CN-121988623-A - Production method for reducing strip-shaped tissues in spring flat steel

Abstract

The invention discloses a production method for reducing strip structures in spring flat steel, which belongs to the technical field of hot rolling narrow strip steel in ferrous metallurgy industry, and comprises the steps of heating a continuous casting blank and then carrying out splitting rolling to obtain the spring flat steel, wherein after a rolled piece is subjected to blooming and pre-finishing rolling, splitting rollers pre-split and splitting wheels complete splitting of the rolled piece, an electromagnetic induction edge heating device is adopted, the electric gap distance of the electromagnetic induction edge heating device is 50-300 mm, exciting current of the electromagnetic induction edge heating device is 500-2500A, the induction heating frequency of the electromagnetic induction edge heating device is 100-2000 Hz, the induction heating frequency of the electromagnetic induction edge heating device is used for ensuring that the temperature of a single side edge of the rolled piece is raised, the temperature difference of the edge of the rolled piece is reduced, the strip structures in the spring flat steel are ensured to be reduced by utilizing the splitting rolling technology and the electromagnetic induction edge heating technology on a hot rolling narrow strip steel production line, grains can be refined, and the production efficiency is improved.

Inventors

• LIU LIU
• ZHU CHENYU
• JIANG YUEDONG
• LI JUN
• LI YANGZHOU
• LIU XIAO
• ZHAO JUNPU
• WANG KAI
• ZHANG JINLING
• JIANG TIANYU

Assignees

• 江苏集萃冶金技术研究院有限公司

Dates

Publication Date

20260508

Application Date

20241104

Claims (8)

1. 1. A method of reducing the banding pattern in spring flat steel, the method comprising: And heating the continuous casting blank, and then cutting and rolling to obtain the spring flat steel, wherein after the rolled piece is subjected to blooming and pre-finish rolling, a cutting roller pre-cuts and a cutting wheel completes cutting of the rolled piece, an electromagnetic induction side heating device is adopted, exciting current of the electromagnetic induction side heating device is 500-3500A, and induction heating frequency of the electromagnetic induction side heating device is 100-2000 Hz and is used for ensuring that temperature of a single side of the rolled piece is raised, and temperature difference of sides of the rolled piece is reduced.
2. 2. The method for producing the strip-shaped structure reduction of the flat spring steel according to claim 1, wherein the casting blank with the cross section edge size ranging from 200mm to 600mm is heated to 1050 ℃ to 1200 ℃ so that the structure of the casting blank is completely converted into an austenite structure, the total reduction rate of the flat spring steel is ensured, and the strip-shaped structure is reduced.
3. 3. The method for producing the spring flat steel with reduced band-shaped structures according to claim 1, wherein the rolled piece after pre-finish rolling is 2 times as large as the cross section of the spring flat steel product, the critical cutting thickness is 1.0 mm-5.0 mm larger than the thickness of the spring flat steel product, the temperature of the rolled piece is controlled within the range of 1000-1150 ℃, and the initial temperature of the rolled piece before cutting is ensured.
4. 4. The method for reducing the strip-shaped tissue in the spring flat steel according to claim 1, wherein the device comprises a slitting roller and a slitting wheel, in the slitting rolling process, the rolled piece is pre-slit by the slitting roller, the thickness of 1.0 mm-2.0 mm at the central connecting position of the rolled piece is reserved, and the slitting of the rolled piece is completed by the slitting wheel.
5. 5. The method for producing a strip-like structure reduced in spring steel strip according to claim 1, wherein at least one electromagnetic induction edge heating device is provided in said hot-rolled strip production line, said electromagnetic induction edge heating device heating the edge of the rolled piece.
6. 6. The method for producing the strip-shaped tissue reducing spring flat steel according to claim 5, wherein the electric gap distance of the electromagnetic induction side heating device is 50-300 mm, the exciting current of the electromagnetic induction side heating device is 500-3500A, and the induction heating frequency of the electromagnetic induction side heating device is 100-2000 Hz, so that the temperature of a single side of a rolled piece is ensured to be increased, and the temperature difference of the side of the rolled piece is reduced.
7. 7. The method according to claim 1, wherein the rolling temperature is controlled in the range of austenite unrecrystallized temperature (750 ℃ to 950 ℃) during the finish rolling.
8. 8. The method of claim 4, wherein the cutting roller and the cutting wheel cut the rolled piece, the center chemical segregation part of the original rolled piece becomes the edge of the new cut piece after cutting, the edge cooling speed is high, and the reduction of the strip structure is ensured.

Description

Production method for reducing strip-shaped tissues in spring flat steel Technical Field The invention belongs to the technical field of hot-rolled narrow strip steel in the ferrous metallurgy industry, and particularly relates to a production method for reducing strip-shaped structures in spring flat steel. Background The spring flat steel is a metal material formed by hot rolling in the metallurgical industry, and has good elastic deformation capability, and the C content is 0.26% -0.90%. The method is mainly applied to manufacturing the leaf springs of machinery such as automobiles, tractors, railway transportation and the like. In the first part of spring steel for automobile suspension system, hot rolled flat steel (GB/T33164.1-2016), the width of the spring flat steel is not more than 180mm and the thickness is not more than 60mm. At present, the spring flat steel is generally smelted and determined to be reasonable in chemical composition combination, and is mostly cast by adopting square or rectangular casting blanks with the cross section single side length of 150-200 mm, so that the spring flat steel is produced by hot rolling the casting blanks on a bar production line or a special small-sized unit, and satisfactory microstructure and mechanical properties are obtained. With the rapid development of the automobile industry and the continuous speed increasing of railway trains, the spring flat steel also develops towards light weight and high strength. An important development of spring flat steels is therefore high strength, long life and light weight. And the fatigue resistance and the elastic reduction resistance are the two main factors influencing the design stress of the spring steel. This requires not only high cleanliness of the spring flat steel but also uniformity of structure in the steel (see fig. 1), and the inability to have a band structure, which affects even distribution of stress in the spring flat steel. The band structure means a structure morphology of ferrite grains and pearlite grains which are arranged in parallel in a rolling direction, distributed in layers, and shaped like a band, which is generated after the steel is hot-rolled and cooled, and is shown in fig. 2. The main forming reason is the segregation of the components in the center of the continuous casting slab, and when the hot working temperature cools, proeutectoid ferrite is generated in the center segregation of the continuous casting slab, and the surrounding austenite is transformed into pearlite, and is mainly distributed in a strip shape in the center of the hot-rolled narrow strip steel. Because the banded structure has obvious directionality and the microstructures of two adjacent bands are different, the uneven internal structure of the banded structure can be caused, the stress concentration is easy to generate, even cracks appear, the plasticity, the impact toughness, the fracture toughness and the area shrinkage of the steel are reduced, the cold bending disqualification and the high stamping rejection rate are caused, the steel is easy to deform and quench and crack during heat treatment, and the service performance of the steel is seriously influenced. Therefore, how to better control the strip-shaped structure in the flat spring steel, improve the quality of the flat spring steel, better meet the demands of users, improve the production efficiency and reduce the manufacturing cost is a problem that flat spring steel production enterprises have to face. The bar cutting and rolling technology originates from the mid seventies, and Canadian iron and steel companies firstly use the two cutting and rolling technology on a small tandem mill to produce deformed steel bars, and compared with the conventional technology, the production rate is improved by 40%. The working principle of the cutting rolling is that a special roll pass and a guide and guard device matched with the special roll pass are utilized on a bar mill to cut a rolled piece into two (or more) rolled pieces along the longitudinal direction, and then the production process of two (or more) finished rolled pieces is rolled. In the 80 s of the last century, new japanese iron, barden corporation of germany, etc. have utilized the guide in-box cutting wheel cutting method to realize multi-line cutting of bars for mass production. At present, split rolling is mainly used for splitting casting blanks and bars. However, in the case of a hot-rolled narrow strip, the width-thickness ratio is large, and the cooling of the edge portion is rapid, so that defects are likely to occur on the strip surface. How to use the split rolling method to produce spring flat steel with the width not more than 180mm on the hot-rolled narrow strip production line is the problem that the split rolling must be solved when applied to the hot-rolled strip production line to remove hot-rolled spring flat steel. The induction heating technology is a technology of converti