Welding rod for repairing surfacing welding of grey cast iron sintering pallet

Abstract

The invention relates to the technical field of surfacing electrodes, and provides a surfacing electrode for repairing a grey cast iron sintering pallet, which comprises a core wire and a coating coated on the surface of the core wire, the coating comprises the following raw materials in parts by weight: 40-50 parts of marble, 20-30 parts of fluorite, 4-7 parts of ferrotitanium, 2-5 parts of ferromolybdenum, 1-3 parts of high-carbon ferromanganese, 1-3 parts of ferrosilicon, 4-7 parts of rare earth oxide, 10-14 parts of metal nickel, 1-5 parts of rubidium oxide, 0.3-2 parts of cesium fluoride and 10-20 parts of a binder; the rare earth oxide is yttrium oxide and / or lanthanum oxide. According to the technical scheme, the problem that the surface of the sintering pallet is prone to cracking after repairing and surfacing in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of surfacing electrodes, and specifically, to an electrode for repairing and surfacing a gray cast iron sintering trolley. Background Art

[0002] Sintering trolleys are indispensable main production equipment in global coke plants and sintering ball plants. Gray cast iron has properties similar to those of cast steel. The reason for choosing gray cast iron as the main material is the high temperature resistance, high carbon and other characteristics of cast iron, and the cost can be reduced to achieve the best value of cost performance. However, due to the long-term high temperature and rapid cooling working characteristics of the gray cast iron sintering trolley, cracks will occur in the girder and the car body compartment, and usually explosions occur in the bearing seat part. The main reason is the long-term rapid change of heat and cold, which makes the original gray cast iron material turn into white cast iron, resulting in significant changes in its ductility and plasticity. With long-term use, the crack in the support part of the trolley bearing seat continues to expand, causing the scrapping of trolleys worth hundreds of thousands of yuan, and even causing the suspension of the trolley group, occupying the track, and causing major production safety accidents. To solve the problem of cracking of sintering trolleys, electrodes are often used for repair welding, which can not only meet the production needs of enterprises, but also directly create economic benefits for enterprises and reduce production costs.

[0003] During the surfacing repair process of cast iron trolleys, problems such as white embrittlement of the structure and cracks are likely to occur; when using traditional surfacing electrodes, even if the whole trolley is preheated before welding (about 400°C, and it is very difficult to meet the conditions), and then heat treatment is carried out after welding under extreme conditions that can be achieved, cracking in the heat affected zone after welding will inevitably occur for ordinary surfacing electrodes. However, preheating before welding and heat treatment after welding are extremely difficult, and a large amount of energy is wasted, which seriously complicates the welding process, increases labor costs and repair costs, and causes considerable economic losses to enterprises. Therefore, it is of great significance to develop an electrode for repairing and surfacing sintering trolleys. Summary of the Invention

[0004] The present invention provides an electrode for repairing and surfacing a gray cast iron sintering trolley, which solves the problem that the surface of the sintering trolley is prone to cracking after repair welding in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides an electrode for repairing and surfacing a gray cast iron sintering trolley, including a welding core and a coating covering the surface of the welding core. The coating comprises raw materials with the following weight parts: 40 - 50 parts of marble, 20 - 30 parts of fluorite, 4 - 7 parts of ferrotitanium, 2 - 5 parts of ferromolybdenum, 1 - 3 parts of high-carbon ferromanganese, 1 - 3 parts of ferrosilicon, 4 - 7 parts of rare earth oxide, 10 - 14 parts of metallic nickel, 1 - 5 parts of rubidium oxide, 0.3 - 2 parts of cesium fluoride, and 10 - 20 parts of binder; the rare earth oxide is yttrium oxide and / or lanthanum oxide.

[0006] As a further technical solution, the rare earth oxide is yttrium oxide and lanthanum oxide.

[0007] As a further technical solution, the mass ratio of yttrium oxide to lanthanum oxide is 1:2 to 6.

[0008] In the present invention, by limiting the mass ratio of yttrium oxide to lanthanum oxide to 1:2 to 6, the crack resistance of the welding rod is further improved.

[0009] As a further technical solution, the mass ratio of rubidium oxide to cesium fluoride is 2 to 5:1.

[0010] In the present invention, by limiting the mass ratio of rubidium oxide to cesium fluoride to 2 to 5:1, the hardness of the welding rod is further improved.

[0011] As a further technical solution, the welding core is an H08A steel welding wire.

[0012] As a further technical solution, the raw materials of the coating also include 0.8 to 1.8 parts of niobium nitride.

[0013] In the present invention, by adding 0.8 to 1.8 parts of niobium nitride to the coating, the grain can be refined to make the surfacing metal more uniform and dense, thereby improving the strength and toughness of the surfacing metal.

[0014] As a further technical solution, the binder is water glass, the modulus of the water glass is 2.7 to 3.0, and the Baume degree is 48 to 50.

[0015] As a further technical solution, the diameter of the welding core is 2 to 3 mm.

[0016] As a further technical solution, the mass ratio of the welding core to the coating is 1:0.7 to 1.

[0017] The present invention also provides a preparation method of a welding rod for repairing and surfacing a gray cast iron sintering trolley, comprising the following steps: S1. Passivate high-carbon ferromanganese and ferrosilicon, and keep titanium ferrosilicon, molybdenum ferrosilicon and metallic nickel at a certain temperature. S2. After mixing other raw materials in the coating except the binder, add the binder and grind and knead into a dough to obtain the coating paint. S3. Coat the coating paint on the welding core and obtain the welding rod after drying.

[0018] As a further technical solution, the temperature of the ferrosilicon passivation treatment is 720 to 750 °C, and the passivation treatment time is 3 to 4 h; The temperature of the high-carbon ferromanganese passivation treatment is 300 to 350 °C, and the passivation treatment time is 3 to 4 h.

[0019] The temperature of the heat preservation treatment is 150~200°C, and the time of the heat preservation treatment is 1~2h.

[0020] As a further technical solution, the temperature of the drying is 200~300°C, and the time of the drying is 5~8h.

[0021] The working principle and beneficial effects of the present invention are as follows: In the present invention, during surfacing, the heat will cause the structure of the heat-affected zone of the trolley welding to be white-mouthed, and the existing form of carbon changes from tough graphite to brittle carbide, resulting in large residual stresses in the heat-affected zone, thus increasing the cracking phenomenon of the surfacing metal; while adding nickel can improve the stability of austenite in the surfacing metal, adding yttrium oxide and / or lanthanum oxide can promote the good reaction of deoxidation and desulfurization of cast iron metal, purify the surfacing molten pool, and can refine the metal crystallization purity, effectively remove metamorphic inclusions, and can improve the anti-cracking performance of the surfacing metal; adding cesium fluoride and rubidium oxide can improve the performance of the slag and can increase the hardness of the surfacing metal; adding ferromolybdenum can ensure that the surfacing metal has a certain tensile strength. Adding ferrotitanium, ferromanganese and ferrosilicon for deoxidation reaction and playing an alloying reaction role. Adding auxiliary materials such as marble, fluorite and clay for removing impurities and deoxidation; through composition adjustment or optimization, the hardness of the surfacing metal reaches HB181~217, ensuring the normal use of the trolley after surfacing. Specific embodiments

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0023] Embodiment 1 A preparation method of a welding rod for repairing and surfacing a gray cast iron sintering trolley includes the following steps: S1. Subject 1 part of high-carbon ferromanganese to passivation treatment at 300°C for 4h, subject 1 part of ferrosilicon to passivation treatment at 720°C for 4h, and keep titanium iron, ferromolybdenum and metallic nickel at 150°C for heat preservation treatment for 2h; S2. Mix 40 parts of marble, 3 parts of clay, 20 parts of fluorite, 4 parts of titanium iron, 2 parts of ferromolybdenum, 1 part of high-carbon ferromanganese, 1 part of ferrosilicon, 4 parts of rare earth oxide, 10 parts of metallic nickel, 5 parts of rubidium oxide and 0.3 part of cesium fluoride, then add 10 parts of water glass and grind and knead into a dough to obtain a coating material; S3. Uniformly coat the coating material on an H08A steel wire with a diameter of 2mm by a welding rod extrusion coater, and put it into a drying oven to dry at 200°C for 8h to obtain a welding rod; The mass ratio of the coating flux to the H08A steel welding wire is 0.7:1; The rare earth oxide is yttrium oxide.

[0024] Example 2 A method for preparing a welding electrode for repairing and surfacing a gray cast iron sintering trolley, comprising the following steps: S1. Passivate 3 parts of high-carbon ferromanganese at 350 °C for 3 h, passivate 3 parts of ferrosilicon at 750 °C for 3 h, and keep ferrotitanium, ferromolybdenum, and metallic nickel at 200 °C for 1 h; S2. Mix 50 parts of marble, 6 parts of clay, 30 parts of fluorite, 7 parts of ferrotitanium, 5 parts of ferromolybdenum, 31 parts of high-carbon ferromanganese, 3 parts of ferrosilicon, 7 parts of rare earth oxide, 14 parts of metallic nickel, 1 part of rubidium oxide, and 2 parts of cesium fluoride, then add 10 parts of water glass and grind and knead into a dough to obtain the coating flux; S3. Uniformly coat the coating flux on the H08A steel welding wire with a diameter of 3 mm through a welding electrode extrusion coater, and place it in a drying oven to dry at 300 °C for 5 h to obtain the welding electrode; The mass ratio of the coating flux to the H08A steel welding wire is 1:1; The rare earth oxide is yttrium oxide.

[0025] Example 3 This example is only different from Example 2 in that the rare earth oxide is lanthanum oxide.

[0026] Example 4 This example is only different from Example 2 in that the rare earth oxide is yttrium oxide and lanthanum oxide; the mass ratio of yttrium oxide to lanthanum oxide is 1:1.

[0027] Example 5 This example is only different from Example 4 in that the mass ratio of yttrium oxide to lanthanum oxide is 1:9.

[0028] Example 6 This example is only different from Example 4 in that the mass ratio of yttrium oxide to lanthanum oxide is 1:2.

[0029] Example 7 This example is only different from Example 4 in that the mass ratio of yttrium oxide to lanthanum oxide is 1:6.

[0030] Example 8 This example is only different from Example 7 in that the addition amount of rubidium oxide is 2.6 parts and the addition amount of cesium fluoride is 0.4 parts.

[0031] Example 9 This example is only different from Example 7 in that the addition amount of rubidium oxide is 2 parts and the addition amount of cesium fluoride is 1 part.

[0032] Example 10 This example is only different from Example 7 in that the addition amount of rubidium oxide is 2.5 parts and the addition amount of cesium fluoride is 0.5 part.

[0033] Example 11 This example is only different from Example 8 in that 0.8 part of niobium nitride is further added to the coating.

[0034] Example 12 This example is only different from Example 8 in that 1.8 parts of niobium nitride are further added to the coating.

[0035] Comparative Example 1 This comparative example is only different from Example 1 in that yttrium oxide is not added.

[0036] Comparative Example 2 This comparative example is only different from Example 1 in that rubidium oxide is replaced with an equal amount of cesium fluoride.

[0037] Comparative Example 3 This comparative example is only different from Example 1 in that cesium fluoride is replaced with an equal amount of rubidium oxide.

[0038] Experimental Example 1 The electrodes prepared in Examples 1 to 7 and Comparative Examples 1 to 3 were used for repair surfacing of gray cast iron sintering vehicles. Before welding, the electrodes were dried at 200 °C for 1 hour. A DC welding machine was used with reverse connection. The welding current was set at 150 A. The crack resistance of the surfacing metal was tested, and the test results are shown in Table 1.

[0039] Table 1 Surfacing crack resistance test results

[0040] As can be seen from Table 1, the cracks in the surfacing metal in Examples 1 to 7 are fewer than those in Comparative Examples 1 to 3, indicating that adding yttrium oxide and lanthanum oxide to the coating and limiting the mass ratio of yttrium oxide to lanthanum oxide to 1:2 to 6 can improve the crack resistance of the electrode.

[0041] Experimental Example 2 The electrodes prepared in Examples 7 to 12 were used for repair surfacing of gray cast iron sintering vehicles. The Brinell hardness of the surfacing metal was tested according to the method in GB / T 231.1-2018 "Metallic materials - Brinell hardness test - Part 1: Test method", and the test results are shown in Table 2.

[0042] Table 2 Hardness test results of surfacing metal

[0043] As can be seen from Table 2, the Brinell hardness of Examples 9 to 12 is higher than that of Examples 7 to 8, indicating that when the mass ratio of rubidium oxide to cesium fluoride is 2 to 5:1 and 0.8 to 1.8 parts of niobium nitride are added to the coating, the hardness of the welding electrode can be increased.

[0044] The surfacing welding electrode prepared in Example 1 was used to repair the cracked sintering trolley of Shougang Mining Pellet Plant by explosive repair welding; the cracked sintering trolley of Jianlong Chengde Special Steel Co., Ltd. was repaired by explosive repair welding. After the repair, it was used well and its service life was increased by 1.5 times. The gray cast iron sintering trolley repair surfacing welding electrode was used to repair the cast iron trolley by surfacing welding, reducing energy consumption and avoiding environmental pollution during the manufacturing process. Through preheating-free and heat treatment-free surfacing welding, the near-abandoned gray cast iron trolley was restored to its original use standard and its service life was increased. It solves the problem that the trolleys in coke plants and pellet plants in China are generally unable to be repaired after damage, and has important historical significance, and its market space is very broad.

[0045] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A welding rod for repairing and surfacing welding of a gray cast iron sintering trolley, characterized in that: The invention comprises a welding core and a coating coated on the surface of the welding core, wherein the coating comprises the following raw materials in parts by weight: 40-50 parts of marble, 20-30 parts of fluorite, 4-7 parts of ferrotitanium, 2-5 parts of ferromolybdenum, 1-3 parts of high-carbon ferromanganese, 1-3 parts of ferrosilicon, 4-7 parts of rare earth oxides, 10-14 parts of metallic nickel, 1-5 parts of rubidium oxide, 0.3-2 parts of cesium fluoride and 10-20 parts of a binder; the rare earth oxides are yttrium oxide and / or lanthanum oxide.

2. The welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to claim 1, characterized in that: The rare earth oxides are yttrium oxide and lanthanum oxide.

3. The welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to claim 2, characterized in that: The mass ratio of the yttrium oxide to the lanthanum oxide is 1:2-6.

4. The welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to claim 1, characterized in that: The mass ratio of the rubidium oxide to the cesium fluoride is 2-5:

1.

5. The welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to claim 1, characterized in that: The welding core is H08A steel welding wire.

6. The welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to claim 1, characterized in that: The raw materials of the coating also include 0.8-1.8 parts of niobium nitride.

7. The welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to claim 1, characterized in that: The diameter of the welding core is 2-3 mm.

8. The welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to claim 1, characterized in that: The mass ratio of the welding core to the coating is 1:0.7~1.

9. The method for preparing a welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, passivating high carbon ferromanganese and ferrosilicon, and heat-insulating ferrotitanium, ferromolybdenum and metallic nickel; S2, after mixing the other raw materials in the coating except the binder, adding the binder, grinding and kneading into a mass, to obtain a coating; S3, coating the coating on the welding core, and obtaining the welding rod after drying.

10. The method for preparing a welding rod for repairing and surfacing welding of a gray cast iron sintering trolley according to claim 9, characterized in that: The temperature of the ferrosilicon passivation treatment is 720-750° C., and the time of the passivation treatment is 3-4 hours; The temperature of the high carbon ferromanganese passivation treatment is 300-350°C, and the time of the passivation treatment is 3-4h; The temperature of the heat preservation treatment is 150-200° C., and the time of the heat preservation treatment is 1-2 hours.

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