A sintering trolley, wind wheel roller axle nodular cast iron structure welding repair welding wire and its use method

Abstract

The application provides a sintering trolley, a wind wheel roller shaft, a nodular cast iron structure welding repair welding wire and a use method thereof. The welding wire comprises the following components in percentage by mass: C: 0.03-0.07%, Cr: 10-12%, Mn: 8-10%, Si: 0.2-0.4%, Ni: 32-36%, Nb: 0.6-0.8%, and the balance comprises Fe and inevitable impurities; the use method steps comprise: welding repair is performed on a defect position of a sintering trolley structure or a wind wheel roller shaft structure. The repaired area is well formed, and welding defects such as cracks and inclusions do not exist, the repaired component can serve for a long time, and high-efficiency, high-quality and low-cost welding repair of the sintering trolley and the wind wheel roller shaft is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of spheroidal graphite cast iron welding repair materials, and particularly relates to a spheroidal graphite cast iron structure welding repair welding wire for sintering trolleys and wind wheel rollers and a use method thereof. BACKGROUND

[0002] The sintering trolley is a core component of a sintering furnace of ore smelting equipment, and is mainly used for sintering powder ore into blocks for use in a next step of blast furnace. The sintering trolley has a poor working environment and high performance requirements, needs to serve for a long time under a cyclic thermal shock condition, and cannot leak air. Similarly, the wind wheel roller is a typical load transmission structure, and is extremely prone to problems such as wear and cracking during bearing of a large load, and needs to be restored in shape and function through a repair technology. The spheroidal graphite cast iron is a main material of the sintering trolley and the wind wheel roller, and has excellent strength, toughness, high-temperature resistance and good casting performance. However, after long-term service, the spheroidal graphite cast iron structure of the sintering trolley and the wind wheel roller is prone to defects such as wear, cracking and thermal corrosion pits, which leads to equipment failure, and direct replacement greatly increases the cost. The welding repair method can significantly reduce the operation cost and prolong the service life of the equipment.

[0003] However, the spheroidal graphite cast iron has high carbon content, poor plasticity and poor uniformity of the structure, which makes the weldability poor. Welding of the spheroidal graphite cast iron is a recognized problem in the industry, and the repair is often more difficult than welding. In addition, the position of the repair area is random, and the shape of the repair area is often a closed area, the repair stress is large, and the repair is extremely prone to failure. At present, in the welding and repair of the spheroidal graphite cast iron structure, the existing technology often uses a cast iron electrode with high Ni content, and through opening a groove, multi-layer and multi-pass welding repair, and accurate control of the interlayer temperature, the length of each weld and the welding current, to prevent cracking and other problems in the welding process. However, the welding wire used has high cost, the welding process is complex, and the welding efficiency is low. Therefore, how to ensure the efficient, high-quality and low-cost welding repair of the sintering trolley and the wind wheel roller has become a technical problem to be solved. SUMMARY

[0004] At least in view of the technical problems mentioned in the background, the application aims to provide a spheroidal graphite cast iron structure welding repair welding wire for sintering trolleys and wind wheel rollers and a use method thereof.

[0005] The application adopts the following technical solutions.

[0006] The application discloses a welding wire for repairing sintering trolley and wind wheel roller structure made of nodular cast iron, which comprises the following components in percentage by mass: C: 0.03-0.07%, Cr: 10-12%, Mn: 8-10%, Si: 0.2-0.4%, Ni: 32-36%, Nb: 0.6-0.8%, and the balance of Fe and inevitable impurities.

[0007] Further, the welding wire further comprises the following components: Ga: 0.02-0.05%, In: 0.01-0.03%, and RE: <0.08%.

[0008] Preferably, the welding wire is composed of the following components in percentage by mass: C: 0.05%, Cr: 11%, Mn: 9%, Si: 0.3%, Ni: 34%, Nb: 0.7%, Ga: 0.03%, In: 0.02%, RE: 0.06%, and the balance of Fe and inevitable impurities.

[0009] In the application, the welding wire is used to obtain a welding seam mainly comprising Ni-Fe and Ni-Nb solid solution, NbC compound and M23C6 compound.

[0010] In the application, the welding wire has a cladding layer and a powder filling layer, the cladding layer is made of 304 stainless steel thin strip with a wall thickness of 0.4 mm and a width of 12 mm, and the powder filling layer is made of a mixture of high-purity electrolytic Mn powder, pure electrolytic Ni powder, Nb-Fe powder, Ga-Fe powder, Mn-In powder and Y2O3 powder, and the powder filling rate is 35-40%.

[0011] A method for using the welding wire, which comprises the following steps:

[0012] Step 1, mechanically polishing and cleaning the surface oxide layer of the defect part of the sintering trolley structure or the wind wheel roller structure until the metal luster is exposed, so as to obtain a repaired area;

[0013] Step 2, placing the welding wire and adopting MIG welding method to weld the repaired area, so as to obtain a welding seam; wherein the welding process parameters are as follows: current 183-203 A, voltage 18.7-20.3 V, 99.9% pure Ar gas protection, welding speed 7-9 mm / s and wire feeding speed 8.7-10.4 mm / s;

[0014] Step 3, mechanically processing the welding seam, so that the sintering trolley structure or the wind wheel roller structure can be directly installed and used.

[0015] Preferably, the material of the sintering trolley structure and the wind wheel roller structure is nodular cast iron, which is composed of the following components in percentage by mass: C: 3.5-3.8%, Si: 2.2-2.7%, Mn <0.5%, P <0.07%, S <0.02%, Mg: 0.03-0.06%, and the balance of Fe and inevitable impurities.

[0016] Beneficial effects: the welding wire of the present application obtains a welding seam only containing Ni-Fe and Ni-Nb solid solution, NbC compound and M 23 C6 compound, no excess brittle phase, good crack resistance and mechanical properties; the repaired area has good forming, no welding defects such as cracks and inclusions, and can realize long-term service of the repaired part; the present application does not need preheating during welding, does not need to control the temperature between the welding layers during welding, does not need annealing treatment after repair, can be directly installed and applied after mechanical processing, and realizes high efficiency, high quality and low cost welding repair of the sintering trolley and the wind wheel roller. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Balance solidification phase precipitation diagram of the welding wire in Example 1;

[0018] Figure 2 Wind wheel roller structure before and after repair of the welding wire in Example 2;

[0019] Figure 3 Mechanical properties of the repaired area perpendicular to the direction of Example 3;

[0020] Figure 4 Mechanical properties of the repaired area parallel to the direction of Example 3. DETAILED DESCRIPTION

[0021] The technical solutions in the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0022] Example 1: A welding wire composed of the following components by mass percentage: C: 0.05%, Cr: 11%, Mn: 9%, Si: 0.3%, Ni: 34%, Nb: 0.7%, Ga: 0.03%, In: 0.02%, RE: 0.06%, with the balance being Fe and unavoidable impurities. In this embodiment: the welding wire has a cladding layer and a powder filler layer. The cladding layer is made of 304 stainless steel strip with a wall thickness of 0.4 mm and a width of 12 mm. When preparing the welding wire: the powder filler layer is a mixture containing high-purity electrolytic Mn powder (accounting for 22.33% of the total weight of the powder filler layer), pure electrolytic Ni powder (accounting for 75.26% of the total weight of the powder filler layer), Nb-Fe powder (accounting for 1.87% of the total weight of the powder filler layer), Ga-Fe powder (accounting for 0.08% of the total weight of the powder filler layer), Mn-In powder (accounting for 0.05% of the total weight of the powder filler layer), and Y2O3 powder (accounting for 0.16% of the total weight of the powder filler layer), with a powder filling rate of 37.5%.

[0023] The equilibrium solidification phase precipitation diagram of the welding wire in this embodiment is as follows: Figure 1 As shown in the figure, the equilibrium solidification structure of the welding wire mainly consists of Ni-Fe and Ni-Nb solid solutions, NbC compounds, and M. 23 The absence of excess brittle phases in the C6 compound indicates that the weld obtained after welding with this wire has excellent crack resistance and good mechanical properties.

[0024] Example 2: Using the welding wire from Example 1 to repair defects in the wind turbine roller structure (such as...) Figure 2 The repair was carried out as shown. The material of the wind turbine roller structure is ductile iron, which is composed of the following components by mass percentage (C: 3.6%, Si: 2.5%, Mn < 0.5%, P < 0.07%, S < 0.02%, Mg: 0.05%, balance Fe and unavoidable impurities). The steps are as follows:

[0025] Step 1: Mechanically grind and clean the surface oxide layer of the defective parts of the wind turbine roller structure until the metallic luster is exposed, and obtain the area to be repaired;

[0026] Step 2: Position the welding wire and weld the area to be repaired using the MIG welding method to obtain a weld. The welding process parameters are: current 201A, voltage 20V, 99.9% pure Ar gas protection, welding speed 8mm / s, and wire feed speed 9.5mm / s.

[0027] Step 3, perform machining on the obtained weld (e.g., Figure 2 As shown in the figure, the wind turbine roller structure can be directly installed and used.

[0028] Example 3: The welding wire in Example 1 is used to repair the defect site of the sintering trolley wall plate structure. The material of the sintering trolley wall plate structure is nodular cast iron, which is composed of the following components in mass percentage (C: 3.8%, Si: 2.3%, Mn < 0.5%, P < 0.07%, S < 0.02%, Mg: 0.04%, the balance being Fe and unavoidable impurities), and the steps are as follows:

[0029] Step 1: The defect site of the sintering trolley wall plate structure is mechanically polished and the surface oxide layer is cleaned until the metal luster is exposed, obtaining a repair area;

[0030] Step 2: The welding wire is placed in position, and the MIG welding method is used to weld the obtained repair area, obtaining a weld; wherein the welding process parameters are: current 203A, voltage 19.5V, 99.9% pure Ar gas protection, welding speed 8.5mm / s, wire feeding speed 10mm / s;

[0031] Step 3: The obtained weld is mechanically processed (polished flat), and the sintering trolley wall plate structure can be directly installed and used.

[0032] Comparative Example: A commercially available ASM dissimilar steel electrode produced in the United States (currently there is no full nodular cast iron welding wire on the market that meets the corresponding requirements, so only the electrode can be selected), C content 0.38%, Mn content 11.4%, Si content 0.14%, Ni content 43.9%, Nb content 0.7%, Cu content 0.09, Cr content 6.6%, P content 0.004%, S content 0.004, balance Fe.

[0033] A certain enterprise's ore smelting workshop used to use imported electrodes (i.e. the electrode in the comparative example) to repair the sintering trolley wall plate structure, and the average service life after repair was about 12.5 months. After the sintering trolley wall plate structure is repaired using the scheme in Example 3 (the defect area, pit area and depth are processed to the same size), the service life after repair has exceeded 13 months. For the wind wheel roller structure in Example 2, it cannot be repaired at present because the only option on the market is the ASM dissimilar steel electrode produced in the United States, which will directly cause the wind wheel roller to deform and be scrapped; while using the scheme in Example 2, the repair and reuse of the wind wheel roller are realized, and the service life has exceeded 5 months.

[0034] RT detection and penetration detection are performed on the repair areas in Example 2 and Example 3, and the results show that the repair areas are free of cracks, slag inclusions, pores and incomplete fusion defects, meeting the use requirements.

[0035] Mechanical property tests are performed on the repair area in Example 3, and the results are shown in Figure 3 and Figure 4As shown in the figure, the average tensile strength obtained in two directions reaches 450 MPa, about 90% of the strength of the base material (ductile cast iron), meeting the performance use requirements of the repaired ductile cast iron structure.

[0036] In the present application, the welding wire with specific component ratio and structure is adopted, and the cost is significantly reduced compared with the commercially available welding rod with basically the same performance (i.e. the American dissimilar steel welding rod, C accounts for 0.38%, Mn accounts for 11.4%, Si accounts for 0.14%, Ni accounts for 43.9%, Nb accounts for 0.7%, Cu accounts for 0.09, Cr accounts for 6.6%, P accounts for 0.004%, S accounts for 0.004, and the balance is Fe). Not only the strength, wear resistance and temperature resistance of the welding wire are guaranteed, but also the cracking during welding is prevented, and the domestic substitution of the ductile cast iron welding material is realized.

[0037] The welding seam obtained by the welding wire of the embodiment basically only has Ni-Fe and Ni-Nb solid solution, NbC compound and M23C6 compound, and there is no excess brittle phase, etc. phase, and has good crack resistance and mechanical properties; the repaired area after the embodiment scheme is repaired is well formed, and there is no crack, inclusion and other welding defects, and the long-term service of the repaired part can be realized, the welding process does not need preheating, the interlayer temperature during the welding process does not need to be controlled, and the annealing treatment is not needed after the repair is completed, and the repaired part can be directly installed and applied after mechanical processing, realizing the high-efficiency, high-quality and low-cost welding repair of the sintering trolley and the wind wheel roller.

Claims

1. A welding wire for welding repair of ductile iron structures such as sintering trolleys and impeller rollers, comprising the following components by mass percentage: C: 0.03-0.07%, Cr: 10-12%, Mn: 8-10%, Si: 0.2-0.4%, Ni: 32-36%, Nb: 0.6-0.8%, with the balance including Fe and unavoidable impurities.

2. The welding wire according to claim 1, characterized in that, It also includes components Ga: 0.02-0.05%, In: 0.01-0.03%, RE < 0.08%.

3. The welding wire according to claim 1 or 2, characterized in that, C: 0.05%, Cr: 11%, Mn: 9%, Si: 0.3%, Ni: 34%, Nb: 0.7%, Ga 0.03%, In 0.02%, RE 0.06%.

4. The welding wire according to claim 1, characterized in that: The weld obtained after welding with the aforementioned welding wire mainly contains Ni-Fe and Ni-Nb solid solutions, NbC compounds, and M23C6 compounds.

5. The welding wire according to any one of claims 1-4, characterized in that: The welding wire has a cladding layer and a powder filling layer. The cladding layer is made of 304 stainless steel strip with a wall thickness of 0.4 mm and a width of 12 mm. The powder filling layer is a mixture of high-purity electrolytic Mn powder, pure electrolytic Ni powder, Nb-Fe powder, Ga-Fe powder, Mn-In powder and Y2O3 powder, with a powder filling rate of 35-40%.

6. A method of using the welding wire as described in any one of claims 1-5, characterized in that the steps... include: Step 1: Mechanically grind and clean the surface oxide layer of the defective parts of the sintering trolley structure or wind turbine roller structure until the metallic luster is exposed, and obtain the area to be repaired. Step 2: Position the welding wire and weld the area to be repaired using the MIG welding method to obtain a weld. The welding process parameters are: current 183-203A, voltage 18.7-20.3V, 99.9% pure Ar gas protection, welding speed 7-9mm / s, and wire feed speed 8.7-10.4mm / s. Step 3: Machining the obtained weld seam allows for direct installation and use on the sintering trolley structure or wind turbine roller structure.

7. The method of using the welding wire according to claim 6, characterized in that: The sintering trolley structure and the impeller roller structure are made of ductile iron, which is composed of the following components by mass percentage: C: 3.5-3.8%, Si: 2.2-2.7%, Mn<0.5%, P<0.07%, S<0.02%, Mg: 0.03-0.06%, RE<0.06%.

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