KR20040077105A - Special steel as hot-cool composite material and manufacturing process thereof - Google Patents

Abstract

PURPOSE: A special steel used as hot-cold composite material is provided which shows high heat resistance, wear resistance, impact resistance, oxidation resistance, accuracy and corrosion resistance by properly selecting type and content of elements added, and a method for manufacturing the same is provided. CONSTITUTION: The special steel used as hot-cold composite material comprises 0.90 to 1.20 wt.% of carbon (C), 0.50 to 1.50 wt.% of silicon (Si), 0.40 to 1.00 wt.% of manganese (Mn), 6.0 to 7.5 wt.% of nickel (Ni), 23 to 28 wt.% of chromium (Cr), 0.50 to 2.00 wt.% of molybdenum (Mo) and a balance of iron (Fe) and other inevitable impurities. The method for manufacturing special steel used as hot-cold composite material comprises a step of melting the sorted and weighed work in the temperature range of 1,700 to 2,000 deg.C after sorting and weighting a work such as ferro-alloy; a step of injecting the molten material into a mold frame formed by blending molding sand; a step of performing shaking-out and sand-breaking processes after cooling the molten material injected into the mold frame; and a step of machining the solution heat treated material after solution heat treatment of the cooled material in the temperature range of 1,010 to 1,150 deg.C to remove stress of the cooled material.

Description

SPECIAL STEEL AS HOT-COOL COMPOSITE MATERIAL AND MANUFACTURING PROCESS THEREOF

The present invention relates to a special steel as a cold heat composite material and a method of manufacturing the same.

Specifically, the present invention relates to a wire guide guide in a wire rod process, a deformed reinforcement guide in a hot rolled process, a billet cutting knife in a steelmaking process or a continuous casting process, a round bar cutting knife in a hot rolled process, The present invention relates to a special steel used for materials such as scrap metal cutting press knife, sharing cutting bending knife, rebar cutting knife or thick plate (steel plate) cutting knife in scrap metal, its use and manufacturing method.

The manufacture and processing of steel is generally done over a long period of time in high temperature environments. In this case, the general iron alloy steel is softened and surface oxidized as well as annealed when exposed to a high temperature environment even though its hardness at room temperature is high. Therefore, steel processing tools made of such iron alloy steel cannot be used for a long time especially at high temperatures. . Therefore, special steels having other element (s) added to carbon steels are generally used for the above applications.

Generally, the special steel refers to a steel having special properties suitable for each case by alloying one or more special elements with carbon steel. Such special elements for alloys include nickel (Ni), chromium (Cr), manganese (Mn), tungsten (W), cobalt (Co), vanadium (V), and silicon (Si), and some or all of these elements. If the alloy is selectively added in an appropriate amount, the original properties are improved and improved, and at the same time, special properties different from those of the unadded carbon steel are exhibited, so that special steels suitable for special applications can be manufactured by adjusting the added elements and the added content.

In other words, the properties of special steels vary depending on the alloying elements. When looking at the properties of general alloying elements, nickel increases toughness, increases oxidation resistance, nonmagnetic properties, low transformation point, high temperature impact resistance, and chromium has corrosion resistance and abrasion resistance. Molybdenum prevents tempering properties, Tungsten increases hardness and tensile strength at high temperatures, Copper increases oxidation resistance in air, Silicon has electromagnetic properties and heat resistance is improved. Manganese is one of the deoxygenating elements, and is effective for enhancing the solid solution. Cobalt plays a role in improving hot rolling properties, and vanadium can withstand high thermal shocks, thereby imparting heat resistance and corrosion resistance to the alloy. However, increasing the alloying amount of the above elements is not superior to the above properties, and will exhibit better properties when alloying the appropriate amount.

By alloying the appropriate amount of the above elements to produce a special steel according to the required purpose, structural steel, nickel-chromium steel, nickel-chromium-molybdenum steel, chromium-molybdenum steel, manganese-chromium steel is used, and as a hardened surface hardening steel Low carbon steel is used, but when demanding better performance, special steel containing nickel, chromium, molybdenum, tungsten, vanadium, etc. is used, and high carbon steel is used as tool steel.

The present invention relates to a cold-thermal composite material among the special steels as described above, and those shown in Table 1 are known in the conventional special steels.

division Standard symbol C Si Mn Ni Cr Mo Remarks SUS SUS440C 0.95-1.20 1.00 or less 1.00 or less 0.60 or less 16-18 - Martensitic Heat Resistant Steel (Heat Resistant, Wear Resistant) SUH36 0.48-0.58 0.35 or less 8.00-10.00 3.25-4.50 20-22 - N: 0.35 ~ 0.50 Austenitic Heat Resistant Steel (Heat Resistance, Wear Resistance, Shock Resistance) Heat Resistant Steel SCH12 0.20-0.40 2.00 or less 2.00 or less 8-12 18-23 - Heat-resistant steel (heat resistant, corrosion resistance) SCH24 0.35-0.75 2.00 or less 2.00 or less 33-37 24 ~ 28 - Heat-resistant steel (heat resistant, corrosion resistance) Nodular cast iron FCD500-7 2.5 or more - - - - - Tensile strength: 500N / mm ² or more Strength: 320N / mm ² or more Elongation: 7% or more Hardness: 150 ~ 230HB Base structure: Ferrite + Pearlite Alloy steel SKD61 0.32-0.42 0.8 ~ 1.2 0.5 or less - 4.5 ~ 5.5 1.0-1.5 V: 0.8 ~ 1.2 die casting die, extrusion die. ① SUS440C material is knives because of martensite structure ② SUH36 material is heat resistant steel ③ SCH12 and SCH24 material are heat resistant steel ④ FCD500-7 material is spheroidal graphite cast iron material ⑤ SKD61 material is alloy tool steel Hot mold material.

However, none of the special steels have the required level of heat resistance, oxidation resistance, abrasion resistance, impact resistance and corrosion resistance in high temperature, high pressure, and high impact environments such as steel or petrochemical processing. Severe hardness deterioration occurs for long time use. For this reason, when using the conventional special steel, the wear of the processing equipment is severe and must be replaced from time to time, which must be reworked, resulting in a decrease in production efficiency.

The present invention has been made to solve the above problems, the purpose of the special steel used as a cold-heat composite material to maintain excellent heat resistance, oxidation resistance, wear resistance, impact resistance and corrosion resistance even in high temperature, high pressure and high impact environment .

That is, an object of the present invention is to provide a special steel as a material that is used as a cold heat composite material, and maintains excellent heat resistance, oxidation resistance, wear resistance, impact resistance, precision and corrosion resistance in high temperature, high pressure and high impact environments.

Another object of the present invention is to provide a special steel as a guide material in particular.

It is another object of the present invention to provide special steels, in particular, as various knife materials.

Another object of the present invention is to provide a method for producing the special steel.

Another object of the present invention is to provide a special steel produced by the above production method.

In order to achieve the above object, the present inventors have repeatedly tested the additive elements and their contents, and as a result of repeated experiments, the present inventors have unexpectedly been unable to reach the conventional special steel as a cold-heat composite material having super heat resistance, ultra oxidation resistance, ultra corrosion resistance, ultra impact resistance and ultra wear resistance. Invented a special steel.

That is, the special steel as the cold-heat composite material of the present invention is 0.90 to 1.20% by weight of carbon (C), 0.50 to 1.50% by weight of silicon (Si), 0.40 to 1.00% by weight of manganese (Mn), 6.0 to 7.5% by weight of nickel (Ni). The technical characteristics are that it is composed of 23 to 30% by weight of chromium (Cr), 0.50 to 2.00% by weight of molybdenum (Mo) and the remaining iron (Fe) and other unavoidable impurities.

The content of silicon is more preferably 0.50 to 1.19% by weight, more preferably 0.81 to 1.00% by weight of manganese, and more preferably 0.76 to 2.00% by weight of molybdenum.

In addition, the special steel may be used as a guide material, or may be used as various knife materials.

The present invention also provides a method consisting of the following steps as a method for producing the special steel:

Selecting and calibrating materials such as ferroalloy and dissolving them at a temperature of 1700 to 2000 ° C;

Injecting the melt into the mold after molding sand compounding;

Cooling it and then carrying out the process of desalination and tetradecay;

The solution is heat-treated at 1010 to 1150 ° C. to remove the stress and then machined.

In another aspect, the present invention provides a special steel as a cold heat composite material produced by the manufacturing method.

First, the reason why the above-described member element has excellent heat resistance, oxidation resistance, abrasion resistance, impact resistance, precision and corrosion resistance in the extreme environment intended by the present invention is as follows.

First, the content of carbon in the constituents of the alloy of the present invention corresponds to a hyper-eutectoral steel, and carbonizes a high content of chromium to form carbides. This chromium carbide has a hardness of 30 to 35 HRC (Hardness Rockwell "C" scale), which serves to improve the wear resistance of the final product.

In addition, since nickel has a high content, the transformation point of special steel is lowered to room temperature (20 ° C.) or less, so that it is not hardened by heat generated during material movement and softening does not occur, so it does not twist and wear even in a high temperature and high pressure environment. In other words, due to the large amount of nickel, the structure of the special steel becomes "γ" iron austenite structure, and the structure is also composed of a body centered cubic lattice, so that the machined surface is smooth and the friction coefficient is small. In addition, the special steel of the present application containing a large amount of nickel does not increase the hardness even after quenching after applying heat, the hardness does not drop even when slowly cooling after adding heat.

Furthermore, since the high content of nickel and chromium of the special steel of the present application imparts excellent heat resistance and hot oxidation resistance to the alloy, it is possible to perform precise work under high temperature and room temperature for a long time, and in particular, to provide excellent wear resistance.

On the other hand, the reason for the addition of each component element constituting the special steel as the cold-heat composite material of the present invention and the reason for numerical limitation are as follows.

First of all, carbon is an invasive employment element, and has a great influence on the formation of special steel texture. The carbon content of the present invention is adjusted to the range of super-vacuum steel, when the content is less than 0.90% by weight, the state is changed to vacancy steel, and when it exceeds 1.20% by weight, the desired heat resistance and wear resistance cannot be obtained. In addition, since the content of chromium for carbide formation is relatively high, hardness and abrasion resistance are increased, but it is susceptible to impact and easily cracks and breaks.

Silicon in steel is one of the deoxygenated elements with electromagnetic properties and affects the coefficient of thermal expansion and strength. If the content of silicon is less than 0.50% by weight, there is a problem in the chemical reaction of other elements due to the lack of deoxidation. If the content of silicon is more than 1.50% by weight, the toughness is lowered due to excessive silicon content and the coefficient of thermal expansion at high temperature is excessively increased. A significant drop in physical properties is caused. In order to achieve the effect peculiar to the present invention, 0.50 to 1.19% by weight is particularly preferable.

Manganese in steel is one of the deoxidizing elements and is useful for pearlite structure strengthening effect, and is added to ensure deoxidizing and hot workability. However, if the content is less than 0.40% by weight, not only the desired strength can be secured, but also a predetermined deoxidation effect cannot be obtained or the hot workability is inferior. And when the manganese content exceeds 1.00% by weight, the desired strength is secured, but the elongation is sharply reduced and the surface properties are poor. In order to ensure heat resistance and wear resistance of the present invention, 0.81 to 1.00% by weight is particularly preferable.

Nickel in steel generally increases toughness, oxidation resistance, nonmagnetic, low transformation point high temperature impact resistance, and especially imparts corrosion resistance and thermal shock resistance to the alloy. In particular, in the present invention, as described above, the nickel content is high and the A ₁ transformation point of the alloy steel is lowered to room temperature (20 ° C.). It is composed of a lattice, so the processing surface of the material is smooth and there is no change in hardness. As a result, the precision work can be performed for a long time even in high temperature. However, if the content is less than 6.0% by weight, the desired heat resistance and wear resistance cannot be secured, and when the content exceeds 7.5% by weight, workability is significantly reduced.

In steel, chromium is generally added to increase the reinforcement, corrosion resistance, and abrasion resistance of the alloy. In the present invention, particularly, as described above, a carbide formed with a high chromium content improves the wear resistance of the alloy steel. Furthermore, due to the high content of chromium, heat and oxidation resistance are imparted to the alloy steel. However, if the content is less than 23% by weight, the desired heat resistance, oxidation resistance and wear resistance cannot be secured, and when it exceeds 30% by weight, workability is reduced as in the case of nickel.

Molybdenum in steels generally acts to prevent tempering properties, to impart reinforcing effects to the alloy, to increase heat resistance, and to specifically increase corrosion resistance to chemicals such as strong acids. In the present invention, industrial cooling water is usually sprayed. In the present invention, molybdenum is added to prevent corrosion by high temperature steam, thereby increasing the service life of special steel. Furthermore, in the present invention, in particular, like chromium, heat resistance is imparted to the alloy, thereby suppressing erosion or thermal oxidation of the present material at a high temperature, thereby improving product precision. However, if the content is less than 0.50% by weight, heat resistance, oxidation resistance, abrasion resistance, and impact resistance in the high temperature, high pressure, and high impact environments particularly desired in the present invention cannot be secured, and in particular, the corrosion resistance described above cannot be secured. This results in shortening the service life, on the contrary, in the case of more than 2.00% by weight, the workability is deteriorated, and the coefficient of linear expansion is excessively increased. In order to implement the characteristic effects of the present invention, 0.76 to 2.00% by weight is particularly preferable.

The special steel of the present invention containing the above elements has excellent heat resistance and corrosion resistance even in the harsh environment of high temperature, high pressure and high impact, and in particular, excellent wear resistance, oxidation resistance, precision and impact resistance, showing excellent performance as a cold heat composite material. do.

In particular, the special steel as a cold-heat composite material of the present invention is suitable as a material for induction guides or various knives.

Specific examples of the induction guide may include a wire guide guide in a wire rod process and a deformed steel reinforce guide guide in a hot rolled rolling process.

Specific examples of the various knives include billet cutting knives in steelmaking or continuous casting, round bar cutting knives in hot rolling, scrap metal cutting press knives in scrap steel, shearing bending knives, rebar cutting knives and thick plates ( Steel plate) cutting knife etc. are mentioned.

The method for producing special steel as the cold thermal composite material consists of the following steps:

Screening and calibrating materials such as ferroalloy and dissolving at temperatures of 1700 to 2000 ° C;

Injecting the melt into the mold after molding sand compounding;

Cooling it and then carrying out the process of desalination and tetradecay;

The solution is heat-treated at 1010 to 1150 ° C. to remove the stress and then machined.

In particular, the production method of the present invention can be prepared by pre-melting a mother alloy containing elements with a significantly higher melting point than other elements before the main melting process.

In general, the melting process of special steel manufacturing adopts a single melting process in which each element is melted by heating to a high temperature capable of dissolving all necessary elements. However, molybdenum (melting point: 2622 ± 10 ℃) has a higher melting point than other elements. In addition, the heating cost is higher than necessary, and the melting point and the scattering point are different and the oxidization property is increased, resulting in segregation, which makes it difficult to obtain desired physical properties of the final product.

Therefore, the present invention can adopt a double melting process including a process of pre-dissolving each necessary element and iron to form a mother alloy, and the manufacturing method using the mother alloy is particularly efficient in the case of molybdenum having a high melting point among the required elements. .

Among the manufacturing methods of the present invention, a manufacturing method including a master alloy manufacturing process is as follows:

The required elements are selected and dissolved at a temperature of 1700-2000 ° C .;

Injecting the lysate into an ingot case;

After cooling, the case was shelled to obtain a master alloy;

Selecting and calibrating ferroalloys and master alloys and dissolving them at a temperature of 1700 to 2000 ° C;

Injecting the lysate into the mold after molding sand molding;

Cooling it and then carrying out the process of desalination and tetradecay;

The solution is heat-treated at 1010 to 1150 ° C. to remove the stress and then machined.

Special steel as a cold-heat composite material produced by the above step is heat-resistant and corrosion-resistant, so even if used continuously for a long time at high temperature, the surface oxide film does not occur, the accuracy of the product is high. This is a part of the conventional iron-based alloy steel, even if the hardness is high at room temperature, it is not only annealing at high temperatures, especially long time use, but also a significant increase compared to the fact that work is not possible due to softening and surface oxidation due to heating will be. That is, the material of the alloy steel of the present invention does not soften and surface oxidize at high temperatures, and thus is very suitable for use as a processing tool for steel products, particularly as a guide guide and a knife material. Among them, the billet cutting knife used in the continuous casting process was only used about 15,000 times in the past, but when used in the special steel of the present invention, it was found that the wear of the blade was extremely insignificant even after using 230,000 times or more. Excellent excellence has been proven. In addition, the press knife for cutting scrap metal used in scrap steel has a variety of scrap steel itself to be cut and the structure is also rough, so that the replacement cycle of the conventionally known metal material is very short, but the special steel of the present invention This problem has been remarkably improved.

The above characteristics clearly show that when the special steel of the present invention is applied to the actual site, the replacement cycle of the processing tool can be extended, and the reworking cost can be lowered, resulting in high productivity and cost reduction effect.

Embodiments of the present invention are as follows.

Example 1

Powdered powdered 20 kg of iron-molybdenum (molybdenum content: 60% by weight) and 80 kg of scrap iron were dissolved at 1800 ° C., injected into an ingot case, cooled, and the shell was shelled to prepare a mixed master alloy of molybdenum and iron.

Example 2

The ferroalloy and the master alloy were screened and calibrated with the composition shown in Table 2, and then dissolved at a temperature of 1800 ° C., and then separately blended with a molding sand and injected into a molded mold. After cooling it, degassing and tetradecay processes were carried out, followed by solid solution heat treatment at 1100 ° C., followed by machining to obtain a wire guide guide as a final product.

Examples 3 to 5

Example 2 was repeated, but the composition of the special steel of each Example was adjusted as described in Table 2 below.

Comparative Examples 1 to 7

Example 2 was repeated, but the composition of the special steel of each comparative example was adjusted as described in Table 2 below. In Comparative Example 7 of the present comparative example, a conventional spheroidal graphite iron FCD500-7 was used.

Examples 6-9

Example 2 was repeated, but the composition of the special steel of each example was adjusted as described in Table 2 below to obtain a guide for releasing rebar in the hot rolling process as a final product.

Comparative Examples 8 to 14

Example 2 was repeated, but the composition of the special steel of each comparative example was adjusted as described in Table 2 below to obtain a guide for releasing rebar in the hot rolling process, which is a final product. In the comparative example 14, the conventional spherical graphite cast iron FCD500-7 was used.

Examples 10 to 13

Example 2 was repeated, but the composition of the special steel of each example was adjusted as described in Table 2 below to obtain the final product billet cutting knife.

Comparative Examples 15 to 21

Example 2 was repeated, but the composition of the special steel of each comparative example was adjusted as described in Table 2 below to obtain the final product billet cutting knife. Comparative Example 21 of the present comparative example used SKD61 which is a conventional hot die material.

Examples 14-17

Example 2 was repeated, but the composition of the special steel of each example was adjusted as described in Table 2 below to obtain a round bar cutting knife which is a final product.

Comparative Examples 22 to 28

Example 2 was repeated, but the composition of the special steel of each comparative example was adjusted as described in Table 2 below to obtain a round bar cutting knife which is a final product. In the comparative example 28 of this comparative example, the conventional spheroidal graphite iron FCD500-7 was used.

Examples 18-21

Example 2 was repeated, but the composition of the special steel of each example was adjusted as described in Table 2 below to obtain a scrap metal cutting press knife as a final product.

Comparative Examples 29 to 35

Example 2 was repeated, but the composition of the special steel of each comparative example was adjusted as described in Table 2 below to obtain a scrap metal cutting press knife as a final product. Comparative Example 35 of the present comparative example used SKD61 which is a conventional hot die material.

Examples 22-25

Example 2 was repeated, but the composition of the special steel of each example was adjusted as described in Table 2 to obtain a shearing cutting bending knife which is the final product.

Comparative Examples 36 to 42

Example 2 was repeated, but the composition of the special steel of each comparative example was adjusted as described in Table 2 below to obtain a shearing cutting bending knife as a final product. Comparative Example 42 of the present comparative example used SKD61 which is a conventional hot die material.

Examples 26-29

Example 2 was repeated, but the composition of the special steel of each example was adjusted as described in Table 2 below to obtain a final cutting rebar cutting knife.

Comparative Examples 43 to 49

Example 2 was repeated, but the composition of the special steel of each comparative example was adjusted as described in Table 2 below to obtain a final cutting rebar cutting knife. In the comparative example 49, the comparative example 49 used SKD61 which is a conventional hot die material.

Examples 30-33

Example 2 was repeated, but the composition of the special steel of each example was adjusted as described in Table 2 below to obtain a thick plate (steel plate) cutting knife as a final product.

Comparative Examples 50 to 56

Example 2 was repeated, but the composition of the special steel of each comparative example was adjusted as described in Table 2 to obtain a thick plate (steel plate) cutting knife as a final product. In the comparative example 56 of this comparative example, SKD61 which is a conventional hot die material was used.

number C Si Mn Ni Cr Mo Remarks Example 2,6,10,14,18,22,26,30 1.00 1.00 0.90 7.0 25 1.50 3,7,11,15,19,23,27,31 1.00 1.30 0.90 7.0 25 1.50 4,8,12,16,20,24,28,32 1.00 1.00 0.60 7.0 25 1.50 5,9,13,17,21,25,29,33 1.00 1.00 0.90 7.0 25 0.60 Comparative example 1,8,15,22,29,36,43,50 0.50 1.00 0.90 7.0 25 1.50 2,9,16,23,30,37,44,51 1.00 0.25 0.90 7.0 25 1.50 3,10,17,24,31,38,45,52 1.00 1.00 0.20 7.0 25 1.50 4,11,18,25,32,39,46,53 1.00 1.00 0.90 3.0 25 1.50 5,12,19,26,33,40,47,54 1.00 1.00 0.90 7.0 20 1.50 6,13,20,27,34,41,48,55 1.00 1.00 0.90 7.0 25 0.20 7,14,28 2.5 or more - - - - - Tensile strength: 500N / mm ² or more Strength: 320N / mm ² or more Elongation: 7% or more Hardness: 150 ~ 230HB 21,35,42,49,56 0.32-0.42 0.8 ~ 1.2 0.5 or less - 4.5 ~ 5.5 1.0-1.5 V: 0.8 ~ 1.2

Test Example 1

Table 3 shows the results of actual wire rod fabrication using the wire guide guides of Examples 2 to 5 and Comparative Examples 1-7. In Table 3, the corrected tonnage refers to the tonnage of the normal wire rod (5.6 φ) manufactured using a set of wire guide guides.

No. Correction tonnage Example 2 2,960 Example 3 2,410 Example 4 2,440 Example 5 2,120 Comparative Example 1 790 Comparative Example 2 890 Comparative Example 3 1,190 Comparative Example 4 1,040 Comparative Example 5 960 Comparative Example 6 760 Comparative Example 7 310

Test Example 2

Table 4 shows the results of manufacturing actual deformed reinforcing bars using the respective deformed bar induction guides of Examples 6 to 9 and Comparative Examples 8 to 14. The corrected tonnage in Table 4 refers to the tonnage of the deformed rebar (10 φ mm) normal product manufactured using a set of deformed bar guides.

No. Correction tonnage Example 6 3,890 Example 7 3,160 Example 8 3,170 Example 9 2,770 Comparative Example 8 1,140 Comparative Example 9 1,040 Comparative Example 10 1,520 Comparative Example 11 1,370 Comparative Example 12 1,250 Comparative Example 13 980 Comparative Example 14 520

Test Example 3

The results of cutting the actual billets using the respective billet cutting knives of Examples 10 to 13 and Comparative Examples 15 to 21 are shown in Table 5 below. Each figure in Table 5 indicates the number of times a billet (150 × 150 mm) can be cut normally using one knife.

No. Count Example 10 231,200 Example 11 197,300 Example 12 198,700 Example 13 174,200 Comparative Example 15 65,600 Comparative Example 16 72,000 Comparative Example 17 97,000 Comparative Example 18 77,900 Comparative Example 19 84,800 Comparative Example 20 58,200 Comparative Example 21 15,400

Test Example 4

The results obtained by cutting the actual round bar using the round bar cutting knives of Examples 14 to 17 and Comparative Examples 22 to 28 are shown in Table 6 below. Each numerical value of Table 6 shows the number of times a round bar (20φ) can be cut normally using one knife.

No. Count Example 14 230,800 Example 15 185,400 Example 16 190,100 Example 17 169,600 Comparative Example 22 62,700 Comparative Example 23 67,700 Comparative Example 24 92,800 Comparative Example 25 75,800 Comparative Example 26 81,100 Comparative Example 27 54,700 Comparative Example 28 16,900

Test Example 5

The results of cutting actual scrap metal using the scrap metal cutting press knives of Examples 18 to 21 and Comparative Examples 29 to 35 are shown in Table 7 below. Each figure in Table 7 indicates the number of times a scrap metal can be cut normally using one knife.

No. Count Example 18 220,300 Example 19 180,300 Example 20 181,400 Example 21 158,900 Comparative Example 29 59,900 Comparative Example 30 65,800 Comparative Example 31 88,600 Comparative Example 32 71,000 Comparative Example 33 77,400 Comparative Example 34 53,200 Comparative Example 35 16,200

Test Example 6

The results of actual shearing using the shearing cutting bending knives of Examples 22 to 25 and Comparative Examples 36 to 42 are shown in Table 8 below. Each value in Table 8 indicates the number of times that the shearing can be normally cut using one knife.

No. Count Example 22 251,700 Example 23 205,800 Example 24 207,300 Example 25 181,800 Comparative Example 36 68,400 Comparative Example 37 75,100 Comparative Example 38 101,200 Comparative Example 39 81,200 Comparative Example 40 88,400 Comparative Example 41 60,700 Comparative Example 42 18,500

Test Example 7

The results obtained by cutting the actual reinforcing bars using the respective rebar cutting knives of Examples 26 to 29 and Comparative Examples 43 to 49 are shown in Table 9 below. Each numerical value of Table 9 shows the number of times a rebar (16φ) can be cut normally using one knife.

No. Count Example 26 226,100 Example 27 183,500 Example 28 186,200 Example 29 164,500 Comparative Example 43 61,400 Comparative Example 44 67,000 Comparative Example 45 90,900 Comparative Example 46 73,500 Comparative Example 47 79,400 Comparative Example 48 54,100 Comparative Example 49 16,600

Test Example 8

The results of cutting the actual thick plate (steel plate) using each thick plate (steel plate) cutting knife of Examples 30 to 33 and Comparative Examples 50 to 56 are shown in Table 10 below. Each figure in Table 10 indicates the number of times that a thick plate (steel plate) (thickness 30 mm) can be cut normally using one knife.

No. Count Example 30 246,600 Example 31 203,700 Example 32 203,100 Example 33 176,300 Comparative Example 50 67,000 Comparative Example 51 74,300 Comparative Example 52 99,100 Comparative Example 53 78,700 Comparative Example 54 86,600 Comparative Example 55 60,100 Comparative Example 56 18,200

It can be seen from Tables 3 to 10 that the special steel of the present invention shows remarkable heat resistance, abrasion resistance, impact resistance, oxidation resistance, precision and corrosion resistance compared to FCD500-7 and SKD61 which are conventional materials.

This is a result of precisely adjusting the element and its content to fit the microstructure of the special steel to the high temperature, high pressure and high impact environment intended by the present invention, through which the special steel having an excellent effect compared to the known hot materials used in the past It is early to provide.

As described above, the special steel as the cold-heat composite material of the present invention has high heat resistance, abrasion resistance, impact resistance, oxidation resistance, precision and corrosion resistance even when used for a long time in a high temperature, high pressure and high impact environment by appropriately selecting the type and content of added elements. Therefore, the present invention can provide a particularly suitable material for the processing tool of steel products.

Claims (12)

0.90 to 1.20% by weight of carbon (C), 0.50 to 1.50% by weight of silicon (Si), 0.40 to 1.00% by weight of manganese (Mn), 6.0 to 7.5% by weight of nickel (Ni), 23 to 28% by weight of chromium (Cr), Special steel as a cold-heat composite made of 0.50 to 2.00% by weight of molybdenum (Mo) and the remaining iron (Fe) and other unavoidable impurities. The special steel of claim 1, wherein the content of silicon is 0.50 to 1.19% by weight. The special steel of claim 1, wherein the content of manganese is 0.81 to 1.00% by weight. The special steel of claim 1, wherein the molybdenum content is 0.76 to 2.00 wt%. The special steel as a cold-heat composite material according to claim 1, wherein the special steel is used as an induction guide material. The special steel as a cold-heat composite material according to claim 5, wherein the induction guide is a wire rod guide in a wire rod process or a reinforcing bar guide in a hot rolling process. The special steel as a cold-heat composite material according to claim 1, wherein the special steel is used as a knife material. The method according to claim 7, wherein the knife is a billet cutting knife in the steelmaking process or continuous casting process, round bar cutting knife in hot rolling process, scrap metal cutting press knife in scrap steel sheet, shearing bending knife, rebar cutting knife and thick plate ( Steel plate) Special steel as a cold-heat composite material, characterized in that selected from the group consisting of a cutting knife. Selecting and calibrating materials such as ferroalloy and dissolving them at a temperature of 1700 to 2000 ° C; Injecting the melt into the mold after molding sand compounding; Cooling it and then carrying out the process of desalination and tetradecay; It is subjected to machining after solidifying heat treatment at 1010 to 1150 ℃ to remove the stress, Method for producing a special steel as a cold-heat composite material of any one of claims 1 to 8, characterized in that consisting of a step of. The required elements are selected and dissolved at a temperature of 1700-2000 ° C .; Injecting the lysate into an ingot case; After cooling, the case was shelled to obtain a master alloy; Selecting and calibrating ferroalloys and master alloys and dissolving them at a temperature of 1700 to 2000 ° C; Injecting the lysate into the mold after molding sand molding; Cooling it and then carrying out the process of desalination and tetradecay; It is subjected to machining after solidifying heat treatment at 1010 to 1150 ℃ to remove the stress, Method for producing a special steel as a cold-heat composite material of any one of claims 1 to 8, characterized in that consisting of a step of. A special steel as a cold-heat composite material according to any one of claims 1 to 8, characterized in that it is manufactured by the manufacturing method of claim 9. A special steel as a cold-heat composite material according to any one of claims 1 to 8, characterized in that it is manufactured by the manufacturing method of claim 10.