JP4826372B2 - Stainless steel sheet having uniform film and method for producing the same - Google Patents

Stainless steel sheet having uniform film and method for producing the same Download PDF

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JP4826372B2
JP4826372B2 JP2006193974A JP2006193974A JP4826372B2 JP 4826372 B2 JP4826372 B2 JP 4826372B2 JP 2006193974 A JP2006193974 A JP 2006193974A JP 2006193974 A JP2006193974 A JP 2006193974A JP 4826372 B2 JP4826372 B2 JP 4826372B2
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勇人 喜多
太 香月
一雄 平原
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Sumitomo Metal Industries Ltd
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Description

本発明は精密プレス加工またはフォトエッチング加工により製造される機械部品や電子部品の素材として用いるのに適した、均一な酸化皮膜を有するステンレス鋼板とその製造方法に関する。   The present invention relates to a stainless steel plate having a uniform oxide film suitable for use as a material for mechanical parts and electronic parts manufactured by precision pressing or photoetching and a method for manufacturing the same.

ステンレス鋼板は、耐食性のみならず、機械的強度やバネ性にも優れており、機械部品や電子部品用の金属材料として使用されている。一般にこのような部品はプレス加工またはフォトエッチング加工により製造される。近年、機器の小型化や性能向上に伴い、ステンレス鋼板から製造される部品の小型化が進み、従来よりも高精度の加工が要求されるようになってきた。   Stainless steel sheets are excellent not only in corrosion resistance but also in mechanical strength and springiness, and are used as metal materials for mechanical parts and electronic parts. In general, such parts are manufactured by pressing or photoetching. In recent years, with the miniaturization and performance improvement of equipment, the miniaturization of parts manufactured from stainless steel sheets has progressed, and higher precision processing has been required than before.

ステンレス鋼板の製造は、電気炉溶解の後に連続鋳造または鍛造したスラブを熱間圧延した後、冷間圧延と焼鈍を繰り返して所定板厚の薄板にすることにより行われる。焼鈍は、窒素、水素、アルゴンまたはこれらの混合ガスを用いた無酸化雰囲気中で行われる光輝焼鈍(BAと略記される)とするのが一般的である。それにより美麗な光沢表面が得られ、通常は無塗装で使用されるステンレス鋼板の商品価値が高まるからである。所定の硬度を得るために、光輝焼鈍の後に調質圧延を行い、さらに平坦性を得るためにテンションレベラによる形状矯正を行うこともある。   A stainless steel plate is manufactured by hot rolling a continuously cast or forged slab after melting in an electric furnace, and then repeating cold rolling and annealing to obtain a thin plate having a predetermined thickness. The annealing is generally a bright annealing (abbreviated as BA) performed in a non-oxidizing atmosphere using nitrogen, hydrogen, argon or a mixed gas thereof. This is because a beautiful glossy surface is obtained, and the commercial value of a stainless steel plate that is normally used without coating is increased. In order to obtain a predetermined hardness, temper rolling may be performed after bright annealing, and shape correction by a tension leveler may be performed in order to further obtain flatness.

光輝焼鈍の際に、焼鈍雰囲気ガス中に微量に含まれる酸素や水分によって金属表面が酸化されるため、製造されたステンレス鋼板の表面は必然的に酸化皮膜(以下、BA皮膜とも言う)を有している。次に説明するように、このBA皮膜がステンレス鋼板の精密プレス加工やフォトエッチングを阻害することが問題視されるようになっている。   During bright annealing, the surface of the manufactured stainless steel sheet inevitably has an oxide film (hereinafter also referred to as BA film) because the metal surface is oxidized by oxygen and moisture contained in a trace amount in the annealing atmosphere gas. is doing. As will be described below, it has become a problem that this BA film inhibits precision press working and photoetching of stainless steel plates.

<精密プレス加工における問題点>
プレス加工とは、図1に示すようにステンレス鋼板1をダイス上2に置載し、ポンチ3でプレスして製品形状に成型する方法である。4は鋼板と金型との接触部分を示す。この方法は立体形状の加工に適し、高速で加工できるため量産性にも優れているので、例えば、ミニチュアベアリングのリテーナーやサイドシール、ボタン電池ケースなどの小型精密部品の製造に利用されている。
<Problems in precision pressing>
The press working is a method in which the stainless steel plate 1 is placed on a die 2 as shown in FIG. 4 shows the contact part of a steel plate and a metal mold | die. This method is suitable for processing a three-dimensional shape, and can be processed at high speed, so that it is excellent in mass productivity. For example, it is used for manufacturing small precision parts such as retainers, side seals and button battery cases of miniature bearings.

工業生産の場合、1分間あたり数百回の高速でプレス加工が行われる。プレス回数の増加に伴って金型が磨耗し、製品のバリが大きくなる、製品形状が悪化するなどの不具合を生ずる。そのため、金型が磨耗すると、プレス作業を中断して研磨、寸法調整などの金型の手入れを行う。手入れが不可能となるほど金型が摩耗した場合には新しい金型と交換する。精密プレス加工に使用される精密金型は高価であり、その手入れには熟練した作業を要するので、金型寿命の劣化は製品コストの上昇を招く。   In the case of industrial production, pressing is performed at a high speed several hundred times per minute. As the number of presses increases, the mold wears, resulting in problems such as increased product burrs and deteriorated product shape. Therefore, when the mold is worn, the press operation is interrupted and the mold is cleaned such as polishing and dimension adjustment. If the mold becomes worn so that it cannot be maintained, it is replaced with a new mold. The precision mold used for precision press processing is expensive, and skillful work is required for its maintenance. Therefore, deterioration of the mold life leads to an increase in product cost.

ステンレス鋼板の精密プレス加工の場合、金型摩耗の大きな原因が、加工中に脱落したBA皮膜による金型の損傷である。近年は、部品の小型化に伴う加工精度の高度化と生産性向上のためのプレス速度の高速化とにより、精密金型の磨耗改善に対する要望は一層強くなっている。   In the case of precision press working of stainless steel sheets, a major cause of mold wear is damage to the mold due to the BA film that has fallen off during processing. In recent years, there has been a growing demand for improved wear of precision molds due to the advancement of machining accuracy accompanying the miniaturization of parts and the increase in press speed for improving productivity.

下記特許文献1には、冷間圧延したステンレス鋼板を光輝焼鈍した後、ステンレス鋼板表面に生成したBA皮膜の表層を機械的手段または化学的手段により除去して、BA皮膜の厚さを300Å以下にすることにより、プレス金型の長寿命化を可能にすることが示されている。化学的手段として硝酸を主成分とする溶液を用いて浸漬または電解する酸洗処理が記載されている。表面仕上がりが問題になる製品ではBA皮膜を少し残しておくのがよいと記載されている。   In the following Patent Document 1, after the cold-rolled stainless steel sheet is brightly annealed, the surface layer of the BA film formed on the surface of the stainless steel sheet is removed by mechanical means or chemical means, and the thickness of the BA film is 300 mm or less. Thus, it is shown that the service life of the press die can be extended. As a chemical means, a pickling treatment in which a solution containing nitric acid as a main component is immersed or electrolyzed is described. It is stated that it is better to leave a little BA film in products where surface finish is a problem.

しかし、BA皮膜を均一に残存させることは困難であることと、BA皮膜自体が高硬度の緻密で均一な酸化皮膜ではないことにより、残存BA皮膜を均一に残存させたとしてもプレス成型時の皮膜の脱落は避け得ない。従って、この手法によるプレス金型の長寿命化の効果は制限される。   However, it is difficult to leave the BA film uniformly and because the BA film itself is not a dense and uniform oxide film with high hardness, even if the remaining BA film remains uniformly, The film is unavoidable. Therefore, the effect of extending the life of the press die by this method is limited.

また、特許文献1には、ステンレス鋼板を硝酸溶液中で浸漬または電解処理することが記載されているが、詳細な処理条件は明示されていない。
近年は機器の小型化、高精度化の要求から、使用される部品の加工精度も必然的に厳しくなってきている。そのため素材となるステンレス鋼板の従来よりもさらに高度な皮膜均一性が要求される。従来よりも高精度の加工が要求される具体例として、ハードディスクドライブ(HDD)等に使用されるミニチュアベアリングの場合、従来は板厚0.15〜0.2mmが主流であったが、近年はHDDの小型化にともないベアリング径を小さくする必要があり、素材となるステンレス鋼板の板厚も0.1〜0.05mmまで薄くなったため、酸化皮膜の特性が従来以上に影響する。さらに生産性を高めるため、従来よりもプレス加工速度は早くなってきており、金型寿命の劣化も顕著になってきている。次に述べるフォトエッチング加工でも、例えばプリンタトナーグリッドの場合、従来はグリッドピンの幅は0.2mm程度であったものが、近年は0.15mm以下に細くなり、これまで以上にフォトレジスト膜の密着性の向上が要求される。特許文献1には、このような加工精度の高度化に対応可能な技術は開示されていない。
Patent Document 1 describes that a stainless steel plate is immersed or electrolytically treated in a nitric acid solution, but detailed processing conditions are not clearly described.
In recent years, due to the demand for miniaturization and high precision of equipment, the processing accuracy of the components used is inevitably becoming strict. Therefore, a higher degree of film uniformity is required than in the conventional stainless steel plate. In the case of miniature bearings used in hard disk drives (HDDs) and the like as a specific example that requires higher precision machining than before, a plate thickness of 0.15 to 0.2 mm has been the mainstream in the past. With the miniaturization of HDDs, it is necessary to reduce the bearing diameter, and the thickness of the stainless steel plate as the material has also been reduced to 0.1 to 0.05 mm. In order to further increase the productivity, the press working speed has become faster than before, and the deterioration of the mold life has become remarkable. Even in the photo-etching process described below, for example, in the case of a printer toner grid, the width of the grid pin is conventionally about 0.2 mm, but in recent years it has been reduced to 0.15 mm or less. Improvement of adhesion is required. Patent Document 1 does not disclose a technique that can cope with such high processing accuracy.

<フォトエッチングにおける問題点>
写真製版技術を応用した加工方法であるフォトエッチング加工は、プレス加工では精密金型を用いても困難な超微細加工や、ハーフエッチングを含む複雑形状製品の加工に適している。例えば、ジンバル、エンコーダー、プリンタトナーグリッド、プリンタの紙送り歯車などがフォトエッチング加工により製造されている。
<Problems in photoetching>
Photo-etching, which is a processing method that applies photoengraving technology, is suitable for ultra-fine processing, which is difficult even when using a precision mold in press processing, and processing of complex shaped products including half etching. For example, gimbals, encoders, printer toner grids, printer paper feed gears, and the like are manufactured by photoetching.

フォトエッチング加工では、前処理工程においてアルカリ脱脂洗浄と酸洗処理により清浄化されたステンレス鋼板の表面に感光性の(フォト)レジスト膜を被覆する。次に、レジスト膜を露光現像してレジスト膜を製品形状と同じ形にパターニングする。次に、レジスト膜の上からエッチング液をスプレー噴霧して、露出している金属部分を溶解することにより製品形状への加工が行われ、最後にレジストを剥離して最終製品が得られる。   In the photo-etching process, a photosensitive (photo) resist film is coated on the surface of the stainless steel plate cleaned by alkali degreasing cleaning and pickling processing in the pretreatment process. Next, the resist film is exposed and developed to pattern the resist film in the same shape as the product shape. Next, an etching solution is sprayed and sprayed on the resist film to dissolve the exposed metal portion, whereby processing into a product shape is performed. Finally, the resist is peeled off to obtain a final product.

図2にエッチング加工断面を模式的に示す。5はステンレス鋼板、6はパターニングされたレジスト膜、7はエッチングにより残存する材料部分、8はエッチングにより除去された材料部分を示す。エッチング加工精度の向上には金属材料とレジスト膜の密着性が高いことが重要である。レジスト密着性が悪いと、図の左側に示すように、大きなサイドエッチング9が起こり、微細加工性が損なわれる。さらに、スプレーエッチング中にレジスト膜との隙間にエッチング液が浸透してエッチング端面の直線性が悪化し、悪くするとレジスト膜が剥離してしまう。   FIG. 2 schematically shows a cross section of the etching process. 5 is a stainless steel plate, 6 is a patterned resist film, 7 is a material portion remaining by etching, and 8 is a material portion removed by etching. In order to improve the etching processing accuracy, it is important that the adhesion between the metal material and the resist film is high. If the resist adhesion is poor, as shown on the left side of the figure, a large side etching 9 occurs and the fine workability is impaired. Further, during spray etching, the etchant penetrates into the gap between the resist film and the linearity of the etching end face is deteriorated.

下記特許文献2には、半導体のエッチング剤として使われている1水素2フッ化アンモニウムと過酸化水素の混合液を用いて材料表面を化学研磨することによりレジスト密着性を高める前処理方法が開示されている。この方法は高価な特殊薬剤を必要とするのでコスト高であり、塩酸等の安価な薬液を使用した処理によって良好なレジスト密着性を得ることが求められている。
特開平10−58054号公報 特開平9−67684号公報
Patent Document 2 below discloses a pretreatment method for improving resist adhesion by chemically polishing a material surface using a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide, which is used as a semiconductor etching agent. Has been. This method is expensive because it requires expensive special chemicals, and it is required to obtain good resist adhesion by treatment using an inexpensive chemical such as hydrochloric acid.
Japanese Patent Laid-Open No. 10-58054 JP-A-9-67684

本発明は、精密プレス加工やフォトエッチング加工などの高い加工精度が要求される用途に用いるステンレス鋼板とその製造方法を提供することを課題とする。
より具体的な課題は、光輝焼鈍されたステンレス鋼板の表面に存在するBA皮膜(酸化皮膜)に起因する問題点、すなわち、精密プレス加工ではBA皮膜の脱落による金型摩耗、フォトエッチング加工ではレジスト密着性の低下、を改善することができるステンレス鋼板とその製造方法を提供することである。
This invention makes it a subject to provide the stainless steel plate used for the use as which high process precision is requested | required, such as a precision press process and a photo-etching process, and its manufacturing method.
More specific problems are the problems caused by the BA film (oxide film) present on the surface of the brightly annealed stainless steel plate, that is, die wear due to falling off of the BA film in precision press processing, and resist in photo etching processing. It is to provide a stainless steel plate and a method for producing the same that can improve the decrease in adhesion.

本発明者らは、光輝焼鈍されたステンレス鋼板の精密プレス加工やフォトエッチング加工における上述した問題点は、光輝焼鈍時に不可避的に鋼板表面に生成するBA皮膜が不均一であって、しかも表面が汚れで汚染され、それらが除去しにくいためであることを究明した。   The above-mentioned problems in the precision press processing and photoetching processing of the brightly annealed stainless steel sheet are that the present inventors inevitably have a non-uniform BA film formed on the steel sheet surface during bright annealing, and the surface is not uniform. It was found that they were contaminated with dirt and they were difficult to remove.

BA皮膜が不均質であることはナノインデンテーション法により判明した。ナノインデンテーション測定は、先鋭化したダイヤモンド製三角錐型(または四角錘型)圧子を材料表面に押込み、荷重を数十μNレベルで制御しながら押込み深さを測定することにより、表面の1μm未満の極表層の機械強度や硬度を測定することができ、一般に厚みが1μmより薄いBA皮膜について調査するのに最適の方法である。このナノインデンテーション測定において、BA皮膜は、後で詳しく説明するように、厚み方向に脆い構造が存在し、皮膜構造が不均質であることが判明した。また、また、測定部位による硬度のばらつきや焼鈍雰囲気の温度や露点による硬度の変動も大きく、硬度の値が安定しないことがわかった。さらに、断面TEM写真から、図3(2)に模式的に示すように、皮膜の厚み自体も均一ではなく、皮膜表面に凹凸があることがわかった。したがって、BA皮膜は「不均一な皮膜」であると言える。   The inhomogeneity of the BA film was found by the nanoindentation method. Nanoindentation measurement is performed by pressing a sharpened diamond pyramid type (or square pyramid type) indenter into the material surface and measuring the indentation depth while controlling the load at a level of several tens of μN. This is an optimum method for investigating a BA film having a thickness of less than 1 μm. In this nanoindentation measurement, it was found that the BA film has a brittle structure in the thickness direction and the film structure is inhomogeneous, as will be described in detail later. In addition, it was found that the hardness value was not stable because the hardness variation due to the measurement site and the temperature variation in the annealing atmosphere and the dew point were large. Further, from the cross-sectional TEM photograph, it was found that the thickness of the film itself was not uniform and the film surface was uneven as schematically shown in FIG. Therefore, it can be said that the BA film is a “non-uniform film”.

この不均一なBA皮膜がステンレス鋼板の表面に存在することにより、プレス加工金型との接触時にBA皮膜の破壊や剥離を生じやすく、その結果、露出した素地金属と金型との凝着が高速で繰り返されるうちに金型を著しく磨耗させてしまう。また、硬度にばらつきや変動が大きいため、ステンレス鋼板の製造ロットによって金型寿命にばらつきが生じ、安定的な加工性が得られないという問題がある。   Due to the presence of this non-uniform BA film on the surface of the stainless steel plate, the BA film is liable to be destroyed or peeled off when contacting with the press mold, and as a result, the adhesion between the exposed base metal and the mold is likely to occur. While repeated at high speed, the mold will be significantly worn. Further, since the hardness varies widely and varies, there is a problem that the mold life varies depending on the production lot of the stainless steel sheet, and stable workability cannot be obtained.

フォトエッチング加工については、BA皮膜の表面凹凸が大きく、かつ表面に汚れが吸着した汚染吸着層が生成していることから、光輝焼鈍ステンレス鋼板は表面の濡れ性が低く、レジスト密着性が著しく低下することがわかった。レジスト密着性が低いと、上述したように、サイドエッチングやレジストの剥離により、エッチング加工精度の著しい低下を招く。   For photo-etching processing, the surface of the BA film has large surface irregularities, and a contamination adsorption layer with dirt adsorbed on the surface has been formed. Therefore, the bright annealed stainless steel sheet has low surface wettability, and resist adhesion is significantly reduced. I found out that When the resist adhesiveness is low, as described above, the etching processing accuracy is significantly lowered by side etching or resist peeling.

本発明によれば、光輝焼鈍したあとのステンレス鋼板を酸性水溶液中で電解処理することによって、不均一なBA皮膜を完全に除去すると同時に不動態化処理を行い、ステンレス鋼板の表面に新たな酸化皮膜を形成することにより、上記課題を解決することができる。こうして形成された酸化皮膜は、ナノインデンテーション測定と電気化学測定により、BA皮膜より硬度の高い緻密で均一な構造を持つ皮膜であることが確認され、断面SEM写真からは表面が平滑で大きな凹凸を含んでいないことも確認された。したがって、この表面酸化皮膜は「均一な表面皮膜」であると言うことができる。   According to the present invention, the stainless steel plate after bright annealing is electrolytically treated in an acidic aqueous solution to completely remove the non-uniform BA film and at the same time passivate the surface of the stainless steel plate. The above problem can be solved by forming a film. The oxide film thus formed was confirmed to be a film having a dense and uniform structure with higher hardness than the BA film by nanoindentation measurement and electrochemical measurement. From the cross-sectional SEM photograph, the surface was smooth and had large irregularities. It was also confirmed that it does not contain. Therefore, it can be said that this surface oxide film is a “uniform surface film”.

また、この「均一な表面皮膜」を有するステンレス鋼板を用いて精密プレス加工すると金型磨耗寿命が大幅に向上し、フォトエッチング加工ではレジスト密着性が改善されてエッチング加工精度の向上が図られ、精密加工用の材料として極めて有用であることも判明した。   In addition, precision press processing using a stainless steel plate having this “uniform surface coating” significantly improves the die wear life, and photoetching improves resist adhesion and improves etching accuracy. It has also been found to be extremely useful as a material for precision processing.

ここに、本発明は、ナノインデンテーション測定による硬度が5GPa以上の表面酸化皮膜を有することを特徴とする、光輝焼鈍されたステンレス鋼板である。このステンレス鋼は、好ましくは、表面の水の接触角が60°以下であるという濡れ性を示す。 Here, the present invention is characterized in that the hardness by the nanoindentation measurements has 5 GP a more surface oxide film, a stainless steel plate which has been bright annealed. This stainless steel preferably exhibits wettability such that the contact angle of water on the surface is 60 ° or less.

本発明のステンレス鋼板は、光輝焼鈍されたステンレス鋼板を酸性水溶液中で電解して、光輝焼鈍により形成された酸化皮膜の除去および不動態化処理を行った後、Feイオン濃度が0.3mg/L以下の水で洗浄することを特徴とする方法により製造することができる。この方法において、前記酸性水溶液は、硝酸、硫酸、硝酸塩および硫酸塩の中から選ばれた1種以上を含むpH2以下の水溶液であることが好ましい。   The stainless steel plate of the present invention is obtained by electrolyzing a brightly annealed stainless steel plate in an acidic aqueous solution, removing the oxide film formed by bright annealing and performing passivation treatment, and then the Fe ion concentration is 0.3 mg / It can be produced by a method characterized by washing with water of L or less. In this method, the acidic aqueous solution is preferably an aqueous solution having a pH of 2 or less containing at least one selected from nitric acid, sulfuric acid, nitrate and sulfate.

本発明の表面酸化皮膜の特性について次に説明する。
図3に、本発明のステンレス鋼板の表面酸化皮膜のような「均一な表面皮膜」とBA皮膜のような「不均一な表面皮膜」の状態を模式的に示す。
The characteristics of the surface oxide film of the present invention will be described next.
FIG. 3 schematically shows a state of a “uniform surface film” such as a surface oxide film of the stainless steel plate of the present invention and a “non-uniform surface film” such as a BA film.

本発明に従って、光輝焼鈍したあとに酸性水溶液中で電解処理することにより、光輝焼鈍で形成されたBA皮膜と汚染吸着層が完全に除去され、再不動態化されることにより、厚みが均一で硬度が高く緻密で清浄な表面酸化皮膜がステンレス鋼板の表面に形成され、これは図3(1)に模式的に示すような「均一な表面皮膜」である。   According to the present invention, by performing electrolytic treatment in an acidic aqueous solution after bright annealing, the BA film and the contamination adsorbing layer formed by bright annealing are completely removed and repassivated to obtain uniform thickness and hardness. A high, dense and clean surface oxide film is formed on the surface of the stainless steel plate, which is a “uniform surface film” as schematically shown in FIG.

一方、光輝焼鈍で形成されたBA皮膜は、図3(2)に模式的に示すように、表面に大きな凹凸があり、厚みが不均一で場所ごとにばらついている。さらに、BA皮膜の厚みは焼鈍雰囲気の温度や露点によって変動するため、光輝焼鈍ステンレス鋼板のロットごとにBA皮膜の厚みが変動する。   On the other hand, as schematically shown in FIG. 3 (2), the BA film formed by bright annealing has large irregularities on the surface, and the thickness is uneven and varies from place to place. Furthermore, since the thickness of the BA film varies depending on the temperature and dew point of the annealing atmosphere, the thickness of the BA film varies for each lot of the bright annealed stainless steel sheet.

再不動態化により形成された表面酸化皮膜は、厚みが均一であるのみならず、緻密で鋼板母材との密着性が良好であるため、結果として皮膜硬度が高くなることから、皮膜の均一性の評価として皮膜自身の硬度を指標として用いることができる。   The surface oxide film formed by repassivation is not only uniform in thickness, but also is dense and has good adhesion to the steel base material, resulting in high film hardness, resulting in film uniformity. As an evaluation, the hardness of the film itself can be used as an index.

金属材料の機械強度を評価する手段としてビッカース硬度計やマイクロビッカース硬度計による硬さ測定が広く用いられている。しかし、ステンレス鋼板の表面皮膜の厚みは厚みが1μmより小さい極めて薄い皮膜であるため、上記の硬度計では表面皮膜そのものの機械強度を測定することは出来ない。   As a means for evaluating the mechanical strength of a metal material, hardness measurement using a Vickers hardness tester or a micro Vickers hardness tester is widely used. However, since the thickness of the surface film of the stainless steel plate is an extremely thin film having a thickness of less than 1 μm, the mechanical strength of the surface film itself cannot be measured with the above hardness meter.

ナノインデンテーション測定は、先鋭化したダイヤモンド製三角錐型圧子を材料表面に押込み、荷重を数十μNレベルで制御しながら押込み深さを測定することにより、表面皮膜のような極薄膜の機械強度を得ることができる。この方法を用いれば、ビッカース硬度計などでは不可能であった、ステンレス鋼板のBA皮膜自身の機械強度の測定が可能となる。   Nanoindentation measurement is performed by pressing a sharpened diamond triangular pyramid indenter into the surface of the material and measuring the indentation depth while controlling the load at a level of several tens of μN. Can be obtained. By using this method, it is possible to measure the mechanical strength of the BA film itself of a stainless steel plate, which was impossible with a Vickers hardness tester.

ナノインデンテーション測定では、材料表面硬さをH、圧子にかかる荷重をP、および圧子と材料間の接触投射面積をAとしてH=P/Aの関係式から材料表面の硬度を求めることができる。すなわち図5に示す荷重−接触深さ曲線において、一定荷重のときの接触深さが小さいほど表面硬さHが大きいことを意味する。なお、荷重−接触深さ曲線は、図示のように、荷重負荷時と除荷時では異なる挙動を示す。   In the nanoindentation measurement, the hardness of the material surface can be obtained from the relational expression of H = P / A where the material surface hardness is H, the load applied to the indenter is P, and the contact projection area between the indenter and the material is A. . That is, in the load-contact depth curve shown in FIG. 5, the smaller the contact depth at a constant load, the greater the surface hardness H. In addition, the load-contact depth curve shows different behavior at the time of loading and unloading as shown in the figure.

本発明に係るステンレス鋼板が有する再不働態化により形成された表面酸化皮膜は、図3(1)に示すような「均一な表面皮膜」であり、この表面酸化皮膜をナノインデンテーション測定すると、図5(1)の荷重負荷曲線に示すように、荷重増加にともなって連続的に接触深さが増加し、深さ方向に向かって一定の硬さを有する均質な皮膜が形成されていることがわかる。この荷重負荷曲線の荷重増加に伴う接触深さ増大の勾配が小さく、これは硬度が高いことを意味している。この荷重負荷曲線において、接触深さ8nm付近に不連続点が認められ、ここで素地に達したことがわかる。   The surface oxide film formed by the repassivation of the stainless steel plate according to the present invention is a “uniform surface film” as shown in FIG. 3 (1). When this surface oxide film is measured by nanoindentation, As shown in the load curve of 5 (1), the contact depth increases continuously as the load increases, and a uniform film having a certain hardness in the depth direction is formed. Recognize. The gradient of the contact depth increase accompanying the load increase of this load load curve is small, which means that the hardness is high. In this load load curve, a discontinuous point is recognized in the vicinity of the contact depth of 8 nm, and it can be seen that the base has been reached here.

ナノインデンテーション測定で得られた荷重負荷曲線において不連続点が1点だけであることは、ここで皮膜から素地に達したためであり、皮膜の構造が均質であり、内部に脆い構造を有していないことを意味する。   The fact that there is only one discontinuity point in the load curve obtained by nanoindentation measurement is that the coating has reached the substrate, and the coating structure is homogeneous and has a brittle structure inside. Means not.

一方、光輝焼鈍したままのステンレス鋼板についてナノインデンテーション測定することによりBA皮膜自体の硬度を調査することができる。この場合の測定結果を、図5(2)に「不均一な表面皮膜」として示す。この場合は、荷重負荷曲線に複数(図示例では1〜4の4箇所)の不連続点が検出され、最終的に約12nmの部分で素地に達している。圧子を押し込む過程で素地に達する前に皮膜の破壊が何度も生じており、深さ方向に向かって部分的に脆い構造が存在していることが推定される。すなわち、BA皮膜は、厚みが不均一であるのみならず、皮膜の厚み方向において皮膜が一定硬さを有しておらず、皮膜の構造自体が不均質である。   On the other hand, the hardness of the BA coating itself can be investigated by measuring the nanoindentation of the stainless steel plate as brightly annealed. The measurement result in this case is shown as “non-uniform surface film” in FIG. In this case, a plurality of discontinuous points (four locations 1 to 4 in the illustrated example) are detected in the load load curve, and finally reach the substrate at a portion of about 12 nm. It is presumed that the coating is broken many times before reaching the substrate in the process of pushing the indenter, and a partially brittle structure exists in the depth direction. That is, the BA film not only has a non-uniform thickness, but the film does not have a certain hardness in the thickness direction of the film, and the structure of the film itself is not uniform.

その結果、「不均一な表面皮膜」であるBA皮膜は、プレス加工金型と接触する際に皮膜の破壊や剥離を生じやすく、それにより露出した素地金属と金型との凝着が高速で繰り返されるうちに金型を著しく磨耗させる。また、BA皮膜は測定部位による厚みのばらつきや焼成雰囲気の露点や温度による変動が大きく、厚みや硬さの値が安定しない。そのため、ステンレス鋼板の製造ロットによって金型寿命にばらつきが生じる。   As a result, the BA film, which is a “non-uniform surface film”, is likely to break or peel off the film when it comes into contact with the press working mold, thereby causing the adhesion between the exposed base metal and the mold at high speed. The mold will wear significantly over time. In addition, the BA film has a large variation in thickness depending on the measurement site and a large variation due to the dew point and temperature of the firing atmosphere, and the thickness and hardness values are not stable. Therefore, the mold life varies depending on the production lot of the stainless steel plate.

一方、「均一な表面皮膜」は、皮膜構造が厚さ方向において均一であって、皮膜密着性が良好である。また、酸性水溶液中での電解処理により形成される皮膜であるため、一定厚みで測定部位による変動のない表面酸化皮膜を安定して形成することができる。その結果、プレス加工の際に皮膜が剥離しにくいので、素地金属と金型との凝着が起こりにくくなり、金型寿命が大幅に改善される。   On the other hand, the “uniform surface film” has a uniform film structure in the thickness direction and good film adhesion. Moreover, since it is a film | membrane formed by the electrolytic process in acidic aqueous solution, the surface oxide film which does not change with a measurement site | part with a fixed thickness can be formed stably. As a result, since the film is difficult to peel off during press working, adhesion between the base metal and the mold is difficult to occur, and the mold life is greatly improved.

表面濡れ性は、表面に一定量の水滴を滴下し、表面と水滴の接線のなす角度(接触角)を測定することにより評価できる。この場合、水の接触角が小さいほど濡れ性が優れている。   The surface wettability can be evaluated by dropping a certain amount of water droplets on the surface and measuring the angle (contact angle) formed by the tangent line between the surface and the water droplets. In this case, the smaller the contact angle of water, the better the wettability.

光輝焼鈍したままのSUS304ステンレス鋼板は、表面の水の接触角を測定すると、通常70〜90°程度の値を示し、濡れ性が低い。ステンレス鋼板の光輝焼鈍時には、炉内で鋼板表面に汚れが焼きついたり、あるいはその後の過程で大気中に存在する汚れが表面に吸着して汚染吸着層を形成する。BA皮膜に存在するこれらの表面汚染物質は濡れ性を著しく低下させる。また、表面凹凸が大きく、かつ内部に脆い構造を含むBA皮膜の奥まで入り込んだ汚れは容易に取り除くことができないため、エッチング前処理工程で表面を洗浄しても、濡れ性を回復するのは困難である。   The brightly annealed SUS304 stainless steel sheet shows a value of about 70 to 90 ° when the contact angle of water on the surface is measured, and has low wettability. During bright annealing of a stainless steel plate, dirt is burned on the surface of the steel plate in the furnace, or dirt existing in the atmosphere is adsorbed on the surface in the subsequent process to form a contamination adsorbing layer. These surface contaminants present in the BA film significantly reduce wettability. In addition, since dirt that penetrates deep into the BA film that has a large surface irregularity and has a brittle structure inside cannot be easily removed, wetting can be restored even if the surface is washed in the pre-etching process. Have difficulty.

一方、本発明に従って光輝焼鈍後に酸性水溶液中で電解処理を施したステンレス鋼板では、BA皮膜が除去される際にBA皮膜に吸着された汚染物質も除去されてしまう。また、再不働態化により形成された表面積酸化皮膜は緻密で「均一な表面皮膜」である。そのため、本発明のステンレス鋼板は表面の水の接触角が60°以下と、濡れ性が高いという特徴を有する。さらに、表面積酸化皮膜が、均一な厚みを持つ緻密な皮膜であるため、表面に汚れが吸着しても、皮膜の内部まで入り込まず、エッチング前処理工程で容易に除去することができ、安定的に良好な濡れ性を得ることができる。そのため、密着性の高いレジスト膜を安定して形成することができ、サイドエッチングなどを起こさずに、高精度のフォトエッチング加工を行うことができる。   On the other hand, in a stainless steel plate that has been subjected to electrolytic treatment in an acidic aqueous solution after bright annealing according to the present invention, contaminants adsorbed on the BA coating are also removed when the BA coating is removed. Further, the surface area oxide film formed by repassivation is a dense “uniform surface film”. Therefore, the stainless steel plate of the present invention has a feature that the wettability is high as the contact angle of water on the surface is 60 ° or less. Furthermore, since the surface area oxide film is a dense film with a uniform thickness, even if dirt is adsorbed on the surface, it does not enter the inside of the film and can be easily removed in the pre-etching process, which is stable. In addition, good wettability can be obtained. Therefore, a resist film with high adhesion can be stably formed, and high-precision photoetching can be performed without causing side etching or the like.

本発明のステンレス鋼板は、次に説明するように、精密プレス加工およびフォトエッチング加工の素材として最適である。
精密プレス加工では、図1に示すようにプレス加工を行う際に、鋼板1とダイス2またはポンチ3とが接触する部分4で摩擦により金属材料1の表面皮膜が破壊、剥離することにより新生面が露出し、金型との間で金属同士の凝着が生じる。高速でプレス加工するうちに繰返し凝着することによって金型が磨耗する。BA皮膜は「不均一な表面皮膜」であるため、プレス速度の高速化にともない、金型磨耗が激しくなる。
The stainless steel plate of the present invention is most suitable as a material for precision pressing and photoetching as described below.
In precision pressing, as shown in FIG. 1, when pressing is performed, the surface film of the metal material 1 is broken and peeled off by friction at a portion 4 where the steel plate 1 and the die 2 or the punch 3 are in contact with each other, thereby forming a new surface. It is exposed and adhesion of metals occurs between the molds. The mold is worn by repeated adhesion during pressing at high speed. Since the BA film is a “non-uniform surface film”, the wear of the mold becomes severe as the press speed increases.

一方、緻密で「均一な表面皮膜」を有する本発明のステンレス鋼板は、皮膜が破壊・剥離を受けにくく、材料と金型との接触部分4に機械強度の高い表面酸化皮膜が介在するため、プレスを繰返し行っても金属同志の凝着が起こりにくい。さらに材料表面が清浄であるため、プレス油も均一に濡れ広がり、潤滑効果が向上する。その結果、高速で繰返しプレス加工を行っても金型磨耗が抑制され、従来に比べて金型寿命は飛躍的に向上する。   On the other hand, the stainless steel plate of the present invention having a dense “uniform surface film” is less susceptible to breakage and peeling, and a surface oxide film with high mechanical strength is interposed in the contact portion 4 between the material and the mold. Even if the press is repeated, adhesion between the metals hardly occurs. Furthermore, since the material surface is clean, the press oil is evenly spread and the lubrication effect is improved. As a result, mold wear is suppressed even when repeated press work is performed at high speed, and the mold life is dramatically improved as compared with the conventional technique.

フォトエッチング加工における加工性の向上にはレジスト密着性が良いことが必要であり、そのためにはステンレス鋼板表面の濡れ性の向上が必要となる。
これに関して、前述したように、BA皮膜は濡れ性が低く、レジスト密着性が悪いため、フォトエッチング加工の精度に著しい悪影響を及ぼしていた。一方、本発明に係る「均一な表面皮膜」を有するステンレス鋼板は、BA皮膜と同時に表面の汚染物質も除去されているため、本来の良好な濡れ性を回復している上、後工程で汚れが吸着しても、エッチング前処理工程で容易に除去することが可能であるため、安定して良好な濡れ性を確保できる。その結果、レジスト密着性が向上し、加工精度の向上およびエッチング加工不良の低減による加工歩留りの改善が図られる。
In order to improve the workability in the photoetching process, it is necessary that the resist adhesion is good. For this purpose, it is necessary to improve the wettability of the surface of the stainless steel plate.
In this regard, as described above, since the BA film has low wettability and poor resist adhesion, it has had a significant adverse effect on the accuracy of photoetching. On the other hand, the stainless steel plate having the “uniform surface coating” according to the present invention is free from the contaminants on the surface at the same time as the BA coating. Even if adsorbed, it can be easily removed in the pre-etching treatment step, so that good wettability can be secured stably. As a result, the resist adhesion is improved, and the processing yield is improved by improving processing accuracy and reducing etching processing defects.

本発明のステンレス鋼板は、安価な薬液を用いた処理により、光輝焼鈍時に形成されたBA皮膜が除去され、代りに厚み構造が均一で緻密な表面酸化皮膜が表面に形成されているため、精密プレス加工における金型寿命を飛躍的に改善し、フォトエッチング加工ではレジストの密着性を向上させる効果が得られる。従って、この鋼板は精密プレス加工またはフォトエッチング加工による高精度加工が可能であり、小型部品の製造に適している。   The stainless steel plate of the present invention has a precise surface oxide film formed on the surface by removing the BA film formed at the time of bright annealing by treatment with an inexpensive chemical solution. The die life in press working is dramatically improved, and the effect of improving the adhesion of the resist is obtained in photo etching. Therefore, this steel plate can be processed with high precision by precision pressing or photoetching, and is suitable for manufacturing small parts.

本発明に係るステンレス鋼板の表面積酸化皮膜(すなわち、「均一な表面皮膜」)は、ナノインデンテーション測定により求めた硬さが5GPa以上(皮膜硬さの逆数が0.2GPa-1以下)である。このような硬い表面皮膜は、高速で繰返しプレス加工を行っても割れや剥離を生じにくく、従来のBA皮膜に比べて、金型寿命を飛躍的に改善する効果が得られ、精密プレス加工用の材料として適している。皮膜硬さが5GPaより低いと、鋼板表面の酸化皮膜が金型の接触部分で容易に剥離し、鋼板表面と金型との間で金属凝着が生じやすくなり、金型寿命は悪化する。 The surface area oxide film (namely, “uniform surface film”) of the stainless steel plate according to the present invention has a hardness determined by nanoindentation measurement of 5 GPa or more (the reciprocal of the film hardness is 0.2 GPa −1 or less). . Such a hard surface film does not easily crack or peel even when repeatedly pressed at high speed, and has the effect of dramatically improving the die life compared to the conventional BA film. Suitable as a material. When the film hardness is lower than 5 GPa, the oxide film on the surface of the steel sheet is easily peeled off at the contact portion of the mold, and metal adhesion tends to occur between the surface of the steel sheet and the mold, and the mold life is deteriorated.

本発明のステンレス鋼板は、水の接触角が60°以下、望ましくは40°以下である。このような良好な濡れ性は、BA焼鈍過程で焼き付いた汚染物質が除去され、均一な酸化皮膜が表面に形成されることにより得られたものである。その結果、フォトエッチング加工において密着性に優れたレジスト膜を形成することができるため、本発明のステンレス鋼板は、精密加工のみならず、フォトエッチング加工用の材料としても適している。接触角が60°より大きくなると、レジスト密着性が不十分となり、フォトエッチング加工における製品歩留りが悪化する。下限は特に規定しないが、接触角は小さいほど濡れ性は良い。   The stainless steel plate of the present invention has a water contact angle of 60 ° or less, desirably 40 ° or less. Such good wettability is obtained by removing contaminants burned in the BA annealing process and forming a uniform oxide film on the surface. As a result, since a resist film having excellent adhesion can be formed in photoetching, the stainless steel plate of the present invention is suitable not only for precision processing but also as a material for photoetching. When the contact angle is larger than 60 °, the resist adhesion becomes insufficient and the product yield in the photoetching process is deteriorated. Although the lower limit is not particularly defined, the smaller the contact angle, the better the wettability.

上述した「均一な表面皮膜」としての表面酸化皮膜を有する本発明のステンレス鋼板は、光輝焼鈍したステンレス鋼板(すなわち、BA皮膜を有するステンレス鋼板)を酸性水溶液中で電解処理し、その直後に洗浄して、鋼板表面に残存する酸性水溶液を完全に除去し、最後に乾燥することにより得られる。電解処理は直流電解法(金属材料を連続的に陽極電解する方法)と交番電解法(陽極電解と陰極電解を交互に複数回繰り返す方法)のいずれによっても行うことができる。電解処理により、陽極電解時に皮膜溶解、陰極電解時もしくは無電解時に不働態化が起こり、均一な表面皮膜が形成されるものと考えられる。   The stainless steel sheet of the present invention having the surface oxide film as the “uniform surface film” described above is obtained by electrolytically treating a brightly annealed stainless steel sheet (that is, a stainless steel sheet having a BA film) in an acidic aqueous solution, and immediately after that, cleaning it. Then, the acidic aqueous solution remaining on the steel plate surface is completely removed and finally dried. The electrolytic treatment can be performed by either a direct current electrolysis method (a method in which a metal material is continuously subjected to anodic electrolysis) or an alternating electrolysis method (a method in which anodic electrolysis and cathodic electrolysis are alternately repeated a plurality of times). It is considered that the electrolytic treatment causes dissolution of the film during anodic electrolysis and passivation during cathodic electrolysis or non-electrolysis, thereby forming a uniform surface film.

工業規模で実施する場合には、電解処理は図6に示す間接通電方式、すなわち、電解槽12内に上下複数配置した電極11の間に鋼帯10を通過させながら、酸性水溶液13中で通電し、その後に洗浄槽4を通過させて洗浄を行う方式が最も効率的である。シート状あるいは成型後の部品の場合には被加工材料に電極を接続して電解液中で直接陽極電解する方式を用いてもよい。対極には白金や高珪素鋳鉄など公知の金属材料が使用できる。   When it is carried out on an industrial scale, the electrolytic treatment is conducted in the acidic aqueous solution 13 while passing the steel strip 10 between the electrodes 11 arranged in a plurality of upper and lower sides in the electrolytic cell 12 as shown in FIG. The most efficient method is to pass the cleaning tank 4 and perform cleaning thereafter. In the case of a sheet-like or molded part, a method in which an electrode is connected to a material to be processed and direct anodic electrolysis in an electrolytic solution may be used. A known metal material such as platinum or high silicon cast iron can be used for the counter electrode.

酸性水溶液は、安価で廃液処理もしやすい硝酸が工業的には望ましい。硝酸以外の酸としては硫酸も使用できる。また硝酸塩や硫酸塩の水溶液を使用することも可能であるが、水溶液が中性であると、電解処理中に水酸化鉄が発生して設備や鋼板表面を汚染する恐れがあるため、pH2以下の酸性にしてから使用するのが望ましい。   As the acidic aqueous solution, nitric acid is desirable industrially because it is inexpensive and easy to treat the waste liquid. Sulfuric acid can also be used as an acid other than nitric acid. It is also possible to use an aqueous solution of nitrate or sulfate. However, if the aqueous solution is neutral, iron hydroxide may be generated during the electrolytic treatment to contaminate the equipment and the steel plate surface. It is desirable to use after acidifying.

酸性水溶液が硝酸である場合、硝酸の濃度は1〜10質量%とするのが望ましく、より好ましくは3〜7質量%である。
電解時の温度(浴温)は20〜60℃の範囲が好ましい。これより低温でも電解処理による皮膜形成は可能であるが、効率が悪く処理時間がかかる。60℃より高温では、液の蒸発による原単位ロスや作業環境の悪化などが問題となる。
When the acidic aqueous solution is nitric acid, the concentration of nitric acid is desirably 1 to 10% by mass, and more preferably 3 to 7% by mass.
The temperature during electrolysis (bath temperature) is preferably in the range of 20 to 60 ° C. Film formation by electrolytic treatment is possible even at a temperature lower than this, but the efficiency is poor and processing time is required. When the temperature is higher than 60 ° C., the basic unit loss due to the evaporation of the liquid or the deterioration of the working environment becomes a problem.

電解処理における電気量(C/dm2)は1〜100、望ましくは5〜50とするのが良い。
酸性水溶液13を収容した電解槽12から出てきた直後のステンレス鋼板には酸性水溶液の極薄い液膜が残っており、そのまま放置しておくと金属表面が過剰に酸化してしまうため、速やかに酸性水溶液を除去する必要がある。そのため、電解槽12に隣接して洗浄槽14を配置し、電解処理したステンレス鋼板を洗浄する。
The amount of electricity (C / dm 2 ) in the electrolytic treatment is 1 to 100, preferably 5 to 50.
The stainless steel plate immediately after coming out of the electrolytic cell 12 containing the acidic aqueous solution 13 has a very thin liquid film of the acidic aqueous solution. If left as it is, the metal surface will be excessively oxidized, It is necessary to remove the acidic aqueous solution. Therefore, the cleaning tank 14 is disposed adjacent to the electrolytic tank 12 to clean the electrolytically treated stainless steel plate.

この洗浄に使用する洗浄水が濃度0.3mg/Lを越えるFeイオンを含有していると、腐食反応(金属表面の過剰酸化)を促進させてしまい、その結果、皮膜の均一性が損われてしまう。洗浄水がFeイオンを含有するのは、洗浄水のタンクや配管の錆が混入してくることが主な理由である。このように腐食の進んだ表面皮膜の場合、プレス金型寿命の改善の効果は得られず、またエッチング加工においてもレジスト密着性が悪化して加工精度の劣化を招く。   If the cleaning water used for this cleaning contains Fe ions with a concentration exceeding 0.3 mg / L, the corrosion reaction (excess oxidation of the metal surface) is promoted, and as a result, the uniformity of the film is impaired. End up. The main reason why the cleaning water contains Fe ions is that rust of the cleaning water tank and piping is mixed. In the case of such a corroded surface film, the effect of improving the press die life cannot be obtained, and the resist adhesion is deteriorated even in the etching process, resulting in deterioration of the processing accuracy.

これに対してFeイオン濃度が0.3mg/L以下の洗浄水で洗浄すると、上記の過剰な腐食反応を防止することができ、均一な皮膜が保たれる。従って、洗浄は、Feイオン濃度が0.3mg/L以下の洗浄水を使用して行う。洗浄水への錆の混入を防ぐ処置をとるか、あるいは必要であれば、イオン交換などの適当な手段でFeイオンを除去した洗浄水を使用する。洗浄水には界面活性剤を含有させてもよい。   On the other hand, when the Fe ion concentration is washed with washing water having a concentration of 0.3 mg / L or less, the excessive corrosion reaction can be prevented and a uniform film can be maintained. Therefore, cleaning is performed using cleaning water having an Fe ion concentration of 0.3 mg / L or less. Measures are taken to prevent rust from being mixed into the cleaning water, or if necessary, cleaning water from which Fe ions have been removed by appropriate means such as ion exchange is used. The washing water may contain a surfactant.

洗浄方法はスプレー方式または浸漬方式など形態は問わないが、特にスプレー方式の場合には広角ノズルを用いて板の全面を隙間なく洗浄できるようにするとよい。洗浄にかかる水量や温度、時間、およびその後の乾燥までの間隔については特に規定しない。   The cleaning method may be in any form such as a spray method or a dipping method. In particular, in the case of the spray method, it is preferable to use a wide-angle nozzle to clean the entire surface of the plate without any gaps. The amount of water used for washing, temperature, time, and interval until subsequent drying are not particularly specified.

上述した条件で電解処理を行うと、BA酸化皮膜が完全に除去された後に均一な表面酸化皮膜が形成され、金型寿命の改善および濡れ性の改善に顕著な効果が得られる。
酸性水溶液の酸濃度が低すぎるか、あるいは電気量が少なすぎると、BA皮膜を完全に除去することができず不均一な表面皮膜が残ったり、表面濡れ性を向上させることができないことがある。逆に、酸濃度、電気量、温度の少なくとも一つが高すぎると、金属表面が過剰に溶解されて著しく光沢が低下したり、酸洗ムラによる外観悪化を招くなど、商品価値の低下を生ずることがある。
When the electrolytic treatment is performed under the above-described conditions, a uniform surface oxide film is formed after the BA oxide film is completely removed, and a remarkable effect is obtained in improving the mold life and wettability.
If the acid concentration of the acidic aqueous solution is too low or the amount of electricity is too small, the BA film cannot be completely removed, and a non-uniform surface film may remain or the surface wettability may not be improved. . Conversely, if at least one of the acid concentration, the amount of electricity, and the temperature is too high, the metal surface will be excessively dissolved, resulting in a significant decrease in gloss and a deterioration in product value due to appearance deterioration due to pickling unevenness. There is.

上記の電解処理は光輝焼鈍の直後に実施するのが最も効果的である。圧延工程では酸化皮膜が成長することはほとんど無いので、電解処理の後に調質圧延、さらには形状矯正をおこなってもなんら問題は無い。また、光輝焼鈍の後に調質圧延、形状矯正を行い、最終工程で電解処理を行っても同じ効果が得られる。   It is most effective to carry out the above electrolytic treatment immediately after bright annealing. Since the oxide film hardly grows in the rolling process, there is no problem even if temper rolling and further shape correction are performed after the electrolytic treatment. Further, the same effect can be obtained by performing temper rolling and shape correction after bright annealing and performing electrolytic treatment in the final step.

本発明の「均一な表面皮膜」を有するステンレス鋼板は、スリット加工における刃先磨耗の抑制に有用であり、さらに塗装やハンダなどの付着強度向上にも有用である。   The stainless steel plate having the “uniform surface coating” of the present invention is useful for suppressing cutting edge wear in slit processing, and is also useful for improving the adhesion strength of coating and solder.

表1に示す組成を有するステンレス鋼板(SUS304)を使用し、仕上冷間圧延により板厚0.15mmとした後に、光輝焼鈍を行った。光輝焼鈍は、窒素と水素の混合ガス(窒素:水素=1:3)、露点−38℃の雰囲気中1080℃で行った。これは一般的な光輝焼鈍条件である。   A stainless steel plate (SUS304) having the composition shown in Table 1 was used, and after the thickness was reduced to 0.15 mm by finish cold rolling, bright annealing was performed. Bright annealing was performed at 1080 ° C. in an atmosphere of a mixed gas of nitrogen and hydrogen (nitrogen: hydrogen = 1: 3) and a dew point of −38 ° C. This is a general bright annealing condition.

Figure 0004826372
Figure 0004826372

光輝焼鈍の済んだステンレス鋼板を、図6に示す電解装置を用いて、5質量%濃度の硝酸水溶液(pH0.2)を用いて電解処理することにより、BA皮膜の除去と不動態化処理を行って、表面酸化皮膜を有するステンレス鋼板(a)および(b)を得た。電解処理は間接通電法により陽極電解と陰極電解を交互に5秒間、2回繰り返す交番電解処理により実施した。電気量は、ステンレス鋼板(a)が1C/dm2、ステンレス鋼板(b)が15C/dm2であった。光輝焼鈍ままのステンレス鋼板(c)を比較材として使用した。 The stainless steel plate that has been brightly annealed is subjected to electrolytic treatment using a 5 mass% nitric acid aqueous solution (pH 0.2) by using the electrolytic apparatus shown in FIG. And stainless steel plates (a) and (b) having a surface oxide film were obtained. The electrolytic treatment was carried out by alternating electrolytic treatment, in which anodic electrolysis and cathodic electrolysis were alternately repeated twice for 5 seconds by the indirect energization method. The quantity of electricity stainless steel plate (a) is 1C / dm 2, a stainless steel plate (b) was 15C / dm 2. A stainless steel plate (c) with bright annealing was used as a comparative material.

[表面皮膜の均一性]
ステンレス鋼板の表面皮膜の均一性を電気化学測定により確認した。図4に、5%硫酸水溶液中での自然電位の経時変化を測定した結果を示す。a〜cの3つの曲線はそれぞれステンレス鋼板(a)〜(c)での測定結果である。
[Uniformity of surface film]
The uniformity of the surface film of the stainless steel plate was confirmed by electrochemical measurement. FIG. 4 shows the results of measuring the change in natural potential with time in a 5% sulfuric acid aqueous solution. The three curves a to c are the measurement results for the stainless steel plates (a) to (c), respectively.

本発明に従って1C/dm2で電解処理を行ったステンレス鋼板(a)は、表面皮膜に起因する貴な自然電位を維持する時間が長く、溶けにくい「均一な表面皮膜」が形成されたことがわかる。電気量が15C/dm2と高かったステンレス鋼板(b)は、20分経過後も貴な自然電位を維持しており、表面皮膜の均一化がさらに増したことが確認された。 The stainless steel sheet (a) subjected to the electrolytic treatment at 1 C / dm 2 according to the present invention has a long time for maintaining a noble natural potential due to the surface film, and a “uniform surface film” that is difficult to melt is formed. Recognize. It was confirmed that the stainless steel plate (b) having an electric quantity as high as 15 C / dm 2 maintained a noble natural potential even after 20 minutes, and the surface coating was more uniform.

一方、光輝焼鈍ままのステンレス鋼板(c)は、硫酸に浸漬した直後は表面皮膜に起因する貴な自然電位を示すが、約2分後に急激に電位が低下して、素地の活性溶解による卑な自然電位を示した。すわなち、このステンレス鋼板(c)が有するBA皮膜は、硫酸溶液中で容易に溶解するような「不均一な表面皮膜」であることがわかる。   On the other hand, the stainless steel plate (c) that has been brightly annealed exhibits a noble natural potential due to the surface film immediately after being immersed in sulfuric acid, but the potential suddenly drops after about 2 minutes, resulting in a base metal due to active dissolution of the substrate. Showed a natural potential. That is, it can be seen that the BA film of the stainless steel plate (c) is a “non-uniform surface film” that is easily dissolved in a sulfuric acid solution.

図5にナノインデンテーションの測定例を示す。図5(1)に示す本発明のステンレス鋼板の表面に形成された「均一な表面皮膜」では、図5(2)に示す「不均一な表面皮膜」であるBA皮膜に比べて、荷重負荷曲線における押込み荷重に対する接触深さの勾配が小さく、機械強度(皮膜硬さ)が高いことがわかる。 FIG. 5 shows an example of nanoindentation measurement. The “uniform surface coating” formed on the surface of the stainless steel plate of the present invention shown in FIG. 5 (1) is more loaded than the BA coating which is the “non-uniform surface coating” shown in FIG. 5 (2) . It can be seen that the gradient of the contact depth with respect to the indentation load in the curve is small and the mechanical strength (film hardness) is high.

さらに、図5(2)の「不均一な表面皮膜」の荷重負荷曲線には複数の不連続点が認められ、このBA皮膜が機械強度が低く、内部に脆い構造を含んだ不均質な皮膜であることがわかる。これに対し、図5(1)の「均一な表面皮膜」の荷重負荷曲線では不連続点は表面皮膜から素地に達した時の1つだけであり、それまでは接触深さが押込み荷重に比例して連続的に増大しており、表面酸化皮膜が均質な皮膜であることがわかる。 In addition, the load curve of “Non-uniform surface coating” in FIG. 5 (2) shows a plurality of discontinuities, and this BA coating has a low mechanical strength and a non-uniform coating containing a brittle structure inside. It can be seen that it is. On the other hand, in the load curve of “Uniform surface coating” in Fig. 5 (1) , there is only one discontinuity point when the surface coating reaches the substrate. Until then, the contact depth is the indentation load. It increases in proportion and continuously, and it can be seen that the surface oxide film is a homogeneous film.

[プレス加工性(金型寿命の比較)]
金型寿命の評価は、上記3種類のステンレス鋼板(a)〜(c)を用いて実際に精密プレス加工によってミニチュアベアリングリテーナーを製造したときに金型寿命に達するまでのプレス回数を比較することにより行った。加工途中で製品抜き取り検査を行い、バリ高さが基準値以上になったところで金型寿命と判断した。結果を表2に示す。
[Press workability (Comparison of mold life)]
To evaluate the die life, compare the number of presses until the die life is reached when a miniature bearing retainer is actually manufactured by precision pressing using the above three types of stainless steel plates (a) to (c). It went by. A product sampling inspection was performed during the processing, and when the burr height exceeded the reference value, it was determined that the mold life was reached. The results are shown in Table 2.

Figure 0004826372
Figure 0004826372

本発明に従って電解処理を行った発明材(a)および(b)の表面皮膜の機械的強度(硬度)は0.2GPa-1以下(=5GPa以上)であり、プレス回数も目標とする50万回を大きく上回り、硝酸電解を行わない未処理の比較材(c)に比べて、2〜3倍以上も金型寿命が改善されていることがわかる。 The mechanical strength (hardness) of the surface coatings of the inventive materials (a) and (b) subjected to electrolytic treatment according to the present invention is 0.2 GPa −1 or less (= 5 GPa or more), and the number of presses is also a target of 500,000. It can be seen that the mold life is improved by 2-3 times or more compared to the untreated comparative material (c) which does not perform nitric acid electrolysis.

[フォトエッチング加工性]
上記3種類のステンレス鋼板(a)〜(c)を用いて実際にフォトエッチング加工によりプリンタトナーグリッドを製造した時の、グリッド部分(残し幅150μm、抜き幅500μm)のエッチング欠陥発生率を調査した。試験結果を水の接触角(協和界面科学製CA−A150により測定)の結果と一緒に表3に示す。
[Photo etching processability]
When the printer toner grid was actually manufactured by photoetching using the above three types of stainless steel plates (a) to (c), the etching defect occurrence rate of the grid portion (remaining width 150 μm, punching width 500 μm) was investigated. . The test results are shown in Table 3 together with the results of the contact angle of water (measured with CA-A150 manufactured by Kyowa Interface Science).

Figure 0004826372
Figure 0004826372

本発明に従って電解処理を行った発明材(a)および(b)のエッチング欠陥発生率は3%以下であるのに対し、未処理の比較材(c)の欠陥発生率は8%と高かった。従って、本発明によりフォトエッチング加工における大幅な歩留り改善効果が得られることがわかる。   Inventive materials (a) and (b) subjected to electrolytic treatment according to the present invention have an etching defect occurrence rate of 3% or less, whereas the untreated comparative material (c) has a high defect occurrence rate of 8%. . Therefore, it can be seen that a significant yield improvement effect in photoetching can be obtained by the present invention.

水の接触角は、未処理の比較材(c)では85°と高く、濡れ性が乏しいのに対し、本発明に従って電解処理した発明材(a)および(b)では接触角は60°以下であり、濡れ性が改善されていることがわかる。特に電気量が15C/dm2と高かった発明材(b)では接触角が32°と小さく、濡れ性が著しく改善されていた。この濡れ性の改善がフォトエッチング加工性の改善につながっていると推測される。 The contact angle of water is as high as 85 ° for the untreated comparative material (c) and poor wettability, whereas the contact angle is 60 ° or less for the inventive materials (a) and (b) electrolyzed according to the present invention. It can be seen that the wettability is improved. In particular, the invention material (b) having a high electric charge of 15 C / dm 2 had a contact angle as small as 32 ° and the wettability was remarkably improved. It is speculated that this improvement in wettability leads to an improvement in photoetching processability.

冷間圧延したSUS304鋼板(板厚0.22mm)を、AXガス中1130℃でBA焼鈍したものを使用した。この冷間圧延ステンレス鋼板を5%硝酸水溶液中で交番電解処理し(電気量20C/dm2)、直ちにFeイオン濃度0.3mg/L以下の水およびFeイオン濃度0.3mg/Lを越える水で洗浄したものについて調査した。 A cold-rolled SUS304 steel plate (thickness 0.22 mm) subjected to BA annealing at 1130 ° C. in AX gas was used. This cold-rolled stainless steel sheet was subjected to alternating electrolytic treatment in a 5% nitric acid aqueous solution (electricity 20 C / dm 2 ) and immediately water with an Fe ion concentration of 0.3 mg / L or less and water with an Fe ion concentration exceeding 0.3 mg / L. We investigated what was washed in

自然電位測定は、実施例1(硝酸電解電流の影響)では5%硫酸水溶液を用いて行ったが、洗浄の影響を比較する本例では、電位変化が敏感に現れる5%塩酸水溶液を用いて行った。結果を図7に示す。   The natural potential measurement was performed using a 5% aqueous sulfuric acid solution in Example 1 (effect of nitric acid electrolysis current), but in this example for comparing the effect of cleaning, a 5% aqueous hydrochloric acid solution in which potential changes appear sensitively was used. went. The results are shown in FIG.

図7からわかるように、Feイオン濃度0.3mg/Lを越える水を用いて洗浄したもの(d)は、測定開始直後からマイナス電位を示し、皮膜の均一性が損われていることが確認される。これに対して電解処理後にFeイオン濃度0.3mg/L以下の水で洗浄したもの(e)は、プラス電位を1分半程度持続した後に−400mV以下の電位へ低下を示しており、皮膜の均一性が高いことがわかる。   As can be seen from FIG. 7, the product (d) washed with water having an Fe ion concentration exceeding 0.3 mg / L shows a negative potential immediately after the start of measurement, confirming that the uniformity of the coating is impaired. Is done. On the other hand, what was washed with water having an Fe ion concentration of 0.3 mg / L or less after electrolytic treatment (e) showed a decrease to a potential of −400 mV or less after maintaining a positive potential for about one and a half minutes. It can be seen that the uniformity is high.

精密プレス加工におけるステンレス鋼板の切断断面を模式的に示す。The cut section of a stainless steel plate in precision press processing is shown typically. フォトエッチング加工におけるステンレス鋼板の加工断面を模式的に示す。The process cross section of the stainless steel plate in a photoetching process is shown typically. 図3(1)および(b)はそれぞれ「均一な表面皮膜」および「不均一な表面皮膜」を模式的に示す図である。FIGS. 3A and 3B are diagrams schematically showing a “uniform surface coating” and a “non-uniform surface coating”, respectively. 実施例で試験した発明材(a)および(b)と未処理の比較材(c)の5%硫酸水溶液中で測定した自然電位の経時変化を示すグラフ。The graph which shows the time-dependent change of the natural potential measured in the 5% sulfuric acid aqueous solution of invention material (a) and (b) which were tested in the Example, and untreated comparative material (c). 図5(1)および(2)はそれぞれ「均一な表面皮膜」および「不均一な表面皮膜」のナノインデンテーションの測定例を示す。5 (1) and 5 (2) show measurement examples of nanoindentation of “uniform surface coating” and “non-uniform surface coating”, respectively. 連続式の間接通電型電解処理装置を示す説明図。Explanatory drawing which shows a continuous indirect-current-type electrolytic treatment apparatus. 洗浄水中のFeイオン濃度が0.3mg/Lを超えた(d)と、0.3mg/L以下であった(e)の5%塩酸水溶液中で測定した自然電位の経時変化を示すグラフ。The graph which shows the time-dependent change of the natural potential measured in 5% hydrochloric acid aqueous solution of (e) whose Fe ion density | concentration in wash water exceeded 0.3 mg / L and (e) which was 0.3 mg / L or less.

符号の説明Explanation of symbols

1:ステンレス鋼板、2:金型(ダイス)、3:金型(ポンチ)、4:材料と金型の接触部分、5:ステンレス鋼板、6:フォトレジスト膜、7:残し部分、8:抜き部分、9:エッチング欠陥部分、10:ステンレス鋼板、11:電極、12:電解槽、13:酸性水溶液、14:洗浄槽 1: stainless steel plate, 2: mold (die), 3: mold (punch), 4: contact portion between material and mold, 5: stainless steel plate, 6: photoresist film, 7: remaining portion, 8: punched Part, 9: Etching defect part, 10: Stainless steel plate, 11: Electrode, 12: Electrolysis tank, 13: Acidic aqueous solution, 14: Cleaning tank

Claims (5)

ナノインデンテーション測定による硬度が5GPa以上の表面酸化皮膜を有することを特徴とする、光輝焼鈍され、酸性水溶液中で電解処理された後に、Feイオン濃度が0.3mg/L以下の水で洗浄されたステンレス鋼板。 Featuring a surface oxide film with a hardness of 5 GPa or more by nanoindentation measurement, it is brightly annealed , electrolytically treated in an acidic aqueous solution, and then washed with water having an Fe ion concentration of 0.3 mg / L or less. Stainless steel sheet. 表面の水の接触角が60°以下である、請求項1に記載の光輝焼鈍されたステンレス鋼板。   The brightly annealed stainless steel sheet according to claim 1, wherein the contact angle of water on the surface is 60 ° or less. 光輝焼鈍されたステンレス鋼板を酸性水溶液中で電解して、光輝焼鈍により形成された酸化皮膜の除去および不動態化処理を行った後、Feイオン濃度が0.3mg/L以下の水で洗浄することを特徴とする、請求項1または2に記載のステンレス鋼板の製造方法。 The bright annealed stainless steel plate is electrolyzed in an acidic aqueous solution to remove the oxide film formed by bright annealing and passivate it, and then washed with water having an Fe ion concentration of 0.3 mg / L or less. The method for producing a stainless steel plate according to claim 1 or 2 , characterized in that 前記酸性水溶液が、硝酸、硫酸、硝酸塩および硫酸塩の中から選ばれた1種以上を含むpH2以下の水溶液である、請求項3に記載の方法。   The method according to claim 3, wherein the acidic aqueous solution is an aqueous solution having a pH of 2 or less containing at least one selected from nitric acid, sulfuric acid, nitrate and sulfate. 前記酸性水溶液が硝酸濃度1〜10質量%の硝酸水溶液であり、電解を電気量1〜100C/dm2で行う、請求項3に記載の方法。 The method according to claim 3, wherein the acidic aqueous solution is a nitric acid aqueous solution having a nitric acid concentration of 1 to 10% by mass , and electrolysis is performed at an electric charge of 1 to 100 C / dm 2 .
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