JP2981384B2 - Steel strip carburizing method - Google Patents
Steel strip carburizing methodInfo
- Publication number
- JP2981384B2 JP2981384B2 JP5295465A JP29546593A JP2981384B2 JP 2981384 B2 JP2981384 B2 JP 2981384B2 JP 5295465 A JP5295465 A JP 5295465A JP 29546593 A JP29546593 A JP 29546593A JP 2981384 B2 JP2981384 B2 JP 2981384B2
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- Prior art keywords
- steel strip
- carburizing
- cathode
- steel
- annealing furnace
- Prior art date
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、鋼帯の浸炭方法に関
し、特に、緩目にコイル状に巻いた鋼帯（所謂オープン
コイル）を焼鈍炉中でプラズマ浸炭する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for carburizing a steel strip, and more particularly, to a method for plasma carburizing a steel strip loosely wound into a coil (a so-called open coil) in an annealing furnace.
【０００２】[0002]
【従来の技術】プレス加工用鋼板は、従来Ｃが０．００
１％以上の低Ｃ−リムド鋼や低Ｃ−キルド鋼を箱焼鈍し
て製造されていた。しかし、それは、近年の製鋼技術の
進歩に伴ない極低炭素鋼（Ｃが５０ｐｐｍ以下）が容易
に得られるようになった今日では、極低炭素鋼に必要に
応じてＴｉ，Ｎｂ，Ｂ等の炭化物形成元素を添加して製
造されることが多くなった。ところが、この極低炭素鋼
から製造したプレス加工用鋼板は、そのまま使用する
と、プレス成形後の塗装下地処理、溶接時での熱影響部
（ＨＡＺ）の強度低下、あるいは打ち抜き、剪断時での
バリ発生等の問題があり、種々の改善が望まれた。そこ
で、この鋼板を浸炭して表面層にのみ固溶Ｃを存在させ
て強度を増し、プレス成形用冷延鋼板を提供することが
考えられた。2. Description of the Related Art Conventional steel sheets for press working have a C content of 0.00.
It was manufactured by box annealing 1% or more of low C-rimmed steel and low C-killed steel. However, in recent years, with the progress of steelmaking technology, ultra-low carbon steel (C: 50 ppm or less) has been easily obtained. In many cases, it is produced by adding a carbide-forming element. However, if the steel sheet for press working manufactured from this ultra-low carbon steel is used as it is, the coating base treatment after press forming, the reduction of the strength of the heat-affected zone (HAZ) during welding, or the burr during punching and shearing. There are problems such as occurrence, and various improvements have been desired. Therefore, it was considered to provide a cold-rolled steel sheet for press forming by carburizing this steel sheet so that solid solution C exists only in the surface layer to increase the strength.
【０００３】一方、鋼材の浸炭技術に関しては、従来よ
り一般に一酸化炭素系ガスを使用するガス雰囲気浸炭、
炭化水素系ガスを使用する真空浸炭、プラズマ浸炭が知
られ、特許技術も多々存在している。ところで、鋼帯の
浸炭に関しては、以前から箱焼鈍炉でガス雰囲気浸炭を
実施していた。その技術は、箱焼鈍炉内にコイル状鋼帯
を載置し、長時間浸炭ガス例えば、ＨＮＸガス（Ｈ2 ：
３〜１０％、Ｎ2 ：９７〜９０％、ＣＯ2 ：０．２％以
下、ＣＯ：０．２％以下）、ＡＸガス（Ｈ2 ：７５％，
Ｎ2 ：２５％）等に接触させるものであるが、鋼板表面
から内部へのＣの拡散が浸炭速度を律速するため、浸炭
にようする時間が永いこと、長時間ガス雰囲気下にある
ため浸炭層が１ｍｍ程度と厚くなり、表面が硬くなりす
ぎる欠点があった。[0003] On the other hand, regarding the carburizing technology of steel materials, a gas atmosphere carburizing using carbon monoxide-based gas has been conventionally used.
Vacuum carburization and plasma carburization using hydrocarbon-based gas are known, and there are many patented technologies. By the way, regarding carburizing of steel strip, gas atmosphere carburizing has been carried out in a box annealing furnace. The technique is to place a coiled steel strip in a box annealing furnace and to carry out carburizing gas such as HNX gas (H 2 :
3~10%, N 2: 97~90% , CO 2: 0.2% or less, CO: 0.2% or less), AX gas (H 2: 75%,
N 2 : 25%) etc., but diffusion of C from the steel sheet surface to the inside limits the carburizing rate, so that the carburizing time is long, and the carburizing is performed in a gas atmosphere for a long time. There was a disadvantage that the layer became thick as about 1 mm and the surface became too hard.
【０００４】そこで、最近は鋼板表面の極く薄い部分
（ミクロンの単位）を浸炭する技術が要求されるように
なった（例えば、特開平１−４２３３１号、特開昭６３
−３８５５６号公報）。しかしながら、これらの公報
は、迅速浸炭の考え方（特開昭６３−３８５５６号公報
は、コイル状鋼帯の巻き方をルーズにしてガス雰囲気と
の接触を容易にする）は、開示してあるものの、具体的
な設備構成については何ら提案がなかった。そのため、
本出願人は、特開平４−８８１２６号公報に開示したよ
うに、冷延鋼板８表面の極薄い部分（０．５〜１００μ
ｍ）を浸炭する竪型連続焼鈍炉１６を提案した。それ
は、図２に示すように、竪型連続焼鈍炉１６の加熱帯１
０と冷却帯１３，１４との間にガスシール１５を施した
浸炭帯１２を設けるもので、この竪型連続焼鈍炉１６を
利用すれば、鋼板温度、ガス雰囲気条件、搬送速度及び
冷却条件を制御して浸炭を行うことにより、鋼板の材質
仕様を満足させながら表層浸炭の濃度と深さを所望値に
することができるようになった。Therefore, recently, a technique for carburizing an extremely thin portion (micron unit) of the surface of a steel sheet has been required (for example, Japanese Patent Application Laid-Open Nos. Hei 1-42331 and 63-63).
-38556). However, these publications disclose the concept of rapid carburization (Japanese Patent Application Laid-Open No. S63-38556 discloses that the coiled steel strip is loosely wound to facilitate contact with a gas atmosphere). There were no proposals for specific equipment configurations. for that reason,
As disclosed in Japanese Patent Application Laid-Open No. 4-88126, the present applicant has disclosed a very thin portion (0.5 to 100 μm) of the surface of the cold-rolled steel sheet 8.
m), a vertical continuous annealing furnace 16 for carburizing was proposed. As shown in FIG. 2, the heating zone 1 of the vertical type continuous annealing furnace 16 was used.
The carburizing zone 12 provided with a gas seal 15 is provided between the cooling zone 13 and the cooling zone 13. If this vertical continuous annealing furnace 16 is used, the steel sheet temperature, gas atmosphere condition, transfer speed and cooling condition can be controlled. By controlling and carburizing, the concentration and depth of surface carburization can be set to desired values while satisfying the material specifications of the steel sheet.
【０００５】しかしながら、この設備は、大掛かりであ
り、且つ鋼帯の大量生産用のものである。さらに、浸炭
量を変更するには、前記したように炉温、鋼帯の搬送速
度、雰囲気ガス中のＣＯ濃度を変更する必要があるが、
それら変更の応答性が必ずしも良くないので、浸炭量の
変更時に材質が一定とならず不良品が発生するという問
題が発生した。However, this equipment is large-scale and is for mass production of steel strip. Further, in order to change the carburizing amount, it is necessary to change the furnace temperature, the conveying speed of the steel strip, and the CO concentration in the atmosphere gas as described above.
Since the responsiveness of these changes is not always good, there has been a problem that the material becomes inconsistent when the amount of carburizing is changed and defective products are generated.
【０００６】したがって、これらの問題を解決するため
には、設備がコンパクトで鋼帯の少量生産に向き、なお
且つ迅速浸炭が可能な技術ということになり、プラズマ
浸炭技術の利用が望まれた。現在のプラズマ浸炭技術
は、技術雑誌「工業加熱」のｖｏｌ．２４，Ｎｏ．５，
１９９ 年やｖｏｌ．２６，Ｎｏ．６，１９９ 年に総
説で紹介されているように、浸炭の対象品が鋼製加工部
品であり、鋼帯を処理したものはない。Therefore, in order to solve these problems, the equipment is compact, suitable for small-scale production of steel strip, and can be rapidly carburized. Therefore, the use of the plasma carburizing technique has been desired. The current plasma carburizing technology is described in Vol. 24, no. 5,
1999 and vol. 26, no. As introduced in the review in 6,199, the carburized product is a steel processed part, and no steel strip is processed.
【０００７】[0007]
【発明が解決しようとする課題】本発明は、かかる事情
を鑑み、コイル状鋼帯の極く表層部を瞬間的に短時間で
均一に浸炭し、且つ少量の鋼帯であっても処理できる浸
炭方法の提供を目的としている。SUMMARY OF THE INVENTION In view of the above circumstances, the present invention is capable of instantaneously and uniformly carburizing an extremely superficial portion of a coiled steel strip in a short period of time, and can treat even a small amount of steel strip. It aims to provide a carburizing method.
【０００８】[0008]
【課題を解決するための手段】発明者は、上記目的を達
成するため、従来のあらゆる浸炭技術を見直し、それら
の利用できる点を整理した。本発明は、その整理結果に
基づきなされたもので、緩目に巻いたコイル状鋼帯を、
ガス雰囲気下にある箱型焼鈍炉内にアップエンドに載置
して焼鈍するにあたり、上記コイル状鋼帯自体を陰極と
し、さらに該陰極の上方に陽極を配し、一時的に上記箱
形焼鈍炉内を減圧するとともに、上記両極間に電圧を印
加することを特徴とする鋼帯の浸炭方法である。また、
効果促進のため、本発明は、鋼帯コイルの内径及び／又
は外径に補助陰極を配置したことを特徴とする請求項１
記載の鋼帯の浸炭方法でもある。Means for Solving the Problems In order to achieve the above object, the inventor reviewed all the conventional carburizing techniques and arranged points which can be used. The present invention has been made on the basis of the rearrangement results.
When placing the coiled steel strip itself as a cathode and placing it in the box-type annealing furnace under a gas atmosphere for annealing, an anode is disposed above the cathode, and the box-shaped annealing is temporarily performed. A method for carburizing a steel strip, which comprises reducing the pressure in a furnace and applying a voltage between the two electrodes. Also,
In order to promote the effect, the present invention is characterized in that an auxiliary cathode is arranged at the inner diameter and / or the outer diameter of the steel strip coil.
It is also the method of carburizing the steel strip described.
【０００９】[0009]
【作用】本発明では、鋼帯を緩めにコイル状に巻くよう
にしたので、雰囲気ガスは鋼帯のすべての表面に接触で
きるようになる。また、本発明によれば、箱型焼鈍炉の
インナーカバ内を一時的に減圧し、陰極であるコイルと
その上方に配した陽極間に電圧を印加するようにしたの
で、両電極間にグロー放電プラズマが発生するようにな
る。その結果、Ｃイオンを含む陽イオンは、陰極である
鋼帯の表面に激突し、瞬時に浸炭現象を起こすのであ
る。According to the present invention, since the steel strip is loosely wound into a coil, the atmospheric gas can come into contact with all surfaces of the steel strip. Further, according to the present invention, since the inside of the inner cover of the box-type annealing furnace is temporarily depressurized and a voltage is applied between the coil as the cathode and the anode disposed above the coil, the glow is applied between the two electrodes. Discharge plasma is generated. As a result, the cations including C ions collide with the surface of the steel strip as the cathode and instantaneously cause carburization.
【００１０】さらに、本発明では、コイル状鋼帯の内径
及び／又は外径に補助陰極を設けるようにしたので、プ
ラズマの発生が促進され、瞬間的な浸炭を確実にしてい
る。以下、図１〜２に基づき、本発明の内容を説明す
る。図１は、本発明に係る鋼帯の浸炭方法を実施する場
合の概念を示したものであり、箱形焼鈍炉の縦断面図で
ある。図２は、コイル状鋼帯周囲への電極配置を示す斜
視図である。図１〜２に示すような配置において、陽極
１と陰極２の間を１０〜２０００（Ｐａ）に減圧し、そ
の間に２００〜１５００（Ｖ）の電圧を印加すると、陰
極２近傍で強い電位降下（以下、陰極降下）を生じ、陽
極より電子が放出される。放出された電子は、陰極２降
下部の強電場により急加熱されて、陽極へ向かって移動
する途中、雰囲気ガス中のＣＨ4 やＨ2 等のガス分子と
衝突し、それらを励起してＨ+ ，ＣＨ+ ，Ｃ+ 等のイオ
ン及びＣ* ，Ｈ* 等の活性子を生成する。発生したイオ
ンのうち陽イオンは陰極降下部で急速に加速され、陰極
であるコイル状鋼帯の表面に激突する。その際、Ｃを含
むイオンは、コイル状鋼帯の表層部を加熱するととも
に、Ｃを付与するのである。なお、コイル支持台の下方
に設けたファン６は、雰囲気ガスや発生したプラズマが
鋼帯の全表面に行き渡るための補助具である。Further, in the present invention, since the auxiliary cathode is provided on the inner and / or outer diameter of the coiled steel strip, the generation of plasma is promoted and instantaneous carburization is ensured. Hereinafter, the contents of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of a box-type annealing furnace, showing a concept in a case where a method of carburizing a steel strip according to the present invention is carried out. FIG. 2 is a perspective view showing the arrangement of electrodes around the coiled steel strip. In the arrangement shown in FIGS. 1 and 2, when the pressure between the anode 1 and the cathode 2 is reduced to 10 to 2000 (Pa) and a voltage of 200 to 1500 (V) is applied during that time, a strong potential drop occurs near the cathode 2. (Hereinafter referred to as cathode fall), and electrons are emitted from the anode. The emitted electrons are rapidly heated by the strong electric field in the descending portion of the cathode 2 and collide with gas molecules such as CH 4 and H 2 in the atmosphere gas while moving toward the anode, and excite them to generate H 2. + , CH + , C + and other ions and C * , H * and other activators. Positive ions among the generated ions are rapidly accelerated at the cathode descending portion and collide with the surface of the coiled steel strip as the cathode. At that time, the ions containing C heat the surface layer of the coiled steel strip and impart C. The fan 6 provided below the coil support is an auxiliary tool for the atmospheric gas and the generated plasma to spread over the entire surface of the steel strip.
【００１１】また、図２に示すように、コイル状鋼帯の
周りに５〜１０ｍｍ程度離して補助陰極（ホローカソー
ド）を配置し、上記の放電をさせると、補助陰極とコイ
ル状鋼帯（陰極）の間に極めて強い発光が生じる。これ
は、ホローカソード現象と呼ばれ、通常のグロー放電に
比べ数倍から数十倍の電流密度が得られ、通常のプラズ
マ浸炭より短時間の処理が可能となるのである。As shown in FIG. 2, an auxiliary cathode (hollow cathode) is disposed around the coiled steel strip at a distance of about 5 to 10 mm, and when the above-described discharge is performed, the auxiliary cathode and the coiled steel strip (hollow cathode) are discharged. A very strong emission occurs between the cathodes). This is called a hollow cathode phenomenon, and a current density several to several tens times higher than that of a normal glow discharge can be obtained, so that the treatment can be performed in a shorter time than normal plasma carburization.
【００１２】なお、本発明に係る鋼帯の浸炭方法では、
焼鈍炉での鋼帯加熱温度は６００〜１０００℃である
が、プラズマによる加熱エネルギーが不足する場合に
は、ラジアントチューブバーナや電気ヒータ等の補助加
熱源を用いても良い。In the method for carburizing a steel strip according to the present invention,
The heating temperature of the steel strip in the annealing furnace is 600 to 1000 ° C. However, if the heating energy by the plasma is insufficient, an auxiliary heating source such as a radiant tube burner or an electric heater may be used.
【００１３】[0013]
【実施例】溶鋼を転炉から出鋼後、ＲＨ真空脱炭処理し
て得た極低炭素鋼スラブを熱間圧延、冷間圧延を経て板
厚０．８ｍｍの冷延鋼板コイルとして巻取った。このコ
イル状鋼帯３を、図１に示すように、箱型焼鈍炉７の支
持台１８上にアップエンドに載置し、コイルの渦巻きを
緩め、所謂オープン（又はルーズ）コイルとした。[Example] An ultra-low carbon steel slab obtained by removing molten steel from a converter and subjecting it to RH vacuum decarburization is subjected to hot rolling and cold rolling to form a 0.8 mm thick cold rolled steel coil. Was. As shown in FIG. 1, the coiled steel strip 3 was placed on the support base 18 of the box-type annealing furnace 7 at the up end, and the spiral of the coil was loosened to form a so-called open (or loose) coil.
【００１４】その後、上部電極１（陽極）及び補助陰極
５、５ａをセットし、インナカーバ４及びベル３をかぶ
せ、電気配線、真空装置（図示せず）を取付けた。な
お、図１は各部のシールも省略してある。本実施例は、
図３に示す焼鈍温度パターンと炭化水素系の雰囲気ガス
を採用し、図示していない加熱手段により昇温が行われ
た。そして、この焼鈍工程の均熱期が終了に近ずいた時
点（図３では（１）で示す）より、直ちに真空装置を駆
動させ５００Ｐａまで減圧してから、４０秒間だけ両電
極間に１０００Ｖの電圧を印加した。その後は、通常の
焼鈍工程である冷却期に戻し、製品を炉から取り出し
た。Thereafter, the upper electrode 1 (anode) and the auxiliary cathodes 5 and 5a were set, the inner cover 4 and the bell 3 were covered, and electric wiring and a vacuum device (not shown) were attached. In FIG. 1, the seals of the respective parts are also omitted. In this embodiment,
The annealing temperature pattern shown in FIG. 3 and a hydrocarbon-based atmosphere gas were employed, and the temperature was raised by a heating means (not shown). Then, immediately after the end of the soaking period of this annealing step (indicated by (1) in FIG. 3), the vacuum device was immediately driven to reduce the pressure to 500 Pa, and then a voltage of 1000 V was applied between both electrodes for 40 seconds. A voltage was applied. Thereafter, the product was returned to the cooling period, which is a normal annealing step, and the product was taken out of the furnace.
【００１５】本実施例では、本発明に係る鋼帯の浸炭方
法を実施するタイミングは、３通り選んだ。すなわち、
図３の焼鈍温度パターン上で、（１）、（２）及び
（３）として示した。また、比較例として、上記と同一
のコイル状鋼帯が単に図３の温度パターンで焼鈍され
た。その結果、上記３つの実施例とも、鋼帯表層部に表
面から２００μｍ厚程度の浸炭層が均一に生成された。
その炭素含有量は、表１の最終欄に示してある。また、
表１には、上記実施例及び比較例で得た鋼帯の材料特性
が一括して示してある。表１より、本発明を適用して浸
炭した３つの鋼帯は、各特性値が比較例と比べてプレス
加工に好都合な数値であり、いずれも優れたプレス加工
鋼板となっていることが明らかである。In this embodiment, three kinds of timings for carrying out the method for carburizing a steel strip according to the present invention were selected. That is,
These are shown as (1), (2) and (3) on the annealing temperature pattern in FIG. Further, as a comparative example, the same coiled steel strip as above was simply annealed in the temperature pattern of FIG. As a result, in each of the three examples, a carburized layer having a thickness of about 200 μm was uniformly formed on the surface layer of the steel strip from the surface.
Its carbon content is shown in the last column of Table 1. Also,
Table 1 collectively shows the material properties of the steel strips obtained in the above Examples and Comparative Examples. From Table 1, it is apparent that the three steel strips carburized by applying the present invention have respective characteristic values more favorable for press working than the comparative example, and all of them are excellent pressed steel sheets. It is.
【００１６】[0016]
【表１】 [Table 1]
【００１７】[0017]
【発明の効果】以上述べたように、本発明によれば、極
低炭素鋼を素材としても、その表層部の極めて薄い部分
の浸炭で、プレス加工性の優れた鋼板を得ることができ
た。As described above, according to the present invention, a steel sheet excellent in press workability can be obtained by carburizing an extremely thin portion of the surface layer even when using extremely low carbon steel as a raw material. .
【図１】本発明に係る鋼帯の浸炭方法を実施する概念を
示した箱型焼鈍炉の縦断面図である。FIG. 1 is a longitudinal sectional view of a box-type annealing furnace showing a concept for carrying out a method for carburizing a steel strip according to the present invention.
【図２】コイル状鋼帯（陰極）周囲の電極配置を示す斜
視図である。FIG. 2 is a perspective view showing the arrangement of electrodes around a coiled steel strip (cathode).
【図３】本発明に係る鋼帯の浸炭方法を実施した焼鈍温
度パターンの１例である。FIG. 3 is an example of an annealing temperature pattern obtained by carrying out the method for carburizing a steel strip according to the present invention.
【図４】従来のガス浸炭法を実施する連続焼鈍設備の側
面図である。FIG. 4 is a side view of a continuous annealing facility that performs a conventional gas carburizing method.
１ 陽極 ２ 陰極（オープンコイル状鋼帯） ３ ベル ４ インナカバ ５、５ａ 補助陰極（ホローカソード） ６ ファン ７ 箱型焼鈍炉 ８ 冷延鋼板 ９ 予熱帯 １０ 加熱帯 １１ 均熱帯 １２ 浸炭帯 １３ 第１冷却帯 １４ 第２冷却帯 １５ シール １６ 従来の竪型連続焼鈍炉 １７ 進行方向を示す矢印 Reference Signs List 1 anode 2 cathode (open coiled steel strip) 3 bell 4 inner cover 5, 5a auxiliary cathode (hollow cathode) 6 fan 7 box-type annealing furnace 8 cold rolled steel sheet 9 pretropical 10 heating zone 11 uniform tropical zone 12 carburized zone 13 first Cooling zone 14 Second cooling zone 15 Seal 16 Conventional vertical continuous annealing furnace 17 Arrow indicating the traveling direction
───────────────────────────────────────────────────── フロントページの続き (72)発明者 中川 二彦 倉敷市水島川崎通１丁目（番地なし） 川崎製鉄株式会社 水島製鉄所内 (58)調査した分野(Int.Cl.6，ＤＢ名) C23C 8/38 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Futhiko Nakagawa 1-chome, Kawasaki-dori, Mizushima, Kurashiki-shi Kawasaki Steel Corporation Mizushima Works (58) Field surveyed (Int. Cl. 6 , DB name) C23C 8/38
Claims (2)
気下にある箱型焼鈍炉内にアップエンドに載置して焼鈍
するにあたり、上記コイル状鋼帯自体を陰極とし、さら
に該陰極の上方に陽極を配し、一時的に上記箱形焼鈍炉
内を減圧するとともに、上記両極間に電圧を印加するこ
とを特徴とする鋼帯の浸炭方法。When the coiled steel strip wound loosely is placed on an up end in a box type annealing furnace under a gas atmosphere and annealed, the coiled steel strip itself is used as a cathode, and A carburizing method for a steel strip, comprising disposing an anode above a cathode, temporarily reducing the pressure in the box-shaped annealing furnace, and applying a voltage between the two electrodes.
陰極を配置したことを特徴とする請求項１記載の鋼帯の
浸炭方法。2. The method for carburizing a steel strip according to claim 1, wherein an auxiliary cathode is disposed at an inner diameter and / or an outer diameter of the steel strip coil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5295465A JP2981384B2 (en) | 1993-11-25 | 1993-11-25 | Steel strip carburizing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5295465A JP2981384B2 (en) | 1993-11-25 | 1993-11-25 | Steel strip carburizing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07150332A JPH07150332A (en) | 1995-06-13 |
| JP2981384B2 true JP2981384B2 (en) | 1999-11-22 |
Family
ID=17820949
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5295465A Expired - Lifetime JP2981384B2 (en) | 1993-11-25 | 1993-11-25 | Steel strip carburizing method |
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|---|---|
| JP (1) | JP2981384B2 (en) |
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|---|---|---|---|---|
| US20050011192A1 (en) * | 2001-05-10 | 2005-01-20 | Shinjiroh Ohishi | Surface-reformed exhaust gas guide assembly of vgs type turbo charger, and method surface-reforming component member thereof |
| JP4811759B2 (en) * | 2005-11-07 | 2011-11-09 | 島根県 | Control method and apparatus for plasma carburizing treatment |
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| Publication number | Publication date |
|---|---|
| JPH07150332A (en) | 1995-06-13 |
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