JP2777980B2 - Manufacturing method of heat-resistant steel castings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heat-resistant steel cast steel product, such as a grate built in an incinerator, which is made to withstand high-temperature wear from heat-resistant cast iron, cast steel, and the like. It is.

[0002]

2. Description of the Related Art Conventionally, cast iron and cast steel products are used depending on the size of a furnace used.
℃, but now it is continuously processed at 700 ℃ ~ 900 ℃, and furthermore, precision is required for air conditioning, so machining is required, and usually 0.5 m or less as cast Tolerance is required.

[0003]

As described above, cast irons and cast steels are conventionally used depending on the size of the furnace used, but each has an advantage and disadvantage, and the grate is burned. Since the metal mixed in the corrosion-resistant and heat-resistant refuse is welded to the grate and the grate falls off, it is a fact that the grate is replaced every time or periodically.

[0004] Therefore, the furnace shutdown period is long, and the cost is enormous. In addition, the furnace itself has been improved and advanced in recent years, and the amount of incinerated ash is decreasing. In addition, as described above,
Processing at 50 ° C to 600 ° C is now 700
At present, it is necessary to frequently exchange stokers and the like for alloys that have been conventionally used because continuous processing is performed at a temperature of from 900C to 900C.

[0005] In addition, machining is required, for example, precision is required for air adjustment, and since it is normally cast and has a tolerance of 0.5 mm or less, the following properties are required. (B) Abrasion resistance, (b) Corrosion resistance, (c) High temperature resistance, (e)
Withstands continuous use of 15,000 to 20,000 hours.
However, it has been difficult for conventional alloys to meet the requirements (a) to (e). The present invention has been proposed in view of such circumstances, and its purpose is to provide:
It is an object of the present invention to provide a heat-resistant cast iron product which has high resistance to abrasion, corrosion, and high temperature and can withstand continuous use for a long time.

[0006]

In order to achieve the above object, a method for producing a heat-resistant cast iron cast steel according to the present invention comprises the steps of: alloying ratio C: 0.25 to 0.3%; 0%,
Mn: 0.8-1.0%, P: 0.02-0.025
%, S: 0.005 to 0.008%, Cr: 25.0 to%
28.0%, Ni: 1.0-1.2%, AL: 5.0-
6.0%, Fe: 66.125 to 61.467% material is melted at a melting temperature of 1600 ° C. by a high frequency induction furnace, a casting metal having a casting temperature of 1500 ° C. to 1550 ° C. is cast into a mold, and the mold is separated. The high-temperature heat treatment is performed at 920 ° C. for 2.5 hours to 3.5 hours, and then cooled in a furnace at room temperature for about 8 hours or more.

[0007]

In the material used in the present invention, C is 0.2
Occupies 5% to 0.3%, moderate tensile strength, elongation, impact value,
It imparts weldability, Si serves as an inoculant, Mn is used as a deoxidizer for adjusting the composition, and usually S has a minimum content but eliminates harm when containing a large amount of sulfur P is used to improve the flow of hot metal.

[0008] 25.0% to 28.0% of Cr is added to alloy cast iron to provide oxidation resistance, corrosion resistance, toughness and the like. However, when a large amount is added, the temperature of the molten metal is lowered, and A thick oxide film is formed, which causes casting defects. Also, the addition of Ni is effective for improving the graphite structure and for removing chilled white iron, which is difficult to machine, and is a graphitizing accelerator that increases the strength by reducing the wall thickness sensitivity. Of metal is melted and drops in a granular form and adheres to the surface of the rostrum.
It can be easily removed by alloying about 1.2%.

[0009] AL is added as cast iron for nitriding or heat-resistant cast iron. However, excessive addition of Al tends to cause pinholes and significantly reduces fluidity. Thick oxide film, 1.5mm-2.0
Hot water wrinkles of about mm are easily generated on the surface of the upper mold.

Hereinafter, the present invention will be described with reference to examples. Alloy ratio C: 0.25-0.3%, Si: 1.80-2.
0%, Mn: 0.8 to 1.0%, P: 0.02 to 0.0
25%, S: 0.005 to 0.008%, Cr: 25.
0 to 28.0%, Ni: 1.0 to 1.2%, AL: 5.
A material of 0 to 6.0% and Fe: 66.125 to 61.467% is melted in a high frequency induction furnace at 1600 ° C.

At this time, aluminum oxide adheres to the side wall of the electric furnace, causing a change in capacity. Therefore, when performing alloying by inoculation, A
L is heated and melted at 600 to 800 ° C. In addition, casting water at a temperature of 1500 ° C. to 1550 ° C. is poured in a short time to achieve a brief setting. At this time, deoxidation is performed with Ca-Si.

Since the structure of the cast steel is coarse and brittle as cast, the mold is separated, for example, at 920 ° C. and 2.5 to 3.5.
A high-temperature heat treatment is performed for a period of time, followed by cooling at room temperature for 8 hours or more in a furnace. Since the cast steel product obtained by the above method has a remarkably large molecular crystal, it must be condensed as quickly as possible in consideration of the melting temperature, the alloy ratio, the casting speed, the shape, and the like. And until it congeals,
Aluminum oxide continues to evolve. In addition, if the high-temperature treatment and the normal-temperature cooling in the furnace are not sufficiently performed, the as-cast has little elongation, and the cutting becomes difficult.

The surface of the casting formed by the above method is finely finished by a method such as shot blasting, and after finishing, it can be machined at a speed of about 206 revolutions per minute at 155 mm. According to the alloy ratio table, the depletion rate of AL is 9% to 12%.
As the L material, 99% grains, plates, etc. are used.

[0014]

According to the present invention, as described above, the alloy ratio C is 0.25 to 0.3%, Si is 1.80 to 2.0%,
Mn: 0.8-1.0%, P: 0.02-0.025
%, S: 0.005 to 0.008%, Cr: 25.0 to%
28.0%, Ni: 1.0-1.2%, AL: 5.0-
6.0%, Fe: 66.125 to 61.467% material is melted at a melting temperature of 1600 ° C. by a high frequency induction furnace, a casting metal having a casting temperature of 1500 ° C. to 1550 ° C. is cast into a mold, and the mold is separated. High temperature heat treatment at 920 ° C for 2.5 to 3.5 hours, and cooling at room temperature for more than 8 hours in a furnace, it has abrasion and corrosion resistance, withstands high temperature, and withstands long-term continuous use It can cast heat-resistant cast iron products.

Claims (1)

(57) [Claims] 1. Alloying ratio C 0.25 to 0.3% Si 1.80 to 2.0% Mn 0.8 to 1.0% P 0.02 to 0.025% S 0.005 to 0. 008% Cr 25.0 to 28.0% Ni 1.0 to 1.2% AL 5.0 to 6.0% Fe 66.125 to 61.467% material is melted at 1600 ° C. by a high frequency induction furnace. And then cast into a mold at a temperature of 1500 to 1550 ° C, then heat-treat at 920 ° C for 2.5 to 3.5 hours after demolding, and cool in a furnace at room temperature for at least 8 hours. A method for producing a heat-resistant steel cast steel product, comprising: