US20060266443A1 - Forged piston - Google Patents

Forged piston Download PDF

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Publication number
US20060266443A1
US20060266443A1 US11/435,399 US43539906A US2006266443A1 US 20060266443 A1 US20060266443 A1 US 20060266443A1 US 43539906 A US43539906 A US 43539906A US 2006266443 A1 US2006266443 A1 US 2006266443A1
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United States
Prior art keywords
aluminum alloy
less
piston
strength
forged piston
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Abandoned
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US11/435,399
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English (en)
Inventor
Tomoo Oka
Hidenori Fujii
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Honda Motor Co Ltd
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Honda Motor Co Ltd
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Publication date
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Assigned to HONDA MOTOR CO., LTD. reassignment HONDA MOTOR CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FUJII, HIDENORI, OKA, TOMOO
Publication of US20060266443A1 publication Critical patent/US20060266443A1/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/02—Alloys based on aluminium with silicon as the next major constituent

Definitions

  • the present invention relates to a forged piston made of an aluminum alloy.
  • a piston is used in an internal combustion engine designed for converting energy produced by combustion to motive power. Improvements may yet be made in such pistons to provide a piston that is lighter and has more excellent properties in heat resistance and abrasion resistance. A piston that can meet such properties are in demand. Particularly, forged pistons made of an aluminum alloy attract attention. Past piston designs have been proposed in attempt to achieve such desirable characteristics.
  • JP-A No. 216487/1995 proposes an aluminum alloy on which abrasion resistance is conferred by Si, which includes a precipitation hardening element of Cu and Mg and further includes Fe and Ni, elements that contribute to the enhancement in strength, and includes Mn, Ti, Zr and V provided for the effect of recovery at high temperature and the effect of inhibiting recrystallization coexist.
  • Si which includes a precipitation hardening element of Cu and Mg and further includes Fe and Ni, elements that contribute to the enhancement in strength, and includes Mn, Ti, Zr and V provided for the effect of recovery at high temperature and the effect of inhibiting recrystallization coexist.
  • JP-A No. 54053/2000 proposes an aluminum alloy in which the maximum length of a crystallized substance by casting is controlled to be 200 ⁇ m and proposes that the strength of which at further higher temperature is enhanced by strengthening the dispersion of the crystallized substances.
  • the specific gravity increases and the enhancement of engine performance by lightening is hindered.
  • JP-A No. 260089/1996 proposes that the strength at high temperature equal to or exceeding 250° C. is enhanced by setting the percentage content of Ni, out of the elements of an Al—Si aluminum alloy used in a piston, to 2 to 6 wt %.
  • the percentage content of Ni out of the elements of an Al—Si aluminum alloy used in a piston, to 2 to 6 wt %.
  • Cu and Ni are included in a large quantity, the specific gravity increases and as the weight increases, a merit that the strength is enhanced is conversely lost.
  • a bulky crystallized substance causes a defect in forging and remarkably deteriorates the strength.
  • an aluminum alloy for a forged piston may be employed, such as A4032 and A2618 according to JIS.
  • A4032 is material depending upon precipitation hardening, the strength of the piston is deteriorated when the material is exposed to high temperature.
  • Si is included in A2618, the coefficient of thermal expansion increases and the sliding performance of the piston is deteriorated.
  • a forged piston comprises an aluminum alloy which includes 8 to 18 wt % of Si (wt %: percentage by weight), 0.5 to 3 wt % of Cu and 1 to 5 wt % of Ni, which further includes Al and unavoidable impurities, in which more Ni is included than Cu and in which the maximum length of an intermetallic compound generated by Al and Ni is 3 to 100 ⁇ m.
  • a forged piston comprises an aluminum alloy which includes 8 to 18 wt % of Si, 0.5 to 3 wt % of Cu, 1 to 5 wt % of Ni and 2.0 wt % or less of Fe, which further includes Al and unavoidable impurities, in which the total in wt % of Ni and Fe is more than Cu and is equivalent to 5 wt % or less and in which the maximum length of an intermetallic compound generated by Al, Ni and Fe is 3 to 100 ⁇ m.
  • the aluminum alloy further includes 2.0 wt % or less of Mg.
  • the aluminum alloy further includes at least either of 0.25 wt % or less of Zr, or 0.25 wt % or less of Ti, and the total of Zr and Ti in the case where Zr and Ti are included is 0.3 wt % or less.
  • the aluminum alloy further includes 2.0 wt % or less of at least one type of the total of Fe and Mn, and 2.0 wt % or less of the total of Fe and Cr ⁇ 5.
  • a mean particle diameter of eutectic Si and pro-eutectic Si in the metallographic structure of the aluminum alloy is 10 to 100 ⁇ m.
  • a forged piston can be provided with excellent properties in heat resistance and abrasion resistance and made of the light aluminum alloy can be acquired by the aluminum alloy the strength at high temperature of which is enhanced, securing toughness and productivity.
  • FIG. 1 illustrates a perspective view of one embodiment of a forged piston according to the inventive principles.
  • FIG. 2 illustrates a graph showing the results of measurement in which each fatigue strength of a forged piston according to the principles of the invention and conventional type forged pistons is measured.
  • FIG. 3 illustrates a photograph showing metallographic structure in the forged piston according to the principles of the invention.
  • FIG. 4 shows a photograph showing metallographic structure in a forged piston in a comparative example.
  • the forged piston for example, as shown in FIG. 1 , has a structure provided with a piston head 1 for receiving an explosion load in a cylinder of an internal combustion engine, a skirt 2 for smoothly reciprocating the piston in the cylinder, a plurality of piston-ring grooves 3 for incorporating a piston ring which slidingly contacts an inner wall of the cylinder in the piston and a pin hole 4 for inserting a piston pin to connect the piston to a connecting rod.
  • the forged piston to which the inventive concepts may be applied is characterized in that it is made of an aluminum alloy which includes 8 to 18 wt % of Si, 0.5 to 3 wt % of Cu and 1 to 5 wt % of Ni, which further includes Al and unavoidable impurities, in which more Ni is included than Cu and in which the maximum length of an intermetallic compound generated by Al and Ni is 3 to 100 ⁇ m.
  • the forged piston to which the inventive concepts may be applied is characterized in that it is made of an aluminum alloy which includes 8 to 18 wt % of Si, 0.5 to 3 wt % of Cu, 1 to 5 wt % of Ni and 2.0 wt % or less of Fe, which further includes Al and unavoidable impurities, in which the total in wt % of Ni and Fe is more than Cu and is equivalent to 5 wt % or less and in which the maximum length of an intermetallic compound generated by Al, Ni and Fe is 3 to 100 ⁇ m.
  • a coefficient of linear expansion of the piston reciprocated in the high-temperature cylinder is inhibited by Si and its dimensional change can be minimized.
  • sliding resistance at high speed can be enhanced.
  • the material strength at room temperature to 200° C. can be enhanced by Cu.
  • the aluminum alloy crystallizes an Al—Cu—Ni ternary compound and enhances material strength up to 250° C.
  • an Al—Ni compound in the aluminum alloy enhances strength up to high temperature of 250° C. or higher, inhibits the generation of a bulky crystallized substance, and prevents an internal defect and a crack in forging.
  • the Al—Ni compound in the aluminum alloy can enhance the strength even when exposed to high temperatures of 250° C. or higher, can inhibit the generation of a bulky crystallized substance, and can prevent an internal defect and an occurrence of a crack caused by forging.
  • the forged piston to which the inventive concepts may be applied can be made into a forged piston of light aluminum alloy with excellent properties in heat resistance and abrasion resistance by the aluminum alloy, the strength of which at high temperatures can be enhanced, while securing toughness and productivity.
  • Mg in the forged piston to which the inventive concepts may be applied, Mg can be further included in the aluminum alloy.
  • the percentage content of Mg shall be 2.0 wt % or less.
  • the strength of the material can be enhanced by the strengthening of solid solution.
  • the forged piston to which the inventive concepts may be applied, at least either of Zr or Ti can be included in the aluminum alloy.
  • the percentage content of Zr would be 0.25 wt % or less and that of Ti would be 0.25 wt % or less.
  • the total of Zr and Ti would be 0.3 wt % or less.
  • the forged piston to which the inventive concepts may be applied, at least either of Mn or Cr can be included in the aluminum alloy.
  • Mn the total of Fe and Mn would be 2.0 wt % or less and as to the percentage content of Cr, the total of Fe and Cr ⁇ 5 would be 2.0 wt % or less, where “Cr ⁇ 5” is five times a wt % of Cr.
  • Cr ⁇ 5 is five times a wt % of Cr.
  • the particle size of eutectic Si and pro-eutectic Si in the metallographic structure of the aluminum alloy can be 10 to 100 ⁇ m.
  • sufficient toughness and productivity are secured and the sliding performance of the piston can be enhanced.
  • Si is an element that can inhibit the linear expansion of the piston used at high temperature, minimize its dimensional change and resist sliding at high speed.
  • Si is added in a large quantity, bulky pro-eutectic Si is crystallized, and the toughness and the workability of the material are deteriorated. Therefore, in the invention, to acquire sufficient effect, its lower limit is 8 wt % and to secure sufficient toughness and workability as a piston, its upper limit is 18 wt %.
  • Cu is an element for enhancing material strength between room temperature to approximately 200° C. by the strengthening of solid solution.
  • the crystallization of the Al—Ni compound is hindered, the enhancement of material strength at 250° C. or higher temperatures is hindered, and a light piston cannot be acquired because the specific gravity of the material increases.
  • the lower limit of Cu is 0.5 wt % and to inhibit the increase of the specific gravity without preventing the crystallization of the Al—Ni compound, its upper limit is 3 wt %.
  • Ni is an element for crystallizing the Al—Cu—Ni ternary compound by coexisting with Cu and enhancing strength at high temperature. The effect can act up to 250° C. However, to enhance strength up to 250° C. or higher temperatures, the Al—Ni compound is required to be crystallized. To crystallize the Al—Ni compound, Ni is required to be added in a larger quantity than Cu. However, when Ni is added in a large quantity, a crystallized substance is made bulky, the toughness of the material is deteriorated, which causes cracking and defects in forging.
  • the lower limit of Ni is 1 wt % and to inhibit the crystallization of a bulky compound, its upper limit is 5 wt %. Further, Ni is added in a larger quantity than Cu.
  • Fe is an element for crystallizing a compound with Al like Ni and enhancing strength at high temperature and can be arbitrarily added, however, to inhibit bulking a crystallized substance, Fe equivalent to 2 wt % maximum can be included.
  • Al—Ni—Fe compound is crystallized in the case where Fe and Ni are simultaneously added, the total of Ni and Fe would be 5 wt % or less. Further, the total of Ni and Fe would be more than Cu.
  • Mg is an element for enhancing the strength of the material by the strengthening of solid solution and can be arbitrarily added, however, as the toughness of the material is deteriorated by the crystallization of Mg 2 Si when Mg is added in a large quantity, a maximum of 2.0 wt % of Mg would be included.
  • Zr and Ti are both elements that contribute to making a crystal grain minute and enhancing heat resistance. However, when Zr and Ti are added in a large quantity, either or both crystallize a bulky compound with Al. Therefore, the percentage of Zr and Ti included would be respectively 0.25 wt % maximum to inhibit the generation of a bulky crystallized substance. The total of Zr and Ti when they are both included would be 0.3 wt % or less.
  • Mn and Cr are elements for enhancing strength at high temperature and making the metallographic structure minute, however, when they are added at the same time as Fe, a bulky compound is generated together with Al and Fe and the malleability is deteriorated. Therefore, an upper limit for the total of these Mn, Cr and Fe is preferred. That is, the total of Fe and Mn would be 2.0 wt % or less and the total of Fe and Cr ⁇ 5 would be 2.0% less.
  • An intermetallic compound of Al, Ni and a transition element such as Fe enhances material strength up to high temperature by inhibiting the transformation of material.
  • a lower limit of the maximum length is 3 ⁇ m.
  • an upper limit of the maximum length is 100 ⁇ m so that the intermetallic compound can be resistant to forging.
  • Eutectic Si and pro-eutectic Si are effective to enhance sliding performance, however, when the particle sizes of them are made too excessive, cracking and defects are caused in forging. Therefore, a lower limit of the particle sizes of eutectic Si and pro-eutectic Si would be 3 ⁇ m to gain sufficient effect and an upper limit would be 100 ⁇ m to resist forging.
  • an aluminum alloy including each additional element shown in Table 1 is forged into the shape of a piston and forged pistons of samples 1 to 12 are produced.
  • a mechanical characteristic and malleability are evaluated.
  • the samples 1 to 5 of these are the embodiments that meet conditions of the inventive principles and the samples 6 to 10 are comparative examples that do not meet the conditions of the inventive principles.
  • the sample 11 shows JIS A4032 and the sample 12 shows JIS AC8A.
  • each test piece is cut from the forged piston of each sample 1 to 12, after it is kept at 300° C. for 100 hours, a tension test is made in an atmosphere of 300° C., and the tensile strength and the extension of each test piece are measured.
  • each sample 1 to 12 is heated at 350° C. or higher and it is checked whether a crack is made or not in forging the shape of the piston.
  • ⁇ shows a case that no crack is made and ⁇ shows a case that a crack is made.
  • Table 1 show that the samples 1 to 6 (the embodiments) higher tensile strength than A4032 and show larger extension than AC8A. Besides, the samples 1 to 6 have no problem in relation to malleability and also show no increase in specific gravity to the extension that the specific gravity has an effect upon each actual piston. Further, the embodiments 2 and 3 show higher tensile strength and larger extension than AC8A. In the meantime, the embodiments 1, 4 and 5 show higher strength than AC8A in relation to fatigue strength which is important in each actual piston and owing to the enhancement of each internal quality by minute metallographic structure and malleability, though each tensile strength is inferior to that in AC8A.
  • JP-A No. 54053/2000 shows the effect of micronizing a crystallized substance by Mn and shows that the maximum length of the crystallized substance is reduced by changing the shape of the crystallized substance from a sharp and narrow shape to a lump.
  • the volume itself of an individual crystallized substance is not reduced and the maximum length is also at a level of 100 ⁇ m. Therefore, the effect of micronization to the extent that malleability is enhanced, cannot be recognized as in the presently disclosed inventive concepts.
  • each specific gravity is 2.75 or less and further lightening is enabled by inhibiting the increase of the specific gravity, maintaining high strength resistant to high temperature and excellent malleability.
  • the results of the measurement shown in FIG. 2 show that in the sample 4, though the tensile strength is lower than that in AC8A, the fatigue strength is higher by 10% or more than that in AC8A.
  • the results also show that the fatigue strength in the sample 4 is higher by 40% or more than that in A40432 and that the strength of sample 4 is greatly enhanced.
  • FIG. 3 shows a photograph of a microstructure showing the forged piston in the sample 4 (the invention) and FIG. 4 shows a photograph of a microstructure in the sample 9 (the comparative example).
  • These photographs of the microstructures shown in FIGS. 3 and 4 show that in the forged piston in the comparative example, the maximum length of an intermetallic compound in metallographic structure is 100 ⁇ m or longer, while in the forged piston according to the present inventive concepts, the intermetallic compounds in the metallographic structure are minutely and homogeneously dispersed and are controlled at a level at which the malleability is not hindered.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
US11/435,399 2005-05-26 2006-05-16 Forged piston Abandoned US20060266443A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2005-153740 2005-05-26
JP2005153740A JP5116951B2 (ja) 2005-05-26 2005-05-26 鍛造ピストン

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070062479A1 (en) * 2005-09-21 2007-03-22 Honda Motor Co., Ltd. Piston for internal combustion engine
EP1975262A3 (en) * 2007-03-30 2010-09-15 Kabushiki Kaisha Toyota Chuo Kenkyusho Aluminum alloys for casting, aluminum alloy castings and process for producing aluminum alloy castings
CN104212987A (zh) * 2014-09-19 2014-12-17 无锡贺邦金属制品有限公司 铸造用铝合金的制备方法
CN104233012A (zh) * 2014-09-19 2014-12-24 无锡贺邦金属制品有限公司 铸造用铝合金
CN111705246A (zh) * 2020-07-04 2020-09-25 安徽恒明工程技术有限公司 一种铝活塞用的铝合金材料及其加工方法

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4982159B2 (ja) * 2006-11-16 2012-07-25 三協マテリアル株式会社 アルミニウム合金ビレット
JP5150406B2 (ja) * 2008-08-12 2013-02-20 昭和電工株式会社 ピストン素材の製造方法
JP6103382B2 (ja) * 2013-10-31 2017-03-29 スズキ株式会社 アルミニウム合金
DE102015205895A1 (de) * 2015-04-01 2016-10-06 Federal-Mogul Nürnberg GmbH Aluminium-Gusslegierung, Verfahren zur Herstellung eines Motorbauteils, Motorbauteil und Verwendung einer Aluminium-Gusslegierung zur Herstellung eines Motorbauteils

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0663567B2 (ja) * 1985-03-19 1994-08-22 トヨタ自動車株式会社 アルミニウムピストン
JPS6210237A (ja) * 1985-07-09 1987-01-19 Showa Denko Kk 熱間鍛造用アルミニウム合金
JPH03180440A (ja) * 1989-08-23 1991-08-06 Kubota Corp 耐熱高強度Ａｌ合金材
JP2001200327A (ja) * 2000-01-20 2001-07-24 Kyushu Mitsui Alum Kogyo Kk 高性能ピストン用アルミニウム合金及びピストン製造方法
JP3845035B2 (ja) * 2002-03-27 2006-11-15 日本軽金属株式会社 内燃機関用ピストンの製造方法及び内燃機関用ピストン

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070062479A1 (en) * 2005-09-21 2007-03-22 Honda Motor Co., Ltd. Piston for internal combustion engine
US7398754B2 (en) * 2005-09-21 2008-07-15 Honda Motor Co., Ltd. Piston for internal combustion engine
EP1975262A3 (en) * 2007-03-30 2010-09-15 Kabushiki Kaisha Toyota Chuo Kenkyusho Aluminum alloys for casting, aluminum alloy castings and process for producing aluminum alloy castings
CN104212987A (zh) * 2014-09-19 2014-12-17 无锡贺邦金属制品有限公司 铸造用铝合金的制备方法
CN104233012A (zh) * 2014-09-19 2014-12-24 无锡贺邦金属制品有限公司 铸造用铝合金
CN111705246A (zh) * 2020-07-04 2020-09-25 安徽恒明工程技术有限公司 一种铝活塞用的铝合金材料及其加工方法

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JP5116951B2 (ja) 2013-01-09
JP2006328482A (ja) 2006-12-07

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