JPS61147860A - Method for refining grain of primary crystal si in hyper-eutectic al-si alloy - Google Patents

Abstract

PURPOSE:To enhance the grain refining effect of P and to improve the yield of P by continuously adding a grain refiner contg. P for proeutectic Si to a molten hyper-eutectic Al-Si alloy flowing in a casting spout. CONSTITUTION:The molten hyper-eutectic Al-Si alloy 12 in a holding furnace 10 is introduced into the casting spout 16, and a grain refiner 30 contg. P for the proeutectic Si is continuously added to the molten alloy 15 flowing in the spout 16 so as to refine the grains of proeutectic Si in the molten alloy 12 during solidification. Thus, the grain refining effect of P is enhanced and the yield of P is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for refining primary crystal Si during solidification of a molten hypereutectic Al-3i alloy.

(Prior art) Al-Si alloys exhibit high fluidity in the molten state and have little shrinkage during solidification, so they are widely used as casting alloys, especially hypereutectic A1-3i alloys with a high Si acid content. The alloy is used as a foundry alloy with excellent wear resistance.

By the way, the eutectic point (generally Si=1
When continuously casting a predetermined ingot using an Al-3i alloy with a content of 1.6% or more, it is generally adopted to pour the molten Al-3i alloy contained in a holding furnace into a casting trough. In this method, the hypereutectic Al-3
The pro-eutectoid Si crystals during solidification of i-series alloys are 40μ or more, sometimes 100μ or more, unless particularly refined.
It becomes coarse grains of μ or more. As a result, the structure of the ingot becomes rough and its properties become inferior. Therefore, such hypereutectic Al
In -3i alloys, primary Si crystals are refined by adding P to the molten alloy. This P
By adding , Al and P compounds are generated, and the nucleating effect of this Al and P refines the primary crystal Si.

(Problems to be Solved by the Invention) By the way, the addition of P to a molten hypereutectic Al-3i alloy has conventionally been carried out by adding Cu-
This is done by adding a primary Si refiner in the form of an intermediate alloy such as 8% P, Cu-15% P, or a flux containing P. Due to charging into the holding furnace, it is difficult to uniformly disperse P in the entire molten metal, and there have been problems in that the yield of P is poor. Since the amount of P added is extremely small in proportion to the amount of molten alloy, even if the molten metal in the holding furnace is stirred, the concentration tends to be uneven, and some of it may settle during stirring. , they float to the surface of the molten metal and are no longer effectively utilized.

Furthermore, in such conventional methods, the refinement effect of P changes with the passage of casting time, and the ingot part cast in the early stage of casting and the ingot part cast in the latter stage are different from each other. However, the size of the primary crystal 3i differs, resulting in a problem that the quality of the product also changes. P
After the addition of Si, its refining effect becomes smaller as time passes. Therefore, although the primary Si crystals in the ingot part cast in the early stage of casting are effectively refined, in the later stage, the refining effect becomes smaller. The effect becomes smaller and the size of primary Si becomes larger than that at the initial stage of casting.

(Means for Solving the Problems) The present invention has been made to solve these problems, and its gist is that primary Si? By continuously adding an lt-refining agent to the molten hypereutectic Al1-3i alloy flowing in the casting trough, the Si primary crystals during solidification of the alloy are effectively refined. It is in.

(Functions and Effects) That is, the present invention eliminates the need to add the primary Si refiner in an amount corresponding to the total amount of the molten metal at once to the molten metal housed in the holding furnace. A corresponding amount of the primary Si refining agent was continuously added to a portion of the molten metal gradually flowing out from the holding furnace.

As a result, primary crystal S is formed in the hypereutectic Af-Si alloy molten metal.
The i-refining agent can be uniformly dispersed, and the P added to the molten metal can be effectively utilized, improving its yield.

Furthermore, in the present invention, since the primary Si refining agent is continuously added to the molten metal immediately before casting, the effect of refining P is large, and after adding P, Since the time is also constant, the quality of the product does not change between the early and late stages of casting, which is the case with conventional methods.

(Example) Next, an example of the present invention will be specifically described based on the drawings.

In Fig. 1, numeral 10 is a heat-retaining furnace as a molten metal holding furnace.
A molten i-based alloy 12 is accommodated therein. The molten alloy 12 in the heat-retaining furnace 10 is led from the tap 14 to a casting gutter 16, flows through the casting gutter 16, and is cast into the casting device 20 from the supply port 18. As a result, the hypereutectic Al-Si alloy billet 22 is continuously produced.

The molten alloy 15 flowing through the casting trough 16 contains:
According to the present invention, a primary Si refining agent containing P is added, but in this example, this refining agent is a Cu-8% P alloy as shown in FIG. It is said to be in the form of grains, which are made of AI thin tubes (wall thickness 0.5 to 2 m,
(outer diameter 5 to 15 fi) 26 is densely packed.

As shown in FIG. 1, the AJ thin tube 26 is wound into a coil, and the AI thin tube 26 is gradually taken out from the coil portion 2!5 by the feeding device 28. It is charged into the molten alloy 15 in the casting trough 16 from its tip side. The alloy was charged into the molten metal 15. 11 thin tube 2
6 is melted into the molten metal by the heat of the molten metal, and at the same time, the refiner 30 filled inside the molten metal enters into the molten metal. The A, l tubes 26 are continuously fed into the molten metal 15 according to the flow rate of the molten alloy metal 15, whereby the refining agent 30 in the JL tubes 26 is introduced into the molten alloy metal 15 at a predetermined ratio. added.

The position at which the Al thin tube 26 is charged into the molten metal 15 is such that the /l thin tube 26 can be sufficiently dissolved in the molten alloy 15 in the casting gutter 16, and the refining agent 30 can be sufficiently refined. A location that can be effective is selected. Its proper position is in the form of the atomizing agent 30.

Although it varies depending on the composition etc., in this example, the finer
In this case, the temperature of the molten metal 15 is relatively high and the residence time in the casting is at least 1 minute or more at the outlet 14 of the heat retention furnace 10.
It will be nearby. In addition, if there is a degassing device on the casting trough 16 to remove dissolved gas in the molten alloy 15, the refining agent 3
It is desirable to add 0 just before that. The added refiner 30 is transferred to the molten alloy 15 by a degassing device.
This is because they can be well dispersed in the interior of the container.

In this way, the method of the present example allows the hypereutectic An! -Refining agent 30% for molten Si alloy 15%
Since P is added little by little and continuously, the yield of P is improved. In the heat retention furnace 10,
As in the case where the total amount of the necessary refining agent 30 is added simultaneously and all at once, the refining agent 30 settles or floats up inside the heat insulating furnace 10, and it no longer works effectively as a refining agent. This is because there is no such thing.

Furthermore, since the refining agent 30 is continuously added to the molten alloy 15 flowing through the casting trough 16, the refining agent 30 is uniformly dispersed in the molten alloy 15, and the P in the molten metal 15 is The concentration of is also appropriate and constant.

Moreover, in this example, since the refining agent 30 is added to the molten metal 15 immediately before pouring, the effect of refining P is large. Since the time until it is cast is always constant,
At! -The primary Si of the Si-based alloy is finely refined, and there is no difference in the degree of refinement between the early and late stages of casting.

Furthermore, in this example, the atomizing agent 30 is AA! Since the Al thin tube 26 is charged into the molten alloy 15 in a covered state, the refiner 30 is added to the molten alloy 15 immediately before adding it to the molten alloy 15.
is suppressed from being oxidized by the heat of the molten alloy 15,
Moreover, since the atomizing agent 30 is in a granular form, Al
After the capillary tube 26 is melted, it can be quickly injected into the molten alloy 15 and uniformly dispersed.

Table 1 shows that Al-
200fi diameter billet 22 using 18% Si alloy
In casting, the experimental results were obtained when the primary crystalline Sin refiner (Cu-8%P) 20 of the above form was added to the molten alloy 15 in the pouring trough 16 by adding it to the conventional heat retention furnace IO. This is shown in comparison with the case. The amount of P added is 100pp+ for both the powder method and the conventional method.
The goal was m.

As is clear from this table, the yield of P is greatly improved by this method, the primary Si is effectively refined, and there is no difference in the degree of refinement between the early and late stages of casting. was confirmed.

Although one specific example of the present invention has been described above, the present invention can be implemented in other embodiments.

For example, it is also possible to use a primary crystal Sim refiner, such as Cu-15%P, or a refiner having another composition. Also,
It is advantageous if the refining agent is in the form of such an alloy, since the removal of reaction residues becomes unnecessary, but it is also possible to add such a refining agent in the form of a P-containing flux into the molten alloy. It is. It is also possible to form the refining agent into granules and add it directly to the molten alloy in the casting trough using a vibrating feeder, etc. Furthermore, the position at which the refining agent should be added to the molten alloy is , as shown above, is not limited to the vicinity of the outlet of the holding furnace, but the composition of the refining agent,
It is possible to select an appropriate position depending on the form.

In addition, the present invention can be implemented with various modifications based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a simplified diagram showing the state of implementation of a method for refining primary crystal Si, which is a specific example of the present invention, together with a casting device. FIG. 2 is a perspective view of a main part showing the primary Sil refiner in FIG. 1 together with an Af thin tube. 10: Heat retention furnace (holding furnace) 12.15: Hypereutectic AJ-Si alloy molten metal 16: Casting gutter 20: Casting device 22: Billet (ingot) 26: Aj + capillary tube 30:
Cu-8%P alloy grains (primary Si refining agent) Applicant: Sumitomo Light Metal Industries, Ltd. Figure 1 Figure 2 Procedures (Hoshosho stamping) Date dated February 13, 1985

Claims (2)

[Claims] (1) When the hypereutectic Al-Si alloy molten metal contained in the holding furnace is guided to the casting equipment through the pouring gutter to produce a predetermined ingot, a primary Si refining agent containing P is added. , primary crystals in a hypereutectic Al-Si alloy, characterized in that primary crystals of Si during solidification of the alloy are refined by continuously adding them to the molten alloy flowing in the casting trough. A method for making Si finer. (2) The primary Si refining agent is made into a granular form containing P and is filled into an Al thin tube, and the Al thin tube is inserted from its tip into the molten alloy in the casting trough. The primary crystal S according to claim 1 is added to the molten metal by adding the primary crystal Si refiner into the molten metal.
i refinement method.