JPS6268671A - Production of stainless clad steel - Google Patents

Abstract

PURPOSE:To prevent the carburization of a cladding metal to the surface of a stainless steel by attaching a backing plate having the carbon content below the carbon content of the cladding metal to the surface of the cladding metal on which a release material is coated, setting the material into a casting mold and casting a molten steel into the mold. CONSTITUTION:After the release material 7 is coated on the surface of the cladding metal 2 to be separated from the base metal, the backing plate 8 having the carbon content below the carbon content of the cladding metal 2 is superposed therein and the periphery of the plate 8 is spot-welded and fixed. An antioxidant 6 is coated on the adhesive surface side of the cladding metal 2. The cladding metal 2 and backing plate 8 united to one body in the above-mentioned manner are set by a hanger 3 into the casting mold 1 and the molten metal which is the base metal 5 is cast into the mold by a bottom pouring method, by which a stainless clad steel ingot is obtd. The clad steel ingot is subjected soaking and blooming and is cut at four sides. The base metal on the side coated with the release material is stripped and thereafter the material is subjected to hot rolling, by which the clad steel plate is obtd.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention produces two-layer stainless clad steel by casting stainless steel in a base material having a carbon content greater than that of the stainless steel core material. It's about things.

(Prior Art) Conventionally, two-layer stainless clad steel sheets have been manufactured as follows.

First, as shown in FIG. 2, a stainless steel core material 2 (hereinafter referred to as a laminate material) is coated with an antioxidant 6 on the adhesive side and a release agent 7 on the peeling surface side, and then a hanging tool 3 is attached. After setting the steel in a mold so that the peeled surface side is thinner, molten steel 5 (hereinafter referred to as base metal) is poured by the bottom pouring method to form a clad steel ingot. Next, this clad steel ingot is placed in a bag in a soaking furnace and heated, followed by blooming rolling to form a slab in which the mating material and the base material are crimped together.After cooling, the top, bottom and both sides of the slab are rolled. The base material on the side coated with the release agent is removed to create a two-layer kraft steel slab.

Thereafter, hot rolling was performed to produce a clad steel sheet.

(Problems to be Solved by the Invention) However, in order to obtain corrosion resistance and strength, stainless clad steel sheets are made by combining stainless steel with a carbon content of 0.03% or less and structural steel with a carbon content of about 0.6 to 0.20%. When trying to manufacture the above-mentioned steel by the above-mentioned method, there was a problem in that carburization occurred on the surface of the stainless steel that was the mating material despite the presence of the thin film-like release material, which deteriorated the corrosion resistance. As shown in Fig. 3, the degree of carburization reaches a depth of 3 or more, and especially in the surface layer, the carbon content is 0.
It has increased by 0.04 to 0.09%. When a slab obtained from this stainless steel ingot is hot rolled, the carburization depth becomes shallower depending on the rolling reduction ratio, but the amount of carbon on the surface does not change.

Therefore, before hot rolling a stainless clad steel slab, the surface of the composite material had to be ground to remove the carburized portion.

An object of the present invention is to provide a method for manufacturing stainless clad steel in which carburization does not occur on the surface of the laminated material.

(Means for Solving the Problems) In the present invention, when manufacturing two-layer stainless craft steel, as shown in FIG. The method is characterized in that a caul plate 8 containing carbon is attached and set in a mold, and molten steel serving as the base material is poured into the mold.

Furthermore, the method of the present invention will be explained in detail. First, after applying a release agent 7 to the surface that separates the laminate material 2 and the base material, a caul plate 8 having a carbon content less than that of the lamina material 2 is placed on top of it, and the area around the caul plate is spotted. After fixing by welding, an antioxidant 6 is applied to the adhesive surface side of the laminate 2. The laminated material 2 and the patch plate 8 that have been processed and integrated in this way are set in the mold 1 via the hanging tool 3 in the same manner as before, and the molten steel that will become the base material 5 is poured by the bottom pouring method. After soaking and blooming the obtained stainless clad steel ingot, the four circumferences are cut, the base material on the side coated with a release agent is peeled off, and then hot rolled to obtain a clad steel plate.

(Function) In the present invention, a low-carbon backing material is attached to the side of the laminated material coated with a release agent, so when molten steel with a high carbon content is cast, the backing plate will be carburized, but stainless steel It will not be carburized until The results are shown in Figure 4.As can be seen from this figure, the depth of carburization from the molten steel that is the base material is the same as that of the conventional plate, but the amount of carburization of the cladding material is It has become extremely rare.

(Example) 80m x 1600n+ containing 0.020% carbon
The treatment shown in Table 1 was applied to the peeled surface of each laminate material of 5US304 of X2400+n.

After applying a hydrocarbon-based antioxidant to the adhesive side of the first facing material, the above-treated laminate is placed with a hanger at a position where the peeling surface side is 60 cm away from one of the long sides of the mold. It was suspended in a 30-ton mold.

After this, C10.13%, 5i10.20%, Mn10
．． 80%, P 10.015%, S 10.010
%, 8l110.028% was poured by the bottom pouring method at a molten steel superheating degree of 83°C to produce a clad steel ingot. After demolding, it was soaked at 1280°C for 8 hours and then subjected to blooming rolling at a reduction ratio of 4.0 to a size of 200 mm x 13Q.
Qmm X j2 I made a crane slab. After cooling this slab, the slab was cut around the four sides and the base material was peeled off to produce a two-layer stainless clad steel slab.

The carbon concentration on the surface of the laminated material at this time was 0.020% according to the method of the present invention, and 0.085% according to the conventional method.

(Effects of the Invention) As explained above, according to the method of the present invention, carburization of the surface of stainless steel, which is a mating material, can be prevented, so that the corrosion resistance of stainless steel is not impaired.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the method of casting clad steel according to the method of the present invention, Fig. 2 is a diagram showing the conventional casting method, and Fig. 3 is a diagram showing the surface of the cladding material in the case of the conventional casting method. FIG. 4 is a diagram showing the amount of carburization of the surface of the composite material by casting according to the present invention. 1... Mold

Claims (1)

[Claims] 1. When producing stainless steel clad steel using the casting method, a release material is sandwiched between the stainless steel core material and a patch plate containing a carbon content less than that of the stainless steel core material, and the stainless steel core material is suspended in a mold. , a method for manufacturing stainless clad steel characterized by casting molten steel as a base material.