Method for testing apparent phase transition temperature of aluminum alloy

Abstract

The invention discloses a method for testing the apparent phase transition temperature of an aluminum alloy, and belongs to the field of nonferrous metal material testing. The method requires that the equivalent diameter of aluminum alloy sample scraps is smaller than or equal to 3 mm, the waiting time of two empty crucibles before an experiment is measured for 2-3 hours, the weight of the empty crucibles is recorded after data are stable, the compacted crucibles are carefully placed on a tray of a differential scanning calorimetry analyzer through a clamp, the waiting time is larger than or equal to 15 min, and the weight of the empty crucibles is recorded. And after the data are stable, recording the weight measurement data of the crucible filled with the sample. And under the condition that the upper limit temperature is not changed, setting more than five different heating rates, starting heating, obtaining a thermal analysis curve of a corresponding sample, capturing the apparent phase change temperature, and drawing a heating rate-phase change apparent temperature and melting enthalpy curve. The method provided by the invention is relatively accurate in test result, has strong guidance on the heat treatment processes such as quenching, homogenization and annealing of the aluminum alloy, and is beneficial to improving the mechanical property and the processability of the aluminum alloy.

Description

Technical Field

[0001] The invention discloses a method for testing the apparent phase change temperature of an aluminum alloy, and belongs to the field of nonferrous metal materials. Background Art

[0002] The phase change of aluminum alloy is a complex process, involving changes in the physical state, microstructure and performance of the material. The phase change of aluminum alloy mainly occurs in the process of solid solution, precipitation, aging, etc. These processes are closely related to the changes in the microstructure of aluminum alloy, such as grain growth, generation and disappearance of crystal defects, precipitation and disappearance of phases, etc. Changes in microstructure will lead to changes in the physical properties and mechanical properties of aluminum alloy.

[0003] Temperature is a key parameter in the dynamic phase transition process of aluminum alloy. Simply put, the phase transition temperature refers to the temperature at which aluminum alloy changes from one physical state to another. This temperature is affected by many factors, including the formula, microstructure, and external environment of the aluminum alloy.

[0004] The apparent phase transition temperature of aluminum alloys can be directly obtained by capturing the thermal analysis curve of alloy phase transition paths at different heating rates through computers. Usually, studying the apparent phase transition temperature can better understand and control the phase transition process of aluminum alloys, thereby optimizing the performance indicators of aluminum alloys. How to determine the apparent phase transition temperature of aluminum alloys is a key technical issue that restricts its further development.

[0005] The test method should meet the actual use requirements and can adjust the heating rate. The national standard stipulates that the heating rate of similar samples is below 20℃ / min. In order to meet the actual application conditions of aluminum alloys, a higher heating rate must be set, and the obtained thermal analysis curve (thermal analysis curve) is more obvious, which intuitively reflects the key information of the study, which is conducive to further guiding the heat treatment process of aluminum alloy quenching, homogenization, annealing, etc., and improving its comprehensive performance and processing performance.

[0006] The present invention discloses a method for testing the apparent phase transition temperature of an aluminum alloy, which mainly tests the apparent phase transition temperature and melting enthalpy of an aluminum alloy under different heating rate conditions by thermal analysis technology. The present invention provides a method for testing the apparent phase transition temperature of an aluminum alloy, the test result has high accuracy, has strong guidance for heat treatment processes such as quenching, homogenization, and annealing, and is conducive to improving its mechanical properties and processing properties. Summary of the invention

[0007] The present invention provides a method for testing the apparent phase transition temperature of an aluminum alloy, comprising the following steps:

[0008] (1) Sample preparation: Place the aluminum alloy under a drilling machine to drill out the debris, use special scissors to process the debris so that its equivalent diameter is ≤3 mm, and use a glass dish to collect a sufficient amount of debris as the experimental sample;

[0009] (2) Equipment preheating: Turn on the differential scanning calorimeter, reset it, use tweezers to pick up two empty crucibles and place them on the tray of the differential scanning calorimeter, wait for 2 to 3 hours, and record the weight of the empty crucible after the data on the display screen stabilizes;

[0010] (3) Sample measurement: Use tweezers to take out one of the empty crucibles, add an appropriate amount of aluminum alloy sample, compact it with a sample spoon, and then use a clamp to carefully place the compacted crucible on the tray of the differential scanning calorimeter. Wait for ≥ 15 min, and record the weight data of the crucible containing the sample after the data on the display screen stabilizes;

[0011] (4) Control measurement: Set the heating rate to 15°C / min and the upper limit temperature to 600°C, start heating and observe the heating process of the instrument, record the heat flow rate and temperature change of the sample, and obtain the thermal analysis curve of the sample; while keeping the upper limit temperature unchanged, increase the heating rate and obtain the thermal analysis curves of the samples respectively;

[0012] (5) Data analysis: Compare and analyze the thermal analysis curves of the samples, capture the apparent phase change temperature, and plot the heating rate-phase change apparent temperature and melting enthalpy curves. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the phase transformation apparent temperature and melting enthalpy curve of 6063 aluminum alloy at different heating rates in Example 1. DETAILED DESCRIPTION

[0014] The present invention will be further described below with reference to the embodiments.

[0015] Example 1

[0016] The method for testing the apparent phase transition temperature of an aluminum alloy comprises the following steps:

[0017] (1) Sample preparation: 6063 aluminum alloy was placed under a drilling machine to obtain chips, and the chips were processed with special scissors to make their equivalent diameter 2.5 mm. A glass dish was used to collect sufficient chips as experimental samples;

[0018] (2) Equipment preheating: Turn on the differential scanning calorimeter, reset it to zero, use tweezers to pick up two empty crucibles and place them on the tray of the differential scanning calorimeter, wait for 2.5 hours, and record the weight of the empty crucible after the data on the display screen stabilizes;

[0019] (3) Sample measurement: Take out one of the empty crucibles with tweezers, add an appropriate amount of aluminum alloy sample, compact it with a sample spoon, and then carefully place the compacted crucible on the tray of the differential scanning calorimeter with a clamp. Wait for 20 minutes, and record the weight data of the crucible containing the sample after the data on the display screen stabilizes;

[0020] (4) Control measurement: Set the heating rate to 15°C / min and the upper limit temperature to 600°C, start heating and observe the instrument heating to record the heat flow rate and temperature change of the sample to obtain the thermal analysis curve of the sample; when the upper limit temperature remains unchanged, increase the heating rate to 20°C / min, 25°C / min, 30°C / min, and 35°C / min, respectively record the heat flow rate and temperature change of the sample, and obtain 5 thermal analysis curves of the sample;

[0021] (5) Data analysis: Compare and analyze the thermal analysis curves of the samples, use the integration method to calculate the area of ​​the thermal analysis curve as the melting enthalpy, capture the apparent phase change temperature, and plot the heating rate-phase change apparent temperature and melting enthalpy curves. The results are as follows: Figure 1 shown.

Claims

1. A method for testing the apparent phase transition temperature of aluminum alloy, characterized in that The equivalent diameter of aluminum alloy chips is ≤3mm.

2. A method for testing the apparent phase transition temperature of aluminum alloy according to claim 1, characterized in that Using a differential scanning calorimeter, two empty crucibles were measured for a waiting time of 2 to 3 hours before the experiment, and the weight of the empty crucible was recorded after the data stabilized.

3. A method for testing the apparent phase transition temperature of aluminum alloy according to claim 1, characterized in that Use a clamp to carefully place the compacted crucible on the tray of the differential scanning calorimeter, wait for ≥15 minutes, and record the weight data of the crucible containing the sample after the data stabilizes.

4. A method for testing the apparent phase transition temperature of aluminum alloy according to claim 1, characterized in that With the upper limit temperature unchanged, set more than 5 different heating rates, start heating and obtain the thermal analysis curve of the corresponding sample, capture the apparent phase change temperature, and draw the heating rate-phase change apparent temperature and melting enthalpy curve.

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