Steel hot-rolled wide strip for marble gang saws and method for manufacturing same

Abstract

The present application relates to the technical field of steel smelting material processing, in particular to marble gang saw steel hot-rolled wide steel strip and a preparation method thereof; the composition of the marble gang saw steel hot-rolled wide steel strip comprises, in terms of mass percentage, C: 0.66% to 0.70%, Cr: 0.12% to 0.25%, Ni: 0.52% to 0.70%, Mo: 0.20% to 0.40%, and Nb: 0.008% to 0.030%; Cr:Ni:Mo=1:(2-4):(1-2), 0.85<=Cr+Ni+Mo<=1.25; the marble gang saw steel hot-rolled wide steel strip has good wear resistance, strength, toughness, and a long service life, and can reduce the amount of precious metals to reduce costs; moreover, the wide steel strip is convenient for cutting, cold rolling, heat treatment and other processes during gang saw processing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting material processing, in particular to a marble gang saw steel hot-rolled wide steel strip and a preparation method thereof. BACKGROUND

[0002] In the processing of marble, it is usually necessary to use a gang saw to reciprocally pull saw cut the marble, so the saw blade used for cutting marble needs to have the characteristics of high strength, good toughness, good wear resistance, good fatigue resistance and long service life.

[0003] However, the related art uses 65Mn, 75Cr1, 75Ni8 and the like to make a saw blade for cutting marble, such steel strips have poor wear resistance, poor strength and toughness, are prone to breakage, have a low service life, and the use of 75Ni8 and the like also increases the cost due to the high amount of precious metals. The narrow steel strip itself has limited dimensions, and is not convenient for subsequent processing into a gang saw for subsequent processing such as blanking, cold rolling, heat treatment and the like. SUMMARY

[0004] The present application relates to the technical field of steel smelting material processing, in particular to a marble gang saw steel hot-rolled wide steel strip and a preparation method thereof.

[0005] The present application is implemented as follows:

[0006] In a first aspect, the present application provides a marble gang saw steel hot-rolled wide steel strip, comprising: the composition of the marble gang saw steel hot-rolled wide steel strip, comprising, in terms of mass percentage:

[0007] C: 0.66%~0.70%, Mn: 0.57%~0.70%, Si: 0.18%~0.35%, Cr: 0.12%~0.25%, Ni: 0.52%~0.70%, Mo: 0.20%~0.40%, Nb: 0.008%~0.030%, P≤0.020%, S≤0.010%, Alt: 0.010%~0.030%, the balance being Fe and unavoidable impurities; wherein,

[0008] Cr:Ni:Mo=1:(2-4):(1-2), 0.85≤Cr+Ni+Mo≤1.25;

[0009] The width of the marble gang saw steel hot-rolled wide steel strip is 800mm~1430mm.

[0010] In an alternative embodiment, the microstructure of the hot-rolled wide steel strip for marble gang sawing steel is 60-65% pearlite plus 35-40% ferrite.

[0011] In an alternative embodiment, Cr:Ni:Mo=1:3:1.5.

[0012] In a second aspect, the present application provides a method for preparing a hot-rolled wide steel strip for marble gang sawing steel according to any one of the preceding embodiments, comprising: converter smelting, LF refining, RH refining, slab continuous casting, heating, rolling, laminar cooling, coiling, and slow cooling pit slow cooling; wherein,

[0013] In the step of converter smelting, molten iron and scrap steel are used as raw materials, and top and bottom combined blowing oxygen converter is used for smelting; the smelting time is 35-50 min, and the tapping temperature is 1620-1680℃; the mass percentage content of C at the end of the molten steel is controlled to be ≤0.20%, and the mass percentage content of P is controlled to be ≤0.018%; silicon iron alloy, manganese iron alloy and aluminum iron alloy are added to the molten steel in the ladle for deoxidation when tapping;

[0014] In the step of LF refining, lime and pre-melted slag are added to the molten steel for slagging and desulfurization; nickel iron, molybdenum iron and chromium iron are added to the molten steel, and then niobium iron alloy is added to the molten steel; the outlet temperature is controlled to be 1600-1620℃;

[0015] In the step of slab continuous casting, the molten steel is cast into a slab with a thickness of 220-240mm by a slab continuous casting machine; the molten steel temperature in the tundish is controlled to be 1495-1530℃ during continuous casting, and the casting speed is controlled to be 0.80-1.30m / min.

[0016] In an alternative embodiment, in the step of RH refining, the molten steel after LF refining station refining is sent to the RH vacuum furnace for vacuum treatment for 35-45min, wherein the step of vacuum treatment includes dehydrogenation and inclusion removal treatment under the condition of vacuum degree ≤67Pa for 15-25min; when the composition of the molten steel reaches C: 0.66%-0.70%, Mn: 0.57%-0.70%, Si: 0.18%-0.35%, Cr: 0.12%-0.25%, Ni: 0.40%-0.70%, Mo: 0.20%-0.40%, Nb: 0.008%-0.030%, P≤0.020%, S≤0.010%, Alt: 0.010%-0.030%, calcium wire is fed at a standard of 1.2-1.5m / t steel, and soft argon blowing is performed for 10-20min.

[0017] In an optional embodiment, the heating step comprises: controlling the furnace entry temperature to be greater than or equal to 500 DEG C, and heating to 1190-1280 DEG C, and controlling the total heating time according to the length of the slab, wherein the total heating time = length of the slab x (0.7-1.0) min / mm.

[0018] In an optional embodiment, the cooling rate of the laminar cooling is 1.5-3.0 DEG C / s.

[0019] In an optional embodiment, the coiling temperature is 620-700 DEG C.

[0020] In an optional embodiment, in the rolling step, hot charging and hot charging are used, the heated slab is rolled using a hot continuous rolling mill, and the heating temperature of the slab is 1050-1120 DEG C, and the hot continuous rolling finishing temperature is 850 DEG C-920 DEG C.

[0021] In an optional embodiment, the same slab difference of the steel strip obtained in the rolling step is ≤60 µm.

[0022] The present application comprises the following beneficial effects:

[0023] The marble gang saw steel hot-rolled wide steel strip of the present application adopts a high-C low-Cr-Ni-Mo-Nb composition system, strictly controls the contents of Cr and the noble metals Ni and Mo, and reduces the amounts of Cr and the noble metals Ni and Mo, which is beneficial to reducing the cost; the composition of the marble gang saw steel hot-rolled wide steel strip is controlled to satisfy Cr:Ni:Mo=1:(2-4):(1-2) and 0.85≤Cr+Ni+Mo≤1.25, which can ensure that the solid solution strengthening, precipitation strengthening and fine-grain strengthening of the steel material achieve good effects, and in combination with the smelting, refining and continuous casting steps of the preparation method, the grain of the steel material is uniformly refined, so that the steel material has good processability and high strength and toughness, which is beneficial to improving the service life.

[0024] Moreover, the marble gang saw steel of the present application is a wide steel strip with a width of 800-1430 mm, which is convenient for being processed into a gang saw in subsequent processing, then being subjected to cold rolling, heat treatment and the like to prepare a gang saw of a corresponding specification, and ensures the convenience of subsequent gang saw processing and production. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0026] Figure 1Microstructure of the steel material after slow cooling in Example 4 of the present application Figure 1 ;

[0027] Figure 2 Microstructure of the steel material after slow cooling in Example 4 of the present application Figure 2 ;

[0028] Figure 3 Quenching microstructure obtained after cold rolling and heat treatment of the steel material in Example 4 of the present application

[0029] Figure 4 Tempering microstructure obtained after cold rolling and heat treatment of the steel material in Example 4 of the present application DETAILED DESCRIPTION

[0030] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not indicated in the embodiments, the conventional conditions or the conditions suggested by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not indicated, the conventional products that can be purchased in the market are adopted.

[0031] The present application provides a hot-rolled wide steel strip for marble gang saw, which comprises the following components in percentage by mass:

[0032] C: 0.66%~0.70% (for example: 0.66%, 0.67%, 0.68%, 0.69%, 0.70%, etc.), Mn: 0.57%~0.70% (for example: 0.57%, 0.58%, 0.60%, 0.62%, 0.64%, 0.66%, 0.68%, 0.70%, etc.), Si: 0.18%~0.35% (for example: 0.18%, 0.20%, 0.22%, 0.25%, 0.27%, 0.30%, 0.32%, 0.35%, etc.), Cr: 0.12%~0.25% (for example: 0.12%, 0.15%, 0.17%, 0.19%, 0.22%, 0.25%, etc.), Ni: 0.52%~0.70% (for example: 0.52%, 0.53%, 0.54%, 0.55%, 0.57%, 0.60%, 0.65%, 0.70%, etc.), Mo: 0.20%~0.40% (for example: 0.20%, 0.22%, 0.24%, 0.27%, 0.30%, 0.35%, 0.38%, 0.40%, etc.), Nb: 0.008%~0.030% (for example: 0.008%, 0.010%, 0.015%, 0.018%, 0.020%, 0.024%, 0.027%, 0.030%, etc.), P≤0.020% (for example: 0.020%, 0.018%, 0.015%, etc.), S≤0.010% (for example: 0.010%, 0.008%, 0.006%, etc.), Alt: 0.010%~0.030% (for example: 0.010%, 0.015%, 0.020%, 0.025%, 0.030%, etc.), the balance being Fe and unavoidable impurities; wherein, Cr:Ni:Mo=1:(2-4):(1-2), for example: 1:3:1.5, 1:2:1, 1:4:2, 1:3:2, etc., 0.85≤Cr+Ni+Mo≤1.25, for example: 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, etc., and the marble gang saw steel hot-rolled wide steel strip is a wide steel strip, with a width of 800-1430mm, for example: 800mm, 850mm, 900mm, 950mm, 1000mm, 1100mm, 1150mm, 1200mm, 1250mm, 1300mm, 1350mm, 1400mm, 1430mm, etc.

[0033] The marble gang saw steel hot-rolled wide steel strip of the present application adopts a high-C low-Cr-Ni-Mo-Nb composition system, strictly controls the content of Cr and the noble metals Ni and Mo, and reduces the amount of Cr and the noble metals Ni and Mo, which is beneficial to reduce the cost; the composition of the marble gang saw steel hot-rolled wide steel strip is controlled to meet Cr:Ni:Mo=1:(2-4):(1-2) and 0.85≤Cr+Ni+Mo≤1.25, which can ensure that the solid solution strengthening, precipitation strengthening and fine-grain strengthening of the steel reach good effects, and in combination with the smelting, refining, continuous casting and other steps of the preparation method, the grain of the steel is uniformly refined, so that the steel has good processability and high strength and toughness, which is beneficial to improve the service life.

[0034] Moreover, the marble gang saw steel of the present application is a wide steel strip with a width of 800-1430mm, which is convenient for being processed into a gang saw, then being subjected to slitting, cold rolling, heat treatment and the like to prepare a gang saw of a corresponding specification, and ensures the convenience of subsequent gang saw processing and production.

[0035] The present application adopts a high-C low-Cr-Ni-Mo-Nb composition system, mainly because:

[0036] (1) The price of C is relatively low, and the content of C is controlled to be relatively high (mass percentage of 0.66%-0.70%), which can effectively reduce the cost, and C is the most effective strengthening element, dissolving C into the matrix can play a solid solution strengthening effect, and can form cementite and various carbides in the steel to play a precipitation strengthening effect, further improving the strength of the steel. If the content of C is greater than 0.77%, it is a hypereutectoid steel, although the material hardness is high, but the plasticity and toughness will be poor.

[0037] (2) Si can improve the strength of the steel in the form of solid solution strengthening, and is also a deoxidizing element in the steel; if the content of Si is too high (greater than 0.35%), it will also reduce the plasticity and toughness of the steel and the weldability, and also increase the viscosity of the surface iron oxide scale of the steel blank after heating, which is easy to cause surface problems such as pitting on the surface of the steel plate.

[0038] (3) Mn is a weak carbide-forming element, which plays a role in deoxidation and eliminating the adverse effects of sulfur in smelting, and can also reduce the austenite transformation temperature and refine ferrite grains, which is beneficial to improve the strength and toughness of the steel. Manganese can also be dissolved in ferrite to play a solid solution strengthening effect, and with the increase of the content of Mn, the strength of the steel increases, but too high Mn (greater than 0.70%) will also reduce the toughness and weldability of the steel.

[0039] (4) Cr is an element that improves the hardenability of steel, mainly forming carbide Cr7C3 or Cr 23C6, can also form complex carbide with carbon, improve the hardness and wear resistance of steel, but too high Cr (more than 0.25%) can affect the weldability of steel.

[0040] (5) Ni is the element of expanding austenite zone, which is beneficial to improve the strength and toughness of steel and improve the corrosion resistance, but nickel is a precious metal, and high content will significantly increase the cost of steel strip, therefore, the content of nickel is controlled to be less than or equal to 0.70% in the application.

[0041] (6) Mo can effectively refine the grain, improve the strength and toughness of steel, Mo exists in the form of solid solution and carbide in steel, therefore, the steel containing Mo has the effect of solid solution strengthening and carbide dispersion strengthening. Molybdenum can also improve the hardenability, wear resistance and tempering stability of steel.

[0042] (7) Nb is a strong carbide and nitride forming element, which can strongly inhibit the growth of austenite grains, and a small amount of niobium can refine the grains and improve the strength and toughness, therefore, the content of Nb can be controlled in the range of 0.008% to 0.030%.

[0043] (8) Al is a main deoxidizing element, which can effectively reduce the oxygen content in steel, and aluminum in steel forms fine and dispersed AlN compounds with nitrogen element, which can hinder grain growth and refine grains, that is, Al can refine the grains of steel. If the content of aluminum is too high (more than 0.030%), alumina inclusions will be formed, which will affect the fatigue performance of steel.

[0044] (9) The upper limit of impurity elements in steel is controlled as P≤0.020%, S≤0.010%, which can improve the purity of steel and improve the plasticity and toughness of steel.

[0045] On the basis of the above, under the control of Cr:Ni:Mo=1:(2-4):(1-2), 0.85≤Cr+Ni+Mo≤1.25, the solid solution strengthening, precipitation strengthening and fine grain strengthening of the steel can achieve good effect, and the strength, toughness and service life of the steel can be ensured.

[0046] Further, the microstructure of the marble gang saw steel hot-rolled wide steel strip is 60-65% pearlite and 35-40% ferrite. In this way, the good subsequent processing performance of the marble gang saw steel hot-rolled wide steel strip can be ensured.

[0047] The application also provides a preparation method of the marble gang saw steel hot-rolled wide steel strip, which comprises converter smelting, LF refining, RH refining, slab continuous casting, heating, rolling, laminar flow cooling, coiling, and slow cooling pit slow cooling.

[0048] Converter smelting: taking molten iron and scrap steel as raw materials, using top and bottom combined blowing oxygen converter for smelting, smelting time 35-50 min (for example: 35 min, 40 min, 45 min, 50 min, etc.), tapping temperature 1620-1680℃ (for example: 1620℃, 1630℃, 1640℃, 1650℃, 1660℃, 1670℃, 1680℃, etc.); control the mass content of C in the molten steel ≤0.20%, the mass content of P ≤0.018%; add ferrosilicon, ferromanganese, ferroaluminum to the molten steel in the ladle for deoxidation when tapping, so that the mass percentage content of silicon, manganese and aluminum in the molten steel is close to or equal to the content of finished steel.

[0049] It should be noted that the ferro-nickel, ferro-molybdenum, ferro-chromium and ferro-niobium alloy are added in the LF refining.

[0050] LF refining: the molten steel from the converter smelting is sent to the LF refining station for refining, and lime and pre-melted slag are added to the molten steel for desulfurization; adding raw materials and alloys such as ferro-nickel, ferro-molybdenum and ferro-chromium to the ladle to further adjust the mass percentage content of C, Si, Mn, Cr, Ni, Mo, Al elements in the molten steel, and after adjusting each alloy element and impurity element sulfur in place, adding ferro-niobium alloy to the molten steel, adjusting the temperature to 1600-1620℃ (for example: 1600℃, 1605℃, 1610℃, 1615℃, 1620℃, etc.) and leaving the station.

[0051] RH refining: the molten steel after refining in the LF refining station is sent to the RH vacuum furnace for vacuum treatment for 35-45 min (for example: 35 min, 38 min, 40 min, 42 min, 45 min, etc.), wherein the steps of vacuum treatment include dehydrogenation and inclusion removal treatment under a vacuum degree ≤67 Pa (for example: 67 Pa, 65 Pa, 63 Pa, 60 Pa, etc.) for 15-25 min (for example: 15 min, 18 min, 20 min, 22 min, 25 min, etc.); when the composition of the molten steel reaches: C 0.66%-0.70%, Mn 0.57%-0.70%, Si 0.18%-0.35%, Cr 0.12%-0.25%, Ni 0.40%-0.70%, Mo 0.20%-0.40%, Nb 0.008%-0.020%, P ≤0.020%, S ≤0.010%, Alt 0.010%-0.030%, according to the standard of 1.2-1.5 meters per ton of steel, calcium wire is fed, soft argon blowing time is 10-20 minutes (for example: 10 min, 12 min, 15 min, 17 min, 20 min, etc.), and the RH vacuum furnace refining is completed, and the molten steel is sent to the continuous casting workshop for continuous casting.

[0052] Slab continuous casting: the molten steel is cast into a slab with a thickness of 220-240 mm (for example: 220 mm, 225 mm, 230 mm, 235 mm, 240 mm, etc.) by a slab continuous casting machine, in order to prevent center segregation of the cast slab and to have good flowability of the molten steel, the molten steel temperature in the tundish is controlled at 1495-1530°C (for example: 1495°C, 1500°C, 1510°C, 1515°C, 1520°C, 1525°C, 1530°C, etc.) during continuous casting, if the tundish temperature is low, the flowability is poor, and if the temperature is high, segregation will occur; the normal casting speed is 0.80-1.30 m / min (for example: 0.80 m / min, 0.90 m / min, 1.00 m / min, 1.10 m / min, 1.15 m / min, 1.20 m / min, etc.), and after the slab exits the horizontal section of the continuous casting machine, it is cut into a prescribed length of billet by flame cutting.

[0053] Heating: in order to prevent low-temperature heating fracture of the cast slab, save energy, and ensure uniform heating temperature of the cast slab, the hot charging and hot feeding process is used to send the slab into the heating furnace for heating, the entry temperature of the slab into the heating furnace is greater than or equal to 500°C (for example: 500°C, 505°C, 510°C, 515°C, 520°C, 600°C, 700°C, etc.), the slab is heated to 1190-1280°C (for example: 1190°C, 1195°C, 1200°C, 1220°C, 1240°C, 1260°C, 1280°C, etc.), and the total heating time is controlled at 0.7-1.0 minutes / mm, that is, the total heating time is controlled according to the length of the slab, wherein the total heating time = length of the slab x (0.7-1.0) minutes / mm. For example, if the length of the slab is 1000 mm, the total heating time is 1000 mm x (0.7-1.0) minutes / mm = 700-1000 minutes.

[0054] Rolling: the heated slab is controlled by using a hot continuous rolling mill, the heating temperature of the slab is 1050-1120°C (for example: 1050°C, 1080°C, 1100°C, 1120°C, etc.), and the slab is coiled into a steel strip, and the final rolling temperature range of the hot continuous rolling is 850-920°C, for example: 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, etc.

[0055] The steel strip after finish rolling is subjected to laminar flow water cooling, and the cooling rate is controlled at 1.5-3.0 ℃ / s, for example, 1.5 ℃ / s, 1.8 ℃ / s, 2.0 ℃ / s, 2.2 ℃ / s, 2.5 ℃ / s, 2.7 ℃ / s, 3.0 ℃ / s, etc., to prevent the steel strip from being broken due to too fast cooling rate and to generate martensite, and then the steel strip is coiled into a coil, and if the cooling rate is too slow, the grain refinement is not good; the coiling temperature is controlled at 620-700 ℃, for example, 620 ℃, 630 ℃, 640 ℃, 650 ℃, 660 ℃, 670 ℃, 680 ℃, 690 ℃, 700 ℃, etc., to ensure that the steel strip obtains fine lamellar pearlite and a small amount of ferrite, and the coil is quickly sent to a slow cooling pit for slow cooling (i.e. natural cooling in the slow cooling pit), to ensure that the hardness of the steel strip is uniform, the stress is eliminated, and the subsequent processing is facilitated.

[0056] The high-C and low-Cr-Ni-Mo-Nb component system is adopted, chromium, nickel, molybdenum and niobium are used as alloying elements, Cr:Ni:Mo is cooperatively controlled at 1:(2-4):(1-2), 0.85≤Cr+Ni+Mo≤1.25, the solid solution strengthening, precipitation strengthening and fine-grain strengthening mechanisms are fully utilized, and the grain of the steel strip is uniformly refined under the cooperative and reasonable controlled rolling and controlled cooling process, so that the microstructure of the steel is 60-65% pearlite and 35-40% ferrite, the steel has good subsequent processing performance, and the prepared hot-rolled steel strip has high strength and toughness after cold rolling, quenching and tempering heat treatment, and the service life is prolonged.

[0057] The marble gang saw steel hot-rolled wide steel strip is produced by using a hot continuous rolling mill and is made by using a hot feeding, hot charging, controlled rolling, air cooling and pit slow cooling integrated process. Compared with a narrow steel strip, the steel strip has a thickness precision of ±0.10 mm, a same plate difference small convexity of ≤60 µm, good surface quality, a small decarburization layer, uniform head and tail performance, and a width of 800 mm to 1430 mm. In subsequent processing, the steel strip can be processed into various width specifications required by gang saws through slitting, cold rolling and heat treatment, production is convenient, raw material inventory is reduced, and the requirements of users for conveniently producing gang saws by using the marble gang saw steel hot-rolled wide steel strip are met.

[0058] The application will be further described in detail in combination with examples.

[0059] Example 1

[0060] In a 210t converter-1580mm hot continuous rolling mill production line:

[0061] (1) Converter smelting process: 203 tons of molten iron and 27 tons of scrap steel are charged into a 210 tons top and bottom combined blowing oxygen converter for smelting, the smelting time is 38 min, and the tapping temperature is 1636℃; the final point carbon content of the molten steel is 0.13%, and the phosphorus content is 0.012%. Silicon iron, manganese iron, and aluminum iron are added to the ladle molten steel for deoxidization and alloying.

[0062] (2) LF+RH refining process: the initial molten steel is adjusted in composition and temperature at the ladle (LF) refining station, lime and pre-melted slag are added to the molten steel for desulfurization, and nickel iron, molybdenum iron, chromium iron, and niobium iron alloy are added to the molten steel, and the temperature is adjusted to 1605℃ to exit the station. The molten steel is then treated in a RH vacuum furnace for 38 min, including 15 min at a vacuum degree of 67 Pa; when the composition of the molten steel reaches the required value, 285 m of calcium wire is fed, and the soft argon blowing time is 13 minutes, and the refining is completed.

[0063] (3) Slab continuous casting process: the molten steel is sent to the continuous casting workshop to be continuously cast into a slab with a thickness of 230 mm, and the tundish temperature is 1500℃. Sampling and testing show that the composition of the slab is as follows: C: 0.67%, Mn: 0.58%, Si: 0.21%, Cr: 0.17%, Ni: 0.52%, Mo: 0.26%, Nb: 0.014%, P: 0.014%, S: 0.005%, Alt: 0.017%, and the balance is iron Fe and unavoidable impurity elements.

[0064] (4) Heating process: the slab enters the heating furnace at an entry temperature of 500℃; the slab is heated to 1230℃, and the total heating time is controlled at 185 min.

[0065] (5) Rolling process: the target thickness of the steel strip is 2.75 mm, and the width is 850 mm, the heated slab is controlled by using a 1580 hot continuous rolling mill, the size accuracy control is as follows: thickness allowable deviation +0.10~ -0.10 mm, width allowable deviation 0~ +20 mm, and the steel strip is coiled. The average temperature of the hot continuous rolling final rolling is 915℃, and the average temperature of the coiling is 685℃.

[0066] (6) Post-rolling cooling process: after coiling, the coil is quickly unloaded and slowly cooled in the slow cooling pit.

[0067] Example 2

[0068] Production on a 210 t converter-1580 mm hot continuous rolling mill production line.

[0069] (1) Converter smelting process: 201 tons of molten iron and 29 tons of scrap steel are used as raw materials and charged into a 210-ton top and bottom combined blowing oxygen converter for smelting, the smelting time is 36 min, and the tapping temperature is 1645℃; the final carbon content of the molten steel is 0.120%, and the phosphorus content is 0.015%. Silicon iron, manganese iron, and aluminum iron are added to the ladle molten steel during tapping for deoxidization and alloying.

[0070] (2) LF+RH refining process: The initial molten steel is adjusted in composition and temperature at the ladle (LF) refining station, lime and pre-melted slag are added to the molten steel for desulfurization, and nickel iron, molybdenum iron, chromium iron, and niobium iron alloy are added to the molten steel, and the temperature is adjusted to 1610℃ to exit the station. The molten steel is then treated in a RH vacuum furnace for 37 min, including 25 min at a vacuum degree of 66 Pa; when the composition of the molten steel meets the requirements, 280 m of calcium wire is fed, and soft argon blowing is performed for 12 minutes, and the refining is completed.

[0071] (3) Slab continuous casting process: The molten steel is sent to the continuous casting workshop to be continuously cast into a slab with a thickness of 220mm, and the tundish temperature is 1525℃. Sampling and testing show that the composition of the slab is as follows: C: 0.66%, Mn: 0.62%, Si: 0.22%, Cr: 0.18%, Ni: 0.54%, Mo: 0.27%, Nb: 0.015%, P: 0.016%, S: 0.006%, Alt: 0.015%, and the balance is iron Fe and unavoidable impurity elements.

[0072] (4) Heating process: The slab enters the heating furnace at an entry temperature of 520℃; the slab is heated to 1225℃, and the total heating time is controlled at 180 minutes.

[0073] (5) Rolling process: The target thickness of the steel strip is 3.0mm, and the width is 1150mm. The heated slab is controlled by using a 1580 hot continuous rolling mill, and the size accuracy control is as follows: thickness allowable deviation +0.10~-0.10mm, width allowable deviation 0~+20mm, and coiling into a steel strip. The average temperature of the hot continuous rolling final rolling is 910℃, and the average temperature of the coiling is 672℃.

[0074] (6) Post-rolling cooling process: After coiling, the coil is quickly unloaded and slowly cooled in the slow cooling pit.

[0075] Example 3

[0076] Produced on a 210t converter-1580mm hot continuous rolling mill production line.

[0077] (1) Converter smelting process: 205 tons of molten iron and 25 tons of scrap steel are used as raw materials and charged into a 210-ton top and bottom combined blowing oxygen converter for smelting, the smelting time is 38 min, and the tapping temperature is 1632℃; the final carbon content of the molten steel is 0.140%, and the phosphorus content is 0.013%. Silicon iron, manganese iron, and aluminum iron are added to the ladle molten steel during tapping for deoxidization and alloying.

[0078] (2) LF+RH refining process: The initial molten steel is adjusted in composition and temperature at the ladle (LF) refining station, lime and pre-melted slag are added to the molten steel for desulfurization, and nickel iron, molybdenum iron, chromium iron, and niobium iron alloy are added to the molten steel, and the temperature is adjusted to 1612℃ to exit the station. The molten steel is then treated in a RH vacuum furnace for 36 min, including 20 min at a vacuum degree of 65 Pa; when the composition of the molten steel meets the requirements, calcium wire is fed for 290 m, and soft argon blowing is performed for 14 minutes, and the refining is completed.

[0079] (3) Slab continuous casting process: The molten steel is sent to the continuous casting workshop to be continuously cast into a slab with a thickness of 240mm, and the tundish temperature is 1515℃. Sampling and testing show that the composition of the slab is as follows: C: 0.68%, Mn: 0.58%, Si: 0.23%, Cr: 0.20%, Ni: 0.60%, Mo: 0.30%, Nb: 0.016%, P: 0.015%, S: 0.004%, Alt: 0.014%, and the balance is iron Fe and unavoidable impurity elements.

[0080] (4) Heating process: The slab enters the heating furnace at an entry temperature of 600℃; the slab is heated to 1215℃, and the total heating time is controlled at 192 minutes.

[0081] (5) Rolling process: The target thickness of the steel strip is 3.5mm, and the width is 1250mm, the heated slab is controlled by using a 1580 hot continuous rolling mill, the size accuracy control is as follows: thickness allowable deviation +0.10~ -0.10mm, width allowable deviation 0~ +20mm, and the steel strip is coiled. The average temperature of the hot continuous rolling final rolling is 895℃, and the average temperature of the coiling is 655℃.

[0082] (6) Post-rolling cooling process: After coiling, the coil is quickly unloaded and slowly cooled in the slow cooling pit.

[0083] Example 4

[0084] Produced on a 210t converter-1580mm hot continuous rolling mill production line.

[0085] (1) Converter smelting process: 202 tons of molten iron and 28 tons of scrap steel are used as raw materials and charged into a 210 tons top and bottom combined blowing oxygen converter for smelting, the smelting time is 40 min, and the tapping temperature is 1625℃; the final carbon content of the molten steel is 0.150%, and the phosphorus content is 0.011%. Silicon iron, manganese iron, and aluminum iron are added to the ladle molten steel during tapping for deoxidization and alloying.

[0086] (2) LF+RH refining process: The initial molten steel is adjusted in composition and temperature at the ladle (LF) refining station, lime and pre-melted slag are added to the molten steel for desulfurization, and nickel iron, molybdenum iron, chromium iron, and niobium iron alloy are added to the molten steel, and the temperature is adjusted to 1615℃ to exit the station. The molten steel is then treated in a RH vacuum furnace for 40 min, including 18 min under a vacuum of 67 Pa; when the composition of the molten steel reaches the required value, calcium wire is fed for 302 m, and soft argon blowing is performed for 14 minutes, and the refining is completed.

[0087] (3) Slab continuous casting process: The molten steel is sent to the continuous casting workshop for continuous casting into a slab with a thickness of 230 mm, and the tundish temperature is 1505℃. Sampling and testing show that the composition of the slab is as follows: C: 0.69%, Mn: 0.59%, Si: 0.20%, Cr: 0.18%, Ni: 0.54%, Mo: 0.27%, Nb: 0.017%, P: 0.013%, S: 0.003%, Alt: 0.018%, and the balance is iron Fe and unavoidable impurity elements.

[0088] (4) Heating process: The entry temperature of the slab into the heating furnace is 505℃; the slab is heated to 1210℃, and the total heating time is controlled at 192 minutes.

[0089] (5) Rolling process: The target thickness of the steel strip is 4.5 mm, and the width is 1350 mm, the heated slab is controlled by using a 1580 hot continuous rolling mill, the size accuracy control is as follows: thickness allowable deviation +0.10~-0.10 mm, width allowable deviation 0~+20 mm, and the steel strip is coiled. The average temperature of the hot continuous rolling finish rolling is 885℃, and the average temperature of the coiling is 635℃.

[0090] (6) Post-rolling cooling process: After coiling, the coil is quickly unloaded and slowly cooled in the slow cooling pit.

[0091] Comparative Example 1

[0092] Comparative Example 1 is similar to Example 1, except that Cr: 0.12%, Ni: 0.7%, Mo: 0.4%, Cr:Ni:Mo=1:5.83:3.33, Cr+Ni+Mo=1.22; the remaining process parameters refer to Example 1.

[0093] Comparative Example 2

[0094] Comparative Example 2 is similar to Example 1, except that Cr: 0.25%, Ni: 0.4%, Mo: 0.2%, Cr:Ni:Mo = 1:1.6:0.8, Cr+Ni+Mo = 0.85; the rest of the process parameters refer to Example 1.

[0095] Comparative Example 3

[0096] Comparative Example 3 is similar to Example 1, except that Cr: 0.30%, Ni: 0.9%, Mo: 0.45%, Cr:Ni:Mo = 1:3:1.5, Cr+Ni+Mo = 1.65; the rest of the process parameters refer to Example 1.

[0097] Comparative Example 4

[0098] Comparative Example 4 is similar to Example 1, except that the smelting time is 30 min, the tapping temperature is 1600℃; the LF refining outstation temperature is 1580℃; the RH vacuum treatment time is 20 min; the continuous casting tundish molten steel temperature is 1550℃, the continuous casting casting speed is 0.75 m / min; the heating into the furnace temperature is 400℃, heated to 1100℃; the laminar cooling rate is 1℃ / s; the coiling temperature is 750℃; the hot continuous rolling finishing temperature is 1000℃; the rest of the process parameters refer to Example 1.

[0099] Comparative Example 5

[0100] Comparative Example 5 is similar to Example 1, except that the smelting time is 60 min, the tapping temperature is 1700℃; the LF refining outstation temperature is 1600℃; the RH vacuum treatment time is 55 min; the continuous casting tundish molten steel temperature is 1480℃, the continuous casting casting speed is 1.5 m / min; the heating into the furnace temperature is 450℃, heated to 1300℃; the laminar cooling rate is 3.5℃ / s; the coiling temperature is 580℃; the hot continuous rolling finishing temperature is 800℃; the rest of the process parameters refer to Example 1.

[0101] Comparative Example 6

[0102] Comparative Example 6 is similar to Example 1, except that Cr: 0.12%, Ni: 0.7%, Mo: 0.4%, Cr:Ni:Mo = 1:5.83:3.33, Cr+Ni+Mo = 1.22; the smelting time is 30 min, the tapping temperature is 1600℃; the LF refining outstation temperature is 1630℃; the RH vacuum treatment time is 20 min; the continuous casting tundish molten steel temperature is 1540℃, the continuous casting casting speed is 1.5 m / min; the heating into the furnace temperature is 400℃, heated to 1100℃; the laminar cooling rate is 1℃ / s; the coiling temperature is 750℃; the hot continuous rolling finishing temperature is 1000℃; the rest of the process parameters refer to Example 1.

[0103] The samples of each embodiment and the comparative example were taken, and the organization and mechanical properties were tested, and the test results are shown in Table 1.

[0104] Table 1 Mechanical properties and organization of hot-rolled strip steel

[0105]

[0106] According to Table 1, Figure 1 and Figure 2 It can be known that the grain of the steel material of Example 4 is uniformly refined, and the steel material has good strength and toughness.

[0107] The steel materials of each embodiment and the comparative example 1 were tested after cold rolling, quenching and tempering, and the results are shown in Table 2.

[0108] Table 2 Test results of properties and organization of strip steel after heat treatment

[0109]

[0110] According to Table 2, Figure 3 and Figure 4 It can be known that the steel material of Example 4 has good quenching and tempering properties.

[0111] In summary, the hot-rolled wide steel strip for marble gang saw of the application adopts a high-C low-Cr-Ni-Mo-Nb composition system, strictly controls the content of Cr and noble metals Ni and Mo, and reduces the amount of Cr and noble metals Ni and Mo, which is beneficial to reduce the cost; the composition of the hot-rolled wide steel strip for marble gang saw is controlled to meet Cr:Ni:Mo=1:(2-4):(1-2) and 0.85≤Cr+Ni+Mo≤1.25, which can ensure that the solid solution strengthening, precipitation strengthening and fine-grain strengthening of the steel material achieve good results, and in combination with the smelting, refining and continuous casting steps of the preparation method, the grain of the steel material is uniformly refined, so that the steel material has good processing performance and high strength and toughness, which is beneficial to improve the service life.

[0112] Moreover, the hot-rolled steel strip for marble gang saw of the application is a wide steel strip with a width of 800-1430mm, which is convenient for strip processing when subsequent gang saw processing, and then cold rolling, heat treatment and the like are performed to prepare a gang saw of a corresponding specification, so that the subsequent gang saw processing and production convenience is ensured.

[0113] The above only describes the preferred embodiments of the application and is not used to limit the application, and the application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A hot-rolled wide steel strip for marble gang saws, characterized by, The application relates to a marble gang saw steel hot-rolled wide steel strip. The composition of the marble gang saw steel hot-rolled wide steel strip comprises the following components in percentage by mass: C: 0.66%-0.70%, Mn: 0.57%-0.70%, Si: 0.18%-0.35%, Cr: 0.12%-0.25%, Ni: 0.52%-0.70%, Mo: 0.20%-0.40%, Nb: 0.008%-0.030%, P<=0.020%, S<=0.010%, Alt: 0.010%-0.030%, and the balance of Fe and inevitable impurities; wherein, Cr:Ni:Mo=1:(2-4):(1-2), 0.85<=Cr+Ni+Mo<=1.25; The width of the marble gang saw steel hot-rolled wide steel strip is 800mm-1430mm.

2. The steel hot-rolled wide strip for marble gang sawing according to claim 1, characterized in that, The structure of the marble gang saw steel hot-rolled wide steel strip is 60-65% pearlite plus 35-40% ferrite.

3. The steel hot-rolled wide strip for marble gang sawing according to claim 1, characterized in that, Cr:Ni:Mo=1:3:1.

5.

4. A method for the production of a hot-rolled wide strip of steel for marble gang saws according to any one of claims 1-3, characterized in that, The application also relates to a preparation method of the marble gang saw steel hot-rolled wide steel strip. The converter smelting, LF refining, RH refining, slab continuous casting, heating, rolling, laminar cooling, coiling, and slow cooling pit slow cooling are included; wherein, In the step of the converter smelting, molten iron and scrap steel are used as raw materials, and top and bottom combined blowing oxygen converter is used for smelting; the smelting time is 35-50min, and the tapping temperature is 1620-1680 DEG C; the mass percentage content of the end-point C of the molten steel is controlled to be <=0.20%, and the mass percentage content of P is <=0.018%; when tapping, silicon-iron alloy, manganese-iron alloy and aluminum-iron alloy are added into the ladle molten steel for deoxidation; In the step of the LF refining, lime and premelted slag are added into the molten steel for slagging and desulfurization; nickel-iron, molybdenum-iron and chromium-iron are added into the molten steel, and then niobium-iron alloy is added into the molten steel; the outgoing temperature is controlled to be 1600-1620 DEG C; In the step of the slab continuous casting, the molten steel is cast into a slab with a thickness of 220-240mm through a slab continuous casting machine; the molten steel temperature in the tundish is controlled to be 1495-1530 DEG C during continuous casting, and the continuous casting speed is controlled to be 0.80-1.30m / min.

5. The method of claim 4, wherein the steel hot-rolled wide strip for marble gang sawing is characterized by, The step of the heating comprises the following steps: the furnace entry temperature is greater than or equal to 500 DEG C, and the heating temperature is 1190-1280 DEG C, and the total heating time is controlled according to the length of the slab, wherein the total heating time = the length of the slab x (0.7-1.0) min / mm.

6. The method of claim 4, wherein the steel hot-rolled wide strip for marble gang sawing is characterized by, The cooling rate of the laminar cooling is 1.5-3.0 DEG C / s.

7. The method of claim 4, wherein the steel hot-rolled wide strip for marble gang sawing is characterized by, The coiling temperature is 620-700 DEG C.

8. The method of claim 4, wherein the steel hot-rolled wide strip for marble gang sawing is characterized by, In the step of the rolling, hot charging and hot charging are used, the heated slab is rolled by using a hot continuous rolling mill, the heating temperature of the slab is 1050-1120 DEG C, and the hot continuous rolling final rolling temperature is 850 DEG C-920 DEG C.

9. The method of claim 8, wherein the steel hot-rolled wide strip for marble gang sawing is characterized by, The same slab difference of the steel strip obtained in the step of the rolling is <=60mu m.

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