JPS61110702A - Heat treatment of iron and steel powder with high productivity - Google Patents

Heat treatment of iron and steel powder with high productivity

Info

Publication number
JPS61110702A
JPS61110702A JP59231036A JP23103684A JPS61110702A JP S61110702 A JPS61110702 A JP S61110702A JP 59231036 A JP59231036 A JP 59231036A JP 23103684 A JP23103684 A JP 23103684A JP S61110702 A JPS61110702 A JP S61110702A
Authority
JP
Japan
Prior art keywords
powder
heat treatment
denitrification
deoxidation
cooling
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
Application number
JP59231036A
Other languages
Japanese (ja)
Inventor
Ritsuo Okabe
岡部 律男
Kazuya Endo
一哉 遠藤
Kotaro Okawa
大川 浩太郎
Eiji Hatsuya
初谷 栄治
Hiroyuki Yamasoto
山外 博幸
Shinichiro Muto
武藤 振一郎
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
Kawasaki Steel Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Kawasaki Steel Corp filed Critical Kawasaki Steel Corp
Priority to JP59231036A priority Critical patent/JPS61110702A/en
Publication of JPS61110702A publication Critical patent/JPS61110702A/en
Pending legal-status Critical Current

Links

Landscapes

  • Powder Metallurgy (AREA)

Abstract

PURPOSE:To execute efficiently the heat treatment of iron and steel powder with good productivity by executing the decarburization and deoxidation of the iron and steel powder in a hydrogen atmosphere under specific conditions then cooling quickly the powder and subjecting the powder to slow cooling and denitrification under specific conditions then again to quick cooling. CONSTITUTION:The raw material iron and steel powder is heated and held to and at 800-1,000 deg.C in a gaseous atmosphere contg. hydrogen and is subjected to decarburization and deoxidation. The decarburization is executed by increas ing the dew point of the atmosphere gas (about >=30 deg.C) in the first half of the heating and the deoxidation is executed by decreasing the dew point (about <=30 deg.C) in the second half. The powder is then quickly cooled at an optional rate down to 700 deg.C and is slowly cooled at <=10 deg.C/min cooling rate in a 700-450 deg.C range. The cooled powder is subjected to the denitrification at about <=40 deg.C dew point. The powder is further quickly cooled at an optional cooling rate down to 100 deg.C. The efficient heat treatment is thus executed in the decarburization, deoxidation and denitrification, by which the productivity of the finish heat treatment is improved.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、鉄鋼粉の製造に係り、とくに原料鉄鋼粉の仕
上還元熱処理条件の改善により、生産性を大幅に向上さ
せることのできる鉄粉の熱処理方法に係る。
[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the production of iron and steel powder, and in particular to iron powder that can significantly improve productivity by improving the finish reduction heat treatment conditions of raw material steel powder. This relates to a heat treatment method.

〔従°来の技術〕[Conventional technology]

一般に、鉄鉱石、ミルスケール等の酸化鉄粉を粗還元し
て得られた海綿鉄粉、溶鋼を噴霧して得られたアトマイ
ズ鉄粉、ダライコ粉砕粉、集塵粉等の粗原料鉄粉には、
炭素、酸素、窒素などの不純物成分が目標となる値より
多量に含有しているため、これらの原料鉄鋼粉を適切な
条件で仕上還元熱処理をして、脱炭素、脱酸素および脱
窒素を行なっているのが好適である。
In general, raw material iron powder such as sponge iron powder obtained by rough reduction of iron oxide powder such as iron ore and mill scale, atomized iron powder obtained by spraying molten steel, pulverized Daliko powder, and dust collection powder is used. teeth,
Since the content of impurity components such as carbon, oxygen, and nitrogen is higher than the target value, these raw steel powders are subjected to finishing reduction heat treatment under appropriate conditions to decarbonize, deoxygenate, and denitrify them. It is preferable that

従来、これら鉄鋼粉の仕上還元熱処理方法に関しては、
これまでに幾つかの方法が提案されており、例えば特公
昭57−58401では、圧縮性の良好な還元鉄粉を得
るために、高見掛密度の原料鉄粉を水蒸気を含有した水
素からなる雰囲気ガス中で700〜tooo℃に加熱し
て脱炭および脱酸する方法、また特公昭58−482で
は水素からなる雰囲気ガス中での800〜950℃の加
熱において、まず加熱の前半は水分量を多くして脱炭反
応を、そして後半は水分量を少なくして脱酸反応を積極
的に進行させる方法等が提案されている。
Conventionally, regarding the finishing reduction heat treatment method for these steel powders,
Several methods have been proposed so far. For example, in Japanese Patent Publication No. 57-58401, in order to obtain reduced iron powder with good compressibility, raw iron powder with a high apparent density is heated in an atmosphere consisting of hydrogen containing water vapor. A method of decarburizing and deoxidizing by heating in gas to 700 - too0°C, and in Japanese Patent Publication No. 58-482, in heating at 800 - 950°C in an atmospheric gas consisting of hydrogen, the first half of the heating is to reduce the moisture content. A method has been proposed in which the amount of water is increased to allow the decarburization reaction to proceed, and in the second half, the amount of water is decreased to actively proceed with the deoxidation reaction.

しかし、これらの仕上還元熱処理では脱炭および脱酸を
優先し、脱窒については余り考慮されていないため、最
適な熱処理方法とはいえない。
However, these final reduction heat treatments prioritize decarburization and deoxidation, and do not take denitrification into account much, so they cannot be said to be optimal heat treatment methods.

そこで脱窒を積極的に行なう方法きして、例えば、特公
昭51−13090では公知の工程で得られた還元鉄粉
を、さらに水素系のガス中で500−1000℃に加熱
保持して脱窒を進行させる方法が提案されている。この
方法は脱窒に関しては、債れた方法の1つともいえるが
、脱炭および脱酸と脱窒のための熱処理とを2回に分離
しているため、連続操業が困難であり、また粉砕が余分
に必要なことなどの欠点を有している。
For example, Japanese Patent Publication No. 51-13090 denitrifies the reduced iron powder obtained by a known process by further heating and holding it at 500-1000°C in a hydrogen-based gas. Methods for advancing nitrification have been proposed. This method can be said to be one of the most reliable methods for denitrification, but since decarburization and deoxidation and heat treatment for denitrification are separated into two processes, continuous operation is difficult, and It has drawbacks such as the need for extra grinding.

そこで、この欠点を補う方法として特開昭59−358
01では、アトマイズ鋼粉を還元性あるいは中性雰囲気
ガス中で900〜1050℃に加熱保持したのち、90
0〜550℃の温度範囲内を冷却速度5〜20℃/ m
 i nで冷却して脱炭。
Therefore, as a method to compensate for this drawback, JP-A No. 59-358
In 01, atomized steel powder was heated and held at 900 to 1050°C in a reducing or neutral atmosphere gas, and then heated to 90°C.
Cooling rate 5-20℃/m within the temperature range of 0-550℃
Decarburize by cooling with in.

脱酸および脱窒を連続的に行なう方法が提案されている
。この方法は前述の2回熱処理の方法に比べて生産性の
面で優れているといえるが、脱窒に効果的な温度域を考
慮せず、加熱保持後の高温域から徐冷するため、熱処理
時間が徒・に長くなるという欠点を有し、最適な熱処理
方法とはいえない。
A method has been proposed in which deoxidation and denitrification are performed continuously. This method can be said to be superior in terms of productivity compared to the two-time heat treatment method described above, but it does not take into account the temperature range that is effective for denitrification and slowly cools from the high temperature range after heating and holding. This method has the disadvantage that the heat treatment time is unnecessarily long, so it cannot be said to be an optimal heat treatment method.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

本発明は、仕上還元炉の熱サイクルを検討中に、脱窒に
効果的な徐冷温度域および徐冷速度を見出し、この知見
に基づいてなされたもので、上記従来法の欠点を解消し
、I!1続した仕上還元熱処理において、脱炭、脱酸お
よび脱窒反応を効率的に進行させることによって生産性
に優れる鉄鋼粉の熱処理方法を提案するものである。
The present invention was made based on the discovery of an effective slow cooling temperature range and slow cooling rate for denitrification while studying the thermal cycle of a finishing reduction furnace, and it eliminates the drawbacks of the conventional method described above. , I! This paper proposes a heat treatment method for iron and steel powder that has excellent productivity by efficiently promoting decarburization, deoxidation, and denitrification reactions in one continuous finishing reduction heat treatment.

〔問題点を解決するための手段〕[Means for solving problems]

本発明は、海綿鉄粉、アトマイズ鉄鋼粉、ダライコ粉砕
粉、集塵粉等の原料鉄鋼粉の仕上還元熱処理において、
該原料鉄鋼粉の脱炭、脱酸および脱窒反応を効率的に進
行させることによって生産性に優れる鉄鋼粉の仕上熱処
理を行う。
The present invention provides finishing reduction heat treatment of raw material steel powder such as sponge iron powder, atomized steel powder, Daliko pulverized powder, dust collection powder, etc.
Finishing heat treatment of the steel powder is performed, which is highly productive, by efficiently progressing the decarburization, deoxidation, and denitrification reactions of the raw material steel powder.

具体的には、原料鉄鋼粉を800〜1000℃に加熱保
持して脱炭および脱酸を行なったのち、脱窒にあまり効
果的でない高温度域を任意の冷却速度で急冷し、脱窒に
有効な700〜450℃の温度範囲内を10℃/m i
 n以下の冷却速度で徐冷して脱窒反応を進行させたの
ち、それ以下の温度域を再び任意の冷却速度で急冷する
Specifically, raw steel powder is heated and held at 800 to 1000°C to decarburize and deoxidize, and then the high temperature range, which is not very effective for denitrification, is rapidly cooled at an arbitrary cooling rate to achieve denitrification. 10℃/m i within the effective temperature range of 700-450℃
After the denitrification reaction is progressed by slow cooling at a cooling rate of n or less, the temperature range below that temperature is rapidly cooled again at an arbitrary cooling rate.

以下、本発明の構成について説明する。The configuration of the present invention will be explained below.

本発明の仕上還元熱処理では、まず、該鉄鋼粉を水素を
含む雰囲気ガス中で800〜1000℃に加熱保持して
脱炭および脱酸を行なう、この際、加熱の前半では雰囲
気ガスの露点を高くして脱炭反応を進行させ、後半では
露点を低くして脱酸反応を進行させる。脱炭を進行させ
る雰囲気ガスとしては湿潤することが必要であるが、露
点が30℃未満では脱炭反応が著しく低下するため、y
g点は30℃以上とすることが好ましい、また、脱酸を
進行させる雰囲気ガスとしては、露点が低くなるほど脱
酸反応が進行するため、露点は30″C以下、望ましく
は室温以下とすることが好ましい、露点が30℃を超え
ると脱酸反応が著しく低下し、効率的な脱酸処理ができ
ない。
In the finishing reduction heat treatment of the present invention, first, the steel powder is heated and held at 800 to 1000°C in an atmospheric gas containing hydrogen to decarburize and deoxidize.In the first half of the heating, the dew point of the atmospheric gas is lowered. The dew point is raised to allow the decarburization reaction to proceed, and in the latter half the dew point is lowered to allow the deoxidation reaction to proceed. The atmospheric gas that promotes decarburization needs to be humid, but if the dew point is less than 30°C, the decarburization reaction will drop significantly, so y
It is preferable that the g point is 30°C or higher, and as for the atmospheric gas that promotes deoxidation, the lower the dew point, the more the deoxidation reaction progresses, so the dew point should be 30"C or lower, preferably room temperature or lower. is preferable; if the dew point exceeds 30°C, the deoxidation reaction will be significantly reduced, making it impossible to carry out efficient deoxidation treatment.

次に、本発明で脱炭および脱酸のための加熱温度を80
0〜1000℃に限定した理由について述べる。加熱保
持温度が高いほど脱炭および脱酸反応が活発に進行する
ため好ましいといえるが、tooo℃を超える温度では
鉄鋼粉が焼結固化したケーキとなり、熱処理後のケーキ
の解砕が困難となり歩留りが低下し、また所定の粒度の
粉末を(与るために過度の解砕を行うと鉄鋼粉粒子が加
重硬化あるいは球状化して圧縮性、成形性が低下する。
Next, in the present invention, the heating temperature for decarburization and deoxidation is set to 80°C.
The reason for limiting the temperature to 0 to 1000°C will be described. It can be said that the higher the heating holding temperature, the more active the decarburization and deoxidation reactions are, so it is preferable. However, at temperatures exceeding too many degrees Celsius, the steel powder becomes a sintered and solidified cake, making it difficult to break up the cake after heat treatment, which reduces the yield. In addition, if excessive crushing is performed to obtain a powder with a predetermined particle size, the steel powder particles will harden or become spheroidized, resulting in a decrease in compressibility and formability.

一方、加熱温度が800°C未満では熱処理後のケーキ
の解砕は容易であるものの、脱炭および脱酸反応速度が
著しく低下するため熱処理に長時間を要し、効率的でな
い、したがって本発明では、脱炭および脱酸のための加
熱温度を800〜tooo℃に限定する。なお、加熱保
持時間は原料鉄鋼粉の炭素および酸素含有量に応じて調
整する。
On the other hand, if the heating temperature is less than 800°C, although it is easy to crush the cake after heat treatment, the decarburization and deoxidation reaction rates are significantly reduced, so the heat treatment takes a long time and is not efficient. Here, the heating temperature for decarburization and deoxidation is limited to 800 to toooC. Note that the heating holding time is adjusted depending on the carbon and oxygen contents of the raw material steel powder.

つぎに脱窒のための熱処理条件について述べる。Next, the heat treatment conditions for denitrification will be described.

−・般に、鉄鋼粉を粉末冶金用として使用する場合に、
脱窒が不十分であると、圧縮性や機械的特性が低下する
ため、適切な条件で熱処理して十分脱窒することが必要
である。
−・Generally, when using iron and steel powder for powder metallurgy,
If denitrification is insufficient, compressibility and mechanical properties will deteriorate, so it is necessary to perform heat treatment under appropriate conditions for sufficient denitrification.

まず、脱窒を進行させる雰囲気ガスとしては、水素を含
む雰囲気ガス中において、a点が低くなるほど脱窒反応
が進行するため、露点は40℃以下、望ましくは、室温
以下とする。露点が40℃を超えると、水蒸気分圧が上
昇して、水素分圧が低下し、脱窒速度が低下するため好
ましくない。
First, as for the atmospheric gas that promotes denitrification, in an atmospheric gas containing hydrogen, the denitrification reaction progresses as the a point becomes lower, so the dew point is set to 40° C. or lower, preferably room temperature or lower. If the dew point exceeds 40°C, the water vapor partial pressure will increase, the hydrogen partial pressure will decrease, and the denitrification rate will decrease, which is not preferable.

本発明者らの実験によれば、脱窒は高温加熱保持後から
の冷却速度に大きく影響され、10℃/minを超える
冷却速度では脱窒反応はあまり進行せず脱窒が不十分と
なるが、冷却速度がlO℃/min以下で徐冷すると脱
窒反応が急激に進行して、十分に脱窒した鉄鋼粉を得る
ことができる。したがって、脱窒のための冷却速度はl
O℃/ m I nで徐冷することが必要である。
According to experiments conducted by the present inventors, denitrification is greatly affected by the cooling rate after high temperature heating and maintenance, and at cooling rates exceeding 10°C/min, the denitrification reaction does not proceed much and denitrification becomes insufficient. However, if the cooling rate is slowly cooled to 10° C./min or less, the denitrification reaction will rapidly proceed, making it possible to obtain iron and steel powder with sufficient denitrification. Therefore, the cooling rate for denitrification is l
Slow cooling at 0 °C/min is necessary.

また、脱窒は徐冷の開始温度および終了温度に6′大き
く影響され1本発明者らの実験によれば。
Furthermore, denitrification is greatly influenced by the starting temperature and ending temperature of slow cooling, according to experiments conducted by the present inventors.

徐冷の開始温度が700℃未満では、脱窒が不十分であ
るが、徐冷開始温度が700℃以上では。
If the starting temperature of slow cooling is less than 700°C, denitrification is insufficient, but if the starting temperature of slow cooling is 700°C or higher.

いずれの温度域から徐冷しても十分脱窒されて。Sufficient denitrification is achieved even when slowly cooled from any temperature range.

脱窒反応ははC飽和する。このことは、脱窒のための徐
冷開始温度は700℃で十分であることを意味しており
、それを超える温度域からの徐冷は効率的な熱処理とは
いえない、したがって本発明では、脱窒にあまり寄与し
ない700℃を超える高温域は任意の冷却速度で急冷し
、700℃から脱窒のための徐冷を行なう、また、徐冷
の終了温度が低下するほど脱窒反応は進行するが、45
0℃を下廻る温度域では十分に脱窒して、脱窒速度は一
定となる。したがって脱窒反応を効果的に進行させるに
は450℃まで徐冷すれば十分であり、それ未満の温度
域まで徐冷することは脱窒にあまり効果がなく、徐冷時
間のみが徒に長くなり効率的な熱処理とはいえない、し
たがって、本発明では、脱窒のための徐冷の終了温度を
450℃として、それを下廻る温度域は任意の冷却速度
で急冷する。なお徐冷終了温度が450℃より高いと1
悦窄が不十分となり好ましくない。
The denitrification reaction is C saturated. This means that a slow cooling start temperature of 700°C is sufficient for denitrification, and slow cooling from a temperature range exceeding this cannot be considered an efficient heat treatment. The high temperature range above 700°C, which does not contribute much to denitrification, is rapidly cooled at an arbitrary cooling rate, and slow cooling for denitrification is performed from 700°C. Also, the lower the end temperature of slow cooling, the less the denitrification reaction. It progresses, but 45
In the temperature range below 0°C, sufficient denitrification occurs and the denitrification rate remains constant. Therefore, slow cooling to 450°C is sufficient for the denitrification reaction to proceed effectively; slow cooling to a temperature lower than that is not very effective for denitrification, and only slows down the slow cooling time to be unnecessarily long. Therefore, in the present invention, the end temperature of slow cooling for denitrification is set at 450° C., and the temperature range below that temperature is rapidly cooled at an arbitrary cooling rate. Note that if the slow cooling end temperature is higher than 450℃, 1
This is not desirable because the pleasure is insufficient.

以上説明したように1本発明における脱窒のための熱処
理条件は、高温加熱保持後700.”0までは任意の冷
却速度で急冷し、700℃から450℃までの温度範囲
内をlO℃/min以下の冷却速度で徐冷して、脱窒反
応を効果的に進行させたのち、450℃を下廻る温度域
では再び任意の冷却速度で急冷して、脱窒悪理を効率的
に行なう。
As explained above, the heat treatment conditions for denitrification in the present invention are as follows: 700. After rapidly cooling at an arbitrary cooling rate to 0 and then gradually cooling at a cooling rate of 10°C/min or less within the temperature range from 700°C to 450°C to effectively advance the denitrification reaction, In the temperature range below ℃, rapid cooling is performed again at an arbitrary cooling rate to efficiently perform denitrification.

なお、急冷時の雰囲気は酸化を防止する意味から、中性
あるいは還元性雰囲気であることが好ましい。
Note that the atmosphere during rapid cooling is preferably a neutral or reducing atmosphere in order to prevent oxidation.

〔作用〕[Effect]

本発明は、脱炭、脱酸を最も適切な温度域に加熱保持し
、脱窒反応に最も効果的な温度域をlO℃/ m l 
nの冷却速度で徐冷し、その他の温度域を急冷するので
、脱炭、脱酸、脱窒を最も効率よく熱処理することがで
き、仕上熱処理の生産性を最大限に高める作用をなす。
The present invention heats and maintains decarburization and deoxidation in the most appropriate temperature range, and maintains the most effective temperature range for denitrification reaction at lO℃/ml.
Since slow cooling is performed at a cooling rate of n, and rapid cooling is performed in other temperature ranges, decarburization, deoxidation, and denitrification can be performed most efficiently, and the productivity of finishing heat treatment is maximized.

〔実施例〕〔Example〕

以下実施例について説明する。 Examples will be described below.

原料鉄鋼粉として溶鋼を水噴霧して得たアトマイズ鉄鋼
粉を用いて仕上熱処理を行った。その鉄鋼粉の化学組成
および粉体特性を第1表に示す。
Finishing heat treatment was performed using atomized steel powder obtained by water spraying molten steel as raw material steel powder. The chemical composition and powder properties of the steel powder are shown in Table 1.

第1表 鉄鋼粉の化学組成および粉体特性化学組成: C:  0.190   重量% 0:  0,722   重量% N:  0,0082  正量% 粉体特性: 見掛密度:2.96  g/crn’ 流動度:  25.7  sec150gこの粉末をH
2:50容量%、N2:50容量%の雰囲気ガス中にお
いて、950℃で20分間加熱保持したのち、種々の条
件で熱処理した。雰囲気ガスの露点は昇温時は40″C
1均熱および冷却時は室温以下として、脱炭、脱酸およ
び脱窒を行なった。第2表に熱処理後の鉄鋼粉の化学組
成および圧粉体特性を示す。
Table 1 Chemical composition and powder properties of steel powder Chemical composition: C: 0.190% by weight 0: 0,722% by weight N: 0,0082% by weight Powder properties: Apparent density: 2.96 g/ crn' Fluidity: 25.7 sec150g of this powder
After heating and holding at 950°C for 20 minutes in an atmosphere gas containing 2:50% by volume and N2:50% by volume, heat treatment was performed under various conditions. The dew point of the atmospheric gas is 40″C when the temperature rises.
1. During soaking and cooling, the temperature was kept below room temperature to perform decarburization, deoxidation, and denitrification. Table 2 shows the chemical composition and compact properties of the steel powder after heat treatment.

比較例1は、従来から提案されている熱処理条件のもの
で、950℃で20分間加熱保持して脱)餐、脱酸を行
なったのち、直ちに、徐冷を開始したものである。
In Comparative Example 1, the heat treatment conditions were conventionally proposed, and after heating and holding at 950° C. for 20 minutes to perform deoxidation and deoxidation, slow cooling was immediately started.

比較例2は950’C!で20分間加熱保持した後80
0℃までは任意の冷却速度で急冷し、800〜450℃
の温度範囲内を20℃/ m i nで徐冷したもので
、徐冷速度の比較的速いものである。
Comparative example 2 is 950'C! After heating and holding for 20 minutes at 80
Rapidly cool down to 0℃ at any cooling rate, 800-450℃
The temperature range is 20°C/min, and the slow cooling rate is relatively fast.

比較例3は高温加熱保持後650℃までは任意の冷却速
度で急冷したのち、650℃から徐冷を開始した徐冷開
始温度の低いものを示す。
Comparative Example 3 shows a low slow cooling start temperature in which after high temperature heating and holding, rapid cooling was performed at an arbitrary cooling rate up to 650°C, and then slow cooling was started from 650°C.

そして比較例4は、800℃から徐冷を開始し、600
℃で徐冷を終了した、徐冷終了温度の旨いものである。
In Comparative Example 4, slow cooling was started from 800°C and 600°C.
It is a delicious product that has been slowly cooled at ℃.

これに対し実施例は加熱保持vk700℃までは任意の
冷却速度で急冷したのち、700〜450℃の温度tI
I2!]内を、実施例1では5℃/ m i nで、そ
して実施例2では6.5℃/minの冷却速度でそれぞ
れ徐冷したものである。
On the other hand, in the example, after heating retention vk is rapidly cooled at an arbitrary cooling rate up to 700°C, the temperature tI is 700 to 450°C.
I2! ] was slowly cooled at a cooling rate of 5° C./min in Example 1 and 6.5° C./min in Example 2.

いずれの条件で処理したものも、 炭素量が0.001−0.002重1%。Those treated under any of the conditions, Carbon content is 0.001-0.002% by weight.

酸素量が0.120〜0.140主星%。Oxygen content is 0.120-0.140% of the main star.

と十分脱炭および脱酸されおり、加熱保持後からの冷却
は脱炭および脱離に影響しないことがわかる。しかじ脱
窒は冷却条件に大さく影響され、冷却速度の速い比較例
2では、 窒素量が0.0064重量%、 また徐冷開始温度の低い比較例3では。
It can be seen that the decarburization and deoxidation were sufficient, and that cooling after heating and holding had no effect on decarburization and deoxidation. However, denitrification is greatly affected by the cooling conditions; in Comparative Example 2, where the cooling rate was fast, the nitrogen amount was 0.0064% by weight, and in Comparative Example 3, where the slow cooling start temperature was low.

窒素量は0.004821量%、 モして徐冷終了温度の高い比較例4では窒素量が0.0
0511量%、 と高い値を示す、なお加熱保持直後から徐冷を行った従
来法の比較例1では、 窒素量が0.0040重量%。
The amount of nitrogen was 0.004821% by mass, and the amount of nitrogen was 0.0% in Comparative Example 4, which had a high end temperature of slow cooling.
In Comparative Example 1 of the conventional method in which slow cooling was performed immediately after heating and holding, the nitrogen content was 0.0040% by weight.

と低いが、この方法では熱処理に長時間を要し。However, this method requires a long time for heat treatment.

効率的でない。Not efficient.

これに対し1本発明の実施例では、脱窒に有効な温度域
のみを徐冷するため熱処理時間が短かく、窒素量も。
On the other hand, in the embodiment of the present invention, only the temperature range effective for denitrification is slowly cooled, so the heat treatment time is short and the amount of nitrogen is also reduced.

″に施例1では0.0032主星%、 実施例2では0.0039重量%。” in Example 1, 0.0032 main star%, In Example 2, it was 0.0039% by weight.

といずれも低い値を示し1本発明の熱処理方法が脱窒に
効果的であることがわかる。
Both showed low values, indicating that the heat treatment method of the present invention is effective for denitrification.

熱処理後の鉄鋼粉の圧縮性を見るために、これら鉄鋼粉
にステアリン酸亜鉛を1重量%添加混合して5Lon/
cm’の成形圧力で圧粉体を形成して圧粉密度を測定し
たが、その結果を第2表の中に示す。
In order to check the compressibility of the steel powder after heat treatment, 1% by weight of zinc stearate was added and mixed to the steel powder to give 5 L/L.
A green compact was formed at a compacting pressure of cm' and the green density was measured, and the results are shown in Table 2.

従来法の比較例1は窒素量が低いため、圧粉密度゛が6
.81g/crrfと高いが、比較例2〜4は窒素量が
高いため、圧粉密度が6.76〜6.79g/c m’
と低く、圧縮性が悪い、これに対し、本発明の条件で熱
処理した実施例1および2では窒素量が低いため、圧粉
密度が6.83および6.82g/c m’と高く、従
来の熱処理方法のものに比べて優れた圧縮性を示す。
In Comparative Example 1 of the conventional method, the green density was 6 because the nitrogen content was low.
.. Although it is high at 81 g/crrf, since the nitrogen amount in Comparative Examples 2 to 4 is high, the green density is 6.76 to 6.79 g/cm'
On the other hand, in Examples 1 and 2, which were heat-treated under the conditions of the present invention, the nitrogen content was low, so the green density was high at 6.83 and 6.82 g/cm', which was higher than that of the conventional It exhibits superior compressibility compared to the heat treatment method.

〔発明の効果〕〔Effect of the invention〕

以°上説明したように鉄鋼粉の連続した仕上還元熱処理
において、脱炭、脱酸および脱窒を効率的に行なうこと
により、全処理工程に要する時間が従来に比しほぼ局程
度となり、特性の優れる鉄鋼粉を工業的に多量に生産す
ることが可能となり、本発明の鉄鋼粉の製造方法は工業
的にWAMな効果を奏する。
As explained above, by efficiently performing decarburization, deoxidation, and denitrification in the continuous finish reduction heat treatment of steel powder, the time required for the entire treatment process is reduced to approximately the same level as in the past, and the characteristics are improved. It becomes possible to industrially produce a large amount of iron and steel powder with excellent properties, and the method for producing iron and steel powder of the present invention has an industrial WAM effect.

Claims (1)

【特許請求の範囲】 1 鉄鋼粉粗原料を連続仕上還元熱処理するにあたり、
該鉄鋼粉を水素を含む雰囲気ガス中で800〜1000
℃の温度に加熱保持し て、脱炭および脱酸したのち700℃までは任意の冷却
速度で急冷し、次いで、700〜450℃の温度範囲内
を10℃/min以下の冷却速度で徐冷して脱窒したの
ち、再び 100℃以下まで任意の冷却速度で急冷することを特徴
とする生産性に優れる鉄鋼粉の熱処理方法。
[Claims] 1. In continuous finishing reduction heat treatment of crude raw material of iron and steel powder,
The steel powder is heated to 800 to 1000 in an atmospheric gas containing hydrogen.
Decarburize and deoxidize by heating and holding at a temperature of 100°C, then rapidly cooling at an arbitrary cooling rate to 700°C, then slowly cooling at a cooling rate of 10°C/min or less within a temperature range of 700 to 450°C. A heat treatment method for iron and steel powder with excellent productivity, characterized by denitrifying the powder and then rapidly cooling it again to 100° C. or less at an arbitrary cooling rate.
JP59231036A 1984-11-01 1984-11-01 Heat treatment of iron and steel powder with high productivity Pending JPS61110702A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP59231036A JPS61110702A (en) 1984-11-01 1984-11-01 Heat treatment of iron and steel powder with high productivity

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP59231036A JPS61110702A (en) 1984-11-01 1984-11-01 Heat treatment of iron and steel powder with high productivity

Publications (1)

Publication Number Publication Date
JPS61110702A true JPS61110702A (en) 1986-05-29

Family

ID=16917264

Family Applications (1)

Application Number Title Priority Date Filing Date
JP59231036A Pending JPS61110702A (en) 1984-11-01 1984-11-01 Heat treatment of iron and steel powder with high productivity

Country Status (1)

Country Link
JP (1) JPS61110702A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02274801A (en) * 1989-04-17 1990-11-09 Kawasaki Steel Corp Finishing reduction method for alloy steel powder

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5435967A (en) * 1977-08-23 1979-03-16 Kobe Steel Ltd Transportation device of cylindrical article
JPS5935601A (en) * 1982-08-19 1984-02-27 Kawasaki Steel Corp Production of atomized steel powder having high compressibility

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5435967A (en) * 1977-08-23 1979-03-16 Kobe Steel Ltd Transportation device of cylindrical article
JPS5935601A (en) * 1982-08-19 1984-02-27 Kawasaki Steel Corp Production of atomized steel powder having high compressibility

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02274801A (en) * 1989-04-17 1990-11-09 Kawasaki Steel Corp Finishing reduction method for alloy steel powder

Similar Documents

Publication Publication Date Title
KR100247598B1 (en) Production of grain oriented magnetic steel sheet reduced in iron loss
EP0400549B1 (en) Process for producing grainoriented electrical steel sheet having superior magnetic and surface film characteristics
WO2018181712A1 (en) Method for producing die-cast product of spherical graphitic cast iron including ultrafine spherical graphite, and spheroidizing treatment agent
US2342799A (en) Process of manufacturing shaped bodies from iron powders
JPS598049B2 (en) Manufacturing method of non-oriented electrical steel sheet with excellent magnetic properties
JPS61110702A (en) Heat treatment of iron and steel powder with high productivity
JP2002501123A (en) Method of producing iron-based powder in an airtight furnace
JPS6253561B2 (en)
JPS58482B2 (en) Heat treatment method for raw iron powder
US2237867A (en) Method of making sponge iron powder
US2797156A (en) Nitrogen-bearing ferrochromium
JPH10265803A (en) Production of ferrous powder for powder metallurgy
RU2198226C2 (en) Method of manufacturing article from iron-carbon material
JP3728922B2 (en) Method for melting molybdenum-containing molten steel
US3595709A (en) Process for producing ferrochrome alloys with high nitrogen content and low carbon content
JPS624801A (en) Method and apparatus for finish heat treatment of iron and steel powder by making combination use of rotary kiln and moving bed furnace
US3334999A (en) Method of manufacturing semi-fabricated products of chrome-nickel steels
US3253909A (en) Processing silicon steel
Aleksandrov et al. Improving rail-steel production
JPH0471962B2 (en)
JPH049402A (en) Method for executing reduction-annealing to metal powder
US3385694A (en) Method of producing iron powder from pig iron or such and iron oxides
TWI657150B (en) Phosphorus-containing electromagnetic steel having extremely low contents of titanium and carbon and method of producing the same
JPS62107001A (en) Finish heat treatment method for reduced iron powder
JPS5923840A (en) Production of high strength sintered material