JPH08337812A - Production of heat resistant cast steel product - Google Patents

Abstract

PURPOSE: To produce a cast steel product enough in wear resistance, corrosion resistance, and high temp. resistance and withstanding continuous use for a long time by casting molten metal of a specified temp. obtd. by melting a steel material having a specified compsn. in a high-frequency induction furnace, knocking-out the same and thereafter executing high temp. heat treatment and cold cooling under specified conditions. CONSTITUTION: A material in which the allaying ratio is regulated to 0.25 to 0.3% C, 1.80 to 2.0% Si, 0.8 to l.0% Mn, 0.02 to 0.025% P, 0.005 to 0.008% S, 25.0 to 28.0% Cr, 1.0 to l.2% Ni and 5.0 to 6.0% Al is melted at a melting temp. of 1600 deg.C in a high-frequency induction furnace. At this time, since side wall of the electric furnace is deposited with aluminum oxide and the change of volume occurs, Al is melted under heating at 600 to 800 deg.C in the case alloying is executed by inoculation. Next, cast molten metal of 1500 to 1550 deg.C is cast into a mold. At this time, deoxidation is executed by Ca-Si. After knock-out, it is subjected to high temp. heat treatment at 920 deg.C for 2.5 to 3.5hr and is subjected to cold cooling for about >=8hr in the furnace.

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 cast steel product such as a grate built in an incinerator, which is produced for the purpose of withstanding high-temperature wear, such as heat-resistant cast iron and cast steel. Is.

[0002]

2. Description of the Related Art Conventionally, cast iron and cast steel products have been used depending on the size of the furnace used, and conventionally 450 ° C. to 600 ° C.
Although it was processed at ℃, it is currently processed continuously at 700 ℃ to 900 ℃, and because air adjustment requires accuracy, it requires machining, and usually it is 0.5 m or less as cast. Tolerance is required.

[0003]

As described above, cast iron and cast steel are conventionally used depending on the size of the furnace used, but both have advantages and disadvantages, and the grate burns out. The metal mixed in the corrosion-resistant and heat-resistant dust is welded to the grate to cause the grate to fall off. Therefore, the fact is that the grate is replaced every time or periodically.

Therefore, the furnace is shut down for a long period of time, and the cost is enormous. Also, the furnace itself has been improved and improved in recent years, and the amount of incinerated ash is decreasing. Also, as mentioned above,
Processing at 50 to 600 ℃ is now 700
Since continuous treatment is carried out at a temperature of from 900 to 900 ° C., it is the current situation that the stoker or the like has to be frequently replaced in the conventionally used alloy.

Further, for air adjustment, precision is required, and machining is required. Usually, as cast, the tolerance is 0.5 mm or less, so the following properties are required. (A) abrasion resistance, (b) corrosion resistance, (c) high temperature resistance, (e)
Withstands continuous use for 15,000 to 20,000 hours.
However, it has been difficult for the conventional alloys to meet the requirements (a) to (e). The present invention has been proposed in view of such circumstances, and the purpose thereof is to:
The point is to provide a heat-resistant cast iron cast steel product that is rich in abrasion resistance, corrosion resistance, and high temperature resistance and can withstand continuous use for a long time.

[0006]

In order to achieve the above-mentioned object, a method for producing heat-resistant cast iron cast steel according to the present invention comprises an alloy ratio C: 0.25 to 0.3%, Si: 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 to 1.2%, AL: 5.0 to
A 6.0% material is melted by a high-frequency induction furnace at a melting temperature of 1600 ° C., a molten metal having a casting metal temperature of 1500 ° C. to 1550 ° C. is cast into a mold, and after unmolding, at 920 ° C. for 2.5 hours to 3.5. It is characterized in that it is heat-treated at a high temperature for an hour and cooled at room temperature in a furnace for about 8 hours or more.

[0007]

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

[0008] Cr is added to the cast iron alloy in an amount of 0.3% to 1.0% to provide oxidation resistance, corrosion resistance, toughness, etc. When a large amount is added, the temperature of the molten metal is lowered and A thick oxide film is formed on the surface, which causes defective casting. Further, the addition of Ni is effective in improving the graphite structure and removing the chilled chill that is difficult to machine, and is a graphitization accelerator that reduces the thickness sensitivity and increases the strength. Metal is melted and falls in granular form and adheres to the surface of the grate.
It can be easily removed by alloying about 1.2%.

[0009] AL is added as nitriding cast iron or heat-resistant cast iron, but excessive addition thereof easily causes pinholes, resulting in a marked decrease in fluidity. Thick oxide film, 1.5mm-2.0
The wrinkles of about mm are likely to be formed on the surface of the casting upper die.

[0010]

EXAMPLES The present invention will be described below with reference to examples. Alloy ratio C: 0.25 to 0.3%, Si: 1.80 to 2.0
%, Mn: 0.8 to 1.0%, P: 0.02 to 0.02
5%, S: 0.005 to 0.008%, Cr: 25.0
Up to 28.0%, Ni: 1.0 to 1.2%, AL: 5.0
˜6.0% of material is melted at 1,600 ° C. in high frequency induction furnace.

At this time, since aluminum oxide adheres to the side wall of the electric furnace to cause a change in capacity, when alloying by inoculation, A
L is heated and melted at 600 ° C to 800 ° C. Also, cast water at 1500 ° C to 1550 ° C is poured in a short time to condense for a short time. At this time, it is deoxidized with Ca-Si.

Since the structure of cast steel is rough and brittle when cast as it is, it is, for example, 920 ° C. and 2.5 to 3.5 after unmolding.
High temperature heat treatment is carried out for a period of time, followed by room temperature cooling for 8 hours or longer in the furnace. Since the cast steel product obtained by the above method has a remarkably large molecular crystal, it must be solidified as soon as possible in consideration of the melting temperature, the alloying rate, the molten metal speed, the shape and the like. And until it sets
Aluminum oxide continues to be generated. Further, if the high temperature treatment and the room temperature cooling in the furnace are not performed sufficiently, the elongation is small after casting and the cutting becomes difficult.

The surface of the casting molded by the above method is finished by shot blasting or the like, and after finishing, it can be machined at a speed of 206 revolutions per minute and 155 mm. In addition, the wear rate of AL according to the above alloy rate table 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: 0.25 to 0.3%, Si: 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 to 1.2%, AL: 5.0 to
A 6.0% material is melted in a high-frequency induction furnace at a melting temperature of 1600 ° C., a molten metal having a molten metal temperature of 1500 ° C. to 1550 ° C. is cast into a mold, and after unmolding at 920 ° C. for 2.5 hours to 3.5. By heat-treating at high temperature for 8 hours and cooling at room temperature in the furnace for about 8 hours or more, it is possible to cast heat-resistant cast-iron cast steel products that have abrasion resistance, corrosion resistance, high temperature resistance, and long-term continuous use. is there.

Claims (1)

[Claims] 1. An alloy 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 0.004. A material of 0.008% Cr 25.0 to 28.0% Ni 1.0 to 1.2% AL 5.0 to 6.0% is melted at a melting temperature of 1600 ° C. by a high-frequency induction furnace, and a casting metal temperature is 1500 ° C. A heat-resistant cast steel product, characterized in that a casting hot water of ˜1550 ° C. is cast into a mold, and after unmolding, it is subjected to high temperature heat treatment at 920 ° C. for 2.5 hours to 3.5 hours, and then cooled at room temperature for about 8 hours or more in a furnace. Manufacturing method.