A method, system, medium, and device for determining a preheat temperature for welding a structural steel

Abstract

The application discloses a high-precision coupling iteration structural steel welding preheating temperature determination method and system, a computer readable storage medium and an electronic device. The method only collects four types of core parameters, including core chemical composition of steel, equivalent plate thickness, diffusion hydrogen content of deposited metal and joint restraint grade quantization coefficient; a high-order nonlinear coupling crack sensitive index is constructed, a power function, a logarithm and a root formula nested model are used to solve an initial benchmark preheating temperature; a dynamic restraint correction model related to temperature is introduced to obtain a candidate preheating temperature; a heat-hydrogen coupling dynamics model is established to solve a hydrogen diffusion coefficient and a hydrogen escape critical time length; a double-layer nested iteration optimization algorithm is used, a hardening cooling rate, hydrogen diffusion aging and a critical hardness of a heat affected zone are taken as triple constraints, and the lowest safe preheating temperature and the optimal preheating interval are obtained through iteration convergence.

Description

Technical Field

[0001] This invention relates to the field of welding heat, and in particular to a method, system, medium, and equipment for determining the preheating temperature for welding structural steel. Background Technology

[0002] Cold cracking in structural steel welding is a core problem restricting the welding quality of high-strength steel thick plates. Preheating before welding is a core process to inhibit the formation of hardened structures, accelerate the release of diffused hydrogen, and slow down the release of welding restraint stress.

[0003] Currently, there are three main methods for determining welding preheating temperature in engineering: standard lookup table method, traditional carbon equivalent empirical formula method, and welding simulation test method.

[0004] The standard lookup table method provides a fixed preheating range based on the steel grade and plate thickness. It can only use conservative thresholds and cannot distinguish between fluctuations in the composition of steel of the same grade and differences in joint restraint. It is easy to cause overheating, which leads to increased energy consumption and grain coarsening, or underheating, which leads to cold cracks.

[0005] Traditional carbon equivalent and Pcm crack sensitivity index are both linear superposition empirical formulas that simply superimpose alloying elements and ignore the synergistic hardening effect between alloying elements. Constraint correction and environmental correction mostly use fixed constants, which cannot characterize the dynamic coupling relationship between temperature, stress and hydrogen diffusion.

[0006] Existing patents and literature generally employ a single open-loop forward calculation mode for calculating preheating temperature, without an iterative optimization mechanism; hydrogen diffusion parameters are generally used only as static input conditions, without establishing a two-way coupling relationship between preheating temperature and hydrogen escape kinetics.

[0007] At the same time, existing technologies suffer from path dependence: to improve calculation accuracy, a large number of input parameters must be added, which makes it difficult to collect on-site parameters and makes it difficult to use them directly for rapid process evaluation in engineering.

[0008] A method, system, medium, and equipment for determining the preheating temperature of structural steel welding are needed to solve the above problems. Summary of the Invention

[0009] This invention addresses the shortcomings of existing technologies in preheating temperature calculation models, such as linearization, static correction coefficients, open-loop calculations without iteration, and complex parameters that are difficult to implement. This invention provides a method for determining the preheating temperature of structural steel welding. By abandoning the traditional linear carbon equivalent system, it constructs a multi-field nonlinear coupled mathematical model of thermal cycling, hydrogen diffusion, and constraint stress; it simplifies the dimensions of input parameters and eliminates low-sensitivity secondary parameters; and it relies on a double-layer nested iterative algorithm to accurately solve the critical preheating temperature range. This method balances theoretical accuracy with practical engineering applications, thus solving the problems of existing technologies.

[0010] This invention provides a method for determining the preheating temperature for welding structural steel, comprising the following steps: S1. Collect core input parameters, including: core chemical composition of steel, equivalent plate thickness t, standard diffusible hydrogen content of deposited metal Hd, and joint restraint level quantification coefficient KR0; core chemical composition of steel includes C, Mn, Cr, Mo, and V elements; S2. Based on the core parameters collected, a nonlinear coupled crack sensitivity index Smc is constructed. The value of the nonlinear coupled crack sensitivity index is calculated by using a preset element interaction coupling formula and a plate thickness index attenuation correction formula. S3. Based on the nonlinear coupled crack sensitivity index, diffusible hydrogen content, and equivalent plate thickness, a power function and logarithmic nested composite model is used to solve for the initial reference preheating temperature Tpre0 without working condition correction. S4. Construct a temperature-related dynamic restraint correction model. Based on the initial reference preheating temperature and the restraint level quantification coefficient KR0, calculate the dynamic restraint correction coefficient KR and correct the initial reference preheating temperature to obtain the candidate preheating temperature Tpre1. S5. Establish a thermal-hydrogen coupling kinetic model, construct a temperature-dependent hydrogen diffusion coefficient calculation formula based on candidate preheating temperatures, and solve for the hydrogen diffusion coefficient D(T) and the critical time tH for complete hydrogen escape. S6. Using a double-layer nested iterative closed-loop optimization algorithm, with hardening cooling rate, hydrogen diffusion aging, and critical hardness of heat-affected zone as triple nonlinear constraints, the inner layer hydrogen diffusion parameters and outer layer preheating temperature are iteratively corrected. After the iteration converges, the lowest safe preheating temperature Tmin that satisfies all constraints is obtained, and the optimal preheating temperature range [Tmin, Tmax] is output in combination with the grain coarsening critical threshold. S7 outputs the minimum safe preheating temperature, optimal preheating range, and welding crack risk level parameters.

[0011] The method for determining the preheating temperature for welding structural steel described in this invention is, as a preferred embodiment, The formula for calculating the higher-order nonlinear coupled crack sensitivity index in step S2 is as follows: Wherein, C, Mn, Cr, Mo, and V correspond to the mass fractions of each core chemical component of the steel, and t is the equivalent plate thickness.

[0012] The method for determining the preheating temperature for welding structural steel described in this invention is, as a preferred embodiment, The formula for calculating the initial reference preheating temperature Tpre0 in step S3 is as follows: Where Hd is the diffusible hydrogen content of the weld metal under standard conditions.

[0013] The method for determining the preheating temperature for welding structural steel described in this invention is, as a preferred embodiment, The formula for calculating the dynamic restraint correction coefficient KR in step S4 is as follows: Among them, KR0 is the basic restraint level quantification value, and its value range is... ; KR is a nonlinear correction coefficient that dynamically and adaptively changes with the preheating temperature. The corrected candidate preheating temperature Tpre1 satisfies .

[0014] The method for determining the preheating temperature for welding structural steel described in this invention is, as a preferred embodiment, The core calculation formulas for the thermal-hydrogen coupling kinetic model in step S5 include: ; ; Where D0 is the hydrogen diffusion reference coefficient, Q is the hydrogen diffusion activation energy, R is the universal gas constant, and Hcrit is the safe critical threshold for hydrogen content. D(T) is the temperature-coupled high-order hydrogen diffusion coefficient. This is the critical time for hydrogen to completely escape.

[0015] The method for determining the preheating temperature for welding structural steel described in this invention is, as a preferred embodiment, The double-nested iterative closed-loop optimization algorithm in step S6 includes inner iteration and outer iteration: The inner iteration specifically involves iteratively solving the steady-state hydrogen diffusion coefficient D(T) and critical diffusion time tH with a convergence accuracy of 0.1℃, thereby achieving steady-state convergence of the hydrogen diffusion parameters. The outer layer iteration specifically uses a cooling rate constraint formula based on the coupled hydrogen diffusion deviation to determine the threshold. The constraint formula is as follows: ; Wherein, CRsim is the simulated cooling rate, CRcrit is the critical safe cooling rate, and tstd is the standard hydrogen diffusion time; The candidate preheating temperatures are iteratively corrected until the heat-affected zone hardening constraint, hydrogen diffusion aging constraint, and hardness threshold constraint are simultaneously satisfied, and the optimal preheating temperature range is obtained by convergence.

[0016] Systems using the above methods include: The simplified parameter input module is used to receive four types of core input parameters: core chemical composition of steel, equivalent plate thickness, diffusible hydrogen content, and restraint grade quantification coefficient. The advanced metallurgical index calculation module is used to run nonlinear coupling formulas and calculate the nonlinear coupling crack sensitivity index Smc. The dynamic restraint correction module is used to calculate the dynamic restraint correction coefficient based on the temperature coupling model and complete the initial correction of the preheating temperature. The hydrogen thermal coupling kinetics calculation module is used to solve for the temperature-dependent hydrogen diffusion coefficient and the critical hydrogen escape time. The double-nested iterative optimization module is used to perform inner and outer double-layer iterations, complete multi-constraint closed-loop convergence calculations, and solve for the optimal preheating temperature range. The results output and storage module is used to output preheating temperature parameters and crack risk levels, and to store data from the entire iterative calculation process.

[0017] The present invention further discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements all the steps of the above-described method for determining the preheating temperature for welding structural steel.

[0018] The present invention also discloses a computer device, characterized in that it includes a processor and a memory; The memory stores computer programs that can be executed by the processor; When the processor executes the computer program, it implements the above-mentioned method for determining the preheating temperature for welding structural steel.

[0019] The beneficial effects of this invention are as follows: 1) This invention uses a nonlinear crack sensitivity index and introduces element power terms, element interaction coupling terms, and plate thickness index decay terms, which can accurately characterize the nonlinear metallurgical law of synergistic hardening of alloy elements. 2) A multi-layer nested composite function is used to construct the basic model of preheating temperature, which is combined with a dynamic constraint correction model that adapts to temperature, unlike the industry-standard fixed correction coefficient scheme. 3) Construct a set of thermal-hydrogen bidirectional coupled kinetic equations, solve the preheating temperature and hydrogen diffusion rate simultaneously, and realize the dynamic quantification of the hydrogen escape process; 4) The double-layer nested iterative architecture, with the inner layer converging hydrogen diffusion parameters and the outer layer iteratively optimizing the preheating temperature, relies on triple constraint closed-loop optimization, which is more accurate than a single forward open-loop calculation; 5) Innovatively adopting the approach of "simplified input parameters + high-order mathematical model", discarding a large number of secondary working condition parameters, reducing the threshold for on-site data collection, and improving the engineering implementation capability of the solution while ensuring calculation accuracy; 6) Output quantitative preheating range to balance the safety of welding cold crack prevention and heating energy consumption, and avoid blindly conservative preheating. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a method for determining the preheating temperature for welding structural steel. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] Example 1: As Figure 1 As shown, a method for determining the preheating temperature for welding structural steel includes the following steps: S1. Collect core input parameters, including: core chemical composition of steel, equivalent plate thickness t, standard diffusible hydrogen content of deposited metal Hd, and joint restraint level quantification coefficient KR0; core chemical composition of steel includes C, Mn, Cr, Mo, and V elements; S2. Based on the core parameters collected, a nonlinear coupled crack sensitivity index Smc is constructed. The value of the nonlinear coupled crack sensitivity index is calculated by using a preset element interaction coupling formula and a plate thickness index attenuation correction formula. S3. Based on the nonlinear coupled crack sensitivity index, diffusible hydrogen content, and equivalent plate thickness, a power function and logarithmic nested composite model is used to solve for the initial reference preheating temperature Tpre0 without working condition correction. S4. Construct a temperature-related dynamic restraint correction model. Based on the initial reference preheating temperature and the restraint level quantification coefficient KR0, calculate the dynamic restraint correction coefficient KR and correct the initial reference preheating temperature to obtain the candidate preheating temperature Tpre1. S5. Establish a thermal-hydrogen coupling kinetic model, construct a temperature-dependent hydrogen diffusion coefficient calculation formula based on candidate preheating temperatures, and solve for the hydrogen diffusion coefficient D(T) and the critical time tH for complete hydrogen escape. S6. Using a double-layer nested iterative closed-loop optimization algorithm, with hardening cooling rate, hydrogen diffusion aging, and critical hardness of heat-affected zone as triple nonlinear constraints, the inner layer hydrogen diffusion parameters and outer layer preheating temperature are iteratively corrected. After the iteration converges, the lowest safe preheating temperature Tmin that satisfies all constraints is obtained, and the optimal preheating temperature range [Tmin, Tmax] is output in combination with the grain coarsening critical threshold. S7 outputs the minimum safe preheating temperature, optimal preheating range, and welding crack risk level parameters.

[0023] The formula for calculating the higher-order nonlinear coupled crack sensitivity index in step S2 is as follows: Where C, Mn, Cr, Mo, and V correspond to the mass fractions of the core chemical components of the steel, and t is the equivalent plate thickness.

[0024] The formula for calculating the initial reference preheating temperature Tpre0 in step S3 is as follows: Hd represents the diffusible hydrogen content of the weld metal under standard conditions.

[0025] The formula for calculating the dynamic restraint correction coefficient KR in step S4 is as follows: Wherein, KR0 is the quantified value of the basic restraint level, and its value range is... ; KR is a nonlinear correction coefficient that dynamically and adaptively changes with the preheating temperature. The corrected candidate preheating temperature Tpre1 satisfies .

[0026] The core calculation formulas for the thermal-hydrogen coupling kinetic model in step S5 include: ; ; Where D0 is the hydrogen diffusion reference coefficient, Q is the hydrogen diffusion activation energy, R is the universal gas constant, and Hcrit is the safe critical threshold for hydrogen content. D(T) is the temperature-coupled high-order hydrogen diffusion coefficient. This is the critical time for hydrogen to completely escape.

[0027] The double-nested iterative closed-loop optimization algorithm in step S6 includes inner iteration and outer iteration: The inner iteration specifically involves iteratively solving the steady-state hydrogen diffusion coefficient D(T) and critical diffusion time tH with a convergence accuracy of 0.1℃, thereby achieving steady-state convergence of the hydrogen diffusion parameters. The outer layer iteration specifically uses a cooling rate constraint formula based on the coupled hydrogen diffusion deviation to determine the threshold. The constraint formula is as follows: ; Wherein, CRsim is the simulated cooling rate, CRcrit is the critical safe cooling rate, and tstd is the standard hydrogen diffusion time; The candidate preheating temperatures are iteratively corrected until the heat-affected zone hardening constraint, hydrogen diffusion aging constraint, and hardness threshold constraint are simultaneously satisfied, and the optimal preheating temperature range is obtained by convergence.

[0028] Systems using the above methods include: The simplified parameter input module is used to receive four types of core input parameters: core chemical composition of steel, equivalent plate thickness, diffusible hydrogen content, and restraint grade quantification coefficient. The advanced metallurgical index calculation module is used to run nonlinear coupling formulas and calculate the nonlinear coupling crack sensitivity index Smc. The dynamic restraint correction module is used to calculate the dynamic restraint correction coefficient based on the temperature coupling model and complete the initial correction of the preheating temperature. The hydrogen thermal coupling kinetics calculation module is used to solve for the temperature-dependent hydrogen diffusion coefficient and the critical hydrogen escape time. The double-nested iterative optimization module is used to perform inner and outer double-layer iterations, complete multi-constraint closed-loop convergence calculations, and solve for the optimal preheating temperature range. The results output and storage module is used to output preheating temperature parameters and crack risk levels, and to store data from the entire iterative calculation process.

[0029] A computer-readable storage medium storing a computer program that, when executed by a processor, implements all the steps of the above-described method for determining the preheating temperature for structural steel welding.

[0030] A computer device, characterized in that it includes a processor and a memory; The memory stores computer programs that can be executed by the processor; When the processor executes the computer program, it implements the above-mentioned method for determining the preheating temperature for welding structural steel.

[0031] According to the method described in the embodiment, this embodiment is for bridge-grade Q355NL steel with an equivalent plate thickness of 28mm. Chemical composition: C=0.14%, Mn=1.32%, Cr=0.10%, Mo=0.04%, V=0.05%; Diffusible hydrogen (Hd) = 2.1 mL / 100 g; Free-connecting joint, KR0=0.9; Based on the iterative calculations of the algorithm of this invention, the minimum safe preheating temperature Tmin is 76℃, and the recommended range is 76~150℃, which meets the requirements for crack prevention during welding in low-temperature outdoor environments.

[0032] Example 2: Unlike Example 1, the base material to be welded in this example is Q460D high-strength structural steel; Chemical composition: C=0.16%, Mn=1.45%, Cr=0.22%, Mo=0.11%, V=0.07%; equivalent plate thickness t=40mm; Low-hydrogen gas shielded welding wire is used, with diffusible hydrogen Hd of 3.2 mL / 100 g in the deposited metal; the joint is a rigid box-type column joint with a restraint level quantification coefficient KR0=1.3; After iterative convergence, the minimum safe preheating temperature Tmin = 108℃ was obtained; combined with the critical temperature for grain coarsening, the preheating range was determined to be 108℃~160℃.

[0033] The minimum preheating temperature of 150℃ was obtained by looking up the national standard table. As can be seen from the comparison, this embodiment effectively reduces the lower limit of preheating and reduces gas consumption while meeting all anti-crack constraints, and there is no risk of cold cracking.

[0034] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for determining the preheating temperature for welding structural steel, characterized in that, Includes the following steps: S1. Collect core input parameters, which include: core chemical composition of steel, equivalent plate thickness t, standard diffusible hydrogen content Hd of deposited metal, and quantification coefficient KR0 of joint restraint level; the core chemical composition of steel includes C, Mn, Cr, Mo, and V elements; S2. Based on the core parameters collected, a nonlinear coupled crack sensitivity index Smc is constructed. The value of the nonlinear coupled crack sensitivity index is calculated by using a preset element interaction coupling formula and a plate thickness index attenuation correction formula. S3. Based on the nonlinear coupled crack sensitivity index, diffusible hydrogen content, and equivalent plate thickness, the initial reference preheating temperature Tpre0 without working condition correction is obtained by using a power function and logarithmic nested composite model. S4. Construct a temperature-related dynamic restraint correction model. Based on the initial reference preheating temperature and the restraint level quantification coefficient KR0, calculate the dynamic restraint correction coefficient KR and correct the initial reference preheating temperature to obtain the candidate preheating temperature Tpre1. S5. Establish a thermal-hydrogen coupling kinetic model, construct a temperature-dependent hydrogen diffusion coefficient calculation formula based on candidate preheating temperatures, and solve for the hydrogen diffusion coefficient D(T) and the critical time tH for complete hydrogen escape. S6. Using a double-layer nested iterative closed-loop optimization algorithm, with hardening cooling rate, hydrogen diffusion aging, and critical hardness of heat-affected zone as triple nonlinear constraints, the inner layer hydrogen diffusion parameters and outer layer preheating temperature are iteratively corrected. After the iteration converges, the lowest safe preheating temperature Tmin that satisfies all constraints is obtained, and the optimal preheating temperature range [Tmin, Tmax] is output in combination with the grain coarsening critical threshold. S7 outputs the minimum safe preheating temperature, optimal preheating range, and welding crack risk level parameters.

2. The method for determining the preheating temperature for welding structural steel according to claim 1, characterized in that: The formula for calculating the higher-order nonlinear coupled crack sensitivity index in step S2 is as follows: Where C, Mn, Cr, Mo, and V correspond to the mass fractions of the core chemical components of the steel, and t is the equivalent plate thickness.

3. The method for determining the preheating temperature for welding structural steel according to claim 2, characterized in that: The formula for calculating the initial reference preheating temperature Tpre0 in step S3 is as follows: Where Hd is the diffusible hydrogen content of the weld metal under standard conditions.

4. The method for determining the preheating temperature for welding structural steel according to claim 3, characterized in that: The formula for calculating the dynamic restraint correction coefficient KR in step S4 is as follows: Wherein, KR0 is the quantified value of the basic restraint level, and its value range is... ; KR is a nonlinear correction coefficient that dynamically and adaptively changes with the preheating temperature. The corrected candidate preheating temperature Tpre1 satisfies .

5. The method for determining the preheating temperature for structural steel welding according to claim 4, characterized in that: The core calculation formulas of the thermal-hydrogen coupling kinetic model described in step S5 include: ; ; Where D0 is the hydrogen diffusion reference coefficient, Q is the hydrogen diffusion activation energy, R is the universal gas constant, and Hcrit is the safe critical threshold for hydrogen content. D(T) is the temperature-coupled high-order hydrogen diffusion coefficient. This is the critical time for hydrogen to completely escape.

6. The method for determining the preheating temperature for welding structural steel according to claim 1, characterized in that: The double-nested iterative closed-loop optimization algorithm described in step S6 includes inner iteration and outer iteration: The inner iteration specifically refers to... To improve convergence accuracy, the steady-state hydrogen diffusion coefficient D(T) and critical diffusion time tH are solved iteratively to achieve steady-state convergence of the hydrogen diffusion parameters. The outer layer iteration specifically uses a cooling rate constraint formula for coupled hydrogen diffusion deviation to determine the threshold. The constraint formula is as follows: ; Wherein, CRsim is the simulated cooling rate, CRcrit is the critical safe cooling rate, and tstd is the standard hydrogen diffusion time; The candidate preheating temperatures are iteratively corrected until the heat-affected zone hardening constraint, hydrogen diffusion aging constraint, and hardness threshold constraint are simultaneously satisfied, and the optimal preheating temperature range is obtained by convergence.

7. A system for determining the preheating temperature for structural steel welding, characterized in that, For performing the method according to any one of claims 1-6, comprising: The simplified parameter input module is used to receive four types of core input parameters: core chemical composition of steel, equivalent plate thickness, diffusible hydrogen content, and restraint grade quantification coefficient. The advanced metallurgical index calculation module is used to run nonlinear coupling formulas and calculate the nonlinear coupling crack sensitivity index. The dynamic restraint correction module is used to calculate the dynamic restraint correction coefficient based on the temperature coupling model and complete the initial correction of the preheating temperature. The hydrogen thermal coupling kinetics calculation module is used to solve for the temperature-dependent hydrogen diffusion coefficient and the critical hydrogen escape time. The double-nested iterative optimization module is used to perform inner and outer double-layer iterations, complete multi-constraint closed-loop convergence calculations, and solve for the optimal preheating temperature range. The results output and storage module is used to output preheating temperature parameters and crack risk levels, and to store data from the entire iterative calculation process.

8. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements all the steps of the method for determining the preheating temperature for welding structural steel according to any one of claims 1-6.

9. A computer device, characterized in that, Including processor and memory; The memory stores computer programs that can be executed by the processor; When the processor executes the computer program, it implements the method for determining the preheating temperature for welding structural steel as described in any one of claims 1-6.

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