Production method of 6.5 mm specification ER70S-6 wire rod

Abstract

The invention relates to the technical field of ferrous metallurgy, and particularly discloses a 6.5 mm specification ER70S-6 wire rod production method which comprises the following steps that S1, a continuous casting square billet is evenly heated through a three-section walking beam furnace; s2, after being discharged from the furnace, the steel billet is subjected to rough rolling, intermediate rolling and pre-finish rolling to control the material type and the sectional area, and then is cooled through two water tanks; s3, cooling the rolled piece again after the rolled piece passes through a finishing mill group, enabling the rolled piece to pass through three water tanks, controlling the temperature of the rolled piece to 920 + / -10 DEG C, entering a double-module unit, enabling the rolled piece to pass through two rolling mills, finally achieving the required product size, and controlling the final spinning temperature; s4, the rolled piece passes through a silking machine to produce a wire rod finished product, flying shear equipment is installed in front of the silking machine, and slow cooling and heat preservation are conducted through a Stelmor air cooling line after silking; the production cost is reduced, the surface defect rate is reduced, energy consumption is reduced, and the steel yield is increased.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of steel metallurgy, in particular to a production method of 6.5mm-specification ER70S-6 coil. BACKGROUND

[0002] The high-speed wire rod ER70S-6 industrial wire rod coil is a steel grade produced according to the national standard GB / T3429-2015 (AWS A5.18-2005) and GB / 14981-2009, is a low-alloy steel welding wire widely used in gas shielded welding (MIG / MAG), and has a wide market prospect.

[0003] High Si (0.8-1.15%) in the ER70S-6 billet easily intensifies surface oxidation, generates a relatively thick iron oxide skin, enhances the adhesion of the rolling material surface, easily sticks to the roller to form roller marks or scratches, and increases the wire breaking rate during drawing; Mn (1.4-1.85%) causes the heat conductivity of the billet to be slightly low, the core-surface temperature difference is prone to occurring during heating, high Mn increases the deformation resistance, a higher rolling temperature is needed, but Si easily accelerates grain coarsening, and the temperature is prone to causing work hardening when being too low or causing grain coarsening when being too high, thereby reducing the toughness of the welding wire. Therefore, it is urgent to design a production method of the 6.5mm-specification high-speed wire rod coil ER70S-6 steel grade to solve the problems of high surface defect rate, high rolling energy consumption and high production cost in the production of the existing ER70S-6 steel grade. SUMMARY

[0004] In view of the problems in the prior art, the purpose of the application is to provide a production method of the 6.5mm-specification high-speed wire rod coil ER70S-6 steel grade.

[0005] The technical scheme adopted by the application to solve the technical problems is as follows: a production method of 6.5mm-specification ER70S-6 coil, comprising the following steps:

[0006] S1, continuously cast billets are uniformly heated through a three-section step-by-step heating furnace;

[0007] S2, after the billets are discharged, the billets are controlled in shape and cross-sectional area through rough rolling, intermediate rolling and pre-precision rolling, and then are cooled through two water tanks;

[0008] S3, the rolled piece is cooled again after passing through a precision rolling mill group, passes through three water tanks, the rolled piece temperature is controlled to 920±10 DEG C, enters a double-module mill group, passes through two rolling mills, finally reaches the required product size, and the final wire drawing temperature is controlled;

[0009] S4, the rolled piece is produced into a coil finished product through a wire drawing machine, a flying shear device is installed in front of the wire drawing machine, and the wire drawing machine is subjected to slow cooling and heat preservation through a Stelmor air cooling line after wire drawing.

[0010] Specific is, the size of the continuous casting billet in the step S1 is 165*165*12000mm.

[0011] Specific is, the steel billet chemical composition of the continuous casting billet is as follows: C: 0.070-0.080%; Si: 0.82-0.88%, Mn: 1.40-1.49%, S, P impurity elements ≤0.015%, Cr: 0.02-0.04%, Ni: 0.012-0.018%, Cu: 0.012-0.018%, Mo: 0.002%, V: 0.003%, and the rest is iron and inevitable impurities.

[0012] Specific is, the three-section step-by-step heating furnace in the step S1 adopts intelligent combustion control technology, and different temperature range standards are set according to different steel grades and production specifications.

[0013] Specific is, when the three-section step-by-step heating furnace produces 6.5mm specification ER70S6-steel grade with billet, a step-by-step heating system is adopted, the temperature is slowly increased to reduce Si oxidation, the temperature of the second section is controlled at 830±20℃, the temperature of the first section is controlled at 1040±20℃, and the temperature of the soaking section is controlled at 1110±20℃, and when the billet is produced, the temperature of each section is increased to different degrees, the opening rolling temperature is controlled at 1010℃, the automatic combustion technology is adopted, and the temperature difference of the billet is controlled within 10℃.

[0014] Specific is, the high-pressure water descaling system is arranged before the billet enters the rough rolling mill set after being discharged in the step S2, the water pressure of the high-pressure water descaling system is ≥20MPa, and the iron oxide scale removal rate is ensured to be >99.5%.

[0015] Specific is, the rough rolling, medium rolling and pre-precision rolling area mill set in the step S2 uses 14 flat-stand alternating type rolling mills and two DanieI precision rolling mills, and a plurality of passes, small reduction rate and large reduction amount are adopted to control the material shape to be a circle with a diameter of 19.5mm and a cross-sectional area of 315-316mm 2 ; then the rolling piece is cooled through two water tanks, the water supply pressure of the water tank is controlled to be above 14Bar to pass through water, the cooling rate of the rolling piece is controlled, and after the rolling piece passes through a 3# flying shear cutter, the rolling piece enters the DanieI precision rolling mill set, at this time, the temperature is controlled to be 930±10℃, the precision rolling mill set uses one-drag-two 45° top cross precision rolling mill, a total of eight rolling mills, and the outlet out-of-roundness is controlled to be within 0.3mm and the cross-sectional area is controlled to be 53-54mm 2 .

[0016] Specific is, the three water tanks in the step S3 are uniformly cooled in sections, and the wire laying temperature is finally controlled to be 840±10℃.

[0017] Specifically, the flying shear device in the step S4 adopts a Danelly high-speed flying shear device to automatically shear the steel material with the head and tail size exceeding the standard and the mechanical property exceeding the standard.

[0018] The present application has the following advantages:

[0019] The 6.5mm specification ER70S-6 coil production method designed in the present application enhances the plasticity and strength of the finished steel material by controlling the heating temperature, rolling temperature, deformation, and segmented cooling, adjusts the alloying elements to reduce the production cost, reduce the surface defect rate, reduce the energy consumption, and improve the steel material yield. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be further described clearly and completely. Based on the embodiments in the present application, all the other embodiments obtained by the person skilled in the art without creative labor are within the protection scope of the present application.

[0021] The present application aims to provide a 6.5 specification high-speed wire coil ER70S-6 steel production method, which enhances the plasticity and strength of the finished steel material by controlling the heating temperature, rolling temperature, deformation, and segmented cooling, adjusts the alloying elements to reduce the production cost. The 165*165*12000mm continuous casting billet is uniformly heated by the three-stage step-by-step heating furnace, the coil finished product is produced after the billet is discharged and is subjected to rough rolling, intermediate rolling, pre-precision rolling, precision rolling, module, and wire feeding, and the water cooling is arranged before and after the precision rolling and after the module to adjust the steel cooling rate, control the grain deformation and phase change temperature, and improve the strength and plasticity of the steel. The wire feeding is subjected to the Stelmor air cooling line for slow cooling and heat preservation, and the internal organization of the finished steel material is adjusted to be ferrite+pearlite.

[0022] Embodiment one.

[0023] A 6.5mm specification ER70S-6 coil production method, comprising the following steps:

[0024] 1. The chemical composition of the continuous casting billet has the following weight percentages: C: 0.070%; Si: 0.82%, Mn: 1.40%, S, P impurities ≤0.015%, Cr: 0.02%, Ni: 0.012%, Cu: 0.012%, Mo: 0.002%, V: 0.003%, and the rest is iron and inevitable impurities.

[0025] The continuous casting billet is uniformly heated by a three-stage step heating furnace; the three-stage step heating furnace adopts intelligent combustion control technology, and different temperature range standards are set according to different steel grades and production specifications. When the three-stage step heating furnace produces 6.5mm specification ER70S6-steel grade with a billet, a step heating system is adopted, the temperature is slowly increased to reduce Si oxidation, the temperature of the second stage is controlled at 810℃, the temperature of the first stage is controlled at 1020℃, and the temperature of the soaking stage is controlled at 1090℃. When the billet is produced, the temperature of each stage is increased to different degrees, and the opening temperature is controlled at 1010℃. The automatic combustion technology is adopted, and the temperature difference of the billet is controlled within 10℃.

[0026] 2. After the billet is discharged, it is controlled by rough rolling, intermediate rolling and pre-precision rolling, and then cooled by two water tanks; a high-pressure water descaling system is provided before the billet enters the rough rolling unit after being discharged, the water pressure of the high-pressure water descaling system is ≥20MPa, and the iron oxide scale removal rate is ensured to be >99.5%.

[0027] The rough rolling, intermediate rolling and pre-precision rolling area unit uses 14 flat-stand alternating type rolling mills and two DanieI precision rolling mills, multiple passes, small reduction rate and large reduction amount, avoiding work hardening, controlling the material shape to 19.5mm round, and controlling the cross-sectional area to 315mm 2 ; then cooled by two water tanks, the water tank water supply pressure is controlled to 14Bar above water penetration, the rolling piece cooling rate is controlled, after passing through the 3# flying shear cutting head, it enters the DanieI precision rolling mill unit, at this time the temperature is controlled to 920℃, the precision rolling mill unit uses one-drag-two 45° top cross precision rolling mill, a total of eight rolling mills, passing through the full-specification universal roll ring pass, the outlet out-of-roundness is controlled within 0.3mm, and the cross-sectional area is controlled within 53mm 2 .

[0028] 3. The rolling piece is cooled again after passing through the precision rolling mill unit, cooled by three water tanks, the rolling piece temperature is controlled to 910℃ to enter the double-module unit, passes through two rolling mills, finally reaches the required product size, and controls the final wire laying temperature; the three water tanks are uniformly cooled in sections, and the wire laying temperature is also controlled at 830℃, so as to ensure that the product surface is dense, uniform and smooth.

[0029] 4. The rolling piece is produced into a disc round finished product by the wire laying machine, a flying shear device is installed in front of the wire laying machine, the flying shear device adopts DanieI high-speed flying shear device, and automatically shears the steel with oversized head and tail size and mechanical property. After wire laying, it is cooled by a Stelmor air cooling line, and is slowly cooled and heat preserved to adjust the product organization, so as to ensure that the final product is pearlite and ferrite, and has no hardened layer.

[0030] The oxidation burning loss of the produced 6.5mm specification ER70S-6 coil is reduced to below 0.9%, the surface defect rate (indentation, scratch) is reduced by 40%, the grain size is stabilized at above 8.5 level, the rolling force is reduced by 10%, the energy consumption is reduced by 7%, and the yield is increased to above 97.5%.

[0031] Example two.

[0032] A 6.5mm specification ER70S-6 coil production method, comprising the following steps:

[0033] 1. The chemical composition of the continuous casting billet is as follows: C: 0.080%; Si: 0.88%, Mn: 1.49%, S and P impurities ≤0.015%, Cr: 0.04%, Ni: 0.018%, Cu: 0.018%, Mo: 0.002%, V: 0.003%, and the rest is iron and inevitable impurities.

[0034] The continuous casting billet is uniformly heated by a three-stage step heating furnace; the three-stage step heating furnace adopts intelligent combustion control technology, and different temperature range standards are set according to different steel grades and production specifications. When the three-stage step heating furnace produces 6.5mm specification ER70S6-steel, a step heating system is adopted, the temperature is slowly increased to reduce Si oxidation, the temperature of the second heating stage is controlled at 850℃, the temperature of the first heating stage is controlled at 1060℃, and the temperature of the soaking stage is controlled at 1130℃. When producing with a cooled billet, the temperature of each stage is increased to a different degree, and the opening rolling temperature is controlled at 1010℃. An automatic combustion technology is adopted, and the temperature difference of the billet is controlled within 10℃.

[0035] 2. After the billet is discharged, it is controlled in size and cross-sectional area by rough rolling, intermediate rolling and pre-precision rolling, and then cooled by two water tanks. A high-pressure water descaling system is provided before the billet enters the rough rolling unit after being discharged, the water pressure of the high-pressure water descaling system is ≥20MPa, and the iron oxide skin removal rate is ≥99.5%.

[0036] The rough rolling, intermediate rolling and pre-precision rolling area units use 14 flat-stand alternating type rolling mills and two DanieI precision rolling mills, multiple passes, small reduction rate and large reduction amount, avoid work hardening, control the size to 19.5mm round, and control the cross-sectional area to 316mm 2 ; then cooled by two water tanks, the water tank water supply pressure is controlled to 14Bar above water penetration, the rolling piece cooling rate is controlled, after passing through the 3# flying shear cutting head, it enters the DanieI precision rolling mill unit, at this time the temperature is controlled to 940℃, the precision rolling mill unit uses one-drag-two 45° top cross precision rolling mill, a total of eight rolling mills, passes through the full specification universal roll ring pass, the outlet out-of-roundness is controlled to within 0.3mm, and the cross-sectional area is controlled to 54mm 2 .

[0037] 3. After passing through the finishing mill, the rolled piece is cooled again. After passing through three water tanks, the temperature of the rolled piece is controlled to 940℃ before entering the dual-module mill. After passing through two mill stands, the final product size is achieved, and the final wire drawing temperature is controlled. The three water tanks provide segmented and uniform cooling, and the final wire drawing temperature is also controlled at 850℃ to ensure that the product surface is dense, uniform, and smooth.

[0038] 4. The rolled product is produced into a coiled finished product by the wire drawing machine. A flying shear is installed in front of the wire drawing machine. The flying shear is a Danieli high-speed flying shear, which automatically cuts steel with excessive head and tail dimensions and mechanical properties. After wire drawing, the product passes through the Stellmore air cooling line for slow cooling and heat preservation, adjusting the product structure to ensure that the final product contains pearlite and ferrite without a hardened layer.

[0039] The oxidation burn-off rate of the 6.5mm specification ER70S-6 coils was reduced to below 0.8%, and the surface defect rate (indentation, scratches) was reduced by 45%. The grain size was stabilized at grade 8.5 or above. The rolling force was reduced by 15%, and energy consumption was reduced by 8%; the yield rate was increased to over 97.5%.

[0040] Example 3.

[0041] A method for producing 6.5mm specification ER70S-6 coils includes the following steps:

[0042] On March 10, our company's steel rolling mill organized the production of ER70S-6 coils using the relevant technical solutions of this invention.

[0043] The steelmaking furnace number is: L1G1Z225C00210; the rolling sequence number is: L1Z3K325C11001;

[0044] The main chemical components of the steel billet by weight percentage are shown in the table below:

[0045] C Si Mn P S Cr Ni Cu Mo V 0.073％ 0.85％ 1.465％ 0.011％ 0.003％ 0.024％ 0.015％ 0.016％ 0.002％ 0.003％

[0046] A square billet with an end face of 165mm is used, and the billet weight is 2310kg.

[0047] Production is carried out by feeding the cooled billets into the furnace at a temperature of 30℃. A three-stage walking beam furnace is used for continuous heating. The average temperature of the second heating stage is controlled at 847℃, the temperature of the first heating stage is controlled at 1033℃, the average temperature of the soaking stage is controlled at 1112℃, the average rolling temperature is controlled at 1011℃, and the average furnace time is 115 minutes. The decarburization layer depth is controlled.

[0048] To ensure product quality, high-pressure water descaling is performed at the furnace exit point to ensure that the iron oxide scale removal rate reaches over 99.5%.

[0049] Subsequently into the rolling area low speed area is divided into rough rolling, medium rolling, pre-precision rolling three areas, including 14 times Danielet short stress rolling mill and two Danielet finishing mill, rolling mill adopts flat and vertical alternating type arrangement, the rolling process adopts micro tension control, out of two machine frame will be material type controlled to 19.5mm circle, average cross-sectional area data 315mm 2 ; Subsequently into the high speed area, through two water tank cooling, the temperature is controlled at about 925 DEG C, into the finishing eight machine frame area, all use Danielet 45 DEG top intersection finishing mill, the outlet out-of-roundness is controlled at 0.21mm, the cross-sectional area is controlled at 53mm 2 ; Subsequently through two water tank cooling, the temperature is controlled at about 918 DEG C before entering the reducing diameter machine group; Through four Danielet finishing mill, finally rolling is 6.5mm round steel, diameter deviation is 0.1mm, out-of-roundness is 0.2mm, after the finished product, through three water tank subsection uniform cooling, reaches the wire drawing machine, the wire drawing temperature is controlled at 845 DEG C.

[0050] Subsequently into the collection air cooling line area, all the heat preservation cover is closed for heat preservation, the first section of the roller is set to 0.15m / s, the last section of the roller is set to 3m / s, the temperature at the collecting point is controlled at 650 DEG C.

[0051] There are 24 products, the finished product tensile strength is 521-532MPa, elongation after fracture is 27%-32%, the reduction of area is 75.2%-81%.

[0052] The present application is not limited to the above-mentioned embodiments, anyone should know that the structural changes made under the inspiration of the present application, any technical solution with the same or similar to the present application, falls within the scope of the present application.

[0053] The technology, shape, structure part not described in detail in the present application are all known technology.

Claims

1. A method for producing 6.5mm specification ER70S-6 coils, characterized in that, Includes the following steps: S1. The continuously cast square billet is uniformly heated through a three-stage walking beam furnace. S2. After the steel billet exits the furnace, it undergoes rough rolling, intermediate rolling, and pre-finishing rolling to control the material shape and cross-sectional area, and then passes through two water tanks for cooling. S3. After passing through the finishing mill, the rolled piece is cooled again. After passing through three water tanks, the temperature of the rolled piece is controlled to 920±10℃ before entering the dual-module mill. After passing through two mills, the final product size is achieved, and the final wire drawing temperature is controlled. S4. The rolled parts are produced into coiled finished products by the wire drawing machine. A flying shear is installed in front of the wire drawing machine. After wire drawing, the coils are slowly cooled and kept warm by the Stellmore air cooling line.

2. The method for producing 6.5mm specification ER70S-6 coils according to claim 1, characterized in that, The dimensions of the continuously cast square billet in step S1 are 165*165*12000mm.

3. The method for producing 6.5mm specification ER70S-6 coils according to claim 2, characterized in that, The chemical composition of the continuously cast square billet by weight percentage is as follows: C: 0.070-0.080%; Si: 0.82-0.88%; Mn: 1.40-1.49%; S and P impurity elements ≤0.015%; Cr: 0.02-0.04%; Ni: 0.012-0.018%; Cu: 0.012-0.018%; Mo: 0.002%; V: 0.003%; with the remainder being iron and unavoidable impurities.

4. The method for producing 6.5mm specification ER70S-6 coils according to claim 1, characterized in that, The three-stage walking beam furnace in step S1 adopts intelligent combustion control technology and sets different temperature range standards according to different steel grades and production specifications.

5. The method for producing 6.5mm specification ER70S-6 coils according to claim 4, characterized in that, When the three-stage walking beam furnace produces 6.5mm ER70S6 steel using cold billets, it adopts a stepped heating system, slowly increasing the temperature to reduce Si oxidation. The temperature of the second heating stage is controlled at 830±20℃, the temperature of the first heating stage is controlled at 1040±20℃, and the temperature of the soaking stage is controlled at 1110±20℃. When producing using cold billets, the temperature of each stage increases to varying degrees. The initial rolling temperature is controlled at 1010℃. Automatic combustion technology is used, and the temperature difference of the billet through the bar is controlled within 10℃.

6. The method for producing 6.5mm specification ER70S-6 coils according to claim 1, characterized in that, In step S2, a high-pressure water descaling system is set up before the billet enters the roughing mill after exiting the furnace. The water pressure of the high-pressure water descaling system is ≥20MPa to ensure that the iron oxide scale removal rate is >99.5%.

7. The method for producing 6.5mm specification ER70S-6 coils according to claim 1, characterized in that, In step S2, the roughing, intermediate, and pre-finishing mills utilize 14 alternating horizontal and vertical mills and two Danieli finishing mills, employing multiple passes with small reduction rates and large reductions to control the material shape to a 19.5mm circle with a cross-sectional area of ​​315-316mm². 2 The rolled piece then undergoes cooling via two water tanks, with the water supply pressure controlled at over 14 Bar to regulate the cooling rate. After passing through the No. 3 flying shear head, it enters the Danieli finishing mill, where the temperature is controlled at 930±10℃. The finishing mill uses a 1-to-2 45° top-crossing finishing mill, with a total of eight stands. Using a universal roll ring pass, the out-of-roundness at the exit is controlled within 0.3mm, and the cross-sectional area is controlled at 53-54mm². 2 .

8. The method for producing 6.5mm specification ER70S-6 coils according to claim 1, characterized in that, In step S3, the three water tanks are cooled in sections to achieve uniform cooling, and the spinning temperature is ultimately controlled at 840±10℃.

9. The method for producing 6.5mm specification ER70S-6 coils according to claim 1, characterized in that, In step S4, the flying shear equipment used is the Danieli high-speed flying shear equipment, which automatically cuts steel with excessive head and tail dimensions and excessive mechanical properties.