Novel high-manganese austenitic steel manual electric arc welding electrode for frog repair

Abstract

The invention relates to a novel high-manganese austenitic steel manual arc welding rod for frog repair. The welding rod comprises 70-80 wt% of a welding rod core and 20-30 wt% of a coating, wherein the outer surface of the welding rod core is coated with the coating. The welding rod core comprises the following chemical components in percentage by weight: 0.95 to 1.2 weight percent of C, 36 to 46 weight percent of Mn, 2.0 to 4.0 weight percent of Mo, 1.0 to 5.0 weight percent of Cr, 0.5 to 6.0 weight percent of Al, 0.5 to 6.0 weight percent of V, 0.5 to 4 weight percent of Cu, 0.1 to 1.0 weight percent of Si, less than or equal to 0.002 weight percent of P, less than or equal to 0.002 weight percent of S and the balance of Fe and inevitable impurities; the coating comprises the following chemical components in percentage by weight: 20 to 30 percent of marble, 10 to 20 percent of fluorite, 10 to 20 percent of rutile, 4 to 6 percent of 45 ferrosilicon, 5 to 8 percent of low-carbon ferromanganese, 5 to 8 percent of sodium carbonate and the balance of iron powder. The welding rod is matched with frog base metal, good metallurgical bonding is generated, and the welding rod has the advantages of being low in hot crack sensitivity, excellent in impact wear resistance, high in strength, hardness and toughness, low in cost, simple in component system, excellent in operation manufacturability and the like.

Description

Technical Field

[0001] The present invention relates to the field of welding materials, and more specifically, to a new type of manual arc welding electrode made of high manganese austenitic steel for frog repair. Background Art

[0002] Railways are the main arteries of China's economy and occupy an important position in the national economy. High manganese steel (Mn13) used for frogs has excellent work hardening ability and is widely used in railway transportation. However, high manganese steel for frogs is cast and prone to defects such as shrinkage porosity and gas holes. Under harsh service conditions, frogs are easily damaged, resulting in unstable frog dimensions and large discreteness in service life. Since frogs are expensive, direct scrapping after damage will greatly increase the operating cost. Improving the service life of frogs through surfacing repair is one of the effective ways to solve this problem.

[0003] For on-site welding repair of damaged frogs after service, the welding electrode is one of the commonly used welding materials. The welding electrode consists of a welding core and a coating. The welding core conducts current and transfers alloying elements. The coating plays roles such as protection, chemical metallurgy, minor alloying, and regulating the operation processability. The prior art "High Manganese Steel Welding Electrode and Its Welding Method" (Patent No.: CN1439481A) has the advantages of low price and simple operation. However, this technology does not give the mechanical properties and impact wear properties data of the surfacing metal after repair, and it is impossible to judge whether it meets the actual working conditions of frog service. The prior art "Special Nitrogen-containing Electrode for Railway Frogs" (Patent No.: CN1490121A), the surfacing metal prepared by this technology has more than doubled wear resistance compared with the widely used KD286 electrode. However, the addition of nitrogen element is prone to generate pores, which limits the further improvement of the service performance of the surfacing metal. And there is a large difference in carbon content between the surfacing metal and the frog high manganese steel, and cracks may occur near the fusion line, making it difficult to achieve good metallurgical bonding. In addition, alloying elements Cr, Mn, N, and V in the surfacing metal are all transitioned by the coating, and the transition coefficient is low. The burning loss of a large amount of alloying elements leads to high production costs. The surfacing metal prepared by the prior art "A Low Crack Sensitivity Electrode for Welding and Repairing High Manganese Steel" (Patent No.: CN110977241A) does not show hot cracks at the fusion line with the frog, achieving good metallurgical bonding. However, 20% of the Mn element content in the surfacing metal is alloyed through the coating, resulting in serious alloy burning loss and high production costs. In addition, this technology also does not give relevant test data such as wear resistance, and it is also impossible to judge whether it can meet the service conditions and life of frogs. The Mn-Cr-N series electrodes in Japan, and the Cr-Mn-Mo series and Mn-Cr series electrodes used in some countries in the United States and Western Europe all maintain good service performance after frog surfacing repair. However, such electrodes all contain a large amount of precious elements such as nickel, chromium, and molybdenum, and the cost is expensive. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a new type of manual arc welding electrode made of high manganese austenitic steel for frog repair, which can produce good metallurgical bonding with the frog steel base material, has excellent impact wear resistance, and greatly reduces the use of precious alloying elements, having advantages such as low cost and simple alloy composition system, and can meet the mechanical property requirements of strength, hardness and toughness of the deposited layer of the repaired frog.

[0005] The technical solution adopted by the present invention to solve its technical problem is to construct a new type of manual arc welding electrode made of high manganese austenitic steel for frog repair, and the electrode includes a welding core of 70-80wt% and a coating of 20-30wt% coated on the outer surface of the welding core;

[0006] The chemical components and their contents of the welding core are: C is 0.95-1.2wt%, Mn is 36-46wt%, Mo is 2.0-4.0wt%, Cr is 1.0-5.0wt%, Al is 0.5-6.0wt%, V is 0.5-6.0wt%, Cu is 0.5-4.0wt%, Si is 0.1-1.0wt%, P≤0.002wt%, S≤0.002wt%, and the balance is Fe and unavoidable impurities;

[0007] The chemical components and their contents of the coating are: marble 20-30wt%, fluorite 10-20wt%, rutile 10-20wt%, 45 ferrosilicon 4-6wt%, low-carbon ferromanganese 5-8wt%, soda ash 5-8wt%, and the balance is iron powder.

[0008] According to the above scheme, the metallographic structure of the deposited metal after welding of the electrode is all austenite structure.

[0009] According to the above scheme, the hardness of the deposited metal formed by the electrode is ≥255HV1, the yield strength of the deposited metal after welding of the electrode is 545-574MPa, the tensile strength is 707-747MPa, the elongation after fracture is 45.5-49.5%, and the impact toughness at room temperature reaches 174-200J / cm 2 。

[0010] The present invention also provides a preparation method of a manual arc welding electrode made of high manganese austenitic steel for frog repair, in which the chemical components of the coating are proportioned and mixed, and then 10%-15% of a binder is added, and after being stirred evenly, it is pressed and coated on the surface of the welding core to obtain a manual arc welding electrode for frog repair.

[0011] According to the above scheme, the binder is water glass with a mass ratio of K:Na of 2:1 and a modulus of 2.6-3.2.

[0012] According to the above solution, the purity of the marble is ≥99%, and the particle size of the marble is ≤0.3 mm.

[0013] According to the above solution, the purity of the fluorite is ≥99%, and the particle size of the fluorite is ≤0.3 mm.

[0014] According to the above solution, the purity of the rutile is ≥99%, and the particle size of the rutile is ≤0.3 mm.

[0015] According to the above solution, the purity of the 45 ferrosilicon is ≥99%, and the particle size of the 45 ferrosilicon is ≤0.3 mm.

[0016] According to the above solution, the purity of the low-carbon ferromanganese is ≥99%, and the particle size of the low-carbon ferromanganese is ≤0.3 mm.

[0017] According to the above solution, the purity of the soda ash is ≥99%, and the particle size of the soda ash is ≤0.3 mm.

[0018] According to the above solution, the purity of the iron powder is ≥99%, and the particle size of the iron powder is ≤0.3 mm.

[0019] Implementing the new type of manual arc welding electrode of high manganese austenitic steel for frog repair of the present invention has the following

[0020] Beneficial effects:

[0021] 1. The present invention is mainly composed of "C", "Mn" and other alloying elements. The appropriate content of "C" element ensures good metallurgical bonding between the welding material and the base material. The appropriate content of "Mn" element and other alloying elements ensures that the deposited metal meets the strength, hardness, toughness required for the service of the frog, as well as excellent impact wear performance;

[0022] 2. The present invention uses the method of alloying element transition through the electrode core. Compared with the method of alloying element transition through the coating, the advantage of the electrode core transition is that it can transition alloying elements to the deposited metal with higher efficiency and stability, ensuring that the alloying element content in the deposited metal meets the technical requirements. There are no large amounts of alloying elements in the coating, which not only avoids the waste caused by the burning loss of alloying elements but also improves the operation processability;

[0023] 3. The present invention has a small addition amount of precious alloying elements such as Nb, V, Ti, and Ni, etc., and has the advantage of low economic cost;

[0024] 4. The electrode prepared by the present invention has advantages such as good weld bead formability and low sensitivity to hot cracks, and no hot cracks appear in the formed deposited metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0026] Figure 1It is the microstructure diagram of the weld metal in Embodiment 1 of the present invention;

[0027] Figure 2 It is the microstructure diagram of the weld metal in Embodiment 2 of the present invention;

[0028] Figure 3 It is the microstructure diagram of the weld metal in Embodiment 3 of the present invention;

[0029] Figure 4 It is the microstructure diagram of the weld metal in Comparative Example 1 of the present invention;

[0030] Figure 5 It is the microstructure diagram of the weld metal in Comparative Example 2 of the present invention. Detailed implementation manners

[0031] For a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed implementation manners of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] A manual arc welding electrode for manganese high austenitic steel used for frog repair, the manual arc welding electrode for manganese high austenitic steel is composed of 70-80 wt% of the electrode core and 20-30 wt% of the coating. The chemical components of the electrode core are: C is 0.95-1.2 wt%, Mn is 36-46 wt%, Mo is 2.0-4.0 wt%, Cr is 1.0-5.0 wt%, Al is 0.5-6.0 wt%, V is 0.5-6.0 wt%, Cu is 0.5-4.0 wt%, Si is 0.1-1.0 wt%, P≤0.002 wt%, S≤0.002 wt%, and the balance is Fe and unavoidable impurities; the coating is designed with a calcium carbonate type having low hydrogen characteristics and neutral chemical properties, and the components of the coating include 20-30 wt% of marble, 10-20 wt% of fluorite, 10-20 wt% of rutile, 4-6 wt% of 45 ferrosilicon, 5-8 wt% of low-carbon ferromanganese, 5-8 wt% of soda ash, and the balance of iron powder in terms of mass percentage.

[0033] The preparation method of the manual arc welding electrode for manganese high austenitic steel used for frog repair is: first, mix the chemical components of the coating evenly according to the above ratio, then add 10%-15 wt% of the binder, stir evenly, and then press and coat it on the surface of the electrode core to obtain the manual arc welding electrode used for frog repair. The binder is water glass with a mass ratio of K:Na of 2:1 and a modulus of 2.6-3.2. The metallographic structure of the deposited metal formed by the electrode is all austenite structure, the hardness of the deposited metal formed is ≥255 HV1, the yield strength of the deposited metal formed is 545-574 MPa, the tensile strength is 707-747 MPa, the elongation after fracture is 45.5-49.5%, and the room temperature impact toughness reaches 174-200 J / cm 2 .

[0034] The purity of marble is ≥99%, and the particle size of marble is ≤0.3 mm. The purity of fluorite is ≥99%, and the particle size of fluorite is ≤0.3 mm. The purity of rutile is ≥99%, and the particle size of rutile is ≤0.3 mm. The purity of 45 ferrosilicon is ≥99%, and the particle size of 45 ferrosilicon is ≤0.3 mm. The purity of low-carbon ferromanganese is ≥99%, and the particle size of low-carbon ferromanganese is ≤0.3 mm. The purity of soda ash is ≥99%, and the particle size of soda ash is ≤0.3 mm. The purity of iron powder is ≥99%, and the particle size of iron powder is ≤0.3 mm.

[0035] In the field of railway frog manufacturing in China, Mn13 steel has been widely used due to its excellent performance. In this invention's experiment, an Mn13 frog steel plate with a thickness of 30 mm, a width of 35 mm, and a length of 70 mm was selected, its surface was cladded, and the impact wear performance and other mechanical properties of the cladded metal were detected. The diameter of the manual arc welding electrode is φ3.2 mm. The welding process parameters are: welding current is 90 - 120 A, arc voltage is 22 - 26 V, and welding speed is 9 - 12 cm / min. The manual arc welding electrode for frog cladding test was strictly carried out in accordance with the standard TB / T 3083 - 2003, and the impact wear test (including sampling and parameter setting) of the cladded metal was strictly carried out in accordance with T / CFA010604.05 - 2017.

[0036] Example 1

[0037] As Figure 1 shown, the weld metal is a full austenite structure diagram. The chemical components of the electrode core of the manual arc welding electrode for frog repair are: C is 0.95 wt%, Mn is 36 wt%, Cr is 2.0 wt%, Mo is 2.0 wt%, Al is 0.5 wt%, V is 0.5 wt%, Si is 0.1 wt%, Cu is 0.5 wt%, P is 0.002 wt%, S is 0.001 wt%; the balance is Fe and unavoidable impurities.

[0038] The coating with components including 25 wt% marble, 18 wt% fluorite, 14 wt% rutile, 4 wt% 45 ferrosilicon, 5 wt% low-carbon ferromanganese, 5 wt% soda ash, and the balance of iron powder by mass percentage was mixed evenly, 13 wt% of K:Na with a mass ratio of 2:1 and a modulus of 2.6 - 3.2 was added and stirred evenly, and then it was pressed and coated on the surface of the electrode core to obtain a manual arc welding electrode for frog repair. The prepared welding electrode was cladded on the surface of the frog base material, with good operation processability, no cracks appeared in the weld metal, and the microstructure and mechanical properties of the weld metal were detected and analyzed. The results showed that the weld metal was a pure austenite structure, and the room temperature impact toughness was 174 J / cm 2, with a hardness of 269 HV1, a yield strength of 574 MPa, a tensile strength of 747 MPa, and an elongation after fracture of 45.5%. After 9000 impacts with impact loads of 2 J, 3.5 J, and 5 J, the wear amounts are less than 0.95 g, 0.87 g, and 0.74 g respectively, meeting the mechanical property requirements for the repair cladding layer of frog in TB / T 3083 - 2003.

[0039] Example 2

[0040] As Figure 2 shown, the weld metal is a full austenite structure diagram. The chemical components of the electrode core of the manual arc welding electrode for frog repair are: C is 1.1 wt%, Mn is 42 wt%, Cr is 3.0 wt%, Mo is 3.0 wt%, Al is 3.3 wt%, V is 3.0 wt%, Cu is 2.0 wt%, Si is 0.3%, P is 0.002 wt%, S is 0.001 wt%; the balance is Fe and unavoidable impurities.

[0041] The components by mass percentage include 25 wt% marble, 18 wt% fluorite, 14 wt% rutile, 4 wt% 45 ferrosilicon, 5 wt% low - carbon ferromanganese, 5 wt% soda ash, and the balance iron powder. The coating is mixed evenly, added with 13 wt% of K:Na with a mass ratio of 2:1 and a modulus of 2.6 - 3.2, stirred evenly, and then pressed onto the surface of the electrode core to obtain a manual arc welding electrode for frog repair. The obtained welding electrode is deposited on the surface of the frog base material, with good operation processability, no cracks in the weld metal, and its microstructure and mechanical properties are detected and analyzed. The results show that the weld metal is a full austenite structure, and the weld metal not only ensures excellent toughness, with a room - temperature impact toughness of 200 J / cm 2 , with a hardness of 255 HV1, a yield strength of 545 MPa, a tensile strength of 707 MPa, and an elongation after fracture of 49.5%. After 9000 impacts with impact loads of 2 J, 3.5 J, and 5 J, the wear amounts are less than 0.90 g, 0.81 g, and 0.70 g respectively, meeting the mechanical property requirements for the repair cladding layer of frog in TB / T 3083 - 2003.

[0042] Example 3

[0043] As Figure 3 shown, the weld metal is a full austenite structure diagram. The chemical components of the electrode core of the manual arc welding electrode for frog repair are: C is 1.2 wt%, Mn is 46 wt%, Cr is 5.0 wt%, Mo is 4.0 wt%, Al is 6.0 wt%, V is 6.0 wt%, Si is 0.5 wt%, Cu is 4.0%, P is 0.002 wt%, S is 0.001 wt%; the balance is Fe and unavoidable impurities.

[0044] The coating is composed of, by mass percentage, 25 wt% marble, 18 wt% fluorite, 14 wt% rutile, 4 wt% ferrosilicon 45, 5 wt% ferromanganese low carbon, 5 wt% soda ash, and the balance iron powder. The coating is evenly mixed, and 13 wt% of a mixture with a K:Na mass ratio of 2:1 and a modulus of 2.6 - 3.2 is added and stirred evenly. Then it is pressed and coated onto the surface of the electrode core to obtain a manual arc welding electrode for frog repair. The obtained welding electrode is deposited on the surface of the frog base material. The operation processability is good, and no cracks appear in the weld metal. The microstructure and mechanical properties thereof are detected and analyzed. The results show that the weld metal is a fully austenitic structure. The weld metal not only ensures excellent toughness, with a room temperature impact toughness of 180 J / cm 2 , a hardness of 271 HV1, a yield strength of 552 MPa, a tensile strength of 717 MPa, and an elongation after fracture of 47.5%. After 9000 impact wear cycles with 2 J, 3.5 J, and 5 J impact loads, the wear amounts are less than 0.94 g, 0.88 g, and 0.73 g respectively, meeting the mechanical property requirements for the deposited layer of frog repair in TB / T 3083 - 2003.

[0045] Comparative Example 1

[0046] As Figure 4 shown, the weld metal is a fully austenitic structure diagram. The chemical composition of the electrode core of the manual arc welding electrode for frog repair is: C is 1.1 wt%, Mn is 42 wt%, Cr is 3.0 wt%, Mo is 0 wt%, Al is 0 wt%, V is 0 wt%, Si is 0 wt%, Cu is 0%, P is 0.002 wt%, S is 0.001 wt%; the balance is Fe and inevitable impurities.

[0047] The coating is composed of, by mass percentage, 25 wt% marble, 18 wt% fluorite, 14 wt% rutile 6, 4 wt% ferrosilicon 45, 5 wt% ferromanganese low carbon, 5 wt% soda ash, and the balance iron powder. The coating is evenly mixed, and 13 wt% of a mixture with a K:Na mass ratio of 2:1 and a modulus of 2.6 - 3.2 is added and stirred evenly. Then it is pressed and coated onto the surface of the electrode core to obtain a manual arc welding electrode for frog repair. The obtained welding electrode is deposited on the surface of the frog base material. The operation processability is good, and no cracks appear in the weld metal. The microstructure and mechanical properties thereof are detected and analyzed. The results show that the weld metal is a fully austenitic structure, with a room temperature impact toughness of 195 J / cm 2 , a yield strength of 502 MPa, a tensile strength of 662 MPa, and an elongation after fracture of 45.5%. After 9000 impact wear cycles with 2 J, 3.5 J, and 5 J impact loads, the wear amounts are less than 1.26 g, 1.08 g, and 0.9 g respectively.

[0048] Comparative Example 2

[0049] As Figure 5 shown, the chemical components of the electrode core of the shielded metal arc welding electrode for frog repair are: C is 1.1 wt%, Mn is 42 wt%, Cr is 3.0 wt%, Mo is 6.0 wt%, Al is 7.0 wt%, V is 6.5 wt%, Si is 1.5 wt%, Cu is 6.0%, P is 0.002 wt%, S is 0.001 wt%; the balance is Fe and unavoidable impurities.

[0050] The coating components include 25% marble, 18% fluorite, 14% rutile, 4% ferrosilicon 45, 5% low-carbon ferromanganese, 5% soda ash, and the balance iron powder are mixed evenly, added with 13 wt% of K:Na with a mass ratio of 2:1 and a modulus of 2.6 - 3.2 and stirred evenly, and then pressed and coated on the surface of the electrode core to obtain the shielded metal arc welding electrode for frog repair. The obtained welding electrode is deposited on the surface of the frog base material, with good operation processability, no cracks in the weld metal, and its microstructure and mechanical properties are detected and analyzed: the weld metal is a fully austenitic structure, the room temperature impact toughness is 54 J / cm, the hardness is 265 HV1, the yield strength is 599 MPa, the tensile strength is 785 MPa, the elongation after fracture is 35%, and the impact wear amounts after 9000 times of impact with 2 J, 3.5 J, and 5 J impact loads are less than 2.56 g, 2.33 g, and 2.12 g respectively.

[0051] Alloying elements are added to the electrode core and play the following positive roles:

[0052] C: Carbon can expand the austenite phase region and ensure a stable austenite structure during water toughening treatment. And since carbon is an interstitial solid solution element, when it dissolves in the austenite lattice, it will cause strong lattice distortion, form Cottrell atmospheres, hinder the movement of dislocations, and improve the strength of the steel. At the same time, the carbon content of the frog steel is about 1.1 wt%, and sufficient carbon needs to be added to reduce the carbon content difference from the base material to avoid problems such as uneven element distribution, sudden change in tissue properties, and low metallurgical bonding strength in the fusion zone during welding. However, the mass fraction of carbon should not be too high, as too high a carbon content will increase the thermal crack sensitivity of the material. Therefore, to ensure good metallurgical bonding between the welding material and the base material, give full play to the role of carbon atoms in increasing the strength of the deposited metal, and have no adverse impact on the thermal crack sensitivity. So the carbon content in the electrode core should be controlled at 0.95 - 1.2 wt%.

[0053] Si: The silicon element can produce solid solution strengthening, distort the crystal lattice of steel, hinder the movement of dislocations, and thus improve the ability of steel to resist deformation. At the same time, silicon can also increase the strength and hardness of steel materials and enhance the impact wear resistance of the materials. However, too high a content of silicon may reduce the solubility of carbon in austenite, thereby forming a large amount of carbides, resulting in an increase in material brittleness. Moreover, silicon will also reduce the stacking fault energy of high manganese steel, increase the possibility of the TRIP effect in high manganese steel, and damage the work hardening ability of high manganese steel. Therefore, to ensure that the silicon element can improve the strength of the deposited metal without excessively reducing the stacking fault energy of the deposited metal. Therefore, the silicon content in the electrode core of the present invention is controlled at 0.1-1.0 wt%.

[0054] Mn: The manganese element can keep the room temperature structure of high manganese steel as a single and stable austenite structure by lowering the Ms point and expanding the austenite phase region. Most of the manganese elements exist in the austenite matrix in a solid solution form. A higher manganese content can improve the solid solution ability of other alloy elements, and a higher manganese content is more suitable for workpieces under high impact wear conditions. However, too much manganese content will not only reduce the toughness of the deposited metal but also lead to an increase in its thermal expansion coefficient. The manganese content of the frog steel base material is about 13 wt%. If the manganese content of the welding consumable and the base material differs too much, it is easy to cause cracking at the fusion line between the deposited layer and the frog steel base material. Therefore, it is necessary to increase the manganese content in the deposited metal as much as possible without affecting the metallurgical bonding between the welding consumable and the frog steel base material. Therefore, the mass fraction of manganese in the electrode core of the present invention is 36-46 wt%.

[0055] Cr+Mo: When Cr and Mo alloy elements act in a coupled manner, they can improve the yield strength of steel materials. Adding Cr-Mo can inhibit the generation of deformation twins at the initial stage of strain, reduce the carbon activity, and form slow and thinner deformation twins in the middle and late stages of strain, so as to achieve high-strength and continuous work hardening. In addition, when high manganese steel is alloyed with Mo, the grain size of high manganese steel will be significantly refined, significantly improving its tensile strength and elongation. Moreover, the Mo element can also reduce the stacking fault energy of high manganese steel. The combined effect of the two aspects will make the deposited layer have excellent strength and plasticity, and form a deeper plastic strain layer during impact. The high-strength and continuous work hardening ability and the cooperation between the hardened surface layer and the plastic strain layer enable high manganese steel materials to exhibit more excellent wear resistance. However, excessive Cr and Mo elements in the deposited metal will cause the high-density precipitation of large-size carbides, greatly increasing the material strength while significantly reducing the toughness, resulting in a mismatch between material strength and toughness. And the addition of excessive Cr and Mo elements will also increase the manufacturing cost of the electrode. Therefore, the Mo in the electrode core is controlled at 2.0-4.0 wt%, and the Cr element is controlled at 1.0-5.0 wt%. The proportions of Cr and Mo elements are relatively small, so the economic cost is very low.

[0056] V: The V element can increase the hardness of high manganese steel. Vanadium is a strong carbide-forming element and easily combines with the C element to form carbides such as VC. Vanadium carbide has a very high melting point and high hardness. The high-hardness vanadium carbide particles are distributed in the austenite in a dispersed form, which can form a strong hardening effect on the matrix. It is reported that the wear resistance of vanadium-containing high manganese steel is five times that of traditional high manganese steel. At the same time, when fine-grained vanadium carbide compounds generally precipitate at the grain boundaries, due to their very high melting points, they cannot all dissolve into the matrix, so they will prevent grain boundary diffusion and thus inhibit grain growth. Due to the refinement of grains, the strength of high manganese steel can be improved while the plasticity and toughness do not decrease. Therefore, the wear resistance of austenitic manganese steel containing vanadium carbide is significantly better than that of standard austenitic manganese steel. However, excessive V will still cause a decrease in the toughness of the deposited metal, resulting in a mismatch between the strength and hardness of the material and reducing the reliability of the mechanical properties of the deposited metal. Therefore, the V element in the electrode core is controlled at 0.5 - 6.0 wt%.

[0057] Cu: The Cu element can play a role in solid solution strengthening in high manganese steel. The Cu atoms entering the crystal lattice distort the lattice, increasing the resistance to dislocation movement, thereby increasing the surface hardness and enhancing its wear resistance. The Cu element can also act synergistically with the Mn element to improve the work hardening performance of high manganese steel and increase the hardness and thickness of the work hardened layer. An appropriate content of the Cu element will also promote the precipitation of the Cu-containing second phase, playing a role in second phase strengthening. However, the addition of excessive Cu elements will not only damage the toughness, strength and hardness of the material, but also cause serious element segregation. This compositional inhomogeneity will seriously affect the comprehensive properties of the steel and make the material prone to local damage during use. Therefore, the Cu element in the electrode core is controlled at 0.5 - 4.0 wt%.

[0058] Al: The Al element can increase the stability of austenite, enabling high manganese steel to maintain a stable single austenite structure under external forces and avoiding martensitic transformation. High levels of aluminum can not only promote the kinetic precipitation of nano-sized carbides after aging, but also act as a solid solution element in high manganese steel. The nano-carbides increase the surface hardness and yield strength of high manganese steel, thereby improving its wear resistance. However, excessive Al elements will deteriorate the strength, hardness and toughness of the material and also reduce the fatigue performance of the material. In addition, a large amount of Al elements in the electrode core will seriously reduce the operability of the process. Therefore, the Al element in the electrode core is controlled at 0.5 - 6.0 wt%.

[0059] The coating is designed to be low-hydrogen and neutral. On the one hand, both marble and fluorite play roles in gas formation, slag formation, and arc stabilization. On the other hand, marble also has the function of adjusting the composition of the weld metal. Fluorite has the function of hydrogen removal, which can effectively reduce the hydrogen content in the weld metal, avoid the tendency of cracks in the weld due to hydrogen, and enhance the crack resistance of the weld. The coating in the present invention mainly plays roles such as protection, chemical metallurgy, and regulation of operating processability, without the need to add a large amount of alloying elements. Compared with the prior art where a large amount of alloying elements are transferred through the coating, the coating design of the electrode in the present invention effectively avoids the problem of alloying element burn-out, significantly improves the operating processability, reduces the welding difficulty, and enhances the stability of the welding quality.

[0060] For the deposited metal, its service performance is the manifestation of comprehensive mechanical properties. Therefore, it is necessary to detect its mechanical properties such as hardness, toughness, yield strength, etc. The manual arc welding electrode prepared in the present invention for repairing frog has a fully austenitic structure in the weld metal, which not only ensures excellent toughness. The hardness of the deposited metal formed by the electrode is ≥255HV1, the yield strength of the deposited metal formed by the electrode is 545 - 574 MPa, the tensile strength is 707 - 747 MPa, the elongation after fracture is 45.5 - 49.5%, and the impact toughness at room temperature reaches 174 - 200 J / cm 2 . The impact wear amounts after 9000 impacts with 2J, 3.5J, and 5J impact loads are respectively less than 0.90 g, 0.81 g, and 0.70 g, meeting the mechanical property requirements of the frog deposited repair layer.

[0061] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention. These all fall within the protection scope of the present invention.

Claims

1. A new type of high manganese austenitic steel manual arc welding electrode for frog repair, characterized in that: The welding rod comprises 70-80wt% of welding rod core and 20-30wt% of coating coated on the outer surface of the welding core; The chemical components and contents of the welding rod core are as follows: C is 0.95-1.2wt%, Mn is 36-46wt%, Mo is 2.0-4.0wt%, Cr is 1.0-5.0wt%, Al is 0.5-6.0wt%, V is 0.5-6.0wt%, Cu is 0.5-4.0wt%, Si is 0.1-1.0wt%, P≤0.002wt%, S≤0.002wt%, and the balance is Fe and unavoidable impurities; The chemical components and contents of the coating are: 20-30wt% marble, 10-20wt% fluorite, 10-20wt% rutile, 4-6wt% 45 ferrosilicon, 5-8wt% low-carbon ferromanganese, 5-8wt% soda ash, and the balance iron powder.

2. The novel high manganese austenitic steel manual arc welding electrode for frog repair according to claim 1, characterized in that: The metallographic structure of the deposited metal formed by the welding rod is all austenite structure.

3. The novel high manganese austenitic steel manual arc welding electrode for frog repair according to claim 1, characterized in that: The hardness of the deposited metal formed by the welding rod is ≥255HV1, the yield strength of the deposited metal formed by the welding rod is 545-574MPa, the tensile strength is 707-747MPa, the elongation after fracture is 45.5-49.5%, and the room temperature impact toughness is 174-200J / cm 2 .

4. A method for preparing the high manganese austenitic steel manual arc welding electrode for frog repair according to claim 1, characterized in that: The chemical components of the coating according to claim 1 are prepared and mixed, and then 10%-15% of a binder is added, stirred evenly, and then pressed onto the surface of the electrode core to prepare a manual arc welding electrode for frog repair.

5. The method for preparing a high manganese austenitic steel manual arc welding electrode for frog repair according to claim 4, characterized in that: The mass ratio of K:Na in the binder is 2:1, and the modulus of water glass is 2.6-3.

2.

6. The method for preparing a high manganese austenitic steel manual arc welding electrode for frog repair according to claim 4, characterized in that: The purity of the marble is ≥99%, and the particle size of the marble is ≤0.3 mm.

7. The method for preparing a high manganese austenitic steel manual arc welding electrode for frog repair according to claim 4, characterized in that: The purity of the fluorite is ≥99%, and the particle size of the fluorite is ≤0.3 mm.

8. The method for preparing a high manganese austenitic steel manual arc welding electrode for frog repair according to claim 4, characterized in that: The purity of the rutile is ≥99%, and the particle size of the rutile is ≤0.3 mm.

9. The method for preparing a high manganese austenitic steel manual arc welding electrode for frog repair according to claim 4, characterized in that: The purity of the 45% ferrosilicon is ≥99%, and the particle size of the 45% ferrosilicon is ≤0.3mm.

10. The method for preparing a high manganese austenitic steel manual arc welding electrode for frog repair according to claim 4, characterized in that: The purity of the low carbon ferromanganese is ≥99%, and the particle size of the low carbon ferromanganese is ≤0.3mm; the purity of the soda ash is ≥99%, and the particle size of the soda ash is ≤0.3mm; the purity of the iron powder is ≥99%, and the particle size of the iron powder is ≤0.3mm.

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