DE10230383B4 - Stainless cast iron material with ball carbide - Google Patents

Abstract

Stainless Steel Carbide Cast Iron Material:
containing alloying constituents with iron (Fe) as a main constituent, 0.6-4.0% C and 4-15% V as constituents for forming spherical vanadium carbide, 0.01-0.15% P, 0.01-0.05% S, 0.05-1.0% Al and 0.01-0.2% Mg as the gas (hydrogen) bubble aid and 0.2-4.5% Si, 13-30% Cr, 0.2 -3.0% Mn and 4-15% Ni and / or Co as anti-corrosion matrix formers, each in wt%;
characterized in that spherical vanadium carbide having a covalent bond in crystalline form is dispersed within the spherical space in the ball-cast stainless steel cast iron material.

Description

Technical field of the invention

The The present invention relates to stainless ball-and-socket cast iron material and it is an object of the present invention to provide a stainless ball-and-socket cast iron material in which exclusively spherical vanadium carbide crystallized out at the cold melt temperature, and which certain properties such as corrosion resistance, heat resistance, abrasion resistance, toughness and processability.

State of the art

With the advancement of industrial technology requires that that the strength, heat resistance, Abrasion resistance, corrosion resistance and processability of materials in environments where apparatus much used, higher is as with earlier Materials. For example, in the field of injection molding technical Plastics reinforcements like FRP and any kind of additives to the ceramics and the Resin added to the strength, fire resistance and abrasion resistance to increase the resin moldings. As a result, due to the brittleness of the ceramic and due the reinforcement within the cylindrical resin, the resin molding system easily rubbed off, and it easily corrodes with a corrosive gas, which from the additives arises. Also subject, since then, the shape of parts in wide Areas of industry, such as As the automotive industry, more complicated becomes a higher, manufactured parts Wear or Abrasion than ever before.

At first you can the use of white Cast iron is under consideration be pulled, which is a tough one or solid cast iron is excellent abrasion resistance to obtain. This white Cast iron, which does not contain graphite within its structure, however has the disadvantage that it is very brittle, as it is with perlite and cementite is formed. Therefore, it is not easy to use of white Cast iron to obtain excellent abrasion resistance. For this Reason will be the use of spheroidal graphite cast iron with a toughness investigated, thus overcoming the disadvantage of white cast iron becomes.

cast iron with nodular or nodular cast iron, in which a structure of flake-shaped graphite crystallized in its structure, which is a spherical shape exhibits excellent toughness since the structure a crystallized substance in the structure of metallic materials a big Influence on toughness exercises. This means that the structure of a crystallized substance generally covalently or electrostatically binds, which always if it has a strong anti-metallic property, a crystal surface and a platelike one Form is formed. Under these circumstances, the tenacity is or strength low. In contrast, the structure binds one crystalline substance metallic if the metallic property is highly trained, and it will have no crystal surfaces granular or spherical Dendrite formed. Under these circumstances, toughness is due the force distribution high, even under the influence of an impact impact from the outside. In the case of spheroidal graphite cast iron, this has an excellent toughness because of the structure of crystallized within the cast iron structure flaky Graphits a spherical The form assumes when more than 0.04% of magnesium (Mg) as an ingredient available. However, it is difficult to have both a high toughness as well as to obtain a high abrasion resistance.

On the other hand, the present inventors already in the Japanese Patent Application No. 9-307951 discloses that an alloy cast iron having excellent abrasion resistance and impact resistance can be obtained by crystallizing spherical or granular VC system carbide and Fe-Cr system carbide within the structure of cast iron.

Moreover, the present inventors have in the Japanese Patent Application No. 11-122861 discloses that an alloyed cast iron having excellent abrasion resistance, corrosion resistance and impact resistance can be obtained by depositing spherical or granular carbide of the VC system in austenite.

Although the above-mentioned nodular cast iron has excellent abrasion resistance and toughness, it has the disadvantage that it has poor corrosion resistance. That in the Japanese Patent Application No. 9-307951 The disclosed alloyed cast iron has excellent abrasion resistance and impact resistance because spherical or granular VC system carbide and Fe-Cr system carbide crystallize within the structure, but has the disadvantage that it is a little worse in corrosion resistance and heat resistance. Moreover, that has in the Japanese Patent Application No. 11-122861 Although alloy cast iron disclosed an outstanding feature compared to the alloy cast iron found in the Japanese Patent Application No. 9-307951 since only VC system carbide is crystallized, however, in addition to spherical VC system carbide, granular VC system carbide is also crystallized within its structure at the same time, so that its property is not sufficiently satisfactory. Therefore, a cast iron material having abrasion resistance, toughness, corrosion resistance, heat resistance and processability is desirable.

To further implementation An extensive investigation of the alloy cast iron are the present Inventors have come to the present invention that, by only spherical Carbide of the VC system is crystallized, not just an abrasion resistance and toughness can be produced, but also excellent corrosion resistance and heat resistance, the for stainless cast iron are high, and the stainless cast iron, moreover has excellent processability. Also, with the addition of a certain additive in a certain amount as essential ingredients a further improvement in corrosion resistance and heat resistance be achieved.

Brief description of the drawings

1 Fig. 10 is a 500X magnification micrograph showing an example of the geometric sphere of the present invention.

2 Fig. 10 is a photomicrograph at 1000x magnification showing an example of the geometric sphere of the present invention.

3 Fig. 10 is a photomicrograph at 10,000 × magnification showing an example of the geometric spherical shape of the present invention.

4 is a 500X micrograph showing an example of granulation or lumps in metal histology.

5 is a 1000X photomicrograph showing an example of granulation or lumps in metal histology.

6 Figure 10 is a 10,000X magnification micrograph showing an example of granulation or lumps in metal histology.

7 Fig. 13 is a graph showing the calculated result of energy fluctuation and cohesive energy when Fe atoms are accidentally exchanged by V.

8th Fig. 14 is a graph showing the calculated result of energy fluctuation and cohesive energy when Fe atoms are accidentally exchanged with Cr.

9 is a model showing the spherical carbide production process.

10 Fig. 10 is a photomicrograph of the metallic structure of Example 1, with 1.70 cm in true 50 μm.

11 Fig. 12 is a photomicrograph (reflected electron image) of the metallic structure of Example 1, where 1.70 cm is really 50 μm.

12 Figure 5 is a photomicrograph of the metallic construction of Example 2, where 1.70 cm is actually 50 μm.

13 Fig. 10 is a photomicrograph (reflected electron image) of the metallic structure of Example 2, where 1.70 cm is actually 50 μm.

14 Figure 3 is a photomicrograph of the metallic construction of Example 3, where 1.70 cm is actually 50 μm.

15 is a micrograph (a reflected electron image) of the metallic structure Example 3, wherein 1.70 cm actually corresponds to 50 microns.

16 Figure 3 is a micrograph of the metallic construction of Example 4, where 1.70 cm is actually 50 μm.

17 Figure 3 is a micrograph of the metallic construction of Example 5, where 1.70 cm is actually 50 μm.

18 Figure 5 is a photomicrograph of the metallic construction of Example 1, where 1.70 cm is actually 50 μm.

19 Fig. 10 is a micrograph (a reflected electron image) of the metallic structure of Comparative Example 1, where 1.70 cm actually corresponds to 50 μm.

20 Fig. 10 is a photomicrograph of the metallic structure of Comparative Example 2, where 1.70 cm actually corresponds to 50 μm.

21 Fig. 10 is a micrograph (a reflected electron image) of the metallic structure of Comparative Example 2, where 1.70 cm actually corresponds to 50 μm.

22 Fig. 10 is a photomicrograph of the metallic structure of Comparative Example 3, wherein 1.70 cm actually corresponds to 50 μm.

23 Fig. 10 is a micrograph (a reflected electron image) of the metallic structure of Example 3, where 1.70 cm is actually 50 μm.

24 Fig. 10 is a photomicrograph of the metallic structure of Comparative Example 4, where 1.70 cm actually corresponds to 50 μm.

25 Fig. 10 is a photomicrograph of the metallic structure of Comparative Example 5, where 1.70 cm actually corresponds to 50 μm.

26 Fig. 10 is a micrograph (a reflected electron image) of the metallic structure of Comparative Example 5, where 1.70 cm actually corresponds to 50 μm.

27 Fig. 12 is a schematic explanatory diagram of the abrasion tester used in Test 6.

Detailed description of the invention

in the The following will be the stainless steel relating to the present invention Ball carbide cast iron material described. In terms of stainless Cast iron ball carbide material according to the present invention the stability and instability of the system using the "quantum fluctuation" to which one with the molecular orbital procedure with quantum mechanics as a fundamental concept. Based on this then the alloy composition and the Reaction temperature rated. In addition, by means of a coexisting bubble source component and by means of influence of blowing aids at the melting temperature from 1673 to 1973 K, which is the bubble reaction temperature is, tiny spherical Gas chamber (hydrogen) -Bläschen po sively distributed in the molten metal, and after in the first Line spherical Vanadiumcarbid is crystallized with covalent bond is spherical vanadium carbide largely uniform within of the spherical one Space distributed by means of a coagulation process. Accordingly is the stainless ball-and-socket cast iron material with this metallic composition, excellent in processability and durability, receive. The stainless spheroidal graphite cast iron material according to the present invention Invention includes: iron (Fe) as its main component; C and V as necessary components; P, S, Al and Mg as blister aids or the blistering supportive Medium; Ca, Ba, Sr and rare earth metals as bubble stabilizers; and Cr, Ni, Si, Mn as an anti-corrosion matrix former, wherein spherical vanadium carbide largely evenly distributed becomes.

In the following, the content unit is weight percent except for special emphasis. In addition, "globular" in this specification means that the shape in the notation of geometry is "spherical", but different from "granular" and "lumpy" in metal histology. The present inventors provide a stainless ball-and-socket cast iron material in which "ball uniformly distributed "carbide, but not" granular "and" lumpy "carbide. In the 1 to 3 is an example of "spherical" shown in the language of geometry. In the 4 - 6 For example, an example of "granular" or "lumpy" in metal histology is shown.

The alloy composition and the fusion process are important to form spherical carbide. This is because when cast iron is melted by the conventional method, flat plates of the M ₇ C ₃ type carbide are formed but the spherical carbide is not formed. In order to prevent the formation of shallow, platy M ₇ C ₃ -type carbide and to form spherical carbide, a high-temperature melt may be performed. At low temperature, flat plates of the M ₇ C ₃ -type carbide are formed. On the other hand, at high temperature, new spherical carbide is formed and formation of shallow, platy M ₇ C ₃ type carbide is prevented. The new spherical carbide formed by the high-temperature melt is vanadium carbide (hereinafter referred to as VC carbide).

Of the Reason why spherical Vanadium carbide is formed by the high-temperature melt can explained be by the stability of the alloy system is evaluated quantum mechanically. In addition, can the stability of the alloy system explained by calculating "cohesive energy" and "energy fluctuation" become.

The "cohesive energy" can be obtained be calculated by the sum of the total energy of a system Energy of isolated atoms is subtracted, the energy of a isolated atom itself as the sum of the ionization energy each Given electron.

(Wobei Δ E die Energieschwankung ist, En die Orbitalenergie und <En> der Mittelwert der Orbitalenergie ist.)The "energy fluctuation" (ΔE) is obtained, as shown in the following equation, as the standard deviation of the orbital energy (En) of all free orbitals that are not molecularly occupied, with the energy of the highest occupied molecular orbital (HOMO) in the ground state Standard is taken. (Note: The probability that an electron is excited obeys the Gibbs distribution.) AE 2 = <(En - <En>) 2 >

(Where Δ E is the energy fluctuation, En is the orbital energy and <En> is the mean of the orbital energy.)

It It should be noted that "cohesive energy" is static stability of the system, whereas the "energy fluctuation" (ΔE) defined above is the slope of an electron, to be stimulated; in other words, the reactivity (activity).

In order to calculate these concretely, the Schrödinger wave equation H Ψ = E Ψ is calculated numerically with the aid of a computer using the extended Hückel method. In the cluster of 89 Fe atoms, the calculated results of cohesive energy and energy fluctuation are 7 and 8th shown when the Fe atoms are randomly substituted by V or by Cr.

As a result, it has been found that the change in "cohesive energy" is slow when the Fe atoms are accidentally replaced by V or Cr. It has also been found that increasing the "energy fluctuation" increases as the temperature is raised. Further, it has been found that when V is added to Fe, the energy fluctuation at high temperature quickly becomes larger as compared with when Cr is added to Fe. This means that in a Fe-V binary system, it rapidly becomes unstable at high temperatures and increases reactivity. In other words, the unstabilized Fe-V binary system is rapidly stabilized at high temperature, with reaction to form VC carbide. On the other hand, since M ₇ C ₃ type carbide exists only at low temperatures but can not exist at high temperature, it is possible to form only spherical VC carbide while forming normal M ₇ C ₃ type carbide. Carbide is prevented with the use of the rapid formation reaction of the VC carbide at high temperature. That is, to form the spherical VC carbide, C and V are indispensable, and their desired addition is a 1: 1 atomic number ratio and a 1: 4 weight ratio.

Further, the balling of the VC carbide formed by melting at high temperature depends on gas (hydrogen) bubbles, as in the graphite spheroidization theory of spheroidal graphite cast iron Is accepted. That is, it is required that minute gas (hydrogen) bubbles are generated inside the molten cast iron and dispersed therein. V, which has the property of easily absorbing hydrogen, is used for this purpose. V is a preferred element for absorption or occlusion, which is clear from the study of hydrogen-absorbing alloys. Further, for distribution of minute hydrogen bubbles released from V, low-boiling-point elements such as elements belonging to Group IIa of the Periodic Table of Elements, for example, Mg, Ca, Ba and Sr are effective. Furthermore, a rare earth metal can aid the release of hydrogen bubbles since the solid solution limit of hydrogen is high. By adding P, S and Al to increase the distribution of minute gas (hydrogen) bubbles in a small amount, this effect can be stabilized. By adding these elements to molten metal at 1673-1973 K, low boiling point elements evaporate and the hydrogen bubble aids release further hydrogen bubbles. In addition, Al activates the distribution of tiny hydrogen bubbles, so that it is possible to form completely spherical carbide. In addition, in order to ensure the pourability of the cast iron, it is necessary to add an appropriate amount of C and V, and to improve the corrosion resistance, toughness and heat resistance, it is necessary that the appropriate amount of Ni, Si, Cr, Mn, etc. is added.

According to the above it is impossible, the spherical one Carbide only by melting alloy material according to a usual Process to form. To form the spherical carbide is It requires that tiny spherical gas space (hydrogen) bubbles generated These are positively distributed in the molten metal, and a spherical one Carbide with a covalent bond within the spherical space is brought to education.

A model of the spherical carbide formation process is in (a) and (b) of 9 shown. First, the tiny covalently bonded VC crystal grows along the bubble boundary ( 2 ) in the tiny spherical space ( 1 ), which is formed in the metal structure. When the grown tips meet, this results in a granularity and grows further to the inside of the bubble ( 3 ). By repeating this, the spherical VC carbide forms, the outer shape of which is spherical and which has the internal structure of a reticulated surface which is radially piled when the spherical bubble is filled by the minute covalently bonded VC crystal ( 4 . 5 ).

The stainless ball-and-socket cast iron material according to the present invention has the properties of corrosion resistance, abrasion resistance, Heat resistance, Toughness, moldability, Workability, weldability etc., all of which are strongly related to that the carbide spherical is. This means, that the corrosion of the material at the phase boundary progresses. In the present case, however, the phase boundary is spherically closed, so that the progression of corrosion is prevented. The abrasion resistance or wear resistance is guaranteed by the presence of a hard phase. Burglary however, the material progresses from the phase boundary. Therefore, the progression of the crack or fracture also becomes thereby prevents the phase from being spherical. In addition will reduces the occurrence of a stress concentration and increases the heat resistance and toughness properties are mediated when the shape is spherical. Due to the sphericity the processability is improved compared to flat platelet carbide and the accuracy of processing is increased.

As described above, the melting process is important to obtain the spherical carbide, and it is required to perform it at very high temperatures as compared with the conventional melting of cast iron. In other words, it is required that the bubbling temperature at which minute gas (hydrogen) bubbles are generated within the molten cast iron be melted. Specifically, this is done at 1673-1973 K, preferably 1773-1973 K, more preferably 1873-1973 K. When the melting temperature is less than 1673 K, minute gas (hydrogen) bubbles are not dispersed, so that spherical VC carbide is not formed that M ₇ C ₃ carbide crystallizes in the matrix and the flowability of the treated molten metal is so deteriorated that it can not be cast. On the other hand, when exceeding 1973 K, there is no problem in producing a spherical shape, but the yield of the bubble aid is deteriorated, so that it is not preferable. Furthermore, the ingredients shown below are included in the stainless steel ball-and-socket cast iron material of the present invention.

At first are C and V for crystallization of spherical VC carbide included.

The content of carbon (C) should be from 0.6 to 4.0%, preferably 1.5 to 3.5%, more preferably 2.3-3.3%. If less than 0.6% of C is contained, the hardness and mechanical property of the alloy cast iron do not change much. However, when more than 0.6% of C is contained, the hardness and the mechanical property of the alloyed cast iron are improved, but more than 4.0% of C does not merely lead to the conversion of C into platy carbide of Fe-Cr System (ie cementite), but also lowers toughness, corrosion resistance and heat resistance.

Of the Content of vanadium (V) should be 4.0-15%, preferably 5-13% more preferably 8-12%. If Less than 4.0% V can contain spherical carbide of the VC system not completely crystallized due to dispersion of the very hard carbide, and no improved effect can be expected if more are contained as 15% V, which would easily separate. none the above cases is desirable. The V content should be 3-6 times by weight, preferably 3.5-5.5 times by weight, more preferably about 4 times, based on the weight, the C content amount, since the ratio of the Atomic number in spherical VC carbide about 1: 1 (weight ratio 4: 1) is.

P, S, Mg and Al are blistering aids supportive Contain elements.

phosphorus (P), sulfur (S) and magnesium (Mg) are low-level elements Boiling point that evaporate during the high temperature melting of cast iron and generate tiny gas (hydrogen) bubbles. Al is included to improve the distribution of the bubbles.

Of the Phosphorus (P) content should be 0.01-0.15%, preferably 0.04 to 0.13% more preferably 0.08-0.12%. The reason for that is: If it is less than 0.01%, the effect of the distribution can be the bubbles can not be expected. On the other hand, if 0.15% is exceeded, one can Deposition and fragility occur. Therefore, both cases not desirable.

Of the Content of sulfur (S) should be 0.01-0.05%, preferably 0.015 to 0.03%. The reason for that is: If it is less than 0.01%, the effect may be, bubbles too distribute, not be expected, and if it's more than 0.05%, MnS (manganese sulfide) easily crystallizes and corrosion resistance decreases. Therefore, both cases not desirable.

magnesium (Mg) can be tiny bubbles provide evenly, because its boiling point (1373K) is relatively low and it is a strong ability has, spherical Carbide because it has a deoxidizing effect. As magnesium Pure Mg, Mg alloys, Mg chloride or Mg fluoride can be used and as examples Mg-Ni, Mg-Fe, Mg-Si-Fe, Mg-Cu, Mg-Al in the lumps / pieces or briquettes etc. as Mg alloy.

Of the Mg content should be 0.01-0.2% be, preferably 0.01-0.1%, even more preferably 0.01-0.08%.

The effect of dispersing tiny hydrogen bubbles can be obtained by combining aluminum (Al) with metallic elements belonging to group IIa of the Periodic Table of the Elements, e.g. As magnesium (Mg) and calcium (Ca) or mixed with rare earth metals and mixed. The content of aluminum (Al) should be 0.05-1.0%, preferably 0.08-0.8%, more preferably 0.1-0.5%. The reason for this is:
If the content is less than 0.05%, it becomes a deoxidizer because the affinity for oxygen is strong, and the effect of this ingredient can not be obtained. When the content is larger than 1.0%, the flowability decreases and the pourability deteriorates. Therefore both cases are not desirable.

nickel (Ni), silicon (Si), chromium (Cr) and manganese (Mn) are anti-corrosion matrix formers, in other words, they are considered as improving the ingredients Corrosion resistance, heat resistance and toughness, contain.

Of the Ni content should be 4.0-15% be, preferably 5.0-13%, more preferably 7-10%. The reason for this is: If the content is less than 4.0%, a martensitic occurs Metal structure on, and the structure becomes hard and brittle. On the other hand, if exceeded 15% the deposition will be encouraged and the base becomes poor. Therefore, none of these cases prefers.

Silicon (Si) is an element effective for heat resistance, and it can considerably reduce the oxidation. The content of silicon should be 0.2-4.5%, preferably 0.5-4.0%, more preferably 1.0-3.0%, be wear. The reason for this is that if it is less than 0.2%, the effect of the Si contained therein can not be obtained because the yield of V is made difficult, whereas the toughness decreases when 4.5% is exceeded. Therefore, none of these cases is preferred.

Of the Content of chromium (Cr) should be 13-30%, preferably 13-25%, more preferably 16-20% be. If less than 13% chromium is contained, can be stable Austenite (γ) not crystallized, reducing the heat resistance and the corrosion resistance across from an oxidizing solution decreases. On the other hand, if more than 30% of Cr is contained, flat platelet-shaped carbide crystallized, this deposition reducing the strength causes. None of the above cases is desirable.

When manganese (Mn) is blended, its content should be 0.2-3.0%, preferably 0.3-2.0%, more preferably 0.4-1.5%. Adding more than 3.0% Mn is not desirable for the alloy cast iron of the VC system, since it is easy to cause the deposition of M ₇ C ₃ .

The mentioned above Elements are the necessary components that come together with iron (Fe), which is the main component. In the present Invention are 0.1-1.5%, preferably 0.5-1.5%, more preferably 0.5-0.8% contain at least one or more types of selected additives consisting of Ca, Ba, Sr and alloying elements belonging to the rare earth metals and are described below are.

calcium (Ca) melts heavily into molten metal, but the Ca-Si combination, in which the bond is strong, increased by the addition of Ca. Therefore the melting point of the Mg alloy increases, and thereby the generation tiny bubbles proceed calmly in molten metal.

If Ca is added, its content is not particularly limited when it is in the range of the above stated amount, but it should 0.2-0.8% preferably 0.3-0.7%, more preferably 0.4-0.6% be.

The Boiling points of barium (Ba) and strontium (Sr) leading to the others Elements of Group IIa of the Periodic Table of the Elements belong higher than that of Mg, however, their melting points are low, and it can an effect like that of Al is obtained, distributing tiny hydrogen bubbles become. In particular, a fading phenomenon that occurs in Mg, be mitigated.

If Ba is added, its content is not particularly limited when It is included in the range of the above given quantity, it should but 0.01-1.0%, preferably 0.01-0.5%, more preferably 0.01-0.2%, be.

Farther is when Sr is admitted, whose salary is not particularly limited when this is in the range of the above stated content, he should but 0.01-1.0%, preferably 0.01-0.5%, more preferably 0.01-0.2% be.

rare earth metals have a big one Hydrogen absorption volume, since their melting point is low is and the fixed solution limit of hydrogen is high. Therefore, there is a hydrogen blowing assisting effect. In addition, the fading phenomenon can be tempered by Mg. Incidentally, it is possible to use any rare earth metal However, in this invention, as rare earth metal to use preferably uses elements belonging to the cerium group, such as for example cerium (Ce), lanthanum (La), neodymium (Nd), praseodymium (Pr), Promethium (Pm), Samarium (Sm), Europium (Eu), and Ce, La, Nd or belonging to the cerium group In particular, rare earth metals are mixed metal, which is a mixture light rare earth elements is more preferably used.

If a rare earth metal is added, its content is not particularly limited, if it is in the range of the above stated content, he should however be 0.1-1.0%, preferably 0.1-0.6%, more preferably 0.2-0.5% be.

By the way are in this invention when one or more types of alloying elements of Ca, Ba, Sr and rare earth metals are / is, one or several of the alloying elements Ca and mischmetal preferably contain and it is even more preferred that a mixture of one or more the alloying elements Ca, Ba, Sr (preferably Ca) and one or several of the alloying element types (mischmetal) of the rare earth metals is included.

Moreover, in the present invention, at least one or more selected from the group consisting of:
(a) Mo, (b) Ti, (c) B and (d) at least two or more of the alloying elements Cu, W, Zr, Co, Nb, Ta and Y are compounded to the necessary components as desired.

Molybdenum (Mo) changes effectively the deposition of graphite and has a stabilizing effect on the base or the basic structure. When Mo is mixed, its content should be 0.05-15%, preferably 0.1-13%, more preferably 1.0-7.0% be. The addition of both less than 0.05% Mo, with Mo not as described above, and more than 15% Mo, being spherical VC system carbide can not be stably crystallized due to the distribution of the very hard carbide and one with it accompanying deterioration of corrosion resistance not desirable.

moreover should, if the improvement of the heat resistance is particularly desired, the content of Mo 0.05-5% Since adding more than 5% Mo is the heat resistance a little bit worse.

titanium (Ti) is effective in denitrification and refining or refinement of the structure of the alloy cast iron. When Ti is added, its content should be 0.01-5.0%, preferably 0.05-4.5%, more preferably 0.1-3.5%. An addition of both less than 0.01% Ti, with Ti not being effective can refine, and more than 5.0% Ti, whereby the production of carbide of the V-C system in spherical Form is deteriorated with increasing deposition of Ti is not desirable.

If furthermore the improvement of the heat resistance is desired, the Ti content should be 0.01-1.0% since the addition of more than 1.0% Ti is the heat resistance a little bit worse.

boron (B) is effective in increasing the hardness in a heat treatment. If B is included, its salary should be 0.01-2.0% preferably 0.05-1.5%, more preferably 0.1-1.0%, be. The admixture of both less than 0.01% B, where B can not be effective as described above, and more than 2.0% B, which causes a deterioration of the strength are not desirable.

moreover should the B content, if the improvement of heat resistance required is, 0.01-0.5% since the addition of more than 0.5% B is the heat resistance a little bit worse.

copper (Cu), tungsten (W), zirconium (Zr), cobalt (Co), niobium (Nb), tantalum (Ta) and yttrium (Y) may be included be to requirements such as improving corrosion resistance, abrasion resistance and heat resistance, as desired fulfill. It is better to include more than two types of these elements, so that a much better effect can be obtained, though already the addition of one of these elements is effective. A random composition however, these elements do not always become a strong covalent bond cause, so if an improvement in corrosion resistance required is, a total content of more than two of these elements will be 0.2-5% should. moreover should, if an improvement in heat resistance is desired, a total content of more than one of the elements 0.2-10%, since the inclusion of a larger amount of these elements is more effective.

By the way The combination with cobalt (Co), which has the same effect as Nickel (Ni) shows to prevent a martensitic metallic Structure to be effective. Especially in the improvement of abrasion resistance or wear resistance is the proper replacement of part or all of the Ni content effective through co. This means, the total content of Ni and Co is 4.0-15%, preferably 5.0-13 °, more preferably 7-10%.

In of the present invention the above explained Composition components in addition to necessary components: C, V, P, S, Al, Mg, Ni, Si, Cr and Mn be included to desired To meet requirements and you can added, melted and poured at 1673-1973 K. Especially the inclusion is effective from: P, S, Mg, Ca, Ba, Sr and rare earth metals for the stabilization of spherical VC carbide; Ni, Si, Cr and Mn to form an anti-corrosion matrix; Not a word, Ti, B, Co, W, Zr, Nb, Ca, Y and Co for corrosion resistance; Abrasion resistance and toughness.

The stainless ball-screw type cast iron material containing this composition can be obtained by a conventional method by cooling and leaving poured molten metal in a mold. Furthermore, annealing for about two hours at 823 ± 50 K is advantageous to remove any casting stresses that occur during cooling. The remaining structure is an austenite (γ) + VC complex and heat treatment has no influence.

Farther There are no differences between the alloy cast iron and the structure that will be preserved after casting, if it is one normalizing and an annealing treatment or annealing.

Examples

It follows a detailed Description of the stainless disclosed in the present invention Kugelcarbid cast iron material based on examples. It should be noted that the present Invention is not limited to the following examples.

Conditions of Melting and the test material

At first were according to the composition in Table 1 samples of Examples 1-5 and Comparative Examples 1-5 produced.

The prepared samples were melted using 50 kg in a high-frequency induction furnace (furnace feed material MgO + Al ₂ O ₃ ). In Examples 1-5 and Comparative Examples 1-4, after the onset of melting, C, V and a corrosion resistant matrix material were melted while raising the temperature to 1923K, hydrogen bubble aids and stabilizers were added, reacted, and then the test pieces for the Microstructure observation (30 mm ∅ X 100 mm L) and mechanical test pieces collected at 1873 K in the sand mold. After casting, heat treatment was performed under air cooling after holding at 873 K for one hour.

at Comparative Example 5, after the onset of melting, was C, V and a corrosion resistant matrix material melted, raising the temperature to 1670 K, hydrogen bubble aid and stabilizer were added, reacted, and then the test pieces became Microstructure observation (30 mm ∅ X 100 mm L) and mechanical test pieces collected at the sand mold at 1623 K After pouring was a heat treatment under air cooling carried out, after one hour at 873K.

Table I is shown on the following page

(TEST 1)

Observation of the microstructure

Around to observe the microstructure became a part with 30 mm of that lower part of the materials to be tested of Examples 1-5 and the Comparative Examples 1-5 cut out and with the metal microscope and after sanding with observed by electron microscope. The metal structure and the reflected Electron images of the VC carbide were photographed.

The results of Examples 1-5 are each in the 10 - 17 shown. The results of Comparative Examples 1-5 are respectively in FIGS 18 - 26 shown.

(TESTS 2 and 3)

Tensile strength and elongation

The Tensile strength and elongation of that in Examples 1-5 and in Comparative Examples 1-5 obtained alloy cast iron Were tested. As test pieces were "JISZ2201 No. 4 test pieces for tensile tests for metallic Materials "according to" forms and dimensions more ordinary Test samples (a) used in JISG 0307 Steel Casting - General Technical Requirements ". In the test procedure these # 4 test pieces were used to test both the tensile strength as well as the elongation according to "JISZ2241 Standard Test Method for the Tensile strength of metallic materials "to determine.

The Results of tensile strength and elongation are shown in Table 2.

(TEST 4)

impact test

Of the Impakt or the notch effect of in Examples 1-5 and in Comparative Examples 1-5 obtained alloy cast iron was examined. There were JIS No. 3 test pieces without notches with a 10 × 10 × 55 mm - extent used being surface oxide the test pieces was removed with a belt-like abrasion system before a Charpy impact test according to the test method: "JISZ2242 Metallic material impact test method "was performed. Split or notched surfaces were observed using surfaces were excluded with defects.

The Result of the impact test is shown in Table 2.

(TEST 5)

hardness determination

The hardness of the alloyed cast iron obtained in Examples 1-5 and Comparative Examples 1-5 was examined. The "C scale (H _R C)" of "Rockwell hardness (H _R )" was used in the test method according to the "Rockwell hardness test method" as in "JISZ2245" as an index (ie, hardness According to a particular equation, differences between the depths of the indenter impressions of the rated load were determined before and after the test load was applied to the test piece, as measured by the following procedure: First, a nominal load is applied to a test piece and further a test load is applied and then the test piece is returned to nominal load using diamond indenters and spherical indenters).

The Result of hardness determination is shown in Table 2.

(TEST 6)

Abrasion test or wear test

Using the in 27 The abrasion tester shown in FIG. 1 was the alloyed cast iron obtained in Examples 1-5 and Comparative Examples 1-5 according to the following abrasion test method examined.

A square bar of 10 mm × 50 mm in height was cut as a test piece from the ordinary test piece of 25 mm square × 50 mm height and placed in a screw holder ( 2 ) and then cut to 12 mm height. Further, as the grindstone for contact with the test piece, a grindstone of ∅25 mm × 2 mm having a type 28 abrasive grain was used, with a shank containing commercially available Al ₂ O ₃ materials sintered at about 1473 K, approximately 30% Tonbinder was mixed.

All surfaces of the test sample were measured using a belt type abrader with a type no. 80 grit rubbed, paying special attention was directed to the fact that in particular the surfaces, the the whetstone touched, balanced horizontally.

To Confirmation, that on the surfaces The test specimens did not adhere to their weight with a precision balance given as pre-abrasion test weight.

Secondly The test sample was after a holder part with the test area after arranged below and fastened with locking screws from the sides, the test surface using an alignment holder, which is the same Height like the whetstone was set level.

After adjusting the equilibrium or the compensation of the tester, 0.2 kg of a load weight ( 3 ) was placed exactly on top of the test sample and free movement of the test sample was suppressed by using spring-stop oscillators ( 5 ) on the other side of the scale ( 4 ) were attached to the test sample.

In This state became the abrasion tester at a rotational speed started from 1700 rpm. Within the rotation time of 90 seconds was at 30 and 60 seconds after starting with a surface treatment grindstone a surface treatment for preventing dulling of the grindstone with the shank carried out.

After this the test is over was the test sample, from the polishing powder that was on the test sample was present, was wiped off, again with a precision balance scaled. The difference of the test sample weight before and after Test was rated as abrasion amount.

The The result of the abrasion test is shown in Table 2.

(TEST 7)

Corrosion resistance test

Using the alloyed cast iron obtained in Examples 1-5 and Comparative Examples 1-5, corrosion resistance to H ₂ SO ₄ (7N) and HCl (1N) was examined. As a test method, after a test sample of 10 mm ^{3 was} completely finished (emery surface finish Type No. 320), it was degreased and its weight and surface area were measured. Each test piece was separately placed in a 500 ml flask in which 300 ml each of H ₂ SO ₄ (7N) and HCl (1N) were poured. After the test piece boiled in H ₂ SO ₄ (7N) and the test piece soaked in HCl (1N) at room temperature for 140 hours and dried, the weight and the surface area of each test piece were measured. Subsequently, the corrosion loss was determined in mg / cm ² .

In addition was a corrosion resistance test as above using SUS304, which is in terms of corrosion resistance is excellent.

Farther For example, the composition of SUS304 is shown in Table 3.

The Results of Corrosion Resistance Tests Tables 2 and 3 are shown.

TABELLE 3 C Si Mn P S Ni Cr Fe + Verunreinigungen SUS304 0,07% 0,8% 1,5% 0,04% 0,01% 8,0% 18,0% Rest Table 2 is shown on the following page.

TABLE 3 C Si Mn P S Ni Cr Fe + impurities SUS304 0.07% 0.8% 1.5% 0.04% 0.01% 8.0% 18.0% rest

(TEST 8)

Underwater pump and impeller test

An underwater pump and an impeller within a sewage treatment system of a mud storage box were examined in the test. The sludge storage tank actually had a pH of 4-7 (designed for pH 7-9), and as a foreign matter, sand was mixed with the sludge. In addition, the concentration of the mud was about 3%. The composition of the sludge storage container treatment system was analyzed by X-ray fluorescent technique with a sludge concentration of 0.5% and the concentrations of FeSO ₃ 18.0%, SO ₃ 6.1%, Al ₂ O ₃ 4.2%, SiO _{2 2 was} 8.8%, V ₂ O _{5 was} 2.9%, and organic matter (C) was 63.0%. The pH during the study was 5.0.

Wheels or With impellers an outer diameter ∅ 230 mm were prepared using the alloy cast iron of Example 3 and conventional Cast iron FC200 as material for the test test produced, with the impeller for wastewater treatment was arranged on the underwater pump. As a result, that was Weight of the impeller from the alloy cast iron of Example 3 after 1003 hours running time reduced by 0.15%. In contrast, the weight of the wheel was from the conventional Cast iron reduced by 9.00% after 844 hours. Therefore was the abrasion resistance or wear resistance and corrosion resistance of the alloy cast iron of the example Impeller far better than that of the impeller from the conventional Cast iron.

Effects of the present invention

As above in detail explained, is characterized by the recited in claim 1 stainless steel ball-cast iron material of this invention shown that spherical carbide at much colder melting temperatures than conventional crystallized due to the attached special bubble aids. It also has excellent abrasion resistance, toughness and processability and has a corrosion resistance and heat resistance on, which is equal to that of stainless steel, since that in the Structure crystallized carbide is produced in spherical form.

The in claim 2 listed stainless steel ball-cast iron material This invention has excellent abrasion resistance and heat resistance and also a greatly improved corrosion resistance.

The in one of the claims 3 or 4 listed Stainless ball-cast iron cast iron material of this invention has a excellent abrasion resistance and heat resistance and greatly improved corrosion resistance on.

The in one of the claims 5 or 6 listed Stainless ball-cast iron cast iron material of this invention has a excellent abrasion resistance and heat resistance and greatly improved corrosion resistance on.

Claims (5)

Stainless steel ball-cast iron material: containing alloying components with iron (Fe) as a main component, 0.6-4.0% C and 4-15% V as constituents for forming spherical vanadium carbide, 0.01-0.15% P, 0.01 -0.05% S, 0.05-1.0% Al and 0.01-0.2% Mg as gas (hydrogen) bubble aid and 0.2-4.5% Si, 13-30% Cr, 0.2-3.0% Mn and 4-15% Ni and / or Co as anti-corrosion matrix formers, each in wt%; characterized in that spherical vanadium carbide having a covalent bond in crystalline form is dispersed within the spherical space in the ball-cast stainless steel cast iron material. Stainless Steel Carbide Cast Iron Material: containing Alloy constituents with iron (Fe) as the main constituent, 0.6-4.0% C and 4-15% V as constituents for forming spherical vanadium carbide, 0.01-0.15% P, 0.01-0.05% S, 0.05-1.0% Al and 0.01-0.2% Mg as a gas (hydrogen) bubble aid and 0.2-4.5% Si, 13-30% Cr, 0.2-3.0% Mn and 4-15% Ni and / or Co as anti-corrosion matrix formers, each in wt .-%; thereby characterized in that the stainless ball-and-socket cast iron material is melted by melting Alloy components at 1673-1973 K, which is the bubbling reaction temperature is made to be tiny, spherical spaces of gas (hydrogen) bubbles in the We sentlichen uniformly within to disperse the molten metal; and in that spherical vanadium carbide with a covalent bond in a crystalline form within the spherical Space is dispersed in the stainless ball-cast iron cast-iron material. A stainless ball-cast iron cast iron material according to claim 1 or 2, characterized in that additionally 0.1-1.5% alloying ingredients one or more of Ca, Ba, Sr and rare earth metals in addition to Gas (hydrogen) -Bläschen stabilizer in the stainless spherical carbide cast iron material each in wt .-% present. Stainless steel ball-cast iron material after one the claims 1-3 thereby characterized in that the stainless ball-and-socket cast iron material is a mixture of said Alloy constituents and at least one or more, selected from the group consisting of: (a) 0.05-15% Mo; (b) 0.01-5% Ti; (C) 0.01-2% B; and (d) 0.2-5% at least two or more of the alloy components Cu, W, Zr, Co, Nb, Ta and Y. Stainless steel ball-cast iron material after one the claims 1-3, by characterized in that the stainless steel ball-cast iron material comprises a mixture of said alloying ingredients and at least one or more, selected from the group consisting of: (a) 0.05-5% Mo; (b) 0.01-1.0% Ti; (C) 0.01-0.5% B; and (d) 0.2-10% at least two or more of the alloy components Cu, W, Zr, Co, Nb, Ta and Y.