JPS58167058A - Casting mold for continuous casting of iron and steel - Google Patents

Abstract

PURPOSE:To improve abrasion resistance by forming an Ni-W alloy layer cont. a specific amt. of W on the surface of a casting mold to be charged thereon with molten steel. CONSTITUTION:In a casting mold made of Cu or a Cu alloy for continuous casting of iron and steel, an Ni-W alloy layer contg. 20-40wt% (more particularly 36-39wt%) W is formed on the surface of the casting mold to be charged thereon with molten steel. This Ni-W alloy layer has about 1,500 deg.C m.p., is highly resistant to heat, maintains high hardness and has excellent adhesive strength to Cu and a Cu alloy. Thus, the life of the mold is prolonged remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cast iron 11 for continuous casting of steel, such as ordinary steel, high carbon steel, steelless steel, special alloy steel, and the like.

Continuous casting molds usually use steel or steel alloys with good thermal conductivity as their base material. However, when using copper or copper alloy as is, the molten steel injection surface is severely damaged by the high temperature molten steel, and the life of the mold is reached within a short period of time, so it is not necessary to form a protective coating layer on the molten steel injection surface. It is being done. There are a wide variety of protective coating layers currently being implemented and proposed, but from the viewpoint of hardness and heat resistance, xi-p
Alloy-based METS+ layers are widely used. However, this Ni--P alloy layer (hereinafter simply referred to as KNip) has the disadvantage that molten steel droplets (slush) tend to adhere to q# in the initial stage of use. That is, since the adhered and solidified slush has the risk of causing so-called cohesive breakout, it is practical to add 111CCr on the NiP.
Furthermore, NiP has a lower melting point than NiK, which poses some problems (
melting point at the eutectic point of Pll-880°C). Since the mold is sufficiently water-cooled during use, its surface temperature is normally maintained at 600° C. or lower, and there is no problem when the mold is operated normally. However, if the temperature of the molten steel injection surface rises close to the melting point of NiP due to cracks in the cooling water flow path, fluctuations in water pressure, operational errors, etc., breakouts may occur due to heat loss on the mold surface. The occurrence of serious accidents is also expected.

As a result of various studies in view of the above-mentioned current situation, the present inventor has discovered that the N1-jF' alloy containing a specific amount of W has extremely excellent properties as a protective coating layer for continuous casting molds made of copper and prepared alloys. After further experiments and research, K finally completed the present invention. That is, the present invention is characterized in that, in a mold for continuous casting of steel made of copper or prepared alloy, ten layers of N1-W alloy containing 20 to 40% Kr by weight are formed on the molten steel injection surface of the mold. The present invention provides a mold for continuous steel casting.

The N1-F alloy layer, which is the protective coating layer of the mold of the present invention, has a melting point of approximately 1500°C and has excellent heat resistance, maintains high hardness even at high temperatures, and has excellent adhesion to copper and copper alloys. . Therefore, in a normal usage method in which a solid lubricant such as vitreous butter is interposed between the mold and molten steel so that it flows in accordance with the flow of molten steel, its lifespan is shorter than that of NLP coated casting 11. Tsutacho is made.

In the present invention, W in the Ni-7 alloy is 20 to 40
Weight-1 is preferably 56 to 39 weight-high. When the content of r exceeds 40% by weight, it becomes difficult to form an alloy middle layer, while when the content of r is less than 20% by weight, the wear resistance is insufficient.

The thickness of the N1-IP' alloy is usually 20 to 500.
It is about μ level, and more preferably about 30 to 100 insults. N1-F alloy middle layer thickness is 20jllll
If it is less than l1, the surface protection effect will be fully exhibited, 50
If it exceeds 0μ, there is a tendency for cooling failure due to insufficient heat removal.

The N1-If' alloy layer in the mold of the present invention is formed by performing pretreatment and meth operation according to conventional methods. In other words, Copper . As a series of these processes,
Examples include alkaline degreasing → water washing → electrolytic degreasing → water washing → acid treatment → water washing. In this series of treatments, alkaline degreasing is performed, for example, in a degreasing bath containing 0.5 to 301/l of a surfactant (about pH I O to 14), and a Schiff mold at a temperature of 20 to 80°C. After rinsing the mold, the mold is immersed for 5 to 60 minutes in the same bath as above.

Electrolytic degreasing is carried out under conditions of a cathode current density of about 1"30 A/rLvn", a temperature of about 30 to 70 DEG C., and a time of about 1 to 30 minutes. After further washing the mold with water, add hydrochloric acid, sulfuric acid, etc.
0 chronic aqueous solution at room temperature! -The conditions for dipping for about 10 minutes can be almost the same as those for normal N1-F medicine.
For example, in a met+ bath containing nickel sulfate 20f/11 sodium tasixstate 501/l, citric acid 661/l and a small amount of cationic surfactant pH 8.6~
9.0% temperature 50~60℃ and cathode current 5~1OA/d
#i60~8611111 and 740-20 should be electrolyzed under the following conditions.
A heavy Ni-7 alloy metal layer is formed. In the area where the N1-f' alloy middle layer of the present invention is formed,
It goes without saying that the bath composition can be changed as appropriate.

After washing and drying the mold with the middle layer formed, the mold has a mass +
The coated coating material is removed, and the mold of the present invention is thus obtained.

In addition, in the present invention casting 11, a Ni layer is provided as an intermediate layer on the molten steel injection surface (K), and the mold life is changed.
It can be lengthened to m. That is, although Ni-1 has very good so-called static adhesion to copper or copper alloys, its physical properties such as hardness and coefficient of thermal expansion are different from those of copper or steel alloys, so it is not suitable for so-called dynamic adhesion. Target adhesion is slightly inferior to static adhesion. However, when a 5155 layer is provided as an intermediate layer or a buffer layer, dynamic adhesion is similarly excellent. Ni mesh + total thickness is 100~1
The shoulder should be about 000μ, preferably 200μ.
〜500j1ml. The thickness of the 5155 layer is 1
Below 00 fi, the effect of improving dynamic adhesion is not significant; on the other hand, when it exceeds 1000 s*,
This is not preferable because it inhibits heat removal.

Furthermore, according to the research conducted by the present inventor, it has become clear that the life of a mold for continuous casting of copper or copper alloy steel is mainly determined by damage to the protective coating layer on the lower part of the inner surface of the mold. Therefore, the Ni-W' alloy mesh on the inner surface of the mold may be formed into a tapered shape so that the total thickness gradually increases from the top to the bottom. That is, by changing the inner thickness of the door within the range of 20 to 500 μm, for example,
The middle layer of the xi-F alloy at the upper end is set to 10μ, and the thickness is gradually increased toward the lower end to make the thickness at the lower end 100μ.
It can be used as a curse. Even when forming the entire tapered mesh, ten layers of tapered or non-tapered Ni metal can be formed as the intermediate layer. In this case, it is preferable that the total thickness of the Ni layer and the entire Ni-F alloy layer be 330 to 30 .mu.mS degree.

Furthermore, in some cases, after cutting to a certain depth in advance from the lower end of the inner surface of the mold to the extent of the total height of the mold, this part is cut with a ui-wr alloy layer alone or with a Ni intermediate layer and a Ni-F layer. It was also found that the remaining 3 to 5 coats can be coated with an alloy layer and the remaining 3 to 5 coats can be coated without coating. Also in this case,
The thickness of the coating may be uniform, or it may be tapered from above to below, or it may be a two-step taper with a large taper angle near the lower end of the coating layer.

Furthermore, in the mold of the present invention, after forming the middle layer, it is possible to further extend the life of the mold by subjecting it to a dipping treatment (baking jig) at 400 to 600°C for 1 to 2 hours according to a conventional method. I can do it.

Example l Steel continuous casting mold (short side width 250w x height 700cm)
, long side width 1300 mm x height 700 mm) on the molten steel injection surface with a thickness of 200 μ and a total thickness of 50 mm.
63 'II Ni-37*t' alloy layer eJ [next formation].

When the obtained mold was used for casting ordinary steel, 400
Even after 9 sage (1 charge: 'l Q Q ta +%), some sushi eaves were observed, and there was almost no wear overall.

Comparative example l 300JIII was applied to the molten steel injection surface of the same mold as in Example 1.
A full-sized Ni-P alloy middle layer with a thickness of 30 swg and a Cr middle layer with a thickness of 10μ are sequentially provided.

When the obtained mold was used for casting in the same manner as in Example 1, after 500 charges, copper was observed to be exposed at the lower left and right ends of the long sides, and an area of about 30 square meters in the upper and lower middles, excluding the central part. The exposure of the Ni layer was recognized.

Comparative Example 2 100-tone Cr was applied to the molten steel injection surface of the same mold as in Example 1.
Forms middle layer of mets.

The obtained nine molds were used for casting in the same manner as in Example 1, and after 50 charges, the left and right lower end portions were 100w1i.
Exposure of copper was observed at about 301w at the bottom end and center.

Comparative Example 3 A copper mold was obtained in the same manner as in Example 1 except that the composition of the alloy layer was 85*Ni-15Is11'.

When the nine molds obtained were used for casting in the same manner as in Example 1, after 50 charges, damage to the mold was found to be the same as in the case of comparative f142.

C and above)

Claims (1)

[Claims] ■ In continuous casting of copper or prepared alloy steel,
20 to 40 weight of Tashixten on the molten steel injection surface of the mold.
A mold for continuous casting of steel, characterized in that it forms ten layers of a stainless steel and kerosene alloy containing metal.