JPH05309447A - Pressure horizontal continuous casting process - Google Patents

Abstract

PURPOSE:To stably obtain phosphor bronze without surface flaws by setting the pressure inside an induction heating furnace by the horizontal continuous, casting process where a mold is provided to the side wall of the induction heating furnace. CONSTITUTION:In a horizontal continuous casting furnace where the continuous casting is executed by cooling the molten metal through a mold made of graphite provided to the side wall of an induction heating furnace 2 which is provided in a chamber 1 while the molten metal being pulled in the horizontal direction, the continuous casting is executed in the pressurized condition where the pressure inside the induction heating furnace 2 is set to the value which is higher than the atmospheric pressure by 0.1kgf/cm<2>, and which is smaller than 1kgf/ cm<2>. This arrangement allows stable manufacture of phosphor bronze with excellent flawless surface property.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal continuous casting method capable of stably casting a bronze cast slab having good surface properties.

[0002]

2. Description of the Related Art A horizontal continuous casting method is one in which a molten metal is continuously fed horizontally from one end of a mold with both ends open installed on the side wall of an induction heating furnace or a tundish to solidify in the mold, and the other end of the mold. It is a method of continuous drawing from the steel, and this method can reduce the size of the device, and since a slab with a size and shape closer to the product can be obtained, the processing cost after the casting process can be low, so iron Alternatively, it is one of the manufacturing methods adopted in various fields regardless of nonferrous metals. For example, in the case of producing a phosphor bronze strip material, when a slab is cast by a so-called "hard continuous casting method" or "semi-continuous casting method", a phenomenon in which Sn is significantly segregated on the surface of the slab tends to occur. In particular, phosphor bronze containing 4% or more of Sn (hereinafter,% representing the component ratio is% by weight) has extremely low hot workability, so that "hard continuous casting method" or "semi-continuous casting method" is used. In the case of a relatively thick cast slab obtained by the above method, there is a problem that it takes a lot of time and labor to perform subsequent processing until it is formed into a strip. Therefore, at present, a "horizontal continuous casting method" capable of producing thin cast pieces is widely used in the production of phosphor bronze strip materials. For example, as shown in FIG.
Molten metal is supplied into the mold 3 installed on the side wall of the induction heating furnace 2 to continuously draw out the slab 4. Reference numeral 5 is a molten metal, and reference numeral 6 is a drawing roll.

[0003]

However, fine defects frequently occur on the surface of the phosphor bronze slab cast by the conventional horizontal continuous casting method, and in order to remove these defects, the surface of the slab or the cast A step of surface-cutting a certain amount of the surface of the raw strip obtained by rolling the piece was indispensable. However, there are some cases in which defects are left behind even by chamfering, and in this case, the defects expand to the inside during further rolling and become "scratch marks", which is one of the causes of lowering the yield.

Therefore, the following facts were confirmed by conducting a basic study on the relationship between the pressure applied to the molten metal during casting by the horizontal continuous casting method and the castability, in particular, the occurrence of surface defects. That is, in an alloy having a wide solid-liquid coexistence range during solidification, a dendrite structure is first formed at the beginning of solidification, and a solute-element-enriched molten metal having a lowered melting point finally solidifies between dendrites. When phosphor bronze, which is a typical copper-based alloy, is observed for surface defects in a slab cast by the conventional horizontal continuous casting method, shrinkage cavity-like defects generated between dendrites as shown in FIG. 4 are observed. there were. In the horizontal continuous casting method, the thickness of the slab is thin and the cooling capacity by the mold is high, so that the temperature gradient in the plate thickness direction during solidification is large. Therefore, in the case of horizontally continuously casting a thin cast piece, the solidification rate of the molten metal increases, so that the intervals of dendrites growing from the surface of the cast piece toward the inside become very narrow. Therefore, Sn between dendrites whose viscosity increased as the solid fraction increased
The movement of the enriched molten metal is obstructed, the molten metal replenishment becomes insufficient, and shrinkage cavities occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a horizontal continuous casting method capable of stably obtaining a phosphor bronze slab having good surface properties without surface defects. ..

[0006]

In order to achieve the above object, the present inventor has conducted various researches as to a measure for preventing the shrinkage cavities which are surface defects of the cast slab, and as a result, in particular, the shrinkage cavity-like defects are solidified. Focusing on the fact that it is difficult to move the molten metal between narrow dendrites at the end of the period, the molten metal in the induction heating furnace or tundish is continuously heated under a pressure higher than atmospheric pressure. It was found that the occurrence of shrinkage-cavity defects can be suppressed as much as possible by performing the casting. The present invention has been completed based on the above findings, and horizontal continuous casting in which molten metal is continuously drawn by cooling while horizontally drawing through a mold installed on the side wall of an induction heating furnace or a tundish. In the method
Air induction heating furnace or tank in the dish, and characterized by performing continuous casting in a state of 0.1 kgf / cm ² or more and pressurized to less than 1 kgf / cm ² above atmospheric pressure by the compressed air or inert gas Is a horizontal continuous casting method, further in the horizontal continuous casting method of continuously casting by cooling while drawing the molten metal horizontally through a mold installed in the side wall of the induction heating furnace or tundish installed in the chamber, The inside of the chamber is 0.1kgf / atmosphere above atmospheric pressure due to the atmosphere, compressed air or inert gas.
cm ² or more, and a horizontal continuous casting method characterized by continuously performing casting in a pressurized state below 1 kgf / cm ^2.

In the present invention, the method for pressurizing the induction heating furnace or the tundish can be carried out by enclosing a pressurized gas in the induction heating furnace or the tundish, but directly in the induction heating furnace or the tundish. If a pressurized gas is enclosed, a large amount of leak will occur from the refractory, the induction heating furnace, or the furnace lid that seals the upper part of the tundish, and high pressure cannot be obtained. Therefore, it is preferable to install an induction heating furnace or a tundish in the chamber and pressurize the chamber.

The pressurized gas may be atmospheric air or compressed air as long as deterioration of the quality of the molten metal due to oxidation does not pose a problem, but depending on the type of alloying element, oxidation may be prevented. It is preferable to use an inert gas. According to the present invention, the applied pressure is 0.1 kgf / cm ² or more and 1 kgf.
/ cm was limited to less than ² is for is less than 0.1 kgf / cm ² can not be obtained shrinkage cavity defects inhibiting effect of the slab by continuous casting under pressure, induction heating at 1 kgf / cm ² or more Furnace,
This is because the tundish or chamber corresponds to a pressure vessel and its manufacture and maintenance are subject to various regulations.

Further, in the horizontal continuous casting method of the present invention, in which the molten metal is continuously drawn by cooling while drawing the molten metal horizontally, the induction heating furnace or the tundish is pressurized to a pressure higher than atmospheric pressure. The reason why the surface defects are suppressed by continuously casting in the above state is as follows. That is, by pressurizing the molten metal to a pressure higher than the atmospheric pressure, the unsolidified molten metal is in a state where a new pressure is applied in addition to the hydrostatic pressure, and the newly added pressure moves the molten metal between the dendrites. Since the solidification progresses while the heat treatment is promoted, the shrinkage cavity defect due to the insufficient supply of the molten metal is effectively prevented, and a sound cast piece can be obtained.

[0010]

EXAMPLES Next, the effects of the present invention will be described more specifically by way of examples. An experiment for clarifying the effect of the present invention was carried out by using a horizontal continuous casting furnace in which a graphite mold 3 was attached to an induction heating furnace 2 installed in a chamber 1 as shown in FIG. Number C5212 thickness 16
mm, width 300 mm, plate-shaped slab was continuously cast. In this experiment, compressed air was introduced through the introduction pipe 7, and continuous casting was performed in a state where the pressure inside the chamber 1 was set to the pressure shown in Table 1 by the pressure valve 8. The results of this experiment are shown in Table 1. Reference numeral 9 is an induction heating device.

[0011]

[Table 1]

In Table 1, Test Nos. 1 to 3 are Examples according to the present invention in which a chamber containing an induction heating furnace was pressed with compressed air to perform casting.
Is a comparative example in which casting was performed using a conventional induction heating furnace without pressurization. Next, a test piece was taken from the cast slab, and after polishing the vertical cross section in the drawing direction, the shrinkage cavity-like surface defects generated on the slab surface by microscope observation were counted, and the maximum depth of the defect was measured. .. Table 1 shows the measured average number of defects per cm in the width direction of the cast slab and the maximum depth of the defects together with comparative examples. Further, a cross-sectional metallographic view (magnification: 50 times) of the defect occurrence portion of the cast piece obtained in test number 1 (this example) is shown in FIG. The cross-sectional metallographic diagram (magnification: 50 times) of the defect generation part of the cast slab is shown, respectively.

As is clear from Table 1 and FIG. 3, the slabs of Test Nos. 1 to 3 according to the present example have shrinkage cavity defects on the surface of the slab as compared with the slab of Test No. 4 as a comparative example. The number of occurrence of defects is extremely small, and the maximum depth of the generated defects is such that it can be sufficiently removed by chamfering the slab, or the raw strip surface obtained by rolling the slab, and has a good surface texture. I know that there is. In this example, the components and composition of the cast alloy, the plate thickness and plate width of the slab, and only a few examples of the casting speed are shown, but it goes without saying that the present invention is not limited thereto. is there.

[0014]

According to the present invention described above, there is provided a horizontal continuous casting method capable of stably producing a slab in which surface defects are reduced as much as possible. It has an extremely useful effect in industry, such as being able to greatly contribute to cost reduction.

[Brief description of drawings]

FIG. 1 is an explanatory view of a horizontal continuous casting device according to the present invention.

FIG. 2 is an explanatory view of a conventional horizontal continuous casting device.

FIG. 3 is a micrograph of a metal structure in a cross section perpendicular to a drawing direction of a continuously cast slab obtained in this example.

FIG. 4 is a micrograph of a metal structure in a vertical cross section of a continuously cast slab obtained in a comparative example.

[Explanation of symbols]

 1 Chamber 2 Induction Heating Furnace 3 Graphite Mold 4 Slab 5 Molten Metal 7 Introduction Pipe 8 Pressure Valve

Claims (5)

[Claims] 1. A horizontal continuous casting method in which a molten metal is continuously drawn while being horizontally drawn through a mold installed on a sidewall of an induction heating furnace or a tundish to cool the molten metal. A horizontal continuous casting method characterized by continuously casting in a state of being pressurized to a pressure higher than atmospheric pressure. 2. An induction heating furnace or a tundish is installed in a chamber, and casting is continuously performed in a state in which the chamber is pressurized to a pressure higher than atmospheric pressure. The horizontal continuous casting method described in the item. 3. The horizontal continuous casting method according to claim 1, wherein the inside of the induction heating furnace, the tundish or the chamber is pressurized with the atmosphere or compressed air. 4. The horizontal continuous casting method according to claim 1, wherein the induction heating furnace, the tundish or the chamber is pressurized with an inert gas. 5. The induction heating furnace, the pressing force of the tundish or in the chamber is 0.1 kgf / cm ² or more and 1 kgf / cm ²
The horizontal continuous casting method according to any one of claims 1 to 4, characterized in that