Method for calibrating high-instantaneity solid-state phase change JMAK equation parameters based on thermal expansion

Abstract

The invention discloses a method for calibrating high-instantaneity solid-state phase change JMAK equation parameters based on thermal expansion, and belongs to the field of metallurgy. The implementation method comprises the following steps: based on a JMAK equation in a differential form and a lever method, accurately judging an inflection point of length change of a sample in a thermal expansion experiment by carrying out forward and backward difference on thermal expansion experiment data, and calculating an austenite volume fraction by establishing a lever; the parameters n, C and delta H in the JMAK equation are measured and calculated through fitting of the obtained austenite volume fraction and corresponding temperature data, that is, the parameters of the high-instantaneity solid-state phase change JMAK equation are fitted, measured and calibrated based on a thermal expansion experiment, and the prediction precision of the high-instantaneity solid-state phase change JMAK equation on austenite phase change of metal in the high-instantaneity heating process is improved. The method can predict the elastic modulus, Poisson's ratio and tensile strength of the material in the high instantaneous heating process, and prolongs the service life of the material. The method has the advantages of high measurement and calculation, calibration and prediction precision and high efficiency.

Description

technical field [0001] The invention relates to a method for calibrating parameters of a JMAK equation of a highly transient solid state phase transition based on thermal expansion, and belongs to the field of metallurgy. Background technique [0002] In recent years, with the development of aerospace technology, the research demand for metal phase transition processes with high instantaneous heating and cooling processes has been increasing. The isothermal phase transition process is different, does not conform to the classical nucleation theory, and cannot be described by the commonly used TTT curve or CCT curve, so it is difficult to study this process. So far, there has not been any mathematical model that can completely and accurately describe the volume fraction of the metal phase transition after the metal as a whole is heated and cooled with high transients. Therefore, it is a way to improve the existing classical phase transition theory. better solution. Due to th...

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Problems solved by technology

[0006] Aiming at the problem that the existing metallurgical methods cannot accurately describe the volume fraction of the metal phase transition in the high instantaneous heating and cooling process, the method disclosed in the present invention is based on the method of calibrating the JMAK equation parameters of the high instantaneous solid phase transition based on the thermal expansion, based on the differential form of the JMAK equation and Leverage method, through the forward and backward difference of the thermal expansion experiment data, accurately judge the inflection point of the sample length change in the thermal expansion experiment, obtain the austenite volume fraction by establishing a lever, and obtain the austenite volume fraction And the corresponding temperature data fitting, measuring and calculating the parameters n, C, and ΔH in the JMAK equation, that is, based on the thermal expansion experiment, fitting, measuring, and calibrating the parameters of the high instantaneous solid phase transition JMAK equation, and improving the high instantaneous solid phase transition JMAK Accuracy of Equation for Prediction of Austenitic Transformation in Metals During High Transient Heating

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