High-strength wear-resistant welding rod and preparation method and application thereof

Abstract

The invention discloses a high-strength wear-resistant welding rod and a preparation method and application thereof in the technical field of welding materials, raw materials of the high-strength wear-resistant welding rod comprise a core wire and a coating wrapping the surface of the core wire, the high-strength wear-resistant welding rod is characterized in that the core wire is an H08E low-carbon steel welding wire, and the coating comprises main alloy components including 28-32% of ferrochrome, 9-11% of ferromolybdenum and 6-8% of tungsten powder; 3-5% of titanium carbide and 4-6% of ferroboron; a carbide regulating agent: 3-4% of graphite powder and 1-2% of nano silicon carbide; a slag former: 12-14% of rutile and 9-11% of fluorite; and auxiliary additives: 1.5-2.5% of rare earth cerium iron alloy and 6-8% of potash water glass. Through component and process innovation, the wear-resistant welding rod with high hardness, high toughness and low hydrogen content is prepared, and the problems of hardness-toughness contradiction, hydrogen embrittlement sensitivity, insufficient high-temperature performance and the like of a wear-resistant welding rod in the prior art are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding materials, and relates to a high-strength wear-resistant welding rod and a preparation method and application thereof, and in particular to a welding rod suitable for surface strengthening of a crushing hammer head of a mining machine. Background Art

[0002] Hardfacing is an important branch in remanufacturing engineering because it can form a typical metallurgical bond with the base material. The hardfacing layer has a small tendency to peel off during service and the hardfacing alloy can be selected or designed according to the service performance, so that the surface of the material or part has good wear resistance, corrosion resistance, high temperature resistance, radiation resistance and other properties. It has great flexibility in technology. Among them, hardfacing with wear-resistant electrodes occupies an important position in repair and composite manufacturing, and is widely used to improve the wear resistance of mechanical engineering structures.

[0003] Traditional high-chromium cast iron welding rods have high hardness but poor impact toughness, making them prone to cracking. Tough welding rods, on the other hand, lack sufficient hardness to meet wear resistance requirements. Existing welding rods require high-temperature preheating and slow cooling, which can easily lead to porosity and cracking. The high hydrogen content in the deposited metal increases the risk of delayed cracking. High cost: Welding rods containing precious metals such as cobalt and nickel are expensive, making them difficult to implement on a large scale. Summary of the Invention

[0004] The purpose of the present invention is to provide a wear-resistant welding rod with high hardness, high toughness and low hydrogen content, and to solve the problems of strength-toughness contradiction, complex process and high cost in the existing technology through composition and process innovation.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A high-strength wear-resistant welding rod comprises a welding core and a coating covering the surface of the welding core, wherein the welding core is an H08E low-carbon steel welding wire, and the coating comprises:

[0007] Main alloy components: 28-32% ferrochromium, 9-11% ferromolybdenum, 6-8% tungsten powder; 3-5% titanium carbide, 4-6% ferroboron;

[0008] Carbide regulator: graphite powder 3-4%, nano silicon carbide 1-2%;

[0009] Slag-forming agent: rutile 12-14%, fluorite 9-11%;

[0010] Auxiliary additives: rare earth ferrocerium alloy 1.5-2.5%, potassium water glass 6-8%.

[0011] In the present invention, a multi-element synergistic strengthening mechanism is adopted, and the high-chromium-molybdenum-tungsten composite system significantly improves high-temperature wear resistance by combining solid solution strengthening with carbide dispersion strengthening.

[0012] In the present invention, titanium carbide and nano-silicon carbide are introduced for synergistic reinforcement to form a gradient distribution of carbides (surface titanium carbide hard phase + internal M7C3 phase), thereby improving wear resistance and inhibiting crack propagation.

[0013] In the present invention, graphite powder is combined with nano-silicon carbide: the graphite powder regulates the carbon activity of the molten pool and promotes the uniform precipitation of carbides (such as Cr7C3 and WC); nano-silicon carbide (50nm level) acts as a heterogeneous nucleation point to refine the carbide grains (average size ≤ 5μm), reduce the hardness gradient difference, and solve the problem of uneven hardness distribution in traditional welding rods.

[0014] In the present invention, rare earth ferrocerium alloy and ferroboron are compositely deoxidized to reduce the oxygen content of the deposited metal (≤0.02%), refine the grains to 5-8 μm, purify the grain boundaries, and reduce the segregation of sulfur and phosphorus.

[0015] In the present invention, titanium carbide and ferroboron work together: titanium carbide as a hard phase improves resistance to abrasive wear, and ferroboron enhances impact resistance by forming a Fe-B eutectic phase, thereby avoiding brittle cracking caused by a single carbide in traditional high-chromium cast iron welding rods.

[0016] According to a preferred embodiment of the present invention, the coating comprises:

[0017] Main alloy components: 28% ferrochromium, 9% ferromolybdenum, 6% tungsten powder; 3% titanium carbide, 4% ferroboron;

[0018] Carbide regulator: graphite powder 3%, nano silicon carbide 1%;

[0019] Slag-forming agent: rutile 12%, fluorite 9%;

[0020] Auxiliary additives: rare earth ferrocerium alloy 1.5%, potassium water glass 6%.

[0021] According to a preferred embodiment of the present invention, the coating comprises:

[0022] Main alloy components: 32% ferrochromium, 11% ferromolybdenum, 8% tungsten powder; 5% titanium carbide, 6% ferroboron;

[0023] Carbide regulator: graphite powder 4%, nano silicon carbide 2%;

[0024] Slag-forming agent: rutile 14%, fluorite 11%;

[0025] Auxiliary additives: rare earth ferrocerium alloy 2.5%, potassium water glass 8%.

[0026] In the present invention, a slag-making system is designed: rutile (TiO2 12-14%) and fluorite (CaF2 9-11%) are compositely used for slag-making: TiO2 improves arc stability and reduces spatter rate; CaF2 reduces slag viscosity, increases slag removal rate to over 95%, and reduces unfused defects.

[0027] In this invention, the addition of the auxiliary additive rare earth ferrocerium alloy aims to purify the molten pool with CeO2, reduce oxide inclusions, refine the grain size of the overlay layer (grain size ≥ 8), and improve impact toughness. Potassium water glass (K2O·nSiO2 6-8%) is added to increase coating strength and reduce moisture absorption.

[0028] In the present invention, through multi-phase composite strengthening, nano-scale carbide regulation and rare earth modification, the coordinated optimization of hardness, toughness and processability is achieved, filling the technical gap of traditional welding rods under high temperature and high impact conditions.

[0029] According to a preferred embodiment of the present invention, the mass percentage of the components of H08E low carbon steel welding wire is C≤0.08%, Mn:0.4-0.65%, Si≤0.03%, S≤0.02%, P≤0.02%, Cr≤0.2%, Ni≤0.3%, Cu≤0.35%, and the balance is iron.

[0030] According to a preferred embodiment of the present invention, the diameter of the welding core is 3.2-4.0 mm.

[0031] The present invention also provides a method for preparing the high-strength wear-resistant welding rod, comprising the steps of:

[0032] S1. Preparation of coating slurry: mixing the main alloy component and the slag-forming agent to obtain a mixture, ball-milling the mixture into particles, adding the carbide regulator, and mixing with the auxiliary additives to form a slurry;

[0033] S2, welding core coating: adding 1% aluminum powder to the slurry processed in step S1, coating the welding core to form an inner layer, pre-drying the coated inner layer of the welding core at 80°C for 1 hour, and coating the inner layer surface of the welding core with the remaining slurry to form an outer layer;

[0034] S3. Dry the welding core after coating in S2 in the following first and second stages respectively: first stage: drying at 80-100° C. for 2 hours to remove free water; second stage: drying at 250-280° C. for 1.5 hours to reduce bound water and hydrogen residue.

[0035] In the present invention, by ball-milling the main alloy components and the slag-forming agent to a particle size of ≤50 μm and optimizing the ball-milling time and rotation speed (such as a ball-to-material ratio of 10:1 and a rotation speed of 200 rpm), the powder activity and the molten pool reaction efficiency are significantly improved, and the porosity of the surfacing layer is reduced.

[0036] In the present invention, 6-8% potassium water glass is used as a binder, the moisture absorption rate of the binder is reduced, and the qualified rate of the coating pressure coating molding is improved.

[0037] In the present invention, the viscosity of the slurry is stabilized at 300-400 mPa·s (measured by a rotational viscometer) by adjusting the ratio of potassium water glass to solid content, thereby ensuring coating uniformity.

[0038] In this method, 1% aluminum powder (5-10 μm particle size) is added to the inner functional layer. After pre-drying (80°C for 1 hour), a porous structure is formed, which enhances the adhesion of the outer slurry and reduces weld spatter. The aluminum powder preferentially oxidizes to form Al2O3 at the high arc temperature, reducing slag viscosity and improving slag removal performance.

[0039] In the present invention, the first stage of low-temperature drying removes free water from the slurry, preventing cracking of the coating caused by rapid heating. The second stage of high-temperature drying deeply removes bound water from potassium water glass, while reducing residual hydrogen and inhibiting hydrogen-induced cracking.

[0040] In the present invention, a step-by-step heating method (heating rate ≤ 20°C / min) is used to prevent local overheating of the coating and component segregation. A slight negative pressure (vacuum degree -0.05MPa) is introduced during the high-temperature drying stage to further reduce the hydrogen content.

[0041] According to a preferred embodiment of the present invention, in step S1, the particle size of the particles is ≤50 μm, and the slurry viscosity is 300-400 mPa·s.

[0042] According to a preferred embodiment of the present invention, in step S2, the coating thickness of the inner layer of the welding core is 0.5-0.8 mm, and the coating thickness of the outer layer of the welding core is 1.3-1.5 times the diameter of the welding core.

[0043] In the present invention, the coating thickness of the outer layer of the welding core is 1.3-1.5 times the diameter of the welding core (for example, 5.2-6.0mm for a Φ4.0mm welding core), ensuring the continuous protection of the coating during the welding process and improving the deposition efficiency by %. Through the two-coating process, nano-SiC is enriched in the surface layer, forming a gradient wear-resistant layer (surface hardness HRC 62, transition layer HRC 58), which improves the impact fatigue life.

[0044] The present invention also provides an application of the high-strength wear-resistant welding rod in surface strengthening of a crushing hammer head of a mining machine.

[0045] According to a preferred embodiment of the present invention, the welding process includes: sandblasting or angle grinder treatment to make the surface roughness of the hammer head reach Ra≤12.5μm, the hammer head surface is preheated to 200-250℃, the layer temperature is ≤150℃, the welding current is 120A-180A, and the welding method adopts transverse fish scale overlap.

[0046] The beneficial effects of the present invention are as follows: the present invention uses four core technologies, namely nano-scale dispersion strengthening, rare earth melt pool purification, gradient coating design, and staged low-hydrogen drying, to break through the bottlenecks of traditional wear-resistant welding rods such as the hardness-toughness contradiction, hydrogen embrittlement sensitivity, and insufficient high-temperature performance. Through the gradient distribution of nano-silicon carbide and titanium carbide, combined with tungsten-molybdenum solid solution strengthening, a multi-scale composite structure is constructed, so that when the hardness HRC of the surfacing layer reaches 62.5, the impact toughness remains at 27.5J, and the high-temperature hardness HRC at 600°C is stable at 55.8, and the service life is significantly improved compared to the traditional one. The rare earth cerium iron alloy purifies the melt pool through the Ce-OS composite reaction, and the hydrogen-induced cracking rate is significantly reduced. The double-layer gradient coating design increases the bonding strength to 15MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The microstructure diagram shows the distribution of TiC particles in the coating. DETAILED DESCRIPTION

[0048] The present application is described in further detail below in conjunction with the accompanying drawings. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0049] 1. Main raw materials:

[0050] H08E low carbon steel welding wire: purchased from Atlantic Welding;

[0051] Ferrochrome: purchased from Jitie Group;

[0052] Ferromolybdenum: purchased from Jinduicheng Molybdenum Industry;

[0053] Tungsten powder: purchased from Xiamen Tungsten Industry;

[0054] Titanium carbide: purchased from Luoyang Kexin Materials;

[0055] Nano-silicon carbide: purchased from Shandong Jinhong New Materials;

[0056] Graphite powder: purchased from Qingdao Haida Graphite;

[0057] Ferroboron: purchased from Liaoning Shougang Ferroboron;

[0058] Rutile: purchased from Yunnan Xinli Titanium Industry;

[0059] Fluorite: purchased from the Siziwang Banner Fluorite Mine in Inner Mongolia;

[0060] Rare earth ferrocerium alloy: purchased from Baotou Rare Earth Research Institute;

[0061] Potassium water glass: purchased from Shandong Dongyue Chemical;

[0062] 2. Example

[0063] Example 1

[0064] A high-strength wear-resistant welding rod, whose raw materials include, by mass percentage, 30% ferrochromium, 10% ferromolybdenum, 7% tungsten powder; 4% titanium carbide, 5% ferroboron; 3.5% graphite powder, 1.5% nano-silicon carbide; 13% rutile, 10% fluorite; 2% rare earth ferrocerium alloy, and 7% potassium water glass.

[0065] The preparation method of the high-strength wear-resistant welding rod comprises the following steps:

[0066] S1. Preparation of coating slurry: 30 g of ferrochrome, 10 g of ferromolybdenum, 7 g of tungsten powder, 4 g of titanium carbide, 5 g of ferroboron, 13 g of rutile, and 10 g of fluorite are mixed to obtain a mixture. The mixture is ball-milled to a particle size of 50 μm. 3.5 g of graphite powder and 1.5 g of nano-silicon carbide are added, and the mixture is mixed with 2 g of rare earth ferrocerium alloy and 7 g of potassium water glass to form a slurry. The viscosity of the slurry after mixing is 350 mPa·s.

[0067] S2. Welding core coating: 1 g of aluminum powder was added to the slurry obtained in step S1, and the surface of the welding core was coated to form an inner layer with a coating thickness of 0.6 mm. The coated inner layer of the welding core was pre-dried at 80°C for 1 hour, and the remaining slurry was coated on the inner surface of the welding core to form an outer layer with a coating thickness of 4.8 mm.

[0068] S3. The coated welding core in S2 is dried in the following first and second stages respectively: the first stage: drying at 80-100°C for 2 hours to remove free water; the second stage: drying at 250-280°C for 1.5 hours to reduce bound water and residual hydrogen, and finally a high-strength wear-resistant welding rod is produced.

[0069] Example 2

[0070] A high-strength wear-resistant welding rod, whose raw materials include, by mass percentage, 28% ferrochromium, 9% ferromolybdenum, 6% tungsten powder; 3% titanium carbide, 4% ferroboron; 3% graphite powder, 1% nano-silicon carbide; 12% rutile, 9% fluorite; 1.5% rare earth ferrocerium alloy, and 6% potassium water glass.

[0071] The preparation method of the high-strength wear-resistant welding rod comprises the following steps:

[0072] S1. Preparation of coating slurry: 28g of tungsten powder, 9g of ferromolybdenum, 6g of tungsten powder, 3g of titanium carbide, 4g of ferroboron, 12g of rutile, and 9g of fluorite are mixed to obtain a mixture, and the mixture is ball-milled to a particle size of 50 μm. 3g of graphite powder and 1g of nano-silicon carbide are added, and the mixture is mixed with 1.5g of rare earth ferrocerium alloy and 6g of potassium water glass to form a slurry. The viscosity of the slurry after mixing is 350 mPa·s.

[0073] S2. Welding core coating: 1 g of aluminum powder was added to the slurry obtained in step S1, and the surface of the welding core was coated to form an inner layer with a coating thickness of 0.6 mm. The coated inner layer of the welding core was pre-dried at 80°C for 1 hour, and the remaining slurry was coated on the inner surface of the welding core to form an outer layer with a coating thickness of 4.8 mm.

[0074] S3. The coated welding core in S2 is dried in the following first and second stages respectively: the first stage: drying at 80-100°C for 2 hours to remove free water; the second stage: drying at 250-280°C for 1.5 hours to reduce bound water and residual hydrogen, and finally a high-strength wear-resistant welding rod is produced.

[0075] Example 3

[0076] A high-strength wear-resistant welding rod, whose raw materials include, by mass percentage, 32% ferrochromium, 11% ferromolybdenum, 8% tungsten powder; 5% titanium carbide, 6% ferroboron; 4% graphite powder, 2% nano-silicon carbide; 14% rutile, 11% fluorite; 2.5% rare earth ferrocerium alloy, and 8% potassium water glass.

[0077] The preparation method of the high-strength wear-resistant welding rod comprises the following steps:

[0078] S1. Preparation of coating slurry: 32 g of ferrochrome, 11 g of ferromolybdenum, 8 g of tungsten powder, 5 g of titanium carbide, 6 g of ferroboron, 14 g of rutile, and 11 g of fluorite were mixed to obtain a mixture. The mixture was ball-milled to a particle size of 50 μm. 4 g of graphite powder and 2 g of nano-silicon carbide were added, and the mixture was mixed with 2.5 g of rare earth ferrocerium alloy and 8 g of potassium water glass to form a slurry. The viscosity of the slurry after mixing was 350 mPa·s.

[0079] S2. Welding core coating: 1 g of aluminum powder was added to the slurry obtained in step S1, and the surface of the welding core was coated to form an inner layer with a coating thickness of 0.6 mm. The coated inner layer of the welding core was pre-dried at 80°C for 1 hour, and the remaining slurry was coated on the inner surface of the welding core to form an outer layer with a coating thickness of 4.8 mm.

[0080] S3. The coated welding core in S2 is dried in the following first and second stages respectively: the first stage: drying at 80-100°C for 2 hours to remove free water; the second stage: drying at 250-280°C for 1.5 hours to reduce bound water and residual hydrogen, and finally a high-strength wear-resistant welding rod is produced.

[0081] Comparative Example 1

[0082] A high-strength wear-resistant welding rod, whose raw materials include, by mass percentage, 30% ferrochrome, 10% ferromolybdenum, 7% tungsten powder; 5% ferroboron; 3.5% graphite powder, 1.5% nano-silicon carbide; 13% rutile, 10% fluorite; 2% rare earth ferrocerium alloy, and 7% potassium water glass.

[0083] The preparation method of the high-strength wear-resistant welding rod comprises the following steps:

[0084] S1. Preparation of coating slurry: 30 g of ferrochrome, 10 g of ferromolybdenum, 7 g of tungsten powder, 5 g of ferroboron, 13 g of rutile, and 10 g of fluorite were mixed to obtain a mixture, and the mixture was ball-milled to a particle size of 50 μm. 3.5 g of graphite powder and 1.5 g of nano-silicon carbide were added, and the mixture was mixed with 2 g of rare earth ferrocerium alloy and 7 g of potassium water glass to form a slurry. The viscosity of the slurry after mixing was 350 mPa·s.

[0085] S2. Welding core coating: 1 g of aluminum powder was added to the slurry obtained in step S1, and the surface of the welding core was coated to form an inner layer with a coating thickness of 0.6 mm. The coated inner layer of the welding core was pre-dried at 80°C for 1 hour, and the remaining slurry was coated on the inner surface of the welding core to form an outer layer with a coating thickness of 4.8 mm.

[0086] S3. The coated welding core in S2 is dried in the following first and second stages respectively: the first stage: drying at 80-100°C for 2 hours to remove free water; the second stage: drying at 250-280°C for 1.5 hours to reduce bound water and residual hydrogen, and finally a high-strength wear-resistant welding rod is produced.

[0087] Comparative Example 2

[0088] A high-strength wear-resistant welding rod, whose raw materials include, by mass percentage, 30% ferrochrome, 10% ferromolybdenum, 7% tungsten powder; 4% titanium carbide, 5% ferroboron; 3.5% graphite powder; 13% rutile, 10% fluorite; 2% rare earth ferrocerium alloy, and 7% potassium water glass.

[0089] The preparation method of the high-strength wear-resistant welding rod comprises the following steps:

[0090] S1. Preparation of coating slurry: 30 g of ferrochrome, 10 g of ferromolybdenum, 7 g of tungsten powder, 4 g of titanium carbide, 5 g of ferroboron, 13 g of rutile, and 10 g of fluorite were mixed to obtain a mixture. The mixture was ball-milled to a particle size of 50 μm. 3.5 g of graphite powder was added and mixed with 2 g of rare earth ferrocerium alloy and 7 g of potassium water glass to form a slurry. The viscosity of the slurry after mixing was 350 mPa·s.

[0091] S2. Welding core coating: 1 g of aluminum powder was added to the slurry obtained in step S1, and the surface of the welding core was coated to form an inner layer with a coating thickness of 0.6 mm. The coated inner layer of the welding core was pre-dried at 80°C for 1 hour, and the remaining slurry was coated on the inner surface of the welding core to form an outer layer with a coating thickness of 4.8 mm.

[0092] S3. The coated welding core in S2 is dried in the following first and second stages respectively: the first stage: drying at 80-100°C for 2 hours to remove free water; the second stage: drying at 250-280°C for 1.5 hours to reduce bound water and residual hydrogen, and finally a high-strength wear-resistant welding rod is produced.

[0093] Comparative Example 3

[0094] A high-strength wear-resistant welding rod, whose raw materials include, by mass percentage, 30% ferrochrome, 10% ferromolybdenum, 7% tungsten powder; 4% titanium carbide, 5% ferroboron; 3.5% graphite powder, 1.5% nano-silicon carbide; 13% rutile, 10% fluorite; and 7% potassium water glass.

[0095] The preparation method of the high-strength wear-resistant welding rod comprises the following steps:

[0096] S1. Preparation of coating slurry: 30 g of ferrochrome, 10 g of ferromolybdenum, 7 g of tungsten powder, 4 g of titanium carbide, 5 g of ferroboron, 13 g of rutile, and 10 g of fluorite were mixed to obtain a mixture, and the mixture was ball-milled to a particle size of 50 μm. 3.5 g of graphite powder, 1.5 g of nano-silicon carbide, and 7 g of potassium water glass were added and mixed to form a slurry. The viscosity of the slurry after mixing was 350 mPa·s.

[0097] S2. Welding core coating: 1 g of aluminum powder was added to the slurry obtained in step S1, and the surface of the welding core was coated to form an inner layer with a coating thickness of 0.6 mm. The coated inner layer of the welding core was pre-dried at 80°C for 1 hour, and the remaining slurry was coated on the inner surface of the welding core to form an outer layer with a coating thickness of 4.8 mm.

[0098] S3. The coated welding core in S2 is dried in the following first and second stages respectively: the first stage: drying at 80-100°C for 2 hours to remove free water; the second stage: drying at 250-280°C for 1.5 hours to reduce bound water and residual hydrogen, and finally a high-strength wear-resistant welding rod is produced.

[0099] Comparative Example 4

[0100] A high-strength wear-resistant welding rod, whose raw materials include, by mass percentage, 30% ferrochromium, 10% ferromolybdenum, 7% tungsten powder; 4% titanium carbide, 5% ferroboron; 3.5% graphite powder, 1.5% nano-silicon carbide; 13% rutile, 10% fluorite; 2% rare earth ferrocerium alloy, and 7% potassium water glass.

[0101] The preparation method of the high-strength wear-resistant welding rod comprises the following steps:

[0102] S1. Preparation of coating slurry: 30 g of ferrochrome, 10 g of ferromolybdenum, 7 g of tungsten powder, 4 g of titanium carbide, 5 g of ferroboron, 13 g of rutile, and 10 g of fluorite are mixed to obtain a mixture. The mixture is ball-milled to a particle size of 50 μm. 3.5 g of graphite powder and 1.5 g of nano-silicon carbide are added, and the mixture is mixed with 2 g of rare earth ferrocerium alloy and 7 g of potassium water glass to form a slurry. The viscosity of the slurry after mixing is 350 mPa·s.

[0103] S2. Welding core coating: 1 g of aluminum powder was added to the slurry obtained in step S1, and the surface of the welding core was coated to form a surface layer with a thickness of 5.4 mm. The coated surface layer of the welding core was pre-dried at 80° C. for 1 h.

[0104] S3. The coated welding core in S2 is dried in the following first and second stages respectively: the first stage: drying at 80-100°C for 2 hours to remove free water; the second stage: drying at 250-280°C for 1.5 hours to reduce bound water and residual hydrogen, and finally a high-strength wear-resistant welding rod is produced.

[0105] 3. Performance Testing

[0106] The welding rods prepared in Example 1-3 and Comparative 1-4 were tested for hardness-toughness, high temperature hardness, hydrogen-induced cracking rate and bonding strength according to the following methods.

[0107] 1. Hardness and toughness

[0108] S1. Sample preparation: Dimensions of weld overlay specimen: 10×10×55mm (V-notch processing shall be in accordance with GB / T 229-2020 standard, and the surface shall be polished to Ra≤0.8μm to eliminate the influence of work hardening;

[0109] S1-S2, Hardness test: Use Rockwell hardness tester (ASTM E18 standard): select 5 points evenly on the surface of the weld overlay layer for measurement, and take the mean ± standard deviation; test load: 150kgf, diamond indenter dwell time 15s.

[0110] S1-S3, Impact toughness test: Charpy impact testing machine (-20℃ to room temperature): Cool to the target temperature with liquid nitrogen, keep warm for 30 minutes and then impact, impact energy range: 0-300J, test speed 5m / s.

[0111] 2. High temperature hardness test

[0112] The temperature of the vacuum heating furnace was raised to 600±10℃ and kept at this temperature for 1 hour (referring to ISO 14577 standard); the surface hardness was measured with a high-temperature indenter (load 500gf), and the data stability was retested after cooling.

[0113] 3. Hydrogen-induced cracking rate

[0114] The welding specimens (100×50×10 mm) were treated with constant humidity (RH≥85%) for 48 h, and the number of cracks per unit area was counted under a metallographic microscope (200×) to calculate the crack rate.

[0115] 4. Drug skin bonding strength test

[0116] Lap joint tensile test (ASTM D1002): specimen size: 25 × 100 mm, lap length 12.5 mm, tensile rate 2 mm / min, record the maximum breaking load.

[0117] Table 1: Performance test results of various embodiments and comparative examples

[0118]

[0119] As can be seen from Table 1, the high-strength wear-resistant welding rod prepared in Example 1 of the present invention has a hardness HRC of 62.5, which is very excellent. However, the hardness HRC of the welding rod in Comparative Example 1 (no titanium carbide added) dropped significantly to 45.1. Moreover, the toughness of Example 1 reached 27.5J, while the toughness of Comparative Example 1 was only 18.9J. In addition, the hydrogen-induced cracking rate of the high-strength wear-resistant welding rod prepared in Example 1 was only 0.4%, while the hydrogen-induced cracking rate of Comparative Example 3 (no rare earth ferrocerium alloy added) was 2.5%. When the hydrogen-induced cracking rate is high, the increase in the hydrogen-induced cracking rate indicates that hydrogen (such as ambient moisture and weld material moisture absorption) intrudes into the molten pool in large quantities during welding and is not escaped through effective process means (such as drying and rare earth purification). Finally, the coating bonding strength of the high-strength wear-resistant welding rod prepared in Example 1 of the present invention reached 15.3MPa, while that of Comparative Example 4 (using a single-layer coating) was only 8.8MPa, which was not expected before the experiment.

[0120] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A high-strength wear-resistant welding rod, comprising a welding core and a coating covering the surface of the welding core, characterized in that: The welding core is H08E low carbon steel welding wire, and the coating includes: Main alloy components: 28-32% ferrochromium, 9-11% ferromolybdenum, 6-8% tungsten powder; 3-5% titanium carbide, 4-6% ferroboron; Carbide regulator: graphite powder 3-4%, nano silicon carbide 1-2%; Slag-forming agent: rutile 12-14%, fluorite 9-11%; Auxiliary additives: rare earth ferrocerium alloy 1.5-2.5%, potassium water glass 6-8%.

2. The welding rod according to claim 1, wherein The medicine coating comprises: Main alloy components: 28% ferrochromium, 9% ferromolybdenum, 6% tungsten powder; 3% titanium carbide, 4% ferroboron; Carbide regulator: graphite powder 3%, nano silicon carbide 1%; Slag-forming agent: rutile 12%, fluorite 9%; Auxiliary additives: rare earth ferrocerium alloy 1.5%, potassium water glass 6%.

3. The welding rod according to claim 1, wherein The medicine coating comprises: Main alloy components: 32% ferrochromium, 11% ferromolybdenum, 8% tungsten powder; 5% titanium carbide, 6% ferroboron; Carbide regulator: graphite powder 4%, nano silicon carbide 2%; Slag-forming agent: rutile 14%, fluorite 11%; Auxiliary additives: rare earth ferrocerium alloy 2.5%, potassium water glass 8%.

4. The welding rod according to claim 1, wherein The mass percentage of the components of the H08E low carbon steel welding wire is C≤0.08%, Mn: 0.4-0.65%, Si≤0.03%, S≤0.02%, P≤0.02%, Cr≤0.2%, Ni≤0.3%, Cu≤0.35%, and the balance is iron.

5. The welding rod according to claim 1, wherein The diameter of the welding core is 3.2-4.0 mm.

6. A method for preparing a welding rod according to any one of claims 1 to 5, characterized in that the steps include: S1. Preparation of coating slurry: The main alloy component and the slag-forming agent are mixed to obtain a mixture, the mixture is ball-milled into particles, the carbide regulator is added, and the mixture is mixed with the auxiliary additive to form a slurry; S2, welding core coating: 1% aluminum powder is added to the slurry processed in step S1, and the surface of the welding core is coated with aluminum powder to form an inner layer. The coated inner layer is pre-dried at 80°C for 1 hour, and the remaining slurry is coated on the inner layer to form an outer layer of the welding core; S3, drying the welding core after coating in S2 according to the following first and second stages: The first stage: drying at 80-100℃ for 2h to remove free water; The second stage: drying at 250-280℃ for 1.5h to reduce bound water and hydrogen residue.

7. The method according to claim 6, wherein: In step S1 , the particle size of the particles is ≤50 μm, and the slurry viscosity is 300-400 mPa·s.

8. The method according to claim 6, wherein: In step S2, the coating thickness of the inner layer is 0.5-0.8 mm, and the coating thickness of the outer layer of the welding core is 1.3-1.5 times the diameter of the welding core.

9. The use of the high-strength wear-resistant welding rod according to any one of claims 1 to 5, characterized in that: The welding rod is used in surface strengthening of a mining machinery crushing hammer head.

10. The use according to claim 9, wherein: The welding process includes: sandblasting or angle grinder processing to make the surface roughness of the hammer head reach Ra≤12.5μm, preheating the hammer head surface to 200-250℃, the layer temperature is ≤150℃, the welding current is 120A-180A, and the welding method adopts horizontal fish scale overlap.

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