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...

AI Technical Summary

Problems solved by technology

The main reason is that in the thermal cycle of the welding coarse-grained zone, when the grain grows, it will be pinned by the second phase particles in the microalloyed steel, and the welding thermal cycle itself will also affect the thermal stability of the second phase , as the thermal cycle time and temperature change, the pinning effect of the second phase particles will also change, and the welding thermal cycle is a typical non-thermodynamic equilibrium thermal process. Therefore, the rationality of the results obtained by using the grain growth kinetic formula to calculate the grain size of the microalloy steel welding coarse grain zone depends on whether the micro Precise description of thermal stability of second phase particles in alloy steel

Although the basic formulation of the grain growth kinetics formula is publicly available, different researchers have different approaches on how to approximate the pinning effect of the second relative grain growth in microalloyed steels during the welding heat process , so the reliability of the calculated results will be different

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