JPH1025533A - Sintered low alloy steel and its production - Google Patents

Sintered low alloy steel and its production

Info

Publication number
JPH1025533A
JPH1025533A JP20112296A JP20112296A JPH1025533A JP H1025533 A JPH1025533 A JP H1025533A JP 20112296 A JP20112296 A JP 20112296A JP 20112296 A JP20112296 A JP 20112296A JP H1025533 A JPH1025533 A JP H1025533A
Authority
JP
Japan
Prior art keywords
atmosphere
temperature
powder
carbon
carbide
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
JP20112296A
Other languages
Japanese (ja)
Inventor
Akira Horata
亮 洞田
Tetsuya Kondo
鉄也 近藤
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.)
Daido Steel Co Ltd
Original Assignee
Daido Steel Co Ltd
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 Daido Steel Co Ltd filed Critical Daido Steel Co Ltd
Priority to JP20112296A priority Critical patent/JPH1025533A/en
Publication of JPH1025533A publication Critical patent/JPH1025533A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To provide a sintered low alloy steel having accurately controlled carbon content and its preferred production. SOLUTION: A green compact is heated to 300-1000 deg.C in an Ar atmosphere and held for a time sufficient to cause reaction, C+2[O]→CO2 , by which oxygen is previously removed thoroughly. Then, in the state of Ar atmosphere, the temp. is lowered down to 300-600 deg.C at which reaction, C+2H2 →CH4 takes place. While holding the green compact a 300-600 deg.C, the atmosphere is substituted by (Ar+50%H2 ) atmosphere and the green compact is held in this state for required time to undergo the latter reaction, by which carbon in iron powder is removed. While the green compact is held at 300-600 deg.C the atmosphere is substituted again by the Ar atmosphere, and the temp. is raised up to a sintering temp. to sinter the green compact. Because oxygen is substantially removed previously, carbon in the carbide remaining by reaction, C+[O]→CO is not removed at this time.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】この発明は、炭素量が正確に
制御された容易に製造可能な焼結低合金鋼と、その製造
方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered low alloy steel whose carbon content is accurately controlled and which can be easily manufactured, and a method of manufacturing the same.

【０００２】[0002]

【従来の技術】金属粉末を所要形状に成形し、これを焼
結して得た焼結品が、各種産業界で広く使用されてい
る。この焼結品、例えば焼結低合金鋼においては、その
鋼中に含有される炭素量を各種変えたものが製造され、
使用する部位に応じて使い分けられている。この焼結低
合金鋼の炭素量を制御する方法として、焼結時における
Ｃ＋Ｏ→ＣＯおよびＣ＋Ｏ2→ＣＯ2の反応量を予測し、
焼結低合金鋼中に残留させるべき炭素量に応じて粉末中
の炭素(Ｃ)と酸素(Ｏ)の量を調整することが一般に行な
われている。また具体的な炭素量の調整方法としては、
炭素量の異なる低合金鋼の粉末を製造してこれらを混
合し、焼結時の炭素(Ｃ)と酸素(Ｏ)の反応の結果とし
て、目的の炭素量を残留させる方法や、低合金鋼の粉
末に炭素粉を混合し、焼結時に低合金鋼粉末中の炭素
(Ｃ)と炭素粉とを低合金鋼粉末中の酸素(Ｏ)と反応させ
る結果として、目的の炭素量を残留させる方法がある。2. Description of the Related Art A sintered product obtained by forming a metal powder into a required shape and sintering it is widely used in various industries. In this sintered product, for example, in a sintered low-alloy steel, those in which the amount of carbon contained in the steel is variously changed are manufactured,
It is used properly according to the part to be used. As a method of controlling the carbon content of the sintered low alloy steel, the reaction amounts of C + O → CO and C + O 2 → CO 2 during sintering are predicted,
It is common practice to adjust the amounts of carbon (C) and oxygen (O) in the powder according to the amount of carbon to be left in the sintered low alloy steel. As a specific method of adjusting the carbon amount,
A method of producing powders of low alloy steels having different carbon contents and mixing these powders, as a result of a reaction between carbon (C) and oxygen (O) at the time of sintering, leaving a desired carbon amount, The carbon powder is mixed with the carbon powder in the low alloy steel powder during sintering.
As a result of reacting (C) and carbon powder with oxygen (O) in the low alloy steel powder, there is a method of leaving a target carbon amount.

【０００３】[0003]

【発明が解決しようとする課題】前述した,の調整
方法で用いられる低合金鋼の粉末は、噴霧法でしか製造
することができず、しかも低合金鋼故に酸素量が高い値
になると共にその値も安定していなかった。このため、
炭素(Ｃ)と酸素(Ｏ)とを反応させて炭素量を制御するこ
とは容易ではなく、その制御精度は低いものであった。
また、低合金鋼の噴霧粉は比較的粉末粒径が大きく、高
い焼結密度を得ることができない難点が指摘される。す
なわち、低合金鋼の粉末は製造し難く、しかも焼結性が
良くないものであった。The powder of the low alloy steel used in the above-mentioned adjustment method can be produced only by the spraying method. The values were not stable either. For this reason,
It was not easy to control the amount of carbon by reacting carbon (C) and oxygen (O), and the control accuracy was low.
In addition, it is pointed out that the low-alloy steel spray powder has a relatively large powder particle size and cannot obtain a high sintering density. That is, the powder of the low-alloy steel is difficult to produce and has poor sinterability.

【０００４】[0004]

【発明の目的】そこで発明者は、炭素量が制御された焼
結低合金鋼を製造するに際し、これに内在している前記
課題を好適に解決するべく種々の試験を重ねた結果、製
造し難く、しかも焼結性が良くない低合金鋼の粉末に代
えて、カーボニル法によって容易に製造可能な鉄粉また
は鉄粉にＮｉ粉を混合させた混合粉をベース粉末とし、
これに炭化物の粉末を添加した原料粉末を用いて成形体
を成形し、これを焼結する際の温度および雰囲気を制御
することにより、焼結低合金鋼の炭素量を正確に制御し
得ることを見い出した。すなわち本発明の目的は、炭素
量が正確に制御された焼結低合金鋼と、その好適な製造
方法とを提供することにある。The object of the present invention is to provide a sintered low-alloy steel with a controlled carbon content, after carrying out various tests in order to preferably solve the above-mentioned problems inherent therein. In place of low alloy steel powder that is difficult and yet has poor sinterability, iron powder or a mixed powder obtained by mixing Ni powder with iron powder that can be easily produced by the carbonil method is used as a base powder,
It is possible to accurately control the carbon content of a sintered low alloy steel by controlling a temperature and an atmosphere when sintering a compact using a raw material powder obtained by adding a carbide powder thereto. I found That is, an object of the present invention is to provide a sintered low-alloy steel in which the amount of carbon is accurately controlled, and a suitable production method thereof.

【０００５】[0005]

【課題を解決するための手段】前記課題を克服し、所期
の目的を達成するため、本発明に係る焼結低合金鋼は、
鉄粉または鉄粉＋Ｎｉ粉の混合粉に炭化物を添加した原
料粉末から成形され、略炭化物中の炭素のみを残留させ
るよう焼結したことを特徴とする。In order to overcome the above-mentioned problems and achieve the intended object, a sintered low-alloy steel according to the present invention comprises:
It is characterized by being formed from a raw material powder obtained by adding carbide to iron powder or a mixed powder of iron powder and Ni powder, and sintered so that substantially only carbon in the carbide remains.

【０００６】また前記目的を達成するため、本願の別の
発明に係る焼結低合金鋼の製造方法は、鉄粉または鉄粉
＋Ｎｉ粉の混合粉に炭化物を添加した原料粉末からなる
成形体を焼結するに際し、水素を殆ど含まない雰囲気の
下で３００〜１０００℃に昇温して所要時間保持し、そ
の後３００〜６００℃に降温すると共に水素分圧の高い
雰囲気に置換した下で所要時間保持し、次いで少なくと
も水素による炭化物の還元反応が起きる温度までは水素
を殆ど含まない雰囲気に保持したまま焼結温度まで昇温
することを特徴とする。In order to achieve the above object, a method for producing a sintered low alloy steel according to another invention of the present application is to provide a method for producing a compact comprising a raw material powder obtained by adding carbide to iron powder or a mixed powder of iron powder and Ni powder. In sintering, the temperature is raised to 300 to 1000 ° C. in an atmosphere containing almost no hydrogen and maintained for a required time, and then the temperature is lowered to 300 to 600 ° C. and the required time is replaced in an atmosphere having a high hydrogen partial pressure. Then, the temperature is raised to a sintering temperature while maintaining an atmosphere containing almost no hydrogen until at least a temperature at which a carbide reduction reaction occurs by hydrogen.

【０００７】また前記目的を達成するため、本願の更に
別の発明に係る焼結低合金鋼の製造方法は、鉄粉または
鉄粉＋Ｎｉ粉の混合粉に炭化物を添加した原料粉末から
なる成形体を焼結するに際し、水素０％のＡｒ雰囲気の
下で３００〜１０００℃に昇温して所要時間保持し、そ
の後３００〜６００℃に降温すると共に水素５０％のＡ
ｒ雰囲気に置換した下で所要時間保持し、次いで水素０
％のＡｒ雰囲気に置換した下で焼結温度まで昇温するこ
とを特徴とする。In order to achieve the above object, a method for producing a sintered low alloy steel according to still another invention of the present application is directed to a compact comprising a raw material powder obtained by adding carbide to iron powder or a mixed powder of iron powder and Ni powder. When sintering, the temperature is raised to 300 to 1000 ° C. in an Ar atmosphere of 0% hydrogen and maintained for a required time, and then the temperature is lowered to 300 to 600 ° C. and the A of 50% hydrogen is cooled.
for a required time under the atmosphere of
%, And the temperature is raised to the sintering temperature while replacing the atmosphere with Ar.

【０００８】[0008]

【発明の実施の形態】次に、本発明に係る焼結低合金鋼
およびその製造方法につき、好適な実施例を挙げて、添
付図面を参照しながら以下説明する。本発明は、前述し
たように鉄粉のみのベース粉末、または鉄粉＋Ｎｉ粉の
混合粉からなるベース粉末に炭化物の粉末を添加した原
料粉末を用い、これを焼結する際の温度および雰囲気を
制御することにより、焼結低合金鋼の炭素量を正確に制
御することを内容としている。この場合の炭化物粉とし
ては、Ｃｒ3Ｃ2やＭｏ2Ｃ等の微粉が好適に使用され、
対象とする低合金系はＦｅ−Ｃｒ,Ｆｅ−Ｃｒ−Ｍｏ,Ｆ
ｅ−Ｃｒ−Ｍｏ−Ｎｉである。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a sintered low alloy steel and a method for producing the same according to the present invention will be described with reference to the accompanying drawings, with reference to preferred embodiments. As described above, the present invention uses a base powder composed of only iron powder or a base powder formed by adding a carbide powder to a base powder composed of a mixed powder of iron powder and Ni powder. The control is intended to accurately control the carbon content of the sintered low alloy steel. As the carbide powder in this case, fine powder such as Cr 3 C 2 or Mo 2 C is preferably used.
The target low alloy system is Fe-Cr, Fe-Cr-Mo, F
e-Cr-Mo-Ni.

【０００９】先ず、本発明を完成するに至った経緯につ
き簡単に説明する。前記原料粉末を成形・焼結するに際
し、鉄粉中の炭素(Ｃ)および酸素(Ｏ)を還元除去する
が、炭化物粉中の炭素(Ｃ)は還元されない焼結条件(温
度および雰囲気)を検討した。この場合に、水素(Ｈ)を
含有するか、あるいは含有しない雰囲気で前記原料粉末
からなる成形体を加熱した場合、次のような反応が予想
される。 Ｃ＋２[Ｏ]→ＣＯ2 (１) Ｃ＋[Ｏ] →ＣＯ (２) [Ｏ]＋Ｈ2 →Ｈ2Ｏ (３) Ｃ＋２Ｈ2 →ＣＨ4 (４) ２[Ｏ] →Ｏ2 (５) なお、図２に示す如く、(１)の反応は３００〜７００℃
で生じ、(２)の反応は７５０℃以上で生じ、(３)の反応
は３００℃以上で生じ、(４)の反応は３００〜６００℃
で生じ、(５)の反応はＡｒまたは真空雰囲気で４００℃
以上で生じることが確認されている。First, a brief description will be given of how the present invention has been completed. When molding and sintering the raw material powder, sintering conditions (temperature and atmosphere) are such that carbon (C) and oxygen (O) in iron powder are reduced and removed, but carbon (C) in carbide powder is not reduced. investigated. In this case, when a molded body made of the raw material powder is heated in an atmosphere containing or not containing hydrogen (H), the following reaction is expected. C + 2 [O] → CO 2 (1) C + [O] → CO (2) [O] + H 2 → H 2 O (3) C + 2H 2 → CH 4 (4) 2 [O] → O 2 (5) As shown in FIG. 2, the reaction of (1) is performed at 300 to 700 ° C.
The reaction of (2) occurs at 750 ° C. or higher, the reaction of (3) occurs at 300 ° C. or higher, and the reaction of (4) occurs at 300 to 600 ° C.
The reaction of (5) is performed at 400 ° C. in an Ar or vacuum atmosphere.
It has been confirmed that this occurs.

【００１０】前記４つの反応を前提として、鉄(Ｆｅ)と
クロム(Ｃｒ)やモリブデン(Ｍｏ)の炭化物の還元反応が
生じるかを実験を行ない検討した。(１)の反応は鉄粉に
含まれる炭素(Ｃ)については起こるが、クロム(Ｃｒ)や
モリブデン(Ｍｏ)の炭化物中の炭素(Ｃ)については起こ
らないことが認められた。(２)の反応は鉄粉中の炭素
(Ｃ)、クロム(Ｃｒ)やモリブデン(Ｍｏ)の炭化物中の炭
素(Ｃ)の何れについても起こることが判った。(４)の反
応は、(２)と同様に何れの炭素(Ｃ)についても起こるこ
とが判明した。そこで、次の実験を実施した。On the premise of the above four reactions, an experiment was conducted to examine whether or not a reduction reaction of iron (Fe) with a carbide of chromium (Cr) or molybdenum (Mo) occurs. It was found that the reaction (1) occurs for carbon (C) contained in iron powder, but does not occur for carbon (C) in chromium (Cr) or molybdenum (Mo) carbide. The reaction of (2) is carbon in iron powder
(C) and carbon (C) in carbides of chromium (Cr) and molybdenum (Mo) were found to occur. The reaction (4) was found to occur for any carbon (C) as in (2). Therefore, the following experiment was performed.

【００１１】カーボニル鉄粉(平均粒径＝３.４μｍ)の
みの原料粉末からプレス成形法により第１成形体を成形
し、カーボニル鉄粉に炭化物である１.１％のＣｒ3Ｃ2
粉(平均粒径＝２μｍ)を添加した原料粉末からプレス成
形法により第２成形体を成形した。この第１成形体およ
び第２成形体を、Ａｒ雰囲気で５５０℃まで加熱した場
合の炭素(Ｃ)と酸素(Ｏ)の分析値は、第１成形体では
Ｃ：０.６３％，Ｏ：０.３２％であり、第２成形体では
Ｃ：０.７９％，Ｏ：０.３７％であった。この焼結条件
では、(１),(３),(５)の反応が僅かに生じていることが
判る。次に、第１成形体および第２成形体を、Ａｒ＋５
０％Ｈ2雰囲気で５５０℃まで加熱した場合の炭素(Ｃ)
と酸素(Ｏ)の分析値は、第１成形体ではＣ：０.０１２
％，Ｏ：０.０９４％であり、第２成形体ではＣ：０.１
６３％，Ｏ：０.２１８％であった。この焼結条件で
は、第１成形体の炭素量が著しく低下しており、(４)の
反応が主に生じていることが理解される。なお、水素
(Ｈ)を含有する雰囲気での焼結条件では、第２成形体の
炭素(Ｃ)が炭化物(Ｃｒ3Ｃ2)で添加した量だけ略残留し
ていた。すなわち、(４)の反応は鉄粉中の炭素(Ｃ)につ
いては生じているが、炭化物中の炭素(Ｃ)については反
応が生じておらず、炭化物中の炭素(Ｃ)のみが残留した
ものと判断される。A first compact is formed from a raw material powder of only carbonyl iron powder (average particle size = 3.4 μm) by a press molding method, and 1.1% of Cr 3 C 2 which is a carbide is added to the carbonyl iron powder.
A second compact was formed from the raw material powder to which the powder (average particle size = 2 μm) was added by a press molding method. When the first compact and the second compact were heated to 550 ° C. in an Ar atmosphere, the analysis values of carbon (C) and oxygen (O) were 0.63% for the first compact and O: 0.32%, and C: 0.79% and O: 0.37% in the second molded body. Under these sintering conditions, it can be seen that the reactions of (1), (3), and (5) slightly occur. Next, the first molded body and the second molded body were formed by Ar + 5
Carbon (C) when heated to 550 ° C in 0% H 2 atmosphere
The analysis values of oxygen and oxygen (O) indicate that C: 0.012 in the first molded body.
%, O: 0.094%, and C: 0.1 in the second molded body.
63%, O: 0.218%. Under these sintering conditions, it is understood that the amount of carbon in the first compact is significantly reduced, and the reaction (4) mainly occurs. In addition, hydrogen
Under the sintering conditions in the atmosphere containing (H), carbon (C) of the second compact was substantially left in an amount added by carbide (Cr 3 C 2 ). That is, the reaction of (4) occurs for carbon (C) in iron powder, but no reaction occurs for carbon (C) in carbide, and only carbon (C) in carbide remains. Is determined.

【００１２】なお、Ａｒ雰囲気で加熱した第１成形体お
よび第２成形体を７５０℃以上の焼結温度まで加熱し、
(２)の反応のみが生ずると、第１成形体では炭素(Ｃ)が
０.３９％残留し、第２成形体では炭素(Ｃ)が０.５１％
残留する。しかるに、Ａｒ＋５０％Ｈ2雰囲気で加熱し
た第１成形体および第２成形体を、その雰囲気をＡｒ雰
囲気に置換したもとで７５０℃以上の焼結温度まで加熱
すると、(２)の反応によって残留している炭素(Ｃ)は殆
ど無くなるか、あるいは酸素(Ｏ)が残留することにな
る。すなわち、炭化物中の炭素(Ｃ)のみを残留させたと
しても、Ｃ＋[Ｏ]→ＣＯ・・・(２)の反応で残留する炭素
(Ｃ)を除去してしまうだけの酸素(Ｏ)が残留しているた
め、炭素(Ｃ)を焼結品に残留させることができない。従
って、炭化物中の炭素(Ｃ)のみを残留させるためには、
予め酸素(Ｏ)を充分に取除くことが重要であることを突
き止めた。The first compact and the second compact heated in an Ar atmosphere are heated to a sintering temperature of 750 ° C. or more.
When only the reaction of (2) occurs, 0.31% of carbon (C) remains in the first compact and 0.51% of carbon (C) in the second compact.
Remains. However, when the first molded body and the second molded body heated in an Ar + 50% H 2 atmosphere are heated to a sintering temperature of 750 ° C. or more while replacing the atmosphere with an Ar atmosphere, the reaction of (2) causes a residual. Almost no carbon (C) is left, or oxygen (O) remains. That is, even if only carbon (C) in the carbide remains, the carbon remaining in the reaction of C + [O] → CO (2)
Since oxygen (O) enough to remove (C) remains, carbon (C) cannot remain in the sintered product. Therefore, in order to leave only carbon (C) in the carbide,
It has been found in advance that it is important to sufficiently remove oxygen (O).

【００１３】すなわち、鉄粉＋炭化物(５５０℃前後で
水素(Ｈ)によって還元されない物)の原料粉末からなる
成形体を、以下の条件(図１参照)で焼結することによ
り、ベース粉末に添加した炭化物中の炭素(Ｃ)のみを残
留させ、目的の炭素量の焼結体を得ることができるもの
である。 水素０％のＡｒ雰囲気としたもとで、成形体を３００
〜１０００℃の温度に加熱し、Ｃ＋２[Ｏ]→ＣＯ2・・・
(１)および２[Ｏ]→Ｏ2・・・(５)の反応により酸素量を充
分低下させる。７５０℃以上ではＣ＋[Ｏ]→ＣＯ・・・
(２)の反応も生ずるが、この時点での酸素量は少なく、
影響は小さい。しかし鉄粉に含有される酸素(Ｏ)が除去
され、炭素量制御は容易になる場合がある。なお、温度
を上げ過ぎると密度が上昇し、後の反応((４)の反応)を
阻害するので、この時点の密度を９０％以上にすること
が望ましい。 次に、水素０％のＡｒ雰囲気のまま、(４)の反応が起
きる３００〜６００℃の温度まで降温する。 そして、３００〜６００℃の温度に保持したまま雰囲
気をＡｒ＋５０％Ｈ2に置換して所要時間(例えば１〜３
時間)保持し、Ｃ＋２Ｈ2→ＣＨ4・・・(４)の反応を起こさ
せることで、鉄粉中の炭素(Ｃ)を除去する。 次に、３００〜６００℃の温度に保持したまま、雰囲
気を再び水素０％のＡｒまたは真空に置換する。 更に、このままの雰囲気で、焼結温度まで昇温して焼
結する。このとき、予め酸素(Ｏ)は殆ど除去されている
から、Ｃ＋[Ｏ]→ＣＯ・・・(２)の反応によって残留して
いる炭化物中の炭素(Ｃ)が除去されることはない。な
お、９００℃より高温ではＣ＋２Ｈ2→ＣＨ4・・・(４)の
反応は起きないので、該温度より高温となった段階で水
素(Ｈ)を含有する雰囲気に置換してもよい。That is, a compact made of a raw material powder of iron powder + carbide (a substance not reduced by hydrogen (H) at about 550 ° C.) is sintered under the following conditions (see FIG. 1) to obtain a base powder. Only the carbon (C) in the added carbide is left, and a sintered body having a desired carbon content can be obtained. Under an Ar atmosphere of 0% hydrogen, the compact was
Heat to a temperature of ~ 1000 ° C and C + 2 [O] → CO 2 ...
The amount of oxygen is sufficiently reduced by the reaction of (1) and 2 [O] → O 2 (5). C + [O] → CO at 750 ℃ or more
The reaction of (2) also occurs, but the amount of oxygen at this point is small,
The effect is small. However, oxygen (O) contained in the iron powder is removed, and the control of the amount of carbon may be facilitated. If the temperature is too high, the density increases, and the subsequent reaction (reaction (4)) is hindered. Therefore, it is desirable that the density at this point be 90% or more. Next, the temperature is lowered to a temperature of 300 to 600 [deg.] C. at which the reaction (4) occurs in an Ar atmosphere of 0% hydrogen. Then, while maintaining the temperature at 300 to 600 ° C., the atmosphere is replaced with Ar + 50% H 2 and the required time (for example, 1 to 3)
(Time), and the reaction of C + 2H 2 → CH 4 (4) is caused to remove carbon (C) in the iron powder. Next, while maintaining the temperature at 300 to 600 ° C., the atmosphere is replaced with Ar of 0% hydrogen or vacuum again. Further, in the atmosphere as it is, the temperature is raised to the sintering temperature and sintering is performed. At this time, most of the oxygen (O) has been removed in advance, so that the carbon (C) in the remaining carbide is not removed by the reaction of C + [O] → CO (2). Since the reaction of C + 2H 2 → CH 4 (4) does not occur at a temperature higher than 900 ° C., an atmosphere containing hydrogen (H) may be substituted at a stage when the temperature becomes higher than the temperature.

【００１４】以上のように焼結時における温度および雰
囲気を制御することにより、ベース粉末に添加した炭化
物中の炭素(Ｃ)のみを焼結体中に残留させることができ
るものである。すなわち、炭化物の添加量を変えること
により、焼結体中の炭素量を正確に制御することができ
る。また、原料取扱い中に微粉であるが故の酸化が多少
生じても、焼結体中の炭素量は殆ど変化しない利点を有
する。By controlling the temperature and atmosphere during sintering as described above, only carbon (C) in the carbide added to the base powder can be left in the sintered body. That is, the amount of carbon in the sintered body can be accurately controlled by changing the amount of carbide added. Further, there is an advantage that the carbon content in the sintered body is hardly changed even if some oxidation occurs due to the fine powder during handling of the raw material.

【００１５】[0015]

【実験例について】図４の表に示す(Ａ)〜(Ｅ)の組成に
係る原料粉末に、７.０重量％のポリプロピレンとワッ
クスをベースにしたバインダを添加して１６０℃で加圧
混練を１時間行なった原料から、射出成形法により引張
試験片を成形した。この試験片を４０℃のノルマルヘキ
サン中に２４時間浸漬して、ワックス成分を除去した。
更に、窒素雰囲気で３９０℃まで加熱し、バインダ全体
の９１％を除去した。これを以下に示す〜の条件で
焼結し、炭素(Ｃ)および酸素(Ｏ)の分析を夫々実施し
た。[Experimental example] 7.0 wt% of a binder based on polypropylene and wax was added to the raw material powders having the compositions (A) to (E) shown in the table of FIG. Was performed for 1 hour to form a tensile test piece by an injection molding method. This test piece was immersed in normal hexane at 40 ° C. for 24 hours to remove the wax component.
Furthermore, heating was performed to 390 ° C. in a nitrogen atmosphere to remove 91% of the entire binder. This was sintered under the following conditions and carbon (C) and oxygen (O) were each analyzed.

【００１６】焼結条件：真空からＡｒ雰囲気に置換し
たもとで、５５℃／ｈの速さで７３２℃まで昇温し、該
温度(７３２℃)で１時間保持する。次に、１００℃／ｈ
の速さで５５０℃まで降温し、Ａｒ雰囲気からＡｒ＋５
０％Ｈ2雰囲気に置換したもとで、該温度(５５０℃)で
３時間保持する。次いで、Ａｒ＋５０％Ｈ2雰囲気から
Ａｒ雰囲気に置換したもとで、５５℃／ｈの速さで９５
０℃まで昇温し、該温度(９５０℃)で１時間保持する。
更に、１５０℃／ｈの速さで１３００℃まで昇温し、該
温度(１３００℃)で２時間保持した後に、炉冷する(図
３参照)。Sintering conditions: The temperature is raised to 732 ° C. at a rate of 55 ° C./h under the condition that the vacuum is replaced with an Ar atmosphere, and the temperature is maintained at that temperature (732 ° C.) for 1 hour. Next, 100 ° C / h
The temperature is lowered to 550 ° C. at a speed of
The temperature is maintained at that temperature (550 ° C.) for 3 hours while replacing the atmosphere with a 0% H 2 atmosphere. Next, at a rate of 55 ° C./h, 95% H 2 atmosphere was replaced with an Ar atmosphere.
The temperature is raised to 0 ° C. and maintained at that temperature (950 ° C.) for 1 hour.
Further, the temperature is raised to 1300 ° C. at a rate of 150 ° C./h, and the temperature is maintained at the temperature (1300 ° C.) for 2 hours, followed by furnace cooling (see FIG. 3).

【００１７】焼結条件：真空からＡｒ＋５０％Ｈ2雰
囲気に置換したもとで、５５℃／ｈの速さで５５０℃ま
で昇温し、該温度(５５０℃)で１時間保持する。次に、
４５℃／ｈの速さで７３２℃まで昇温し、該温度(７３
２℃)で１時間保持する。次いで、５５℃／ｈの速さで
９５０℃まで昇温し、該温度(９５０℃)で１時間保持す
る。更に、１５０℃／ｈの速さで１３００℃まで昇温
し、該温度(１３００℃)で２時間保持した後に、炉冷す
る。Sintering conditions: The temperature is raised to 550 ° C. at a rate of 55 ° C./h under the atmosphere replaced by an atmosphere of Ar + 50% H 2 from vacuum, and the temperature is maintained at that temperature (550 ° C.) for 1 hour. next,
The temperature was raised to 732 ° C. at a rate of 45 ° C./h, and the temperature (73
(2 ° C.) for 1 hour. Next, the temperature is raised to 950 ° C. at a rate of 55 ° C./h and maintained at the temperature (950 ° C.) for 1 hour. Further, the temperature is raised to 1300 ° C. at a rate of 150 ° C./h, and the temperature is maintained at the temperature (1300 ° C.) for 2 hours, followed by furnace cooling.

【００１８】焼結条件：真空からＡｒ雰囲気に置換し
たもとで、５５℃／ｈの速さで５５０℃まで昇温し、該
温度(５５０℃)で１時間保持する。次に、４５℃／ｈの
速さで７３２℃まで昇温し、該温度(７３２℃)で１時間
保持する。次いで、５５℃／ｈの速さで９５０℃まで昇
温し、該温度(９５０℃)で１時間保持する。更に、１５
０℃／ｈの速さで１３００℃まで昇温し、該温度(１３
００℃)で２時間保持した後に、炉冷する。Sintering conditions: The temperature is raised to 550 ° C. at a rate of 55 ° C./h under a vacuum atmosphere replaced with an Ar atmosphere, and the temperature is maintained at that temperature (550 ° C.) for 1 hour. Next, the temperature is raised to 732 ° C. at a rate of 45 ° C./h and maintained at the temperature (732 ° C.) for 1 hour. Next, the temperature is raised to 950 ° C. at a rate of 55 ° C./h and maintained at the temperature (950 ° C.) for 1 hour. In addition, 15
The temperature was raised to 1300 ° C. at a rate of 0 ° C./h, and the temperature (13
(00 ° C.) for 2 hours, and then cooled in a furnace.

【００１９】図４の表に示す各焼結体の炭素(Ｃ)および
酸素(Ｏ)の分析値から、本発明である焼結条件で焼結
した焼結体は、添加した炭化物中の炭素量が略残留して
おり、目的を達している。また、通常のＦｅ系の焼結条
件である焼結条件では、炭素(Ｃ)は殆ど残留していな
い。更に、全てをＡｒ雰囲気で焼結した焼結条件で
は、鉄粉中の酸素(Ｏ)を充分除去することができず、多
量の炭素(Ｃ)が残留することが判明する。From the analysis values of carbon (C) and oxygen (O) of each sintered body shown in the table of FIG. 4, the sintered body sintered under the sintering conditions of the present invention shows that the carbon in the added carbide The amount is almost left, and the purpose is achieved. Further, under the sintering conditions which are the usual sintering conditions of the Fe system, carbon (C) hardly remains. Furthermore, under the sintering conditions in which all were sintered in an Ar atmosphere, it was found that oxygen (O) in the iron powder could not be sufficiently removed and a large amount of carbon (C) remained.

【００２０】また、焼結条件で得られた焼結体をＲＸ
ガス中で９００℃の温度で２時間保持する条件で浸炭処
理し、次に８３０℃の温度で３０分保持した後油冷する
浸炭・焼入処理を行なった。更に１６０℃で２時間保持
する焼戻処理を行ない、得られた焼結体の表面硬さを測
定した結果を、図４の表に示した。この結果、炭化物を
添加することなく焼結した(Ａ),(Ｂ)の焼結体の浸炭性
より、炭化物を添加した(Ｃ),(Ｄ),(Ｅ)の焼結体の浸炭
性が良好なことが判明した。The sintered body obtained under the sintering conditions is
Carburizing treatment was performed in a gas at a temperature of 900 ° C. for 2 hours, followed by carburizing and quenching at a temperature of 830 ° C. for 30 minutes followed by oil cooling. Further, a tempering treatment was performed at 160 ° C. for 2 hours, and the surface hardness of the obtained sintered body was measured. The result is shown in the table of FIG. As a result, from the carburizing properties of the sintered bodies (A) and (B) sintered without adding the carbide, the carburizing properties of the sintered bodies (C), (D) and (E) added with the carbide were Turned out to be good.

【００２１】なお、成形体を成形する方法としては、プ
レス成形法や射出成形法に限らず、その他の成形法であ
ってもよい。また炭化物としては、所要温度以下では水
素含有雰囲気で還元されないものであれば、Ｃｒ3Ｃ2や
Ｍｏ2Ｃ以外のものが採用可能である。更に、前述した
焼成条件におけるＡｒ雰囲気を、原理的には真空にして
も同一の効果が得られる。The method for molding the molded body is not limited to the press molding method or the injection molding method, but may be another molding method. As the carbide, any material other than Cr 3 C 2 or Mo 2 C can be used as long as it is not reduced in a hydrogen-containing atmosphere at a required temperature or lower. Further, the same effect can be obtained even if the Ar atmosphere under the above-mentioned firing conditions is in principle vacuum.

【００２２】[0022]

【発明の効果】以上説明した如く、本発明に係る焼結低
合金鋼およびその製造方法によれば、炭素量が正確に制
御された焼結低合金鋼を簡単に製造することができる。
また、原料粉末である鉄粉または鉄粉＋Ｎｉ粉の混合粉
中の炭素量や酸素量に影響されることなく、添加する炭
化物中の炭素量を調整するだけで、焼結低合金鋼の炭素
量を正確に制御することができる。しかも、鉄粉や炭化
物の粉末は簡単に製造し得る利点も有する。As described above, according to the sintered low-alloy steel and the method for producing the same according to the present invention, it is possible to easily produce a sintered low-alloy steel whose carbon content is accurately controlled.
In addition, the carbon content of the sintered low alloy steel is adjusted by adjusting the carbon content in the added carbide without being affected by the carbon content or the oxygen content in the iron powder or the mixed powder of the iron powder and the Ni powder as the raw material powder. The quantity can be controlled precisely. In addition, iron powder and carbide powder have an advantage that they can be easily manufactured.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の好適な実施例に係る焼結低合金鋼の製
造方法の温度と雰囲気との関係を示すグラフ図である。FIG. 1 is a graph showing the relationship between temperature and atmosphere in a method for producing a sintered low alloy steel according to a preferred embodiment of the present invention.

【図２】成形体を焼成する際に生ずる反応と温度との関
係を示す説明図である。FIG. 2 is an explanatory diagram showing a relationship between a reaction that occurs when a molded body is fired and a temperature.

【図３】実験例における温度と雰囲気との関係を示すグ
ラフ図である。FIG. 3 is a graph showing the relationship between temperature and atmosphere in an experimental example.

【図４】実験例における炭素(Ｃ)と酸素(Ｏ)との残留量
および表面硬さを示す表図である。FIG. 4 is a table showing the residual amounts of carbon (C) and oxygen (O) and surface hardness in an experimental example.

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】 鉄粉または鉄粉＋Ｎｉ粉の混合粉に炭化
物を添加した原料粉末から成形され、略炭化物中の炭素
のみを残留させるよう焼結したことを特徴とする焼結低
合金鋼。1. A sintered low alloy steel formed from a raw material powder obtained by adding carbide to iron powder or a mixed powder of iron powder and Ni powder, and sintered so as to leave substantially only carbon in carbide. 【請求項２】 前記炭化物は、Ｃｒ3Ｃ2またはＭｏ2Ｃ
である請求項１記載の焼結低合金鋼。2. The method according to claim 1, wherein the carbide is Cr 3 C 2 or Mo 2 C.
The sintered low alloy steel according to claim 1, wherein 【請求項３】 鉄粉または鉄粉＋Ｎｉ粉の混合粉に炭化
物を添加した原料粉末からなる成形体を焼結するに際
し、水素を殆ど含まない雰囲気の下で３００〜１０００
℃に昇温して所要時間保持し、その後３００〜６００℃
に降温すると共に水素分圧の高い雰囲気に置換した下で
所要時間保持し、次いで少なくとも水素による炭化物の
還元反応が起きる温度までは水素を殆ど含まない雰囲気
に保持したまま焼結温度まで昇温することを特徴とする
焼結低合金鋼の製造方法。3. When sintering a compact made of a raw material powder obtained by adding a carbide to iron powder or a mixed powder of iron powder and Ni powder, 300 to 1000 in an atmosphere containing almost no hydrogen.
℃ to maintain the required time, then 300-600 ℃
And then hold for a required time under a high hydrogen partial pressure atmosphere, and then raise the temperature to the sintering temperature while maintaining the atmosphere containing almost no hydrogen until at least the temperature at which the reduction of carbides by hydrogen occurs. A method for producing a sintered low-alloy steel, comprising: 【請求項４】 鉄粉または鉄粉＋Ｎｉ粉の混合粉に炭化
物を添加した原料粉末からなる成形体を焼結するに際
し、水素０％のＡｒ雰囲気の下で３００〜１０００℃に
昇温して所要時間保持し、その後３００〜６００℃に降
温すると共に水素５０％のＡｒ雰囲気に置換した下で所
要時間保持し、次いで水素０％のＡｒ雰囲気に置換した
下で焼結温度まで昇温することを特徴とする焼結低合金
鋼の製造方法。4. When sintering a compact made of a raw material powder obtained by adding carbide to iron powder or a mixed powder of iron powder and Ni powder, the temperature is raised to 300 to 1000 ° C. in an Ar atmosphere of 0% hydrogen. Holding for a required time, then lowering the temperature to 300 to 600 ° C. and holding for a required time while replacing the atmosphere with 50% hydrogen in an Ar atmosphere, and then raising the temperature to a sintering temperature while replacing the atmosphere with an atmosphere of 0% hydrogen. A method for producing a sintered low alloy steel characterized by the above-mentioned. 【請求項５】 前記炭化物は、Ｃｒ3Ｃ2またはＭｏ2Ｃ
である請求項３または４記載の焼結低合金鋼の製造方
法。5. The method according to claim 1, wherein the carbide is Cr 3 C 2 or Mo 2 C.
The method for producing a sintered low alloy steel according to claim 3 or 4, wherein
JP20112296A 1996-07-10 1996-07-10 Sintered low alloy steel and its production Pending JPH1025533A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP20112296A JPH1025533A (en) 1996-07-10 1996-07-10 Sintered low alloy steel and its production

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP20112296A JPH1025533A (en) 1996-07-10 1996-07-10 Sintered low alloy steel and its production

Publications (1)

Publication Number Publication Date
JPH1025533A true JPH1025533A (en) 1998-01-27

Family

ID=16435782

Family Applications (1)

Application Number Title Priority Date Filing Date
JP20112296A Pending JPH1025533A (en) 1996-07-10 1996-07-10 Sintered low alloy steel and its production

Country Status (1)

Country Link
JP (1) JPH1025533A (en)

Similar Documents

Publication Publication Date Title
JP6212632B2 (en) Method for producing a steel compact
TWI542707B (en) Iron based powders for powder injection molding
US6358298B1 (en) Iron-graphite composite powders and sintered articles produced therefrom
EP0960953A2 (en) Alloy steel powders, sintered bodies and method
US8071015B2 (en) Process for producing porous metal body
US4436696A (en) Process for providing a uniform carbon distribution in ferrous compacts at high temperatures
US2352316A (en) Method of producing shaped bodies from powdery ferrous material
JPH1025533A (en) Sintered low alloy steel and its production
JP2588057B2 (en) Manufacturing method of mold material for mold
JPH0257606A (en) Stainless steel fine powder and sintering material
JP2743974B2 (en) Control method of carbon content and oxygen content of degreased molded body in metal powder injection molding method
JPH0364402A (en) Method for controlling carbon content of metallic injection molding
US5162099A (en) Process for producing a sintered compact from steel powder
JP2004263294A (en) Alloy steel powder having improved sintering property for metal injection molding and sintered body
JPH0472004A (en) Manufacture of porous metallic mold
JP2557870B2 (en) Manufacturing method of tough sintered member
JPH03173702A (en) Production of sintered body
dePoutiloff et al. Sintering of stainless steels
JPS6330395B2 (en)
JPH07243008A (en) Steel sintered compact
JPH09202934A (en) Production of stainless steel sintered body
KR970002093B1 (en) Method of sintering object
JPH03271302A (en) Manufacture of powder sintered product
JP2766427B2 (en) Method for producing iron-chromium sintered soft magnetic material
CN116024501A (en) High-speed steel and preparation method and application thereof