A surfacing electrode for crack repair

Abstract

The present invention relates to the technical field of welding materials, and provides a surfacing electrode for crack repair, which comprises a welding core and a coating covering the welding core. The coating comprises raw materials in the following weight percentages: 1% - 2% of kaolin, 20% - 30% of fluorite, 1% - 3% of quartz, 2% - 4% of rutile, 4% - 7% of ferrotitanium, 1% - 3% of high-carbon ferromanganese, 1% - 3% of ferrosilicon, 4% - 7% of cerium oxide, 15% - 17% of metallic nickel, 4% - 10% of hard phase, and the balance is marble. The welding core is an H08A steel welding wire; the hard phase is carbide. Through the above technical solution, the problems of low hardness and poor wear resistance of the surfacing weld layer in the related art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of welding materials, and specifically, to a surfacing electrode for crack repair. Background Art

[0002] A surfacing electrode is a welding material used for surfacing on the surface of a workpiece. It consists of a metal core coated with a layer of coating. The coating contains various alloying elements, slag formers, arc stabilizers and other components. During the welding process, the coating will melt to form a slag to protect the welding molten pool. At the same time, the alloying elements will transition into the molten pool and fuse with the base material to form a surfacing layer with special properties on the surface of the base material. Surfacing electrodes are widely used in the fields of mechanical manufacturing, metallurgy, electric power, etc.

[0003] The functions of surfacing electrodes mainly include repairing damaged surfaces, enhancing performance, avoiding workpiece scrapping, simplifying the repair process, etc. For workpieces with damages such as cracks, especially equipment like sintering pallets that crack and burst in an environment of alternating high temperature and cooling, surfacing electrodes can be used to fill and repair the damaged parts.

[0004] Sintering pallets are key equipment indispensable in coke plants and sintering ball plants in China and the world. They are usually made of ductile iron. Ductile iron is somewhat similar to cast steel, and using it can reduce costs and achieve good use effects. However, sintering pallets face many problems during operation. Its working nature determines that it is in a state of alternating high temperature and cooling for a long time. This long-term alternation of heat and cold will cause the ductile iron to turn white cast iron, change the extensibility and plasticity of the material, and then cause cracking in the bearing seat part of the pallet. With the long-term use of the bearing seat support part of the sintering pallet, the cracks continue to expand, and ultimately may lead to the scrapping of a sintering pallet worth millions. In addition, due to the large temperature difference between the natural temperature and the sintering temperature, cracking problems are also likely to occur.

[0005] As the main tool of each factory, once a sintering pallet is damaged and spare parts are not available, it will directly cause production stoppage or operational difficulties. However, when using traditional surfacing electrodes, even if the pallet is preheated (about 400°C) before welding and heat-treated after welding, the cracking phenomenon in the heat-affected zone is still relatively serious. At the same time, preheating before welding and heat-treatment after welding not only waste a large amount of energy, make the welding process complex, but also increase the manual labor intensity, causing greater economic losses to the enterprise.

[0006] During the sintering process, the sintering trolley needs to carry and transport a large amount of materials such as ore and coke. These materials move on the trolley and will generate continuous friction with the surface of the trolley. If the repaired part after surfacing electrode repair does not have wear resistance, during the long-term material transportation process, the repaired area is easily worn, which will affect the normal operation of the sintering trolley. A surfacing weld layer with high hardness can ensure that the repaired area will not fail again due to problems such as wear, deformation or cracking for a long time.

[0007] Therefore, developing a surfacing electrode for crack repair to improve the hardness and wear resistance of the surfacing weld layer and the anti-cracking performance of the weld layer, and applying it to the surfacing repair of cast iron trolleys not only reduces energy consumption and avoids environmental pollution during the manufacturing process, but also can restore the scrapped cast iron trolleys to their original shape and size through preheating-free and heat treatment-free surfacing, and improve their service life. It has important engineering significance for solving the problem that the trolleys in coke plants and sintering ball plants in China are generally damaged and cannot be repaired, and its market space is very broad. Summary of the Invention

[0008] The present invention provides a surfacing electrode for crack repair, which solves the problems of low hardness and poor wear resistance of the surfacing weld layer in the related art.

[0009] The technical solution of the present invention is as follows: The present invention provides a surfacing electrode for crack repair, which includes a welding core and a coating covering the welding core. The coating includes the following raw materials in weight percentages: 1% - 2% of white clay, 20% - 30% of fluorite, 1% - 3% of quartz, 2% - 4% of rutile, 4% - 7% of ferrotitanium, 1% - 3% of high-carbon ferromanganese, 1% - 3% of ferrosilicon, 4% - 7% of cerium oxide, 15% - 17% of metallic nickel, 4% - 10% of hard phase, and the balance is marble. The welding core is an H08A steel welding wire;

[0010] The hard phase is carbide.

[0011] As a further technical solution, the carbide includes one or more of tungsten carbide, boron carbide, and titanium carbide.

[0012] As a further technical solution, the mass ratio of the metallic nickel to the hard phase is 3:1 - 2.

[0013] In the present invention, by limiting the mass ratio of metallic nickel and carbide, the strengthening effect between the two is enhanced, thereby improving the hardness and wear resistance of the surfacing layer.

[0014] As a further technical solution, when the carbide is composed of tungsten carbide and titanium carbide, the mass ratio of the tungsten carbide to the titanium carbide is 2 - 3:1.

[0015] In the present invention, tungsten carbide and titanium carbide are added simultaneously as carbides. By limiting the mass ratio of the two, the synergistic effect of the two is exerted, a more reasonable hard phase distribution is formed, the bonding strength between the two and metallic nickel is enhanced, and the hardness and wear resistance of the surfacing layer are further improved.

[0016] As a further technical solution, the tungsten carbide is supported tungsten carbide, the carrier of the supported tungsten carbide is mesoporous silica, and the active ingredient is tungsten carbide.

[0017] In the present invention, mesoporous silica is used as the carrier to support tungsten carbide, improve the dispersibility of tungsten carbide, enhance the stability of tungsten carbide, and further improve the hardness and wear resistance of the surfacing layer.

[0018] As a further technical solution, in the raw materials of the supported tungsten carbide, the mass ratio of the carrier to the active ingredient is 10:1 to 2.

[0019] As a further technical solution, the preparation method of the supported tungsten carbide includes the following steps: dispersing the precursor of tungsten carbide in a solvent, adding mesoporous silica, drying uniformly after dispersion, and obtaining the supported tungsten carbide through a carbonization reaction.

[0020] As a further technical solution, the diameter of the mesoporous silica is 100 to 400 nm.

[0021] As a further technical solution, the precursor of tungsten carbide includes tungsten oxide and graphite, and the molar ratio of tungsten oxide to graphite is 1:1.

[0022] As a further technical solution, the temperature of the carbonization reaction is 1200 to 1300 °C, and the heat preservation time is 2 to 4 h.

[0023] As a further technical solution, the ferrosilicon is purified ferrosilicon, the purification temperature is 720 to 750 °C, and the heat preservation time is 0.8 to 1.2 h.

[0024] As a further technical solution, the high-carbon ferromanganese is purified high-carbon ferromanganese, the purification temperature is 300 to 350 °C, and the heat preservation time is 0.8 to 1.2 h.

[0025] The present invention also provides a preparation method of a surfacing electrode for crack repair, including the following steps: weighing the raw materials according to the weight percentage of the coating, mixing uniformly, pressing and coating on the welding core with a binder, and drying and polishing to obtain the surfacing electrode for crack repair.

[0026] As a further technical solution, the drying temperature is 250 to 300 °C.

[0027] As a further technical solution, the binder includes one or two of water glass and clay.

[0028] As a further technical solution, the iron content in the ferrotitanium is 30 wt% to 80 wt%, the carbon content in the ferromanganese is 6 wt% to 7 wt%, and the silicon content in the ferrosilicon is 70 wt% to 75 wt%.

[0029] The working principle and beneficial effects of the present invention are as follows:

[0030] In the present invention, ore substances such as marble, fluorite, and quartz and alloy materials such as ferrotitanium and ferromanganese are used as the main materials, and auxiliary materials such as metallic nickel and cerium oxide are added. On this basis, carbide is added as the hard phase to prepare the electrode coating. The carbide improves the hardness of the surfacing layer by hindering the movement of dislocations and improves the wear resistance of the surfacing layer by resisting abrasive wear. Specific embodiments

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of the present invention.

[0032] In the following examples and comparative examples:

[0033] Marble: The particle size is 400 mesh;

[0034] Fuller's earth: The particle size is 400 mesh;

[0035] Quartz: The particle size is 325 mesh;

[0036] Rutile: The average particle size is 0.3 μm;

[0037] Ferrotitanium: The iron content is 40 wt%;

[0038] Ferromanganese: The carbon content is 7 wt%;

[0039] Ferrosilicon: The silicon content is 75 wt%;

[0040] Cerium oxide: The average particle size is 1.5 μm;

[0041] Metallic nickel: The purity is 99.99%;

[0042] Mesoporous silica: The diameter is 300 nm;

[0043] Tungsten oxide: The average particle size is 40 nm;

[0044] Graphite: The average particle size is 10 nm;

[0045] Water glass: potassium water glass, with an effective content of 40 wt% and a modulus of 2.6 - 2.8 m;

[0046] Chromium boride: average particle size of 1 μm;

[0047] Coating: thickness of 1 mm;

[0048] Welding core: H08A steel welding wire, with a diameter of 2 mm.

[0049] Example 1

[0050] A surfacing electrode for crack repair, comprising a welding core and a coating wrapped around the welding core. The coating comprises raw materials in the following weight percentages:

[0051] China clay 1%, fluorite 20%, quartz 1%, rutile 2%, ferrotitanium 4%, high-carbon ferromanganese 1%, ferrosilicon 1%, cerium oxide 4%, metallic nickel 15%, hard phase 4%, the balance being marble, where the hard phase is tungsten carbide;

[0052] The welding core is H08A steel welding wire;

[0053] Purify ferrosilicon at a temperature of 720 °C for a holding time of 1.2 h, purify high-carbon ferromanganese at a temperature of 300 °C for a holding time of 1.2 h. Prepare the raw materials for the coating according to the above weight percentages, mix them evenly using a roller mill, add water glass and stir evenly, extrude the electrode using an electrode coating machine, dry the electrode at 250 °C, and then perform head grinding and tail grinding to obtain the surfacing electrode for crack repair.

[0054] Example 2

[0055] A surfacing electrode for crack repair, comprising a welding core and a coating wrapped around the welding core. The coating comprises raw materials in the following weight percentages:

[0056] China clay 1.5%, fluorite 22.7%, quartz 1.7%, rutile 3.8%, ferrotitanium 5.8%, high-carbon ferromanganese 2.5%, ferrosilicon 1.6%, cerium oxide 5.3%, metallic nickel 16%, hard phase 5%, the balance being marble, where the hard phase is tungsten carbide;

[0057] The welding core is H08A steel welding wire;

[0058] Purify ferrosilicon at a temperature of 730 °C for a holding time of 1 h, purify high-carbon ferromanganese at a temperature of 320 °C for a holding time of 1 h. Prepare the raw materials for the coating according to the above weight percentages, mix them evenly using a roller mill, add water glass and stir evenly, extrude the electrode using an electrode coating machine, dry the electrode at 280 °C, and then perform head grinding and tail grinding to obtain the surfacing electrode for crack repair.

[0059] Example 3

[0060] A surfacing electrode for crack repair, comprising a welding core and a coating wrapped around the welding core. The coating comprises raw materials in the following weight percentages:

[0061] Fuller's earth 2%, fluorite 30%, quartz 3%, rutile 4%, ferrotitanium 7%, high-carbon ferromanganese 3%, ferrosilicon 3%, cerium oxide 7%, metallic nickel 17%, hard phase 5%, and the balance is marble, wherein the hard phase is tungsten carbide;

[0062] The welding core is an H08A steel welding wire;

[0063] Purify ferrosilicon at a temperature of 750 °C for 0.8 h, purify high-carbon ferromanganese at a temperature of 350 °C for 0.8 h. Prepare the raw materials of the coating according to the above weight percentages, mix them evenly by a roller compactor, add sodium silicate and stir evenly, extrude the electrode with an electrode coating machine, dry the electrode at 300 °C, and then grind the head and tail to obtain a surfacing electrode for crack repair.

[0064] Example 4

[0065] Compared with Example 1, the difference in Example 4 is that tungsten carbide is replaced with an equal amount of titanium carbide.

[0066] Example 5

[0067] Compared with Example 1, the difference in Example 5 is that the addition amount of the hard phase is 5%.

[0068] Example 6

[0069] Compared with Example 1, the difference in Example 6 is that the addition amount of the hard phase is 10%.

[0070] Example 7

[0071] Compared with Example 6, the difference in Example 7 is that the hard phase is composed of tungsten carbide and titanium carbide with a mass ratio of 2:1.

[0072] Example 8

[0073] Compared with Example 6, the difference in Example 8 is that the hard phase is composed of tungsten carbide and titanium carbide with a mass ratio of 3:1.

[0074] Example 9

[0075] The preparation method of tungsten carbide supported includes the following steps: Disperse 1 part of the precursor in 100 parts of ethanol, add 10 parts of mesoporous silica, dry it after ultrasonic treatment for 1 h, carry out a carbonization reaction at a temperature of 1200 °C for 3 h to obtain tungsten carbide supported, wherein the precursor is composed of tungsten oxide and graphite with a molar ratio of 1:1.

[0076] Compared with Example 8, Example 9 is different in that tungsten carbide is replaced with an equal amount of supported tungsten carbide obtained by the above preparation method.

[0077] Example 10

[0078] Compared with Example 9, Example 10 is different in that the addition amount of the precursor is 2 parts.

[0079] Comparative Example 1

[0080] Compared with Example 1, Comparative Example 1 is different in that no hard phase is added.

[0081] Comparative Example 2

[0082] Compared with Example 1, Comparative Example 2 is different in that tungsten carbide is replaced with an equal amount of chromium boride.

[0083] The surfacing electrodes for crack repair prepared in Examples 1 to 10 and Comparative Examples 1 to 2 were used to repair the sintering trolley. Before welding, the electrodes were dried at 300 °C for 1 h to remove the crystal water in the coating. A DC welding machine was used with reverse connection. The welding current was 180 A and the welding voltage was 80 V. It was not necessary to preheat the trolley part before welding, and no heat treatment was required after welding. The repaired sintering trolley was tested according to the following method:

[0084] 1. Brinell hardness: According to the single-point determination test method specified in GB / T 2654-2008 "Test Method for Hardness of Welded Joints", the Brinell hardness of the test sample was measured.

[0085] 2. Wear weight loss: The surfacing layer obtained by surfacing was made into a cylinder with φ32×10 mm and tested on an MMW-1A vertical universal friction and wear testing machine. The wear time was 10 min, and the mass difference before and after wear was the wear weight loss.

[0086] The test results are shown in the following table:

[0087] Table 1 Test results of the application performance of the surfacing electrodes for crack repair prepared in Examples 1 to 10 and Comparative Examples 1 to 2

[0088]

[0089] Compared with Comparative Examples 1 and 2, tungsten carbide was added as the hard phase in Example 1. As a result, the Brinell hardness of Example 1 was better than that of Comparative Examples 1 and 2, and the wear weight loss was less than that of Comparative Examples 1 and 2, indicating that the addition of the hard phase and the hard phase being carbide can improve the hardness and wear resistance of the surfacing layer.

[0090] Compared with Examples 1 and 4, in Examples 7 and 8, tungsten carbide and titanium carbide are added simultaneously as hard phases. As a result, the Brinell hardness of Examples 7 and 8 is better than that of Examples 1 and 4, and the wear weight loss is less than that of Examples 1 and 4, indicating that tungsten carbide and titanium carbide play a synergistic role and can improve the hardness and wear resistance of the surfacing layer.

[0091] Compared with Example 8, in Examples 9 and 10, tungsten carbide supported by mesoporous silica is added. As a result, the Brinell hardness of Examples 9 and 10 is better than that of Example 8, and the wear weight loss is less than that of Example 8, indicating that after tungsten carbide is supported by mesoporous silica, the hardness and wear resistance of the obtained surfacing layer are better.

[0092] 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 within the protection scope of the present invention.

Claims

1. A surfacing electrode for explosion repair, characterized in that, It includes a welding core and a coating covering the welding core. The coating comprises raw materials in the following weight percentages: 1% - 2% of bolus alba, 20% - 30% of fluorite, 1% - 3% of quartz, 2% - 4% of rutile, 4% - 7% of ferrotitanium, 1% - 3% of high-carbon ferromanganese, 1% - 3% of ferrosilicon, 4% - 7% of cerium oxide, 15% - 17% of metallic nickel, 4% - 10% of hard phase, and the balance is marble. The welding core is an H08A steel welding wire; the hard phase is carbide; The carbide includes one or more of tungsten carbide, boron carbide, and titanium carbide.

2. The surfacing electrode for crack repair according to claim 1, characterized in that, The mass ratio of the metallic nickel to the hard phase is 3:1 - 2.

3. A surfacing electrode for crack repair according to claim 1, characterized in that, When the carbide consists of tungsten carbide and titanium carbide, the mass ratio of the tungsten carbide to the titanium carbide is 2 - 3:

1.

4. A surfacing electrode for crack repair according to claim 3, characterized in that, The tungsten carbide is supported tungsten carbide, the carrier of the supported tungsten carbide is mesoporous silica, and the active ingredient is tungsten carbide.

5. A surfacing electrode for explosion repair according to claim 4, characterized in that, In the raw materials of the supported tungsten carbide, the mass ratio of the carrier to the active ingredient is 10:1 - 2.

6. A surfacing electrode for crack repair according to claim 4, characterized in that, The preparation method of the supported tungsten carbide includes the following steps: dispersing a precursor of tungsten carbide in a solvent, adding mesoporous silica, drying after uniform dispersion, and obtaining the supported tungsten carbide through a carbonization reaction.

7. A surfacing electrode for crack repair according to claim 6, characterized in that, The diameter of the mesoporous silica is 100 - 400 nm.

8. A surfacing electrode for crack repair according to claim 6, characterized in that, The precursor of the tungsten carbide includes tungsten oxide and graphite, and the molar ratio of the tungsten oxide to the graphite is 1:

1.

9. A surfacing electrode for crack repair according to claim 6, characterized in that, The temperature of the carbonization reaction is 1200 - 1300 °C, and the heat preservation time is 2 - 4 h.

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