Method for determining Avrami mathematical model coefficient of metal dynamic recrystallization volume fraction

Abstract

The invention provides a method for determining an Avrami mathematical model coefficient of a metal dynamic recrystallization volume fraction, and the method comprises the following steps: 1, obtaining a stress-strain curve of a material, carrying out water quenching treatment on a sample after the sample is deformed, observing a metallographic structure in the sample, and measuring the recrystallization volume fraction; 2, determining critical strain epsilon c of dynamic recrystallization; 3, determining a return curve; 4, calculating a curve of the volume fraction of the dynamic recrystallization along with the strain; and 5, solving coefficients m and epsilon * of the Avrami mathematical model according to the curve obtained in the step 4. According to the method, only the recrystallization volume fraction in the sample after deformation is measured, the recrystallization volume fraction of the sample in the deformation process is not needed, an equation is directly used for obtaining the curve of the recrystallization volume fraction changing along with strain, and steady-state stress epsilon ss does not need to participate in calculation; compared with the existing method, the method provided by the invention has the advantages of less parameters required in the calculation process, low workload and less sample consumption, and is suitable for popularization.

Description

technical field [0001] The invention relates to the technical field of material microstructure analysis, in particular to a method for determining the Avrami mathematical model coefficient of the dynamic recrystallization volume fraction of metals. Background technique [0002] Metals and alloys will accumulate a large amount of distortion energy inside after plastic deformation. At this time, if it is heated to an appropriate temperature and heat-preserved, the internal distorted structure will nucleate again and the grain grows to form undistorted grains. This process is called the recrystallization process; the recrystallization process Simultaneously with the deformation process, such recrystallization is called dynamic recrystallization; dynamic recrystallization volume fraction is the percentage of the total volume of recrystallized grains in the total volume of the sample, which is closely related to heating temperature, holding time and deformation degree. It can us...

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Problems solved by technology

[0031] Both of the above two methods can obtain the coefficients of the Avrami equation, but both have unavoidable defects

The former metallographic test method not only has a huge workload, but also consumes a lot of funds

The second stress-strain curve analysis method requires the steady-state stress σ ss participate in the calculation, but in the stress-strain curves of most metals and alloys, there is no steady-state stress σ ss , so its applicability is poor

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