High-purity gas shielded alloy welding wire steel rod and preparation method thereof

Abstract

The application discloses a high-cleanliness gas protection alloy welding wire steel wire rod and a preparation method thereof. The preparation method is characterized by the following steps: chemical component design, converter smelting, deoxidization alloying process, slag washing after tapping, LF furnace refining, VD furnace vacuum refining, continuous casting, rolling heating system, controlled rolling, Stelmor controlled cooling and the like. The method has the characteristics of strong process applicability and controllability. The produced ER70S-6 alloy welding wire steel wire rod has high cleanliness, few inclusions, low gas content (O is less than or equal to 0.0015wt%, N is less than or equal to 0.0020wt%), a section shrinkage rate is greater than or equal to 85%, excellent plasticity and toughness and drawing deformation capacity, can draw welding wire with a very thin specification of Φ0.4mm, does not break wire when drawing welding wire with a specification of Φ1.0mm-Φ1.2mm, the wire breaking rate is less than or equal to 0.02 times per ton when drawing welding wire with a specification of Φ0.8mm, the wire breaking rate is less than or equal to 0.04 times per ton when drawing welding wire with a very thin specification of Φ0.4mm-Φ0.6mm, and the market competitiveness and innovation of the product are improved significantly.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel smelting, and particularly relates to a high-cleanliness gas protection alloy welding wire steel wire rod and a preparation method thereof. BACKGROUND

[0002] At present, the alloy welding wire steel wire rod ER70S-6 in China is produced through the process route of molten iron pretreatment, converter smelting, LF furnace refining, (vacuum refining), small billet full-process protection casting, high-speed wire rod mill controlled rolling and controlled cooling, and the control means and management of the whole process of raw and auxiliary materials for steelmaking, steelmaking and rolling process equipment, process control technology, production process management are improved and controlled, so that the surface of the wire rod is free of cracks, folds, scabs and ears and other quality defects. At present, the C content of the ER70S-6 alloy welding wire steel wire rod produced by the process is high, a small amount of granular bainite exists in the microstructure, and the reduction of area is mostly less than 80%, so that the welding wire with a diameter of Φ0.8mm to Φ1.2mm can be drawn, but the welding wire with a diameter of Φ0.4mm to Φ0.6mm cannot be drawn, which restricts the improvement of the product market competitiveness. SUMMARY

[0003] In view of the above problems, the purpose of the present application is to provide a high-cleanliness gas protection alloy welding wire steel wire rod and a preparation method thereof, so as to improve the wire rod drawing efficiency and product quality.

[0004] The purpose of the present application is achieved in the following way: a preparation method of a high-cleanliness gas protection alloy welding wire steel wire rod is achieved in the following steps:

[0005] A, desulfurization of molten iron pretreatment: the molten iron from the blast furnace is transported to the KR molten iron pretreatment device for desulfurization treatment, the molten iron temperature is ≥1350℃, the stirring head insertion depth is controlled to be 2100mm, the conventional CaO desulfurizer is added in an amount of 14.0-16.0kg / t 钢 for desulfurization treatment, and the stirring time is controlled to be 5 minutes; after stirring, the slag is removed to ensure that the molten iron surface in the ladle is exposed ≥4 / 5, and the desulfurization slag is removed completely;

[0006] B, molten steel smelting: the molten iron obtained by pretreatment desulfurization and high-quality scrap steel are added into the LD converter in a loading ratio of 880kg / t 钢 , 175kg / t 钢 , respectively, for conventional top and bottom combined blowing, the converter smelting adopts double-slag smelting, the first batch of slag is added with lime and light-burned dolomite for slagging according to 10-14kg / t 钢 , 10-12kg / t 钢 , respectively, before smelting, the second batch of slag is added after the first batch of slag is removed, and the second batch of slag is added according to 10-12kg / t 钢 , 8kg / t 钢Add lime, light-burned dolomite to slag again, control the C content of the final molten steel 0.03wt%-0.04wt%, and the tapping temperature is ≤1600℃; before tapping, add 1.0-1.5kg / t 钢 of the following mass ratio of slag washing materials to the bottom of the ladle: Al2O3 23.5wt%, SiO2 4.6wt%, CaO 48.5wt%, Al 3.5wt%, MgO 5.4wt%, and the rest is Fe and unavoidable impurities, and adopt the whole bottom blowing nitrogen process during the tapping process, and control the nitrogen flow to be 20-25NL / min;

[0007] C, deoxidization and alloying: after the smelting is completed, the molten steel is tapped, when the amount of molten steel in the ladle is greater than 1 / 4, add the following materials to the ladle in the following order: add the following mass ratio of ferrosilicon in an amount of 12.1-13.2kg / t 钢 : Si 72.2wt%, Al 1.5wt%, P 0.025wt%, S 0.018wt%, and the rest is Fe and unavoidable impurities; add the following mass ratio of low-carbon ferromanganese in an amount of 15.6-17.0kg / t 钢 : Mn 84.5wt%, C 0.3wt%, P 0.024wt%, S 0.015wt%, and the rest is Fe and unavoidable impurities; and the above alloying is completed when the amount of molten steel in the ladle reaches 4 / 5;

[0008] D, LF furnace refining of molten steel: after the tapping is completed, the molten steel is hoisted to the LF furnace refining station and connected to the argon gas belt, and the argon gas is started to blow at a small argon flow of 20-25NL / min for 3 minutes, then the electrode is lowered at a gear position of 7-9 to slag, and 0.3-0.5kg / t 钢 of ferrosilicon powder is added to adjust the slag; after 8 minutes of power supply, the electrode is lifted to observe the slag condition in the furnace, and then the temperature is measured and the sample is taken; if the slag condition is relatively thin, 4.0-5.0kg / t 钢 of lime is added, then 0.5kg / t 钢 of ferrosilicon powder, 0.5kg / t 钢 of calcium carbide is added to adjust the slag, and vice versa, the slag is adjusted by adding pre-melted refining slag, and the slag basicity is controlled to be 4.0-5.0; according to the steel sample analysis results, the alloy is added to adjust the molten steel composition, to ensure that each chemical composition is within the target range, and the oxygen activity of the molten steel is controlled to be ≤10ppm; the number of electrode lowering during the refining process is controlled to be ≤2 times; then the temperature of the molten steel is heated to 1640-1650℃, and the molten steel is soft-blow argon at a small argon flow of 20-25NL / min, and the soft-blow argon time is 10 minutes, then the molten steel covering agent is added, and the addition amount is controlled to be 1.0kg / t of steel, then the molten steel is hoisted to the VD furnace vacuum refining station;

[0009] E, VD furnace vacuum refining: after the molten steel in step D is hoisted to the VD vacuum refining furnace, the argon blowing pipe is connected, and argon is turned on at a small argon flow rate of 20-30 NL / min for 2 minutes. Then the oxygen in the molten steel is determined, and the temperature is measured and sampled. After sampling is completed, the vacuum tank cover vehicle is opened to the working position, the vacuum tank cover is closed, vacuum is drawn, and when the vacuum is drawn to 67 Pa, vacuum degassing treatment is started, and bottom argon blowing treatment is carried out at the same time. The argon flow rate is controlled to be 40-50 NL / min, and the molten steel degassing treatment time is 15 minutes under the condition of a vacuum degree of 67 Pa. After vacuum degassing treatment is completed, the vacuum main valve is closed, the tank cover is lifted, and the molten steel is sampled and the oxygen and hydrogen are determined. Then the molten steel is treated by soft argon blowing at a small argon flow rate, and the argon flow rate is 20-30 NL / min, and the soft argon blowing time is 2 minutes. After the molten steel soft argon blowing is completed, the molten steel is added with a covering agent, and the addition amount is controlled to be 1.0 kg / t 钢 Then the molten steel is hoisted to the casting position;

[0010] F, molten steel casting: under the conditions that the tundish temperature is 1540-1550℃, the withdrawal speed is 2.0-2.1 m / min, the secondary cooling water ratio is 1.3-1.5 L / kg, the crystallizer electromagnetic stirring current intensity is 320 A, and the operating frequency is 4 Hz, the molten steel obtained in step E is continuously cast into a billet with a section of 165 mm x 165 mm by using a R9m straight arc continuous straightening 7-machine 7-stream small billet caster;

[0011] G, billet heating: the billet in step F is sent into a heating furnace with a furnace temperature of 1070-1100℃ in the soaking section, and after heating for 50-70 minutes, the steel is discharged, the scale is removed by high-pressure water, and the billet is pushed to a high-speed wire rod mill for rolling;

[0012] H, controlled rolling and controlled cooling: the billet in step G is sent into a high-speed wire rod mill with 30 stands for rolling, and under the rolling conditions of a speed of 0.4 m / s, the billet is coarsely rolled for 6 passes in the rough rolling mill group. Then under the rolling conditions of a speed of 12.0 m / s, the billet is rolled for 5-6 passes in the intermediate rolling mill group. Then under the rolling conditions of a speed of 50.0 m / s, the billet is rolled for 5 passes in the pre-precision rolling mill group. Then under the rolling conditions of a speed of 60 m / s, the billet is rolled for 5-6 passes in the precision rolling mill group. Then under the rolling conditions of a speed of 65 m / s, the billet is rolled for 2 passes in the reducing and sizing mill group. Then under the conditions of a temperature of 895-920℃ and a speed of 70-85 m / s, the billet is drawn. After drawing, the coil is subjected to air mist cooling and air cooling control in a Stelmor air cooling line, the fan and the heat preservation cover are completely closed, and the roller speed is controlled to be 0.15-0.25 m / s. Then the coil is naturally air cooled to room temperature to obtain a high-cleanliness gas shielded alloy welding wire steel coil with a nominal diameter of 6.0-6.5 mm.

[0013] The high-cleanliness gas shielded alloy wire rod has the following chemical components by weight percentage: C 0.04-0.06wt%, Si 0.77-0.84wt%, Mn 1.35-1.44wt%, S≤0.008wt%, P≤0.008wt%, N≤0.0020wt%, O≤0.0015wt%, and the rest is Fe and inevitable impurities; the high-cleanliness gas shielded alloy wire rod has ferrite grain size of 10.5-11.0, tensile strength Rm of 460-480 MPa, reduction of area Z≥86.0, and wire breakage rate of ≤0.02 times / ton for drawing Φ0.8mm wire, and wire breakage rate of ≤0.04 times / ton for drawing Φ0.4mm-Φ0.6mm wire.

[0014] The present application adopts top and bottom combined blowing full-range argon blowing mode in converter smelting, controls the end point C 0.03wt%-0.04wt%, adopts slag washing material for full-range slag washing in the process of tapping, improves the cleanliness of molten steel; the converter smelting adopts double slag method to remove phosphorus, the dephosphorization rate is >95%, significantly reduces the P content of the end point molten steel, and greatly reduces the harmful element content of the molten steel; the LF furnace adopts silicon iron powder to adjust slag and deoxidize, avoids the formation of Al2O3 brittle inclusions, and improves the drawing performance; the molten steel is soft-blowing argon for 10 minutes at the end of LF furnace refining, and the LF furnace refined molten steel is treated by VD furnace vacuum refining, so that the gas content and inclusions in the steel are significantly reduced, P≤0.008wt%, S≤0.008wt%, O≤0.0015wt%, N≤0.0020wt%, non-metallic inclusions≤0.5 level, and the plasticity and toughness and drawing performance of the wire rod are significantly improved; the rolling process controls lower opening rolling temperature, entry finishing temperature and wire laying temperature, promotes the refinement of austenite grains, speeds up the transformation speed of supercooled austenite in the phase change process, and obtains equiaxed ferrite+pearlite microstructure easy to draw; the wire rod after wire laying is controlled by delayed Stelmor cooling mode, the fan and the heat preservation cover are fully closed, the wire rod is controlled on the Stelmor roller at low roller speed (0.15-0.25m / s), the formation of "hard phase" bainite and martensite is avoided, equiaxed ferrite+pearlite microstructure is obtained, the plasticity and toughness and drawing deformation capacity of the steel are significantly improved, and the wire breakage phenomenon in the wire rod drawing process is effectively avoided.

[0015] The preparation method has the characteristics of strong process applicability and controllability, the produced ER70S-6 alloy welding wire steel has high cleanliness, few inclusions, low gas content (O≤0.0015wt%, N≤0.0020wt%), a section shrinkage rate ≥85%, excellent plasticity and toughness and drawing deformation capacity, can draw Φ0.4mm extremely thin welding wire, the wire is not broken when drawing Φ1.0mm~Φ1.2mm welding wire from the steel wire rod, the wire breakage rate is ≤0.02 times / ton when drawing Φ0.8mm welding wire, the wire breakage rate is ≤0.04 times / ton when drawing extremely thin welding wire Φ0.4mm~Φ0.6mm, and the product market competitiveness and innovation are significantly improved. DETAILED DESCRIPTION

[0016] The application is further described below in combination with the embodiments, but does not limit the application in any way, and any transformation or replacement based on the teaching of the application belongs to the protection scope of the application.

[0017] The preparation method of the high-cleanliness gas protection alloy welding wire steel wire rod is realized according to the following steps:

[0018] A, hot metal pretreatment desulfurization: the hot metal is transported to the KR hot metal pretreatment device for desulfurization treatment, the hot metal temperature is ≥1350℃, the stirring head insertion depth is controlled to be 2100mm, the conventional CaO desulfurizer is added in an amount of 14.0~16.0kg / t 钢 for desulfurization treatment, and the stirring time is controlled to be 5 minutes; after stirring, the slag is removed to ensure that the hot metal surface in the ladle is exposed ≥4 / 5, and the desulfurization slag is removed completely;

[0019] B, molten steel smelting: the hot metal obtained by pretreatment desulfurization and high-quality scrap steel are respectively added into the LD converter in a ratio of 880kg / t 钢 , 175kg / t 钢 , conventional top and bottom combined blowing is carried out, double-slag method is adopted for converter smelting, the first batch of slag is added according to 10~14kg / t 钢 , 10~12kg / t 钢 before smelting, lime and light-burned dolomite are used for slagging, the second batch of slag is added after the first batch of slag is slagged and the slag is poured out, the second batch of slag is added according to 10~12kg / t 钢 , 8kg / t 钢 , lime and light-burned dolomite are used for slagging again, the C content of the molten steel at the end point is controlled to be 0.03wt%~0.04wt%, and the tapping temperature is ≤1600℃; 1.0~1.5kg / t 钢The slag washing material with the following mass ratio: Al2O3 23.5wt%, SiO2 4.6wt%, CaO 48.5wt%, Al 3.5wt%, MgO 5.4wt%, and the rest Fe and inevitable impurities is added in an amount of 20~25kg / t, and the nitrogen gas flow is controlled to be 20~25NL / min during the whole tapping process;

[0020] C, deoxidation and alloying: the molten steel is tapped after the smelting is completed, when the amount of molten steel in the ladle is greater than 1 / 4, the following deoxidation and alloying sequence is used: ferrosilicon→low-carbon ferromanganese, the following substances are sequentially added into the ladle: ferrosilicon with the following mass ratio: Si 72.2wt%, Al 1.5wt%, P 0.025wt%, S 0.018wt%, and the rest Fe and inevitable impurities, in an amount of 12.1~13.2kg / t 钢 low-carbon ferromanganese with the following mass ratio: Mn 84.5wt%, C 0.3wt%, P 0.024wt%, S 0.015wt%, and the rest Fe and inevitable impurities, in an amount of 15.6~17.0kg / t 钢 The above alloys are added when the amount of molten steel in the ladle reaches 4 / 5;

[0021] D, LF furnace refining of molten steel: after the tapping is completed, the molten steel is hoisted to the LF furnace refining station and connected to the argon gas belt, the argon gas is started with a small argon flow of 20~25NL / min for 3 minutes, then the electrode is lowered with a gear position of 7~9 to slag, and ferrosilicon powder 0.3~0.5kg / t 钢 is added to adjust the slag; after 8 minutes of power-on, the electrode is lifted to observe the slag condition in the furnace, then the temperature is measured and the sample is taken; if the slag condition is relatively thin, lime 4.0~5.0kg / t 钢 is added, then ferrosilicon powder 0.5kg / t 钢 , calcium carbide 0.5kg / t 钢 is added to adjust the slag, and vice versa, the pre-melted refining slag is added to adjust the slag, and the slag basicity is controlled to be 4.0~5.0; according to the steel sample analysis result, the alloy is added to adjust the molten steel composition, to ensure that each chemical composition is within the target range, and the oxygen activity of the molten steel is controlled to be ≤10ppm; the number of electrode lowering during the refining process is controlled to be ≤2 times; then the temperature of the molten steel is heated to 1640~1650℃, and the molten steel is soft-blow argon with a small argon flow of 20~25NL / min, the soft-blow argon time is 10 minutes, then the molten steel covering agent is added, the addition amount is controlled to be 1.0kg / t of steel, and then the molten steel is hoisted to the VD furnace vacuum refining station;

[0022] E. VD furnace vacuum refining: After the molten steel in step D is hoisted to the VD vacuum refining furnace, the argon blowing pipe is connected, and argon is turned on at a small argon flow rate of 20-30 NL / min for 2 minutes. Then the oxygen in the molten steel is determined, and the temperature is measured and sampled. After sampling is completed, the vacuum tank cover vehicle is opened to the working position, the vacuum tank cover is closed, vacuum is drawn, and when the vacuum is drawn to 67 Pa, vacuum degassing treatment is started, and bottom argon blowing treatment is carried out at the same time. The argon flow rate is controlled to be 40-50 NL / min, and the molten steel degassing treatment time is 15 minutes under the condition of a vacuum degree of 67 Pa. After vacuum degassing treatment is completed, the vacuum main valve is closed, the tank cover is lifted, and the molten steel is sampled and the oxygen and hydrogen are determined. Then the molten steel is treated by soft argon blowing at a small argon flow rate, and the argon flow rate is 20-30 NL / min, and the soft argon blowing time is 2 minutes. After the molten steel soft argon blowing is completed, the molten steel is added with a covering agent, and the addition amount is controlled to be 1.0 kg / t 钢 Then the molten steel is hoisted to the casting position;

[0023] F. Molten steel casting: Under the conditions of a tundish temperature of 1540-1550℃, a withdrawal speed of 2.0-2.1 m / min, a secondary cooling water ratio of 1.3-1.5 L / kg, a crystallizer electromagnetic stirring current intensity of 320 A, and a running frequency of 4 Hz, the molten steel obtained in step E is continuously cast into a billet with a section of 165 mm x 165 mm by using a R9m straight arc continuous straightening 7-machine 7-stream small billet caster.

[0024] G. Billet heating: The billet in step F is sent into a heating furnace with a furnace temperature of 1070-1100℃ in the soaking section, and after heating for 50-70 minutes, the billet is discharged, descaled by high-pressure water, and pushed to a high-speed wire rod mill for rolling.

[0025] H. Controlled rolling and controlled cooling: The billet in step G is sent into a high-speed wire rod mill with 30 stands for rolling. Under the rolling conditions of a speed of 0.4 m / s, the billet is coarsely rolled for 6 passes in the rough rolling mill group. Then under the rolling conditions of a speed of 12.0 m / s, the billet is rolled for 5-6 passes in the intermediate rolling mill group. Then under the rolling conditions of a speed of 50.0 m / s, the billet is rolled for 5 passes in the pre-precision rolling mill group. Then under the rolling conditions of a speed of 60 m / s, the billet is rolled for 5-6 passes in the precision rolling mill group. Then under the rolling conditions of a speed of 65 m / s, the billet is rolled for 2 passes in the reducing and sizing mill group. Then under the conditions of a temperature of 895-920℃ and a speed of 70-85 m / s, the billet is drawn. After drawing, the coil is subjected to air mist cooling and air cooling control in a Stelmor air cooling line. The fan and the heat preservation cover are completely closed, and the roller speed is controlled to be 0.15-0.25 m / s. Then the coil is naturally air cooled to room temperature to obtain a high-cleanliness gas shielded alloy welding wire steel coil with a nominal diameter of 6.0-6.5 mm.

[0026] In step A, the chemical composition of the blast furnace molten iron is: C 4.6-4.8wt%, Si 0.30-0.45wt%, Mn 0.20-0.30wt%, P 0.070-0.090wt%, S≤0.030wt%, and the rest is Fe and inevitable impurities.

[0027] In step B, the chemical composition of the molten iron obtained by the pretreatment desulfurization is: C 4.6-4.8wt%, Si 0.30-0.45wt%, Mn 0.20-0.30wt%, P 0.070-0.090wt%, S≤0.005wt%, and the rest is Fe and inevitable impurities.

[0028] The chemical composition of the high-quality scrap steel is: C 0.12-0.25wt%, Si 0.12-0.50wt%, Mn 0.45-1.50wt%, P 0.020-0.038wt%, S 0.015-0.036wt%, and the rest is Fe and inevitable impurities.

[0029] In step G, the tapping temperature is 970-1000℃.

[0030] In step H, the coil temperature after the end of Stelmor air cooling is controlled to be 530-550℃.

[0031] The application also provides a high-cleanliness gas shielded alloy welding wire steel wire rod obtained by the preparation method, which has the following chemical composition by weight percentage: C 0.04-0.06wt%, Si 0.77-0.84wt%, Mn 1.35-1.44wt%, S≤0.008wt%, P≤0.008wt%, N≤0.0020wt%, O≤0.0015wt%, and the rest is Fe and inevitable impurities; the process mechanical properties and the microstructure of the high-cleanliness gas shielded alloy welding wire steel wire rod are shown in Table 1 and Table 2, respectively.

[0032] Table 1 Process mechanical properties of the gas shielded alloy welding wire steel wire rod produced by the application

[0033]

[0034] Table 2 Microstructure and inclusions of the gas shielded alloy welding wire steel wire rod produced by the application

[0035]

[0036] Example 1

[0037] A, hot metal pretreatment desulphurization: the hot metal (chemical composition C 4.6wt%, Si 0.30wt%, Mn 0.20wt%, P 0.070wt%, S 0.017wt%, the rest is Fe and inevitable impurities) is transported to the KR hot metal pretreatment device for desulphurization treatment, the hot metal temperature is 1380℃, the stirring head insertion depth is controlled to be 2100mm, the conventional CaO desulphurizer is added in an amount of 14.0kg / t 钢 , and the stirring time is controlled to be 5 minutes; after the stirring is completed, the slag is removed, the hot metal surface in the ladle is exposed ≥4 / 5, and the desulphurization slag is removed completely; the composition of the pretreated hot metal is controlled to be: C 4.6wt%, Si 0.30wt%, Mn 0.20wt%, P 0.070wt%, S 0.003wt%, and the rest is Fe and inevitable impurities.

[0038] B, molten steel smelting: the hot metal (C 4.6wt%, Si 0.30wt%, Mn 0.20wt%, P 0.070wt%, S 0.003wt%, and the rest is Fe and inevitable impurities) obtained by pretreatment desulphurization, high-quality scrap (chemical composition C 0.12wt%, Si 0.12wt%, Mn 0.45wt%, P 0.020wt%, S 0.015wt%, and the rest is Fe and inevitable impurities) are respectively loaded into the LD converter in an amount of 880kg / t 钢 , 175kg / t 钢 , and conventional top and bottom combined blowing is carried out, the double slag method is used for converter smelting, the first batch of slag is added in an amount of 10kg / t 钢 , 10kg / t 钢 , lime and light-burned dolomite are used for slagging, the second batch of slag is added after the first batch of slag is slagged and the slag is removed, the second batch of slag is added in an amount of 10kg / t 钢 , 8kg / t 钢 , lime and light-burned dolomite are used for slagging again, the C content of the molten steel at the end point is controlled to be 0.03wt%, and the tapping temperature is 1590℃; before tapping, the following mass ratio of slag washing material is added to the ladle in an amount of 1.0kg / t 钢 : Al2O3 23.5wt%, SiO2 4.6wt%, CaO 48.5wt%, Al 3.5wt%, MgO 5.4wt%, and the rest is Fe and inevitable impurities, and the full-process bottom argon blowing process is used during the tapping process, and the argon flow is controlled to be 20NL / min.

[0039] C. Deoxidation and alloying: the molten steel of B step is tapped, when the amount of molten steel in the ladle is greater than 1 / 4, the following deoxidation and alloying sequence is used: ferrosilicon→low-carbon ferromanganese, the following substances are sequentially added to the ladle: ferrosilicon with the following mass ratio: Si 72.2wt%, Al 1.5wt%, P 0.025wt%, S 0.018wt%, and the rest is Fe and inevitable impurities, in an amount of 12.1kg / t 钢 ; low-carbon ferromanganese with the following mass ratio: Mn 84.5wt%, C 0.3wt%, P 0.024wt%, S 0.015wt%, and the rest is Fe and inevitable impurities, in an amount of 15.6kg / t 钢 ; the above alloying is completed when the amount of molten steel in the ladle reaches 4 / 5; after tapping is completed, the molten steel is lifted to the LF furnace refining process.

[0040] D. LF furnace refining of molten steel: the molten steel of C step is lifted to the LF furnace refining station and connected to the argon gas belt, argon blowing is started with a small argon flow (20NL / min) for 3 minutes, then the electrode is lowered with gear 7~9 to slag, 0.3kg / t 钢 ferrosilicon powder is added to adjust the slag; after 8 minutes of power supply, the electrode is lifted to observe the slag condition in the furnace, then the temperature is measured and the sample is taken; if the slag condition is relatively thin, 4.0kg / t 钢 of lime is added, then 0.5kg / t 钢 of ferrosilicon powder, 0.5kg / t 钢 of calcium carbide is added to adjust the slag, otherwise pre-melted refining slag is added to adjust the slag, and the slag basicity is controlled to be 4.0; according to the steel sample analysis results, alloy is added to adjust the composition of the molten steel, to ensure that each chemical composition is within the target range, and the oxygen activity of the molten steel is controlled to be 6ppm; the number of electrode lowering during the refining process is 2 times; then the temperature of the molten steel is heated to 1640℃, and the molten steel is soft-blow argon with a small argon flow of 20NL / min, the soft-blow time is 10 minutes, then the molten steel covering agent is added, the addition amount is controlled to be 1.0kg / t of steel, then the molten steel is lifted to the VD furnace vacuum refining station.

[0041] E. VD furnace vacuum refining: After the molten steel in step D is hoisted to the VD vacuum refining furnace, the argon blowing pipe is connected, argon is turned on with a small argon flow rate (20 NL / min) for 2 minutes, and then the oxygen in the molten steel is determined while the temperature is measured and sampling is performed. After sampling is completed, the vacuum tank cover vehicle is opened to the working position, the vacuum tank cover is closed, vacuum is drawn, and when the vacuum is drawn to 67 Pa, vacuum degassing treatment is started while bottom argon blowing treatment is performed, with an argon flow rate controlled at 40 NL / min. The molten steel degassing treatment time under a vacuum of 67 Pa is 15 minutes. After vacuum degassing treatment is completed, the vacuum main valve is closed, the tank cover is lifted, and the molten steel is sampled and the oxygen and hydrogen are determined. Then the molten steel is subjected to soft argon blowing treatment with a small argon flow rate, with an argon flow rate of 20 NL / min and a soft argon blowing time of 2 minutes. After the molten steel soft argon blowing is completed, the molten steel is added with a covering agent, with an addition amount controlled at 1.0 kg / t 钢 The molten steel is then hoisted to the casting position.

[0042] F. Molten steel casting: Under the conditions of a tundish temperature of 1550°C, a withdrawal speed of 2.0 m / min, a secondary cooling water ratio of 1.3 L / kg, a crystallizer electromagnetic stirring current intensity of 320 A, and a running frequency of 4 Hz, the molten steel obtained in step E is continuously cast into a 165 mm x 165 mm billet by using an R9m straight arc continuous straightening 7-machine 7-stream billet caster.

[0043] G. Billet heating: The billet in step F is sent to a heating furnace with a furnace temperature of 1070°C in the soaking section, heated for 50 minutes, and the billet exit temperature is 970°C. After high-pressure water descaling, the billet is pushed to a high-speed wire rod mill for rolling.

[0044] H, controlled rolling and controlled cooling: the steel billet of step G is sent to a 30-stand high-speed wire rod mill for rolling, under the rolling condition of a speed of 0.4 m / s, 6 passes of rough rolling in a rough rolling mill set; then under the rolling condition of a speed of 12.0 m / s, 5 passes of intermediate rolling in an intermediate rolling mill set; then under the rolling condition of a speed of 50.0 m / s, 5 passes of pre-precision rolling in a pre-precision rolling mill set; then under the rolling condition of a speed of 60 m / s, 5 passes of precision rolling in a precision rolling mill set; then under the rolling condition of a speed of 65 m / s, 2 passes of diameter reduction in a diameter reduction mill set; then under the condition of a temperature of 895 ℃ and a speed of 70 m / s, wire drawing; after wire drawing, the wire rod enters a Stelmor air cooling line for air mist cooling and air cooling control, the fan and the heat preservation cover are all turned off, and the roller speed is controlled to be 0.15-0.20 m / s; after Stelmor air cooling, the coiling temperature is controlled to be 530 ℃, and then the coil is naturally air cooled to room temperature to obtain a high-cleanliness gas shielded alloy welding wire steel wire rod ER70S-6 with a nominal diameter of 6.0 mm, which has the following chemical components by weight percentage: C 0.04wt%, Si 0.77wt%, Mn 1.35wt%, S 0.005wt%, P 0.005wt%, N 0.0013wt%, O 0.0010wt%, and the balance of Fe and inevitable impurities. The process mechanical properties and the microstructure thereof are shown in Table 3 and Table 4, respectively.

[0045] Table 3 Process mechanical properties of the gas shielded alloy welding wire steel wire rod produced in Example 1

[0046]

[0047] Table 4 Microstructure and inclusions of the gas shielded alloy welding wire steel wire rod produced in Example 1

[0048]

[0049] Example 2

[0050] A, hot metal pretreatment desulphurization: the hot metal (chemical components C 4.7wt%, Si 0.38wt%, Mn 0.25wt%, P 0.080wt%, S 0.025wt%, and the balance of Fe and inevitable impurities) is transported to a KR hot metal pretreatment device for desulphurization treatment, the hot metal temperature is 1360 ℃, the stirring head insertion depth is controlled to be 2100 mm, and the desulphurization agent is added at a rate of 15.0 kg / t 钢Add the appropriate amount of conventional CaO desulfurizing agent for desulfurization treatment, and control the stirring time to 5 minutes; after stirring, perform slag removal operation to ensure that the surface of molten iron in the ladle is exposed ≥4 / 5, and remove the desulfurization slag; the composition of the molten iron after pretreatment is controlled as follows: C 4.7wt%, Si 0.38wt%, Mn 0.25wt%, P 0.080wt%, S 0.004wt%, with the remainder being Fe and unavoidable impurities.

[0051] B. Steelmaking: The pre-treated desulfurized molten iron (C 4.7wt%, Si 0.38wt%, Mn 0.25wt%, P 0.080wt%, S 0.004wt%, the remainder being Fe and unavoidable impurities) and high-quality scrap steel (chemical composition C 0.20wt%, Si 0.45wt%, Mn 1.35wt%, P 0.029wt%, S 0.026wt%, the remainder being Fe and unavoidable impurities) are processed at 880 kg / t. 钢 175kg / t 钢 Molten iron and scrap steel are added to the LD converter in a specific ratio for conventional top and bottom combined blowing. The converter smelting adopts the double-slag method. In the early stage of smelting, the first batch of slag is prepared at 12 kg / t. 钢 12kg / t 钢 Lime and lightly calcined dolomite are added for slag formation. After the first batch of slag is formed and the furnace is turned over, the second batch of slag is added at a rate of 12 kg / t. 钢 8kg / t 钢 Lime and lightly calcined dolomite are added to create slag again, controlling the final steel C content to 0.04wt% and the tapping temperature to 1595℃; before tapping, 1.5 kg / t of lime is added to the bottom of the ladle. 钢 The following slag washing materials were added in the specified mass ratio for slag washing: Al2O3 23.5wt%, SiO2 4.6wt%, CaO 48.5wt%, Al 3.5wt%, MgO 5.4wt%, with the remainder being Fe and unavoidable impurities. The tapping process adopted a full bottom blowing nitrogen process, with the nitrogen flow rate controlled at 25NL / min.

[0052] C. Deoxidation and Alloying: After tapping the molten steel from step B, when the ladle contains more than 1 / 4 tonnes of molten steel, deoxidize and alloy it in the following order: ferrosilicon → low-carbon ferromanganese, adding the following substances sequentially at a rate of 12.6 kg / t. 钢 Add the following mass ratio of ferrosilicon: Si 72.2wt%, Al 1.5wt%, P 0.025wt%, S 0.018wt%, with the remainder being Fe and unavoidable impurities; at a rate of 16.3 kg / t. 钢The low-carbon ferromanganese with the following mass ratio: Mn 84.5wt%, C 0.3wt%, P 0.024wt%, S 0.015wt%, and the rest being Fe and inevitable impurities is added in an amount of 0.5kg / t of the steel liquid, and the above alloy is added when the ladle steel liquid reaches 4 / 5.

[0053] D, LF furnace refining of the steel liquid: the steel liquid after the completion of the tapping in the C step is hoisted to the LF furnace refining station and connected to the argon pipe, and the argon is started to be blown with a small argon amount (25NL / min) for 3 minutes, then the electrode is lowered to use gear 7~9 to slag, and ferrosilicon powder 0.4kg / t is added 钢 The slag is adjusted; after the power is on for 8 minutes, the electrode is lifted to observe the slag condition in the furnace, and then the temperature is measured and the sample is taken; if the slag condition is relatively thin, 4.5kg / t of lime is added 钢 Then ferrosilicon powder 0.5 kg / t is added 钢 , calcium carbide 0.5 kg / t 钢 The slag is adjusted, and otherwise the pre-melted refining slag is adjusted; the slag basicity is controlled to be 4.5; according to the steel sample analysis result, the alloy is added to adjust the composition of the steel liquid, to ensure that each chemical composition is within the target range, and the oxygen activity of the steel liquid is controlled to be 8ppm; the electrode is lowered twice during the refining process; then the temperature of the steel liquid is heated to 1645℃, and the steel liquid is soft-blow argon with a small argon amount of 25NL / min, the soft-blow argon time is 10 minutes, then the covering agent is added to the steel liquid, the addition amount is controlled to be 1.0kg / t of steel, and then the steel liquid is hoisted to the VD furnace vacuum refining station.

[0054] E, VD furnace vacuum refining of the steel liquid: after the steel liquid in the D step is hoisted to the VD vacuum refining furnace, the argon pipe is connected, the argon is started to be blown with a small argon amount (25NL / min) for 2 minutes, then the oxygen of the steel liquid is determined, and the temperature is measured and the sample is taken; after the sampling is completed, the vacuum tank cover car is opened to the working position, the vacuum tank cover is closed, and the vacuum is pumped; when the vacuum is pumped to 67Pa, the vacuum degassing treatment is started, and the bottom argon treatment is carried out at the same time, the argon flow is controlled to be 45NL / min, and the steel liquid degassing treatment time is 15 minutes under the condition of vacuum degree 67Pa; after the vacuum degassing treatment is completed, the vacuum main valve is closed, the tank cover is lifted, and the sample and the oxygen and hydrogen of the steel liquid are determined; then the steel liquid is treated by soft-blow argon with a small argon amount, the argon flow is 25NL / min, and the soft-blow argon time is 2 minutes; after the soft-blow argon of the steel liquid is completed, the covering agent is added to the steel liquid, and the addition amount is controlled to be 1.0kg / t 钢 , and then the steel liquid is hoisted to the casting station.

[0055] F. Steel pouring: under the conditions of a tundish temperature of 1545 °C, a withdrawal speed of 2.1 m / min, a secondary cooling water ratio of 1.4 L / kg, a crystallizer electromagnetic stirring current intensity of 320 A, and a running frequency of 4 Hz, the molten steel obtained in the E step was continuously cast into a billet with a section of 165 mm x 165 mm by using a R9m straight arc continuous straightening 7-machine 7-stream billet caster.

[0056] G. Billet heating: the billet of the F step was sent into a heating furnace with a furnace temperature of 1085 °C in the soaking section, and heated for 60 minutes. The billet exit temperature was 990 °C, and then the billet was descaled by high-pressure water and pushed to a high-speed wire rod mill for rolling.

[0057] H. Controlled rolling and controlled cooling: the billet of the G step was sent into a high-speed wire rod mill with 30 stands for rolling. Under the rolling conditions of a speed of 0.4 m / s, the billet was coarsely rolled for 6 passes in the rough rolling mill group. Then, under the rolling conditions of a speed of 12.0 m / s, the billet was rolled for 6 passes in the intermediate rolling mill group. Then, under the rolling conditions of a speed of 50.0 m / s, the billet was rolled for 5 passes in the pre-precision rolling mill group. Then, under the rolling conditions of a speed of 60 m / s, the billet was rolled for 6 passes in the precision rolling mill group. Then, under the rolling conditions of a speed of 65 m / s, the billet was rolled for 2 passes in the reducing and sizing mill group. Then, under the conditions of a temperature of 910 °C and a speed of 80 m / s, the billet was wire-drawing. After wire-drawing, the wire rod was sent to a Stelmor air cooling line for air mist cooling and air cooling control. The fan and the heat preservation cover were all turned off, and the roller speed was controlled to be 0.15-0.25 m / s. After the Stelmor air cooling was completed, the coil temperature was controlled to be 540 °C, and then the coil was naturally air-cooled to room temperature to obtain a high-cleanliness gas shielded alloy welding wire steel wire rod ER70S-6 with a nominal diameter of 6.5 mm, which has the following chemical composition by weight percentage: C 0.05 wt%, Si 0.80 wt%, Mn 1.40 wt%, S 0.007 wt%, P 0.007 wt%, N 0.0017 wt%, O 0.0013 wt%, and the balance of Fe and unavoidable impurities. The process mechanical properties and the microstructure of the gas shielded alloy welding wire steel wire rod produced in Example 2 are shown in Tables 5 and 6, respectively.

[0058] Table 5 Process mechanical properties of the gas shielded alloy welding wire steel wire rod produced in Example 2

[0059]

[0060] Table 6 Microstructure and inclusions of the gas shielded alloy welding wire steel wire rod produced in Example 2

[0061]

[0062] Example 3

[0063] A, hot metal pretreatment desulphurization: the hot metal (chemical composition C 4.8wt%, Si 0.45wt%, Mn 0.30wt%, P 0.090wt%, S 0.030wt%, the rest is Fe and inevitable impurities) is transported to the KR hot metal pretreatment device for desulphurization treatment, the hot metal temperature is 1350℃, the stirring head insertion depth is controlled to be 2100mm, the conventional CaO desulphurizer is added in an amount of 16.0kg / t 钢 , and the stirring time is controlled to be 5 minutes; after the stirring is completed, the slag is removed, the hot metal surface in the ladle is exposed ≥4 / 5, and the desulphurization slag is removed completely; the composition of the pretreated hot metal is controlled to be: C 4.8wt%, Si 0.45wt%, Mn 0.30wt%, P 0.090wt%, S 0.005wt%, and the rest is Fe and inevitable impurities.

[0064] B, molten steel smelting: the hot metal (C 4.8wt%, Si 0.45wt%, Mn 0.30wt%, P 0.090wt%, S 0.005wt%, and the rest is Fe and inevitable impurities) obtained by pretreatment desulphurization, high-quality scrap (chemical composition C 0.25wt%, Si 0.50wt%, Mn 1.50wt%, P 0.038wt%, S 0.036wt%, and the rest is Fe and inevitable impurities) are respectively loaded into the LD converter in an amount of 880kg / t 钢 , 175kg / t 钢 of hot metal and scrap, and conventional top and bottom combined blowing is carried out; the double slag method is used for converter smelting, the first batch of slag is added in an amount of 14kg / t 钢 , 12kg / t 钢 of lime and light-burned dolomite for slagging, the second batch of slag is added after the first batch of slag is slagged and the slag is removed, the second batch of slag is added in an amount of 12kg / t 钢 , 8kg / t 钢 of lime and light-burned dolomite for slagging again, the C content of the molten steel at the end point is controlled to be 0.04wt%, and the tapping temperature is 1600℃; before tapping, the following mass ratio of slag washing material is added to the ladle bottom in an amount of 1.5kg / t 钢 : Al2O3 23.5wt%, SiO2 4.6wt%, CaO 48.5wt%, Al 3.5wt%, MgO 5.4wt%, and the rest is Fe and inevitable impurities, and the full-process bottom blowing nitrogen process is used during the tapping process, and the nitrogen flow is controlled to be 25NL / min.

[0065] C. Deoxidation and alloying: the molten steel of B step is tapped, when the amount of molten steel in the ladle is greater than 1 / 4, the following deoxidation and alloying sequence is used: ferrosilicon→low-carbon ferromanganese, the following substances are sequentially added to the ladle: ferrosilicon with the following mass ratio: Si 72.2wt%, Al 1.5wt%, P 0.025wt%, S 0.018wt%, and the rest is Fe and unavoidable impurities, in an amount of 13.2kg / t 钢 ; low-carbon ferromanganese with the following mass ratio: Mn 84.5wt%, C 0.3wt%, P 0.024wt%, S 0.015wt%, and the rest is Fe and unavoidable impurities, in an amount of 17.0kg / t 钢 ; the above alloying is completed when the amount of molten steel in the ladle reaches 4 / 5; after tapping is completed, the molten steel is hoisted to the LF furnace refining process.

[0066] D. LF furnace refining of molten steel: the molten steel of C step is hoisted to the LF furnace refining station and connected to the argon gas belt, argon gas is started with a small argon flow (25NL / min) for 3 minutes, then the electrode is lowered with gear 7~9 to slag, 0.5kg / t 钢 ferrosilicon powder is added for slag adjustment; after 8 minutes of power supply, the electrode is lifted to observe the slag condition in the furnace, then the temperature is measured and the sample is taken; if the slag condition is relatively thin, 5.0kg / t 钢 of lime is added, then 0.5kg / t 钢 of ferrosilicon powder, 0.5kg / t 钢 of calcium carbide is added for slag adjustment, otherwise pre-melted refining slag is added for slag adjustment, and the slag basicity is controlled to be 5.0; according to the steel sample analysis results, alloy is added to adjust the composition of the molten steel, to ensure that each chemical composition is within the target range, and the oxygen activity of the molten steel is controlled to be 10ppm; the number of electrode lowering during the refining process is 2 times; then the temperature of the molten steel is heated to 1650℃, and the molten steel is soft-blow argon with a small argon flow of 25NL / min, the soft-blow time is 10 minutes, then the molten steel covering agent is added, the addition amount is controlled to be 1.0kg / t of steel, then the molten steel is hoisted to the VD furnace vacuum refining station.

[0067] E. VD furnace vacuum refining: After the molten steel in step D is hoisted to the VD vacuum refining furnace, the argon blowing pipe is connected, argon is turned on with a small argon flow rate (30 NL / min) for 2 minutes, and then the oxygen in the molten steel is determined while the temperature is measured and sampling is performed. After sampling is completed, the vacuum tank cover vehicle is opened to the working position, the vacuum tank cover is closed, vacuum is drawn, and when the vacuum is drawn to 67 Pa, vacuum degassing treatment is started while bottom argon blowing treatment is performed, with an argon flow rate controlled at 50 NL / min. The molten steel degassing treatment time under a vacuum of 67 Pa is 15 minutes. After vacuum degassing treatment is completed, the vacuum main valve is closed, the tank cover is lifted, and the molten steel is sampled and the oxygen and hydrogen are determined. Then the molten steel is treated with soft argon blowing with a small argon flow rate, with an argon flow rate of 30 NL / min and a soft argon blowing time of 2 minutes. After the molten steel soft argon blowing is completed, the molten steel is added with a covering agent, with an addition amount controlled at 1.0 kg / t 钢 The molten steel is then hoisted to the casting position.

[0068] F. Molten steel casting: Under the conditions of a tundish temperature of 1540°C, a withdrawal speed of 2.1 m / min, a secondary cooling water ratio of 1.5 L / kg, a crystallizer electromagnetic stirring current intensity of 320 A, and a running frequency of 4 Hz, the molten steel obtained in step E is continuously cast into a 165 mm x 165 mm billet by using an R9m straight arc continuous straightening 7-machine 7-stream billet caster.

[0069] G. Billet heating: The billet in step F is sent to a heating furnace with a furnace temperature of 1100°C in the soaking section, heated for 70 minutes, and the billet exit temperature is 1000°C. After high-pressure water descaling, the billet is pushed to a high-speed wire rod mill for rolling.

[0070] H, controlled rolling and controlled cooling: the steel billet of step G is sent to a high speed wire rod mill with 30 stands for rolling, under the rolling condition of speed 0.4 m / s, the steel billet is coarsely rolled for 6 passes in the rough rolling mill group; then under the rolling condition of speed 12.0 m / s, the steel billet is rolled for 6 passes in the intermediate rolling mill group; then under the rolling condition of speed 50.0 m / s, the steel billet is rolled for 5 passes in the pre-precision rolling mill group; then under the rolling condition of speed 60 m / s, the steel billet is rolled for 6 passes in the precision rolling mill group; then under the rolling condition of speed 65 m / s, the steel billet is rolled for 2 passes in the reducing and sizing mill group; then under the condition of temperature 920℃ and speed 85 m / s, the steel billet is drawn; after drawing, the wire rod enters the Stelmor air cooling line for air mist cooling and air cooling control, the fan and the heat preservation cover are all turned off, the roller speed is controlled to be 0.15~0.25 m / s; after the Stelmor air cooling is finished, the coiling temperature is controlled to be 550℃, then the coil is naturally air cooled to room temperature, and a high-cleanliness gas shielded alloy welding wire steel wire rod ER70S-6 with nominal diameter 6.0 mm is obtained, which has the following chemical components by weight percentage: C 0.06wt%, Si 0.84wt%, Mn 1.44wt%, S 0.008wt%, P 0.008wt%, N 0.0020wt%, O 0.0015wt%, and the rest is Fe and inevitable impurities. The process mechanical properties and the microstructure are shown in Table 7 and Table 8 respectively.

[0071] Table 7 Process mechanical properties of the gas shielded alloy welding wire steel wire rod produced in Example 3

[0072]

[0073] Table 8 Microstructure and inclusions of the gas shielded alloy welding wire steel wire rod produced in Example 3

[0074]

Claims

1. A method of producing a high cleanliness gas shielded alloy welding wire rod, characterized by, The following steps are implemented: A, hot metal pretreatment desulphurization: the hot metal from blast furnace is transported to KR hot metal pretreatment device for desulphurization treatment, the hot metal temperature is ≥1350℃, the insertion depth of stirring head is controlled to be 2100mm, the conventional CaO desulfurizer is added in an amount of 14.0~16.0kg / t 钢 , the stirring time is controlled to be 5 minutes; after stirring, the slag after scraping operation is performed, the hot metal surface in the ladle is ensured to be exposed ≥4 / 5, and the desulfurization slag is scraped clean; B, molten steel smelting: the pretreatment desulfurization of molten iron, high-quality scrap steel respectively according to 880kg / t 钢 , 175kg / t 钢 Into the LD converter, the conventional top and bottom blowing, converter smelting using double slag smelting, smelting early first batch of slag material respectively according to 10~14kg / t 钢 , 10~12kg / t 钢 Add lime, light calcined dolomite slag, first batch of slag material after slagging end pouring pouring slag, the second batch of slag material respectively according to 10~12kg / t 钢 , 8kg / t 钢 Add lime, light calcined dolomite again slagging, control the end of molten steel C content 0.03wt%~0.04wt%, tapping temperature ≤1600℃; Before tapping to the ladle bottom according to 1.0~1.5kg / t 钢 The following mass ratio of slag washing material for slag washing: Al2O3 23.5wt%, SiO24.6wt%, CaO 48.5wt%, Al3.5wt%, MgO 5.4wt%, the rest is Fe and inevitable impurities, the whole process of tapping process using bottom blowing nitrogen process, nitrogen flow control for 20~25NL / min; C. Alloying and deoxidation: after the smelting of the molten steel, when the amount of molten steel in the ladle is greater than 1 / 4, the following alloying and deoxidation sequence is used: ferrosilicon→low-carbon ferromanganese, and the following substances are sequentially added to the ladle: ferrosilicon with a mass ratio of Si 72.2wt%, Al 1.5wt%, P 0.025wt%, S 0.018wt%, and the rest being Fe and unavoidable impurities, is added in an amount of 12.1-13.2kg / t 钢 low-carbon ferromanganese with a mass ratio of Mn 84.5wt%, C 0.3wt%, P 0.024wt%, S 0.015wt%, and the rest being Fe and unavoidable impurities, is added in an amount of 15.6-17.0kg / t 钢 the above alloying is completed when the amount of molten steel in the ladle reaches 4 / 5. D, LF furnace refining of molten steel: after tapping, the molten steel is hoisted to the LF furnace refining station and connected to the argon belt, argon is started at a small argon flow of 20-25 NL / min for 3 minutes, then the electrode is lowered at gear 7-9 to slag, 0.3-0.5 kg / t of ferrosilicon powder is added 钢 Slag adjustment; after 8 minutes of power-on, the electrode is lifted to observe the slag condition in the furnace, then the temperature is measured and the sample is taken; if the slag condition is relatively thin, 4.0-5.0 kg / t of lime is added 钢 Then 0.5 kg / t of ferrosilicon powder is added 钢 , 0.5 kg / t of calcium carbide is added 钢 Slag adjustment, otherwise pre-melted refining slag is added for slag adjustment, and the slag basicity is controlled to be 4.0-5.0; according to the steel sample analysis results, alloy is added to adjust the composition of the molten steel, to ensure that each chemical component is within the target range, and the oxygen activity of the molten steel is controlled to be ≤10 ppm; the number of times of lowering the electrode during the refining process is controlled to be ≤2 times; then the temperature of the molten steel is heated to 1640-1650℃, and the molten steel is soft-blow argon with a small argon flow of 20-25 NL / min, the soft-blow argon time is 10 minutes, then the molten steel covering agent is added, the addition amount is controlled to be 1.0 kg / t of steel, then the molten steel is hoisted to the VD furnace vacuum refining station; E, VD furnace vacuum refining of liquid steel: after the liquid steel of step D is hoisted to the VD vacuum refining furnace, the argon blowing pipe is connected, the argon is turned on, and a small argon amount of 20-30 NL / min is blown for 2 minutes, after which the oxygen of the liquid steel is determined, and the temperature is measured and sampled; after sampling is completed, the vacuum tank cover vehicle is opened to the working position, the vacuum tank cover is closed, vacuum is drawn, and when the vacuum is drawn to 67 Pa, vacuum degassing treatment is started, and bottom argon blowing treatment is carried out at the same time, the argon flow is controlled to be 40-50 NL / min, and the liquid steel degassing treatment time is 15 minutes under the condition of a vacuum degree of 67 Pa; after vacuum degassing treatment is completed, the vacuum main valve is closed, the tank cover is lifted, the liquid steel is sampled and the oxygen and hydrogen are determined; then a small argon amount of soft argon blowing treatment is carried out on the liquid steel, the argon flow is 20-30 NL / min, and the soft argon blowing time is 2 minutes; after the liquid steel soft argon blowing is completed, the liquid steel covering agent is added, and the addition amount is controlled to be 1.0 kg / t 钢 and then the liquid steel is hoisted to the casting position; F, molten steel casting: under the conditions of a tundish temperature of 1540-1550℃, a withdrawal speed of 2.0-2.1 m / min, a secondary cooling water ratio of 1.3-1.5 L / kg, a crystallizer electromagnetic stirring current intensity of 320 A, and a running frequency of 4 Hz, the molten steel obtained in step E is continuously cast into a billet with a section of 165 mm x 165 mm by using a R9m straight arc continuous straightening 7-machine 7-stream billet caster; G, billet heating: the billet in step F is sent into a heating furnace with a furnace temperature of 1070-1100℃ in the soaking section, and after heating for 50-70 minutes, the billet is discharged, descaled by high-pressure water, and pushed to a high-speed wire rod mill for rolling; H, controlled rolling and controlled cooling: the billet in step G is sent into a high-speed wire rod mill with 30 stands for rolling, under the rolling conditions of a speed of 0.4 m / s, 6 passes in the rough rolling mill group; then under the rolling conditions of a speed of 12.0 m / s, 5-6 passes in the intermediate rolling mill group; then under the rolling conditions of a speed of 50.0 m / s, 5 passes in the pre-precision rolling mill group; then under the rolling conditions of a speed of 60 m / s, 5-6 passes in the precision rolling mill group; and then under the rolling conditions of a speed of 65 m / s, 2 passes in the reducing and sizing mill group; then wire drawing at a temperature of 895-920℃ and a speed of 70-85 m / s; after wire drawing, the coil is subjected to air mist cooling and air cooling control in a Stelmor air cooling line, the fan and the heat preservation cover are fully closed, and the roller speed is controlled at 0.15-0.25 m / s; then the coil is naturally air cooled to room temperature to obtain a high-cleanliness gas shielded alloy welding wire steel coil with a nominal diameter of 6.0-6.5 mm, which has the following chemical composition by weight percentage: C 0.04-0.06wt%, Si 0.77-0.84wt%, Mn 1.35-1.44wt%, S≤0.008wt%, P≤0.008wt%, N≤0.0020wt%, O≤0.0015wt%, and the balance of Fe and unavoidable impurities; the microstructure of the high-cleanliness gas shielded alloy welding wire steel coil has equiaxed ferrite 92-94% + pearlite 6-8%, the ferrite grain size is 10.5-11.0 grade, the tensile strength Rm is 460-480 MPa, the reduction of area Z is ≥86.0%, the Φ1.0 mm-Φ1.2 mm welding wire does not break during drawing, the breakage rate of the Φ0.8 mm welding wire is ≤0.02 times / ton, and the breakage rate of the Φ0.4 mm-Φ0.6 mm welding wire is ≤0.04 times / ton.

2. The method of producing high cleanliness gas shielded alloy welding wire rod as claimed in claim 1, wherein, In step A, the chemical composition of the blast furnace molten iron is: C 4.6-4.8wt%, Si 0.30-0.45wt%, Mn 0.20-0.30wt%, P 0.070-0.090wt%, S≤0.030wt%, and the balance of Fe and unavoidable impurities.

3. The method of producing high cleanliness gas shielded alloy welding wire rod as claimed in claim 1, wherein, The chemical composition of the molten iron obtained by the pretreatment desulfurization in step B is: C 4.6~4.8wt%, Si 0.30~0.45wt%, Mn 0.20~0.30wt%, P 0.070~0.090wt%, S≤0.005wt%, and the rest is Fe and inevitable impurities; The chemical composition of the high-quality scrap steel is: C 0.12~0.25wt%, Si 0.12~0.50wt%, Mn 0.45~1.50wt%, P 0.020~0.038wt%, S 0.015~0.036wt%, and the rest is Fe and inevitable impurities.

4. The method of claim 1 wherein the wire rod is produced by the steps of: In step G, the tapping temperature is 970~1000℃.

5. The method of claim 1 wherein the wire rod is produced by the steps of: In step H, the coiling temperature after the Stelmor air cooling is controlled to be 530~550℃. ​ 6. A high cleanliness gas shielded alloy welding wire rod prepared by the method of any one of claims 1 to 5, characterized in that, The high-cleanliness gas shielded alloy welding wire steel wire rod has the following chemical composition in weight percentage: C 0.04~0.06wt%, Si 0.77~0.84wt%, Mn 1.35~1.44wt%, S≤0.008wt%, P≤0.008wt%, N≤0.0020wt%, O≤0.0015wt%, and the rest is Fe and inevitable impurities; the ferrite grain size of the high-cleanliness gas shielded alloy welding wire steel wire rod is 10.5~11.0 grade, the tensile strength Rm is 460~480MPa, the reduction of area Z is≥86.0%, the wire breaking rate of drawing Φ0.8mm welding wire is≤0.02 times / ton, and the wire breaking rate of drawing Φ0.4mm~Φ0.6mm welding wire is≤0.04 times / ton.

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