Method for welding steel, steel piece and use thereof

Abstract

The application relates to a steel welding method, which comprises the following steps: providing a micro-alloy steel; performing laser surface alloying treatment on a region of the micro-alloy steel to be welded to form an alloy layer; performing ion injection treatment on the alloy layer to obtain a to-be-welded layer; performing welding on the micro-alloy steel by taking the to-be-welded layer as a welding operation region to obtain a welded product; and performing annealing treatment on the welded product, wherein the micro-alloy steel comprises 0.05-0.5% of neodymium, 0.05-0.5% of lanthanum, 0.3-1.5% of niobium and 0.3-1.5% of molybdenum in percentage of the mass of the micro-alloy steel. The steel welding method provided by the application can make the material of the welded structure have high tensile strength and impact toughness, and is beneficial to reducing welding defects.

Description

Technical Field

[0001] This application relates to the field of steel materials, and more particularly to the field of steel welding technology. Background Technology

[0002] The welding process for railway freight car steel structures is one of the key processes in railway transportation equipment manufacturing. This process involves welding steel into the freight car body and load-bearing structure to ensure the strength, stability, and safety of the freight car during operation. The quality of the welding process directly affects the service life and operational reliability of the freight car; therefore, improving the performance of steel structure welding has always been a key focus in the field of engineering technology.

[0003] Existing welding processes for railway freight car steel structures typically employ traditional methods such as manual arc welding, gas shielded welding, and automatic submerged arc welding. These methods melt the surface of the steel at high temperatures, forming a strong welded joint upon cooling, thus achieving structural connection. Manual arc welding is widely used for welding complex structures due to its operational flexibility, while gas shielded welding is favored for its high weld quality and suitability for large-scale production, and automatic submerged arc welding is characterized by high efficiency and deep penetration. However, despite these railway freight car steel structure welding processes achieving certain results in improving steel connection strength and increasing production efficiency, they still have significant shortcomings in dealing with high-strength, long-term operation, and harsh environmental conditions. Specifically, the tensile strength and impact toughness of the welded joints are not ideal, corrosion resistance is poor, and the consistency of weld quality is unstable, easily leading to defects such as cracks, porosity, and lack of fusion. These defects directly affect the safety and service life of the freight cars. Summary of the Invention

[0004] This application provides a steel welding method, steel components, and their applications to solve the technical problem of insufficient tensile strength and impact toughness of welded joints.

[0005] In a first aspect, embodiments of this application provide a steel welding method, the steel welding method comprising the following steps:

[0006] Microalloy steel is available;

[0007] The area of ​​the microalloyed steel to be welded is subjected to laser surface alloying treatment to form an alloy layer in the area to be welded.

[0008] Nitrogen ions and titanium ions are implanted into the alloy layer using an ion implantation process to obtain the layer to be welded;

[0009] The microalloy steel is welded using the layer to be welded as the welding operation area, and a welded part is obtained after welding is completed.

[0010] The welded parts are subjected to annealing treatment.

[0011] The microalloyed steel comprises, by mass percentage, 0.05% to 0.5% neodymium, 0.05% to 0.5% lanthanum, 0.3% to 1.5% niobium, and 0.3% to 1.5% molybdenum.

[0012] In some embodiments of this application, the welding current is 200–500 A; and / or,

[0013] The welding voltage is 25–50V; and / or,

[0014] The welding speed is 150–600 mm / min; and / or,

[0015] The welding temperature is 300–400°C; and / or,

[0016] The laser power for the laser surface alloying treatment is 1500–3000 W; and / or,

[0017] The thickness of the alloy layer is 20–60 μm; and / or,

[0018] The ion implantation process has an ion energy range of 50–150 keV; and / or,

[0019] The annealing temperature is 550–700°C; and / or,

[0020] The annealing process lasts for 1 to 5 hours.

[0021] In some embodiments of this application, prior to welding the microalloyed steel, the steel welding method further includes the following steps:

[0022] Nanoparticles are coated onto the layer to be soldered to form a nano-protective layer.

[0023] In some embodiments of this application, the nanoparticles are made of at least one of silicon dioxide or titanium dioxide; and / or,

[0024] The thickness of the nano-protective layer is 3–15 μm.

[0025] In some embodiments of this application, prior to welding the microalloyed steel, the steel welding method further includes the following steps:

[0026] The layer to be soldered is subjected to ultrasonic treatment.

[0027] In some embodiments of this application, the ultrasonic frequency of the ultrasonic treatment is 15kHz to 45kHz.

[0028] In some embodiments of this application, after annealing the welded component, the steel welding method further includes the following steps:

[0029] The weld seam of the welded component is ground.

[0030] In some embodiments of this application, the weld of the welded component is ground to a surface roughness between Ra3.2μm and Ra0.8μm.

[0031] Secondly, embodiments of this application provide a steel component, which is obtained by welding the steel welding method described in any embodiment of the first aspect.

[0032] Thirdly, embodiments of this application provide a railway freight car, which includes the steel components described in any embodiment of the second aspect.

[0033] The technical solutions provided in this application have the following advantages compared with the prior art:

[0034] The steel welding method provided in this application uses microalloyed steel as the welding material and performs laser surface alloying and ion implantation processes on the surface of the microalloyed steel to form a weldable layer with high strength and toughness, so that the material of the welded structure has high tensile strength and impact toughness. In addition, the weldable layer formed by laser surface alloying and ion implantation processes has good uniformity, which makes the welded structure have good consistency, which helps to reduce welding defects such as cracks, porosity and lack of fusion, and ensures the reliability and safety of the welded structure. Attached Figure Description

[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic flowchart of a steel welding method provided in an embodiment of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any conflict, this specification shall prevail.

[0040] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0041] Existing steel welding processes suffer from insufficient tensile strength and impact toughness in welded joints.

[0042] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0043] In a first aspect, embodiments of this application provide a steel welding method, the steel welding method comprising the following steps:

[0044] S1: Available in microalloyed steel;

[0045] S2: Perform laser surface alloying treatment on the area of ​​the microalloyed steel to be welded, and form an alloy layer in the area to be welded.

[0046] S3: Nitrogen ions and titanium ions are implanted into the alloy layer by an ion implantation process to obtain the layer to be welded;

[0047] S4: Weld the microalloyed steel using the layer to be welded as the welding operation area, and obtain the welded part after welding is completed;

[0048] S5: Anneal the welded part.

[0049] The microalloyed steel comprises, by mass percentage, 0.05% to 0.5% neodymium, 0.05% to 0.5% lanthanum, 0.3% to 1.5% niobium, and 0.3% to 1.5% molybdenum.

[0050] Microalloyed steel is a type of steel in which trace amounts of alloying elements have been added to the base chemical composition of ordinary mild steel and ordinary high-strength low-alloy steel. The addition of these trace alloying elements significantly enhances one or more properties of the steel. Microalloyed steel typically exhibits good cold and hot formability and weldability, especially at low and ultra-low carbon contents. The main alloying elements added to microalloyed steel include titanium, vanadium, niobium, boron, aluminum, zirconium, and tantalum. These elements can form various compounds with elements such as carbon, nitrogen, oxygen, and sulfur in the steel, resulting in a variety of effects on the steel's properties.

[0051] This application selects a microalloyed steel comprising 0.05%–0.5% neodymium, 0.05%–0.5% lanthanum, 0.3%–1.5% niobium, and 0.3%–1.5% molybdenum. Neodymium and lanthanum, as rare earth elements, effectively improve the microstructure and cleanliness of the steel upon addition. These elements contribute to refining the steel's structure, enhancing the toughness of the weld heat-affected zone by refining grain size. Niobium and molybdenum are key microalloying elements for strengthening steel properties; they enhance the strength and hardness of the material by forming fine carbide and / or nitride particles. These particles, dispersed in the steel, effectively hinder dislocation movement, thereby improving the material's yield strength and fatigue resistance, and giving railway freight car steel structures higher safety and reliability under long-term fatigue loads and harsh environmental conditions. The aforementioned trace metallic elements improve the steel's cleanliness and grain refinement, thereby enhancing the toughness of the weld heat-affected zone, while also increasing the material's strength and toughness, resulting in welded structures with higher load-bearing capacity and better fatigue resistance.

[0052] Laser surface alloying is an advanced material surface treatment technology that utilizes the rapid heating and melting characteristics of a high-energy-density laser beam to melt and mix the substrate surface and added alloying elements, thereby forming a new surface alloy layer based on the original substrate. The laser beam can precisely control the treated area, achieving localized strengthening of the material surface. Through laser treatment, the alloying elements and the substrate achieve excellent metallurgical bonding, forming a high-performance alloy layer. Compared with traditional surface treatment technologies, laser surface alloying is faster, significantly improving production efficiency. The strengthening mechanism of laser surface alloying is a comprehensive result of phase transformation hardening, solid solution strengthening, and carbide strengthening. Among these, carbide second-phase strengthening is the most important strengthening mechanism, enabling the alloy layer to achieve hardness exceeding that of the base material and significantly improving wear resistance. The high energy of the laser not only ensures rapid alloying but also enables rapid cooling, preventing excessive oxidation and annealing of the alloy layer. This rapid solidification process results in an alloy layer with a very fine grain structure, which significantly enhances its wear resistance and corrosion resistance, improves the wear and corrosion resistance of the steel surface, and by precisely controlling the thickness and uniformity of the alloy layer, not only is the surface hardness of the material increased, but its resistance to fatigue fracture is also improved. This makes the steel structure more resistant to performance degradation caused by wear and corrosion during long-term service, thereby extending the service life of railway freight cars and reducing operational interruptions caused by maintenance and repair.

[0053] The basic principle of ion implantation is to accelerate charged impurity ions, enabling them to enter the matrix of solid materials (such as semiconductors and metals) at high energy. During this process, the accelerated dopant ions bombard the surface of the solid material at extremely high speeds and penetrate to a certain depth. By controlling the ion energy and implantation dosage, the depth and concentration of impurity ion distribution can be precisely controlled. This application implants nitrogen and titanium ions into the alloy layer. These ions replace existing atoms in the material's crystal lattice or form solid solutions in the interstitial spaces, causing lattice distortion. This distortion significantly improves the material's hardness and wear resistance because the denser lattice structure increases the interatomic interaction forces, thus increasing the difficulty of dislocation movement. Ion implantation treatment enhances the surface hardness of the steel. Furthermore, the increased hardness also leads to better corrosion resistance, as a harder surface is more difficult to erode or penetrate. Ultimately, this surface modification technology extends the service life of steel structures, reduces long-term maintenance and replacement costs, and improves the reliability and efficiency of railway freight cars in operation.

[0054] Furthermore, it is easy to understand that both laser surface alloying and ion implantation are stable and uniform processing techniques, which makes the material uniformity of the layer to be welded good, thereby improving the consistency of the welded structure and helping to reduce welding defects such as cracks, porosity and lack of fusion, thus ensuring the reliability and safety of the welded structure.

[0055] This application selects microalloyed steel as the welding material and performs laser surface alloying and ion implantation processes on the surface of the microalloyed steel to form a weldable layer with high strength and toughness, so that the material of the welded structure has high tensile strength and impact toughness. In addition, the weldable layer formed by laser surface alloying and ion implantation processes has good uniformity, which makes the welded structure have good consistency and helps to reduce welding defects such as cracks, porosity and lack of fusion, thus ensuring the reliability and safety of the welded structure.

[0056] In some embodiments of this application, the welding current is 200–500 A; and / or,

[0057] The welding voltage is 25–50V; and / or,

[0058] The welding speed is 150–600 mm / min; and / or,

[0059] The welding temperature is 300–400°C; and / or,

[0060] The laser power for the laser surface alloying treatment is 1500–3000 W; and / or,

[0061] The thickness of the alloy layer is 20–60 μm; and / or,

[0062] The ion implantation process has an ion energy range of 50–150 keV; and / or,

[0063] The annealing temperature is 550–700°C; and / or,

[0064] The annealing process lasts for 1 to 5 hours.

[0065] Selecting the above-mentioned range for the welding process parameters is beneficial for obtaining welded structures with optimal tensile strength and impact toughness. Appropriate current and voltage levels ensure arc stability and sufficient heat input, which are crucial for melting the steel and forming a uniform weld. A welding speed of 150–600 mm / min helps control the weld formation rate and the size of the heat-affected zone (HAZ). By controlling the welding speed, the HAZ and penetration depth of the weld can be affected, thereby influencing the microstructure and mechanical properties of the welded structure. A welding temperature of 300–400°C ensures optimal weld quality, optimizes heat input and cooling rate, and prevents overheating or excessive cooling of the weld. Excessive temperature can lead to weld defects such as burn-through, while excessively low temperatures may result in incomplete welding. An annealing temperature of 550–700°C and an annealing duration of 1–5 hours allow the atoms in the steel to rearrange, thereby eliminating the inhomogeneous lattice distortion formed during welding. Maintaining the above temperature for the above time period allows new grain boundaries to form, thereby enhancing the overall toughness and strength of the material. Through the above annealing treatment, the welded structure can obtain significantly improved mechanical properties, including enhanced tensile strength, improved fatigue life and better crack resistance.

[0066] As an example, the welding current can be 200A, 300A, 400A, or 500A.

[0067] As an example, the welding voltage can be 25V, 30V, 35V, 40V, 45V, or 50V.

[0068] As an example, the welding speed can be 150 mm / min, 300 mm / min, 450 mm / min, or 600 mm / min.

[0069] As an example, the welding temperature can be 300℃, 320℃, 340℃, 360℃, 380℃, or 400℃.

[0070] As an example, the laser power for the laser surface alloying treatment can be 1500W, 2000W, 2500W, or 3000W.

[0071] As an example, the thickness of the alloy layer can be 20μm, 30μm, 40μm, 50μm, or 60μm.

[0072] As an example, the ion energy range of the ion implantation process can be 50keV, 70keV, 100keV, 80keV, or 150keV.

[0073] As an example, the annealing temperature can be 550°C, 600°C, 650°C, or 700°C.

[0074] As an example, the duration of the annealing can be 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours.

[0075] In some embodiments of this application, prior to welding the microalloyed steel, the steel welding method further includes the following steps:

[0076] S31: Nanoparticles are coated on the layer to be soldered to form a nano protective layer.

[0077] It's easy to understand that the purpose of preparing a nano-protective layer is to increase the corrosion resistance of welded structures. Nanoparticles form a high-density nano-protective layer on the steel surface, effectively blocking direct contact between moisture and oxygen and the metal surface, thereby enhancing the corrosion resistance of the welded structure. This is especially beneficial in rainy or humid environments, effectively extending the service life of the welded structure and reducing maintenance requirements. Furthermore, the nano-coating can absorb and disperse oxidation stress transmitted through the coating to a certain extent, thereby reducing the oxidation rate and enhancing the corrosion and oxidation resistance of the steel, particularly in harsh external environments such as high humidity or salt spray conditions.

[0078] In some embodiments of this application, the nanoparticles are made of at least one of silicon dioxide or titanium dioxide; and / or,

[0079] The thickness of the nano-protective layer is 3–15 μm.

[0080] It's easy to understand that the main function of the nano-protective layer is to isolate water and oxygen. Therefore, chemically stable nanoparticles can be chosen as the material, and it is not limited to silicon dioxide and titanium dioxide. For example, tin dioxide can also be used. Silica nanoparticles and titanium dioxide nanoparticles are inexpensive and readily available nanomaterials on the market, and they are chemically stable.

[0081] As an example, the thickness of the nanoprotective layer can be 3μm, 6μm, 9μm, 12μm, or 15μm.

[0082] In some embodiments of this application, prior to welding the microalloyed steel, the steel welding method further includes the following steps:

[0083] S32: Perform ultrasonic treatment on the layer to be soldered.

[0084] Ultrasonic treatment of the layer to be welded can improve the material uniformity of the layer, increase the reliability of the welding process, and reduce welding defects. The energy of ultrasound can break the existing grain boundaries and promote the formation of new grain boundaries. These newly formed fine grains have higher interfacial energy, which helps to enhance the overall mechanical properties of the material, thereby improving the microstructure of the steel. This makes the fusion of materials more uniform during the welding process, reduces the occurrence of welding defects such as porosity and lack of fusion, and improves the quality and consistency of the weld. This increases the static and fatigue strength of the welded structure, effectively extends the service life of the freight car structure, reduces maintenance costs, and improves the operating efficiency of railway freight cars.

[0085] In some embodiments of this application, the ultrasonic frequency of the ultrasonic treatment is 15kHz to 45kHz.

[0086] As an example, the ultrasonic frequency of the ultrasonic treatment can be 15kHz, 25kHz, 35kHz, or 45kHz.

[0087] In some embodiments of this application, after annealing the welded component, the steel welding method further includes the following steps:

[0088] S51: Grind the weld seam of the welded component.

[0089] It is easy to understand that the grinding can be performed using devices such as grinding wheels or abrasive belts. Grinding the weld seams of the welded components helps improve the smoothness and aesthetics of the welded structure surface. Mechanical grinding removes high points and irregularities from the welded structure surface, smoothing the weld seam and improving appearance quality. The grinding process not only removes surface defects but also locally anneals the weld area through the minute heat generated during grinding, helping to release welding stress, improve the material's microstructure, and thus enhance the surface smoothness and appearance quality of the welded structure. It also strengthens its corrosion resistance and fatigue life. Furthermore, a smooth surface reduces the formation of eddies and turbulence, which is particularly important for railway freight cars transporting liquid or gaseous products, reducing hydrodynamic losses.

[0090] In some embodiments of this application, the weld of the welded component is ground to a surface roughness between Ra3.2μm and Ra0.8μm.

[0091] As an example, the surface roughness of the weld can be ground to Ra3.2μm, Ra2.4μm, Ra1.6μm, or Ra0.8μm.

[0092] Secondly, embodiments of this application provide a steel component, which is obtained by welding the steel welding method described in any embodiment of the first aspect.

[0093] The steel component is realized based on the above-described steel welding method. The specific implementation of the steel component can be referred to the above embodiments and common knowledge in the field. Since the steel component adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0094] Thirdly, embodiments of this application provide a railway freight car, which includes the steel components described in any embodiment of the second aspect.

[0095] The railway freight car is based on the aforementioned steel components. The specific implementation of the railway freight car can be referred to the above embodiments and common knowledge in the field. Since the railway freight car adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0096] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0097] Example 1

[0098] This embodiment provides a steel welding method, which includes the following steps:

[0099] Microalloy steel is available;

[0100] The area of ​​the microalloyed steel to be welded is subjected to laser surface alloying treatment to form an alloy layer in the area to be welded.

[0101] Nitrogen ions and titanium ions are implanted into the alloy layer using an ion implantation process to obtain the layer to be welded;

[0102] Silica nanoparticles are coated onto the layer to be soldered to form a nano-protective layer.

[0103] The layer to be soldered is subjected to ultrasonic treatment;

[0104] The microalloy steel is welded using the layer to be welded as the welding operation area, and a welded part is obtained after welding is completed.

[0105] The welded parts are subjected to annealing treatment.

[0106] The weld seam of the welded component is ground.

[0107] The microalloyed steel comprises, by mass percentage, 0.1% neodymium, 0.1% lanthanum, 0.5% niobium, and 0.5% molybdenum.

[0108] The welding current is 350A, the welding voltage is 30V, the welding speed is 300mm / min, the welding temperature is 350℃, the laser power for laser surface alloying is 2000W, the thickness of the alloy layer is 40μm, the ion energy range for the ion implantation process is 100keV, the annealing temperature is 600℃, and the annealing duration is 3h. The thickness of the nano-protective layer is 10μm. The ultrasonic frequency for the ultrasonic treatment is 30kHz.

[0109] The weld seam of the welded component is ground to reduce its surface roughness to Ra1.0μm.

[0110] Example 2

[0111] This embodiment provides a steel welding method, which includes the following steps:

[0112] Microalloy steel is available;

[0113] The area of ​​the microalloyed steel to be welded is subjected to laser surface alloying treatment to form an alloy layer in the area to be welded.

[0114] Nitrogen ions and titanium ions are implanted into the alloy layer using an ion implantation process to obtain the layer to be welded;

[0115] Silica nanoparticles are coated onto the layer to be soldered to form a nano-protective layer.

[0116] The layer to be soldered is subjected to ultrasonic treatment;

[0117] The microalloy steel is welded using the layer to be welded as the welding operation area, and a welded part is obtained after welding is completed.

[0118] The welded parts are subjected to annealing treatment.

[0119] The weld seam of the welded component is ground.

[0120] The microalloyed steel comprises, by mass percentage, 0.3% neodymium, 0.3% lanthanum, 1.0% niobium, and 1.0% molybdenum.

[0121] The welding current is 500A, the welding voltage is 50V, the welding speed is 150mm / min, the welding temperature is 400℃, the laser power for laser surface alloying is 3000W, the thickness of the alloy layer is 60μm, the ion energy range for the ion implantation process is 150keV, the annealing temperature is 700℃, and the annealing duration is 3h. The thickness of the nano-protective layer is 10μm. The ultrasonic frequency for the ultrasonic treatment is 30kHz.

[0122] The weld seam of the welded component is ground to reduce its surface roughness to Ra0.8μm.

[0123] Example 3

[0124] This embodiment provides a steel welding method, which includes the following steps:

[0125] Microalloy steel is available;

[0126] The area of ​​the microalloyed steel to be welded is subjected to laser surface alloying treatment to form an alloy layer in the area to be welded.

[0127] Nitrogen ions and titanium ions are implanted into the alloy layer using an ion implantation process to obtain the layer to be welded;

[0128] Silica nanoparticles are coated onto the layer to be soldered to form a nano-protective layer.

[0129] The layer to be soldered is subjected to ultrasonic treatment;

[0130] The microalloy steel is welded using the layer to be welded as the welding operation area, and a welded part is obtained after welding is completed.

[0131] The welded parts are subjected to annealing treatment.

[0132] The weld seam of the welded component is ground.

[0133] The microalloyed steel comprises, by mass percentage, 0.5% neodymium, 0.5% lanthanum, 1.5% niobium, and 1.5% molybdenum.

[0134] The welding current is 450A, the welding voltage is 45V, the welding speed is 600mm / min, the welding temperature is 350℃, the laser power for laser surface alloying is 2500W, the thickness of the alloy layer is 50μm, the ion energy range for the ion implantation process is 150keV, the annealing temperature is 650℃, and the annealing duration is 4h. The thickness of the nano-protective layer is 10μm. The ultrasonic frequency for the ultrasonic treatment is 30kHz.

[0135] The weld seam of the welded component is ground to reduce its surface roughness to Ra0.8μm.

[0136] Comparative Example 1

[0137] This comparative example uses the same microalloyed steel as Example 1, but without surface treatment, and welded parts are obtained directly under the same welding conditions as in Example 1. Specifically:

[0138] Microalloy steel is available;

[0139] The microalloy steel is welded to obtain a welded part after welding.

[0140] The welded parts are subjected to annealing treatment.

[0141] The weld seam of the welded component is ground.

[0142] The microalloyed steel comprises, by mass percentage, 0.1% neodymium, 0.1% lanthanum, 0.5% niobium, and 0.5% molybdenum.

[0143] The welding current is 350A, the welding voltage is 30V, the welding speed is 300mm / min, the welding temperature is 350℃, the annealing temperature is 600℃, and the annealing duration is 3h. The weld seam of the welded part is then ground to a surface roughness of Ra1.0μm.

[0144] Comparative Example 2

[0145] This comparative example uses ordinary commercial steel without surface treatment, and welded parts are obtained directly under the same welding conditions as in Example 1. Specifically:

[0146] Provide steel;

[0147] The steel is welded, and a welded part is obtained after welding.

[0148] The welded parts are subjected to annealing treatment.

[0149] The weld seam of the welded component is ground.

[0150] The welding current is 350A, the welding voltage is 30V, the welding speed is 300mm / min, the welding temperature is 350℃, the annealing temperature is 600℃, and the annealing duration is 3h. The weld seam of the welded part is then ground to a surface roughness of Ra1.0μm.

[0151] Relevant experimental and effect data:

[0152] Three sets of samples each of the welded components from Example 1, Comparative Example 1, and Comparative Example 2 were provided, with each set containing at least five samples. Tensile tests were performed on each sample using a universal testing machine, and the fracture strength was recorded. Charpy impact tests were performed using an impact testing machine, and the absorbed energy was recorded. All test data were collected, and the mean and standard deviation were calculated. The results are shown in Table 1.

[0153] Table 1

[0154] Sample grouping Sample type Tensile strength (MPa) Standard deviation (MPa) Impact energy (J) Standard deviation (J) Group 1 Example 1 620 15 35 2 Group 2 Example 1 615 20 36 1.5 Group 3 Example 1 630 18 37 3 Group 4 Comparative Example 1 590 22 30 2.5 Group 5 Comparative Example 1 595 19 31 2 Group 6 Comparative Example 1 580 20 29 2.2 Group 7 Comparative Example 2 550 25 25 3 Group 8 Comparative Example 2 560 30 24 3.5 Group 9 Comparative Example 2 555 28 26 2.8

[0155] The tensile strength and impact energy of Example 1 are higher than those of Comparative Examples 1 and 2, indicating that the welded structure exhibits significantly better tensile strength and impact toughness than untreated microalloyed steel and conventional commercial steel due to the use of laser surface alloying and ion implantation. These treatments improve the mechanical properties of the welded structure, demonstrating higher tensile strength and toughness.

[0156] Three sets of samples were provided for each of the welded components of Example 1, Comparative Example 1, and Comparative Example 2. Each set of samples included at least five samples. All samples were placed in a salt spray test chamber for a continuous 240-hour salt spray corrosion test. Subsequently, all samples were placed in the salt spray test chamber again for a continuous 240-hour salt spray corrosion test. All test data were collected, and the average value was calculated. The results are shown in Table 2.

[0157] Table 2

[0158]

[0159]

[0160] Example 1, after laser surface alloying, ion implantation and nanotechnology coating treatment, exhibits excellent corrosion resistance. Its corrosion rate is significantly lower than that of untreated Comparative Example 1 and conventional steel Comparative Example 2. Although the material of Comparative Example 1 has a certain degree of corrosion resistance, it still cannot compare with the treated Example 1.

[0161] Three sets of samples each of the welded components from Example 1, Comparative Example 1, and Comparative Example 2 were provided, with each set containing at least five samples. All samples were placed in a wear testing machine with the same load and rotation speed, and 10,000 cycles of wear testing were performed. The mass of the samples before and after wear was measured using a weighing device, and the amount of wear was recorded. All test data were collected, and the average value and standard deviation were calculated. The results are shown in Table 3.

[0162] Table 3

[0163]

[0164] Example 1, after laser surface alloying and ion implantation treatment, showed significantly improved surface hardness and wear resistance. Its hardness and wear rate were significantly better than those of the untreated Comparative Example 1 and the conventional steel Comparative Example 2. Although the material of Comparative Example 1 showed some improvement in hardness and wear resistance, it was still inferior to the material of the experimental group, indicating that surface treatment has a significant impact on material properties.

[0165] Three sets of samples each of the welded components from Example 1, Comparative Example 1, and Comparative Example 2 were provided. Each set of samples included at least five samples. Ultrasonic testing was performed on each welded sample, and the number and type of defects detected were recorded. X-ray testing was also performed on each welded sample to confirm and record the number and type of defects detected. All test data were collected, and the number of defects and defect rate for each sample were calculated. The results are shown in Table 4.

[0166] Table 4

[0167]

[0168] Example 1, after laser surface alloying, ion implantation, and nanotechnology coating treatment, exhibited the best welding quality consistency, with significantly fewer defects and types compared to the untreated Comparative Example 1 and the conventional steel Comparative Example 2. Although the material of Comparative Example 1 was better than that of Comparative Example 2 in terms of the number and types of defects, it was still far inferior to that of the experimental group, indicating that surface treatment has a significant impact on the consistency of welding quality.

[0169] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0170] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." Moreover, 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 limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. For relationships involving three or more related objects described using "and / or", it indicates that any one of the three related objects can exist alone, or at least two of them can exist simultaneously. For example, for A, and / or B, and / or C, it can mean that any one of A, B, and C exists alone, or any two of them exist simultaneously, or all three of them exist simultaneously. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. The "parts representation" involved in this application, such as parts by weight or parts by mass, indicates the proportional relationship between the components. In the proportional relationships involved in this application, the parameters that need to be described by proportion should be understood as the first term of the proportion in the order of description, and the proportion figures should be understood as the second term of the proportion. For example, if the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond one-to-one with the proportion figures in the proportion in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0171] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for welding steel, characterized in that, The steel welding method includes the following steps: Microalloy steel is available; The area of ​​the microalloyed steel to be welded is subjected to laser surface alloying treatment to form an alloy layer in the area to be welded. The thickness of the alloy layer is 20-60 μm, and the laser power of the laser surface alloying treatment is 1500-3000 W. Nitrogen ions and titanium ions are implanted into the alloy layer by ion implantation process to obtain the layer to be welded. The ion energy range of the ion implantation process is 50 to 150 keV. Silicon dioxide or titanium dioxide nanoparticles are coated onto the layer to be soldered to form a nano-protective layer. The microalloy steel is welded using the layer to be welded as the welding operation area. After welding, a welded part is obtained. The welding current is 200-500A; the welding voltage is 25-50V; the welding speed is 150-600mm / min; and the welding temperature is 300-400℃. The welded parts are subjected to annealing treatment at a temperature of 550–700°C for a duration of 1–5 hours. The microalloyed steel comprises, by mass percentage, 0.05% to 0.5% neodymium, 0.05% to 0.5% lanthanum, 0.3% to 1.5% niobium, and 0.3% to 1.5% molybdenum.

2. The steel welding method according to claim 1, characterized in that, The thickness of the nano-protective layer is 3–15 μm.

3. The steel welding method according to claim 1 or 2, characterized in that, Prior to welding the microalloyed steel, the steel welding method further includes the following steps: The layer to be soldered is subjected to ultrasonic treatment.

4. The steel welding method according to claim 3, characterized in that, The ultrasonic frequency of the ultrasonic treatment is 15kHz to 45kHz.

5. The steel welding method according to claim 1 or 2, characterized in that, After annealing the welded parts, the steel welding method further includes the following steps: The weld seam of the welded component is ground.

6. The steel welding method according to claim 5, characterized in that, The weld seam of the welded component is ground to a surface roughness between Ra3.2μm and Ra0.8μm.

7. A steel component, characterized in that, The steel component is obtained by welding steel using the steel welding method described in any one of claims 1 to 6.

8. A railway freight car, characterized in that, The railway freight car includes the steel component as described in claim 7.

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