Manufacturing method of steel substrate for ultra-wide high-carbon saw blade

Abstract

According to the manufacturing method of the steel substrate for the ultra-wide high-carbon saw blade, the thickness specification of a produced steel plate is 10-15 mm, the width specification is 4500-4800 mm, and the process route comprises the steps of molten iron pretreatment, converter smelting, LF furnace treatment, RH vacuum treatment, continuous casting, heating, rolling, hot straightening, slitting, flaw detection and warehousing. The steel comprises the following chemical components in percentage by weight: 0.67%-0.76% of C, 0.17%-0.37% of Si, 0.90%-1.20% of Mn, 0.50%-0.70% of Cr, less than or equal to 0.020% of P, less than or equal to 0.003% of S and the balance of Fe and inevitable impurities. A 70MnCr component basis is adopted for design, through optimized component design, blank size design, heating temperature and rolling process temperature control, intermediate blank thickness design, optimized straightening procedure design and the like, batch production of saw blade steel substrates is achieved, the plate shape is straight, the unevenness is smaller than or equal to 10 mm / 2 m, and a high-quality substrate is provided for subsequent quenching and tempering heat treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of steel rolling and relates to a method for producing a steel base plate for an ultra-wide high-carbon saw blade. Background Art

[0002] 70MnCr is a typical grade of steel for diamond welding saw blade substrate. It has good hardenability and can reach a hardness of 42~47HRC after heat treatment. It has excellent strength and wear resistance and is widely used in the mining industry. At present, domestic circular saw blades with a diameter of less than 2000mm are manufactured by hot-rolled coils produced by hot rolling mills. For diameters ≥2000mm, steel plates are welded. Fatigue cracks are prone to occur in welded joints during use, reducing the service life of saw blades. Due to the high carbon content of 70MnCr, cracks are prone to occur during the process of slab blanking and cutting. When producing ultra-wide saw blade substrates of 4500~4800mm, the thermal deformation resistance is large, the rolling plate shape is poor, and the production is extremely difficult. Summary of the invention

[0003] The present invention aims to provide a method for manufacturing a steel substrate for ultra-wide high-carbon saw blades. The 70MnCr grade composition design is adopted, and through the optimization of composition control, billet size design, heating temperature and rolling process temperature control, intermediate billet thickness design, and optimized straightening process, the mass production of saw blade steel substrates with a thickness specification of 10-15mm and a width specification of 4500-4800mm is achieved. The plate shape is straight, and the unevenness is ≤10mm / 2m, providing a high-quality substrate for subsequent quenching and tempering heat treatment.

[0004] The technical solution of the present invention: A method for manufacturing a steel substrate for an ultra-wide high-carbon saw blade, wherein the thickness of the produced steel plate is 10-15 mm and the width is 4500-4800 mm, and the process route is molten iron pretreatment → converter smelting → LF furnace → RH vacuum treatment → continuous casting → heating → rolling → hot straightening → slitting → flaw detection → warehousing, characterized in that the chemical composition of the steel is C: 0.67%-0.76%, Si: 0.17%-0.37%, Mn: 0.90%-1.20%, Cr: 0.50%-0.70%, P≤0.020%, S≤0.003%, and the remainder is Fe and unavoidable impurities; the key process steps include: (1) Billet specification design: Use small billets with a cross-section of (150~180) mm*(1800~2270) mm for production, and the billet length ensures that the length of the rolled large plate is ≤25m; (2) Rolling: After the billet is off the line, it is subjected to stack cooling and hydrogen expansion, and the stack cooling time is ≥8h; after stack cooling, it is rolled in a warm furnace, and the billet is heated to 1200~1280℃ for steel production; the rolling adopts hot rolling process, the rough rolling temperature is greater than 1150℃, the intermediate billet is 50~80mm, and the finishing rolling adopts hot rolling with a starting rolling temperature of ≥1050℃; (3) Hot straightening: The rolled steel plate is hot straightened for 5 times, using a 3+2 two-stage hot straightening mode. The first stage is hot straightening for 3 times at a temperature of 580-650°C; the second stage is hot straightening for 2 times at a temperature of 500-550°C. The second stage is hot straightening in the high temperature zone after the phase transformation of the steel plate is completed, and a flat steel plate is obtained with an unevenness of ≤10mm / 2m.

[0005] The invention has the following advantages: the invention can be used to produce high-carbon ultra-wide saw blade steel substrates with a thickness of 10-15 mm and a width of 4500-4800 mm, meeting the domestic demand for large diamond saw blade substrates. Optimized billet size design. The production is carried out using small billets with a specification of 180 mm × (1800-2270) mm, avoiding unfavorable factors such as high energy consumption of two-fire billeting, long production process, and easy cracking of high-carbon steel billets after billeting and fire cutting, and the production efficiency is high; the rolling process adopts a high-temperature hot rolling process, the rolling process is simple, and it is easy to mass produce; a two-stage hot straightening scheme designed for high-carbon saw blade steel: the first stage of hot straightening is carried out in the phase change temperature zone of the steel plate, and the second stage of hot straightening is carried out in the high temperature zone after the phase change of the steel plate is completed, which improves the deformation of the steel plate on the cooling bed due to the phase change structure stress using the ordinary hot straightening process, and improves the flatness level and stability of the steel plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a metallographic photograph of the saw blade steel in the rolled state (500×). DETAILED DESCRIPTION

[0007] The present invention is further described below with reference to the embodiments.

[0008] Embodiment 1~4: A method for manufacturing a steel substrate for an ultra-wide high-carbon saw blade, wherein the chemical composition mass percentage of the steel is shown in Table 1. The slab specifications, steel plate rolling process, hot straightening process and actual unevenness measurement are shown in Table 2.

[0009] Table 1 Composition of high carbon saw blade steel .

[0010] Table 2 Saw blade steel rolling and hot straightening process .

Claims

1. A method for manufacturing a steel substrate for an ultra-wide high-carbon saw blade, wherein the thickness of the produced steel plate is 10-15 mm and the width is 4500-4800 mm. The process route is hot metal pretreatment → converter smelting → LF furnace → RH vacuum treatment → continuous casting → heating → rolling → hot straightening → slitting → flaw detection → storage, and the method is characterized in that: The chemical composition of the steel is C=0.67%~0.76% by weight, Si=0.17%~0.37%, Mn=0.90%~1.20%, Cr=0.50%~0.70%, P≤0.020%, S≤0.003%, and the balance is Fe and unavoidable impurities; The key process steps include: (1) Billet specification design: Use small billets with a cross-section of (150~180) mm × (1800~2270) mm for production, and the billet length ensures that the length of the rolled large plate is ≤25m; (2) Rolling: After the billet is off the line, it is subjected to stack cooling and hydrogen expansion, and the stack cooling time is ≥8h; after stack cooling, it is rolled in a warm furnace, and the billet is heated to 1200~1280℃ for steel production; the rolling adopts hot rolling process, the rough rolling temperature is greater than 1150℃, the intermediate billet is 50~80mm, and the finishing rolling adopts hot rolling with a starting rolling temperature of ≥1050℃; (3) Hot straightening: The rolled steel plate is hot straightened for 5 times, using a 3+2 two-stage hot straightening mode. The first stage is hot straightening for 3 times at a temperature of 580-650°C; the second stage is hot straightening for 2 times at a temperature of 500-550°C. The second stage is hot straightening in the high temperature zone after the phase transformation of the steel plate is completed, and a flat steel plate is obtained with an unevenness of ≤10mm / 2m.

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