A production method for stabilizing the performance of high-speed drawn welding wire ER70S-6

Abstract

The application discloses a production method for stabilizing the performance of high-speed drawing welding wire ER70S-6, which comprises the following steps: 1) adopting intermediate ladle electromagnetic induction heating technology, the intermediate ladle electromagnetic induction heating is in a symmetrical double-channel mode, and the overheating degree of the intermediate ladle is controlled within 30 DEG C plus or minus 5 DEG C; 2) adopting constant drawing speed operation, the drawing speed control range is 1.5-1.8 m / min; 3) the temperature entering the reducing sizing mill is controlled within 780 DEG C-820 DEG C, so as to ensure the uniformity of product size and bar; and 4) the wire discharge temperature is controlled within 750-780 DEG C, meanwhile, the cooling speed of the air cooling line is controlled to be less than or equal to 1.0 DEG C / s, so that the tensile strength of the coil is controlled to be less than or equal to 530 MPa, and the average value of the area reduction is increased by more than 70%. The application makes the performance of the ER70S-6 welding wire adapt to high-speed drawing production, high-quality welding wire steel produced by the application can obtain excellent structure and performance, and the drawing and welding performance of the welding wire steel ER70S-6 is improved.

Description

Technical Field

[0001] This invention relates to the fields of metallurgy and rolling technology, and in particular to a production method for stabilizing the performance of high-speed drawing welding wire ER70S-6. Background Technology

[0002] my country consumes over 50% of the world's welding materials, making it a major producer and consumer. Currently, the welding materials with the highest production and consumption volumes mainly include three categories: gas-shielded welding wire steel, submerged arc welding wire steel, and welding electrode steel. Among these, ER70S-6 gas-shielded welding wire steel is the main product. ER70S-6 refers to steel wire used for CO2 gas-shielded manual welding, submerged arc welding, semi-continuous welding, and automatic welding. It is widely used in pressure vessels, power, automotive, and various machinery manufacturing industries. It is also widely applied in steel structures, automotive, home appliances, power, bridges, and machinery manufacturing industries, with strong market demand. Our factory's ER70S-6 welding wire product has always been a flagship product, but for a long time, we haven't undertaken any product upgrades or development efforts. Since last year, downstream users who have long used our ER70S-6 welding wire products have been upgrading their products. As our long-term customers have begun to upgrade and transform their equipment, many workshops have been converted to high-speed, full-process continuous drawing equipment production lines. In the future, they will all use ER70S-6 wire rod raw materials with a diameter of φ6.5mm, and φ5.5mm welding wire rods will gradually be phased out.

[0003] To adapt to the advanced high-speed continuous drawing welding wire production lines continuously improved by downstream users, and to meet their increasingly stringent quality requirements, a targeted effort was made to improve the performance stability of the high-speed drawn φ6.5mm welding wire ER70S-6. To ensure its excellent drawing performance, a production method for stabilizing the performance of the high-speed drawn welding wire ER70S-6 must be developed, achieving a tensile strength ≤530MPa, a 30% reduction in wire breakage rate, and a microstructure consisting of ferrite + pearlite + a small amount of bainite. Summary of the Invention

[0004] The purpose of this invention is to provide a production method for stabilizing the performance of high-speed drawn welding wire ER70S-6, enabling the ER70S-6 welding wire to adapt to high-speed drawing production. This method maintains tensile strength within a certain range while producing a microstructure of ferrite + pearlite with minimal bainite, and ensuring the product has no dimensional or appearance defects. The resulting high-quality welding wire steel achieves excellent microstructure and properties, improving the drawing and welding performance of ER70S-6 welding wire steel.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses a production method for stabilizing the performance of high-speed drawn welding wire ER70S-6. The main production steps include: molten iron pretreatment → 100-ton top-and-bottom blowing converter → LF furnace refining → continuous casting billet → acceptance and loading → billet heating → high-pressure water descaling → roughing mill rolling → intermediate mill rolling → pre-finishing mill rolling → finishing mill rolling → reducing and sizing mill rolling → controlled water cooling → diameter gauge → wire drawing machine → Steyrmo roller cooling → coiling → trimming and surface quality inspection → packaging → weighing → tagging → warehousing; specifically:

[0007] 1) Tracking the steelmaking process revealed that the superheat fluctuation range was large, which directly affected the quality of the cast billet. The improvement method was to adopt tundish electromagnetic induction heating technology. The tundish electromagnetic induction heating is a symmetrical dual-channel method. The process parameters should be set as follows: the working voltage of the intermediate electromagnetic induction coil is 1500-2200V, the working frequency is 50-55HZ, the output power is 600-900KW, and the tundish superheat is controlled at 30℃±5℃.

[0008] 2) Occasionally, hollow products may occur during the downstream drawing process. The preliminary cause is determined to be voids in the cast billet due to inconsistent drawing speed. In order to reduce the fluctuation of drawing speed, constant drawing speed operation should be adopted, and the drawing speed control range should be 1.5-1.8m / min.

[0009] 3) Through downstream production tracking, it was found that many product drawing fractures occurred at the head and tail of the base material coil. The cause was found to be that the dimensions of the head and tail of the base material product fluctuated significantly compared with other parts. The solution is to add a sizing mill rolling process and control the temperature of the sizing mill at 780℃-820℃ to ensure the uniformity of product dimensions.

[0010] 4) The spinning temperature is controlled at 750-780℃, and the cooling rate of the air-cooling line is controlled at ≤1.0℃ / s, so that the tensile strength of the wire rod is controlled at ≤530MPa, and the average section shrinkage rate is increased from 70% to more than 75%.

[0011] Furthermore, the chemical composition of the ER70S-6 welding wire by mass percentage is as follows: C: 0.06-0.09%; Si: 0.80-0.95%; Mn: 1.40-1.80%; P≤0.030%; S: ≤0.030%; with the balance being Fe and trace amounts of impurity elements.

[0012] Furthermore, the pulling speed for constant pulling speed operation is controlled at 1.8 m / min.

[0013] Furthermore, the superheat of the tundish is controlled at 26℃, 30℃, 32℃ or 35℃.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0015] A production method for stabilizing the performance of high-speed drawn welding wire ER70S-6 has been developed. While stabilizing tensile strength and reduction of area, the rolling process is adjusted to obtain a microstructure of ferrite + pearlite with minimal bainite. The rolling equipment is also adjusted to improve product dimensional accuracy and eliminate surface quality defects.

[0016] This allows the tensile strength of the wire rod to be controlled at ≤530MPa, and the average reduction of area to be increased by more than 75% from 70%. Detailed Implementation

[0017] The present invention will be further described below with reference to specific embodiments.

[0018] 1) Fluctuation range of superheat control before and after ER70S-6 welding wire steel

[0019] Table 1

[0020]

[0021]

[0022] The real-time nature of technical solution 1) not only limits the superheat range to the specified range, but also effectively reduces the superheat, which greatly ensures the quality of the continuously cast billet.

[0023] 2) Constant speed control

[0024] Table 2

[0025] Example 1 2.1 Example 6 1.8 Example 2 1.5 Example 7 1.8 Example 3 1.7 Example 8 1.8 Example 4 1.7 Example 9 1.8 Example 5 1.5 Example 0 1.8

[0026] The improved continuous casting billet casting speed is stably controlled, which basically eliminates the phenomenon of hollow continuous casting billets, and at the same time prevents the porosity caused by excessive gas content, especially oxygen content, during the continuous casting process.

[0027] 3) Improvement of product dimensional consistency

[0028] Table 3

[0029]

[0030]

[0031] After using a reducing sizing mill, the dimensional accuracy of the products was significantly improved, with the C-grade accuracy reaching over 80%.

[0032] 4) Improved stability of product mechanical properties

[0033] Table 4

[0034]

[0035] After adjustments, the tensile strength of the product stabilized at around 500 MPa, and the area reduction ratio also improved. Specific example data obtained through these measures demonstrate that the performance of the ER70S-6 welding wire has been stabilized.

[0036] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A production method for stabilizing the performance of high-speed drawing welding wire ER70S-6, the main production steps of which include: Hot metal pretreatment → 100-ton top and bottom blowing converter → LF furnace refining → continuous casting billet → acceptance and loading → billet heating → high-pressure water descaling → roughing mill rolling → intermediate mill rolling → pre-finishing mill rolling → finishing mill rolling → reducing and sizing mill rolling → controlled water cooling → diameter gauge → wire drawing machine → Steyrmo roller cooling → coiling → trimming and surface quality inspection → packaging → weighing → tagging → warehousing; Its features are: 1) Tracking the steelmaking process revealed that the superheat fluctuation range was large, directly affecting the quality of the cast billet. The improvement method was to adopt tundish electromagnetic induction heating technology. The tundish electromagnetic induction heating is a symmetrical dual-channel method. The process parameters should be set as follows: the working voltage of the intermediate electromagnetic induction coil is 1500-2200V, the working frequency is 50-55HZ, the output power is 600-900KW, and the tundish superheat is controlled at 30℃±5℃. 2) Occasionally, hollow products may occur during the downstream drawing process. The preliminary cause is determined to be voids in the cast billet due to inconsistent drawing speed. In order to reduce the fluctuation of drawing speed, constant drawing speed operation should be adopted, and the drawing speed control range should be 1.5-1.8m / min. 3) Through downstream production tracking, it was found that many product drawing fractures occurred at the head and tail of the base material coil. The cause was found to be that the dimensions of the head and tail of the base material product fluctuated significantly compared with other parts. The solution is to add a sizing mill rolling process and control the temperature of the sizing mill to 780℃-820℃ to ensure the uniformity of product dimensions. 4) The spinning temperature is controlled at 750~780℃, and the cooling rate of the air-cooling line is controlled at ≤1.0℃ / s, so that the tensile strength of the wire rod is controlled at ≤530MPa, and the average section shrinkage rate is increased from 70% to more than 75%. The chemical composition of the ER70S-6 welding wire by mass percentage is as follows: C: 0.06-0.09%; Si: 0.80-0.95%; Mn: 1.40-1.80%; P≤0.030%; S: ≤0.030%; the balance is Fe and a small amount of impurity elements.

2. The production method for stabilizing the performance of high-speed drawing welding wire ER70S-6 according to claim 1, characterized in that: The pulling speed for constant pulling speed operation is controlled at 1.8 m / min.

3. The production method for stabilizing the performance of high-speed drawing welding wire ER70S-6 according to claim 1, characterized in that: The superheat of the tundish is controlled at 26℃, 30℃, 32℃ or 35℃.

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