditional welding wire.

[0050] Example 3 The wear-resistant surfacing flux-cored wire suitable for rotary drilling teeth in this embodiment includes an outer sheath and a flux core. The flux core is composed of the following components by mass percentage: 0.2% C powder, 18% CrN powder, 8% Ti powder, 1.3% Mn powder, 1.0% Si powder, 8% V powder, 1.2% Mo powder, 5% Nb powder, 0.4% Al powder, and the balance is Fe. The outer sheath is made of H08A low carbon steel strip, with a thickness of 0.45mm and a width of 9mm; the filling rate of the drug core in the outer sheath is 25%.

[0051] The above-mentioned method for preparing wear-resistant welded flux-cored wire for rotary drilling teeth is implemented according to the following steps: Step 1: Weigh the following raw material powders according to their mass percentages: The powder composition is as follows: C powder 0.2%, CrN powder 18%, Ti powder 8%, Mn powder 1.3%, Si powder 1.0%, V powder 8%, Mo powder 1.2%, Nb powder 5%, Al powder 0.4%, with the balance being Fe; the particle size of all powders is no greater than 200 μm. Step 2: Mix the raw material powders evenly; Specifically, the powder is placed in a heating furnace and kept at 130°C for 3 hours to remove moisture. Then, it is placed in a mixer and dry-mixed for 2 hours to obtain a uniform core powder. Step 3: Clean the outer skin and roll it into a U-shape; The cleaning method is as follows: wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains, and place it in a tube furnace to keep it at 200℃ for 1.5 hours to ensure that the steel strip surface is clean; Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth. The fill rate is 25%; The specific steps of drawing are as follows: After the U-shaped outer skin is closed, it is drawn and reduced in diameter through drawing dies in succession, with diameters of 2.1mm, 1.9mm, 1.7mm and 1.6mm, to finally obtain a semi-finished wire with a diameter of 1.4mm; after drawing, the wire is placed in a tube furnace and kept at 200℃ for 1.5h. After cooling, the surface is wiped with anhydrous ethanol to obtain the finished wire.

[0052] The wear-resistant flux-cored wire for rotary drilling teeth prepared by the above preparation method was used to surface the rotary drilling teeth. The welding process was as follows: MAG welding was used, the welding current was 160A, the welding voltage was 21V, the welding speed was 0.23m / min, and the shielding gas was a mixture of Ar and CO2, in which Ar was 80 vol% and CO2 was 20 vol%.

[0053] Post-weld testing showed that the hardness of the weld layer reached 62HRC, the bonding strength with the substrate was 590MPa, no cracks were found after 50 cycles of 600℃ water-cooled thermal shock test, and the weight loss in 4 minutes of quartz sand abrasion test was 0.038g, with wear resistance improved by 35% compared with traditional welding wire.

[0054] Example 4 The wear-resistant surfacing flux-cored wire suitable for rotary drilling teeth in this embodiment includes an outer sheath and a flux core. The flux core is composed of the following components by mass percentage: 0.3% C powder, 19% CrN powder, 9% Ti powder, 1.4% Mn powder, 1.1% Si powder, 9% V powder, 1.3% Mo powder, 7% Nb powder, 0.4% Al powder, and the balance is Fe. The outer sheath is made of H08A low carbon steel strip, with a thickness of 0.5mm and a width of 10mm; the filling rate of the drug core in the outer sheath is 26%.

[0055] The above-mentioned method for preparing wear-resistant welded flux-cored wire for rotary drilling teeth is implemented according to the following steps: Step 1: Weigh the following raw material powders according to their mass percentages: The powder composition is as follows: C powder 0.3%, CrN powder 19%, Ti powder 9%, Mn powder 1.4%, Si powder 1.1%, V powder 9%, Mo powder 1.3%, Nb powder 7%, Al powder 0.4%, with the balance being Fe; the particle size of all powders is no greater than 200 μm. Step 2: Mix the raw material powders evenly; Specifically, the powder is placed in a heating furnace and kept at 140°C for 3.5 hours to remove moisture. Then, it is placed in a mixer and dry-mixed for 2.5 hours to obtain a uniform core powder. Step 3: Clean the outer skin and roll it into a U-shape; The cleaning method is as follows: wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains, and place it in a tube furnace to keep it at 220℃ for 1.8 hours to ensure that the steel strip surface is clean; Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth. The fill rate is 26%; The specific steps of drawing are as follows: After the U-shaped outer skin is closed, it is drawn and reduced in diameter through drawing dies in succession, with diameters of 2.2mm, 2.0mm, 1.8mm and 1.7mm, to finally obtain a semi-finished wire with a diameter of 1.5mm; after drawing, the wire is placed in a tube furnace and kept at 220℃ for 1.8h. After cooling, the surface is wiped with anhydrous ethanol to obtain the finished wire.

[0056] The wear-resistant flux-cored wire for rotary drilling teeth prepared by the above preparation method was used to surface the rotary drilling teeth. The welding process was as follows: MAG welding was used, the welding current was 170A, the welding voltage was 22V, the welding speed was 0.24m / min, and the shielding gas was a mixture of Ar and CO2, in which Ar was 80 vol% and CO2 was 20 vol%.

[0057] Post-weld testing showed that the hardness of the weld layer reached 63 HRC, the bonding strength with the substrate was 610 MPa, no cracks were found after 55 water-cooled thermal shock tests at 600℃, and the weight loss in 5 minutes of quartz sand abrasion test was 0.045g, with wear resistance improved by 38% compared to traditional welding wire.

[0058] Example 5 The wear-resistant surfacing flux-cored wire suitable for rotary drilling teeth in this embodiment includes an outer sheath and a flux core. The flux core is composed of the following components by mass percentage: 0.3% C powder, 20% CrN powder, 10% Ti powder, 1.5% Mn powder, 1.2% Si powder, 10% V powder, 1.3% Mo powder, 10% Nb powder, 0.5% Al powder, and the balance is Fe. The outer sheath is made of H08A low carbon steel strip, with a thickness of 0.55mm and a width of 11mm; the filling rate of the drug core in the outer sheath is 27%.

[0059] The above-mentioned method for preparing wear-resistant welded flux-cored wire for rotary drilling teeth is implemented according to the following steps: Step 1: Weigh the following raw material powders according to their mass percentages: The powder composition is as follows: C powder 0.3%, CrN powder 20%, Ti powder 10%, Mn powder 1.5%, Si powder 1.2%, V powder 10%, Mo powder 1.3%, Nb powder 10%, Al powder 0.5%, with the balance being Fe; the particle size of all powders is no greater than 200 μm. Step 2: Mix the raw material powders evenly; Specifically, the powder is placed in a heating furnace and kept at 150°C for 4 hours to remove moisture. Then, it is placed in a mixer and dry-mixed for 3 hours to obtain a uniform core powder. Step 3: Clean the outer skin and roll it into a U-shape; The cleaning method is as follows: Wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains, and place it in a tube furnace to keep it at 230℃ for 2 hours to ensure that the steel strip surface is clean. Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth. The fill rate is 27%; The specific steps of drawing are as follows: After the U-shaped outer skin is closed, it is drawn and reduced in diameter through drawing dies in succession, with diameters of 2.3mm, 2.1mm, 1.9mm and 1.8mm, to finally obtain a semi-finished wire with a diameter of 1.6mm; after drawing, the wire is placed in a tube furnace and kept at 230℃ for 2 hours. After cooling, the surface is wiped with anhydrous ethanol to obtain the finished wire.

[0060] The wear-resistant flux-cored wire for rotary drilling teeth prepared by the above preparation method was used to surface the rotary drilling teeth. The welding process was as follows: MAG welding was used, the welding current was 180A, the welding voltage was 23V, the welding speed was 0.25m / min, and the shielding gas was a mixture of Ar and CO2, in which Ar was 80 vol% and CO2 was 20 vol%.

[0061] Post-weld testing showed that the hardness of the weld layer reached 64 HRC, the bonding strength with the substrate was 630 MPa, and no cracks were found after 60 cycles of water-cooled thermal shock tests at 600℃. In the quartz sand abrasion test, the weight loss was 0.032 g in 5 minutes, and the wear resistance was 40% higher than that of traditional welding wire. In the drilling test of granite strata, it could operate continuously for 250 hours without failure. Its overall performance was the best among all embodiments.

[0062] Examples 1-5 above demonstrate that the present invention, through precise control of the core composition (especially the synergistic ratio of nitrides and carbides) and preparation process, effectively improves the wear resistance, crack resistance, and thermal stability of the weld overlay layer of rotary drilling teeth, meeting the needs of different geological drilling conditions. Among them, Example 5 exhibits the best overall performance among the five schemes.

[0063] Its weld overlay hardness reaches 64 HRC, which is outstanding in all embodiments, demonstrating significant resistance to abrasive cutting and plastic deformation; the bonding strength reaches 630 MPa, far exceeding other embodiments, ensuring a firm bond between the weld overlay and the tooth substrate, fundamentally reducing the risk of spalling failure. It exhibits excellent thermal shock stability, showing no cracks after 60 cycles of 600℃ water-cooled thermal shock tests, and can stably adapt to the harsh working conditions of alternating high temperatures and rapid cooling in rotary drilling operations.

[0064] In terms of wear resistance, Example 5 showed a weight loss of only 0.032g in 5 minutes of quartz sand abrasion test, with wear resistance improved by 40% compared to traditional welding wire; in granite formation drilling test, it can operate continuously for 250 hours without failure, with a significantly extended wear life.

[0065] This superior performance is attributed to the synergistic effect of a high proportion of CrN with Ti, V, and Nb in the flux core, forming a multi-component nitride-carbide strengthening system of CrN, TiN, VC, and NbC. The hard phase is evenly distributed and tightly bonded to the matrix. Combined with deep deoxidation and purification of Al and Si (extremely low inclusion content), optimized preparation process (heating and holding at 150℃ for 4 hours to ensure uniform powder drying, and tube furnace treatment at 230℃ to improve the compatibility between the steel strip and the flux core), and matching welding parameters (180A current and 23V voltage to ensure the density of the cladding layer), the best balance of hardness, toughness, and wear resistance is ultimately achieved.

[0066] Overall, Example 5 is superior in all core performance indicators and is the optimal solution for harsh drilling conditions such as hard rock formations.

[0067] Example 6 The wear-resistant surfacing flux-cored wire for rotary drilling teeth in this embodiment includes an outer sheath and a flux core. The flux core is composed of the following components by mass percentage: 0.25% C powder, 19% CrN powder, 9% Ti powder, 1.4% Mn powder, 1.1% Si powder, 9% V powder, 1.2% Mo powder, 9% Nb powder, 0.4% Al powder, and the balance is Fe. The outer sheath is made of H08A low carbon steel strip, with a thickness of 0.5mm and a width of 10mm; the filling rate of the drug core in the outer sheath is 26%.

[0068] The above-mentioned method for preparing wear-resistant welded flux-cored wire for rotary drilling teeth is implemented according to the following steps: Step 1: Weigh the following raw material powders according to their mass percentages: The powder composition is as follows: C powder 0.25%, CrN powder 19%, Ti powder 9%, Mn powder 1.4%, Si powder 1.1%, V powder 9%, Mo powder 1.2%, Nb powder 9%, Al powder 0.4%, with the balance being Fe; the particle size of all powders is no greater than 200 μm. Step 2: Mix the raw material powders evenly; Specifically, the powder is placed in a heating furnace and kept at 140°C for 3 hours to remove moisture. Then, it is placed in a mixer and dry-mixed for 2.5 hours to obtain a uniform core powder. Step 3: Clean the outer skin and roll it into a U-shape; The cleaning method is as follows: wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains, and place it in a tube furnace to keep it at 220℃ for 1.8 hours to ensure that the steel strip surface is clean; Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth. The fill rate is 26%; The specific steps of drawing are as follows: After the U-shaped outer skin is closed, it is drawn and reduced in diameter through drawing dies in succession, with diameters of 2.2mm, 2.0mm, 1.8mm and 1.7mm, to finally obtain a semi-finished wire with a diameter of 1.5mm; after drawing, the wire is placed in a tube furnace and kept at 220℃ for 1.8h. After cooling, the surface is wiped with anhydrous ethanol to obtain the finished wire.

[0069] The wear-resistant flux-cored wire for rotary drilling teeth prepared by the above preparation method was used to surface the rotary drilling teeth. The welding process was as follows: MAG welding was used, the welding current was 170A, the welding voltage was 22V, the welding speed was 0.24m / min, and the shielding gas was a mixture of Ar and CO2, in which Ar was 80 vol% and CO2 was 20 vol%.

[0070] Post-weld testing showed that the hardness of the weld layer reached 63HRC, the bonding strength with the substrate was 600MPa, no cracks were found after 55 water-cooled thermal shock tests at 600℃, and the weight loss in 4 minutes of quartz sand abrasion test was 0.004g, with wear resistance improved by 36% compared to traditional welding wire.

Claims

1. A flux-cored wire suitable for wear-resistant surfacing welding of rotary drilling teeth, characterized in that, It includes an outer casing and a core, wherein the core is composed of the following components by weight percentage: The powder composition is as follows: C powder 0.1%~0.3%, CrN powder 15%~20%, Ti powder 5%~10%, Mn powder 0.8%~1.5%, Si powder 0.6%~1.2%, V powder 5%~10%, Mo powder 0.9%~1.3%, Nb powder 3%~10%, Al powder 0.2%~0.5%, with the balance being Fe; the powder particle size is not greater than 200μm.

2. The wear-resistant flux-cored wire for rotary drilling teeth according to claim 1, characterized in that, The core consists of the following components by mass percentage: The composition is as follows: C powder 0.1%~0.3%, CrN powder 17%~20%, Ti powder 7%~10%, Mn powder 0.8%~1.5%, Si powder 0.6%~1.2%, V powder 7%~10%, Mo powder 0.9%~1.3%, Nb powder 5%~10%, Al powder 0.2%~0.5%, with the balance being Fe.

3. The wear-resistant flux-cored wire for rotary drilling teeth according to claim 1, characterized in that, The outer sheath is made of H08A low-carbon steel strip, with a thickness of 0.4mm to 0.55mm and a width of 7mm to 11mm.

4. The wear-resistant flux-cored wire for rotary drilling teeth according to claim 1, characterized in that, The filling rate of the herbal core in the outer skin is 23%~27%.

5. A method for preparing wear-resistant flux-cored wire for rotary drilling teeth, characterized in that, The specific steps are as follows: Step 1: Weigh the raw material powders according to their mass percentages; Step 2: Mix the raw material powders evenly; Step 3: Clean the outer skin and roll it into a U-shape; Step 4: Fill the U-shaped outer skin with raw material powder according to the predetermined filling rate, and draw it to obtain a wear-resistant flux-cored wire suitable for rotary drilling teeth.

6. The method for preparing wear-resistant flux-cored wire for rotary drilling teeth according to claim 5, characterized in that, The mass percentage of each component in the raw material powder in step 1 is as follows: The raw material powder consists of 0.1%~0.3% C powder, 15%~20% CrN powder, 5%~10% Ti powder, 0.8%~1.5% Mn powder, 0.6%~1.2% Si powder, 5%~10% V powder, 0.9%~1.3% Mo powder, 3%~10% Nb powder, and 0.2%~0.5% Al powder, with the balance being Fe; the particle size of the raw material powder is no greater than 200μm.

7. The method for preparing wear-resistant flux-cored wire for rotary drilling teeth according to claim 5, characterized in that, The specific steps of step 2 are as follows: place the powder in a heating furnace and keep it at 110℃~150℃ for 2h~4h to remove moisture. Then, put it into a powder mixer and mix for 1h~3h to obtain uniform core powder.

8. The method for preparing wear-resistant flux-cored wire for rotary drilling teeth according to claim 5, characterized in that, In step 3, the outer sheath is made of H08A low-carbon steel strip with a thickness of 0.4mm to 0.55mm and a width of 7mm to 11mm. The cleaning method is as follows: Wipe the surface of H08A low carbon steel strip with anhydrous ethanol to remove oil stains; place the cleaned H08A low carbon steel strip into a tube furnace and keep it at 150℃~230℃ for 1h~2h to ensure the surface of the steel strip is clean.

9. The method for preparing wear-resistant flux-cored wire for rotary drilling teeth according to claim 5, characterized in that, In step 4, the filling rate is 23%~27%; The specific steps of drawing are as follows: after the U-shaped outer skin is closed, it is drawn through the drawing die to reduce the diameter step by step, and the final diameter is controlled to be 1.2mm~1.6mm; after the drawing is completed, the wire is placed in a tube furnace and kept at 150℃~230℃ for 1h~2h. After cooling, the surface is wiped with anhydrous ethanol.

10. A welding method applicable to wear-resistant surfacing flux-cored wire for rotary drilling teeth, characterized in that, The rotary drilling teeth are surfacing using the flux-cored wire for wear-resistant surfacing as described in any one of claims 1 to 4. The welding process is as follows: MAG welding is used, the welding current is 140A to 180A, the welding voltage is 19V to 23V, the welding speed is 0.21m / min to 0.25m / min, and the shielding gas is a mixture of Ar and CO2, wherein Ar is 80 vol% and CO2 is 20 vol%.

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