JPS5874252A - Mold for continuous casting - Google Patents

Abstract

PURPOSE:To improve the heat conductivity in the upper part of a mold and the abrasion resistance in the lower part by providing layers of an Ni-P alloy and Cr metal respectively of prescribed thicknesses in the upper and lower parts on the inside surface of the copper mold in contact with molten metal and subjecting these layers to heat treatments at prescribed temps. CONSTITUTION:An Ni-P alloy layer of 30-100mum thickness is provided on the lower half part on the surface of a mold consisting basically of copper in contact with molten metal. A Cr metal layer of 10-500mum is provided on the top layer thereof over the entire surface of the mold or only on the upper half part thereof. Thereafter the above-described Ni-P alloy layer and Cr metal layer are heat-treated for 5min at 300-500 deg.C. The above-mentioned mold has excellent heat conductivity in the upper part and high abrasion resistance in the lower part and yields slab of good quality.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a continuous casting operation with a thinner luster.More specifically, the upper part of the mold has good thermal conductivity, and the lower part of the mold has high wear resistance. This relates to a continuous casting mold configured as follows.

It is well known that in recent years, continuous casting has become mainstream in the manufacturing field, but in implementing continuous casting operations, there are important aspects such as improving product quality and operational efficiency. As a result, improvements in molds are desperately needed.

The present invention was developed based on such a view and from the factual proposal of the same subject from the operational site. This is a successful mold manufacturing method.

In addition, I would like to comment on the water-cooled copper mold, lol! I
11. There have been many inventions related to casting hardening constructions or mold manufacturing methods in which surface treatment is applied to the contact side with metal.

However, each of these conventional inventions has many problems from a practical standpoint, and a satisfactory mold has not yet been completed. Only,
What can be said with certainty is that if a mold is made only of mirror materials, loud cracks will occur on the surface of the mold slab, resulting in poor product quality, and the copper plate surface will be severely worn, shortening the life of the mold. It is.

ml! Some inventions regarding surface treatment methods include:
For example, equity E 48-28255, same < 52-9
No. 169, JP-A No. 51-147431, same as No. 52
No.-54422.

52-10828 and 52-56018, etc., but in the case of JP-B No. 48-282558, many heat cracks occur due to high-speed continuous casting operation, and in the case of JP-B No. 52-9169H, electroless nickel Since it is Lurin plating, it has very poor thermal conductivity and may cause burn-in, making it difficult to form a thick plate that is thick enough to extend the life of the mold.

Furthermore, in the case of the mold described in JP-A-51-147451, the interlayer as in the above two cases is still present, and since no heat treatment is applied, the hardness of the alloy plating such as nickel-phosphorus cannot be sufficiently improved. Furthermore, since Cobalt has low thermal conductivity and is inferior in malleability to Cobalt, heat cracking in the meniscus area is further exacerbated and accelerated.

Furthermore, in JP-A-52-54622, chromium plating is applied on electroplated nickel, but chrome plating is severely corroded in the lower part of the mold that comes in contact with secondary cooling water and easily disappears. Therefore, since it is not sufficiently effective against wear at the bottom of the mold, wear resistance depends only on the second part. And JP-A-52
It can be said that JP-A-10828 and JP-A-52-54018 have the same drawbacks as the above-mentioned JP-A-52-54622.

The present invention aims to provide a mold which should eliminate the above-mentioned drawbacks.The gist of the present invention is to provide a mold made of copper as a base material.
A 1000 μm thick second Kerlin alloy layer is provided, and a chromium layer of 10 μm to 500 μm thick is provided on the entire surface of the mold or only on the half surface of the mold.
and the nickel-phosphorous alloy layer and the chromium layer are heated at 300°C.
2. Kel
This is a continuous casting mold characterized by comprising a phosphorus alloy layer and a chromium layer.

The present invention will be described in detail below with reference to the drawings showing embodiments thereof.

Under the following plating conditions, as shown in FIG. 1, a Kerrin alloy plating layer (2) was attached to approximately the lower half of the copper mold base material (1) so that the thickness was as smooth as possible.

2. Kel-Rin plating conditions and bath composition> Nickel sulfate 175t/j Nickel chloride 50 f/l phosphoric acid
501/l, phosphorous acid t51/l pH 0.5~
10 Bath Humidity 4 75-85°C Current Density ~ 10 μm/dII/So After that, using a normal surge bath, a chrome-plated shoe with a thickness of about 50 μm is shown in Figures 2 and 3. I installed it like this.

In addition, when installing a chrome plating layer (31) only on the upper half of the mold, the outermost surface of the mold may be made uniform as shown in Figures 114 and 115, in addition to the case shown in Figure 3. As shown in FIG. 164, there are cases where the nickel-phosphorus alloy plating layer (3) and the chromium plating layer (3) overlap in the center of the mold, and cases where they are not, as shown in FIG. Thereafter, this was heat treated at 400°C for 30 minutes.

The hardness (micro-Vickers) and thermal conductivity of each plating layer of the continuous casting mold manufactured as described above are shown in Table 1, along with those of the Ni-Kel plating for ratio casting.

Table → 1゜As can be seen from this Table-1, the N1-P alloy layer is stronger when no intensive heat treatment is applied, compared to the conventional Ni-Kel plating only or chrome plating only. and C
The combined structure with the R layer has sufficient uniformity of hardness for refreshing purposes. In other words, the surface protective layer can be increased. Also, in terms of thermal conductivity, it can be expected to exhibit a desirable water cooling effect.

Note that the same effect can be obtained even if the plating bath for the nickel-phosphorous alloy exemplified is a sulfamic acid bath, a pyrophosphoric acid bath, or the like.

In addition, the heat treatment humidity is 300 to 500, considering the brittle characteristics of steel.
00°C is excessive.

The mold according to this example uses the conventional mold 111 (
(not including alterations after use), it was around 50°, but it was about twice as long as 900°, and the cast □ one-sided cracking was also a star quality.

According to the present invention, as described above, the upper half of the mold is covered with only a relatively thin chromium layer. The part has good thermal conductivity, and there are two parts approximately in the lower half of the mold.
The nickel-phosphorus alloy layer is stretched (a chromium layer may be further provided on the top surface), and the hardness of the nickel-phosphorus alloy layer is increased by subsequent heat treatment, so it is approximately the lower half of the same mold. Because it has excellent wear resistance in the upper part of the mold, it can prevent breakouts, heat cracks, and scratches due to decreased thermal conductivity in the upper part of the mold, and also minimize wear and tear in the lower part of the mold. , it is possible to obtain slab products of good quality over a long period of time.

[Brief explanation of the drawing]

The first one is an explanatory diagram showing the process of manufacturing the mold of the present invention, the second one is an explanatory diagram showing the process of manufacturing the mold of the present invention.
Figures to WAS figures are explanatory diagrams showing each aspect of the mold of the present invention, respectively. In the figure, (11: Mold base material (21: Nickel-phosphorus alloy layer (3) Nichrome edition patent ratio - Mishima Kosan Co., Ltd. Figure 1 #2v11 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In the casting 11 made of copper as a base material, a 50# to 1000mm thick Kerrin alloy layer is provided approximately in the lower half of the surface that will come into contact with the molten metal, and a mold is placed on the upper layer. 10 μm to 50 μm over the entire surface or only on half of the road
A chromium layer with a thickness of 0 am is used, and the above-mentioned 2. Kel-Rin alloy layer and chromium layer are heated at 300°C to 500°C (both of them are heat-treated in a 5-minute tone). Continuous casting mold with exemption of ξ.