Flux-cored wire special for roller repair for welding robot and preparation method of flux-cored wire

Abstract

The invention relates to the technical field of welding materials, and particularly discloses a flux-cored wire special for roller repairing for a welding robot and a preparation method of the flux-cored wire. A roller repairing flux-cored wire special for a welding robot comprises an outer skin and flux core powder, and the flux core powder is prepared from, by mass, 14%-18% of rutile powder, 2%-5% of zircon sand, 6%-9% of dehydrated potassium feldspar, 3%-6% of fluoride, 4%-8% of potassium compounds or / and sodium compounds, 18%-25% of chromium powder, 3%-6% of molybdenum powder, 5%-8% of electrolytic manganese, 2%-4% of silicon iron, 1%-3% of ferrotitanium, 3%-5% of carbon black, 0.1%-0.6% of bismuth oxide and the balance iron powder. The flux-cored wire prepared in the invention shows excellent working stability in welding, and an obtained surfacing layer has high hardness, good low-temperature impact toughness and excellent wear resistance, and is intact in internal quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding materials, more particularly, it relates to a flux-cored wire for roller repair specially used for welding robots and a preparation method thereof. BACKGROUND

[0002] The roller is a key vulnerable component in the rolling production line, which works under the conditions of high temperature, high pressure and strong wear for a long time, and is prone to failure forms such as wear, crack and spalling. Roller surfacing is a common method for repairing and protecting the surface of the roller, and its general process includes steps such as material selection, parameter control and post-welding treatment.

[0003] With the development of industrial automation, welding robots are gradually applied to the field of roller repair due to their high welding precision, good stability and high efficiency. However, the existing flux-cored wires are mostly designed for manual or semi-automatic welding, and have poor matching with the welding parameters (such as wire feeding speed, arc voltage and welding current) of welding robots, which may cause problems such as unstable arc, large spatter, crack, poor deslagging, gas hole and poor weld layer forming due to poor liquidity of molten iron, and the strength and toughness of the post-welding surfacing layer are difficult to meet the use requirements of the roller.

[0004] The patent application file with publication number CN107127478A discloses a flux-cored wire, which comprises a low-carbon steel belt sheath and a core, wherein the raw materials of the core include, by weight percentage, graphite 1%~2%, chromium powder 15%~17%, manganese powder 1%~2%, nickel powder 4%~6%, niobium powder 4%~6%, vanadium powder 1%~3%, titanium dioxide 1%~1.5%, silicon dioxide 0.5%~1%, rhenium oxide 4%~5%, cerium oxide 4%~5%, slagging agent, oxidizing agent and reducing agent, and the balance is iron powder.

[0005] In this technical solution, first, graphite is used as the carbon source in the formula, which may cause the coarsening and segregation of carbides under the condition of rapid cooling during surfacing, and although it may increase the hardness, it will significantly reduce the toughness, and cracks may occur under low temperature or dynamic load. Second, relatively more rare earth elements and rare earth oxides are added to the formula, which may cause the segregation of rare earth elements at the grain boundaries, forming coarse compounds and becoming the source of crack initiation, thereby reducing the hardness and toughness of the surfacing layer. SUMMARY

[0006] In order to balance the hardness and toughness of the post-welding surfacing layer, the present application provides a flux-cored wire for roller repair specially used for welding robots and a preparation method thereof.

[0007] In the first aspect, the present application provides a flux-cored wire for roller repair specially used for welding robots, which adopts the following technical solution: A flux-cored wire for roller repair used for welding robot, comprising an outer skin and a core powder, the core powder is prepared from raw materials with the following mass percentages: Rutile 14%-18%, zircon sand 2%-5%, dehydrated potassium feldspar 6%-9%, fluoride 3%-6%, potassium compound or / and 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%, and the rest is iron powder; The amount of the core powder is 18%-22% of the total mass of the flux-cored wire; The outer skin is an ultra-low carbon stainless steel strip with C≤0.02%.

[0008] In the technical solution, the pretreated carbon black is used as the carbon source, and is matched with chromium and molybdenum and other high-hardness carbide forming elements to avoid the coarsening and segregation of carbides and ensure the wear resistance of the surfacing layer; through the strengthening deoxidization and grain refinement of ferrosilicon and ferrotitanium, and the solid solution strengthening of electrolytic manganese and the auxiliary refinement of trace bismuth oxide, a fine and uniform weld structure is jointly constructed, the optimization matching of high hardness and high toughness is realized, and the organizational foundation for obtaining excellent comprehensive mechanical properties is laid. In the welding process, the composite slag system composed of rutile, zircon sand, dehydrated potassium feldspar and fluoride not only ensures good molten pool coverage and fluidity during welding, but also realizes automatic slag shell stripping after welding, meeting the needs of high-efficiency continuous operation of the robot; the rutile and potassium-sodium compound cooperate to significantly stabilize the arc and reduce spatter, and the fluoride effectively reduces the risk of hydrogen-induced defects. Combined with subsequent drawing and annealing technology, the welding wire has excellent size consistency and wire feeding stability, fully meeting the strict requirements of the welding robot on process consistency, wire feeding stability and forming quality.

[0009] Preferably, the Si content in the ferrosilicon is not less than 45%, and the Ti content in the ferrotitanium is not less than 40%.

[0010] Further preferably, the Si content in the ferrosilicon is 45%-50%, and the Ti content in the ferrotitanium is 40%-45%.

[0011] In the technical solution, it is ensured that silicon and iron can fully complete deep deoxidization of the molten pool, purify the molten pool and inhibit pores, and it is also avoided that excessive silicon and titanium cause an increase in brittle phases and a decrease in toughness; this content range cooperates with other composite strengthening elements in the technical solution to jointly construct a fine and uniform microstructure, thereby more systematically realizing the optimization of high hardness and high toughness.

[0012] Preferably, the ultra-low carbon stainless steel strip has the following chemical composition in terms of 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%, and the balance of Fe and inevitable impurities.

[0013] Preferably, the carbon black is subjected to the following pretreatment step before use: heat treatment at 800~1000℃ for 1.5~2h under inert atmosphere, cooling, and standby.

[0014] In the technical solution, heat treatment under inert atmosphere can effectively remove water, volatile matter and oxygen-containing groups adsorbed on the surface of the carbon black, so that the release and diffusion behavior of carbon elements is more stable and uniform in the welding pool, thereby avoiding excessive local carbon concentration and significantly reducing carbide segregation and crack sensitivity.

[0015] Preferably, the fluoride is calcium fluoride.

[0016] In the technical solution, calcium fluoride can reduce the melting point and viscosity of the slag, improve the deslagging performance; at the same time, the fluorine ions generated by the decomposition of calcium fluoride at high temperature of the electric arc can combine with hydrogen to generate hydrogen fluoride gas to escape, thereby significantly reducing the diffusion hydrogen content in the welding pool and reducing the risk of hydrogen-induced pores and cold cracks.

[0017] Preferably, the potassium compound is potassium carbonate; and the sodium compound is sodium carbonate.

[0018] In the technical solution, potassium carbonate and / or sodium carbonate are ionized at high temperature of the electric arc to provide potassium and sodium ions with low ionization potential, which can effectively reduce the electric arc potential gradient, so that the electric arc shrinks and becomes more stable and gentle.

[0019] Preferably, the flux cored powder further comprises 0.5%~1.5% niobium powder by weight.

[0020] In the technical solution, niobium is a strong carbonitride forming element, and the addition of trace niobium powder can form fine niobium carbonitride particles in the surfacing layer. These particles can effectively pin the grain boundaries and hinder the growth of the grains, thereby playing a significant role in fine-grain strengthening, and further improving the hardness through precipitation strengthening, which helps to optimize the ratio of hardness and toughness.

[0021] Preferably, the flux cored powder further comprises 0.1%~0.2% yttrium oxide by weight.

[0022] In the technical solution, yttrium oxide can adsorb and refine non-metallic inclusions in the weld, so that the non-metallic inclusions are spheroidized and dispersedly distributed to reduce stress concentration points; at the same time, yttrium oxide can be segregated at the grain boundaries to improve the cleanliness and stability of the grain boundaries. This helps to improve the toughness of the surfacing layer while improving the hardness.

[0023] Preferably, the core powder further includes 1% to 2% ferrovanadium by weight.

[0024] 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.

[0025] Preferably, the particle size of each raw material in the core powder is 200-300 mesh, and the moisture content is ≤0.1%.

[0026] 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.

[0027] 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: S1: Weigh the raw materials according to the specified ratio, 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.

[0028] Preferably, in step S2, the fluctuation of the core powder filling rate is controlled to be within ±0.5%.

[0029] Preferably, in step S2, the drawing process includes: first performing roller drawing, and then performing pressure drawing.

[0030] 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.

[0031] 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.

[0032] In summary, this application has the following beneficial effects: 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

[0033] The present application will be further described in detail below with reference to the embodiments.

[0034] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0035] 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.

[0036] Example 1 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: 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. The amount of flux-cored powder used is 22% of the total mass of the flux-cored wire; 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.

[0037] Before use, carbon black undergoes the following pretreatment steps: 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. In ferrosilicon, the Si content is 45%; in ferrotitanium, the Ti content is 40%.

[0038] 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: 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; 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.

[0039] Example 2 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: 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. The amount of flux-cored powder used is 18% of the total mass of the flux-cored welding wire; 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.

[0040] Before use, carbon black undergoes the following pretreatment steps: 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. In ferrosilicon, the Si content is 45%; in ferrotitanium, the Ti content is 40%.

[0041] 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: 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; 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.

[0042] Example 3 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: 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. The amount of flux-cored powder used is 20% of the total mass of the flux-cored welding wire; 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.

[0043] Before use, carbon black undergoes the following pretreatment steps: 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. In ferrosilicon, the Si content is 45%; in ferrotitanium, the Ti content is 40%.

[0044] 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: 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; 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.

[0045] Example 4 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: 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. The amount of flux-cored powder used is 20% of the total mass of the flux-cored welding wire; 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.

[0046] Before use, carbon black undergoes the following pretreatment steps: 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. In ferrosilicon, the Si content is 50%; in ferrotitanium, the Ti content is 45%.

[0047] 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: 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; 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.

[0048] Example 5 The difference between this embodiment and embodiment 4 is that: 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: 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. The rest is the same as in Example 4.

[0049] Example 6 The difference between this embodiment and embodiment 5 is as follows: 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: 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. The rest is the same as in Example 5.

[0050] Example 7 The difference between this embodiment and embodiment 6 is that: 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: 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. The rest is the same as in Example 6.

[0051] Example 8 The difference between this embodiment and embodiment 7 is that: 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: 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. In ferrovanadium, the vanadium content is 50%. The rest is the same as in Example 7.

[0052] Example 9 The difference between this embodiment and embodiment 8 is as follows: 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: 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. In ferrovanadium, the vanadium content is 50%. The rest is the same as in Example 8.

[0053] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: 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: 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. Everything else is the same as in Example 1.

[0054] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: 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: 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. Everything else is the same as in Example 1.

[0055] Comparative Example 3 The difference between this comparative example and Example 1 is as follows: 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: 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. Everything else is the same as in Example 1.

[0056] Comparative Example 4 The difference between this comparative example and Example 1 is as follows: The carbon black was not pretreated before use; Everything else is the same as in Example 1.

[0057] Performance testing 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.

[0058] Table 1 Welding process performance test results

[0059] Table 2 Test Results of Weld Overlay Layer

[0060] Based on the performance test results in Tables 1 and 2, analysis of Examples 1-9 and Comparative Examples 1-4 shows that: 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.

[0061] 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.

[0062] 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 specified ratio, 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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