RU2364466C1 - Ingot casting mould - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy. There are grooves arranged on the outside of the casting mould whose wall thickness is equal to 0.4÷0.55 of its inner cavity radius. The groove width is equal to 0.23÷0.27 of the inner cavity radius. The groove depth is equal to 0.05÷0.15 of the wall lower section thickness. Distance from the lower butt-end to the groove is equal to 0.23÷0.27 of the inner cavity radius. On the casting mould grooved section surface a metal casing is mounted whose width and thickness are equal to 0.3÷0.35 of the inner cavity radius and 0.1÷0.15 of the mould wall thickness accordingly.

EFFECT: provision for elimination of off-centre segregation due to compensation for the chilling effect the tray has on metal crystalisation in the ingot lower part.

2 cl, 2 dwg, 1 ex

Description

FIELD OF THE INVENTION

The invention relates to ferrous metallurgy, in particular to the production of steel ingots.

It can be used in metallurgical and engineering plants for casting molten metal.

State of the art

A known mold for casting an ingot broadened downward and a method for its production (patent RU No. 2198763, class 7 B22D 7/06, bull. No. 5, 02/20/2003), the wall thickness of which in each cross section in height is 0.4 -0.55 radius of its internal cavity.

The mold provides the conditions for “horizontal crystallization” of molten metal and the production of an ingot, the macrostructure of which is free from off-axis segregation zones.

However, during the crystallization of high alloy steels and alloys that are sensitive to the heat sink speed in different directions, the conditions of “horizontal crystallization” in the lower part of the ingot may deteriorate due to heat removal in the vertical, axial, direction from the cooling effect of the pallet. In this part of the ingot, a deterioration in the quality of the metal is possible.

Thus, the existing device needs to be improved in order to be able to obtain an ingot free of off-axis segregation and with high quality metal over the entire height of the ingot in the case of casting of high alloy steels and alloys.

Disclosure of invention

The objective of the present invention is to provide a mold for casting an ingot, which provides a high quality ingot: free from off-axis segregation and with high quality metal over the entire height of the ingot, in the case of casting of high alloy steels and alloys.

This problem is solved in that a mold for casting an ingot having a wall thickness in each cross section of a height of 0.4 ÷ 0.55 of the radius of its inner cavity has a groove on the outer surface with a width of up to 0.23 ÷ 0.27 of the radius of the inner cavity , a depth of 0.05 ÷ 0.15 of the wall thickness in the lower part of the mold, at a distance from the lower end to 0.23 ÷ 0.27 of the radius of the internal cavity of the mold. This makes it possible to compensate for the cooling effect of the pallet and to achieve high quality metal throughout the entire height of the ingot.

The optimality of the claimed range of geometric dimensions of the groove is confirmed by calculation using a mathematical model developed by the applicant. When reducing the mold parameters below the stated limits, the conditions of "horizontal crystallization" are violated towards the pallet; with increasing parameters of the mold above the stated limits, the conditions of "horizontal crystallization" are violated towards the upper part of the ingot.

To enhance the compensation effect of the cooling effect of the pallet on the crystallization of the metal in the lower part of the ingot, it is advisable to install a metal casing with a width equal to 0.3 ÷ 0.35 of the radius of the inner cavity and a thickness of 0.1 ÷ 0.15 of the wall thickness on the machined part of the mold.

This technique makes it possible to improve the quality of the ingot of high alloy steels and alloys over its entire height.

In the future, the patented ingot mold for casting an ingot is illustrated with a specific example of its implementation and is illustrated by the accompanying drawings, which schematically depict the design of the ingot.

Brief Description of the Drawings

Figure 1 schematically depicts a mold with a groove in its lower part according to the invention;

Figure 2 schematically depicts a mold with a groove in its lower part and an installed metal casing on a machined section according to the invention.

The implementation of the invention

The mold is made with an internal cavity 1 (Figure 1) along the radius of the ingot R, taking into account thermal shrinkage during crystallization and cooling of the metal, with a thickness Δ of wall 2 equal to 0.40 ÷ 0.55 of radius R, and on its surface 3, in the lower part, at a distance H from the lower end 5, equal to 0.25 from the radius R, a groove 4 is made of a width P equal to 0.25 from the radius R, to a depth G equal to 0.1 from the thickness Δ of the wall 2.

The width P of the groove 4, equal to 0.25 of the radius R, its location at a distance H equal to 0.25 of the radius R, and the depth G of the groove 4, which is equal to 0.1 from the thickness Δ of the wall 2, makes it possible to maintain the conditions of "horizontal crystallization" over the entire height of the ingot. The reduction of heat sink from the mold 2 in its lower part and the compensation of the cooling effect of the pallet on the crystallization of the metal in the lower part of the mold is additionally ensured by installing on the machined section 4 of the metal casing 6 (Figure 2) a width W equal to 0.3 of the radius R of the inner cavity 1, and a thickness T equal to 0.1 of the thickness Δ of the wall 2. This technique makes it possible to obtain a thermal gap between the groove 4 and the casing 6 in the lower part of the mold, to additionally compensate for the cooling effect of the pallet on the crystallization of the metal and in the lower part of the ingot, additionally guarantee the preservation of the conditions of "horizontal crystallization" over the entire height of the ingot.

The optimality of the declared geometric dimensions of the casing is confirmed by calculation using a mathematical model developed by the applicant. When reducing the parameters of the casing below the stated limits, the conditions of "horizontal crystallization" are violated towards the upper part of the ingot; with increasing parameters of the casing above the stated limits, the conditions of "horizontal crystallization" are violated towards the pallet.

Example

To obtain an ingot with a height of 1000 mm and a diameter of 200 mm, a mold with a wall thickness of 45 mm at the top and 55 mm at the bottom was made of 20X2H4A steel. In the lower part of the mold, at a distance of 25 mm from the lower end, a groove was made with a width of 25 mm and a depth of 5 mm.

After casting the steel during crystallization of the ingot in the mold of the claimed design, it was thermographed. The thermal state of the surface of the mold showed that the conditions for "horizontal crystallization" were created for the ingot along the entire height of its body (excluding a profitable extension). Further study of the macrostructure of the ingot showed that along its entire height there are no off-axis and axial segregation zones, the metal is dense. However, at the lower end of the ingot, the cast structure differs from the metal structure in the rest of the ingot.

When casting the second ingot from the same steel and at the same temperature and speed conditions, a steel casing 30 mm wide and 5 mm thick was installed on the groove in the lower part of the mold.

After casting steel into the mold of the claimed design with a casing in the lower part, it was thermographed, which showed that the conditions of "horizontal crystallization" were provided along the entire height of the mold. Further study of the macrostructure of the ingot confirmed its high quality and uniformity of the cast structure throughout the volume.

Using the inventive mold for casting an ingot allows us to ensure the conditions of "horizontal crystallization", to compensate for the cooling effect of the pallet on the crystallization of the metal in the lower part of the ingot during casting of high alloy steel 20X2H4A and on this basis to improve the quality of the ingot.

Thus, the claimed mold for casting an ingot makes it possible to obtain an ingot of high alloy steel, free from off-axis and axial segregation, with a uniform cast structure throughout the volume.

It is quite obvious that, using the claimed mold for casting an ingot, it is possible to minimize the heterogeneity of the metal over the volume of the ingot.

The claimed mold for casting an ingot is characterized by the simplicity of the design and its manufacture will not cause difficulties.

It is obvious that the use of the claimed mold for casting an ingot in the steel shop of a metallurgical plant will not require additional equipment or special equipment.

The claimed design of the mold for casting an ingot is suitable for producing ingots of any height to diameter ratio found in the metallurgical industry and for ingots of round or polyhedral cross section.

Claims (2)

1. Mold for casting an ingot, the wall thickness of which in each cross section in height is 0.4 ÷ 0.55 of the radius of the inner cavity, characterized in that a groove is made on the outer surface with a width equal to 0.23 ÷ 0.27 of the radius of the inner cavity , a depth equal to 0.05 ÷ 0.15 of the wall thickness in the lower part of the mold and at a distance from the lower end equal to 0.23 ÷ 0.27 of the radius of the internal cavity. 2. The mold according to claim 1, characterized in that it is equipped with a metal casing installed on the machined section of the mold and having a width equal to 0.3 ÷ 0.35 of the radius of the inner cavity and a thickness of 0.1 ÷ 0.15 of thickness the walls.

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