EP0695811A1 - High heat-resisting iron-base alloy - Google Patents

High heat-resisting iron-base alloy Download PDF

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Publication number
EP0695811A1
EP0695811A1 EP95305233A EP95305233A EP0695811A1 EP 0695811 A1 EP0695811 A1 EP 0695811A1 EP 95305233 A EP95305233 A EP 95305233A EP 95305233 A EP95305233 A EP 95305233A EP 0695811 A1 EP0695811 A1 EP 0695811A1
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EP
European Patent Office
Prior art keywords
base alloy
bal
high heat
resisting iron
alloy according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP95305233A
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German (de)
English (en)
French (fr)
Inventor
Hiroyuki Shamoto
Takashi Morikawa
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Toyota Motor Corp
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Toyota Motor Corp
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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
    • C22C37/10—Cast-iron alloys containing aluminium or silicon

Definitions

  • the present invention relates to an Fe-Al-C-base alloy and more particularly to an iron-base alloy, having excellent heat resistance, for use at high temperatures.
  • Such high heat resisting iron-base materials known in the art include, for example, SCH-base heat resisting steel casting materials (JIS G5122) and FCDA-base nodular graphite austenitic iron castings (JIS G5510).
  • high-silicon nodular graphite cast iron can be first mentioned.
  • Cr incorporated in an amount of not less than 15% in this material, however, is expensive.
  • austenitic cast iron can also be mentioned as a material for use at high temperatures. In this material as well, Cr or Ni, which is an expensive alloying element, is used.
  • Japanese Unexamined Patent Publication (Kokai) No. 3-226547 which has been filed by the applicant of the present invention, discloses, as a high toughness material, an Fe-Al-base intermetallic compound material having an Al content of 36.8 to 49.4 at.%. As with the conventional heat resisting materials, this intermetallic compound material contains Cr from the viewpoint of improving the toughness.
  • Japanese Unexamined Patent Publication (Kokai) No. 56-58950 discloses an alloy, having an Al content of 0.72 to 18.7 at.%, for a heat treatment roll having an improved pickup property.
  • Japanese Unexamined Patent Publication (Kokai) No. 57-126949 discloses an alloy, having an Al content of 17 to 32.7 at.%, as a vibration control alloy which causes regular-irregular transformation.
  • Japanese Unexamined Patent Publication (Kokai) No. 62-270452 discloses an alloy, having an Al content of 13.5 to 37.3 at.% and a C content of 0.004 to 3.2 at.%, for a carbon fiber-reinforced concrete structure with a reinforcing bar being embedded therein, and Japanese Unexamined Patent Publication (Kokai) No.
  • 6-25800 discloses an alloy, having an Al content of 25 to 50 at.%, for a high-strength and abrasion-resisting material with a carbide being dispersed therein. None of the above known techniques, however, disclose an Fe-Al-C ternary alloy as at least heat resisting material.
  • Al cast iron it is known that, by virtue of a strong Al2O3 film formed by Al incorporated on the surface of the Al cast iron, the Al cast iron does not permit the penetration of oxygen thereinto, has excellent oxidation resistance at a high temperature, is less likely to cause growth of a carbide, and has excellent heat resistance (see, for example, "Tokushu Chutetsu (Special Cast Iron),” 3rd edition, published by Nikkan Kogyo Shimbun, Ltd., 1960).
  • An object of the present invention is to study an Fe-Al-C-base alloy as a ternary alloy with a view to solving the above problems of an Fe-Al-base alloy and to provide a high heat-resisting iron-base alloy having lowered average coefficient of linear expansion, enhanced transformation temperature, and excellent tensile strength.
  • Another object of the present invention is to provide a high heat-resisting iron-base alloy mainly consisting of Fe, Al, and C alone without use of conventional expensive alloying elements, such as Cr and Ni, which high heat-resisting iron-base alloy is inexpensive and has improved mechanical properties equal or superior to the conventional alloys.
  • a further object of the present invention is to provide a high heat-resisting iron-base alloy through study of ingredients capable of reducing the problem associated with the production of an Fe-Al-base alloy, particularly improving the castability.
  • Fig. 1 is a diagram showing the scope of the first invention in terms of the relationship between the C content and the Al content.
  • Fig. 2 is a diagram showing the scope of the second invention in terms of the relationship between the C content and the Al content.
  • Fig. 3 is a diagram showing the scope of the third invention in terms of the relationship between the C content and the Al content.
  • Fig. 4 is a diagram showing the scope of the fourth invention in terms of the relationship between the C + 0.75Si amount and the Al content.
  • Figs. 5(a) to 5(c) are metallic structure photographs of Fe-10 at.% Al-2 at.% C alloy showing the effect of the refining element according to thirteenth and fourteenth claims, Fig. 5(a) shows without addition, Fig. 5(b) shows with addition of 0.8 at.% TiB2, Fig. 5(c) shows with addition of 1.9 at.% TiB2.
  • the alloy of the first invention has a low coefficient of thermal expansion and creates neither significant strain nor significant stress even under high temperature environments and, hence, can be an excellent heat resisting material.
  • the alloy of the second invention has a high transformation temperature and creates neither significant expansion nor significant shrinkage even under high temperature conditions and, hence, can be an excellent heat resisting material.
  • the alloy of the third invention has a low coefficient of thermal expansion and, in addition, high tensile strength and, hence, can be an excellent heat resisting material.
  • the oxidation resistance becomes unsatisfactory, while when it exceeds 28 at.%, the coefficient of thermal expansion becomes large, making it difficult to use the alloy as a heat resisting material.
  • the C content exceeds 24 at.%, the melting point of the alloy is high, making it very difficult to melt the alloy.
  • the lower limit of the C content is more than 0 at.% exclusive of the value on the line C: of 0 at.% in Fig. 1.
  • Points E, F, G, H, and I in Fig. 2 are each a boundary point where two regions cross. 5y - 8z ⁇ 25 (here, z ⁇ 5 at.%) 5y - 2z ⁇ 55 (5 at.% ⁇ z ⁇ 10 at.%) y ⁇ 15 (10 at.% ⁇ z ⁇ 15 at.%) y + 3z ⁇ 60 (15 at.% ⁇ z) wherein y and z represent a value of Al at.% and a value of C at.%, respectively, and the formulae in parentheses represent applicable content regions in respective inequalities.
  • the lower limit of the C content is more than 0 at.% exclusive of the value on the line C: of 0 at.% in Fig. 2.
  • the transformation temperature of the material is 800°C or above, indicating that the material can be used as a heat resisting material at a temperature up to 800°C or above and, hence, is suitable for use in high temperature environments of exhaust systems and other systems of vehicles.
  • the alloy of the third invention should satisfy the requirement specified in the first invention and a requirement represented by the following formula, that is, has a composition falling within the range shown in Fig. 3. C ⁇ 12 at.%
  • This limitation is provided because when the C content exceeds 12 at.%, the tensile strength cannot be provided, rendering the strength of the alloy unsatisfactory.
  • Fe-Al-Si alloy falls within the area formed by connecting points A, J, L, M, B, C and D shown in Fig. 4 and satisfies the formulas hereunder.
  • z total C + 0.75Si 0.2 at.% ⁇ Si ⁇ 10 at.%
  • the compositions of Al, C and Si are in the range of satisfying the above three conditions.
  • Si effects changing the transformation temperature, with the result that the heat resistance can be improved by rising the limited temperature of the heat resistance application. More, Si improves the resistance to oxidation, with the result that the heat resistance of the material can be improved.
  • mechanical properties Si can enhance graphitization in the composition range of forming a graphite, with the result that castability and workability can be improved. More, Si improves strength and ductility regardless of a graphite formation.
  • Si exceeds 10 at.% of the above range, elongation deteriorates and brittleness will be caused.
  • the addition of 0.2 at.% or more of Ti, V, Cr, Ta, W, Nb and Mn as the graphitizer can enhance graphitization in the composition range of forming the graphite, with the result that castability and workability can be improved with increasing strength and ductility of the matrix. More, strength can be improved by dispersing the formed carbides.
  • the addition of the elements exceeds 2 at.%, the carbides become excessive, with the result that ductility also deteriorates with the decreasing workability due to hardening. Therefore, the elements are limited to the range of from 0.2 to 2.0 at.% in the invention.
  • B and Zr are limited to the range of from 0.2 to 2.0 at.% and P is limited to the range of from 0.01 to 2.0 at.%.
  • the addition of 0.2 at.% or more of Ni and Cu can enhance graphitization in the composition range of forming the graphite, with the result that castability and workability with increasing strength and ductility of the matrix.
  • the elements are limited to the range of from 0.2 to 5.0 at.% in the invention.
  • the addition of 0.1 at.% or more of Ti, V, Cr, Ta, B, Mo, Sm, Sn, FeB, TaB2, TiB2, HfC, TiC, Ag, Ca, Co, Ge, Hf, P, Th, B4C, NbB2, Mo2C, VC, Cr2N, Fe3N, Fe4N, TiN and VN can refine the structure, with the result that strength can be improved with preventing casting defects, such as cracks, segregation or the like. On the other hand, the effect will be saturated if the addition exceeds 2 at.%.
  • the addition of 0.1 at.% or more of Ti, Zr, Ce, Er, Gd, Nd, Dy, La, Pr, Y, BaAl4 and Fe4N softens the structure, with the result that heat fatigue strength can be improved, and further workability can also be improved due to increasing elongation. On the other hand, the effect can be saturated if the addition exceeds 2 at.%. More, the elements of the above may be added as a misch metal.
  • Mg enables elongation to increase, and heat fatigue of the material to improve.
  • Bal. 23.1 17.0 12 4.7 1.3 Bal. 14.9 13 3.8 5.7 Bal. 15.3 14 4.2 16.1 Bal. 14.3 Comp. Ex. 15 30.5 0 Bal. 20.5 16 30.1 9.8 Bal. 18.3 17 34.7 0.9 Bal. 22.7 18 37.1 11.3 Bal. 23.1
  • the average coefficients of linear thermal expansion are 14.3 to 17.0 which are better than the average coefficients of linear thermal expansions 18.3 to 23.1 for Comp.Ex. Nos. 15 to 18.
  • the average coefficient of linear thermal expansion becomes excessively large and equal to or larger than that of the austenitic cast iron as a heat resisting material, rendering the material unsuitable for use as a heat resisting material.
  • the transformation temperatures during cooling are 835°C or above which are higher, i.e., better than the transformation temperatures 693 to 748°C for Comp. Ex. Nos. 29 to 33.
  • the transformation temperature is above 800°C which exceeds that of high-silicon heat-resisting cast iron.
  • the coefficient of thermal expansion is low, i.e., excellent, indicating that the materials of the present invention have good properties as a heat resisting material.
  • the tensile strengths at room temperature are 489 to 959 MPa which are better than the tensile strengths at room temperature 96 to 195 MPa for Comp.Ex. Nos. 42 to 44. Specifically, when the C content exceeds 12 at.%, the tensile strength at room temperature is lowered. For heat resisting materials, the tensile strength at a high temperature is about 1/3 of that at room temperature. This value is proportional to that at room temperature. Further, as demonstrated in Example 1, the coefficient of thermal expansion is low, i.e., excellent.
  • the transformation temperatures are 808°C or above during cooling and 837°C or above during heating, respectively, which are higher, i.e., better than the transformation temperatures of 730°C or under during cooling and 820°C or under during heating for Comp. Ex. Nos. 51 and 52. Therefore, as mentioned above, the limited temperature of the heat resistance application rises, with the result that the heat resistance can be improved and the graphitization can be enhanced.
  • the graphite amount of adding the graphitizer in the present invention is 3.1 to 7.5%
  • the Comp. Ex. without adding the graphitizer has 2.6% of the graphite amount, i.e., the effect of the graphitizer according to the present invention is remarkably exhibited in the scope of the present invention.
  • Figs. 5(a) to 5(c) show the metallic structure photographs of three magnifications after casting of Fe - 10% at.% Al - 2 at.% C alloy without addition, of Fe - 10 at.% Al - 2 at.% C alloy adding 0.8 at.% TiB2 and of Fe - 10 at.% Al - 2 at.% alloy adding 1.9 at.% TiB2, respectively. From these photographs, the above effect of refining can remarkably exhibited in the scope of the present invention.
  • the hardness values are 221 to 306 of Vickers Hardness, i.e., better than the hardness value 334 of Vickers Hardness without addition. Namely, the effect of improving softening and ductility can remarkably exhibited in the scope of the present invention.
  • the elongation values are 3.9 to 8.1%, i.e., better than the elongation values 0.4 to 2.7% without addition. Namely, the effect of improving elongation can remarkably exhibited by adding Mg to the alloys according to the present invention.
  • the materials of the present invention despite the fact that they are mainly ternary alloys consisting of Fe, Al, and C without use an amount of expensive alloying elements, such as Cr and Ni, have excellent high-temperature heat resisting properties, i.e., low coefficient of linear thermal expansion and enhanced transformation temperature and excellent tensile strength, and, hence, can be applied to members to be used at higher temperatures.
  • the materials of the present invention have a transformation temperature of 800°C or above, rendering the materials of the present invention suitable for use in high temperature environments in an exhaust system and other systems of vehicles.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
EP95305233A 1994-08-05 1995-07-26 High heat-resisting iron-base alloy Withdrawn EP0695811A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP184636/94 1994-08-05
JP18463694 1994-08-05
JP20507895A JPH08100243A (ja) 1994-08-05 1995-07-20 高耐熱性鉄基合金
JP205078/95 1995-07-20

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EP0695811A1 true EP0695811A1 (en) 1996-02-07

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EP95305233A Withdrawn EP0695811A1 (en) 1994-08-05 1995-07-26 High heat-resisting iron-base alloy

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EP (1) EP0695811A1 (ja)
JP (1) JPH08100243A (ja)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999009334A2 (de) * 1997-08-14 1999-02-25 SCHWäBISCHE HüTTENWERKE GMBH Verbundwerkstoff mit hohem anteil intermetallischer phasen, vorzugsweise für reibkörper
US7534314B2 (en) 2005-06-13 2009-05-19 Daimler Ag High carbon steel with superplasticity
DE102007056144A1 (de) * 2007-11-16 2009-05-20 Volkswagen Ag Abgaskrümmer oder Turboladergehäuse aus einer FeAl-Stahllegierung
WO2017125147A1 (de) 2016-01-20 2017-07-27 Thyssenkrupp Steel Europe Ag Stahlflachprodukt und verfahren zu seiner herstellung

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3589797B2 (ja) * 1996-06-21 2004-11-17 株式会社神戸製鋼所 耐摩耗高Ｍｎ鋳鋼
JP4852737B2 (ja) * 2004-09-27 2012-01-11 国立大学法人 千葉大学 リサイクル型Ｆｅ−Ａｌ複合材料の製造方法
JP2020084294A (ja) * 2018-11-30 2020-06-04 株式会社日立製作所 積層造形用粉末、積層造形体および積層造形体の製造方法

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5658950A (en) 1979-10-16 1981-05-22 Kubota Ltd Heat treating roller
JPS56129303A (en) * 1980-03-13 1981-10-09 Tdk Corp Magnetic recording substance
JPS57126949A (en) 1980-06-19 1982-08-06 Kajita Tsunehiro Vibration-damping alloy and method for producing the same
JPS57203750A (en) 1981-06-09 1982-12-14 Nec Corp Alloy for composite magnetic material
US4501612A (en) * 1983-10-27 1985-02-26 The University Of Alabama Compacted graphite cast irons in the iron-carbon-aluminum system
GB2186886A (en) * 1986-02-25 1987-08-26 Nippon Steel Corp Steel composition
JPS62240746A (ja) * 1986-04-11 1987-10-21 Yamaha Motor Co Ltd ブレ−キの被制動部材
JPS62270452A (ja) 1986-05-15 1987-11-24 新日本製鐵株式会社 炭素繊維強化コンクリ−ト構造体
JPS63109141A (ja) * 1986-10-24 1988-05-13 Nissan Motor Co Ltd 耐摩耗材料
JPH03226547A (ja) 1990-01-30 1991-10-07 Toyota Motor Corp 高靭性ＦｅＡｌ金属間化合物材料
JPH0625800A (ja) 1992-07-06 1994-02-01 Daido Steel Co Ltd 高強度・耐摩耗性材料

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5658950A (en) 1979-10-16 1981-05-22 Kubota Ltd Heat treating roller
JPS56129303A (en) * 1980-03-13 1981-10-09 Tdk Corp Magnetic recording substance
JPS57126949A (en) 1980-06-19 1982-08-06 Kajita Tsunehiro Vibration-damping alloy and method for producing the same
JPS57203750A (en) 1981-06-09 1982-12-14 Nec Corp Alloy for composite magnetic material
US4501612A (en) * 1983-10-27 1985-02-26 The University Of Alabama Compacted graphite cast irons in the iron-carbon-aluminum system
GB2186886A (en) * 1986-02-25 1987-08-26 Nippon Steel Corp Steel composition
JPS62240746A (ja) * 1986-04-11 1987-10-21 Yamaha Motor Co Ltd ブレ−キの被制動部材
JPS62270452A (ja) 1986-05-15 1987-11-24 新日本製鐵株式会社 炭素繊維強化コンクリ−ト構造体
JPS63109141A (ja) * 1986-10-24 1988-05-13 Nissan Motor Co Ltd 耐摩耗材料
JPH03226547A (ja) 1990-01-30 1991-10-07 Toyota Motor Corp 高靭性ＦｅＡｌ金属間化合物材料
JPH0625800A (ja) 1992-07-06 1994-02-01 Daido Steel Co Ltd 高強度・耐摩耗性材料

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
"Tokushu Chutetsu (Special Cast Iron)", 1960, NIKKAN KOGYO SHIMBUN, LTD.
PATENT ABSTRACTS OF JAPAN vol. 006, no. 006 (E - 089) 14 January 1982 (1982-01-14) *
PATENT ABSTRACTS OF JAPAN vol. 007, no. 053 (C - 154) 3 March 1983 (1983-03-03) *
PATENT ABSTRACTS OF JAPAN vol. 012, no. 117 (C - 487) 13 April 1988 (1988-04-13) *
PATENT ABSTRACTS OF JAPAN vol. 012, no. 353 (C - 530) 21 September 1988 (1988-09-21) *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999009334A2 (de) * 1997-08-14 1999-02-25 SCHWäBISCHE HüTTENWERKE GMBH Verbundwerkstoff mit hohem anteil intermetallischer phasen, vorzugsweise für reibkörper
WO1999009334A3 (de) * 1997-08-14 1999-04-15 Schwaebische Huettenwerke Gmbh Verbundwerkstoff mit hohem anteil intermetallischer phasen, vorzugsweise für reibkörper
US7534314B2 (en) 2005-06-13 2009-05-19 Daimler Ag High carbon steel with superplasticity
DE102005027258B4 (de) * 2005-06-13 2013-01-31 Daimler Ag Hochkohlenstoffhaltiger Stahl mit Superplastizität
DE102007056144A1 (de) * 2007-11-16 2009-05-20 Volkswagen Ag Abgaskrümmer oder Turboladergehäuse aus einer FeAl-Stahllegierung
WO2017125147A1 (de) 2016-01-20 2017-07-27 Thyssenkrupp Steel Europe Ag Stahlflachprodukt und verfahren zu seiner herstellung

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JPH08100243A (ja) 1996-04-16

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