WO2018150645A1 - Heat resistant spheroidal graphite cast iron with excellent creep resistance - Google Patents
Heat resistant spheroidal graphite cast iron with excellent creep resistance Download PDFInfo
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- WO2018150645A1 WO2018150645A1 PCT/JP2017/039551 JP2017039551W WO2018150645A1 WO 2018150645 A1 WO2018150645 A1 WO 2018150645A1 JP 2017039551 W JP2017039551 W JP 2017039551W WO 2018150645 A1 WO2018150645 A1 WO 2018150645A1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B9/00—Stoves for heating the blast in blast furnaces
- C21B9/02—Brick hot-blast stoves
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/04—Cast-iron alloys containing spheroidal graphite
Definitions
- the present invention relates to a heat-resistant spheroidal graphite cast iron having excellent creep resistance.
- FIG. 2A and 2B show a conceptual diagram of the structure of the heat storage chamber in the hot stove, and the process of storing heat and supplying hot air in the heat storage chamber.
- the heat storage chamber heats the checker brick 1 by blowing high-temperature checker brick heating gas 3 previously generated in a combustion chamber separate from the heat storage chamber into the checker brick 1 provided in the heat storage chamber from the upper part of the heat storage chamber.
- FIG. 2A heat storage process
- air 6 heated by the heat storage chamber having a low temperature to be heated is introduced into the heat storage chamber as necessary, and the heat storage chamber is heated by the heat of the stored checker brick 1
- the air 6 heated by the heat storage chamber is supplied as hot air 5 to the blast furnace (FIG.
- the exhaust gas 4 exhausted in the heat storage process through the checker receiving member 2 has a high temperature of about 150 to 400 ° C. even though it loses heat by transferring heat to the checker brick 1 of the heat storage member.
- the member 2 is required to have heat resistance.
- FCD spheroidal graphite cast iron
- FCD ductile cast iron or nodular cast iron
- Mg is generally added as a cast iron component and inoculated with an Fe—Si alloy.
- it can be realized by adding appropriate amounts of Ce and Ca.
- Patent Document 1 discloses that a support assembly for supporting a heat storage grid refractory brick includes a ferrite matrix and a dispersion of graphite particles, and the shape of the graphite particles is substantially the same.
- the exhaust temperature can exceed 600 ° C. or even 700 ° C. by using cast iron which is a cast iron structure having a worm-like or nodular shape.
- the cast iron material is composed of carbon 2.0-3.8%, silicon 1.8-5.0%, manganese 0.1-1.0%, phosphorus 0.1% or less, sulfur 0 .1% or less, optionally molybdenum 1.25% or less, unavoidable impurities and balance iron.
- FCD spheroidal graphite cast iron
- the invention described in Patent Document 1 is substantially composed of FCD and Mo.
- Added alloy cast iron Since this FCD is spheroidal graphite cast iron, it has high strength and high toughness, and has a certain degree of heat resistance. However, the hot air blown into the blast furnace is heated to a higher temperature to reduce the heating coke charged in the blast furnace. In order to achieve this, since it is required to improve the temperature of the heat storage chamber, further heat resistance is required.
- the blast furnace 1 In particular, in a checker-receiver member that is loaded with a high weight of about 2000 tons f at a high temperature of the actual large-scale actual machine level, for example, by raising the exhaust gas temperature from 400 ° C. to 500 ° C. by 100 ° C., the blast furnace 1
- the annual coke consumption per base can be reduced by tens of thousands of tons, and cost reduction of several hundred million yen per year can be expected.
- the checker receiving member Since the checker receiving member has a higher temperature than conventional and a load as high as 2000 tons f is applied, it is necessary to set the required durability at a high temperature.
- the allowable stress of materials used at high temperatures is the design stress specified by “ASME Code” (American Society of Mechanical Engineers), ie, “1 ⁇ 4 of high temperature tensile strength” and “10 ⁇ 5 % / hour”. Is determined by the smaller value of “the stress at which the creep rate is generated” (“% / hour” is the deformation rate per hour).
- the broken line in FIG. 1 shows the relationship between the temperature and the “stress that generates a creep rate of 10 ⁇ 5 % / hour” in FCD. Further, the solid line in FIG. 1 represents the high strength characteristic targeted by the present invention.
- FCD which is a conventional material, reverses the “high temperature tensile strength 1/4” and “stress at which a creep rate of 10 ⁇ 5 % / hour” occurs at around 400 ° C. as the temperature rises. “Stress that generates a creep rate of 10 ⁇ 5 % / hour” becomes smaller.
- the creep strength is rate-determining, and the maximum allowable temperature is determined by design stress and design conditions. That is, if the conventional technique shown by the broken line can be improved to the characteristic shown by the solid line, the stress at which the creep rate of 10 ⁇ 5 % / hour is improved, and the maximum allowable temperature of the checker metal receiving member can be improved.
- Patent Document 1 describes that the exhaust temperature can exceed 600 ° C. or even 700 ° C., but does not mention high-temperature creep characteristics, and does not disclose actual high-temperature strength. .
- the gist of the present invention for solving the above problems is as follows.
- (1) C: 3.0% to 4.3% by mass%, Si: 1.5% or more, less than 3.0%, Mn: 0.4% or less, Graphite spheronizing agent comprising at least one of Mg, Misch metal, Ce, and Ca: 0.010 to 0.15%, P: 0.20% or less, S: 0.050% or less, Ni: 0.50 to 1.5%, Cu: 0.20% or more, less than 0.8%, Mo: 0.50 to 1.5%, Containing A heat-resistant spheroidal graphite cast iron excellent in creep resistance, characterized in that the balance consists of Fe and inevitable impurities.
- a heat storage brick support member for a hot stove comprising the heat-resistant spheroidal graphite cast iron according to (1).
- a checker-receiver member for a hot stove comprising the heat-resistant spheroidal graphite cast iron according to (1).
- the creep strength and high-temperature tensile strength of spheroidal graphite cast iron can be improved, and by using it suitably as a heat-resistant structural material such as a heat storage brick support member of a hot blast furnace, a checker metal receiving member, Thermal efficiency such as operation can be improved, and resources and costs can be reduced.
- the conceptual diagram explaining the use temperature of FCD in high temperature, the relationship between tensile strength and creep strength, and the target characteristic of this invention The schematic diagram which shows the structure of the thermal storage chamber of a hot stove, and the thermal storage process in a thermal storage chamber.
- the present inventor examined various additive elements in order to improve the high temperature creep strength based on the component composition used for FCD. As a result, it was found that the high-temperature creep strength and tensile strength of spheroidal graphite cast iron are improved by adding a predetermined amount of Mo, Cu, and Ni in combination. Hereinafter, the reason for limitation of each component is demonstrated. All percentages relating to the components are mass%.
- Cast iron originally contains about 1.7 to 4.5% by mass of carbon for improving castability.
- spheroidal graphite and carbides such as cementite contained in pearlite structure
- the range is defined as 3.0 to 4.3%. If it is less than 3.0%, spheroidal graphite cast iron has a poorer molten metal flow than flake graphite cast iron. Therefore, castability deteriorates and casting defects and shrinkage due to poor molten metal flow occur, resulting in poor formation of spheroidal graphite and carbide. , Lack of strength.
- primary crystal graphite (hypereutectic graphite) is likely to be generated because it exceeds the eutectic composition.
- Generation of primary graphite is not preferable because the toughness of cast iron decreases and the elongation deteriorates.
- dross and segregation occur, resulting in a casting defect, graphite is not sufficiently spheroidized and dispersed, the toughness of cast iron is reduced, and the elongation is deteriorated.
- a more preferable lower limit range is 3.5% or more, and a further preferable lower limit range is 3.7% or more.
- a more preferable upper limit range is 4.0% or less, and a more preferable lower limit range is 3.9% or less.
- Si 1.5 to 3.5% Si is added in order to facilitate crystallization of graphite, and in combination with the effect of adding Mg, which will be described later, to spheroidize graphite and to improve castability. If it is less than 1.5%, the above effect is not sufficient, and sufficient graphite does not crystallize, so that the strength is insufficient. On the other hand, if it exceeds 3.5%, the amount of crystallized graphite becomes too large, and a flake crystallized product that does not spheroidize is generated. When graphite is crystallized in the form of a piece, stress concentrates on the interface with graphite and deteriorates strength, toughness, and elongation. A more preferred lower limit range is 2.0% or more, and a more preferred lower limit range is 2.5% or more. On the other hand, a more preferable upper limit range is 3.0% or less, and a more preferable lower limit range is 2.7% or less.
- Mn 1.0% or less Mn is added in a small amount to ensure deoxidation and toughness in ordinary steel smelting. If it exceeds 1.0%, hard and brittle manganese carbide is likely to be produced, and the strength, toughness and elongation are deteriorated.
- a more preferable upper limit range is 0.6%, and a more preferable upper limit range is 0.4% or less.
- the lower limit is not necessarily limited, but it is preferably 0.1% or more in order to reduce Mn more than necessary to increase the cost and to ensure deoxidation and toughness. More preferably 2% or more.
- Graphite spheroidizing agent comprising at least one of Mg, Misch metal, Ce, and Ca: 0.010 to 0.15%
- a graphite spheroidizing agent comprising at least one of Mg, Misch metal, Ce, and Ca is added to spheroidize the crystallized graphite. If it is less than 0.010%, the graphite cannot be sufficiently spheroidized, and flake graphite is produced. On the other hand, if it exceeds 0.15%, hard and brittle carbides are produced, and the toughness and elongation deteriorate.
- a more preferable graphite spheroidizing agent is Mg added alone or Mg and Ce and Ca are used in combination.
- P 0.20% or less
- P (phosphorus) is an element inevitably contained in cast iron, but if it exceeds 0.20%, castability deteriorates and casting defects tend to occur, and toughness and elongation deteriorate. Therefore, the content is limited.
- a more preferable range is 0.10% or less.
- S 0.050% or less S (sulfur) is an element inevitably contained in the cast iron as in the case of P. However, if it exceeds 0.05%, the spheroidization of graphite is inhibited, so the content is limited. A more preferable range is 0.02% or less.
- Ni 0.50 to 1.5%
- the tensile strength at high temperature is improved. If it is less than 0.50%, the effect of improving the strength is not sufficient, and if it exceeds 1.5%, the toughness and elongation are lowered, and casting defects are likely to occur.
- a more preferable lower limit range is 0.8% or more, and a further preferable lower limit range is 1.0% or more.
- a more preferable upper limit range is 1.3% or less, and a more preferable upper limit range is 1.1% or less.
- Cu 0.20 to 1.0%
- the creep strength at high temperature is improved. If the content is less than 0.20%, the effect of improving the creep strength is not sufficient. If the content exceeds 1.0%, the toughness and elongation are reduced, and a Cu-rich phase is easily generated and the strength is also reduced.
- a more preferable lower limit range is 0.4% or more, and a further preferable lower limit range is 0.5% or more.
- a more preferable upper limit range is 0.8% or less, and a more preferable upper limit range is 0.6% or less.
- Mo 0.50 to 1.5%
- the creep strength at high temperature is improved. If it is less than 0.50%, the effect of improving the creep strength is not sufficient, and if it exceeds 1.5%, an intermetallic compound phase composed of a hard carbide is generated, and the toughness and elongation are lowered, and the strength is also lowered.
- a more preferred lower limit range is 0.6% or more, and a more preferred lower limit range is 0.8% or more.
- a more preferable upper limit range is 1.2% or less, and a more preferable upper limit range is 1.0% or less.
- the balance other than the above is Fe and inevitable impurities.
- the inevitable impurities mentioned here include the elements and the amount of elements that are inevitably contained in the production process of producing ordinary cast iron, and each is clearly specified to the limit that is possible with the current technology. It is not a statement to the effect that impurity elements that are not used are reduced.
- inevitable impurities refer to elements contained rather than intentionally added elements for a specific purpose. For example, adding an expensive modifying element such as V significantly increases the cost, especially in large products such as structural materials, and is out of the scope of the present invention.
- As a measure of impurities it is allowed to contain elements of the kind and amount that are allowed by the FCD standard.
- the spheroidal graphite cast iron of the present invention exhibits the effects of the invention by determining the component composition as described above. For production, it is melted by a usual method, adjusted for components, cast, and cast as it is. It can be manufactured by releasing it.
- the structure of spheroidal graphite cast iron produced by as-casting is a ferrite structure with an area ratio of 30 to 70% and the remaining pearlite structure, excluding the spheroidal graphite part.
- Creep test result The creep test was performed using a tensile test piece prepared by melting and casting cast iron, producing an ingot by as-casting, and cutting out in accordance with the provisions of JIS Z 2271.
- the result of having analyzed the component of the test piece was the component range shown in Table 1.
- the creep test was performed at 400 ° C., 450 ° C., 500 ° C., and 550 ° C.
- the test time is 300 to 1200 hours as the total time including the transition zone and acceleration zone, and the elongation over time during steady-state creep is measured at various temperatures at various temperatures. Creep speed was calculated. Then, a relational expression between the minimum creep rate at each temperature and the corresponding load stress is obtained by extrapolation, and the load stress at 10 ⁇ 5 % / hour from the relational expression (at the same temperature and constant load, The stress at the time of deformation of 10 ⁇ 5 % in one hour was calculated individually and evaluated as the creep strength.
- Comparative Examples 1 to 12 where the material is FCD since none of Ni, Cu, and Mo is added, the creep strength is low. Furthermore, Comparative Examples 13 to 15 in which Ni is added to FCD are not sufficient, although improvement in creep strength is observed.
- Examples 1 to 6 according to the present invention the minimum creep rate was sufficiently slow, and it was confirmed that it could withstand the load even at high temperatures.
- the creep strength was 7.6 kgf / mm 2 at a temperature equivalent to that of Comparative Examples 5 to 8, and the strength was increased by a factor of 10 or more.
- sufficient creep strength could be maintained even at 550 ° C.
- Examples 1-1 to 7-2 exceeded each of Comparative Examples 1-1 to 14-2 at the same temperature in any of the high-temperature tensile tests at 300 to 600 ° C. .
- Tables 2 and 3 in light of “ASME Code” regarding allowable stress of materials used at high temperatures at temperatures of 450, 500, and 550 ° C., “1/4 of high temperature tensile strength” and “10 ⁇ 5 ”.
- the smaller of “Stress at which a creep rate of% / hour is generated” is confirmed to be “Stress at which a creep rate of 10 ⁇ 5 % / hour” is used. It was confirmed that the “stress at which a creep rate of 10 ⁇ 5 % / hour is generated” must be high.
- the present invention is excellent in high-temperature strength, high-temperature creep resistance, and excellent heat resistance, and therefore can be applied to various high-temperature materials that continue to be loaded at high temperatures, such as engines, boilers, and heating furnaces.
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Abstract
Heat resistant spheroidal graphite cast iron with excellent creep resistance that contains, in mass%, C: 3.0%-4.3%, Si: 1.5% to less than 3.0%, Mn: 0.4% or less, a graphite spheroidizing agent made of at least one of Mg, mischmetal, Ce and Ca: 0.010-0.15%, P: 0.20% or less, S: 0.050% or less, Ni: 0.50-1.5%, Cu: 0.20% to less than 0.8%, and Mo: 0.50-1.5%, the balance being made of Fe and unavoidable impurities.
Description
本発明は、耐クリープ性に優れた耐熱球状黒鉛鋳鉄に関する。
The present invention relates to a heat-resistant spheroidal graphite cast iron having excellent creep resistance.
製銑のための高炉用熱風炉の蓄熱室に備えられたチェッカー煉瓦を支持するチェッカー受金物部材には、高強度、高靱性に加えて、耐熱性が求められている。
In addition to high strength and high toughness, heat resistance is required for a checker metal receiving member that supports checker bricks provided in a heat storage chamber of a blast furnace hot stove for iron making.
図２Ａ、図２Ｂに、熱風炉における蓄熱室の構造概念図と、蓄熱室内の蓄熱と熱風供給の過程を示した。前記蓄熱室は、蓄熱室中に設けられたチェッカー煉瓦１に蓄熱室の上部から予め蓄熱室とは別の燃焼室で生成させた、高温のチェッカー煉瓦加熱ガス３を吹き込んでチェッカー煉瓦１に熱を蓄熱しておき（図２Ａ、蓄熱過程）、必要に応じて、加熱したい温度の低い、蓄熱室により加熱される空気６を蓄熱室に導入し、蓄熱されたチェッカー煉瓦１の熱により蓄熱室により加熱される空気６を加熱することで、この蓄熱室により加熱される空気６を熱風５として高炉に供給する（図２Ｂ、熱風供給過程）。
この蓄熱過程時（図２Ａ）に、チェッカー煉瓦加熱ガス３は、加熱を終えて熱を失い、ガスが通るように構成されたチェッカー受金物部材２を通して、下部から外部へと高温の排ガス４として排気される。 2A and 2B show a conceptual diagram of the structure of the heat storage chamber in the hot stove, and the process of storing heat and supplying hot air in the heat storage chamber. The heat storage chamber heats the checker brick 1 by blowing high-temperature checkerbrick heating gas 3 previously generated in a combustion chamber separate from the heat storage chamber into the checker brick 1 provided in the heat storage chamber from the upper part of the heat storage chamber. (FIG. 2A, heat storage process), air 6 heated by the heat storage chamber having a low temperature to be heated is introduced into the heat storage chamber as necessary, and the heat storage chamber is heated by the heat of the stored checker brick 1 By heating the air 6 heated by the above, the air 6 heated by the heat storage chamber is supplied as hot air 5 to the blast furnace (FIG. 2B, hot air supply process).
During this heat storage process (FIG. 2A), the checkerbrick heating gas 3 loses heat after heating, and passes through a checker metal receiving member 2 configured to allow the gas to pass from the bottom to the outside as high-temperature exhaust gas 4. Exhausted.
この蓄熱過程時（図２Ａ）に、チェッカー煉瓦加熱ガス３は、加熱を終えて熱を失い、ガスが通るように構成されたチェッカー受金物部材２を通して、下部から外部へと高温の排ガス４として排気される。 2A and 2B show a conceptual diagram of the structure of the heat storage chamber in the hot stove, and the process of storing heat and supplying hot air in the heat storage chamber. The heat storage chamber heats the checker brick 1 by blowing high-temperature checker
During this heat storage process (FIG. 2A), the checker
チェッカー受金物部材２を通して蓄熱過程において排気される排ガス４は、蓄熱部材のチェッカー煉瓦１に熱を移動させて熱を失ってはいても、１５０～４００℃程度の高温であるので、チェッカー受金物部材２には耐熱性が要求される。
The exhaust gas 4 exhausted in the heat storage process through the checker receiving member 2 has a high temperature of about 150 to 400 ° C. even though it loses heat by transferring heat to the checker brick 1 of the heat storage member. The member 2 is required to have heat resistance.
このようなチェッカー受金物部材として、従来、ＦＣやＦＣＤなどの鋳鉄が採用されている。中でも、ＦＣＤ（球状黒鉛鋳鉄）は、ダクタイル鋳鉄あるいはノジュラ鋳鉄とも呼ばれ、母相鉄中に、鋳鉄中の炭素分が黒鉛として球形に析出している組織を呈している。このような球状黒鉛鋳鉄組織とするには、鋳鉄成分として、一般的にＭｇを加え、Ｆｅ－Ｓｉ合金で接種を行う。あるいは、さらにＣｅ、Ｃａを適量添加することで実現できる。黒鉛が球形に析出する球状黒鉛組織となることにより、黒鉛と母相との界面の応力集中が緩和され、亀裂が進行しにくくなる。そのため、析出している黒鉛が片状である片状黒鉛鋳鉄に比べて、高強度、高靱性（高延性）、高耐摩耗性能を付与することができる。さらに、鋳造用であるので、形状設計を比較的自由に行うことができる。自由に形状設計できるため、自動車部品や建材等にも利用することが容易となる。
Conventionally, cast iron such as FC and FCD has been adopted as such a checker-receiver member. Among these, FCD (spheroidal graphite cast iron) is also called ductile cast iron or nodular cast iron, and exhibits a structure in which the carbon content in the cast iron is precipitated in a spherical shape as graphite in the parent phase iron. In order to obtain such a spheroidal graphite cast iron structure, Mg is generally added as a cast iron component and inoculated with an Fe—Si alloy. Alternatively, it can be realized by adding appropriate amounts of Ce and Ca. By forming a spherical graphite structure in which graphite precipitates in a spherical shape, stress concentration at the interface between the graphite and the parent phase is relieved, and cracks are difficult to progress. Therefore, high strength, high toughness (high ductility), and high wear resistance can be imparted as compared with flake graphite cast iron in which the precipitated graphite is flake. Furthermore, since it is for casting, shape design can be performed relatively freely. Since it can be designed freely, it can be easily used for automobile parts and building materials.
しかしながら、近年、高炉や熱風炉の熱効率を向上させるため、熱風炉から供給される熱風５の温度をさらに上昇させることが求められている。
熱風５の温度を上昇させるには、蓄熱室の温度を上昇させる必要があり、その手段の１つとして、排ガス温度の上昇がある。
ところが、チェッカー煉瓦加熱ガス３の温度を上げると、チェッカー煉瓦の加熱を終えた排ガス４の温度が従来の耐熱温度である３５０～４００℃よりも上昇する。そのため、高温の排ガス４にさらされながらチェッカー煉瓦１の重量を支えなければならないチェッカー受金物部材２は、熱と重みで座屈してしまう。すなわち、チェッカー受金物部材２の耐熱強度が向上し、排ガス４の温度を上げることができれば、蓄熱熱量も増え、熱風５の温度も上昇させることができる。 However, in recent years, in order to improve the thermal efficiency of a blast furnace or a hot stove, it is required to further increase the temperature of thehot air 5 supplied from the hot stove.
In order to increase the temperature of thehot air 5, it is necessary to increase the temperature of the heat storage chamber, and one of the means is to increase the exhaust gas temperature.
However, when the temperature of the checkerbrick heating gas 3 is increased, the temperature of the exhaust gas 4 after heating the checker brick rises from 350 to 400 ° C., which is the conventional heat resistance temperature. Therefore, the checker metal receiving member 2 that must support the weight of the checker brick 1 while being exposed to the high temperature exhaust gas 4 is buckled by heat and weight. That is, if the heat resistance strength of the checker-receiver member 2 is improved and the temperature of the exhaust gas 4 can be increased, the amount of heat stored can be increased and the temperature of the hot air 5 can be increased.
熱風５の温度を上昇させるには、蓄熱室の温度を上昇させる必要があり、その手段の１つとして、排ガス温度の上昇がある。
ところが、チェッカー煉瓦加熱ガス３の温度を上げると、チェッカー煉瓦の加熱を終えた排ガス４の温度が従来の耐熱温度である３５０～４００℃よりも上昇する。そのため、高温の排ガス４にさらされながらチェッカー煉瓦１の重量を支えなければならないチェッカー受金物部材２は、熱と重みで座屈してしまう。すなわち、チェッカー受金物部材２の耐熱強度が向上し、排ガス４の温度を上げることができれば、蓄熱熱量も増え、熱風５の温度も上昇させることができる。 However, in recent years, in order to improve the thermal efficiency of a blast furnace or a hot stove, it is required to further increase the temperature of the
In order to increase the temperature of the
However, when the temperature of the checker
排ガス温度を上げるための技術として、特許文献１には、蓄熱格子耐火煉瓦を支持するための支持組立品を、フェライト系マトリックスおよびグラファイト粒子の分散物を含んでなり、前記グラファイト粒子の形状が実質的に芋虫状または団塊状である鋳鉄組織である鋳鉄とすることで、排気温度が６００℃さらには７００℃を超えられる旨記載されている。また、成分的には、鋳鉄材料は、炭素２．０～３．８％、ケイ素１．８～５．０％、マンガン０．１～１．０％、リン０．１％以下、硫黄０．１％以下、所望によりモリブデン１．２５％以下、不可避不純物および残部鉄、である旨記載されている。
As a technique for raising the exhaust gas temperature, Patent Document 1 discloses that a support assembly for supporting a heat storage grid refractory brick includes a ferrite matrix and a dispersion of graphite particles, and the shape of the graphite particles is substantially the same. In particular, it is described that the exhaust temperature can exceed 600 ° C. or even 700 ° C. by using cast iron which is a cast iron structure having a worm-like or nodular shape. In terms of components, the cast iron material is composed of carbon 2.0-3.8%, silicon 1.8-5.0%, manganese 0.1-1.0%, phosphorus 0.1% or less, sulfur 0 .1% or less, optionally molybdenum 1.25% or less, unavoidable impurities and balance iron.
ＦＣＤ（球状黒鉛鋳鉄）は、基地組織がフェライトであり、グラファイト粒子の形状が球状である団塊状であるから、特許文献１に記載されている発明は、実質的にＦＣＤと、これにＭｏを添加した合金鋳鉄である。このＦＣＤは、球状黒鉛鋳鉄であるから、高強度、高靱性ではあり、ある程度の耐熱性を有しているが、高炉に吹き込む熱風をさらに高温とし、高炉に装入する加熱用のコークスを減少させるためには、蓄熱室の温度を向上させることが求められるため、さらなる耐熱性が求められる。特に、現状の大規模な実機レベルの、高温で約２０００トンｆの高重量が負荷されるチェッカー受金物部材おいて、例えば排ガス温度を４００℃から５００℃に１００℃向上させることで、高炉１基あたり年間コークス使用量を数万トン減少させ、年間数億円のコスト削減が期待できる。
Since FCD (spheroidal graphite cast iron) is a nodule in which the base structure is ferrite and the shape of the graphite particles is spherical, the invention described in Patent Document 1 is substantially composed of FCD and Mo. Added alloy cast iron. Since this FCD is spheroidal graphite cast iron, it has high strength and high toughness, and has a certain degree of heat resistance. However, the hot air blown into the blast furnace is heated to a higher temperature to reduce the heating coke charged in the blast furnace. In order to achieve this, since it is required to improve the temperature of the heat storage chamber, further heat resistance is required. In particular, in a checker-receiver member that is loaded with a high weight of about 2000 tons f at a high temperature of the actual large-scale actual machine level, for example, by raising the exhaust gas temperature from 400 ° C. to 500 ° C. by 100 ° C., the blast furnace 1 The annual coke consumption per base can be reduced by tens of thousands of tons, and cost reduction of several hundred million yen per year can be expected.
チェッカー受金物部材は、従来よりも高温で、２０００トンｆもの高荷重が負荷されることから、高温で必要な耐用強度を設定する必要がある。一般的に、高温で用いられる材料の許容応力は「ＡＳＭＥ Ｃｏｄｅ」（アメリカ機械学会基準）で規定されている設計応力、すなわち、「高温引張強度の１／４」と「１０－５％／時のクリープ速度が発生する応力」（「％／時」は、一時間あたりの変形割合）のうちの小さい方の値によって決定される。
Since the checker receiving member has a higher temperature than conventional and a load as high as 2000 tons f is applied, it is necessary to set the required durability at a high temperature. In general, the allowable stress of materials used at high temperatures is the design stress specified by “ASME Code” (American Society of Mechanical Engineers), ie, “¼ of high temperature tensile strength” and “10 −5 % / hour”. Is determined by the smaller value of “the stress at which the creep rate is generated” (“% / hour” is the deformation rate per hour).
図１の破線にＦＣＤにおける「高温引張強度の１／４」、「１０－５％／時のクリープ速度が発生する応力」と温度との関係を示す。また、図１の実線は、本発明の目標とする高強度化特性である。一般的に従来材質であるＦＣＤは、温度が上昇するに従い、４００℃近辺で、「高温引張強度の１／４」と、「１０－５％／時のクリープ速度が発生する応力」が逆転し、「１０－５％／時のクリープ速度が発生する応力」の方が小さくなる。このように、４００℃を超えるような高温下で材料を使用する場合は、当該温度での単純な引張強度だけでは材料を使用できるか評価することができず、高温でのクリープ強度が高い必要がある。そのため、チェッカー受金物部材として使用する際は、クリープ強度が律速となり、さらに設計応力や設計条件によって最大許容温度が決定される。すなわち、破線に示した従来技術を実線のような特性に改善できれば、１０－５％／時のクリープ速度が発生する応力が向上し、チェッカー受金物部材の最大許容温度を向上させることができる。
The broken line in FIG. 1 shows the relationship between the temperature and the “stress that generates a creep rate of 10 −5 % / hour” in FCD. Further, the solid line in FIG. 1 represents the high strength characteristic targeted by the present invention. In general, FCD, which is a conventional material, reverses the “high temperature tensile strength 1/4” and “stress at which a creep rate of 10 −5 % / hour” occurs at around 400 ° C. as the temperature rises. “Stress that generates a creep rate of 10 −5 % / hour” becomes smaller. As described above, when a material is used at a high temperature exceeding 400 ° C., it cannot be evaluated whether the material can be used only by a simple tensile strength at the temperature, and the creep strength at a high temperature needs to be high. There is. For this reason, when used as a checker-receiver member, the creep strength is rate-determining, and the maximum allowable temperature is determined by design stress and design conditions. That is, if the conventional technique shown by the broken line can be improved to the characteristic shown by the solid line, the stress at which the creep rate of 10 −5 % / hour is improved, and the maximum allowable temperature of the checker metal receiving member can be improved.
特許文献１には、排気温度が６００℃さらには７００℃を超えられる旨記載されているものの、高温クリープ特性については言及されておらず、また、実態的な高温での強度も開示されていない。
Patent Document 1 describes that the exhaust temperature can exceed 600 ° C. or even 700 ° C., but does not mention high-temperature creep characteristics, and does not disclose actual high-temperature strength. .
上記課題を解決するための、本発明の要旨とするところは以下のとおりである。
（１）質量％で
Ｃ ：３．０％～４．３％、
Ｓｉ：１．５％以上、３．０％未満、
Ｍｎ：０．４％以下、
Ｍｇ、ミッシュメタル、Ｃｅ、Ｃａのいずれか１種以上からなる黒鉛球状化剤：０．０１０～０．１５％、
Ｐ ：０．２０％以下、
Ｓ ：０．０５０％以下、
Ｎｉ：０．５０～１．５％、
Ｃｕ：０．２０％以上、０．８％未満、
Ｍｏ：０．５０～１．５％、
を含有し、
残部がＦｅおよび不可避的不純物からなることを特徴とする耐クリープ性に優れた耐熱球状黒鉛鋳鉄。
（２）（１）に記載の耐熱球状黒鉛鋳鉄からなることを特徴とする熱風炉の蓄熱煉瓦支持部材。
（３）（１）に記載の耐熱球状黒鉛鋳鉄からなることを特徴とする熱風炉のチェッカー受金物部材。 The gist of the present invention for solving the above problems is as follows.
(1) C: 3.0% to 4.3% by mass%,
Si: 1.5% or more, less than 3.0%,
Mn: 0.4% or less,
Graphite spheronizing agent comprising at least one of Mg, Misch metal, Ce, and Ca: 0.010 to 0.15%,
P: 0.20% or less,
S: 0.050% or less,
Ni: 0.50 to 1.5%,
Cu: 0.20% or more, less than 0.8%,
Mo: 0.50 to 1.5%,
Containing
A heat-resistant spheroidal graphite cast iron excellent in creep resistance, characterized in that the balance consists of Fe and inevitable impurities.
(2) A heat storage brick support member for a hot stove comprising the heat-resistant spheroidal graphite cast iron according to (1).
(3) A checker-receiver member for a hot stove comprising the heat-resistant spheroidal graphite cast iron according to (1).
（１）質量％で
Ｃ ：３．０％～４．３％、
Ｓｉ：１．５％以上、３．０％未満、
Ｍｎ：０．４％以下、
Ｍｇ、ミッシュメタル、Ｃｅ、Ｃａのいずれか１種以上からなる黒鉛球状化剤：０．０１０～０．１５％、
Ｐ ：０．２０％以下、
Ｓ ：０．０５０％以下、
Ｎｉ：０．５０～１．５％、
Ｃｕ：０．２０％以上、０．８％未満、
Ｍｏ：０．５０～１．５％、
を含有し、
残部がＦｅおよび不可避的不純物からなることを特徴とする耐クリープ性に優れた耐熱球状黒鉛鋳鉄。
（２）（１）に記載の耐熱球状黒鉛鋳鉄からなることを特徴とする熱風炉の蓄熱煉瓦支持部材。
（３）（１）に記載の耐熱球状黒鉛鋳鉄からなることを特徴とする熱風炉のチェッカー受金物部材。 The gist of the present invention for solving the above problems is as follows.
(1) C: 3.0% to 4.3% by mass%,
Si: 1.5% or more, less than 3.0%,
Mn: 0.4% or less,
Graphite spheronizing agent comprising at least one of Mg, Misch metal, Ce, and Ca: 0.010 to 0.15%,
P: 0.20% or less,
S: 0.050% or less,
Ni: 0.50 to 1.5%,
Cu: 0.20% or more, less than 0.8%,
Mo: 0.50 to 1.5%,
Containing
A heat-resistant spheroidal graphite cast iron excellent in creep resistance, characterized in that the balance consists of Fe and inevitable impurities.
(2) A heat storage brick support member for a hot stove comprising the heat-resistant spheroidal graphite cast iron according to (1).
(3) A checker-receiver member for a hot stove comprising the heat-resistant spheroidal graphite cast iron according to (1).
本発明により、球状黒鉛鋳鉄のクリープ強度及び高温引張強度を向上させることができ、熱風炉の蓄熱煉瓦支持部材、チェッカー受金物部材等の耐熱構造材として好適に使用することにより、熱風炉、高炉操業等の熱効率を向上させ、資源やコストを低減させることができる。
According to the present invention, the creep strength and high-temperature tensile strength of spheroidal graphite cast iron can be improved, and by using it suitably as a heat-resistant structural material such as a heat storage brick support member of a hot blast furnace, a checker metal receiving member, Thermal efficiency such as operation can be improved, and resources and costs can be reduced.
本発明者は、ＦＣＤに使用される成分組成をベースに、高温クリープ強度の向上を図るため、種々の添加元素を検討した。その結果、所定量のＭｏ、Ｃｕ、Ｎｉを、併用して添加することにより、球状黒鉛鋳鉄の高温クリープ強度と引張強度が向上することを見出した。以下、各成分の限定理由について説明する。成分に関する％表記は、すべて質量％である。
The present inventor examined various additive elements in order to improve the high temperature creep strength based on the component composition used for FCD. As a result, it was found that the high-temperature creep strength and tensile strength of spheroidal graphite cast iron are improved by adding a predetermined amount of Mo, Cu, and Ni in combination. Hereinafter, the reason for limitation of each component is demonstrated. All percentages relating to the components are mass%.
Ｃ：３．０～４．３％
元々鋳鉄は、鋳造性を良好にするための炭素を１．７～４．５質量％程度含むが、本発明においては、球状黒鉛および炭化物（パーライト組織に含まれるセメンタイト等）を十分に生成させるために、範囲を３．０～４．３％と規定した。３．０％未満では、球状黒鉛鋳鉄は片状黒鉛鋳鉄よりも湯流れが悪いため、鋳造性が悪化して湯流れ不良等に伴う鋳造欠陥や引け巣の発生、球状黒鉛や炭化物生成不良となり、強度が不足する。４．３％を超えると、共晶組成を超えることから初晶黒鉛（過共晶黒鉛）が生成しやすくなる。初晶黒鉛が生成すると、鋳鉄の靱性が低下し、伸びが悪化するので好ましくない。また、４．３％を超えると、ドロスや偏析が発生して鋳造欠陥となり、黒鉛が十分に球状化、分散せず、鋳鉄の靱性が低下し、伸びが悪化する。より好ましい下限範囲は、３．５％以上、さらに好ましい下限範囲は３．７％以上である。一方、より好ましい上限範囲は、４．０％以下、さらに好ましい下限範囲は３．９％以下である。 C: 3.0 to 4.3%
Cast iron originally contains about 1.7 to 4.5% by mass of carbon for improving castability. In the present invention, spheroidal graphite and carbides (such as cementite contained in pearlite structure) are sufficiently generated. Therefore, the range is defined as 3.0 to 4.3%. If it is less than 3.0%, spheroidal graphite cast iron has a poorer molten metal flow than flake graphite cast iron. Therefore, castability deteriorates and casting defects and shrinkage due to poor molten metal flow occur, resulting in poor formation of spheroidal graphite and carbide. , Lack of strength. When it exceeds 4.3%, primary crystal graphite (hypereutectic graphite) is likely to be generated because it exceeds the eutectic composition. Generation of primary graphite is not preferable because the toughness of cast iron decreases and the elongation deteriorates. On the other hand, if it exceeds 4.3%, dross and segregation occur, resulting in a casting defect, graphite is not sufficiently spheroidized and dispersed, the toughness of cast iron is reduced, and the elongation is deteriorated. A more preferable lower limit range is 3.5% or more, and a further preferable lower limit range is 3.7% or more. On the other hand, a more preferable upper limit range is 4.0% or less, and a more preferable lower limit range is 3.9% or less.
元々鋳鉄は、鋳造性を良好にするための炭素を１．７～４．５質量％程度含むが、本発明においては、球状黒鉛および炭化物（パーライト組織に含まれるセメンタイト等）を十分に生成させるために、範囲を３．０～４．３％と規定した。３．０％未満では、球状黒鉛鋳鉄は片状黒鉛鋳鉄よりも湯流れが悪いため、鋳造性が悪化して湯流れ不良等に伴う鋳造欠陥や引け巣の発生、球状黒鉛や炭化物生成不良となり、強度が不足する。４．３％を超えると、共晶組成を超えることから初晶黒鉛（過共晶黒鉛）が生成しやすくなる。初晶黒鉛が生成すると、鋳鉄の靱性が低下し、伸びが悪化するので好ましくない。また、４．３％を超えると、ドロスや偏析が発生して鋳造欠陥となり、黒鉛が十分に球状化、分散せず、鋳鉄の靱性が低下し、伸びが悪化する。より好ましい下限範囲は、３．５％以上、さらに好ましい下限範囲は３．７％以上である。一方、より好ましい上限範囲は、４．０％以下、さらに好ましい下限範囲は３．９％以下である。 C: 3.0 to 4.3%
Cast iron originally contains about 1.7 to 4.5% by mass of carbon for improving castability. In the present invention, spheroidal graphite and carbides (such as cementite contained in pearlite structure) are sufficiently generated. Therefore, the range is defined as 3.0 to 4.3%. If it is less than 3.0%, spheroidal graphite cast iron has a poorer molten metal flow than flake graphite cast iron. Therefore, castability deteriorates and casting defects and shrinkage due to poor molten metal flow occur, resulting in poor formation of spheroidal graphite and carbide. , Lack of strength. When it exceeds 4.3%, primary crystal graphite (hypereutectic graphite) is likely to be generated because it exceeds the eutectic composition. Generation of primary graphite is not preferable because the toughness of cast iron decreases and the elongation deteriorates. On the other hand, if it exceeds 4.3%, dross and segregation occur, resulting in a casting defect, graphite is not sufficiently spheroidized and dispersed, the toughness of cast iron is reduced, and the elongation is deteriorated. A more preferable lower limit range is 3.5% or more, and a further preferable lower limit range is 3.7% or more. On the other hand, a more preferable upper limit range is 4.0% or less, and a more preferable lower limit range is 3.9% or less.
Ｓｉ：１．５～３．５％
Ｓｉは、黒鉛の晶出を容易とし、また、後述するＭｇ添加の効果と相まって、黒鉛を球状化するため、さらには鋳造性を良好にするために添加する。１．５％未満では、上記の効果が十分でなく、十分な黒鉛が晶出しないため、強度が不足する。一方、３．５％を超えると、晶出した黒鉛量が多くなりすぎ、球状化しない片状晶出物が生成する。黒鉛が片状で晶出すると、黒鉛との界面に応力が集中して強度と靱性、伸びを悪化させる。より好ましい下限範囲は、２．０％以上、さらに好ましい下限範囲は２．５％以上である。一方、より好ましい上限範囲は、３．０％以下、さらに好ましい下限範囲は２．７％以下である。 Si: 1.5 to 3.5%
Si is added in order to facilitate crystallization of graphite, and in combination with the effect of adding Mg, which will be described later, to spheroidize graphite and to improve castability. If it is less than 1.5%, the above effect is not sufficient, and sufficient graphite does not crystallize, so that the strength is insufficient. On the other hand, if it exceeds 3.5%, the amount of crystallized graphite becomes too large, and a flake crystallized product that does not spheroidize is generated. When graphite is crystallized in the form of a piece, stress concentrates on the interface with graphite and deteriorates strength, toughness, and elongation. A more preferred lower limit range is 2.0% or more, and a more preferred lower limit range is 2.5% or more. On the other hand, a more preferable upper limit range is 3.0% or less, and a more preferable lower limit range is 2.7% or less.
Ｓｉは、黒鉛の晶出を容易とし、また、後述するＭｇ添加の効果と相まって、黒鉛を球状化するため、さらには鋳造性を良好にするために添加する。１．５％未満では、上記の効果が十分でなく、十分な黒鉛が晶出しないため、強度が不足する。一方、３．５％を超えると、晶出した黒鉛量が多くなりすぎ、球状化しない片状晶出物が生成する。黒鉛が片状で晶出すると、黒鉛との界面に応力が集中して強度と靱性、伸びを悪化させる。より好ましい下限範囲は、２．０％以上、さらに好ましい下限範囲は２．５％以上である。一方、より好ましい上限範囲は、３．０％以下、さらに好ましい下限範囲は２．７％以下である。 Si: 1.5 to 3.5%
Si is added in order to facilitate crystallization of graphite, and in combination with the effect of adding Mg, which will be described later, to spheroidize graphite and to improve castability. If it is less than 1.5%, the above effect is not sufficient, and sufficient graphite does not crystallize, so that the strength is insufficient. On the other hand, if it exceeds 3.5%, the amount of crystallized graphite becomes too large, and a flake crystallized product that does not spheroidize is generated. When graphite is crystallized in the form of a piece, stress concentrates on the interface with graphite and deteriorates strength, toughness, and elongation. A more preferred lower limit range is 2.0% or more, and a more preferred lower limit range is 2.5% or more. On the other hand, a more preferable upper limit range is 3.0% or less, and a more preferable lower limit range is 2.7% or less.
Ｍｎ：１．０％以下
Ｍｎは、通常の鉄鋼製錬において、脱酸や靱性の確保のために微量添加されるものである。１．０％を超えると、硬く脆いマンガン炭化物が生成しやすくなり、強度と靱性、伸びが悪化する。より好ましい上限範囲は、０．６％、さらに好ましい上限範囲は０．４％以下である。一方、下限については、必ずしも限定する必要はないが、必要以上にＭｎを低減することはコストを押し上げるため、また、脱酸や靱性の確保を行う必要上、０．１％以上が好ましく、０．２％以上がさらに好ましい。 Mn: 1.0% or less Mn is added in a small amount to ensure deoxidation and toughness in ordinary steel smelting. If it exceeds 1.0%, hard and brittle manganese carbide is likely to be produced, and the strength, toughness and elongation are deteriorated. A more preferable upper limit range is 0.6%, and a more preferable upper limit range is 0.4% or less. On the other hand, the lower limit is not necessarily limited, but it is preferably 0.1% or more in order to reduce Mn more than necessary to increase the cost and to ensure deoxidation and toughness. More preferably 2% or more.
Ｍｎは、通常の鉄鋼製錬において、脱酸や靱性の確保のために微量添加されるものである。１．０％を超えると、硬く脆いマンガン炭化物が生成しやすくなり、強度と靱性、伸びが悪化する。より好ましい上限範囲は、０．６％、さらに好ましい上限範囲は０．４％以下である。一方、下限については、必ずしも限定する必要はないが、必要以上にＭｎを低減することはコストを押し上げるため、また、脱酸や靱性の確保を行う必要上、０．１％以上が好ましく、０．２％以上がさらに好ましい。 Mn: 1.0% or less Mn is added in a small amount to ensure deoxidation and toughness in ordinary steel smelting. If it exceeds 1.0%, hard and brittle manganese carbide is likely to be produced, and the strength, toughness and elongation are deteriorated. A more preferable upper limit range is 0.6%, and a more preferable upper limit range is 0.4% or less. On the other hand, the lower limit is not necessarily limited, but it is preferably 0.1% or more in order to reduce Mn more than necessary to increase the cost and to ensure deoxidation and toughness. More preferably 2% or more.
Ｍｇ、ミッシュメタル、Ｃｅ、Ｃａのいずれか１種以上からなる黒鉛球状化剤：０．０１０～０．１５％
Ｍｇ、ミッシュメタル、Ｃｅ、Ｃａのいずれか１種以上からなる黒鉛球状化剤は、晶出する黒鉛を球状化させるために添加する。０．０１０％未満では黒鉛を十分に球状化できず、片状黒鉛が生成する。一方、０．１５％を超えると、硬く脆い炭化物が生成し、靱性、伸びが悪化する。より好適な黒鉛球状化剤は、Ｍｇ単独添加であるか、Ｍｇに、ＣｅおよびＣａを併用したものである。 Graphite spheroidizing agent comprising at least one of Mg, Misch metal, Ce, and Ca: 0.010 to 0.15%
A graphite spheroidizing agent comprising at least one of Mg, Misch metal, Ce, and Ca is added to spheroidize the crystallized graphite. If it is less than 0.010%, the graphite cannot be sufficiently spheroidized, and flake graphite is produced. On the other hand, if it exceeds 0.15%, hard and brittle carbides are produced, and the toughness and elongation deteriorate. A more preferable graphite spheroidizing agent is Mg added alone or Mg and Ce and Ca are used in combination.
Ｍｇ、ミッシュメタル、Ｃｅ、Ｃａのいずれか１種以上からなる黒鉛球状化剤は、晶出する黒鉛を球状化させるために添加する。０．０１０％未満では黒鉛を十分に球状化できず、片状黒鉛が生成する。一方、０．１５％を超えると、硬く脆い炭化物が生成し、靱性、伸びが悪化する。より好適な黒鉛球状化剤は、Ｍｇ単独添加であるか、Ｍｇに、ＣｅおよびＣａを併用したものである。 Graphite spheroidizing agent comprising at least one of Mg, Misch metal, Ce, and Ca: 0.010 to 0.15%
A graphite spheroidizing agent comprising at least one of Mg, Misch metal, Ce, and Ca is added to spheroidize the crystallized graphite. If it is less than 0.010%, the graphite cannot be sufficiently spheroidized, and flake graphite is produced. On the other hand, if it exceeds 0.15%, hard and brittle carbides are produced, and the toughness and elongation deteriorate. A more preferable graphite spheroidizing agent is Mg added alone or Mg and Ce and Ca are used in combination.
Ｐ：０．２０％以下
Ｐ（リン）は鋳鉄中に不可避に含まれる元素であるが、０．２０％を超えると、鋳造性が悪化して鋳造欠陥を生じやすくなり、靱性と伸びが悪化するため、含有を制限する。より好ましい範囲は０．１０％以下である。 P: 0.20% or less P (phosphorus) is an element inevitably contained in cast iron, but if it exceeds 0.20%, castability deteriorates and casting defects tend to occur, and toughness and elongation deteriorate. Therefore, the content is limited. A more preferable range is 0.10% or less.
Ｐ（リン）は鋳鉄中に不可避に含まれる元素であるが、０．２０％を超えると、鋳造性が悪化して鋳造欠陥を生じやすくなり、靱性と伸びが悪化するため、含有を制限する。より好ましい範囲は０．１０％以下である。 P: 0.20% or less P (phosphorus) is an element inevitably contained in cast iron, but if it exceeds 0.20%, castability deteriorates and casting defects tend to occur, and toughness and elongation deteriorate. Therefore, the content is limited. A more preferable range is 0.10% or less.
Ｓ：０．０５０％以下
Ｓ（硫黄）もＰと同様に鋳鉄中に不可避に含まれる元素であるが、０．０５％を超えると、黒鉛の球状化を阻害するため、含有を制限する。より好ましい範囲は０．０２％以下である。 S: 0.050% or less S (sulfur) is an element inevitably contained in the cast iron as in the case of P. However, if it exceeds 0.05%, the spheroidization of graphite is inhibited, so the content is limited. A more preferable range is 0.02% or less.
Ｓ（硫黄）もＰと同様に鋳鉄中に不可避に含まれる元素であるが、０．０５％を超えると、黒鉛の球状化を阻害するため、含有を制限する。より好ましい範囲は０．０２％以下である。 S: 0.050% or less S (sulfur) is an element inevitably contained in the cast iron as in the case of P. However, if it exceeds 0.05%, the spheroidization of graphite is inhibited, so the content is limited. A more preferable range is 0.02% or less.
Ｎｉ：０．５０～１．５％
Ｎｉは、Ｍｏ、Ｃｕとともに添加することにより、高温での引張強度が向上する。０．５０％未満では、強度向上の効果が十分でなく、１．５％を超えると、靱性、伸びが低下し、また、鋳造欠陥が発生しやすくなる。より好ましい下限範囲は、０．８％以上、さらに好ましい下限範囲は１．０％以上である。一方、より好ましい上限範囲は、１．３％以下、さらに好ましい上限範囲は１．１％以下である。 Ni: 0.50 to 1.5%
When Ni is added together with Mo and Cu, the tensile strength at high temperature is improved. If it is less than 0.50%, the effect of improving the strength is not sufficient, and if it exceeds 1.5%, the toughness and elongation are lowered, and casting defects are likely to occur. A more preferable lower limit range is 0.8% or more, and a further preferable lower limit range is 1.0% or more. On the other hand, a more preferable upper limit range is 1.3% or less, and a more preferable upper limit range is 1.1% or less.
Ｎｉは、Ｍｏ、Ｃｕとともに添加することにより、高温での引張強度が向上する。０．５０％未満では、強度向上の効果が十分でなく、１．５％を超えると、靱性、伸びが低下し、また、鋳造欠陥が発生しやすくなる。より好ましい下限範囲は、０．８％以上、さらに好ましい下限範囲は１．０％以上である。一方、より好ましい上限範囲は、１．３％以下、さらに好ましい上限範囲は１．１％以下である。 Ni: 0.50 to 1.5%
When Ni is added together with Mo and Cu, the tensile strength at high temperature is improved. If it is less than 0.50%, the effect of improving the strength is not sufficient, and if it exceeds 1.5%, the toughness and elongation are lowered, and casting defects are likely to occur. A more preferable lower limit range is 0.8% or more, and a further preferable lower limit range is 1.0% or more. On the other hand, a more preferable upper limit range is 1.3% or less, and a more preferable upper limit range is 1.1% or less.
Ｃｕ：０．２０～１．０％
Ｃｕは、Ｎｉ、Ｍｏとともに添加することにより、高温でのクリープ強度が向上する。０．２０％未満では、クリープ強度向上の効果が十分でなく、１．０％を超えると、靱性、伸びが低下し、また、Ｃｕに富んだ相が発生しやすくなり、強度も低下する。より好ましい下限範囲は、０．４％以上、さらに好ましい下限範囲は０．５％以上である。一方、より好ましい上限範囲は、０．８％以下、さらに好ましい上限範囲は０．６％以下である。 Cu: 0.20 to 1.0%
By adding Cu together with Ni and Mo, the creep strength at high temperature is improved. If the content is less than 0.20%, the effect of improving the creep strength is not sufficient. If the content exceeds 1.0%, the toughness and elongation are reduced, and a Cu-rich phase is easily generated and the strength is also reduced. A more preferable lower limit range is 0.4% or more, and a further preferable lower limit range is 0.5% or more. On the other hand, a more preferable upper limit range is 0.8% or less, and a more preferable upper limit range is 0.6% or less.
Ｃｕは、Ｎｉ、Ｍｏとともに添加することにより、高温でのクリープ強度が向上する。０．２０％未満では、クリープ強度向上の効果が十分でなく、１．０％を超えると、靱性、伸びが低下し、また、Ｃｕに富んだ相が発生しやすくなり、強度も低下する。より好ましい下限範囲は、０．４％以上、さらに好ましい下限範囲は０．５％以上である。一方、より好ましい上限範囲は、０．８％以下、さらに好ましい上限範囲は０．６％以下である。 Cu: 0.20 to 1.0%
By adding Cu together with Ni and Mo, the creep strength at high temperature is improved. If the content is less than 0.20%, the effect of improving the creep strength is not sufficient. If the content exceeds 1.0%, the toughness and elongation are reduced, and a Cu-rich phase is easily generated and the strength is also reduced. A more preferable lower limit range is 0.4% or more, and a further preferable lower limit range is 0.5% or more. On the other hand, a more preferable upper limit range is 0.8% or less, and a more preferable upper limit range is 0.6% or less.
Ｍｏ：０．５０～１．５％
Ｍｏは、Ｎｉ、Ｃｕとともに添加することにより、高温でのクリープ強度が向上する。０．５０％未満では、クリープ強度向上の効果が十分でなく、１．５％を超えると、硬い炭化物からなる金属間化合物相が生成し、靱性、伸びが低下し、強度も低下する。より好ましい下限範囲は、０．６％以上、さらに好ましい下限範囲は０．８％以上である。一方、より好ましい上限範囲は、１．２％以下、さらに好ましい上限範囲は１．０％以下である。 Mo: 0.50 to 1.5%
When Mo is added together with Ni and Cu, the creep strength at high temperature is improved. If it is less than 0.50%, the effect of improving the creep strength is not sufficient, and if it exceeds 1.5%, an intermetallic compound phase composed of a hard carbide is generated, and the toughness and elongation are lowered, and the strength is also lowered. A more preferred lower limit range is 0.6% or more, and a more preferred lower limit range is 0.8% or more. On the other hand, a more preferable upper limit range is 1.2% or less, and a more preferable upper limit range is 1.0% or less.
Ｍｏは、Ｎｉ、Ｃｕとともに添加することにより、高温でのクリープ強度が向上する。０．５０％未満では、クリープ強度向上の効果が十分でなく、１．５％を超えると、硬い炭化物からなる金属間化合物相が生成し、靱性、伸びが低下し、強度も低下する。より好ましい下限範囲は、０．６％以上、さらに好ましい下限範囲は０．８％以上である。一方、より好ましい上限範囲は、１．２％以下、さらに好ましい上限範囲は１．０％以下である。 Mo: 0.50 to 1.5%
When Mo is added together with Ni and Cu, the creep strength at high temperature is improved. If it is less than 0.50%, the effect of improving the creep strength is not sufficient, and if it exceeds 1.5%, an intermetallic compound phase composed of a hard carbide is generated, and the toughness and elongation are lowered, and the strength is also lowered. A more preferred lower limit range is 0.6% or more, and a more preferred lower limit range is 0.8% or more. On the other hand, a more preferable upper limit range is 1.2% or less, and a more preferable upper limit range is 1.0% or less.
上記以外の残部は、Ｆｅおよび不可避的不純物である。ここでいう、不可避的不純物とは、通常の鋳鉄を製造する製造工程において不可避に含有される程度の種類と量の元素を含む、ということであり、現状の技術で可能である限界まで各明記されない不純物元素を低減させたという趣旨の記載ではない。言い換えると、不可避的不純物とは、特定の目的をもって、意図的に添加させた元素ではなく含まれる元素をいう。たとえば、高価なＶ等の改質元素を添加させることは、特に構造材のような大きな製品においては、コストを著しく増大させるので、本発明の対象外である。不純物の目安としては、ＦＣＤの規格に許容される程度の種類と量の元素を含むことは許容される。
The balance other than the above is Fe and inevitable impurities. The inevitable impurities mentioned here include the elements and the amount of elements that are inevitably contained in the production process of producing ordinary cast iron, and each is clearly specified to the limit that is possible with the current technology. It is not a statement to the effect that impurity elements that are not used are reduced. In other words, inevitable impurities refer to elements contained rather than intentionally added elements for a specific purpose. For example, adding an expensive modifying element such as V significantly increases the cost, especially in large products such as structural materials, and is out of the scope of the present invention. As a measure of impurities, it is allowed to contain elements of the kind and amount that are allowed by the FCD standard.
本発明の球状黒鉛鋳鉄は、上記のように成分組成を決定したことにより発明の効果を奏するものであり、製造するには、通常の方法で溶解し、成分調整を行い、鋳造し、そのまま鋳放しすることなどで製造できる。鋳放しで製造された球状黒鉛鋳鉄の組織は、球状黒鉛部を除き、フェライト組織が面積率で３０～７０％、残部パーライト組織である。
The spheroidal graphite cast iron of the present invention exhibits the effects of the invention by determining the component composition as described above. For production, it is melted by a usual method, adjusted for components, cast, and cast as it is. It can be manufactured by releasing it. The structure of spheroidal graphite cast iron produced by as-casting is a ferrite structure with an area ratio of 30 to 70% and the remaining pearlite structure, excluding the spheroidal graphite part.
クリープ試験結果
クリープ試験は、ＪＩＳ Ｚ ２２７１の規定に従い、鋳鉄を溶製して鋳造し、鋳放しにより鋳塊を製造し、切り出して作製した引張試験片を用いて行った。なお、試験片の成分を分析した結果は、表１に示す成分範囲であった。 Creep test result The creep test was performed using a tensile test piece prepared by melting and casting cast iron, producing an ingot by as-casting, and cutting out in accordance with the provisions of JIS Z 2271. In addition, the result of having analyzed the component of the test piece was the component range shown in Table 1.
クリープ試験は、ＪＩＳ Ｚ ２２７１の規定に従い、鋳鉄を溶製して鋳造し、鋳放しにより鋳塊を製造し、切り出して作製した引張試験片を用いて行った。なお、試験片の成分を分析した結果は、表１に示す成分範囲であった。 Creep test result The creep test was performed using a tensile test piece prepared by melting and casting cast iron, producing an ingot by as-casting, and cutting out in accordance with the provisions of JIS Z 2271. In addition, the result of having analyzed the component of the test piece was the component range shown in Table 1.
クリープ試験は、４００℃、４５０℃、５００℃、５５０℃で行った。また、試験時間は、遷移域や加速域の時間を含む合計時間として、３００から１２００時間を目標に行い、各温度で、様々な負荷応力において、定常クリープ中の時間に対する伸びを測定し、最小クリープ速度を算出した。そして、各温度での最小クリープ速度と、対応する負荷応力との関係式を外挿により求め、その関係式より１０－５％／時となった際の負荷応力（同一温度で一定荷重において、一時間で１０－５％の変形を生じた際の応力）を個別に算出し、クリープ強度として評価した。実施例１～３から負荷応力と最小クリープ速度の関係式を求めると、負荷応力＝２２０．６５×（最小クリープ速度）０．２９２２であり、実施例４～６では、負荷応力＝９９．１７５×（最小クリープ速度）０．２９８７であった。比較例も同様に関係式を求め、クリープ強度を算出した。結果を表２に示した。
The creep test was performed at 400 ° C., 450 ° C., 500 ° C., and 550 ° C. The test time is 300 to 1200 hours as the total time including the transition zone and acceleration zone, and the elongation over time during steady-state creep is measured at various temperatures at various temperatures. Creep speed was calculated. Then, a relational expression between the minimum creep rate at each temperature and the corresponding load stress is obtained by extrapolation, and the load stress at 10 −5 % / hour from the relational expression (at the same temperature and constant load, The stress at the time of deformation of 10 −5 % in one hour was calculated individually and evaluated as the creep strength. When a relational expression between the load stress and the minimum creep rate is obtained from Examples 1 to 3, the load stress = 220.65 × (minimum creep rate) is 0.2922. In Examples 4 to 6, the load stress = 99.175. X (Minimum creep rate) It was 0.2987 . In the comparative example, the relational expression was similarly obtained, and the creep strength was calculated. The results are shown in Table 2.
材質がＦＣＤある比較例１～１２は、Ｎｉ、Ｃｕ、Ｍｏがいずれも添加されていないので、クリープ強度が低い。さらに、ＦＣＤにＮｉを添加した比較例１３～１５も、クリープ強度に関して向上が見られるものの、十分ではない。
In Comparative Examples 1 to 12 where the material is FCD, since none of Ni, Cu, and Mo is added, the creep strength is low. Furthermore, Comparative Examples 13 to 15 in which Ni is added to FCD are not sufficient, although improvement in creep strength is observed.
一方、本発明である実施例１～６は、最小クリープ速度が十分に遅く、高温でも荷重に耐えることが確認できた。また、本発明である実施例１～３は、比較例５～８と同等の温度で、クリープ強度が７．６ｋｇｆ／ｍｍ２と、十倍以上の強度に向上した。さらに、実施例４～６に示したように、５５０℃においても、十分なクリープ強度を維持することができた。また、酸化スケールの発生も少なく、高温耐酸化性も優れていることが確認できた。
On the other hand, in Examples 1 to 6 according to the present invention, the minimum creep rate was sufficiently slow, and it was confirmed that it could withstand the load even at high temperatures. In addition, in Examples 1 to 3 according to the present invention, the creep strength was 7.6 kgf / mm 2 at a temperature equivalent to that of Comparative Examples 5 to 8, and the strength was increased by a factor of 10 or more. Furthermore, as shown in Examples 4 to 6, sufficient creep strength could be maintained even at 550 ° C. In addition, it was confirmed that there was little generation of oxide scale and excellent high-temperature oxidation resistance.
高温引張試験結果
ＪＩＳ Ｇ ０５６７に規定される高温引張試験により鋳片の引張強度と伸びを測定した。試験温度は３００、３５０、４００、４５０、５００、５５０、６００℃で各２本ずつ行った。結果を表３に示した。 Result of high-temperature tensile test The tensile strength and elongation of the slab were measured by a high-temperature tensile test specified in JIS G 0567. The test temperatures were 300, 350, 400, 450, 500, 550, and 600 ° C., two each. The results are shown in Table 3.
ＪＩＳ Ｇ ０５６７に規定される高温引張試験により鋳片の引張強度と伸びを測定した。試験温度は３００、３５０、４００、４５０、５００、５５０、６００℃で各２本ずつ行った。結果を表３に示した。 Result of high-temperature tensile test The tensile strength and elongation of the slab were measured by a high-temperature tensile test specified in JIS G 0567. The test temperatures were 300, 350, 400, 450, 500, 550, and 600 ° C., two each. The results are shown in Table 3.
表３に示したように、実施例１－１～７－２は３００～６００℃での高温引張試験のいずれにおいても、同じ温度での比較例１－１～１４－２のそれぞれを上回った。
また、表２、表３において、４５０、５００、５５０℃の温度において、高温で用いられる材料の許容応力に関する「ＡＳＭＥ Ｃｏｄｅ」に照らすと、「高温引張強度の１／４」と「１０－５％／時のクリープ速度が発生する応力」のうちの小さい方は、「１０－５％／時のクリープ速度が発生する応力」であることが確認され、このような温度で使用するには、「１０－５％／時のクリープ速度が発生する応力」が高くなければならないことが確認できた。 As shown in Table 3, Examples 1-1 to 7-2 exceeded each of Comparative Examples 1-1 to 14-2 at the same temperature in any of the high-temperature tensile tests at 300 to 600 ° C. .
In Tables 2 and 3, in light of “ASME Code” regarding allowable stress of materials used at high temperatures at temperatures of 450, 500, and 550 ° C., “1/4 of high temperature tensile strength” and “10 −5 ”. The smaller of “Stress at which a creep rate of% / hour is generated” is confirmed to be “Stress at which a creep rate of 10 −5 % / hour” is used. It was confirmed that the “stress at which a creep rate of 10 −5 % / hour is generated” must be high.
また、表２、表３において、４５０、５００、５５０℃の温度において、高温で用いられる材料の許容応力に関する「ＡＳＭＥ Ｃｏｄｅ」に照らすと、「高温引張強度の１／４」と「１０－５％／時のクリープ速度が発生する応力」のうちの小さい方は、「１０－５％／時のクリープ速度が発生する応力」であることが確認され、このような温度で使用するには、「１０－５％／時のクリープ速度が発生する応力」が高くなければならないことが確認できた。 As shown in Table 3, Examples 1-1 to 7-2 exceeded each of Comparative Examples 1-1 to 14-2 at the same temperature in any of the high-temperature tensile tests at 300 to 600 ° C. .
In Tables 2 and 3, in light of “ASME Code” regarding allowable stress of materials used at high temperatures at temperatures of 450, 500, and 550 ° C., “1/4 of high temperature tensile strength” and “10 −5 ”. The smaller of “Stress at which a creep rate of% / hour is generated” is confirmed to be “Stress at which a creep rate of 10 −5 % / hour” is used. It was confirmed that the “stress at which a creep rate of 10 −5 % / hour is generated” must be high.
本発明は、高温強度、高温での耐クリープ強度に優れ、耐熱性に優れるから、エンジン、ボイラー、加熱炉等、高温で荷重が負荷され続けるさまざまな高温材料に適用することができる。
The present invention is excellent in high-temperature strength, high-temperature creep resistance, and excellent heat resistance, and therefore can be applied to various high-temperature materials that continue to be loaded at high temperatures, such as engines, boilers, and heating furnaces.
１…チェッカー煉瓦、２…チェッカー受金物部材、３…チェッカー煉瓦加熱ガス、４…排ガス、５…熱風、６…蓄熱室により加熱される空気
DESCRIPTION OF SYMBOLS 1 ... Checker brick, 2 ... Checker receiving material member, 3 ... Checker brick heating gas, 4 ... Exhaust gas, 5 ... Hot air, 6 ... Air heated by a thermal storage chamber
DESCRIPTION OF SYMBOLS 1 ... Checker brick, 2 ... Checker receiving material member, 3 ... Checker brick heating gas, 4 ... Exhaust gas, 5 ... Hot air, 6 ... Air heated by a thermal storage chamber
Claims (3)
- 質量％で
Ｃ ：３．０％～４．３％、
Ｓｉ：１．５％以上、３．０％未満、
Ｍｎ：０．４％以下、
Ｍｇ、ミッシュメタル、Ｃｅ、Ｃａのいずれか１種以上からなる黒鉛球状化剤：０．０１０～０．１５％、
Ｐ ：０．２０％以下、
Ｓ ：０．０５０％以下、
Ｎｉ：０．５０～１．５％、
Ｃｕ：０．２０％以上、０．８％未満、
Ｍｏ：０．５０～１．５％、
を含有し、
残部がＦｅおよび不可避的不純物からなることを特徴とする耐クリープ性に優れた耐熱球状黒鉛鋳鉄。 C by mass: 3.0% to 4.3%,
Si: 1.5% or more, less than 3.0%,
Mn: 0.4% or less,
Graphite spheronizing agent comprising at least one of Mg, Misch metal, Ce, and Ca: 0.010 to 0.15%,
P: 0.20% or less,
S: 0.050% or less,
Ni: 0.50 to 1.5%,
Cu: 0.20% or more, less than 0.8%,
Mo: 0.50 to 1.5%,
Containing
A heat-resistant spheroidal graphite cast iron excellent in creep resistance, characterized in that the balance consists of Fe and inevitable impurities. - 請求項１に記載の耐熱球状黒鉛鋳鉄からなることを特徴とする熱風炉の蓄熱煉瓦支持部材。 A heat storage brick support member for a hot stove, comprising the heat-resistant spheroidal graphite cast iron according to claim 1.
- 請求項１に記載の耐熱球状黒鉛鋳鉄からなることを特徴とする熱風炉のチェッカー受金物部材。
A checker-receiver member for a hot stove comprising the heat-resistant spheroidal graphite cast iron according to claim 1.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017027737A JP6190552B1 (en) | 2017-02-17 | 2017-02-17 | Heat-resistant spheroidal graphite cast iron with excellent creep resistance |
| JP2017-027737 | 2017-02-17 |
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| WO2018150645A1 true WO2018150645A1 (en) | 2018-08-23 |
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| PCT/JP2017/039551 WO2018150645A1 (en) | 2017-02-17 | 2017-11-01 | Heat resistant spheroidal graphite cast iron with excellent creep resistance |
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|---|---|
| JP (1) | JP6190552B1 (en) |
| TW (1) | TWI716650B (en) |
| WO (1) | WO2018150645A1 (en) |
Citations (3)
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|---|---|---|---|---|
| WO1996038596A1 (en) * | 1993-11-24 | 1996-12-05 | Wing Metal Corporation | High-strength spherical graphitic cast iron |
| JP2008528808A (en) * | 2005-02-01 | 2008-07-31 | ダニエリ、コラス、ベスローテン、フェンノートシャップ | Support assembly for supporting a heat storage grid refractory brick in a hot stove, hot stove equipped with the support assembly, and method for generating hot air using the hot stove |
| JP2014105342A (en) * | 2012-11-26 | 2014-06-09 | Japan Steel Works Ltd:The | Spheroidal graphite cast iron excellent in high temperature ductility and high temperature creep rupture life and production method thereof |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS587855U (en) * | 1981-07-06 | 1983-01-19 | 新日本製鐵株式会社 | hot air stove heat storage chamber |
| JPH0629479B2 (en) * | 1986-07-02 | 1994-04-20 | 日立造船株式会社 | Spheroidal graphite cast iron for sintering machine pallet |
| JP3597211B2 (en) * | 1993-10-21 | 2004-12-02 | 株式会社日本製鋼所 | Spheroidal graphite cast iron with excellent high-temperature strength |
| JPH07145444A (en) * | 1993-11-24 | 1995-06-06 | Wing Kinzoku Kk | High strength spheroidal graphite case iron |
| CN104264033A (en) * | 2014-10-13 | 2015-01-07 | 松下·万宝(广州)压缩机有限公司 | High-strength and high-rigidity ductile cast iron material for compressor and application of ductile cast iron |
-
2017
- 2017-02-17 JP JP2017027737A patent/JP6190552B1/en active Active
- 2017-11-01 WO PCT/JP2017/039551 patent/WO2018150645A1/en active Application Filing
- 2017-11-09 TW TW106138810A patent/TWI716650B/en active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996038596A1 (en) * | 1993-11-24 | 1996-12-05 | Wing Metal Corporation | High-strength spherical graphitic cast iron |
| JP2008528808A (en) * | 2005-02-01 | 2008-07-31 | ダニエリ、コラス、ベスローテン、フェンノートシャップ | Support assembly for supporting a heat storage grid refractory brick in a hot stove, hot stove equipped with the support assembly, and method for generating hot air using the hot stove |
| JP2014105342A (en) * | 2012-11-26 | 2014-06-09 | Japan Steel Works Ltd:The | Spheroidal graphite cast iron excellent in high temperature ductility and high temperature creep rupture life and production method thereof |
Also Published As
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|---|---|
| JP6190552B1 (en) | 2017-08-30 |
| TWI716650B (en) | 2021-01-21 |
| JP2018131671A (en) | 2018-08-23 |
| TW201831702A (en) | 2018-09-01 |
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