Measuring method of aluminum alloy CCT (Continuous Cooling Transformation) diagram

Abstract

The invention discloses a measuring method of an aluminum alloy CCT (Continuous Cooling Transformation) diagram, which comprises the following steps: 1. measuring data of aluminum alloy voltage and temperature along with the change of time under various cooling regimes; 2. drawing a voltage-temperature curve and a temperature-time curve in the cooling process of a sample according to the data obtained by the first step; 3. determining phase transformation points: determining the temperatures of phase transformation starting points and phase transformation ending points of the aluminum alloy sample according to the change position of the slope of the voltage-temperature curve; and 4. drawing the CCT diagram: drawing the temperature-time curve of the sample obtained at different cooling speeds to a logarithmic coordinate system, labeling the phase transformation starting points and the phase transformation ending points on corresponding temperature-time curves according to the phase transformation starting points and the phase transformation ending points determined according to the voltage-temperature curve, and connecting the phase transformation starting points and the phase transformation ending points by lines to obtain the CCT diagram of the sample alloy. The method has the advantages of strong operability, simple process, simple operation, high speed, dense acquired points, measuring material saving and higher measuring precision, fills up the blank of a measuring technology of the CCT diagram of the aluminum alloy and is suitable for scientific research units to measure the phase transformation points of the aluminum alloy and the CCT diagram.

Description

technical field [0001] The invention discloses a method for measuring a CCT map of an aluminum alloy, belonging to the technical field of metal material testing. Background technique [0002] Thermal processing and heat treatment processes are very important to improve the microstructure and properties of alloys. After thermal processing and heat treatment, metal materials must adopt appropriate cooling medium and cooling speed, and control the type, size, quantity and distribution of the second phase by controlling the cooling rate. , so as to obtain specific organization and performance. The continuous cooling transformation kinetics curve (CCT diagram) is the basis for studying solid-state phase transition and formulating heat treatment processes. The appropriate cooling medium and cooling rate can be determined by using the CCT diagram. [0003] The method of measuring the continuous cooling transformation kinetic curve of iron and steel materials is becoming more and m...

AI Technical Summary

Problems solved by technology

Li Hongying and others measured the CCT diagrams of 2A97 and 7475 aluminum alloys by using the continuous relative resistance method combined with DTA, Xrd, microstructure quantitative analysis and other methods. Relative change (R T -R 0 ) / R 0 According to the temperature change curve, the phase change point can be judged. Since the double-arm bridge measurement circuit passes a weak current, it is difficult to eliminate the oxide film with high resistance, and it cannot shield the influence of electrode contact on the measurement accuracy. The measured resistance shows The value is not accurate, it cannot accurately reflect the phase change process, and the relative resistance value change is unstable during the measurement process, and the measured resistance change value is also small, which will bring errors when drawing the CCT diagram. At present, it can be more accurate The method of measuring the CCT map of aluminum alloy has not been reported so far

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