KR20190081779A - Wheel blade having a high hardness and anti-wearness, and making method there-of, and Die for making a wheel blade - Google Patents

Abstract

The present invention relates to a wheel blade assembled to a shot blasting machine for shooting a shot ball (steel ball) having a size of 0.5 to 2 mm in a preprocessing process such as descaling, plating, or painting of a steel plate, or shooting the shot ball to remove sand, slag, or foreign substances adhering to the surface of a casting casted in a casting factory, and more particularly, to a wheel blade for shot blasting machine having high hardness and high wear resistance, manufacturing method therefor, and centrifugal casting mold for manufacturing of wheel blade. The wheel blade for shot blasting machine having high hardness and high wear resistance comprises: by wt%, molybdenum (Mo) of 1-3%; cobalt (Co) of 1-3%; vanadium (V) of 1-3%; chromium (Cr) of 20-30%; carbon (C) of 1.5-3.5%; silicon (Si) of 0.5-1.5%; manganese (Mn) of 0.1-0.5%; boron (B) of 1.5-4.5%; niobium (Nb) of 0.5-1%; tungsten (W) of 1-3%; aluminum (Al) of 0.1-0.2%; titanium (Ti) of 0.1-0.3%; rare-earth (RE) metal of 0.1-0.2%; and the remainder of iron (Fe) and inevitable impurities, and has a bulk hardness (HRC) of 66-68.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel blade for a short wheel having high hardness and high wear resistance, a method for manufacturing the wheel blade, and a centrifugal casting mold for manufacturing a wheel blade.

In the present invention, a shot ball or steel ball having a size of 0.5 to 2 mm is projected on the surface of a steel sheet by a pretreatment process such as de-lime of a steel sheet, plating, painting or the like, or sand or slag And more particularly to an alloy material for a wheel blade having a high hardness and a high abrasion resistance, a method for manufacturing the wheel blade, and a manufacturing method of a wheel blade. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel blade used in a shot blasting machine for projecting a steel ball, The present invention relates to a centrifugal casting mold used in a centrifugal casting mold.

As shown in Fig. 1, there is a rotating wheel (11) assembled with eight blades (12) as a component for continuously projecting a shot ball on an object. The centrifugal force of the wheel The impact is applied to this subject with a strong force, and the deodorization and the foreign matter are removed by this impact.

The wheel blade 12 used here has a shape as shown in Fig. 2, which makes contact friction with thousands of times to several tens of thousands of times per minute, and can not withstand wear with ordinary metal alloys. The shot ball used here is a high carbon alloy steel with a hardness of HRC 45 to 55, which is very high.

The material that can withstand high-hardness steel balls and continuous friction wear is the highest wear resistant material ever used in high chromium white cast iron (Cr15 ~ 18%, Mo3%). Some makers use 27Cr2Mo white cast iron, which is less abrasive than 15Cr3Mo white cast iron.

Certain companies raise their carbon content by more than 2.5% in Tungsten high speed steel products and sell them at more than twice the price, but the wear resistance is only about 50% better than the chrome white cast iron.

Short-wheel blades that have been commercialized so far are the above-mentioned products and are being used as products of great popularity all over the world. In recent years, when the shot blasting operation is performed in an automatic line that is continuously operated for 24 hours by automation of the post-casting treatment line, the service life of the wheel blade becomes very important, and the operation efficiency and productivity of the entire line are greatly improved It was a problem. In addition, the Descaling work of the steel plate is also carried out for 24 hours continuously, which has the same problem as that of the casting plant.

Until now, the commercially available wheel blades used continuously for 24 hours have been used for only about one week to ten days, resulting in long life products.

 Companies with high wheel blade usage are currently importing from abroad. In recent years, domestic manufacturers have developed new products to replace imported products, but this product could not exceed the lifespan of almost two weeks with almost the same lifetime as imports. The product developed by this company is not a product made by casting (KS-STD11) (JIS-SKD11) cold steel tool steel but it is formed by rolling or forging to a machining center. It is produced by machining and vacuum heat treatment, which is the best long life product produced domestically.

According to metallurgical data, STD11 steel is much less abrasion resistant than 15Cr3Mo white cast iron.

Nonetheless, the reason why the above-mentioned STD11-type plate machined and vacuum heat-treated products are superior in wear resistance is not a matter of material but a problem of unevenness in the texture of castings and forgings (including rolling) Or whisking, the entire surface of the structure is homogenized. Therefore, even when the heat treatment is performed, the hardness of the surface is very uniform so that the wear does not occur. On the other hand, the casting has different cooling rates depending on the position of the casting mold, This is because the organization is uneven.

On the other hand, although the casting has a high hardness of carbide having a high microscopic texture, the casting is uneven in texture and uneven wear occurs. As a result, STD11, which is an alloy tool steel for cold die, is rolled or forged Which is shorter than that of the manufactured product.

However, there is a problem that the product manufactured by rolling or forging is inferior in economic efficiency due to a complicated manufacturing process due to a high production cost, and the use life is about two weeks, I am not satisfied.

For reference, the chemical composition of STD11 species is 1.4 to 1.6% of C, 0.4% or less of Si, 0.6% or less of Mn, 11 to 13% of Cr, 0.8 to 1.2% of Mo, and 0.2 to 0.5% of V . The maximum hardness of this grade is about HRC65.

In order to solve such problems, the present invention has been made to solve the above-mentioned problems by providing iron boride which is a boride which is harder and cheaper than carbide, instead of chromium carbide, which is a carbide which depends on existing products in terms of hardness and abrasion resistance. And chromium boride, and to provide a method of manufacturing the same.

Another object of the present invention is to provide a vertical centrifugal casting mold capable of manufacturing wheel blades having high hardness and wear resistance.

In order to attain the above object, the present invention provides a wheel blade for a short wheel having high hardness and high wear resistance,

(C) is 1 to 3%, molybdenum (Mo) is 1 to 3%, cobalt (Co) is 1 to 3%, vanadium (V) is 1 to 3% (B) is 0.5 to 1%, niobium (Nb) is 0.5 to 1%, tungsten (W) is 1 to 3%, silicon (Si) is 0.5 to 1.5%, manganese To 3%, and the remainder is made of iron (Fe) and inevitable impurities, the end portion has higher impact strength than the inner portion, and the bulk hardness value is HRC 66 to 68.

The present invention also provides a method of manufacturing a wheel blade for a short chain wheel having high hardness and high wear resistance,

(C) is 1.5 to 3.5%, molybdenum (Mo) is 1 to 3%, cobalt (Co) is 1 to 3%, vanadium (V) is 1 to 3%, chromium (Cr) (B) is 0.5 to 1%, niobium (Nb) is 0.5 to 1%, tungsten (W) is 1 to 3%, silicon (Si) is 0.5 to 1.5%, manganese To 3% and the balance of iron (Fe) at 1630 占 폚 占 20 占 폚 in a high-frequency electric induction furnace,

Injecting the melted molten metal into a mold for centrifugal casting rotating at 350 to 550 RPM at a temperature of 1550 DEG C +/- 10 DEG C,

Air cooling or water-cooling the metal mold into which the molten metal is injected, followed by demolding to manufacture a wheel blade,

And heat treating the manufactured wheel blades,

Wherein the heat treatment is performed by normalizing the wheel blade at 750 to 850 占 폚, austenizing the normalized wheel blade by raising the temperature to 1000 占 폚 50 占 폚, air-cooling the austenized wheel blade, And a step of tempering the air-cooled wheel blade at 510 ° C to 580 ° C for 120 to 140 minutes.

Further, in the mold for manufacturing blades of the horizontal split centrifugal casting method of the present invention,

A vertical sprue 4 formed by the sprue cup 5; two primary inlet ports 3-1 formed at the lower portion of the sprue cup and communicating with the lower portion of the sprue and branched in opposite directions; ,

(2) in which the first injection port communicates with the first injection port and the second injection port (3-2) branches to the outside, and a wheel space shaped mold space part (1) communicating with the second injection port. Lt; / RTI >

The ring-shaped blanket (2) is in the form of a tunnel having a convex upper part, and the primary injection port and the secondary injection port are formed to be mutually shifted.

Industrial Applicability According to the present invention, it is easy to manufacture a wheel blade for a short chain having high hardness and high abrasion resistance, so that the service life of the wheel blade can be remarkably improved.

Fig. 1 is a schematic view of a wheel blade assembled and used in a short-
Fig. 2 is a perspective view of a blade mounted on a wheel,
3 is a cross-sectional view of a centrifugal casting mold for manufacturing a wheel blade viewed from the side and above,
4 is a perspective view of a centrifugal casting mold for manufacturing a wheel blade.

As described above, the Wheel Blade, which is a part of the Shot Blasting Machine, should be made of an alloy material which can withstand friction and wear between metals as a consumable tool. The most important factor that determines wear resistance is hardness. Hardness is divided into two types, one is the hardness of the microstructure and the other is the hardness of the matrix.

Here, the term "base structure" refers to a background structure, and microhardness refers to various intermetallic compounds that are mixed in a base structure. Typical examples are carbides, nitrides, main compounds and complex compounds. These intermetallic compounds have a very high hardness, a high melting point and a very high bonding strength. In addition, it is chemically stable and does not corrode well. Second, the bulk hardness must be high in order to have excellent abrasion resistance. Secondly, many intermetallic compounds such as carbide, nitride and boride which are microstructures must exist.

Where the matrix is austenite when the metal is in a molten state and it turns into a solid by cooling and becomes a pearlite structure. When the cooling rate becomes higher, it transforms into martensite. The martensite has the highest hardness. Even though 100% martensitic structure is not obtained in the casting state, it can be transformed into martensitic structure by heat treatment after casting.

Analyzing the structure of various materials used as wheel blades up to now, most of the base structure is made of martensite and the high hardness material of microstructure is composed of chromium carbide. Chromium carbide, such as 15Cr3Mo, 27Cr2Mo, and STD11 described above, is a microstructure material that improves abrasion resistance.

Table 1 shows the hardness of various carbides.

Vickers Hardness and Knoop  Hardness  material or phase hardness HV knoop  hardness Pearlite  (matrix) 300 to 800 300 to 600 Martensite  (matrix) 500 to 900 500 to 800 Cementite  ( Fe3C ) 840-1100 1,025  Chrome Carbide ( Cr7C3 ) 1,200-1,600 1,735 Moly  Carbide ( Mo2C ) 1,500 - 1,800 1,800  Tungsten Carbide ( WC . W2C, W6C ) 1,800-2,400 1,800  Niobium Carbide ( NbC ) 2,400 2,400  Silicon Carbide (SiC) 2,600 2,660  Vanadium Carbide (VC) 2,800 2,470  Titanium Carbide ( TiC ) 3,200 2,580  Boron Carbide ( B4C ) 3,700 2,800  Diamond 10,000 7,575

As shown in Table 1, the chromium carbide has a relatively low hardness value.

For the wheel blade to have the highest abrasion resistance, the bulk hardness must first be high. Bulk hardness is the composite hardness of the hardness and microhardness of the matrix and is usually expressed as Brinell hardness or Rockwell hardness. Here, Brinell hardness is used to measure the hardness of a steel with a relatively low hardness value, and Rockwell hardness is used to measure the hardness of the hardness steel.

The existing commercially available wheel blades are HRC62 to HRC64. In the case of STD11, which is the wheel blade material having the longest life described above, HRC65 is the hardness at which the maximum value can be obtained.

As mentioned above, HRC65 is the maximum hardness value obtained from the material of the existing products, and the maximum life of the continuous shot blasting machine running 24 hours is limited to 2 weeks. In order to overcome these limitations, chromium carbide is almost impossible. In the present invention, chromium boride, vanadium carbide, tungsten carbide, boron carbide and boron compound, MolybdenumBoride, Cobalt Boride and Niobium Boride are mixed together in a large amount to make the minimum hardness of HRC67 or higher.

In the case of T15 and M4, which are generally considered to have the highest abrasion resistance among high-speed steel materials, HRC 66 to 67 are the highest hardness values.

(Table 2) are hardness values of various borides.

various Boride  Melting point and hardness ( HV ) Boride Melting Point ( Figure C ) HV -Hardness Aluminum Boride ( AlB2 ) 1,350 2,000  Chrome Boride ( CrB2 ) 1,850 2,100  Cobalt Boride ( CoB ) 1,400 2,000  Iron Boride ( FeB ) 1,390 1,800  Nickel Boride ( Ni2B ) 1,220 1,800  Niobium Boride ( NbB ) 2,270 2,700  Molybdenum Boride ( MoB2 ) 2,000 2,300  Titanium Boride ( TiB2 ) 3.225 3,300  Vanadium Boride ( VB ) 2,100 2,500  Tungsten Boride ( W2B5 ) 2,800 3,000  Zirconium Boride ( ZrB2 ) 3,050 2,050

The description so far has been directed to the role of contributing to the composition and abrasion resistance of the metal structure depending on the chemical composition.

Even if the chemical components are the same, the crystal grains of the metal vary in size depending on the cooling rate during casting. If the crystal grains are large, the hardness and the mechanical properties deteriorate, and if the crystal grains are fine, the impact strength and the abrasion resistance are improved as well as the hardness.

Taking all of these characteristics into consideration, it is a technical challenge to produce the best abrasion resistance products.

To obtain the highest hardness and the highest abrasion resistance, we designed a special high chromium and boron white steel alloy alloy to obtain bulk hardness of HRC65 ~ 68 with Rockwell hardness.

Specifically, it is preferable that the carbon (C) is 1.5 to 3.5%, the silicon (Si) is 0.5 to 1.5%, the manganese (Mn) is 0.1 to 0.5%, the chromium (Cr) is 20 to 30% 1 to 3% of vanadium (V), 1 to 3% of cobalt (Co), 0.5 to 1% of niobium (Nb), 1 to 3% of tungsten (W) 0.3 to 0.3% of aluminum, 0.1 to 0.2% of aluminum (Al), 0.1 to 0.2% of hydrazine metal (RE), and 2.5 to 3.5% of boron (B).

The properties of this high chromium high boron white cast iron are not high speed steel for cutting tools requiring high temperature hardness and strength, to be. Therefore, we focused on maximizing bulk hardness and microhardness.

In the alloy design of the present invention, the carbon is alloyed to form a carbide, and its content is 1.5% to 3.5% by weight. The more effective content is 2.0% ~ 3.0%. If the content of carbon exceeds 3.5%, the ratio of boron to boron carbide increases, resulting in an increase in hardness but a stronger brittleness.

Here, silicon (Si) is a major element that improves the role of deoxidizer and castability. Generally, in high-speed steel, 0.4% or less of alloy is used, but in the present invention, 0.5-1.5% alloy is preferably used in order to improve deoxidation and castability, preferably 0.7-1.0%.

Manganese has no purpose other than deoxidizing purposes. Manganese in tool steel is helpful in increasing toughness, but it is counterproductive in increasing hardness. Therefore, it is limited to 0.1 to 0.5%. This content is also acceptable for inclusion in scrap iron or other ferroalloys.

Here, chromium is the most important element. Chromium is one of the cheapest alloying elements and its hardness is somewhat lower, but chrome carbide is an important microstructure that improves abrasion resistance. Chromium carbide includes Cr3C, Cr7C3, and Cr23C7. Cr7C3 is the best in terms of hardness and abrasion resistance. It is not easy to make carbide. Therefore, in the present invention, chromium carbide is formed more than chromium carbide to improve abrasion resistance. The hardness of chrome carbide is about HV1300 ~ 1500, but the chrome boride is about HV1800 ~ HV2100, and the chromium boride is higher. Although there are special elements with high hardness, the price is high, so we will manufacture a short wheel blade with excellent wear resistance by increasing the chrome content, which is relatively inexpensive. Here, the content of chromium (Chromium) is limited to 20 ~ 30%. When the chromium content is less than 20%, the chromium boride formation ratio is lowered and the wear resistance is lowered. When the chromium content is less than 30%, the hardness may be increased, but when the chromium content is lower than 30%, the wheel blade may be broken during use. do.

Here, vanadium (V) serves to increase the microhardness by forming an MC type carbide. In addition, it also serves to make the size of the crystal grains finer and alloys 1 to 3% by weight. For high hardness and abrasion resistance, it is possible to alloy more than 3%, but since it is an expensive element, 1 ~ 3% is suitable for special wear-resistant wheel blades.

Here, Niobium is an element that forms a typical MC type carbide together with vanadium. As shown in Table 1, however, the niobium tends to coarsen crystal grains and is expensive, so it is limited to 0.5 to 1% in the present invention.

Tungsten is an element that forms carbide and boride like molybdenum. It plays an important role in increasing micro hardness and abrasion, but it is expensive and has a specific gravity of 19.3. %.

Here, molybdenum forms carbide, but hardness of carbide such as chromium or tungsten vanadium is not high, and carbide of M2C type is formed, so hardness of carbide is relatively low as HV1,800. However, boron and boride are easily boride, and the hardness of molyboryide is also HV2,000 as in (Table 2). In addition, molybdenum is alloyed with 1 to 3% by weight in the present invention. When the content of molybdenum is increased, the abrasion resistance is greatly increased. However, in the case of the present invention, the molybdenum content is sufficient for the molybdenum because the alloy is designed for high chromium and high boron to make an inexpensive wheel blade. Therefore, it is limited to 1 to 3%.

Here, Cobalt is combined with boron to form Cobalt Boride (Table 2). CoB has a very low melting point of 1,400 ° C and easily forms boride. The hardness of CoB is very high at HV2,000. Nevertheless, in the present invention, the content of cobalt is limited to 1 to 3% by weight. Because cobalt is the most expensive element among the alloys required for the present invention, when the content is increased, the cost of the alloy rises, so 1 to 3% is suitable for producing an inexpensive wheel blade.

Boron is a key element along with chromium. Boron has very similar properties to carbon. Boron has atomic number 5, atomic weight is 10.82, carbon is atomic number 6, and atomic number is 12. Like carbon, it reacts easily with iron (Fe). The temperature of the process point of iron and carbon is as low as 1,134 ° C and the temperature of the process point of iron and boron is as low as 1,179 ° C. Boron forms boride just as carbon makes carbide. Both materials are intermetallic compounds. Unusual is that boride is harder than carbide. By using the properties of boron, the content of boron is limited to 1.5 to 4.5% by weight in the present invention. The content of boron is limited to not less than 1.5%. In the case of below, the hardness is lowered and the effect is less in the present invention. When the content is more than 4.55%, the brittleness is strong.

The blade of the present invention has a hardness higher than that of the inner side, in which the short ball contacts first, that is, the inner end of the wide width of the product, that is, the end where the short ball is projected, 68,

The reason for this is that short-ball projection causes high-speed friction, and wear occurs when hardness is less than HRC65. Conventional shot wheel blades were not able to reach HRC65 or higher and were easily worn.

In addition, in the present invention, a technical problem as important as an alloy design is a casting method, and even if a suitable alloy design is not appropriate, the desired purpose can not be achieved unless the casting method is appropriate.

This is because the single-shaft wheel blades are produced in small quantities in many varieties, and therefore there is no economic advantage in forging or rolling. Therefore, it must be produced by casting and the casting method is an important manufacturing process.

There are various casting methods such as sand casting, die casting, precision casting and centrifugal casting, and there are advantages and disadvantages for each process. Abrasive wear resistance is the most important and Impact Strength is important for the wheel blades of the short wheel as the present invention. The centrifugal casting method is good as a casting method to satisfy both of them, but the investment cost is somewhat higher because the mold cost is rather high and the centrifugal casting machine must be manufactured.

Nevertheless, the present invention adopts the vertical centrifugal casting method, and in particular, the casting method is designed as shown in FIG. 3 for casting, gas defects, shrinkage defects, uniformity and fineness of the texture. The material of the mold is STD61 (SKD61), but only S15C or S20C.

The present invention dissolves the alloy in a high-frequency electric induction furnace at 1630 ° C ± 20 ° C because the alloy is alloyed with a high melting point metal such as vanadium, tungsten, molybdenum, and niobium, and a large amount of chromium is alloyed with 20% or more to be. In order to obtain a homogeneous composition, high-temperature melting must be performed.

The reason why the molten metal is injected into the mold at 1550 ° C ± 10 ° C is that the lower the injection temperature, the finer the crystal grains by quenching and is advantageous in terms of strength and hardness, but too low in casting defects. Therefore, in the case of our products, the injection temperature is around 1550 degrees, which is the proper injection temperature.

The metal mold into which the molten metal is injected is air-cooled or water-cooled, and then the product is obtained by demolding and normalizing the product at 750 to 850 ° C for removing the casting stress.

The normalized product is heated to 950 ° C to 1050 ° C and air quenched.

The reason for air cooling is air cooling because there is a risk of cracking when water quenching or oil quenching occurs. And sufficient hardness can be obtained even by air cooling.

Thereafter, tempering heat treatment is performed at 510 ° C to 580 ° C to uniform the distribution of hardness and release thermal stress.

Further, the casting method of the wheel blade of the present invention performs vertical centrifugal casting. The reason for the centrifugal casting is that the molten material is pressurized by the centrifugal force, and the molten material is rapidly cooled by injecting the molten material into the mold, thereby making the structure finer and making the product free from porosity or shrinkage.

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

FIG. 3 is a cross-sectional view showing a front casting method of the present invention, and FIG. 4 is a perspective view showing a casting mold of the present invention.

In the mold for manufacturing a blade of the horizontal split centrifugal casting method of the present invention,

As shown in Fig. 3, a sprue 4 having a funnel shape at a central portion, a mold space portion 1 in which blades of both plate shapes are formed,

A wing shape for connecting the central sprue 4 and the sprue 2 is composed of a primary inlet 3-1 and a secondary inlet 3-2 for connecting the sprue 2 and the product space, have.

The sprue 4 is a vertical sprue 4 formed by the sprue cup 5 and has a funnel shape with a large upper part for facilitating the injection of the molten metal.

The primary injection port 3-1 is formed at a lower portion of the spout cup 5 and is formed as two primary injection ports 3-1 which communicate with the lower portion of the spout 4 and branch in opposite directions to each other .

The blanket 2 has a ring shape in which the primary injection port 3-1 is communicated to the inside and eight secondary injection ports 3-2 are branched to the outside.

The mold space part (1) is formed in the same shape as a wheel blade shape as a product space communicating with the secondary injection port.

The ring-shaped blanket (2) is in the form of a tunnel with an upper convex shape, and the primary injection port (3-1) and the secondary injection port (3-2) are formed to be mutually shifted.

When the molten metal is injected through the sprue (4) of the centrifugal casting mold rotating at 350 ~ 450 RPM, fill the bottom of the sprue first and transfer the molten metal through the first primary injection port (3-2) . Subsequently, the tangue in the tangdo is injected into the product in equal amounts through eight injection ports. This is because there is no need to install a large number of primary injection ports because the two primary entrances are installed with two entrances and the secondary entrances are offset by the rotational force of the centrifugal casting machine. This is to prevent the incoming tangles from entering the product immediately without staying in the tang.

In this case, the role of the Donas type tundo (3-2) is to slow the flow rate of the molten metal introduced through the first injection port (3-3-1) to float slag or other impurities to the upper part of the molten metal Only the pure molten metal flows into the product space and serves as a distributor to allow the molten metal to flow evenly into the eight products. Therefore, the mixing of the non-metal openings and the slag is prevented.

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

Example

    division                             Chemical composition State Landscape Heat treatment hardness C Si Cr V Mo Co Nb W B Centrifugal casting Centrifugal casting Example  One 2.0 0.8 20 1.5 1.5 1.0 0.5 2.5 2.2 HRC64 HRC66 Example  2 2.0 0.7 25 2.5 2.0 1.0 0.5 2.0 2.5 HRC65 .5 HRC67 Example  3 2.45 0.8 25 2.5 2.0 1.1 0.8 2.0 2.5 HRC65 .7 HRC68 Example  4 2.5 0.9 28 3.0 3.0 1.0 1.0 2.4 2.8 HRC66 .5 HRC68 .5 Example  5 3.0 0.7 30 2.0 2.5 1.5 1.0 2.5 3.0 HRC66 .8 HRC69 .2 Comparative Example  One 3.0 1.0 4.0 10 8.0 3 6.0 2.0 - HRC64 HRC66 Comparative Example  2 3.0 0.8 4.0 8.0 16 16 2.0 3.5 2.0 HRC65 .8 HRC69 Comparative Example 3
( 15Cr3Mo ) 3.5 0.6 16 - 3.0 - - - - Mold casting
HRC61 .5 Mold casting
HRC64 Comparative Example 4
( HSS  T15) 1.5 0.4 4.0 5 One 5 - 12 - * Forging
HRC66 .7 Comparative Example 5
( Stellite190 ) 3.2 1.0 27 - - 50 - 13.5 - Mold casting
HRC52 Mold casting
HRC58 Comparative Example  6
( SKD11 ) 1.5 0.4 13 0.5 One - - - - * Forging
HRC64 .5

Comparative Example No. 4 and Comparative Example No. 6 were not cast, but were forged or rolled.

Examples 1 to 5 are the present inventions

Comparative Example No. 1 is a high-vanadium and niobium-based alloy to which boron is not added, and a small amount of molybdenum and cobalt is also added.

Comparative Example No. 2 is an alloy of 16% of cobalt, 16% of molybdenum and 8% of vanadium, which are expensive elements, and the hardness and abrasion resistance are the best, but the price is very high.

Comparative Example No. 3 is a high chromium white cast iron, which is the most excellent in hardness and abrasion resistance among high chromium white cast iron.

Comparative Example No. 4 is an alloy having the highest abrasion resistance among ASTM standard high-speed steels (HSS), which is forged and rolled.

Comparative Example 5 is a material having the highest abrasion resistance among conventional stellite.

Comparative Example No. 6 is a material made by cold forging or rolling with cold metal steel SKD11 (KS STD11) which is JIS standard that is currently used for the longest time in the market.

The heat treatments of Examples 1 to 5, which are the inventions of the above (Table 3), were performed by normalizing heat treatment at 750 ° to 850 ° C. to remove the casting stress and then heated to 950 ° C. to 1,050 ° C. The tissue was subjected to Austenizing, followed by oil quenching, and subjected to a tempering heat treatment at 530 ° C to 580 ° C for 2 hours.

Comparative Example No. 1 was osteonized at 950 ° C and also subjected to oil quenching and tempering in the same manner.

Comparative Example 2 was subjected to quenching and tempering heat treatment in the same manner as in Example.

Comparative Example No. 3 was heated up to 1,050 ° C, subjected to air quenching after austenizing, and was not heat-treated.

Quenching and tempering were carried out according to the international standards in Comparative Examples 4 and 6.

In the above (Table 3), in Examples 1 to 5, the casting method was made by centrifugal casting.

The dissolution was dissolved in a high frequency electric induction furnace, and the maximum dissolution temperature was 1,650 ° C, and the injection temperature was 1,530 ° C. The number of revolutions of the centrifugal casting machine was 450 RPM.

Shock and wear test division After heat treatment  Hardness( HRC ) Wear test ( Loss amount ) Impact strength ( Charpy )  Example 1 HRC66  (Centrifugal casting) 24. 0 mg 7.0 ft-lbs  Example 2 HRC67  (Centrifugal casting) 21. 7 mg 6.5 ft-lbs  Example 3 HRC68  (Centrifugal casting) 20. 1 mg 7.0 ft-lbs  Example 4 HRC68 .5 (Centrifugal Casting) 20. 6 mg 7.5 ft-lbs  Example 5 HRC69 .2 (Centrifugal Casting) 19. 5 mg 6.0 ft-lbs  Comparative Example 1 HRC66  (Centrifugal casting) 33. 4 mg 7.2 ft-lbs  Comparative Example 2 HRC69  (Centrifugal casting) 19. 8 mg 7.4 ft -lbs  Comparative Example 3 HRC64 .1 (Mold Casting) 58. 6 mg 6.7 ft -lbs  Comparative Example 4 HRC65 .9 (Forging) 45. 4 mg 12. 1 ft -lbs  Comparative Example 5 HRC58  (Die Casting) 66. 0 mg 28. 7 ft -lbs  Comparative Example 6 HRC64 .3 (Forging) 74. 3 mg 14. 6 ft -lbs

As expected from the hardness test described above (Table 3), the result of the abrasion resistance and impact strength showed excellent abrasion resistance of the present invention having a high hardness (Table 4).

On the other hand, the impact strength is somewhat lower, which is inversely proportional to hardness and impact strength. Although the invention has a somewhat detrimental impact value compared to conventional products, there is no problem that it can be used as a shorting device.

 1: Blade, 4: Sprue, 3-1: First gate, 3-2: Second gate, 2: Runner,

Claims (7)

(C) is 1 to 3%, molybdenum (Mo) is 1 to 3%, cobalt (Co) is 1 to 3%, vanadium (V) is 1 to 3% (B) is 0.5 to 1%, niobium (Nb) is 0.5 to 1%, tungsten (W) is 1 to 3%, silicon (Si) is 0.5 to 1.5%, manganese To 3%, and the remainder is composed of a material made of iron (Fe) and inevitable impurities, and the end portion has an impact strength higher than that of the inner side, and the wheel blade for a short- The method according to claim 1,
Wherein the wheel blade has a bulk hardness value of HRC 66 to 68. The wheel blade of the present invention has high hardness and high abrasion resistance (C) is 1.5 to 3.5%, molybdenum (Mo) is 1 to 3%, cobalt (Co) is 1 to 3%, vanadium (V) is 1 to 3%, chromium (Cr) (B) is 0.5 to 1%, niobium (Nb) is 0.5 to 1%, tungsten (W) is 1 to 3%, silicon (Si) is 0.5 to 1.5%, manganese To 3% and the balance of iron (Fe) at 1630 占 폚 占 20 占 폚 in a high-frequency electric induction furnace,
Injecting the melted molten metal into a mold for centrifugal casting rotating at 350 to 550 RPM at a temperature of 1550 DEG C +/- 10 DEG C,
Air cooling or water-cooling the metal mold into which the molten metal is injected, followed by demolding to manufacture a wheel blade,
And a step of heat-treating the wheel blades. The method for manufacturing a blade for a short shaft having high hardness and high abrasion resistance The method of claim 3,
The heat treatment step may include:
The wheel blades were normalized at 750 to 850 占 폚,
The above-mentioned normalized wheel blades were heated to 1000 ° C ± 50 ° C and subjected to austenizing,
The austenized wheel blades were air-cooled,
And the air-cooled wheel blade is maintained at a temperature of 510 ° C to 580 ° C for 120 to 140 minutes. The method for manufacturing a wheel blade for a short-chain wheel having high hardness and high abrasion resistance A vertical sprue 4 formed by the sprue cup 5,
Two primary injection ports (3-1) formed at a lower portion of the sprue cup and communicating with a lower portion of the sprue and branched in opposite directions,
(2) in which the first injection port communicates with the inside and the second injection port (3-2) branches outward,
And a mold cavity part (1) of a wheel blade shape communicating with the secondary injection port. The mold for manufacturing a blade of the horizontal split centrifugal casting type 6. The method of claim 5,
Characterized in that the ring-shaped water bath has a tunnel shape with a convex upper part. 6. The method of claim 5,
Characterized in that the primary injection port and the secondary injection port are formed so as to be mutually shifted from each other.

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