JPS5856020B2 - Method for manufacturing sintered mechanical parts with excellent specific strength - Google Patents

Description

【発明の詳細な説明】 本発明は比強度に優れる焼結機械部品の製造方法に関す
るものであり、特に本発明は、できるだけ少ないＭｎお
よびＣｒを合金させた本質的に焼入性に優れる合金鋼粉
より主としてなる原料粉末の圧粉体を還元性ガス雰囲気
中で焼結した後、焼結温度付近から直ちに油焼入れする
ことを特徴とする比強度に優れる焼結機械部品の製造方
法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing sintered mechanical parts having excellent specific strength, and in particular, the present invention relates to an alloy steel having essentially excellent hardenability, which is alloyed with as little Mn and Cr as possible. This invention relates to a method for producing sintered machine parts with excellent specific strength, which comprises sintering a green compact made primarily of raw material powder in a reducing gas atmosphere and then immediately quenching it in oil from around the sintering temperature. be.

近年、鉄系焼結機械部品の生産が、次第に高強度、高耐
摩耗性部品の分野に及び始めたことから、原料粉末に対
する要請も、純鉄粉から合金鋼粉へ次第に変りつつある
。In recent years, the production of iron-based sintered machine parts has gradually begun to reach the field of high-strength, high-wear-resistant parts, and the requirements for raw material powder are also gradually changing from pure iron powder to alloy steel powder.

すなわち、これら高強度、高耐摩耗性部品の製造が、従
来の焼結のみによる方法から、焼結後、焼入れ一焼戻し
の熱処理を施す方法へと転換しつつあるため、それに伴
なって原料粉末も変換を余儀なくされている次第である
。In other words, the production of these high-strength, highly wear-resistant parts is changing from the conventional method of only sintering to a method of heat treatment of quenching and tempering after sintering, and as a result, the raw material powder However, they are also being forced to undergo transformation.

このように焼結部品に熱処理を施すことが基本になると
、原料としての合金鋼粉にも本質的に焼入性に優れるこ
とが要求され、しかもより低廉でなければならないこと
から、Ｍｎ、Ｃｒを主要合金元素とせざるを得なくなる
。When it becomes basic to heat treat sintered parts in this way, the alloy steel powder used as a raw material is required to have essentially excellent hardenability, and it also has to be cheaper, so Mn, Cr, etc. must be used as the main alloying element.

しかるに、Ｍｎ。Ｃｒを主体に合金した銅粉を使用する
場合、焼結中と焼結後の徐冷中における酸化に十分注意
しなければならない。However, Mn. When using copper powder alloyed mainly with Cr, sufficient care must be taken to prevent oxidation during sintering and during slow cooling after sintering.

このことは、従来技術による場合とくに問題となる。This is particularly problematic in the case of prior art.

従来の熱処理技術によれば、焼結炉を用いて、圧粉体を
加熱焼結せしめ、焼結完了と同時に降温徐冷して一旦冷
却体となし、次いで、別種の熱処理炉を用いて再加熱後
焼入れるのが普通であった。According to conventional heat treatment technology, a sintering furnace is used to heat and sinter the green compact, and upon completion of sintering, the temperature is lowered and gradually cooled to form a cooling body, and then a different type of heat treatment furnace is used to recycle the compact. It was common to quench after heating.

このように焼結用と焼入用の二度にわたって加熱を行な
うことは、エネルギー的にみて不経済なばかりでなく、
工数的にも、設備的にも無駄があり好ましくない。Performing heating twice for sintering and quenching in this way is not only uneconomical from an energy standpoint, but also
This is undesirable as it is wasteful both in terms of man-hours and equipment.

しかも、焼結後に徐冷処理を伴なうため、Ｍｎ、Ｃｒを
合金させた銅粉を使用する場合には、部品が著しく酸化
されて強度低下を来し、焼結後の焼入処理によっても最
早強度は十分には回復せず、したがって合金鋼粉を使用
することの意義までも失なわれるという欠点があった。Moreover, since slow cooling treatment is required after sintering, if copper powder alloyed with Mn and Cr is used, the parts will be significantly oxidized and their strength will decrease. However, there was a drawback that the strength was no longer fully recovered, and therefore the significance of using alloy steel powder was lost.

本発明は、従来方法による欠点を除去、改善した方法を
提供することを目的とするものであり、特許請求の範囲
記載の方法によって前記目的を達成することができる。An object of the present invention is to provide a method that eliminates and improves the drawbacks of conventional methods, and the above object can be achieved by the method described in the claims.

次に本発明の詳細な説明する。Next, the present invention will be explained in detail.

本発明方法は下記８つの構成要素よりなる。The method of the present invention consists of the following eight components.

〔１〕 原料粉末としては、酸化反応の自由エネルギ
ー変化が−１２０〜−１５０Ｋｃａｌ／ｍｏ１．０２の
範囲内にある元素のうちから、特にＭｎとＣｒを選びこ
れらをそれぞれＭｎ：０．１〜２，３％、Ｃｒ二０．１
〜５．５％主成分中に含有させた合金鋼粉を用いる。[1] As the raw material powder, Mn and Cr are particularly selected from among the elements whose free energy change in oxidation reaction is within the range of -120 to -150 Kcal/mo1.02, and these are respectively Mn:0.1 to 2. ,3%, Cr20.1
An alloyed steel powder containing ~5.5% in the main component is used.

このようにできるだけ少ないＭｎ量およびＣｒ量とした
合金鋼粉末を主体として使用するのは、低廉であること
、および成形体の焼入性に優れるため、製造部品のコス
ト低減を可能とし、しかも部品の高強度化が計れるから
である。Mainly using alloy steel powder with the lowest possible Mn and Cr contents is inexpensive and has excellent hardenability of compacts, which makes it possible to reduce the cost of manufactured parts. This is because high strength can be measured.

一方、上記Ｍｎ、Ｃｒの所定量に対し、さらにＭｏを０
．１〜７．０％含有させ、それらの合計量： Ｍｎ ＋
Ｃｒ −１−Ｍ ｏ＝０．４０〜７．０％にすると、さ
らに比強度の優れた焼結材料が得られるようになる。On the other hand, with respect to the predetermined amounts of Mn and Cr, Mo is further added to 0.
．． 1 to 7.0%, their total amount: Mn +
When Cr -1-Mo = 0.40 to 7.0%, a sintered material with even better specific strength can be obtained.

以下にそれぞれの成分組成限定の理由について述べる。The reasons for limiting the composition of each component will be described below.

Ｍｎは、焼結体の焼入れ性を増し、強度を高めるが、０
．１％未満ではその効果が小さい。Mn increases the hardenability and strength of the sintered body, but 0
．． If it is less than 1%, the effect is small.

また、その量が２．３％を超えると、Ｍｎの固溶により
鋼粉の圧縮性が著しく低下し、かつ鋼粉の酸素量が増加
し、焼結後の焼入れ性も低下するため好ましくない。In addition, if the amount exceeds 2.3%, the compressibility of the steel powder will be significantly reduced due to the solid solution of Mn, and the amount of oxygen in the steel powder will increase, which is undesirable because the hardenability after sintering will also decrease. .

Ｃｒは、焼結体の焼入れ性および焼戻し抵抗を高めるが
、０．１％未満ではその効果が小さく、また、その量が
５．５％を超えると、Ｃｒの固溶およびＣｒのＣ，Ｎと
の強い親和力のため、鋼粉中のＣ，Ｎが増加し、圧縮性
が著しく低下し、かつ鋼粉の酸素量が増加し、焼結後の
焼入れ性も低下するため好ましくない。Cr increases the hardenability and tempering resistance of the sintered body, but if the amount is less than 0.1%, the effect is small, and if the amount exceeds 5.5%, solid solution of Cr and C,N of Cr Due to the strong affinity with steel powder, C and N in the steel powder increase, resulting in a significant decrease in compressibility, an increase in the amount of oxygen in the steel powder, and a decrease in hardenability after sintering, which is not preferable.

Ｍｏについては、焼入れ性および焼戻し抵抗をさらに高
める作用をする。Mo has the effect of further increasing hardenability and tempering resistance.

０．１％未満ではその効果がほとんどない。If it is less than 0.1%, there is almost no effect.

また、７．０％を超えるとＭｏの固溶およびＭｏのＣと
の強い親和力のため、銅粉中のＣが増加し、銅粉の圧縮
性が著しく低下し好ましくない。Moreover, if it exceeds 7.0%, C in the copper powder increases due to the solid solution of Mo and the strong affinity of Mo with C, which is not preferable because the compressibility of the copper powder decreases significantly.

なお、上記Ｍｎ、Ｃｒについては、Ｍｎ単独だと焼戻し
抵抗があまり期待できない。Regarding Mn and Cr, if Mn is used alone, it is not expected that the tempering resistance will be very good.

また、Ｃｒ単独では焼戻し抵抗は出るが、焼入れ性につ
いてはＭｎ程の向上が望めない。Further, although Cr alone provides good tempering resistance, it cannot be expected to improve hardenability as much as Mn.

本発明は焼入れ性、焼戻し性の両方を満足するために、
Ｍｎ、Ｃｒをあわせて加える必要があり、所定の範囲内
で一緒に含有させるのである。In order to satisfy both hardenability and temperability, the present invention
It is necessary to add Mn and Cr together, and they are contained together within a predetermined range.

また、上記のＭｎ、Ｃｒを主体とする主成分に対しては
、副成分として、後述するような目的で酸化反応の自由
エネルギー変化が−１２０〜−１５０Ｋｃ ａｌｌ／ｍ
ｏｉｌ ０２の範囲内にあるＮｂ、Ｖ、Ｈのうちから選
ばれる倒れか１種または２種以上を、Ｎｂにあっては０
．０１〜０゜１％、■にあっては０．０１〜３．５％、
およびＢにあっては０．０００１〜０．５％含有させた
合金鋼粉を用いる。In addition, for the above-mentioned main components mainly consisting of Mn and Cr, as a subcomponent, the free energy change of the oxidation reaction is -120 to -150Kc all/m for the purpose described later.
One or more types of collapse selected from Nb, V, and H within the range of oil 02, and 0 for Nb.
．． 01~0゜1%, ■0.01~3.5%,
And for B, alloy steel powder containing 0.0001 to 0.5% is used.

さらには、他の副成分として後述するような目的で、Ｃ
ｕ０．１〜３．０％、Ｎｉ０．１〜５．０％、Ｃｏ Ｏ
，１〜１０．０％、Ｓｎ０．１〜３．０％、Ｍ。Furthermore, as other subcomponents, C
u0.1-3.0%, Ni0.1-5.0%, CoO
, 1-10.0%, Sn0.1-3.0%, M.

ｏ、ｉ〜７．０％、ＷＯ１１〜８．０％、Ｐ、０．０４
〜０．３０％、および８０．０４〜０．３０％のうちか
ら選ばれる倒れか１種または２種以上を含有させた合金
鋼粉を用いると焼結体の性状を向上させることができる
。o, i~7.0%, WO11~8.0%, P, 0.04
The properties of the sintered body can be improved by using an alloy steel powder containing one or more of the following: 0.30% to 80.04% to 0.30%.

（２）上記合金鋼粉に黒鉛粉を混合して圧粉体Ｃ量を０
．３０〜１．８０％とし、該圧粉体の焼結中における酸
化就中Ｍｎ、ＣｒあるいはＮｂ、Ｖ。(2) Mix graphite powder with the above alloy steel powder to reduce the amount of green compact C to 0.
．． 30 to 1.80%, and Mn, Cr, Nb, and V are oxidized during sintering of the green compact.

Ｂ等の酸化反応の自由エネルギー変化が−１２０〜−１
５０Ｋｃ ａ Ｉｊ／ｍｏｌ −０２の範囲内にある合
金元素の酸化を抑制する。The free energy change of the oxidation reaction of B etc. is -120 to -1
Suppresses oxidation of alloying elements within the range of 50 Kca Ij/mol -02.

なお、圧粉体のＣ量が１．８０％を超えると、焼結焼入
れ終了後の焼結鋼中における初析セメンタイト量が増大
して、特性の低下を来すほか焼結時の寸法変化量も大き
くなり、部品の寸法精度が損なわれるので好ましくない
。If the C content of the green compact exceeds 1.80%, the amount of pro-eutectoid cementite in the sintered steel after sintering and quenching will increase, resulting in a decrease in properties and dimensional changes during sintering. This is not preferable because the amount becomes large and the dimensional accuracy of the parts is impaired.

■ 上記の如く準備した圧粉体を、還元性ガス雰囲気で
焼結するに当り、該雰囲気ガスの露点を＋１２℃以下、
およびＣＯ２量を０．２９％以下として、前記圧粉体中
のＣと相俟って、焼結中における成形体の酸化を抑制す
る。■ When sintering the green compact prepared as above in a reducing gas atmosphere, the dew point of the atmospheric gas should be set to +12°C or less.
The amount of CO2 is set to 0.29% or less, which together with C in the compact suppresses oxidation of the compact during sintering.

（４）焼結を、Ｈ２２０％以上、ＣＯ３０％以下、炭化
水素ガス１０％以下、Ｎ２５５％以下の範囲で構成され
た還元性ガス雰囲気中で行ない、かつ１１００〜１２０
０℃の温度範囲内で２０分以上加熱して粉末粒子間の結
合を促進せしめると同時に、混合した黒鉛粉を基質中へ
拡散合金化せしめる。(4) Sintering is performed in a reducing gas atmosphere consisting of 20% or more of H2, 30% or less of CO, 10% or less of hydrocarbon gas, and 55% or less of N2, and
Heating is performed within a temperature range of 0° C. for 20 minutes or more to promote bonding between powder particles and at the same time to diffuse and alloy the mixed graphite powder into the matrix.

還元性ガス雰囲気を上記組成とする理由は、焼結の促進
と焼結体の酸化抑制にある。The reason why the reducing gas atmosphere has the above composition is to promote sintering and suppress oxidation of the sintered body.

とくにＣＯガス量が３０％を超えると、焼結が進行し難
くなり、強度低下を来すのでＣＯガス量は３０％以下で
なければならない。In particular, if the amount of CO gas exceeds 30%, sintering will be difficult to proceed and the strength will decrease, so the amount of CO gas must be 30% or less.

また、ＣＯガス量が３０％を超えて多く、かつガスの露
点が高い場合には、ＣＯ＋Ｈ２０→ＣＯ＋Ｈ２の水性ガ
ス反応を生じ易くなり、生成するＣｏによりＭｎ、Ｃｒ
が容易に酸化されるので不都合である。In addition, when the amount of CO gas is more than 30% and the dew point of the gas is high, the water gas reaction of CO+H20→CO+H2 is likely to occur, and the generated Co causes Mn, Cr.
This is disadvantageous because it is easily oxidized.

なお、この水性ガス反応は低温はど生じ易く、また低温
になるほど焼結も進行し難くなるので、本発明によれば
焼結温度を１１００℃とした。Note that this water gas reaction is more likely to occur at low temperatures, and the lower the temperature, the more difficult it is for sintering to proceed, so according to the present invention, the sintering temperature was set at 1100°C.

しかし逆に焼結温度を１２００℃を超えて高くすると、
経済性の観点から不利となるほか、焼結時の寸法変化も
犬きくなるので好ましくない。However, on the other hand, if the sintering temperature is increased beyond 1200℃,
Not only is this disadvantageous from an economic point of view, but it is also undesirable because dimensional changes during sintering become more severe.

前述の如き還元性ガス雰囲気のカーボンポテンシャルは
、部品の表面脱炭を防止する上から０．４〜１．２％の
範囲内が好適であり、露点、Ｃｏ量などに加えて、添加
する炭化水素系ガスの種類と量により微妙に調節するこ
とが肝要である。The carbon potential of the reducing gas atmosphere as described above is preferably within the range of 0.4 to 1.2% in order to prevent surface decarburization of parts. It is important to make delicate adjustments depending on the type and amount of hydrogen-based gas.

■ 上記（４）の焼結が終了してのち、該焼結体を室温
まで降温することなく、焼結時の加熱をそのまま利用し
て、該焼結体のＡｃ３変態点もしくはＡ 変態点より
５０℃以上高い温度乃至前ｍ 記焼結温度の範囲内の温度から直接油焼入れする。■ After the sintering in (4) above is completed, the sintered body is not cooled to room temperature and the heating during sintering is used as it is to lower the Ac3 transformation point or A transformation point of the sintered body. Direct oil quenching is performed at a temperature within the range of 50°C or more higher than the sintering temperature mentioned above.

つまり、焼結終了と同時に焼入れる焼結焼入法を本発明
法の根幹とする。In other words, the basis of the method of the present invention is a sintering and hardening method in which quenching is performed simultaneously with the completion of sintering.

（６）焼結終了後直ちに上記■の急冷処理を行なうこと
により、徐冷中の酸化が抑制されると同時に焼入硬化が
実現する。(6) Immediately after the completion of sintering, the rapid cooling treatment described in (1) above is performed to suppress oxidation during slow cooling and at the same time achieve quench hardening.

このように、焼結時の加熱を以って焼入用の加熱をも兼
ねさせることにより、工程の短縮化を計り得ると同時に
省エネルギーも実現して、ランニングコストの低減や設
備費の節減、生産性の向上などがもたらされ、その上部
品強度の向上も実現するなどその利得は極めて大となる
。In this way, by using the heating during sintering to also serve as the heating for quenching, it is possible to shorten the process and at the same time save energy, reducing running costs and equipment costs. The benefits are extremely large, as it not only improves productivity but also improves the strength of parts.

■ 以上本発明の方法について述べたが、なお必要に応
じて焼戻処理を施したり、原料粉末としての合金鋼粉に
、前記Ｏ〕の各合金元素のほかに、さらにＣｕ、Ｎｉ、
Ｃｏ、Ｓｎ、Ｍｏ、Ｗ、Ｐ。■ Although the method of the present invention has been described above, if necessary, tempering treatment may be applied to the alloy steel powder as the raw material powder, in addition to each alloying element O], Cu, Ni,
Co, Sn, Mo, W, P.

Ｓの各元素を１種以上合金させた銅粉を使用したりする
こともでき、これらは、製造部品に要求される特性を勘
案の上、適宜実施される。It is also possible to use copper powder made by alloying one or more of each element of S, and these are appropriately implemented in consideration of the characteristics required of the manufactured parts.

上述の付加的に合金されるＮ ｂ 、 Ｖ 、 Ｂ 、
Ｃｕ 。The above-mentioned additionally alloyed N b , V , B ,
Cu.

Ｎ ｉ 、Ｃｏ 、Ｓｎ 、Ｍｏ 、Ｗ、Ｐ 、Ｓは、
ＭｎおよびＣｒと共同して焼結部品のより一層の焼入性
向上を計り得るものであり、これら元素の必要最低限の
量が、Ｍｎ、Ｃｒを含めてそれぞれ特許請求の範囲に示
した如く、実験を通じて求められた。N i , Co , Sn , Mo , W, P , S are
Together with Mn and Cr, it is possible to further improve the hardenability of sintered parts, and the minimum necessary amount of these elements is as shown in the claims, including Mn and Cr. , determined through experiments.

また、各合金元素の上限量は、鋼粉の圧縮性や焼結中に
おける酸化抑制等を勘案して決定した。Further, the upper limit amount of each alloying element was determined by taking into consideration the compressibility of the steel powder, the suppression of oxidation during sintering, and the like.

なお、これら一連の合金元素は、同時に部品の耐食性や
高温強度の向上、あるいは切削性の向上などにも寄与す
るものであり、それぞれ特徴ある作用をなすことは通常
溶製鋼の場合と同様である。These series of alloying elements also contribute to improving the corrosion resistance, high-temperature strength, and machinability of parts, and each has its own characteristic action, just as in the case of ordinary molten steel. .

（８）以上α〕から■までの各事項に加えて、本発明法
によれば、原料鋼粉中のＣ量を、圧縮性、成形性の観点
から０．２０％以下とすることおよび、Ｓｉ、Ａｌ、Ｔ
ｉ、０の容量を、焼結部品の焼入性の観点からそれぞれ
０．１％以下、ｏ、ｏｉ％以下、０．０１％以下、０．
２５％以下に抑制する必要がある。(8) In addition to the above items α] to ■, according to the method of the present invention, the amount of C in the raw steel powder is set to 0.20% or less from the viewpoint of compressibility and formability; Si, Al, T
The capacities of i and 0 are respectively 0.1% or less, o, oi% or less, 0.01% or less, and 0.
It is necessary to suppress it to 25% or less.

これらの元素が、この規制量を超えて多くなると非金属
介在物量が増し、焼結部品の焼入性が急激に低下して、
機械的性質やその他の特性が損なわれてしまう。When the amount of these elements exceeds the regulated amount, the amount of nonmetallic inclusions increases, and the hardenability of sintered parts decreases rapidly.
Mechanical properties and other properties are impaired.

このほか本発明法によれば、圧縮成形時の圧粉密度を６
．０ｇ／−以上にする必要があるが、この理由は焼結を
十分促進せしめて、十分なる強度を得るためと、焼入時
の冷却速度を十分大きく保つためであり、余り密度が低
過ぎると十分な急冷が不能となり焼入硬化不足を招来す
る。In addition, according to the method of the present invention, the green density during compression molding can be increased to 6
．． The reason for this is to sufficiently promote sintering and obtain sufficient strength, and to maintain a sufficiently high cooling rate during quenching.If the density is too low, Sufficient rapid cooling becomes impossible, resulting in insufficient quench hardening.

次に本発明を実施例について具体的かつ詳細に説明する
。Next, the present invention will be described in detail with reference to examples.

実施例 １ １）原料鋼粉（０，９Ｍｎ−Ｉ Ｃｒ−２５Ｍｏ鋼粉）
ｉｉ）圧粉体Ｃ量 ０．５０％ １１１）圧粉密度 ６．５ｇ／諦 ｉＶ）焼結焼入時の加熱雰囲気（ ガス組成、露点） ２ ３１．１％ Ｏ ２，７％ ２ ４５．９％ Ｏ２ ０，２２〜０．２４％ 露点 ＋１〜＋３°Ｃ ■）焼結焼入条件 ａ）焼結条件 １１５０℃Ｘ５ＱｍｉＨ ｂ）焼入温度 焼結終了後１１５０℃より油焼入れ ｖｉ）焼戻条件 １７０℃Ｘ９０ｍ１ｎ−＋空冷ｖ１１
）成形体 ＪＳＰＭ標準引張試験片Ｖｉｉｌ）焼結焼入
材のＯ量と、引張強さおよび比強度ａ）焼結焼入材Ｏ量
０．０８３％ ｂ）引張強さ ８８．２ ｋｇ／ｍｒｎＣ）比強
度 １３．６ｋｌｌ１ｃｍ’／ｇ−ｍｉ原料粉末には
、低酸素（０，０７９％）の０．９Ｍｎ−／Ｃｒ Ｏ
，２５Ｍｏ銅粉を用いた。Example 1 1) Raw material steel powder (0,9Mn-I Cr-25Mo steel powder)
ii) Green powder C amount 0.50% 111) Green powder density 6.5 g/IV) Heating atmosphere during sintering and quenching (gas composition, dew point) 2 31.1% O 2.7% 2 45. 9% O2 0.22~0.24% Dew point +1~+3°C ■) Sintering and quenching conditions a) Sintering conditions 1150°C x 5QmiH b) Quenching temperature Oil quenching from 1150°C after sintering vi) Tempering Conditions 170℃X90m1n-+air cooling v11
) Molded object JSPM standard tensile test piece Viil) O content of sintered and quenched material, tensile strength and specific strength a) O content of sintered and quenched material 0.083% b) Tensile strength 88.2 kg/mrnC ) Specific strength 13.6kll1cm'/g-mi The raw material powder contains 0.9Mn-/CrO with low oxygen (0,079%).
, 25Mo copper powder was used.

コノ銅粉に黒鉛粉を混合して、圧粉体Ｃ量を０．５０％
とし、圧粉密度６．５ｊｉ／ｃｍ３でＪＳＰＭ標準引張
試験片に成形後、前記の如き吸熱型の変成ガス雰囲気中
で１１５０℃Ｘ５０分の焼結を行ない、そのまま焼結温
度から油焼入れした。Mixing graphite powder with Kono copper powder, the amount of compacted powder C is 0.50%
After molding into a JSPM standard tensile test piece with a powder density of 6.5ji/cm3, sintering was performed at 1150°C for 50 minutes in an endothermic modified gas atmosphere as described above, and oil quenching was performed at the sintering temperature.

その後、１７０℃×９０分焼戻し処理して引張試験に供
した。Thereafter, it was tempered at 170°C for 90 minutes and subjected to a tensile test.

この熱処理焼結鋼の酸素量は０．０８３％であり、引張
強さは８８．２ｋｇ／ｉｉ、また、引張強さを密度で除
した値（比強度）は、１３．６ｋｇ・−／９−ｍ？ｎで
あった。The oxygen content of this heat-treated sintered steel is 0.083%, the tensile strength is 88.2 kg/ii, and the value obtained by dividing the tensile strength by the density (specific strength) is 13.6 kg・-/9 -m? It was n.

実施例 ２ １）原料鋼粉（０，５Ｍｎ −１，５Ｃｒ鋼粉）ｉｉ）
圧粉体Ｃ量 ０．６５％ １１１）圧粉密度 ６．８ ｇ／ａｎ３ｉＶ）焼結
焼入時の加熱雰囲気（ガス組成、露点） ２ １．８％ Ｏ ２３，２％ ２ ４４．６％ Ｏ ０，２２〜０．２４％ 露点 ＋４〜＋６°Ｃ ■）焼結焼入条件 ａ）焼結条件 １１５０℃Ｘ５０ｍ１ｎｂ）焼入温度
焼結終了後１１５０℃から９５０℃まで降温しで油
焼入 れ Ｖｉ）焼戻条件 １７０℃Ｘ９０ｍ１ｎ−→空冷ｖ１１
）成形体 ＪＳＰＭ標準引張試験片ｖｉｉ＋）焼結焼入
材のＯ量と、引張強さおよび比強度ａ）焼結焼入材Ｏ量
０．０７７％ ｂ）引張強さ ９３．４ ｋｇ／ｍｒｎ２Ｃ）比
強度 １３．７ ｋｇ・ｃｒｒｐ９−ｍｉ原料粉末に
は、酸素量０．０６３％の０．５Ｍｎ −１．５Ｃｒ鋼
粉を用いた。Example 2 1) Raw material steel powder (0,5Mn-1,5Cr steel powder) ii)
Green powder C amount 0.65% 111) Green powder density 6.8 g/an3iV) Heating atmosphere during sintering and quenching (gas composition, dew point) 2 1.8% O 23.2% 2 44.6% O 0.22~0.24% Dew point +4~+6°C ■) Sintering and quenching conditions a) Sintering conditions 1150°C ) Tempering conditions 170℃X90m1n-→air cooling v11
) Molded object JSPM standard tensile test piece vii +) O content of sintered and quenched material, tensile strength and specific strength a) O content of sintered and quenched material 0.077% b) Tensile strength 93.4 kg/mrn2C ) Specific strength: 13.7 kg/crrp9-mi 0.5Mn-1.5Cr steel powder with an oxygen content of 0.063% was used as the raw material powder.

この銅粉に黒鉛粉を混合して、圧粉体Ｃ量を０．６５％
とし、圧粉密度６．８ｇ／ｃＩＴ１３でＪＳＰＭ標準引
張試験片に成形後、吸熱型の変成ガス雰囲気中で１１５
０℃×５０分焼結し、次いで９５０℃まで降温しで油焼
入れした。Graphite powder is mixed with this copper powder to reduce the amount of green compact C to 0.65%.
After molding into a JSPM standard tensile test piece with a green powder density of 6.8 g/cIT13, it was heated to 115 in an endothermic modified gas atmosphere.
Sintering was carried out at 0°C for 50 minutes, and then the temperature was lowered to 950°C and oil quenching was performed.

その後１７０℃×９０分焼戻し処理して引張試験に供し
た。Thereafter, it was tempered at 170°C for 90 minutes and subjected to a tensile test.

この焼結焼入鋼の酸素量は０．０７７％であり、引張強
さは９３．４ ｋｇ／ｍｍ２、比強度は１３、７ ｋｇ
＠ ｉ／ 、９ ＊ ｍｙｙｔ２であった。The oxygen content of this sintered and hardened steel is 0.077%, the tensile strength is 93.4 kg/mm2, and the specific strength is 13.7 kg.
@i/, 9*myyt2.

実施例 ３ １）原料鋼粉（０，２Ｍｎ −３，５Ｃｒ −０，５Ｎ
ｉ −０，２Ｍｏ −０，２Ｖ鋼粉） １１）圧粉体Ｃ量 ０．８０％ ）圧粉密度 ６．８ ｇ／ｃｍ” ｉＶ）焼結焼入時の加熱雰囲気（ガス組成、露点）２ ７４．７％ ２ ２４．７％ Ｈ４ ０，６％ Ｏ ０，０％ 露点 ０〜＋３°Ｃ ■）焼結焼入条件 ａ）焼結条件 １１８０°ＣＸ５０ｍ１ｎｂ）焼入温度
焼結終了後１１８０℃から９００℃まで降温して油焼
入れ ｖｉ）焼戻条件 １７０°ＣＸ９Ｑｍｉｎ−＋空冷ｖ１
１）成形体 ＪＳＰＭ標準引張試験片Ｖｉｉｉ）焼結焼
入材のＯ量と、引張強さおよび比強度ａ）焼結焼入材Ｏ
量 ０．０９５％ ｂ）引張強さ １０８．４ｋｇ／前２Ｃ前２節度
１５−９ ｋｇ・ｃｍ” ／ｇ−ｍｒｎ２原料粉末
には、酸素量０．１８６％の０．２ Ｍ ｎ３．５Ｃｒ
−０，５Ｎｉ−０，２Ｍｏ−０，２Ｖ鋼粉を用いた。Example 3 1) Raw material steel powder (0,2Mn -3,5Cr -0,5N
i -0,2Mo -0,2V steel powder) 11) Green powder C amount 0.80%) Green powder density 6.8 g/cm" iV) Heating atmosphere during sintering and hardening (gas composition, dew point) 2 74.7% 2 24.7% H4 0.6% O 0.0% Dew point 0 to +3°C ■) Sintering and quenching conditions a) Sintering conditions 1180°C Oil quenching by lowering the temperature from ℃ to 900℃vi) Tempering conditions 170℃X9Qmin-+air cooling v1
1) Molded object JSPM standard tensile test piece VIII) O content of sintered and sintered material, tensile strength and specific strength a) Sintered and sintered material O
Amount 0.095% b) Tensile strength 108.4 kg/2C front 2 moderation 15-9 kg・cm"/g-mrn2 The raw material powder contains 0.2M n3.5Cr with an oxygen content of 0.186%
-0,5Ni-0,2Mo-0,2V steel powder was used.

成形は、圧粉体Ｃ量Ｏ，ＳＯ％、圧粉密度６．８９／ｃ
ｍ３で行なった。For molding, green compact C amount O, SO%, green compact density 6.89/c
I did it on m3.

このようにして成形した圧粉体（ＪＳＰＭ標準引張試験
片）を、分解アンモニアガスに、エンリッチガスとして
０．６％のメタンガスを添加した還元ガス雰囲気中で１
１８０℃×５０分加熱焼結し、次いで９００℃まで降温
後油焼入れして、１７０℃×９０分の焼戻し処理を施し
た。The green compact (JSPM standard tensile test piece) formed in this way was placed in a reducing gas atmosphere containing decomposed ammonia gas and 0.6% methane gas as an enrichment gas.
It was heated and sintered at 180°C for 50 minutes, then cooled to 900°C, oil quenched, and tempered at 170°C for 90 minutes.

この焼結焼入鋼の酸素量は０．０９５％であり、引張強
さは１０８．４に９７ｍ１ｎ” 、また比強度は１５．
９ ｋｇ・ｃｍ３／！９・ｍ２で、かなり高い値が得ら
れた。The oxygen content of this sintered and hardened steel is 0.095%, the tensile strength is 108.4.97 m1n'', and the specific strength is 15.4.
9 kg・cm3/! A fairly high value was obtained at 9·m2.

なお、エンリッチガスの添加により焼結鋼表面の脱炭は
十分に防止された。Note that decarburization of the sintered steel surface was sufficiently prevented by the addition of enriched gas.

実施例 ４ ［）原料粉末 実施例１で用いた０、９Ｍｎ−ｌＣｒ ０．２５Ｍｏ銅粉８５％にアトマ イズ純鉄粉１５％を混合したもの を原料粉末として使用 ４ アトマイズ純鉄粉の化学組成（ハ） 表 １１）原料粉末を除くその他条件：すべで実施例１に同
じ。Example 4 [) Raw material powder A mixture of 85% of the 0,9Mn-lCr 0.25Mo copper powder used in Example 1 and 15% of atomized pure iron powder was used as the raw material powder.4 Chemical composition of atomized pure iron powder ( c) Table 11) Other conditions except raw material powder: All the same as in Example 1.

１１１）焼結焼入材のＯ量と、引張強さおよび比強度ａ
）焼結焼入材Ｏ量 ０．０８６％ ｂ）引張強さ ８２．７ ｋｇ／ｒｎｒｔ？Ｃ）
比強度 １２−７ ｋｇ＋ ｃｍ３／９− ｍｒｎ
２実施例４は、実施例１で使用した０、９Ｍｎ−ＩＣｒ
−０，２５Ｍｏ銅粉８５％（重量百分率）とアトマイ
ズ純鉄粉１５％（同前）とを混合した粉末を原料として
本発明法を適用した例であり、その他の条件は総て実施
例１と同じである。111) O content of sintered and hardened material, tensile strength and specific strength a
) Sintered hardened material O amount 0.086% b) Tensile strength 82.7 kg/rnrt? C)
Specific strength 12-7 kg+ cm3/9- mrn
2 Example 4 is based on the 0,9Mn-ICr used in Example 1.
- This is an example in which the method of the present invention is applied using a powder mixture of 85% (weight percentage) of 0,25Mo copper powder and 15% of atomized pure iron powder (same as above), and all other conditions are as in Example 1. is the same as

焼結焼入後の焼結鋼の酸素量は０．０８．６％、引張強
さは８２、７ ｋｇ／７１”ｓ比強度は１２．７ ｋｌ
１７− ｃｍ／ ９−ｍｍ２であった。The oxygen content of the sintered steel after sintering and quenching is 0.08.6%, the tensile strength is 82, and the specific strength of 7 kg/71”s is 12.7 kl.
It was 17-cm/9-mm2.

比較例 １ １）焼結焼入時の加熱雰囲気を除くその他条件：すべで
実施例１に同じ。Comparative Example 1 1) Other conditions except the heating atmosphere during sintering and quenching: All the same as in Example 1.

１１）焼結焼入時の加熱雰囲気 ２ ３０．７％ Ｏ ２２，１％ ２ ４６．８％ ＣＯ２ ０，３６〜０．３８％ 露点 ＋１８〜＋２０００ １１１）焼結焼入材のＯ量と引張強さおよび比強度ａ）
焼結焼入材Ｏ量 ０．２７７％ ｂ）引張強さ ６２．９に９／闘２Ｃ）比強度
９−７ ｋｌ？ ・ｃｍ３／ｇ・ｎｉｌ原料鋼粉に
は、実施例１で用いたものと同じ鋼粉を用い、焼結焼入
時の加熱雰囲気を除いて、その他の条件はすべて実施例
１と同じである。11) Heating atmosphere during sintering and hardening 2 30.7% O 22.1% 2 46.8% CO2 0.36 to 0.38% Dew point +18 to +2000 111) O amount and tension of sintering and hardening material Strength and specific strength a)
Sintered hardened material O amount 0.277% b) Tensile strength 62.9 to 9/T2C) Specific strength
9-7 kl?・cm3/g・nil The same steel powder as that used in Example 1 was used as the raw material steel powder, and all other conditions were the same as in Example 1 except for the heating atmosphere during sintering and quenching. .

加熱雰囲気には、実施例１と同じ吸熱型の変成ガスを用
いたが、ＣＯ量、露点が本発明の範囲を超えて高かった
ため、焼結中に成形体の酸化が進み、焼結焼入後の酸素
量は０．２７７％にもなった。The same endothermic modified gas as in Example 1 was used for the heating atmosphere, but since the CO amount and dew point were higher than the range of the present invention, oxidation of the compact progressed during sintering, resulting in sintering and quenching. The amount of oxygen after that was as high as 0.277%.

そのため、引張強さは６２．９ ｋｇ／ｍｍ２ と低く
、比強度も９．７ｋｇ・ｃＩＴ１３／ｇ−一で、実施例
１に較べてかなり低い値を示した。Therefore, the tensile strength was as low as 62.9 kg/mm2, and the specific strength was also 9.7 kg·cIT13/g-1, which were considerably lower values than in Example 1.

比較例 ２ ｉ）焼結後の冷却方法と熱処理条件を除くその他条件二
すべで実施例１に同じ。Comparative Example 2 i) All other conditions were the same as in Example 1 except for the cooling method and heat treatment conditions after sintering.

１［）焼結後の冷却方法 炉冷（徐冷）Ｉｌｌ）焼結
徐冷後の熱処理条件 ａ）焼入時加熱雰囲気 実施例１の焼結焼入時加熱雰囲
気と同じ。1 [) Cooling method after sintering Furnace cooling (slow cooling) Ill) Heat treatment conditions after sintering slow cooling a) Heating atmosphere during quenching Same as the heating atmosphere during sintering and quenching in Example 1.

ｂ）焼入条件 ９００℃Ｘ４０ｍ１ｎ、→油冷Ｃ）焼戻
条件 １７０°ＣＸ ９０ ｍｉｎ 、−）空冷１ｖ）
熱処理焼結鋼のＯ量と、引張強さおよび比強度 ａ）熱処理焼結鋼Ｏ量 ０．２８６％ ｂ）引張強さ ６０．４ ｋｇ／ｍｍ２Ｃ）比
強度 ９．３ｋｇ・ｃｎ￥’ｇ−ｍｍ”本例は、
焼結後の徐冷とその後の熱処理条件を除いて、使用鋼粉
およびその他の成形、焼結等の諸条件が、実施例１と総
て同じで、しかも焼結徐冷後に、実施例１と同等の焼入
れ一焼戻し処理を施した例である。b) Quenching conditions 900°C x 40ml, → oil cooling C) Tempering conditions 170°C x 90 min, -) Air cooling 1v)
O amount, tensile strength, and specific strength of heat-treated sintered steel a) O amount of heat-treated sintered steel 0.286% b) Tensile strength 60.4 kg/mm2C) Specific strength 9.3 kg・cn\'g- mm” In this example,
Except for the slow cooling after sintering and the subsequent heat treatment conditions, the steel powder used and other conditions for forming, sintering, etc. were all the same as in Example 1. This is an example in which the same quenching and tempering treatment was applied.

しかし、焼結後に徐冷しているため、熱処理焼結鋼の酸
素量は０．２８６％にもなり、実施例１より２０００ｐ
ｐｍも多い値を示した。However, since it is slowly cooled after sintering, the amount of oxygen in the heat-treated sintered steel is as high as 0.286%, which is 2000p compared to Example 1.
pm also showed a high value.

このように、焼結後の徐冷によりＭｎ、Ｃｒ等の合金元
素の酸化が進むため、その後の焼入れ一焼戻しによって
も十分な強度が得られず、エネルギーや工数上の損失と
併わせで極めて不利となる。In this way, as the slow cooling after sintering progresses the oxidation of alloying elements such as Mn and Cr, sufficient strength cannot be obtained even with subsequent quenching and tempering, resulting in extremely high energy and man-hour losses. It will be disadvantageous.

本例熱処理焼結鋼の引張強さ、比強度は、それぞれ６０
．４ ｋｇ／ｍｒｎ”、および９．３ｋｇ・ｃＩ１１３
／ｇ・ｍｍ２ で、実施例１に較べてかなり低かった。The tensile strength and specific strength of the heat-treated sintered steel of this example are 60, respectively.
．． 4 kg/mrn”, and 9.3 kg・cI113
/g·mm2, which was considerably lower than that in Example 1.

比較例 ３ １）原料鋼粉（高酸素０．９ Ｍ ｎ Ｍｏ鋼粉） １Ｃｒ−０，２５ ｉｌ）原料鋼粉を除くその他条件 ：総で実施例１に同じ。Comparative example 3 1) Raw material steel powder (high oxygen 0.9 Mn Mo steel powder) 1Cr-0.25 il) Other conditions excluding raw material steel powder : Totally the same as in Example 1.

用）焼結焼入材のＯ量と、引張強さおよび比強度ａ）焼
結焼入材Ｏ量 ０．４３５％ ｂ）引張強さ ５４．７ ｋｇ／ｍｒｎ２Ｃ）比
強度’ ８．４ ｋｇ・ｃｍ” ／ｇ−ｍｉ実施例
７は、原料に高酸素（０，５２４％Ｏ）の０．９Ｍｎ−
ｌＣｒ−０，２５Ｍｏ銅粉を用いた例である。a) O content of sintered and hardened material 0.435% b) Tensile strength 54.7 kg/mrn2C) Specific strength' 8.4 kg・cm”/g-mi Example 7 uses 0.9Mn− with high oxygen (0,524% O) as the raw material
This is an example using lCr-0,25Mo copper powder.

この実施例によれば原料鋼粉を除いて、その他の成形、
焼結、焼入等の諸条件は、総て実施例１と同じにした。According to this example, except for the raw material steel powder, other molding,
All conditions such as sintering and quenching were the same as in Example 1.

その結果焼結焼入鋼の引張強さは、５４．７ ｋｇ／ｍ
ｍ２、比強度は８．４ｋｇ・ｃｒｊ、／／ｇ誦であり、
実施例１の低酸素鋼粉の場合に較べてかなり低い値を示
した。As a result, the tensile strength of the sintered and hardened steel was 54.7 kg/m
m2, specific strength is 8.4 kg・crj, //g,
This value was considerably lower than that of the low-oxygen steel powder of Example 1.

以上実施例１〜４および比較例１〜３を通じて明らかな
ように、本発明法によれば、本質的に焼入性に優れる原
料鋼粉と好適範囲の圧粉体Ｃ量と焼結焼入用加熱雰囲気
中の不純物ガス量の抑制と、焼結後の直接焼入れ、すな
わち急冷処理の４者を組合わせて、初めて比強度に優れ
る焼結機械部品の製造が可能となるものであり、とくに
焼結後の急冷処理により、 （１３Ｍｎ 、 Ｃｒなとの易酸化性合金元素の酸化抑
制 （２）焼入組織を得ることによる部品強度の向上（３）
熱処理回数の削減、すなわち焼入用加熱の省略によるコ
スト低減すなわち省エネルギー、省資源（還元性ガスの
消費量節減）、省力（省工数）、設備投資額の圧縮等。As is clear from Examples 1 to 4 and Comparative Examples 1 to 3 above, according to the method of the present invention, raw material steel powder having essentially excellent hardenability, green compact C amount in a suitable range, and sintering and quenching It is possible to manufacture sintered machine parts with excellent specific strength for the first time by combining the following four factors: suppression of the amount of impurity gas in the heating atmosphere, direct quenching after sintering, or rapid cooling treatment. Rapid cooling treatment after sintering suppresses oxidation of easily oxidizable alloying elements such as 13Mn and Cr (2) Improves component strength by obtaining a quenched structure (3)
Cost reduction by reducing the number of heat treatments, that is, omitting heating for quenching, which means saving energy, saving resources (reducing consumption of reducing gas), saving labor (saving man-hours), reducing capital investment, etc.

（４）迅速冷却に基く生産性の向上 など多くの効果が期待される。(4) Improving productivity based on rapid cooling Many other effects are expected.

このような本発明法の適用により、低密度でも高強度を
もった部品の製造が可能となり、部品の軽量化を実現し
得るものである。By applying the method of the present invention as described above, it is possible to manufacture parts having high strength even with low density, and it is possible to realize a reduction in the weight of the parts.

例えば自動車部品の製造に本発明法を適用して、自動車
の車体重量軽減を通じた低燃費化を計るなどの応用が考
えられ、今後の活用が大いに期待されるところである。For example, it is possible to apply the method of the present invention to the manufacture of automobile parts to reduce the weight of automobiles and thereby improve fuel efficiency, and it is highly anticipated that the method will be used in the future.

Claims (1)

【特許請求の範囲】 １ 酸化反応の自由エネルギー変化が−１２０〜−１５
０Ｋｃａｌ／ｍｏ１０２の範囲にある元素のうちＭｎお
よびＣｒを、Ｍｎにあっては０．１〜２．３％、Ｃｒに
あっては０．１〜５．５％含有し 、他にＣ０，２０％
以下、Ｃ０，２５％以下、Ｓｉ０．１０％以下、Ａ１０
．０１％以下、およびＴｉＯ，０１％以下を含み、残部
が不可避不純物とＦｅよりなる合金鋼粉を原料粉末とし
、この原料粉末に対し、潤滑剤と圧粉体Ｃ量が０．３０
〜１．８０％になる量の黒鉛粉とを混合し、金型中で圧
縮成形して圧粉密度が６．０ｇ〆邪以上を示すような圧
粉体とし、ついでその圧粉体をＣＯ２０，２９％以下、
Ｎ２２０％以上、ＣＯ３０％以下、炭化水素系ガス１０
％以下、およびＮ２５５％以下の組成よりなる露点子１
２℃以下の還元性ガス雰囲気中で予熱、脱ろうし、その
後１１００〜１２００℃の温度範囲で２０分以上加熱し
て焼結させ、かくして得られる焼結体を前記焼結温度〜
鉄焼結体のＡＣ３変態点もしくはＡ 変態点より５０℃
高い温度の範囲内より油焼入れすることを特徴とする比
強度に優れる焼結機械部品の製造方法。 ２ 酸化反応の自由エネルギー変化が一１２０〜１５０
ＫｃａＡ／ｍｏＡＯ２の範囲にある元素のうちＭｎおよ
びＣｒを、Ｍｎにあっては０．１〜２．３％、Ｃｒにあ
っては０．１〜５．５％含有し、他にＭｏを０．１〜７
．０％含有するとともに、それらの合計量が０．４０〜
７．０％になるように含有しており、そしてＣ０，２０
％以下、００．２５％以下、Ｓｉ０．１０％以下、Ａ１
０．０１％以下、およびＴｉＯ，０１％以下を含み、残
部が不可避不純物とＦｅよりなる合金鋼粉の原料粉末と
し、この原料粉末に対し、潤滑剤と圧粉体Ｃ量が０．３
０〜１．８０％になる量の黒鉛粉とを混合し、金型中で
圧縮成形して圧粉密度が６．０．９／ｉ以上を示すよう
な圧粉体とし、ついでその圧粉体をＣ０２０，２９％以
下、Ｎ２２０％以上、ＣＯ３０％以下、炭化水素系ガス
１０％以下、およびＮ２５５％以下の組成よりなる露点
＋１２℃以下の還元性ガス雰囲気中で予熱、脱ろうし、
その後１１００〜１２００℃の温度範囲で２０分以上加
熱して焼結させ、かくして得られる焼結体を前記焼結温
度〜鉄焼結体のＡＣ３変態点もしくはＡ 変態点より
５０℃高い温度の範囲内より油焼入れすることを特徴と
する比強度に優れる焼結機械部品の製造方法。 ３ 酸化反応の自由エネルギー変化が−１２０〜１５０
Ｋｃａｌ／ｍｏｂ０２の範囲にある元素のうちＭｎおよ
びＣｒを、Ｍｎにあっては０．１〜２．３％、Ｃｒにあ
っては０．１〜５．５％含有し、Ｃ０，２０％以下、０
０．２５％以下、Ｓ ｉ ０．１０％以１Ｍ０００１％
以下、およびＴｉＯ，０１％以下を主成分として含み、
さらに副成分として、酸化反応の自由エネルギー変化が
−１２０〜−１５０Ｋｃａｌ／１１１ｏｌＯ２の範囲内
にあるＮｂ、Ｖ、Ｂのうちから選ばれる倒れか１種また
は２種以上をＮｂにあっては０．０１〜１．０％、■に
あっては０．０１〜３．５％、Ｂにあってはｏ、ｏｏｏ
ｉ〜０．５％含有させる他、Ｃｕ０．１〜３．０％、Ｎ
ｉＯ，１〜５．０％、Ｃｏ ０．１〜１０．０％、Ｓｎ
０．１〜３．０％、ＭＯｏ、１〜７．０％、Ｗｏ、１〜
８．０％、Ｐｏ、０４〜０．３０％、８０．０４〜０．
３０％のうちから１種または２種以上を選んで含有させ
、残部が不可避不純物とＦｅよりなる合金鋼粉の原料粉
末とし、この原料粉末に対し、潤滑剤と圧粉体Ｃ量が０
．３０〜１．８０％になる量の黒鉛粉とを混合し、金型
中で圧縮成形して圧粉密度が６．ｏｇ／ｄ以上を示すよ
うな圧粉体とし、ついでその圧粉体をＣＯ２０，２９％
以下、Ｈ２２０％以上、Ｃｏ３０％以下、炭化水素系ガ
ス１０％以下、およびＮ２５５％以下の組成よりなる露
点＋１２℃以下の還元性ガス雰囲気中で予熱、脱ろうし
、その後１１００〜１２００℃の温度範囲で２０分以上
加熱して焼結させ、かくして得られる焼結体を前記焼結
温度〜鉄焼結体のＡ。 ３変態点もしくはＡ 変態点より５０℃高い温度ｍ の範囲内より油焼入れすることを特徴とする比強度に優
れる焼結機械部品の製造方法。 ４ 酸化反応の自由エネルギー変化が−１２０〜−１５
０Ｋｃａｌ／ｍｏｂ０２の範囲にある元素のうちＭｎお
よびＣｒをＭｎにあっては０．１〜２．３％、Ｃｒにあ
っては０．１〜５．５％含有し、Ｃ０，２０％以下、０
０．２５％以下、ＳｉＯ，１０％以下１．１０．０１％
以下、およびＴｉＯ，０１％以下を含み、残部が不可避
不純物とＦｅよりなる合金鋼粉の原料粉末とし、この原
料粉末に対し、潤滑剤と圧粉体Ｃ量が０．３０〜１．８
０％になる量の黒鉛粉とを混合し、金型中で圧縮成形し
て圧粉密度が６．０ｇ／ｃ＆１以上を示すような圧粉体
とし、ついでその圧粉体をＣＯＯ，２９％以下、Ｈ２２
０％以上、Ｃｏ３０％以下、炭化水素系ガス１０％以下
、およびＮ２５５％以下の組成よりなる露点＋１２℃以
下の還元性ガス雰囲気中で予熱、脱ろうし、その後１１
００〜１２００℃の温度範囲で２０分以上加熱して焼結
させ、かくして得られる焼結体を前記焼結温度〜鉄焼結
体のＡ。 ３変態点もしくはＡ 変態点より５０℃高い温度の範
囲内より油入れし、次いで脱脂した後室温から該焼結体
のＡ 変態点までの温度範囲内で油中または前記１ 還元性ガス雰囲気中の倒れかの中で加熱焼戻しすること
を特徴とする比強度に優れる焼結機械部品の製造方法。 ５ 酸化反応の自由エネルギー変化が一１２０〜１５０
Ｋｃａｌ／ｒｒ］ｏｌＯ２の範囲にある元素のうちＭｎ
およびＣｒを、Ｍｎにあっては０．１〜２．３％、Ｃｒ
にあっては０．１〜５．５％含有し、他にＣ０９２０％
以下、００．２５％以下、Ｓｉ０．１０％以下、Ａ７０
．０１％以下、およびＴｉ０．０１％以下を含み残部が
不可避不純物とＦｅよりなる合金鋼粉を原料粉末とし、
この原料粉末に対し、潤滑剤と圧粉体Ｃ量が０．３０〜
１．８０％になる量の黒鉛粉とを混合し、金型中で圧縮
成形して圧粉密度が６．０ｇ／ａｍ以上を示すような圧
粉体とし、ついでその圧粉体をＣＱｏ、２９％以下、Ｈ
２２０％以上、Ｃｏ３０％以下、炭化水素系ガス１０％
以下、およびＮ２５５％以下の組成よりなる露点＋１２
℃以下の還元性ガス雰囲気中で予熱、脱ろうし、その後
１１００〜１２００°Ｃの温度範囲で２０分以上加熱し
て焼結させ、かくして得られる焼結体を前記焼結温度〜
鉄焼結体のＡ 変態点もしくは３ Ａ 変態点より５０℃高い温度の範囲内より油焼入れ
し、次いで脱脂した後室温から該焼結体のＡｏ０変態点
までの温度範囲内で油中または前記還元性ガス雰囲気中
の倒れかの中で加熱焼戻し、さらに得られた焼結体を油
中で急冷することを特徴とする比強度に優れる焼結機械
部品の製造方法。 ６ 上記原料粉末として、前記合金鋼粉を７０％以上を
含み、残部には非鉄金属粉末、合金粉末、前記合金鋼以
外の合金鋼粉、非金属粉末のなかから選ばれる何れか少
なくとも１種よりなる混合粉末を原料として用いる特許
請求の範囲第１〜５項の倒れかに記載の方法。[Claims] 1. Free energy change of oxidation reaction is -120 to -15
Of the elements in the range of 0Kcal/mo102, it contains Mn and Cr, 0.1 to 2.3% for Mn and 0.1 to 5.5% for Cr, and also contains C0,20 %
Below, C0.25% or less, Si0.10% or less, A10
．． The raw material powder is an alloyed steel powder containing 0.01% or less and TiO, 0.01% or less, with the remainder consisting of unavoidable impurities and Fe, and the amount of lubricant and green compact C is 0.30% for this raw material powder.
~1.80% of graphite powder is mixed, compression molded in a mold to form a compact with a compact density of 6.0 g or more, and then the compact is CO20 , 29% or less,
N220% or more, CO30% or less, hydrocarbon gas 10
Dew pointer 1 having a composition of % or less and N255% or less
Preheating and dewaxing in a reducing gas atmosphere of 2° C. or lower, then heating and sintering in a temperature range of 1100 to 1200° C. for 20 minutes or more, and the sintered body thus obtained is heated to a temperature ranging from the sintering temperature to
50℃ below AC3 transformation point or A transformation point of iron sintered body
A method for manufacturing sintered mechanical parts with excellent specific strength, characterized by oil quenching within a high temperature range. 2 The free energy change of oxidation reaction is 1120 to 150
Of the elements in the range of KcaA/moAO2, Mn and Cr are contained in an amount of 0.1 to 2.3%, Cr in an amount of 0.1 to 5.5%, and Mo is 0. .1-7
．． Contains 0% and their total amount is 0.40~
Contains 7.0%, and C0.20
% or less, 0.25% or less, Si0.10% or less, A1
0.01% or less and TiO, 0.01% or less, and the balance is unavoidable impurities and Fe, and the amount of lubricant and compact C is 0.3% for this raw material powder.
0 to 1.80% of graphite powder is mixed, compression molded in a mold to form a compact with a compact density of 6.0.9/i or more, and then the green compact is Preheating and dewaxing the body in a reducing gas atmosphere with a dew point of +12°C or less consisting of a composition of CO20, 29% or less, N20% or more, CO30% or less, hydrocarbon gas 10% or less, and N255% or less,
Thereafter, the sintered body is sintered by heating in a temperature range of 1100 to 1200°C for 20 minutes or more, and the sintered body thus obtained is heated in a temperature range of 50°C higher than the sintering temperature to the AC3 transformation point or A transformation point of the iron sintered body. A method for manufacturing sintered machine parts with excellent specific strength, characterized by oil quenching from the inside. 3 Free energy change of oxidation reaction is -120 to 150
Of the elements in the range of Kcal/mob02, Mn and Cr are contained in an amount of 0.1 to 2.3%, Cr in an amount of 0.1 to 5.5%, and C0.20% or less. ,0
0.25% or less, Si 0.10% or more 1M0001%
Contains the following and TiO, 01% or less as a main component,
Furthermore, as a subcomponent, one or more types selected from Nb, V, and B whose free energy change in oxidation reaction is within the range of -120 to -150 Kcal/111 olO2 is added to Nb. 01-1.0%, 0.01-3.5% for ■, o, ooo for B
In addition to containing i~0.5%, Cu0.1~3.0%, N
iO, 1-5.0%, Co 0.1-10.0%, Sn
0.1-3.0%, MOo, 1-7.0%, Wo, 1-
8.0%, Po, 04-0.30%, 80.04-0.
One or more types are selected and contained from 30% of the raw material powder, and the remainder is unavoidable impurities and Fe.
．． 30 to 1.80% of graphite powder is mixed and compression molded in a mold to a powder density of 6. The green compact is made into a powder that shows og/d or more, and then the green compact is heated to CO20.29%.
Preheating and dewaxing in a reducing gas atmosphere with a dew point of +12°C or less consisting of H20% or more, Co30% or less, hydrocarbon gas less than 10%, and N255% or less, followed by a temperature range of 1100 to 1200°C. The sintered body thus obtained is sintered by heating for 20 minutes or more at a temperature ranging from the above sintering temperature to A of the iron sintered body. A method for producing sintered mechanical parts with excellent specific strength, characterized by oil quenching at a temperature m that is 50° C. higher than the 3 transformation point or the A transformation point. 4 Free energy change of oxidation reaction is -120 to -15
Of the elements in the range of 0Kcal/mob02, Mn and Cr are contained in an amount of 0.1 to 2.3%, Cr in an amount of 0.1 to 5.5%, and C0.20% or less. 0
0.25% or less, SiO, 10% or less 1.10.01%
A raw material powder for alloy steel powder containing the following and TiO, 0.1% or less, and the remainder consisting of unavoidable impurities and Fe, and for this raw material powder, the amount of lubricant and green compact C is 0.30 to 1.8
0% graphite powder, compression molded in a mold to make a green compact with a green density of 6.0g/c&1 or more, and then the green compact is COO, 29% Below, H22
Preheating and dewaxing in a reducing gas atmosphere with a dew point of +12°C or less consisting of 0% or more, Co30% or less, hydrocarbon gas less than 10%, and N255% or less, then 11
The sintered body thus obtained is sintered by heating in the temperature range of 00 to 1200°C for 20 minutes or more, and the sintered body is heated at a temperature ranging from the above sintering temperature to A of the iron sintered body. 3 Transformation point or A The sintered body is poured into oil at a temperature 50° C. higher than the transformation point, and then degreased and then placed in oil or in a reducing gas atmosphere within a temperature range from room temperature to the A transformation point of the sintered body. A method for producing sintered machine parts with excellent specific strength, characterized by heating and tempering them in a collapsed furnace. 5 Free energy change of oxidation reaction is 1120 to 150
Among the elements in the range of Kcal/rr]olO2, Mn
and Cr, 0.1 to 2.3% for Mn, Cr
Contains 0.1 to 5.5%, and other C0920%
Below, 0.25% or less, Si 0.10% or less, A70
．． The raw material powder is an alloy steel powder containing 0.01% or less of Ti and 0.01% or less of Ti with the remainder consisting of unavoidable impurities and Fe,
The amount of lubricant and compact C for this raw powder is 0.30~
1.80% of graphite powder and compression molded in a mold to form a green compact with a green density of 6.0 g/am or more, and then the green compact is CQo, 29% or less, H
220% or more, Co30% or less, hydrocarbon gas 10%
Dew point +12 consisting of the following and N255% or less composition
Preheating and dewaxing in a reducing gas atmosphere of 1,100 to 1,200 degrees Celsius or lower, followed by sintering by heating at a temperature range of 1,100 to 1,200 degrees Celsius for 20 minutes or more, and the sintered body thus obtained is
A transformation point of the iron sintered body or 3 A method for manufacturing sintered mechanical parts having excellent specific strength, which comprises heating and tempering in a fallen oven in a reducing gas atmosphere, and then rapidly cooling the obtained sintered body in oil. 6 The raw material powder contains 70% or more of the alloy steel powder, and the remainder is at least one selected from non-ferrous metal powder, alloy powder, alloy steel powder other than the alloy steel, and non-metal powder. The method according to any one of claims 1 to 5, using a mixed powder as a raw material.