High-wear-resistance hot-rolled round steel for titanium-containing steel balls and preparation method of high-wear-resistance hot-rolled round steel

Abstract

The invention relates to the technical field of material metallurgy, and discloses high-wear-resistance hot-rolled round steel for titanium-containing steel balls and a preparation method thereof.The round steel comprises 0.60%-0.67% of C, 1.40%-1.60% of Si, 0.70%-0.90% of Mn, smaller than or equal to 0.020% of P, smaller than or equal to 0.015% of S, 0.70%-0.90% of Cr, 0.10%-0.15% of Ti, smaller than or equal to 0.30% of Ni, smaller than or equal to 0.40% of Cu, smaller than or equal to 0.05% of Al, smaller than or equal to 0.0020% of O, smaller than or equal to 0.0002% of H and smaller than or equal to 0.0035% of N; and the balance of Fe and inevitable impurities. Through the high-titanium-low-nitrogen microalloying design, the technical contradiction that the toughness is remarkably reduced when the strength and the hardness of traditional high-carbon steel ball steel are improved is solved, and excellent synergistic improvement of the strength, the hardness and the toughness is achieved.

Description

Technical Field

[0001] This invention relates to the field of materials metallurgy, and in particular to a hot-rolled round bar for titanium-containing steel balls with high wear resistance and its preparation method. Background Technology

[0002] With the increasing scale of ball mills and semi-autogenous mills in industries such as mining, metallurgy, and power plants, the quality requirements for the core grinding media—wear-resistant steel balls—are becoming increasingly stringent. High-performance wear-resistant steel balls are key to reducing material loss, improving grinding efficiency, and achieving energy conservation and emission reduction. Currently, the mainstream process for producing high-performance grinding balls is the rolling or forging of continuously cast round steel, resulting in a quality far exceeding that of cast grinding balls. Therefore, the performance of the basic raw material, the round steel, directly determines the final quality of the steel balls.

[0003] The core requirements for steel balls in ball mills are "high hardness, high toughness, and low breakage rate." Among these, increasing hardness is the most effective way to reduce wear. However, a core technical contradiction has long existed in this field: simply increasing the carbon content to pursue high hardness inevitably leads to a significant decrease in material toughness. This makes steel balls made of high-carbon steel prone to breakage under impact loads, resulting in poor reliability; while using medium- or low-carbon steel to ensure toughness results in insufficient hardness and poor wear resistance. Existing technologies struggle to achieve an ideal balance between ultra-high hardness and high toughness, failing to meet the increasingly stringent requirements of large-scale equipment for grinding media.

[0004] Therefore, there is a need in the existing technology for improving hot-rolled round steel bars for titanium-containing steel balls with high wear resistance and their preparation methods. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a hot-rolled round steel bar for titanium-containing steel balls with high wear resistance and its preparation method. Through the microalloying design of high titanium and low nitrogen, the technical contradiction of the significant decrease in toughness when the strength and hardness of traditional high carbon steel balls are improved is solved, and excellent synergistic improvement of strength, hardness and toughness is achieved.

[0006] To achieve the above objectives, this invention provides a hot-rolled round steel bar for titanium-containing steel balls with high wear resistance. The round steel bar, by weight percentage, comprises: C 0.60%–0.67%, Si 1.40%–1.60%, Mn 0.70%–0.90%, P ≤0.020%, S ≤0.015%, Cr 0.70%–0.90%, Ti 0.10–0.15%, Ni ≤0.30%, Cu ≤0.40%, Al ≤0.05%, O ≤0.0020%, H ≤0.0002%, N ≤0.0035%; the remainder being Fe and unavoidable impurities.

[0007] Another aspect of the present invention provides a method for preparing hot-rolled round steel for titanium-containing steel balls with high wear resistance, comprising the following steps: S1 is produced by converter smelting, ladle refining, RH vacuum treatment, continuous casting, and slow cooling of the billet to obtain a billet with the required chemical composition. In the later stage of RH vacuum treatment, FeTi alloy is added to perform titanium microalloying, and the Ti content is controlled in the range of 0.10 to 0.15%. S2 produces hot-rolled round steel by heating the billet, descaling it with high-pressure water, rolling it, and slow cooling it. The final rolling temperature is controlled to be 850-900℃ during rolling.

[0008] In some implementations, the converter smelting process uses desulfurized semi-steel smelting, with S ≤ 0.010% in the semi-steel fed into the furnace; the converter endpoint target is C ≥ 0.05%, P ≤ 0.010%, and the tapping temperature ≥ 1640℃.

[0009] In some embodiments, a deoxidizing alloy is added during the tapping process to pre-deoxidize the molten steel. The alloy is added starting at 1 / 3 of the tapped steel and ending at 2 / 3 of the tapped steel. The deoxidizing alloy includes FeSi alloy, FeMn alloy, and FeCr alloy, with C controlled in the range of 0.57% to 0.64%, Si controlled in the range of 1.40% to 1.60%, Mn controlled in the range of 0.70% to 0.90%, and Cr controlled in the range of 0.70% to 0.90%.

[0010] In some implementations, the alkalinity at the outlet of the refining process is controlled at 2.0 to 3.0.

[0011] In some implementations, the vacuum treatment process, where the vacuum level is ≤3 mbar, takes no less than 12 minutes.

[0012] In some implementations, during continuous casting, the ladle of molten steel is superheated to 20–40°C, casting is carried out at a constant speed, the billet pulling speed is ≤0.68 m / min, the electromagnetic stirring current of the crystallizer is 335–350 A, and the frequency is 2.4 Hz; and protective casting is adopted throughout the casting process.

[0013] In some implementations, in the slow cooling process of the billet, the billet is stacked and cooled slowly for a period of not less than 48 hours.

[0014] In some implementations, the temperature control of each section of the heating furnace in the heating process is as follows: first heating temperature 800-1100℃, second heating temperature 1000-1250℃, third heating temperature 1220-1300℃, soaking temperature 1220-1280℃, total heating time not less than 210 min, and soaking time not less than 43 min.

[0015] In some implementations, the temperature of the material entering the slow cooling pit is ≥500°C in the slow cooling process.

[0016] The present invention has at least the following beneficial technical effects: The hot-rolled round steel for high wear resistance titanium-containing steel balls provided by this invention has the following mechanical properties: yield strength ≥ 600 MPa, tensile strength ≥ 1050 MPa, elongation after fracture ≥ 15.0%, reduction of area ≥ 25%; room temperature unnotched impact toughness ≥ 240 J, and hardness ≥ 300 HB. The composition of this invention, through the synergistic effect of grain refinement and precipitation strengthening, improves strength and hardness without compromising toughness. In fact, grain refinement achieves a high level of room temperature unnotched impact toughness, perfectly achieving a balance between strength and toughness. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating an embodiment of a method for preparing a hot-rolled round bar for titanium-containing steel balls with high wear resistance, as provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0020] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0021] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] This invention provides a hot-rolled round steel bar for titanium-containing steel balls with high wear resistance. The chemical composition of the round steel bar, by weight percentage, includes: C 0.60%–0.67%, Si 1.40%–1.60%, Mn 0.70%–0.90%, P≤0.020%, S≤0.015%, Cr 0.70%–0.90%, Ti 0.10–0.15%, Ni ≤0.30%, Cu ≤0.40%, Al≤0.05%, O≤0.0020%, H≤0.0002%, N≤0.0035%; the remainder being Fe and unavoidable impurities.

[0023] In another aspect, the present invention provides a method for preparing hot-rolled round steel for making titanium-containing steel balls with high wear resistance, as described above. Figure 1 As shown, it includes the following steps: S1 is produced by converter smelting, ladle refining, RH vacuum treatment, continuous casting, and slow cooling of the billet to obtain a billet with the required chemical composition. In the later stage of RH vacuum treatment, FeTi alloy is added to perform titanium microalloying, and the Ti content is controlled in the range of 0.10 to 0.15%. S2 produces hot-rolled round steel by heating the billet, descaling it with high-pressure water, rolling it, and slow cooling it. The final rolling temperature is controlled to be 850-900℃ during rolling.

[0024] The addition of FeTi alloy during the later stages of vacuum treatment, when the molten steel is highly pure, significantly reduced the oxidation loss of Ti, improved the yield and stability of Ti, and ensured the precision of composition control. Controlling the final rolling temperature facilitated the induction of precipitation of microalloyed carbonitrides such as TiC at the end of rolling, and suppressed the recrystallization and growth of post-rolled austenite grains, further refining the grain size.

[0025] Furthermore, in the converter smelting process, desulfurized semi-steel smelting is adopted, with S≤0.010% in the semi-steel fed into the furnace; the converter endpoint target is C≥0.05%, P≤0.010%, and the tapping temperature≥1640℃.

[0026] Furthermore, during the tapping process, deoxidizing alloys are added to pre-deoxidize the molten steel. The addition of the alloys begins when 1 / 3 of the steel has been tapped and ends when 2 / 3 of the steel has been tapped. The deoxidizing alloys include FeSi alloy, FeMn alloy, and FeCr alloy. The C content is controlled within the range of 0.57% to 0.64%, the Si content within the range of 1.40% to 1.60%, the Mn content within the range of 0.70% to 0.90%, and the Cr content within the range of 0.70% to 0.90%.

[0027] Furthermore, in the ladle refining process, the alkalinity at the refined product outlet is controlled at 2.0 to 3.0.

[0028] Furthermore, in the vacuum treatment process, the treatment time for a vacuum degree ≤ 3 mbar is not less than 12 min.

[0029] Furthermore, during continuous casting, the ladle of molten steel is superheated to 20–40°C, casting is carried out at a constant speed, the billet pulling speed is ≤0.68m / min, the electromagnetic stirring current of the crystallizer is 335–350A, and the frequency is 2.4Hz; and protective casting is adopted throughout the casting process.

[0030] Furthermore, in the slow cooling process of the billet, the billets are stacked and cooled slowly for a period of not less than 48 hours.

[0031] Furthermore, in the heating process, the temperature control of each section of the heating furnace is as follows: first heating temperature 800~1100℃, second heating temperature 1000~1250℃, third heating temperature 1220~1300℃, soaking temperature 1220~1280℃, total heating time not less than 210min, soaking time not less than 43min.

[0032] Furthermore, in the slow cooling process, the temperature of the product entering the slow cooling pit is ≥500℃. The slow cooling process aims to homogenize the internal structure, release internal stress, prevent cracks caused by excessively rapid cooling, and ensure the internal quality of the product.

[0033] This scheme controls the Ti content at a relatively high level of 0.10-0.15%, far exceeding that of conventional steel grades. Its mechanism of action is dual: (1) Grain refinement (undissolved particles): Some Ti forms stable TiN or Ti(C,N) particles at high temperatures. These particles can effectively pin grain boundaries during austenitization heating, strongly inhibiting the growth of austenite grains, thereby obtaining fine original austenite grains, laying the foundation for finally obtaining a fine room temperature microstructure. According to the Hall-Page formula, grain refinement is the only strengthening mechanism that can simultaneously improve strength and toughness.

[0034] (2) Precipitation strengthening (nanoprecipitation): Another part of the Ti dissolved in austenite will precipitate in the form of uniform and dispersed nano-sized TiC particles during subsequent rolling and cooling. These nanoparticles can effectively hinder dislocation movement, produce a significant precipitation strengthening effect, and greatly improve the strength and hardness of the material.

[0035] Therefore, through the synergistic effect of the above-mentioned "fine grain strengthening" and "precipitation strengthening", this solution not only improves the strength (tensile strength ≥1050MPa) and hardness (≥300HB) without compromising the toughness, but also achieves a high level of room temperature unnotched impact toughness of ≥240J through grain refinement, thus perfectly achieving a combination of strength and toughness.

[0036] This method strictly limits the nitrogen content to an extremely low level of ≤0.0035% and employs protective casting throughout the continuous casting process. The purpose of this measure is very clear: to minimize the content of free nitrogen in the molten steel. This effectively prevents the formation of coarse, irregular, and sharply angular liquid-precipitated TiN inclusions during the solidification process. These inclusions are typical stress concentration sources that severely rupture the matrix, becoming the starting point for crack initiation and propagation, and greatly harming toughness (especially impact toughness). By strictly controlling the nitrogen content, the formation of such harmful inclusions is fundamentally eliminated, maintaining the lower limit of material toughness and ensuring that the benefits of high Ti content are fully realized, rather than producing negative effects.

[0037] The present invention will be further explained below with reference to specific embodiments.

[0038] Example 1 A steel plant uses the technology of this invention to produce high-wear-resistant titanium-containing hot-rolled round bars for use in a converter process with a nominal capacity of 120 tons (actual output range of 120-140 tons). The production process is as follows: converter smelting, ladle refining, RH vacuum treatment, continuous casting, and slow cooling of the billet to obtain the required billet. The billet is then subjected to heating, high-pressure water descaling, rolling, and slow cooling in sequence. Specific process details: First, 136 tons of molten iron are added to the converter, with a sulfur content not exceeding 0.010%. After the molten iron is added to the converter, its oxygen blowing function is used to initially refine it into steel. When the steel composition reaches 0.07% C, 0.005% P, and 0.006% S, and the temperature is 1656℃, it is tapped into the ladle, with an actual tapping volume of 134 tons. During tapping, FeSi, FeMn, and FeCr alloys and a carburizing agent are added to the molten steel to alloy the C, Si, Mn, and Cr elements, controlling the C content in the molten steel to be 0.60%, Si content to 1.5%, Mn content to 0.8%, and Cr content to 0.8%. A certain amount of deoxidizing alloy is also added to pre-deoxidize the molten steel. The alloy is added starting when 1 / 3 of the steel has been tapped and must be completed when 2 / 3 has been tapped. 80m of aluminum wire was quantitatively fed into the small platform. After feeding the wire, argon was blown at a low flow rate. It was forbidden to blow the molten steel surface to the point of violent turbulence. The N content was measured to be 18ppm.

[0039] The molten steel arrives at the refining furnace for electric heating and refining, and its basicity at the outlet is 2.5.

[0040] When the molten steel reaches the RH process, it undergoes vacuum treatment. The treatment time is 16 minutes with a vacuum degree ≤3mbar. The chemical composition is then fine-tuned. At this time, FeTi alloy is added to adjust the Ti content, which is controlled to 0.13%.

[0041] Casting 360mm×450mm billets on a continuous casting machine at a superheat of 25~35℃, constant casting speed of 0.60m / min, and an electromagnetic stirring current of 340A and a frequency of 2.4Hz in the crystallizer. Protective measures should be taken throughout the casting process, using long nozzles and sealing gaskets from the ladle to the tundish. Before opening the ladle for pouring, the long nozzle should be fitted first; open pouring is prohibited. Argon should be blown through the long nozzle at a low flow rate to maintain slight movement of the liquid surface, preventing violent churning in the impact zone. After opening the ladle, the long nozzle should be promptly immersed in molten steel for pouring. The weight of molten steel in the ladle during pouring should not be less than 20 tons. Analysis of the molten steel sample taken from the tundish in the continuous casting machine revealed the following chemical composition: 0.63% C, 1.5% Si, 0.8% Mn, 0.8% Cr, 0.13% Ti, 0.007% P, 0.006% S, 0.0030% N, with the remainder being Fe and other unavoidable impurities. The billets are stacked and allowed to cool naturally to room temperature.

[0042] After cooling, the billet is sent to the rolling production line for heating and rolling. The temperatures of each section of the heating furnace are as follows: first heating temperature is 868℃, second heating temperature is 1023℃, third heating temperature is 1230℃, and the soaking temperature is 1250℃. The total heating time is 223 minutes, and the soaking time is 50 minutes. After being removed from the furnace, it undergoes high-pressure water descaling and is rolled into hot-rolled round bars for titanium-containing steel balls, with a final rolling temperature of 875℃. It is then immediately transferred to a slow cooling pit with an initial temperature of 550℃.

[0043] The hot-rolled round steel for high wear resistance titanium-containing steel balls produced by the above method has the following mechanical properties: yield strength 621 MPa, tensile strength 1086 MPa, elongation after fracture 15.5%, reduction of area 26%; room temperature unnotched impact toughness meets 250 J, and hardness meets 314 HB.

[0044] Example 2 A steel plant uses the technology of this invention to produce high-wear-resistant titanium-containing hot-rolled round steel balls in a converter process with a nominal capacity of 120 tons (actual output range of 120-140 tons). The production process is as follows: converter smelting, ladle refining, RH vacuum treatment, continuous casting, and slow cooling of the billet to obtain the required billet. The billet is then subjected to heating, high-pressure water descaling, rolling, and slow cooling in sequence. Specific process details: First, 136 tons of molten iron are added to the converter, with a sulfur content not exceeding 0.010%. After the molten iron is added to the converter, its oxygen blowing function is used to initially refine it into steel. When the steel composition reaches 0.07% C, 0.005% P, and 0.006% S, and the temperature is 1678℃, it is tapped into the ladle, with an actual tapping volume of 131 tons. During tapping, FeSi, FeMn, FeCr, and a carburizing agent are added to the molten steel to alloy the C, Si, Mn, and Cr elements, controlling the C content in the molten steel to be 0.57%, Si content to 1.4%, Mn content to 0.7%, and Cr content to 0.7%. A certain amount of deoxidizing alloy is also added to pre-deoxidize the molten steel. The alloy is added starting when 1 / 3 of the steel has been tapped and must be completed when 2 / 3 has been tapped. 80m of aluminum wire was quantitatively fed into the small platform. After feeding the wire, argon was blown at a low flow rate. It was forbidden to blow the molten steel surface to the point of violent turbulence. The nitrogen content was measured to be 19ppm.

[0045] The molten steel arrives at the refining furnace for electric heating and refining, and its basicity at the outlet is 2.1.

[0046] When the molten steel reaches the RH process, it undergoes vacuum treatment. The treatment time is 15 minutes with a vacuum degree ≤3mbar. The chemical composition is then fine-tuned. At this time, FeTi alloy is added to adjust the Ti content, which is controlled to 0.10%.

[0047] Casting 320mm×410mm billets on a continuous casting machine at a superheat of 25~35℃, constant casting speed of 0.68m / min, and an electromagnetic stirring current of 350A and a frequency of 2.4Hz in the crystallizer. Protective measures should be taken throughout the casting process, using long nozzles and sealing gaskets from the ladle to the tundish. Before opening the ladle for pouring, the long nozzle should be fitted first; open pouring is prohibited. Argon should be blown through the long nozzle at a low flow rate to maintain slight movement of the liquid surface, preventing violent churning in the impact zone. After opening the ladle, the long nozzle should be promptly immersed in molten steel for pouring. The weight of molten steel in the ladle during pouring should not be less than 20 tons. Analysis of the molten steel sample taken from the tundish in the continuous casting machine revealed the following chemical composition: 0.60% C, 1.4% Si, 0.7% Mn, 0.7% Cr, 0.13% Ti, 0.007% P, 0.006% S, 0.0032% N, with the remainder being Fe and other unavoidable impurities. The billets are stacked and allowed to cool naturally to room temperature.

[0048] After cooling, the billet is sent to the rolling production line for heating and rolling. The temperatures of each section of the heating furnace are as follows: first heating temperature is 925℃, second heating temperature is 1120℃, third heating temperature is 1220℃, and the soaking temperature is 1230℃. The total heating time is 246 minutes, and the soaking time is 54 minutes. After being removed from the furnace, it undergoes high-pressure water descaling and is rolled into hot-rolled round bars for high wear-resistant titanium-containing steel balls, with a final rolling temperature of 860℃. It is then immediately transferred to a slow cooling pit with an initial temperature of 512℃.

[0049] The hot-rolled round steel for high wear resistance titanium-containing steel balls produced by the above method has the following mechanical properties: yield strength 645MPa, tensile strength 1105MPa, elongation after fracture 15%, reduction of area 25%; room temperature unnotched impact toughness meets 240J, and hardness meets 320HB.

[0050] Example 3 A steel plant uses the technology of this invention to produce high-wear-resistant titanium-containing hot-rolled round steel balls in a converter process with a nominal capacity of 120 tons (actual output range of 120-140 tons). The production process is as follows: converter smelting, ladle refining, RH vacuum treatment, continuous casting, and slow cooling of the billet to obtain the required billet. The billet is then subjected to heating, high-pressure water descaling, rolling, and slow cooling in sequence. Specific process details: First, 131 tons of molten iron are added to the converter, with a sulfur content not exceeding 0.010%. After the molten iron is added to the converter, its oxygen blowing function is used to initially refine it into steel. When the steel composition reaches 0.07% C, 0.005% P, and 0.006% S, and the temperature is 1648℃, it is tapped into the ladle, with an actual tapping yield of 124 tons. During tapping, FeSi, FeMn, and FeCr alloys and a carburizing agent are added to the molten steel to alloy the C, Si, Mn, and Cr elements, controlling the C content in the molten steel to be 0.64%, Si content to 1.6%, Mn content to 0.9%, and Cr content to 0.9%. A certain amount of deoxidizing alloy is also added to pre-deoxidize the molten steel. The alloy is added starting when 1 / 3 of the steel has been tapped and must be completed when 2 / 3 has been tapped. 80m of aluminum wire was quantitatively fed into the small platform. After feeding the wire, argon was blown at a low flow rate. It was forbidden to blow the molten steel surface to the point of violent turbulence. The N content was measured to be 20ppm.

[0051] The molten steel arrives at the refining furnace for electric heating and refining, and its basicity at the outlet is 2.9.

[0052] When the molten steel reaches the RH process, it undergoes vacuum treatment. The treatment time is 16 minutes with a vacuum degree ≤3mbar. The chemical composition is then fine-tuned. At this time, FeTi alloy is added to adjust the Ti content, which is controlled to 0.15%.

[0053] Casting 320mm×410mm billets on a continuous casting machine at a superheat of 25~35℃, constant casting speed of 0.68m / min, and an electromagnetic stirring current of 350A and a frequency of 2.4Hz in the crystallizer. Protective measures should be taken throughout the casting process, using long nozzles and sealing gaskets from the ladle to the tundish. Before opening the ladle for pouring, the long nozzle should be fitted first; open pouring is prohibited. Argon should be blown through the long nozzle at a low flow rate to maintain slight movement of the liquid surface, preventing violent churning in the impact zone. After opening the ladle, the long nozzle should be promptly immersed in molten steel for pouring. The weight of molten steel in the ladle during pouring should not be less than 20 tons. Analysis of the molten steel sample taken from the tundish in the continuous casting machine revealed the following chemical composition: 0.67% C, 1.6% Si, 0.9% Mn, 0.9% Cr, 0.15% Ti, 0.007% P, 0.006% S, 0.0035% N, with the remainder being Fe and other unavoidable impurities. The billets are stacked and allowed to cool naturally to room temperature.

[0054] After cooling, the billet is sent to the rolling production line for heating and rolling. The temperatures of each section of the heating furnace are as follows: first heating temperature is 1081℃, second heating temperature is 1180℃, third heating temperature is 1260℃, and the soaking temperature is 1275℃. The total heating time is 212 minutes, and the soaking time is 48 minutes. After being removed from the furnace, it undergoes high-pressure water descaling and is rolled into hot-rolled round bars for high wear-resistant titanium-containing steel balls, with a final rolling temperature of 890℃. It is then immediately transferred to a slow cooling pit with an initial temperature of 578℃.

[0055] The hot-rolled round steel for high wear resistance titanium-containing steel balls produced by the above method has the following mechanical properties: yield strength 605MPa, tensile strength 1058MPa, elongation after fracture 16%, reduction of area 27%; room temperature unnotched impact toughness meets 235J, and hardness meets 305HB.

[0056] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0057] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0058] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0059] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A hot-rolled round bar for titanium-containing steel balls with high wear resistance, characterized in that, The chemical composition of the round steel, by weight percentage, includes: C 0.60%–0.67%, Si 1.40%–1.60%, Mn 0.70%–0.90%, P≤0.020%, S≤0.015%, Cr 0.70%–0.90%, Ti 0.10–0.15%, Ni ≤0.30%, Cu ≤0.40%, Al≤0.05%, O≤0.0020%, H≤0.0002%, N≤0.0035%; the remainder being Fe and unavoidable impurities.

2. A method for preparing hot-rolled round steel bars for producing titanium-containing steel balls with high wear resistance as described in claim 1, characterized in that, include: S1 is prepared by converter smelting, ladle refining, RH vacuum treatment, continuous casting, and slow cooling of the billet to obtain a billet with the required chemical composition. In the later stage of the RH vacuum treatment, FeTi alloy is added to perform titanium microalloying, and the Ti content is controlled in the range of 0.10 to 0.15%. S2 heats the billet, removes phosphorus with high-pressure water, rolls it, and cools it slowly to obtain the hot-rolled round steel. The final rolling temperature is controlled to be 850-900℃ during rolling.

3. The method for hot-rolling round steel for titanium-containing steel balls with high wear resistance as described in claim 2, characterized in that, In the converter smelting process, desulfurized semi-steel is used, with S≤0.010% in the semi-steel fed into the furnace; the converter endpoint targets are C≥0.05%, P≤0.010%, and tapping temperature≥1640℃.

4. The method for hot-rolling round steel for titanium-containing steel balls with high wear resistance as described in claim 3, characterized in that, During the tapping process, a deoxidizing alloy is added to pre-deoxidize the molten steel. The alloy is added starting at 1 / 3 of the tapping volume and ending at 2 / 3 of the tapping volume. The deoxidizing alloy includes FeSi alloy, FeMn alloy, and FeCr alloy, with C controlled within the range of 0.57% to 0.64%, Si controlled within the range of 1.40% to 1.60%, Mn controlled within the range of 0.70% to 0.90%, and Cr controlled within the range of 0.70% to 0.90%.

5. The method for hot-rolling round steel for titanium-containing steel balls with high wear resistance as described in claim 2, characterized in that, In the aforementioned ladle refining process, the alkalinity at the refined outlet is controlled at 2.0 to 3.

0.

6. The method for hot-rolling round steel for titanium-containing steel balls with high wear resistance as described in claim 2, characterized in that, In the vacuum treatment process, the treatment time for a vacuum degree ≤ 3 mbar is not less than 12 min.

7. The method for hot-rolling round steel for titanium-containing steel balls with high wear resistance as described in claim 2, characterized in that, During the continuous casting process, the molten steel ladle is superheated to 20-40℃, the casting speed is constant, the billet pulling speed is ≤0.68m / min, the electromagnetic stirring current of the crystallizer is 335-350A, and the frequency is 2.4Hz; and protective casting is adopted throughout the casting process.

8. The method for hot-rolling round steel for titanium-containing steel balls with high wear resistance as described in claim 2, characterized in that, In the aforementioned slow cooling process for cast billets, the billets are stacked and cooled slowly for a period of not less than 48 hours.

9. The method for hot-rolling round steel for titanium-containing steel balls with high wear resistance as described in claim 2, characterized in that, In the heating process, the temperature of each section of the heating furnace is controlled as follows: first heating temperature 800~1100℃, second heating temperature 1000~1250℃, third heating temperature 1220~1300℃, and soaking temperature 1220~1280℃. The total heating time is not less than 210min, and the soaking time is not less than 43min.

10. The method for hot-rolling round steel for titanium-containing steel balls with high wear resistance as described in claim 2, characterized in that, In the slow cooling process, the temperature of the material entering the slow cooling pit is ≥500℃.

Images