KR20010046205A - HSLA Cast Steel for Slag Pot Having Improved High Temperature Strength - Google Patents

Abstract

PURPOSE: A HSLA (high strength low alloy) cast steel having superior tensile properties at a high temperature is provided which has low generation of deformation and cracks by controlling constituents of the steel to an appropriate range, thereby replacing C-Mn cast steel such as SC used as a slag pot. CONSTITUTION: The steel for slag pot having superior high temperature strength comprises 0.09 to 0.16 wt.% of C, 0.6 to 1.5 wt.% of Mn, 0.025 wt.% or less of P, 0.025 wt.% or less of S, 0.6 wt.% or less of Si, 0.09 to 0.13 wt.% of Ni, 0.35 to 0.4 wt.% of Cr, 0.45 to 0.55 wt.% of Mo, 0.02 to 0.06 wt.% of Al, 0.05 to 0.15 wt.% of one or more elements selected from Nb, V and Ti and a balance of Fe and inevitable impurities.

Description

HSLA Cast Steel for Slag Pot Having Improved High Temperature Strength}

The present invention relates to a cast steel that can be applied as a slag pot, which is a container for receiving slag generated in steel mills, etc. More specifically, the deformation and cracks are reduced at high temperatures, thereby extending the service life of the slag pot. It is about materials that can be used.

Slag pot used in the steelmaking process is a container for transporting slag to be excluded from the yard, conventionally made of C-Mn cast steel such as SC42,46. Liquid slag is a high temperature of more than 1400 degrees Celsius, so when the slag pot is used for a long time, the temperature of the slag pot rises and the strength of the slag decreases or the resistance to cracking tends to occur.

In order to prevent this, the reinforcing rod is installed in the slag pot, but in this case, the weight of the slag pot is not only increased but also the expansion of the slag pot due to repeated use at high and low temperatures due to slag input and exclusion. There is a problem that the cracking is intensified due to the increase of thermal stress by preventing the shrinkage. In addition, various repair methods such as deformation and cracks have been proposed (JP62-84891, JP62-130209). However, the application of such repair methods requires a cost generation and repair time separately.

Therefore, the present invention is to control the steel components in an appropriate range, replacing the C-Mn cast steel, such as SC, which was previously used as a slag spot, excellent tensile properties at high temperature with low deformation and cracking, HSLA (high tensile low alloy) To provide the cast steel, which has a purpose.

The present invention for achieving the above object by weight, C: 0.09-0.16, Mn: 0.6-1.5, P: 0.025 or less, S: 0.025 or less, Si: 0.6 or less, Ni: 0.09-0.13, Cr: 0.35-0.4 , Mo: 0.45-0.55, Al: 0.02-0.06, and contains one or two or more components selected from Nb, V, Ti and 0.05-0.15, characterized in that it is composed of the remaining Fe and inevitable impurities It is related with the slag pot steel which is excellent in high-temperature strength.

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

The C (carbon) is added 0.09-0.16 because less than 0.09 the tensile strength is lowered, if it exceeds 0.16 the strength is increased but the weldability is poor.

The Mn (manganese) is added in the 0.6-1.5, because the impact value is increased but less than 0.6, the strength is lowered, and if it exceeds 1.5, the strength is increased, but the carbon equivalent (Ceq) is increased and the weldability is poor.

The P (phosphorus) and S (sulfur) is added to 0.025 or less, which is limited to 0.025 or less because more P or S increases defects in the material and decreases the impact value.

The Si (silicon) is added below 0.6, because the impact value is lowered below 0.6.

The Ni (nickel), Cr (chromium) and Mo (molybdenum) are contained as 0.09-0.13, 0.35-0.4, 0.45-0.55, respectively, if their addition is less than the lower limit, the impact value increases but the strength is lowered, the upper limit If it exceeds, the strength increases, but there is a problem that the impact value decreases because the amount of ferrite in the tissue decreases.

The Al (aluminum) is added 0.02-0.06, which is less than 0.02 because the deoxidation effect of the material is less, the impact value of the material is reduced, and if it exceeds 0.06, the precipitation strengthening effect is reduced by the reaction with nitrogen to decrease the strength to be.

The Nb (niobium), V (vanadium), Ti (titanium) may be added by selecting one kind or two or more kinds, when added in the content of 0.05-0.15. The reason is that if the content is less than 0.05, the effect of enhancing the strength due to precipitation strengthening and particle refining is small, and if the content exceeds 0.15, the effect tends to be saturated, and thus further addition is not preferable.

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

Example

Electrolytic iron and various alloying elements were dissolved in a vacuum furnace to prepare cast steel having the components shown in Table 1 below. At this time, the conventional example has a composition of SC46 (JIS standard).

Using the cast steels prepared by measuring their high temperature yield strength of 500 ℃ is shown in Table 1 below.

C Mn S / P Si Ni Cr Mo Nb Al V Ti High Temperature Yield Strength (500 ℃) (kg / ㎠) Inventive Example 1 0.16 1.5 0.023 0.45 0.1 0.36 0.51 0.05 0.045 0.05 - 64 Conventional example 0.19 0.7 0.005 - 0.4 0.4 - - 0 - - 31 Inventive Example 2 0.097 1.5 0.023 0.47 0.1 0.36 0.50 0.05 0.046 0.05 - 63 Inventive Example 3 0.09 1.16 0.023 0.45 0.1 0.36 0.51 0.05 0.046 0.05 - 51 Inventive Example 4 0.097 0.65 0.023 0.47 0.1 0.36 0.52 0.05 0.046 0.05 - 45 Inventive Example 5 0.097 0.65 0.023 0.48 0.1 0.36 0.51 0.05 0.046 0.05 0.05 46

As can be seen in Table 1, in the case of Inventive Example (1-5) that satisfies the conditions of the present invention, the high temperature strength was significantly increased than the conventional SC46. In addition, after the production of slag pot using the HSLA cast steel according to the invention example (1-5), even if applied to the actual industry, less deformation and cracking than conventional.

According to the present invention as described above, by appropriately selecting the steel component to design the HSLA cast steel with excellent tensile properties at high temperature and apply it to the slag pot, it is possible to reduce the deformation and cracks in the real-world application of the slag pot Investment cost and repair cost can be reduced.

Claims (1)

By weight, C: 0.09-0.16, Mn: 0.6-1.5, P: 0.025 or less, S: 0.025 or less, Si: 0.6 or less, Ni: 0.09-0.13, Cr: 0.35-0.4, Mo: 0.45-0.55, Al: It contains 0.02-0.06, and contains one or two or more components selected from Nb, V, Ti, 0.05-0.15, and is composed of the remaining Fe and unavoidable impurities. River.