KR101077171B1 - Hsla cast steel for slag pot having high elongation in high temperature - Google Patents

Abstract

The present invention relates to a steel for slag pot having excellent elongation at high temperature, and by controlling the steel component in an appropriate range, while replacing the C-Mn cast steel, such as SC previously used as a slag pot, while maintaining the same strength as compared to the conventional The purpose of the present invention is to provide an HLSA cast steel having excellent elongation at high temperature with low cracking rate. The present invention for achieving the above object by weight% C: 0.09 ~ 0.25%, Mn: 0.6 ~ 1.5%, P: 0.025% or less, S: 0.025% or less, Si: 0.8% or less, rare earth elements (REM): Cast iron for slag pot excellent in elongation at high temperature characterized by containing 0.1 to 1.0% and consisting of remaining Fe and unavoidable impurity is made into the summary. The present invention design HLSA cast steel with excellent elongation at high temperature by appropriately controlling the steel components, and by applying it to the slag pot to reduce the occurrence of cracks in the slag width to extend the service life, thereby reducing the investment cost and repair cost Can be obtained.

Slag Pot, Rare Earth, REM, Strength, Elongation, HSLA

Description

Highly ductile slag pot cast steel {HSLA CAST STEEL FOR SLAG POT HAVING HIGH ELONGATION IN HIGH TEMPERATURE}

The present invention relates to cast steel, which is applicable to slag pot, which is a container that receives slag generated in steel mills, etc., and more particularly, it can extend the service life of slag pots due to less cracking at high temperatures. It is about material.

Slag pot (Slag pot) is a container used for receiving and transporting high-temperature liquid slag, a by-product generated in the steelmaking process of steel mills, to be discarded in a yard. Conventionally, slag pot is a C-Mn cast steel such as SC42 and SC46. Produced.

As shown in FIG. 1, the slag pot 10 includes a rib 4 mounted on the lower side of the slag pot wall 5 on which the shaft 1 is mounted and a hook portion 7 mounted on the rib 4. And hook pins (2) and shackle pins (3) are mounted on both sides of the upper portion of the hook portion (7), and the slag pot (10) is lifted to exclude the liquid slag received from the steel mill in the yard. Lifting the hook pin (2) by the force of the other crane to lift most of the load to the shackle pin (3) slag pot 10 is rotated, the liquid slag is empty. At this time, the load acting on the shackle pin (3) pushes the slag spot by applying a compressive load to the rib (4) of the slag pot, and if the slag exclusion is repeatedly performed for a long time, the wall surface of the slag width is depressed by the compressive force. There is a problem that occurs.

In addition, since the liquid slag is a high temperature of more than 1400 degrees Celsius, when using the slag pot 10 for a long time, the inside of the slag pot 10 is in contact with the hot liquid slag, so the strength of the slag pot is much higher than at room temperature. Low deformation easily occurs, and the elongation is low, so there is a problem in which a turtle-like crack easily occurs even under a small stress.

These cracks become larger when the impact hamburger is applied to remove the molten metal attached to the surface of the slag after the liquid slag is removed from the yard, which shortens the service life of the slag and increases the cost of repair. .

In order to prevent such a phenomenon, "Slag pot steel with excellent high temperature strength" of the Republic of Korea Patent No. 605679 provided the effect of reducing the deformation by increasing the strength at high temperature by adding a small amount of elements such as Ni, V, Ti and the like. . However, since the elongation was lower than the conventional SC42 and the like for a long time use, the possibility of cracking due to shrinkage and expansion of heat was further increased, and there was a difficulty in repairing.

In addition, as shown in Figure 2, "Slag port with reinforcing mechanism" of the Republic of Korea Patent No. 289933 is provided with a reinforcing mechanism 20 to prevent deformation due to local stress concentration occurring in the slag pot. One slagpot was proposed. However, in this case, not only is the weight increase of the slag pot, but also the expansion and contraction of the slag pot due to the repeated use at high and low temperatures due to the slag input and exclusion prevents the expansion of the slag pot, thereby increasing the thermal stress and intensifying the crack. There was a problem.

In addition, Japanese Patent Laid-Open Publication Nos. 62-84891 and 62-130209 provide various repairing methods when such deformations and cracks occur. However, the application of such repairing methods requires cost and maintenance time separately. There is.

The present invention relates to a slag pot steel having excellent elongation at high temperature, and has excellent elongation at high temperature with low crack occurrence by substituting C-Mn cast steel, such as SC, which has been used as a slag pot. The purpose is to provide HLSA (High Strength Low Alloy) cast steel.

In order to achieve the above object, the present invention, by weight% C: 0.15% or more and 0.25 or less, Mn: 0.6 ~ 1.5%, P: 0% or more and 0.025% or less, S: 0% or more and 0.025% or less, Si: 0% Less than 0.8% or less, rare earth element (REM): 0.1 to 1.0% is contained, and is composed of the remaining Fe and inevitable impurities, the rare earth element (REM) is contained 50 to 60% by weight Ce, the rest is Nd, La It provides a cast steel for slag pot excellent in elongation at high temperature, characterized in consisting of two or more components selected from, Pr.

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According to the present invention having the above-described configuration, by designing the HLSA cast steel excellent in elongation at high temperature by appropriately controlling the steel components, and applying it to the slag spot, to reduce the occurrence of cracks of the slag spot, to extend the service life, thereby the investment cost And maintenance costs can be reduced.

Hereinafter, the configuration of the present invention will be described in detail.

In order to achieve the above effect, the present invention provides C: 0.15% or more and 0.25 or less, Mn: 0.6 to 1.5%, P: 0% or more and 0.025% or less, S: 0% or more and 0.025% or less, and Si: 0% or more. 0.8% or less, rare earth element (REM): 0.1 ~ 1.0% is contained, and is composed of the remaining Fe and inevitable impurities, the rare earth element (REM) is contained 50 to 60% by weight of Ce, the rest is Nd, La, Provided is a slag pot cast steel excellent in elongation at high temperature, characterized in consisting of two or more components selected from Pr.

In the present invention, by adding a rare earth element (REM) to the cast steel, the strength is maintained to be the same as before and the elongation is greatly improved to reduce the crack as well as the deformation of the slag pot.

Hereinafter, the steel component of the present invention will be described in detail.

C is a component contributing to the improvement of strength, the strength is lower than 0.15%, the strength is increased if it exceeds 0.25%, but the cause of impact toughness decreases and the weldability is poor, so The content is limited to more than 0.15% and less than 0.25%.

Mn is a component that can improve strength and toughness at the same time. If it is less than 0.6%, the impact toughness is increased but the strength is low, and if it is more than 1.5%, the strength is increased. Since it inhibits the content of Mn is preferably limited to 0.6 ~ 1.5% by weight.

P greatly reduces the impact toughness and causes cracks on the surface and inside, so the content is limited to more than 0% and less than 0.025% by weight.

Since S impairs impact toughness and weldability, the content is limited to more than 0% and 0.025% by weight or less.

Si is an element added for improving strength and deoxidation effect, and when excessively added, it causes cracking and impact toughness, so the content is limited to more than 0% and 0.8 wt% or less.

Rare earth element (REM) is an effective component to increase the elongation. If it is less than 0.1%, the addition effect is almost insignificant. If it exceeds 1.0%, the elongation increases by that amount, but the strength decreases significantly. Limited to 1.0% by weight.

Among the rare earth elements, Ce is the element which is most present among the rare earth elements, and is an element softer than zinc with good malleability and ductility. Therefore, in the present invention, it is preferable to contain Ce as an essential element among the rare earth elements. In addition, when two or more kinds of components selected from Nd, La, and Pr are further contained, steel for slag pots having excellent elongation can be obtained.

In addition, Ce and having good malleability and ductility are preferably contained in an amount of 50 to 60% in the rare earth element (REM) by weight, and controlled to 0.1 to 1.0 wt% with other rare earth elements to increase the elongation of the slag pot at a high temperature. It can improve more. However, in consideration of the economics and ductility of Ce to contain at least 50%, if the strength exceeds 60%, the Ce content is limited to 50 to 60% of the content of the total rare earth element.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Electrolytic iron and various alloying elements were dissolved in a vacuum furnace to prepare cast steel having a component by weight as shown in Table 1 below. At this time, the conventional example has a composition of SC42. Elongation and tensile strength were measured at 900 ° C. using the manufactured cast steels. The results are shown in Table 1 below.

TABLE 1

C Mn S and P Si Rare earths
element Elongation (%) The tensile strength
(MPa) Conventional example 0.16 1.2 0.005 0.7 - 72 51.1 Comparative Example 1 0.16 1.2 0.005 0.7 0.05 73 51.2 Inventive Example 1 0.16 1.2 0.005 0.7 0.5 82 50.5 Inventive Example 2 0.16 1.2 0.005 0.7 One 98 51.1 Comparative Example 2 0.16 1.2 0.005 0.7 2 42 42

As can be seen in Table 1, in the case of Inventive Examples 1 and 2, which satisfy the conditions of the present invention, the strength change is little compared to the conventional SC42, but the elongation is remarkably increased, and the length change after the experiment is shown in FIG. It can be seen that Inventive Examples 1 and 2 were significantly drawn compared with the conventional examples.

1 is a perspective view of a conventional slag pot.

2 is a perspective view of a conventional slag pot with reinforcement.

Description of the Related Art [0002]

1. Shaft 2. Hook Pin

3. Shackle pin 4. Rib

5. Wall 7. Hook

10. Slagpot 20. Reinforcement Mechanism

26. Vertical stiffeners 27. Horizontal stiffeners

28. Reinforcement plate

Claims (3)

By weight% C: 0.15% or more, 0.25 or less, Mn: 0.6 ~ 1.5%, P: 0% or more and 0.025% or less, S: 0% or more and 0.025% or less, Si: 0% or more and 0.8% or less, rare earth elements (REM) : Contains 0.1 ~ 1.0%, and is composed of the remaining Fe and inevitable impurities, The rare earth element (REM) is 50 ~ 60% by weight of Ce, the remainder of the slag pot cast steel having excellent elongation at high temperature, characterized in consisting of two or more components selected from Nd, La, Pr. delete delete

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