High-strength steel member and manufacturing method thereof

Abstract

The invention discloses a high-strength steel member which is alloyed by a Fe matrix and comprises the following components in percentage by weight: 0.35%-0.45% of carbon (C), 12%-15% of manganese (Mn), 8%-10% of nickel (Ni), 1.8%-2.2% of molybdenum (Mo), 0.08%-0.12% of nitrogen (N), 0.03%-0.08% of rare earth elements, 0.02%-0.05% of boron (B) and the balance of iron (Fe) and inevitable impurities. Alloy elements with specific content are added into a Fe matrix, and the elements interact with the Fe matrix, so that the microstructure and the performance of the Fe matrix are changed; carbon and nitrogen can form carbides and nitrides to play a role in precipitation strengthening; manganese and nickel can improve the hardenability of the steel; molybdenum can improve the strength and toughness of the steel; and the rare earth elements can refine grains, so that the steel member has high strength, high toughness and good corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel components, and in particular relates to a high-strength steel component and a manufacturing method thereof. Background Art

[0002] High-strength steel is widely used in aviation, automotive, marine engineering, and other fields due to its excellent mechanical properties. However, the process of increasing the strength of traditional high-strength steel often leads to a decrease in toughness. This makes the material prone to cracking in stress-concentrated areas, which in turn affects its service life and safety. For example, in the heat-affected zone of high-strength steel welding, due to the uneven microstructure, stress corrosion cracking is prone to occur in complex environments.

[0003] At the same time, high-strength steel is susceptible to corrosion in complex environments, especially humid, acidic or salt spray environments. Corrosion not only reduces the strength of the steel, but also causes local stress concentration, further triggering crack propagation. The microstructure of traditional high-strength steel also has problems such as coarse grains and uneven distribution of inclusions, which not only affects its overall performance, but also leads to deterioration of local performance. Summary of the Invention

[0004] The purpose of the present invention is to propose a high-strength steel component to solve the problem that traditional high-strength steel often leads to a decrease in toughness during the process of increasing strength, which makes the material prone to cracks at stress concentration areas, thereby affecting its service life and safety.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: a high-strength steel component is alloyed with an Fe matrix and contains the following components by weight percentage:

[0006]

[0007]

[0008] The rest is iron (Fe) and inevitable impurities.

[0009] As a further description of the above technical solution:

[0010] The rare earth elements are Ce and La.

[0011] As a further description of the above technical solution:

[0012] Inevitable impurities include sulfur (S), phosphorus (P), oxygen (O), silicon (Si), copper (Cu), vanadium (V), and titanium (Ti), among which the content of sulfur (S) and phosphorus (P) is 0.01%-0.05%.

[0013] As a further description of the above technical solution:

[0014] The present invention also provides a method for manufacturing a high-strength steel component, comprising the following steps:

[0015] S1: Prepare the raw materials for the above-mentioned steel components and calculate the amount of each raw material to be added according to the composition of the steel components;

[0016] S2: Add iron (Fe) to the smelting furnace, and then add other alloying elements in sequence according to the requirements of the alloy composition. The order of addition is usually determined by the melting point and chemical properties of the elements;

[0017] S3: The raw materials are melted using a dual process of vacuum induction melting and electroslag remelting;

[0018] S4: The smelted steel material is quenched to -80°C for deep freezing treatment, kept warm for 2 hours, and then subjected to graded aging treatment, first kept warm at 480°C for 8 hours and then kept warm at 550°C for 4 hours to form a steel component.

[0019] As a further description of the above technical solution:

[0020] During the graded aging treatment in S4, the temperature field is monitored in real time by an infrared thermal imager to ensure that the temperature control accuracy is within ±5°C.

[0021] As a further description of the above technical solution:

[0022] In vacuum induction melting and electroslag remelting processes, the oxygen content is ≤15ppm.

[0023] As a further description of the above technical solution:

[0024] The order of addition to the S2 is iron (Fe), manganese (Mn), nickel (Ni), molybdenum (Mo), carbon (C), nitrogen (N), rare earth elements and boron (B).

[0025] As a further description of the above technical solution:

[0026] Plasma electrolytic oxidation (PE0) method is used to generate a composite coating with a thickness of 5-8μm on the surface of the steel component.

[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] 1. In the present invention, by adding specific amounts of alloying elements, including carbon (C), manganese (Mn), nickel (Ni), molybdenum (Mo), nitrogen (N), rare earth elements and boron (B), to the Fe matrix, these elements interact with the iron matrix to change its microstructure and properties; carbon and nitrogen can form carbides and nitrides, which play a role in precipitation strengthening; manganese and nickel can improve the hardenability of steel; molybdenum can improve the strength and toughness of steel; rare earth elements can refine the grains and improve the toughness and corrosion resistance of steel. This alloying design makes the steel components have high strength, high toughness and good corrosion resistance, which can meet the use requirements of high-strength steel components in complex environments.

[0029] 2. In the present invention, the dual process of vacuum induction melting and electroslag remelting can effectively remove impurities and gases in the steel and improve the purity of the steel. The deep cryogenic treatment of quenching to -80°C can further refine the grains and improve the strength and toughness of the steel. The graded aging treatment can make the alloy elements precipitate uniformly in the steel matrix, forming fine strengthening phases, further improving the strength and toughness of the steel. This manufacturing method can produce steel components with high strength, high toughness and good corrosion resistance, meeting the requirements for the use of high-strength steel components in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 Composition diagram of a high-strength steel component.

[0032] Figure 2 A step diagram of a method for manufacturing a high-strength steel component. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0036] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0037] In the description of the embodiments of the present invention, it should be noted that the terms "upper" and "inner" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are orientations or positional relationships in which the inventive product is usually placed when in use. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0038] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0039] See also Figure 1-2 The present invention provides a technical solution: a high-strength steel component, alloyed with an Fe matrix, comprising the following components by weight percentage:

[0040]

[0041] The rest is iron (Fe) and inevitable impurities.

[0042] Rare earth elements are Ce and La. These elements primarily exist in segregated forms in steel. At high temperatures, they form compounds with elements like oxygen and sulfur, forming modified inclusions that enhance the steel's toughness. Furthermore, Ce and La refine the microstructure, further improving the steel's performance.

[0043] Unavoidable impurities include sulfur (S), phosphorus (P), oxygen (O), silicon (Si), copper (Cu), vanadium (V), and titanium (Ti). The content of sulfur (S) and phosphorus (P) is 0.01%-0.05%. Controlling the content of sulfur (S) and phosphorus (P) can reduce the negative impact of these impurities on steel properties, improve the purity of steel, and thus enhance the strength, toughness, and corrosion resistance of steel.

[0044] The following steps are involved:

[0045] S1: Prepare the raw materials for the above-mentioned steel components and calculate the amount of each raw material to be added according to the composition of the steel components;

[0046] S2: Add iron (Fe) to the smelting furnace, and then add other alloying elements in sequence according to the requirements of the alloy composition. The order of addition is usually determined by the melting point and chemical properties of the elements;

[0047] S3: The raw materials are melted using a dual process of vacuum induction melting and electroslag remelting;

[0048] S4: The smelted steel material is quenched to -80°C for cryogenic treatment, kept at this temperature for 2 hours, and then subjected to graded aging treatment, first kept at 480°C for 8 hours and then kept at 550°C for 4 hours to form a steel component. The steel is heated to an austenitizing temperature (such as 900°C) and then rapidly cooled to room temperature to form martensite. The quenched steel is kept at -80°C for 2 hours to further stabilize the microstructure. The cryogenically treated steel is kept at 480°C for 8 hours and then at 550°C for 4 hours to promote the precipitation and uniform distribution of carbides. Through these steps, nano-scale carbides are formed in the microstructure of the steel, and these carbides are evenly dispersed in the martensite matrix, thereby significantly improving the overall performance of the steel.

[0049] During the step-by-step aging treatment in S4, the temperature field is monitored in real time using an infrared thermal imager to ensure that the temperature control accuracy is within ±5°C. This ensures the uniformity and stability of the temperature during the aging treatment, allowing the alloying elements to precipitate uniformly in the steel matrix, forming fine strengthening phases.

[0050] In vacuum induction melting and electroslag remelting processes, the oxygen content is ≤15ppm. This effectively reduces oxide inclusions in the steel, improving its purity and, consequently, its strength, toughness, and corrosion resistance. Vacuum induction melting is performed within a sealed vacuum chamber. The chamber is evacuated by a vacuum pump to reduce the influx of gaseous impurities such as oxygen and nitrogen. A high-frequency current is then passed through an induction coil to generate a high-frequency magnetic field. This magnetic field induces eddy currents in the metal, causing it to melt. The induction coil, typically made of copper, is wound around the exterior of the vacuum chamber. During this melting process, the vacuum environment effectively reduces the influx of oxygen and nitrogen, preventing metal oxidation and nitridation and improving metal purity.

[0051] The electroslag remelting process involves transferring the melted metal from vacuum induction melting to an electroslag remelting furnace. Current passes through the slag, generating heat that further melts the metal. The slag protects the metal from oxidation and removes impurities.

[0052] The order of addition to S2 is iron (Fe), manganese (Mn), nickel (Ni), molybdenum (Mo), carbon (C), nitrogen (N), rare earth elements, and boron (B). Rare earth elements are easily oxidized at high temperatures, while boron is easily volatile at high temperatures and easily forms borides with iron during the smelting process. Therefore, it needs to be added later in the smelting process to reduce volatilization losses. This addition order ensures uniform distribution and sufficient dissolution of the alloying elements. This addition order takes into account the melting points and chemical properties of the elements, which facilitates a smooth smelting process.

[0053] Plasma electrolytic oxidation (PEO) is used to generate a composite coating with a thickness of 5-8 μm on the surface of steel components. The coating can improve the corrosion resistance and wear resistance of the steel and extend its service life.

[0054] Working principle: By adding specific amounts of alloying elements to the Fe matrix, including carbon (C), manganese (Mn), nickel (Ni), molybdenum (Mo), nitrogen (N), rare earth elements and boron (B), these elements interact with the iron matrix to change its microstructure and properties; carbon and nitrogen can form carbides and nitrides, which play a role in precipitation strengthening; manganese and nickel can improve the hardenability of steel; molybdenum can improve the strength and toughness of steel; rare earth elements can refine the grains and improve the toughness and corrosion resistance of steel. This alloying design makes the steel components have high strength, high toughness and good corrosion resistance, which can meet the use requirements of high-strength steel components in complex environments.

[0055] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A high-strength steel component, characterized in that: Alloyed by Fe matrix, containing the following components by weight percentage: The rest is iron (Fe) and inevitable impurities.

2. A high-strength steel component according to claim 1, characterized in that: The rare earth elements are Ce and La.

3. The high-strength steel component according to claim 1, characterized in that: Inevitable impurities include sulfur (S), phosphorus (P), oxygen (O), silicon (Si), copper (Cu), vanadium (V), and titanium (Ti), among which the content of sulfur (S) and phosphorus (P) is 0.01%-0.05%.

4. A method for manufacturing a high-strength steel component according to claims 1-3, characterized in that: The following steps are involved: S1: Prepare the raw materials for the steel member and calculate the amount of each raw material added according to the composition of the steel member; S2: Add iron (Fe) to the smelting furnace, and then add other alloying elements in sequence according to the requirements of the alloy composition. The order of addition is usually determined by the melting point and chemical properties of the elements; S3: The raw materials are melted using a dual process of vacuum induction melting and electroslag remelting; S4: The smelted steel material is quenched to -80°C for deep freezing treatment, kept warm for 2 hours, and then subjected to graded aging treatment, first kept warm at 480°C for 8 hours and then kept warm at 550°C for 4 hours to form a steel component.

5. The method for manufacturing a high-strength steel component according to claim 4, characterized in that: During the graded aging treatment in S4, the temperature field is monitored in real time by an infrared thermal imager to ensure that the temperature control accuracy is within ±5°C.

6. The high-strength steel component according to claim 4, characterized in that: In vacuum induction melting and electroslag remelting processes, the oxygen content is ≤15ppm.

7. The high-strength steel component according to claim 4, characterized in that: The order of addition to the S2 is iron (Fe), manganese (Mn), nickel (Ni), molybdenum (Mo), carbon (C), nitrogen (N), rare earth elements and boron (B).

8. The high-strength steel component according to claim 4, characterized in that: Plasma electrolytic oxidation (PE0) method is used to generate a composite coating with a thickness of 5-8μm on the surface of the steel component.

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