A method and system for evaluating the vickers hardness of a welded joint of a marine steel

Abstract

The present application belongs to the technical field of welding hardness, and specifically provides a Vickers hardness evaluation method and system for a marine steel welded joint, wherein the method comprises: obtaining a thermal cycle curve of the welded joint of the marine steel, and performing discrete processing on the thermal cycle curve to obtain a temperature curve; inputting the chemical components related to the marine steel, and evaluating the key temperature of the metal solid-state phase change; calculating the percentage of each microstructure component that can currently participate in the metal solid-state phase change; according to the time step of the discrete processing, calculating the transient microstructure change in different temperature change intervals from heating to cooling in the welding process to obtain the final microstructure component ratio, and performing weighted summation calculation on different microstructures to obtain the final Vickers hardness. The scheme can accurately calculate the Vickers hardness value of the marine steel welded joint, does not need to damage the welded joint, has low cost and is convenient, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention relates to the field of welding hardness technology, and more specifically, to a method and system for evaluating the Vickers hardness of welded joints for marine steel. Background Technology

[0002] Marine-grade ordinary steel (Q235, Q345, etc.) and high-strength steel (EH46, EH56, etc.) plates are generally assembled and connected using carbon dioxide gas shielded welding. Meanwhile, thick marine steel plates require multi-layer, multi-pass welding, with multiple weld deposits used to fill the bevel. The complex heating and cooling thermal cycle of welding significantly affects the Vickers hardness of the weld joint; as hardness increases, the ductility and toughness of the steel decrease, resulting in reduced overall mechanical properties and weakened fracture resistance.

[0003] Vickers hardness was proposed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd.; it is a standard for expressing the hardness of materials. Specifically, Vickers hardness is determined by pressing a diamond pyramid indenter with an included angle of 136 degrees between its opposite faces into the surface of the test sample under a specified load F, holding it for a certain time, removing the load, measuring the diagonal length d of the indentation, calculating the surface area of ​​the indentation, and finally determining the average pressure on the surface area of ​​the indentation, which is the Vickers hardness value of the metal, represented by the symbol HV.

[0004] The formula for calculating the Vickers hardness of a material is:

[0005]

[0006] F = Load (Newtonian force)

[0007] S = Indentation surface area (square millimeters)

[0008] α = Angle between the opposing surfaces of the indenter = 136°

[0009] d = average indentation diagonal length (mm).

[0010] my country issued its first standard for testing the Vickers hardness of welded metals, GB2654—1981, "Test Method for Hardness of Welded Joints and Weld Overlay Metals," as early as 1981. In 1984, GB / T 4675.5—1984, "Test Method for Maximum Hardness of Welded Heat-Affected Zone," was developed and published, adopting the equivalent Japanese JIS Z3101—76 standard. GB / T4675.5—1984 was abolished in 2005, while GB 2654—1981 underwent two revisions in 1989 and 2008, and the current valid standard is GB / T 2654—2008 / ISO 9015—1:2001, "Hardness test methods on welded joints."

[0011] Currently, the Vickers hardness of welded joints of carbon steel is still measured using direct testing methods. There are relevant national and international standards for directly measuring the Vickers hardness of welded joints; however, this assessment method is too simplistic and has a high testing cycle cost.

[0012] The Vickers hardness measurement method requires sample preparation and pressure testing; this can damage the integrity of welded structures, and the process is cumbersome and expensive. For example, the surface of a Vickers hardness sample should be smooth and flat, free of oxide scale, impurities, and oil. Generally, the surface roughness parameter Ra of a Vickers hardness sample should not exceed 0.40 μm, for a low-load Vickers hardness sample not exceeding 0.20 μm, and for a micro Vickers hardness sample not exceeding 0.10 μm. (μm is the unit of surface roughness parameter Ra.) Summary of the Invention

[0013] This invention addresses the technical problems of existing Vickers hardness measurement methods, which require sample preparation and pressure testing, potentially damaging the integrity of welded structures, and are cumbersome and costly.

[0014] This invention provides a method for evaluating the Vickers hardness of welded joints of marine steel, comprising the following steps:

[0015] S1. Obtain the thermal cycle curve of the welded joint of marine steel, and discretize the thermal cycle curve to obtain the temperature curve.

[0016] S2, input the relevant chemical composition of marine steel, and evaluate the critical temperature of the solid-state phase transformation of the metal;

[0017] S3, calculate the percentage of each microstructure component that can currently participate in the solid-state phase transition of the metal;

[0018] S4. Based on the time step of the discretization process in step S1, calculate the transient microstructure changes in different temperature ranges during the welding process from heating to cooling, and then obtain the welding microstructure change model under different welding conditions.

[0019] S5. Obtain the current welding conditions, match them with the welding microstructure change model to obtain the volume fraction of the microstructure after cooling to room temperature, and perform weighted summation calculation on different microstructures to obtain the final Vickers hardness.

[0020] Preferably, S1 specifically includes:

[0021] By setting a time step, the continuous welding thermal cycle curve is discretized into several straight line segments indicating either an increase or decrease in temperature.

[0022] Preferably, the microstructure includes austenite, fully austenite, pearlite, ferrite, bainite, and martensite.

[0023] Preferably, S2 specifically includes: calculating the austenite transformation temperature, the complete austenitization temperature, the metal melting temperature during the heating process, and the phase transformation temperatures of austenite decomposing into pearlite, ferrite, bainite and martensite during the cooling process, based on the chemical composition of the marine steel.

[0024] Preferably, the temperature change range in S4 specifically includes: when the temperature is below the austenite transformation temperature; when the temperature is between the austenite transformation temperature and the complete austenitizing temperature; when the temperature is above the complete austenitizing temperature; when the austenite transforms into ferrite upon cooling; when the austenite transforms into pearlite upon cooling; when the austenite transforms into bainite upon cooling; when the austenite transforms into martensite upon cooling; and when the temperature drops to room temperature.

[0025] Preferably, S4 specifically includes: taking the average of the maximum and minimum values ​​of the temperature curve as the loading value of the temperature curve, with the loading time being the time step, and calculating the proportion of transient microstructures in different temperature change ranges.

[0026] Preferably, after step S4, the method further includes: spot welding a high-temperature platinum-rhodium alloy temperature sensor to the temperature measurement position to obtain the Vickers hardness test value in real time, and comparing and analyzing the test value with the summed calculated value to verify the calculated value.

[0027] This invention also provides a Vickers hardness evaluation system for marine steel welded joints, the system being used to implement a Vickers hardness evaluation method for marine steel welded joints, comprising:

[0028] The thermal cycling curve discretization module is used to obtain the thermal cycling curve of the welded joint of marine steel and to discretize the thermal cycling curve to obtain the temperature curve.

[0029] The critical temperature assessment module is used to input the relevant chemical composition of marine steel and assess the critical temperature of the metal solid-state phase transformation.

[0030] The current microstructure composition calculation module is used to calculate the percentage of each microstructure component that can participate in the solid-state phase transition of metals.

[0031] The transient microstructure change calculation module is used to calculate the transient microstructure changes in different temperature ranges during the welding process from heating to cooling, based on the time step of the discretization process, and thus obtain the welding microstructure change model under different welding conditions.

[0032] The Vickers hardness assessment module is used to obtain the current welding conditions, match them with the welding microstructure change model to obtain the volume fraction of the microstructure after cooling to room temperature, and perform weighted summation calculation on different microstructures to obtain the final Vickers hardness.

[0033] The present invention also provides an electronic device, including a memory and a processor, wherein the processor is used to execute a computer management program stored in the memory to implement the steps of the Vickers hardness evaluation method for marine steel welded joints.

[0034] The present invention also provides a computer-readable storage medium storing a computer management program thereon, which, when executed by a processor, implements the steps of a Vickers hardness evaluation method for marine steel welded joints.

[0035] Beneficial Effects: This invention provides a method and system for evaluating the Vickers hardness of welded joints of marine steel. The method includes: acquiring the thermal cycling curve of the welded joint of marine steel and discretizing the thermal cycling curve to obtain a temperature curve; inputting the relevant chemical composition of the marine steel and evaluating the critical temperature of the metal solid-state phase transformation; calculating the percentage of each microstructure component that can participate in the metal solid-state phase transformation; calculating the transient microstructure changes in different temperature ranges during the welding process from heating to cooling, based on the time step of the discretization process, to obtain the final microstructure component ratio; and performing a weighted summation of different microstructures to obtain the final Vickers hardness. This scheme can accurately calculate the Vickers hardness value of welded joints of marine steel without damaging the welded joint, is low-cost and convenient, and is suitable for widespread application. Attached Figure Description

[0036] Figure 1 A flowchart of a Vickers hardness evaluation method for marine steel welded joints provided by the present invention;

[0037] Figure 2 The temperature-time curve provided for this invention;

[0038] Figure 3The volume fraction change diagram of pearlite during the thermal cycling process provided by this invention;

[0039] Figure 4 The volume fraction variation diagram of ferrite during thermal cycling provided by this invention;

[0040] Figure 5 The volume fraction variation diagram of austenite during the thermal cycling process provided by this invention;

[0041] Figure 6 The volume fraction variation diagram of bainite during thermal cycling provided by this invention;

[0042] Figure 7 The volume fraction variation diagram of martensite during the thermal cycling process provided by this invention;

[0043] Figure 8 A schematic diagram of the hardware structure of a possible electronic device provided by the present invention;

[0044] Figure 9 This is a schematic diagram of the hardware structure of a possible computer-readable storage medium provided by the present invention. Detailed Implementation

[0045] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0046] like Figure 1 As shown, this embodiment of the invention provides a method for evaluating the Vickers hardness of welded joints of marine steel, including the following steps:

[0047] S1. The thermal cycling curve, i.e., the temperature change over time, is obtained through measurement using a platinum-rhodium alloy thermocouple or finite element calculation, and then discretized to obtain the temperature curve. Discretization of the thermal cycling curve: Set the time step (generally 0.01 seconds to 0.1 seconds), and discretize the continuous welding thermal cycling curve into several linear segments with minute temperature increases or decreases.

[0048] S2: Input the relevant chemical composition of marine steel to assess the critical temperatures of solid-state phase transformations in the metal. Specifically, based on the chemical composition of the marine steel, calculate the austenite transformation temperature, complete austenitization temperature, metal melting temperature during heating, and the phase transformation temperatures during cooling, such as the decomposition of austenite into pearlite, ferrite, bainite, and martensite.

[0049] S3 calculates the proportions of ferrite, pearlite, and retained austenite that can currently participate in the solid-state phase transformation of the metal. Based on the chemical composition of the marine steel, calculate the percentages of the initial microstructure (pearlite and ferrite) at room temperature. The microstructure of marine steel at room temperature generally includes pearlite and ferrite.

[0050] S4. Based on the time step of the discretization process in step S1, calculate the transient microstructure changes in different temperature ranges throughout the welding process from heating to cooling to obtain the final microstructure composition ratio. Then, perform a weighted summation of the different microstructures to obtain the final Vickers hardness. Specifically, this includes calculating the phase transformation temperatures between each microstructure during the heating and cooling processes, as well as the initial percentages of each microstructure component at room temperature.

[0051] S5 involves spot-welding a high-temperature platinum-rhodium alloy temperature sensor to the temperature measurement position to obtain Vickers hardness test values ​​in real time. The test values ​​are then compared and analyzed with the summed calculated values ​​to verify the calculated values. By using sensor detection to provide feedback and continuously correct the final calculated values, the calculation accuracy can be further improved, and the calculation model can be revised.

[0052] Specifically, the microstructure composition ratio within a specific temperature range can be obtained through specific calculations, and the Vickers hardness can be determined once the microstructure composition ratio is known.

[0053] The temperature change ranges are mainly divided into the following categories: when the temperature is below the austenite transformation temperature; when the temperature is between the austenite transformation temperature and the complete austenitizing temperature; when the temperature is above the complete austenitizing temperature; when the temperature drops and austenite transforms into ferrite; when the temperature drops and austenite transforms into pearlite; when the temperature drops and austenite transforms into bainite; when the temperature drops and austenite transforms into martensite; and when the temperature drops to room temperature.

[0054] When considering the welding heating portion of the thermal cycle curve, the microstructure transformation during the heating process is studied based on the previously discretized thermal cycle curve, i.e., the temperature curve. The average of the maximum and minimum values ​​of the temperature curve is taken as the loading value, and the loading time is the time step. The transient microstructure proportions in different temperature ranges are calculated. The specific microstructure changes during the welding heating process are as follows:

[0055] When the temperature is below the austenite transformation temperature (A1), no microstructure phase transformation occurs, and the microstructure of marine steel remains the initial pearlite and ferrite, with no change in percentage. When the temperature is above the austenite transformation temperature (A1) but below the complete austenitizing temperature (A3), some ferrite undergoes austenite transformation; by solving the phase transformation kinetic equation, the percentages of ferrite, pearlite, and austenite at this temperature can be obtained. When the temperature is above the complete austenitizing temperature (A3) but below the metal melting temperature (MP), austenite grains begin to grow. By setting an initial austenite grain size (10 μm) and calculating the increment of austenite grain size with increasing temperature, the specific austenite grain size can be obtained.

[0056] When considering the cooling portion of the thermal cycling curve, the average of the maximum and minimum values ​​of the discrete temperature curve is still used as the loading value for that temperature curve, and the loading time is the time step. The transient microstructure proportions in different temperature ranges are then calculated. The specific microstructure changes during the cooling process after welding are as follows:

[0057] When the temperature is below the complete austenitizing temperature (A3) but above the austenite transformation temperature (A1), the austenite undergoes ferrite decomposition, yielding partial ferrite and retained austenite. When the temperature is below the austenite transformation temperature (A1) but above the bainite transformation temperature (BT), the retained austenite undergoes pearlite decomposition again, yielding a mixture of ferrite, pearlite, and retained austenite. When the temperature is below the bainite transformation temperature (BT) but above the martensitic transformation temperature (MT), the retained austenite undergoes bainite decomposition again, yielding a mixture of ferrite, pearlite, bainite, and retained austenite. When the temperature is below the martensitic transformation temperature (MT), the retained austenite undergoes martensitic decomposition again, yielding a mixture of ferrite, pearlite, bainite, martensite, and retained austenite. The time required for the temperature to decrease from 800°C to 500°C during the cooling process is analyzed as the cooling rate, an important parameter for evaluating the effect of cooling rate on the hardness of the weld joint. The specific calculation formula is as follows:

[0058] When the maximum temperature exceeds 800 degrees Celsius:

[0059]

[0060] When the maximum temperature is greater than 500 degrees Celsius but less than 800 degrees Celsius:

[0061]

[0062] When the maximum temperature is less than 500 degrees Celsius, the cooling rate is 0.

[0063] In the preferred scheme, for the thermal cycling curve of multi-layer and multi-pass welding, the bainite and martensite that have been decomposed and transformed are irreversible; it is necessary to use the percentage content of the above-mentioned residual austenite, ferrite and pearlite as the new initial conditions of microstructure, and to perform calculation and analysis again on the transformation of austenite and grain growth during heating and the decomposition and transformation of austenite during cooling.

[0064] The specific details are as follows:

[0065] During the first welding thermal cycle: the content of microstructures participating in austenite transformation = ferrite content + pearlite content.

[0066] During subsequent welding thermal cycles: the microstructure content participating in austenite transformation = ferrite content + pearlite content + retained austenite content. Alternatively, the microstructure content participating in austenite transformation = 1 - bainite content - martensite content. The analysis process is the same for different thermal cycles, only the initial conditions differ, i.e., the content of microstructures participating in austenite transformation varies.

[0067] By calculating and analyzing the multi-layer, multi-pass welding thermal cycle of marine steel welded joints, the percentage of microstructure after each cooling and the corresponding cooling rate (i.e., the time required for the temperature to drop from 800 degrees Celsius to 500 degrees Celsius) were obtained.

[0068] By analyzing the chemical composition of marine steel and the cooling rate during the cooling process, the Vickers hardness of martensite, bainite, and the mixture of ferrite-pearlite-retained austenite were calculated respectively. Then, based on the percentage of microstructure generated in each thermal cycle, the final Vickers hardness was evaluated.

[0069] In a specific implementation scenario, let's first take a single-pass welding, i.e., one thermal cycle, as an example:

[0070] The highest temperature was 1230 degrees Celsius; the time to cool down to 800 degrees Celsius was 10.05 seconds, and the time to cool down to 500 degrees Celsius was 14.7 seconds; the specific temperature change curves over time are as follows. Figure 2 As shown.

[0071] Based on the chemical composition of the material, it can be calculated that:

[0072] The initial ferrite volume fraction was 97.2%, and the initial pearlite volume fraction was 2.8%; the A1 temperature was 706.5 degrees Celsius; the A3 temperature was 835.3 degrees Celsius; the bainite transformation temperature was 550.3 degrees Celsius; the martensite transformation temperature was 434.2 degrees Celsius; the gas constant was 1.9872; the grain growth constant was 7.0 × 10¹¹; the initial austenite grain size was 10 micrometers; and the martensite transformation constant was 0.011.

[0073] The entire thermal cycle can be divided into two stages: heating and cooling.

[0074] During the heating process, the transformation and growth of austenite can be solved using metallographic dynamics.

[0075]

[0076] The austenite volume fraction is 100%, and the austenite grain size is 69.05 micrometers. During the cooling process, the austenite decomposes, which can be solved using relevant governing equations. The solution process is existing technology and will not be elaborated further here. The change in pearlite volume fraction throughout the thermal cycle is as follows: Figure 3 As shown. The change in ferrite volume fraction throughout the entire thermal cycle is as follows. Figure 4 As shown. The change in the volume fraction of austenite throughout the entire thermal cycle is as follows. Figure 5 As shown. The change in the volume fraction of bainite throughout the entire thermal cycle is as follows. Figure 6 As shown. The change in martensite volume fraction throughout the entire thermal cycle is as follows. Figure 7 As shown.

[0077] The volume fraction of the microstructure after cooling to room temperature is as follows: 46.0% bainite; 52.0% martensite; and 2.0% retained austenite-pearlite-ferrite.

[0078] Cooling rate is:

[0079] The calculated hardness results for different microstructures are as follows: martensite hardness is 380.43; bainite hardness is 283.04; and the hardness of the retained austenite-pearlite-ferrite is 180.73. Therefore, the hardness at the location that underwent the thermal cycle is:

[0080] 331.65 = 380.43 * 52.0% + 283.04 * 46.0% + 180.73 * 2.0%.

[0081] For multi-layer, multi-pass welding thermal cycles, the volume fraction used in subsequent analyses is the volume fraction of austenite-pearlite-ferrite remaining from the previous cycle, and the cooling rate and microstructure hardness of the current cycle need to be determined. Taking three thermal cycles as an example, as follows:

[0082] Final hardness = First bainite and martensite hardness + Second bainite and martensite hardness + Third bainite and martensite hardness + Residual austenite-pearlite-ferrite hardness.

[0083] The specific hardness value is related to the volume fraction of microstructure generated during the current thermal cycle and the cooling rate.

[0084] This invention also provides a Vickers hardness evaluation system for marine steel welded joints. The system is used to implement the Vickers hardness evaluation method for marine steel welded joints as described above, including:

[0085] The thermal cycling curve discretization module is used to obtain the thermal cycling curve of the welded joint of marine steel and to discretize the thermal cycling curve to obtain the temperature curve.

[0086] The critical temperature assessment module is used to input the relevant chemical composition of marine steel and assess the critical temperature of the metal solid-state phase transformation.

[0087] The current microstructure composition calculation module is used to calculate the percentage of each microstructure component that can participate in the solid-state phase transition of metals.

[0088] The Vickers hardness assessment module is used to calculate the transient microstructure changes in different temperature ranges during the welding process, from heating to cooling, based on the time step of the discretization process, in order to obtain the final microstructure composition ratio. The final Vickers hardness is obtained by weighted summation of different microstructures.

[0089] Please see Figure 8 This is a schematic diagram illustrating an embodiment of the electronic device provided in this invention. For example... Figure 8 As shown, an embodiment of the present invention provides an electronic device, including a memory 1310, a processor 1320, and a computer program 1311 stored in the memory 1310 and executable on the processor 1320. When the processor 1320 executes the computer program 1311, it performs the following steps: S1, obtaining the thermal cycle curve of the welded joint of marine steel, and discretizing the thermal cycle curve to obtain a temperature curve.

[0090] S2, input the relevant chemical composition of marine steel, and evaluate the critical temperature of the solid-state phase transformation of the metal;

[0091] S3, calculate the percentage of each microstructure component that can currently participate in the solid-state phase transition of the metal;

[0092] S4. Based on the time step of the discretization process in step S1, calculate the transient microstructure changes in different temperature ranges during the welding process from heating to cooling, so as to obtain the final microstructure composition ratio. The final Vickers hardness is obtained by weighted summation of different microstructures.

[0093] Please see Figure 9 This is a schematic diagram illustrating an embodiment of a computer-readable storage medium provided by the present invention. (See diagram below.) Figure 9As shown, this embodiment provides a computer-readable storage medium 1400, on which a computer program 1411 is stored. When the computer program 1411 is executed by a processor, it performs the following steps: S1, obtaining the thermal cycle curve of the welded joint of marine steel, and discretizing the thermal cycle curve to obtain a temperature curve.

[0094] S2, input the relevant chemical composition of marine steel, and evaluate the critical temperature of the solid-state phase transformation of the metal;

[0095] S3, calculate the percentage of each microstructure component that can currently participate in the solid-state phase transition of the metal;

[0096] S4. Based on the time step of the discretization process in step S1, calculate the transient microstructure changes in different temperature ranges during the welding process from heating to cooling, so as to obtain the final microstructure composition ratio. The final Vickers hardness is obtained by weighted summation of different microstructures.

[0097] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0098] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0099] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0100] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0101] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0102] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0103] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for evaluating the Vickers hardness of welded joints for marine steel, characterized in that, Includes the following steps: S1. Obtain the thermal cycle curve of the welded joint of marine steel, and discretize the thermal cycle curve to obtain the temperature curve. S2, input the relevant chemical composition of marine steel, and evaluate the critical temperature of the solid-state phase transformation of the metal; S3, calculate the percentage of each microstructure component currently participating in the metal solid-state phase transformation; specifically, calculate the proportion of ferrite, pearlite, and retained austenite that can currently participate in the metal solid-state phase transformation. S4. Based on the time step of the discretization process in step S1, calculate the transient microstructure changes in different temperature ranges during the welding process from heating to cooling, so as to obtain the final microstructure composition ratio. The final Vickers hardness is obtained by weighted summation of different microstructures. Specifically, the average of the maximum and minimum values ​​of the temperature curve is taken as the loading value of the temperature curve, and the loading time is the time step. The transient microstructure ratio in different temperature change ranges is calculated. The specific temperature variation ranges include: when the temperature is below the austenite transformation temperature; when the temperature is between the austenite transformation temperature and the complete austenitizing temperature; when the temperature is above the complete austenitizing temperature; when the temperature drops and austenite transforms into ferrite; when the temperature drops and austenite transforms into pearlite; when the temperature drops and austenite transforms into bainite; when the temperature drops and austenite transforms into martensite; and when the temperature drops to room temperature. S5. For the thermal cycling curve of multi-layer and multi-pass welding, the decomposed and transformed bainite and martensite are irreversible. It is necessary to use the contents of the above-mentioned residual austenite, ferrite and pearlite as the new initial conditions of microstructure, and to perform calculation and analysis again on the transformation of austenite and grain growth during heating and the decomposition and transformation of austenite during cooling. Specifically, during the first welding thermal cycle: the content of microstructures participating in austenite transformation = ferrite content + pearlite content; During subsequent welding thermal cycles: the content of microstructures participating in austenite transformation = 1 - bainite content - martensite content.

2. The Vickers hardness evaluation method for marine steel welded joints according to claim 1, characterized in that, S1 specifically includes: By setting a time step, the continuous welding thermal cycle curve is discretized into several straight line segments indicating either an increase or decrease in temperature.

3. The Vickers hardness evaluation method for marine steel welded joints according to claim 1, characterized in that, The microstructure includes austenite, fully austenite, pearlite, ferrite, bainite, and martensite.

4. The Vickers hardness evaluation method for marine steel welded joints according to claim 1, characterized in that, S2 specifically includes: calculating the austenite transformation temperature, complete austenitization temperature, metal melting temperature during heating, and phase transformation temperatures of austenite decomposing into pearlite, ferrite, bainite and martensite during cooling, based on the chemical composition of marine steel.

5. The Vickers hardness evaluation method for marine steel welded joints according to claim 1, characterized in that, The process after S4 further includes: spot welding a high-temperature platinum-rhodium alloy temperature sensor to the temperature measurement position to obtain the Vickers hardness test value in real time, and comparing and analyzing the test value with the summed calculated value to verify the calculated value.

6. A Vickers hardness evaluation system for marine steel welded joints, characterized in that, The system is used to implement the Vickers hardness evaluation method for marine steel welded joints as described in any one of claims 1-5, including: The thermal cycling curve discretization module is used to obtain the thermal cycling curve of the welded joint of marine steel and to discretize the thermal cycling curve to obtain the temperature curve. The critical temperature assessment module is used to input the relevant chemical composition of marine steel and assess the critical temperature of the metal solid-state phase transformation. The current microstructure composition calculation module is used to calculate the percentage of each microstructure component currently participating in the metal solid-state phase transition; The Vickers hardness assessment module is used to calculate the transient microstructure changes in different temperature ranges during the welding process, from heating to cooling, based on the time step of the discretization process, in order to obtain the final microstructure composition ratio. The final Vickers hardness is obtained by weighted summation of different microstructures.

7. An electronic device, characterized in that, It includes a memory and a processor, wherein the processor is used to execute computer management programs stored in the memory to implement the steps of the Vickers hardness evaluation method for marine steel welded joints as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, It stores a computer management program, which, when executed by a processor, implements the steps of the Vickers hardness evaluation method for marine steel welded joints as described in any one of claims 1-5.

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