Metal powder core type welding wire and method for surface modification of furnace discharging roller way of heating furnace

Abstract

The invention discloses a metal powder core type welding wire and method for surface modification of a furnace discharging table of a heating furnace, the metal powder core type welding wire comprises a powder core and a welding skin, the powder core is composed of the following components of, by mass, 35%-55% of Ni, 15.0%-17.0% of Cr, 15%-19% of Fe, 4.0%-5.0% of Nb, 2.8%-4.3% of Mo, 5.0%-15.0% of TiC, 0.5%-2.25% of Zr and 1.5%-2.5% of B, and the sum of the mass percentages of the components is 100%; the welding skin is a nickel-based alloy strip; the filling amount of the powder core powder in the metal powder core type welding wire ranges from 18 wt.% to 25 wt.%. The welding wire can be used for preparing a nickel-based alloy cladding layer on a heating furnace discharge roller way, and the hardness, wear resistance and corrosion resistance of the heating furnace discharge roller way are improved. The invention further discloses a preparation method of the metal powder core type welding wire and a method for modifying the surface of a furnace discharging roller way of a heating furnace.

Description

Technical Field

[0001] The invention belongs to the technical field of surface engineering of low-carbon steel materials, and in particular relates to a metal powder core welding wire and a method for surface modification of a roller table of a heating furnace in a steel rolling mill. Background Art

[0002] The roller table of the heating furnace in the rolling mill is a key process link, which is used to transfer the heated billet from the heating furnace to the rolling mill for subsequent rolling processing. The roller table is composed of a series of rollers, which are usually made of high-temperature resistant materials and can withstand the weight and heat radiation of the high-temperature billet as well as the wear and tear generated during the transmission. However, the roller table made of high-temperature materials is expensive and costly, and the cast roller table is prone to defects such as pores and cracks. These problems greatly increase the production cost of steel. Summary of the invention

[0003] The first object of the present invention is to provide a metal powder cored welding wire for surface modification of a heating furnace discharge roller, which can be used to prepare a nickel-based alloy cladding layer on the heating furnace discharge roller to improve the hardness, wear resistance and high temperature resistance of the heating furnace discharge roller.

[0004] The second object of the present invention is to provide a method for preparing a metal powder cored welding wire for surface modification of a roller table out of a heating furnace.

[0005] The third object of the present invention is to provide a method for modifying the surface of a roller table of a heating furnace.

[0006] The first technical solution adopted by the present invention is a metal powder cored welding wire for surface modification of a heating furnace roller table, comprising a powder core and a weld skin, wherein the powder core is composed of the following components by mass percentage: Ni 35%-55%, Cr 15.0%-17.0%, Fe 15%-19%, Nb4.0%-5.0%, Mo 2.8%-4.3%, TiC 5.0%-15.0%, Zr 0.5%-2.25%, and B 1.5-2.5%, and the sum of the mass percentages of the above components is 100%; the weld skin is a nickel-based alloy strip; and the filling amount of the powder core powder in the metal powder cored welding wire is 18wt.%-25wt.%.

[0007] The nickel-based alloy strip is Inconel 625 alloy.

[0008] The second technical solution adopted by the present invention is a method for preparing a metal powder cored welding wire for surface modification of a heating furnace roller table, and the specific implementation steps are as follows: Step 1: Weigh the following powder cores by mass percentage: Ni 35%-55%, Cr 15.0%-17.0%, Fe 15%-19%, Nb4.0%-5.0%, Mo 2.8%-4.3%, TiC 5.0%-15.0%, Zr 0.5%-2.25%, B 1.5-2.5%. The sum of the mass percentages of the above components is 100%; Step 2: The powder core powder weighed in step 1 is evenly mixed and placed in a tube furnace and argon gas is continuously introduced, the furnace temperature is set to 120°C~150°C, and the drying time is 1h~2h; the dried powder core is placed in a powder mixer for sufficient mixing, and the mixing time is 1h~3h; Step 3: Roll the Inconel 625 alloy strip on a wire drawing machine, wrap the powder core prepared in step 2 in the Inconel 625 alloy strip, and close the alloy strip through a die. Use the die to reduce the diameter of the welding wire to 1.6 mm, and remove impurities on the surface of the welding wire; the filling amount of the powder core powder in the metal powder core welding wire is 18wt.%-25wt.%.

[0009] The third technical solution adopted by the present invention is a method for modifying the surface of a heating furnace roller table, characterized in that the above-mentioned welding wire is clad on the surface of the heating furnace roller table, and a cladding layer of metal is prepared by surfacing welding on the surface of the heating furnace roller table, wherein the cladding current is 100A~140A, the cladding speed is 0.15m / min~0.25m / min, and a volume fraction of 50% nitrogen and 50% argon is introduced during cladding. The welding method is a multi-pass deposition welding method, and the overlap between the previous and subsequent cladding passes is 30%-40%.

[0010] When the cladding layer metal is prepared by surfacing welding on the surface of the roller table out of the heating furnace, the welding process adopts automatic TIG welding. During the TIG cladding process, 50% N2 and 50% Ar gas with a volume fraction are used to protect the welding area, which can effectively prevent the molten metal from generating spatter and pores.

[0011] The beneficial effects of the present invention are: (1) The present invention adopts an automatic TIG welding cladding method to perform cladding on the surface of Q345 low alloy steel. The welding process adopts inert gas protection to effectively prevent defects such as oxidation, impurities and pores. The welding speed is fast and efficient, with less spatter and no pores. By cladding a nickel-based alloy layer on the surface of the substrate, the performance and service life of the workpiece are improved.

[0012] (2) The metal powder core welding wire used in the present invention is easy to operate, has excellent welding effect, reduces material loss, and saves costs. This welding wire can be applied to the roller table of the heating furnace made of Q345 low alloy steel, and by preparing the nickel-based alloy cladding layer, the hardness, wear resistance and corrosion resistance of the shaft sleeve are significantly improved.

[0013] (3) In order to improve the surface performance of parts, a cladding layer is often prepared on the surface to form a protective layer to enhance the surface performance. Arc cladding technology has strong applicability and high cladding efficiency. It can form a uniform and dense cladding layer to improve adhesion and hardness. Metal powder cored welding wire is easy to prepare and can accurately provide the required components to prevent defects such as oxidation and pores. The nickel-based cladding layer of the metal powder cored welding wire in the present invention has excellent performance on the surface of the heating furnace roller, can be well bonded to the substrate, and has excellent surface performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a macroscopic surface morphology of a single-pass cladding experiment of the metal powder cored welding wire prepared in Example 1 of the present invention; Figure 2 is a microstructure diagram of the cladding layer prepared in Example 1 of the present invention; Figure 3 This is a macroscopic surface morphology of a single-pass cladding experiment of the metal powder cored welding wire prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0015] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] The first technical solution adopted by the present invention is a metal powder cored welding wire for surface modification of a heating furnace roller table, comprising a powder core and a weld skin, wherein the powder core is composed of the following components by mass percentage: Ni 35%-55%, Cr 15.0%-17.0%, Fe 15%-19%, Nb4.0%-5.0%, Mo 2.8%-4.3%, TiC 5.0%-15.0%, Zr 0.5%-2.25%, and B 1.5-2.5%, and the sum of the mass percentages of the above components is 100%; the weld skin is a nickel-based alloy strip; and the filling amount of the powder core powder in the metal powder cored welding wire is 18wt.%-25wt.%.

[0017] The nickel-based alloy strip is Inconel 625 alloy.

[0018] The roles of various raw materials in welding wire are as follows: (1) The Ni element has good corrosion resistance, which enables Inconel 625 alloy to have excellent corrosion resistance in high temperature, high pressure and corrosive environment. By controlling the content of Ni element and heating treatment conditions, the grain refinement of the alloy can be effectively promoted.

[0019] (2) Cr can form strengthening phases with other elements. These strengthening phases can effectively inhibit lattice slip and grain boundary slip, and improve the high temperature strength and deformation resistance of the alloy. Cr can form stable compounds with Nb and other elements, such as Ni3 (Nb, Cr), etc. These compounds can inhibit the precipitation phase transformation of the alloy at high temperature and improve the thermal stability of the alloy.

[0020] (3) Ti element can form a strengthening phase with Nb, which can improve the strength and hardness of the alloy. During the cladding process, N2 in the protective gas reacts with Ti to form TiN, which improves the wear resistance and high temperature resistance of the cladding layer.

[0021] TiC, with the increase of TiC content, the microstructure gradually changes from the morphology of columnar dendrites in the middle of the melt channel and equiaxed crystals at the junction of the melt channel to the morphology composed of substructures such as cellular equiaxed crystals. This grain refinement effect helps to improve the strength and hardness of the material. Part of the TiC decomposes and the Ti element reacts with nitrogen.

[0022] (4) In Inconel 625 alloy, the main function of iron (Fe) is to enhance the mechanical properties and corrosion resistance of the material. Iron increases the strength and hardness of the alloy and forms a solid solution with elements such as nickel (Ni) and chromium (Cr), thereby significantly improving the comprehensive mechanical properties of the material. The addition of iron not only enhances the corrosion resistance of the alloy, but also improves the strength and hardness of the material through the solid solution strengthening mechanism, making it have better performance under various environmental conditions.

[0023] (5) The main function of molybdenum (Mo) in the alloy is to improve its strength and hardness. Molybdenum enhances the tensile strength and toughness of the alloy by forming a strengthening phase with other alloying elements. Specifically, molybdenum significantly improves the overall mechanical properties of the alloy through the grain boundary strengthening mechanism. This strengthening effect not only enhances the tensile strength of the alloy, but also improves its toughness, making the alloy perform better when subjected to stress.

[0024] (6) In Inconel 625 alloy, the main function of niobium (Nb) is to improve the creep resistance of the alloy. The addition of niobium significantly enhances the stability of the alloy in high temperature and high stress environments. By forming a strengthening phase and improving the grain boundary structure, niobium significantly improves the creep resistance of the alloy. This enhanced high temperature stability enables Inconel 625 alloy to maintain excellent performance under extreme working conditions and prolongs its service life in high temperature applications.

[0025] (7) Zirconium nitride (ZrN) generated by the reaction of Zr and nitrogen has high hardness and good wear resistance. ZrN also has good high temperature stability and can maintain its performance in high temperature environments. Therefore, it has application prospects in aerospace and other fields. The reaction of Zr with materials such as Ti can form composite materials. These composite materials usually have higher strength, hardness and fracture toughness, and can meet more stringent engineering requirements.

[0026] (8) The reaction of B with Zr can form ZrB2, a compound with high melting point, high hardness and good chemical stability. ZrB2 exhibits excellent oxidation resistance and corrosion resistance at high temperatures. The reaction of B with Ti can form TiB2, a compound with high hardness, high melting point and good electrical conductivity. TiB2 exhibits excellent oxidation resistance and corrosion resistance at high temperatures. Reaction of B with Cr The reaction of B with Cr can form CrB2, a compound with high hardness, high melting point and good chemical stability. CrB2 exhibits excellent oxidation resistance and corrosion resistance at high temperatures.

[0027] The present invention also provides a method for preparing a metal powder cored welding wire for surface modification of a heating furnace roller table, and the specific implementation steps are as follows: Step 1: Weigh the following powder cores by mass percentage: Ni 35%-55%, Cr 15.0%-17.0%, Fe 15%-19%, Nb4.0%-5.0%, Mo 2.8%-4.3%, TiC 5.0%-15.0%, Zr 0.5%-2.25%, B 1.5-2.5%. The sum of the mass percentages of the above components is 100%; Step 2: The powder core powder weighed in step 1 is evenly mixed and placed in a tube furnace and argon gas is continuously introduced, the furnace temperature is set to 120°C~150°C, and the drying time is 1h~2h; the dried powder core is placed in a powder mixer for sufficient mixing, and the mixing time is 1h~3h; Step 3: Roll the Inconel 625 alloy strip on a wire drawing machine, wrap the powder core prepared in step 2 in the Inconel 625 alloy strip, and close the alloy strip through a die. Use the die to reduce the diameter of the welding wire to 1.6 mm, and remove impurities on the surface of the welding wire; the filling amount of the powder core powder in the metal powder core welding wire is 18wt.%-25wt.%.

[0028] The present invention also provides a method for modifying the surface of a heating furnace outlet roller, wherein the welding wire is clad on the surface of the heating furnace outlet roller, the material of the heating furnace outlet roller is low carbon steel, and a cladding layer of metal is prepared by surfacing welding on the surface of the heating furnace outlet roller, wherein the cladding current is 100A-140A, the cladding speed is 0.15m / min-0.25m / min, 50% nitrogen and 50% argon are introduced during cladding, the welding method is a multi-pass deposition welding method, and the overlap between the previous and subsequent cladding passes is 30%-40%.

[0029] Among them, when the cladding layer metal is prepared by surfacing welding on the surface of the roller table out of the heating furnace, the welding process adopts automatic TIG welding. During the TIG cladding process, 50% nitrogen and 50% argon gas by volume are used to protect the welding area, which can effectively prevent the molten metal from generating spatter and pores.

[0030] Example 1 First, a metal powder cored welding wire for surface modification of a heating furnace roller table is prepared, and then the surface of the heating furnace roller table is modified using the welding wire, specifically: Step 1: Weigh the following core powders Ni 51.0%, Cr 17.0%, Fe 16.0%, Nb 5.2%, Mo 3.3%, TiC 5.0%, Zr 1.0%, B 1.5% respectively by mass percentage, and the sum of the mass percentages of the above components is 100%.

[0031] Step 2: The powder core powder weighed in step 1 is evenly mixed and placed in a tube furnace and argon gas is continuously introduced, the furnace temperature is set to 150° C., and the drying time is 1 hour; the dried powder core is placed in a powder mixer for sufficient mixing, and the mixing time is 1 hour; Step 3: Roll the Inconel 625 alloy strip on a wire drawing machine, wrap the powder core prepared in step 2 in the Inconel 625 alloy strip, close the alloy strip through a mold, reduce the diameter of the thick welding wire to 1.6 mm, and remove impurities on the surface of the welding wire; the filling amount of the powder core powder in the metal powder core welding wire is 20wt.%.

[0032] Step 4: The welding wire obtained in step 3 is clad on the surface of the roller table of the heating furnace. The cladding current is 100A, the cladding speed is 0.15m / min, and the volume fraction of nitrogen and argon is 50% and 50% respectively during cladding. The welding process adopts automatic TIG welding, and the welding method is multi-pass deposition welding. The overlap between the previous cladding and the next cladding is 40%.

[0033] The single-pass cladding test of the prepared welding wire was carried out, and its microstructure was as follows Figure 1 As shown in the figure, the single weld obtained is uniform and continuous, and the cross section of the cladding layer has no pores and slight slag inclusions. Figure 2As shown in the figure, the test results of the cladding layer show that after mechanical properties testing and microstructure observation, the average microhardness can reach 357.5HV 0.5 The wear amount is 5.4 mg. The wear amount refers to the mass lost on the surface of the material due to friction. The size of the wear amount can reflect the wear resistance of the material. The material with high microhardness and small wear amount is more difficult to be worn or deformed. The corrosion current density of Inconel 625 cladding layer is 1.235×10 -4 A.cm -2 The corrosion current density of the cladding layer with 5% TiC is 1.198×10 -4 A.cm -2 The corrosion current density of the 5% TiC cladding layer is lower than that of the Inconel625 cladding layer, indicating that the corrosion resistance of the 5% TiC cladding layer is improved.

[0034] Example 2 First, a metal powder cored welding wire for surface modification of a heating furnace roller table is prepared, and then the surface of the heating furnace roller table is modified using the welding wire, specifically: Step 1: Weigh the following core powders Ni 48.0%, Cr 17.0%, Fe 16%, Nb 4.0%, Mo 2.0%, TiC 10%, Zr 1.5%, B 1.5% respectively according to mass percentage, and the sum of the mass percentages of the above components is 100%.

[0035] Step 2: The powder core powder weighed in step 1 is evenly mixed and placed in a tube furnace and argon is continuously introduced, the furnace temperature is set to 180°C, and the drying time is 2 hours; the dried powder core is placed in a powder mixer for sufficient mixing, and the mixing time is 3 hours; Step 3: Roll the Inconel 625 alloy strip on a wire drawing machine, wrap the powder core prepared in step 2 in the Inconel 625 alloy strip, close the alloy strip through a mold, reduce the diameter of the thick welding wire to 1.6 mm, and remove impurities on the surface of the welding wire; the filling amount of the powder core powder in the metal powder core welding wire is 22wt.%.

[0036] Step 4: The welding wire obtained in step 3 is clad on the surface of the roller table of the heating furnace. The cladding current is 120A, the cladding speed is 0.20m / min, and the volume fraction of nitrogen and argon is 50% and 50% respectively during cladding. The welding process adopts automatic TIG welding, and the welding method is multi-pass deposition welding. The overlap between the previous and the next cladding is 40%.

[0037] The single-pass cladding test of the prepared welding wire was carried out, and its microstructure was as follows Figure 3As shown in the figure, the single weld obtained is uniform and continuous, and the cross section of the cladding layer has no microscopic defects such as pores and cracks. The test results of the cladding layer show that after mechanical property testing and microstructure observation, the average microhardness can reach 413.16HV 0.5 The wear amount is 2.7 mg. The wear amount refers to the mass lost on the surface of the material due to friction. The size of the wear amount can reflect the wear resistance of the material. The material with high microhardness and small wear amount is more difficult to be worn or deformed. The corrosion current density of Inconel 625 cladding layer is 1.235×10 -4 A.cm -2 The corrosion current density of the cladding layer with 10% TiC is 1.04×10 -4 A.cm -2 The corrosion current density of the 10% TiC cladding layer is lower than that of the Inconel625 cladding layer, indicating that the corrosion resistance of the 10% TiC cladding layer is improved.

[0038] Example 3 First, a metal powder cored welding wire for surface modification of a heating furnace roller table is prepared, and then the surface of the heating furnace roller table is modified using the welding wire, specifically: Step 1: Weigh the following core powders by mass percentage: Ni 40.00%, Cr 17.0%, Fe 16%, Nb 4.5%, Mo 3.1%, TiC 15%, Zr 2.0%, B 2.4%. The sum of the mass percentages of the above components is 100%.

[0039] Step 2: The powder core powder weighed in step 1 is evenly mixed and placed in a tube furnace and argon is continuously introduced, the furnace temperature is set to 180°C, and the drying time is 2 hours; the dried powder core is placed in a powder mixer for sufficient mixing, and the mixing time is 3 hours; Step 3: Roll the Inconel 625 alloy strip on a wire drawing machine, wrap the powder core prepared in step 2 in the Inconel 625 alloy strip, close the alloy strip through a mold, reduce the diameter of the thick welding wire to 1.6 mm, and remove impurities on the surface of the welding wire; the filling amount of the powder core powder in the metal powder core welding wire is 25wt.%.

[0040] Step 4: The welding wire obtained in step 3 is clad on the surface of the roller table of the heating furnace. The cladding current is 140A, the cladding speed is 0.25m / min, and the volume fraction of nitrogen and argon is 50% and 50% respectively during cladding. The welding process adopts automatic TIG welding, and the welding method is multi-pass deposition welding. The overlap between the previous and the next cladding is 40%.

[0041] The single-pass cladding test of the prepared welding wire was carried out, and its microstructure was as follows Figure 3As shown in the figure, the single weld obtained is uniform and continuous, and the cross section of the cladding layer has no microscopic defects such as pores and cracks. The test results of the cladding layer show that after mechanical property testing and microstructure observation, the average microhardness can reach 452.16HV 0.5 The wear amount is 2.7 mg. The wear amount refers to the mass lost on the surface of the material due to friction. The size of the wear amount can reflect the wear resistance of the material. The material with high microhardness and small wear amount is more difficult to be worn or deformed. The corrosion current density of Inconel 625 cladding layer is 1.235×10 -4 A.cm -2 The corrosion current density of the cladding layer with 15% TiC is 1.14×10 -4 A.cm -2 The corrosion current density of the 15% TiC cladding layer is lower than that of the Inconel625 cladding layer, indicating that the corrosion resistance of the 15% TiC cladding layer is improved.

[0042] In summary, the heating furnace roller is expensive and difficult to process, so the heating furnace roller is made of low carbon steel and a nickel-based high temperature alloy is clad on its surface. The hardness, wear resistance and corrosion resistance of the heating furnace roller can be improved by the method of the present invention.

[0043] The TIG cladding method is adapted to the prepared welding wire. When TIG welding clads nickel-based high-temperature alloys on the surface of low-carbon steel, a high-quality cladding layer can be formed, which has the advantages of controllable welding process, low heat input, small heat-affected zone, and small deformation of the substrate. In the cladding process, 50% nitrogen and 50% argon are used to react the Ti element in the metal powder cored welding wire with the N2 in the shielding gas to generate TiN. This cladding method and powder cored welding wire can improve the high temperature resistance and corrosion resistance of low-carbon steel.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A metal powder cored welding wire for surface modification of a roller table of a heating furnace, comprising a powder core and a welding skin, characterized in that: The powder core is composed of the following components by mass percentage: Ni 35%-55%, Cr 15.0%-17.0%， Fe 15%-19%, Nb 4.0%-5.0%, Mo 2.8%-4.3%, TiC 5.0%-15.0%, Zr 0.5%-2.25%， B 1.5-2.5%, the sum of the mass percentages of the above components is 100%; the welding skin is a nickel-based alloy strip; the filling amount of the powder core powder in the metal powder core welding wire is 18wt.%-25wt.%.

2. The metal powder cored welding wire for surface modification of a heating furnace roller table according to claim 1, characterized in that: The nickel-based alloy strip is Inconel 625 alloy.

3. A method for preparing a metal powder cored welding wire for surface modification of a heating furnace roller table as claimed in any one of claims 1 to 2, characterized in that: include: Step 1: Weigh the following powder cores by mass percentage: Ni 35%-55%, Cr 15.0%-17.0%, Fe 15%-19%, Nb 4.0%-5.0%, Mo 2.0%-4.3%, TiC 5.0%-15.0%, Zr 0.5%-2.25%, B 1.5-2.5%. The sum of the mass percentages of the above components is 100%; Step 2: The powder core powder weighed in step 1 is evenly mixed and placed in a tube furnace and argon gas is continuously introduced, the furnace temperature is set to 120°C~150°C, and the drying time is 1h~2h; the dried powder core is placed in a powder mixer for sufficient mixing, and the mixing time is 1h~3h; Step 3: Roll the Inconel 625 alloy strip on a wire drawing machine, wrap the powder core prepared in step 2 in the Inconel 625 alloy strip, and close the alloy strip through a mold; use the mold to reduce the diameter of the welding wire to 1.6 mm, and remove impurities on the surface of the welding wire; the filling amount of the powder core powder in the metal powder core type welding wire is 18wt.%-25wt.%.

4. A method for modifying the surface of a roller table of a heating furnace, characterized in that: The metal powder cored welding wire for surface modification of a heating furnace roller table as claimed in any one of claims 1 to 2 is clad on the surface of the heating furnace roller table, and a cladding layer of metal is prepared by surfacing welding on the surface of the heating furnace roller table, wherein the cladding current is 100A to 140A, the cladding speed is 0.15m / min to 0.25m / min, 50% nitrogen and 50% argon are introduced during cladding, the welding method is a multi-pass deposition welding method, and the overlap between the previous and subsequent cladding passes is 30% to 40%.

5. The method for surface modification of a heating furnace roller table according to claim 4, characterized in that: The welding process for preparing the cladding layer metal by surfacing welding on the surface of the roller table out of the heating furnace adopts automatic TIG welding. During the TIG cladding process, 50% nitrogen and 50% argon gas by volume are used to protect the welding area.

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