CN115463989A - Method for improving frequent strip breakage of welding seam of thin-specification high-carbon cold-rolled steel sheet - Google Patents

Method for improving frequent strip breakage of welding seam of thin-specification high-carbon cold-rolled steel sheet Download PDF

Info

Publication number
CN115463989A
CN115463989A CN202210892436.0A CN202210892436A CN115463989A CN 115463989 A CN115463989 A CN 115463989A CN 202210892436 A CN202210892436 A CN 202210892436A CN 115463989 A CN115463989 A CN 115463989A
Authority
CN
China
Prior art keywords
welding
rolling
cold
carbon
rolled steel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210892436.0A
Other languages
Chinese (zh)
Inventor
王野
郭久明
齐林雷
李远旭
郑茂刚
包红军
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rizhao Baohua New Material Co Ltd
Original Assignee
Rizhao Baohua New Material Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rizhao Baohua New Material Co Ltd filed Critical Rizhao Baohua New Material Co Ltd
Priority to CN202210892436.0A priority Critical patent/CN115463989A/en
Publication of CN115463989A publication Critical patent/CN115463989A/en
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
    • B21C37/02—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of sheets
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/50—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for welded joints
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
    • 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
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

The invention discloses a method for improving frequent strip breakage of a welding seam of a thin high-carbon cold-rolled steel plate, belonging to the field of cold-rolled steel plate rolling, and the production process comprises the following steps: heating a plate blank → rough rolling → finish rolling → cooling → coiling to obtain a hot rolled material → uncoiling → welding → crushing scale → acid washing and rinsing → rolling of a five-rack → coiling → coil unloading → annealing → flattening → shearing → cold rolling to obtain a finished product. Compared with the prior art, the method can avoid frequent strip breakage of the welding line, ensure the quality of the thin high-carbon cold-rolled sheet end product and meet the use requirements of users.

Description

Method for improving frequent strip breakage of welding seam of thin-specification high-carbon cold-rolled steel sheet
Technical Field
The invention discloses a divisional application of a 50Mn thin high-carbon cold-rolled steel sheet rolling method (2020109013676), relates to a high-carbon steel production process, and particularly relates to a method suitable for improving frequent strip breakage of a weld joint of a thin high-carbon cold-rolled steel sheet with the thickness of less than or equal to 2.5 mm.
Background
A 50Mn high carbon steel is a high carbon steel product which is widely used, and is generally an intermediate product of a so-called hot rolled steel sheet which is produced from a slab through a continuous hot rolling process, and is cold rolled after a pickling and spheroidizing annealing process to produce a cold rolled steel sheet. The cold-rolled steel sheet is then subjected to an annealing process and a cold-rolling process in this order, and a cold-rolled steel sheet having a desired thickness is produced.
With the progress of the technological process of the hot rolling production line, the production of hot rolled steel plates with the thickness of below 2.5mm is feasible. Because the 50Mn high-carbon steel has high content of C, si and Mn and high strength, the strength of the high-carbon steel is higher than that of the high-carbon steel of the traditional hot rolling process by more than 60MPa under the same specification through the production of a continuous rolling, continuous casting and hot rolling production line. However, since the strength is too high, the thermal conductivity is poor for high carbon steel with a carbon content of more than 0.5% and a thickness of less than or equal to 2.5mm, a significant temperature difference is generated between a welding zone and an unheated part when the high-strength 50Mn high carbon steel is produced through a continuous pickling line, and cracks are easily formed due to internal stress caused in a weld when a molten pool is rapidly cooled; the weld and the heat affected zone are more likely to generate hard and brittle high carbon martensite, so the hardenability tendency and the crack sensitivity are greater, and the weldability is poor. Due to the influence of high welding temperature, crystal grains grow fast, carbides are easy to accumulate and grow on crystal boundaries, welding seams are weak, the strength of welding joints is reduced, rolling is difficult in a cold rolling stage, and particularly high-carbon steel with the thickness less than or equal to 1.5mm is produced, and frequent strip breakage of the welding seams is caused. Therefore, at present, domestic medium-high carbon strip steel is basically produced on a single-stand rolling mill, and the production efficiency is low.
In order to avoid the technical defects of weak welding seams and cold rolling cracking, the invention of China applies for a high-carbon steel thin strip and a production method thereof (CN 201910777534.8) to directly replace a cold rolling annealing product by producing hot rolling thin strip steel with the thickness of less than 2.5mm in one step. However, since the annealing and cold rolling processes are processes necessary for forming fine spheroidized cementite in the pearlite structure of the hot-rolled high carbon steel sheet, this method has a thin gauge and stability, but the yield strength is not large because of the pearlite contained therein, the fatigue life is reduced, and the quality of the final product is not satisfactory.
Disclosure of Invention
The technical task of the invention is to provide a method for improving frequent strip breakage of a welding seam of a thin-gauge high-carbon cold-rolled steel plate aiming at the defects of the prior art.
The technical scheme for solving the technical problem is as follows: a method for improving frequent strip breakage of a welding seam of a thin high-carbon cold-rolled steel plate comprises the following production process steps: heating a plate blank → rough rolling → finish rolling → cooling → coiling to obtain a hot rolled material → uncoiling → welding → crushing scale → acid washing and rinsing → rolling of five racks → coiling → coil unloading → annealing → leveling → shearing → cold rolling to obtain a finished product; the method is characterized in that:
in the high-carbon cold-rolled steel sheet, 0.5 to 0.56 percent of C; 0.2 to 0.3 percent of Si; mn:0.6% -0.7%;
the welding process flow comprises preheating, welding and annealing: after the welding line is preheated for 1 time and annealed for 1 time, the laser welding function of the welding machine is closed by manual control, the annealing power is kept, and the welding wheel of the welding machine moves away from the welding line again to realize secondary annealing;
in the scale breaking procedure, the welding seam passes through a phosphorus breaker, and a bending roller and a straightening roller of the phosphorus breaker are opened;
the cold rolling process adopts a five-stand continuous rolling process, and the compression ratio is 36-50%; distributing the loads of all the racks: a frame: 18-22%, two frames: 20% -25%, three frames: 18-22%, four stands: 12-15%, five shelves: 5 to 6 percent; one working roll adopts a 0.05mm roll curve; 2. thirdly, adopting a 0.06mm roller curve for the fourth frame; five rollers adopt a roller curve of 0 mm; adding rolling liquid into the rolling mill;
the leveling process comprises the following steps: the thickness is less than or equal to 1.5mm, and the leveling elongation is 1.0%; the thickness is more than 1.5mm, and the flat elongation is 1.2%.
Furthermore, the lap welding parameters of the high-carbon steel and the high-carbon steel are that the welding speed is 7.2-7.8 m/min.
Furthermore, the lap welding parameters of the high-carbon steel and the low-carbon steel are that the welding speed is 7.8-8.4 m/min.
Furthermore, in the welding procedure, the preheating temperature for welding the high-carbon steel is 250-350 ℃, and the temperature for stress relief heat treatment is 600-650 ℃.
Furthermore, in the cold rolling procedure, the tension among the first, second, third and fourth frames is 2-5%.
Compared with the prior art, the invention has the following outstanding beneficial effects:
1. the high-strength high-carbon steel is welded under the control of an acid rolling welding machine, so that the rolling stability in the cold rolling stage is ensured, frequent strip breakage of a welding line is avoided, and the stable production of the high-carbon steel on an acid rolling line is realized;
2. the compatibility of thin specification and stability is realized, the strength is ensured, the yield strength is high, the fatigue life is not influenced, the quality of the thin high-carbon cold-rolled sheet end product is ensured, and the use requirement of a user is met;
3. the existing equipment and facilities are utilized, the components are simple, the production cost is not increased, and the popularization is convenient.
Detailed Description
The present invention will be further described with reference to the following specific embodiments. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.
The invention relates to a rolling method suitable for a thin 50Mn high-carbon cold-rolled steel plate with the thickness less than or equal to 2.5 mm.
The production process comprises the following steps: heating a plate blank → rough rolling → finish rolling → cooling → coiling to obtain a hot rolled material → uncoiling → welding → crushing scale → acid washing and rinsing → rolling of a five-rack → coiling → coil unloading → annealing → flattening → shearing → cold rolling to obtain a finished product.
S1, heating the plate blank
The 50Mn high-carbon steel hot rolled material comprises the following components: 0.5 to 0.56 percent of C; 0.2 to 0.3 percent of Si; mn:0.6% -0.7%, P: less than or equal to 0.025 percent; s: less than or equal to 0.005 percent; and (3) Als: less than or equal to 0.02 percent; cr: less than or equal to 0.02 percent; ni is less than or equal to 0.02 percent; cu is less than or equal to 0.02 percent, and the balance is Fe and inevitable impurities.
S2, rough rolling
Outlet temperature: 1160-1180 ℃. The temperature difference between the inlet R1 and the plate is less than or equal to 30 ℃, and the outlet R3 is more than 950 ℃.
S3, finish rolling
The descaling pressure is more than or equal to 340bar, and the finishing temperature is 820-860 ℃.
S4, cooling
Laminar cooling, back cooling and water spraying cooling of the upper and lower surface nozzles are adopted to maintain the opening degree of the nozzle valve at 50%.
S5, coiling to obtain the hot rolled material
The coiling temperature is 675-705 ℃.
The hot rolled product is off-line and intensively cooled slowly, air blowing and forced cooling are not required, and the slow cooling requires 48 hours or the temperature of the hot rolled coil is less than or equal to 200 ℃.
The properties of the hot rolled material obtained by the above steps are shown in the following table:
thickness mm Yield strength MPa Tensile strength MPa Elongation percentage%
1.50 597 870 17.6
1.80 578 865 18.5
2.00 540 846 19.3
2.20 530 843 19.4
2.50 527 840 20.2
S6, uncoiling of hot rolled material
The feeding temperature is less than or equal to 60 ℃.
S7, welding
As the 50Mn high-carbon steel has high content of C, si and Mn components and high strength, hard and brittle high-carbon martensite is more easily generated in a welding seam and a heat affected zone, and the welding performance is poor.
In order to ensure the welding stability and the stable production, the steel grade requirement of lap welding is carried out on the 50Mn high-carbon steel welding requirement and the 50Mn steel grade, the yield strength difference of the two steel grades is less than or equal to 150MPa, and the thickness difference of the two steel coils is less than 10 percent or less than 0.1mm; the width difference is not allowed to exceed 200mm.
The welding machine of the acid rolling combined unit is a Mibach wire filling welding machine. The basic parameters are: the maximum welding speed is 12m/min; the welding power is 12KW at maximum; the maximum pressure of the leveling wheel is 100Bar; the maximum preheating power is 40KW, the maximum annealing power is 40KW, and the maximum laser head pressure is 100Bar; the wire feeding speed of the wire filling is 15m/min.
The lap welding parameters of the 50Mn high-carbon steel and the 50Mn high-carbon steel are shown in the following table, and the process parameters in the table are percentages of the parameters of the welding machine.
Wherein,
the thickness of the raw material is less than 2mm and is less than or equal to 1.50mm, and the welding speed is 60-65% of the maximum parameter of the welding machine
(7.2-7.8 m/min), the welding power is 75% (9 KW) of the maximum parameter of the welding machine, the pressure of the leveling wheel is 10% (10 Bar) of the maximum parameter of the welding machine, the preheating power is 25-30% (10-12 KW) of the maximum parameter of the welding machine, the annealing power is 45-50% (18-20 KW) of the maximum parameter of the welding machine, the pressure of the laser head is 25% (25 Bar) of the maximum parameter of the welding machine, and the wire feeding speed is 75% (11.25 m/min) of the maximum parameter of the welding machine.
The thickness of the raw material is not less than 2mm and not more than 2.5mm, the welding speed is 7.8m/min, the welding power is 9.6-10.2 KW, the pressure of the leveling wheel is 15-20 Bar, the preheating power is 14KW, the annealing power is 22KW, the pressure of a laser head is 30Bar, and the wire feeding speed is 12m/min.
Figure RE-RE-GDA0003898713020000051
Figure RE-RE-GDA0003898713020000061
The lap welding parameters of the 50Mn high-carbon steel and the low-carbon steel are shown in the following table, wherein the process parameters are percentages of the parameters of the welding machine.
Wherein,
the thickness of the raw material is less than 2mm and is less than or equal to 1.50mm, and the welding speed is 65-70 percent of the maximum parameter of the welding machine
(7.8-8.4 m/min), the welding power is 75-80% (9-9.6 KW) of the maximum parameter of the welding machine, the pressure of the leveling wheel is 10% (10 Bar) of the maximum parameter of the welding machine, the preheating power is 25-30% (10-12 KW) of the maximum parameter of the welding machine, the annealing power is 30-45% (12-18 KW) of the maximum parameter of the welding machine, the pressure of the laser head is 25% (25 Bar) of the maximum parameter of the welding machine, and the wire feeding speed is 75% (11.25 m/min) of the maximum parameter of the welding machine.
The thickness of the raw material is less than or equal to 2mm and less than or equal to 2.5mm, the welding speed is 7.8m/min, the welding power is 9.6-10.2 KW, the pressure of a leveling wheel is 15Bar, the preheating power is 14KW, the annealing power is 22KW, the pressure of a laser head is 30Bar, and the wire feeding speed is 12m/min.
Figure RE-RE-GDA0003898713020000062
The welding process of the wire filling welding machine comprises three steps of preheating, welding and annealing: the preheating temperature for welding the high-carbon steel is 250-350 ℃, the temperature for stress relief heat treatment is 600-650 ℃, and the selection of proper preheating power and annealing power in the welding process is crucial. The strength of the hot-rolled 50Mn raw material is higher than the yield strength and tensile strength of the traditional hot-rolled 50 MN. Therefore, the preheating power and the annealing power are increased during welding, and the welding speed is slower. The welding speed is slow, the preheating function and the annealing power are high, and the welding of the two welded steel materials can be better ensured.
In order to ensure that the structure of a heat affected zone of a high-carbon steel weld joint is sorbite and ferrite and ensure the stability of the weld joint, the invention has the most important welding process characteristic of adopting 1-time preheating and 2-time annealing process, and the specific operation is as follows: after the welding seam is preheated for 1 time and annealed for 1 time, the laser welding function of the welding machine is closed by manual control, the annealing power is kept, the welding wheel of the welding machine moves away from the welding seam again, and the secondary annealing power plays a role in heating and insulating the welding seam. The traditional high-carbon steel welding is generally carried out by 1-time preheating and 1-time annealing, because the carbon content of 50Mn is high, the laser welding annealing belongs to air cooling, the cooling speed is high, when the 1-time annealing is adopted, the weld structure can not be completely converted into ferrite and pearlite, bainite and sorbite exist, and the toughness of the weld structure is poor. Meanwhile, the heat affected zone on one side of 50Mn is martensite and sorbite, the brittleness is high, the cup bulge experiment is directly cracked, and the welding seam does not meet the production requirement. When 2 times of annealing is adopted, the effect of heat preservation on the weld joint structure is equivalent to that bainite and sorbite in the weld joint structure are completely replaced by ferrite and pearlite, martensite in the weld joint of the heat affected zone on one side of 50Mn is completely converted into ferrite and sorbite, the structure has good toughness and high strength, the vertical weld joint is cracked during the cup-convex test of the weld joint, and the weld joint meets the production requirement.
S8, breaking scales
Because the high-carbon steel has high strength and relatively poor welding quality, the welding seam is easy to break in the repeated bending process of the phosphorus breaking machine. In order to ensure the stability of the high-carbon steel welding seam over-breaking phosphorus machine, the welding seam over-breaking phosphorus machine, a bending roller and a straightening roller of the phosphorus machine are opened.
S9, acid washing and rinsing
The welding line is broken when the strip steel is repeatedly bent by a tension roller or a phosphorus breaker roller, and the speed of the pickling section needs to be controlled in order to ensure the stable production of high-carbon steel. The speed of the pickling process section is less than or equal to 120m/min.
S10, cold rolling
The five-stand continuous rolling process is adopted, and the following parameters are controlled:
(1) Compression ratio:
because the 50Mn alloy has high component, high raw material strength and large rolling force in the production process, in order to avoid the abnormal conditions of uneven thick plate, poor plate shape or broken welding seam in the production process of a rolling mill, the rolling is usually carried out by adopting a proper compression ratio, so that the rolling force of each frame of the rolling mill can be reduced, and therefore, the design of the 50Mn compression ratio adopts the design idea of a small compression ratio, and the compression ratio is 36-50%.
Thickness of raw material (mm) Finished product thickness (mm) Compression ratio Finished product thickness (mm) Compression ratio
1.5 0.8 46.6％ 0.85 43.3
1.8 0.9 50％ 1 44％
2.0 1.05 48％ 1.2 40％
2.2 1.25 43％ 1.4 36％
2.5 1.45 42％ 1.6 36％
(2) Load distribution for racks
The 50Mn high-carbon steel is produced in a five-stand acid rolling combined unit, and the 50Mn high-carbon steel has higher strength, so that strip steel can stably enter a rolling mill, and the situations of slipping and welding line strip breakage are prevented.
The loads of each rack are distributed as follows:
a frame: 18 to 22 percent of the total weight of the mixture,
II, two frames: 20 to 25 percent.
Three frames: 18-22 percent
Four frames: 12-15%, mainly adopting tension adjustment and inclination adjustment to ensure the plate shape, and simultaneously rolling the plate to the target thickness.
Five frames: 5-6%, and has the effects of leveling and further improving the plate shape.
1. The tension among the second, third and fourth frames is 2-5%, so that the strip steel is prevented from slipping.
(3) The speed of the outlet of the rolling mill is controlled to be less than or equal to 600M/min; when the welding seam passes through each frame of the rolling mill, the positive bending roll is manually reduced. And recovering the roller after the welding seam.
(4) Control of roll profile
After the working roll and the supporting roll are rolled for a long time, the roll shape is greatly changed due to thermal expansion, the roll curve is abraded into an irregular shape at the last stage of the roll, the effect of the positive bending roll is reduced, and the condition that the thickness of the strip steel is not consistent or the strip shape is poor is easy to occur. Therefore, to ensure the rolling smoothness, the 50Mn high carbon steel was arranged to be rolled early in the work rolls. The working roll period is within 2500 tons of rolling quantity, and one working roll adopts a 0.05mm roll curve; 2. and the curves of the three and four frames adopt 0.06mm rollers. Five rolls used 0mm roll curves. 1. And the second and third support rollers are in cycle of 60000 tons of rolling quantity for production discharge. Four and five support rollers can be used for production ranging within 35000 tons. Meanwhile, the material of the front 5 coils of the working roll is not allowed to discharge 50Mn high-carbon steel.
(5) Emulsion parameters of rolling mill
The temperature of the rolling liquid is controlled to be 50 ℃, and the cooling effect is enhanced; the concentration is controlled according to the upper limit, the target concentration of the emulsion A system of the rolling mill is 3.0 percent, the control concentration range of the emulsion L system is 0.3 to 1.0 percent, the optimization target is 0.7 percent, the lubricating effect of the rolling liquid is enhanced, and the rolling force is reduced. 1. The flow rate of the second and third emulsions is controlled to be more than 5600L/min.
S11, winding
S12, coil stripping
S13, annealing
The 50Mn high-carbon steel treated by the process is not suitable for production in a continuous annealing unit and is suitable for production in a traditional bell-type furnace. Therefore, the invention adopts the cover annealing process, the annealing temperature is heated from 400 ℃ to 720 ℃, and the heating time is 12-13 hours; the temperature is kept for 10 to 11 hours at the annealing temperature of 720 ℃.
S15, leveling
Leveling parameters: the thickness is less than or equal to 1.5mm, and the leveling elongation is 1.0%; the thickness is more than 1.5mm, and the flat elongation is 1.2%.
S16, shearing to obtain a cold-rolled finished product
To better compare the process of the present application with the prior art, comparative tests were performed.
The process steps adopted by the control group comprise: heating a plate blank → rough rolling → finish rolling → cooling → coiling to obtain a hot rolled material → uncoiling → welding → crushing scale → acid washing and rinsing → rolling of a five-rack → coiling → coil unloading → annealing → flattening → shearing → cold rolling to obtain a finished product.
The parts of the method of heating the plate blank → rough rolling → finish rolling → cooling → coiling to obtain the hot rolled material are consistent with the method of the embodiment, so the raw material hot rolled material is the same as the embodiment, and the hot rolled material with the thickness of 1.8mm is selected at the moment, except the following, the other process parameters are the same as those in the embodiment with the thickness of 1.8 mm.
In the welding procedure, the traditional technological parameters are adopted, and 1 preheating and 1 annealing process are adopted. In the same thickness specification and the maximum parameter table of the welding machine, the preheating power and the annealing power are respectively reduced by 5 percent, and the welding speed is 7.2m/min. The speed of the pickling process section is 120m/min. Other process parameters are the same as those of the raw material thickness in the same specification embodiment.
The comparison result shows that the thickness specification of the raw material of 1.5-2.5 mm in the example has no broken welding line in the process production, the specification of 1.5mm in the comparison group cannot be produced due to frequent broken welding line, and the frequency of broken welding line in the specifications of 1.8mm, 2mm, 2.25mm and 2.5mm is respectively 5%, 3%, 4% and 6%. From the results, the process for producing the high-strength 50Mn high-carbon steel realizes good rolling stability in the cold rolling stage and avoids frequent strip breakage of welding seams by controlling welding and pickling in the acid rolling welding machine.
In the embodiment, the yield strength of the raw material with the thickness of 1.5-2.5 mm is 590-525MPa, the compatibility of thin specification and stability is realized, the fatigue life is not influenced, the quality of the final product of the 50Mn cold-rolled sheet is guaranteed, and the use requirement of a user is met.
It should be noted that while the invention has been described in detail with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various obvious changes can be made therein without departing from the spirit and scope of the invention.

Claims (5)

1. A method for improving frequent strip breakage of a welding seam of a thin-gauge high-carbon cold-rolled steel plate comprises the following production process steps: heating a plate blank → rough rolling → finish rolling → cooling → coiling to obtain a hot rolled material → uncoiling → welding → crushing scale → acid washing and rinsing → rolling of a five-rack → coiling → coil unloading → annealing → flattening → shearing → cold rolling to obtain a finished product; the method is characterized in that:
in the high-carbon cold-rolled steel sheet, 0.5 to 0.56 percent of C; 0.2 to 0.3 percent of Si; mn:0.6% -0.7%;
the welding process flow comprises preheating, welding and annealing: after the welding line is preheated for 1 time and annealed for 1 time, the laser welding function of the welding machine is closed by manual control, the annealing power is kept, and the welding wheel of the welding machine moves away from the welding line again to realize secondary annealing;
in the scale breaking procedure, the welding seam passes through a phosphorus breaker, and a bending roller and a straightening roller of the phosphorus breaker are opened;
the cold rolling process adopts a five-stand continuous rolling process, and the compression ratio is 36-50%; distributing the loads of all the racks: a frame: 18-22%, two frames: 20% -25%, three frames: 18-22%, four stands: 12-15%, five shelves: 5 to 6 percent; one working roll adopts a 0.05mm roll curve; 2. thirdly, adopting a 0.06mm roller curve for the fourth frame; five rollers adopt a roller curve of 0 mm; adding rolling liquid into the rolling mill;
the leveling process comprises the following steps: the thickness is less than or equal to 1.5mm, and the leveling elongation is 1.0%; the thickness is more than 1.5mm, and the flat elongation is 1.2%.
2. The method for improving frequent strip breakage of a weld of a thin gauge high carbon cold rolled steel sheet according to claim 1, wherein: the lap welding parameters of the high-carbon steel and the high-carbon steel are that the welding speed is 7.2-7.8 m/min.
3. The method for improving frequent strip breakage of the weld of the thin gauge high carbon cold rolled steel sheet according to claim 1, wherein: the lap welding parameters of the high-carbon steel and the low-carbon steel are that the welding speed is 7.8-8.4 m/min.
4. The method for improving frequent strip breakage of a weld of a thin gauge high carbon cold rolled steel sheet according to claim 1, wherein: in the welding procedure, the high-carbon steel welding preheating temperature is 250-350 ℃, and the stress relief heat treatment temperature is 600-650 ℃.
5. The method for improving frequent strip breakage of a weld of a thin gauge high carbon cold rolled steel sheet according to claim 1, wherein: in the cold rolling procedure, the tension among the first, second, third and fourth frames is 2-5%.
CN202210892436.0A 2020-08-31 2020-08-31 Method for improving frequent strip breakage of welding seam of thin-specification high-carbon cold-rolled steel sheet Pending CN115463989A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210892436.0A CN115463989A (en) 2020-08-31 2020-08-31 Method for improving frequent strip breakage of welding seam of thin-specification high-carbon cold-rolled steel sheet

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202010901367.6A CN112077165B (en) 2020-08-31 2020-08-31 Rolling method of 50Mn thin high-carbon cold-rolled steel sheet
CN202210892436.0A CN115463989A (en) 2020-08-31 2020-08-31 Method for improving frequent strip breakage of welding seam of thin-specification high-carbon cold-rolled steel sheet

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
CN202010901367.6A Division CN112077165B (en) 2020-08-31 2020-08-31 Rolling method of 50Mn thin high-carbon cold-rolled steel sheet

Publications (1)

Publication Number Publication Date
CN115463989A true CN115463989A (en) 2022-12-13

Family

ID=73732759

Family Applications (2)

Application Number Title Priority Date Filing Date
CN202210892436.0A Pending CN115463989A (en) 2020-08-31 2020-08-31 Method for improving frequent strip breakage of welding seam of thin-specification high-carbon cold-rolled steel sheet
CN202010901367.6A Active CN112077165B (en) 2020-08-31 2020-08-31 Rolling method of 50Mn thin high-carbon cold-rolled steel sheet

Family Applications After (1)

Application Number Title Priority Date Filing Date
CN202010901367.6A Active CN112077165B (en) 2020-08-31 2020-08-31 Rolling method of 50Mn thin high-carbon cold-rolled steel sheet

Country Status (1)

Country Link
CN (2) CN115463989A (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114381589B (en) * 2021-11-26 2024-04-16 安阳钢铁股份有限公司 Preparation method of environment-friendly and economical steel for goods shelves
CN114643279A (en) * 2022-01-29 2022-06-21 安阳钢铁股份有限公司 Method for controlling shape of ultrathin ultra-wide steel strip for continuous galvanizing
CN115673547A (en) * 2022-11-17 2023-02-03 湖南华菱涟钢特种新材料有限公司 Method for welding hot-rolled medium-high carbon strip steel in acid rolling line and product

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013227624A (en) * 2012-04-25 2013-11-07 Jfe Steel Corp Method of manufacturing high strength cold rolled steel sheet excellent in workability
CN105149810B (en) * 2015-08-12 2017-06-16 北京首钢冷轧薄板有限公司 Prevent the welding method of carbon equivalent high strip steel weld joint broken belt
CN107649512B (en) * 2017-09-08 2019-01-11 新余钢铁股份有限公司 A kind of manufacturing process of 65Mn cold rolling wide strip
CN108034957B (en) * 2017-12-27 2020-02-18 日照宝华新材料有限公司 High-carbon steel welding and pickling method
CN108486500A (en) * 2018-05-15 2018-09-04 首钢集团有限公司 A kind of cold rolling hot dip galvanizing Multiphase Steel and preparation method thereof
CN109604934B (en) * 2018-12-26 2021-02-09 中冶南方工程技术有限公司 Laser welding method for hot-rolled stainless steel

Also Published As

Publication number Publication date
CN112077165A (en) 2020-12-15
CN112077165B (en) 2022-08-09

Similar Documents

Publication Publication Date Title
CN112077165B (en) Rolling method of 50Mn thin high-carbon cold-rolled steel sheet
CN109266815B (en) Shape control method for online quenching high-strength steel plate
CN104946968A (en) Cold-rolled tin plate for beverage can bottom cover and production method of cold-rolled tin plate
CN110055458B (en) Production method of hot-rolled pickled automobile plate
CN108441759B (en) 540 MPa-grade hot-rolled pickled steel plate and manufacturing method thereof
CN110180893A (en) A kind of rolling mill practice for improving 38CrMoAl steel and rolling state tissue
CN106191682A (en) A kind of easy-open end draw ring cold rolling hot-dip galvanized steel sheet and production method thereof
CN107723602A (en) 750MPa levels hot-rolled ferrite-bainite dual-phase steel and its production method
CN111647806B (en) Rolling process of Ti-containing low alloy steel
CN105734403A (en) Hot-rolled coil for saw blade steel and production method of hot-rolled coil
CN111235463B (en) Hot-rolled pickled steel strip for 450 MPa-grade oil well pipe and manufacturing method thereof
CN113699325A (en) Plate shape control method for thin cold-rolled HSLA continuous annealing strip steel
CN107541663B (en) A kind of beverage can ferrostan and its production method
CN110747408B (en) Thin-specification ASNZS 3678-350L15 structural steel plate and manufacturing method thereof
CN113020266A (en) Method for producing 45Mn hot-rolled coil by thin slab continuous casting and rolling production line
CN111349863A (en) Process for producing S350GD + Z hot galvanizing product with thickness less than 2.0mm
CN101831587A (en) 600 MPa-grade hot rolled steel plate and manufacturing method thereof
CN114226453B (en) Manufacturing method for low-carbon steel and improving performance uniformity of ferrite-rolled low-carbon steel
CN103103538A (en) Production method of hot dipped steel coil
CN115945525A (en) Method for improving rolling stability of high-carbon steel for chain
CN111451277A (en) X65 pipeline steel plate and plate shape control method thereof
CN114798736B (en) Method for producing thin pattern steel plate by thin slab continuous casting and rolling process
CN114686751B (en) Brittle failure prevention production method for high-chromium ferrite stainless steel
CN115647070A (en) Control method for comprehensive quality of thin ultrahigh-strength steel plate
CN116607081A (en) 980 MPa-level high-strength automobile plate and production method thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination