CN114535806A - 450 MPa-grade cold-rolled dual-phase steel and welding method for acid rolling process thereof - Google Patents

450 MPa-grade cold-rolled dual-phase steel and welding method for acid rolling process thereof Download PDF

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CN114535806A
CN114535806A CN202210361604.3A CN202210361604A CN114535806A CN 114535806 A CN114535806 A CN 114535806A CN 202210361604 A CN202210361604 A CN 202210361604A CN 114535806 A CN114535806 A CN 114535806A
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welding
steel
less
equal
strip
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余灿生
常智渊
郑之旺
郑昊青
靳阳
陈述
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/20—Bonding
    • B23K26/21—Bonding by welding
    • B23K26/24—Seam welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/60—Preliminary treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/38—Selection of media, e.g. special atmospheres for surrounding the working area
    • B23K35/383—Selection of media, e.g. special atmospheres for surrounding the working area mainly containing noble gases or nitrogen
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N19/00—Investigating materials by mechanical methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention discloses 450 MPa-grade cold-rolled dual-phase steel and a welding method of an acid rolling process thereof, wherein the 450 MPa-grade cold-rolled dual-phase steel comprises the following components in percentage by weight: 0.03 to 0.11%, Si: 0.05-0.60%, Mn: 1.00-1.60%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Als: 0.010 percent to 0.090 percent and less than or equal to 0.008 percent of N; the rest elements are Fe and inevitable impurities for control. The welding is that 450MPa grade cold rolling dual-phase steel is selected as a connecting material, after the connecting material and the raw material steel coil are cut, welding is carried out after the welding surfaces of the connecting material and the raw material steel coil are aligned and are positioned on the same horizontal plane, after welding, post-welding annealing and polishing treatment are carried out on a welding seam, and the welding seam quality is checked through measuring the thickness of the welding seam and a cupping test. Therefore, the technical problems of instability and low production efficiency in the production process in the prior art are effectively solved, and the purpose of ensuring stable and efficient production of the 450 MPa-grade cold-rolled dual-phase steel acid rolling process is achieved.

Description

450 MPa-grade cold-rolled dual-phase steel and welding method for acid rolling process thereof
Technical Field
The invention relates to the technical field of steel rolling production processes, in particular to 450 MPa-grade cold-rolled dual-phase steel and a welding method for the 450 MPa-grade cold-rolled dual-phase steel acid rolling process.
Background
The welding equipment is used for welding the front steel coil and the rear steel coil to realize the continuous production of steel enterprises, and the method is an important technological means for improving the production efficiency and reducing the production cost. Is widely applied to an acid rolling combined unit, a continuous annealing/galvanizing unit and the like to realize continuous and efficient production. Laser welding is a method of welding by the heat generated by a focused laser beam as an energy source to bombard a weldment. Because the laser has optical properties of refraction, focusing and the like, the laser welding has the characteristics of low heat input, small welding deformation, no electromagnetic field influence and the like, and is widely applied to welding raw materials of the acid rolling combined unit. If the welding effect is not added, the strip breakage accident along the welding line is easy to happen in the pickling and cold rolling processes, the continuous production is not facilitated, the production efficiency and the production safety are seriously affected, and the production rhythm, transition materials, welding key processes and the like of the strip breakage accident need to be studied in detail so as to obtain good welding quality and promote continuous and efficient production.
The patent document with publication number CN 104842056A discloses a welding line plasticizing device and a process for a super-high-strength dual-phase steel laser tailor-welded blank, wherein the welding line of the super-high-strength dual-phase steel tailor-welded blank is arranged between a heat conduction material and a cooling plate, so that the flatness of a welded plate is ensured, and meanwhile, an electromagnetic chuck is adopted for accurately positioning to assemble the material; switching on a high-frequency heating coil to adjust the output power, ensuring the output temperature to be 800-850 ℃, keeping the temperature for 3-5 min, and austenitizing the welded seam tissue; rapidly cooling the welding line of the ultrahigh-strength dual-phase steel tailor-welded blank by adopting a cooling plate filled with cooling liquid; adjusting the output power of the high-frequency heating coil, ensuring the output temperature to be 250-300 ℃, and preserving the heat for 5-30 s; reducing the flow rate of the cooling liquid, improving the output power of the high-frequency heating coil, ensuring the output temperature to be 300-380 ℃, keeping the temperature for 10-90 s, and performing a local distribution process on the weld joint; reducing the output power of the high-frequency heating coil to zero; and (3) rapidly cooling the welding line of the ultrahigh-strength dual-phase steel tailor-welded blank to room temperature by adopting the cooling plate filled with cooling liquid. The average value of the grain sizes of the obtained welding lines is 1.5-4.0 mu m, the cupping value of the dual-phase steel tailor-welded blank with the ultra-high strength steel is 7.3-9.9 mm, and the cupping value of the tailor-welded blank is improved by 43%. However, the technical scheme does not detail production rhythm, transition material selection basis, raw material requirements, strip head/tail treatment, welding key process parameters and the like, and equipment is specially modified, so that the conventional machine set is not favorable for completing welding of the acid rolling raw materials.
Patent document CN 113118630A discloses a method for preparing a laser tailor-welded blank with different thicknesses, which comprises the steps of purifying two DP steel plates with different thicknesses (the thickness difference is less than or equal to 0.5mm, the C content difference is less than or equal to 0.03%, and the Mn content difference is less than or equal to 0.4%), cooling, air-drying and placing on a welding workbench. The horizontal gap of the DP steel plate is 0mm, the gap in the vertical direction is 0.05-0.08 mm, and the defocusing amount is 0.2-1.0 mm in the welding process; the laser power is 3.7-4.2 kW; the welding speed is 5.0-8.0 m/min; the laser offset is 0.4-0.7 mm, a protective gas blowing device is adopted to blow gas, and the distance between a gas blowing port and a welding line is 20-28 mm; a protective gas of 30-60 degrees is argon gas between the blowing opening of the blowing measuring device and the DP steel plate to be welded, and the gas flow is 900-1000L/H; welding of 590DP and 780DP finished products is realized. However, the welding thickness of the finished product of the technical scheme is thin, no basis is provided for the production rhythm and the selection of transition materials, and guidance cannot be provided for the welding method of the acid rolling process of the 450 MPa-grade cold-rolled dual-phase steel.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: provides 450 MPa-grade cold-rolled dual-phase steel which can ensure stable and efficient production of an acid rolling process.
In order to solve the technical problems, the invention adopts the technical scheme that: 450MPa grade cold-rolled dual-phase steel, which comprises the following components in percentage by weight: 0.03 to 0.11%, Si: 0.05-0.60%, Mn: 1.00-1.60%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Als: 0.010 percent to 0.090 percent and less than or equal to 0.008 percent of N; the rest elements are Fe and inevitable impurities.
Further, the method comprises the following steps: comprises the following components in percentage by weight: 0.05-0.09%, Si: 0.15 to 0.35%, Mn: 1.15-1.50%, Al: 0.015-0.060 percent, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S and less than or equal to 0.004 percent of N; the rest elements are Fe and inevitable impurities.
The invention also discloses a welding method for the 450 MPa-grade cold-rolled dual-phase steel acid rolling process, which adopts the technical scheme that: the welding adopts 450MPa grade cold rolling dual-phase steel as a connecting material, after the connecting material and the raw material steel coil are cut, the welding surfaces of the connecting material and the raw material steel coil are aligned and positioned on the same horizontal plane for welding, after the welding, the welding seam is subjected to post-welding annealing and polishing treatment, and the welding seam quality is checked through measuring the thickness of the welding seam and a cupping test;
wherein, the steel coil is cooled to less than or equal to 75 ℃ before welding, and the yield strength of the strip steel with higher strength in the two steel coils before and after welding is not more than 1.5 times of the yield strength of the strip steel with lower strength;
the carbon equivalent of the connecting material selected for welding is controlled within the range of 0.05-0.40 according to the following formula, wherein the carbon equivalent formula is Ceq ═ C + Mn/6+ Si/24+ Ni/40+ Cr/5+ Mo/4+ V/14 (%).
Further, the method comprises the following steps: the shearing adopts double-shearing, the inclination angle between the shearing edge and the steel strip in the shearing process is 2 degrees, and the clearance range of the shearing edge is controlled to be 0.30-0.65 mm.
Further, the method comprises the following steps: the control of the shear blade gap is determined according to the steel strip thickness according to the following requirements, when the steel strip thickness is less than or equal to 2.5mm, the shear blade gap is 0.30mm, and when the steel strip thickness is increased by 0.5mm, the shear blade gap is increased by 0.05 mm; the cutting edge is replaced according to the period of being less than or equal to 10500t or the cutting frequency of being less than or equal to 14000 times, the side clearance of the cutting edge is calibrated after the cutting edge is replaced every time, the cutting cross section and the longitudinal direction of the strip steel form 90 degrees, and the defects of smooth and straight cutting end face, no burr, no layering and the like need to be ensured.
Further, the method comprises the following steps: during shearing, the cutting length of the steel coil is controlled according to the following requirements, and welding is carried out after the plate shape and the surface quality are ensured;
the control requirements for the resection length are as follows: the cutting length is 4.5mm when the thickness t of the strip steel is less than 2.75mm, the cutting length is 3.3mm when the thickness t of the strip steel is less than or equal to 2.75mm and less than 4.0mm, and the cutting length is 2.6mm when the thickness t of the strip steel is more than or equal to 4.0mm, thereby ensuring that the defects of the head and the tail of the strip can be completely cut without deteriorating the welding quality.
Further, the method comprises the following steps: the surface flatness of the strip steel is required to be less than or equal to 250um, the camber is required to be less than or equal to 30mm/10m, hc-h40The convexity requirement is less than or equal to 160 mu m, the wave height requirement is less than or equal to 15mm/5m, and the warping requirement is less than or equal to 35.
Further, the method comprises the following steps: the welding is carried out by adopting a laser welding machine, the jumping range of the thickness of the welding machine is less than or equal to 1.8H1, the jumping range of the width is less than or equal to 360mm, and each side is less than or equal to 180mm, wherein H1 is the thickness of the thinner strip steel, and the unit is mm; in the laser welding process, a laser beam is focused into a welding spot by utilizing a focusing position or a spot position, the height adjusting range of the focusing position is 0-9.0 mm, the Z-axis control precision is +/-0.05 mm, the adjusting range of the spot position is +/-1.5 mm, and the X-axis control precision is +/-0.05 mm.
Further, the method comprises the following steps: the power of the laser welding is 12 +/-0.8 KW, and the welding speed is controlled to be 3.6-6.4 +/-0.3 m/min according to the thickness of the strip steel; introducing gas for protection in the whole welding process, wherein the protective gas is He and N2And CO, wherein the auxiliary gas during welding is He; cleaning a weld joint by using a rolling wheel after welding is finished, wherein the pressure of the rolling wheel is less than or equal to 75KN, and the height of the rolling wheel is 0-7.8 mm;
wherein the welding speed is 6.4 +/-0.3 m/min when the thickness of the strip steel is less than or equal to 2.5mm, the welding speed is reduced by 0.3m/min when the thickness of the strip steel is increased by 0.5mm, and the compensation range of the welding speed is 0-15%;
the flow rate of He in the welding protective gas is 45-51 NL/h, and N2The flow rate of the mixed gas is 8.0-12.0 NL/h, the flow rate of the CO is 1.8-2.3 NL/h, the dew point of the mixed gas is less than or equal to minus 50 ℃, the pressure is 0.4-0.7 MPa, and the temperature is 5-50 ℃;
the flow rate of the auxiliary gas He is 90-160 NL/min, the pressure is 0.4-0.7 MPa, and the temperature is 5-50 ℃.
Further, the method comprises the following steps: in the welding process, the thickness of a welding seam is 1.02-1.20 times of that of the raw material steel strip; when the weld seam is sampled and the cupping test is carried out, the number of sampling points is at least 3, the left point and the right point are taken within a range of 100-200 mm from the edge part, the third point is taken in the middle of the steel strip, the hole diameter of a punching hole of the sampling point is 15mm, and the punching hole is 100mm away from the weld seam;
the requirement of the cupping test is that if the crack is vertical to the direction of the weld seam in the heat affected zone and the crack is vertical to the direction of the weld seam, the weld seam is judged to be qualified; if the crack is coincident with the welding seam, determining that the welding seam quality is unqualified; two welding seams are not allowed in one large coil, otherwise, the coil is judged to be unqualified;
when the welding is carried out with width jump connection, a crescent bay punching experiment is required,
(1) punching at the welding seam, wherein the punching amount is 30mm relative to the width of the narrow strip steel,
(2) in the case of narrow and wide, punching was performed twice at a position deviated from the wide side toward the inlet side by 240mm from the weld and at the weld,
(3) in the case of narrowing the width, punching was performed twice at a position deviated from the wider side by 240mm from the weld toward the exit side and at the weld,
after the experiment, the transition of the width jumping steel coil can be carried out without problems.
The beneficial effects of the invention are: the 450 MPa-grade cold-rolled dual-phase steel comprises the following components in percentage by weight: 0.03 to 0.11%, Si: 0.05-0.60%, Mn: 1.00-1.60%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Als: 0.010 percent to 0.090 percent and less than or equal to 0.008 percent of N; controlling the other elements of Fe and inevitable impurities, and welding the steel coil before acid rolling according to the following method, namely selecting 450 MPa-grade cold-rolled dual-phase steel as a connecting material, shearing the connecting material and the raw material steel coil to enable the welding surfaces of the connecting material and the raw material steel coil to be aligned and to be positioned on the same horizontal plane for welding, carrying out post-welding annealing and polishing treatment on a welding seam after welding, and checking the quality of the welding seam through measuring the thickness of the welding seam and a cupping test; cooling the steel coils to be less than or equal to 75 ℃ before welding, wherein the yield strength of the steel strips with higher strength in the two steel coils before and after welding is not more than 1.5 times of the yield strength of the steel strips with lower strength; the carbon equivalent of the connecting material selected for welding is controlled within the range of 0.05-0.40 according to the following formula, wherein the carbon equivalent formula is Ceq ═ C + Mn/6+ Si/24+ Ni/40+ Cr/5+ Mo/4+ V/14 (%). Therefore, the technical problems of instability and low production efficiency in the production process in the prior art are effectively solved, and the purpose of ensuring stable and efficient production of the 450 MPa-grade cold-rolled dual-phase steel acid rolling process is achieved.
Drawings
FIG. 1 is a schematic representation of the quality of the weld after welding according to the present invention.
Detailed Description
In order to facilitate understanding of the present invention, the present invention will be further described with reference to the drawings and examples.
The invention discloses 450 MPa-grade cold-rolled dual-phase steel which comprises the following components in percentage by weight: 0.03 to 0.11%, Si: 0.05-0.60%, Mn: 1.00-1.60%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Als: 0.010 percent to 0.090 percent and less than or equal to 0.008 percent of N; the rest elements are Fe and inevitable impurities. The welding method for the 450MPa cold-rolled dual-phase steel acid rolling procedure disclosed by the invention is characterized in that 450MPa cold-rolled dual-phase steel is selected as a connecting material for welding, after the connecting material and a raw material steel coil are cut, the welding surfaces of the connecting material and the raw material steel coil are aligned and are positioned on the same horizontal plane for welding, after welding, the welding seam is subjected to post-welding annealing and polishing treatment, and the quality of the welding seam is checked through measuring the thickness of the welding seam and a cupping test; before welding the steel coils, the steel coils need to be cooled to be less than or equal to 75 ℃, and the yield strength of the steel strips with higher strength in the two steel coils before and after welding is not higher than 1.5 times of the yield strength of the steel strips with lower strength; the carbon equivalent of the connecting material selected for welding is controlled within the range of 0.05-0.40 according to the following formula, and the adopted carbon equivalent formula is Ceq ═ C + Mn/6+ Si/24+ Ni/40+ Cr/5+ Mo/4+ V/14 (%). According to the welding method for the acid rolling process of the 450 MPa-grade cold-rolled dual-phase steel, disclosed by the invention, the material parameters including temperature, straightness, camber and convexity, thickness/width transition, good surface quality, shearing process and quality of a connecting material, and key welding processes including welding wire selection, laser power, welding speed and the like are regulated, as shown in figure 1, a welding seam with a smooth surface and no crack is obtained, no defects such as inclusion, incomplete penetration, misalignment and the like exist in a welding seam area, the stable and efficient production of the acid hydrolysis process is ensured, and guidance can be provided for producing the 450 MPa-grade cold-rolled dual-phase steel by using similar units at home and abroad.
The components of the 450 MPa-grade cold-rolled dual-phase steel can be further optimized according to actual needs, and the components comprise the following components in percentage by weight: 0.05-0.09%, Si: 0.15 to 0.35%, Mn: 1.15 to 1.50%, Al: 0.015-0.060%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, N is less than or equal to 0.004%; the rest elements are Fe and inevitable impurities.
In the welding method disclosed by the invention, when the raw material steel coil is selected, the surface of the raw material is required not to have serious concave-convex printing, scratching and wrinkling, the normal hot-rolled iron scale is observed visually, the defect exceeding the standard is avoided, and the wave shape, the warping and the like of the steel coil needing to be welded are not too large. The thickness range of the welded raw material steel coil is 1.9-6.0 mm, and the width range is 850-1650 mm. When 450MPa grade cold rolling dual-phase steel is selected as the connecting material, the surface flatness requirement of the connecting material is less than or equal to 250um, the camber requirement is less than or equal to 30mm/10m, hc-h40The convexity requirement is less than or equal to 160 mu m, the wave height requirement is less than or equal to 15mm/5m, and the warping requirement is less than or equal to 35.
According to the welding method, before welding, the first connecting material and the raw material steel coil need to be sheared, double shearing is adopted for shearing, the inclination angle between the shearing edge and the steel strip in the shearing process is 2 degrees, the tail part of the former steel coil and the head part of the latter steel coil need to be sheared by double shearing to remove a certain length before welding so as to ensure the shape of the plate and weld after the quality is indicated, and the gap range of the shearing edge is controlled to be 0.30-0.65 mm; the control of the shear blade clearance is determined according to the steel strip thickness according to the following requirements, when the steel strip thickness is less than or equal to 2.5mm, the shear blade clearance is 0.30mm, and when the steel strip thickness is increased by 0.5mm, the shear blade clearance is increased by 0.05 mm; the shearing edge is replaced according to the period of not more than 10500t or the shearing frequency of not more than 14000 times, the side clearance of the shearing edge is calibrated after the shearing edge is replaced every time, the shearing cross section and the longitudinal direction of the strip steel form 90 degrees, and the defects of smooth and straight shearing end face, no burr, layering and the like need to be ensured.
In addition, during shearing, the cutting length of the steel coil is controlled according to the following requirements, and welding is carried out after the plate shape and the surface quality are ensured; the control requirements for the resection length are as follows: the cutting length is 4.5mm when the thickness t of the strip steel is less than 2.75mm, the cutting length is 3.3mm when the thickness t of the strip steel is more than or equal to 2.75mm and less than 4.0mm, and the cutting length is 2.6mm when the thickness t of the strip steel is more than or equal to 4.0mm, so that the defects of the head and the tail of the strip can be completely cut, and the welding quality cannot be deteriorated.
The welding method adopts laser welding to weld, the jumping range of the thickness of the welding machine is less than or equal to 1.8H1, the jumping range of the width is less than or equal to 360mm, and each side is less than or equal to 180mm, wherein H1 is the thickness of the thinner strip steel, and the unit is mm; in the laser welding process, a focusing position or a light spot position is utilized to focus a laser beam into a welding light spot, the height adjusting range of the focusing position is 0-9.0 mm, the Z-axis control precision is +/-0.05 mm, the adjusting range of the light spot position is +/-1.5 mm, and the X-axis control precision is +/-0.05 mm. The laser welding power is 12 +/-0.8 KW, and the welding speed is controlled to be 3.6-6.4 +/-0.3 m/min according to the thickness of the strip steel; introducing gas for protection in the whole welding process, wherein the protective gas is He and N2And CO, wherein the auxiliary gas during welding is He; cleaning a weld joint by using a rolling wheel after welding is finished, wherein the pressure of the rolling wheel is less than or equal to 75KN, and the height of the rolling wheel is 0-7.8 mm; wherein the welding speed is 6.9 +/-0.3 m/min when the thickness of the strip steel is less than or equal to 2.5mm, the welding speed is reduced by 0.3m/min when the thickness of the strip steel is increased by 0.5mm, and the compensation range of the welding speed is 0-15%; the flow rate of He in the welding protective gas is 45-51 NL/h, and N2The flow rate of (A) is 8.0 to 12.0NL/h, and the flow rate of CO is 1.8 to 2.3NLThe dew point of the mixed gas is less than or equal to minus 50 ℃, the pressure is 0.4 to 0.7MPa, and the temperature is 5 to 50 ℃; the flow rate of the auxiliary gas He is 90-160 NL/min, the pressure is 0.4-0.7 MPa, and the temperature is 5-50 ℃. In the welding process, the thickness of the welding seam is 1.02-1.20 times of that of the raw material steel strip.
After the welded seam is annealed and polished after welding, the surface of the welded seam is required to be smooth and free of cracks, the welded seam area cannot have the defects of inclusion, incomplete penetration, misalignment and the like, and the quality of the welded seam needs to be checked through measuring the thickness of the welded seam and a cupping test.
When the weld seam is sampled and the cupping test is carried out, the number of sampling points is at least 3, the left point and the right point are taken within a range of 100-200 mm from the edge part, the third point is taken in the middle of the steel strip, the hole diameter of a punching hole of the sampling point is 15mm, and the punching hole is 100mm away from the weld seam; the requirement of the cupping test is that if the crack is vertical to the direction of the weld seam in the heat affected zone and the crack is vertical to the direction of the weld seam, the weld seam is judged to be qualified; if the crack is coincident with the welding seam, determining that the welding seam quality is unqualified; two welding seams are not allowed in one large coil, otherwise, the coil is judged to be unqualified; the welding needs to be carried out towards crescent bay experiment when width jump links up, and the experiment requirement is as follows:
(1) punching at the welding seam, wherein the punching amount is 30mm relative to the width of the narrow strip steel,
(2) in the case of narrow and wide, punching was performed twice at a position deviated from the wide side toward the inlet side by 240mm from the weld and at the weld,
(3) in the case of narrowing the width, punching was performed twice at a position deviated from the wider side by 240mm from the weld toward the exit side and at the weld,
after the experiment, the transition of the width jumping steel coil can be carried out without problems.
Examples
Example 1
After 3.8mm of a tail shear of a 450 MPa-grade cold-rolled dual-phase steel (chemical composition is 0.072% C, 0.28% Si, 1.38% Mn, 0.011% P, 0.007% S, 0.039% Als, carbon equivalent is 0.30) coil with a coil temperature of 53 ℃ and a dimensional schedule of 3.80X 1370mm was cut, the steel was welded at a speed of 5.2m/min with a coil head shear of 3.65X 1350mm 450DP (chemical composition is 0.070% C, 0.25% Si, 1.40% Mn, 0.009% P, 0.006% S, 0.033% Als, carbon equivalent is 0.31) at a coil temperature of 51 ℃ and a coil head shear of 3.9mm, using a welding current of 12.5 in combination. The welding seam welded by the welding process is flat and smooth, has no nodules, craters and welding penetration, has no cracks along the welding seam and good effect of punching crescent in a cupping test, and has no strip breakage accident caused by the welding seam in the pickling and cold rolling processes.
Example 2
After 3.9mm of a tail of a 450MPa grade cold-rolled dual-phase steel (chemical components of 0.068% C, 0.26% Si, 1.40% Mn, 0.010% P, 0.004% S, 0.035% Als, and a carbon equivalent of 0.30) coil with a coil temperature of 45 ℃ and a size of 4.50 × 1290mm was cut off, the steel coil was cut at 4.2mm of a head of a 590DP (chemical components of 0.09% C, 0.55% Si, 1.58% Mn, 0.012% P, 0.007% S, 0.043% Als, and a carbon equivalent of 0.41) coil with a coil temperature of 47 ℃ and a size of 4.30 × 1340mm, and the steel coil was welded at a speed of 4.4m/min by using a welding current of 12.3 kW. The welding seam welded by the welding process is flat and smooth, has no nodules, scars or welding through, has no crack along the welding seam in a cupping test, has good effect of punching crescent, and has no belt breakage accident caused by the welding seam in the acid washing and cold rolling processes.
Comparative example 1
After 3.9mm of a tail of a 450MPa grade cold-rolled dual-phase steel (chemical composition of 0.073% C, 0.28% Si, 1.41% Mn, 0.015% P, 0.007% S, 0.085% Als, carbon equivalent of 0.32) coil whose coil temperature is 42 ℃ and whose size is 3.50 × 1310mm was cut off, 7.6mm of a head of a coil whose coil temperature is 48 ℃ and whose size is 4.10 × 1330mm was cut off with 1180DH (chemical composition of 0.125% C, 0.35% Si, 2.32% Mn, 0.011% P, 0.002% S, 0.045% Als, 0.61% Cr, 0.025% Nb, 0.028% Ti, 0.33% Mo, 0.0025% B, carbon equivalent of 0.73), and the welding was performed at a welding speed of 5.2m/min with a welding current of 12.3 kW. The welding seam welded by the welding process has poor quality, cracks appear along the welding seam during a cupping test, and a connecting material is changed after continuous production is not normally carried out.

Claims (10)

1.450 MPa-grade cold-rolled dual-phase steel, which is characterized in that: comprises the following components in percentage by weight: 0.03 to 0.11%, Si: 0.05-0.60%, Mn: 1.00-1.60%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Als: 0.010 percent to 0.090 percent and less than or equal to 0.008 percent of N; the rest elements are Fe and inevitable impurities.
2. The 450MPa grade cold rolled dual phase steel according to claim 1, characterized in that: comprises the following components in percentage by weight: 0.05-0.09%, Si: 0.15 to 0.35%, Mn: 1.15-1.50%, Al: 0.015-0.060 percent, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S and less than or equal to 0.004 percent of N; the rest elements are Fe and inevitable impurities.
3. Welding method for the pickling process of a 450MPa grade cold rolled dual phase steel according to claim 2, characterized in that: the welding method comprises the following steps of selecting 450 MPa-grade cold-rolled dual-phase steel as a connecting material, shearing the connecting material and a raw material steel coil, aligning welding surfaces of the connecting material and the raw material steel coil, keeping the welding surfaces on the same horizontal plane, then welding, carrying out post-welding annealing and polishing treatment on a welding seam after welding, and checking the quality of the welding seam through measuring the thickness of the welding seam and a cupping test;
wherein, the steel coil is cooled to less than or equal to 75 ℃ before welding, and the yield strength of the strip steel with higher strength in the two steel coils before and after welding is not more than 1.5 times of the yield strength of the strip steel with lower strength;
the carbon equivalent of the connecting material selected for welding is controlled within the range of 0.05-0.40 according to the following formula, wherein the carbon equivalent formula is Ceq ═ C + Mn/6+ Si/24+ Ni/40+ Cr/5+ Mo/4+ V/14 (%).
4. The welding method for the acid rolling process of 450MPa grade cold rolled dual phase steel according to claim 3, wherein: the shearing adopts double-shearing, the inclination angle between the shearing edge and the steel strip in the shearing process is 2 degrees, and the clearance range of the shearing edge is controlled to be 0.30-0.65 mm.
5. The welding method for the acid rolling process of 450MPa grade cold rolled dual phase steel according to claim 4, wherein: the control of the shear blade gap is determined according to the steel strip thickness according to the following requirements, when the steel strip thickness is less than or equal to 2.5mm, the shear blade gap is 0.30mm, and when the steel strip thickness is increased by 0.5mm, the shear blade gap is increased by 0.05 mm; the shearing edge is replaced according to the period of not more than 10500t or the shearing frequency of not more than 14000 times, the side clearance of the shearing edge is calibrated after the shearing edge is replaced every time, the shearing cross section and the longitudinal direction of the strip steel form 90 degrees, and the defects of smooth and straight shearing end face, no burr, layering and the like need to be ensured.
6. The welding method for the acid rolling process of 450MPa grade cold rolled dual phase steel according to claim 3, wherein: during shearing, the cutting length of the steel coil is controlled according to the following requirements, and welding is carried out after the plate shape and the surface quality are ensured;
the control requirements for the resection length are as follows: the cutting length is 4.5mm when the thickness t of the strip steel is less than 2.75mm, the cutting length is 3.3mm when the thickness t of the strip steel is less than or equal to 2.75mm and less than 4.0mm, and the cutting length is 2.6mm when the thickness t of the strip steel is more than or equal to 4.0mm, thereby ensuring that the defects of the head and the tail of the strip can be completely cut without deteriorating the welding quality.
7. The welding method for the acid rolling process of 450MPa grade cold rolled dual phase steel, according to claim 3, wherein: the surface flatness of the strip steel is required to be less than or equal to 250um, the camber is required to be less than or equal to 30mm/10m, and hc-h40The convexity requirement is less than or equal to 160 mu m, the wave height requirement is less than or equal to 15mm/5m, and the warping requirement is less than or equal to 35.
8. The welding method for the acid rolling process of 450MPa grade cold rolled dual phase steel according to claim 3, wherein: the welding is carried out by adopting a laser welding machine, the jumping range of the thickness of the welding machine is less than or equal to 1.8H1, the jumping range of the width is less than or equal to 360mm, and each side is less than or equal to 180mm, wherein H1 is the thickness of the thinner strip steel, and the unit is mm; in the laser welding process, a laser beam is focused into a welding spot by utilizing a focusing position or a spot position, the height adjusting range of the focusing position is 0-9.0 mm, the Z-axis control precision is +/-0.05 mm, the adjusting range of the spot position is +/-1.5 mm, and the X-axis control precision is +/-0.05 mm.
9. The welding method for the 450MPa grade cold rolled dual phase steel acid rolling process according to claim 8, wherein: the power of the laser welding is 12 +/-0.8 KW, and the welding speed is controlled to be 3.6-6.4 +/-0.3 m/min according to the thickness of the strip steel; introducing gas for protection in the whole welding process, wherein the protective gas is He and N2And CO, wherein the auxiliary gas during welding is He; cleaning a weld joint by using a rolling wheel after welding is finished, wherein the pressure of the rolling wheel is less than or equal to 75KN, and the height of the rolling wheel is 0-7.8 mm;
wherein the welding speed is 6.4 +/-0.3 m/min when the thickness of the strip steel is less than or equal to 2.5mm, the welding speed is reduced by 0.3m/min when the thickness of the strip steel is increased by 0.5mm, and the compensation range of the welding speed is 0-15%;
the flow rate of He in the welding protective gas is 45-51 NL/h, and N2The flow rate of the mixed gas is 8.0-12.0 NL/h, the flow rate of the CO is 1.8-2.3 NL/h, the dew point of the mixed gas is less than or equal to minus 50 ℃, the pressure is 0.4-0.7 MPa, and the temperature is 5-50 ℃;
the flow rate of the auxiliary gas He is 90-160 NL/min, the pressure is 0.4-0.7 MPa, and the temperature is 5-50 ℃.
10. The welding method for the 450MPa grade cold rolled dual phase steel acid rolling process according to claim 8, wherein: in the welding process, the thickness of a welding seam is 1.02-1.20 times of that of the raw material steel strip; when the weld seam is sampled and the cupping test is carried out, the number of sampling points is at least 3, the left point and the right point are taken within a range of 100-200 mm from the edge part, the third point is taken in the middle of the steel strip, the hole diameter of a punching hole of the sampling point is 15mm, and the punching hole is 100mm away from the weld seam;
the requirement of the cupping test is that if the crack is vertical to the direction of the weld seam in the heat affected zone and the crack is vertical to the direction of the weld seam, the weld seam is judged to be qualified; if the crack is coincident with the welding seam, determining that the welding seam quality is unqualified; two welding seams are not allowed in one large coil, otherwise, the coil is judged to be unqualified;
when the welding is carried out with width jump connection, a crescent bay punching experiment is required,
(1) punching at the welding seam, wherein the punching amount is 30mm relative to the width of the narrow strip steel,
(2) in the case of narrow and wide, punching was performed twice at a position deviated from the wide side toward the inlet side by 240mm from the weld and at the weld,
(3) in the case of narrowing the width, punching was performed twice at a position deviated from the wider side by 240mm from the weld toward the exit side and at the weld,
after the experiment, the transition of the width jumping steel coil can be carried out without problems.
CN202210361604.3A 2022-04-07 2022-04-07 450 MPa-grade cold-rolled dual-phase steel and welding method for acid rolling process thereof Pending CN114535806A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116497274A (en) * 2023-04-19 2023-07-28 邯郸钢铁集团有限责任公司 Low-cost and easy-rolling 600 MPa-grade hot-rolled dual-phase steel and preparation method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116497274A (en) * 2023-04-19 2023-07-28 邯郸钢铁集团有限责任公司 Low-cost and easy-rolling 600 MPa-grade hot-rolled dual-phase steel and preparation method thereof

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