JP3708562B2 - Powder sintered electromagnetic stainless steel - Google Patents
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- JP3708562B2 JP3708562B2 JP26243993A JP26243993A JP3708562B2 JP 3708562 B2 JP3708562 B2 JP 3708562B2 JP 26243993 A JP26243993 A JP 26243993A JP 26243993 A JP26243993 A JP 26243993A JP 3708562 B2 JP3708562 B2 JP 3708562B2
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- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
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- H01F1/14766—Fe-Si based alloys
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Description
【０００１】
【産業上の利用分野】
この発明は、優れた耐食性と磁気特性とを兼ね備えた焼結電磁ステンレス鋼に関するものであり、特に自動車の電子制御式４輪アンチロックブレーキシステムにおける車輪速センサのロータをはじめとして、耐食性を必要とされる電磁弁、各種磁気シールド、ヨーク等の材料として最適な粉末焼結電磁ステンレス鋼を提案しようとするものである。
【０００２】
【従来の技術】
アンチロックブレーキシステム（ＡＢＳ）は、高い信頼性を有するブレーキシステムとして、近年とみに搭載される車種が拡大されつつある。このＡＢＳにおける車輪速センサとしては、磁束の変化を利用した非接触型の可変磁気抵抗方式が多く用いられている。図１の模式図で、車輪速センサの構造と原理を説明すると、歯車の形をした強磁性体のトーンホイール１と永久磁石２とを間隙をおいて近接配置し、この間隙に磁気検出素子としてコイル３を巻回したポールピース（電極）４を配置する。トーンホイール１が車輪とともに回転することにより、永久磁石から発生している磁束が変化し、コイル３に交流が発生する。この交流電圧は、図２に電圧の時間変化をグラフで示すように、回転速度に比例して周期が変化するので、時間当たりの周期を数えることで速度を検出できるのである（自動車技術ハンドブック、２，社団法人自動車技術会編）。
【０００３】
このような車輪速センサのトーンホイール、すなわちロータは一般に、鉄系粉末焼結品を材料として、耐食性向上の目的のために水蒸気処理やめっき等の表面処理を施したものが使用されている。
【０００４】
【発明が解決しようとする課題】
ところで、近年、冬季におけるスパイクタイヤの使用による道路粉塵公害が深刻化したため、緊急車以外の車両のスパイクタイヤの使用が禁止された。そして、それに伴って除雪融雪態勢も強化され、塩化マグネシウムや塩化カルシウム等の融雪剤が大量に使用されるようになってきた。これらの塩化物は、非常に腐食性が高いことから、自動車部品材料等には、上述の融雪剤が散布された道路を走行することも想定して、特に高耐食性であることが要求される。これは、車輪速センサのロータも例外ではなく、耐食性を高めるための対策として、既に述べたとおり表面処理が行われていた。
【０００５】
しかしながら、車輪速センサのロータは、その構造上、車体の下にむき出しで使用される場合が多く、単に表面処理を施しただけのロータでは小石や砂が直接ロータに衝突して表面処理被膜を損傷させる結果、錆発生の起点になる危険性が高く、信頼性に欠けていた。結局のところ、要求される耐食性を満足するには、ロータ自体が高い耐食性を具備することが必要である。
【０００６】
耐食性の高い材料としては、ステンレス鋼を直ちに挙げることができ、18Cr−８NiのSUS 304 鋼や18Cr−12Ni−２MoのSUS 316 鋼が汎用されているが、これらのステンレス鋼はいずれも、耐食性に関しては極めて優れているが、非磁性であるため、車輪速センサのロータには使用することができない。
【０００７】
このように、車輪速センサのロータ等の使途に望まれる、SUS 304 鋼程度の優れた耐食性並び良好な軟磁気特性及び安価に製造するための良好な焼結性を兼ね備えた合金粉末は、なかったのである。
【０００８】
そこでこの発明の目的は、発明者らの研究開発によって上記の望まれていた新規な合金を提案することにあり、すなわち、大量に使用される融雪剤たる塩化物による腐食に耐え、しかも優秀な軟磁気特性を有し、さらにＡＢＳ装置の車輪速センサのロータを製造する際の良好な焼結性をも兼ね備えた高耐食性電磁ステンレス鋼粉末及び高耐食性焼結電磁ステンレス鋼を提案するものである。
【０００９】
【課題を解決するための手段】
この発明の要旨構成は、次のとおりである。
(1) Ｃ：0.001 〜0.1 wt％（以下、単に％で示す）、Si：0.79〜5.0 ％、Mn：0.01〜0.50％、Cr：10〜30％、Ni：0.01〜3.0％、Mo：0.01〜5.0％、Cu：0.01〜3.0％及びＯ：0.30％以下を含有し、残部はFe及び不可避的不純物からなる粉末焼結電磁ステンレス鋼（第１発明）。
【００１０】
(2) Ｃ：0.001〜0.1％、Si：0.79〜5.0 ％、Mn：0.01〜0.50％、Cr：10〜30％、Ni：0.01〜3.0 ％、Mo：0.01〜5.0 ％、Cu：0.01〜3.0 ％及びＯ：0.30％以下を含み、かつ切削性を加味する目的で副成分としてＰ：1.0 ％以下、Ca：1.0 ％以下、Sn：1.0 ％以下及びＳ：1.0 ％以下のうちの１種又は２種以上を合計で 0.001〜4.0 ％含有し、残部はFe及び不可避的不純物からなる粉末焼結電磁ステンレス鋼（第２発明）。
【００１１】
(3) Ｃ：0.001〜0.1％、Si：0.79〜5.0 ％、Mn：0.01〜0.50％、Cr：10〜30％、Ni：0.01〜3.0 ％、Mo：0.01〜5.0 ％、Cu：0.01〜3.0 ％及びＯ：0.30％以下を含み、かつじん性向上のために副成分として希土類元素のうちの１種又は２種以上を合計で 0.001〜0.5 ％含有し、残部はFe及び不可避的不純物からなる粉末焼結電磁ステンレス鋼（第３発明）。
【００１２】
(4) Ｃ：0.001〜0.1％、Si：0.79〜5.0 ％、Mn：0.01〜0.50％、Cr：10〜30％、Ni：0.01〜3.0 ％、Mo：0.01〜5.0 ％、Cu：0.01〜3.0 ％及びＯ：0.30％以下を含み、かつ切削性を加味する目的で副成分としてＰ：1.0 ％以下、Ca：1.0 ％以下、Sn：1.0 ％以下及びＳ：1.0 ％以下のうちの１種又は２種以上を合計で 0.001〜4.0 ％含有し、さらに、じん性向上のために副成分として希土類元素のうちの１種又は２種以上を合計で 0.001〜0.5 ％含有し、残部はFe及び不可避的不純物からなる粉末焼結電磁ステンレス鋼（第４発明）。
【００１３】
【作用】
以下、この発明をより具体的に説明する。
まず、この発明において合金組成を上記の範囲に限定した理由について述べる。
Ｃ：0.001 〜0.1 ％
Ｃは、この発明の合金粉末にあっては、非常に有用な成分であって、合金中にＣが存在することによって焼結過程で粉末中のO2に効果的に作用し、強力な脱酸剤として働く。かかる作用を有効に発揮させるためる下限として0.001 ％とする一方、Ｃが焼結後の合金中に含まれると耐食性、磁気特性を著しく阻害するので、上限を0.1 ％とした。
【００１４】
Si：0.79〜5.0 ％
Siは、焼結後の合金中にあって、Cr系のフェライトステンレス鋼の磁気特性を有効に改善する。また、比抵抗を増加させ、高周波領域でのレスポンス特性に有用であるが、Si含有量が0.79 ％未満では磁気特性、比抵抗増加効果が十分でなく、一方、５％を超えると粉末の硬度が増加し、成形性を著しく阻害するので上限を５％とした。
【００１５】
Mn：0.01〜0.50％
Mnは、この発明の合金鋼にあって、脱酸剤として効果的な成分であるが、0.01％に満たないとその効果も十分ではなく、また、0.5 ％を超えると粉末の酸素量が増大し、さらに磁気特性を阻害するので、上限を0.50％とした。
【００１６】
Cr：10〜30％
Crは、この発明の合金の主成分の一であり、耐食性、磁気特性、電気抵抗を最も効果的に向上させる。しかし、Cr量が10.0％に満たないと、その効果は十分ではないのでCr量の下限を10.0％とした。また、Cr量が30.0％を超えると、磁気特性の劣化（具体的には、磁束密度の低下）を招くので、上限を30.0％とした。
【００１７】
Ni：0.01〜3.0 ％
Niは、この発明の合金においてCr，Mo及びCuと共存することによって、著しく耐食性を向上させる。しかし、Ni量が0.01％に満たないとその効果も十分ではなく、また、3.0 ％を超えると磁気特性を劣化させるばかりでなく、高価にもなるため、上限を3.0 ％とした。
【００１８】
Mo：0.01〜5.0 ％
Moは、Cr，Cu及びNiと共存することによって、著しく耐食性を向上させる成分である。また、Moの少量添加によって、合金の保持力（Hc）が改善される。しかし、Mo量が0.01％に満たないと、その効果は顕著ではなく、また、5.0 ％を超えると焼結性を阻害するばかりでなく、高価にもなるので、0.01〜5.0 ％に限定した。
【００１９】
Cu：0.01〜3.0 ％
Cuは、Cr，Mo及びNiと共存することによって、著しく耐食性を向上させるばかりでなく、少量の添加で焼結性を非常に改善し、しかも磁気特性の劣化も少ない。しかし、Cu量が0.01％に満たないと、その効果も十分でなく、また、添加量が多くなると磁気特性の劣化も大きくなるので、0.01〜3.0 ％に限定した。
【００２０】
Ｏ：0.30％以下
Ｏは、水噴霧法、ガス噴霧法等で合金粉末を製造する過程で、不可避に含まれる不純物であり、Ｏが多量に鋼中に含まれると、磁気特性、耐食性を著しく阻害する。この発明では、粉末中のＣ量を比較的高濃度とし、真空中で焼結することにより、焼結過程で効果的に脱酸させるが、0.30％以下であれば、上記した不都合も小さいので、0.30％以下とした。
【００２１】
第２発明、第４発明においては、上記の成分に加えて、切削性を加味するために副成分としてＰ：1.0 ％以下、Ca：1.0 ％以下、Sn：1.0 ％以下及びＳ：1.0 ％以下のうちの１種又は２種以上を合計で0.001 〜4.0 ％含有させる。しかし、いずれも規定量以上の含有では、耐食性、磁気特性、焼結性を阻害する。また、切削性向上の効果を得るための下限として合計量で0.001 ％以上とした。
【００２２】
第３発明、第４発明においては、さらに、じん性向上のために副成分として希土類元素（Sc、Ｙ及びランタノイド元素）のうちの１種又は２種以上を合計で0.001 〜0.5 ％含有させる。しかし、いずれも規定量以上の含有では、耐食性、磁気特性、焼結性を阻害する。また、じん性向上の効果を得るための下限として合計量で0.001 ％以上とした。
【００２３】
この発明の高耐食性電磁ステンレス鋼粉末及び高耐食性焼結電磁ステンレス鋼の製造方法の一例としては、次のとおりである。
粉末製造方法：
溶解方法 電気炉溶解又は高周波誘導溶解
精錬方法 ＡＯＤ又はＶＯＤの精錬を行なっても良い。
噴霧方法 水噴霧法、（ガス噴霧法でも可）
粉末分布例（％）：表１のとおり
【表１】
プレス圧：５〜20トン／cm2
焼結条件：1150〜1250℃×１〜３Hr 真空中焼結
【００２４】
【実施例】
表１に示した各組成になる供試鋼（No. １〜16）を誘導加熱溶解して20kg調製した後、水アトマイズ法によりステンレス合金粉末を作製し、各粉末の、100 メッシュアンダー部分のみを試料粉末とした。
【００２５】
【表２】
各粉末を、無潤滑又は１％ステアリン酸鉛を潤滑剤として加圧力５〜７t/cm2 でプレス後、1150〜1250℃の温度でかつ真空又は水素気流中で焼結を行った。
かくして得られた試料について、磁気特性、耐食性について調べた。磁気特性については、外径10mm、内径5.5 mmφ、厚み５mmのリング状試料を焼結作成し、850 〜950 ℃で真空中で磁気焼鈍後、Ｂ−Ｈループトレーサで直流特性を測定した。また、耐食性は、孔食電位及び塩水噴霧試験により調べた。この孔食電位は、10mmφの試験片を作成し、800 番までサンドペーパで研磨したのち、30℃の3.5 ％NaCl水溶液入での孔食電位を測定したものであり、塩水噴霧試験は、30mmφ、長さ30mmの円筒形試料に焼結後、850 〜950 ℃で磁気焼鈍を施し、その後35℃の５％NaCl水溶液を96時間噴霧してものである。これらの結果を表２に示す。
【００２７】
【表３】
供試鋼No. ７は、Mo，Cu，Niを全く含まない比較例であり、焼結性、磁気特性は良好であるが、孔食電位が−200 mVに示されるように耐食性は十分ではなく、塩水噴霧試験で短時間で全面に錆が発生した。
【００２９】
供試鋼No. ８は、Cr量が10％未満の例であるが、Mo，Cu，Niを含有していても、フェライト組織が安定せずにマルテンサイト組織が部分的に発生し、磁気特性、耐食性が著しく劣化していた。
【００３０】
供試鋼No. ９は、Cr量が30％以上、Si量が５％以上含まれる例であり、粉末焼結過程で割れが発生し、良好な焼結品が得られなかった。なお、小径試料で測定した孔食電位は360 mVと非常に良好であった。
【００３１】
供試鋼No.10は、Niを多量に含むSUS 304 系の合金であり、耐食性はひじょう良好で、孔食電位は300 mVであり、塩水噴霧試験でも全く錆発生は示さなかったが、非磁性であり、目的とする用途には、使用し得ない。
【００３２】
これに対して、この発明によって得られた供試鋼No. １〜６、 11 〜 15は、いずれもがμmが2000以上、Ｈc が2000 A/m以下、Ｂ25が0.8 Ｔ以上と、良好な軟磁気特性を示し、また同時に200 以上の孔食電位を示し、塩水噴霧試験における96時間経過後も、わずかに点食が発生する程度での良好な耐食性を示した。
【００３３】
【発明の効果】
かくしてこの発明の鋼は、塩化物による高腐食性の環境下でも、非常に優れた耐食性を有し、良好な軟磁気特性を兼ね備えた高耐蝕性の粉末焼結電磁ステンレス鋼であって、自動車用ＡＢＳ用車輪速センサのロータや腐食性の雰囲気で使用される電磁弁材料、各種磁気シールド、ヨーク材料として産業界に貢献するものである。
【図面の簡単な説明】
【図１】車輪速センサの構造と原理を説明するための模式図である。
【図２】コイルに発生する電圧の時間変化を示すグラフである。
【符号の説明】
１ トーンホイール
２ 永久磁石
３ コイル
４ ポールピース[0001]
[Industrial application fields]
TECHNICAL FIELD The present invention relates to sintered electromagnetic stainless steel having both excellent corrosion resistance and magnetic characteristics, and particularly requires corrosion resistance including a rotor of a wheel speed sensor in an electronically controlled four-wheel antilock brake system of an automobile. It is intended to propose the most suitable powder sintered electromagnetic stainless steel as a material for electromagnetic valves, various magnetic shields, yokes and the like.
[0002]
[Prior art]
The anti-lock brake system (ABS) is a highly reliable brake system. As a wheel speed sensor in the ABS, a non-contact type variable magnetoresistive method using a change in magnetic flux is often used. Referring to the schematic diagram of FIG. 1, the structure and principle of the wheel speed sensor will be described. A gear-shaped ferromagnetic tone wheel 1 and a
[0003]
In general, a tone wheel of such a wheel speed sensor, that is, a rotor is made of an iron-based powder sintered product and subjected to surface treatment such as steam treatment or plating for the purpose of improving corrosion resistance.
[0004]
[Problems to be solved by the invention]
By the way, in recent years, road dust pollution due to the use of spike tires in winter has become serious, and use of spike tires for vehicles other than emergency vehicles has been prohibited. Along with this, the snow-melting system has been strengthened, and snow melting agents such as magnesium chloride and calcium chloride have been used in large quantities. Since these chlorides are very corrosive, automobile parts materials and the like are required to have particularly high corrosion resistance on the assumption that they travel on roads on which the above-mentioned snow melting agent is applied. . This is not an exception for the rotor of the wheel speed sensor, and surface treatment has been performed as described above as a measure for enhancing the corrosion resistance.
[0005]
However, because of the structure of the rotor of the wheel speed sensor, it is often used barely under the vehicle body. With a rotor that has been subjected to surface treatment, pebbles and sand directly collide with the rotor and form a surface treatment coating. As a result of damage, there was a high risk of starting rust and lacked reliability. After all, to satisfy the required corrosion resistance, the rotor itself needs to have high corrosion resistance.
[0006]
As a material having high corrosion resistance, stainless steel can be mentioned immediately, and 18Cr-8Ni SUS 304 steel and 18Cr-12Ni-2Mo SUS 316 steel are widely used. Is extremely excellent, but it is non-magnetic and cannot be used for the wheel speed sensor rotor.
[0007]
In this way, there is no alloy powder that combines the excellent corrosion resistance of SUS 304 steel, good soft magnetic properties, and good sinterability for inexpensive production, which is desired for the use of rotors for wheel speed sensors, etc. It was.
[0008]
Therefore, an object of the present invention is to propose the above-mentioned new desired alloy by the research and development of the inventors, that is, to withstand corrosion by chloride as a snow melting agent used in large quantities, and to be excellent. The present invention proposes a high corrosion resistance electromagnetic stainless steel powder and a high corrosion resistance sintered electromagnetic stainless steel that have soft magnetic properties and also have good sinterability when manufacturing a rotor of a wheel speed sensor of an ABS device. .
[0009]
[Means for Solving the Problems]
The gist configuration of the present invention is as follows.
(1) C: 0.001 to 0.1 wt% (hereinafter simply expressed as%), Si: 0.79 to 5.0%, Mn: 0.01 to 0.50%, Cr: 10 to 30%, Ni: 0.01 to 3.0%, Mo: 0.01 A powder sintered electromagnetic stainless steel containing ˜5.0%, Cu: 0.01 to 3.0% and O: 0.30% or less, the balance being Fe and unavoidable impurities (first invention).
[0010]
(2) C: 0.001 to 0.1%, Si: 0.79 to 5.0%, Mn: 0.01 to 0.50%, Cr: 10 to 30%, Ni: 0.01 to 3.0%, Mo: 0.01 to 5.0%, Cu: 0.01 to 3.0 % And O: 0.30% or less, and for the purpose of taking into account machinability, P: 1.0% or less, Ca: 1.0% or less, Sn: 1.0% or less and S: 1.0% or less Powder sintered electromagnetic stainless steel containing 2 or more types in total of 0.001 to 4.0%, the balance consisting of Fe and inevitable impurities (second invention).
[0011]
(3) C: 0.001 to 0.1%, Si: 0.79 to 5.0%, Mn: 0.01 to 0.50%, Cr: 10 to 30%, Ni: 0.01 to 3.0%, Mo: 0.01 to 5.0%, Cu: 0.01 to 3.0 % And O: 0.30% or less, and in order to improve toughness, one or more of rare earth elements are contained as a subsidiary component in total of 0.001 to 0.5%, and the balance is composed of Fe and inevitable impurities Powder sintered electromagnetic stainless steel (third invention).
[0012]
(4) C: 0.001 to 0.1%, Si: 0.79 to 5.0%, Mn: 0.01 to 0.50%, Cr: 10 to 30%, Ni: 0.01 to 3.0%, Mo: 0.01 to 5.0%, Cu: 0.01 to 3.0 % And O: 0.30% or less, and for the purpose of taking into account machinability, P: 1.0% or less, Ca: 1.0% or less, Sn: 1.0% or less and S: 1.0% or less Contains a total of 0.001 to 4.0% of 2 or more types, and further contains 0.001 to 0.5% of one or more of rare earth elements as subcomponents in order to improve toughness, the balance being Fe and inevitable Sintered stainless steel made of mechanical impurities (fourth invention).
[0013]
[Action]
Hereinafter, the present invention will be described more specifically.
First, the reason why the alloy composition is limited to the above range in the present invention will be described.
C: 0.001 to 0.1%
C is a very useful component in the alloy powder according to the present invention, and the presence of C in the alloy effectively acts on O 2 in the powder during the sintering process, and has a strong desorption. Works as an acid agent. On the other hand, the lower limit for effectively exhibiting such an action is set to 0.001%. On the other hand, if C is contained in the sintered alloy, the corrosion resistance and magnetic properties are remarkably impaired. Therefore, the upper limit is set to 0.1%.
[0014]
Si: 0.79 to 5.0%
Si is present in the sintered alloy and effectively improves the magnetic properties of Cr ferritic stainless steel. In addition, it increases the specific resistance and is useful for response characteristics in the high frequency range, but if the Si content is less than 0.79 % , the magnetic characteristics and the specific resistance increase effect are not sufficient, while if it exceeds 5%, the hardness of the powder And the upper limit was made 5%.
[0015]
Mn: 0.01-0.50%
Mn is an effective component as a deoxidizer in the alloy steel of the present invention, but its effect is not sufficient if it is less than 0.01%, and if it exceeds 0.5%, the amount of oxygen in the powder increases. In addition, since the magnetic properties are further hindered, the upper limit was made 0.50%.
[0016]
Cr: 10-30%
Cr is one of the main components of the alloy of the present invention and improves the corrosion resistance, magnetic properties, and electrical resistance most effectively. However, if the Cr content is less than 10.0%, the effect is not sufficient, so the lower limit of Cr content was set to 10.0%. Further, if the Cr content exceeds 30.0%, the magnetic characteristics are deteriorated (specifically, the magnetic flux density is lowered), so the upper limit was made 30.0%.
[0017]
Ni: 0.01-3.0%
Ni significantly improves corrosion resistance by coexisting with Cr, Mo and Cu in the alloy of the present invention. However, if the amount of Ni is less than 0.01%, the effect is not sufficient, and if it exceeds 3.0%, not only will the magnetic properties be degraded, but it will also be expensive, so the upper limit was made 3.0%.
[0018]
Mo: 0.01-5.0%
Mo is a component that significantly improves corrosion resistance by coexisting with Cr, Cu and Ni. In addition, the addition of a small amount of Mo improves the holding power (Hc) of the alloy. However, if the amount of Mo is less than 0.01%, the effect is not remarkable, and if it exceeds 5.0%, not only does the sinterability be inhibited, but also the cost becomes high, so it was limited to 0.01 to 5.0%.
[0019]
Cu: 0.01-3.0%
By coexisting with Cr, Mo and Ni, Cu not only significantly improves the corrosion resistance but also greatly improves the sinterability with a small amount of addition, and there is little deterioration in magnetic properties. However, if the amount of Cu is less than 0.01%, the effect is not sufficient, and if the amount of addition increases, the deterioration of the magnetic properties increases, so the content was limited to 0.01 to 3.0%.
[0020]
O: 0.30% or less O is an unavoidable impurity in the process of producing alloy powder by water spraying method, gas spraying method, etc. If a large amount of O is contained in steel, the magnetic properties and corrosion resistance are remarkably increased. Inhibit. In the present invention, the amount of C in the powder is set to a relatively high concentration and sintered in a vacuum to effectively deoxidize during the sintering process. However, if it is 0.30% or less, the above disadvantages are small. And 0.30% or less.
[0021]
In the second and fourth inventions, in addition to the above components, P: 1.0% or less, Ca: 1.0% or less, Sn: 1.0% or less, and S: 1.0% or less as subcomponents in consideration of machinability 1 type or 2 types or more are included in 0.001 to 4.0% in total. However, if the content is more than the prescribed amount, corrosion resistance, magnetic properties and sinterability are impaired. Further, the lower limit for obtaining the effect of improving the machinability is set to 0.001% or more in total amount.
[0022]
In the third and fourth inventions, in order to improve toughness, one or more of rare earth elements (Sc, Y and lanthanoid elements) are contained as a subsidiary component in a total amount of 0.001 to 0.5%. However, if the content is more than the prescribed amount, corrosion resistance, magnetic properties and sinterability are impaired. Further, the lower limit for obtaining the effect of improving toughness was set to 0.001% or more in total.
[0023]
An example of a method for producing the high corrosion resistance electromagnetic stainless steel powder and the high corrosion resistance sintered electromagnetic stainless steel of the present invention is as follows.
Powder production method:
Melting method Electric furnace melting or high frequency induction melting and refining method AOD or VOD may be refined.
Spraying method Water spraying method (gas spraying method is acceptable)
Example of powder distribution (%): as shown in Table 1 [Table 1]
Press pressure: 5 to 20 tons / cm 2
Sintering conditions: 1150 ~ 1250 ℃ × 1 ~ 3Hr Sintering in vacuum [0024]
【Example】
Sample steels (Nos. 1 to 16) having the respective compositions shown in Table 1 were prepared by induction heating and melting to prepare 20 kg, and then a stainless steel alloy powder was produced by the water atomization method. Only 100 mesh under part of each powder Was used as a sample powder.
[0025]
[Table 2]
Each powder was pressed with no lubrication or 1% lead stearate as a lubricant at a pressure of 5 to 7 t / cm 2 and then sintered at a temperature of 1150 to 1250 ° C. and in a vacuum or a hydrogen stream.
The samples thus obtained were examined for magnetic properties and corrosion resistance. Regarding the magnetic characteristics, a ring-shaped sample having an outer diameter of 10 mm, an inner diameter of 5.5 mmφ, and a thickness of 5 mm was prepared by sintering. After magnetic annealing in vacuum at 850 to 950 ° C., DC characteristics were measured with a BH loop tracer. Corrosion resistance was examined by pitting potential and salt spray test. This pitting corrosion potential was measured by preparing a 10mmφ test piece and polishing it with sand paper up to 800, then measuring the pitting corrosion potential with a 3.5% NaCl aqueous solution at 30 ° C. A cylindrical sample having a length of 30 mm is sintered, magnetically annealed at 850 to 950 ° C., and then sprayed with a 5% NaCl aqueous solution at 35 ° C. for 96 hours. These results are shown in Table 2.
[0027]
[Table 3]
Test steel No. 7 is a comparative example that does not contain Mo, Cu, or Ni at all. The sinterability and magnetic properties are good, but the corrosion resistance is not sufficient so that the pitting potential is -200 mV. In the salt spray test, rust was generated on the entire surface in a short time.
[0029]
Test steel No. 8 is an example in which the Cr content is less than 10%, but even if it contains Mo, Cu, Ni, the ferrite structure is not stabilized and a martensite structure is partially generated, resulting in magnetic properties. Characteristics and corrosion resistance were significantly degraded.
[0030]
Test steel No. 9 is an example in which the Cr content is 30% or more and the Si content is 5% or more, and cracks occurred in the powder sintering process, and a good sintered product was not obtained. The pitting corrosion potential measured with a small-diameter sample was very good at 360 mV.
[0031]
Test steel No. 10 is a SUS 304 alloy that contains a large amount of Ni, has very good corrosion resistance, has a pitting corrosion potential of 300 mV, and showed no rusting even in the salt spray test. It is non-magnetic and cannot be used for intended purposes.
[0032]
In contrast, sample steel No. 1 to 6 were obtained by the present invention, 11-15, and both are μm over 2000, H c is less 2000 A / m, B 25 is 0.8 T or more, It showed good soft magnetic properties, and at the same time showed a pitting corrosion potential of 200 or more, and showed good corrosion resistance with a slight pitting after 96 hours in the salt spray test.
[0033]
【The invention's effect】
Thus, the steel of the present invention is a highly corrosion-resistant powder sintered electromagnetic stainless steel having a very excellent corrosion resistance even in a highly corrosive environment due to chloride, and also having a good soft magnetic property. It contributes to the industry as a rotor for ABS wheel speed sensors, electromagnetic valve materials used in corrosive atmospheres, various magnetic shields, and yoke materials.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining the structure and principle of a wheel speed sensor.
FIG. 2 is a graph showing a time change of a voltage generated in a coil.
[Explanation of symbols]
1
Claims (4)
Si：0.79〜5.0 wt％、
Mn：0.01〜0.50wt％、
Cr：10〜30wt％、
Ni：0.01〜3.0 wt％、
Mo：0.01〜5.0 wt％、
Cu：0.01〜3.0 wt％及び
Ｏ：0.30wt％以下
を含有し、残部はFe及び不可避的不純物からなる粉末焼結電磁ステンレス鋼。C: 0.001 to 0.1 wt%,
Si: 0.79 to 5.0 wt%,
Mn: 0.01 to 0.50 wt%
Cr: 10-30 wt%
Ni: 0.01-3.0 wt%,
Mo: 0.01-5.0 wt%,
Powder sintered electromagnetic stainless steel containing Cu: 0.01 to 3.0 wt% and O: 0.30 wt% or less, with the balance being Fe and inevitable impurities.
Si：0.79〜5.0 wt％、
Mn：0.01〜0.50wt％、
Cr：10〜30wt％、
Ni：0.01〜3.0 wt％、
Mo：0.01〜5.0 wt％、
Cu：0.01〜3.0 wt％及び
Ｏ：0.30wt％以下
を含み、かつ
Ｐ：1.0 wt％以下、
Ca：1.0 wt％以下、
Sn：1.0 wt％以下及び
Ｓ：1.0 wt％以下
のうちの１種又は２種以上を合計で0.001 〜4.0 wt％
含有し、残部はFe及び不可避的不純物からなる粉末焼結電磁ステンレス鋼。C: 0.001 to 0.1 wt%,
Si: 0.79 to 5.0 wt%,
Mn: 0.01 to 0.50 wt%
Cr: 10-30 wt%
Ni: 0.01-3.0 wt%,
Mo: 0.01-5.0 wt%,
Cu: 0.01 to 3.0 wt% and O: 0.30 wt% or less, and P: 1.0 wt% or less,
Ca: 1.0 wt% or less,
One or two or more of Sn: 1.0 wt% or less and S: 1.0 wt% or less in total 0.001 to 4.0 wt%
Contains powdered sintered stainless steel made of Fe and inevitable impurities.
Si：0.79〜5.0 wt％、
Mn：0.01〜0.50wt％、
Cr：10〜30wt％、
Ni：0.01〜3.0 wt％、
Mo：0.01〜5.0 wt％、
Cu：0.01〜3.0 wt％及び
Ｏ：0.30wt％以下
を含み、かつ
希土類元素のうちの１種又は２種以上を合計で0.001 〜0.5 wt％
含有し、残部はFe及び不可避的不純物からなる粉末焼結電磁ステンレス鋼。C: 0.001 to 0.1 wt%,
Si: 0.79 to 5.0 wt%,
Mn: 0.01 to 0.50 wt%
Cr: 10-30 wt%
Ni: 0.01-3.0 wt%,
Mo: 0.01-5.0 wt%,
Cu: 0.01 to 3.0 wt% and O: 0.30 wt% or less, and one or more of the rare earth elements in total 0.001 to 0.5 wt%
Contains powdered sintered stainless steel made of Fe and inevitable impurities.
Si：0.79〜5.0 wt％、
Mn：0.01〜0.50wt％、
Cr：10〜30wt％、
Ni：0.01〜3.0 wt％、
Mo：0.01〜5.0 wt％、
Cu：0.01〜3.0 wt％及び
Ｏ：0.30wt％以下
を含み、かつ
Ｐ：1.0 wt％以下、
Ca：1.0 wt％以下、
Sn：1.0 wt％以下及び
Ｓ：1.0 wt％以下
のうちの１種又は２種以上を合計で0.001 〜4.0 wt％
含有し、さらに
希土類元素のうちの１種又は２種以上を合計で0.001 〜0.5 wt％
含有し、残部はFe及び不可避的不純物からなる粉末焼結電磁ステンレス鋼。C: 0.001 to 0.1 wt%,
Si: 0.79 to 5.0 wt%,
Mn: 0.01 to 0.50 wt%
Cr: 10-30 wt%
Ni: 0.01-3.0 wt%,
Mo: 0.01-5.0 wt%,
Cu: 0.01 to 3.0 wt% and O: 0.30 wt% or less, and P: 1.0 wt% or less,
Ca: 1.0 wt% or less,
One or two or more of Sn: 1.0 wt% or less and S: 1.0 wt% or less in total 0.001 to 4.0 wt%
In addition, one or more of rare earth elements in total 0.001 to 0.5 wt%
Contains powdered sintered stainless steel made of Fe and inevitable impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26243993A JP3708562B2 (en) | 1993-10-20 | 1993-10-20 | Powder sintered electromagnetic stainless steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26243993A JP3708562B2 (en) | 1993-10-20 | 1993-10-20 | Powder sintered electromagnetic stainless steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07118816A JPH07118816A (en) | 1995-05-09 |
| JP3708562B2 true JP3708562B2 (en) | 2005-10-19 |
Family
ID=17375809
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26243993A Expired - Lifetime JP3708562B2 (en) | 1993-10-20 | 1993-10-20 | Powder sintered electromagnetic stainless steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3708562B2 (en) |
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| KR20190070738A (en) * | 2017-12-13 | 2019-06-21 | 현대자동차주식회사 | Stainless steel powder and method of manufacturing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH11222652A (en) * | 1997-12-03 | 1999-08-17 | Daido Steel Co Ltd | Stainless steel powder for sintered alloy |
| JP5289807B2 (en) * | 2007-06-11 | 2013-09-11 | 日本ピストンリング株式会社 | Soft magnetic iron-based sintered material |
| JP5196668B2 (en) * | 2008-11-07 | 2013-05-15 | 株式会社日立メタルプレシジョン | Ferritic stainless steel soft magnetic material and manufacturing method thereof |
| JP6722548B2 (en) * | 2016-08-30 | 2020-07-15 | 山陽特殊製鋼株式会社 | Soft magnetic flat powder, magnetic sheet and method for producing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5852001B2 (en) * | 1978-05-26 | 1983-11-19 | 大同特殊鋼株式会社 | free cutting stainless steel powder |
| JPS62133042A (en) * | 1985-12-04 | 1987-06-16 | Daido Steel Co Ltd | Electromagnetic stainless steel |
| JPH0257606A (en) * | 1988-08-20 | 1990-02-27 | Kawasaki Steel Corp | Stainless steel fine powder and sintering material |
| JPH03173749A (en) * | 1989-12-01 | 1991-07-29 | Aichi Steel Works Ltd | Soft magnetic stainless steel for cold forging and its manufacture |
| JP2917450B2 (en) * | 1990-07-24 | 1999-07-12 | 大同特殊鋼株式会社 | Stainless steel with excellent corrosion resistance |
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| KR20190070738A (en) * | 2017-12-13 | 2019-06-21 | 현대자동차주식회사 | Stainless steel powder and method of manufacturing the same |
| KR102391013B1 (en) | 2017-12-13 | 2022-04-27 | 현대자동차주식회사 | Stainless steel powder and method of manufacturing the same |
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| Publication number | Publication date |
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| JPH07118816A (en) | 1995-05-09 |
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