JPS5868463A - Insert casting method for cooling pipe or the like - Google Patents

Abstract

PURPOSE:To prevent carburization by low-carbon steel foils and to reduce the cost for insert casting with simple stages by wrapping foil materials of low- carbon steel on the surfaces of pipes, etc. to form covering layers then insert casting the pipes, etc. into castings. CONSTITUTION:In the stage of insert casting of cooling pipes 3 in a stave 1 for cooling of blast furnaces, foil materials 4 of low-carbon steel of about 30 microns thickness contg. <=0.20% carbon are warapped on the sufaces of the pipes 3, whereby covering layers of 50-400 microns thickness are formed. Low-carbon steel has a m.t. higher than a casting temp., does not cause erosion in the stage of insert casting, prevents carburization and prevents the embrittleness of the pipes 3. Since the pipes 3 do not contact directly with the molten metal, the original mechanical properties of the pipes 3 are retained and a high cooling effect is obtained by the low carbon steel covering layers having high heat conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for casting cooling pipes, etc., and in detail, C. When casting cooling pipes in a blast furnace cooling staple, unlike conventional methods, the surface of the cooling pipe is coated with refractories. The low-damage bulk steel foil is coated without completely covering the refractory fibers, and the thickness of the W1 layer is kept constant, allowing for peeling even at high temperatures, which is different from the conventional case of covering with refractories or refractory fibers. Some%A
The cooling pipe method is used, which eliminates the preheating and drying steps without causing harmful reactions with the bath iron.

In general, a blast furnace cooling stave 1 is made by integrally molding refractory bricks 2 and cooling pipes 3 into one piece, as shown in Fig. 1.
The cooling pipe 3 is configured to pass cooling water to cool the stave 1, etc. However, the cooling pipe 3 is
During casting, it is exposed to high IM (Zr), which causes deformation and thermal stress.

Heat @ attack? Did it break or break after receiving it? There is a risk that this will occur. There are many problems such as the cooling pipe 3 becoming brittle due to the primary and -1 heated metals.

Therefore, conventionally, the outer surface of the cooling pipe 3 is coated with a covering material such as #large material or refractory fiber and then cast, or there is considerable variation in the film thickness of the covering material. Carburizing? Failure to prevent the problem properly or the occurrence of cracks will have a negative impact on the cooling function. vinegar. 1. When high-temperature i"e-C bath water is poured into Komagome 1, a partial V (void or crack occurs) on the surface of the cooling pipe due to the difference in expansion, allowing the bath water and CO gas to penetrate. , becomes carburized and becomes brittle.

Furthermore, in case of building a building using the conventional method, the surface of the cooling pipe is finished with an uneven surface, then preheated, and then the refractory material is turned into a slurry and painted by spraying it with a gray gun. Also, when casting, the cooling pipe is at a cooling temperature of 4.

Casting is carried out within an appropriate temperature range so that the surface coating material does not peel off and further damage is prevented. But by the Loss of Rice Act? & When cooling pipes are cast in a carbon-iron alloy, the camphor forest of TRT fireworks etc. will peel off and the debris will seep into the bath water, making it impossible to obtain a sound casting.The reason for this is ,
If the thickness of the coating material is shortened due to the degree of drying of refractory materials, internal S defects will occur due to insufficient drying of the refractory materials, etc., and due to peeling of the refractory material, poor bath coating will occur on the cooling pipe VC. Occur. In addition, before painting the refractory, preheating is required for landscaping, and even after 0m installation, main drying is required, resulting in a large loss in terms of heat melting economy. Historically, it has been impossible to store long-term cooling pipes in the painted state of large IIT products due to moisture content, and the storage material on the surface is easily damaged during handling.

The present invention aims to solve the above-mentioned drawbacks, specifically, the surface of the cooling pipe? By surrounding it with low carbon steel foil, the OS: carbon foil will not peel off during casting, and carburization can be prevented.

We have proposed a casting method that can improve workability and reduce costs due to energy savings, and the low-moxibustion foil on the surface has excellent thermal conductivity and can be used as a cooling pipe with a large cooling effect.

That is, 1 the present invention provides Kl'e in castings of iron or iron alloys.
When wrapping a pipe made of RJ material or a different material, wrap a low carbon foil V containing 0.20 or less carbon around the surface of the pipe to cover it with a thickness of 50 to 400 microns.
The present invention-V (this invention will be explained in detail) by forming the k floor and installing pipes etc.

1. Prior to wrapping the piece, as shown in FIG. 2, a low carbon foil material 4 is wrapped around the outer periphery of the cooling pipe 3. In this case, as long as the outer surface of the cooling pipe 3 is wrapped, it can be wrapped in any manner. For example, IJ can be flat rolled or #-I spiral wrapped. Moreover, the foil material 4 is made of low carbon steel, and its carbon content is uO
, 20 inches or less, and preferably 30 microns or less in thickness.

The thickness of the wrapped layer should be approximately 50 to 400 microns.

That is, if the carbon content II# in the foil material is less than 0.20 9, it is clear from the iron-carbon phase diagram shown in FIG. 3 that the melting iI! The temperature is about 1520C, and when casting, there is no melting loss compared to the casting temperature.
As shown above, when the amount of carbon in the foil material increases to 0.2%, the higher the value, the higher the VC from the foil material to the cooling pipe. ! ! The thickness of the foil material may be any thickness, but it is preferably 30 microns or less from the viewpoint of its workability and thermal conductivity.

In addition, the wrapping thickness of the foil material is 50 microns, which is difficult to completely prevent carburization under 40 microns or more.
Due to the expansion of the cooling pipe, a void is created in the winding part,
Heat conduction deteriorates and cm gas passes through the void,
Carburization of the orange area is promoted □ Next, the cooling pipe 3 wrapped with the foil material is set in a @-shape, and as shown in Fig. 4, it is cast with a base metal 5.
When casting, the outer surface of the cooling pipe 3 is wrapped with W3F, so even if it is immersed in instantaneous VC high-temperature bath water during casting, the melting of the foil material made of low carbon steel will continue. Because it is higher than the temperature, there will be no damage at all, and the surface of the cooling pipe will also be crushed, so it will definitely prevent the penetration of the hot water from the base metal 5 and cool it at the same time. Vibrator 3
The base metal 5 and the base metal 5 do not adhere to each other in the bath, and the mechanical properties of the cooling pipe 3 are not impaired.

Next, I will explain in detail about the implementation voice.

1. On the surface of the cooling pipe, prepare carbon-(CO, 12%
) No w3 Hayashi (J!l Q, Q4m)? S e attached ffte.

A coating of Vc 0.12mm was formed on the outer shell surface of the cooling pipe for 7t, and then it was set in the cooling pipe mold and cast with Fe-c type Rakutougag at 1215C.
The microstructure near the surface of the cooling pipe at this time is shown below.
5th V [As shown. As is clear from Figure 5, 1
It was found that there was almost no carburization on the surface, and the structure was similar to that of the original tube. In fact, when we actually determined the carbon content from the outer surface of a low-carbon foil coated with heat, the results were as shown in Table 1.

gl Table 1 As is clear from Table 1, the carbon content of the original tube is 0.12%, whereas the carbon content of the cooling pipe cast by the method of the present invention is 0.12 to 0.14%. It can be seen that it is not carburized.

The method of the present invention (g) is to completely wrap a low carbon steel foil material around the outer surface of the cooling pipe to form a coating layer. In addition, there is no need to apply refractories or the like as in the conventional case, and there is no need for a drying process, so the work efficiency is greatly improved. In particular, according to the method of the present invention, there is no risk of variations in the thickness of the coated layer, as was the case with the conventional coating work for refractory coating, and a uniform layer of uniform thickness can always be obtained.
can. For this reason, the cooling pipe Kfp charcoal mesh is formed by the formation formula f′
However, the bathing part with the base metal does not occur and it does not cool down.
The mechanical properties of the cooling pipe are not compromised. Therefore, during use of blast furnace staves, etc., for example, cracks will not occur in the base metal and the book and cooling pipe will not break at the same time, and from a safety perspective, it has a large number of young fruits.
Although the explanation focused on the hole fittings that are cast into the cooling pipe in the blast furnace cooling stave, it can be applied to any part of the hole that is cast.

[Brief explanation of the drawing]

Figure 1 shows one ga of blast furnace cooling stave? Showing the sensuzu, No. 2
(2) is a method of connecting the cooling pipe Qr outer wall according to the method of the present invention;
FIG. 4 is an explanatory diagram showing the cast-in condition of the cooling pipe, and FIG. 5 is an explanatory diagram of the microstructure of the cooling pipe when the method of the present invention is applied. Code 1...Blast furnace cooling stave 2...-
・Firebrick 3... Cooling vibe 4...
... Foil material 5 ... Bullion special fraud person 71
Hitoshi Suzuki, Patent Attorney, Matsushita Gifu, Patent Attorney, Ichizaki Sessaku Co., Ltd. Figure 2, Figure 3, C (%) Figure 4, Figure 5, Procedure Supplement + Book E (Flag) March 25, 1980 1 , Incident display Showa 56. Special Application No. 167278-
(H・)t4!9 11 Title of the invention Casting method for cooling pipes, etc. 3, Supplement 1
]:Relationship with patent applicant 7, subject of amendment Brief explanation of the inside of the specification, column 0 8,
Contents of the amendment As shown in the attached sheet, the contents of the amendment 1, the statement in the brief description of the drawings section on page 9, lines 2-3 of the specification, have been corrected as follows. "This is a photograph showing the micrometallic structure of the cooling pipe of Gurun 712."

Claims (1)

[Claims] When casting a pipe, etc. of a surrounding material or a different material into a casting of iron or iron alloy, the surface Eii of the pipe, etc.
A method for casting a cooling pipe, etc., characterized in that the pipe, etc. is cast by wrapping a foil material of world carbon containing 0.20 or less liK carbon to form a 50 to 400 micron thick layer.