JPH0477041B2 - - Google Patents
Info
- Publication number
- JPH0477041B2 JPH0477041B2 JP58214889A JP21488983A JPH0477041B2 JP H0477041 B2 JPH0477041 B2 JP H0477041B2 JP 58214889 A JP58214889 A JP 58214889A JP 21488983 A JP21488983 A JP 21488983A JP H0477041 B2 JPH0477041 B2 JP H0477041B2
- Authority
- JP
- Japan
- Prior art keywords
- iron powder
- reduction
- powder
- annealing treatment
- iron
- 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.)
- Expired
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 97
- 238000000137 annealing Methods 0.000 claims description 25
- 238000005507 spraying Methods 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 13
- 239000001301 oxygen Substances 0.000 claims description 13
- 229910052760 oxygen Inorganic materials 0.000 claims description 13
- 238000004663 powder metallurgy Methods 0.000 claims description 11
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 10
- 239000001257 hydrogen Substances 0.000 claims description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 238000000034 method Methods 0.000 description 18
- 239000000843 powder Substances 0.000 description 16
- 239000002245 particle Substances 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- 239000007921 spray Substances 0.000 description 8
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 238000005452 bending Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 238000005056 compaction Methods 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 1
Landscapes
- Powder Metallurgy (AREA)
Description
イ 産業上の利用分野
本考案は、粉末治金用高成形性鉄粉に関し、詳
しくは、噴霧法で製造された鉄粉表面を覆つてい
るフイルム状の酸化物を、涙状形態となして鉄粉
表面上に付着させるとともに、還元・焼鈍処理後
の酸素含有量を水素還元減量にして、重量比率で
1.0％以下とすることにより、成形性を改良した
粉末治金用高成形性鉄粉にかかる。
ロ 従来技術
粉末治金に使用する鉄粉は、還元法と噴霧法の
２種類に大別される。
前者の還元法は、微分に粉砕された鉄鉱石や、
鋼板の熱間圧延時に発生するミルスケール等を、
還元して鉄粉を製造する方法であるが、還元費用
が高くつくため、近年は、後者の噴霧法による鉄
粉の生産が、次第に増加する傾向にある。
以下、噴霧法の説明は、その主流をなす水噴霧
法に例をとつて、具体的に述べる。
水噴霧法により鉄粉の製造は、鋼板等の鉄スク
ラツプを、誘導炉やアーク炉で溶解し、この溶湯
を取鍋等により、底部に孔径φ5〜φ20mmの孔を有
するタンデイツシユに溶湯を主湯して、タンデイ
ツシユ底部に設けられた孔から、溶湯を自然流下
させ、この自然流下する溶湯に、通常、50〜150
Kg／cm2の高圧水を噴きつけて溶湯を粉化させ、鉄
粉とする（噴霧工程）。
つぎに、脱水・乾燥後、噴霧工程で鉄粉の表面
にフイルム上に形成された酸化皮膜を、つぎの還
元・焼鈍処理で除去する。
鉄粉の還元・焼鈍処理は、通常800〜1100℃の
アンモニア分解ガス中で行われる。
なお、還元・焼鈍処理された鉄粉は、部分的に
焼結されてケーキ状となるため、このケーキ状の
鉄粉を解砕し、所望の鉄粉とするものである。
しかし、このようにして水噴霧法で製造された
鉄粉には、前述の還元鉄粉に比較して、以下のよ
うな欠点がある。
すなわち、鉄粉の表面形状が、第１図ｂに示す
ように、第１図ａに示すような還元鉄粉に比較し
て、表面凹凸の少ない形状をしていることから、
この水噴霧法で製造した鉄粉を、金型内で圧粉成
形する場合において、鉄粉同士のからみ合いが少
なく、圧粉成形体の強度が低く、いいかえると、
水噴霧法で製造した鉄粉は、成形性が悪いという
欠点がある。
ハ 発明の目的
本発明は、噴霧法で製造した鉄粉に付着した、
酸化物形態を改善するとともに、鉄粉の酸素含有
量を低減させることにより、粉末治金用鉄粉の成
形性を改良した、粉末治金用高成形性鉄粉を提供
することを目的としている。
ニ 発明の構成
このような目的は、本発明によれば、噴霧法で
製造された、粉末治金用高成形性鉄粉であつて、
噴霧後、還元・焼鈍処理前の酸素含有量を水素
還元減量にして、重量比率で0.20％以上の鉄粉を
800〜1100℃の高温で、窒素ガス・アルゴン等の
不活性ガス雰囲気中にて還元・焼鈍処理し、鉄粉
表面を覆つているフイルム状の酸化皮膜を、涙状
形態となして鉄粉表面上に付着させるとともに、
還元・焼鈍処理後の酸素含有量を水素還元減量に
して、重量比率で1.0％以下となしたことを特徴
とする。粉末治金用高成形性鉄粉によつて達成さ
れる。
ホ 発明の作用
以下、本発明の作用を説明する。
本発明において、還元・焼鈍処理前の酸素含有
量を水素還元減量にして、重量比率が0.20％以上
としたのは、乾燥前、すなわち、還元・焼鈍処理
前の鉄粉の表面は、フイルム状の鉄酸化皮膜によ
り覆われているが、還元・焼鈍処理において高温
となるため、フイルム状の鉄酸化皮膜に粘性が生
じ、表面張力により涙状形態となるが、0.20％未
満では、鉄酸化皮膜が薄く、還元・焼鈍処理での
涙状形態酸化物が形成されないか、形成されても
極く僅かであるため、圧粉成形体の強度、いいか
えると、鉄粉の成形性が十分に改善されないから
である。
また、還元・焼鈍処理温度を800〜1100℃とし
たのは、800℃未満では、焼鈍効果が不十分であ
り、鉄粉自体の硬さが高くなつて圧縮性が悪く、
圧粉成形時に成形圧力を高くしないと、圧粉成形
体の密度が上昇せず、成形金型の寿命が短くなる
からである。
さらに、鉄粉に含有されている炭素の、脱炭反
応が十分に進行せず、還元・焼鈍処理後の鉄粉に
炭素が残り、鉄粉自体の硬さが高く、圧縮性が悪
くなる欠点がある。
一方、1100℃を越えると、還元・焼鈍処理で鉄
粉同士が強固に焼結され、後の解砕工程でケーキ
状鉄粉の解砕が事実上不可能となる。
つぎに、還元・焼鈍処理後の酸素含有量を水素
還元減量にして、重量比率で1.0％以下とした理
由を説明する。
焼結部品は、通常、原材料となる鉄粉は、強度
向上のための、銅粉、黒鉛粉等を添加・混合し、
圧粉成形ご、還元性雰囲気中で焼結するが、この
焼結工程で添加した黒鉛粉が、鉄粉中の酸素によ
り、
Ｃ＋１／2O2→CO↑
の反応が進行して脱炭されるため、強度が十分向
上しないという欠点がある。
この欠点を解消するため、脱炭される分だけ、
黒鉛を余分に添加しておけばよいが、現在の技術
水準では、水噴霧法で製造した鉄粉の酸素量が水
素還元減量にして1.0％以上になるとバラツキや
すいため、添加した黒鉛の脱炭量にもバラツキを
生じ、その結果として、機械的特性がバラツクた
め、水噴霧法で製造した鉄粉の、還元・焼鈍処理
後の酸素含有量を水素還元減量にして、重量比率
で1.0％以下とした。
つぎに、本発明鉄粉が粉末成形性に優れている
理由について、発明者らが研究した結果をもとに
以下に説明する。
本発明鉄粉は、圧粉成形前においては、第２図
ａに示すような分散した鉄粉粒１状態にあるが、
圧粉成形時になると、第２図ｂに示すように、鉄
粉粒１が移動し、軟らかい鉄粉粒１は塑性変形さ
れ、比較的硬い涙状形態の酸化物２が、鉄粉粒１
の移動や塑性変形に伴つて、鉄粉粒１の表面を引
掻くことになる。
この結果、鉄粉粒１の表面の引つ掻き痕３に
は、極めて活性化した新生面が形成され、鉄粉粒
１の新生面同士が接触、拡散し、鉄粉粒１の間
に、涙状形態の酸化物２が″くさび″のように喰い
込んで、鉄粉粒１同士の結合が強固となり、本発
明鉄粉の粉末成形性が著しく改善されるものと思
われる。
また、第３図は、本発明鉄粉を用いた圧粉成形
体の曲げ破断面の走査型電子顕微鏡観察写真であ
るが、明らかに涙状形態の酸化物２が、鉄粉粒１
の表面を引掻いた痕が認められ、本発明鉄粉にお
ける涙状形態の酸化物２の、成形性改善効果が確
認された。
ヘ 実施例
以下、添付図面に基づいて、本発明の実施例を
説明する。
なお、この実施例においては、水噴霧法を例と
して具体的に説明する。
軟鋼板スクラツプを高周波誘導炉で溶解した、
1600℃の溶湯を、底部に直径13mmの孔を有するタ
ンデイツシユに注湯して、タンデツシユ底部に設
けられた孔から、溶湯を自然流下させ、この自然
流下する溶湯に、水噴射ノズルから噴射された
150m／secという高速度の水を噴きつけて、溶湯
を粉化させ、鉄粉とした。
なお、噴霧は、鉄粉の酸化を抑制するため、窒
素ガス雰囲気中で行つた。
ついで、水噴霧により製造された鉄粉を、脱水
処理後、80〜120度で乾燥させた。
なお、乾燥後、すなわち、還元・焼鈍処理前に
おける酸素含有量は水素還元減量にして、重量比
率で0.45％であつた。また、炭素含有量は、0.25
％であつた。
つぎに、窒素ガス雰囲気中で、900℃×30分の
還元・焼鈍処理をした。
なお、窒素ガス雰囲気では、雰囲気による還元
は不可能であるが、鉄粉中に含有されている炭素
により、自己還元されることから「還元・焼鈍処
理」とした。
この還元・焼鈍処理により形成されたケーキ状
の鉄粉を、解砕し80メツシユの篩にかけて、第１
表ａおよび第１表ｂに示すような特性の鉄粉を製
造した。
B. Field of Industrial Application The present invention relates to highly formable iron powder for powder metallurgy, and more specifically, the present invention relates to highly formable iron powder for powder metallurgy. In addition to adhering to the surface of iron powder, the oxygen content after reduction and annealing treatment is reduced by hydrogen reduction, and the weight ratio is reduced.
By controlling the content to 1.0% or less, it is possible to obtain highly formable iron powder for powder metallurgy with improved formability. B. Prior Art Iron powder used in powder metallurgy is roughly divided into two types: reduction method and spray method. The former reduction method uses finely crushed iron ore,
Mill scale, etc. generated during hot rolling of steel plates,
This is a method of producing iron powder by reduction, but the cost of reduction is high, so in recent years, the production of iron powder by the latter spraying method has been gradually increasing. Hereinafter, the spraying method will be specifically explained using an example of the water spraying method, which is the mainstream method. To produce iron powder using the water spray method, iron scrap such as steel plates is melted in an induction furnace or arc furnace, and the molten metal is poured into a tundish with a hole with a diameter of 5 to 20 mm at the bottom using a ladle, etc. Then, the molten metal is allowed to flow down by gravity through the hole provided at the bottom of the tundish.
The molten metal is pulverized by spraying high-pressure water at kg/cm 2 and turned into iron powder (spraying process). Next, after dehydration and drying, the oxide film formed on the surface of the iron powder on the film during the spraying process is removed by the next reduction and annealing treatment. Reduction and annealing of iron powder is usually performed in ammonia decomposition gas at 800 to 1100°C. Note that the reduced and annealed iron powder is partially sintered into a cake-like shape, so this cake-like iron powder is crushed to obtain the desired iron powder. However, the iron powder produced by the water spray method in this way has the following drawbacks compared to the above-mentioned reduced iron powder. That is, since the surface shape of the iron powder, as shown in FIG. 1b, has a shape with fewer surface irregularities compared to the reduced iron powder as shown in FIG. 1a,
When iron powder produced by this water spray method is compacted in a mold, there is little entanglement between the iron powders and the strength of the compact is low; in other words,
Iron powder produced by the water spray method has the disadvantage of poor formability. C. Purpose of the invention The present invention provides for
The purpose of the present invention is to provide highly formable iron powder for powder metallurgy, which has improved formability by improving the oxide morphology and reducing the oxygen content of the iron powder. . D. Structure of the Invention According to the present invention, the present invention provides highly formable iron powder for powder metallurgy produced by a spraying method, and after spraying, the oxygen content before reduction and annealing treatment is reduced to hydrogen. Iron powder with a reduction weight of 0.20% or more by weight
Reduction and annealing treatment is carried out at high temperatures of 800 to 1100℃ in an inert gas atmosphere such as nitrogen gas or argon, and the film-like oxide film covering the surface of the iron powder is formed into a tear-like shape. At the same time as attaching it to the top,
It is characterized in that the oxygen content after reduction and annealing treatment is reduced by hydrogen reduction to a weight ratio of 1.0% or less. This is achieved by using highly formable iron powder for powder metallurgy. E. Effects of the Invention The effects of the present invention will be explained below. In the present invention, the oxygen content before reduction and annealing treatment is reduced by hydrogen reduction and the weight ratio is set to 0.20% or more because the surface of the iron powder before drying, that is, before reduction and annealing treatment, is However, due to the high temperatures during reduction and annealing, the film-like iron oxide film becomes viscous and takes on a tear-like shape due to surface tension. is thin, and tear-shaped oxides are not formed during reduction and annealing treatment, or even if they are formed, they are very small, so the strength of the compacted compact, or in other words, the formability of the iron powder, is not sufficiently improved. It is from. In addition, the reduction/annealing temperature was set at 800 to 1100°C because at temperatures below 800°C, the annealing effect is insufficient and the hardness of the iron powder itself increases, resulting in poor compressibility.
This is because if the compacting pressure is not increased during powder compacting, the density of the powder compact will not increase and the life of the molding die will be shortened. Furthermore, the decarburization reaction of the carbon contained in the iron powder does not proceed sufficiently, and carbon remains in the iron powder after reduction and annealing, resulting in high hardness of the iron powder itself and poor compressibility. There is. On the other hand, if the temperature exceeds 1100°C, the iron powder will be strongly sintered together during the reduction and annealing treatment, making it virtually impossible to crush the cake-like iron powder in the subsequent crushing process. Next, the reason why the oxygen content after the reduction/annealing treatment is reduced by hydrogen reduction and is set to 1.0% or less in terms of weight ratio will be explained. For sintered parts, the raw material, iron powder, is usually mixed with copper powder, graphite powder, etc. to improve strength.
During powder compaction, it is sintered in a reducing atmosphere, and the graphite powder added in this sintering process is decarburized by the reaction of C+1/2O 2 →CO↑ due to the oxygen in the iron powder. Therefore, there is a drawback that the strength is not sufficiently improved. In order to eliminate this drawback, the amount that is decarburized is
It is possible to add extra graphite, but with the current state of the art, the amount of oxygen in iron powder produced by the water spray method tends to vary if it becomes 1.0% or more in terms of hydrogen reduction loss, so it is necessary to decarburize the added graphite. As a result, the mechanical properties vary, so the oxygen content of iron powder produced by the water spray method after reduction and annealing treatment is reduced by hydrogen reduction to 1.0% or less by weight. And so. Next, the reason why the iron powder of the present invention has excellent powder formability will be explained below based on the results of research conducted by the inventors. Before the iron powder of the present invention is compacted, it is in the state of dispersed iron powder particles as shown in FIG. 2a.
During powder compaction, as shown in FIG. 2b, the iron powder particles 1 move, the soft iron powder particles 1 are plastically deformed, and the relatively hard tear-shaped oxides 2 are transferred to the iron powder particles 1.
As the particles move and plastically deform, the surface of the iron powder particles 1 will be scratched. As a result, extremely activated new surfaces are formed in the scratch marks 3 on the surface of the iron powder grains 1, and the new surfaces of the iron powder grains 1 come into contact with each other and spread, causing tear-like formations between the iron powder grains 1. It is thought that the oxides 2 in the form of oxides 2 bite into each other like a "wedge", thereby strengthening the bond between the iron powder particles 1, thereby significantly improving the powder formability of the iron powder of the present invention. Furthermore, FIG. 3 is a scanning electron microscope photograph of the bending fracture surface of the compacted compact using the iron powder of the present invention, and it is clear that the tear-shaped oxide 2 is found in the iron powder particles 1.
Scratch marks were observed on the surface of the iron powder, confirming the formability improving effect of the tear-shaped oxide 2 in the iron powder of the present invention. F. Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In this example, a water spray method will be specifically explained as an example. Mild steel plate scrap is melted in a high frequency induction furnace.
Molten metal at 1,600°C was poured into a tundish with a hole of 13 mm in diameter at the bottom, and the molten metal was allowed to flow down naturally through the hole at the bottom of the tundish.
The molten metal was pulverized into iron powder by spraying water at a high speed of 150 m/sec. Note that the spraying was performed in a nitrogen gas atmosphere in order to suppress oxidation of the iron powder. The iron powder produced by water spraying was then dehydrated and dried at 80 to 120 degrees. Note that the oxygen content after drying, that is, before the reduction/annealing treatment, was 0.45% by weight in terms of hydrogen reduction loss. Also, the carbon content is 0.25
It was %. Next, reduction and annealing treatment was performed at 900°C for 30 minutes in a nitrogen gas atmosphere. Note that in a nitrogen gas atmosphere, atmospheric reduction is not possible, but self-reduction occurs due to the carbon contained in the iron powder, so it is referred to as a "reduction/annealing treatment." The cake-like iron powder formed by this reduction and annealing treatment is crushed and passed through an 80 mesh sieve.
Iron powder having the characteristics shown in Tables a and 1b was produced.
【表】【table】
【表】
なお、第１表ａおよび第１表ｂには、比較材と
して、従来の鉄粉である。還元、焼鈍処理を、ア
ンモニア分解ガス中で、900℃×30分とした鉄粉
の特性を併せ示している。
また、従来の還元鉄粉と噴霧鉄粉の表面状況
を、それぞれ、第１図ａと第１図ｂに示している
が、これらと比較して、第４図から明らかなよう
に、本発明鉄粉の表面には、涙状形態の酸化物が
付着していることが理解される。
つぎに、本発明鉄粉、従来の水噴霧鉄粉、従来
の鉄鉱石の還元鉄粉に、それぞれ、潤滑剤である
ステアリン酸亜鉛を、1.0重量％添加・混合し、
圧粉成形体の密度が、いずれも、7.0g／cm3となる
ように圧粉成形し、この圧粉成形体を曲げ試験し
た。
曲げ試験結果を第２表に示す。[Table] Note that Tables 1a and 1b use conventional iron powder as a comparative material. It also shows the characteristics of iron powder that was reduced and annealed in ammonia decomposition gas at 900°C for 30 minutes. Furthermore, the surface conditions of conventional reduced iron powder and sprayed iron powder are shown in FIG. 1a and FIG. 1b, respectively, and compared with these, as is clear from FIG. It is understood that tear-shaped oxides are attached to the surface of the iron powder. Next, 1.0% by weight of zinc stearate as a lubricant was added to and mixed with the iron powder of the present invention, the conventional water-sprayed iron powder, and the conventional reduced iron powder of iron ore, respectively.
Each powder compact was compacted so that its density was 7.0 g/cm 3 , and the compact was subjected to a bending test. The bending test results are shown in Table 2.
【表】
第２表から明らかなように、本発明鉄粉を使用
した圧粉成形体の曲げ強度は、従来の水噴霧鉄
粉、鉄鉱石の還元鉄粉を使用した圧粉成形体の曲
げ強度に比較して、高い値を示し、焼結部品の製
造において、しばしば問題となる、圧粉成形時の
クラツク発生、また、圧粉成形体のハンドリング
時における欠けやクラツク発生は激減し、本発明
鉄粉が成形性に優れていることを示している。
ト 発明の効果
以上により明らかなように、本発明にかかる粉
末治金用高成形性鉄粉によれば、噴霧法で製造し
た鉄粉に付着した、酸化物形態を還元・焼鈍工程
で改善するとともに、鉄粉の酸素含有量を低減さ
せることにより、粉末治金用鉄粉の粉末形成性を
改良することができる利点がある。
また、本発明鉄粉は、還元・焼鈍処理で、高価
なアンモニア分解ガスを使用する必要がなく、安
価な窒素ガスの使用でよいことから、噴霧鉄粉の
製造原価を、大幅に安価とすることができる利点
もある。[Table] As is clear from Table 2, the bending strength of the green compact using the iron powder of the present invention is the same as that of the conventional water-sprayed iron powder and the reduced iron powder of iron ore. It shows a high value compared to the strength, and the occurrence of cracks during powder compaction, which are often problems in the production of sintered parts, as well as the occurrence of chips and cracks during handling of compacted products, are drastically reduced. This shows that the invented iron powder has excellent formability. G. Effects of the Invention As is clear from the above, according to the highly formable iron powder for powder metallurgy according to the present invention, the form of oxides attached to the iron powder produced by the spraying method is improved by the reduction/annealing process. In addition, by reducing the oxygen content of the iron powder, there is an advantage that the powder formability of the iron powder for powder metallurgy can be improved. In addition, the iron powder of the present invention does not require the use of expensive ammonia decomposition gas in the reduction/annealing process, and can use inexpensive nitrogen gas, which significantly reduces the manufacturing cost of the atomized iron powder. There is also the advantage of being able to
第１図は、従来のａ還元鉄粉、ｂ噴霧鉄粉の粒
子構造を示す走査型電子顕微鏡観察写真、第２図
は、本発明鉄粉の高成形性メカニズム説明模式
図、第３図は、圧粉成形体の曲げ破断面における
粒子構造を示す走査型電子顕微鏡観察写真、第４
図は、本発明鉄粉の粒子構造を示す走査型電子顕
微鏡観察写真である。
１……鉄粉粒、２……涙状形態酸化物、３……
引掻き痕。
Figure 1 is a scanning electron microscope photograph showing the particle structure of conventional reduced iron powder (a) and atomized iron powder (b). Figure 2 is a schematic diagram explaining the high formability mechanism of the iron powder of the present invention. Figure 3 is , Scanning electron microscope photograph showing the particle structure on the bending fracture surface of the compact, No. 4
The figure is a scanning electron microscope photograph showing the particle structure of the iron powder of the present invention. 1...Iron powder grains, 2...Tear-shaped oxide, 3...
Scratch marks.
Claims (1)
粉であつて、 噴霧後、還元・焼鈍処理前の酸素含有量を水素
還元減量にして、重量比率で0.20％以上の鉄粉を
800〜1100℃の高温で、窒素ガス・アルゴン等の
不活性ガス雰囲気中にて還元・焼鈍処理し、鉄粉
表面を覆つているフイルム状の酸化皮膜を、涙状
形態となして鉄粉表面上に付着させるとともに、
還元・焼鈍処理後の酸素含有量を水素還元減量に
して、重量比率で1.0％以下となしたことを特徴
とする、粉末治金用高成形性鉄粉。[Scope of Claims] 1 Highly formable iron powder for powder metallurgy manufactured by a spraying method, wherein the oxygen content after spraying and before reduction/annealing treatment is reduced by hydrogen reduction, and the weight ratio is 0.20. % or more of iron powder
Reduction and annealing treatment is carried out at high temperatures of 800 to 1100℃ in an inert gas atmosphere such as nitrogen gas or argon, and the film-like oxide film covering the surface of the iron powder is formed into a tear-like shape. At the same time as attaching it to the top,
Highly formable iron powder for powder metallurgy, characterized in that the oxygen content after reduction and annealing treatment is reduced by hydrogen reduction to a weight ratio of 1.0% or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58214889A JPS60106901A (en) | 1983-11-15 | 1983-11-15 | Iron powder having high moldability for powder metallurgy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58214889A JPS60106901A (en) | 1983-11-15 | 1983-11-15 | Iron powder having high moldability for powder metallurgy |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60106901A JPS60106901A (en) | 1985-06-12 |
| JPH0477041B2 true JPH0477041B2 (en) | 1992-12-07 |
Family
ID=16663240
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58214889A Granted JPS60106901A (en) | 1983-11-15 | 1983-11-15 | Iron powder having high moldability for powder metallurgy |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60106901A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5234489A (en) * | 1992-05-27 | 1993-08-10 | L'air Liquide | Process for reducing oxides contained in iron powder without substantial decarburization thereof |
-
1983
- 1983-11-15 JP JP58214889A patent/JPS60106901A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60106901A (en) | 1985-06-12 |
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