Steel for grinding balls and method for producing same

Abstract

The application provides a kind of steel for grinding ball and its preparation method, the steel for grinding ball includes: C 0.72-0.82wt%, Si 0.17-0.37wt%, Mn 0.70-1.00wt%, Cr 0.50-0.90wt%, Cu≤0.25wt%, Ni≤0.25wt%, A1≤0.06wt%, V 0.05-0.10wt%, the balance is Fe and inevitable impurities.By adjusting the carbon, manganese, chromium components, collocation vanadium and other elements content synergies, narrow component and residual element control, reduce component segregation, while optimizing LF refining process and combining whole process protection pouring process, and regulation cast blank process parameters, improve the hardenability and wear resistance, the surface hardness of the prepared steel for grinding ball and the difference between the core hardness value is ≤3HRC, and the impact toughness is improved, and the ball consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steelmaking, and particularly relates to a steel for grinding balls and a preparation method thereof. BACKGROUND

[0002] Abrasion-resistant steel is a kind of alloy steel widely used in various wear conditions, and is an abrasion-resistant medium applied to industries such as mining, cement, smelting and power generation. Through continuous impact, the ore is ground into powder, and then used for production. Abrasion is one of the main damage forms of metal materials. In China, nearly 3 million tons of grinding balls are lost every year. Therefore, it is of great significance to study high-performance abrasion-resistant steel.

[0003] CN110541055A discloses a production method of HB450 grade non-quenched high-strength abrasion-resistant steel for track plates, the high-strength abrasion-resistant steel contains the following mass percentage of chemical components: C: 0.22-0.27%; Si: ≤0.30%; Mn: 3.0-5.0%; P: ≤0.012%; S: ≤0.002%; Mo: 0.10-0.50%; Ti: 0.10-0.15%; B: 0.0010-0.0040%; N ≤0.0040%, the rest is Fe and inevitable impurities; the method takes the above high-strength abrasion-resistant steel as the implementation object, and produces the steel plate through a BOF converter smelting + LF furnace external refining + RH treatment + slab continuous casting + controlled rolling process. Although the abrasion-resistant steel prepared by the above method has large hardness, the hardenability, surface hardness and core hardness difference of the steel still need to be improved.

[0004] CN111500918A discloses a production method of an abrasion-resistant steel plate, the chemical composition of the steel plate is as follows: C=0.19-0.25, Si=0.9-1.2, Mn=0.7-1.50, P≤0.020, S≤0.005, Ti=0.070-0.20, B=0.0008-0.0025, Ni=0.15-0.50, the balance is Fe and inevitable impurities; the process route is: molten iron desulfurization→converter smelting→refining→vacuum treatment→continuous casting→rolling→quenching→tempering. By reducing the alloy content in the abrasion-resistant steel composition, increasing the percentage content of Si, adding a small amount of Ni element, selecting a suitable oxide smelting process, a suitable rolling process and different tempering processes, and a flexible production technology, different grades of 6-30mm abrasion-resistant steel plates with low cost, good low-temperature impact toughness, high welding efficiency, plasticity and toughness are produced. The process also needs tempering, the operation is complex, and the hardenability, surface hardness and core hardness difference of the steel plate still need to be improved.

[0005] Therefore, in view of the problems in the prior art, a steel for grinding balls with high hardenability, small surface hardness and core hardness difference and reduced ball consumption is provided. SUMMARY

[0006] The application aims to provide a steel for grinding ball and a preparation method thereof, by adjusting the contents of carbon, manganese and chromium, matching the contents of vanadium and other elements, optimizing the process parameters, the surface hardness and the core hardness of the steel for grinding ball are less than 3HRC, the impact toughness is improved, the ball consumption is reduced, the content of gas and inclusions in the steel for grinding ball is reduced, and the purity of the steel for grinding ball is improved.

[0007] To achieve the application, the application adopts the following technical scheme:

[0008] In the first aspect, the application provides a steel for grinding ball, which comprises, in mass percentage: C 0.72-0.82wt%, Si 0.17-0.37wt%, Mn 0.70-1.00wt%, Cr 0.50-0.90wt%, Cu≤0.25wt%, Ni≤0.25wt%, Al≤0.06wt%, V 0.05-0.10wt%, and the balance of Fe and inevitable impurities.

[0009] The steel for grinding ball provided by the application can improve the hardenability of the steel, reduce the difference between the surface hardness and the core hardness of the steel, and improve the impact toughness and the wear resistance of the steel.

[0010] In the present application, the mass percentage of C in the steel for grinding balls is 0.72-0.82wt%, for example, it can be 0.73wt%, 0.74wt%, 0.75wt%, 0.76wt%, 0.77wt%, 0.78wt%, 0.79wt%, 0.80wt% or 0.81wt% and the like, the mass percentage of Si in the steel for grinding balls is 0.17-0.37wt%, for example, it can be 0.19wt%, 0.20wt%, 0.22wt%, 0.24wt%, 0.26wt%, 0.28wt%, 0.30wt%, 0.32wt%, 0.34wt% or 0.35wt% and the like, the mass percentage of Mn in the steel for grinding balls is 0.70-1.00wt%, for example, it can be 0.75wt%, 0.80wt%, 0.85wt%, 0.90wt% or 0.95wt% and the like, the mass percentage of Cr in the steel for grinding balls is 0.50-0.90wt%, for example, it can be 0.55wt%, 0.60wt%, 0.65wt%, 0.70wt%, 0.75wt%, 0.80wt% or 0.85wt% and the like, the mass percentage of Cu in the steel for grinding balls is ≤0.25wt%, for example, it can be 0.23wt%, 0.20wt%, 0.18wt%, 0.15wt%, 0.12wt% or 0.10wt% and the like, the mass percentage of Ni in the steel for grinding balls is ≤0.25wt%, for example, it can be 0.23wt%, 0.20wt%, 0.18wt%, 0.15wt%, 0.12wt% or 0.10wt% and the like, the mass percentage of Al in the steel for grinding balls is ≤0.06wt%, for example, it can be 0.05wt%, 0.04wt%, 0.03wt%, 0.02wt% or 0.01wt% and the like, the mass percentage of V in the steel for grinding balls is 0.05-0.10wt%, for example, it can be 0.055wt%, 0.06wt%, 0.065wt%, 0.07wt%, 0.08wt% or 0.09wt% and the like, but not limited to the listed values, other values not listed in the value range are also applicable.

[0011] As a preferred technical solution of the present application, the mass percentage of V in the steel for grinding balls is 0.07-0.08wt%, for example, it can be 0.071wt%, 0.072wt%, 0.073wt%, 0.074wt%, 0.075wt%, 0.076wt%, 0.077wt%, 0.078wt% or 0.079wt% and the like, but not limited to the listed values, other values not listed in the value range are also applicable.

[0012] In the present application, the addition of V element can refine the grain size and improve the impact toughness.

[0013] Preferably, the total mass percentage content of Mn+Cr in the steel for the grinding ball is 1.75-1.85wt%, for example, it can be 1.76wt%, 1.77wt%, 1.78wt%, 1.79wt%, 1.80wt%, 1.81wt%, 1.82wt%, 1.83wt% or 1.84wt%, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0014] In the present application, by reasonably matching the components of manganese and chromium, the hardenability and wear resistance can be improved, and by narrow component control, the component segregation is reduced, so that the surface hardness and the core hardness difference of the steel are small.

[0015] As a preferred technical solution of the present application, in the unavoidable impurities, the mass percentage content of P is ≤0.035wt%, and the mass percentage content of S is ≤0.035wt%, preferably, the mass percentage content of P is ≤0.015wt%, and the mass percentage content of S is ≤0.003wt%.

[0016] In the present application, the mass percentage content of P in the unavoidable impurities is ≤0.035wt%, for example, it can be 0.030wt%, 0.025wt%, 0.020wt%, 0.015wt%, 0.010wt% or 0.005wt%, etc., but not limited to the listed values, and other values not listed in the value range are also applicable, and preferably, the mass percentage content of P is ≤0.015wt%.

[0017] In the present application, the mass percentage content of S in the unavoidable impurities is ≤0.035wt%, for example, it can be 0.030wt%, 0.025wt%, 0.020wt%, 0.015wt%, 0.010wt%, 0.005wt%, 0.002wt% or 0.001wt%, etc., but not limited to the listed values, and other values not listed in the value range are also applicable, and preferably, the mass percentage content of S is ≤0.003wt%.

[0018] As a preferred technical solution of the present application, the difference between the surface hardness value and the core hardness value of the steel for the grinding ball is ≤3HRC, for example, it can be 3HRC, 2.5HRC, 2HRC, 1.5HRC or 0.5HRC, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0019] Preferably, the impact energy of the steel for the grinding ball is ≥15J, for example, it can be 15J, 16J, 17J, 18J, 19J or 20J, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0020] Preferably, the ball consumption of the steel for the grinding ball is ≤0.5kg.

[0021] Preferably, the inclusions of the steel for the grinding ball are A class ≤ 1.5 level, B class ≤ 1.0 level, C class ≤ 0 level, and D class ≤ 1.0 level.

[0022] The present application makes the hardness distribution more uniform by studying the micro-alloying technology, according to the corresponding relationship between carbon element and hardness, and the influence of different contents of manganese and chromium alloying elements on hardenability, refines the grain structure by adding trace V element, improves the impact toughness, and controls the proportion of the content of each oxide in the final slag in LF refining, so that the inclusions content of the steel for the grinding ball is low.

[0023] In a second aspect, the present application provides a preparation method of the steel for the grinding ball of the first aspect, which comprises: formula amount of blast furnace molten iron is sequentially subjected to converter smelting, deoxidation alloying, LF refining, VD vacuum degassing, continuous casting, heating, rolling and slow cooling in the box.

[0024] The final slag in the LF refining comprises, in terms of mass percentage: CaO 53-57wt%, Al2O3 38-42wt%, SiO2 3-7wt%.

[0025] By controlling the process parameters of the final slag in the LF refining and the continuous casting process parameters, the present application reduces the center porosity, center segregation and center shrinkage of the casting blank, improves the core quality of the steel, makes the surface hardness and core hardness difference of the steel small, reduces the gas and inclusion content in the steel, and improves the purity of the steel.

[0026] In the present application, the mass percentage of CaO in the final slag in the LF refining is 53-57wt%, for example, it can be 53.5wt%, 54wt%, 54.5wt%, 55wt%, 55.5wt%, 56wt% or 56.5wt% and the like, the mass percentage of Al2O3 in the final slag in the LF refining is 38-42wt%, for example, it can be 38.4wt%, 38.5wt%, 39wt%, 39.5wt%, 40wt%, 40.5wt%, 41wt% or 41.5wt% and the like, and the mass percentage of SiO2 in the final slag in the LF refining is 3-7wt%, for example, it can be 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt% or 6.5wt% and the like, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0027] In the present application, by adjusting the effective element ratio in the ternary phase diagram, the final slag in the LF furnace has the characteristics of low melting point, good fluidity and strong adsorption of inclusions.

[0028] As a preferred technical solution of the present application, the converter smelting adopts high-ladle-slag-reducing and blowing operation.

[0029] Preferably, the end point temperature of the converter smelting is ≥1620℃, for example, it can be 1630℃, 1640℃, 1650℃, 1660℃, 1670℃, 1680℃ or 1700℃, etc., but not limited to the listed values, other values not listed in the value range are also applicable, preferably 1650-1680℃.

[0030] Preferably, the end point C content of the converter smelting is 0.08-0.15wt%, for example, it can be 0.09wt%, 0.10wt%, 0.11wt%, 0.12wt%, 0.13wt% or 0.14wt% etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0031] Preferably, the end point P content of the converter smelting is ≤0.020wt%, for example, it can be 0.018wt%, 0.015wt%, 0.013wt%, 0.012wt%, 0.010wt% or 0.005wt% etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0032] Preferably, slag washing material and alloy are added in the deoxidizing alloying.

[0033] Preferably, the slag washing material includes lime, refining slag and aluminum ingot.

[0034] Preferably, the alloy includes manganese silicon alloy, high-carbon ferromanganese and high-carbon ferrochrome.

[0035] The present application does not specifically limit the amount of slag washing material and alloy, those skilled in the art can select the appropriate amount according to the actual situation, for example: the addition amount of lime in the slag washing material is 500Kg / furnace, the addition amount of refining slag is 300Kg / furnace, and the addition amount of aluminum ingot is 0.5-1.5Kg / t.

[0036] As a preferred technical solution of the present application, the white slag making time of the LF refining is ≥15min, for example, it can be 15min, 20min, 25min, 30min, 35min, 40min, 45min or 50min, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0037] Preferably, the vacuum time of the VD vacuum degassing is ≥15min, for example, it can be 15min, 20min, 25min, 30min, 35min, 40min, 45min or 50min, etc., but not limited to the listed values, other values not listed in the value range are also applicable.

[0038] Preferably, the soft blowing time of the VD vacuum degassing is ≥15 min, for example, it can be 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min or 50 min, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0039] Preferably, the end point V content of the VD vacuum degassing is 0.07-0.08wt%, for example, it can be 0.071wt%, 0.072wt%, 0.073wt%, 0.074wt%, 0.075wt%, 0.076wt%, 0.077wt%, 0.078wt% or 0.079wt%, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0040] As a preferred technical solution of the present application, the specific water amount of the continuous casting is 0.20-0.25L / kg, for example, it can be 0.205L / kg, 0.21L / kg, 0.215L / kg, 0.22L / kg, 0.225L / kg, 0.23L / kg, 0.235L / kg, 0.24L / kg or 0.245L / kg, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0041] Preferably, the casting speed of the continuous casting is 0.85-0.95m / min, for example, it can be 0.87m / min, 0.89m / min, 0.90m / min, 0.91m / min, 0.93m / min or 0.94m / min, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0042] Preferably, the superheat degree of the continuous casting is 15-35℃, for example, it can be 17℃, 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃ or 34℃, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0043] Preferably, the current of the electromagnetic stirring in the mold of the continuous casting is 380-420A, for example, it can be 385A, 390A, 395A, 400A, 405A, 410A or 415A, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0044] Preferably, the frequency of the electromagnetic stirring in the mold of the continuous casting is 2.8-3.2Hz, for example, it can be 2.85Hz, 2.9Hz, 2.95Hz, 3.00Hz, 3.05Hz, 3.10Hz or 2.15Hz, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0045] Preferably, the current of the electromagnetic stirring at the end of continuous casting is 80-120A, for example, can be 85A, 90A, 95A, 100A, 105A, 110A or 115A, etc., but not limited to the listed values, other values not listed in the range of values are also applicable.

[0046] Preferably, the frequency of the electromagnetic stirring at the end of continuous casting is 9.5-10.5Hz, for example, can be 9.6Hz, 9.7Hz, 9.8Hz, 9.9Hz, 10.0Hz, 10.1Hz, 10.2Hz or 10.4Hz, etc., but not limited to the listed values, other values not listed in the range of values are also applicable.

[0047] The present application adopts electromagnetic stirring in the crystallizer and electromagnetic stirring at the end to realize the control of the structure of the casting blank, expand the equiaxed crystal zone of the casting blank, reduce the center porosity, center segregation and center shrinkage of the casting blank, and improve the core quality of the steel.

[0048] As a preferred technical solution of the present application, the temperature of the heating is 1130-1210℃, for example, can be 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, 1190℃, 1200℃ or 1205℃, etc., but not limited to the listed values, other values not listed in the range of values are also applicable.

[0049] Preferably, the heating time is 150-240min, for example, can be 170min, 190min, 200min, 210min, 220min, 230min or 235min, etc., but not limited to the listed values, other values not listed in the range of values are also applicable.

[0050] The present application controls the heating time and temperature, adopts high-temperature diffusion process, and promotes the homogenization of various elements in the steel.

[0051] Preferably, the opening rolling temperature of the rolling is 1030-1100℃, for example, can be 1040℃, 1050℃, 1060℃, 1070℃, 1080℃, 1090℃ or 1095℃, etc., but not limited to the listed values, other values not listed in the range of values are also applicable.

[0052] Preferably, the finishing rolling speed of the rolling is 1.0-3.5m / s, for example, can be 1.5m / s, 2.0m / s, 2.5m / s, 3.0m / s or 3.2m / s, etc., but not limited to the listed values, other values not listed in the range of values are also applicable.

[0053] In the application, under the same specification condition, the rolling speed is reduced by 30% on the original basis, which is beneficial to improve the density of the bar, thereby improving the quality under low magnification, and the specific rolling speed is determined according to the actual situation.

[0054] Preferably, the finish rolling temperature of the rolling is 940-1020℃, for example, it can be 950℃, 960℃, 970℃, 980℃, 990℃, 1000℃ or 1010℃, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0055] As a preferred technical solution of the application, the preparation method comprises: the formula quantity of molten iron in the blast furnace is sequentially subjected to converter smelting, deoxidization alloying, LF refining, VD vacuum degassing, continuous casting, heating, rolling and case-in slow cooling;

[0056] The converter smelting adopts high-ladle-slag-blown operation, the end-point temperature of the converter smelting is ≥1620℃, the end-point C content is 0.08-0.15wt%, and the end-point P content is ≤0.020wt%;

[0057] The deoxidization alloying adds slag washing material and alloy, the slag washing material includes lime, refining slag and aluminum ingot, and the alloy includes manganese-silicon alloy, high-carbon ferromanganese and high-carbon ferrochrome;

[0058] The white slag making time of the LF refining is ≥15min, and the final slag in the LF refining includes, in terms of mass percentage: CaO 53-57wt%, Al2O3 38-42wt%, SiO2 3-7wt%;

[0059] The vacuum time of the VD vacuum degassing is ≥15min, the soft blowing time is ≥15min, and the end-point V content is 0.07-0.08wt%;

[0060] The specific water quantity of the continuous casting is 0.20-0.25L / kg, the pulling speed is 0.85-0.95m / min, and the superheat is 15-35℃; the current of the electromagnetic stirring in the mold in the continuous casting is 380-420A, and the frequency is 2.8-3.2Hz; the current of the end electromagnetic stirring in the continuous casting is 80-120A, and the frequency is 9.5-10.5Hz;

[0061] The temperature of the heating is 1130-1210℃, and the time is 150-240min;

[0062] The open rolling temperature of the rolling is 1030-1100℃, the finish rolling speed is 1.0-3.5m / s, and the finish rolling temperature of the rolling is 940-1020℃.

[0063] The numerical ranges recited herein include all values from and including the lower and upper values. This is true even if the values included in the lower or upper range are outside of the recited range. The ranges are presented essentially to provide some guidance as to what an implementer should select, and endpoints are provided for clarity. Notwithstanding, numerical ranges are non-limiting and are used merely to narrow possibilities for an implementer.

[0064] Compared with the prior art, the present application has the following beneficial effects:

[0065] The present application improves the hardenability and wear resistance by adjusting the contents of carbon, manganese and chromium, matching the contents of vanadium and other elements, controlling the narrow composition and residual elements, reducing composition segregation, optimizing the LF refining process and combining with the whole process protection pouring process, and regulating the casting process parameters, so that the difference between the surface hardness and the core hardness of the prepared grinding ball steel is ≤3HRC, the impact toughness is improved, and the ball consumption is reduced; meanwhile, the gas and inclusion contents in the grinding ball steel are reduced, and the purity of the grinding ball steel is improved. DETAILED DESCRIPTION

[0066] The technical solutions of the present application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as specific limitations on the present application.

[0067] Embodiment 1

[0068] The present embodiment provides a grinding ball steel and a preparation method thereof. The grinding ball steel comprises, in terms of mass percentage: C 0.76wt%, Si 0.27wt%, Mn 0.95wt%, Cr 0.85wt%, Cu 0.15wt%, Ni 0.15wt%, Al 0.03wt%, V 0.07wt%, and the balance of Fe and inevitable impurities; the total mass percentage of Mn+Cr in the grinding ball steel is 1.80wt%; in the inevitable impurities: P≤0.015wt%, S≤0.015wt%.

[0069] The preparation method comprises: sequentially subjecting the formula quantity of blast furnace molten iron to converter smelting, deoxidization alloying, LF refining, VD vacuum degassing, continuous casting, heating, rolling and slow cooling in a box.

[0070] The converter smelting adopts high-ladle-slag-blowing operation, the end-point temperature of the converter smelting is 1660℃, the end-point C content is 0.12wt%, and the end-point P content is 0.010wt%.

[0071] The deoxidization alloying adds slag washing material and alloy, the slag washing material comprises lime, refining slag and aluminum ingot, and the alloy comprises manganese-silicon alloy, high-carbon ferromanganese and high-carbon ferrochrome;

[0072] The LF refining white slag time is 20 min, and the end slag in the LF refining includes CaO 55wt%, Al2O3 40wt%, SiO2 5wt% in mass percentage;

[0073] The VD vacuum degassing vacuum time is 18 min, the soft blowing time is 20 min, and the end point V content is 0.07wt%;

[0074] The specific water amount in the continuous casting is 0.22L / kg, the pulling speed is 0.90m / min, and the superheat is 25℃; the current of the electromagnetic stirring in the crystallizer in the continuous casting is 400A, and the frequency is 3Hz; the current of the end electromagnetic stirring in the continuous casting is 100A, and the frequency is 10Hz;

[0075] The heating temperature is 1170℃, and the time is 200 min;

[0076] The open rolling temperature is 1060℃, the final rolling speed is 2.5m / s, and the final rolling temperature of the rolling is 980℃.

[0077] Example 2

[0078] The present embodiment provides a steel for grinding ball and a preparation method thereof, the steel for grinding ball includes, in mass percentage: C 0.73wt%, Si 0.17wt%, Mn 0.95wt%, Cr 0.80wt%, Cu 0.20wt%, Ni 0.25wt%, Al 0.01wt%, V 0.08wt%, and the balance of Fe and inevitable impurities; the total mass percentage of Mn+Cr in the steel for grinding ball is 1.75wt%; in the inevitable impurities: P≤0.015wt%, S≤0.003wt%;

[0079] The preparation method includes: the formula amount of the blast furnace molten iron is sequentially subjected to converter smelting, deoxidization alloying, LF refining, VD vacuum degassing, continuous casting, heating, rolling, and case storage and slow cooling;

[0080] The converter smelting adopts high-pull blow-by operation, the end point temperature of the converter smelting is 1680℃, the end point C content is 0.08wt%, and the end point P content is 0.008wt%;

[0081] The deoxidization alloying adds slag washing material and alloy, the slag washing material includes lime, refining slag and aluminum ingot, and the alloy includes manganese-silicon alloy, high-carbon ferromanganese and high-carbon ferrochrome;

[0082] The LF refining white slag time is 17 min, and the end slag in the LF refining includes CaO 53wt%, Al2O3 38wt%, SiO2 4wt% in mass percentage;

[0083] The vacuum time of the VD vacuum degassing is 16 min, the soft blowing time is 18 min, and the terminal V content is 0.08wt%;

[0084] The specific water amount of the continuous casting is 0.205L / kg, the pulling speed is 0.85m / min, and the superheat is 17℃; the current of the electromagnetic stirring in the crystallizer in the continuous casting is 380A, and the frequency is 2.85Hz; the current of the end electromagnetic stirring in the continuous casting is 80A, and the frequency is 9.5Hz;

[0085] The temperature of the heating is 1130℃, and the time is 230min;

[0086] The open rolling temperature of the rolling is 1040℃, the final rolling speed is 1.5m / s, and the final rolling temperature of the rolling is 940℃.

[0087] Example 3

[0088] The steel for grinding ball provided by the embodiment and a preparation method thereof, the steel for grinding ball comprises, in mass percentage: C 0.81wt%, Si 0.37wt%, Mn 1.00wt%, Cr 0.85wt%, Cu 0.10wt%, Ni 0.15wt%, A1 0.02wt%, V 0.08wt%, and the balance of Fe and inevitable impurities; the total mass percentage of Mn+Cr in the steel for grinding ball is 1.85wt%; in the inevitable impurities, P≤0.015wt%, S≤0.003wt%;

[0089] The preparation method comprises: formula amount of blast furnace molten iron is sequentially subjected to converter smelting, deoxidization alloying, LF refining, VD vacuum degassing, continuous casting, heating, rolling and box storage slow cooling;

[0090] The converter smelting adopts high-lifting complementary blowing operation, the terminal temperature of the converter smelting is 1650℃, the terminal C content is 0.11wt%, and the terminal P content is 0.010wt%;

[0091] In the deoxidization alloying, slag washing material and alloy are added, the slag washing material comprises lime, refining slag and aluminum ingot, and the alloy comprises manganese-silicon alloy, high-carbon ferromanganese and high-carbon ferrochrome;

[0092] The white slag making time of the LF refining is 20min, and the terminal slag in the LF refining comprises, in mass percentage: CaO 55wt%, A12O3 41wt%, SiO2 5wt%;

[0093] The vacuum time of the VD vacuum degassing is 20min, the soft blowing time is 25min, and the terminal V content is 0.08wt%;

[0094] The specific water amount of the continuous casting is 0.23 L / kg, the pulling speed is 0.92 m / min, and the superheat is 25 ℃; the current of electromagnetic stirring in the crystallizer in the continuous casting is 410 A, and the frequency is 3.1 Hz; the current of electromagnetic stirring at the end in the continuous casting is 110 A, and the frequency is 10.2 Hz;

[0095] The temperature of the heating is 1200 ℃, and the time is 170 min;

[0096] The open rolling temperature of the rolling is 1100 ℃, the final rolling speed is 3 m / s, and the final rolling temperature of the rolling is 1000 ℃.

[0097] Example 4

[0098] The steel for grinding balls and the preparation method thereof are provided, and the steel for grinding balls comprises, in mass percentage: C 0.76wt%, Si 0.27wt%, Mn 0.90wt%, Cr 0.78wt%, Cu 0.15wt%, Ni 0.15wt%, Al 0.03wt%, V 0.07wt%, and the balance of Fe and inevitable impurities; the total mass percentage of Mn+Cr in the steel for grinding balls is 1.68wt%; in the inevitable impurities: P≤0.015wt%, S≤0.015wt%.

[0099] The preparation method is the same as that in example 1.

[0100] Example 5

[0101] The steel for grinding balls and the preparation method thereof are provided, and the steel for grinding balls comprises, in mass percentage: C 0.76wt%, Si 0.27wt%, Mn 1.00wt%, Cr 0.90wt%, Cu 0.15wt%, Ni 0.15wt%, Al 0.03wt%, V 0.07wt%, and the balance of Fe and inevitable impurities; the total mass percentage of Mn+Cr in the steel for grinding balls is 1.90wt%; in the inevitable impurities: P≤0.015wt%, S≤0.015wt%.

[0102] The preparation method is the same as that in example 1.

[0103] Example 6

[0104] The steel for grinding balls and the preparation method thereof are provided, and except that the current of electromagnetic stirring in the crystallizer in the continuous casting is 360 A and the frequency is 3.1 Hz, other conditions are the same as those in example 1.

[0105] Example 7

[0106] The embodiment provides a steel for grinding balls and a preparation method thereof, wherein, except that the current of electromagnetic stirring in the crystallizer in the continuous casting is 450 A and the frequency is 3.1 Hz, other conditions are the same as those in the embodiment 1.

[0107] Embodiment 8

[0108] The embodiment provides a steel for grinding balls and a preparation method thereof, wherein, except that the current of electromagnetic stirring in the crystallizer in the continuous casting is 450 A and the frequency is 3.1 Hz, other conditions are the same as those in the embodiment 1.

[0109] Embodiment 9

[0110] The embodiment provides a steel for grinding balls and a preparation method thereof, wherein, except that the current of electromagnetic stirring in the crystallizer in the continuous casting is 450 A and the frequency is 3.1 Hz, other conditions are the same as those in the embodiment 1.

[0111] Comparative example 1

[0112] The comparative example provides a steel for grinding balls and a preparation method thereof, wherein, except that the mass percentage content of V is 0.03 wt%, other conditions are the same as those in the embodiment 1.

[0113] Comparative example 2

[0114] The comparative example provides a steel for grinding balls and a preparation method thereof, wherein, except that the mass percentage content of V is 0.13 wt%, other conditions are the same as those in the embodiment 1.

[0115] Comparative example 3

[0116] The comparative example provides a steel for grinding balls and a preparation method thereof, wherein, except that the mass percentage content of V is 0.03 wt%, other conditions are the same as those in the embodiment 1.

[0117] Comparative example 4

[0118] The comparative example provides a steel for grinding balls and a preparation method thereof, wherein, except that the mass percentage content of V is 0.03 wt%, other conditions are the same as those in the embodiment 1.

[0119] The steel for grinding balls prepared in the above embodiment and comparative example is detected in terms of the difference between surface hardness and core hardness, impact energy and ball consumption, and the test results are shown in Table 1, and the distribution of inclusions of the steel for grinding balls is shown in Table 2.

[0120] Table 1

[0121]

[0122]

[0123] wherein: the difference is the difference between the surface hardness value and the core hardness value of the steel for grinding ball;

[0124] From Table 1, it can be concluded that:

[0125] (1) The steel for grinding ball and the preparation method thereof provided in embodiments 1-3 can make the difference between the surface hardness value and the core hardness value of the prepared steel for grinding ball ≤3HRC, and the impact energy ≥15J, thereby reducing the ball consumption;

[0126] (2) It can be known from the comparison of embodiment 1 and embodiments 4-5 that when the total amount of Mn+Cr in the steel for grinding ball is too small or too large, it is not conducive to reducing the difference between the surface hardness and the core hardness of the steel, and the impact toughness slightly decreases;

[0127] (3) It can be known from the comparison of embodiment 1 and embodiments 6-9 that when the continuous casting process parameters are not reasonably selected, the center porosity, center segregation and center shrinkage of the casting blank become larger, which is not conducive to improving the core quality of the steel;

[0128] (4) It can be known from the comparison of embodiment 1 and comparative examples 1-2 that when the V content in the steel for grinding ball is too high or too low, the difference between the surface hardness and the core hardness of the steel becomes large, and the impact toughness decreases;

[0129] (5) It can be known from the comparison of embodiment 1 and comparative examples 3-4 that when the content of each oxide in the final slag in the LF refining is not in the optimal range, the inclusion content in the steel increases, which affects the impact toughness and the ball consumption;

[0130] Table 2

[0131] Class A inclusions Class B inclusions Class C inclusions Class D inclusions Example 1 1.0 0.5 0 0.5 Example 2 1.0 0.5 0 0.5 Example 3 1.0 0.5 0 0.5 Example 4 1.5 1.0 0 0.5 Example 5 1.5 1.0 0 0.5 Example 6 1.5 1.5 0 0.5 Example 7 1.5 1.5 0 0.5 Example 8 1.5 1.5 0 0.5 Example 9 1.5 1.5 0 0.5 Comparative Example 1 1.5 1.0 0 1.0 Comparative Example 2 1.5 1.0 0 1.5 Comparative Example 3 1.5 2.0 0 1.5 Comparative Example 4 1.5 1.5 0 1.5

[0132] From Table 2, it can be concluded that:

[0133] (1) The steel for grinding ball and the preparation method thereof provided in embodiments 1-3 can effectively control the inclusion content in the steel, thereby ensuring that the obtained steel for grinding ball has good performance and a long service life;

[0134] (2) It can be known from the comparison of embodiment 1 and embodiments 6-9 that when the continuous casting process parameters are not reasonably selected, the inclusion content in the steel increases, and the level of B-type inclusions increases significantly;

[0135] (3) It can be known from the comparison of embodiment 1 and comparative examples 1-2 that when the V content in the steel for grinding ball is too high, titanium nitride inclusions are easily formed, which leads to an increase in the inclusion content in the steel;

[0136] (4) From the comparison of Example 1 and Comparative Examples 3-4, it can be seen that when the content of each oxide in the final slag in LF refining is not within the preferred range, the inclusions in the steel obviously increase because the inclusions cannot be sufficiently adsorbed.

[0137] The applicant declares that the present application is illustrated by the above-mentioned embodiments to show the detailed structural features of the present application, but the present application is not limited to the above-mentioned detailed structural features, i.e. it does not mean that the present application must rely on the above-mentioned detailed structural features to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the components selected by the present application, addition of auxiliary components, selection of specific modes, etc. all fall within the protection scope and disclosure scope of the present application.

Claims

1. Steel for grinding balls, characterized in that, The steel for the grinding ball comprises, in mass percentage: C 0.72-0.82wt%, Si 0.17-0.37wt%, Mn 0.70-1.00wt%, Cr 0.50-0.90wt%, Cu≤0.25wt%, Ni≤0.25wt%, Al≤0.06wt%, V 0.07-0.08wt%, the balance of Fe and inevitable impurities; The total mass percentage of Mn+Cr in the steel for the grinding ball is 1.75-1.85wt%; The difference between the surface hardness value and the core hardness value of the steel for the grinding ball is ≤3HRC; The steel for the grinding ball is prepared by the following method, which comprises: formula quantity blast furnace molten iron is sequentially subjected to converter smelting, deoxidization alloying, LF refining, VD vacuum degassing, continuous casting, heating, rolling and slow cooling in a box; The end slag in the LF refining comprises, in mass percentage: CaO 53-57wt%, Al2O3 38-42wt%, SiO2 3-7wt%; The current of electromagnetic stirring in the crystallizer in the continuous casting is 380-420A, and the frequency is 2.8-3.2Hz; the current of end electromagnetic stirring in the continuous casting is 80-120A, and the frequency is 9.5-10.5Hz.

2. Steel for grinding balls according to claim 1, characterized in that, In the inevitable impurities, the mass percentage of P is ≤0.035wt%, and the mass percentage of S is ≤0.035wt%.

3. Steel for grinding balls according to claim 2, characterized in that, In the inevitable impurities, the mass percentage of P is ≤0.015wt%, and the mass percentage of S is ≤0.003wt%.

4. Steel for grinding balls according to claim 1, characterized in that, The impact energy of the steel for the grinding ball is ≥15J.

5. Steel for grinding balls according to claim 1, characterized in that, The ball consumption of the steel for the grinding ball is ≤0.5kg.

6. Steel for grinding balls according to claim 1, characterized in that, The inclusion A class of the steel for the grinding ball is ≤1.5 level, the inclusion B class is ≤1.0 level, the inclusion C class is ≤0 level, and the inclusion D class is ≤1.0 level.

7. A method of manufacturing a steel for grinding balls as claimed in any of claims 1 to 6, characterized in that, The steel for the grinding ball is prepared by the following method, which comprises: formula quantity blast furnace molten iron is sequentially subjected to converter smelting, deoxidization alloying, LF refining, VD vacuum degassing, continuous casting, heating, rolling and slow cooling in a box; The end slag in the LF refining comprises, in mass percentage: CaO 53-57wt%, Al2O3 38-42wt%, SiO2 3-7wt%; The current of electromagnetic stirring in the crystallizer in the continuous casting is 380-420A, and the frequency is 2.8-3.2Hz; the current of end electromagnetic stirring in the continuous casting is 80-120A, and the frequency is 9.5-10.5Hz.

8. The preparation method according to claim 7, characterized in that, The converter smelting adopts high-lifting blow operation.

9. The preparation method according to claim 7, characterized in that, The end point temperature of the converter smelting is ≥1620℃.

10. The method of claim 9, wherein, The end point temperature of the converter smelting is 1650-1680℃.

11. The preparation method according to claim 7, characterized in that, The C content at the end point of the converter smelting is 0.08-0.15wt%.

12. The method of claim 7, wherein, The P content at the end point of the converter smelting is ≤0.020wt%.

13. The preparation method according to claim 7, characterized in that, The deoxidization alloying adds slag washing material and alloy.

14. The method of claim 13, wherein, The slag washing material comprises lime, refining slag and aluminum ingot.

15. The preparation method according to claim 13, characterized in that, The alloy comprises manganese-silicon alloy, high-carbon ferromanganese and high-carbon ferrochrome.

16. The method of claim 7, wherein, The white slag making time of the LF refining is ≥15min.

17. The method of claim 7, wherein the method further comprises, The vacuum time of the VD vacuum degassing is ≥15min.

18. The method of claim 7, wherein, The soft blowing time of the VD vacuum degassing is ≥15min.

19. The method of claim 7, wherein, The V content of the VD vacuum degassing end point is 0.07-0.08wt%.

20. The method of claim 7, wherein, The specific water amount of the continuous casting is 0.20-0.25L / kg.

21. The method of claim 7, wherein, The casting speed of the continuous casting is 0.85-0.95m / min.

22. The method of claim 7, wherein, The superheat of the continuous casting is 15-35℃.

23. The method of claim 7, wherein the method further comprises, The heating temperature is 1130-1210℃.

24. The method of claim 7, wherein, The heating time is 150-240min.

25. The method of claim 7, wherein, The rough rolling temperature of the rolling is 1030-1100℃.

26. The method of claim 7, wherein, The final rolling speed of the rolling is 1.0-3.5m / s.

27. The method of claim 7, wherein, The final rolling temperature of the rolling is 940-1020℃.

28. The method of claim 7, wherein, The preparation method comprises: formula amount of blast furnace molten iron is sequentially subjected to converter smelting, deoxidization alloying, LF refining, VD vacuum degassing, continuous casting, heating, rolling and box storage slow cooling; The converter smelting adopts high-lifting complementary blowing operation, the end point temperature of the converter smelting is ≥1620℃, the end point C content is 0.08-0.15wt%, and the end point P content is ≤0.020wt%; The deoxidization alloying adds slag washing material and alloy, the slag washing material comprises lime, refining slag and aluminum ingot, and the alloy comprises manganese-silicon alloy, high-carbon ferromanganese and high-carbon ferrochrome; The white slag forming time of the LF refining is ≥15min, and the final slag of the LF refining comprises, in terms of mass percentage: CaO 53-57wt%, Al2O3 38-42wt%, and SiO2 3-7wt%; The vacuum time of the VD vacuum degassing is ≥15min, the soft blowing time is ≥15min, and the end point V content is 0.07-0.08wt%; The specific water amount of the continuous casting is 0.20-0.25L / kg, the casting speed is 0.85-0.95m / min, and the superheat is 15-35℃; the current of the mold electromagnetic stirring in the continuous casting is 380-420A, and the frequency is 2.8-3.2Hz; the current of the end electromagnetic stirring in the continuous casting is 80-120A, and the frequency is 9.5-10.5Hz; The heating temperature is 1130-1210℃, and the time is 150-240min. The rough rolling temperature of the rolling is 1030-1100℃, the final rolling speed is 1.0-3.5m / s, and the final rolling temperature of the rolling is 940-1020℃.

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