JPH10265803A - Production of ferrous powder for powder metallurgy - Google Patents
Production of ferrous powder for powder metallurgyInfo
- Publication number
- JPH10265803A JPH10265803A JP9088928A JP8892897A JPH10265803A JP H10265803 A JPH10265803 A JP H10265803A JP 9088928 A JP9088928 A JP 9088928A JP 8892897 A JP8892897 A JP 8892897A JP H10265803 A JPH10265803 A JP H10265803A
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- atmosphere
- heat treatment
- finish
- dew point
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- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Powder Metallurgy (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、水を用いた噴霧に
より製造される粉末冶金用純鉄粉の低コストでの製造方
法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-cost method for producing pure iron powder for powder metallurgy produced by spraying with water.
【０００２】[0002]
【従来の技術】一般に水アトマイズ鉄粉の製造工程は、
所定の組成の溶鋼を高圧の水で噴霧するアトマイズ工
程、乾燥工程、粒子表面の酸化皮膜を還元除去しアトマ
イズ工程による急冷組織を焼鈍軟化する仕上げ還元工
程、処理された粉末を解砕粉化する解砕工程からなる。
このうち仕上げ還元工程はアトマイズ鉄粉製造の上で最
も重要な工程であり、かつ最もコストダウンが求められ
る工程でもある。つまり工程の短縮、設備費、労務費、
用役費の削減などコストダウン効果が大きい。この仕上
げ熱処理は、移動床という連続式に移動するベルト上に
原料粉が積層され、温度および雰囲気が制御された水平
炉内を連続的に通過することで、雰囲気中の水素ないし
水蒸気と反応して脱炭、脱酸の反応が行われる。2. Description of the Related Art Generally, a process for producing water atomized iron powder is as follows.
Atomizing step of spraying molten steel of predetermined composition with high-pressure water, drying step, finishing reduction step of reducing and removing the oxide film on the particle surface and annealing and softening the quenched structure by the atomizing step, pulverizing the treated powder It consists of a crushing process.
Of these, the finish reduction step is the most important step in the production of atomized iron powder, and is also the step that requires the most cost reduction. In other words, process shortening, equipment costs, labor costs,
Great cost reduction effect such as reduction of utility costs. In this finishing heat treatment, raw material powders are stacked on a belt that moves continuously in a moving bed, and reacts with hydrogen or steam in the atmosphere by continuously passing through a horizontal furnace whose temperature and atmosphere are controlled. The reaction of decarburization and deacidification is performed.
【０００３】これらの仕上げ熱処理を効率よくおこなう
ため、従来は種々の提案がなされている。たとえば特公
昭５７−５８４０１号公報には移動床炉を用いて水蒸気
を含む水素中で脱炭、脱酸をおこなう方法が開示されて
いる。また特公昭５８−４８２号公報には移動床炉を用
いて水素中の水蒸気量を変えて脱炭、脱酸をおこなう方
法が開示されている。さらに特開昭６１−１１０７０１
号公報には連続式移動床炉内を進行方向に分割して各処
理工程を独立させて移動床上の原料粉が焼結する位置以
降で雰囲気ガスをファンで攪拌することにより、炉内の
反応生成ガスが原料粉上に滞留（よどむ）ことを防止す
ることで反応を促進する方法が開示されている。しかし
これらの方法はいずれも原料粉上の雰囲気に関するもの
であり、原料粉充填層の表面部での反応は促進される
が、原料粉充填層内部での反応はおそくなり、結果的に
は生産性は不十分なままであった。[0003] Various proposals have conventionally been made to efficiently perform these finishing heat treatments. For example, Japanese Patent Publication No. 57-58401 discloses a method of performing decarburization and deoxidation in hydrogen containing steam using a moving bed furnace. Further, Japanese Patent Publication No. 58-482 discloses a method of performing decarburization and deoxidation using a moving bed furnace while changing the amount of steam in hydrogen. Further, Japanese Patent Application Laid-Open No. 61-110701
In the publication, the inside of the continuous moving bed furnace is divided in the traveling direction, each processing step is made independent, and the atmosphere gas is agitated by a fan after the position where the raw material powder on the moving bed sinters. There is disclosed a method of accelerating the reaction by preventing generated gas from staying (stagnating) on raw material powder. However, all of these methods relate to the atmosphere on the raw material powder, and the reaction on the surface of the raw material powder packed layer is promoted, but the reaction inside the raw material powder packed layer is slow, resulting in production. Sex remained poor.
【０００４】[0004]
【発明が解決しようとする課題】本発明は、以上述べた
ような従来技術の欠点に鑑み、鉄粉の仕上げ還元工程に
おいて反応を促進させることでコストダウンを図り、安
価な粉末冶金用水アトマイズ鉄粉を製造する技術を提供
することにある。SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the prior art, the present invention aims to reduce the cost by promoting the reaction in the finishing reduction step of iron powder, and to reduce the cost of water atomized iron for powder metallurgy. It is to provide a technique for producing powder.
【０００５】[0005]
【課題を解決するための手段】以上の課題を解決するた
め、本発明者らは鋭意研究をおこなった。その結果、従
来、軟化焼鈍・還元工程がおこなわれていた理由は、水
アトマイズされ乾燥後・軟化焼鈍工程前の状態の生鉄粉
は硬度が高く、そのままでは圧縮性が低下し粉末冶金用
としては使用に耐えないので、焼鈍により水アトマイズ
されたときに生じる焼き入れ組織を軟化することにあっ
た。鉄粉の断面硬度と圧縮性の関係を調査すると、鉄粉
断面硬度が低下してくると圧縮性が向上してくる相関関
係がある。この鉄粉断面硬度は、鉄粉中のＣ量を低下さ
せることで低減してくる。すなわちアトマイズ生鉄粉中
のＣ量を低減させることで、仕上げ工程時の負荷を低減
させることができる。Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies. As a result, conventionally, the softening annealing / reducing process has been performed because the raw iron powder in the state after water atomization and drying / before the softening annealing process has high hardness, and as it is, its compressibility is reduced and it is used for powder metallurgy. Is not suitable for use, and softens the quenched structure generated when water is atomized by annealing. Examining the relationship between the cross-sectional hardness and the compressibility of the iron powder, there is a correlation that as the cross-sectional hardness of the iron powder decreases, the compressibility improves. The iron powder cross section hardness is reduced by reducing the amount of C in the iron powder. That is, by reducing the amount of C in the atomized raw iron powder, it is possible to reduce the load during the finishing step.
【０００６】さらに粉末中の酸素はＦｅＯの形態で粉末
表面に皮膜を形成しており、この皮膜があると鉄粉内部
のＣが雰囲気と反応して除去される反応の障害となる。
本発明は以上の知見に基づいてなされたものである。[0006] Further, oxygen in the powder forms a film on the powder surface in the form of FeO, and if this film is present, C in the iron powder reacts with the atmosphere and becomes an obstacle to the reaction of being removed.
The present invention has been made based on the above findings.
【０００７】すなわち本発明は、Ｃ≦０．０７ｗｔ％を
含む溶鋼を水アトマイズにより噴霧し、該粉末を非酸化
性雰囲気にて１００〜３００℃で乾燥処理した後、該粉
末を露点２５〜４５℃のＨ2 還元性雰囲気で仕上げ還元
熱処理することを特徴とする鉄系粉末の製造方法であ
る。また上記乾燥処理の雰囲気がＡｒ、Ｎ2 、Ｈ2 、ま
たはこれらの混合物または真空中のいずれかである請求
項１記載の鉄系粉末の製造方法である。ここで、乾燥処
理の雰囲気が、露点２５〜４５℃のＨ2 還元性雰囲気で
あってもよい。That is, according to the present invention, molten steel containing C ≦ 0.07 wt% is sprayed by water atomization, the powder is dried at 100 to 300 ° C. in a non-oxidizing atmosphere, and then the powder is dew point 25 to 45. A method for producing an iron-based powder, which comprises performing a finish reduction heat treatment in a H 2 reducing atmosphere at a temperature of ℃. 2. The method for producing an iron-based powder according to claim 1, wherein the atmosphere of the drying treatment is any of Ar, N 2 , H 2 , a mixture thereof, or a vacuum. Here, the atmosphere of the drying treatment may be an H 2 reducing atmosphere having a dew point of 25 to 45 ° C.
【０００８】[0008]
【作用】以下に本発明の実施の形態について述べる。ま
ず溶鋼中のＣ量については、０．０７ｗｔ％以下に低下
させるとアトマイズ生粉の断面硬さが減少し、仕上げ処
理時の焼鈍負荷が低減されるが、これを越えると断面硬
さは急速に増加してくる。よって溶鋼中のＣ量は０．０
７ｗｔ％以下とした。An embodiment of the present invention will be described below. First, when the C content in the molten steel is reduced to 0.07 wt% or less, the sectional hardness of the atomized raw powder decreases, and the annealing load at the time of finishing treatment is reduced. To increase. Therefore, the C content in molten steel is 0.0
7 wt% or less.
【０００９】粉末を非酸化性雰囲気、好ましくは、Ａ
ｒ、Ｎ2 、Ｈ2 、またはこれらの混合雰囲気、または真
空中で乾燥するのは、アトマイズ鉄粉の酸素が最も増加
するのが乾燥時であり、ここの雰囲気を非酸化性雰囲気
とすることで粉末中の酸素量の上昇を抑えるためであ
る。The powder is placed in a non-oxidizing atmosphere, preferably A
Drying in the atmosphere of r, N 2 , H 2 , or a mixture of these, or in a vacuum is performed when the atomized iron powder has the greatest increase in oxygen, and the atmosphere here should be a non-oxidizing atmosphere. This is to suppress an increase in the amount of oxygen in the powder.
【００１０】乾燥温度を１００〜３００℃としたのは、
この温度未満では乾燥効果が上がらないためであり、３
００℃を越えると粉末が不必要に凝集してしまい、かえ
って仕上げ時の反応が遅くなるためである。乾燥後のＯ
量は好ましくは０．４ｗｔ％以下、さらには０．３ｗｔ
％以下とする。The reason for setting the drying temperature to 100 to 300 ° C. is as follows.
If the temperature is lower than this, the drying effect does not increase.
If the temperature exceeds 00 ° C., the powder is unnecessarily agglomerated, and the reaction at the time of finishing is rather slowed down. O after drying
The amount is preferably 0.4 wt% or less, more preferably 0.3 wt%
% Or less.
【００１１】また、仕上げ還元熱処理におけるＨ2 還元
雰囲気（純Ｈ2 雰囲気又はＨ2 とＡｒもしくはＮ2 の混
合ガスでもよい）の露点は２０〜４５℃とする。露点が
４５℃を越えると鉄粉中酸素量が逆に増加して粉末が硬
くなり、圧縮性が低下してくる。仕上げ還元熱処理の還
元温度は８００〜１１００℃が好ましい。８００℃未満
では脱炭、脱酸が不十分となるので好ましくなく、１１
００℃を越えると粉末同士が拡散によって強固に焼結凝
集してしまうので好ましくない。また露点が２０℃未満
では脱炭の進行が遅いので、さけるべきである。仕上げ
還元時間は好ましくは６０〜１８０分、より好ましくは
３０〜９０分とする。The dew point of the H 2 reducing atmosphere (may be a pure H 2 atmosphere or a mixed gas of H 2 and Ar or N 2 ) in the finish reduction heat treatment is set to 20 to 45 ° C. If the dew point exceeds 45 ° C., the amount of oxygen in the iron powder increases conversely, the powder becomes hard and the compressibility decreases. The reduction temperature of the finish reduction heat treatment is preferably from 800 to 1100 ° C. If the temperature is lower than 800 ° C., the decarburization and deoxidation become insufficient.
If the temperature exceeds 00 ° C., the powders are undesirably strongly sintered and aggregated by diffusion. If the dew point is lower than 20 ° C., the progress of decarburization is slow and should be avoided. The finish reduction time is preferably from 60 to 180 minutes, more preferably from 30 to 90 minutes.
【００１２】[0012]
【実施例】以下、実施例によって本発明を詳細に説明す
る。 （１）まず溶鋼中のＣ量を変化させた場合について検討
した。高周波溶解炉で電解鉄を溶解し所定量になるよう
にＣ量を調整した後に水アトマイズした。これらの生粉
を非酸化性のＮ2 雰囲気で１５０℃で３００分乾燥し
た。乾燥した後生粉段階でＣ，Ｏ量の測定および樹脂に
埋め込み研磨して断面を露出させてマイクロビッカース
で断面硬さを測定した。これらの乾燥した生粉をＨ2 中
（露点２５℃）で仕上げ熱処理した。温度は９５０℃に
０〜６０分間保持した後に冷却して、粉末のＣ，Ｏ量を
測定し、粉末の断面硬さを測定し、その減少の変化を追
跡した。The present invention will be described below in detail with reference to examples. (1) First, the case where the amount of C in molten steel was changed was examined. Electrolytic iron was melted in a high-frequency melting furnace to adjust the amount of C to a predetermined amount, followed by water atomization. These raw powders were dried at 150 ° C. for 300 minutes in a non-oxidizing N 2 atmosphere. After drying, at the raw powder stage, the amounts of C and O were measured and embedded in resin and polished to expose the cross section, and the cross section hardness was measured with a micro Vickers. These dried green flours were finish heat treated in H 2 (dew point 25 ° C.). The temperature was maintained at 950 ° C. for 0 to 60 minutes and then cooled, the C and O contents of the powder were measured, the cross-sectional hardness of the powder was measured, and the change in the decrease was tracked.
【００１３】仕上熱処理前の生粉のＣ，Ｏ量および断面
硬さを表１に示す。Ｃ量の低下に従って粉末の硬さは低
く抑制されてきている。またこれらの粉末を仕上げ熱処
理（露点２５℃Ｈ2 中）９５０℃に各時間保持させた際
の鉄粉中Ｃ量変化を図１に硬さ変化を図２に示す。アト
マイズ生粉段階でＣ量の低い粉末（実施例１〜３）は、
Ｃ量の高い粉末（比較例１〜３）より、脱炭および硬さ
低減に要する時間は大幅に低減できている。Table 1 shows the C and O contents and the cross-sectional hardness of the raw powder before the finish heat treatment. As the amount of C decreases, the hardness of the powder has been suppressed to a low level. FIG. 1 shows the change in the amount of C in the iron powder and FIG. 2 shows the change in hardness when these powders were held at 950 ° C. for each hour at a finish heat treatment (in a dew point of 25 ° C. in H 2 ). Powders with low C content at the atomized raw powder stage (Examples 1-3)
The time required for decarburization and hardness reduction can be significantly reduced from the powder having a high C content (Comparative Examples 1 to 3).
【００１４】 [0014]
【００１５】（２）ここでは、粉末の酸素量の影響につ
いて述べる。（１）の実施例３の乾燥前の湿粉末を用い
て、乾燥雰囲気中に空気を導入して、種々の酸素量のア
トマイズ生粉を製造した。この粉末を（１）と同じよう
にして仕上げ還元処理をおこなった。そして（１）と同
じ要領で鉄粉中Ｃ，Ｏ量および硬さの変化を測定した。
表２に乾燥処理後の粉末の酸素量を示す。これらの粉末
を９５０℃に各時間保持させた際の鉄粉中Ｃ量変化を図
３に酸素量変化を図４に硬さ変化を図５に示す。仕上げ
還元処理前の鉄粉中の酸素量が増加すると仕上げ還元処
理での脱炭の開始が遅れ、硬さ低減が遅れてくる。当然
脱酸は遅くなってくる。(2) Here, the influence of the amount of oxygen in the powder will be described. Using the wet powder before drying of Example 3 of (1), air was introduced into a dry atmosphere to produce atomized raw powder having various oxygen contents. This powder was subjected to a finish reduction treatment in the same manner as in (1). Then, the changes in the C and O contents and hardness in the iron powder were measured in the same manner as in (1).
Table 2 shows the oxygen content of the powder after the drying treatment. FIG. 3 shows changes in the amount of C in iron powder, FIG. 4 shows changes in the amount of oxygen, and FIG. 5 shows changes in hardness when these powders were held at 950 ° C. for each hour. When the amount of oxygen in the iron powder before the finish reduction treatment increases, the start of decarburization in the finish reduction treatment is delayed, and the hardness reduction is delayed. Naturally, deacidification is slow.
【００１６】 [0016]
【００１７】（３）ここでは雰囲気の露点の影響につい
て調べた。実施例３で使用したものと同じ生粉を使用し
て、露点を変えた実験をおこなった。露点以外の実験要
領は（１）と同じにした。表３に９５０℃で１００分間
保持した仕上げ後の粉末のＣ，Ｏ量および硬さを示す。
露点が低くなる（比較例７）と脱炭は不完全になる。一
方、露点が高く脱炭が高く（比較例８）なると、粉末の
脱酸が進行しなくなる。これは雰囲気中に水蒸気が多く
なると、粉末が再酸化するためである。(3) Here, the influence of the dew point of the atmosphere was examined. An experiment was carried out using the same raw powder used in Example 3 and changing the dew point. The experimental procedure other than the dew point was the same as in (1). Table 3 shows the C, O content and hardness of the finished powder held at 950 ° C. for 100 minutes.
When the dew point becomes low (Comparative Example 7), decarburization becomes incomplete. On the other hand, when the dew point is high and the decarburization is high (Comparative Example 8), deoxidation of the powder does not proceed. This is because the powder is reoxidized when the amount of water vapor increases in the atmosphere.
【００１８】 [0018]
【００１９】（４）ここでは実際に連続式移動床炉で実
験をおこなった。実施例１〜３および比較例１〜６の粉
末を使用した。熱処理炉の炉温は９５０℃に設定した。
炉内の雰囲気は露点２５℃に調整したＨ2 を使用した。
仕上げ熱処理後の各粉末のＣ量、Ｏ量、硬さおよび通炉
量をまとめて表４に示す。ここでいう通炉量とは、仕上
げ粉の特性が（Ｃ≦０．００４ｗｔ％）、（０≦０．２
５ｗｔ％）の適正を保ち得る限界の処理量（ｔ／ｈ）の
ことである。本発明になる粉末では比較例の場合に比べ
て生産性が約１．６倍に向上している。(4) Here, an experiment was actually performed in a continuous moving bed furnace. The powders of Examples 1 to 3 and Comparative Examples 1 to 6 were used. The furnace temperature of the heat treatment furnace was set to 950 ° C.
The atmosphere in the furnace was H 2 adjusted to a dew point of 25 ° C.
Table 4 shows the C content, the O content, the hardness, and the passage capacity of each powder after the finish heat treatment. The amount of furnace passing here means that the properties of the finished powder are (C ≦ 0.004 wt%), (0 ≦ 0.2
(5 wt%), which is the limit of the throughput (t / h) that can maintain the appropriateness. The productivity of the powder according to the present invention is about 1.6 times higher than that of the comparative example.
【００２０】 [0020]
【００２１】[0021]
【発明の効果】本発明の製造方法を用いることによっ
て、鉄系粉末の製造において、大幅に反応性を促進し、
生産性が向上する。According to the production method of the present invention, the reactivity is greatly promoted in the production of iron-based powder,
Productivity is improved.
【図１】 仕上げ還元熱処理における鉄粉中のＣ量変化
を示すグラフである。FIG. 1 is a graph showing a change in the amount of C in iron powder in a finish reduction heat treatment.
【図２】 仕上げ還元熱処理における鉄粉の硬度変化を
示すグラフである。FIG. 2 is a graph showing a change in hardness of iron powder in a finish reduction heat treatment.
【図３】 仕上げ還元熱処理における鉄粉中のＣ量変化
を示すグラフである。FIG. 3 is a graph showing a change in the amount of C in iron powder in a finish reduction heat treatment.
【図４】 仕上げ還元熱処理における鉄粉中のＯ量変化
を示すグラフである。FIG. 4 is a graph showing a change in the amount of O in iron powder in a finish reduction heat treatment.
【図５】 仕上げ還元熱処理における鉄粉の硬度変化を
示すグラフである。FIG. 5 is a graph showing a change in hardness of iron powder in a finish reduction heat treatment.
Claims (2)
イズにより噴霧し、該粉末を非酸化性雰囲気にて１００
〜３００℃で乾燥処理した後、該粉末を露点２５〜４５
℃のＨ2 還元性雰囲気で仕上げ還元熱処理することを特
徴とする鉄系粉末の製造方法。1. A molten steel containing C ≦ 0.07 wt% is sprayed by water atomization, and the powder is sprayed in a non-oxidizing atmosphere at 100 ° C.
After drying at ~ 300 ° C, the powder is dew point 25-45.
A method for producing an iron-based powder, which comprises performing a finish reduction heat treatment in a H 2 reducing atmosphere at a temperature of ° C.
たはこれらの混合物、または真空中のいずれかである請
求項１記載の鉄系粉末の製造方法。2. The method for producing an iron-based powder according to claim 1, wherein the atmosphere of the drying treatment is any of Ar, N 2 , H 2 , a mixture thereof, or a vacuum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9088928A JPH10265803A (en) | 1997-03-24 | 1997-03-24 | Production of ferrous powder for powder metallurgy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9088928A JPH10265803A (en) | 1997-03-24 | 1997-03-24 | Production of ferrous powder for powder metallurgy |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10265803A true JPH10265803A (en) | 1998-10-06 |
Family
ID=13956575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9088928A Withdrawn JPH10265803A (en) | 1997-03-24 | 1997-03-24 | Production of ferrous powder for powder metallurgy |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10265803A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101966591A (en) * | 2010-09-09 | 2011-02-09 | 东北大学 | Single-step operating production method of high-nitrogen stainless steel powder |
| KR101041888B1 (en) | 2008-09-08 | 2011-06-15 | 국방과학연구소 | A method of preparation of powdered iron for heating material in thermal battery using spray pyrolysis |
-
1997
- 1997-03-24 JP JP9088928A patent/JPH10265803A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101041888B1 (en) | 2008-09-08 | 2011-06-15 | 국방과학연구소 | A method of preparation of powdered iron for heating material in thermal battery using spray pyrolysis |
| CN101966591A (en) * | 2010-09-09 | 2011-02-09 | 东北大学 | Single-step operating production method of high-nitrogen stainless steel powder |
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| A300 | Application deemed to be withdrawn because no request for examination was validly filed |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20040601 |