JPS5934473B2 - Casting method for steel materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When casting steel materials with cast iron, cast steel, etc., the present invention improves the content of the coating layer that prevents welding of the steel material and the molten metal of the casting material. This invention solves the problem of cracks in the coating layer and the difficulty of integrating the mold layer, which are conventional problems.

When casting various parts made of conventional steel materials with materials such as cast iron or cast steel, direct contact between the steel material and the molten metal for casting may cause carburization on the surface of the steel material if the molten metal is cast iron. There are defects that occur and cause embrittlement of the material, and it is necessary to prevent welding due to direct contact.

In order to solve this problem, conventionally, alumina-based ceramic powder mixed with a kind of binder was coated on the surface of the steel material to be cast in advance, and this coated layer was applied. This prevents direct contact between the molten metal and the steel material, but with conventional mold coating methods, the heat resistance of the binder itself becomes the strength of the coating layer, so the steel material parts are Depending on the shape, etc., cracks may occur in the coated mold layer due to thermal shock during pouring, and this may lead to peeling of the coated mold layer.

The present invention solves the above-mentioned problems by changing the structure of the intervening mold layer when casting various parts made of steel materials with casting materials such as cast iron and cast steel. The feature is that a first coating layer made of 100% ceramic powder is applied to the surface of the steel material to be cast by thermal spraying, and then an amount of ceramic powder is applied onto the coating layer. At least two or more mixed coating layers of ceramic and metal mixtures with a decreasing amount of metal alloy powder and an increasing amount of metal alloy powder are laminated by the same thermal spraying method, and then a final coating layer of 100% metal alloy powder is applied. By coating the upper surface by the same thermal spraying method, the thermal shock during pouring of casting material such as cast iron or cast steel is alleviated, and cracks in the coating layer are prevented.

The present invention will be described in detail with reference to the embodiments shown below. The drawing is an explanatory view of an example of a cast iron, cast steel, etc., which is a steel material, in which the present invention is implemented. The casting material 2 is a steel material that is integrated into the casting by the casting material 1, and the illustrated example shows a bent pipe having an elbow portion 3 as shown.
Reference numeral 4 indicates a sprue, 5 a runner, and 6 a weir, which are not shown in the drawings, but of course this casting is carried out within a mold.

Conventionally, for such castings, steel materials 1
Alumina ceramic powder kneaded with a binder is applied to the surface of the mold to form a ceramic coating layer, thereby avoiding direct contact with the molten metal when pouring the casting material 1. In this way, troubles such as carburization and welding of the steel material due to welding with molten metal are prevented, but as mentioned earlier, in the case of this example, especially at the bent elbow part 3. Cracks are likely to occur in the coating layer, and product quality will be significantly reduced.

In the present invention, when casting the steel material 2 and the cast material 1, a necessary surface of the steel material 2,
The following coating layer is formed by thermal spraying as a composite coating layer in which a plurality of coating layers are laminated.

That is, a commonly used ceramic powder, such as alumina or zirconia, is thermally sprayed onto the surface of the steel material 1 as a first layer using metal spraying means, and then the above-mentioned ceramic powder is deposited on the surface of the first layer. N1-, which is commonly used as a metal intermediate layer in the formation of metal spray coatings, is added to the powder.
A mixture of metal alloy powder such as Alj alloy, Ni-Cr alloy, etc. in an appropriate amount, for example, the first layer is 100%
If it is a ceramic powder, the second layer is a mixture of 80% ceramic powder, 20% N1-A6 alloy, and Ni-Cr alloy powder, and then the third layer is a mixture of 60% ceramic powder and 40% N1. -Ax gold alloy Ni-Cr alloy powder mixed, the second and subsequent layers are made by thermal spraying several layers (2 to 3 layers) of ceramic powder and metal alloy powder with a gradually changing mixing ratio. The uppermost layer, that is, the layer directly in contact with the molten metal of the casting material 1, is coated with a 100% metal alloy such as N1-AA gold alloy Ni-Cr alloy by thermal spraying. , the coating layer is completed, and after applying such a composite coating layer, the casting is performed by pouring the molten metal of the casting material 1.

Next, specific examples of changes in coating ratio in each layer of the composite coating layer according to the present invention will be shown.

The present invention is as described above, and by using a composite coating layer in which the coating layer in which the mixing ratio of ceramic powder and metal alloy powder is gradually changed is configured in a laminated manner, it is possible to form a casting material. When pouring the molten metal in step 1, the thermal shock applied to the ceramic coating layer can be appropriately alleviated, and cracks can be reliably prevented from occurring in the coating layer, and the surface in contact with the molten metal is coated with a 100% metal alloy layer. Therefore, close integration with the casting material can be easily achieved.Moreover, in the present invention, thermal spraying is used to cover the coating layer, so unlike the conventional coating process, it is possible to easily achieve close integration with the casting material. The drying process of the steel material 2 and the casting material 1 can be omitted, the coating layer can be quickly and easily formed, and a homogeneous and stable coating layer can be easily obtained. This is achieved by improving the adhesion of the coating layer, and is excellent as it reliably eliminates the conventional problems caused by cracking.

Conventionally, in this type of casting, a ceramic layer is applied to the surface of the material to be cast, and then this material is soaked in a molten metal bath to adhere the metal layer to the ceramic layer, so that a part of the metal layer is made of ceramic. This is intended to penetrate into the layer surface and bond the two at the interface, but with only two coating layers, it is impossible to prevent cracks in the ceramic layer unless the metal layer is made considerably thicker. The work is time-consuming because it is soaked in the dirt, and it is difficult to form a uniform metal layer on the entire surface.

In contrast, in the present invention, between the 100% ceramic coating layer and the 100% metal coating layer, there are at least two or more layers of ceramics in which the amount of metal is gradually increased in proportion to the gradual decrease in the amount of ceramics. Since a mixed coating layer made of a metal mixture is interposed, when looking at the coating layer as a whole, the mixed structure of the ceramics gradually decreases from the bottom to the top and the metal gradually decreases from the top to the bottom becomes uniform. This makes it possible to reliably prevent cracks on the ceramic coating mold side, and since the coating is applied repeatedly by thermal spraying, it can be applied extremely efficiently and effectively functions as a tough and highly elastic coating layer. It is extremely advantageous in that

[Brief explanation of the drawing]

The drawing is an explanatory diagram of an example of cast casting in which the method of the present invention is carried out. 1...Casting materials such as cast iron and cast steel, 2...
...Steel material, 3...Elbow part, 4...
... sprue, 5 ... duct, 6 ... weir.

Claims (1)

[Claims] 1. When casting a steel material with cast iron, cast steel, etc., a first coating layer made of 100% ceramic powder is applied to the surface of the steel material by thermal spraying, and then ceramic powder is applied onto the coating layer. At least two or more mixed coating layers of ceramic and metal mixtures are laminated by thermal spraying, in which the mixing ratio of ceramic powder and metal alloy powder is gradually decreased and the amount of metal alloy powder is gradually increased. Next, a final coating layer made of 100% metal alloy powder is applied to the top surface by the same thermal spraying method, thereby mitigating the thermal shock during pouring of casting material made of cast iron, cast steel, etc., and preventing cracks in the coating layer. A casting method for steel materials characterized by preventing