Alloy material for surfacing welding, surfacing welding method and mechanical parts

Abstract

The present invention belongs to the field of surfacing welding, and specifically relates to an alloy material for surfacing welding, a surfacing welding method, and a mechanical part. The chemical composition of the surfacing welding alloy material is, by weight percentage, C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, and the balance is iron. By combining a C content of 0.7wt% to 1.4wt%, a W content of 1.5wt% to 3.0wt%, and a V content of 1.5wt% to 3.0wt%, sufficient tungsten carbide and vanadium carbide hard phases in a finely dispersed distribution are provided while simultaneously refining the grains. This improves the hardness and wear resistance of the surfacing alloy layer, and suppresses low-temperature temper brittleness, thereby preventing the continuous precipitation of carbides between grains and the thermal expansion difference between grains from synergistically generating strong internal stress, suppressing the generation and expansion of cracks, and improving the corrosion resistance of the surfacing alloy layer.

Description

Technical Field

[0001] The present invention belongs to the field of surfacing welding, and in particular relates to an alloy material for surfacing welding, a surfacing welding method and mechanical parts. Background Art

[0002] The manufacturing process of rubber products typically involves mixing and extruding granular raw rubber into condensed rubber in the mixing chamber of an internal mixer through the stirring and extrusion of the rotor. During this process, all parts in contact with the rubber compound in the mixing chamber undergo a progression from abrasive wear to adhesive wear. The addition of carbon black, quartz sand, and metal oxides to the rubber compound during refining further increases the degree of wear and oxidation corrosion. Under the dual effects of wear and corrosion, the workpiece will quickly fail. To extend the service life of the workpiece, internal mixer manufacturers generally adopt methods such as adding wear-resistant and corrosion-resistant coatings to the workpiece surface, such as hard alloy cladding and hard chrome electroplating. Hard alloy cladding is the most commonly used method due to its ease of operation and high production efficiency.

[0003] The types of hard alloys for surfacing can be roughly divided into three categories: cobalt-based welding materials, nickel-based welding materials, and iron-based welding materials. The first two welding materials have good wear resistance, fewer cracks in the surfacing alloy layer, and good corrosion resistance. However, the cost of these two welding materials is very high, more than 5 to 10 times that of iron-based welding materials, and it is difficult to promote their use in large quantities. Currently, iron-based high-chromium cast iron and martensite-based Cr13 welding materials are still commonly used. The former material has excellent wear resistance, but its corrosion resistance is limited due to the presence of cracks. As tire technology advances, the latter material can no longer meet the wear requirements of some existing tire rubber compounds, and its service life has been reduced from more than 5 years to about 3 years.

[0004] Internal mixer workpieces are built with hard alloy layers to enhance wear resistance and corrosion resistance. However, due to the curved surface of internal mixer workpieces, cracks are easily generated during cooling during welding. Furthermore, cracks are more likely to form when welding multiple layers or when welding again after cooling a welded area, impacting the wear resistance and strength of the internal mixer workpiece. Furthermore, the high cost of alloys containing elements such as Mo, Co, Ni, and Nb also hinders the application of high-performance hardfacing alloys.

[0005] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or public known technology. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of the existing technology that the surfacing alloy layer formed by the surfacing alloy material for surfacing cannot take into account wear resistance, few cracks, corrosion resistance and economy, which affects the life of mechanical parts such as internal mixers. The present invention provides an alloy material for surfacing, a surfacing method and mechanical parts. The surfacing alloy layer formed by the surfacing alloy material for surfacing has excellent wear resistance, few cracks, and excellent corrosion resistance. In particular, it is more suitable for curved surface welding of internal mixers, etc. The possibility of cracks caused by heat during multi-layer welding is reduced, and the cost is low.

[0007] In order to achieve the above-mentioned objectives, in a first aspect, the present invention provides an alloy material for surfacing welding, whose chemical composition is, in weight percentage, C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, and the balance is iron.

[0008] In some preferred embodiments, the chemical composition of the surfacing alloy material satisfies 3.5%≤W+V≤6% in weight percentage.

[0009] In some preferred embodiments, the chemical composition of the cladding alloy material satisfies a V / W ratio of 0.7 to 0.9 in weight percentage.

[0010] In some preferred embodiments, the surfacing alloy layer formed by layered surfacing of the surfacing alloy material has a dispersed distribution of carbide hard phases, and the thermal expansion coefficient of the carbide hard phases is close to that of iron, thereby suppressing the generation of stress between the substrate and the carbide hard phases.

[0011] Preferably, the carbide hard phase mainly includes tungsten carbide and vanadium carbide.

[0012] Preferably, the distribution density of the carbide hard phase is 1500 / mm 2 ~40000 / mm 2 , the equivalent circle diameter of the carbide hard phase is less than 1 μm.

[0013] In a second aspect, the present invention provides an alloy material for surfacing welding, whose chemical composition, in weight percentage, is C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, rare earth elements: 0.1-0.15, and the balance is iron.

[0014] In some preferred embodiments, the chemical composition of the surfacing alloy material satisfies 3.5%≤W+V≤6% in weight percentage.

[0015] In some preferred embodiments, the chemical composition of the cladding alloy material satisfies a V / W ratio of 0.7 to 0.9 in weight percentage.

[0016] In some preferred embodiments, the surfacing alloy layer formed by layered surfacing of the surfacing alloy material has a dispersed distribution of carbide hard phases, and the thermal expansion coefficient of the carbide hard phases is close to that of iron, thereby suppressing the generation of stress between the substrate and the carbide hard phases.

[0017] Preferably, the carbide hard phase mainly includes tungsten carbide and vanadium carbide.

[0018] Preferably, the distribution density of the carbide hard phase is 1500 / mm 2 ~40000 / mm 2 , the equivalent circle diameter of the carbide hard phase is less than 1 μm.

[0019] In a third aspect, the present invention provides a surfacing method, comprising: preheating the portion to be welded of a workpiece to 150°C to 250°C, performing layered surfacing with the surfacing alloy material described in the first aspect and / or the surfacing alloy material described in the second aspect, wherein the interlayer temperature of the layered surfacing is 200°C to 300°C, and performing a tempering treatment at a temperature of 540°C to 600°C after the layered surfacing.

[0020] In a fourth aspect, the present invention provides a mechanical part having a surfacing alloy layer on the surface of a base steel material, wherein the chemical composition of the surfacing alloy layer is, by weight percentage, C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, and the balance is iron;

[0021] Alternatively, the chemical composition of the surfacing alloy layer is, by weight percentage, C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, rare earth elements: 0.1-0.15, and the balance is iron.

[0022] The present invention adopts a high-carbon silicon, tungsten, and vanadium composition design by combining a carbon content of 0.7wt% to 1.4wt%, a W content of 1.5wt% to 3.0wt%, a V content of 1.5wt% to 3.0wt%, and a Si content of 0.9wt% to 1.3wt%, thereby eliminating expensive elements such as Mo, Co, Ni, and Nb. This meets the requirements for wear resistance, corrosion resistance, and reduced cracking of internal mixer parts, ensuring high hardness while improving wear resistance and reducing costs. In particular, while maintaining high wear resistance, high strength, and strong corrosion resistance during long-term use, the present invention is less likely to crack during long-term use and during welding. In particular, during multi-layer welding on curved surfaces of internal mixer parts or during re-welding after cooling of welded parts, the possibility of cracking due to heat can be greatly reduced, thereby improving the welding performance of the welding material.

[0023] Specifically: high carbon is combined with high tungsten and high vanadium to provide a sufficient amount of tungsten carbide and vanadium carbide hard phases with small dispersion distribution while refining the grains. During multiple welding, the carbides of W and V can be tempered at the welding temperature (200-300 degrees). During the tempering process, more tungsten carbide and vanadium carbide with small dispersion distribution are precipitated, which can improve the hardness and wear resistance of the surfacing alloy layer, and can inhibit the low-temperature tempering brittleness phenomenon, reduce the continuous precipitation of carbides between grains and the thermal expansion difference of adjacent grains to produce strong internal stress. Due to the high thermal expansion coefficient of tungsten carbide and vanadium carbide, the hardness of the surfacing alloy layer is improved. The thermal expansion coefficient is closer to that of iron, reducing the possibility of stress generation between the substrate and the hard phase, thereby reducing the thermal effects of multiple heating on the weld during welding, especially during multiple welding processes (such as cracking), inhibiting the generation and expansion of cracks, and improving the corrosion resistance of the surfacing alloy layer. The Cr content is 12wt% to 16wt%, which improves the hardness and wear resistance of the surfacing alloy layer. The high Si content, specifically 0.9wt% to 1.3wt%, improves the tensile toughness of the surfacing alloy layer, avoids the generation and expansion of cracks, and improves the corrosion resistance of the surfacing alloy layer. In existing surfacing alloy materials, for example, Mo is used to improve the hardness and wear resistance of the surfacing alloy layer, and Ni is used to improve the corrosion resistance of the surfacing alloy layer. However, the addition of these elements to the welding material is expensive. The surfacing alloy material of the present invention, through the above synergistic effect, can still improve the hardness and wear resistance of the surfacing alloy layer, inhibit the generation of cracks in the surfacing alloy layer, and improve the corrosion resistance of the surfacing alloy layer without the need to add high-priced elements such as Mo, Co, Ni, and Nb, and can greatly reduce the cost of the surfacing alloy material.

[0024] The alloy material for surfacing welding of the present invention contains rare earth, and the rare earth content is 0.1wt% to 0.15wt%, which can further promote grain refinement, so that the stress between the grains generated by thermal expansion during welding is small and dispersed, avoiding stress concentration, and avoiding the continuous precipitation of carbides between the grains and the thermal expansion difference between adjacent grains to generate strong internal stress, thereby further suppressing the generation and expansion of cracks in the surfacing alloy layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is the first scanning electron microscope photograph of the surfacing alloy layer of Example 1.

[0027] Figure 2 This is the second scanning electron microscope photograph of the surfacing alloy layer of Example 1.

[0028] Figure 3 This is the first macroscopic photograph of the surfacing alloy layer of Example 5.

[0029] Figure 4 This is a second macroscopic photograph of the surfacing alloy layer of Example 5.

[0030] Figure 5 This is a macroscopic photograph of the surfacing alloy layer of Example 1.

[0031] Figure 6 This is a macroscopic photograph of the surfacing alloy layer of Example 4.

[0032] Figure 7 This is the first macroscopic photograph of the surfacing alloy layer of Comparative Example 1.

[0033] Figure 8 This is a second macroscopic photograph of the surfacing alloy layer of Comparative Example 1. DETAILED DESCRIPTION

[0034] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0035] The inventors of the present invention have found that in the prior art, the surfacing alloy layer formed by the surfacing alloy material cannot take into account the wear resistance, few cracks, corrosion resistance and economy, which affects the life of mechanical parts such as internal mixers.

[0036] In this regard, in a first aspect, the present invention provides an alloy material for surfacing welding, whose chemical composition is, in weight percentage, C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, and the balance is iron.

[0037] The alloy material for surfacing welding of the present invention has a C content of 0.7 wt% to 1.4 wt%, a W content of 1.5 wt% to 3.0 wt%, and a V content of 1.5 wt% to 3.0 wt%.

[0038] W is an element that easily forms carbides. High W content is conducive to forming a large number of precipitated carbides with high carbon, which has a good effect on improving wear resistance. High C content and high W content can provide sufficient carbide hard phase, increase the wear-resistant phase content and thus improve wear resistance. However, W is easily dissolved in the γ phase in the austenite stage. When austenite is transformed into martensite, due to the high W content, W is prone to aggregation and precipitation in the form of flakes, thereby affecting wear resistance and easily generating cracks. Adding a higher V content can inhibit W aggregation and precipitation in the form of flakes, making tungsten carbide and carbide Vanadium is distributed in a micro-dispersed manner, thereby improving wear resistance. Tungsten carbide and vanadium carbide are distributed in a micro-dispersed manner in the martensite matrix, and are solid-dissolved in the martensite with almost no diffusion or aggregation. In addition to improving wear resistance, continuous precipitation of carbides between grains can be reduced, thereby avoiding the strong internal stress generated by the continuous precipitation of carbides between grains and the thermal expansion difference between adjacent grains, thereby improving high-temperature endurance (small heat effect), reducing the thermal expansion coefficient, and making the martensite expand less during welding, that is, the mutual pulling force between grains is small, thereby inhibiting the generation and expansion of cracks. The invention is used When the alloy material is used for layered surfacing welding, when the next layer is welded, at the welding temperature, the previous weld layer will be affected by the heat in the interlayer temperature range, which is similar to the low-temperature tempering temperature. During the heat-affected process, more tungsten carbide and vanadium carbide with small dispersion distribution can be precipitated. In particular, during the heat-affected process, part of the retained austenite is transformed into martensite, and the tungsten carbide and vanadium carbide in the martensite and retained austenite are more finely dispersed. On the basis of maintaining the toughness of part of the retained austenite to reduce the generation of cracks, the more fine dispersion of tungsten carbide and vanadium carbide also improves its wear resistance. Thus, the strength, wear resistance, and corrosion resistance of the cladding alloy layer can be improved, and cracks can be reduced. However, low-temperature tempering is prone to low-temperature temper brittleness, that is, when martensite decomposes, intermittent thin shell-like carbides are precipitated along the interface of martensite strips or sheets, thereby reducing the fracture strength of the grain boundaries and making the grain boundaries a path for crack propagation. The present invention has a W content of 1.5wt% to 3.0wt% and a V content of 1.5wt% to 3.0wt%, so that the tungsten carbide and vanadium carbide are both distributed in a micro-dispersed manner, and the low-temperature temper brittleness phenomenon can be suppressed, thereby controlling the generation and expansion of cracks. The smaller the grains, the smaller and more dispersed the mutual thermal expansion pulling force during welding is, and it is not easy to concentrate. The W content of the present invention is 1.5wt% to 3.0wt%, and the V content is 1.5wt% to 3.0wt%. It can also refine the grains, making the stress between the grains generated by thermal expansion during welding small and dispersed, avoiding stress concentration, reducing crack sensitivity, and controlling the generation and expansion of cracks.The carbide hard phase of the present invention is mainly tungsten carbide and vanadium carbide, without molybdenum carbide, etc. During layered surfacing, the welding point is heated multiple times, and the tungsten carbide, vanadium carbide and iron matrix expand due to heat. Since the thermal expansion coefficients of tungsten carbide and vanadium carbide are close to those of iron, the stress generated between the matrix and tungsten carbide or vanadium carbide can be suppressed, and the possibility of forming a core for crack generation is reduced, which can further suppress the generation and expansion of cracks.

[0039] The Cr content of the alloy material for surfacing welding of the present invention is 12wt% to 16wt%. If the Cr element is less than 12wt%, the hardness and wear resistance of the deposited metal will be reduced. If the Cr element exceeds 16wt%, the alloy has a tendency to austenitize, which will also cause the hardness of the surfacing alloy layer to decrease, affecting the wear resistance.

[0040] The Si content of the alloy material for surfacing welding of the present invention is 0.9wt% to 1.3wt%, which can improve the tensile toughness of the weld layer and avoid the generation and expansion of cracks. Since it does not contain elements such as Mo, Co, Ni, and Nb, the formation of iron-silicon oxides can be controlled, and the problem of a high Si content, specifically above 0.9wt%, which leads to a significant increase in iron-silicon oxides and thus the generation and expansion of cracks, will not occur.

[0041] The present invention adopts a high-carbon silicon, tungsten, and vanadium composition design by combining a carbon content of 0.7wt% to 1.4wt%, a W content of 1.5wt% to 3.0wt%, a V content of 1.5wt% to 3.0wt%, and a Si content of 0.9wt% to 1.3wt%, thereby eliminating expensive elements such as Mo, Co, Ni, and Nb. This meets the requirements for wear resistance, corrosion resistance, and reduced cracking of internal mixer parts, ensuring high hardness while improving wear resistance and reducing costs. In particular, while maintaining high wear resistance, high strength, and strong corrosion resistance during long-term use, the present invention is less likely to crack during long-term use and during welding. In particular, during multi-layer welding on curved surfaces of internal mixer parts or during re-welding after cooling of welded parts, the possibility of cracking due to heat is greatly reduced, thereby improving the welding performance of the welding material.

[0042] Specifically: high carbon is combined with high tungsten and high vanadium to provide a sufficient amount of tungsten carbide and vanadium carbide hard phases with small dispersion distribution while refining the grains. During multiple welding, the carbides of W and V can be tempered at the welding temperature (200-300 degrees). During the tempering process, more tungsten carbide and vanadium carbide with small dispersion distribution are precipitated, which can improve the hardness and wear resistance of the cladding alloy layer, and can inhibit the low-temperature tempering brittleness phenomenon and reduce the continuous precipitation of carbides between grains. The thermal expansion difference between adjacent grains produces strong internal stress. Due to the thermal expansion coefficient of tungsten carbide and vanadium carbide, the tungsten carbide and vanadium carbide are precipitated. The thermal expansion coefficient of the cladding alloy is closer to that of iron, reducing the possibility of stress generation between iron and inclusions, thereby reducing the thermal effects of multiple heating on the weld during welding, especially during multiple welding processes (such as cracking), thereby suppressing the generation and expansion of cracks and improving the corrosion resistance of the cladding alloy layer. The Cr content is 12wt% to 16wt%, which improves the hardness and wear resistance of the cladding alloy layer. The high Si content, specifically 0.9wt% to 1.3wt%, improves the tensile toughness of the cladding alloy layer, avoids the generation and expansion of cracks, and improves the corrosion resistance of the cladding alloy layer. In existing cladding alloy materials, for example, Mo is used to improve the hardness and wear resistance of the cladding alloy layer, and Ni is used to improve the corrosion resistance of the cladding alloy layer. However, the addition of these elements to the welding material is expensive. The cladding alloy material of the present invention, through the above synergistic effect, can still improve the hardness and wear resistance of the cladding alloy layer, suppress the generation of cracks in the cladding alloy layer, and improve the corrosion resistance of the cladding alloy layer without the need to add high-priced elements such as Mo, Co, Ni, and Nb, thereby significantly reducing the cost of the cladding alloy material.

[0043] The cemented carbide of the present invention does not contain elements such as Mo, Co, Ni, and Nb. Even if the C content is relatively high, exceeding 0.7 wt%, it will not cause grain boundary segregation, and the thermal expansion difference between the grain boundary and adjacent grains will not cause the grain boundary to withstand tensile force, thereby promoting the generation and expansion of cracks. If the cemented carbide of the present invention contains elements such as Mo, Co, Ni, and Nb, it is easy to cause grain boundary segregation. During welding, the thermal expansion between the grain boundary and the adjacent grains is different, which promotes the formation of oxides between Fe and Si. The Fe and Si oxides at the grain boundary and the grain boundary segregation phase cooperate to make the grain boundary's ability to withstand tensile force worse, thereby promoting the generation and expansion of cracks. It is easy to precipitate W, V, Mo, Co, Ni, Nb and C at the grain boundary to form complex carbides, leading to crack expansion. The elements added by the present invention try to make tungsten carbide and vanadium carbide dispersed and precipitated inside the grains, reducing the affinity of Ni, Co and impurity elements (P, Sb, Sn, Mn, As), promoting the segregation of impurity elements at the grain boundary, and interacting with high carbon to easily produce large carbides, resulting in increased risk of cracks. Mo and carbon form molybdenum carbide inclusions with larger sizes. The thermal expansion coefficient of molybdenum carbide is 1.5×10-6 / K, and the thermal expansion coefficient differs significantly from that of iron, leading to a greater risk of cracking. This is especially true during multiple welding processes, where the weld is heated repeatedly and the risk of cracking increases. Eliminating the addition of Mo significantly reduces this risk. Nb is expensive and reacts readily with elements like nitrogen. Eliminating the addition of Nb reduces both costs and the risk of cracking.

[0044] The surfacing alloy layer of the present invention has very few surface cracks and can be used as a transition layer hard alloy when manufacturing super-strong wear-resistant parts. The surfacing alloy material of the present invention is preferably used in the form of a flux-cored wire.

[0045] In the present invention, the C content is, for example, 0.7wt%, 0.8wt%, 1.1wt%, 1.3wt% and 1.4wt%, the Si content is, for example, 0.9wt%, 1wt%, 1.1wt%, 1.2wt% and 1.3wt%, the Mn content is, for example, 1.5wt%, 1.7wt%, 1.9wt%, 2.2wt% and 2.3wt%, the Cr content is, for example, 12wt%, 13wt%, 14wt%, 15wt% and 16wt%, the W content is, for example, 1.5wt%, 1.7wt%, 1.9wt%, 2.1wt%, 2.3wt%, 2.6wt%, 2.7wt%, 2.9wt% and 3wt%, and the V content is, for example, 1.5wt%, 1.7wt%, 1.9wt%, 2.1wt%, 2.3wt%, 2.6wt%, 2.7wt%, 2.9wt% and 3wt%.

[0046] In some preferred embodiments, the chemical composition of the surfacing alloy material satisfies 3.5% ≤ W + V ≤ 6% by weight. This preferred solution is more conducive to increasing the number of carbide hard phase particles formed and reducing the equivalent circular diameter of the carbide hard phase particles, providing sufficient finely dispersed tungsten carbide and vanadium carbide hard phases in the surfacing alloy layer, refining the grains, improving the wear resistance of the surfacing alloy layer, and preventing the continuous precipitation of carbides between grains and the thermal expansion differences between adjacent grains from synergistically generating strong internal stress, inhibiting the initiation and expansion of cracks, and improving the corrosion resistance of the surfacing alloy layer. Without adding expensive components such as Mo and Ni, the surfacing alloy layer can reduce cracks and ensure the wear and corrosion resistance of the surfacing alloy layer. Examples of W + V contents include 3.5%, 4%, 4.5%, 5%, 5.5%, and 6%.

[0047] In some preferred embodiments, the chemical composition of the alloy material for hardfacing is expressed in weight percentage, with a V / W ratio of 0.7 to 0.9. W is more likely to form carbides, while V can inhibit W from aggregating and precipitating in the form of flakes when austenite transforms into martensite. At the same time, V can further refine the grains, making the stress between grains generated by thermal expansion during welding small and dispersed. V and W both play a role in forming carbide hard phases, but each has a different and more superior role. Under this preferred embodiment, by limiting V / W to 0.7 to 0.9, it is more conducive to forming dispersed and evenly distributed tiny tungsten carbide and vanadium carbide hard phases in the hardfacing alloy layer while refining the grains, thereby improving the wear resistance of the hardfacing alloy layer, avoiding the continuous precipitation of carbides between grains and the thermal expansion difference between adjacent grains to synergistically generate strong internal stress, inhibiting the generation and expansion of cracks, and improving the corrosion resistance of the hardfacing alloy layer. Without adding high-priced components such as Mo and Ni, the performance of the hardfacing alloy layer is guaranteed. V / W is, for example, 0.75, 0.8, 0.85, and 0.9.

[0048] In some preferred embodiments, the hardfacing alloy layer formed by layered hardfacing of the hardfacing alloy material contains a dispersed carbide hard phase. The thermal expansion coefficient of the carbide hard phase is close to that of iron, thereby suppressing stress between the substrate and the carbide hard phase. This preferred embodiment further improves wear resistance and reduces cracking.

[0049] Preferably, the carbide hard phase mainly includes tungsten carbide and vanadium carbide. Under this preferred embodiment, it is more conducive to improving wear resistance and reducing cracks.

[0050] Preferably, the surfacing alloy layer is dispersed with carbide hard phase, and the distribution density of the carbide hard phase is 1500 / mm 2 ~40000 / mm 2 , the equivalent circle diameter of the carbide hard phase is less than 1 μm. Under this preferred embodiment, the distribution density of the carbide hard phase is not less than 1500 / mm 2 , which is more conducive to improving the wear resistance of the surfacing alloy layer, and the distribution density is not more than 40000 / mm 2 , which is more conducive to reducing the crack sensitivity of the cladding alloy layer and inhibiting the generation and expansion of cracks. The equivalent circle diameter of the carbide hard phase is less than 1μm, which is more conducive to avoiding the continuous precipitation of carbides between grains and the thermal expansion difference between adjacent grains to produce strong internal stress, thereby inhibiting the generation and expansion of cracks. The distribution density of the carbide hard phase is further preferably 1500 / mm 2 ~35000 / mm 2 , and further preferably 2000 / mm 2 ~33000 / mm 2 , and further preferably 3000 / mm 2~30000 / mm 2 , and further preferably 5000 / mm 2 ~25000 / mm 2 , and further preferably 8000 / mm 2 ~22000 / mm 2 , and further preferably 10000 / mm 2 ~20000 / mm 2 The equivalent circle diameter of the carbide hard phase is further preferably less than 0.8 μm, and further preferably less than 0.5 μm.

[0051] In a second aspect, the present invention provides an alloy material for surfacing welding, whose chemical composition, in weight percentage, is C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, rare earth elements: 0.1-0.15, and the balance is iron.

[0052] The present invention adopts a high-carbon silicon, tungsten, and vanadium composition design by combining a carbon content of 0.7wt% to 1.4wt%, a W content of 1.5wt% to 3.0wt%, a V content of 1.5wt% to 3.0wt%, and a Si content of 0.9wt% to 1.3wt%, thereby eliminating expensive elements such as Mo, Co, Ni, and Nb. This meets the requirements for wear resistance, corrosion resistance, and crack resistance of internal mixer parts, ensures high hardness, improves wear resistance, and reduces costs. In particular, while maintaining high wear resistance, high strength, and strong corrosion resistance during long-term use, the present invention is less likely to crack during long-term use and during welding. In particular, during multi-layer welding on curved surfaces of internal mixer parts or during re-welding after a welded part has cooled, the possibility of cracking due to heat is greatly reduced, thereby improving the welding performance of the welding material.

[0053] Specifically: high carbon is combined with high tungsten and high vanadium to provide a sufficient amount of tungsten carbide and vanadium carbide hard phases with a small dispersed distribution while refining the grains. During multiple welding, the carbides of W and V can be tempered at the welding temperature (200-300 degrees). During the tempering process, more tungsten carbide and vanadium carbide with a small dispersed distribution are precipitated, which can improve the hardness and wear resistance of the surfacing alloy layer, and can inhibit the low-temperature tempering brittleness phenomenon, reduce the continuous precipitation of carbides between grains and the thermal expansion difference between adjacent grains to produce strong internal stress. Since the thermal expansion coefficients of tungsten carbide and vanadium carbide are closer to the thermal expansion coefficient of iron, the possibility of stress generation between iron and the hard phase is reduced, thereby reducing the thermal impact of multiple heating on the weld during welding, especially in multiple welding processes (such as cracks), thereby inhibiting the generation and expansion of cracks and improving the corrosion resistance of the surfacing alloy layer. In existing hardfacing alloy materials, for example, Mo is used to improve the hardness and wear resistance of the hardfacing alloy layer, while Ni is used to improve the corrosion resistance of the hardfacing alloy layer. However, the addition of these elements to the welding material is costly. The hardfacing alloy material of the present invention, through the aforementioned synergistic effect, can improve the hardness and wear resistance of the hardfacing alloy layer, inhibit the occurrence of cracks in the hardfacing alloy layer, and improve the corrosion resistance of the hardfacing alloy layer without adding expensive elements such as Mo, Co, Ni, and Nb, thereby significantly reducing the cost of the hardfacing alloy material.

[0054] The present invention further promotes grain refinement by having a rare earth content of 0.1wt% to 0.15wt%, so that the stress between the grains generated by thermal expansion during welding is small and dispersed, thereby avoiding stress concentration and preventing the continuous precipitation of carbides between the grains from cooperating with the thermal expansion difference of adjacent grains to generate strong internal stress, thereby further suppressing the generation and expansion of cracks in the surfacing alloy layer, further improving the dispersion effect of W and V, dispersion strengthening, and improving the wear resistance of the surfacing alloy layer; by having a Cr content of 12wt% to 16wt%, the hardness and wear resistance of the surfacing alloy layer are improved; by having a high Si content, specifically a Si content of 0.9wt% to 1.3wt%, the tensile toughness of the surfacing alloy layer is improved, the generation and expansion of cracks are avoided, and the corrosion resistance of the surfacing alloy layer is improved.

[0055] The C content of the present invention is, for example, 0.7wt%, 0.8wt%, 1.1wt%, 1.3wt% and 1.4wt%, the Si content is, for example, 0.9wt%, 1wt%, 1.1wt%, 1.2wt% and 1.3wt%, the Mn content is, for example, 1.5wt%, 1.7wt%, 1.9wt%, 2.2wt%, 2.3wt% and 2.5wt%, the Cr content is, for example, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, and the W content is, for example, 1.5 wt%, 1.7wt%, 1.9wt%, 2.1wt%, 2.3wt%, 2.6wt%, 2.7wt%, 2.9wt% and 3wt%, the V content is, for example, 1.5wt%, 1.7wt%, 1.9wt%, 2.1wt%, 2.3wt%, 2.6wt%, 2.7wt%, 2.9wt% and 3wt%, and the rare earth element content is, for example, 0.1wt%, 0.11wt%, 0.12wt%, 0.13wt%, 0.14wt% and 0.15wt%.

[0056] In some preferred embodiments, the chemical composition of the hardfacing alloy material, measured in weight percentage, is 3.5% ≤ W + V ≤ 6% and / or V / W is 0.7-0.9. In this preferred embodiment, 3.5% ≤ W + V ≤ 6% is more conducive to providing sufficient finely dispersed tungsten carbide and vanadium carbide hard phases in the hardfacing alloy layer, refining the grains, improving the wear resistance of the hardfacing alloy layer, and preventing the continuous precipitation of carbides between grains and the thermal expansion differences between adjacent grains from synergizing to generate strong internal stress, thereby inhibiting crack initiation and propagation. A V / W ratio of 0.7-0.9 is more conducive to forming finely dispersed and evenly distributed fine tungsten carbide and vanadium carbide hard phases in the hardfacing alloy layer while refining the grains, thereby improving the wear resistance of the hardfacing alloy layer, inhibiting crack initiation and propagation, and improving the corrosion resistance of the hardfacing alloy layer. Examples of W + V contents include 3.5%, 4%, 4.5%, 5%, 5.5%, and 6%. V / W is, for example, 0.7, 0.75, 0.8, 0.85, and 0.9.

[0057] In some preferred embodiments, the hardfacing alloy layer formed by layered hardfacing of the hardfacing alloy material contains a dispersed carbide hard phase. The thermal expansion coefficient of the carbide hard phase is close to that of iron, thereby suppressing stress between the substrate and the carbide hard phase. This preferred embodiment further improves wear resistance and reduces cracking.

[0058] Preferably, the carbide hard phase mainly includes tungsten carbide and vanadium carbide. Under this preferred embodiment, it is more conducive to improving wear resistance and reducing cracks.

[0059] Preferably, the surfacing alloy layer is dispersed with carbide hard phase, and the distribution density of the carbide hard phase is 1500 / mm2 ~40000 / mm 2 , the equivalent circle diameter of the carbide hard phase is less than 1 μm. Under this preferred embodiment, the distribution density of the carbide hard phase is not less than 1500 / mm 2 , which is more conducive to improving the wear resistance of the surfacing alloy layer, and the distribution density is not more than 40000 / mm 2 , which is more conducive to reducing the crack sensitivity of the cladding alloy layer and inhibiting the generation and expansion of cracks. The equivalent circle diameter of the carbide hard phase is less than 1μm, which is more conducive to avoiding the continuous precipitation of carbides between grains and the thermal expansion difference between adjacent grains to produce strong internal stress, thereby inhibiting the generation and expansion of cracks. The distribution density of the carbide hard phase is further preferably 1500 / mm 2 ~35000 / mm 2 , and further preferably 2000 / mm 2 ~33000 / mm 2 , and further preferably 3000 / mm 2 ~30000 / mm 2 , and further preferably 5000 / mm 2 ~25000 / mm 2 , and further preferably 8000 / mm 2 ~22000 / mm 2 , and further preferably 10000 / mm 2 ~20000 / mm 2 The equivalent circle diameter of the carbide hard phase is further preferably less than 0.8 μm, and further preferably less than 0.5 μm.

[0060] In a third aspect, the present invention provides a surfacing method, comprising: preheating the portion to be welded of a workpiece to 150°C to 250°C, performing layered surfacing with the surfacing alloy material described in the first aspect and / or the surfacing alloy material described in the second aspect, wherein the interlayer temperature of the layered surfacing is 200°C to 300°C, and performing a tempering treatment at a temperature of 540°C to 600°C after the layered surfacing.

[0061] According to the surfacing method of the present invention, before performing layered surfacing, the part to be welded of the workpiece is preheated to no less than 150°C, which is more conducive to reducing stress concentration and crack sensitivity, and inhibiting the generation of cracks; the temperature is no more than 250°C, which is more conducive to inhibiting austenitization, maintaining the hardness of the alloy layer stable, and increasing wear resistance; the interlayer temperature of the layered surfacing is no less than 200°C and no more than 300°C, which is more conducive to effectively inhibiting the generation of cracks; since the Cr content of the alloy material for surfacing is 12wt% to 16wt% and the V content is 1.5wt% to 3.0wt%, a tempering treatment at 540°C to 600°C is performed after the layered surfacing, which can significantly promote the secondary precipitation hardening of the carbide hard phase, and is more conducive to improving the hardness and wear resistance of the surfacing alloy layer.

[0062] The layered cladding of the present invention preferably adopts MIG welding (metal inert gas welding), which can reduce spatter and is more conducive to surface forming.

[0063] In a fourth aspect, the present invention provides a mechanical part having a surfacing alloy layer on the surface of a base steel material, wherein the chemical composition of the surfacing alloy layer is, by weight percentage, C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, and the balance is iron;

[0064] Alternatively, the chemical composition of the surfacing alloy layer is, by weight percentage, C: 0.7-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-3.0, V: 1.5-3.0, rare earth elements: 0.1-0.15, and the balance is iron.

[0065] The surfacing alloy layer on the surface of the base steel material of the present invention has a C content of 0.7wt% to 1.4wt%, a W content of 1.5wt% to 3.0wt%, a V content of 1.5wt% to 3.0wt%, a rare earth element content of 0.1wt% to 0.15wt%, a Si content of 0.9wt% to 1.3wt%, and a Cr content of 12wt% to 16wt%. Without adding expensive elements such as Mo, Co, Ni, and Nb, the surfacing alloy layer has significantly improved hardness, wear resistance, and corrosion resistance, and can significantly improve the service life of mechanical parts.

[0066] The embodiments of the present invention are described in detail below, which are exemplary and only used to explain the present invention, and are not to be construed as limiting the present invention.

[0067] Example 1

[0068] The composition of the cladding alloy is shown in Table 1, with the balance being iron. The cladding method comprises preheating the workpiece portion to be welded to 200°C, performing layered cladding using a MIG (metal inert gas) welding process using the cladding alloy of the aforementioned composition, maintaining an interlayer temperature of 200°C to 300°C, and performing a tempering treatment after the layered cladding, maintaining a tempering temperature of 540°C to 600°C.

[0069] The metallographic test of the surfacing alloy layer of Example 1 was carried out, and the distribution of the carbide hard phase was shown in Figure 1 and Figure 2 The hard phase of carbide is finely dispersed. The crack condition of the surfacing alloy layer of Example 1 was characterized. The characterization results are shown in Table 2 and Figure 5 , which is a macro photo of a range of 200mm long and 100mm wide.

[0070] A friction and wear test was conducted on the surfacing alloy layer of Example 1 using a CSM brand friction and wear testing machine. The test conditions were pre-calibrated, with a temperature of 20°C, a pressure of 3N, a rotation speed of 60r / min, and a test time of 40min. The surface morphology of the surfacing alloy layer after the friction and wear test was observed using a LEXTOLS5000 3D laser measuring microscope, and the volume reduction of the surfacing alloy layer was measured to obtain the wear resistance of the surfacing alloy layer. The results are shown in Table 2.

[0071] Examples 2-5

[0072] The methods of Example 1 were respectively followed, except that the composition of the alloy material for surfacing was different, as shown in Table 1. Corresponding tests were performed, and the test results are shown in Table 2. The macroscopic photograph of the surfacing alloy layer of Example 5 is shown in Figure 3 and Figure 4 , Figure 3 The macroscopic photograph of the 200mm long and 100mm wide range is shown in FIG. 4. The macroscopic photograph of the surfacing alloy layer of Example 4 is shown in FIG. Figure 6 , which is a macro photo of a range of 200mm long and 100mm wide.

[0073] Comparative Examples 1-5

[0074] The methods of Example 1 were respectively followed, except that the composition of the alloy material for surfacing was different, as shown in Table 1. Corresponding tests were performed, and the test results are shown in Table 2. The macroscopic photograph of the surfacing alloy layer of Comparative Example 1 is shown in Figure 7 and Figure 8 , Figure 7 This is a macro photo of a range of 200mm long and 100mm wide.

[0075] Table 1

[0076]

[0077] Table 2

[0078] Performance indicators crack wear resistance Example 1 light good Example 2 light better Example 3 light better Example 4 Lighter better Example 5 Extremely light Excellent Comparative Example 1 Heavy Slightly worse Comparative Example 2 Extremely light Difference Comparative Example 3 Extremely light Difference Comparative Example 4 Heavy better Comparative Example 5 Heavy better

[0079] The wear resistance of the surfacing alloy layer is in the following order: excellent > good > better > slightly worse > poor. The method for obtaining the wear resistance level of the surfacing alloy layer is to calculate the volume of the surface layer of the surfacing alloy layer before friction (wherein the volume of the surface layer refers to the volume of the surfacing alloy layer within a certain distance from the surface of the surfacing alloy layer), and divide the volume reduction by the volume of the surface layer of the surfacing alloy layer before friction to obtain the relative volume reduction. A relative volume reduction of ≤25% is called excellent, 25% < relative volume reduction ≤28% is called good, 28% < relative volume reduction ≤30% is called better, 30% < relative volume reduction ≤35% is called slightly worse, and a relative volume reduction greater than 35% is called poor.

[0080] The crack severity of the cladding alloy layer is as follows: very light > light > relatively light > heavy. The method for obtaining the crack severity level of the cladding alloy layer is to divide the cladding alloy layer on the surface of the workpiece to be welded into grids with a length of 200mm and a width of 100mm. The number of cracks and the average crack width in each grid are counted, and the crack severity of each grid is graded. The number of cracks is 0-2 and the average crack width is less than 0.15mm, which is called very light. The number of cracks is 3-6 and the average crack width is less than 0.15mm, which is called light. The number of cracks is 7-12 and the average crack width is less than 0.15mm, which is called relatively light. The number of cracks is greater than 12 and / or the average crack width is greater than 0.15mm, which is called heavy. The crack severity of the grid with the heaviest crack severity among a limited number of grids is used as the crack severity of the cladding alloy layer. The above crack severity classification method is limited to cases where the length of all cracks in the overlay alloy layer is less than 200 mm. When the overlay alloy layer has cracks longer than 200 mm, the crack severity is considered severe. The average crack width of the overlay alloy layer in Comparative Examples 1, 4, and 5 of the present invention is greater than 0.3 mm.

[0081] In Comparative Example 1, the chemical composition of the alloy material for surfacing welding is calculated by weight percentage, and the V content is not less than 1.5, which can inhibit the generation of cracks and improve wear resistance; in Comparative Example 2, the chemical composition of the alloy material for surfacing welding is calculated by weight percentage, and the W content is not less than 1.5, which can improve wear resistance; in Comparative Example 3, the C content is not less than 0.7, which can improve wear resistance; in Comparative Example 4, the alloy material for surfacing welding does not contain Mo, Co, Ni, and Nb, which can inhibit the generation of cracks; in Comparative Example 5, the Si content is 0.9wt% to 1.3wt%, which can inhibit the generation of cracks.

[0082] Comparing Example 5 with Example 1, the rare earth content is 0.1wt% to 0.15wt%, which is more conducive to suppressing the generation of cracks and improving wear resistance; comparing Example 1 with Example 2, the chemical composition of the alloy material for surfacing welding, calculated by weight percentage, satisfies 3.5%≤W+V≤6%, which is more conducive to improving wear resistance; comparing Example 1 with Example 3, the chemical composition of the alloy material for surfacing welding, calculated by weight percentage, V / W is not greater than 0.9, which is more conducive to improving wear resistance; comparing Example 1 with Example 4, the chemical composition of the alloy material for surfacing welding, calculated by weight percentage, V / W is not less than 0.7, which is more conducive to suppressing the generation of cracks and improving wear resistance.

[0083] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. An alloy material for surfacing welding, characterized in that: Its chemical composition, in weight percentage, is C: 1.0-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-2.9, V: 1.5-2.9, with the balance being iron; it is used for surfacing welding of curved surfaces of internal mixers; the surfacing alloy layer formed by layered surfacing welding of the surfacing alloy material has a dispersed carbide hard phase; the carbide hard phase mainly includes tungsten carbide and vanadium carbide; the thermal expansion coefficients of tungsten carbide and vanadium carbide are close to those of iron, thereby suppressing stress between the substrate and the tungsten carbide or vanadium carbide; the distribution density of the carbide hard phase is 1500 / mm 2 ~40000 / mm 2 The equivalent circle diameter of the carbide hard phase is less than 1 μm; and it does not contain the elements Mo, Co, Ni, and Nb.

2. The alloy material for surfacing welding according to claim 1, characterized in that: The chemical composition of the alloy material for surfacing welding satisfies 3.5%≤W+V≤6% in weight percentage.

3. The alloy material for surfacing welding according to claim 1, characterized in that: The chemical composition of the alloy material for surfacing welding satisfies a V / W ratio of 0.7 to 0.9 in terms of weight percentage.

4. An alloy material for surfacing welding, characterized in that: Its chemical composition, in weight percentage, is C: 1.0-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-2.9, V: 1.5-2.9, rare earth elements: 0.1-0.15, and the balance is iron. It is used for surfacing welding of curved surfaces of internal mixers. The surfacing alloy layer formed by layered surfacing welding of the surfacing alloy material has a dispersed carbide hard phase. The carbide hard phase mainly includes tungsten carbide and vanadium carbide. The thermal expansion coefficients of tungsten carbide and vanadium carbide are close to those of iron, thereby suppressing stress between the substrate and the tungsten carbide or vanadium carbide. The distribution density of the carbide hard phase is 1500 / mm 2 ~40000 / mm 2 The equivalent circle diameter of the carbide hard phase is less than 1 μm; and it does not contain the elements Mo, Co, Ni, and Nb.

5. The alloy material for surfacing welding according to claim 4, characterized in that: The chemical composition of the alloy material for surfacing welding satisfies 3.5%≤W+V≤6% in weight percentage.

6. The alloy material for surfacing welding according to claim 4, characterized in that: The chemical composition of the alloy material for surfacing welding satisfies a V / W ratio of 0.7 to 0.9 in terms of weight percentage.

7. A surfacing method, characterized in that: include: The part to be welded of the workpiece is preheated to 150°C to 250°C, and layered surfacing welding is performed using the surfacing alloy material according to any one of claims 1 to 3 and / or the surfacing alloy material according to any one of claims 4 to 6. The interlayer temperature of the layered surfacing welding is 200°C to 300°C, and a tempering treatment at a temperature of 540°C to 600°C is performed after the layered surfacing welding.

8. A mechanical part having a cladding alloy layer on the surface of a base steel material, characterized in that: The chemical composition of the surfacing alloy layer is, by weight percentage, C: 1.0-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-2.9, V: 1.5-2.9, and the balance is iron; Alternatively, the chemical composition of the surfacing alloy layer is, by weight percentage, C: 1.0-1.4, Si: 0.9-1.3, Mn: 1.5-2.5, Cr: 12-16, W: 1.5-2.9, V: 1.5-2.9, rare earth elements: 0.1-0.15, and the balance is iron; Applicable to surfacing welding of curved surfaces of internal mixers; the surfacing alloy layer is formed by layering surfacing with alloy materials, and the surfacing alloy layer is dispersed with carbide hard phase; the carbide hard phase mainly includes tungsten carbide and vanadium carbide; the thermal expansion coefficients of tungsten carbide and vanadium carbide are close to those of iron, which suppresses the stress generated between the substrate and the tungsten carbide or vanadium carbide; the distribution density of the carbide hard phase is 1500 / mm 2 ~40000 / mm 2 The equivalent circle diameter of the carbide hard phase is less than 1 μm; the surfacing alloy layer does not contain the elements Mo, Co, Ni, and Nb.

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