A Method for Predicting the Grain Size of Welding Coarse Grain Zone of Microalloyed Steel

Abstract

The invention relates to a method for predicting the grain size of the welded coarse-grained zone of micro-alloy steel, which belongs to the field of physical measurement. Firstly, the information of the prior austenite grain size in the microalloyed steel welded coarse-grained zone under three or more different heat inputs is obtained through thermal simulation; secondly, M in the grain growth kinetic formula is set 0 and P Z is an unknown constant, other parameters are known parameters and the corresponding reasonable values ​​are obtained by consulting the literature, and then the values ​​of the prior austenite grain size in the coarse-grained region under three different heat inputs are compared with the grain growth kinetics formula Fitting (by numerical integration and using the finite difference method), the best fit results in M 0 and P Z The numerical value; Finally, through this grain growth kinetics formula and the fitted M 0 and P Z The grain size of the microalloyed steel welded coarse-grained zone is calculated under different welding heat input, and the grain size of the microalloyed steel welded coarse-grained zone is predicted. The invention simplifies the fitting and calculation process, and provides an important basis for controlling the grain size of the microalloy steel welded coarse grain area.

Description

Technical field:

[0001] The invention belongs to the field of physical measurement, and in particular relates to a method for predicting the grain size of the microalloy steel welded coarse grain zone. Background technique

[0002] The welded coarse-grained zone is usually one of the weakest regions of the welded joint, and its mechanical properties represent the mechanical properties of the welded joint to a large extent. Therefore, evaluating the mechanical properties of the welded coarse-grained zone can be used to evaluate the The mechanical performance characteristics of welded joints provide an important reference. The microstructure of iron and steel materials is usually one of the most important factors determining their mechanical properties, and the grain size, as an important characterization parameter, has always been considered to be one of the most important indicators for evaluating whether the mechanical properties of the welded coarse-grained zone have deter...

Examples

Embodiment

[0014] Thermal simulation of the thermal cycle of a microalloyed steel in the welding coarse grain zone, the heating rate is 200K / s, the peak temperature is 1643K, the peak temperature residence time is 1s, and the cooling process adopts Rykalin 3D thermal model λ=0.38J / (cm·s·K), T P=1643K, E is the welding heat input, T' is the temperature coordinate, τ is the time coordinate), the welding heat input parameters in the thermal model are 14, 20 and 36kJ / cm respectively. Through metallographic grinding, the average grain size of the welded coarse-grained region under three heat inputs is about 77±4, 83±4, and 88±3 μm, respectively, according to the statistics of the intercept method. Grain Growth Formula Will M 0 and P Z It is an unknown constant, and the numerical scores of other parameters are taken as n=2, R=8.3J / (mol·K), Q a =400kJ / mol, γ=0.5J / m 2 . The time t of the integral interval is the duration from when the temperature exceeds 1100K in the heating process to...

Technical field:

[0001] The invention belongs to the field of physical measurement, and in particular relates to a method for predicting the grain size of the microalloy steel welded coarse grain zone. Background technique

[0002] The welded coarse-grained zone is usually one of the weakest regions of the welded joint, and its mechanical properties represent the mechanical properties of the welded joint to a large extent. Therefore, evaluating the mechanical properties of the welded coarse-grained zone can be used to evaluate the The mechanical performance characteristics of welded joints provide an important reference. The microstructure of iron and steel materials is usually one of the most important factors determining their mechanical properties, and the grain size, as an important characterization parameter, has always been considered to be one of the most important indicators for evaluating whether the mechanical properties of the welded coarse-grained zone have deter...

Examples

Embodiment

[0014] Thermal simulation of the thermal cycle of a microalloyed steel in the welding coarse grain zone, the heating rate is 200K / s, the peak temperature is 1643K, the peak temperature residence time is 1s, and the cooling process adopts Rykalin 3D thermal model λ=0.38J / (cm·s·K), T P=1643K, E is the welding heat input, T' is the temperature coordinate, τ is the time coordinate), the welding heat input parameters in the thermal model are 14, 20 and 36kJ / cm respectively. Through metallographic grinding, the average grain size of the welded coarse-grained region under three heat inputs is about 77±4, 83±4, and 88±3 μm, respectively, according to the statistics of the intercept method. Grain Growth Formula Will M 0 and P Z It is an unknown constant, and the numerical scores of other parameters are taken as n=2, R=8.3J / (mol·K), Q a =400kJ / mol, γ=0.5J / m 2 . The time t of the integral interval is the duration from when the temperature exceeds 1100K in the heating process to...

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