JPH04337001A - Low-alloy steel powder for powder metallurgy and its sintered molding and tempered molding - Google Patents
Low-alloy steel powder for powder metallurgy and its sintered molding and tempered moldingInfo
- Publication number
- JPH04337001A JPH04337001A JP13597691A JP13597691A JPH04337001A JP H04337001 A JPH04337001 A JP H04337001A JP 13597691 A JP13597691 A JP 13597691A JP 13597691 A JP13597691 A JP 13597691A JP H04337001 A JPH04337001 A JP H04337001A
- Authority
- JP
- Japan
- Prior art keywords
- powder
- low
- alloy steel
- strength
- sintered
- 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.)
- Pending
Links
- 239000000843 powder Substances 0.000 title claims abstract description 55
- 229910000851 Alloy steel Inorganic materials 0.000 title claims abstract description 32
- 238000000465 moulding Methods 0.000 title abstract description 8
- 238000004663 powder metallurgy Methods 0.000 title abstract description 7
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 9
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 8
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 6
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 239000000126 substance Substances 0.000 claims abstract description 4
- 238000005056 compaction Methods 0.000 abstract description 20
- 230000000694 effects Effects 0.000 abstract description 12
- 238000010438 heat treatment Methods 0.000 abstract description 11
- 238000005245 sintering Methods 0.000 abstract description 10
- 229910052748 manganese Inorganic materials 0.000 abstract description 4
- 239000000203 mixture Substances 0.000 abstract description 4
- 238000000034 method Methods 0.000 description 26
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 229910045601 alloy Inorganic materials 0.000 description 10
- 239000000956 alloy Substances 0.000 description 10
- 229910000831 Steel Inorganic materials 0.000 description 7
- 238000005275 alloying Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 238000005204 segregation Methods 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000011362 coarse particle Substances 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- HGPXWXLYXNVULB-UHFFFAOYSA-M lithium stearate Chemical compound [Li+].CCCCCCCCCCCCCCCCCC([O-])=O HGPXWXLYXNVULB-UHFFFAOYSA-M 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000007569 slipcasting Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000009692 water atomization Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、圧粉成形性が良好であ
りしかも引張り強度及び疲労強度の高い成形体を与える
粉末冶金用低合金鋼粉及び該低合金鋼粉を用いて得られ
る焼結成形体、並びに該焼結体を調質熱処理してなる調
質成形体に関するものである。[Industrial Application Field] The present invention relates to a low-alloy steel powder for powder metallurgy that provides a compact with good compactability and high tensile strength and fatigue strength, and a sintered steel powder obtained using the low-alloy steel powder. The present invention relates to a formed body and a heat-treated molded body obtained by subjecting the sintered body to heat treatment.
【０００２】0002
【従来の技術】粉末冶金法により低合金鋼焼結体の強度
アップを図る代表的な方法としては、プレミックス法、
プレアロイ法、及びこれらの中間的手法である部分拡散
法が知られている。即ちプレミックス法とは、鉄粉と他
の金属粉または合金粉（以下、添加金属粉ということが
ある）を均一に混合し、これを圧粉成形した後加熱焼結
する方法である。[Prior Art] Typical methods for increasing the strength of low-alloy steel sintered bodies using powder metallurgy include the premix method,
The prealloy method and the partial diffusion method, which is an intermediate method between these methods, are known. That is, the premix method is a method in which iron powder and other metal powder or alloy powder (hereinafter sometimes referred to as added metal powder) are uniformly mixed, compacted, and then heated and sintered.
【０００３】この方法は、成形加工性が良く高密度の焼
結成形体が得られ易いという利点がある反面、圧粉成形
までの段階で鉄粉と添加金属粉が比重差によって分離・
偏析を起こしたり、あるいは焼結時における添加金属の
拡散が十分に進まないといった難点があり、焼結成形体
の強度にばらつきが生じ疲労強度が十分に上がらないと
いう品質上の問題がある。[0003] This method has the advantage of good moldability and the ability to easily obtain a high-density sintered compact, but on the other hand, the iron powder and the added metal powder are separated and separated due to the difference in specific gravity in the stage up to compaction.
There are drawbacks such as segregation or insufficient diffusion of added metals during sintering, resulting in quality problems such as variations in the strength of the sintered compact and insufficient fatigue strength.
【０００４】これに対しプレアロイ法は、Ｎｉ，Ｃｕ，
Ｍｏ等の合金元素を予め鉄中に固溶した合金粉末を使用
するものであり、プレミックス法で指摘した様な問題は
起こさない。ところがこの方法では、プレアロイ化して
得られる合金鋼粉が鉄粉に比べて非常に硬質であるため
圧粉成形時の圧密度を十分に高めることができず、高密
度の焼結成形体が得られにくい。従って当該プレアロイ
化合金鋼の物性を十分に生かすことができない。On the other hand, the pre-alloy method uses Ni, Cu,
This method uses alloy powder in which alloying elements such as Mo are dissolved in iron in advance, and does not cause the problems pointed out in the premix method. However, with this method, the alloy steel powder obtained by pre-alloying is much harder than iron powder, so it is not possible to sufficiently increase the compaction density during powder compaction, and a high-density sintered compact cannot be obtained. Hateful. Therefore, the physical properties of the pre-alloyed alloy steel cannot be fully utilized.
【０００５】また部分拡散法とは、鉄粉と添加合金粉を
混合し部分拡散させることによって鉄粉表面に添加合金
粉を予め付着させておくもので、上記プレミックス法と
プレアロイ法の折衷的手法に当たるものであるが、焼結
工程で添加合金を均一に拡散させることは非常に難しい
。そのため焼結成形体の内部組織はやはり部分的に不均
一となって強度の弱い部分が生じる。そしてこの焼結成
形体にくり返し外力が作用したとき、強度の弱い部分に
応力が集中し、短期間のうちに疲労破壊を起こす。[0005] The partial diffusion method is a method in which the iron powder and the additive alloy powder are mixed and partially diffused to preliminarily adhere the additive alloy powder to the surface of the iron powder, and is a compromise between the premix method and the prealloy method. However, it is extremely difficult to uniformly diffuse the additive alloy during the sintering process. As a result, the internal structure of the sintered compact becomes partially non-uniform, resulting in areas with weak strength. When external forces are repeatedly applied to this sintered compact, stress concentrates on the weaker parts, causing fatigue failure within a short period of time.
【０００６】この様にプレミックス法、プレアロイ法及
び部分拡散法には夫々長所、短所があり、現在実用化さ
れている低合金鋼粉では、成形加工性向上による高密度
化及び添加合金の十分な拡散による高強度化と疲労強度
向上の要求のすべてを満足することはできない。[0006] As described above, the premix method, prealloy method, and partial diffusion method each have their advantages and disadvantages, and with the low alloy steel powder currently in practical use, it is difficult to achieve high density by improving formability and sufficient addition of alloy. It is not possible to satisfy all of the demands for higher strength and improved fatigue strength through diffusion.
【０００７】[0007]
【発明が解決しようとする課題】本発明は上記の様な事
情に着目してなされたものであって、その目的は、上記
方法の中でも添加合金元素の偏析を生じることなく均質
な焼結成形体を得ることのできるプレアロイ法に注目し
、該プレアロイ粉末の成形加工性を高めて高密度化を達
成することにより、強度及び疲労強度の優れた焼結成形
体を与え得る様な低合金鋼粉、及び焼結成形体並びにこ
の焼結成形体を熱処理してなる調質成形体を提供しよう
とするものである。[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a homogeneous sintered compact in the above-mentioned method without causing segregation of added alloying elements. By focusing on the pre-alloying method that can obtain the pre-alloyed powder, and increasing the molding processability of the pre-alloyed powder to achieve high density, we have developed a low-alloy steel powder that can provide a sintered compact with excellent strength and fatigue strength. Another object of the present invention is to provide a sintered compact and a heat-treated compact obtained by heat-treating the sintered compact.
【０００８】[0008]
【課題を解決するための手段】上記課題を達成すること
のできた本発明の構成は、化学成分が、Ｃ ：０．０
５％以下、
Ｍｎ：０．３ ％以下、
Ｎｉ：０．３ 〜２．５ ％
Ｍｏ：０．３ 〜２．０ ％
Ｏ ：０．２ ％以下、
残部：Ｆｅ及び不可避不純物
であるところに要旨を有する粉末冶金用低合金鋼粉であ
り、この低合金鋼粉は優れた成形加工性を有しており、
これを圧縮成形してから焼結すると、成形体密度が６．
７５ｇ／ｃｃ以上という極めて高密度で且つ成分偏析が
なく高強度、高疲労特性の焼結成形体を得ることができ
、焼結成形体を更に熱処理すると強度特性の良好な調質
成形体を得ることができる。[Means for Solving the Problems] The structure of the present invention that can achieve the above-mentioned problems is such that the chemical component is C: 0.0
5% or less, Mn: 0.3% or less, Ni: 0.3 to 2.5%, Mo: 0.3 to 2.0%, O: 0.2% or less, balance: Fe and unavoidable impurities. This is a low alloy steel powder for powder metallurgy with the following features: This low alloy steel powder has excellent formability,
When this is compression molded and then sintered, the compact density becomes 6.
It is possible to obtain a sintered compact with an extremely high density of 75 g/cc or more, no component segregation, and high strength and high fatigue properties.If the sintered compact is further heat-treated, a tempered compact with good strength properties can be obtained. can.
【０００９】[0009]
【作用】本発明では、特にフェライト硬化作用の大きい
合金元素であるＮｉ量を少なめに抑えると共に、焼入れ
効果の高い合金元素として適量のＭｏを含有させたもの
であり、それにより低合金鋼粉としての成形加工性を高
めて高圧密化を可能にすると共に、焼結もしくはその後
の焼入れ性を高めて焼結成形体及び調質成形体の強度及
び疲労特性を高めることができる。以下、本発明で定め
る低合金鋼粉の構成元素についてその作用効果及び含有
率を定めた理由を詳述する。[Function] In the present invention, the amount of Ni, which is an alloying element with a particularly strong ferrite hardening effect, is suppressed to a small level, and an appropriate amount of Mo, which is an alloying element with a high hardening effect, is contained. It is possible to improve the molding processability of the material, thereby making it possible to achieve high compaction, and also to improve the sintering or subsequent hardenability, thereby increasing the strength and fatigue properties of the sintered compact and the tempered compact. Below, the reasons for determining the effects and contents of the constituent elements of the low-alloy steel powder defined in the present invention will be explained in detail.
【００１０】Ｃ：０．０５％以下
Ｃは低合金鋼粉を硬質化し成形加工性（圧縮加工性）を
著しく悪化させる元素であり、多過ぎると鋼粉が硬くな
って圧粉成形による圧密度が十分に上がらず、成形体内
部にミクロポロシティーが残るため十分な強度特性が得
られなくなる。従ってＣ量は０．０５％以下、より好ま
しくは０．０３％以下に抑えるべきである。C: 0.05% or less C is an element that hardens low-alloy steel powder and significantly deteriorates the formability (compression workability). If it is too large, the steel powder becomes hard and the compaction density during powder compaction decreases. is not sufficiently increased, and microporosity remains inside the molded body, making it impossible to obtain sufficient strength properties. Therefore, the amount of C should be suppressed to 0.05% or less, more preferably 0.03% or less.
【００１１】Ｍｎ：０．３ ％以下
ＭｎもＦｅ中に固溶することによって当該鋼粉を硬質化
すると共に、酸素との親和力が高いため一部が酸化物系
介在物として存在し、当該鋼粉の成形加工性を著しく悪
化させる。その結果、圧粉成形時における圧密度の向上
が阻害され、Ｃ量過多の場合と同様に成形体内部にミク
ロポロシティーが残って強度特性を低下させる。従って
Ｍｎ量は０．３ ％以下、より好ましくは０．２５％以
下に抑えるべきである。Mn: 0.3% or less Mn also hardens the steel powder by solid solution in Fe, and since it has a high affinity with oxygen, some of it exists as oxide inclusions, making it difficult to form a solid solution in the steel. Significantly deteriorates the moldability of powder. As a result, the improvement in compaction density during powder compaction is inhibited, and microporosity remains inside the compact, similar to the case where the amount of C is excessive, resulting in a decrease in strength properties. Therefore, the amount of Mn should be suppressed to 0.3% or less, more preferably 0.25% or less.
【００１２】Ｎｉ：０．３ 〜２．５ ％Ｎｉは焼結及
び熱処理後の成形体強度を高めるうえで欠くことのでき
ない元素であるが、多過ぎると固溶強化によって当該鋼
粉を硬質化し成形加工性を悪化させて圧密度の向上に著
しい障害となるばかりでなく、熱処理後の残留オーステ
ナイトの増大によって調質成形体の強度を低下させる。
そのため、こうした障害を生じることなく熱処理後の成
形体強度を十分に高めるため、Ｎｉ量は０．３ 〜２．
５％、より好ましくは０．３ 〜２．０ ％の範囲に設
定すべきである。Ni: 0.3 to 2.5% Ni is an indispensable element for increasing the strength of the compact after sintering and heat treatment, but if it is too much, it will harden the steel powder by solid solution strengthening. This not only deteriorates molding processability and becomes a significant hindrance to improving compaction density, but also reduces the strength of the heat-treated molded product due to an increase in retained austenite after heat treatment. Therefore, in order to sufficiently increase the strength of the molded product after heat treatment without causing such problems, the amount of Ni should be 0.3 to 2.
It should be set at 5%, more preferably in the range of 0.3-2.0%.
【００１３】Ｍｏ：０．３ 〜２．０ ％Ｍｏは焼入れ
効果の高い元素であり、焼結及び熱処理後の強度を高め
るうえで欠くことのできないものであり、０．３ ％以
上含有させなければならない。しかし焼入れ効果は２．
０ ％の添加で飽和し、それ以上含有量を高めても強度
はそれ以上改善されず、むしろ低合金鋼粉の成形性を低
下させて高圧密化の障害となるので、２．０ ％以下、
より好ましくは１．５ ％以下に抑えるのがよい。Mo: 0.3 to 2.0% Mo is an element with a high hardening effect and is indispensable for increasing the strength after sintering and heat treatment, and must be contained at 0.3% or more. Must be. However, the hardening effect is 2.
It is saturated with addition of 0%, and even if the content is increased further, the strength will not be improved any further.In fact, it will reduce the formability of low-alloy steel powder and become an obstacle to high consolidation, so it should not exceed 2.0%. ,
More preferably, it is suppressed to 1.5% or less.
【００１４】Ｏ：０．２ ％以下
Ｏは酸化物系介在物として混入し成形加工性を低下させ
る大きな要因となるので、０．２ ％以下に抑えなけれ
ばならない。O: 0.2% or less O is mixed in as oxide inclusions and becomes a major factor in reducing moldability, so it must be suppressed to 0.2% or less.
【００１５】本発明で規定される必須元素は以上の通り
であって、残部はＦｅ及び不可避不純物であり、この低
合金鋼は常法に従って溶製した後、スタンプミル法、ボ
ールミル法、エッジミル法、カッタミル法、アトマイズ
法等公知の方法で粉末とされる。この場合、比較的低い
圧力で高密度の圧粉成形体を得るには、その粒度構成を
、４５μｍ 以下の微粒物が３０％以下で且つ ２５０
μｍ を超える粗粒物が１％を超えない様にすることが
望まれる。
その理由は、微粒物が多過ぎてもまた粗粒物が多過ぎて
も、圧粉成形時の圧密化が困難になるからである。そし
て上記成分組成と好適粒度構成の要件に合致する低合金
鋼粉は、たとえば５トン／ｃｍ２といった比較的小さい
圧力で低合金鋼粉を高度に圧密化することができる。The essential elements specified in the present invention are as described above, the remainder being Fe and unavoidable impurities, and this low alloy steel is melted according to a conventional method and then processed by stamp milling, ball milling, or edge milling. It is made into powder by a known method such as , cut mill method, atomization method, etc. In this case, in order to obtain a high-density green compact at a relatively low pressure, the particle size composition should be 30% or less of fine particles of 45 μm or less, and 250 μm or less.
It is desirable that the content of coarse particles exceeding μm does not exceed 1%. The reason for this is that if there are too many fine particles or too many coarse particles, compaction during compaction becomes difficult. A low-alloy steel powder that meets the requirements for the above-mentioned composition and suitable particle size structure can be highly consolidated with a relatively small pressure of, for example, 5 tons/cm2.
【００１６】圧粉成形法としては、モールディング法、
遠心加圧法、押出法、静水圧加圧法、高温加圧法、スリ
ップキャスティング法等、公知の成形法が成形体の形状
や要求性能に応じて適宜選択して採用することができる
。[0016] Examples of the powder compacting method include a molding method,
Known molding methods such as centrifugal pressing, extrusion, hydrostatic pressing, high-temperature pressing, and slip casting can be appropriately selected and employed depending on the shape and required performance of the molded article.
【００１７】尚圧粉成形に当たっては、常法に従ってス
テアリン酸亜鉛、ステアリン酸リチウム等の脂肪酸金属
塩、パラフィン等の潤滑剤を少量添加して圧粉成形性を
高めることも有効である。In powder compacting, it is also effective to add a small amount of a fatty acid metal salt such as zinc stearate or lithium stearate, or a lubricant such as paraffin according to a conventional method to improve compaction properties.
【００１８】かくして得られる圧粉成形体をたとえば１
０００〜１３００℃程度、より一般的には１１００〜１
２００℃程度で焼結し、必要によってはその後更に熱処
理を行なって調質すると、成形体密度が６．７５ｇ／ｃ
ｃ以上の高密度の成形体が得られる。またこの熱処理工
程では、低合金鋼粉中に含有された特にＭｏの焼入れ効
果によって成形体は硬質化し、優れた引張り強度を示す
ものとなる。しかもこの焼結成形体及び調質成形体は、
前述の如くプレアロイ化させた低合金鋼粉を圧密化した
ものであるから、内部に合金元素の偏析がなく極めて均
質であり、またミクロポロシティー等の内部欠陥も存在
しないので、疲労強度も非常に優れたものとなる。[0018] For example, the powder compact obtained in this manner is
000-1300℃, more generally 1100-1
Sintering at around 200℃, followed by further heat treatment and refining if necessary, results in a compact density of 6.75g/c.
A molded article with a high density of c or more can be obtained. In addition, in this heat treatment step, the compact becomes hard due to the quenching effect of Mo contained in the low alloy steel powder, and exhibits excellent tensile strength. Moreover, these sintered compacts and heat-treated compacts are
As mentioned above, it is made by compacting pre-alloyed low-alloy steel powder, so it is extremely homogeneous with no segregation of alloying elements inside, and there are no internal defects such as microporosity, so it has very high fatigue strength. Becomes excellent.
【００１９】[0019]
【実施例】表１に示す如く、Ｃ，Ｍｎ，Ｎｉ，Ｍｏ，Ｏ
含有量の異なる低合金鋼を高周波溶解炉によって溶製し
た後、この溶鋼を用いて水アトマイズ（圧力８０〜１０
０ｋｇ／ｃｍ２）で粉末化し、アンモニア分解ガス中で
９５０ ℃×３０分の還元処理を行なって低合金粉末を
得た。この低合金粉末に０．６ ％グラファイト（０．
６％）を、ステアリン酸亜鉛（０．７％）を潤滑剤とし
て配合し、６トン／ｃｍ２で一次成形し、８００ ℃×
３０分の仮焼結後１０トン／ｃｍ２の圧力で再圧縮し、
更に真空中１２００℃で３０分間焼結して焼結成形体を
得た。また調質熱処理は、真空中８５０ ℃で３０分間
均熱処理した後油焼入れを行ない、次いで２００ ℃に
焼戻しを行なった。[Example] As shown in Table 1, C, Mn, Ni, Mo, O
After melting low-alloy steel with different contents in a high-frequency melting furnace, this molten steel is used for water atomization (pressure 80-10
0 kg/cm2) and subjected to reduction treatment at 950° C. for 30 minutes in ammonia decomposition gas to obtain a low alloy powder. 0.6% graphite (0.6%) was added to this low alloy powder.
6%) was blended with zinc stearate (0.7%) as a lubricant, first formed at 6 tons/cm2, and heated at 800°C.
After pre-sintering for 30 minutes, it is compressed again at a pressure of 10 tons/cm2.
Further, it was sintered in vacuum at 1200° C. for 30 minutes to obtain a sintered compact. Further, the refining heat treatment was performed by soaking in vacuum at 850°C for 30 minutes, followed by oil quenching, and then tempering at 200°C.
【００２０】焼結成形体及び調質成形体の引張り強度及
び疲労特性を表１に一括して示す。尚、疲労特性は小野
式回転曲げ疲労試験機を使用し、ミニ試片を用いて回転
数３６００ｒｐｍ で、１０７回転の回転曲げに耐え得
る最大の応力によって求めた。[0020] The tensile strength and fatigue properties of the sintered compact and the heat-treated compact are summarized in Table 1. The fatigue properties were determined using an Ono rotary bending fatigue tester using a mini specimen at a rotational speed of 3600 rpm and the maximum stress that could withstand rotational bending of 107 rotations.
【００２１】[0021]
【表１】[Table 1]
【００２２】表１より次の様に考察することができる。
Ｎｏ．１：Ｃ量が規定量を超える比較例であり、低合金
鋼粉が硬質化するため成形加工性が悪くなって圧粉成形
体の密度が上がらず、焼結成形体及びその熱処理調質体
の引張り強度及び疲労強度が低い。
Ｎｏ．２，６ ：Ｎｏ．２はＭｎ量及びＯ量が多過ぎる
比較例、Ｎｏ．６はＯ量が多過ぎる比較例であり、やは
り低合金鋼粉が硬質化し圧粉成形体の圧密度が十分に上
がらず、焼結成形体及びその熱処理調質体の引張り強度
が不十分であり、疲労強度も低い。
Ｎｏ．３：Ｎｉ量が不足する比較例であり、低合金鋼粉
が軟質であって成形加工性が良く圧密度は十分に上がる
が、焼結成形体及びその熱処理調質体の強度並びに疲労
強度が低い。
Ｎｏ．４：Ｎｉ量が多過ぎる比較例であり、Ｎｉの固溶
強化によって低合金鋼粉が硬質化し、成形加工性が悪く
なるため圧粉成形体の圧密度が十分に上がらず、焼結成
形体及びその熱処理調質体の強度並びに疲労強度が低い
。
Ｎｏ．５：Ｍｏ量が不足する比較例であり、成形加工性
が良く圧密度は十分に上がるが、焼入れ性が不足するた
め焼結成形体及びその熱処理調質体の強度が十分に上が
らない。
Ｎｏ．７：Ｍｏ量が多過ぎる比較例であり、低合金鋼が
硬質化して圧粉成形体の圧密度が十分に上がらず強度不
足となる。
Ｎｏ．８ 〜１１：本発明の規定要件をすべて満たす実
施例であり、成形加工性が良く高密度の圧粉成形体が得
られると共に、成形体は焼結及び熱処理工程で焼入れ硬
化し、引張り強度の優れた焼結成形体及び熱処理調質体
が得られる。尚これらのうちＮｏ．１１はＮｉ量とＭｏ
量を比較的多目にしたものであり、このものは非調質の
焼結状態で高い引張り強度を示しており、疲労特性にも
非常に優れている。From Table 1, the following considerations can be made. No. 1: This is a comparative example in which the amount of C exceeds the specified amount, and since the low-alloy steel powder becomes hard, the formability deteriorates and the density of the powder compact does not increase, and the sintered compact and its heat-treated and tempered product deteriorate. Low tensile strength and fatigue strength. No. 2, 6: No. No. 2 is a comparative example in which the amount of Mn and the amount of O are too large. No. 6 is a comparative example in which the amount of O is too large, and the low alloy steel powder becomes hard, the compaction density of the powder compact does not increase sufficiently, and the tensile strength of the sintered compact and its heat-treated annealed body is insufficient. , fatigue strength is also low. No. 3: Comparative example where the amount of Ni is insufficient, and the low alloy steel powder is soft, has good formability, and the compaction density is sufficiently increased, but the strength and fatigue strength of the sintered compact and its heat-treated and tempered body are low. . No. 4: This is a comparative example in which the amount of Ni is too large, and the solid solution strengthening of Ni hardens the low-alloy steel powder and deteriorates the formability, so the compaction density of the powder compact does not increase sufficiently, and the sintered compact and The strength and fatigue strength of the heat treated body are low. No. 5: This is a comparative example in which the amount of Mo is insufficient, and the moldability is good and the compaction density is sufficiently increased, but the strength of the sintered compact and its heat-treated annealed body is not sufficiently increased due to insufficient hardenability. No. 7: This is a comparative example in which the amount of Mo is too large, and the low alloy steel becomes hard, and the compaction density of the powder compact does not increase sufficiently, resulting in insufficient strength. No. 8 to 11: These are examples that satisfy all the specified requirements of the present invention, and a compacted powder compact with good moldability and high density is obtained, and the compact is quenched and hardened in the sintering and heat treatment process, and has a high tensile strength. Excellent sintered compacts and heat-treated annealed bodies can be obtained. Of these, No. 11 is the amount of Ni and Mo
This material has a relatively large amount, exhibits high tensile strength in a non-thermal sintered state, and has excellent fatigue properties.
【００２３】尚Ｎｏ．１２〜１４は、合金組成は本願発
明の規定要件を満たしているが、圧密不足により成形体
密度が十分に上がっていない参考例であり、いずれも引
張り強度が低い。即ち本発明に係る低合金鋼粉の特性を
有効に発揮させるには、圧密度を６．７５ｇ／ｃｃ以上
にすることが望まれる。また図１，２は、上記表１に示
したデータを含めた多数の実験の中から、低合金鋼粉中
のＮｉ量とＭｏ量が焼結成形体及び熱処理調質体の引張
り強度に与える影響を整理して示したものである。[0023] Furthermore, No. Nos. 12 to 14 are reference examples in which the alloy composition satisfies the specified requirements of the present invention, but the density of the compact is not sufficiently increased due to insufficient compaction, and all have low tensile strength. That is, in order to effectively exhibit the characteristics of the low alloy steel powder according to the present invention, it is desirable that the compaction density be 6.75 g/cc or more. Furthermore, Figures 1 and 2 show the influence of the amount of Ni and Mo in the low-alloy steel powder on the tensile strength of the sintered compact and the heat-treated compact, based on a number of experiments including the data shown in Table 1 above. It is organized and shown.
【００２４】これらの図から明らかである様に、焼結成
形体の強度に及ぼす影響とその熱処理調質体の強度に与
える影響は若干相違するが、いずれにしてもＭｏ量が不
足する場合は、Ｎｉ添加による強度向上効果が有効に発
揮されないのに対し、適量のＭｏを添加するとＮｉ添加
による強度向上効果が顕著に発揮される様になる。As is clear from these figures, the influence on the strength of the sintered compact and the influence on the strength of the heat-treated and tempered body are slightly different, but in any case, when the amount of Mo is insufficient, While the strength-improving effect of Ni addition is not effectively exhibited, when an appropriate amount of Mo is added, the strength-improving effect of Ni addition comes to be significantly exhibited.
【００２５】しかしＭｏ量が多過ぎてもＮｉ同時添加に
よる強度向上効果はそれ以上あがらず、むしろ低下傾向
を示す様になる。また好ましいＭｏ添加量の範囲では、
Ｎｉ量を０．３ 〜２．０ ％の範囲に設定することに
よって高レベルの引張り強度が発揮される。またこれら
のグラフより、非調質の焼結体として高強度を得たい場
合はＮｉ量を多目の１．０ 〜２．０ ％に設定し、ま
た熱処理調質体として高強度を得たい場合はＮｉ量を少
なめの０．３ 〜１．０ ％の範囲に設定するのがよい
。However, even if the amount of Mo is too large, the effect of improving the strength due to the simultaneous addition of Ni does not increase any further, but rather tends to decrease. In addition, within the preferred range of Mo addition amount,
A high level of tensile strength can be achieved by setting the Ni amount in the range of 0.3 to 2.0%. Also, from these graphs, if you want to obtain high strength as a non-heat-treated sintered body, set the Ni amount to a higher value of 1.0 to 2.0%, and if you want to obtain high strength as a heat-treated and tempered body. In this case, it is preferable to set the Ni content to a relatively small range of 0.3 to 1.0%.
【００２６】[0026]
【発明の効果】本発明は以上の様に構成されており、低
合金鋼におけるＣ，Ｍｎ，Ｎｉ，Ｍｏ，Ｏの各含有量を
特定することによって、成形加工性が良好で高密度の圧
粉成形体が得られ、その後の焼結及び調質熱処理によっ
て高強度の焼結体及び熱処理調質体を与える粉末冶金用
低合金鋼粉を提供し得ることになった。Effects of the Invention The present invention is constructed as described above, and by specifying the respective contents of C, Mn, Ni, Mo, and O in low alloy steel, it is possible to obtain high-density pressurized steel with good formability. A powder compact is obtained, and by subsequent sintering and tempering heat treatment, it is possible to provide a low alloy steel powder for powder metallurgy that provides a high-strength sintered body and heat-treated tempered body.
【図１】焼結成形体の引張り強度に与えるＮｉ量とＭｏ
量の影響を示すグラフである。[Figure 1] Effect of Ni amount and Mo on tensile strength of sintered compact
It is a graph showing the influence of quantity.
【図２】熱処理調質体の引張り強度に与えるＮｉ量とＭ
ｏ量の影響を示すグラフである。[Figure 2] Effect of Ni amount and M on tensile strength of heat-treated tempered body
It is a graph showing the influence of the amount of o.
Claims (3)
０．３ ％以下、 Ｎｉ：０．３ 〜２．５ ％ Ｍｏ：０．３ 〜２．０ ％ Ｏ ：０．２ ％以下、 残部：Ｆｅ及び不可避不純物 であることを特徴とする粉末冶金用低合金鋼粉。[Claim 1] The chemical components are C: 0.05% or less (weight %: the same hereinafter), Mn:
0.3% or less, Ni: 0.3 to 2.5%, Mo: 0.3 to 2.0%, O: 0.2% or less, and the remainder: Fe and inevitable impurities. Low alloy steel powder.
なり、６．７５ｇ／ｃｃ以上の成形体密度を有すること
を特徴とする焼結成形体。2. A sintered compact made of the low alloy steel powder according to claim 1 and having a compact density of 6.75 g/cc or more.
処理したものである調質成形体。3. A heat-treated molded product obtained by heat-treating the sintered molded product according to claim 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13597691A JPH04337001A (en) | 1991-05-10 | 1991-05-10 | Low-alloy steel powder for powder metallurgy and its sintered molding and tempered molding |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13597691A JPH04337001A (en) | 1991-05-10 | 1991-05-10 | Low-alloy steel powder for powder metallurgy and its sintered molding and tempered molding |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04337001A true JPH04337001A (en) | 1992-11-25 |
Family
ID=15164277
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13597691A Pending JPH04337001A (en) | 1991-05-10 | 1991-05-10 | Low-alloy steel powder for powder metallurgy and its sintered molding and tempered molding |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04337001A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012527535A (en) * | 2009-05-22 | 2012-11-08 | ホガナス アクチボラグ （パブル） | High strength low alloy sintered steel |
| WO2014103999A1 (en) * | 2012-12-28 | 2014-07-03 | 株式会社神戸製鋼所 | Pre-alloyed steel powder for highly fatigue-resistant sintered body and carburized and quenched material |
| WO2015001894A1 (en) | 2013-07-02 | 2015-01-08 | Ntn株式会社 | Sintered mechanical component and manufacturing method therefor |
| WO2015111338A1 (en) | 2014-01-22 | 2015-07-30 | Ntn株式会社 | Sintered machine part and manufacturing method thereof |
-
1991
- 1991-05-10 JP JP13597691A patent/JPH04337001A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012527535A (en) * | 2009-05-22 | 2012-11-08 | ホガナス アクチボラグ （パブル） | High strength low alloy sintered steel |
| EP2432908A4 (en) * | 2009-05-22 | 2017-06-21 | Höganäs Ab (publ) | High strength low alloyed sintered steel |
| WO2014103999A1 (en) * | 2012-12-28 | 2014-07-03 | 株式会社神戸製鋼所 | Pre-alloyed steel powder for highly fatigue-resistant sintered body and carburized and quenched material |
| JP2014141743A (en) * | 2012-12-28 | 2014-08-07 | Kobe Steel Ltd | Pre-alloy type steel powder for high fatigue strength sintered compact sintered compact, and carburized quenching material |
| CN104884659A (en) * | 2012-12-28 | 2015-09-02 | 株式会社神户制钢所 | Pre-alloyed steel powder for highly fatigue-resistant sintered body and carburized and quenched material |
| WO2015001894A1 (en) | 2013-07-02 | 2015-01-08 | Ntn株式会社 | Sintered mechanical component and manufacturing method therefor |
| US10107376B2 (en) | 2013-07-02 | 2018-10-23 | Ntn Corporation | Sintered machine part and method of manufacturing the same |
| WO2015111338A1 (en) | 2014-01-22 | 2015-07-30 | Ntn株式会社 | Sintered machine part and manufacturing method thereof |
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