CN115125449B - High-hardenability profile steel for ultra-large engineering machinery caterpillar band and production method thereof - Google Patents

High-hardenability profile steel for ultra-large engineering machinery caterpillar band and production method thereof Download PDF

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CN115125449B
CN115125449B CN202210783391.3A CN202210783391A CN115125449B CN 115125449 B CN115125449 B CN 115125449B CN 202210783391 A CN202210783391 A CN 202210783391A CN 115125449 B CN115125449 B CN 115125449B
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percent
steel
hardenability
equal
ultra
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CN115125449A (en
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王刚
霍喜伟
纪进立
刘昀嘉
宋玉卿
叶飞来
李承�
孙晓庆
孙鹏鹏
李忠
刘泽磊
孔令坤
肖强
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Shandong Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/08—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling structural sections, i.e. work of special cross-section, e.g. angle steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/114—Treating the molten metal by using agitating or vibrating means
    • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/18—Controlling or regulating processes or operations for pouring
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C21C2007/0018—Boron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Physics & Mathematics (AREA)
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  • Heat Treatment Of Steel (AREA)

Abstract

The invention discloses a high-hardenability section steel for a super-large engineering machinery crawler belt and a production method thereof, wherein the section steel for the crawler belt comprises the following chemical components in percentage by weight: 0.23 to 0.30 percent of C, 0.15 to 0.35 percent of Si, 1.05 to 1.35 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.015 percent of S, 0.60 to 0.90 percent of Cr, 0.0010 to 0.0030 percent of B, 0.015 to 0.055 percent of Ti, 0.01 to 0.06 percent of Al, and the balance of iron and unavoidable impurities. The steel provided by the invention improves the hardenability and meets the requirements of strength, toughness and service fatigue life of the steel for the ultra-large excavator crawler belt after heat treatment.

Description

High-hardenability profile steel for ultra-large engineering machinery caterpillar band and production method thereof
Technical Field
The invention belongs to the technical field of section steel production, and particularly relates to high-hardenability section steel for a super-large engineering machinery crawler belt and a production method thereof.
Background
The crawler belt is a traveling system of engineering machinery, and is commonly used in engineering machinery such as an excavator, a bulldozer and the like. The profile steel for the hot-rolled track mainly comprises single-tooth track steel, two-tooth track steel and three-tooth track steel according to the appearance, wherein the single-tooth track steel is shown in a schematic view in FIG. 1, the two-tooth track steel is shown in a schematic view in FIG. 2, and the three-tooth track steel is shown in a schematic view in FIG. 3; the pitch covers 135 mm-228 mm,135 mm-190 mm pitch track steel is used for medium and small engineering machinery, and 203 mm-228 mm track steel is used for large engineering machinery.
With the increasing demands of large mines, projects and the like on the working efficiency, the engineering machinery gradually develops towards the ultra-large direction. Based on complex geotechnical working conditions and the large dead weight characteristic of over 100 tons of ultra-large engineering machinery, the crawler belt is required to have high strength, high toughness, high wear resistance and high fatigue life in order to improve the working efficiency by combining the advancing type working characteristics of the engineering machinery.
In the design of ultra-large engineering machinery, the meter weight of the steel section for the track exceeds 100kg/m, the sectional area is more than 2 times of the sectional area of the steel section for the track with the existing maximum pitch, and the tooth height and the tooth thickness of the working teeth are far greater than those of the existing track steel. The existing materials are difficult to meet the requirements of the quenching degree of the section steel for the ultra-large engineering machinery caterpillar band, and the mechanical property and the fatigue life of the operation process after heat treatment cannot be ensured.
Therefore, the design of the chemical composition system for the ultra-large type engineering machinery caterpillar band improves the hardenability of materials, meets the requirements of high strength and high wear resistance, and improves the service life in the operation process, which is a technical problem to be solved in the present urgent need.
Disclosure of Invention
The technical problem solved by the invention is to provide the high-hardenability section steel for the ultra-large engineering machinery caterpillar band, and the section steel for the caterpillar band has excellent hardenability and can meet the use requirements of the ultra-large engineering machinery caterpillar band such as high strength, high wear resistance, long fatigue life and the like.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the high-hardenability profile steel for the ultra-large engineering machinery crawler belt comprises the following chemical components in percentage by weight: 0.23 to 0.30 percent of C, 0.15 to 0.35 percent of Si, 1.05 to 1.35 percent of Mn, less than or equal to 0.030 percent of P, less than or equal to 0.015 percent of S, 0.60 to 0.90 percent of Cr, 0.0010 to 0.0030 percent of B, 0.015 to 0.055 percent of Ti, 0.01 to 0.06 percent of Al, and the balance of iron and trace impurities.
The pitch of the high-hardenability profile steel for the ultra-large type engineering machinery caterpillar track provided by the invention is more than 300, and the teeth are formedThe thickness is greater than or equal to 50mm, the tooth height is greater than or equal to 100mm, the web thickness is greater than or equal to 25mm, and the cross section area is greater than or equal to 130cm 2 。
As a preferred embodiment, the high hardenability section steel for the ultra-large type engineering machinery caterpillar comprises the following chemical components in percentage by weight: 0.24 to 0.29 percent of C, 0.15 to 0.30 percent of Si, 1.15 to 1.30 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.010 percent of S, 0.65 to 0.80 percent of Cr, 0.0015 to 0.0030 percent of B, 0.025 to 0.055 percent of Ti, 0.020 to 0.050 percent of Al, and the balance of iron and unavoidable impurities.
The design of the high-hardenability steel chemical composition for the ultra-large type engineering machinery caterpillar band is based on the following mechanism:
c: c is a main element for improving strength in steel, the content of C mainly determines the hardenability of the steel, and the hardenability of C on the steel is an important factor, but C also has a great adverse effect on the plasticity and toughness of the steel. In the hypoeutectoid steel to which the track section steel belongs, the austenite grains tend to coarsen due to the increase of the C content, and the austenite grain size of the track section steel is low due to the excessively high C content, so that the hardenability can be improved, but the track section steel is extremely easy to break in the heat treatment process and the subsequent use, and the service life is reduced. Therefore, the C content is controlled to be 0.23 to 0.30%.
Si: si is an element in steel which is dissolved in iron, and Si mainly improves the stability of supercooled austenite of carbon steel in a medium temperature region, and has little influence on a high temperature region, even reduces the stability. Si also increases the decarburization tendency of the steel surface, and the caterpillar section steel requires control of the decarburized layer thickness, and Si is required to be controlled at a low content. Therefore, the Si content is controlled to be 0.15 to 0.35%.
Mn: mn is an element which strongly improves the hardenability of steel, dissolves in austenite, promotes the low-temperature transformation curve of austenite to move rightward, increases the stability of austenite and decreases the critical cooling rate, thereby improving the hardenability of steel, but when Mn and S elements are combined to form MnS, the hardenability is lowered, so that it is necessary to control the S content in steel to be less than or equal to 0.010% at the same time. When the Mn content is less than 1.0%, the mechanical property and hardenability of the material are difficult to meet the design requirement of the steel for the ultra-large type engineering machinery caterpillar band, but too high C content can increase the coarsening tendency of crystal grains, increase the tempering brittleness of the steel, and cause quenching deformation beyond a certain content. In comprehensive consideration, the Mn content is controlled to be 1.05-1.35%.
Cr: cr exists in the form of solid solution and various carbides in the steel, and can obviously improve the hardenability, corrosion resistance and wear resistance of the material. Cr forms dispersed carbide in steel, and has pinning effect in grain boundary to prevent grain boundary migration and austenite grain growth, and this effect makes the track steel for very large engineering machinery realize austenite grain refinement control in small compression ratio rolling condition. The hardenability and austenite grain refinement requirements of the steel are combined, and the Cr content is determined to be 0.60-0.90%. This is also one of the innovative points of the present invention.
Ti: ti is extremely easy to combine with N, and mainly plays a role in fixing nitrogen in steel, so that the effective utilization rate of B element is ensured; however, too high a Ti content results in Ti and C forming high melting TiC, resulting in a decrease in hardenability. So the Ti content is controlled at Ti:0.015 to 0.065 percent.
B: b is a strong hardenability element, the hardenability can be obviously improved by adding trace B into the steel, when the B content in the steel is 0.0005-0.0030%, the hardenability of the steel can be improved in multiple, but the B content exceeds 0.0035%, and the influence on the hardenability shows a decreasing trend. Therefore, the B content is controlled to be 0.0010 to 0.0030%.
N: with the increase of the N content, the strength of the steel can be obviously improved, the plasticity, particularly the toughness, is obviously reduced, the weldability is poor, and the cold brittleness is increased; and the ageing tendency, cold brittleness and hot brittleness are increased, the welding performance and cold bending performance of the steel are damaged, and the nitrogen content in the steel should be reduced and limited as much as possible. Thus, the production method of the invention can control the N content to be within 0.004 percent.
O: the increase in the O content can reduce the plasticity and toughness of the steel, and can greatly increase the number and size of nonmetallic inclusions mainly containing oxides in the steel, thereby reducing the fatigue life of the material. The invention and the production process can control the O content within 0.0015 percent.
H: h in solid steel mostly diffuses into fiber pores, around inclusions, etc., and after aggregation, causes internal stress in the steel. During hot working, H-containing pores in steel elongate in the machine direction to form cracks, causing a decrease in strength, plasticity, impact toughness of the steel, and are known in the industry as "hydrogen embrittlement". Reducing the H content in the steel can effectively improve the hot workability and the service life of the steel. The production method of the invention controls H within 0.0002 percent.
The invention also provides a production method of the high-hardenability section steel for the ultra-large type engineering machinery caterpillar band, which comprises the steps of ultra-high power electric arc furnace smelting, LF refining, VD vacuum treatment, continuous casting and rolling;
the method comprises the following steps:
smelting and continuous casting: the electric furnace adopts high molten iron raw material proportion, the molten iron sulfur content is controlled to be less than or equal to 0.010 percent, aluminum deoxidation is adopted in the tapping process, and the oxygen content in steel is strictly controlled; LF refining adopts high alkalinity refining slag proportion, enhances desulfurization operation, and sequentially carries out denitrification, inclusion modification and boron microalloying after deep deoxidation, and slag surface micro-motion small argon stirring is adopted before the LF refining is out of the station to promote nonmetallic inclusion floating removal; vacuum processing by adopting VD; in the continuous casting step, the immersed nozzle is adopted for full protection casting, secondary oxidation and nitrogen absorption of molten steel are reduced, the superheat degree is controlled, and the crystallizer and the tail end are adopted for electromagnetic stirring, so that segregation and internal defects are reduced, and the continuous casting blank production with the section size of 260mm multiplied by 300mm is realized.
The rolling process comprises the following steps: the rolling heating temperature is 1180-1260 ℃, the rolling process adopts 2 times of descaling, the primary descaling pressure is more than or equal to 26MPa, the secondary descaling pressure is more than or equal to 16MPa, the final rolling temperature of a web is controlled to be not more than 900 ℃, the cooling temperature gradient and the cooling rate of the product after rolling are reduced, the generation of brittle phases such as Wistatten tissue, granular bainite and the like is avoided, and the tissue after rolling is pearlite and ferrite.
The end hardenability of the product obtained by adopting the high-hardenability section steel for the ultra-large engineering machinery caterpillar band and the production method provided by the invention meets J1.5=46-54 HRC, J13=38-50 HRC and J25=28-40 HRC, and the common caterpillar band equivalent heat treatment process is adopted, so that the high-strength, high-toughness and wear-resistant comprehensive performance of the product is ensured.
Compared with the prior art, the core point of the invention can improve the inner or core heat treatment performance of the oversized and ultra-thick track steel, and the improvement of the performance can be reflected in the terminal hardenability, especially the improvement of J13 and J25.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, through reasonable chemical composition design, the hardenability of the material is improved, so that the technical requirements of high strength, high toughness and high wear resistance of the ultra-large engineering machinery caterpillar band are met under the same heat treatment process under the condition that the section size, tooth height, tooth thickness and the like of the ultra-large engineering machinery caterpillar band are far superior to those of the existing caterpillar band.
In the production method, a series of smelting technologies for improving the cleanliness are adopted, so that harmful gases such as nitrogen, hydrogen, oxygen and the like are effectively controlled to be low in content, nonmetallic inclusions in steel are reduced, the cleanliness of the steel is improved, and the fatigue life of the section steel for the ultra-large type engineering machinery caterpillar band is prolonged.
In the material design, cr is used as an important element for improving hardenability and refining austenite grains, and the small compression ratio rolling of the steel section for the ultra-large type engineering machinery caterpillar band is realized based on the Cr.
Due to the influence of Cr content improvement, the cooling process of the steel for the crawler belt is more likely to generate brittle phases such as Wittig tissues, granular bainite and the like, and the subsequent processing process is likely to generate defects such as cracks and the like, thereby influencing the application of users. The production method of the invention controls the final rolling temperature, cooling after rolling and the like, and eliminates the influence.
Drawings
FIG. 1 is a schematic structural view of a section steel for a single-tooth track;
FIG. 2 is a schematic structural view of a section steel for a two-tooth track;
fig. 3 is a schematic structural view of a section steel for a three-tooth crawler belt.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments.
The chemical composition pair ratio of the high-hardenability section steel for the ultra-large engineering machinery caterpillar band and the section steel for the medium-and-small-specification caterpillar band used in the prior art is shown in table 1:
TABLE 1 chemical composition vs. wt%
Examples 1 to 3
The following production method is adopted to prepare the high-hardenability section steel for the ultra-large type engineering machinery caterpillar tracks with the same specification as the examples 1-3:
(1) Smelting and continuous casting: the electric furnace adopts high molten iron raw material proportion, the molten iron sulfur content is controlled to be less than or equal to 0.010 percent, aluminum deoxidation is adopted in the tapping process, and the oxygen content in steel is strictly controlled; LF refining adopts high alkalinity refining slag proportion, enhances desulfurization operation, and sequentially carries out denitrification, inclusion modification and boron microalloying after deep deoxidation, and slag surface micro-motion small argon stirring is adopted before the LF refining is out of the station to promote nonmetallic inclusion floating removal; vacuum processing by adopting VD; in the continuous casting step, the immersed nozzle is adopted for full protection casting, secondary oxidation and nitrogen absorption of molten steel are reduced, the superheat degree is controlled, and the crystallizer and the tail end are adopted for electromagnetic stirring, so that segregation and internal defects are reduced, and the continuous casting blank production with the section size of 260mm multiplied by 300mm is realized.
(2) The rolling process comprises the following steps: the rolling heating temperature is 1180-1260 ℃, the rolling process adopts 2 times of descaling, the primary descaling pressure is more than or equal to 26MPa, the secondary descaling pressure is more than or equal to 16MPa, the final rolling temperature of a web is controlled to be not more than 930 ℃, the cooling temperature gradient and the cooling rate of the product after rolling are reduced, the generation of brittle phases such as Wistatten tissue, granular bainite and the like is avoided, and the tissue after rolling is pearlite and ferrite.
TABLE 2 chemical composition (wt%) of high hardenability section steel for ultra-large industrial machinery crawler prepared in examples 1-3
Sampling and processing are carried out on the section steel for the caterpillar tracks prepared in the examples 1-3, the terminal hardenability is checked according to GB/T225, the normalizing temperature is 900+/-10 ℃, the normalizing heat preservation time is 30-35 min, and the quenching temperature is 870+/-5 ℃. The conventional test of the hardenability of the tail end of the comparative steel grade only detects J1.5 and J11, and the invention detects indexes J13 and J25 of the hardenability of the tail end of the comparative steel grade for comparison effect. The end hardenability data of the track section steel produced by the invention and the prior art are shown in table 3.
TABLE 3 example 1-3 end hardenability data for section steel for crawler belt
As can be seen from Table 3, the present invention has higher end hardenability, especially a great improvement in J13 and J25, compared with the conventional specification track section steel to which the comparative steel grade is applied; under the same heat treatment process as that of the conventional steel section for the track, the steel section for the track of the ultra-large engineering machinery with large sectional area and large thickness can meet the technical requirements of high strength, high toughness and wear resistance, is applied to engineering machinery such as ultra-large excavators and bulldozers which work under complex rock-soil working conditions, has good user experience, excellent performance, stable use and obviously prolonged service life.
The method can be realized by the upper and lower limit values of the interval and the interval value of the process parameters (such as temperature, time and the like), and the examples are not necessarily listed here.
The invention may be practiced without these specific details, using any knowledge known in the art.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the appended claims.

Claims (4)

1. The high-hardenability profile steel for the ultra-large engineering machinery caterpillar is characterized by comprising the following chemical components in percentage by weight: 0.23 to 0.30 percent of C, 0.15 to 0.35 percent of Si, 1.05 to 1.35 percent of Mn, less than or equal to 0.030 percent of P, less than or equal to 0.015 percent of S, 0.60 to 0.90 percent of Cr, 0.0010 to 0.0030 percent of B, 0.015 to 0.055 percent of Ti, 0.01 to 0.06 percent of Al, and the balance of iron and trace impurities;
the end hardenability of the high-hardenability section steel for the ultra-large type engineering machinery caterpillar band meets J1.5=46-54 HRC, J13=38-50 HRC and J25=28-40 HRC;
the track pitch of the ultra-large type engineering machinery track is greater than 300, the tooth thickness is greater than or equal to 50mm, the tooth height is greater than or equal to 100mm, the web thickness is greater than or equal to 25mm, and the sectional area is greater than or equal to 130cm 2 。
2. The high hardenability section steel for a super-huge construction machinery crawler belt according to claim 1, wherein the weight percentage of the chemical components of the high hardenability section steel for a super-huge construction machinery crawler belt is: 0.24 to 0.29 percent of C, 0.15 to 0.30 percent of Si, 1.15 to 1.30 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.010 percent of S, 0.65 to 0.80 percent of Cr, 0.0015 to 0.0030 percent of B, 0.025 to 0.055 percent of Ti, 0.020 to 0.050 percent of Al, and the balance of iron and unavoidable impurities.
3. A method of producing a high hardenability profile steel for a very large scale construction machinery crawler of claim 1, the production method comprising ultra high power electric arc furnace smelting + LF refining + VD vacuum treatment + continuous casting + rolling;
wherein, in smelting, the electric furnace adopts high molten iron raw material proportion, the sulfur content of molten iron is controlled to be less than or equal to 0.010 percent, the tapping process adopts aluminum deoxidation, and the oxygen content in steel is strictly controlled; LF refining adopts high alkalinity refining slag proportion, enhances desulfurization operation, and sequentially carries out denitrification, inclusion modification and boron microalloying after deep deoxidation, and slag surface micro-motion small argon stirring is adopted before the LF refining is out of the station to promote nonmetallic inclusion floating removal; vacuum processing by adopting VD; in the continuous casting step, the immersed nozzle is adopted for full protection casting, secondary oxidation and nitrogen absorption of molten steel are reduced, the superheat degree is controlled, and the crystallizer and the tail end are adopted for electromagnetic stirring, so that segregation and internal defects are reduced, and the continuous casting blank production with the section size of 260mm multiplied by 300mm is realized.
4. The method according to claim 3, wherein the heating temperature is 1180-1260 ℃ in the rolling process, the rolling process adopts 2 times of descaling, the primary descaling pressure is more than or equal to 26MPa, the secondary descaling pressure is more than or equal to 16MPa, the final rolling temperature of the web is controlled to be no more than 930 ℃, the cooling temperature gradient and the cooling rate of the product after rolling are reduced, the production of Wittig tissue and granular bainite is avoided, and the tissue after rolling is pearlite+ferrite.
CN202210783391.3A 2022-07-05 2022-07-05 High-hardenability profile steel for ultra-large engineering machinery caterpillar band and production method thereof Active CN115125449B (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101654761A (en) * 2009-05-25 2010-02-24 莱芜钢铁股份有限公司 Carbon-manganese composite microalloyed steel for engineering machinery and preparation method thereof
CN109321712A (en) * 2018-11-08 2019-02-12 江阴兴澄特种钢铁有限公司 A kind of high-hardenability carburized gears 20CrNiB steel
CN111961977A (en) * 2020-09-09 2020-11-20 鞍钢股份有限公司 HB500 grade high-wear-resistance thin steel plate and production method thereof
CN113234992A (en) * 2021-03-24 2021-08-10 江阴兴澄特种钢铁有限公司 High-hardenability medium-carbon MnCrMoB steel for engineering machinery transmission part and manufacturing method thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101654761A (en) * 2009-05-25 2010-02-24 莱芜钢铁股份有限公司 Carbon-manganese composite microalloyed steel for engineering machinery and preparation method thereof
CN109321712A (en) * 2018-11-08 2019-02-12 江阴兴澄特种钢铁有限公司 A kind of high-hardenability carburized gears 20CrNiB steel
CN111961977A (en) * 2020-09-09 2020-11-20 鞍钢股份有限公司 HB500 grade high-wear-resistance thin steel plate and production method thereof
CN113234992A (en) * 2021-03-24 2021-08-10 江阴兴澄特种钢铁有限公司 High-hardenability medium-carbon MnCrMoB steel for engineering machinery transmission part and manufacturing method thereof

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