A flux-cored welding wire for roll repair specifically designed for welding robots and its preparation method

Abstract

This application relates to the technical field of welding materials, specifically disclosing a flux-cored welding wire for roll repair specifically designed for welding robots and its preparation method. The flux-cored welding wire for roll repair specifically designed for welding robots includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages: 14%–18% rutile powder, 2%–5% zircon sand, 6%–9% dehydrated potassium feldspar, 3%–6% fluoride, 4%–8% potassium compound and / or sodium compound, 18%–25% chromium powder, 3%–6% molybdenum powder, 5%–8% electrolytic manganese, 2%–4% ferrosilicon, 1%–3% ferrotitanium, 3%–5% carbon black, 0.1%–0.6% bismuth oxide, and the remainder being iron powder. The flux-cored welding wire prepared in this application exhibits excellent working stability during welding, and the resulting weld overlay possesses high hardness, good low-temperature impact toughness, and excellent wear resistance, with intact internal quality.

Description

Technical Field

[0001] This application relates to the technical field of welding materials, and more specifically, to a flux-cored welding wire for roll repair specifically for use in welding robots and a method for preparing the same. Background Technology

[0002] Rolls are critical and vulnerable components in steel rolling production lines. Operating under high temperature, high pressure, and intense abrasion conditions for extended periods, they are prone to failure modes such as wear, cracking, and spalling. Roll surfacing is a commonly used method for repairing and protecting the roll surface, and its general process includes material selection, parameter control, and post-weld treatment.

[0003] With the development of industrial automation, welding robots are increasingly being used in the field of roll repair due to their advantages of high welding precision, good stability, and high efficiency. However, existing flux-cored welding wires are mostly designed for manual or semi-automatic welding, and their matching with the welding parameters of welding robots (such as wire feed speed, arc voltage, and welding current) is poor. This can easily lead to problems such as unstable arc, large amount of spatter, cracks, poor slag removal, porosity, and poor weld layer formation due to unsatisfactory molten iron fluidity. Furthermore, the strength and toughness of the weld overlay are difficult to meet the requirements for roll use.

[0004] Patent application CN107127478A discloses a flux-cored welding wire comprising a low-carbon steel strip sheath and a flux core. The flux core comprises, by weight percentage: 1%~2% graphite, 15%~17% chromium powder, 1%~2% manganese powder, 4%~6% nickel powder, 4%~6% niobium powder, 1%~3% vanadium powder, 1%~1.5% titanium dioxide, 0.5%~1% silicon dioxide, 4%~5% rhenium oxide, 4%~5% cerium oxide, slag-forming agent, oxidant and reducing agent, with the balance being iron powder.

[0005] In this technical solution, firstly, the formula uses graphite as a carbon source, which easily leads to coarsening and segregation of carbides under rapid cooling conditions during welding. Although this may increase hardness, it will significantly reduce toughness and easily cause cracks at low temperatures or under dynamic loads. Secondly, the formula contains a relatively large amount of rare earth elements and rare earth oxides, which will cause rare earth elements to agglomerate at the grain boundaries, forming coarse compounds that become crack initiation sources, thus reducing the hardness and toughness of the weld overlay layer. Summary of the Invention

[0006] To balance the hardness and toughness of the weld overlay after welding, this application provides a flux-cored welding wire for roll repair specifically for use in welding robots and its preparation method.

[0007] In the first aspect, this application provides a flux-cored welding wire for roll repair specifically for use in welding robots, employing the following technical solution:

[0008] A flux-cored welding wire for roll repair specifically designed for use in welding robots, comprising an outer sheath and a core powder, wherein the core powder is prepared from raw materials comprising the following mass percentages:

[0009] Rutile powder 14%~18%, zircon sand 2%~5%, dehydrated potassium feldspar 6%~9%, fluoride 3%~6%, potassium compound and / or sodium compound 4%~8%, chromium powder 18%~25%, molybdenum powder 3%~6%, electrolytic manganese 5%~8%, ferrosilicon 2%~4%, ferrotitanium 1%~3%, carbon black 3%~5%, bismuth oxide 0.1%~0.6%, the remainder being iron powder;

[0010] The amount of flux-cored powder used is 18% to 22% of the total mass of the flux-cored welding wire;

[0011] The outer sheath is made of ultra-low carbon stainless steel strip with C ≤ 0.02%.

[0012] In this technical solution, pretreated carbon black is used as the carbon source, combined with high-hardness carbide-forming elements such as chromium and molybdenum. This ensures the wear resistance of the weld overlay while avoiding carbide coarsening and segregation. Through the strengthening deoxidation and grain refinement effects of ferrosilicon and ferrotitanium, as well as the solid solution strengthening of electrolytic manganese and the auxiliary refinement of trace amounts of bismuth oxide, a fine and uniform weld microstructure is constructed, achieving an optimized match between high hardness and high toughness, laying the microstructural foundation for excellent comprehensive mechanical properties. Regarding the welding process, the composite slag system composed of rutile, zircon sand, dehydrated potassium feldspar, and fluoride ensures good coverage and fluidity of the molten pool during welding, and enables automatic slag shell removal after welding, meeting the requirements of efficient continuous robotic operation. The synergistic effect of rutile and potassium-sodium compounds significantly stabilizes the arc and reduces spatter, while fluoride effectively reduces the risk of hydrogen-induced defects. Combined with subsequent drawing annealing technology, the welding wire possesses excellent dimensional consistency and wire feeding stability, fully adapting to the stringent requirements of welding robots for process consistency, wire feeding stability, and forming quality.

[0013] Preferably, the Si content in the ferrosilicon is not less than 45%; and the Ti content in the ferrotitanium is not less than 40%.

[0014] More preferably, the Si content in the ferrosilicon is 45%~50%; and the Ti content in the ferrotitanium is 40%~45%.

[0015] In this technical solution, it is ensured that silicon and iron can fully complete the deep deoxidation of the molten pool, purify the molten pool and suppress porosity, while avoiding the increase of brittle phase and decrease of toughness caused by excessive silicon and titanium. This content range is matched with other composite strengthening elements in this solution to jointly construct a fine and uniform microstructure, thereby more systematically achieving the optimization of high hardness and high toughness.

[0016] Preferably, the ultra-low carbon stainless steel strip has the following chemical composition by mass percentage: C≤0.02%, Si≤0.5%, Mn≤0.5%, Cr 11.5%~13.5%, Ni≤0.6%, P≤0.025%, S≤0.015%, with the balance being Fe and unavoidable impurities.

[0017] Preferably, the carbon black undergoes the following pretreatment steps before use: heat treatment at 800~1000℃ for 1.5~2 hours under an inert atmosphere, followed by cooling, and then it is ready for use.

[0018] In this technical solution, heat treatment under an inert atmosphere can effectively remove the moisture, volatile matter and oxygen-containing groups adsorbed on the surface of carbon black, making the release and diffusion behavior of carbon elements more stable and uniform in the weld pool, thereby avoiding excessive local carbon concentration and significantly reducing carbide segregation and crack sensitivity.

[0019] Preferably, the fluoride is calcium fluoride.

[0020] In this technical solution, calcium fluoride can reduce the melting point and viscosity of molten slag and improve slag removal performance; at the same time, the fluoride ions generated by its decomposition at high temperature of electric arc can combine with hydrogen to generate hydrogen fluoride gas that escapes, thereby significantly reducing the content of diffusible hydrogen in the molten pool and reducing the risk of hydrogen-induced porosity and cold cracking.

[0021] Preferably, the potassium compound is potassium carbonate; and the sodium compound is sodium carbonate.

[0022] In this technical solution, potassium carbonate and / or sodium carbonate ionize at the high temperature of the electric arc, providing potassium and sodium ions with low ionization potential, which can effectively reduce the arc potential gradient, making the arc contraction smaller and more stable and gentle.

[0023] Preferably, the core powder further includes 0.5% to 1.5% niobium powder by weight.

[0024] In this technical solution, niobium is a strong carbonitride forming element. Adding trace amounts of niobium powder can form fine niobium carbonitride particles in the weld overlay. These particles can effectively pin grain boundaries, hinder grain growth, and play a significant role in grain refinement and strengthening. At the same time, the hardness is further improved through precipitation strengthening, which helps to optimize the ratio of hardness to toughness.

[0025] Preferably, the core powder further includes 0.1% to 0.2% yttrium oxide by weight.

[0026] In this technical solution, yttrium oxide can adsorb and refine non-metallic inclusions in the weld, causing them to spheroidize and disperse, reducing stress concentration points; at the same time, it can segregate at grain boundaries, improving grain boundary cleanliness and stability. This helps to improve the toughness of the weld overlay while increasing hardness.

[0027] Preferably, the core powder further includes 1% to 2% ferrovanadium by weight.

[0028] In this technical solution, ferrovanadium, as a strong carbonitride forming element, can form extremely fine VC or VN particles, playing a dual role of precipitation strengthening and grain refinement. It can improve the strength of the weld overlay without significantly reducing toughness, thereby achieving a better strength-toughness match and improving the impact and wear resistance.

[0029] Preferably, the particle size of each raw material in the core powder is 200-300 mesh, and the moisture content is ≤0.1%.

[0030] In this technical solution, the particle size range and low moisture content are prerequisites for ensuring uniform mixing and dense filling of the flux core powder. Uniform filling can avoid wire feeding fluctuations caused by uneven density inside the welding wire, which is the basis for meeting the stringent requirements of wire feeding stability in robotic welding; low moisture content directly reduces the hydrogen source of welding porosity.

[0031] Secondly, this application provides a method for preparing a flux-cored welding wire for roll repair specifically for use in welding robots, comprising the following steps:

[0032] S1: Weigh the raw materials according to the specified ratio, mix them evenly, dry and cool them to obtain the core powder;

[0033] S2: After cleaning and rolling the ultra-low carbon stainless steel strip, fill it with the flux-cored powder according to the required amount, draw and anneal it, straighten it, wind it into a disc, vacuum package it and put it into storage to obtain flux-cored welding wire.

[0034] Preferably, in step S2, the fluctuation of the core powder filling rate is controlled to be within ±0.5%.

[0035] Preferably, in step S2, the drawing process includes: first performing roller drawing, and then performing pressure drawing.

[0036] Preferably, in step S2, after every 3 to 5 drawing passes, the material is annealed at 200 to 250°C for 1 to 2 hours.

[0037] Preferably, in step S2, the straightening is performed online synchronously, controlling the straightness of the welding wire to be ≤1mm / m and the diameter tolerance to be ≤±0.05mm.

[0038] In summary, this application has the following beneficial effects:

[0039] This application constructs a stable composite slag system using rutile powder, zircon sand, and dehydrated potassium feldspar. Potassium / sodium compounds provide ions with low ionization potential, significantly stabilizing the arc and reducing spatter. Pretreated carbon black is used to control carbon content, combined with basic strengthening by chromium and molybdenum. Furthermore, the composite grain refinement and strengthening effects of ferrosilicon, ferrotitanium, electrolytic manganese, bismuth oxide, and optional niobium powder, yttrium oxide, and ferrovanadium are utilized. The resulting weld overlay maintains high hardness while possessing excellent low-temperature impact toughness, achieving superior comprehensive performance with simultaneous improvement in both hardness and low-temperature impact toughness. Detailed Implementation

[0040] The present application will be further described in detail below with reference to the embodiments.

[0041] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0042] In the following examples, all raw materials were dried to a moisture content of ≤0.1% before use, and the particle size distribution of each raw material was 200~300 mesh.

[0043] Example 1

[0044] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0045] The composition is as follows: 14% rutile powder, 2% zircon sand, 6% dehydrated potassium feldspar, 3% calcium fluoride, 4% potassium carbonate, 18% chromium powder, 3% molybdenum powder, 5% electrolytic manganese, 2% ferrosilicon, 1% ferrotitanium, 3% carbon black, 0.1% bismuth oxide, and the remainder is iron powder.

[0046] The amount of flux-cored powder used is 22% of the total mass of the flux-cored wire;

[0047] The outer sheath is made of ultra-low carbon stainless steel strip. The chemical composition by mass percentage is as follows: C 0.02%, Si 0.5%, Mn 0.5%, Cr 11.5%, Ni 0.6%, P 0.025%, S 0.015%, with the balance being Fe and unavoidable impurities.

[0048] Before use, carbon black undergoes the following pretreatment steps:

[0049] Under a nitrogen atmosphere, carbon black was placed in a sintering apparatus and heated to 800°C at a rate of 5°C / min for 2 hours. After purging with nitrogen, it was cooled to room temperature for later use.

[0050] In ferrosilicon, the Si content is 45%; in ferrotitanium, the Ti content is 40%.

[0051] This embodiment also provides a method for preparing flux-cored welding wire for roll repair specifically for use in welding robots, comprising the following steps:

[0052] S1: Weigh each core component by mass percentage, pour it into a powder mixer and mix for 60 minutes, then bake in an oven for 2 hours at 150℃, and then cool naturally to room temperature to obtain core powder;

[0053] S2: After cleaning the 0.4mm×10mm outer steel strip, it is rolled into a U-shaped groove using 8 sets of rolling dies. The flux-cored powder prepared in S1 is then filled using a powder filling system, controlling the flux-cored powder filling amount to be 22% of the total mass of the flux-cored welding wire, and ensuring that the real-time fluctuation range of the filling coefficient is controlled within ±0.5%. The filled U-shaped groove is then sealed, and a four-pass drawing reduction process is performed using a drawing die, with the reduction ratio in each pass within the range of 5±1%. Then, a pressure die is used for subsequent processing. The wire is drawn and reduced in diameter, with a reduction ratio of 6±1% per pass until the target diameter Φ1.6mm is reached. During the overall drawing process, after every 5 consecutive drawing passes, an intermediate annealing treatment is performed at 200℃ for 2 hours. The wire drawn to the target diameter is immediately straightened online synchronously, and the straightness (bending) of the straightened wire is controlled to be ≤1mm / m and the diameter tolerance is ≤±0.05mm. The straightened wire layer is wound into a disc and vacuum-packed to obtain the finished flux-cored wire.

[0054] Example 2

[0055] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0056] The composition is as follows: 18% rutile powder, 5% zircon sand, 9% dehydrated potassium feldspar, 6% calcium fluoride, 8% potassium carbonate, 25% chromium powder, 6% molybdenum powder, 8% electrolytic manganese, 4% ferrosilicon, 3% ferrotitanium, 5% carbon black, 0.6% bismuth oxide, and the remainder is iron powder.

[0057] The amount of flux-cored powder used is 18% of the total mass of the flux-cored welding wire;

[0058] The outer sheath is made of ultra-low carbon stainless steel strip. The chemical composition by mass percentage is as follows: C 0.02%, Si 0.5%, Mn 0.5%, Cr 11.5%, Ni 0.6%, P 0.025%, S 0.015%, with the balance being Fe and unavoidable impurities.

[0059] Before use, carbon black undergoes the following pretreatment steps:

[0060] Under a nitrogen atmosphere, carbon black was placed in a sintering apparatus and heated to 1000°C at a rate of 5°C / min for 1.5 hours. After purging with nitrogen, it was cooled to room temperature for later use.

[0061] In ferrosilicon, the Si content is 45%; in ferrotitanium, the Ti content is 40%.

[0062] This embodiment also provides a method for preparing flux-cored welding wire for roll repair specifically for use in welding robots, comprising the following steps:

[0063] S1: Weigh each core component by mass percentage, pour it into a powder mixer and mix for 90 minutes, then bake in an oven for 2 hours at 180℃, and then cool naturally to room temperature to obtain core powder;

[0064] S2: After cleaning the 0.4mm×10mm outer steel strip, it is rolled into a U-shaped groove using 8 sets of rolling dies. The flux-cored powder prepared in S1 is then filled using a powder filling system, controlling the flux-cored powder filling amount to be 18% of the total mass of the flux-cored welding wire, and ensuring that the real-time fluctuation range of the filling coefficient is controlled within ±0.5%. The filled U-shaped groove is then sealed, and a four-pass drawing reduction process is performed using a drawing die, with the reduction ratio in each pass within the range of 5±1%. Then, a pressure die is used for subsequent processing. The wire is drawn and reduced in diameter, with a reduction ratio of 6±1% per pass until the target diameter Φ1.6mm is reached. During the overall drawing process, after every 5 consecutive drawing passes, an intermediate annealing treatment is performed at 200℃ for 2 hours. The wire drawn to the target diameter is immediately straightened online synchronously, and the straightness (bending) of the straightened wire is controlled to be ≤1mm / m and the diameter tolerance is ≤±0.05mm. The straightened wire layer is wound into a disc and vacuum-packed to obtain the finished flux-cored wire.

[0065] Example 3

[0066] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0067] The composition is as follows: 16% rutile powder, 4% zircon sand, 7% dehydrated potassium feldspar, 5% calcium fluoride, 6% potassium carbonate, 20% chromium powder, 5% molybdenum powder, 6% electrolytic manganese, 3% ferrosilicon, 2% ferrotitanium, 4% carbon black, 0.4% bismuth oxide, and the remainder is iron powder.

[0068] The amount of flux-cored powder used is 20% of the total mass of the flux-cored welding wire;

[0069] The outer sheath is made of ultra-low carbon stainless steel strip. The chemical composition by mass percentage is as follows: C 0.02%, Si 0.5%, Mn 0.5%, Cr 11.5%, Ni 0.6%, P 0.025%, S 0.015%, with the balance being Fe and unavoidable impurities.

[0070] Before use, carbon black undergoes the following pretreatment steps:

[0071] Under a nitrogen atmosphere, carbon black was placed in a sintering apparatus and heated to 1000°C at a rate of 5°C / min for 1.5 hours. After purging with nitrogen, it was cooled to room temperature for later use.

[0072] In ferrosilicon, the Si content is 45%; in ferrotitanium, the Ti content is 40%.

[0073] This embodiment also provides a method for preparing flux-cored welding wire for roll repair specifically for use in welding robots, comprising the following steps:

[0074] S1: Weigh each core component by mass percentage, pour it into a powder mixer and mix for 90 minutes, then bake in an oven for 2 hours at 160℃, and then cool naturally to room temperature to obtain core powder;

[0075] S2: After cleaning the 0.4mm×10mm outer steel strip, it is rolled into a U-shaped groove using 8 sets of rolling dies. The flux-cored powder prepared in S1 is then filled using a powder filling system. The flux-cored powder filling amount is controlled to be 20% of the total mass of the flux-cored welding wire, and the real-time fluctuation range of the filling coefficient is controlled within ±0.5%. The filled U-shaped groove is then sealed. First, a drawing die is used for 4 passes of drawing to reduce the diameter, with the diameter reduction ratio in each pass within the range of 5±1%. Then, a pressure die is used for subsequent drawing. The wire is drawn and reduced in diameter, with a reduction ratio of 6±1% per pass until the target diameter Φ1.6mm is reached. During the overall drawing process, after every 5 consecutive drawing passes, an intermediate annealing treatment is performed at 200℃ for 2 hours. The wire drawn to the target diameter is immediately straightened online synchronously, and the straightness (bending) of the straightened wire is controlled to be ≤1mm / m and the diameter tolerance is ≤±0.05mm. The straightened wire layer is wound into a disc and vacuum-packed to obtain the finished flux-cored wire.

[0076] Example 4

[0077] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0078] The composition is as follows: 16% rutile powder, 4% zircon sand, 7% dehydrated potassium feldspar, 5% calcium fluoride, 3% potassium carbonate, 3% sodium carbonate, 20% chromium powder, 5% molybdenum powder, 6% electrolytic manganese, 3% ferrosilicon, 2% ferrotitanium, 4% carbon black, 0.4% bismuth oxide, and the remainder is iron powder.

[0079] The amount of flux-cored powder used is 20% of the total mass of the flux-cored welding wire;

[0080] The outer sheath is made of ultra-low carbon stainless steel strip. The chemical composition by mass percentage is as follows: C 0.01%, Si 0.3%, Mn 0.4%, Cr 13.5%, Ni 0.3%, P 0.01%, S 0.01%, with the balance being Fe and unavoidable impurities.

[0081] Before use, carbon black undergoes the following pretreatment steps:

[0082] Under a nitrogen atmosphere, carbon black was placed in a sintering apparatus and heated to 1000°C at a rate of 5°C / min for 1.5 hours. After purging with nitrogen, it was cooled to room temperature for later use.

[0083] In ferrosilicon, the Si content is 50%; in ferrotitanium, the Ti content is 45%.

[0084] This embodiment also provides a method for preparing flux-cored welding wire for roll repair specifically for use in welding robots, comprising the following steps:

[0085] S1: Weigh each core component by mass percentage, pour it into a powder mixer and mix for 90 minutes, then bake in an oven for 2 hours at 160℃, and then cool naturally to room temperature to obtain core powder;

[0086] S2: After cleaning the 0.4mm×10mm outer steel strip, it is rolled into a U-shaped groove using 8 sets of rolling dies. The flux-cored powder prepared in S1 is then filled using a powder filling system, controlling the flux-cored powder filling amount to be 20% of the total mass of the flux-cored welding wire, and ensuring that the real-time fluctuation range of the filling coefficient is controlled within ±0.5%. The filled U-shaped groove is then sealed, and a four-pass drawing reduction process is performed using a drawing die, with the reduction ratio in each pass within the range of 9±1%. Then, a pressure die is used for subsequent processing. The wire is drawn and reduced in diameter, with a reduction ratio of 9±1% per pass until the target diameter Φ1.0mm is reached. During the overall drawing process, after every 3 consecutive drawing passes, an intermediate annealing treatment is performed at 250℃ for 1 hour. The wire drawn to the target diameter is immediately straightened online synchronously, and the straightness (bending) of the straightened wire is controlled to be ≤1mm / m and the diameter tolerance is ≤±0.05mm. The straightened wire layer is wound into a disc and vacuum-packed to obtain the finished flux-cored wire.

[0087] Example 5

[0088] The difference between this embodiment and embodiment 4 is that:

[0089] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0090] The composition is as follows: 16% rutile powder, 4% zircon sand, 7% dehydrated potassium feldspar, 5% calcium fluoride, 3% potassium carbonate, 3% sodium carbonate, 20% chromium powder, 5% molybdenum powder, 6% electrolytic manganese, 3% ferrosilicon, 2% ferrotitanium, 4% carbon black, 0.4% bismuth oxide, 0.5% niobium powder, and the remainder is iron powder.

[0091] The rest is the same as in Example 4.

[0092] Example 6

[0093] The difference between this embodiment and embodiment 5 is as follows:

[0094] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0095] The composition is as follows: 16% rutile powder, 4% zircon sand, 7% dehydrated potassium feldspar, 5% calcium fluoride, 3% potassium carbonate, 3% sodium carbonate, 20% chromium powder, 5% molybdenum powder, 6% electrolytic manganese, 3% ferrosilicon, 2% ferrotitanium, 4% carbon black, 0.4% bismuth oxide, 1.5% niobium powder, and the remainder is iron powder.

[0096] The rest is the same as in Example 5.

[0097] Example 7

[0098] The difference between this embodiment and embodiment 6 is that:

[0099] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0100] The composition is as follows: 16% rutile powder, 4% zircon sand, 7% dehydrated potassium feldspar, 5% calcium fluoride, 3% potassium carbonate, 3% sodium carbonate, 20% chromium powder, 5% molybdenum powder, 6% electrolytic manganese, 3% ferrosilicon, 2% ferrotitanium, 4% carbon black, 0.4% bismuth oxide, 1.5% niobium powder, 0.1% yttrium oxide, and the remainder is iron powder.

[0101] The rest is the same as in Example 6.

[0102] Example 8

[0103] The difference between this embodiment and embodiment 7 is as follows:

[0104] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0105] The composition is as follows: 16% rutile powder, 4% zircon sand, 7% dehydrated potassium feldspar, 5% calcium fluoride, 3% potassium carbonate, 3% sodium carbonate, 20% chromium powder, 5% molybdenum powder, 6% electrolytic manganese, 3% ferrosilicon, 2% ferrotitanium, 4% carbon black, 0.4% bismuth oxide, 1.5% niobium powder, 0.1% yttrium oxide, 1% ferrovanadium, and the remainder is iron powder.

[0106] In ferrovanadium, the vanadium content is 50%.

[0107] The rest is the same as in Example 7.

[0108] Example 9

[0109] The difference between this embodiment and embodiment 8 is as follows:

[0110] The flux-cored welding wire for roll repair in this embodiment, specifically designed for use with welding robots, includes an outer sheath and a core powder. The core powder is prepared from the following raw materials in the indicated mass percentages:

[0111] The composition is as follows: 16% rutile powder, 4% zircon sand, 7% dehydrated potassium feldspar, 5% calcium fluoride, 3% potassium carbonate, 3% sodium carbonate, 20% chromium powder, 5% molybdenum powder, 6% electrolytic manganese, 3% ferrosilicon, 2% ferrotitanium, 4% carbon black, 0.4% bismuth oxide, 1.5% niobium powder, 0.2% yttrium oxide, 2% ferrovanadium, and the remainder is iron powder.

[0112] In ferrovanadium, the vanadium content is 50%.

[0113] The rest is the same as in Example 8.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 1 is as follows:

[0116] The flux-cored welding wire for roll repair in this comparative example, specifically designed for use with welding robots, comprises an outer sheath and a core powder, wherein the core powder is prepared from the following raw materials in the indicated mass percentages:

[0117] The composition is as follows: 14% rutile powder, 3% calcium fluoride, 4% potassium carbonate, 18% chromium powder, 3% molybdenum powder, 5% electrolytic manganese, 2% ferrosilicon, 1% ferrotitanium, 3% carbon black, 0.1% bismuth oxide, and the remainder is iron powder.

[0118] Everything else is the same as in Example 1.

[0119] Comparative Example 2

[0120] The difference between this comparative example and Example 1 is as follows:

[0121] The flux-cored welding wire for roll repair in this comparative example, specifically designed for use with welding robots, comprises an outer sheath and a core powder, wherein the core powder is prepared from the following raw materials in the indicated mass percentages:

[0122] The composition is as follows: 14% rutile powder, 2% zircon sand, 6% dehydrated potassium feldspar, 3% calcium fluoride, 18% chromium powder, 3% molybdenum powder, 5% electrolytic manganese, 2% ferrosilicon, 1% ferrotitanium, 3% carbon black, 0.1% bismuth oxide, and the remainder is iron powder.

[0123] Everything else is the same as in Example 1.

[0124] Comparative Example 3

[0125] The difference between this comparative example and Example 1 is as follows:

[0126] The flux-cored welding wire for roll repair in this comparative example, specifically designed for use with welding robots, comprises an outer sheath and a core powder, wherein the core powder is prepared from the following raw materials in the indicated mass percentages:

[0127] The composition is as follows: 14% rutile powder, 2% zircon sand, 6% dehydrated potassium feldspar, 3% calcium fluoride, 4% potassium carbonate, 18% chromium powder, 3% molybdenum powder, 5% electrolytic manganese, 3% carbon black, 0.1% bismuth oxide, and the remainder is iron powder.

[0128] Everything else is the same as in Example 1.

[0129] Comparative Example 4

[0130] The difference between this comparative example and Example 1 is as follows:

[0131] The carbon black was not pretreated before use;

[0132] Everything else is the same as in Example 1.

[0133] Performance testing

[0134] The flux-cored welding wires prepared in Examples 1-9 and Comparative Examples 1-4 were subjected to surfacing tests on the surface of a standard roll repair substrate under the same welding robot and welding parameters (wire feed speed: 10 m / min, current: 260 A, voltage: 30 V, shielding gas: 80% Ar + 20% CO2). After welding, the welding process was observed and recorded, and the surfacing layer samples were tested. The results are recorded in Tables 1 and 2. The main reference standards were GB / T 12444-2006 and GB / T 230.1-2018. During wear mass loss, the normal load was 200 N, the grinding ring rotation speed was 200 r / min, the wear time was 70 min, the grinding ring material was GCr15 (bearing steel), and the grinding ring hardness HRC was 62 ± 1.

[0135] Table 1 Welding process performance test results

[0136]

[0137] Table 2 Test Results of Weld Overlay Layer

[0138]

[0139] Based on the performance test results in Tables 1 and 2, analysis of Examples 1-9 and Comparative Examples 1-4 shows that:

[0140] Examples 1-9 exhibit excellent and stable welding process performance, with a highly stable arc, low spatter rate, automatic slag removal and lifting, smooth weld layer, and high deposition efficiency. This directly ensures the integrity of the internal quality and the consistency of the surface formation of the weld overlay. Correspondingly, the weld overlays all demonstrate high hardness, good low-temperature impact toughness, and excellent wear resistance in terms of performance, and no defects were found in any of them through non-destructive testing.

[0141] In comparison, Comparative Example 1 exhibited poor slag removal and an uneven weld layer; Comparative Example 2 showed inconsistent arc and a relatively high spatter rate, indicating slightly poor process stability; while Comparative Examples 3 and 4 had basically satisfactory process performance, their weld overlays contained a small amount of porosity and localized microcracks, respectively. These welding defects or process instability directly led to a decline in the key performance characteristics of their weld overlays: the wear resistance of Comparative Examples 3 and 4 was significantly lower than that of the Example Group, and their impact toughness was significantly reduced.

[0142] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A flux-cored welding wire for roll repair specifically designed for use in welding robots, comprising an outer sheath and a core powder, characterized in that, The core powder is prepared from the following raw materials in the indicated mass percentages: Rutile powder 14%~18%, zircon sand 2%~5%, dehydrated potassium feldspar 6%~9%, fluoride 3%~6%, potassium compound and / or sodium compound 4%~8%, chromium powder 18%~25%, molybdenum powder 3%~6%, electrolytic manganese 5%~8%, ferrosilicon 2%~4%, ferrotitanium 1%~3%, carbon black 3%~5%, bismuth oxide 0.1%~0.6%, the remainder being iron powder; The amount of flux-cored powder used is 18% to 22% of the total mass of the flux-cored welding wire; The outer sheath is made of ultra-low carbon stainless steel strip with C ≤ 0.02%.

2. The flux-cored welding wire for roll repair specifically for welding robots according to claim 1, characterized in that, Before use, the carbon black undergoes the following pretreatment steps: heat treatment at 800~1000℃ for 1.5~2 hours under an inert atmosphere, followed by cooling, and then it is ready for use.

3. The flux-cored welding wire for roll repair specifically for welding robots according to claim 1, characterized in that, The silicon ferrosilicon has a Si content of not less than 45%; the titanium ferrosilicon has a Ti content of not less than 40%.

4. The flux-cored welding wire for roll repair specifically for welding robots according to claim 1, characterized in that, The potassium compound is potassium carbonate; the sodium compound is sodium carbonate.

5. The flux-cored welding wire for roll repair specifically for welding robots according to claim 1, characterized in that, The core powder also includes 0.5% to 1.5% niobium powder by weight.

6. The flux-cored welding wire for roll repair specifically for welding robots according to claim 1, characterized in that, The core powder also includes 0.1% to 0.2% yttrium oxide by weight.

7. The flux-cored welding wire for roll repair specifically for welding robots according to claim 1, characterized in that, The core powder also includes 1% to 2% ferrovanadium by weight.

8. The flux-cored welding wire for roll repair specifically for welding robots according to claim 1, characterized in that, The particle size of each raw material in the core powder is 200-300 mesh, and the moisture content is ≤0.1%.

9. A method for preparing a flux-cored welding wire for roll repair specifically for use in welding robots, as described in any one of claims 1 to 8, characterized in that: Includes the following steps: S1: Weigh the raw materials according to the proportion, mix them evenly, dry and cool them to obtain the core powder; S2: After cleaning and rolling the ultra-low carbon stainless steel strip, fill it with the flux-cored powder according to the required amount, draw and anneal it, straighten it, wind it into a disc, vacuum package it and put it into storage to obtain flux-cored welding wire.

10. The method for preparing flux-cored welding wire for roll repair specifically for welding robots according to claim 9, characterized in that, In step S2, after every 3 to 5 drawing passes, the material is annealed at 200 to 250°C for 1 to 2 hours.

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