Method for improving the hardenability stability of steel used in engineering machinery wheel bodies

Abstract

The present invention belongs to the field of metallurgy technology, and specifically relates to a method for improving the stability of hardenability of steel for wheel bodies of engineering machinery. The present invention improves the stability of hardenability of steel for wheel bodies of engineering machinery by reasonably designing the chemical composition of silicon and boron in steel, controlling the oxygen supply in converter smelting, using boron-containing silicon manganese to match silicon in place in one go during converter steel tapping, using aluminum particles and silicon carbide to deoxidize the steel slag interface in the LF refining process, appropriately increasing the argon flow rate, and adjusting the method and timing of adding ferroboron in the RH vacuum refining process. In combination with the narrow component control process, the hardenability bandwidth of steel for wheel bodies of engineering machinery can be controlled within the range of ≤4HRC, meeting the use requirements of high-end engineering machinery users, and having significant economic and social benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for improving the hardenability stability of steel for a wheel body of an engineering machinery. Background Art

[0002] The construction machinery industry is an important pillar industry for the development of my country's national economy. It plays a vital role in my country's economic construction, especially in the construction of major engineering projects and new urbanization. Crawler-type construction machinery is the main force in construction machinery equipment. The important units of its travel and support system include guide wheels, supporting rollers, sprocket wheels, drive wheels and crawler assemblies. The crawler travel mechanism relies on the drive wheel to transmit the driving force provided by the travel motor to the crawler; the guide wheel provides guidance for the rotation of the crawler chain, and adjusts the movement trajectory of the crawler to avoid derailment and deviation of the crawler during walking; the supporting roller supports the weight of the whole machine and evenly distributes the pressure on the crawler of the grounding department. Because the service conditions of crawler-type construction machinery are very harsh, the road surface is often uneven, and it is often mixed with sand, stone, coal mud, etc., so the entire travel mechanism is subjected to great impact and load, especially the supporting roller wheel body is easy to wear, and fatigue failure is easy to cause after long-term work. Among them, the wheel body is a key component, and its reliability directly affects the stability and service life of the entire four-wheel and one-belt system. This requires that the steel used to manufacture the wheel body has excellent hardenability, high hardness, wear resistance, good strength and toughness, and high fatigue resistance, among which the stability of hardenability is particularly important.

[0003] It is generally believed that carbon can improve the hardenability of steel, manganese and chromium can significantly improve the hardenability of steel, although boron can also improve the hardenability of steel in multiples, but due to the large fluctuation of the hardenability of boron steel, and the difficulty of control is large, the hardenability bandwidth of stable control of boron steel has always been the subject of research of major steel enterprises. The size of hardenability bandwidth affects the degree of heat treatment deformation to a great extent, and then has an important impact on the assembly precision and use of mechanical parts. Because the hardenability bandwidth of boron steel is generally more than 6HRC at present, the application range of boron steel is mostly track assembly, and the wheel body material requiring higher hardenability generally adopts materials such as 50Mn, 40Mn2 that are more stable, and a few adopt the material that further improves Cr content on the basis of 35MnBH to stabilize hardenability, but the use cost of materials can be increased at the same time. How to further improve the stability of hardenability of engineering machinery wheel body steel 35MnBH is the problem to be solved by the present invention. Summary of the invention

[0004] The purpose of the present invention is to address the above technical difficulties by reasonably designing the chemical composition of silicon and boron in steel, controlling the oxygen supply in converter smelting, using boron-containing silicon manganese to match silicon in place in one go during converter steelmaking, using aluminum particles and silicon carbide to deoxidize the slag interface in the LF refining process, appropriately increasing the argon flow rate, and adjusting the method and timing of adding ferroboron in the RH vacuum refining process, thereby improving the stability of the hardenability of steel for the wheel body of engineering machinery. In combination with the narrow composition control process, the hardenability bandwidth of steel for the wheel body of engineering machinery can be controlled within the range of ≤4HRC, which fully meets the use requirements of high-end engineering machinery users.

[0005] In order to achieve the above-mentioned purpose, the steel for engineering machinery wheel body involved in the present invention takes 35MnBH as an example, and its chemical composition is calculated by weight percentage as follows: [C]: 0.34-0.36%, [Si]: 0.33-0.37%, [Mn]: 1.31-1.36%, [P]≤0.025%, [S]: ≤0.025%, [Cr]: 0.18-0.22%, [Al]: 0.020-0.045%, [Ti]: 0.020-0.045%, [B]: 0.0030-0.0040%, and the rest is Fe and unavoidable impurities.

[0006] The present invention provides a method for improving the hardenability stability of steel for a wheel body of an engineering machinery, comprising the steps of converter smelting, LF refining, RH vacuum refining, continuous casting and rolling, and the specific operations are as follows:

[0007] (1) The converter uses molten iron and scrap steel as steelmaking raw materials for oxygen blowing and stirring smelting. The oxygen consumption per furnace is 5000-6500m 3 , re-blowing is prohibited, tapping [C] is controlled to be ≥ 0.10%, tapping [P] is ≤ 0.015%, tapping temperature is ≥ 1600℃, and deoxidizer, boron-containing silicon manganese, high carbon ferromanganese, high carbon ferrochrome, low carbon recarburizer and slag are added in sequence with the steel flow when 1 / 3 of the steel is tapped. The slag includes lime and slag-reducing agent;

[0008] The amount of the deoxidizer added is 200 kg / furnace of aluminum block; boron-containing silicon-manganese is added once according to the target silicon content of 0.33%, and its addition amount is 18.5-19.5 kg / t; high carbon ferromanganese is added in an amount of 0.2-0.8 kg / t; high carbon ferrochrome is added in an amount of 3.0-3.8 kg / t; the amount of slag added is 500 kg / furnace of lime and 200 kg / furnace of slag-removing agent.

[0009] The low oxygen content and high carbon steel tapping operation is used to reduce the oxidizability of molten steel. At the same time, the amount of aluminum blocks is increased to further strengthen deoxidation. Secondly, the silicon content in the molten steel is adjusted to the target value by adding boron-containing silicon-manganese at one time. Silicon generally exists in the form of solid solution in ferrite or austenite. Higher silicon can cooperate with manganese to improve hardenability and help improve the stability of hardenability. In the steel tapping process, the silicon content is adjusted to the right level by using boron-containing silicon-manganese at one time without using ferrosilicon alloy, which can reduce production costs and reduce the pressure of composition adjustment in LF refining. Finally, part of the boron in boron-containing silicon-manganese will also be oxidized and enter the molten steel and slag.

[0010] (2) The LF refining furnace is well sealed and the internal positive pressure is controlled. The LF uses aluminum particles and silicon carbide for composite deoxidation of the slag interface. The amount of aluminum particles added is 2.3-3.8 kg / t, and the amount of silicon carbide added is 1.0-1.5 kg / t. The bottom blowing argon flow rate is appropriately increased and controlled at 550-650 m 3 / h.

[0011] LF uses aluminum particles and silicon carbide for composite deoxidation of the slag interface. The gas generated by the reaction of silicon carbide and oxygen can be used to improve the foaming efficiency, and a large bottom blowing argon flow rate can be used to increase the kinetic conditions of the interface reaction. Adding more aluminum particles to deoxidize the slag surface can, on the one hand, deoxidize to generate Al2O3, and on the other hand, aluminum will reduce the boron in the slag to the molten steel, so as to form a "boron-retaining" atmosphere in the molten steel in advance.

[0012] (3) RH vacuum treatment uses argon as the boost gas, with a boost gas flow rate of 96 to 120 Nm 3 / h, vacuum degree ≤133Pa, vacuum holding time 10~15min,

[0013] Furthermore, the RH vacuum treatment process also includes the following steps: after breaking the air, first feed titanium iron wire, feed a certain amount of carbon wire according to the carbon content in the steel, and then feed an appropriate amount of silicon calcium wire, and then perform soft argon blowing operation, the soft blowing time is ≥15min, after soft blowing, ensure the appropriate hanging bag temperature, feed boron iron wire before hanging the bag, and hang the bag to put steel until continuous casting;

[0014] Preferably, the titanium iron wire feeding amount in step (3) is 320-420 m / furnace; the silicon calcium wire feeding amount is 60-120 m / furnace for the open-cast furnace and 40-80 m / furnace for the continuous casting furnace; the bag temperature after soft blowing is 1567-1597° C. for the open-cast furnace and 1542-1572° C. for the continuous casting furnace;

[0015] The ferroboron wire is fed before the hanging bag, according to the target boron content of 0.0035%, and the feeding amount is 110m-140m / furnace; the boron content of the ferroboron wire is ≥16%, the wire diameter is 13mm, and the powder particle size is 0-5mm.

[0016] Since the diffusion rate of boron in molten steel is very fast, the boron iron wire with fine inner core particle size can be directly fed before the ladle is hung, and it will not affect the uniformity of boron distribution in the steel. At this time, the molten steel has been LF refined, RH high vacuum treated, wire fed, soft blown, deoxidation and nitrogen fixation are completed, and oxygen and nitrogen are at extremely low levels. Boron is directly fed into the molten steel in the form of cored wire, which improves the utilization rate of boron. After entering the molten steel, most of the boron will exist in the form of solid solution boron. At the same time, the total boron content is designed to be 0.0030% to 0.0040%, which can further ensure the solid solution boron content in the molten steel, prevent the threat of oxygen absorption and nitrogen increase in the continuous casting process to the existence of effective boron, and improve the stability of hardenability.

[0017] (4) The continuous casting process adopts full protection casting, the long water inlet of the large ladle is sealed with argon, the argon filling and exhaust time of the middle ladle before pouring is ≥5min, and argon gas pipes are placed in the impact area of ​​the middle ladle and the plug hole;

[0018] Furthermore, the continuous casting tundish adopts an integral coating material or a dry material plug rod tundish, uses a Vesuvius magnesium plug rod and an immersed nozzle, adopts reasonable superheat and constant pulling speed control, the superheat is controlled at 20-40°C, and the pulling speed is controlled at 0.95±0.05m / min; the crystallizer electromagnetic stirring parameter is 200A / 2.5Hz, the sinusoidal vibration parameter is amplitude ±2.5mm, frequency 130+40V opm, the crystallizer electromagnetic stirring parameter is 80A / 6.0Hz, and the crystallizer protective slag is used;

[0019] Preferably, the crystallizer protective slag in step (4) uses special protective slag for anchor chain steel, with a total carbon content of 16-20%, an F content of 2.5-4%, a CaO content of 22-28%, a SiO2 content of 22-30%, an Al2O3 content of 7-12%, a basicity of R=0.90-1.0, and a moisture content of ≤0.3%.

[0020] Measures such as full-process protective casting, argon sealing of the long water nozzle of the large ladle, and argon filling and exhaust of the middle ladle before pouring can avoid secondary oxidation of the molten steel and prevent the molten steel from absorbing nitrogen.

[0021] (5) The rolling process uses high-pressure water to remove phosphorus at a pressure of 18MPa to 25MPa to ensure that the surface oxide scale of the continuous casting billet is completely removed; the preheating section temperature is 800-900℃, the soaking section temperature is 1130-1180℃, the start rolling temperature is 1050-1130℃, the final rolling temperature is ≤920℃, the shearing temperature is 200-500℃, the total heating time is 2.5-4h, and the steel-out rhythm is 82-160s / roll.

[0022] The beneficial effects of the present invention are:

[0023] The present invention effectively improves the stability of the hardenability of steel for the wheel body of engineering machinery through reasonable chemical composition design, selection of process route and optimization of process parameters, thereby achieving the purpose of reducing its hardenability bandwidth. Combined with the narrow composition control process, the hardenability bandwidth of steel for the wheel body of engineering machinery can be controlled within the range of ≤4HRC, which fully meets the use requirements of high-end engineering machinery users.

[0024] Compared with the existing process technology, the process of the present invention adopts measures such as reasonably designing the chemical composition of silicon and boron in steel, controlling the oxygen supply during converter smelting, using boron-containing silicon manganese to match silicon in place in one go during converter steelmaking, using aluminum particles and silicon carbide to deoxidize the steel slag interface in the LF refining process, appropriately increasing the argon gas flow rate, and adjusting the boron iron adding method and timing in the RH vacuum refining process, thereby improving the stability of the hardenability of steel for the wheel body of engineering machinery, reducing its hardenability bandwidth, improving the market competitiveness of the product, and having significant economic and social benefits. DETAILED DESCRIPTION

[0025] The present invention is not limited to the following specific embodiments. A person skilled in the art can implement the present invention in various other specific embodiments according to the contents disclosed in the present invention, or any simple changes or modifications made to the design structure and ideas of the present invention fall within the protection scope of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0026] The present invention is further described in detail below in conjunction with embodiments:

[0027] The production process is briefly described as follows:

[0028] Converter smelting → LF refining → RH vacuum refining → continuous casting (220×260mm 2 )→Rolling.

[0029] Taking 35MnBH as an example, its chemical composition is calculated by weight percentage: [C]: 0.34~0.36%, [Si]: 0.33~0.37%, [Mn]: 1.31~1.36%, [P]≤0.025%, [S]: ≤0.025%, [Cr]: 0.18~0.22%, [Al]: 0.020~0.045%, [Ti]: 0.020~0.045%, [B]: 0.0030~0.0040%, and the rest is Fe and unavoidable impurities.

[0030] Example 1

[0031] (1) The converter uses molten iron and scrap steel as steelmaking raw materials for oxygen blowing and stirring smelting. The molten iron accounts for 85% of the total weight of the steelmaking raw materials, and the scrap steel accounts for 15% of the total weight of the steelmaking raw materials. The total loading amount is 140t / furnace, and the oxygen consumption is 5500m3 , no supplementary blowing, tapping [C] 0.12%, tapping [P] 0.013%, tapping temperature 1615 ℃, when 1 / 3 of the steel is tapped, add deoxidizer aluminum block 200kg / furnace, boron silicon manganese (Si ≥ 17%, Mn ≥ 65%, B ≥ 0.050%) 19kg / t, high carbon ferromanganese 0.5kg / t, high carbon ferrochrome 3.6kg / t, low carbon recarburizer and slag lime 500kg / furnace, slag reducing agent 200kg / furnace in sequence with the steel flow;

[0032] (2) The LF refining furnace is well sealed and the internal pressure is controlled to be slightly positive. 3.2 kg / t of aluminum particles and 1.2 kg / t of silicon carbide are added to the LF for composite deoxidation of the slag interface. The bottom blowing argon flow rate is controlled at 600 m 3 / h;

[0033] (3) RH vacuum treatment uses argon as the boost gas, with a boost gas flow rate of 100 Nm 3 / h, vacuum degree ≤133Pa, vacuum holding time 12min; after breaking the air, first feed titanium iron wire 350m / furnace, then feed silicon calcium wire 80m / furnace, then carry out soft argon blowing operation, soft blowing time 18min, after soft blowing, the hanging bag temperature is 1550℃, before hanging the bag, feed boron iron wire 120m / furnace (B ≥16%, boron iron wire meter weight 0.35kg, wire diameter 13mm, powder particle size 0-5mm), then hang the bag to load steel to continuous casting;

[0034] (4) The continuous casting process adopts full-process protective casting, the long water inlet of the large ladle is sealed with argon, the tundish is filled with argon and vented for 6 minutes before pouring, and argon pipes are placed in the impact zone and stopper hole of the tundish; the continuous casting tundish adopts an integral dry material stopper, uses Vesuvius magnesium stopper and immersed water inlet, the superheat is controlled at 27°C, and the casting speed is controlled at 0.95±0.05m / min; the electromagnetic stirring parameters of the crystallizer are 200A / 2.5Hz, the sinusoidal vibration parameters are amplitude±2.5mm, frequency 130+40V opm, the electromagnetic stirring parameters of the crystallizer are 80A / 6.0Hz, and special protective slag for anchor chain steel is used, with a total carbon content of 17%, F content of 2.8%, CaO content of 24%, SiO2 content of 25%, Al2O3 content of 9%, basicity of R=0.96, and moisture of 0.06%.

[0035] (5) The rolling process uses high-pressure water to remove phosphorus with a pressure of 20 MPa to ensure that the surface oxide scale of the continuous casting billet is completely removed; the preheating section temperature is 840°C, the soaking section temperature is 1165°C, the start rolling temperature is 1070°C, the final rolling temperature is 830°C, the shearing temperature is 295°C, the total heating time is 3.2 h, and the steelmaking rhythm is 120 s / roll.

[0036] Example 2

[0037] Oxygen consumption in converter process 6000m3 , the steel tapping temperature is 1610°C, 60m / furnace of silicon-calcium wire is fed into the RH vacuum treatment process, the ladle temperature after soft blowing is 1552°C, the superheat degree in the continuous casting process is 30°C, and the other operations are the same as in Example 1.

[0038] Example 3

[0039] In the LF refining process, the amount of aluminum particles used was 3.6 kg / t and the amount of silicon carbide used was 0.8 kg / t. The rest of the operations were the same as in Example 1.

[0040] Example 4

[0041] In the rolling process, the soaking section temperature is 1178°C, the start rolling temperature is 1090°C, the final rolling temperature is 875°C, and the remaining operations are the same as in Example 1.

[0042] Comparative Example 1

[0043] The step (1) of Example 1 in which "19 kg / t of boron-containing silicon-manganese (Si≥17%, Mn≥65%, B≥0.050%) is added" is replaced by "19 kg / t of silicon-manganese (Si≥17%, Mn≥65%, B content 0.020%) is added", and other conditions are the same as those of Example 1.

[0044] Comparative Example 2

[0045] The step (1) of Example 1 in which "19 kg / t of boron-containing silicon manganese (Si≥17%, Mn≥65%, B≥0.050%) and 0.5 kg / t of high carbon ferromanganese are added" is replaced by "12 kg / t of boron-containing silicon manganese (Si≥17%, Mn≥65%, B≥0.050%) and 8.5 kg / t of high carbon ferromanganese are added", and other conditions are the same as in Example 1.

[0046] Comparative Example 3

[0047] In step (2) of Example 1, "3.2 kg / t of aluminum particles and 1.2 kg / t of silicon carbide are added to LF to carry out composite deoxidation at the steel slag interface" is replaced with "1.5 kg / t of aluminum particles and 2.9 kg / t of silicon carbide are added to LF to carry out composite deoxidation at the steel slag interface", and other conditions are the same as in Example 1.

[0048] Comparative Example 4

[0049] The feeding order of the boron iron wire (120 m / furnace) in step (3) of Example 1 was adjusted to before the soft argon blowing, and the other conditions were the same as in Example 1.

[0050] Comparative Example 5

[0051] The step (3) of Example 1 in which "120 m of ferroboron wire is fed into the furnace before the ladle is hung" is replaced by "90 m of ferroboron wire is fed into the furnace before the ladle is hung", and the other conditions are the same as those in Example 1.

[0052] The chemical composition and hardenability of the steels prepared in Examples 1 to 4 and Comparative Examples 1 to 5 are shown in Tables 1-2, respectively.

[0053] Table 1 Chemical composition of finished steels prepared in Examples 1 to 4 and Comparative Examples 1 to 5 (wt / %)

[0054] Element C Si Mn P S Cr Al Ti B Example 1 0.35 0.35 1.33 0.015 0.008 0.20 0.028 0.030 0.0036 Example 2 0.34 0.35 1.34 0.017 0.010 0.21 0.029 0.032 0.0038 Example 3 0.35 0.34 1.35 0.015 0.007 0.21 0.032 0.029 0.0032 Example 4 0.35 0.35 1.33 0.014 0.008 0.19 0.028 0.034 0.0036 Comparative Example 1 0.35 0.35 1.33 0.015 0.008 0.20 0.028 0.030 0.0036 Comparative Example 2 0.35 0.25 1.33 0.015 0.008 0.20 0.028 0.030 0.0036 Comparative Example 3 0.35 0.35 1.33 0.015 0.008 0.20 0.028 0.030 0.0036 Comparative Example 4 0.35 0.35 1.33 0.015 0.008 0.20 0.028 0.030 0.0032 Comparative Example 5 0.35 0.35 1.33 0.015 0.008 0.20 0.028 0.030 0.0025

[0055] Table 2 Hardenability (HRC) of steels prepared in Examples 1 to 4 and Comparative Examples 1 to 5

[0056] Hardenability value J1.5 J8 J19 Example 1 53.9～56.1 52.1～54.5 35.5～38.8 Example 2 53.8～56.2 51.8～54.6 35.3～38.6 Example 3 54.2～56.2 52.1～54.7 35.6～39.1 Example 4 53.8～56.1 52.0～54.5 35.3～38.9 Comparative Example 1 53.2～56.1 50.4～54.4 32.9～38.7 Comparative Example 2 53.0～55.9 50.1～54.3 32.6～38.5 Comparative Example 3 53.4～56.1 50.1～54.4 33.0～38.8 Comparative Example 4 52.7～55.8 49.8～54.1 32.3～37.8 Comparative Example 5 53.2～56.0 49.8～54.4 32.5～38.4

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for improving the hardenability stability of steel for a wheel body of an engineering machinery, characterized in that: It includes converter smelting, LF refining, RH vacuum refining, continuous casting and rolling process steps. The specific operations are: (1) The converter uses molten iron and scrap steel as steelmaking raw materials for oxygen blowing and stirring smelting. The oxygen consumption per furnace is 5000-6500m 3 , reblowing is prohibited, tapping [C] is controlled to be ≥ 0.10%, tapping [P] is ≤ 0.015%, tapping temperature is ≥ 1600°C, deoxidizer, boron-containing silicon manganese, high carbon ferromanganese, high carbon ferrochrome, low carbon carburizer and slag are added in sequence with the steel flow when 1 / 3 of the steel is tapped, and the slag includes lime and slag-reducing agent; the boron-containing silicon manganese contains Si ≥ 17%, Mn ≥ 65%, and B ≥ 0.050%, and the boron-containing silicon manganese is added at one time according to the target silicon content; (2) The LF refining furnace is well sealed, the furnace is slightly positively pressurized, aluminum particles and silicon carbide are used for deoxidation of the slag interface, argon is blown from the bottom and the argon flow rate is increased; the amount of aluminum particles added is 2.3-3.8 kg / t, and the amount of silicon carbide added is 1.0-1.5 kg / t; (3) RH vacuum treatment uses argon as the lifting gas, and the lifting gas flow rate is 96~120Nm 3 / h, vacuum degree ≤133Pa, vacuum holding time 10~15min; after breaking the air, first feed titanium iron wire, feed carbon wire according to the carbon content in the steel, and then feed an appropriate amount of silicon calcium wire, followed by soft argon blowing operation, the soft blowing time ≥15min, after soft blowing, ensure that the temperature of the hanging bag is higher than the liquidus line of the molten steel by 45~100℃, feed boron iron wire before hanging the bag, and put the steel on the hanging bag until continuous casting; (4) The continuous casting process adopts full-process protective casting, the long water inlet of the large ladle is sealed with argon, the middle ladle is filled with argon and exhausted before pouring, the continuous casting middle ladle adopts an integral coating material or a dry material plug rod middle ladle, and uses Vesuvius magnesium plug rods and immersed water inlets; the superheat is controlled at 20-40°C, and the casting speed is controlled at 0.95±0.05m / min; the crystallizer adopts electromagnetic stirring, sinusoidal vibration mode, uses crystallizer protection slag, and adopts end electromagnetic stirring; (5) The rolling process uses high-pressure water descaling with a pressure of 18MPa to 25MPa to ensure that the oxide scale on the surface of the continuous casting billet is completely removed; the preheating section temperature is 800 to 900°C, the soaking section temperature is 1130 to 1180°C, the start rolling temperature is 1050 to 1130°C, the final rolling temperature is ≤920°C, the shearing temperature is 200 to 500°C, the total heating time is 2.5 to 4h, and the steel-out rhythm is 82 to 160s / roll; The steel for the wheel body of engineering machinery is 35MnBH, and its chemical composition is calculated by weight percentage as follows: [C]: 0.34-0.36%, [Si]: 0.33-0.37%, [Mn]: 1.31-1.36%, [P]≤0.025%, [S]: ≤0.025%, [Cr]: 0.18-0.22%, [Al]: 0.020-0.045%, [Ti]: 0.020-0.045%, [B]: 0.0030-0.0040%, and the rest is Fe and unavoidable impurities.

2. The method for improving the hardenability stability of the engineering machinery wheel steel according to claim 1, characterized in that: In step (1), the amount of deoxidizer added is 200 kg / furnace of aluminum block; the amount of boron-containing silicon-manganese added is 18.5-19.5 kg / t; the amount of high-carbon ferromanganese added is 0.2-0.8 kg / t; the amount of high-carbon ferrochrome added is 3.0-3.8 kg / t; the amount of slag added is 500 kg / furnace of lime and 200 kg / furnace of slag-removing agent.

3. The method for improving the hardenability stability of the engineering machinery wheel steel according to claim 1, characterized in that: In step (2), the argon flow rate is controlled at 550-650m 3 / h.

4. The method for improving the hardenability stability of the engineering machinery wheel steel according to claim 1, characterized in that: The feeding amount of the titanium iron wire in step (3) is 320-420 m / furnace; the feeding amount of the silicon calcium wire is 60-120 m / furnace for the open-cast furnace and 40-80 m / furnace for the continuous casting furnace; the temperature of the hanging bag after soft blowing is 1567-1597°C for the open-cast furnace and 1542-1572°C for the continuous casting furnace.

5. The method for improving the hardenability stability of the engineering machinery wheel steel according to claim 1, characterized in that: The ferroboron wire in step (3) is fed before the hanging bag according to the target boron content, and the feeding amount is 110m~140m / furnace; B in the ferroboron wire is ≥16%, the wire diameter is 13mm, and the powder particle size is 0~5mm.

6. The method for improving the hardenability stability of the engineering machinery wheel steel according to claim 1, characterized in that: In step (4), the argon filling and exhaust time of the tundish before pouring is ≥5 minutes, and argon tubes are placed in the impact zone of the tundish and the stopper hole; the electromagnetic stirring parameters of the crystallizer are 200A / 2.5Hz, the sinusoidal vibration parameters are amplitude ±2.5mm, and frequency 130+40V opm.

7. The method for improving the hardenability stability of the engineering machinery wheel steel according to claim 1, characterized in that: The mold protection slag in step (4) uses a special protection slag for anchor chain steel, with a total carbon content of 16-20%, an F content of 2.5-4%, a CaO content of 22-28%, a SiO2 content of 22-30%, an Al2O3 content of 7-12%, a basicity of R=0.90-1.0, and a moisture content of ≤0.3%.