TWI647028B - Method for manufacturing cast slab - Google Patents

Abstract

A method of manufacturing a cast embryo. In this method, molten steel is supplied. Continuous casting process for molten steel. Performing the continuous casting process includes coagulating the molten steel to form a semi-solidified preform; and when the solidification rate at the center of the semi-solidified embryo is greater than or equal to about 0.7 and less than about 1.0, the semi-solid casting is performed by a single pair of rolls The embryo is subjected to a heavy pressing operation to produce a cast embryo. The operation under the weight reduction includes causing the compressive strain of the core of the semi-solidified embryo to be equal to or greater than about 0.049.

Description

Method for manufacturing cast embryo

The invention relates to a method for manufacturing a steel blank, and in particular to a method for eliminating shrinkage holes and microvoids in a core portion of a casting.

When making a continuous casting embryo, the continuous casting embryo will not be replenished by the molten steel after the solidification of the dendrite bridge or the secondary dendritic arm gap, but the shrinkage hole or the size is smaller than the shrinkage hole in the core. A small micropore, wherein the size of the microvoids is about 1 mm or less. In the subsequent use of this continuous casting embryo to make large-size bar steel or ultra-thick steel plate, the thickness of the finished product is large, and the rolling ratio of the continuous casting embryo is insufficient, so that the shrinkage hole and the micro-hole of the heart cannot be healed. This will deteriorate the fatigue life of large-size bars or cause cross-sectional defects in ultra-thick steel plates. Especially for the marine steel and ship plates with strict requirements for the low temperature impact toughness of the core of the continuous casting embryo, if the microvoids in the core of the continuous casting embryo cannot heal, the core tissue will be embrittled at low temperature, so The low-temperature impact toughness of the core of the ultra-thick steel plate is insufficient to meet the specifications of the product.

Traditionally, the improvement of the shrinkage or segregation of the core of the steel is mostly by soft reduction technology and electromagnetic stirring technology, such as strand electromagnetic stirring. S-EMS), in which the soft reduction technology is the mainstream technology, the equipment manufacturers of continuous casting machines also provide light reduction technology. The soft reduction process applies a reduction of 3mm to 6mm to the casting blank before solidification of the casting embryo to compensate for the volume shrinkage caused by the solidification shrinkage and temperature drop of the molten steel, so as to avoid the high core of the casting embryo. The concentration of molten steel solidifies to cause segregation and dendritic bridging to form shrinkage cavities. Because the solidification rate of the pressed position is low, and the amount of reduction is small, the segregation of the cast embryo can be controlled within Mannesmann class 1.0, and there is no shrinkage hole in the visual casting. . However, when the cast embryo is detected by X-ray, the presence of shrinkage cavities in the cast embryo can still be found. This is because the reduction of the traditional soft reduction process is small, mainly to compensate for the shrinkage of the casting embryo cooling and solidification metamorphosis, and can only achieve some improvement in the shrinkage cavity defect, but the size is smaller and more Dense microvoids do not have an improvement.

The second cold zone electromagnetic stirring technology uses electromagnetic force to stir the molten steel in the casting shell at the appropriate position of the casting channel, and brushes the dendritic tip in the molten steel to homogenize the temperature of the molten steel and utilize it. The crystal grains at the tip of the dendrite are used as seed crystals to generate an equiaxed crystal structure in the core, thereby eliminating segregation and shrinkage in the cast. Such a technique can also control the segregation in the cast embryo within Mannesmann 1.0, and visually there is no shrinkage hole in the cast. However, when the cast embryo is detected by X-ray, the presence of shrinkage cavities in the cast embryo can also be found.

For example, there is a method for manufacturing a continuous casting embryo when the solidification end solidification rate (fs) of the continuous casting embryo is between 0.05 and 0.2 to 0.3 to 0.6, and at least two sets of roller pairs are not completely used. The solidified continuous casting embryo is subjected to a pressing operation, and the pressing operation is performed at a reduction ratio of 5 mm/m to 10 mm/m, or 3mm/m to 30mm/m. Moreover, it is used with a mould electromagnetic stirrer (M-EMS) or a two-cold electromagnetic stirrer, and a chamfering die, and the superheat degree is controlled to be below 20 °C.

However, the reduction of the pressing operation of this technology causes the impedance of the continuous casting embryo to increase, so it is necessary to increase the strength of the roller set machine to avoid deformation of the machine, which increases the equipment cost and equipment. Abrasion. Secondly, in order to reduce the impedance of the continuous casting embryo, this technique must be used in conjunction with the chamfering mold, thus increasing the use limit and technical threshold. Furthermore, the roller caster of the roller set used must have a dynamic soft reduction system to meet the variable and dynamic casting cone requirements, which also increases the specification limits of the continuous casting machine.

Another method for manufacturing a continuous casting steel plate is to provide a pressing roller at the exit of the casting machine of the continuous casting machine to press the steel blank to utilize the outer soft and soft characteristics of the steel embryo to make the shrinkage hole of the steel embryo core The microvoids heal. However, the steel blank has solidified at the exit of the casting channel and the temperature has decreased. Therefore, the force required to depress the casting embryo at this time is quite large, which causes the equipment of the continuous casting machine to be mega-sized, resulting in an increase in equipment construction and maintenance costs. In addition, since the temperature gradient of the steel blank has also decreased at this time, the effect of the amount of compression of the steel embryo concentrated on the core portion is poor, and therefore the steel embryo requires a relatively large reduction.

There is also a continuous casting method which deliberately causes the cast embryo to form a convex belly during the process, and before the solidification rate of the core portion of the cast embryo is 0.8-1, the central portion of the cast embryo is depressed by 3 mm~ 15mm, thereby eliminating the shrinkage holes and micro-holes in the core of the casting. In this patented technology, the use of the deliberate embossing technique can reduce the impedance of the casting embryo, and at the same time, it has a function of adjusting the shape of the liquid core. However, since this technology must be used in conjunction with the use of deliberate bulging processes, The continuous casting machine needs to have a dynamic soft reduction function to meet the variable and dynamic casting cone setting, which also increases the specification limits of the continuous casting machine.

There is also a very thick steel plate manufacturing method in which a continuous forging device is added to the continuous casting machine to produce a strong compression effect on the casting embryo, thereby compressing the shrinkage hole and the microvoiding hole of the core portion of the steel embryo. To achieve the purpose of improving the quality of steel. However, the operation and maintenance of the online forging machine equipment added by this technology is more complicated than that of the original continuous casting machine, resulting in a substantial increase in labor and equipment costs. In addition, the reduction of the steel embryo by this technique is about half of the thickness of the original embryo, which will seriously affect the embryo thickness of the steel embryo.

However, there is an ultra-thick steel plate manufacturing method which utilizes the powerful compression effect of the offline forging process on the steel embryo to heal the shrinkage hole and the micro-hole of the steel embryo core to improve the quality of the steel plate. However, this technique also has to be additionally added to the forging process, thus resulting in an increase in equipment and production costs.

Accordingly, it is an object of the present invention to provide a method for producing a continuous casting embryo which has a central solid fraction equal to or greater than about 0.7 before the semi-solidified embryo is about to solidify, for example, a semi-solidified embryo. Less than about 1.0, the single-roller semi-solidified casting embryo is subjected to a heavy pressing operation to concentrate the compression effect on the core of the semi-solidified casting embryo by utilizing the semi-solidified outer hard and soft inner characteristics, thereby effectively eliminating the casting embryo The shrinkage hole and the micro-hole of the core portion can further increase the density of the core portion of the cast embryo.

Another object of the present invention is to provide a method for manufacturing a continuous casting embryo, which is simple in equipment and simple in operation, so that it can be taken care of In the case of force and equipment cost, it is easy to eliminate the shrinkage holes and micro-holes in the core of the casting embryo to meet the specifications of the product.

According to the above object of the present invention, a method of manufacturing a continuous casting embryo is proposed. In this method, molten steel is supplied. Continuous casting process for molten steel. Performing the continuous casting process includes coagulating the molten steel to form a semi-solidified preform; and when the solidification rate at the center of the semi-solidified embryo is greater than or equal to about 0.7 and less than about 1.0, the semi-solid casting is performed by a single pair of rolls The embryo is subjected to a heavy pressing operation to produce a cast embryo. The operation under the weight reduction includes causing the compressive strain of the core of the semi-solidified embryo to be equal to or greater than about 0.049.

In accordance with an embodiment of the present invention, the single pair of rollers is comprised of a pinch roller and a fixed roller, and the heavy press operation includes applying a reduction to the semi-solidified preform using the pinch roller.

According to an embodiment of the invention, the reduction is from about 4 mm to about 20 mm.

According to an embodiment of the invention, the above-mentioned pressure roller is a roller, and the fixed roller is a lower roller.

According to an embodiment of the invention, the above-mentioned pressure roller is a convex roller.

According to an embodiment of the invention, the semi-solidified preform comprises two three-pronged points, and the width of the surface of the pressure roller of the pressure roller is greater than the distance between the two three-point points.

According to an embodiment of the invention, the above-mentioned pressure roller is a flat roller.

According to an embodiment of the invention, the fixed roller is a flat roller.

According to an embodiment of the invention, the single pair of rollers is a pair of rollers in a roller set, and the pressure roller is a drive wheel.

In accordance with an embodiment of the present invention, the above-described operation under heavy pressure includes a total area of unit embryo width of less than 20% of the bottom wave intensity of the ultrasonic portion of the core of the casting embryo being less than about 2 mm ² /m.

In accordance with an embodiment of the present invention, the cross-section of the semi-solidified preform has a width of from about 1000 mm to about 3000 mm, and the cross-section has a thickness of from about 100 mm to about 400 mm.

100‧‧‧ steps

110‧‧‧Steps

112‧‧‧Steps

114‧‧‧Steps

200‧‧‧Press roller

202‧‧‧Pressure roller surface

210‧‧‧Fixed roller

220‧‧‧ Semi-solidified embryo

220c‧‧‧ cross section

220c’‧‧‧Narrow side

220c”‧‧‧Narrow side

222‧‧‧ upper surface

224‧‧‧ lower surface

226‧‧‧Three-pronged point

228‧‧‧Three-pronged

230‧‧‧Continuous casting direction

240‧‧‧Virtual line

242‧‧‧Virtual line

244‧‧‧Virtual line

246‧‧‧Virtual line

D‧‧‧Distance

W‧‧‧Width

θ 1‧‧‧ angle

θ 2‧‧‧ angle

θ 3‧‧‧ angle

θ 4‧‧‧ angle

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; A flow chart of the method; [Fig. 2] is a perspective view showing a roller device when performing a heavy pressing operation according to an embodiment of the present invention; [Fig. 3] shows a casting embryo according to an embodiment of the present invention. A comparative diagram of the area sum of the unit embryo width of the base of the comparative example of the casting embryo under the immersion ultrasonic detection of less than 20%; [Fig. 4] shows the flat pressure according to an embodiment of the present invention. A comparison diagram of the pressing force of the roller and the convex roller; and FIG. 5 is a schematic diagram showing the comparison of the internal compression amount of the flat and the convex roller to the casting embryo according to an embodiment of the present invention. .

Please refer to FIG. 1 , which is a flow chart of a method for manufacturing a casting blank according to an embodiment of the present invention. In the present embodiment, step 100 may be performed first to produce a molten steel when manufacturing the foundry. The molten steel is generally an alloy steel liquid. Next, step 110 is performed to perform a continuous casting process on the molten steel to convert the molten steel into a cast embryo. In some embodiments, in the continuous casting process of the molten steel, step 112 may be performed first to perform a solidification operation on the molten steel to form a semi-solidified embryo. The surface of the semi-solidified embryo has solidified to form a crust, and the molten steel of the core of the semi-solidified embryo has not yet solidified. In the solidification operation of the molten steel, the molten steel is first injected into the mold, and the molten steel is cooled and solidified to form a semi-solidified cast embryo having a solid outer shell and a molten steel which has not yet solidified.

Next, the semi-solidified embryo can be drawn into the casting path and transported forward by the roller. Semi-solidified embryos will decrease in temperature during transport. In some examples, in the continuous casting process of molten steel, when the center solidification rate of the semi-solidified casting embryo is greater than or equal to about 0.7 and less than about 1.0, step 114 may be performed to perform heavy pressing operation on the semi-solidified casting embryo. And the embryo is made.

Referring to FIG. 2, it is a perspective view of a roller device when performing a heavy pressing operation according to an embodiment of the present invention. In the present embodiment, when performing the heavy pressing operation, a single pair of rollers may be provided first, wherein the pair of rollers may be composed of one roller roller 200 and one fixed roller 210. In some examples, the semi-solidified preform 220 is conveyed between the pinch roller 200 and the fixed roller 210, wherein the pinch roller 200 is located above the upper surface 222 of the semi-solidified preform 220, and the fixed roller 210 is located in the semi-solid casting The bottom surface 224 of the embryo 220 is under The semi-solidified cast embryo 220 is supported. In such an example, the pinch roller 200 may also be referred to as an upper roller, and the stationary roller 210 may be referred to as a lower roller. In some exemplary embodiments, the cross-section of the semi-solidified preform has a width of from about 1000 mm to about 3000 mm, and the cross-section of the semi-solidified preform has a thickness of from about 100 mm to about 400 mm.

In some specific examples, the fixed roller 210 can also be disposed on the upper surface 222 of the semi-solidified preform 220, and the roller 200 can be disposed below the lower surface 224 of the semi-solidified preform 220. In such an example, due to the influence of gravity, the casting machine must use more force to lift the boosting roller 200 to squeeze the semi-solidified casting preform 220. Such a setting would be more expensive than the design of the upper roller by the pressing roller 200. can.

When the semi-solidified casting 220 is subjected to a heavy pressing operation by the pressing roller 200 and the fixed roller 210, the fixed roller 210 is fixed, and the pressing roller 200 is fixed to the fixed roller on the other side of the semi-solidified casting 220. 210 moves up and down. In addition, the positions of the pressing roller 200 and the fixed roller 210 correspond to each other, so that when the pressing roller 200 presses the semi-solidified casting preform 220, the semi-solidified casting preform 220 can be squeezed by the pressing roller 200 and the fixed roller 210. Pressure. In the example where the press roll 200 is the upper roll, when the operation is performed under heavy pressure, the press roll 200 is moved downward toward the semi-solidified preform 220, and from the upper surface 222 of the semi-solidified cast iron 220. The semi-solidified casting embryo 220 applies a reduction amount to extrude the semi-solidified casting embryo 220. When the pinch roller 200 presses the semi-solidified casting preform 220, the molten molten steel in the core portion of the semi-solidified casting preform 220 can be extruded in a direction opposite to the continuous casting direction 230 of the semi-solidified casting preform 220, thereby being squeezed. The molten steel will solidify and combine The upper and lower crusts of the semi-solidified embryo 220 can eliminate the shrinkage cavities and the microvoids in the core portion of the prepared embryo.

In some examples, the weighting operation may cause the compressive strain of the core of the semi-solidified embryo to be equal to or greater than about 0.049. In some exemplary examples, the reduction roll of the pinch roller 200 to the semi-solidified preform 220 may be from about 4 mm to about 20 mm. When the pressing amount of the pressing roller 200 is less than 4 mm, such a reduction amount may be too small to effectively heal the micropores of the casting embryo. On the other hand, when the pressing amount of the pressing roller 200 is more than 20 mm, although the molten molten steel in the core portion of the semi-solidified casting embryo can be completely extruded and healed the shrinkage hole and the microvoiding hole of the casting embryo, such pressure The amount may be too large to cause the casting embryo to be too thin, and at the same time, the load of the operation under heavy pressure is increased, and the casting machine equipment is enlarged, resulting in a substantial increase in equipment cost.

In some examples, the pinch roller 200 is a male roller and the stationary roller 210 is a flat roller. In other examples, the pinch roller 200 is a flat roller and the stationary roller 210 is also a flat roller. When the pressing roller 200 is a convex roller, since the width of the pressing roller 220 contacting the semi-solidified casting preform 220 is narrowed, and the high-strength crust of the narrow side of the semi-solidified casting embryo 220 can be avoided, the pressure can be lowered. The pressing force of the roller 200 can further extend the life of the casting machine. Further, the platen roller 200 and the fixed roller 210 may be a separate pair of rollers. However, the pressing roller 200 and the fixed roller 210 may also be a pair of rollers in a roller group, and the pressing roller 200 is a movable driving wheel.

Referring again to FIG. 2, the semi-solidified preform 220 includes two trifurcation points 226 and 228. The trigeminal point 226 is the two corners of the narrow side 220c' of the left side of the cross section 220c of the semi-solidified casting 220 which is perpendicular to the continuous casting direction 230. Do not draw a virtual line 240 and 242, the intersection of the two virtual lines 240 and 242 is a three-point 226, wherein the two virtual lines 240 and 242 and the narrow side 220c' respectively have an angle θ 1 and θ 2 . The included angles θ 1 and θ 2 may be angles of about 45 degrees. Similarly, the three-point 228 means that the two corners of the narrow side 220c" on the right side of the cross section 220c of the semi-solidified casting 220 respectively depict a virtual line 244 and 246, and the intersection of the two virtual lines 244 and 246 is The trigeminal point 228, wherein the two virtual lines 244 and 246 and the narrow side 220c" respectively have an angle θ 3 and θ 4 . The included angles θ 3 and θ 4 may be angles of about 45 degrees. The formation of the trigeminal points 226 and 228 is due to the macroscopic tissue boundary generated by the outer and inner cooling of the molten steel surfaces of the wide and narrow faces due to the solidification operation of the molten steel. There is a distance D between the trifurcation points 226 and 228, wherein the distance D between the two trifurcation points 226 and 228 can be defined as the embryo width of the semi-solidified casting embryo 220, so the embryo width is not the actual semi-solidified casting embryo 220. Embryo width.

In the example where the pressure roller 200 is a convex roller, the pressure roller 200 has a raised pressure roller surface 202. When the semi-solidified preform 220 passes between the pressure roller 200 and the fixed roller 210, the pressure roller The weight of the 200-half solidified casting embryo 220 causes the molten steel of the core of the semi-solidified casting 220 to be extruded in the opposite direction to the continuous casting direction 230, whereby the semi-solidified casting 220 can be condensed. The shell is combined with the lower crust. If the width W of the pressing roller surface 202 of the pressing roller 200 is smaller than the distance D between the two trifurcation points 226 and 228, part of the molten steel in the core portion of the semi-solidified casting preform 220 is not extruded. As a result, there may be too much molten steel between the two trigeminal points 226 and 228, and segregation, shrinkage, and/or microvoiding are likely to occur. Thus, the width W of the press roll surface 202 is greater than the distance D between the two triple points 226 and 228. In some In the exemplary embodiment, the difference between the width W of the press roll surface 202 and the distance D between the three-pronged points 226 and 228 is equally divided at both ends of the press roll 200 to provide a more uniform property to the interior of the cast.

In the present embodiment, the semi-solidified casting 220 can be subjected to a heavy pressing operation by using a single pair of rollers, or the single pair of rollers in the original roller module of the casting machine can be pressed against the semi-solidified casting 220. The force can eliminate the segregation, shrinkage, and micro-holes in the core of the casting embryo without the need of a dynamic soft reduction system. Therefore, the present embodiment can eliminate the use of the dynamic soft reduction system. In addition, the strong squeezing action of the heavy pressing operation is better for improving the segregation of the core of the casting embryo than the conventional soft reduction technique.

Please refer to FIG. 3 , which is a comparison of the area sum of the unit embryo width of the casting embryo with a bottom wave intensity of less than 20% in the immersion ultrasonic detection of the casting embryo according to the embodiment of the present invention. schematic diagram. As can be seen from FIG. 3, the area of the bottom of the plurality of castings in the embodiment of the present invention having a bottom wave intensity of less than 20% under the immersion ultrasonic detection is much lower than that of the casting of the comparative example.

In some exemplary examples, the submerged ultrasonic detection of the casts of the examples and the comparative examples was carried out using a 15 MHz probe. When the probe frequency is set to 15MHz, the detection depth range can be increased to more than 10mm, and the resolution can be balanced. In addition, the moving pitch of the ultrasonic probe can be set to 0.3 mm, so that a defect of 0.09 mm can be detected at the minimum. For the test piece for testing, a sulfur-printed or pickled test piece which is routinely sampled by a steel mill can be used. Before the test, both sides of the cast embryo test piece are flattened, and the thickness of the cast test piece is controlled to 20±0.5mm, and the surface processing precision of the cast embryo is controlled at the center line average roughness Ra=1.6. . When testing, the entire cross section of the casting embryo needs to be analyzed. Further, the focus of the ultrasonic wave is set at the intermediate position of the thickness of the test piece, that is, about 10 mm from the surface of the test piece, the bottom wave gain is set to 68 db, and the ultrasonic effective detection depth is about 10 mm. The area of the ultrasonic wave bottom echo intensity of the cross section of the entire casting embryo is less than 20%, and divided by the embryo width of each casting embryo, the super-period of each casting embryo is obtained. The sum of sound wave defect areas, the unit is mm ² /m. Among them, the embryo width of the cast embryo refers to the theoretical distance between the two trigeminal points in the giant structure of the cast embryo, not the actual width of the cast embryo or the set embryo width.

In some examples, the weighting operation of the single pair of rollers on the semi-solidified embryos can result in a total area of the unitary embryo width of less than 20% of the ultrasonic bottom wave intensity of the core of the prepared embryo. About 3mm ² /m. In some preferred embodiments, the operation under heavy pressure may result in a total area of the unitary embryo width of less than 20% of the ultrasonic bottom wave intensity of the core of the cast embryo being less than about 2 mm ² /m.

Please refer to FIG. 4 and FIG. 5 , wherein FIG. 4 is a schematic diagram showing a comparison of the pressing force of the flat roller and the convex roller according to an embodiment of the present invention, and FIG. 5 illustrates an implementation according to the present invention. A schematic diagram comparing the internal compression of the casting blank of the flat roller and the convex roller. In some exemplary examples, as shown in FIG. 4, when the embryo width of the semi-solidified embryo is 1880 mm, and the pressing amount of the pressing roller is also 10 mm, the pressing force of the convex roller is lower than that of the flat roller. The round is 12% lower. However, as shown in Fig. 5, the compression effect of the flat roller and the convex roller on the core of the semi-solidified preform is similar. It can be seen from the above that the present embodiment can achieve a similar effect by using a flat roller or a convex roller to perform a heavy pressing operation on the semi-solidified casting. However, when a convex roller is used as the roller, the pressure is applied. The roller can more effectively squeeze the core of the semi-solidified casting embryo, thereby reducing the energy consumption of the operation under heavy pressure, thereby reducing the process cost.

It can be seen from the above embodiments that one of the advantages of the present invention is that the method for manufacturing the continuous casting embryo of the present invention is such that the solidification rate of the semi-solidified embryo is about equal to or greater than about 0.7 and less than that before the semi-solidified embryo is about to solidify. At about 1.0, the single-roller semi-solidified casting embryo is subjected to a heavy pressing operation to concentrate the compression effect on the core of the semi-solidified casting embryo by utilizing the characteristics of the semi-solidified casting outer hard inner softness, thereby effectively eliminating the casting embryo The shrinkage hole and the micro-hole of the heart can further increase the density of the core of the cast embryo.

It can be seen from the above embodiments that another advantage of the present invention is that the apparatus used in the method for manufacturing the continuous casting embryo of the present invention is simple and easy to operate, so that the casting can be easily achieved while taking into consideration the cost of manpower and equipment. The purpose of shrinkage holes and micro-holes in the heart of the embryo meets the specifications of the product.

While the present invention has been described above by way of example, it is not intended to be construed as a limitation of the scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

Claims (10)

A method for manufacturing a casting preform, comprising: providing a molten steel; and performing a continuous casting process on the molten steel, wherein performing the continuous casting process comprises: performing a solidification operation on the molten steel to form a semi-solidified cast embryo; When the solidification rate of one of the semi-solidified casting embryos is greater than or equal to 0.7 and less than 1.0, the semi-solidified casting embryo is subjected to a heavy pressing operation by a single pair of rollers to obtain the casting embryo, wherein the weighting operation is performed The compressive strain of one of the cores of the semi-solidified embryo is substantially equal to or greater than 0.049. The method for manufacturing a cast bristles according to claim 1, wherein the single pair of roller trains is composed of a press roller and a fixed roller, and the heavy pressure operation comprises using the pressure roller to solidify the semi-coagulation. The casting embryo exerts a reduction. The method for producing a cast embryo according to claim 2, wherein the reduction is substantially 4 mm to 20 mm. The method for manufacturing a cast embryo according to claim 2, wherein the press roller is an upper roller, and the fixed roller is a lower roller. The method for manufacturing a cast embryo according to claim 2, wherein the press roller is a convex roller. The method for manufacturing a cast embryo according to claim 5, wherein the semi-solidified embryo comprises two three-pronged points, and one of the surfaces of one of the press rolls has a width greater than a distance between the three-pronged points. The method for manufacturing a cast embryo according to claim 2, wherein the press roller and the fixed roller are flat rollers. The method for manufacturing a cast embryo according to claim 2, wherein the single pair of rollers is a pair of rollers in a roller set, and the press roller is a drive wheel. The method for manufacturing a cast embryo according to claim 1, wherein the operation under the heavy pressure comprises a total area of the unit width of one of the ultrasonic waves of one of the cores of the cast embryo being less than 20%. Less than 2mm ² /m. The method for producing a cast embryo according to claim 1, wherein a width of a cross section of the semi-solidified embryo is substantially 1000 mm to 3000 mm, and the thickness of the cross section is substantially 100 mm to 400 mm.