A thermal analysis method for judging modification level of ZL114A alloy online

Abstract

The application discloses a kind of online judgment ZL114A alloy modification level thermal analysis method, comprising: 1) in the production smelting process of ZL114A alloy, a certain amount of cast aluminum melt is sampled, and is poured in square sample cup with thermocouple, and the cooling curve of aluminum liquid solidification process is collected using thermal analysis instrument, and the temperature data in cooling process is obtained;2) the temperature data of the collected aluminum liquid solidification process is filtered, the interference in the experimental process is excluded, and the temperature characteristic value required for subsequent analysis is extracted;3) the temperature characteristic value of ZL114A in cooling process extracted from cooling curve is substituted into modification grade evaluation model, and the modification grade of ZL114A evaluated by software online is obtained.The method of the application uses modification grade calculation model to evaluate and calculate the modification grade of target aluminum liquid, can make more rapid, more accurate judgment to the modification effect of ZL114A alloy, provide basis for the dynamic adjustment of the addition amount of modifier in production process, and guarantee the yield of ZL114A alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy casting, in particular to a thermal analysis method for online determination of modification level of ZL114A alloy. BACKGROUND

[0002] Al-Si alloy is the most widely used casting aluminum alloy, and hypoeutectic Al-Si alloy ZL114A is widely used in the fields of transportation and aerospace due to its high specific strength, large specific modulus, high corrosion resistance and good casting performance. Since the Si content in ZL114A alloy is relatively high, it is a typical hypoeutectic alloy, and the plate-shaped eutectic silicon seriously restricts the performance of the alloy. The morphology of eutectic silicon can be changed by modification treatment, which can improve the mechanical properties of the alloy. Si modification treatment is indispensable in Al-Si alloy casting, and grain refinement and eutectic silicon structure improvement have always been a research hotspot.

[0003] In actual production, the modification effect of the modified Al-Si alloy needs to be detected before pouring, and the modification effect of the alloy melt directly affects the performance of the cast product. How to quickly and accurately detect the modification effect of the melt is the key to improving the quality of the castings and improving the yield of the production. The methods for detecting the modification effect before pouring mainly include metallographic method, fracture observation method, electrical conductivity method and thermal analysis method, etc. However, these instruments and methods have high requirements for working environment and sample, and the detection period is long, which cannot meet the requirements of rapid detection at the furnace. In actual production, in order to quickly determine the modification effect of aluminum-silicon alloy before pouring, rapid thermal analysis technology at the furnace is often used. The detection of alloy modification effect at the furnace is an important link to improve the quality of castings and realize production control. SUMMARY

[0004] The present application aims at the deficiencies of the prior art, and provides a thermal analysis method for online determination of modification level of ZL114A alloy, which can make a more rapid and accurate judgment of the modification effect of ZL114A alloy in the production of ZL114A alloy, provide a basis for dynamic adjustment of the addition amount of modification agent in the production process, and better guarantee the yield of ZL114A alloy.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0006] A thermal analysis method for online determination of modification level of ZL114A alloy, comprising the following steps:

[0007] Step 1, in the production and smelting process of ZL114A alloy, a certain amount of cast aluminum melt is sampled and poured into a square sample cup with a thermocouple, and a thermal analysis instrument is used to collect the cooling curve of the aluminum melt solidification process to obtain the temperature data in the cooling process;

[0008] Step 2, filtering the collected temperature data of the solidification process of the aluminum liquid, excluding interference in the experiment process, and extracting temperature characteristic values required for subsequent analysis;

[0009] Step 3, substituting the temperature characteristic values of ZL114A in the cooling process extracted from the cooling curve into the modification grade evaluation model to obtain the modification grade of ZL114A evaluated by the software online.

[0010] Specifically, the extraction of the temperature characteristic values required for subsequent analysis in step 2 includes the following steps:

[0011] Step 21, differentiating the collected cooling curve of the solidification process of the aluminum liquid to obtain the corresponding differential cooling curve;

[0012] Step 22, extracting the temperature characteristic values required for subsequent analysis according to the cooling curve and the differential cooling curve of the solidification process of the aluminum liquid.

[0013] Further, the extraction of the temperature characteristic values required for subsequent analysis in step 2 includes the highest temperature TM, the lowest temperature of the primary crystal stage TLU, the highest temperature of the primary crystal growth TLO, the lowest temperature of the eutectic stage TSU and the highest temperature of the eutectic growth TSO.

[0014] Specifically, the substitution into the modification grade evaluation model in step 3, the calculation formula of the modification grade evaluation model for ZL114A alloy is:

[0015] Modification grade = -0.05677 x △TSU 3 -1.172 x △TSU 2 -6.111 x △TSU + 1.002

[0016] In the above formula, △TSU is the difference of the lowest temperature of the eutectic before and after modification.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] The application provides a thermal analysis method for online determination of modification level of ZL114A alloy. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A flow chart of the thermal analysis method for online determination of modification level of ZL114A alloy according to the application;

[0020] Figure 2 Metallographic photos of ZL114A aluminum alloy after heat preservation for 30 min and 45 min in Example 1 of the application;

[0021] Figure 3 Metallographic photos of ZL114A aluminum alloy after heat preservation for 30 min and 45 min in Example 2 of the application;

[0022] Figure 4 Metallographic photos of ZL114A aluminum alloy after heat preservation for 30 min and 45 min in Example 3 of the application;

[0023] Figure 5 Metallographic photos of ZL114A aluminum alloy after heat preservation for 30 min and 45 min in Example 4 of the application;

[0024] Figure 6 Metallographic photos of ZL114A aluminum alloy after heat preservation for 30 min and 45 min in Example 5 of the application;

[0025] Figure 7 Metallographic photos of ZL114A aluminum alloy after heat preservation for 30 min and 45 min in Example 6 of the application;

[0026] Figure 8 Metallographic photos of ZL114A aluminum alloy after heat preservation for 30 min and 45 min in Example 7 of the application. DETAILED DESCRIPTION

[0027] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] like Figure 1 As shown, the present invention provides a thermal analysis method for online determination of the deterioration level of ZL114A alloy, comprising the following steps:

[0030] Step 1: During the ZL114A alloy production and smelting process, a certain amount of molten aluminum is sampled and poured into a square sample cup with a thermocouple. The cooling curve of the aluminum liquid during solidification is collected using a thermal analysis instrument to obtain temperature data during the cooling process.

[0031] Step 2: Filter the collected temperature data of the aluminum liquid solidification process to eliminate interference during the experiment and extract the temperature characteristic values ​​required for subsequent analysis;

[0032] Step 3: Substitute the temperature characteristic value of ZL114A during the cooling process extracted from the cooling curve into the deterioration grade evaluation model to obtain the deterioration grade of ZL114A evaluated online by the software.

[0033] Specifically, extracting the temperature characteristic values ​​required for subsequent analysis in step 2 includes the following steps:

[0034] Step 21: performing differential processing on the collected cooling curve of the aluminum liquid solidification process to obtain a corresponding differential cooling curve;

[0035] Step 22: According to the cooling curve and the differential cooling curve of the aluminum liquid solidification process, the temperature characteristic value required for subsequent analysis is extracted.

[0036] Furthermore, in step 2, the temperature characteristic values ​​required for subsequent analysis are extracted, and the temperature characteristic values ​​include the maximum temperature TM, the lowest temperature of the primary crystal stage TLU, the highest temperature of the primary crystal growth TLO, the lowest temperature of the eutectic stage TSU and the highest temperature of the eutectic growth TSO.

[0037] Specifically, the modification grade in step 3 is substituted into the modification grade evaluation model, and the modification grade calculation formula of the ZL114A alloy in the modification grade evaluation model is:

[0038] Modification grade = -0.05677 x ΔTSU 3 -1.172 x ΔTSU 2 -6.111 x ΔTSU + 1.002

[0039] In the above formula, ΔTSU is the difference between the eutectic minimum temperatures before and after modification.

[0040] The origin of the modification grade calculation formula in the modification grade evaluation model of the method is described below through a set of thermal analysis experiments of the ZL114A alloy smelting process.

[0041] Example 1

[0042] The crucible required for the experiment is preheated in the resistance furnace, and the aluminum alloy is dried at the same time; when the temperature reaches 500°C, the ZL114A alloy is placed in the crucible, and the temperature is raised to start smelting; after smelting, hexachloroethane is added for refining and degassing; a certain amount of original aluminum liquid without modification treatment is placed in a square sample cup, and thermal analysis data are collected, analyzed and results are output through a thermal analyzer to obtain a thermal analysis cooling curve, and then obtain various characteristic temperature points reflecting the melt: the highest temperature TM, the lowest temperature TLU in the primary crystal stage, the highest temperature TLO in the primary crystal growth, the lowest temperature TSU in the eutectic stage, and the highest temperature TSO in the eutectic growth.

[0043] It should be noted that the above-mentioned highest temperature TM, the lowest temperature TLU in the primary crystal stage, the highest temperature TLO in the primary crystal growth, the lowest temperature TSU in the eutectic stage, and the highest temperature TSO in the eutectic growth are all thermal analysis characteristic parameters automatically read by the thermal analyzer.

[0044] The aluminum liquid in the sample cup at this time is poured into an ingot, which is sawn and ground to prepare a metallographic sample, and then the microstructure of the ingot is observed under a microscope, and a metallographic photo is taken, and the results are shown in Figure 2 .

[0045] Example 2

[0046] The difference between this embodiment and Example 1 is that 0.1% of Al-10Sr alloy is added to the molten aluminum during smelting, and samples are taken after 30 minutes and 45 minutes of holding, respectively; and the sampled aluminum liquid is poured into an ingot, which is sawn and ground to prepare a metallographic sample, and then the microstructure of the ingot is observed under a microscope, and a metallographic photo is taken, and the results are shown in Figure 3 .

[0047] Example 3

[0048] The difference between this embodiment and embodiment 1 is that 0.2% Al-10Sr alloy is added to the molten aluminum liquid, and samples are taken after holding for 30 minutes and 45 minutes respectively; the sampled aluminum liquid is cast into ingots, and metallographic specimens are sawed and ground. The microstructure of the ingots is then observed under a microscope and metallographic photographs are taken. The results are shown in FIG. Figure 4 shown.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is that 0.3% Al-10Sr alloy is added to the molten aluminum liquid, and samples are taken after holding for 30 minutes and 45 minutes respectively; the sampled aluminum liquid is cast into ingots, and metallographic specimens are sawed and ground. The microstructure of the ingots is then observed under a microscope and metallographic photographs are taken. The results are shown in FIG. Figure 5 shown.

[0051] Example 5

[0052] The difference between this embodiment and embodiment 1 is that 0.4% Al-10Sr alloy is added to the molten aluminum liquid, and samples are taken after holding for 30 minutes and 45 minutes respectively; the sampled aluminum liquid is cast into ingots, and metallographic specimens are sawed and ground. The microstructure of the ingots is then observed under a microscope and metallographic photographs are taken. The results are shown in FIG. Figure 6 shown.

[0053] Example 6

[0054] The difference between this embodiment and embodiment 1 is that 0.5% Al-10Sr alloy is added to the molten aluminum liquid, and samples are taken after holding for 30 minutes and 45 minutes respectively; the sampled aluminum liquid is cast into ingots, and metallographic specimens are sawed and ground. The microstructure of the ingots is then observed under a microscope and metallographic photographs are taken. The results are shown in FIG. Figure 7 shown.

[0055] Example 7

[0056] The difference between this embodiment and embodiment 1 is that 0.6% Al-10Sr alloy is added to the molten aluminum liquid, and samples are taken after holding for 30 minutes and 45 minutes respectively; the sampled aluminum liquid is cast into ingots, and metallographic specimens are sawed and ground. The microstructure of the ingots is then observed under a microscope and metallographic photographs are taken. The results are shown in FIG. Figure 8 shown.

[0057] Table 1 below shows the characteristic values ​​of the cooling curves of the ZL114A alloy thermal analysis experiments extracted by the thermal analyzer in the above Examples 1-7.

[0058] Table 1. Characteristic values ​​of cooling curves of ZL114A alloy thermal analysis experiments extracted in various examples

[0059]

[0060]

[0061] From the data in Table 1 and the corresponding metallographic pictures (Fig. 1), it can be preliminarily seen that after adding the modifier, the lowest temperature TSU of the eutectic stage in the cooling curve of ZL114A alloy is obviously reduced compared with that before modification; then, with the increase of the modifier addition, the value of TSU gradually increases. Figures 2-8

[0062] Further, the difference △TLU of the lowest temperature of the primary crystallization stage TLU, the difference △TLO of the highest temperature of the primary crystallization growth TLO, the difference △TSU of the lowest temperature of the eutectic stage TSU, and the difference △TS of the lowest temperature of the eutectic stage TSU and the highest temperature of the eutectic growth TSO before and after modification are calculated according to the data on the cooling curve, and the obtained data are shown in Table 2.

[0063] Table 2, the differences of the temperatures of each stage before and after modification calculated according to the cooling curve in each example

[0064]

[0065]

[0066] Note: The molten aluminum of Example 1 is not added with Al-10Sr alloy, and the modification does not occur during the smelting process, so there is no analysis data before and after modification.

[0067] From the data in Table 2, it can be seen that the difference of the lowest temperature of the eutectic stage TSU before and after modification gradually increases; it is indicated that the higher the modification grade, the greater the difference of the lowest temperature of the eutectic stage TSU; the relationship between the two is determined by MATLAB software as a data processing tool, data analysis, the influence relationship between the dependent variable and the independent variable, and the mathematical calculation model is expressed as:

[0068] Modification grade = -0.05677 × △TSU 3 -1.172 × △TSU 2 -6.111 × △TSU + 1.002

[0069] In the above formula, △TSU is the difference of the lowest temperature of the eutectic stage before and after modification.

[0070] ​To sum up, the method of the present application can evaluate and calculate the modification grade of the target aluminum liquid by sampling the modified aluminum liquid in the production process of ZL114A alloy in a square sample cup, collecting the corresponding thermal analysis cooling curve, extracting the characteristic value of the thermal analysis cooling curve, and using the modification grade calculation model to evaluate and calculate the modification grade of the target aluminum liquid, and evaluating the modification effect of the produced aluminum liquid according to the obtained modification grade result; so that the modification effect of ZL114A alloy can be more quickly and accurately judged in the production of ZL114A alloy, and the dynamic adjustment of the addition amount of the modifier in the production process can be provided with basis, and the yield of ZL114A alloy is ensured.

[0071] It should be understood that the above description of the preferred embodiments is more detailed and should not be considered as limiting the scope of patent protection of the present application. Those skilled in the art can make substitutions or modifications without departing from the scope of protection claimed by the present application under the inspiration of the present application, and all fall within the scope of protection of the present application. The scope of protection of the present application shall be subject to the appended claims.

Claims

1. A thermal analysis method for online determination of the deterioration level of ZL114A alloy, characterized in that: The following steps are involved: Step 1: During the ZL114A alloy production and smelting process, a certain amount of molten aluminum is sampled and poured into a square sample cup with a thermocouple. The cooling curve of the aluminum liquid during solidification is collected using a thermal analysis instrument to obtain temperature data during the cooling process. Step 2: Filter the collected temperature data of the aluminum liquid solidification process to eliminate interference during the experiment and extract the temperature characteristic values ​​required for subsequent analysis; Step 21: performing differential processing on the collected cooling curve of the aluminum liquid solidification process to obtain a corresponding differential cooling curve; Step 22: extracting the temperature characteristic value required for subsequent analysis based on the cooling curve and the differential cooling curve during the solidification process of the aluminum liquid; Step 3: Substitute the temperature characteristic value of ZL114A during the cooling process extracted from the cooling curve into the deterioration grade assessment model to obtain the deterioration grade of ZL114A assessed online by the software; The formula for calculating the deterioration grade is: Deterioration grade = -0.05677 × △TSU 3 -1.172×△TSU 2 -6.111×△TSU+1.002 In the above formula, △TSU is the difference between the lowest temperatures in the eutectic stage before and after metamorphism.

2. The thermal analysis method for online determination of the modification level of ZL114A alloy according to claim 1, characterized in that: In step 2, the temperature characteristic values ​​required for subsequent analysis are extracted, and the temperature characteristic values ​​include the maximum temperature TM, the lowest temperature of the primary crystal stage TLU, the highest temperature of the primary crystal growth TLO, the lowest temperature of the eutectic stage TSU and the highest temperature of the eutectic growth TSO.

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