Seamless flux-cored wire for 10crnicu steel for ships

Abstract

A seamless flux-cored wire for 10CrNiCu steel for ships, applied to welding of continuous casting 907A steel for a main hull and composed of a low-carbon steel sheath and a flux core. The diameter of the wire is 1.0-1.4 mm; the filling rate of flux-cored powder is 14%-16%; measured as the mass percentage of the flux-cored wire, the flux core contains rutile, aluminum oxide, ferroboron, zircon sand, quartz, bismuth oxide, potassium titanate, sodium fluoride, electrolytic manganese, ferrotitanium, magnesium powder, manganese-silicon alloy, nickel powder, metal chromium, copper powder, and iron powder. The seamless flux-cored wire for 10CrNiCu steel for ships has the advantages of good welding performance, stable mechanical properties, good crack resistance, low diffusion hydrogen content, high moisture absorption resistance, excellent rust resistance, and the like. Also provided is a method for manufacturing the seamless flux-cored wire for 10CrNiCu steel for ships

Description

A seamless flux-cored welding wire for 10CrNiCu steel for ships Technical Field

[0001] The invention belongs to the technical field of welding materials, and in particular relates to a seamless flux-cored welding wire for 10CrNiCu steel of ships. Background Art

[0002] 10CrNiCu steel (907A steel) is a hull structural material suitable for 390MPa-class ships. 10CrNiCu steel is a 390MPa-class main hull structural steel for ships, improved from the original 907 steel by reducing Si, increasing Mn, and performing microalloying. Due to its excellent overall mechanical properties and seawater corrosion resistance, it is currently used in the non-pressure hulls of submarines, new missile frigates, and other small and medium-sized ships. Currently, the welding materials used in the continuous-cast 907A steel welding construction for surface ships primarily include 907A flux-cored wire, TH907A welding rods, and 907A submerged arc welding wire with 705-ch flux.

[0003] The 10CrNiCu flux-cored welding wire currently used in shipyards is all seamed. The technical requirements for the supply of 10CrNiCu steel flux-cored welding wire require a diffusible hydrogen content of less than 6ml / 100g (as determined by mercury or gas chromatography). However, existing seamed 10CrNiCu flux-cored wire often fails to meet the diffusible hydrogen standards during the supply process, hindering delivery schedules. Furthermore, existing seamed 10CrNiCu flux-cored wire is almost always vacuum-packed to prevent moisture absorption. During transportation, vacuum bags are often damaged by road jitters or friction between wire reels. Seamed flux-cored wire that is unpacked or whose vacuum packaging is damaged during use is susceptible to moisture absorption and rust, leading to increased diffusible hydrogen content in the weld metal and a greater tendency to crack. Furthermore, moisture-absorbed flux-cored wire increases porosity sensitivity during welding, ultimately degrading weld quality and the mechanical properties of the welded joint. Currently, some manufacturers are using 5kg / reel of flux-cored wire for shipyards in an effort to mitigate moisture absorption issues with seamed 10CrNiCu flux-cored wire, both from prolonged exposure and from unused material. However, using 5kg / reel increases the frequency of wire reel changes, reducing welder efficiency. This suggests that using smaller reels is not a fundamental solution to addressing moisture absorption and the high diffusible hydrogen levels associated with seamed 10CrNiCu flux-cored wire.

[0004] Currently, some countries have begun adopting seamless flux-cored wire for welding ship hull steel. For example, the United States has adopted seamless flux-cored wire for the HY-80 and HY-100 steels used in submarine and aircraft carrier hull structures. Seamless flux-cored wire is also widely used in welding other high-strength steels, such as those in marine engineering and bridges.

[0005] The advantages of seamless flux-cored welding wire over traditional seamed flux-cored welding wire are: ① Ultra-low diffusible hydrogen, the diffusible hydrogen content is generally less than 3.5ml / 100g. Ultra-low diffusible hydrogen can effectively reduce the crack incidence of weld metal and has high porosity resistance. This is because seamless flux-cored welding wire can undergo a high-temperature dehydrogenation treatment during production, which can reduce the moisture content (one of the sources of hydrogen) in the flux core powder and attached to the outer steel strip. Secondly, it has extremely strong resistance to moisture absorption. After the seamless flux-cored welding wire is formed, the outer steel strip has a seamless structure with no gaps, so the flux core powder inside the wire will not absorb moisture at all. Therefore, seamless flux-cored welding wire has extremely strong resistance to moisture absorption and does not require re-drying even when stored in a humid environment for a long time. Thirdly, the surface of the welding wire can be copper-plated, which provides excellent wire feedability and reduces wear on the conductive nozzle. Copper plating can improve current transmission capacity and improve rust resistance of the copper-plated welding wire. Fourthly, the outer steel strip has no gaps, and the cross-sectional shape of the welding wire is uniform and rigid. The welding wire does not twist or deform during use, and the wire feedability and alignment are excellent. The arc is more stable, which can be used in fully automatic welding with more mechanized robots (manipulators), significantly improving welding efficiency and saving overall costs. Therefore, seamless flux-cored welding wire can fundamentally solve the problems of moisture absorption and high diffusible hydrogen.

[0006] With the implementation of China's maritime power plan and the intensification of maritime territorial disputes, the number of Chinese ships built has also increased abnormally. Among them, the use of flux-cored welding wire matched with 10CrNiCu steel has also gradually increased. At the same time, the development of welding technology has also put forward higher requirements on the quality and quality of flux-cored welding wire matched with 10CrNiCu steel.

[0007] Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a seamless flux-cored welding wire for 10CrNiCu steel of ships, which is used for welding 10CrNiCu steel of the main hull. It has the advantages of good welding processability, stable mechanical properties, good crack resistance, low diffusible hydrogen, strong moisture absorption resistance, and excellent rust resistance. It is helpful to promote the upgrading of flux-cored welding wire for ship steel welding in my country and improve the quality of ship construction.

[0009] In order to solve the above technical problems, the present invention provides a seamless flux-cored welding wire for 10CrNiCu steel for ships, which is composed of a low-carbon steel outer sheath and a flux core. The contents of the components in the flux core are as follows, calculated as a percentage by mass of the flux-cored welding wire: 37-42% rutile, 1-2% alumina, 0.2-0.5% ferroboron, 1-3% zircon sand, 2-5% quartz, 0.2-0.4% bismuth oxide, 2-5% potassium titanate, 3-5% sodium fluoride, 2-5% electrolytic manganese, 1-3% ferrotitanium, 4-7% magnesium powder, 10-15% manganese silicon alloy, 7-10% nickel powder, 0.2-0.5% metallic chromium, 0.5-1% copper powder, and the rest is iron powder.

[0010] The present invention's seamless flux-cored welding wire for 10CrNiCu shipbuilding steel utilizes a titanium-alkali flux-cored wire slag system. The TiO2 slag has a high solidification temperature and is suitable for all-position welding. Rutile is the primary slag-forming agent and arc stabilizer, regulating the melting point and viscosity of the slag, improving weld formation and slag removal. Alumina regulates the viscosity of molten iron and slag, facilitating all-position welding. However, excessive addition can increase smoke and spatter, so the amount of alumina added should be controlled between 1 and 2%. Boron and titanium form Ti-B compounds in the weld metal, promoting the formation of acicular ferrite and improving the impact toughness of the weld metal. Boron has a low melting point, and excessive addition can easily precipitate at grain boundaries, causing thermal cracking. Therefore, the appropriate amount of ferroboron added is 0.2 to 0.5%. Zircon sand and quartz can adjust the melting point and viscosity of the slag, making it suitable for all-position welding. Quartz also improves slag spreadability, facilitating weld formation. However, excessive amounts can lower the slag's melting point, hindering weld formation during vertical welding. Therefore, the zircon sand addition level should be 1-3%, and the quartz addition level should be 2-5%. The addition of bismuth oxide facilitates slag removal during flux-cored welding, resulting in a smooth weld. However, bismuth has a low melting point, and excessive addition can easily precipitate at grain boundaries, causing thermal cracking. The optimal bismuth oxide addition level is 0.2-0.4%. During welding, the potassium ions of potassium titanate stabilize the arc, but excessive additions can increase smoke and dust. Therefore, the potassium titanate addition level should be controlled between 2-5%. Sodium fluoride can constrict the arc during welding, increasing arc penetration and penetration depth, thereby preventing incomplete penetration. Furthermore, the fluoride ions produced by the high-temperature decomposition of sodium fluoride can dehydrogenate, reducing the content of diffusible hydrogen in the weld metal. However, adding too much sodium fluoride can increase spatter, so the amount of sodium fluoride should be controlled between 3 and 5%. Electrolytic manganese and manganese silicon alloys neutralize manganese and silicon, improving the tensile strength and toughness of the weld metal while deoxidizing it. Too low a content will result in a weld metal with too low strength, while too high a content will result in a weld metal with too high strength and reduced toughness. Therefore, the amount of electrolytic manganese added is 2 to 5%, and the amount of manganese silicon alloy added is 10 to 15%. The main purpose of adding ferrotitanium is to deoxidize. In addition, titanium oxide can act as a strong hydrogen trap, which can solidify a large amount of hydrogen, thereby effectively reducing the content of diffusible hydrogen in the deposited metal. Since Ti has a strong affinity for oxygen, Ti in the weld is dispersed in the form of tiny oxide particles (TiO, Ti2O3, TiO2), which can easily become the nucleation core of acicular ferrite, which is conducive to the formation of acicular ferrite structure, thereby improving the toughness of the weld metal. The amount of ferrotitanium added should be controlled at 1-3%.The primary purpose of adding magnesium powder is also deoxidation. The deoxidation products incorporated into the deposited metal can improve the tensile strength of the weld metal. A small amount of magnesium oxide can enter the weld metal as inclusions, increasing the hardness and strength of the steel. The majority of the magnesium deoxidation products enter the slag, raising the slag's melting point and making the wire suitable for all-position welding. Too little deoxidation can lead to porosity, while too much increases smoke and impairs weld processability. Therefore, the magnesium powder addition level is controlled between 4 and 7%. Nickel powder is primarily added to improve the impact toughness of the weld metal, and the nickel powder addition level is 7 to 10%. Chromium powder is primarily used to lower the ductile-brittle transition temperature of the weld joint and improve its strength. Too little can result in an excessively high ductile-brittle transition temperature, while too much can lead to excessive strength, hindering toughness. The ideal chromium powder addition level is 0.2 to 0.5%. Copper has a precipitation strengthening effect, but excessive copper can easily increase the tendency to produce liquefaction cracks. An appropriate amount of Cu can improve the strength, toughness and corrosion resistance of the weld. When the Cu content of the deposited metal is less than 1.0%, the weld strength is improved by solid solution strengthening and the acicular ferrite content is increased. When the Cu content is greater than 1.0%, the weld is strengthened by precipitation, but it is not conducive to the toughness of the weld. Therefore, the copper powder content in the flux core component is controlled between 0.5 and 1%.

[0011] Compared with existing seamless flux-cored welding wires, the present invention's 10CrNiCu steel seamless flux-cored welding wire for ships offers the following advantages: It can be used for welding 10CrNiCu steel and has a lower diffusible hydrogen content, with the deposited metal containing 2.46 ml / 100 g of diffusible hydrogen. The welded joint exhibits excellent seawater corrosion resistance, with the stable corrosion potential of the sample being -713 mV. It also exhibits excellent weld crack resistance, with a drop-hammer test showing a 1.2 mm thick 10CrNiCu steel weld NDT of -55°C (P-3 sample). It also offers excellent weldability, enabling all-position welding with a stable arc, easy slag removal, and minimal spatter.

[0012] Specifically, the diameter of the seamless flux-cored welding wire for continuous casting 907A steel of the present invention is 1.0-1.4 mm, and the filling rate of the flux-cored powder is 14-16%.

[0013] The preparation process of the seamless flux-cored welding wire for 10CrNiCu steel for ships described in the present invention is as follows: preparation of flux powder; storage, unloading, cleaning, drying, leveling of steel strips, and roller forming; online synchronous addition of flux-cored powder; online welding; manufacturing and annealing of coarse wire rods; manufacturing and annealing of fine wire rods; drawing and reducing the diameter of the welding wire; copper plating and polishing of the welding wire; batching and testing of the welding wire to prepare the finished welding wire.

[0014] Compared with the existing manufacturing methods of seamless flux-cored welding wire for ship 10CrNiCu steel, the preparation method of the present invention has the following advantages: the use of thick and wide steel strips has higher production efficiency and lower cost; the use of online high-frequency welding has high welding quality; and the use of online detection technology has accurate welding quality detection.

[0015] The seamless flux-cored welding wire for 10CrNiCu steel for ships of the present invention is used for welding 10CrNiCu steel for main hulls and has good welding processability, stable mechanical properties, good crack resistance, low diffusible hydrogen, strong moisture absorption resistance and excellent rust resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flow chart of the manufacturing process of seamless flux-cored welding wire for 10CrNiCu steel for ships.

[0017] Figure 2 is a morphology of the flat welding bead of seamless flux-cored wire for ship 10CrNiCu steel.

[0018] Figure 3 shows the metallographic structure of the welded joint of 10CrNiCu steel seamless flux-cored wire for ships.

[0019] Figure 4 shows the corrosion potential-time curve of the welded joint of 10CrNiCu steel seamless flux-cored wire for ships. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and examples.

[0021] Example 1:

[0022] A seamless flux-cored welding wire for 10CrNiCu steel for ships, comprising a low-carbon steel sheath and a flux core, with a wire diameter of 1.4 mm and a flux core powder filling rate of 15%. The flux core comprises, as a percentage by mass of the flux-cored welding wire, 40% rutile, 1.5% alumina, 0.5% ferroboron, 1% zircon sand, 2% quartz, 0.4% bismuth oxide, 3% potassium titanate, 5% sodium fluoride, 5% electrolytic manganese, 2% ferrotitanium, 5% magnesium powder, 13% manganese silicon alloy, 10% nickel powder, 0.5% metallic chromium, 1% copper powder, and the remainder iron powder.

[0023] The manufacturing process, as shown in Figure 1, includes the following steps:

[0024] (1) Preparation of medicinal powder:

[0025] ① Powder mixing should be performed using a calibrated, valid scale before use. Scales with different ranges and accuracy levels should be used for weighing, depending on the amount of raw materials added. In principle, a scale with a range greater than and close to the weight of the powder being mixed should be used, and the scale's accuracy should be higher than Class 0-III.

[0026] ② Prepare powder according to the welding wire formula and verify the total weight. The weight of a single barrel of powder shall not exceed 30 kg. The total weight deviation shall not exceed ±0.5% of the theoretical weight of the powder. Powder outside the deviation range shall not be put into use.

[0027] ③ Place the qualified core powder into a suitable mixer for mixing. The mixing time should be no less than 60 minutes. It is recommended to use a V-type mixer with a capacity suitable for the powder weight.

[0028] ④Put the evenly mixed powder into the hopper and dry it in an oven at 120-150°C for at least 120 minutes. (After drying, powder that is not put into production should be kept warm in the oven. Powder that is not yet mixed can also be kept warm in the oven until mixed.) The hopper should be labeled with the brand of welding wire produced, powder weight, date, and other information.

[0029] (2) Storing, unloading, cleaning, drying, leveling and rolling of steel strips:

[0030] ① Before uncoiling, inspect all surfaces and sides of the steel strip for rust. If rust is present, polish it with a grinding wheel; otherwise, it cannot be put into production. Each coil of steel strip is butt-welded using an argon arc welder and then driven into a looper storage tray. The recommended welding current is 200 ± 10A, and the argon gas flow rate is 10-20 L / min. The steel strip passes through the storage and unloading devices and enters the cleaning device.

[0031] ② After the steel strip enters the cleaning device, ultrasonic cleaning is used to remove oil, dust, water and other impurities on the surface of the steel strip.

[0032] ③After cleaning, the steel strip enters the drying device and is dried by blast air.

[0033] ④The dried steel strip enters the leveling device to make it flat.

[0034] ⑤ The flattened steel strip is rolled into a "U" shape.

[0035] (3) Add core powder online synchronously:

[0036] ① Input the actual measured steel strip width and thickness values ​​into the steel strip size parameter column in the powder feeder operation interface, and set the powder filling rate to 15%.

[0037] ② When the equipment is running stably, start the powder adding device to produce coarse wire rods. The working conditions of each equipment should be monitored at all times during production.

[0038] ③ During the production process, the amount of medicinal powder in the V-shaped hopper of the powder adding machine should be ensured to be no less than 20 kg. Vibration should be avoided when adding medicinal powder to avoid affecting the filling rate.

[0039] (4) Online welding:

[0040] ①Welding power 2.0kW, steel strip running speed 0.08m / s, extrusion volume 3mm.

[0041] ②Online eddy current testing is used to detect the welding quality, and it should be ensured that the weld is firmly welded and the internal and external burrs do not affect the subsequent wire drawing.

[0042] (5) Coarse wire rod manufacturing and annealing:

[0043] ① Each roll of unannealed thick wire rod produced should be marked with the wire brand and nominal wire rod specifications. Status (cold rolled), weight, production date, coil number, etc.

[0044] ② Samples should be taken from the beginning and end of each coil of wire rod to test the filling rate. When two adjacent coils of wire rod are connected end to end, a filling rate test sample can be taken at the connection point, and the sampling length should be 130-160 mm. A balance with a maximum range of 200 g and a graduation value of 0.1 g should be used for the filling rate test. The test results should be recorded in the corresponding production process record card, and the record should correspond to the coil number of the wire rod. When the filling rate of the wire rod meets the technical index requirements, it can be transferred to subsequent processing. If the filling rate of the wire rod does not meet the requirements, it shall not be transferred to subsequent production. The unannealed coarse wire rod is inspected coil by coil by visual inspection. If no cracking is found, it is qualified. For cracked wire rods, the cracked part should be removed.

[0045] ③ Small coils of thick wire rods that have passed the inspection should be annealed in an annealing furnace with atmosphere protection (normal purity nitrogen). Annealing system: charging temperature not higher than 200℃, heating time: 120 minutes, holding temperature: 650±10℃, holding time: determined by annealing equipment, charging capacity, etc. (60 to 240 minutes is recommended when the charging capacity is less than 2.5 tons). After annealing, the thick wire rods should be cooled in the furnace to below 300℃ before being removed from the furnace for air cooling.

[0046] ④ The wire brand and nominal wire rod specifications should be marked on the annealed thick wire rod. Status (annealed), weight, production date, coil number (the same as the coil number of unannealed rough wire rod), etc.

[0047] (6) Manufacturing and annealing of thin wire rods:

[0048] ①Use a fine reducing mill to roll the annealed thick wire rod (temperature not higher than 60℃) to obtain a fine wire rod with a nominal diameter of 6.5mm or 5.5mm.

[0049] ② Visually inspect each roll of thin wire rod. If no cracks or other defects that may affect subsequent production are found, the wire rod is considered qualified. Otherwise, it should be rejected. Each roll of qualified thin wire rod should be labeled with the roll number (the same as the roll number of the thick wire rod) and weight.

[0050] ③ Qualified fine wire rods should be annealed in an annealing furnace with atmosphere protection (normal purity nitrogen). Annealing system: charging temperature not higher than 200°C, heating time: 120 minutes, holding temperature: 650±10°C, holding time: determined by annealing equipment, charging capacity, etc. (60 to 360 minutes is recommended when the charging capacity is less than 2.5 tons). After annealing, the fine wire rods should be cooled in the furnace to below 300°C before being removed from the furnace for air cooling.

[0051] ④ After annealing, the thin wire rod should be labeled with the brand, specification, state (annealed state), weight, date, coil number (the same as the coil number before annealing) and other information.

[0052] (7) Welding wire drawing and reducing diameter, welding wire copper plating and polishing:

[0053] ① If oxide scale appears on the surface of the annealed fine wire rod after long-term storage, pickling or mechanical methods should be used to remove the surface oxide scale. Hydrochloric acid, sulfuric acid or a mixture of the two acids can be used for pickling. In order to improve the pickling effect or efficiency, the acid solution can be heated or an electrolysis process can be added. If the acid solution contains hydrochloric acid, the acid solution heating temperature must not exceed 60°C to prevent the generation of a large amount of acid mist. The pickling time is determined by the surface oxide scale of the wire rod being clean. After pickling, the residual acid on the surface of the wire rod should be rinsed with clean water. If some oxide scale still remains, it can be removed by re-pickling or grinding according to the amount of residue to ensure that there is no oxide scale residue on the surface of the wire rod. The wire rod that has passed the pickling should be promptly surface coated. The coating can be made of borax or saponified liquid. When applying borax, the solution temperature should be maintained at 80-100°C, and the solution specific gravity range is: 1.15-1.30g / cm 3 After coating, the wire rod should be dried promptly to prevent rust or affect subsequent drawing lubrication.

[0054] ② Drawing and reducing: When drawing wire, polycrystalline diamond dies are recommended for the finished pass and the pass preceding the finished product, while carbide dies are recommended for other passes. Sodium soap drawing powder is recommended as a lubricant when drawing the wire. The wire drawing process can be adjusted appropriately based on changes in equipment and dies.

[0055] ③Welding wire copper plating polishing

[0056] Welding wire copper plating process: mechanical degreasing → hot water scrubbing → electrolytic alkaline cleaning → hot water scrubbing → water washing → electrolytic pickling → activated pickling → water washing → copper plating → neutralization water washing → hot water rinsing → drying → polishing and sizing.

[0057] (8) After the welding wires are batched and inspected, the seamless flux-cored welding wire is obtained:

[0058] ① Each batch of welding wire should be made from the same size and batch number of steel strip and the same batch number of primary flux core raw materials, using the same formula and manufacturing process. The maximum weight of each batch of welding wire is 50 tons. One reel of welding wire from each batch should be selected for inspection.

[0059] ② The inner packaging of welding wire shall be sealed with heat-shrinkable plastic film, and the outer packaging shall be packed in paper boxes. The outer packaging of each piece of welding wire and the side edge of the welding wire reel shall be marked with: standard number, welding wire model or brand; trademark and manufacturer name; specification and net weight; batch number and inspection number; production date, etc.

[0060] Example 2:

[0061] A seamless flux-cored welding wire for 10CrNiCu steel for ships, comprising a low-carbon steel sheath and a flux core, with a wire diameter of 1.0 mm and a flux core powder filling rate of 14%. The contents of the flux core, calculated as a percentage by mass of the flux-cored welding wire, are as follows: 37% rutile, 1% alumina, 0.2% ferroboron, 3% zircon sand, 5% quartz, 0.3% bismuth oxide, 2% potassium titanate, 3% sodium fluoride, 3.5% electrolytic manganese, 3% ferrotitanium, 4% magnesium powder, 15% manganese silicon alloy, 7% nickel powder, 0.3% metallic chromium, 0.7% copper powder, and the balance iron powder.

[0062] The manufacturing process, as shown in Figure 1, includes the following steps:

[0063] (1) Preparation of medicinal powder:

[0064] ① Powder mixing should be performed using a calibrated, valid scale before use. Scales with different ranges and accuracy levels should be used based on the amount of raw materials added. In principle, a scale with a range greater than and close to the weight of the powder being mixed should be used, and the scale's accuracy should be higher than Class 0-III.

[0065] ② Prepare powder according to the welding wire formula and verify the total weight. The weight of a single barrel of powder shall not exceed 30 kg. The total weight deviation shall not exceed ±0.5% of the theoretical weight of the powder. Powder outside the deviation range shall not be put into use.

[0066] ③Put the qualified core powder into a suitable mixer for mixing. The mixing time should be no less than 60 minutes.

[0067] It is recommended to use a V-type mixer with a capacity suitable for the powder weight to mix the powder.

[0068] ④Put the evenly mixed powder into the hopper and dry it in an oven at 120-150°C for at least 120 minutes. (After drying, powder that is not put into production should be kept warm in the oven. Powder that is not yet mixed can also be kept warm in the oven until mixed.) The hopper should be labeled with the brand of welding wire produced, powder weight, date, and other information.

[0069] (2) Storing, unloading, cleaning, drying, leveling and rolling of steel strips:

[0070] ① Before uncoiling, inspect all surfaces and sides of the steel strip for rust. If rust is present, polish it with a grinding wheel; otherwise, it cannot be put into production. Each coil of steel strip is butt-welded using an argon arc welder and then driven into a looper storage tray. The recommended welding current is 200 ± 10A, and the argon gas flow rate is 10-20 L / min. The steel strip passes through the storage and unloading devices and enters the cleaning device.

[0071] ② After the steel strip enters the cleaning device, ultrasonic cleaning is used to remove oil, dust, water and other impurities on the surface of the steel strip.

[0072] ③After cleaning, the steel strip enters the drying device and is dried by blast air.

[0073] ④The dried steel strip enters the leveling device to make it flat.

[0074] ⑤ The flattened steel strip is rolled into a "U" shape.

[0075] (3) Add core powder online synchronously:

[0076] ① Input the actual measured steel strip width and thickness values ​​into the steel strip size parameter column in the powder feeder operation interface, and set the powder filling rate to 14%.

[0077] ② When the equipment is running stably, start the powder adding device to produce coarse wire rods. The working conditions of each equipment should be monitored at all times during production.

[0078] ③ During the production process, the amount of medicinal powder in the V-shaped hopper of the powder adding machine should be ensured to be no less than 20 kg. Vibration should be avoided when adding medicinal powder to avoid affecting the filling rate.

[0079] (4) Online welding:

[0080] ①Welding power 2.7kW, steel strip running speed 0.15m / s, extrusion volume 3mm.

[0081] ②Online eddy current testing is used to detect the welding quality, and it should be ensured that the weld is firmly welded and the internal and external burrs do not affect the subsequent wire drawing.

[0082] (5) Coarse wire rod manufacturing and annealing:

[0083] ① Each roll of unannealed thick wire rod produced should be marked with the wire brand and nominal wire rod specifications. Status (cold rolled), weight, production date, coil number, etc.

[0084] ② Samples should be taken from the beginning and end of each coil of wire rod to test the filling rate. When two adjacent coils of wire rod are connected end to end, a filling rate test sample can be taken at the connection point, and the sampling length should be 130-160 mm. A balance with a maximum range of 200 g and a graduation value of 0.1 g should be used for the filling rate test. The test results should be recorded in the corresponding production process record card, and the record should correspond to the coil number of the wire rod. When the filling rate of the wire rod meets the technical index requirements, it can be transferred to subsequent processing. If the filling rate of the wire rod does not meet the requirements, it shall not be transferred to subsequent production. The unannealed coarse wire rod is inspected coil by coil by visual inspection. If no cracking is found, it is qualified. For cracked wire rods, the cracked part should be removed.

[0085] ③ Small coils of thick wire rods that have passed the inspection should be annealed in an annealing furnace with atmosphere protection (normal purity nitrogen). Annealing system: charging temperature not higher than 200℃, heating time: 120 minutes, holding temperature: 650±10℃, holding time: determined by annealing equipment, charging capacity, etc. (60 to 240 minutes is recommended when the charging capacity is less than 2.5 tons). After annealing, the thick wire rods should be cooled in the furnace to below 300℃ before being removed from the furnace for air cooling.

[0086] ④ The wire brand and nominal wire rod specifications should be marked on the annealed thick wire rod. Status (annealed), weight, production date, coil number (the same as the coil number of unannealed rough wire rod), etc.

[0087] (6) Manufacturing and annealing of thin wire rods:

[0088] ①Use a fine reducing mill to roll the annealed thick wire rod (temperature not higher than 60℃) to obtain a fine wire rod with a nominal diameter of 6.5mm or 5.5mm.

[0089] ② Visually inspect each roll of thin wire rod. If no cracks or other defects that may affect subsequent production are found, the wire rod is considered qualified. Otherwise, it should be rejected. Each roll of qualified thin wire rod should be labeled with the roll number (the same as the roll number of the thick wire rod) and weight.

[0090] ③ Qualified fine wire rods should be annealed in an annealing furnace with atmosphere protection (normal purity nitrogen). Annealing system: charging temperature not higher than 200°C, heating time: 120 minutes, holding temperature: 650±10°C, holding time: determined by annealing equipment, charging capacity, etc. (60 to 360 minutes is recommended when the charging capacity is less than 2.5 tons). After annealing, the fine wire rods should be cooled in the furnace to below 300°C before being removed from the furnace for air cooling.

[0091] ④ After annealing, the thin wire rod should be labeled with the brand, specification, state (annealed state), weight, date, coil number (the same as the coil number before annealing) and other information.

[0092] (7) Welding wire drawing and reducing diameter, welding wire copper plating and polishing:

[0093] ① If oxide scale appears on the surface of the annealed fine wire rod after long-term storage, pickling or mechanical methods should be used to remove the surface oxide scale. Hydrochloric acid, sulfuric acid or a mixture of the two acids can be used for pickling. In order to improve the pickling effect or efficiency, the acid solution can be heated or an electrolysis process can be added. If the acid solution contains hydrochloric acid, the acid solution heating temperature must not exceed 60°C to prevent the generation of a large amount of acid mist. The pickling time is determined by the surface oxide scale of the wire rod being clean. After pickling, the residual acid on the surface of the wire rod should be rinsed with clean water. If some oxide scale still remains, it can be removed by re-pickling or grinding according to the amount of residue to ensure that there is no oxide scale residue on the surface of the wire rod. The wire rod that has passed the pickling should be promptly surface coated. The coating can be made of borax or saponified liquid. When applying borax, the solution temperature should be maintained at 80-100°C, and the solution specific gravity range is: 1.15-1.30g / cm 3 After coating, the wire rod should be dried promptly to prevent rust or affect subsequent drawing lubrication.

[0094] ② Drawing and reducing: When drawing wire, polycrystalline diamond dies are recommended for the finished pass and the pass preceding the finished product, while carbide dies are recommended for other passes. Sodium soap drawing powder is recommended as a lubricant when drawing the wire. The wire drawing process can be adjusted appropriately based on changes in equipment and dies.

[0095] ③Welding wire copper plating polishing

[0096] Welding wire copper plating process: mechanical degreasing → hot water scrubbing → electrolytic alkaline cleaning → hot water scrubbing → water washing → electrolytic pickling → activated pickling → water washing → copper plating → neutralization water washing → hot water rinsing → drying → polishing and sizing.

[0097] (8) After the welding wires are batched and inspected, the seamless flux-cored welding wire is obtained:

[0098] ① Each batch of welding wire should be made from the same size and batch number of steel strip and the same batch number of primary flux core raw materials, using the same formula and manufacturing process. The maximum weight of each batch of welding wire is 50 tons. One reel of welding wire from each batch should be selected for inspection.

[0099] ② The inner packaging of welding wire shall be sealed with heat-shrinkable plastic film, and the outer packaging shall be packed in paper boxes. The outer packaging of each piece of welding wire and the side edge of the welding wire reel shall be marked with: standard number, welding wire model or brand; trademark and manufacturer name; specification and net weight; batch number and inspection number; production date, etc.

[0100] Example 3:

[0101] A seamless flux-cored welding wire for 10CrNiCu steel for ships, comprising a low-carbon steel sheath and a flux core, with a wire diameter of 1.2 mm and a flux core powder filling rate of 16%. The contents of the flux core, as a percentage of the flux core wire mass, are as follows: 42% rutile, 2% alumina, 0.3% ferroboron, 2% zircon sand, 4% quartz, 0.2% bismuth oxide, 5% potassium titanate, 4% sodium fluoride, 2% electrolytic manganese, 1% ferrotitanium, 7% magnesium powder, 10% manganese silicon alloy, 9% nickel powder, 0.2% metallic chromium, 0.5% copper powder, and the balance iron powder.

[0102] The manufacturing process, as shown in Figure 1, includes the following steps:

[0103] (1) Preparation of medicinal powder:

[0104] ① Powder mixing should be performed using a calibrated, valid scale before use. Scales with different ranges and accuracy levels should be used based on the amount of raw materials added. In principle, a scale with a range greater than and close to the weight of the powder being mixed should be used, and the scale's accuracy should be higher than Class 0-III.

[0105] ② Prepare powder according to the welding wire formula and verify the total weight. The weight of a single barrel of powder shall not exceed 30 kg. The total weight deviation shall not exceed ±0.5% of the theoretical weight of the powder. Powder outside the deviation range shall not be put into use.

[0106] ③Put the qualified core powder into a suitable mixer for mixing. The mixing time should be no less than 60 minutes.

[0107] It is recommended to use a V-type mixer with a capacity suitable for the powder weight to mix the powder.

[0108] ④Put the evenly mixed powder into the hopper and dry it in an oven at 120-150°C for at least 120 minutes. (After drying, powder that is not put into production should be kept warm in the oven. Powder that is not yet mixed can also be kept warm in the oven until mixed.) The hopper should be labeled with the brand of welding wire produced, powder weight, date, and other information.

[0109] (2) Storing, unloading, cleaning, drying, leveling and rolling of steel strips:

[0110] ① Before uncoiling, inspect all surfaces and sides of the steel strip for rust. If rust is present, polish it with a grinding wheel; otherwise, it cannot be put into production. Each coil of steel strip is butt-welded using an argon arc welder and then driven into a looper storage tray. The recommended welding current is 200 ± 10A, and the argon gas flow rate is 10-20 L / min. The steel strip passes through the storage and unloading devices and enters the cleaning device.

[0111] ② After the steel strip enters the cleaning device, ultrasonic cleaning is used to remove oil, dust, water and other impurities on the surface of the steel strip.

[0112] ③After cleaning, the steel strip enters the drying device and is dried by blast air.

[0113] ④The dried steel strip enters the leveling device to make it flat.

[0114] ⑤ The flattened steel strip is rolled into a "U" shape.

[0115] (3) Add core powder online synchronously:

[0116] ① Input the actual measured steel strip width and thickness values ​​into the steel strip size parameter column in the powder feeder operation interface, and set the powder filling rate to 16%.

[0117] ② When the equipment is running stably, start the powder adding device to produce coarse wire rods. The working conditions of each equipment should be monitored at all times during production.

[0118] ③ During the production process, the amount of medicinal powder in the V-shaped hopper of the powder adding machine should be ensured to be no less than 20 kg. Vibration should be avoided when adding medicinal powder to avoid affecting the filling rate.

[0119] (4) Online welding:

[0120] ①Welding power 2.5kW, steel strip running speed 0.15m / s, extrusion volume 3mm.

[0121] ②Online eddy current testing is used to detect the welding quality, and it should be ensured that the weld is firmly welded and the internal and external burrs do not affect the subsequent wire drawing.

[0122] (5) Coarse wire rod manufacturing and annealing:

[0123] ① Each roll of unannealed thick wire rod produced should be marked with the wire brand and nominal wire rod specifications. Status (cold rolled), weight, production date, coil number, etc.

[0124] ② Samples should be taken from the beginning and end of each coil of wire rod to test the filling rate. When two adjacent coils of wire rod are connected end to end, a filling rate test sample can be taken at the connection point, and the sampling length should be 130-160 mm. A balance with a maximum range of 200 g and a graduation value of 0.1 g should be used for the filling rate test. The test results should be recorded in the corresponding production process record card, and the record should correspond to the coil number of the wire rod. When the filling rate of the wire rod meets the technical index requirements, it can be transferred to subsequent processing. If the filling rate of the wire rod does not meet the requirements, it shall not be transferred to subsequent production. The unannealed coarse wire rod is inspected coil by coil by visual inspection. If no cracking is found, it is qualified. For cracked wire rods, the cracked part should be removed.

[0125] ③ Small coils of thick wire rods that have passed the inspection should be annealed in an annealing furnace with atmosphere protection (normal purity nitrogen). Annealing system: charging temperature not higher than 200℃, heating time: 120 minutes, holding temperature: 650±10℃, holding time: determined by annealing equipment, charging capacity, etc. (60 to 240 minutes is recommended when the charging capacity is less than 2.5 tons). After annealing, the thick wire rods should be cooled in the furnace to below 300℃ before being removed from the furnace for air cooling.

[0126] ④ The wire brand and nominal wire rod specifications should be marked on the annealed thick wire rod. Status (annealed), weight, production date, coil number (the same as the coil number of unannealed rough wire rod), etc.

[0127] (6) Manufacturing and annealing of thin wire rods:

[0128] ①Use a fine reducing mill to roll the annealed thick wire rod (temperature not higher than 60℃) to obtain a fine wire rod with a nominal diameter of 6.5mm or 5.5mm.

[0129] ② Visually inspect each roll of thin wire rod. If no cracks or other defects that may affect subsequent production are found, the wire rod is considered qualified. Otherwise, it should be rejected. Each roll of qualified thin wire rod should be labeled with the roll number (the same as the roll number of the thick wire rod) and weight.

[0130] ③ Qualified fine wire rods should be annealed in an annealing furnace with atmosphere protection (normal purity nitrogen). Annealing system: charging temperature not higher than 200°C, heating time: 120 minutes, holding temperature: 650±10°C, holding time: determined by annealing equipment, charging capacity, etc. (60 to 360 minutes is recommended when the charging capacity is less than 2.5 tons). After annealing, the fine wire rods should be cooled in the furnace to below 300°C before being removed from the furnace for air cooling.

[0131] ④ After annealing, the thin wire rod should be labeled with the brand, specification, state (annealed state), weight, date, coil number (the same as the coil number before annealing) and other information.

[0132] (7) Welding wire drawing and reducing diameter, welding wire copper plating and polishing:

[0133] ① If oxide scale appears on the surface of the annealed fine wire rod after long-term storage, pickling or mechanical methods should be used to remove the surface oxide scale. Hydrochloric acid, sulfuric acid or a mixture of the two acids can be used for pickling. In order to improve the pickling effect or efficiency, the acid solution can be heated or an electrolysis process can be added. If the acid solution contains hydrochloric acid, the acid solution heating temperature must not exceed 60°C to prevent the generation of a large amount of acid mist. The pickling time is determined by the surface oxide scale of the wire rod being clean. After pickling, the residual acid on the surface of the wire rod should be rinsed with clean water. If some oxide scale still remains, it can be removed by re-pickling or grinding according to the amount of residue to ensure that there is no oxide scale residue on the surface of the wire rod. The wire rod that has passed the pickling should be promptly surface coated. The coating can be made of borax or saponified liquid. When applying borax, the solution temperature should be maintained at 80-100°C, and the solution specific gravity range is: 1.15-1.30g / cm 3 After coating, the wire rod should be dried promptly to prevent rust or affect subsequent drawing lubrication.

[0134] ② Drawing and reducing: When drawing wire, polycrystalline diamond dies are recommended for the finished pass and the pass preceding the finished product, while carbide dies are recommended for other passes. Sodium soap drawing powder is recommended as a lubricant when drawing the wire. The wire drawing process can be adjusted appropriately based on changes in equipment and dies.

[0135] ③Welding wire copper plating polishing

[0136] Welding wire copper plating process: mechanical degreasing → hot water scrubbing → electrolytic alkaline cleaning → hot water scrubbing → water washing → electrolytic pickling → activated pickling → water washing → copper plating → neutralization water washing → hot water rinsing → drying → polishing and sizing.

[0137] (8) After the welding wires are batched and inspected, the seamless flux-cored welding wire is obtained:

[0138] ① Each batch of welding wire should be made from the same size and batch number of steel strip and the same batch number of primary flux core raw materials, using the same formula and manufacturing process. The maximum weight of each batch of welding wire is 50 tons. One reel of welding wire from each batch should be selected for inspection.

[0139] ② The inner packaging of welding wire shall be sealed with heat-shrinkable plastic film, and the outer packaging shall be packed in paper boxes. The outer packaging of each piece of welding wire and the side edge of the welding wire reel shall be marked with: standard number, welding wire model or brand; trademark and manufacturer name; specification and net weight; batch number and inspection number; production date, etc.

[0140] The outer sheath of the seamless flux-cored welding wire for 10CrNiCu shipbuilding steel of the present invention is made of ordinary low-carbon steel strip. The chemical composition and properties are shown in Tables 1 and 2. The chemical composition and mechanical properties of the deposited metal of the welding wire are shown in Tables 3 and 4. The diffusible hydrogen content of the deposited metal is shown in Table 5.

[0141] Table 1

[0142] Table 2

[0143] Table 3

[0144] Table 4

[0145] Table 5

[0146] Figure 2 shows the morphology of a flat weld bead made with a seamless flux-cored wire for 10CrNiCu steel used in ships (the image has been grayscaled). The weld bead morphology shows that the wire has excellent weldability, easy slag removal, and minimal spatter. Figure 3 shows the metallographic structure of a welded joint made with a seamless flux-cored wire for 10CrNiCu steel used in ships. The metallographic image shows that the welded joint is primarily composed of acicular ferrite, indicating good impact toughness. Figure 4 shows the corrosion potential-time curve of a welded joint made with a seamless flux-cored wire for 10CrNiCu steel used in ships. The curve shows that the sample exhibits a stable corrosion potential of -713 mV, indicating excellent resistance to seawater corrosion.

[0147] The above is only the best embodiment of the present invention. It should be noted that, for those skilled in the art, without departing from the principles of the present invention, several modifications or equivalent substitutions can be made to the technical solution of the present invention, which should also be considered to fall within the scope of protection of the present invention.

Claims

1. A seamless flux-cored welding wire for ship 10CrNiCu steel, consisting of a low-carbon steel sheath and a flux core, characterized in that: Calculated as a percentage of the mass of the flux-cored welding wire, the contents of each component in the flux core are as follows: 37-42% rutile, 1-2% alumina, 0.2-0.5% ferroboron, 1-3% zircon sand, 2-5% quartz, 0.2-0.4% bismuth oxide, 2-5% potassium titanate, 3-5% sodium fluoride, 2-5% electrolytic manganese, 1-3% ferrotitanium, 4-7% magnesium powder, 10-15% manganese silicon alloy, 7-10% nickel powder, 0.2-0.5% metallic chromium, 0.5-1% copper powder, and the rest is iron powder.

2. The seamless flux-cored welding wire for 10CrNiCu steel for ships according to claim 1, characterized in that: The diameter of the welding wire is 1.0-1.4 mm, and the filling rate of the flux core powder is 14-16%.

3. A method for manufacturing a seamless flux-cored welding wire for ship 10CrNiCu steel, characterized in that: The following steps are involved: (1) Preparation of powder: Powder is prepared according to the content of each component in the core of seamless flux-cored welding wire, and the total weight is checked; the qualified core powder is put into a mixer for mixing, and the evenly mixed core powder is put into a hopper and placed in an oven for drying; (2) Steel strip storage, unwinding, cleaning, drying, leveling and roll forming: Use an argon arc welding machine to butt-weld the polished steel strip and then put it into the storage tray. The welded steel strip passes through the storage device and unwinding device and enters the cleaning device for cleaning. Then it enters the drying device for drying. The dried steel strip enters the leveling device for leveling. The leveled steel strip is then rolled into a "U" shape; (3) Manufacturing and annealing of thick wire rod: input the actual measured steel strip width and thickness values ​​into the steel strip size parameter column in the powder adding machine operation interface, and set the powder filling rate to 14-16%; start the powder adding device to add core powder after the equipment runs stably; set the welding power to 2.5kW, the steel strip running speed to 0.15m / s, and the extrusion volume to 3mm to weld the steel strip to manufacture the thick wire rod; anneal the thick wire rod under the protection of nitrogen atmosphere, and the annealed thick wire rod is cooled with the furnace to ≤300°C and then taken out of the furnace for air cooling; (4) Manufacturing and annealing of fine wire rods: The annealed coarse wire rods are rolled using a fine reducing mill to obtain fine wire rods; the fine wire rods should be annealed under the protection of a nitrogen atmosphere, and the annealed fine wire rods can be cooled with the furnace to ≤300°C and then air-cooled out of the furnace; (5) Drawing and reducing; (6) Copper plating, polishing and sizing of welding wire; (7) After welding wire batching and inspection, seamless flux-cored welding wire for ship 10CrNiCu steel is obtained.

4. The method for manufacturing a seamless flux-cored welding wire for ship 10CrNiCu steel according to claim 3, characterized in that: In step (1), the powder mixing time is ≥60 min; the drying temperature is 120-150° C., and the drying time is ≥120 min.

5. The method for manufacturing a seamless flux-cored welding wire for ship 10CrNiCu steel according to claim 3, characterized in that: In step (2), the welding current of argon arc welding is 200±10A, and the argon gas flow rate is 10-20L / min.

6. The method for manufacturing a seamless flux-cored welding wire for ship 10CrNiCu steel according to claim 3, characterized in that: The furnace temperature for annealing in step (3) is ≤200°C, the heating time is 120min, the holding temperature is 650±10°C, and the holding time is 60-240min.

7. The method for manufacturing a seamless flux-cored welding wire for ship 10CrNiCu steel according to claim 3, characterized in that: The nominal diameter of the thin wire rod in step (4) is Ф6.5mm or Ф5.5mm.

8. The method for manufacturing a seamless flux-cored welding wire for ship 10CrNiCu steel according to claim 7, characterized in that: The charging temperature of the annealing in step (4) is ≤200°C, the heating time is 120min, the holding temperature is 650±10°C, and the holding time is 60-360min.

9. The method for manufacturing a seamless flux-cored welding wire for ship 10CrNiCu steel according to claim 3, characterized in that: Step (5) Before drawing and reducing the diameter of the thin wire rod, the oxide scale on the surface of the wire is removed by pickling or mechanical means, and then the surface is coated with borax or saponified liquid and dried in time.

10. The method for manufacturing a seamless flux-cored welding wire for ship 10CrNiCu steel according to claim 3, characterized in that: In step (5), sodium soap drawing powder is used as a lubricant during drawing and reducing the diameter.

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