JP3639680B2

JP3639680B2 - Manufacturing method of Ni-plated steel sheet

Info

Publication number: JP3639680B2
Application number: JP30224496A
Authority: JP
Inventors: 輝昭山田; 亮介和気; 良一吉原
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1996-11-13
Filing date: 1996-11-13
Publication date: 2005-04-20
Anticipated expiration: 2016-11-13
Also published as: JPH10140397A

Description

【０００１】
【発明の属する技術分野】
本発明は、Ｎｉメッキ後、熱処理を施すＮｉメッキ鋼板の製造方法に関するものである。
【０００２】
【従来の技術】
Ｎｉメッキ後、熱処理を施すＮｉメッキ鋼板の製造方法としては、特開平６−２１０４号公報に開示された方法がある。この方法は、冷延鋼板上に１〜５μｍのＮｉメッキを施し、引続き還元または非酸化性雰囲気でＮｉの再結晶温度以上で熱処理をする製造法であり、鋼帯の熱処理方法として箱型焼鈍と連続焼鈍のいずれでも可能と記述されている。
【０００３】
本発明者らは、特開平６−２１０４号公報の方法に準じて、Ｎｉメッキを施した冷延鋼板のコイルを箱焼鈍および連続焼鈍で熱処理を行いＮｉ拡散メッキ鋼板の試験製造を試みた結果、バッチ熱処理では焼付が発生し、連続熱処理ではＮｉメッキ層がハースロールに焼付ビルトアップし押し疵となり、いずれも良好なＮｉ拡散メッキ鋼板を得ることができなかった。
【０００４】
そこで、Ｎｉメッキ鋼板を熱処理するときの焼付防止について従来知見を調査したが、焼付防止方法については、通常の冷延鋼板の場合には硫化物を鋼板表面に塗布する方法がある程度で、Ｎｉメッキ鋼板の場合の良好な焼付回避方法が見あたらなかった。尚、上記の特開平６−２１０４号公報には焼付回避方法についてなにも記載されていない。
【０００５】
【発明が解決しようとする課題】
本発明が解決しようとする課題は、Ｎｉメッキ後、熱処理を施すＮｉメッキ鋼板の製造方法において、バッチ熱処理時の焼付の回避あるいは連続熱処理時のＮｉメッキ層がハースロールに焼付ビルトアップし押し疵となるのを回避するＮｉメッキ鋼板の製造方法を提供することである。
【０００６】
【課題を解決するための手段】
本発明者らは、Ｎｉメッキ後、熱処理を施すＮｉメッキ鋼板の製造方法において、バッチ熱処理時の焼付の回避あるいは連続熱処理時のＮｉメッキ層がハースロールに焼付ビルトアップし押し疵となるのを回避するＮｉメッキ鋼板の製造方法を提供することについて、鋭意検討を行い本発明を完成したものであり、その要旨とするところは下記の通りである。
（１）０．１〜２０μｍ厚みのＮｉメッキ鋼板コイルを、バッチ熱処理設備で５００℃〜８５０℃の温度域で２０min 以上滞在せしめる熱処理を施すＮｉメッキ鋼板の製造方法において、Ｎｉメッキ後、Ｎｉメッキ層上にクロメート処理を施して総Ｃｒ量で１０〜１５０mg／ｍ²を被覆した後、バッチ熱処理設備で熱処理を行うことを特徴とするバッチ熱処理時の焼付を回避するＮｉメッキ鋼板の製造方法。
（２）０．１〜２０μｍ厚みのＮｉメッキ鋼帯を連続熱処理設備で５００℃〜８５０℃の温度域で熱処理を施すＮｉメッキ鋼板の製造方法において、Ｎｉメッキ後、Ｎｉメッキ層上にクロメート処理を施して総Ｃｒ量で１０〜１５０mg／ｍ²を被覆した後、連続熱処理設備で熱処理を行うことを特徴とする連続熱処理時のＮｉメッキ層がハースロールに焼付ビルトアップし押し疵となるのを回避するＮｉメッキ鋼板の製造方法。
【０００７】
以下に本発明について詳細に述べる。
本発明者らは、まず、Ｎｉメッキ後、熱処理を施すＮｉメッキ鋼板の製造方法において、バッチ熱処理時の焼付の回避について、Ｎｉメッキ層の上に、１）オルソ珪酸ソーダー液で電解洗浄し、Ｓｉを付着させる方法、２）Ｎｉメッキ後、大気中で３００℃〜４５０℃に加熱し酸化膜を付ける方法、３）電解クロメート処理によってクロメート被膜を付ける方法について、種々の検討を行った。
【０００８】
その結果、１）オルソ珪酸ソーダー液で電解洗浄し、Ｓｉを付着させる方法、２）Ｎｉメッキ後大気中で３００℃〜４５０℃に加熱し酸化膜を付ける方法は、いずれもバッチ熱処理時の焼付け性を改善する傾向は認められるものの十分な改善には到達しなかった。一方、３）電解クロメート処理によってクロメート被膜を付ける方法については、顕著な改善効果が認められた。
【０００９】
そこで、この電解クロメート処理によってクロメート被膜を付ける方法について、種々の方法でバッチ熱処理時の焼付きが防止できる条件について種々の実験を行い、本発明の方法を見いだした。
【００１０】
図１は、０．２０mmのＮｉメッキ（１μｍ厚み）鋼板を、Ｃｒメッキ浴で浴組成、電流量、時間を変え、クロメート量（総Ｃｒ量）が０〜８０mg／ｍ²のサンプル（３０Ｗ×４０Ｌ）を試作し、Ｎｉメッキ面同士を十字型に重ね合せて６０kgf/cm²の強さではさみ付けた状態のペアーのサンプルを７００℃×２０Hrの無酸化雰囲気熱処理を行い、室温まで冷却した箱型焼鈍（バッチ熱処理）のシミュレート熱処理を行い、そのペアーのサンプルの焼付力（ステッキング力）を調査するため、ペアーの十字型のサンプルを上下方向に引張り（十字引張り）焼付力を調査した結果を、クロメート量との関係で図示したものである。
【００１１】
尚、図中の本発明の範囲としてステッキング力≦２kgとしたのは、図１の実験結果を基に、実機試験し、焼付のために焼鈍後のコイルを巻戻す時に板が不規則に折れ曲り凸凹の板とならない限界のステッキング力を求め、≦２kgであれば、問題が生じないという結果に基づいて記入したものである。
【００１２】
図１から、バッチ熱処理設備で熱処理を施すＮｉメッキ鋼板の製造方法において、Ｎｉメッキ後、Ｎｉメッキ層上に総Ｃｒ量で１０mg／ｍ²以上を被覆すればバッチ熱処理時の焼付を回避できることがわかる。
【００１３】
次に、本発明者らは、連続熱処理ではＮｉメッキ層がハースロールに焼付ビルトアップし押し疵となるという問題の解決策として、上記の図１で得られた結果が適用できると考えて、その効果を確認した結果、０．１〜２０μｍ厚みのＮｉメッキ鋼帯を連続熱処理設備で５００℃〜８５０℃の温度域で１０sec 以上滞在せしめ熱処理を施すＮｉメッキ鋼板の製造方法において、Ｎｉメッキ後、Ｎｉメッキ層上に総Ｃｒ量で１０〜１５０mg／ｍ²を被覆した後連続熱処理設備で熱処理を行うことで、連続熱処理時のＮｉメッキ層がハースロールに焼付ビルトアップし押し疵となるのを回避できることを見いだした。
【００１４】
【発明の実施の形態】
以下に本発明の構成条件について詳細に説明する。
対象となるＮｉメッキ鋼板は、メッキ厚みが０．１〜２０μｍのＮｉメッキ鋼板で、メッキ厚みが０．１μｍ未満では熱処理中に地鉄からのＦｅの拡散が早く、Ｎｉ最表層にＦｅが多く存在するようになり、焼付現象そのものが希薄になりクロメート処理等の本願の方法を適用する価値そのものが薄くなるので０．１μｍ厚みを対象の下限とした。また、上限を２０μｍとしたのは、電気メッキで２０μｍ超のメッキを施すには電気エネルギーコストが高くなりすぎ経済的に成立ちがたいので、上限値を２０μｍとした。下地の鋼板は、Ｎｉメッキを施せるものであれば特に限定する必要がない。また、冷間圧延の状態の未再結晶の鋼板でも、再結晶焼鈍後の鋼板でも、更に調質圧延後の鋼板でもいずれでもよく、特に限定する必要はない。
【００１５】
バッチ熱処理の条件は、熱処理温度時間が５００℃〜８５０℃の温度域で２０min 以上滞在せしめる熱処理を施すＮｉメッキ鋼板の熱処理を対象にしており、焼鈍温度が５００℃未満あるいは５００℃以上の熱処理時問が２０min 未満の時は、焼付現象そのものが極僅かで実害が生じないので対象外とした。また、熱処理温度の上限を８５０℃としたのは、バッチ熱処理では８５０℃超では自重でコイルの変形が大きく良好な形状が得られなくなるためである。
【００１６】
連続熱処理の条件は、熱処理温度時間が５００℃〜８５０℃の温度域で熱処理を施すＮｉメッキ鋼板の熱処理を対象にしており、焼鈍温度が５００℃未満であればハースロールヘの焼付現象そのものが極僅かで実害が生じないので対象外とした。また、熱処理温度の上限を８５０℃としたのは、連続焼鈍では、鋼板が軟化し炉内通板中にコイルがのびたり変形したりあるいは破断したりして、連続炉中を通板することが困難となるためである。
【００１７】
Ｎｉメッキ層上に金属ＣｒおよびＣｒ化合物（主として水酸化Ｃｒ）を被覆する方法は、電解クロメート処理でも塗布クロメート処理のいずれでもよく、総Ｃｒ量が１０mg／ｍ²以上あれば、焼付を防止できる。この理由は必ずしも明確ではないが、金属Ｃｒは熱処理中に雰囲気中の僅かな水分と反応し酸化Ｃｒとなり、Ｎｉの表面を酸化Ｃｒあるいは水酸化Ｃｒで覆い、直接Ｎｉ面同士が接触しなくなることそして酸化Ｃｒあるいは水酸化Ｃｒ面同士は高温で接触しても互いのＣｒ元素の拡散を実質的に抑制することができるため焼付現象が生じなくなるのではないかと考えられる。尚、クロメート量の上限を１５０mg／ｍ²としたのは、１５０mg／ｍ²を超えても焼付防止効果は十分存続するが、クロメート処理費用がかさむのみであるので１５０mg／ｍ²を上限値とした。
【００１８】
【実施例】
以下に本発明の効果を実施例により説明する。
表１に示す組成、熱延、冷延条件で０．２５mm厚みの冷間圧延コイルを製造し、第２表に示す焼鈍（再結晶焼鈍）、調質圧延、Ｎｉ電気メッキ、電解クロメート処理、そして、Ｎｉメッキ層の軟質化あるいは密着性を向上させるための拡散熱処理（Ｎｉメッキ前に再結晶焼鈍を省略したものは再結晶焼鈍も兼ねた熱処理）、調質圧延、を行いＮｉメッキ（あるいはＮｉ拡散メッキ）鋼帯を製造した。
【００１９】
バッチ熱処理（箱焼鈍あるいはＢＡＦと称する）の場合の焼付き性の評価は、熱処理後調質圧延を施さないものは巻戻しを行い、巻戻し時に焼付き性を評価し、熱処理後調質圧延を施したものは調質圧延時の巻戻し時に焼付け性の評価を行い、焼付による形状不良等のトラブルがなかったものを○、焼付いて巻戻しができなかったものあるいは焼付により形状不良が発生したものを×として表２に示した。
【００２０】
連続熱処理（連続焼鈍あるいはＣＡＬと称する）の場合の焼付き性の評価は、熱処理後コイルを巻戻しを行って、鋼板の外観観察を行い板表面に押し疵（ＣＡＬ炉中の多数のハースロールの上をＮｉメッキ鋼板が通過するときにＮｉメッキ鋼板とハースロール表面との間で焼付が発生するとハースロールに焼付いた鋼チップがビルトアップし、そのハースロール表面の突起によって鋼板がへこみ押し疵と称する疵が生じる）が生じているか否かを評価し、押し疵が発生したものを×、生じなかったものを○として表２に示した。
【００２１】
供試鋼Ａは、Ｃ含有量が０．００１７％、Ｎｂ，Ｔｉ含有量がそれぞれ０．０１３％，０．０１４％のＮｂ，Ｔｉ添加の極低炭素鋼で厳しい加工用途用の冷間圧延鋼板である。
供試鋼Ｂは、Ｃ含有量が０．０４２％の低炭素Ａｌキルド鋼で一般の加工用の冷間圧延鋼板である。
【００２２】
試料Ｎｏ．１，２，３，４，５，６は本発明の実施例で、試料Ｎｏ．７，８，９，１０は比較例である。試料Ｎｏ．１，２は供試鋼Ａ，Ｂを用いて箱焼鈍（ＢＡＦ）で再結晶焼鈍し調質圧延したコイルにＮｉメッキを２．０μｍ，３．０μｍ目付し、その上に本発明の焼付防止のためのクロメート処理で１００mg／ｍ²，２０mg／ｍ²の目付を施した本発明の実施例で、いずれも焼付の発生がなく良好な外観のＮｉメッキ鋼板が製造できた。
【００２３】
試料Ｎｏ．３，４は供試鋼Ａ，Ｂを用いてＮｉメッキ前の再結晶焼鈍を省略しＮｉメッキ層の軟質化ならびに拡散処理と鋼板自体の再結晶焼鈍を１回のＢＡＦ熱処理で行う本発明の実施例で、冷間圧延鋼帯にＮｉメッキを１．０μｍ，２．０μｍ目付し、その上に本発明の焼付防止のためのクロメート処理で８０mg／ｍ²，３０mg／ｍ²の目付を施したもので、いずれも焼付の発生がなく良好な外観のＮｉメッキ鋼板が製造できた。
【００２４】
試料Ｎｏ．５，６は供試鋼Ａ，Ｂを用いてＮｉメッキ前の再結晶焼鈍を省略し、Ｎｉメッキ層の軟質化ならびに拡散処理と鋼板自体の再結晶焼鈍を１回のＣＡＬ熱処理で行う本発明の実施例で、冷間圧延鋼帯にＮｉメッキを２．０μｍ目付し、その上に本発明の焼付防止のためのクロメート処理で５０mg／ｍ²の目付を施したもので、いずれも焼付の発生がなく良好な外観のＮｉメッキ鋼板が製造できた。
【００２５】
試料Ｎｏ．７，８，９，１０は供試鋼ＡまたはＢを用いて各種のルートで、Ｎｉメッキを２．０μｍ目付し、その上に本発明の焼付防止のためのクロメート処理を施さない条件で試作した比較例で、いずれも焼付が発生し良好な外観のＮｉメッキ鋼板が製造できなかった。
【００２６】
以上の実施例の結果から明らかなように、本発明の方法によって、本発明が解決しようとする課題のＮｉメッキ後、熱処理を施すＮｉメッキ鋼板の製造方法において、バッチ熱処理時の焼付の回避あるいは連続熱処理時のＮｉメッキ層がハースロールに焼付ビルトアップし押し疵となるのを回避するＮｉメッキ鋼板の製造方法を提供することが十分に達成できる。
【００２７】
【表１】

【００２８】
【表２】

【００２９】
【発明の効果】
以上に本発明について詳細に説明したが、本発明の鋼板は、本発明が解決しようとする課題のＮｉメッキ後、熱処理を施すＮｉメッキ鋼板の製造方法において、バッチ熱処理時の焼付の回避あるいは連続熱処理時のＮｉメッキ層がハースロールに焼付ビルトアップし押し疵となるのを回避するＮｉメッキ鋼板の製造方法を提供することが十分に達成でき、工業的価値が極めて大である。
【図面の簡単な説明】
【図１】Ｎｉメッキ鋼板を熱処理したときのクロメート量と焼付き性（ステッキング力）との関係を示す図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a Ni-plated steel sheet that is heat-treated after Ni plating.
[0002]
[Prior art]
As a method for manufacturing a Ni-plated steel sheet that is heat-treated after Ni plating, there is a method disclosed in Japanese Patent Laid-Open No. 6-2104. This method is a manufacturing method in which a 1-5 μm Ni plating is applied on a cold-rolled steel sheet, followed by heat treatment at a temperature equal to or higher than the recrystallization temperature of Ni in a reducing or non-oxidizing atmosphere. And continuous annealing is described as possible.
[0003]
According to the method disclosed in Japanese Patent Application Laid-Open No. 6-2104, the inventors of the present invention tried to heat test the Ni-plated cold-rolled steel sheet by box annealing and continuous annealing to test manufacture of the Ni diffusion-plated steel sheet. In the case of batch heat treatment, seizure occurred, and in the case of continuous heat treatment, the Ni plating layer was baked up on the hearth roll to become a push rod, and none of them could obtain a good Ni diffusion plated steel sheet.
[0004]
Therefore, the conventional knowledge about the seizure prevention when heat-treating the Ni-plated steel sheet was investigated. However, as for the seizure prevention method, in the case of a normal cold-rolled steel sheet, the method of applying sulfide to the steel sheet surface is limited to a certain extent. No good seizure avoidance method was found in the case of steel plates. Incidentally, the above-mentioned Japanese Patent Application Laid-Open No. 6-2104 does not describe anything about the seizure avoidance method.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is that in the method of manufacturing a Ni-plated steel sheet that is heat-treated after Ni plating, avoidance of seizure during batch heat treatment or Ni-plated layer during continuous heat-treatment is baked up on a hearth roll and pressed. It is providing the manufacturing method of the Ni plating steel plate which avoids becoming.
[0006]
[Means for Solving the Problems]
In the method of manufacturing a Ni-plated steel sheet that is subjected to heat treatment after Ni plating, the inventors have avoided that seizure at the time of batch heat treatment or the Ni plating layer at the time of continuous heat treatment is baked up on the hearth roll and becomes a pushing rod. The present invention has been completed by earnestly studying to provide a method for manufacturing a Ni-plated steel sheet to be avoided, and the gist thereof is as follows.
(1) In a method of manufacturing a Ni-plated steel sheet in which a Ni-plated steel sheet coil having a thickness of 0.1 to 20 μm is subjected to a heat treatment that allows a batch heat treatment facility to stay in a temperature range of 500 ° C. to 850 ° C. for 20 minutes or more. A method for producing a Ni-plated steel sheet that avoids seizure during batch heat treatment, wherein the layer is subjected to chromate treatment to cover a total Cr amount of 10 to 150 mg / m ² and then heat treated in a batch heat treatment facility.
(2) In a method for producing a Ni-plated steel sheet, in which a Ni-plated steel strip having a thickness of 0.1 to 20 μm is heat-treated in a continuous heat treatment facility in a temperature range of 500 ° C. to 850 ° C., after Ni plating, chromate treatment is performed on the Ni-plated layer. The Ni plating layer at the time of continuous heat treatment is built-up on a hearth roll and becomes a push rod, which is characterized by performing heat treatment with a continuous heat treatment facility after coating with a total Cr amount of 10 to 150 mg / m ² The manufacturing method of the Ni plating steel plate which avoids.
[0007]
The present invention is described in detail below.
First, in the manufacturing method of a Ni-plated steel sheet in which heat treatment is performed after Ni plating, the inventors of the present invention are directed to avoiding seizure during batch heat treatment on the Ni plating layer by 1) electrolytic cleaning with an orthosilicate soda solution, Various studies were made on a method of attaching Si, 2) a method of applying an oxide film by heating to 300 ° C. to 450 ° C. in the air after Ni plating, and 3) a method of applying a chromate film by electrolytic chromate treatment.
[0008]
As a result, 1) Electrolytic cleaning with orthosilicate soda solution and Si deposition, 2) Heating to 300 ° C to 450 ° C in the air after Ni plating, and attaching oxide film to each other are baking during batch heat treatment Although there was a tendency to improve sex, it did not reach sufficient improvement. On the other hand, the remarkable improvement effect was recognized about the method of attaching the chromate film by 3) electrolytic chromate treatment.
[0009]
Therefore, various experiments were conducted on the conditions for preventing seizure during batch heat treatment by various methods, and the method of the present invention was found.
[0010]
FIG. 1 shows a 0.20 mm Ni-plated (1 μm thick) steel sheet with a Cr plating bath, changing the bath composition, current amount, and time, and a chromate amount (total Cr amount) of 0 to 80 mg / m ² (30 W × 40L), and a pair of samples in which Ni plating surfaces are superimposed in a cross shape and sandwiched at a strength of 60 kgf / cm ² are subjected to heat treatment in a non-oxidizing atmosphere at 700 ° C. × 20 Hr and cooled to room temperature. In order to investigate the seizure power (sticking power) of the paired samples by conducting simulated heat treatment of box-type annealing (batch heat treatment), the pair of cross-shaped samples are pulled up and down (cross tension) to investigate the seizure power The results are shown in relation to the chromate amount.
[0011]
In the figure, the range of the present invention is that the sticking force ≦ 2 kg is based on the experimental results of FIG. 1 and the plate is irregular when the coil after annealing is rewound for baking. The limit sticking force that does not result in a bent and uneven plate is obtained, and it is filled in based on the result that no problem occurs if ≦ 2 kg.
[0012]
From FIG. 1, in the method of manufacturing a Ni-plated steel sheet that is heat-treated in a batch heat treatment facility, after Ni plating, if the Ni plating layer is coated with a total Cr amount of 10 mg / m ² or more, seizure during batch heat treatment can be avoided. Understand.
[0013]
Next, the present inventors consider that the result obtained in FIG. 1 can be applied as a solution to the problem that the Ni plating layer is baked up and pressed into a hearth roll in continuous heat treatment, As a result of confirming the effect, in the method of manufacturing a Ni-plated steel sheet in which a Ni-plated steel strip having a thickness of 0.1 to 20 μm is kept in a continuous heat treatment facility at a temperature range of 500 ° C. to 850 ° C. for 10 seconds or more, and after Ni plating, By coating the Ni plating layer with a total Cr content of 10 to 150 mg / m ² and performing heat treatment with a continuous heat treatment facility, the Ni plating layer during continuous heat treatment is baked up on the hearth roll and becomes a pressing rod. I found that I could avoid it.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The constituent conditions of the present invention will be described in detail below.
The target Ni-plated steel sheet is a Ni-plated steel sheet with a plating thickness of 0.1 to 20 μm. If the plating thickness is less than 0.1 μm, the diffusion of Fe from the ground iron is quick during heat treatment, and there is a lot of Fe on the Ni outermost layer. Since the seizure phenomenon itself becomes thin and the value of applying the method of the present application such as chromate treatment becomes thin, the thickness of 0.1 μm is set as the lower limit. The upper limit is set to 20 μm because the electric energy cost is too high to make plating exceeding 20 μm by electroplating and it is difficult to establish economically, so the upper limit is set to 20 μm. The underlying steel plate is not particularly limited as long as it can be plated with Ni. Further, it may be a non-recrystallized steel sheet in a cold rolled state, a steel sheet after recrystallization annealing, or a steel sheet after temper rolling, and there is no particular limitation.
[0015]
The conditions for batch heat treatment are for heat treatment of Ni-plated steel sheet that is subjected to heat treatment that allows heat treatment temperature to stay for 20 min or more in a temperature range of 500 ° C. to 850 ° C., and when the annealing temperature is less than 500 ° C. or 500 ° C. or more. When the question was less than 20 min, the seizure phenomenon itself was negligible and no actual harm occurred, so it was excluded. Moreover, the upper limit of the heat treatment temperature is set to 850 ° C., because in the batch heat treatment, when the temperature exceeds 850 ° C., the coil is deformed by its own weight and a good shape cannot be obtained.
[0016]
The conditions for the continuous heat treatment are for heat treatment of Ni-plated steel sheets that are heat-treated at a temperature range of 500 ° C. to 850 ° C. If the annealing temperature is less than 500 ° C., there is very little seizure phenomenon on the hearth roll. However, since no actual harm occurred, it was excluded. Moreover, the upper limit of the heat treatment temperature was 850 ° C., in the case of continuous annealing, the steel plate softens and the coil extends, deforms or breaks in the through plate in the furnace, and passes through the continuous furnace. This is because it becomes difficult.
[0017]
The method of coating the metal Cr and Cr compound (mainly Cr hydroxide) on the Ni plating layer may be either electrolytic chromate treatment or coating chromate treatment. If the total Cr amount is 10 mg / m ² or more, seizure can be prevented. . The reason for this is not necessarily clear, but metal Cr reacts with a slight amount of moisture in the atmosphere during heat treatment to become Cr oxide, and the Ni surface is covered with Cr oxide or Cr hydroxide so that the Ni surfaces do not directly contact each other. And even if Cr oxide surfaces or Cr hydroxide surfaces contact each other at a high temperature, it is considered that the diffusion of Cr elements can be substantially suppressed, so that the seizure phenomenon does not occur. Note that the upper limit of the chromate amount is set to 150 mg / m ^{2. Even if} the upper limit exceeds 150 mg / m ² , the seizure prevention effect is sufficiently maintained, but only the chromate treatment cost is increased, so 150 mg / m ² is set as the upper limit. did.
[0018]
【Example】
The effects of the present invention will be described below with reference to examples.
A cold rolled coil having a thickness of 0.25 mm is manufactured under the composition, hot rolling, and cold rolling conditions shown in Table 1, and annealing (recrystallization annealing), temper rolling, Ni electroplating, electrolytic chromate treatment, shown in Table 2, Then, diffusion plating heat treatment for improving the softness or adhesion of the Ni plating layer (if the recrystallization annealing is omitted before Ni plating is a heat treatment that also serves as recrystallization annealing), temper rolling, and Ni plating (or (Ni diffusion plating) steel strip was produced.
[0019]
In the case of batch heat treatment (box annealing or BAF), evaluation of seizure is performed by rewinding those not subjected to temper rolling after heat treatment, evaluating seizure during rewinding, and temper rolling after heat treatment. For those subjected to temper rolling, the bakeability is evaluated at the time of rewinding, ○ if there were no troubles such as shape defects due to baking, or if the shape could not be rewound due to baking, or a shape defect occurred due to baking. The results are shown in Table 2 as x.
[0020]
In the case of continuous heat treatment (continuous annealing or CAL), the evaluation of seizure is performed by unwinding the coil after heat treatment, observing the appearance of the steel sheet, and pressing the plate surface (a number of hearth rolls in the CAL furnace). When the Ni-plated steel sheet passes over the surface and the seizure occurs between the Ni-plated steel sheet and the hearth roll surface, the steel chip baked on the hearth roll is built up, and the steel plate is dented by the protrusion on the hearth roll surface. Table 2 shows whether or not a push wrinkle occurred, and a circle that did not cause a wrinkle.
[0021]
Test steel A is an ultra-low carbon steel containing 0.0017% C, Nb and Ti with Nb and Ti contents of 0.013% and 0.014%, respectively, and is cold rolled for severe processing applications. It is a steel plate.
Test steel B is a low-carbon Al-killed steel having a C content of 0.042% and is a cold-rolled steel sheet for general processing.
[0022]
Sample No. 1, 2, 3, 4, 5, and 6 are examples of the present invention. 7, 8, 9, and 10 are comparative examples. Sample No. Nos. 1 and 2 are obtained by applying Ni plating to 2.0 μm and 3.0 μm on the coil which has been recrystallized annealing by box annealing (BAF) using the test steels A and B, and temper rolled. In the examples of the present invention in which the basis weights of 100 mg / m ² and 20 mg / m ² were applied by the chromate treatment for No, there was no occurrence of seizure and a Ni-plated steel sheet having a good appearance could be produced.
[0023]
Sample No. Nos. 3 and 4 use the test steels A and B, omit recrystallization annealing before Ni plating, soften the Ni plating layer and perform diffusion treatment and recrystallization annealing of the steel sheet itself in one BAF heat treatment. In the examples, Ni plating is applied to cold-rolled steel strips at 1.0 μm and 2.0 μm, respectively, and a weight of 80 mg / m ² or 30 mg / m ² is applied thereon by chromate treatment for preventing seizure according to the present invention. As a result, there was no seizure, and a Ni-plated steel sheet having a good appearance could be produced.
[0024]
Sample No. Nos. 5 and 6 use the test steels A and B, omit recrystallization annealing before Ni plating, and soften the Ni plating layer and perform diffusion treatment and recrystallization annealing of the steel sheet itself in one CAL heat treatment. In this example, Ni plating was applied to a cold-rolled steel strip at a thickness of 2.0 μm, and a weight of 50 mg / m ² was applied on the steel plate by the chromate treatment for preventing seizure according to the present invention. A Ni-plated steel sheet having no appearance and good appearance could be produced.
[0025]
Sample No. 7, 8, 9 and 10 are various routes using the test steel A or B, with a Ni plating per unit area of 2.0 μm, and trial manufacture on the condition that the chromate treatment for preventing seizure of the present invention is not applied thereon. In all the comparative examples, seizure occurred and a Ni-plated steel sheet having a good appearance could not be produced.
[0026]
As is apparent from the results of the above examples, in the method of manufacturing a Ni-plated steel sheet that is subjected to heat treatment after Ni plating, which is a problem to be solved by the present invention, by the method of the present invention, It can be sufficiently achieved to provide a method for producing a Ni-plated steel sheet in which the Ni-plated layer during continuous heat treatment is prevented from being built up by baking up on a hearth roll and becoming pressed.
[0027]
[Table 1]

[0028]
[Table 2]

[0029]
【The invention's effect】
Although the present invention has been described in detail above, the steel sheet of the present invention is a method for manufacturing a Ni-plated steel sheet that is subjected to heat treatment after Ni plating, which is a problem to be solved by the present invention. It is sufficiently attainable to provide a method for producing a Ni-plated steel sheet that avoids the Ni-plated layer during heat treatment being baked up on a hearth roll and becoming a push-up, and the industrial value is extremely high.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the amount of chromate and seizure (sticking force) when a Ni-plated steel sheet is heat treated.

Claims

In a method for producing a Ni-plated steel sheet, in which a Ni-plated steel sheet coil having a thickness of 0.1 to 20 μm is subjected to a heat treatment that allows a batch heat treatment facility to stay at a temperature range of 500 ° C. to 850 ° C. for 20 minutes or more, after Ni plating, on the Ni plating layer A method for producing a Ni-plated steel sheet that avoids seizure during batch heat treatment, wherein a chromate treatment is performed to coat a total Cr amount of 10 to 150 mg / m ² and then heat treatment is performed in a batch heat treatment facility.

In a method for producing a Ni-plated steel sheet in which a Ni-plated steel strip having a thickness of 0.1 to 20 μm is heat-treated at a temperature range of 500 ° C. to 850 ° C. with a continuous heat treatment facility, after Ni plating, a chromate treatment is performed on the Ni-plated layer. After covering the total Cr amount of 10 to 150 mg / m ² , heat treatment is performed in a continuous heat treatment facility, and the Ni plating layer during continuous heat treatment is baked up on the hearth roll and avoids pressing. Manufacturing method of Ni-plated steel sheet.