JP5504828B2 - Method for evaluating cleanliness of aluminum alloys - Google Patents

Description

The present invention relates to a method for evaluating the cleanliness of an ingot of an aluminum alloy (aluminum alloy) that is a raw material for aluminum die casting, and the aluminum die casting is particularly suitable as a steering component for automobiles.

In an aluminum alloy, non-metallic inclusions have a great influence on their mechanical properties depending on their size, number, dispersion status, etc., so it is necessary to grasp their presence. In order to measure non-metallic inclusions in an aluminum alloy, for example, as in Patent Document 1, the total amount of molten aluminum prepared by melting an aluminum alloy is filtered through a filter, and the weight of the molten aluminum before and after filtration. There is a method of measuring the amount of inclusion by the difference.

JP 2005-134296 A

However, the technique of the cited document 1 is a destructive inspection, and there is a problem that the measured ingot cannot be used for a product. Moreover, the technique of the cited document 1 has a problem that it takes time and labor to measure. Therefore, in order to solve the problems of the conventional technology as described above, the present invention enables the measured ingot to be used for a product in an aluminum alloy ingot that is a raw material for aluminum die casting, and the cleanliness can be reduced in a short time. It is an object to provide a method for evaluating with little effort.

In order to solve the above problems, the present invention has the following configuration. In other words, the aluminum alloy ingot cleanliness evaluation method of the present application measures the hardness and cleanliness of a plurality of aluminum alloy ingots in advance, confirms the correlation of the hardness to the cleanliness, and then determines the hardness of the ingot. It is characterized by evaluating the cleanliness by measuring .

In the method for evaluating the cleanliness of an ingot of an aluminum alloy according to the present invention, the cleanliness can be evaluated without destroying the ingot. Therefore, the evaluated ingot can be used for an aluminum die casting of a product. In addition, after confirming the correlation between the hardness and cleanliness of the ingot, it is only necessary to measure the hardness, and since dissolution and filtration are not required, measurement time for the ingot can be shortened and labor can be saved.

The perspective view of the ingot measured in this embodiment Photograph of the top surface of an ingot with poor cleanliness Photo of top surface of ingot with good cleanliness Ingot side photo Photo of the measurement part on the bottom of the ingot Plan view and side view of tensile specimen Hardness and residue rate graph Hardness and tensile strength graph

Embodiments of an aluminum alloy ingot cleanliness evaluation method according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating the shape of an ingot measured in the present embodiment. In the ingot 1 of FIG. 1, the molten metal is poured from the direction of the upper surface 2 and solidifies from the bottom surface 3. FIG. 2 is a photograph of the top surface of the ingot with poor cleanliness, and FIG. 3 is a photograph of the top surface of the ingot with cleanliness. Although there are many holes on the top surface of the ingot in FIG. 2 and the surface unevenness is large, the surface unevenness on the top surface of the ingot in FIG. 3 is small because there are few holes. More holes are generated on the upper surface of the ingot, and if there are many holes, the error tends to increase when hardness is measured, and it is difficult to obtain a correlation between cleanliness and hardness. It is preferable to measure the hardness of a small bottom surface. In order to improve the measurement accuracy even on the bottom surface, it is preferable to measure a plurality of parts, and more preferably to measure three or more parts.

Next, 240 ingots made of an aluminum alloy AD12.1 as a material were manufactured, and the hardness was measured with a B scale of a Rockwell hardness tester. The hardness measurement is performed at three locations excluding the maximum hardness and the minimum hardness as shown in FIG. 5 at the bottom portions of the left end 4, the center 5 and the right end 6 of the ingot of FIG. The average hardness was the hardness of each part, and the average value of the hardness of each part was the hardness of each ingot. At the time of hardness measurement, the surface roughness, flatness, parallelism, etc. of the measurement part were corrected to be suitable for hardness measurement and then measured. And the thing with similar hardness of each ingot was divided into every 30 pieces like Table 1, and the average value of the hardness of each group was computed.

Next, in order to confirm the cleanliness of each ingot group, the residual ratio of three ingots from each ingot group was measured. The residue rate is the percentage obtained by dividing the difference (M1−M2) between the mass M1 before dissolving each ingot, pressurizing and filtering with a filter, and the mass M2 after filtering by the mass M1 before filtering. The expressed value ((M1-M2) / M1) × 100 (%) was defined as the residue rate of each ingot, and the average value within each group was listed in Table 1 as the residue rate of each ingot group. . The residue rates in Table 1 indicate that the lower the residue rate value, the less non-metallic inclusions and the like, and the better the cleanliness.
Further, in order to confirm the tensile strength of each ingot group, 27 ingots from each ingot group were dissolved for each group. Next, flux injection, molten metal treatment, degassing, and deoxidation treatment were performed for each group under the same conditions, and ten tensile test pieces 8 and 9 shown in FIG. 6 were formed for each group by die casting. Subsequently, these test pieces were subjected to a tensile strength test in accordance with ASTM standards, and the average value of 10 pieces was listed in Table 1 as the tensile strength of each group. And the average value of the hardness of each group and the residue rate were graphed as FIG. 7, and the average value of each group and the tensile strength were graphed as FIG.

From FIG. 7, there is a correlation between the group of hardness 15HRB to 47HRB and the residue rate, and there is a correlation between the group of hardness 50HRB to 61HRB and the residue rate. Therefore, by using this result, it is possible to evaluate the cleanliness without destroying the ingot by measuring the hardness of the ingot from the next time. And the evaluated ingot can be used as a product, and can be evaluated in a short time and with little effort. Further, from FIG. 8, there is a correlation between the tensile strength and the group of hardness 15HRB to 47HRB, and there is also a correlation between the residual ratio and the group of hardness 50HRB to 61HRB, and the hardness is measured and cleaned. It can be said that the result of evaluating the degree is supported as the tensile strength. From the results of FIGS. 7 and 8, it can be seen that in an aluminum alloy produced by die casting, if the ingot has a hardness of 50 HRB or more, preferably 52 HRB or more, the ingot has a good cleanliness. Moreover, a thing with high intensity | strength can be made by using this evaluated ingot. If this method is not used, the molten metal treatment time will be increased to increase the service life, the amount of removal will increase, the die casting yield will also deteriorate, and there will be a delay in production time and cost increase due to time and yield deterioration. Is done.

In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in the present embodiment, an example in which the cleanliness of an ingot made of aluminum alloy AD12.1 was evaluated has been described. However, the evaluation method of the present invention uses other base materials as long as they do not depart from the gist of the present invention. Can be used.

DESCRIPTION OF SYMBOLS 1 Ingot 2 Upper surface 3 Bottom surface 4 Left end 5 Center 6 Right end 7 Hardness measurement location 8 Top view of tensile test piece 9 Side view of tensile test piece

Claims (1)

  In the aluminum alloy ingot cleanliness evaluation method, by measuring the hardness and cleanliness of a plurality of aluminum alloy ingots in advance, confirming the correlation of the hardness to the cleanliness, and then measuring the hardness of the ingot An aluminum alloy ingot cleanliness evaluation method, characterized by evaluating cleanliness.

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