JPS5950953A - Production of mold for continuous casting - Google Patents

Abstract

PURPOSE:To form a durable surface having excellent heat resitance and wear resistance on the inside surface of a mold for continuous casting by placing a specific durable sheet material on the surface of a mold body constituting the mold for continuous casting and treating the mold by a hot isotropic pressurization method after evacuating the spacing between said surface and sheet material to provide tight sealing thereto. CONSTITUTION:An Ni or Ni alloy sheet or said sheet 2 formed with Cr plating layer further thereon is superposed on the surface of each of two sets of long and short cooling plates 1 made of a copper alloy constituting a mold for continuous casting. The outside boundary of both materials 1, 2 is airtightly welded by an electron beam or the like and the spacing between both moterials is evacuated to a vacuum state. The assembly is put in a hot isotropic pressurization furnace, and is pressed at 500-800 deg.C under 50-100 atm to adhere securely and tightly both materials 1, 2, whereby the plate material of the mold for continuous casting having excellent heat resistance and wear resistance is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a continuous casting mold having a heat-resistant, wear-resistant, etc. coating layer on its surface.

Continuous H casting molds are made of copper or copper alloy from the viewpoint of thermal conductivity.A coating layer of nickel and its alloys or stainless steel is attached to the inner surface of the mold to give it heat resistance and wear resistance. Furthermore, for the purpose of preventing adhesion of molten steel during the initial stage of casting, a layer is applied on top of the above-mentioned coating layer. This mold body made of copper or copper alloy has many holes for passing cooling water, except for those for very small piston/soto casting, and despite its complicated shape, it has a high strength. Currently, they are manufactured by machining from rolled or forged materials. In other words, cast materials often have cavities inside, making them less reliable. In addition, the surface coating layer attached to the inner surface of the mold body is applied by plating or thermal spraying, but when a uniform layer thickness is required, thermal spraying has poor adhesion, so the only way to process it is to use a piece of metal. It takes a long time.

The present invention provides a method for manufacturing a continuous casting mold that maintains sufficient strength even when a cast material is used as the mold body, and that allows the surface coating layer to adhere firmly regardless of its material or thickness. The gist of this is that the mold body with internal cooling water passage holes is made of copper or copper alloy casting,
GFJ type, in which a thin plate material that becomes a durable surface layer is installed on the surface of the mold body, and after an airtight vacuum treatment is performed between the thin plate material and the mold body, the entire body is subjected to hot isostatic pressure treatment. 3! Characterized by forming a durable surface layer on the surface of the main body!
It! This is a method for manufacturing a mold for continuous casting.

Note that the surface of the mold mainly refers to the inner surface that comes into contact with the molten metal during use, but in the case of a slab mold, there are two
In the case of the short side 8pI type, which is used in a form such that it is held between long side molds, ω becomes the sliding contact surface with the inner surface of the long piece.
Since the surface is also required to have wear resistance, a heat-resistant and wear-resistant surface layer is formed by the method of the present application.

In addition, the durable surface layer is a general term for the surface layer that improves the life of the mold and does not reduce the quality of the product slab. Possible materials include alloys with a chromium layer on their top surfaces, stainless steel, and other materials.

Furthermore, airtight vacuum treatment refers to evacuating the space between the thin plate material and the mold body to create a vacuum state, and airtightly sealing the outer circumference of the boundary.

The method of the present invention will be described in detail below with reference to the drawings.

First, a mold body (1) with the required cooling water passage holes (not shown) is formed by casting, and a durable thin plate material (2) is coated on the surface of the mold body (1).
) i#! (See Figure 1) 8 This thin plate material (2)
There may be one sheet or two or more sheets, and in the case of two or more sheets, if they are bonded in advance by means such as explosive bonding to form a plywood, subsequent work will be done more efficiently. In addition, as shown in Figure 2, there is a bond between the mold body (1), which is a cast product, and the thin plate material (2).
) may be considered, and in the case of B, the subsequent work will be more efficient if the thin plate (2) and the rolled material (3) are made of plywood in advance, as described above. After placing the thin plate material (2) on the mold body (1) J:, which is a cast product, the thin plate material (2) is degassed and the external boundary between the two is made airtight by a welding method such as an electronic beam 1 or welding. Thereafter, the mold is placed in a hot isostatic pressure treatment furnace and subjected to temperature and pressure, but during airtight treatment, it is ensured that no gap is created between the mold body (1) and the thin plate material (2). That is, when joining dissimilar metal objects by welding, a gap tends to occur near the weld, so for example, as shown in Fig. 3, first the auxiliary material (4) is joined to the side of the mold body (1) by the weld part a. Then, use the wide thin plate material (2) as an auxiliary material (
4) and the welded part may be joined by J-jointing.

The temperature and pressure conditions during hot isostatic pressure treatment vary depending on the thickness used and the surface m of the joint surface (although it varies depending on the mold body (1
) is made of copper or a prepared alloy, so if the crystal is too high, its mechanical strength will decrease, so it should be kept at a temperature of about 800°C at most. Therefore, the joint surfaces of both the mold body (1) and the thin plate material (2) should be made as smooth as possible, and the altitude should be kept at a constant temperature of 500 to 800℃.
The test is carried out under conditions of 0 to 100 atmospheres. In addition, when hot isostatic l [pressure treatment is applied, as shown in Figure 4, ceramic powder, plates, and other objects that are difficult to join or that are easy to separate even if joined (7
) Place the mold body (1) on which the thin plate material (2) is placed, facing each other, cover both sides with sealing material (6), weld the four corners, and use two molds at the same time, or use the method described in (2) in multiple stages. many f
Il! , 1 is also possible at the same time.

As mentioned above, according to the method of the present invention, +ffl is removed from the rolled material because it has cooling water passage holes and has a complicated shape.
The main body of the hook, which requires a lot of effort and time with +4 processing, can be easily produced as a cast product, but then it is possible to apply hot isostatic pressure treatment at high temperature and high pressure. This eliminates defects such as cavities inside the mold, making it sufficiently strong and reliable.Since there are cooling water passage holes in the mold body, cooling cannot be achieved using the crimping method, which goes beyond normal mechanical pressure. This is not suitable as the water passage hole will be crushed, but since we use the hot isostatic pressure treatment method in which pressure is applied from the entire circumference, the cooling water passage hole will not be crushed and the thin plate material and the mold body will be connected. This has the effect of easily forming a strong surface layer on the surface of the mold body (ζ) by diffusion bonding each other.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figures 1 and 2 are explanatory diagrams of the thin plate material placed on the mold body according to the method of the present invention, and Figure 3 is an example of airtight treatment of the mold body and the thin plate material. FIG. 4 is an explanatory diagram showing a state in which the same two molds are manufactured at the same time. Patent applicant: Kuroki Kogyo Co., Ltd.

Claims (1)

[Claims] ], a mold body having a cooling water passage hole inside is made of copper or copper alloy casting, a thin plate material to be a durable surface layer is placed on the surface of the mold body, and the thin plate material and the above-mentioned A method for producing a mold for continuous casting, characterized in that after performing an airtight vacuum treatment between the mold bodies, the entire body is subjected to hot isostatic pressure treatment to form a durable surface m1 layer on the surface of the mold body.