JPS63132750A - Casting method for clad steel ingot - Google Patents

Abstract

PURPOSE:To prevent integration of nonmetallic inclusions at the boundary between a cladding metal and base metal and degradation in quality by pouring a molten base steel from plural flow-offs at the time of subjecting the large-sized cladding metal to hollow supporting in a casting mold then casting the molten base steel for internal chill into the mold and producing a clad ingot. CONSTITUTION:The cladding metal 1 is supported in parallel by supporting bars 8 on a mold stool 6 in the casting mold 5 part at a prescribed spacing therefrom and the molten base steel 4 for internal chill is poured through a casting port 7 into the mold by bottom pouring, by which the clad ingot is produced at the time of casting the clad ingot for production of a clad steel plate. The molten base steel for internal chill is cast through the plural flow-offs 2 so as to provide the internal chill evenly to the cladding metal 1 it the cladding metal is large and broad. The layer of the nonmetallic inclusions of MnO-SiO2-Al2O3 is made at the boundary between the cladding metal 1 and the base metal for the internal chill on the outside thereof. The defect such as defective adhesion between the base metal and cladding metal of the clad cladding metal produced by rolling such material is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for casting clad ingots, and in particular, even when using wide laminated materials, the entire interface is clean and the adhesive properties are excellent. The present invention proposes a means for advantageously casting an ingot for clad metal plate (hereinafter described as an example of "clad steel plate"), which also has a high cleanliness of the base material.

(Prior art) A method of obtaining a cast clad ingot by pouring molten base metal around a laminating material (core material) is described, for example, in JP-A-39-3.
This is a known thing as seen in disclosures such as No. 259 and Japanese Unexamined Patent Publication No. 60-257947.

Recently, the uses of this cladding material have been greatly expanded, and the reality is that the actual user requirements are wide-ranging.For example, the cladding ratio is not constant, and there are many types. An advantageous rad ingot manufacturing technology that meets these demands is to place the composite material horizontally in the mold and use the base metal molten metal (the following is an example of "molten steel").
A conventional technique has been proposed in which various cladding ratios can be realized with a small amount of equipment by changing the injection amount of .

That is, the technique disclosed in Japanese Patent Application Laid-Open No. 60-257947 is the technique, and its outline is as follows: A plate-shaped laminated material is placed in a position parallel to the rising scene of molten steel being injected into a mold: This technique allows a desired cladding ratio to be obtained by holding the molten steel horizontally and adjusting the amount of molten steel to be poured (i.e., the height of the poured molten steel) in relation to the position of the laminate.

In other words, a composite material of a certain thickness is hollowly supported (suspended or supported below) in a predetermined position (almost horizontally with respect to the bottom of the mold) in a large-section mold, while molten steel is injected into the remaining casting space in the mold. A technology that allows the cladding ratio of cast ingots to be arbitrarily changed by changing the amount of ingots, thereby making it possible to produce steel ingots that meet the various cladding ratios required by users with a small number of molds and pre-prepared mating materials. It is.

As a result, there is no need to prepare many types of molds and various types of laminate materials in advance (by manufacturing a small number of laminate materials, you can immediately respond to orders from users, and the manufacturing process can be significantly shortened. There are advantages.

(Problems to be Solved by the Invention) However, when the ingot obtained by the above-mentioned conventional technique was subjected to blooming rolling to thick plate rolling to obtain a product plate, and an ultrasonic flaw detection test was performed on the product plate, the result was as shown in Fig. 4. As shown, non-metallic inclusions 3 typified by spacer-tite (MnO-5iO□-AlzOs) are observed at the interface between the laminated material 1 and the base material; especially at the edge portion 1e far from the hot water outlet 2; We have identified a phenomenon that reduces strength. Moreover, this tendency occurs when the width of the laminated material is large (>1400 mm).
), it was more noticeable.

Therefore, when the injection speed was increased, the inclusion traps disappeared, but a new problem occurred: the level of the molten metal fluctuated violently, and the cleanliness of the base material deteriorated.

In summary, the object of the present invention is to propose a development of a casting method that is advantageous in overcoming the above-mentioned problems that arise when using wide laminates.

(Means for Solving the Problems) In response to the above-mentioned demands, the present invention has a configuration based on the following points, namely: In the remaining casting space in the mold in which the laminated material is arranged horizontally to the surface plate, In a method of casting a clad ingot, a wide cladding material is cast by pouring base material molten steel for castings, which has a composition different from that of the cladding material, through an outlet provided at a position separate from the cladding material. By employing a method for casting a clad ingot characterized by injecting the cast molten steel from a plurality of inlets during casting, non-metallic inclusions are prevented from forming at the interface between the edge of the mating material and the molten steel. This is a technology that prevents them from accumulating.

(Function) In order to achieve sound interfacial cleanliness, it is necessary to take the following measures, with consideration given to the cleanliness of the mold refractories and mating materials involved in casting, and the cleanliness of the molten steel itself. be.

According to experiments, it has been found that the higher the injection speed of the melt 1ij 14, the lower the probability that the nonmetallic inclusions 3 will be trapped on the surface of the laminated material 1. Therefore, if the vortex flow of the molten steel 4 on the surface of the laminated material 1 is made uniform at high speed, the above-mentioned trap will be eliminated and a clean interface will be obtained. In this regard, increasing the diameter of the outlet 2 and increasing the injection speed will produce better results, but this is only possible when the laminated material 1 is small, and if the material is wide, an inclusion layer will form at the edges.

Therefore, the inventors of the present invention dealt with the problem by arranging a plurality of hot water outlets for the wide material. As a result, the flow of the molten steel 4 along the surface of the laminated material 1 is equalized, and the adhesion of inclusions to the above-mentioned wide material edge portion 1e can be suppressed.

FIG. 3 is a diagram showing the influence of the hot water outlet 2 and the width of the mating material on the interfacial adhesion, and shows the criticality where the fluctuation of the scene becomes large, leading to oxidation of the molten steel and increasing the amount of inclusions in the base metal: 8.
At Ot/win or less, if the width of the laminated material exceeds 1400 mm, it is found that it is necessary to have two or more hot water outlet ports 2.

Of course, the number of the 20 hot water outlets affects the pouring speed as well as the width of the laminated material 10, so the number is determined taking this into consideration. Note that these relationships can be expressed by the following equation.

-W Here, W is the width of the laminated material (''), n is the number of hot water outlets, W is the injection rate at a single hot water hot water outlet (t/min), and K is a constant determined by n, which is 1500 when n-1.゜n=2
1900 when n=3, and 2300 when n=3.

(Example) An example will be described in which a 2N clad steel plate was cast using the casting apparatus shown in FIG. The mold 5 has inner dimensions of W (width) 1.7 m - L (length) 2.0 m - H (height) 1.2 m, and is installed on a bottom plate 6 with a bottom pouring casting lower. and inside it D (thickness) 100 m-W (width) 1.
A laminated material 1 made of low carbon steel and having a size of 5 m-L (length) 1.7 m was supported in a hollow manner via a support 8. The height H) of the support 8 was 60 mm, and a release agent was applied to the bottom plate side surface of the laminated material 1.

Next, structural steel is injected into the inner space of the mold 5 under various conditions shown in Table 1, and the laminated material 1 is poured into the mold, wl,
A steel ingot of 7m-L2.0m-Hl, Om was obtained, and then this steel ingot was bloomed to form a width of 1.75m-thickness of 250mm x lR.
After cooling, the four circumferences of the slab were cut and peeled to obtain a 2 m clad plate.

Ultrasonic flaw detection was performed on the obtained gland plate.

The results are also shown in Table 1. When a wide material was used, no defects at the interface or defects in the base material were observed in the method of the present invention.

(Effects of the Invention) As explained above, according to the present invention, even when manufacturing a clad ingot using wide-width laminated materials, there is no interface adhesion failure at the edges or inclusion defects in the base material, and the high Rud material can be obtained at a low yield.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a mold illustrating an example of casting according to the method of the present invention (multiple holes), Fig. 2 is a cross-sectional view of a horizontal clad ingot casting device, and Fig. 3 is an effect on interfacial adhesion. FIG. 4 is a graph showing the influence of the spout and the width of the mating material. FIG. 4 is a plan view of a mold illustrating an example of casting according to the conventional method (single mouth). 1... Laminated material 2... Bath outlet 3...
Inclusions 4... Molten steel 5... Mold
6... Bottom plate 7... Casting port 8.
...Support figure 1 figure 2 figure 3 figure 10 crystals (mm) figure 4

Claims (1)

[Claims] 1. Into the remaining casting space in the mold in which the cladding material is placed horizontally to the surface plate, pour the molten metal with a composition different from that of the cladding material through the hot water outlet set at a position away from the cladding material. A method for casting a clad ingot by pouring the molten metal into the casting injecting the molten metal from a plurality of inlets when casting a wide composite material. .