JPH07138613A - Production of heat-treated ferrous sintered alloy parts - Google Patents
Production of heat-treated ferrous sintered alloy partsInfo
- Publication number
- JPH07138613A JPH07138613A JP30758893A JP30758893A JPH07138613A JP H07138613 A JPH07138613 A JP H07138613A JP 30758893 A JP30758893 A JP 30758893A JP 30758893 A JP30758893 A JP 30758893A JP H07138613 A JPH07138613 A JP H07138613A
- Authority
- JP
- Japan
- Prior art keywords
- iron
- point
- based sintered
- heat
- sizing
- 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.)
- Granted
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、粉末冶金法により得ら
れた鉄系焼結体を熱処理することによって高強度化及び
高硬度化した熱処理鉄系焼結合金部品、特に寸法精度に
優れた熱処理鉄系焼結合金部品の製造方法に関する。FIELD OF THE INVENTION The present invention relates to a heat-treated iron-based sintered alloy component which is strengthened and hardened by heat-treating an iron-based sintered body obtained by powder metallurgy, and particularly excellent in dimensional accuracy. The present invention relates to a method for manufacturing a heat-treated iron-based sintered alloy part.
【０００２】[0002]
【従来の技術】粉末冶金法により得られる鉄系焼結合金
は、溶解鋳造では製造し難い組成が得られ、又切削等を
せずにニアネットシェイプの機械部品を製造できる等の
利点があるため、最近では従来の鉄系鋳造合金に代わっ
て種々の分野で機械部品として使用されつつある。2. Description of the Related Art Iron-based sintered alloys obtained by powder metallurgy have the advantages that a composition that is difficult to produce by melt casting is obtained, and that near net shape machine parts can be produced without cutting. Therefore, it is recently being used as a mechanical component in various fields in place of the conventional iron-based casting alloy.
【０００３】又、更に高い強度と硬度を必要とする場合
には、鉄系焼結合金に焼入や焼戻等の熱処理を行うこと
ができ、熱処理することによって高強度化及び高硬度化
した熱処理鉄系焼結合金は、エンジンのオイルポンプや
ギヤのような自動車部品等として使用されている。When higher strength and hardness are required, the iron-based sintered alloy can be subjected to heat treatment such as quenching and tempering, and the heat treatment enhances the strength and hardness. Heat-treated iron-based sintered alloys are used as automobile parts such as engine oil pumps and gears.
【０００４】しかるに、近年の自動車や産業機械の軽量
化及び高性能化のニーズを受けて、これら熱処理鉄系焼
結合金部品の一層の高強度化と高寸法精度化の要求が高
まっている。ところが、熱処理鉄系焼結合金はマルテン
サイト変態していることから変形抵抗が大きく、変形能
も低いので、サイジングやコイニングによる寸法矯正が
極めて難しく、寸法精度の更なる向上が極めて困難であ
る。However, in response to recent needs for weight reduction and high performance of automobiles and industrial machines, there is an increasing demand for higher strength and higher dimensional accuracy of these heat-treated iron-based sintered alloy parts. However, since the heat-treated iron-based sintered alloy undergoes martensitic transformation and thus has a large deformation resistance and a low deformability, it is extremely difficult to correct the size by sizing or coining, and it is extremely difficult to further improve the dimensional accuracy.
【０００５】特に、表面硬度がＨRＡで６０以上又は引
張強度が８０ｋｇ／ｍｍ2以上になると、サイジングや
コイニングに１０ｔ／ｃｍ2を越える高い圧力が必要と
なるため、金型への負荷が増大し、金型の寿命が短くな
ると共に、形状的にも矯正し得る対象に制約が生じる。
更に、このような状況から、金型のたわみ等の影響によ
り、寸法精度も通常の鉄系焼結合金ほどには改善されな
い。In particular, if the surface hardness is 60 or more, or tensile strength H R A becomes 80 kg / mm 2 or more, the high pressure in excess of 10t / cm 2 in the sizing or coining is required, load on the mold As a result, the life of the mold is shortened, and the objects that can be geometrically corrected are restricted.
Further, from such a situation, the dimensional accuracy is not improved as much as that of a normal iron-based sintered alloy due to the influence of the bending of the mold and the like.
【０００６】そこで従来は、高強度や高硬度を必要とす
る熱処理鉄系焼結合金部品を製造する場合には、鉄系焼
結体にサイジングやコイニングを施した後、熱処理を行
い、その後更に高い寸法精度を必要とする箇所に切削等
の機械加工を加えて所望の寸法精度を達成している。か
かる方法により製造されている熱処理鉄系焼結合金部品
の一例として、自動車エンジン用のオイルポンプロータ
ーやギヤ等がある。Therefore, conventionally, when manufacturing a heat-treated iron-based sintered alloy part requiring high strength and hardness, the iron-based sintered body is subjected to sizing and coining, then heat-treated, and then further. The desired dimensional accuracy is achieved by applying machining such as cutting to the places where high dimensional accuracy is required. Examples of heat-treated iron-based sintered alloy parts manufactured by such a method include oil pump rotors and gears for automobile engines.
【０００７】[0007]
【発明が解決しようとする課題】しかし、上記した従来
の方法では、鉄系焼結体をサイジング又はコイニングし
た際の残留応力が、後の熱処理中に解放されるため寸法
精度が大きく劣化し、気孔の存在を利用したサイジング
やコイニングが有効に働かない欠点があった。このた
め、例えばオイルポンプでは、寸法精度の低下により、
ポンプ効率が低下したり、騒音が大きくなる等の問題が
発生する。However, in the above-mentioned conventional method, the residual stress when sizing or coining the iron-based sintered body is released during the subsequent heat treatment, so that the dimensional accuracy is greatly deteriorated. There is a drawback that sizing and coining that utilize the existence of pores do not work effectively. For this reason, for example, in an oil pump, due to a decrease in dimensional accuracy,
There are problems such as reduced pump efficiency and loud noise.
【０００８】又、高い寸法精度を得るために、サイジン
グやコイニングの外に切削等の機械加工を必要とするの
で、加工費の増加や、加工による材料ロスから原料費も
増加し、一般の鋼材の機械加工品あるいは冷間又は熱間
鍛造品を熱処理し、機械加工を加えた鉄系合金部品に対
して、コスト競争力を発揮できなかった。Further, in order to obtain high dimensional accuracy, machining such as cutting is required in addition to sizing and coining, so that the processing cost increases and the raw material cost also increases due to material loss due to the processing. However, the cost-competitiveness could not be exhibited for the iron-based alloy parts machined by heat-treating the machined product or the cold or hot forged product.
【０００９】本発明は、かかる従来の事情に鑑み、高強
度且つ高硬度であって、寸法精度に優れた熱処理鉄系焼
結合金部品を、切削加工等の機械加工を施すことなく、
経済的に低コストで製造する方法を提供することを目的
とする。In view of such conventional circumstances, the present invention provides a heat-treated iron-based sintered alloy component having high strength and high hardness and excellent dimensional accuracy without machining such as cutting.
It is an object of the present invention to provide a method of manufacturing economically at low cost.
【００１０】[0010]
【課題を解決するための手段】上記目的を達成するた
め、本発明が提供する熱処理鉄系焼結合金部品の製造方
法は、マルテンサイト変態開始点（Ｍｓ点）が５０〜３
５０℃の温度域にある鉄系焼結体を、オーステナイト化
温度（Ａｅ１点）以上の温度でオーステナイト化した
後、マルテンサイト変態が出現する冷却速度で焼入し、
その焼入体の温度がＭｓ点以上且つＡｅ１点以下の温度
域に達したときサイジング又はコイニングを行うことを
特徴とする。In order to achieve the above object, the method for producing a heat-treated iron-based sintered alloy part provided by the present invention has a martensitic transformation starting point (Ms point) of 50 to 3.
The iron-based sintered body in the temperature range of 50 ° C. is austenitized at a temperature of austenitizing temperature (Ae1 point) or higher, and then quenched at a cooling rate at which martensitic transformation appears,
It is characterized in that sizing or coining is performed when the temperature of the hardened body reaches a temperature range of Ms point or higher and Ae1 point or lower.
【００１１】[0011]
【作用】本発明においては、高い寸法精度を得るため
に、最終工程である熱処理工程において、同時にサイジ
ング又はコイニングによる寸法矯正を行う。即ち、鉄系
焼結体を焼入した焼入体の温度がマルテンサイト変態点
（Ｍｓ点）に達するまでの冷却過程中は、結晶組織が炭
素固溶度の高いｆｃｃ構造のオーステナイト領域にある
ので、焼入体の変形抵抗が低く、変形能が高いため、サ
イジング又はコイニングにより組成変形を与えることで
気孔を潰し、密度を上げると同時に、寸法精度の高い熱
処理焼結合金部品を得ることができる。In the present invention, in order to obtain high dimensional accuracy, dimensional correction by sizing or coining is carried out at the same time in the final heat treatment step. That is, during the cooling process until the temperature of the quenched body obtained by quenching the iron-based sintered body reaches the martensite transformation point (Ms point), the crystal structure is in the austenite region of the fcc structure having high carbon solid solubility. Therefore, since the deformation resistance of the hardened body is low and the deformability is high, it is possible to obtain the heat-treated sintered alloy parts with high dimensional accuracy while crushing the pores by increasing the density by imparting compositional deformation by sizing or coining. it can.
【００１２】即ち、Ａｅ１点以下で且つＭｓ点以上の温
度で焼入体のサイジング又はコイニングを行うと、焼入
体が金型の温度近くまで冷却され、且つまたサイジング
やコイニングの加圧力によりＭｓ点が上昇して、マルテ
ンサイト変態が誘起される。この結果、マルテンサイト
変態により高強度化及び高硬度化が達成されると同時
に、サイジング又はコイニングにより寸法矯正され、し
かもマルテンサイト変態が終了した後に金型から取り出
されるため、金型寸法のままの熱処理焼結合金部品を得
ることができる。That is, when the hardened body is sized or coined at a temperature not higher than the point Ae and not lower than the point Ms, the hardened body is cooled to a temperature close to the temperature of the mold, and the pressure applied during the sizing or coining causes the hardened body to undergo Ms The point rises and the martensitic transformation is induced. As a result, high strength and high hardness are achieved by the martensitic transformation, and at the same time, the dimensions are corrected by sizing or coining, and the martensitic transformation removes the die from the die. A heat-treated sintered alloy part can be obtained.
【００１３】サイジング又はコイニングを開始する際に
焼入体の温度がＭｓ点を越えて低くなると、マルテンサ
イト変態が開始されるため変形抵抗が増大し、焼入体の
気孔を潰すことによる寸法の矯正が困難となる。又、サ
イジング又はコイニングの際に焼入体の温度がオーステ
ナイト化温度（Ａｅ１点）以下にならないと、サイジン
グやコイニングの終了時までにマルテンサイト変態が完
了しないことが多いので、寸法矯正と同時に高強度化及
び高硬度化を図ることが難しい。When the temperature of the hardened body becomes lower than the Ms point at the start of sizing or coining, the martensitic transformation is started, so that the deformation resistance increases and the size of the hardened body is reduced by crushing the pores. Correction becomes difficult. Also, if the temperature of the hardened body does not fall below the austenitizing temperature (Ae1 point) during sizing or coining, the martensite transformation often does not complete by the end of sizing or coining. It is difficult to increase strength and hardness.
【００１４】本発明方法により、Ｍｓ点以上且つＡｅ１
点以下の温度域にある焼入体をサイジング又はコイニン
グを行い、マルテンサイト化により高強度化するために
は、鉄系焼結体のマルテンサイト変態が５０〜３５０℃
の温度域で出現する必要がある。その理由は、鉄系焼結
体のＭｓ点が５０℃より低い場合には、サイジング又は
コイニング中にマルテンサイト変態が完了せず、金型か
らノックアウトした後にマルテンサイト変態することが
あるからである。又、Ｍｓ点が３５０℃を越える場合に
は、サイジング又はコイニングによる寸法矯正が終わら
ないうちに、金型への放熱によりマルテンサイト変態が
進行するため、十分な寸法矯正を行うことができない。According to the method of the present invention, Ms point or more and Ae1
In order to increase the strength by sizing or coining the hardened body in the temperature range below the point and making it martensitic, the martensitic transformation of the iron-based sintered body is 50 to 350 ° C.
Must appear in the temperature range of. The reason is that when the Ms point of the iron-based sintered body is lower than 50 ° C., martensite transformation may not be completed during sizing or coining, and martensite transformation may occur after knocking out from the mold. . On the other hand, if the Ms point exceeds 350 ° C., before the dimensional correction by sizing or coining is completed, the heat is radiated to the mold to cause martensitic transformation, which results in insufficient dimensional correction.
【００１５】又、本発明方法では鉄系焼結体の焼入体の
サイジング又はコイニングをオーステナイト領域で行う
ので、サイジング又はコイニングに支障はない。しか
し、従来の熱処理によりマルテンサイト化した後にサイ
ジング又はコイニングを行う方法では、マルテンサイト
化後の引張強度が８０ｋｇ／ｍｍ2以上、表面硬度がＨR
Ａで６０以上となる鉄系焼結体はサイジング又はコイニ
ングが困難であることを考慮すれば、本発明方法は従来
困難であった上記引張強度及び表面硬度以上のものにつ
いて特に有効であると言える。In the method of the present invention, since the sizing or coining of the hardened body of the iron-based sintered body is performed in the austenite region, there is no problem in sizing or coining. However, in the method of the conventional heat treatment sizing or coining after martensite, the tensile strength after martensite is 80 kg / mm 2 or more, the surface hardness H R
Considering that sizing or coining is difficult for an iron-based sintered body having an A of 60 or more, the method of the present invention can be said to be particularly effective for those having the above-mentioned tensile strength and surface hardness, which have been difficult so far. .
【００１６】更に、粉末冶金法で製造した鉄系焼結体は
一般的に気孔を含むので、サイジング又はコイニングが
可能であるが、その気孔率が５％未満では寸法矯正のた
めに要する変形が部品内部にまで及び、残留歪が大きく
なるうえ変形抵抗が大きくなる。又、気孔率が２０％を
越えると機械的特性が低下して、サイジングやコイニン
グ及び熱処理を行っても強度等の特性が満足すべきもの
とならない。従って、鉄系焼結体の気孔率は５〜２０％
の範囲であることが好ましい。Furthermore, since the iron-based sintered body produced by the powder metallurgy method generally contains pores, sizing or coining is possible. However, if the porosity is less than 5%, the deformation required for dimensional correction will occur. The residual strain increases to the inside of the component and the deformation resistance increases. On the other hand, if the porosity exceeds 20%, the mechanical properties will deteriorate, and the properties such as strength will not be satisfactory even if sizing, coining and heat treatment are performed. Therefore, the porosity of the iron-based sintered body is 5 to 20%.
It is preferably in the range of.
【００１７】鉄系焼結体の組成については特に制限はな
く、炭素鋼の組成であっても合金鋼の組成であっても良
いが、当然のこととして、熱処理によりマルテンサイト
変態を起こして強度及び硬度を高めるために炭素は必須
の元素である。しかし、炭素が０.２重量％未満ではか
かる効果が少なく、１.６重量％を越えると最終部品の
靭性が低下するので、炭素の含有量は０.２〜１.６重量
％の範囲が好ましい。The composition of the iron-based sintered body is not particularly limited, and may be the composition of carbon steel or the composition of alloy steel, but as a matter of course, heat treatment causes martensitic transformation to cause strength. Also, carbon is an essential element for increasing hardness. However, if the carbon content is less than 0.2% by weight, the effect is small, and if the carbon content exceeds 1.6% by weight, the toughness of the final part is deteriorated. Therefore, the carbon content is in the range of 0.2 to 1.6% by weight. preferable.
【００１８】特に、鉄系焼結体が合金鋼の組成の場合、
０.２〜１.６重量％の炭素と、８０重量％以上の鉄と、
合金元素として８重量％以下のＭｏ、６重量％以下のＮ
ｉ、それぞれ４重量％以下のＭｎ、Ｃｒ、Ｃｕ、それぞ
れ２重量％以下のＷ、Ｃｏ、それぞれ１重量％以下のＳ
ｉ、Ｖ、Ａｌから選ばれた少なくとも１種の合金元素と
からなり、前記合金元素について３５０×Ｃ％＋４０×
Ｍｎ％＋３５×Ｖ％＋２０×Ｃｒ％＋１７×Ｎｉ％＋１
１×Ｓｉ％＋１０×Ｃｕ％＋１０×Ｍｏ％＋５×Ｗ％−
１５×Ｃｏ％−３０×Ａｌ％（いずれも重量％）の値Ｆ
(ｅ)が２００〜５００であることが好ましい。In particular, when the iron-based sintered body has a composition of alloy steel,
0.2-1.6% by weight of carbon, 80% by weight or more of iron,
8% by weight or less of Mo and 6% by weight or less of N as alloying elements
i, 4% by weight or less of Mn, Cr, and Cu, 2% by weight or less of W and Co, and 1% by weight or less of S, respectively.
i, V, and at least one alloy element selected from Al, and the alloy element is 350 × C% + 40 ×
Mn% + 35 × V% + 20 × Cr% + 17 × Ni% + 1
1 x Si% + 10 x Cu% + 10 x Mo% + 5 x W%-
Value F of 15 × Co% −30 × Al% (all are weight%)
It is preferable that (e) is 200 to 500.
【００１９】Ｍｎ等の合金元素の含有量を上記のごとく
限定する理由は、これらの合金元素は機械的特性を改善
するために添加されるが、個々の合金元素の各含有量が
上記の範囲を越えるとサイジングやコイニングによる塑
性変形を阻害するからである。又、上記値Ｆ(ｅ)が２０
０未満では最終部品の熱安定性が低下し、十分な強度が
得られず、５００を越えるとサイジングやコイニングに
おける変形抵抗が高くなるため、寸法矯正が困難にな
る。尚、鉄が８０重量％未満では、均一なマルテンサイ
ト変態が難しくなり、高い寸法精度が得られなくなる。The reason why the content of alloying elements such as Mn is limited as described above is that these alloying elements are added to improve the mechanical properties, but the content of each individual alloying element is within the above range. This is because the plastic deformation due to sizing and coining is hindered when the value exceeds the range. Also, the above value F (e) is 20
If it is less than 0, the thermal stability of the final part is lowered and sufficient strength cannot be obtained, and if it exceeds 500, the deformation resistance in sizing and coining becomes high, which makes it difficult to correct the dimension. If the iron content is less than 80% by weight, uniform martensitic transformation becomes difficult and high dimensional accuracy cannot be obtained.
【００２０】次に、本発明方法を更に具体的に説明す
る。まず、粉末冶金法に従って、通常のごとく原料粉末
を混合し、その成形体を焼結することにより鉄系焼結体
を製造する。原料粉末の一部に、合金元素を拡散接合さ
せた部分拡散合金粉末を用いると、成形体中の組成のば
らつきが少なくなるうえ、焼結時の拡散も均一に進行す
るため、成分偏析の少ない均質な焼結体が得られる。こ
の焼結体ではＭｓ点が安定するため、サイジング又はコ
イニングの条件が安定化し、最終部品の寸法精度が向上
する利点がある。Next, the method of the present invention will be described more specifically. First, according to the powder metallurgy method, raw material powders are mixed as usual and the molded body is sintered to produce an iron-based sintered body. Use of partially diffused alloy powder in which alloying elements are diffusion-bonded to part of the raw material powder reduces the compositional variation in the compact and promotes uniform diffusion during sintering, resulting in less segregation of components. A homogeneous sintered body is obtained. Since the Ms point is stable in this sintered body, there are advantages that the sizing or coining conditions are stabilized and the dimensional accuracy of the final part is improved.
【００２１】かくして得られた鉄系焼結体を、本発明方
法ではサイジングやコイニングを施すことなくオーステ
ナイト化処理する。即ち、本発明方法では、サイジング
やコイニングに先立って鉄系焼結体をオーステナイト化
する。従って、焼結体を一旦常温まで降温する必要はな
く、しかも一般に焼結温度はオーステナイト化温度（Ａ
ｅ１点）よりも高温度域であるから、焼結工程後に焼結
体をマルテンサイト変態開始点（Ｍｓ点）以下に冷却さ
せず、そのままＡｅ１点以上の温度でオーステナイト化
することが可能であり、これによりエネルギーの効率化
を図ることができる。In the method of the present invention, the iron-based sintered body thus obtained is austenitized without sizing or coining. That is, in the method of the present invention, the iron-based sintered body is austenitized prior to sizing and coining. Therefore, it is not necessary to once lower the temperature of the sintered body to room temperature, and generally the sintering temperature is the austenitizing temperature (A
Since the temperature is higher than the e1 point), the sintered body can be austenitized at a temperature of the Ae1 point or higher without cooling the sintered body below the martensite transformation start point (Ms point) after the sintering step. As a result, energy efficiency can be improved.
【００２２】鉄系焼結体のオーステナイト化処理は、焼
結体組成によって定まるＡｅ１点以上に焼結体を加熱保
持することにより行われる。加熱方法は一般的なバッチ
式やベルト式の加熱炉等を用いることが可能である。し
かし、サイジング又はコイニング工程での焼入体の実体
温度の管理精度が重要であるため、加熱条件の正確な設
定が可能で且つエネルギー効率の高い誘電加熱が適して
いる。The austenitizing treatment of the iron-based sintered body is performed by heating and holding the sintered body at Ae1 point or more determined by the composition of the sintered body. As a heating method, a general batch type or belt type heating furnace or the like can be used. However, since the accuracy of controlling the actual temperature of the hardened body in the sizing or coining process is important, dielectric heating, which allows accurate setting of heating conditions and has high energy efficiency, is suitable.
【００２３】オーステナイト化処理した焼結体は、マル
テンサイト変態が出現する冷却速度で、例えば１０℃／
秒を越えるような冷却速度で焼入する。尚、冷却によっ
て焼入体の温度がＭｓ点より低下してはならないし、ベ
イナイト変態が生じるような温度に保持することは避け
ねばならない。The austenitized sintered body has a cooling rate at which a martensitic transformation appears, for example, 10 ° C. /
Quench at a cooling rate that exceeds seconds. The temperature of the hardened body must not drop below the Ms point by cooling, and it must be kept at a temperature at which bainite transformation occurs.
【００２４】冷却によって焼入体の温度がＭｓ点以上で
且つＡｅ１点以下の温度域となったとき、サイジング又
はコイニングにより寸法矯正を行う。その際、サイジン
グ又はコイニングの圧力は２〜１０ｔ／ｃｍ2の範囲と
することが好ましい。この圧力が２ｔ／ｃｍ2未満では
十分な寸法矯正が行えず、１０ｔ／ｃｍ2を越えると金
型寿命が短くなるほか、金型のひずみにより得られる部
品の寸法精度が劣化するからである。When the temperature of the hardened body reaches a temperature range of Ms point or higher and Ae1 point or lower by cooling, dimensional correction is performed by sizing or coining. At this time, the sizing or coining pressure is preferably in the range of 2 to 10 t / cm 2 . This is because if the pressure is less than 2 t / cm 2 , sufficient dimensional correction cannot be performed, and if it exceeds 10 t / cm 2 , the die life is shortened and the dimensional accuracy of the component obtained by the distortion of the die deteriorates.
【００２５】又、サイジング又はコイニングを行う際の
金型温度は（Ｍｓ点＋１００）℃以下とすることが好ま
しい。サイジング型又はコイニング型の温度が（Ｍｓ点
＋１００）℃を越えると、サイジング又はコイニング中
に焼入体の温度がＭｓ点以下に下降しないためマルテン
サイト変態が開始されず、金型からノックアウトした段
階で初めてマルテンサイト変態する場合があるので、寸
法精度が低下するからである。尚、Ｍｓ点より１００℃
まで高温であって良いのは、サイジング又はコイニング
時の塑性加工によりマルテンサイト変態開始点が上昇す
る場合があるからである。The mold temperature during sizing or coining is preferably (Ms point + 100) ° C. or lower. When the temperature of the sizing type or coining type exceeds (Ms point + 100) ° C, the temperature of the hardened body does not drop below the Ms point during sizing or coining, so that martensite transformation does not start and knocking out from the die This is because the martensitic transformation may occur for the first time, and the dimensional accuracy decreases. In addition, 100 ° C from the Ms point
The reason why the temperature may be high is that the starting point of martensitic transformation may increase due to plastic working during sizing or coining.
【００２６】[0026]
【実施例】実施例１ 組成がＦｅ−４重量％Ｎｉ−０.５重量％Ｍｏ−１.５重
量％Ｃｕの部分拡散合金粉末に、０.８重量％のグラフ
ァイト粉末と、０.８重量％の潤滑剤を添加混合し、そ
の混合粉末を成形圧力６ｔ／ｃｍ2で成形して、外径４
０ｍｍ×内径２７ｍｍ×厚さ１０ｍｍのリング状成形体
とした。 Example 1 Partial diffusion alloy powder having a composition of Fe-4 wt% Ni-0.5 wt% Mo-1.5 wt% Cu, 0.8 wt% graphite powder, and 0.8 wt% % Lubricant is added and mixed, and the mixed powder is molded under a molding pressure of 6 t / cm 2 to obtain an outer diameter of 4
A ring-shaped molded body having a diameter of 0 mm, an inner diameter of 27 mm and a thickness of 10 mm was prepared.
【００２７】この成形体を減圧窒素ガス雰囲気中におい
て１１５０℃で２０分間焼結することにより、真密度比
８９％で気孔率１１％の鉄系焼結体を得た。この焼結体
のＦ(ｅ)値＝３５０×Ｃ％＋４０×Ｍｎ％＋３５×Ｖ％
＋２０×Ｃｒ％＋１７×Ｎｉ％＋１１×Ｓｉ％＋１０×
Ｃｕ％＋１０×Ｍｏ％＋５×Ｗ％−１５×Ｃｏ％−３０
×Ａｌ％（いずれも重量％）は、組成より計算して３６
８であった。又、この組成の焼結体のマルテンサイト変
態点（Ｍｓ点）とオーステナイト化温度（Ａｅ１点）を
別途調べたところ、Ｍｓ点は約１７０℃及びＡｅ１点は
約７５０℃であった。The compact was sintered in a reduced pressure nitrogen gas atmosphere at 1150 ° C. for 20 minutes to obtain an iron-based sintered compact having a true density ratio of 89% and a porosity of 11%. F (e) value of this sintered body = 350 × C% + 40 × Mn% + 35 × V%
+20 x Cr% +17 x Ni% +11 x Si% +10 x
Cu% + 10 × Mo% + 5 × W% -15 × Co% -30
XAl% (both are weight%) is 36 calculated from the composition.
It was 8. Further, when the martensite transformation point (Ms point) and the austenitizing temperature (Ae1 point) of the sintered body of this composition were separately examined, the Ms point was about 170 ° C. and the Ae1 point was about 750 ° C.
【００２８】次に、この焼結体を８８０℃でオーステナ
イト化処理した後、１８０℃に保持した油槽中に投入し
て焼入した。焼入体が油槽中で約１８秒後に約２６０℃
まで冷却した段階で油槽から取り出し、金型温度１７０
℃に加熱したサイジング金型を用いて、サイジング圧力
７ｔ／ｃｍ2にて内外径を５０μｍのサイジング代で寸
法矯正した。サイジングの終了時点において、得られた
サイジング体はマルテンサイト化が完了していた。Next, this sintered body was austenitized at 880 ° C. and then put into an oil tank kept at 180 ° C. and quenched. Hardened body is about 260 seconds after about 18 seconds in the oil tank
Removed from the oil bath at the stage of cooling to 170
Using a sizing die heated to ° C, the inner and outer diameters were sized with a sizing margin of 50 µm at a sizing pressure of 7 t / cm 2 . At the end of sizing, the martensite conversion of the obtained sizing body was completed.
【００２９】このサイジング体に−１０℃×１０分のサ
ブゼロ処理を施した後の表面硬度はＨRＡで７２、引張
強度は１５０ｋｇ／ｍｍ2であった。又、同様にして得
られた５０個のサイジング体の内外径の真円度は、内径
が最大４μｍ及び外径が最大６μｍであった。The surface hardness of the after performing sub-zero treatment of -10 ° C. × 10 minutes in the sizing member 72 in H R A, tensile strength was 150 kg / mm 2. The circularity of the inner and outer diameters of 50 sizing bodies obtained in the same manner was such that the inner diameter was 4 μm at the maximum and the outer diameter was 6 μm at the maximum.
【００３０】比較のため、同様に製造した同一組成の焼
結体を、同様にオーステナイト化処理した後、３００℃
の塩浴中で６分間保持してベイナイト変態させた焼結
体、及びＭｓ点以下の１５０℃まで冷却させた焼結体に
ついて、上記と同一条件でサイジングを行ったところ、
寸法矯正ができなかった。又、これらの焼結体を７００
℃まで再加熱した後、２５０℃でサイジング又はコイニ
ングしても塑性変形は殆ど認められなかった。For comparison, a sintered body of the same composition produced in the same manner was subjected to an austenitizing treatment in the same manner, and then was heated to 300 ° C.
Sizing was performed under the same conditions as above for the sintered body that had been subjected to bainite transformation by being held in the salt bath for 6 minutes and cooled to 150 ° C. below the Ms point.
I could not correct the dimensions. In addition, these sintered bodies are
Almost no plastic deformation was observed even after sizing or coining at 250 ° C after reheating to 0 ° C.
【００３１】実施例２ 一部に部分拡散合金粉末を用いた組成がＦｅ−３.５重
量％Ｎｉ−０.５重量％Ｍｏ−１重量％Ｍｎ−１重量％
Ｃｒ−０.５重量％Ｓｉの粉末に、０.６重量％のグラフ
ァイト粉末を添加混合し、その混合粉末を潤滑剤を塗布
した金型を用いて成形圧力８ｔ／ｃｍ2で成形して、真
密度比が９１％で寸法が１０ｍｍ×１０ｍｍ×５５ｍｍ
の矩形成形体とした。 Example 2 A composition using a partial diffusion alloy powder as a part is Fe-3.5 wt% Ni-0.5 wt% Mo-1 wt% Mn-1 wt%
Cr-0.5 wt% Si powder was mixed with 0.6 wt% graphite powder, and the mixed powder was molded at a molding pressure of 8 t / cm 2 using a lubricant-coated mold, True density ratio is 91% and dimensions are 10mm x 10mm x 55mm
Rectangular shaped body.
【００３２】この成形体を、減圧窒素ガス雰囲気中にお
いて誘導加熱により１２８０℃まで昇温し、３分間保持
して焼結した後、得られた焼結体を室温まで冷却するこ
となくそのままオーステナイト化処理し、８５０℃まで
冷却した時点で１５０℃に保持した油槽中に投入して焼
入した。尚、組成より前記計算式で算出したＦ(ｅ)値は
３４０であり、又別途求めた焼結後のＭｓ点は約２００
℃及びＡｅ１点は約７５０℃であった。The compact was heated to 1280 ° C. by induction heating in a reduced-pressure nitrogen gas atmosphere and held for 3 minutes to sinter, and then the obtained sintered body was austenitized as it was without cooling to room temperature. When treated and cooled to 850 ° C., it was put into an oil bath kept at 150 ° C. and quenched. The F (e) value calculated from the composition by the above formula is 340, and the separately obtained Ms point after sintering is about 200.
C. and Ae1 point were about 750.degree.
【００３３】更に、焼入体が油槽中で約１５秒後に約２
３０℃まで冷却した段階で油槽から取り出し、金型温度
１００℃に加熱したコイニング金型を用いて、コイニン
グ圧力８ｔ／ｃｍ2にて真密度比９７％までコイニング
した。コイニングの終了時点において、得られたコイニ
ング体はマルテンサイト化が完了していた。Further, the quenched body is about 2 seconds after about 15 seconds in the oil tank.
After cooling to 30 ° C., the coin was taken out from the oil tank and coined to a true density ratio of 97% at a coining pressure of 8 t / cm 2 using a coining mold heated to a mold temperature of 100 ° C. At the end of coining, the obtained coined body had completed martensite formation.
【００３４】このコイニング体は、２００℃×６０分の
焼戻を行った結果、その表面硬度はＨRＡで６９、引張
強度は２１０ｋｇ／ｍｍ2となった。又、コイニング金
型の各コーナー４点で定める真円に対応するコイニング
体の各コーナーで決まる軌跡の真円度は９μｍであっ
た。As a result of tempering this coined body at 200 ° C. for 60 minutes, the surface hardness was 69 in H R A and the tensile strength was 210 kg / mm 2 . Further, the circularity of the locus determined by each corner of the coining body corresponding to the roundness defined by the four corners of the coining die was 9 μm.
【００３５】比較のため、組成がＦｅ−２重量％Ｎｉ−
０.５重量％Ｍｏの合金粉末に０.４重量％のグラファイ
ト粉末を添加混合し、その真密度比９０％の成形体を焼
結した。得られた焼結体において、組成より前記計算式
で算出したＦ(ｅ)値が１７９であり、Ｍｓ点は約３８０
℃及びＡｅ１点は約７５０℃であった。For comparison, the composition is Fe-2 wt% Ni-
0.4 wt% graphite powder was added to and mixed with 0.5 wt% Mo alloy powder, and a compact having a true density ratio of 90% was sintered. In the obtained sintered body, the F (e) value calculated by the above calculation formula from the composition was 179, and the Ms point was about 380.
C. and Ae1 point were about 750.degree.
【００３６】この焼結体をオーステナイト化処理した
後、上記と同一条件で焼入まで実施して約５秒で約４０
０℃まで冷却した段階で、金型温度１８０℃のコイニン
グ金型を用いコイニング圧力８ｔ／ｃｍ2でコイニング
した。しかし、このコイニング体の真密度比は９２％ま
でしか上昇せず、このコイニング体を同一条件で焼戻し
た場合の表面硬度はＨRＡで８０程度で、引張強度は６
５ｋｇ／ｍｍ2しかなく、コイニング金型の各コーナー
４点で定める真円に対応するコイニング体の各コーナー
で決まる軌跡の真円度も４２μｍと極めて悪かった。After subjecting this sintered body to an austenitizing treatment, quenching is carried out under the same conditions as described above, and it takes about 40 seconds in about 5 seconds.
At the stage of cooling to 0 ° C., coining was performed at a coining pressure of 8 t / cm 2 using a coining mold having a mold temperature of 180 ° C. However, the true density ratio of this coined body increased only to 92%, and the surface hardness of the coined body when tempered under the same conditions was about 80 H R A and the tensile strength was 6%.
Only 5 kg / mm 2 , and the circularity of the locus determined by each corner of the coining body corresponding to the four circles determined by each corner of the coining die was 42 μm, which was extremely poor.
【００３７】実施例３ 組成がＦｅ−４重量％Ｎｉ−０.５重量％Ｍｏ−１.５重
量％Ｃｕ−０.８重量％Ｃからなる熱処理焼結合金部品
として、外径５５ｍｍであってインボリュート歯形の内
接円の内径が３８ｍｍで設計される４葉５接のオイルポ
ンプのアウターローターを、下記の各方法により内接円
の真円度が１０μｍとなるように製造した。 Example 3 A heat-treated sintered alloy part composed of Fe-4 wt% Ni-0.5 wt% Mo-1.5 wt% Cu-0.8 wt% C and having an outer diameter of 55 mm. An outer rotor of a four-leaf, five-contact oil pump designed to have an inner diameter of an inscribed circle of an involute tooth shape of 38 mm was manufactured by the following methods so that the circularity of the inscribed circle was 10 μm.
【００３８】即ち、上記組成の焼結体を冷間サイジング
したアウターローターＡ、焼結体を冷間サイジングした
後焼入し、更に切削加工したアウターローターＢ、及び
焼結体を実施例１と同様にオーステナイト化処理し、そ
の焼入体を実施例１と同一条件でサイジングしたアウタ
ーローターＣを、それぞれ製造した。That is, the outer rotor A obtained by cold-sizing the sintered body having the above composition, the outer rotor B obtained by cold-sizing the sintered body, followed by quenching, and further cutting, and the sintered body were as in Example 1. Similarly, an austenitizing treatment was performed, and the hardened body was sized under the same conditions as in Example 1 to manufacture outer rotors C.
【００３９】これらのアウターローターに対して、歯形
の外接円の外径が異なるインナーローターを組み合わ
せ、チップクリアランスを一定にして各オイルポンプの
耐久テストを実施した。その結果、アウターローターＡ
は吐出圧力が６１ｋｇ／ｃｍ2に達したところで変形を
生じ、ローターがロックして回転不能になった。アウタ
ーローターＢ及びＣは吐出圧力９０ｋｇ／ｃｍ2で１０
００時間運転しても何ら支障はなかったが、１０００時
間運転時の効率はアウターローターＣの方が１０％程度
高かった。The outer rotors were combined with inner rotors having different outer diameters of the circumscribed circles of the tooth profile, and the tip clearance was kept constant to carry out a durability test of each oil pump. As a result, the outer rotor A
Was deformed when the discharge pressure reached 61 kg / cm 2 , the rotor was locked and could not rotate. Outer rotors B and C are 10 at a discharge pressure of 90 kg / cm 2 .
Although there was no problem even after running for 00 hours, the outer rotor C was about 10% higher in efficiency after running for 1000 hours.
【００４０】又、耐久テスト後の摺動面を評価したとこ
ろ、アウターローターＣの摩耗量が５μｍであったのに
対して、アウターローターＢの摩耗量は１４μｍであ
り、キャビテーション損傷の度合も大きかった。尚、ア
ウターローターＣのサイジング面は、露出している気孔
量が約４％程度と少なく高密度化していた。When the sliding surface after the durability test was evaluated, the wear amount of the outer rotor C was 5 μm, whereas the wear amount of the outer rotor B was 14 μm, and the degree of cavitation damage was also large. It was In addition, the sizing surface of the outer rotor C had a high density with only about 4% of exposed pores.
【００４１】[0041]
【発明の効果】本発明によれば、熱処理により高強度化
と高硬度化を図ると同時に、サイジング品やコイニング
品又は切削加工品の精度に近い高寸法精度を有する熱処
理鉄系焼結合金部品を提供することができる。しかも、
本発明によれば、従来に比較して、切削等の後加工の必
要がないので機械加工費を低減できるほか、原料の加工
ロスの低減により原材料の歩留りを向上でき、極めて経
済的である。EFFECTS OF THE INVENTION According to the present invention, a heat-treated iron-based sintered alloy part having a high strength and a high hardness by heat treatment and a high dimensional accuracy close to that of a sizing product, a coining product or a machined product. Can be provided. Moreover,
According to the present invention, there is no need for post-processing such as cutting as compared with the prior art, so that the machining cost can be reduced, and the raw material yield can be improved by reducing the processing loss of the raw material, which is extremely economical.
【００４２】従って、本発明による熱処理鉄系焼結合金
部品は、通常の鋼材の機械加工品等に代わり得る寸法精
度、性能、経済性等を兼ね備え、例えばオイルポンプの
ローターを製造すれば、歯形の寸法精度改善により吐出
量が増加し、ポンプ効率が向上し且つポンプの騒音を低
下させることが可能となる。又、本発明の熱処理鉄系焼
結合金部品の表面は気孔の潰れた面となっているので、
耐摩耗性が改善されると共に、キャビテーションの発生
も低く抑えられる。Therefore, the heat-treated iron-based sintered alloy component according to the present invention has dimensional accuracy, performance, economy, etc., which can be used as a substitute for ordinary machined products of steel materials. For example, if a rotor for an oil pump is manufactured, it will have a tooth profile. By improving the dimensional accuracy, the discharge amount is increased, the pump efficiency is improved, and the noise of the pump can be reduced. Further, since the surface of the heat-treated iron-based sintered alloy part of the present invention is a surface with crushed pores,
The abrasion resistance is improved and the occurrence of cavitation is suppressed to a low level.
Claims (8)
５０〜３５０℃の温度域にある鉄系焼結体を、オーステ
ナイト化温度（Ａｅ１点）以上の温度でオーステナイト
化した後、マルテンサイト変態が出現する冷却速度で焼
入し、その焼入体の温度がＭｓ点以上且つＡｅ１点以下
の温度域に達したときサイジング又はコイニングを行う
ことを特徴とする熱処理鉄系焼結合金部品の製造方法。1. A martensitic transformation is carried out after an iron-based sintered body having a martensitic transformation starting point (Ms point) in a temperature range of 50 to 350 ° C. is austenitized at a temperature of austenitizing temperature (Ae1 point) or higher. Of a heat-treated iron-based sintered alloy part, which is characterized in that quenching is performed at a cooling rate at which Method.
張強度が８０ｋｇ／ｍｍ2以上、表面硬度がＨRＡで６０
以上となるものであることを特徴とする、請求項１に記
載の熱処理鉄系焼結合金部品の製造方法。2. The iron-based sintered body has a tensile strength of 80 kg / mm 2 or more and a surface hardness of H R A of 60 after martensite formation.
It is what is mentioned above, The manufacturing method of the heat treatment iron system sintered alloy parts of Claim 1 characterized by the above-mentioned.
ことを特徴とする、請求項１に記載の熱処理鉄系焼結合
金部品の製造方法。3. The method for manufacturing a heat-treated iron-based sintered alloy component according to claim 1, wherein the porosity of the iron-based sintered body is 5 to 20%.
の炭素と、残部の鉄とからなることを特徴とする、請求
項１に記載の熱処理鉄系焼結合金部品の製造方法。4. The composition of the iron-based sintered body is 0.2 to 1.6% by weight.
2. The method for producing a heat-treated iron-based sintered alloy component according to claim 1, wherein the heat-treated iron-based sintered alloy component is made of carbon and the balance iron.
の炭素と、８０重量％以上の鉄と、合金元素として８重
量％以下のＭｏ、６重量％以下のＮｉ、それぞれ４重量
％以下のＭｎ、Ｃｒ、Ｃｕ、それぞれ２重量％以下の
Ｗ、Ｃｏ、それぞれ１重量％以下のＳｉ、Ｖ、Ａｌから
選ばれた少なくとも１種の合金元素とからなり、前記合
金元素について３５０×Ｃ％＋４０×Ｍｎ％＋３５×Ｖ
％＋２０×Ｃｒ％＋１７×Ｎｉ％＋１１×Ｓｉ％＋１０
×Ｃｕ％＋１０×Ｍｏ％＋５×Ｗ％−１５×Ｃｏ％−３
０×Ａｌ％（いずれも重量％）の値が２００〜５００で
あることを特徴とする、請求項１に記載の熱処理鉄系焼
結合金部品の製造方法。5. The composition of the iron-based sintered body is 0.2 to 1.6% by weight.
Carbon, 80% by weight or more of iron, 8% by weight or less of Mo as an alloying element, 6% by weight or less of Ni, 4% by weight or less of Mn, Cr, Cu, or 2% by weight or less of W or Co, respectively. , 1% by weight or less, and at least one alloy element selected from Si, V, and Al, and 350 × C% + 40 × Mn% + 35 × V for the alloy elements.
% + 20 × Cr% + 17 × Ni% + 11 × Si% + 10
X Cu% + 10 x Mo% + 5 x W% -15 x Co% -3
The method for producing a heat-treated iron-based sintered alloy component according to claim 1, wherein the value of 0 × Al% (all by weight) is 200 to 500.
冷却させず、そのままＡｅ１点以上の温度でオーステナ
イト化することを特徴とする、請求項１に記載の熱処理
鉄系焼結合金部品の製造方法。6. The heat-treated iron-based sintered bond according to claim 1, wherein the iron-based sintered body is austenitized at a temperature of Ae1 point or higher as it is without cooling from the sintering temperature to Ms point or lower. Manufacturing method of gold parts.
１０ｔ／ｃｍ2であることを特徴とする、請求項１に記
載の熱処理鉄系焼結合金部品の製造方法。7. The sizing or coining pressure is 2 to
It is 10 t / cm < 2 >, The manufacturing method of the heat processing iron system sintered alloy parts of Claim 1 characterized by the above-mentioned.
（Ｍｓ点＋１００）℃以下に加熱することを特徴とす
る、請求項１に記載の熱処理鉄系焼結合金部品の製造方
法。8. The method for producing a heat-treated iron-based sintered alloy part according to claim 1, wherein the sizing die or the coining die is heated to (Ms point + 100) ° C. or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30758893A JP3517916B2 (en) | 1993-11-12 | 1993-11-12 | Manufacturing method of heat-treated iron-based sintered alloy parts |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30758893A JP3517916B2 (en) | 1993-11-12 | 1993-11-12 | Manufacturing method of heat-treated iron-based sintered alloy parts |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07138613A true JPH07138613A (en) | 1995-05-30 |
| JP3517916B2 JP3517916B2 (en) | 2004-04-12 |
Family
ID=17970878
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30758893A Expired - Lifetime JP3517916B2 (en) | 1993-11-12 | 1993-11-12 | Manufacturing method of heat-treated iron-based sintered alloy parts |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3517916B2 (en) |
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|---|---|---|---|---|
| JP2007511692A (en) * | 2003-05-14 | 2007-05-10 | ジーケイエヌ ジンテル メタルズ ホールディング ゲゼルシャフト ミット ベシュレンクテル ハフツング | Oil pump |
| JP2005042812A (en) * | 2003-07-22 | 2005-02-17 | Nissan Motor Co Ltd | Sintered sprocket for silent chain and production method therefor |
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| CN109175370A (en) * | 2018-11-01 | 2019-01-11 | 河北工业大学 | A kind of preparation method of the composite material with magnetic field regulation martensitic traoformation |
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| CN109175370B (en) * | 2018-11-01 | 2020-05-12 | 河北工业大学 | Preparation method of composite material with magnetic field regulation and control of martensite phase transformation |
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| Publication number | Publication date |
|---|---|
| JP3517916B2 (en) | 2004-04-12 |
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