Method for measuring solid fraction of alloy

Abstract

The invention discloses a method for measuring the solid fraction of an alloy, which comprises the following steps of: S1, carrying out DSC (differential scanning calorimetry) experiment on the alloy to be measured to obtain the solid-liquid phase line temperature of the alloy; s2, performing a directional solidification experiment on the to-be-tested alloy to obtain an experimental sample; longitudinally cutting and treating the experimental sample to obtain a longitudinal section with a clear metallographic structure, and eroding and photographing the longitudinal section to obtain a morphology picture; and S3, determining solid fractions at different experimental temperatures through the morphology pictures, and counting the alloy solid fractions of the two-phase region at different temperatures to obtain an accurate relationship between the alloy solid fractions and the temperatures. According to the method, the alloy is subjected to DSC and directional solidification experiments, the accurate solid-liquid phase line and two-phase region structure morphology of the alloy are obtained, and the solid fraction of the alloy at different temperatures can be directly and accurately obtained through statistical analysis of the two-phase region structure; the method has the advantages of simplicity in operation, accurate alloy temperature and solid fraction measurement results, wide application range and the like.

Description

Technical Field

[0001] The invention relates to an alloy determination method, in particular to a method for measuring alloy solid phase ratio. Background Art

[0002] The relationship between the solid phase ratio and temperature is one of the most important properties of alloys. It plays an important guiding role in the production of alloys, such as the formulation of alloy heat treatment process, welding process, alloy quality control and process parameter formulation in the manufacture of complex parts. Therefore, clarifying the relationship between the solid phase ratio and temperature of alloys can provide data support for alloy production and processing.

[0003] There are two main methods for measuring the relationship between alloy temperature and solid phase ratio reported in existing literature. One is to heat the alloy sample to a specific temperature and then quench it to statistically analyze the relationship between the solid phase ratio and temperature. This method is not only time-consuming and labor-intensive, but also because the sample temperature is difficult to accurately control during the heating and quenching process, there is an error in the obtained relationship between the temperature and the solid phase ratio, and the error is difficult to eliminate. Another method is to calculate the relationship between the alloy solid phase ratio and temperature through software or empirical formulas. The software calculation has good accuracy for common alloy materials, but when the alloy composition changes, the limitations of the software will cause deviations in the calculation results. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for measuring the alloy solid phase ratio with accurate measurement results.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention includes the following steps:

[0006] S1. Performing a differential scanning calorimetry (DSC) experiment on the alloy to be tested to obtain the solidus-liquidus temperature of the alloy;

[0007] S2. Performing a directional solidification experiment on the alloy to be tested to obtain an experimental sample; longitudinally cutting and processing the experimental sample to obtain a longitudinal section with a clear metallographic structure; etching and photographing the longitudinal section to obtain a morphological photograph;

[0008] S3. Determine the solid phase ratio at different experimental temperatures through morphology photos, and statistically analyze the solid phase ratio of the alloy at different temperatures in the two-phase region to obtain the accurate relationship between the solid phase ratio and temperature of the alloy.

[0009] Furthermore, in step S1, the temperature change rate of the DSC experiment is controlled within ±30°C / min.

[0010] Furthermore, the parameter control of the directional solidification experiment in step S2 is as follows: the temperature gradient selection range is 1.0×10 -4~1.0×10 -3 ℃ / m, the pulling speed selection range is 5~50μm / s.

[0011] Furthermore, in step S3, the morphology photograph of the two-phase region is divided into different temperature regions according to the temperature gradient, and the solid phase ratio in each temperature region in the morphology photograph is calculated, so as to determine the solid phase ratio at different experimental temperatures.

[0012] The beneficial effect of adopting the above technical solution is that the present invention obtains the accurate solid-liquid phase line and two-phase region structure morphology of the alloy by performing DSC and directional solidification experiments on the alloy, and can directly and accurately obtain the solid phase ratio of the alloy at different temperatures by statistical analysis of the two-phase region structure. The present invention has the advantages of simple operation, accurate alloy temperature and solid phase ratio measurement results, and a wide range of applications, and is suitable for measuring the relationship between the solid phase ratio and temperature of various alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0014] Figure 1 is a DSC test result diagram of the high manganese steel described in Example 1 of the present invention;

[0015] Figure 2 is a morphological photograph of the high manganese steel obtained in Example 1 of the present invention;

[0016] Figure 3 is a photograph of the solid phase ratio and temperature distribution of the high manganese steel described in Example 1 of the present invention;

[0017] Figure 4 1 is a graph showing the DSC test results of the medium manganese steel described in Example 2 of the present invention;

[0018] Figure 5 This is a morphological photograph of the medium manganese steel obtained in Example 2 of the present invention;

[0019] Figure 6 This is a photograph of the solid phase ratio and temperature distribution of the medium manganese steel described in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] The method for measuring the solid phase ratio of the alloy comprises the following steps:

[0021] S1. Perform a DSC experiment on the alloy to be tested. The temperature variation rate of the DSC experiment is controlled within ±30°C / min to obtain the solidus-liquidus temperature and liquidus temperature of the alloy. The DSC experiment can obtain an accurate solidus-liquidus temperature of the alloy by selecting a lower temperature variation rate.

[0022] S2. Carry out directional solidification experiment on the alloy to be tested. The temperature gradient selection range of the directional solidification experiment is 1.0×10-4 ~1.0×10 -3 ℃ / m, the pulling speed selection range is 5~50μm / s, and the experimental sample is obtained; the purpose of selecting a lower pulling speed in the directional solidification experiment is to ensure that the temperature of the two-phase region of the directional solidification sample is balanced with the temperature gradient in the directional solidification furnace. The experimental sample is cut and processed longitudinally to obtain a rectangular longitudinal section with a clear metallographic structure, and the longitudinal section is etched and photographed to obtain a morphological photo;

[0023] S3. Determine the solid phase ratio at different experimental temperatures through morphology photographs. The specific process is: divide the morphology photographs of the two-phase region into different temperature regions according to the temperature gradient, calculate the solid phase ratio in each temperature region in the morphology photograph, and then determine the solid phase ratio at different experimental temperatures; statistically analyze the alloy solid phase ratio at different temperatures in the two-phase region to obtain an accurate relationship between the alloy solid phase ratio and temperature.

[0024] The solid phase ratio obtained by this method is based on strictly controlled experimental conditions and is obtained by fitting the experimental results. According to the definition of the solid phase ratio, the experimental design ensures the scientificity and accuracy of the measurement; and the temperature is precisely controlled during the experiment to ensure that the measured solid phase ratio reflects the real phase change process.

[0025] Example 1: Take Fe-0.36C-26Mn-3.3Cr high manganese steel as an example for explanation.

[0026] S1, put the Fe-0.36C-26Mn-3.3Cr high manganese steel with dimensions that meet the requirements of the DSC experiment into the DSC equipment, set the temperature program, and complete the DSC experiment according to the equipment operation steps to obtain the DSC curves of high manganese steel at different heating rates. According to the DSC experimental results, the solid-liquid phase line is fitted. The fitting results are shown in Figure 1 It was found that under equilibrium state, the liquidus temperature of Fe-0.36C-26Mn-3.3Cr high manganese steel is 1400℃ and the solidus temperature is 1342℃.

[0027] S2, put the Fe-0.36C-26Mn-3.3Cr high manganese steel with dimensions that meet the requirements of the directional solidification experiment into the directional solidification furnace, set the temperature program, and complete the directional solidification experiment according to the equipment operation steps. The temperature gradient of the directional solidification furnace is 5×10 -3 ℃ / m, the experimental pulling speed is 5μm / s. The obtained experimental sample was longitudinally sectioned and then polished and etched. The morphological photos obtained are shown in Figure 2 shown.

[0028] S3, according to the DSC results, the liquidus temperature of Fe-0.36C-26Mn-3.3Cr high manganese steel is 1400℃, the solidus temperature is 1342℃, and the temperature gradient of the directional solidification furnace is 5×10-3 ℃ / m, that is, the temperature difference of every 1mm is 5℃. Figure 2 The middle two-phase region is divided into 12 regions according to the temperature from low to high, among which the width of regions 1 to 11 is 1 mm, and the width of region 12 is 0.6 mm; the specific distribution of the solid phase rate and temperature of 5 μm / s is as follows Figure 3 As shown in the figure: Area is the divided area; Solid Fraction is the solid fraction, which is obtained by calculating the solid fraction in each area; Temperature is the temperature, unit ℃, except that the top of area 1 is the liquidus temperature and the bottom of area 12 is the solidus temperature, the other temperatures correspond to the average temperature of the area. Figure 3 The relationship between temperature and solid phase ratio is fitted, and the solid phase ratio and temperature formula of Fe-0.36C-26Mn-3.3Cr high manganese steel in this embodiment is obtained as follows: In the formula, F S is the solid phase ratio; T is the temperature, which ranges from 1342 to 1400℃.

[0029] Example 2: Take Fe-0.95C-8.5Mn-2.1Cr medium manganese steel as an example for explanation.

[0030] S1, put the Fe-0.95C-8.5Mn-2.1Cr medium manganese steel with dimensions that meet the requirements of the DSC experiment into the DSC equipment, set the temperature program, and complete the DSC experiment according to the equipment operation steps to obtain the DSC curves of high manganese steel at different heating rates. According to the DSC experimental results, the solid-liquid phase line is fitted. The fitting results are shown in Figure 4 It was found that under equilibrium conditions, the liquidus temperature of Fe-0.95C-8.5Mn-2.1Cr medium manganese steel is 1423℃ and the solidus temperature is 1368℃.

[0031] S2, put the Fe-0.95C-8.5Mn-2.1Cr medium manganese steel with dimensions that meet the requirements of the directional solidification experiment into the directional solidification furnace, set the temperature program, and complete the directional solidification experiment according to the equipment operation steps. The temperature gradient of the directional solidification furnace is 5×10 -3 ℃ / m, the experimental pulling speed is 5μm / s. The obtained experimental sample was longitudinally sectioned and then polished and etched. The morphological photos obtained are as follows Figure 5 shown.

[0032] S3, according to the DSC results, the liquidus of Fe-0.95C-8.5Mn-2.1Cr medium manganese steel is 1423℃, the solidus temperature is 1342℃, and the temperature gradient of the directional solidification furnace is 5×10 -3 ℃ / m, that is, the temperature difference of every 1mm is 5℃. Figure 5The two-phase region in the Fe-0.95C-8.5Mn-2.1Cr medium manganese steel is divided into 11 regions according to the temperature from low to high, and the region width is 1mm; the specific distribution of the solid phase ratio and temperature of the obtained Fe-0.95C-8.5Mn-2.1Cr medium manganese steel is as follows Figure 6 As shown in the figure, Area is the divided area; Solid Fraction is the solid fraction, which is obtained by calculating the solid fraction in each area; Temperature is the temperature, in units of °C. Except for the top of area 1 which is the liquidus temperature and the bottom of area 11 which is the solidus temperature, the other temperatures correspond to the average temperature of the area. Figure 6 The relationship between temperature and solid phase ratio is fitted, and the solid phase ratio and temperature formula of Fe-0.95C-8.5Mn-2.1Cr medium manganese steel is obtained as follows: In the formula, F S is the solid phase ratio; T is the temperature, which ranges from 1368 to 1423°C.

Claims

1. A method for measuring alloy solid phase ratio, characterized in that: The steps include: S1. Perform a DSC experiment on the alloy to be tested to obtain the solidus-liquidus temperature of the alloy; S2. Performing a directional solidification experiment on the alloy to be tested to obtain an experimental sample; longitudinally cutting and processing the experimental sample to obtain a longitudinal section with a clear metallographic structure; etching and photographing the longitudinal section to obtain a morphological photograph; S3. Determine the solid phase ratio at different experimental temperatures through morphology photos, and statistically analyze the solid phase ratio of the alloy at different temperatures in the two-phase region to obtain the accurate relationship between the solid phase ratio and temperature of the alloy.

2. The method for measuring the alloy solid phase ratio according to claim 1, characterized in that: In the step S1, the temperature change rate of the DSC experiment is controlled within ±30°C / min.

3. The method for measuring the alloy solid phase ratio according to claim 1, characterized in that: Parameter control of the directional solidification experiment in step S2: the temperature gradient selection range is 1.0×10 -4 ~1.0×10 -3 ℃ / m, the pulling speed selection range is 5~50μm / s.

4. A method for measuring alloy solid phase ratio according to claim 1, 2 or 3, characterized in that: In step S3, the morphology photograph of the two-phase region is divided into different temperature regions according to the temperature gradient, and the solid phase ratio in each temperature region in the morphology photograph is calculated to determine the solid phase ratio at different experimental temperatures.

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