High-toughness steel, rotating shaft mechanism, and foldable electronic device

Abstract

This application provides a high-strength and tough steel, a hinge mechanism, and a foldable electronic device. The high-strength and tough steel comprises the following components in the following weight percentages: nickel: [16wt%, 19wt%]; cobalt: [13wt%, 16wt%]; molybdenum: [5wt%, 7wt%]; titanium: [0.5wt%, 2.0wt%]; rare earth elements: (0, 0.03wt%); the balance being iron and unavoidable impurities, wherein the unavoidable impurities have a weight percentage less than or equal to 0.2wt%. The high-strength and tough steel provided in this application has excellent strength and toughness, enabling the hinge mechanism to be manufactured more compactly while maintaining its strength and toughness, meeting the requirements of foldable electronic devices and contributing to the lightweight and thinning of foldable electronic devices.

Description

Technical Field

[0001] This application relates to the field of steel materials technology, and in particular to a high-strength and tough steel, a pivot mechanism, and a foldable electronic device. Background Technology

[0002] In recent years, electronic devices have become an important part of people's lives. With the increasing demand for electronic devices, various forms of electronic products have emerged. Among them, the demand for foldable electronic devices is also growing. For example, foldable phones, this new form of mobile phone, has gained popularity and developed rapidly since its introduction.

[0003] Taking a foldable phone with a two-layer folding structure as an example, a foldable phone generally includes a hinge mechanism and two mid-frame sections, which are connected by the hinge mechanism. The structure and volume of the hinge mechanism largely determine the thickness of the foldable phone. When foldable phones achieve a thinner and lighter design, the hinge mechanism needs to maintain reliable rotation functionality while compressing its volume.

[0004] However, the rotating shaft mechanism is easily damaged by force when its volume is compressed, which affects the service life of electronic devices and the user experience. Summary of the Invention

[0005] This application provides a high-strength and tough steel, a hinge mechanism, and a foldable electronic device. The high-strength and tough steel has excellent strength and toughness, which allows the hinge mechanism to be manufactured more compactly. It can also ensure the strength and toughness of the hinge mechanism, meet the requirements of foldable electronic devices, and facilitate the lightweighting and thinning of foldable electronic devices.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, embodiments of this application provide a high-strength and high-toughness steel comprising the following components, wherein the weight percentages of each component are: nickel: [16wt%, 19wt%]; cobalt: [13wt%, 16wt%]; molybdenum: [5wt%, 7wt%]; titanium: [0.5wt%, 2.0wt%]; rare earth elements: (0, 0.03wt%); the balance being iron and unavoidable impurities, wherein the weight percentage of the unavoidable impurities is less than or equal to 0.2wt%.

[0008] In the embodiments of this application, rare earth elements are added to the composition of high-strength and high-toughness steel, and the weight percentage of rare earth elements in the high-strength and high-toughness steel is controlled within a certain range. This can reduce the stacking fault energy of austenite, decrease the proportion of lamellar martensite, appropriately increase the proportion of austenite, and improve the toughness of the material. It can also reduce the generation of harmful inclusions during the manufacturing process of high-strength and high-toughness steel, purify the matrix, and improve the purity of the steel, thereby improving the strength and toughness of the high-strength and high-toughness steel. Furthermore, rare earth elements can spheroidize inclusions, reduce stress concentration, and further improve the strength and toughness of the high-strength and high-toughness steel material. In addition, rare earth elements can refine austenite grains, thereby refining the spacing between lamellar martensite, which can further improve the strength and toughness of the high-strength and high-toughness steel. Meanwhile, in the high-strength and tough steel provided in this application embodiment, the sum of the contents of molybdenum (Mo) and nickel (Ni) is controlled between 21wt% and 26wt%. The yield strength of this high-strength and tough steel can be greater than 2900MPa, and the tensile strength can be greater than 3000MPa. Furthermore, the high-strength and tough steel exhibits good plasticity, and the yield strength and tensile strength are positively correlated. If the sum of the Mo and Ni contents in the high-strength and tough steel provided in this application embodiment is less than 21wt%, the yield strength of the material is less than 2900MPa. If the sum of the Mo and Ni contents in the high-strength and tough steel provided in this application embodiment is greater than 26wt%, then due to the low plasticity of the material, the yield strength and tensile strength are negatively correlated; that is, a higher yield strength results in a lower tensile strength. In summary, the high-strength and tough steel provided in this application embodiment, by using the above-mentioned proportion range, possesses both high strength and excellent toughness.

[0009] In one possible implementation, the rare earth elements include lanthanum and / or cerium and / or yttrium, and are present in the high-strength and high-toughness steel in the following weight percentages: lanthanum: (0 wt%, 0.01 wt%) and / or cerium: (0 wt%, 0.01 wt%) and / or yttrium: (0 wt% < La ≤ 0.01 wt%).

[0010] In one possible implementation, the rare earth element includes lanthanum, wherein the weight percentage of lanthanum in the high-strength and high-toughness steel is 0 wt%, 0.006 wt%. High-strength and high-toughness steel with this composition and content exhibits excellent strength and toughness.

[0011] In one possible implementation, the rare earth element includes cerium, wherein the weight percentage of cerium in the high-strength and high-toughness steel is (0 wt%, 0.006 wt%). High-strength and high-toughness steel with this composition and content exhibits excellent strength and toughness.

[0012] In one possible implementation, the rare earth element includes yttrium, which is present in the high-strength and high-toughness steel at a weight percentage of 0 wt%, 0.006 wt%. This composition and content result in a high-strength and high-toughness steel exhibiting excellent strength and toughness.

[0013] In one possible implementation, the rare earth elements include lanthanum and cerium, and the combined weight percentage of lanthanum and cerium in the high-strength and high-toughness steel is 0 wt%, 0.006 wt%. High-strength and high-toughness steel with this composition and content exhibits excellent strength and toughness.

[0014] In one possible implementation, the rare earth element further includes the yttrium, and the total weight percentage of the lanthanum, the cerium, and the yttrium in the high-strength and tough steel is (0 wt%, 0.006 wt%).

[0015] In high-strength and tough steel, if the total content of rare earth elements is greater than 0.01 wt%, a large amount of rare earth elements will accumulate at the grain boundaries (grain boundaries refer to the interfaces or interface regions between crystals that are bonded to each other in solid materials). The steel is prone to intergranular fracture during service. Therefore, in this embodiment, the excessive content of rare earth elements can be avoided from affecting the strength and toughness of high-strength and tough steel materials.

[0016] In one possible implementation, the ratio of the sum of the weights of the lanthanum and the cerium to the weight of the yttrium is [2, 5]. This results in a better synergistic effect between the lanthanum, cerium, and yttrium, and a significant increase in the strength and toughness of the material.

[0017] In one possible implementation, the unavoidable impurities include manganese and silicon, wherein the weight percentage of manganese is less than 0.5 wt% and the weight percentage of silicon is less than 0.5 wt%. By controlling the impurity content, it is possible to prevent impurities from affecting the formation of the Mo-Fe phase and the Mo-Ni reinforcing phase, as well as from affecting the strength and toughness of the material.

[0018] In one possible implementation, the high-strength and high-toughness steel further includes aluminum, wherein the aluminum is present in a weight percentage of [0.1 wt%, 0.5 wt%].

[0019] Aluminum acts as a reducing agent in high-strength and high-toughness steel, forming a dense layer of aluminum oxide on the surface during smelting, thus reducing steel oxidation. Furthermore, aluminum can also be a component of precipitation-strengthening phases, forming NiAl or η-Ni3Al phases coherent with martensite, thereby enhancing the strength of high-strength and high-toughness steel. Both NiAl and η-Ni3Al phases are intermetallic compounds, possessing high yield strength, excellent comprehensive properties, and structural stability.

[0020] Secondly, this application provides a rotating shaft mechanism, wherein at least a portion of the material of the rotating shaft mechanism comprises the high-strength and high-toughness steel as described above.

[0021] The hinge mechanism provided in this application uses materials with excellent strength and toughness. The hinge mechanism can be made more compact, and its strength and toughness can be guaranteed to meet the needs of foldable electronic devices.

[0022] In one possible implementation, the pivot mechanism includes a base and a swing arm rotatably connected to the base, wherein at least a portion of the swing arm is made of high-strength and high-toughness steel as described above.

[0023] Thirdly, embodiments of this application provide a foldable electronic device, including: a flexible screen, a first main body, a second main body, and a pivot mechanism as described above. The first main body and the second main body are connected by the pivot mechanism, which is configured to allow the first main body to unfold and fold relative to the second main body. The flexible screen is attached to the first main body and the second main body.

[0024] The foldable electronic device provided in this application embodiment has a hinge mechanism made of a material with excellent strength and toughness, allowing the hinge mechanism to be manufactured more compactly while ensuring its strength and toughness to meet the requirements of foldable electronic devices. This, in turn, facilitates the lightweighting and thinning of foldable electronic devices. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a foldable electronic device provided in an embodiment of this application;

[0026] Figure 2 A schematic diagram of the disassembled structure of a foldable electronic device provided in an embodiment of this application;

[0027] Figure 3 A cross-sectional schematic diagram of a foldable electronic device provided in an embodiment of this application;

[0028] Figure 4 This is a schematic diagram illustrating the folding or unfolding of a foldable electronic device according to an embodiment of this application;

[0029] Figure 5 A comparative schematic diagram of the hinge mechanism of a foldable electronic device provided in an embodiment of this application before and after thinning;

[0030] Figure 6 This is a schematic diagram illustrating the relationship between the strength and toughness of steel.

[0031] Figure 7 A graph showing the influence of the weight percentage of lanthanum and cerium on the weight percentage of yttrium in the high-strength and high-toughness steel provided in the embodiments of this application.

[0032] Figure 8This is a flowchart illustrating a method for preparing high-strength and high-toughness steel according to an embodiment of this application.

[0033] Explanation of reference numerals in the attached figures:

[0034] 100 - Foldable electronic devices;

[0035] 110 - Flexible screen; 120 - First main body; 130 - Second main body;

[0036] 140 - Rotating shaft mechanism;

[0037] 141-Base; 142-Swing arm. Detailed Implementation

[0038] The terminology used in the implementation section of this application is only for explaining specific embodiments of this application and is not intended to limit this application. The implementation of the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0039] This application provides a foldable electronic device. The foldable electronic device is a type of electronic device with a flexible screen. The foldable electronic device can change the unfolded or folded state of the flexible screen and itself. Under different usage requirements, the foldable electronic device can be unfolded or folded. Examples of foldable electronic devices include mobile phones, tablets, televisions, smart wearable products (such as smartwatches, smart bracelets, etc.), virtual reality (VR) devices, augmented reality (AR) devices, and other terminal products, as well as professional shooting equipment such as digital cameras, SLR cameras, mirrorless cameras, and action cameras. For ease of explanation, this application uses a foldable mobile phone as an example for illustration.

[0040] Figure 1 This application provides a schematic diagram of the structure of a foldable electronic device 100 according to an embodiment of the present application. Figure 2 This is a schematic diagram of the disassembled structure of a foldable electronic device 100 provided in an embodiment of this application, with reference to... Figure 1 and Figure 2As shown in the illustration, the foldable electronic device 100 provided in this application embodiment includes: a flexible screen 110, a first main body 120, a second main body 130, and a hinge mechanism 140. The first main body 120 and the second main body 130 are connected by the hinge mechanism 140, which is configured to allow the first main body 120 to unfold and fold relative to the second main body 130. Exemplarily, the first main body 120 and the second main body 130 are respectively connected to opposite sides of the axial direction of the hinge mechanism 140, enabling the first main body 120 and the second main body 130 to unfold and fold relative to each other. The structures of the first main body 120 and the second main body 130 may be the same, not exactly the same, or completely different.

[0041] It should be noted that, in addition to using one pivot mechanism 140 and two main body parts to form a two-layer folding structure, the foldable electronic device 100 provided in this application embodiment can also use multiple pivot mechanisms 140 and two or more main body parts to form a more layered folding mechanism. In this application example, only two main body parts are used as an example for illustration. When the foldable electronic device 100 includes multiple pivot mechanisms 140 and two or more main body parts, two adjacent main body parts are respectively connected to both sides of the axis of a pivot mechanism 140, and the two adjacent main body parts can be relatively unfolded and folded through the pivot mechanism 140.

[0042] The first main body 120 and the second main body 130 may house the components required for the foldable electronic device 100. For example, in some embodiments of this application, the foldable electronic device 100 includes multiple components (not shown in the figures), which can be installed within the first main body 120 and the second main body 130. These components may include, for example, a motherboard, processor, internal memory, external memory interface, universal serial bus (USB) interface, charging management module, power management module, battery, antenna, communication module, camera, audio module, speaker, receiver, microphone, headphone jack, sensor module, motor, indicator, and subscriber identification module (SIM) card interface, etc. The foldable electronic device 100 may have more or fewer components than described above, may combine two or more components, or may have different component configurations. Each component can be implemented in hardware, software, or a combination of hardware and software, including one or more signal processing and / or application-specific integrated circuits.

[0043] The flexible screen 110 is attached to the surfaces of the first main body 120 and the second main body 130 that are close to or far apart when folded. For example... Figure 1As shown, from the user's perspective, when the foldable electronic device 100 is in a flattened state, the user faces the flexible screen 110, which is attached to the upper surfaces of the first main body 120 and the second main body 130. During the relative unfolding and folding of the first main body 120 and the second main body 130, the flexible screen 110 is also simultaneously unfolded and folded along with the first main body 120 and the second main body 130. When the foldable electronic device 100 includes multiple hinge mechanisms 140 and two or more main bodies, the flexible screen 110 is attached to one side of at least two main bodies and at least one hinge mechanism 140.

[0044] In this configuration, the flexible screen 110 is attached to the surfaces of the first main body 120 and the second main body 130 that are close to each other when folded. When the foldable electronic device 100 is folded, the flexible screen 110 is located inside the first main body 120 and the second main body 130, making the foldable electronic device 100 an inward-folding device. Alternatively, the flexible screen 110 can be attached to the surfaces of the first main body 120 and the second main body 130 that are far apart when folded, making the foldable electronic device 100 an outward-folding device. For example... Figure 1 and Figure 2 The foldable electronic device 100 shown is a screen-folding device.

[0045] The foldable electronic device 100 can be unfolded to a flat state, folded to a folded state, or unfolded or folded to an intermediate state. The intermediate state can be any state between the flat state and the folded state.

[0046] Because the aforementioned foldable electronic device 100 can switch between an unfolded and folded state, when the user uses the foldable electronic device 100 to browse web pages, access information, watch videos, play games, etc., they can switch from the folded state to the unfolded state to achieve a large-screen display, providing the user with richer information and a better user experience. When the user is finished using the foldable electronic device 100, they can switch from the unfolded state to the folded state. This reduces the size of the foldable electronic device 100, making it easier to store.

[0047] Figure 3 This is a cross-sectional schematic diagram of a foldable electronic device 100 provided in an embodiment of this application, with reference to... Figure 3 As shown, based on the structural characteristics of the foldable electronic device 100, the first main body 120 and the second main body 130 are located on both sides of the pivot mechanism 140, and the flexible screen 110 is stacked with the first main body 120, the second main body 130 and the pivot mechanism 140, the structure and volume of the pivot mechanism 140 largely determine the thickness of the foldable electronic device 100.

[0048] As the demand for foldable electronic devices 100 increases, foldable electronic devices 100 are also developing towards thinner and lighter designs. Therefore, the hinge mechanism 140 is also gradually becoming miniaturized and thinner.

[0049] Figure 4 This is a schematic diagram illustrating the folding or unfolding of a foldable electronic device 100 provided in an embodiment of this application. Figure 5 This is a comparative diagram of the rotating shaft mechanism 140 before and after thinning. (Reference) Figure 4 and Figure 5 As shown, in the foldable electronic device 100 provided in this application embodiment, the pivot mechanism 140 includes a base 141 and a swing arm 142. The base 141 serves as the supporting "skeleton" of the pivot mechanism 140, and the swing arm 142, synchronization module, damping module, etc. can be installed on the base 141. Regarding the configuration components installed on the base 141, please refer to the prior art, and this application will not elaborate further.

[0050] One end of the swing arm 142 is rotatably connected to the base 141, and the other end is used to connect to the first main body 120 or the second main body 130, so that the first main body 120 and the second main body 130 of the foldable electronic device 100 can be connected as follows: Figure 4 The rotating mechanism 140 shown in the figure allows the foldable electronic device 100 to switch between a folded state and an unfolded state.

[0051] When users use foldable electronic devices 100, etc. Figure 4 When the first main body 120 and the second main body 130 are rotated, the swing arm 142 connected to the first main body 120 or the second main body 130 will be subjected to a reaction force (such as...). Figure 5 (The force F acting on the middle swing arm 142). When the thickness of the swing arm 142 is reduced, under the same force F, the swing arm 142 may crack or break. Therefore, when the thickness of the swing arm 142 is reduced, the strength and toughness of the swing arm 142 also need to be improved simultaneously.

[0052] Here, we will explain the definitions of strength and toughness of steel.

[0053] Strength: The strength of steel is an important indicator for measuring its mechanical properties, mainly including yield strength and tensile strength. Yield strength refers to the maximum stress required for steel to undergo recoverable deformation from a stress-free state under load; it is an indicator of the maximum load steel can withstand before plastic deformation. Tensile strength refers to the ability of steel to resist fracture in a tensile test; it is an indicator of the maximum tensile force steel can withstand before fracture.

[0054] Toughness refers to a material's ability to absorb energy and resist crack propagation before fracture. The toughness of steel can be expressed as elongation. Elongation is the ratio of the increase in length (or cross-sectional area) per unit cross-section when the specimen breaks to the original specimen length (or cross-sectional area). A higher elongation indicates better toughness of the steel.

[0055] However, reference Figure 6 As shown, the strength and toughness of steel generally exhibit an inverse relationship. That is, the higher the strength of steel, the lower its toughness usually is, and vice versa. This relationship is particularly pronounced in steel. This relationship between the strength and toughness of steel is mainly due to changes in the material's microstructure. High-strength steel typically has finer grains and a higher dislocation density, which leads to reduced plasticity, thus affecting toughness. Conversely, improving toughness usually requires increasing the grain size and reducing the dislocation density, but this reduces the material's strength.

[0056] Please continue to refer to this. Figure 4 and Figure 5 As shown, when the hinge mechanism 140 is made of only high-strength material, it will be subjected to a force F when impacted, for example, when a foldable phone is dropped. The hinge mechanism 140 will be subjected to a violent impact, and the base 141 and swing arm 142 are prone to cracking or even breakage, leading to failure. Therefore, the material used to make the hinge mechanism 140 needs to possess both high strength and high toughness. With the increasing thinness and lightness of foldable phones, the strength and toughness of the materials used to make the hinge mechanism 140 are gradually no longer sufficient to meet reliability requirements.

[0057] To address the issues of unsatisfactory reliability of the materials used in the rotating shaft mechanism 140 and the difficulty in simultaneously achieving both strength and toughness in steel, this application provides a high-strength, high-toughness steel suitable for manufacturing the rotating shaft mechanism 140. Furthermore, this high-strength, high-toughness steel possesses both high strength and high toughness. Additionally, refer to... Figure 6 As shown, the high-strength and high-toughness steel provided in this application aims to balance the strength and toughness of the steel, so that the inverse proportional curve between the strength and toughness of the steel is as close as possible to... Figure 6 The close proximity of the "stars" in the middle allows the high-strength and high-toughness steel to achieve the highest possible toughness while maintaining the highest possible strength.

[0058] The following describes, with reference to the accompanying drawings, a method for preparing high-strength and high-toughness steel according to embodiments of this application, and the applications of such high-strength and high-toughness steel.

[0059] According to the embodiments of this application, a high-strength and high-toughness steel has a martensitic and austenitic structure. The high-strength and high-toughness steel comprises the following components, and the weight percentages of the components are as follows: nickel (Ni): [16wt%, 19wt%]; cobalt (Co): [13wt%, 16wt%]; molybdenum (Mo): [5wt%, 7wt%]; titanium (Ti): [0.5wt%, 2.0wt%]; rare earth elements (RE): (0, 0.03wt%); the balance being iron (Fe) and unavoidable impurities, wherein the weight percentage of the unavoidable impurities is less than or equal to 0.2wt%.

[0060] Austenite is a face-centered cubic crystal structure in steel at high temperatures, possessing good toughness and ductility, but lower hardness and strength than martensite. Martensite is a body-centered tetragonal crystal structure formed in steel during rapid cooling (quenching), possessing high hardness and strength, but poor toughness.

[0061] In the preparation of high-strength and high-toughness steel, nickel (Ni) expands the austenite phase region, ensuring the volume of lath martensite after rapid cooling of solution treatment, increasing dislocation density, and thus improving the strength of high-strength and high-toughness steel. Furthermore, nickel (Ni) can disperse with molybdenum (Mo) to precipitate a Mo-Ni reinforcing phase, further enhancing the material's strength.

[0062] Among them, the Mo-Ni strengthening phase refers to the strengthening phase formed in the alloy composed of Mo and Ni through heat treatment or processing. These phases can significantly improve the strength, hardness and heat resistance of the alloy.

[0063] When the weight percentage of nickel (Ni) in high-strength and high-toughness steel exceeds 19 wt%, the steel is prone to forming lamellar martensite and retained austenite, affecting its strength. This application controls the weight percentage of nickel (Ni) to 16 wt% ≤ Ni ≤ 19 wt%, which reduces the formation of lamellar martensite and retained austenite, maximizing the strength of the high-strength and high-toughness steel.

[0064] Cobalt (Co) strengthens the matrix during solution treatment and increases the Ms temperature (the temperature at which austenite transforms into martensite, marking the beginning of the martensitic phase transformation), thus promoting the complete transformation of austenite into martensite and increasing the strength of high-strength and high-toughness steel. Furthermore, Co reduces the solid solubility of molybdenum (Mo) in lath martensite, promoting the precipitation of Mo-Fe and Mo-Ni strengthening phases. It also inhibits the recovery of the martensitic substructure during aging treatment, providing more nucleation sites for precipitated phases.

[0065] The Mo-Fe phase refers to a specific phase structure formed in an alloy composed of Mo and Fe.

[0066] Molybdenum (Mo), as a strengthening alloying element, reacts with Ni and Fe to disperse and precipitate Mo-Fe and Mo-Ni reinforcing phases, thereby improving the material's strength. Mo reacts with Ni to form Mo-Ni precipitates, which exhibit good lattice matching with the body-centered tetragonal structure of the martensitic matrix. However, when the weight percentage of Mo exceeds 7 wt%, coarse Mo-Fe phases are easily formed (over-aging also produces Mo-Fe phases), leading to a deterioration in the strength and toughness of the high-strength and tough steel. Over-aging refers to the temperature and time required to reach peak hardness when the aging temperature exceeds the normal aging temperature. In the embodiments of this application, the weight percentage of Mo is controlled between 5 wt% and 7 wt%, which maximizes the strength and toughness of the high-strength and tough steel.

[0067] Titanium (Ti), as a strengthening metal element, forms Ti-Ni precipitates with Ni in the lath martensitic matrix, which is an important source of precipitation. However, when the weight percentage of Ti is greater than 2 wt%, it will significantly reduce the toughness of the high-strength and tough steel. In the embodiments of this application, the weight percentage of Ti is controlled at 0.5 wt% ≤ Ti ≤ 2.0 wt%, which can maximize the strength and toughness of the high-strength and tough steel.

[0068] Rare earth elements refer to the collective term for elements such as lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium. Rare earth elements are generally represented by RE or R. During the smelting process, rare earth elements can react with impurities such as oxygen (O) and sulfur (S) to form stable RE₂O₃ and RE₂S₃ inclusions, reducing harmful inclusions and improving the purity of steel, thereby enhancing the strength and toughness of high-strength and tough steel. Furthermore, rare earth elements can spheroidize inclusions, resulting in higher roundness, smaller size, and more uniform distribution, which reduces stress concentration and is beneficial for improving the strength and toughness of high-strength and tough steel. In addition, adding rare earth elements to high-strength and tough steel can refine the austenite grains, thereby refining the spacing between lath martensite and improving the strength and toughness of high-strength and tough steel.

[0069] The unavoidable impurities mainly come from the following aspects: raw materials, such as iron ore containing impurities such as silicon, aluminum, phosphorus, and sulfur; the smelting process, such as the use of flux which introduces impurities such as silicon; equipment and environment, such as furnace lining materials that may fall off, increasing impurities, and nitrogen and oxygen in the air that can react with molten steel to form oxides and nitrides; deoxidizers, which may contain residual impurities such as silicon; and subsequent processing, such as the trace impurities that may be introduced due to equipment wear during forging and rolling.

[0070] In the embodiments of this application, rare earth elements are added to the composition of high-strength and high-toughness steel, and the weight percentage of rare earth elements in the high-strength and high-toughness steel is controlled within a certain range. This can reduce the stacking fault energy of austenite, decrease the proportion of lamellar martensite, appropriately increase the proportion of austenite, and improve the toughness of the material. It can also reduce the generation of harmful inclusions during the manufacturing process of high-strength and high-toughness steel, purify the matrix, and improve the purity of the steel, thereby improving the strength and toughness of the high-strength and high-toughness steel. Furthermore, rare earth elements can spheroidize inclusions, reduce stress concentration, and further improve the strength and toughness of the high-strength and high-toughness steel material. In addition, rare earth elements can refine austenite grains, thereby refining the spacing between lamellar martensite, which can further improve the strength and toughness of the high-strength and high-toughness steel. Meanwhile, in the high-strength and tough steel provided in this application embodiment, the sum of the contents of molybdenum (Mo) and nickel (Ni) is controlled between 21wt% and 26wt%. The yield strength of this high-strength and tough steel can be greater than 2900MPa, and the tensile strength can be greater than 3000MPa. Furthermore, the high-strength and tough steel exhibits good plasticity, and the yield strength and tensile strength are positively correlated. If the sum of the Mo and Ni contents in the high-strength and tough steel provided in this application embodiment is less than 21wt%, the yield strength of the material is less than 2900MPa. If the sum of the Mo and Ni contents in the high-strength and tough steel provided in this application embodiment is greater than 26wt%, then due to the low plasticity of the material, the yield strength and tensile strength are negatively correlated; that is, a higher yield strength results in a lower tensile strength. In summary, the high-strength and tough steel provided in this application embodiment, by using the above-mentioned proportion range, possesses both high strength and excellent toughness.

[0071] It should be noted that in some embodiments of this application, in addition to the above-mentioned components, other components may be added as needed to meet the requirements of other material properties, such as the magnetic, luminescent or electrochemical properties of high-strength and tough steel, on the basis of improving strength and toughness achieved in the embodiments of this application.

[0072] In some embodiments of this application, the high-strength and high-toughness steel provided in this application also includes Al, and the weight percentage is [0.1wt%, 0.5wt%].

[0073] Aluminum (Al) acts as a reducing agent in high-strength and high-toughness steel, forming a dense layer of aluminum oxide on the surface during smelting, thus reducing the oxidation of the molten steel. Furthermore, aluminum can also serve as a component of precipitation-strengthening phases, forming NiAl or η-Ni3Al phases coherent with martensite, thereby enhancing the strength of high-strength and high-toughness steel. Both NiAl and η-Ni3Al phases are intermetallic compounds, possessing high yield strength, excellent comprehensive properties, and structural stability.

[0074] Based on the aforementioned high-strength and high-toughness steel, in some embodiments of this application, rare earth elements (REs) include lanthanum (La) and / or cerium (Ce) and / or yttrium (Y), and their weight percentages in the high-strength and high-toughness steel are: La: (0 wt%, 0.01 wt%) and / or Ce: (0 wt%, 0.01 wt%) and / or Y: (0 wt% < La ≤ 0.01 wt%). That is, the rare earth elements (REs) include: La: 0 wt% < La ≤ 0.01 wt% and / or Ce: 0 wt% < Ce ≤ 0.01 wt% and / or Y: 0 wt% < La ≤ 0.01 wt%. Wherein, REs including La and / or Ce and / or Y means that REs include one of La, Ce, and Y, or two of La, Ce, and Y, or three of La, Ce, and Y.

[0075] Based on the aforementioned high-strength and high-toughness steel, in some embodiments of this application, the rare earth element RE includes La, and the weight percentage of La in the high-strength and high-toughness steel is controlled within (0 wt%, 0.006 wt%), that is, 0 wt% < La ≤ 0.006 wt%. High-strength and high-toughness steel with this composition and content exhibits excellent strength and toughness.

[0076] Based on the above-mentioned high-strength and high-toughness steel, in some embodiments of this application, the rare earth element RE includes Ce, and the weight percentage of Ce in the high-strength and high-toughness steel is controlled within (0 wt%, 0.006 wt%), that is, 0 wt% < Ce ≤ 0.006 wt%. The high-strength and high-toughness steel with this composition and content has excellent strength and toughness.

[0077] Based on the aforementioned high-strength and high-toughness steel, in some embodiments of this application, the rare earth element RE includes Y, and the weight percentage of Y in the high-strength and high-toughness steel is controlled within (0 wt%, 0.006 wt%), that is, 0 wt% < Y ≤ 0.006 wt%. High-strength and high-toughness steel with this composition and content exhibits excellent strength and toughness.

[0078] Based on the above-mentioned high-strength and high-toughness steel, in some embodiments of this application, the rare earth element RE includes La and Ce, and the weight percentage of the sum of La and Ce in the high-strength and high-toughness steel is controlled within (0 wt%, 0.006 wt%), that is, 0 wt% < La + Ce ≤ 0.006 wt%. The high-strength and high-toughness steel with this composition and content has excellent strength and toughness.

[0079] In high-strength and tough steel, if the total content of rare earth elements exceeds 0.01 wt%, a large amount of rare earth elements will accumulate at the grain boundaries (grain boundaries refer to the interfaces or interface regions between crystals bonded together in a solid material), making the steel prone to intergranular fracture during service. Therefore, based on the aforementioned high-strength and tough steel, in some embodiments of this application, the rare earth elements RE include La, Ce, and Y. The weight percentage of the sum of the weights of La, Ce, and Y in the high-strength and tough steel is controlled within (0 wt%, 0.006 wt%), i.e., 0 wt% < La + Ce + Y ≤ 0.006 wt%, to avoid excessive rare earth element content affecting the strength and toughness of the high-strength and tough steel material.

[0080] Of course, this application does not stop there. This application also studies the ratio of the sum of the weights of La and Ce to the weight of Y in high-strength and high-toughness steel, and concludes... Figure 7 . refer to Figure 7 As shown, in high-strength and high-toughness steels, when the ratio between the sum of the weights of lanthanum (La) and cerium (Ce) and the weight of yttrium (Y) falls within different ranges, the high-strength and high-toughness steels exhibit various phenomena, including insignificant strength improvement, good strength and toughness, and increased strength but decreased toughness (making the material prone to embrittlement). From... Figure 7 As can be seen from this, when the ratio between the sum of the weights of La and Ce and the weight of Y is within a certain range ( Figure 7 When the proportion of steel is optimized (in the preferred region), the goal of significantly improving the strength and toughness of steel can be achieved simultaneously.

[0081] Based on this, in some embodiments of this application, in high-strength and high-toughness steel, rare earth elements RE include La, Ce and Y, and the ratio of the sum of the weights of La and Ce to the weight of Y is [2, 5], that is, 2:1≤(La+Ce):Y≤5:1. In this case, the sum of the weights of La and Ce forms a certain ratio with the weight of Y, the synergistic effect of La, Ce and Y is better, and the strength and toughness of the material can be significantly increased.

[0082] In some embodiments of this application, unavoidable impurities include manganese (Mn) and silicon (Si), wherein the weight percentage of Mn is less than 0.5 wt% and the weight percentage of Si is less than 0.5 wt%. Controlling the impurity content can prevent impurities from affecting the formation of the Mo-Fe and Mo-Ni reinforcing phases, and from affecting the strength and toughness of the material. Mn, as a constituent element in high-strength and high-toughness steel, can improve strength and toughness and affect the phase transformation temperature. Excessive Mn content can alter the crystal structure of the matrix, thereby affecting the energy state of the grain boundaries. Excessive Mn content can also cause rare earth elements to accumulate at grain boundaries, leading to brittle fracture along grain boundaries.

[0083] In the embodiments of this application, the high-strength and high-toughness steel has a yield strength greater than 2900 MPa, an elongation greater than 5% and less than or equal to 11%, and a tensile strength greater than 3000 MPa.

[0084] The high-strength and tough steel provided in this application embodiment can be applied to electronic devices. For example, the high-strength and tough steel can be processed into a pivot mechanism 140 and applied to an electronic device. At least a portion of the pivot mechanism 140 is made of this high-strength and tough steel, meaning that all or part of the pivot mechanism 140 is made of this high-strength and tough steel. For example, in the foldable electronic device 100 provided in this application, the base 141 and / or swing arm 142 of the pivot mechanism 140 are made of this high-strength and tough steel to realize the opening and folding of the first main body 120 and the second main body 130. The use of this high-strength and tough steel for the base 141 and / or swing arm 142 of the pivot mechanism 140 means that the base 141 of the pivot mechanism 140 is made of this high-strength and tough steel, or that the swing arm 142 of the pivot mechanism 140 is made of this high-strength and tough steel, or that both the base 141 and the swing arm 142 of the pivot mechanism 140 are made of this high-strength and tough steel. The hinge mechanism 140 can be manufactured to a more compact size while maintaining its strength and toughness to meet the requirements of the foldable electronic device 100. Of course, this high-strength and high-toughness steel can also be used in other opening and closing devices, such as flip-top electronic devices, like laptops, and other structural components with opening and closing actions. Naturally, the base 141 and the swing arm 142 can also be partially or entirely made of this high-strength and high-toughness steel material.

[0085] It is understood that the high-strength and tough steel provided in this application embodiment can not only be processed into the rotating shaft mechanism 140, but also into other components with high requirements for strength and toughness.

[0086] Furthermore, the high-strength and high-toughness steel provided in this application embodiment can also be applied to other technical fields, such as photovoltaics, semiconductors, etc., for manufacturing other devices, for precision forging dies and plastic molds. This application does not limit the application fields.

[0087] Figure 8 This is a flowchart illustrating a method for preparing high-strength and high-toughness steel according to an embodiment of this application. (Refer to...) Figure 8 As shown, the preparation method of high-strength and high-toughness steel includes the following steps.

[0088] S100, Smelting and Casting: High-purity metals are smelted in the following weight percentages: Nickel (Ni): 16wt% ≤ Ni ≤ 19wt%; Cobalt (Co): 13wt% ≤ Co ≤ 16wt%; Molybdenum (Mo): 5wt% ≤ Mo ≤ 7wt%; Titanium (Ti): 0.5wt% ≤ Ti ≤ 2.0wt%; Aluminum (Al): 0.1wt% ≤ Al ≤ 0.5wt%; La: 0wt% < La ≤ 0.01wt%; Ce: 0wt% < Ce ≤ 0.01wt%; Y: 0wt% < La ≤ 0.01wt%; the balance being iron (Fe) and unavoidable impurities. This is done using a combination of a vacuum induction furnace and a vacuum arc furnace, or a combination of an electric arc furnace and a vacuum arc furnace. The molten metal is poured into a pre-prepared mold, and after cooling and solidification, metal parts of the desired shape are obtained. The billet is heated to 1100℃-1200℃ and held in the furnace for 15-20 hours.

[0089] S200, Forging or Rolling: Forging or rolling the steel billet to a final forging temperature of 800℃-900℃.

[0090] S300, Heat Treatment: Includes solution treatment, cryogenic treatment, and aging treatment. Forged or rolled steel is directly brought to its usable state after solution treatment, or it is slowly cooled before offline treatment. For solution treatment, the temperature can be set to 750℃-900℃ for rolled steel plates, bars, or forged billets, with a solution treatment time of 1-2 hours, depending on product performance requirements. Then, liquid nitrogen cryogenic treatment is performed for 1-2 hours. After cryogenic treatment, the billet undergoes failure treatment, with aging treatment at 450℃-550℃ and a holding time of 1-4 hours.

[0091] After the above steps, the high-strength and high-toughness steel product provided in this application embodiment is obtained. Its internal microstructure contains a large amount of martensite and austenite, and the material has high strength and toughness. Martensite generally exists in a lath-like structure, and retained austenite is distributed between the lath-like martensite or at the grain boundaries.

[0092] According to the embodiments of this application, the high-strength and high-toughness steel (product) has a yield strength of over 2900 MPa; a material hardness (surface / core) of over 740 HV; a material elongation of over 5%; and a tensile strength of over 3000 MPa. Compared with existing high-strength and high-toughness steels, the strength and toughness are significantly improved.

[0093] The room temperature mechanical properties of the high-strength and high-toughness steel provided in this application will be explained below through one comparative example and ten specific embodiments.

[0094] Comparative Example 1

[0095] The high-strength and high-toughness steel in Comparative Example 1 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, with the total of other impurity elements less than or equal to 0.2 wt%, and the balance being Fe.

[0096] The following preparation method was used:

[0097] (1) Smelting and casting: Smelting is carried out using a combination of vacuum induction furnace and vacuum arc furnace, or a combination of electric arc furnace and vacuum arc furnace. The molten metal is poured into a pre-prepared mold and allowed to cool and solidify to obtain the metal parts of the desired shape. The billet is heated to 1200℃ and held in the furnace for 15 hours.

[0098] (2) Forging: The steel billet is forged at a final forging temperature of 900℃. Slow cooling is performed after forging.

[0099] (3) Heat treatment: The forging billet is subjected to solution treatment at 750℃ for 2 hours, deep cryogenic treatment with liquid nitrogen for 1 hour, and aging treatment at 550℃ for 1 hour.

[0100] The sample of Comparative Example 1 was obtained.

[0101] Example 1

[0102] The high-strength and high-toughness steel in Example 1 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, Ce: 0.001 wt%, the total of other impurity elements is less than or equal to 0.2 wt%, and the balance is Fe.

[0103] The following preparation method was used:

[0104] (1) Smelting and casting: Smelting is carried out using a combination of vacuum induction furnace and vacuum arc furnace, or a combination of electric arc furnace and vacuum arc furnace. The molten metal is poured into a pre-prepared mold and allowed to cool and solidify to obtain the metal parts of the desired shape. The billet is heated to 1100℃ and held in the furnace for 20 hours.

[0105] (2) Forging: The steel billet is forged at a final forging temperature of 800℃. Slow cooling is performed after forging.

[0106] (3) Heat treatment: The forging billet is subjected to solution treatment at 900℃ for 1 hour, deep cryogenic treatment with liquid nitrogen for 2 hours, and aging treatment at 450℃ for 4 hours.

[0107] Sample 1 of Example 1 was obtained.

[0108] Example 2

[0109] The high-strength and high-toughness steel in Example 2 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, Ce: 0.006 wt%, the total of other impurity elements is less than or equal to 0.2 wt%, and the balance is Fe.

[0110] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0111] Sample 2 of Example 2 was obtained.

[0112] Example 3

[0113] The high-strength and high-toughness steel in Example 3 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, Ce: 0.01 wt%, the total of other impurity elements is less than or equal to 0.2 wt%, and the balance is Fe.

[0114] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0115] Sample 3 of Example 3 was obtained.

[0116] Example 4

[0117] The high-strength and high-toughness steel in Example 4 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, La: 0.003 wt%, Ce: 0.003 wt%, with the total of other impurity elements less than or equal to 0.2 wt%, and the balance being Fe.

[0118] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0119] Sample 4 of Example 4 was obtained.

[0120] Example 5

[0121] The high-strength and high-toughness steel in Example 5 comprises the following components: Ni: 17.5wt%, Co: 14.8wt%, Mo: 6.5wt%, Ti: 1.4wt%, Al: 0.2wt%, La: 0.005wt%, Ce: 0.005wt%, with the total of other impurity elements less than or equal to 0.2wt%, and the balance being Fe.

[0122] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0123] Sample 5 of Example 5 was obtained.

[0124] Example 6

[0125] The high-strength and high-toughness steel in Example 6 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, La: 0.001 wt%, Ce: 0.001 wt%, Y: 0.001 wt%, with the total of other impurity elements less than or equal to 0.2 wt%, and the balance being Fe.

[0126] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0127] Sample 6 of Example 6 was obtained.

[0128] Example 7

[0129] The high-strength and high-toughness steel in Example 7 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, La: 0.001 wt%, Ce: 0.002 wt%, Y: 0.001 wt%, with the total of other impurity elements less than or equal to 0.2 wt%, and the balance being Fe.

[0130] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0131] Sample 7 of Example 7 was obtained.

[0132] Example 8

[0133] The high-strength and high-toughness steel in Example 8 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, La: 0.001 wt%, Ce: 0.003 wt%, Y: 0.001 wt%, with the total of other impurity elements less than or equal to 0.2 wt%, and the balance being Fe.

[0134] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0135] Sample 8 of Example 8 was obtained.

[0136] Example 9

[0137] The high-strength and high-toughness steel in Example 9 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, La: 0.002 wt%, Ce: 0.003 wt%, Y: 0.001 wt%, with the total of other impurity elements less than or equal to 0.2 wt%, and the balance being Fe.

[0138] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0139] Sample 9 of the embodiment was obtained.

[0140] Example 10

[0141] The high-strength and high-toughness steel in Example 10 comprises the following components: Ni: 17.5 wt%, Co: 14.8 wt%, Mo: 6.5 wt%, Ti: 1.4 wt%, Al: 0.2 wt%, La: 0.002 wt%, Ce: 0.002 wt%, Y: 0.002 wt%, with the total of other impurity elements less than or equal to 0.2 wt%, and the balance being Fe.

[0142] Apart from the differences mentioned above, its preparation process is the same as that of Comparative Example 1.

[0143] Sample 10 of Example 10 was obtained.

[0144] The room temperature mechanical properties of the samples from the above-mentioned comparative example and 10 embodiments were tested: yield strength, tensile strength, elongation and hardness. The results are shown in Table 1.

[0145] Table 1: Room temperature mechanical properties of Comparative Example 1 and Examples 1-10

[0146] sample Yield strength (MPa) Tensile strength (MPa) elongation % Hardness HV Comparative Example 1 2860 2970 5 740 Example 1 2980 3091 6 744 Example 2 3031 3201 8 756 Example 3 3100 3254 7 761 Example 4 3065 3215 8 759 Example 5 3118 3259 7 768 Example 6 3113 3255 9 766 Example 7 3211 3346 10 770 Example 8 3240 3385 10 772 Example 9 3255 3389 9 775 Example 10 3085 3219 8 760

[0147] As can be seen from Table 1, in the high-strength and high-toughness steel provided in the embodiments of this application, due to the addition of La, Ce and / or Y, and by maintaining the weight percentage of La, Ce and / or Y in the high-strength and high-toughness steel within a certain range, the yield strength of the samples corresponding to the embodiments can all reach above 2900 MPa, with a maximum of 3255 MPa, far exceeding the yield strength of the comparative example, i.e., 2860 MPa; the tensile strength of the samples corresponding to the embodiments can all reach above 3000 MPa, with a maximum of 3389 MPa, far exceeding the tensile strength of the comparative example, i.e., 2970 MPa; the elongation of the samples corresponding to the embodiments can all reach above 6%, with a maximum of 10%, far exceeding the elongation of the comparative example, i.e., 5%; the hardness of the samples corresponding to the embodiments can all reach above 740 HV, with a maximum of 775 HV, far exceeding the hardness of the comparative example, i.e., 740 HV.

[0148] As can be seen from Examples 6 to 10, when the weight percentages of La, Ce and Y are all between 0 and 0.006 wt%, and the ratio of the sum of the weights of La and Ce to the weight of Y is 2:1 ≤ (La + Ce): Y ≤ 5:1, the yield strength, tensile strength, elongation and hardness of the high-strength and tough steel are significantly improved.

[0149] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0150] In the description of the embodiments of this application, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, c can represent a, b, c, a and b, a and c, b and c, a and b and c, where a, b, and c can be a single item or a plurality of items.

[0151] In the description of embodiments of this application, "parallel," "perpendicular," "equal," and "coplanar" include the described situation and situations similar to the described situation, the range of which is within an acceptable deviation range, wherein the acceptable deviation range is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximately parallelism, wherein the acceptable deviation range for approximately parallelism may be, for example, within ±10° or ±5°. "Perpendicular" includes absolute perpendicularity and approximately perpendicularity, wherein the acceptable deviation range for approximately perpendicularity may be, for example, within ±10° or ±5°; "equal" includes absolute equality and approximately equality, wherein the acceptable deviation range for approximately equality may be, for example, the difference between the two equals being less than or equal to 5% of either one. For example, an angle of 180° between two components includes both absolute 180° and approximate 180°, where an acceptable deviation range for approximate 180° could be, for example, within ±10° or ±5°; similarly, an angle of 0° between two components includes both absolute 0° and approximate 0°, where an acceptable deviation range for approximate 0° could be, for example, within ±10° or ±5°. Similarly, an angle of 90° between two components includes both absolute 90° and approximate 90°, where an acceptable deviation range for approximate 90° could be, for example, within ±10° or ±5°.

[0152] In embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0153] The directional terms used in the embodiments of this application, such as "inner" and "outer," are merely for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or a specific orientation structure and operation. Therefore, they should not be construed as limitations on the embodiments of this application. Furthermore, unless otherwise stated in this application, "multiple" in this application refers to two or more.

[0154] In the embodiments of this application, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0155] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0156] The terms "first," "second," "third," "fourth," etc. (if present) in the claims, description, and drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0157] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them; although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A high-strength and high-toughness steel, characterized in that, The high-strength and high-toughness steel comprises the following components, and the weight percentage of each component is as follows: Nickel: [16wt%, 19wt%]; Cobalt: [13wt%, 16wt%]; Molybdenum: [5wt%, 7wt%]; Titanium: [0.5wt%, 2.0wt%]; Rare earth elements: (0, 0.03wt%); Balance iron and unavoidable impurities, wherein the weight percentage of said unavoidable impurities is less than or equal to 0.2wt%.

2. The high-strength and high-toughness steel according to claim 1, characterized in that, The rare earth elements include lanthanum and / or cerium and / or yttrium, and the weight percentage in the high-strength and high-toughness steel is: Lanthanum: (0 wt%, 0.01 wt%) and / or cerium: (0 wt%, 0.01 wt%) and / or yttrium: (0 wt% < La ≤ 0.01 wt%).

3. The high-strength and high-toughness steel according to claim 2, characterized in that, The rare earth element includes the lanthanum, and the weight percentage of the lanthanum in the high-strength and high-toughness steel is (0 wt%, 0.006 wt%).

4. The high-strength and high-toughness steel according to claim 2 or 3, characterized in that, The rare earth element includes cerium, and the weight percentage of cerium in the high-strength and high-toughness steel is (0 wt%, 0.006 wt%).

5. The high-strength and high-toughness steel according to any one of claims 2-4, characterized in that, The rare earth element includes yttrium, and the weight percentage of yttrium in the high-strength and high-toughness steel is (0 wt%, 0.006 wt%).

6. The high-strength and high-toughness steel according to claim 2, characterized in that, The rare earth elements include the lanthanum and the cerium, and the weight percentage of the sum of the weights of the lanthanum and the cerium in the high-strength and high-toughness steel is (0 wt%, 0.006 wt%).

7. The high-strength and high-toughness steel according to claim 6, characterized in that, The rare earth elements also include yttrium, and the total weight percentage of lanthanum, cerium and yttrium in the high-strength and tough steel is (0 wt%, 0.006 wt%).

8. The high-strength and high-toughness steel according to claim 7, characterized in that, The ratio of the sum of the weights of the lanthanum and the cerium to the weight of the yttrium is [2, 5].

9. The high-strength and high-toughness steel according to any one of claims 1-8, characterized in that, The unavoidable impurities include components manganese and silicon, wherein the weight percentage of manganese is less than 0.5 wt% and the weight percentage of silicon is less than 0.5 wt%.

10. The high-strength and high-toughness steel according to any one of claims 1-9, characterized in that, It also includes aluminum, which is [0.1wt%, 0.5wt% by weight].

11. A rotating shaft mechanism, characterized in that, At least a portion of the material of the shaft mechanism comprises high-strength and high-toughness steel as described in any one of claims 1-10.

12. The rotating shaft mechanism according to claim 11, characterized in that, include: The base and the swing arm, the swing arm being rotatably connected to the base, and at least a portion of the material of the swing arm comprising high-strength and high-toughness steel as described in any one of claims 1-10.

13. A foldable electronic device, characterized in that, include: The flexible screen, the first main body, the second main body, and the rotating shaft mechanism as described in claim 11 or 12; The first main body and the second main body are connected by the pivot mechanism, which is configured to allow the first main body to unfold and fold relative to the second main body. The flexible screen is attached to the first main body and the second main body.

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