JP2005007430A - Method for manufacturing cold-rolled stainless steel sheet having antimicrobial property and hot-rolled steel sheet for the cold-rolling - Google Patents
Method for manufacturing cold-rolled stainless steel sheet having antimicrobial property and hot-rolled steel sheet for the cold-rolling Download PDFInfo
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Abstract
Description
【0001】
【発明の属する技術分野】
本発明は、抗菌性を有するステンレス冷延鋼板を経済的に製造する方法に関し、特に、鏡面光沢肌を有し、抗菌性を発現できる光輝焼鈍されたステンレス冷延鋼板を経済的に製造する方法およびその冷延用熱延鋼板に関する。
【0002】
【従来の技術】
ステンレス冷延鋼板のうちでも、SUS304 BA 材のような光輝焼鈍された鏡面光沢肌を有するステンレス冷延鋼板は、生活関連用品や医療機器及び建材等に用いられている。SUS304 BA 材に代表されるステンレス冷延鋼板は、熱延鋼板を、焼鈍、酸洗し、引き続いて熱延鋼板表面を100μm 程度、研削油を用いて表面研削した後、冷間圧延、光輝焼鈍、スキンパス圧延して製造されるのが一般的である。
【0003】
ステンレス熱延鋼板を表面研削する理由は、焼鈍、酸洗されたステンレス熱延鋼板の表面には脱Cr層が優先的に粒界浸食された凹部が存在しており、この凹部を除去しないまま、冷間圧延、光輝焼鈍、スキンパス圧延すると、凹部が幾分か平滑化されずに残存してしまい、鏡面光沢肌を有する製品を製造することができないためである。また、ステンレス熱延鋼板を表面研削する場合に研削油を用いるのは、ステンレス熱延鋼板の研削性を良好として、鏡面光沢肌を有する製品を得るためである。
【0004】
例えば、エンドレスの研磨ベルトを鋼板表面に押し付け、回転させるベルト式のホットコイル用グラインダーを用い、ステンレス熱延鋼板を表面研削するに当たり、研削油を使用しない場合には、研磨ベルトに研削屑が詰まる目詰まりが生じると共に発生する研削熱により目詰まりに起因して構成刃先が形成され、表面研削された後のステンレス熱延鋼板の表面が荒れてしまうなどの研削不良が発生する。このような研削不良が発生すると、鏡面光沢肌を有するステンレス冷延鋼板製品とするのが非常に困難となる。
【0005】
そこで、SUS304 BA 材に代表されるステンレス冷延鋼板は、研削油を用いて表面研削され、その後、冷間圧延、光輝焼鈍、スキンパス圧延して製造される。
【0006】
ところで、抗菌性を有するステンレス鋼板としては、所定量の銀、例えば、0.0005〜0.50質量%含有するオーステナイト系ステンレス鋼が知られている(特許文献1)。特許文献1には、銀を含有するステンレス鋼において、大腸菌やサルモネラ菌に代表される病原性細菌の繁殖を効果的に抑制する効果を発現させるためには、鋼板表面における銀の存在形態が重要であり、使用時に金属状態のAgが表面に存在する必要があると示されている。
【0007】
【特許文献1】
特開平11−172379号公報
【0008】
【発明が解決しようとする課題】
しかしながら、ステンレス熱延鋼板を表面研削するに当たり、ステンレス熱延鋼板の表面研削能率をさらに上げるため、S添加剤を含有する研削油を用いて表面研削したところ、光輝焼鈍を経たステンレス冷延鋼板で抗菌性が認められなくなるという問題があった。
【0009】
本発明は、上記従来技術の問題点を解消することにあり、ステンレス熱延鋼板の表面研削能率を向上させることができ、鏡面光沢肌を有し、抗菌性を発現できるステンレス冷延鋼板を経済的に製造する方法およびその冷延用熱延鋼板を提供することを目的とする。
【0010】
【課題を解決するための手段】
本発明者等は、S添加剤を含有する研削油を用いて研削油の研削性能を高め、ステンレス熱延鋼板の研削能率を向上させることができると共に、S添加剤を含有する研削油を用いて表面研削されたステンレス熱延鋼板を、混酸水溶液中で酸洗することで、冷延用ステンレス熱延鋼板表面に存在する金属Agを増やし、ステンレス冷延鋼板の抗菌性を効果的に発現させることができるという知見を得て、本発明を完成させた。
【0011】
本発明の抗菌性を有するステンレス冷延鋼板の製造方法は、銀を含有するステンレス熱延鋼板を、S添加剤を含有する研削油を用いて表面研削し、その後、硝酸と弗酸の混酸水溶液中に浸漬し、鋼板表面に生成したAg化合物を除去し、そのあとの鋼板表面に新たに金属Agを存在させてから冷間圧延、光輝焼鈍することを特徴とする。
【0012】
その際、前記冷間圧延鈍する前のステンレス熱延鋼板の表面における、金属状態のAg個数/(金属状態のAg個数+Ag化合物個数)×100で定義した金属Ag個数比率を80%以上とすることが好ましい。
【0013】
また、本発明の抗菌性を有する冷延用ステンレス熱延鋼板は、鋼板表面に、表面研削により研削油中に添加されたS添加剤と反応することにより生成したAg化合物が硝酸と弗酸の混酸水溶液中に浸漬されたことによって除去されて、そのあとに新たに存在させた金属Agを有することを特徴とする。
【0014】
その場合、鋼板表面における、金属状態のAg個数/(金属状態のAg個数+Ag化合物個数)×100で定義した金属Ag個数比率が80%以上であることが好ましい。
【0015】
【発明の実施の形態】
以下、本発明の実施の形態に係る抗菌性を有するステンレス冷延鋼板の製造方法について説明する。
【0016】
本発明に用いる銀を含有するステンレス熱延鋼板は、公知の溶製方法で溶製された所定量の銀を含有するステンレス鋼溶鋼を用い、好ましくは連続鋳造法によりスラブとし、必要に応じて所定温度に加熱し、熱間圧延して得ることができる。このようにして得たステンレス熱延鋼板の銀含有量は、例えば、オーステナイト系ステンレス鋼で0.0005〜0.50質量%にすることができる。
【0017】
実施の形態に係る製造方法では、このようにして得た銀を含有するステンレス熱延鋼板を焼鈍、酸洗し、引き続いてS添加剤を含有する研削油を用いて表面研削する。焼鈍、酸洗されたステンレス熱延鋼板を研削油を用いて表面研削する理由は、焼鈍、酸洗されたステンレス熱延鋼板の表面には、脱Cr層が優先的に粒界浸食された凹部が存在しており、この凹部を除去しないまま、冷間圧延、光輝焼鈍、スキンパス圧延すると、凹部が幾分か平滑化されずに残存してしまい、鏡面光沢肌を有するステンレス冷延鋼板を製造することができないためである。
【0018】
実施の形態に係る製造方法では、焼鈍、酸洗されたステンレス熱延鋼板を表面研削するに当たり、S添加剤を含有する研削油を用いたので、S添加剤を含有しない研削油を用いた場合より研削油の研削性能を高めることができる。例えば、エンドレスの研磨ベルトを鋼板表面に押し付けて回転させるベルト式のホットコイル用グラインダーを用いてステンレス熱延鋼板を表面研削するに際し、S添加剤を含有する研削油を用いた場合には、S添加剤を含有しない研削油を用いた場合よりステンレス熱延鋼板の通板速度を速くすることができ、この結果、本発明においては、ステンレス熱延鋼板の表面研削能率を向上させることができるのである。
【0019】
一方、S添加剤を含有しない研削油を用いてステンレス熱延鋼板の通板速度を速めた場合には、研磨ベルトに研削屑が詰まる目詰まりが生じると共に発生する研削熱により目詰まりに起因して構成刃先が形成され、表面研削された後のステンレス熱延鋼板の表面が荒れてしまうなどの研削不良が発生してしまい、鏡面光沢肌を有するステンレス冷延鋼板を製造することができない。
【0020】
実施の形態に係る製造方法に用いるS添加剤としては、ステンレス熱延鋼板を表面研削する際に、発生する研削熱によりS添加剤のS(硫黄)と、鋼板表面に存在するFe、Cr等とが反応してFeS、CrSを生成し、ステンレス熱延鋼板の研削性を向上させるものを選択する。このためには、活性化した硫黄系添加剤が入っている研削油を用いるのが好ましい。活性化した硫黄系添加剤が入っている研削油を用いた場合には、表面研削時に発生する研削熱によりステンレス熱延鋼板の表面に存在するFe、Cr等と活性化した硫黄とが容易に反応し、研削性をより一層向上させることができる。
【0021】
なお、鏡面光沢肌を有するステンレス冷延鋼板を製造するための、好ましいステンレス熱延鋼板の表面研削量は、60〜200μm とすることができる。
【0022】
このように、S添加剤を含有する研削油を用いて研削油の研削性能を高め、ステンレス熱延鋼板の研削能率を向上させた場合には、ステンレス熱延鋼板の表面に存在する銀も硫黄と反応して、Ag2 SなどのAg化合物が生成してしまい、このステンレス熱延鋼板表面に生成したAg化合物は、冷間圧延、光輝焼鈍、スキンパス圧延しても鋼板表面に残って抗菌性を阻害する。
【0023】
そこで本発明の製造方法では、硝酸と弗酸の混酸水溶液中に浸漬し、鋼板表面に生成したAg化合物を除去し、そのあとの鋼板表面に新たに金属Agを存在させてから冷間圧延、光輝焼鈍するようにした。
【0024】
この理由は、冷間圧延した後にAg2 SなどのAg化合物を酸洗により除去しようとしたのでは鋼板長さが長くなり、効率的でなく、また一方、表面研削されたステンレス熱延鋼板の表面に存在するAg2 SなどのAg化合物を表面研削により物理的に除去しようとしたのでは、その際、Ag化合物が生成されるのを防止するのに、S添加剤を含有する研削油を使用できないために表面研削能率を高くできないという問題が発生する。このため、本発明の製造方法では、上記のようにS添加剤を含有する研削油を用いて表面研削したステンレス熱延鋼板を硝酸と弗酸の混酸水溶液中に浸漬し、鋼板表面に生成したAg化合物を除去し、そのあとの鋼板表面に新たに金属Agを存在させてから冷間圧延し、光輝焼鈍、必要に応じ、スキンパス圧延する製造工程を経てステンレス冷延鋼板とした。
【0025】
ここで、混酸水溶液中に浸漬した際、Ag2 SなどのAg化合物は、硝酸と弗酸の働きにより除去され、そのあとに新たに金属Agが鋼板表面に表れるので、冷延用熱延鋼板の表面に存在する、抗菌作用を発揮できる金属Agは、混酸水溶液中に浸漬しない場合に比べて増えることになる。
【0026】
以上説明した本発明の実施の形態に係る製造方法では、ステンレス熱延鋼板の表面研削能率を向上させるため、銀を含有するステンレス熱延鋼板をS添加剤を含有する研削油を用いて表面研削し、その後、硝酸と弗酸の混酸水溶液中に浸漬し、鋼板表面に生成したAg化合物を除去し、そのあとの鋼板表面に新たに金属Agを存在させてから冷間圧延、光輝焼鈍するようにしたので、ステンレス熱延鋼板の表面研削能率を上げることができ、特にSUS304 BA 材のような鏡面光沢肌を有するステンレス冷延鋼板において抗菌性を有利に発現させることができる。
【0027】
その際、冷間圧延鈍する前のステンレス熱延鋼板の表面における、金属状態のAg個数/(金属状態のAg個数+Ag化合物個数)×100(%)で定義した金属Ag個数比率を80%以上とすることが好ましい。
【0028】
この理由は、冷間圧延、光輝焼鈍、必要に応じ、スキンパス圧延して製造したステンレス冷延鋼板の抗菌性が熱延鋼板表面における後述するようにして測定した、鋼板表面における金属Ag個数比率と対応しており、ステンレス熱延鋼板の表面における、金属Ag個数比率を80%以上とすることにより、抗菌性を有する BA 仕上げステンレス冷延鋼板を経済的に製造できることがわかったからである。説明するまでもなく、硝酸と弗酸の混酸水溶液中に浸漬された鋼板には、その後、水洗処理やリンス処理、乾燥処理などを施すのが普通である。
【0029】
このようにして得た、冷間圧延に供する冷延用ステンレス熱延鋼板は、その表面に、表面研削により研削油中に添加されたS添加剤と反応することにより生成したAg化合物が硝酸と弗酸の混酸水溶液中に浸漬されたことによって除去され、そのあとに新たに存在させた金属Agを有する。
【0030】
Ag化合物が混酸水溶液中に浸漬されたことによって除去され、その下に存在する金属Agを最表面に出し、最表面に存在するようにした金属Agのことを新生金属Agということにすると、本発明の冷延用ステンレス熱延鋼板は、その表面に新生金属Agを有するようにされている。
【0031】
ところで、銀を含有するステンレス熱延鋼板をS添加剤を含有しない研削油を用いて表面研削した場合、鋼板表面にAg化合物が生成されないので、新生金属Agというものは、鋼板表面に存在しない。この新生金属AgおよびAg化合物の両方が鋼板表面に存在しない冷延用ステンレス熱延鋼板は、熱延鋼板の表面研削能率を低くして製造したものであるから、抗菌性を有するステンレス冷延鋼板のコストが高くなる。
【0032】
一方、ステンレス熱延鋼板の表面研削能率を向上させるため、銀を含有するステンレス熱延鋼板をS添加剤を含有する研削油を用いて表面研削し、その後、硝酸と弗酸の混酸水溶液中に浸漬しない場合、鋼板表面に生成されたAg化合物が除去されず、冷延用ステンレス熱延鋼板表面にそのまま残り、上記の新生金属Agは鋼板表面に存在しない。鋼板表面に、新生金属Agが存在せず、Ag化合物が存在する冷延用ステンレス熱延鋼板は、熱延鋼板の表面研削能率は高くして製造されているが、経済的にAg化合物を除去し、新たに金属Agを鋼板表面に存在させて、抗菌性を有するステンレス冷延鋼板とするのは困難である。
【0033】
本発明の実施の形態に係る製造方法において、ステンレス熱延鋼板の焼鈍温度は、公知の温度範囲である1050〜1150℃、光輝焼鈍(BA処理)は、公知の還元性雰囲気下で公知の温度範囲である1050〜1150℃とすることができる。また、本発明の実施の形態に係る製造方法において、冷間圧延する際の圧下率は、55〜95%、および光輝焼鈍した後のスキンパス圧延する際の伸び率は、0.1〜1.2%とすることができる。
【0034】
【実施例】
銀を350ppm 含有する厚みが4mmのオーステナイト系ステンレス熱延鋼板SUS304を1100℃で焼鈍し、その後酸洗し、引き続いてS添加剤を含有する研削油を用いてホットコイル用グラインダーにより表面を100μm 表面研削した。表面研削する際の通板速度はS添加剤を含有しない場合の200%とした。S添加剤を含有する研削油を用いて表面研削されたステンレス熱延鋼板SUS304を混酸水溶液(温度50℃、硝酸濃度5vol %、弗酸濃度4vol %)中に15秒間浸漬し、その後冷間圧延、光輝焼鈍、スキンパス圧延して板厚が1mmのステンレス冷延鋼板を製造し、発明例とした。得られたステンレス冷延鋼板の表面状態と抗菌性を調べた。なお、ステンレス熱延鋼板は、20段ゼンジミアミルを用いて冷間圧延し、光輝焼鈍処理は、還元性雰囲気下で温度を1100℃として行った。
【0035】
なお、混酸水溶液の温度及び浸漬時間は、図1からS添加剤を含有する研削油を用いて表面研削されたステンレス熱延鋼板の表面における、金属状態のAg個数/(金属状態のAg個数+Ag化合物個数)×100で定義した金属Ag個数比率が90%以上となる酸洗条件とした。
【0036】
図1は、上記S添加剤を含有する研削油を用いてホットコイル用グラインダーにより表面を100μm 表面研削したステンレス熱延鋼板SUS304のホットコイルを複数用意し、混酸水溶液の温度と浸漬時間の水準を変えて、各ホットコイル表面のAg2 Sを酸洗により除去する予備実験を行って得た。混酸水溶液は、硝酸濃度5vol %、弗酸濃度4vol %とした。ここで、金属Ag個数比率は、各ホットコイルから採取したサンプル板をそれぞれ用い、Ag系析出物によって測定した金属状態のAg個数と、Ag2 SやAg酸化物などのAg化合物個数を測定し、上述したようにして算出した。これらの個数は、AESおよびTEM装置を用い、測定することができる。サンプル板1箇所あたり20個以上のAg系析出物を対象として、5箇所のAg比率の平均を求め、これを金属Ag個数比率と定義した。
〔表面状況〕 表面が鏡面光沢肌であるか否かは、目視により評価した。熱延鋼板の表面研削時に生じた研削不良に起因する光沢不良部が認められた場合は、鏡面光沢肌が得られていないと判定した。
〔抗菌性試験〕 抗菌製品技術協議会のフィルム密着法(JIS Z 2801)に準拠し、評価した。
▲1▼試験体(50mm×50mm)を99.9%エタノール含有脱脂綿等で洗浄・脱脂する。▲2▼大腸菌を1/500 NB溶液に分散する。(菌の個数は2.0×105 〜1.0×106 cfu/mlに調整した。1/500 NB溶液とは、普通ブイオン培地(NB)を減菌精整水で500倍に希釈したものである。)▲3▼菌液を0.4ml/ 25cm2 の割合で試験片(各3個)に接種する。▲4▼試験体表面にポリエチレン製フィルムを被せる。▲5▼温度35℃±1.0℃、相対湿度RH90%以上の条件で24時間保存する。▲6▼生菌数の測定は寒天培養法(35℃±1.0℃、40〜48hr)により行った。抗菌性は、次式で定義される減菌率≧99%で抗菌性あり、減菌率<99%で抗菌性なしと評価した。
減菌率=(比較鋼の生菌数−サンプル板の生菌数)/比較鋼の生菌数×100
但し、比較鋼の生菌数とは、抗菌処理を施さないステンレス冷延鋼板の抗菌試験後の生菌数をいう。
【0037】
但し、比較例1、2は、発明例と同じ規格のステンレス熱延鋼板を用い、発明例と同じ条件で焼鈍、酸洗し、引き続いて表2に示す研削油を用いて表面研削し、冷間圧延、光輝焼鈍、スキンパス圧延して得たステンレス冷延鋼板からサンプル板を採取した。比較例1、2におけるステンレス熱延鋼板を表面研削する際の通板速度は発明例と同じとした。
【0038】
表1には、発明例における銀を含有する熱延鋼板SUS304の成分を示した。また、発明例および比較例1、2におけるBA仕上げサンプル板の表面状況と抗菌性の結果を表2に示す。
【0039】
【表1】
【0040】
【表2】
【0041】
発明例では、S添加剤を含有する研削油を用いたので、ステンレス熱延鋼板の表面研削能率を上げて表面研削することができ、しかも、S添加剤を含有する研削油を用いて表面研削されたステンレス熱延鋼板を硝酸と弗酸の混酸水溶液中に浸漬し、表面に生成したAg2 Sを除去して、そのあとの鋼板表面に新たに金属Agを存在させてから冷間圧延するようにしたので、鏡面光沢肌を有するサンプル板において抗菌性を発現させることができた。
【0042】
一方、比較例1では、S添加剤を含有しない研削油を用い、ステンレス熱延鋼板を表面研削する際の通板速度を発明例と同じとしたので、研削不良に起因する光沢不良部がサンプル板に発生した。また、比較例2では、S添加剤を含有する研削油を用いて表面研削し、表面に生成したAg2 Sを除去せずに冷間圧延したので、サンプル板は抗菌性が発現できなかった。
【0043】
なお、上記予備実験に用いたのと同じ条件で酸洗したホットコイルを用い、冷間圧延、光輝焼鈍、スキンパス圧延して得たサンプル板の抗菌性を調査することより、金属Ag個数比率(%)=金属状態のAg個数/(金属状態のAg個数+Ag化合物個数)×100を80%以上とすることで抗菌性が認められた。
【0044】
S添加剤を含有する研削油を用いて表面研削され、その後酸洗されたオーステナイト系ステンレス熱延鋼板の表面における金属Ag個数比率を80%以上とするには、図1に示したとおり、温度が35℃以上の混酸水溶液(硝酸濃度5vol %、弗酸濃度4vol %)中に10秒以上浸漬させればよい。また、サンプル板の抗菌性とS添加剤を含有する研削油を用いて表面研削され、その後、硝酸と弗酸の混酸水溶液中に浸漬し、表面に生成したAg2 Sを除去したホットコイル表面の抗菌性とは、一対一に対応することも判明した。
【0045】
【発明の効果】
本発明により、ステンレス熱延鋼板の表面研削能率を向上させることができ、鏡面光沢肌を有し、抗菌性を発現できるステンレス冷延鋼板を経済的に製造することができる。
【図面の簡単な説明】
【図1】実施例に用いたステンレス熱延鋼板SUS304を混酸水溶液に浸漬した場合の、金属Ag比率に及ぼす混酸水溶液の温度と浸漬時間の影響を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for economically producing a stainless steel cold-rolled steel sheet having antibacterial properties, and in particular, a method for economically producing a brightly annealed stainless steel cold-rolled steel plate having a specular skin and exhibiting antibacterial properties. And a hot-rolled steel sheet for cold rolling.
[0002]
[Prior art]
Among stainless steel cold-rolled steel sheets, stainless steel cold-rolled steel sheets having a specular polished skin such as SUS304 BA material are used in daily life-related products, medical equipment, and building materials. Stainless cold-rolled steel sheet represented by SUS304 BA material is a hot-rolled steel sheet that is annealed and pickled, and then the surface of the hot-rolled steel sheet is surface-ground using a grinding oil of about 100 μm, followed by cold rolling and bright annealing. Generally, it is manufactured by skin pass rolling.
[0003]
The reason for surface grinding of stainless steel hot-rolled steel sheet is that the surface of the annealed and pickled stainless steel hot-rolled steel sheet has a recess where the Cr-free layer is preferentially eroded by grain boundaries, and this recess is not removed. This is because, when cold rolling, bright annealing, and skin pass rolling are performed, the concave portions remain somewhat unsmoothed, and a product having a specular gloss skin cannot be manufactured. Moreover, the reason why the grinding oil is used when the surface of the stainless hot-rolled steel sheet is ground is that the grindability of the stainless hot-rolled steel sheet is good and a product having a specular gloss skin is obtained.
[0004]
For example, using a belt-type hot coil grinder that presses and rotates an endless polishing belt against the surface of a steel plate, and grinding the surface of a stainless hot-rolled steel plate, when grinding oil is not used, the polishing belt is clogged with grinding debris. Grinding heat such as clogging occurs and a cutting edge is formed due to clogging due to clogging and the surface of the stainless hot-rolled steel sheet after surface grinding becomes rough. When such grinding failure occurs, it becomes very difficult to obtain a stainless cold-rolled steel sheet product having a specular gloss skin.
[0005]
Therefore, a stainless cold-rolled steel sheet represented by SUS304 BA material is manufactured by surface grinding using a grinding oil, and then cold rolling, bright annealing, and skin pass rolling.
[0006]
By the way, as a stainless steel plate having antibacterial properties, a predetermined amount of silver, for example, austenitic stainless steel containing 0.0005 to 0.50 mass% is known (Patent Document 1). In Patent Document 1, in the stainless steel containing silver, in order to express the effect of effectively suppressing the propagation of pathogenic bacteria represented by Escherichia coli and Salmonella, the presence form of silver on the steel sheet surface is important. Yes, it is indicated that Ag in the metallic state needs to be present on the surface during use.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-172379
[Problems to be solved by the invention]
However, in order to further improve the surface grinding efficiency of the stainless hot-rolled steel sheet in surface grinding of the stainless hot-rolled steel sheet, the surface is ground using a grinding oil containing an S additive. There was a problem that antibacterial properties were not recognized.
[0009]
The present invention is to solve the above-mentioned problems of the prior art, and it is possible to improve the surface grinding efficiency of a stainless hot rolled steel sheet, to provide a stainless cold rolled steel sheet that has a mirror gloss skin and can exhibit antibacterial properties. An object of the present invention is to provide a manufacturing method and a hot-rolled steel sheet for cold rolling.
[0010]
[Means for Solving the Problems]
The present inventors can improve the grinding performance of the grinding oil using the grinding oil containing the S additive, improve the grinding efficiency of the stainless hot-rolled steel sheet, and use the grinding oil containing the S additive. The surface-ground stainless steel hot-rolled steel sheet is pickled in a mixed acid aqueous solution to increase the amount of metal Ag present on the surface of the cold-rolled stainless steel hot-rolled steel sheet and effectively develop the antibacterial properties of the stainless steel cold-rolled steel sheet. The present invention has been completed with the knowledge that it is possible.
[0011]
The method for producing an antibacterial stainless cold-rolled steel sheet according to the present invention comprises subjecting a stainless hot-rolled steel sheet containing silver to surface grinding with a grinding oil containing an S additive, and then a mixed acid aqueous solution of nitric acid and hydrofluoric acid. It is characterized by being immersed in the steel plate, removing the Ag compound formed on the surface of the steel sheet, and then making metal Ag newly present on the surface of the subsequent steel sheet, followed by cold rolling and bright annealing.
[0012]
At that time, the ratio of Ag number in metal state / (Ag number in metal state + Ag compound number) × 100 on the surface of the stainless hot-rolled steel sheet before the cold rolling annealing is set to 80% or more. Is preferred.
[0013]
The anti-bacterial stainless hot-rolled steel sheet for cold rolling according to the present invention has an Ag compound formed by reacting with the S additive added to the grinding oil by surface grinding on the steel sheet surface. It is characterized by having a metal Ag newly removed after being immersed in a mixed acid aqueous solution.
[0014]
In that case, it is preferable that the metal Ag number ratio defined by the number of Ag in the metal state / (the number of Ag in the metal state + the number of Ag compounds) × 100 on the steel sheet surface is 80% or more.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the manufacturing method of the stainless steel cold-rolled steel plate which has antibacterial property concerning embodiment of this invention is demonstrated.
[0016]
The stainless hot-rolled steel sheet containing silver used in the present invention uses a stainless steel molten steel containing a predetermined amount of silver melted by a known melting method, preferably a slab by a continuous casting method, and if necessary. It can be obtained by heating to a predetermined temperature and hot rolling. The silver content of the stainless hot-rolled steel sheet thus obtained can be 0.0005 to 0.50% by mass, for example, with austenitic stainless steel.
[0017]
In the manufacturing method according to the embodiment, the stainless hot-rolled steel sheet containing silver thus obtained is annealed, pickled, and subsequently surface ground using a grinding oil containing S additive. The reason for surface grinding the annealed and pickled stainless hot-rolled steel sheet with grinding oil is that the surface of the annealed and pickled stainless hot-rolled steel sheet has a recess where the Cr-free layer is preferentially eroded by grain boundaries. When cold rolling, bright annealing, and skin pass rolling are performed without removing the concave portion, the concave portion remains without being smoothed somewhat, and a stainless cold-rolled steel sheet having a specular gloss skin is produced. This is because it cannot be done.
[0018]
In the manufacturing method according to the embodiment, since the grinding oil containing the S additive is used for surface grinding of the annealed and pickled stainless hot-rolled steel sheet, the grinding oil containing no S additive is used. The grinding performance of the grinding oil can be further increased. For example, when surface-grinding a stainless hot-rolled steel sheet using a belt-type hot coil grinder that rotates by pressing an endless polishing belt against the surface of the steel sheet, when using a grinding oil containing an S additive, The threading speed of the stainless hot-rolled steel sheet can be increased as compared with the case of using a grinding oil that does not contain an additive. As a result, in the present invention, the surface grinding efficiency of the stainless hot-rolled steel sheet can be improved. is there.
[0019]
On the other hand, when the threading speed of the stainless hot-rolled steel sheet is increased using a grinding oil containing no S additive, the abrasive belt is clogged with grinding debris and is caused by clogging due to generated grinding heat. As a result, a poor grinding such as the surface of the stainless hot-rolled steel sheet is roughened after the structured cutting edge is formed and the surface is ground, and a stainless cold-rolled steel sheet having a specular gloss skin cannot be manufactured.
[0020]
As the S additive used in the manufacturing method according to the embodiment, S (sulfur) of the S additive and Fe, Cr, etc. present on the steel sheet surface by the grinding heat generated when surface grinding of the stainless hot-rolled steel sheet is performed. React with each other to produce FeS and CrS and improve the grindability of the stainless hot-rolled steel sheet. For this purpose, it is preferable to use a grinding oil containing an activated sulfur-based additive. When grinding oil containing activated sulfur-based additives is used, Fe, Cr, etc. present on the surface of stainless hot-rolled steel sheet and activated sulfur are easily generated by grinding heat generated during surface grinding. It can react and grindability can be improved further.
[0021]
In addition, the surface grinding amount of a preferable stainless hot-rolled steel plate for manufacturing a stainless cold-rolled steel plate having a specular gloss skin can be set to 60 to 200 μm.
[0022]
In this way, when the grinding oil containing the S additive is used to improve the grinding performance of the grinding oil and improve the grinding efficiency of the stainless hot-rolled steel sheet, the silver present on the surface of the stainless hot-rolled steel sheet is also sulfur. The Ag compound such as Ag 2 S is produced by the reaction with the steel, and the Ag compound formed on the surface of the stainless hot rolled steel sheet remains on the surface of the steel sheet even after cold rolling, bright annealing, and skin pass rolling. Inhibits.
[0023]
Therefore, in the production method of the present invention, the steel is immersed in a mixed acid aqueous solution of nitric acid and hydrofluoric acid, the Ag compound formed on the steel sheet surface is removed, and after the metal Ag is newly present on the steel sheet surface, cold rolling is performed. Bright annealing was performed.
[0024]
The reason for this is that if the Ag compound such as Ag 2 S is removed by pickling after cold rolling, the length of the steel sheet becomes long and is not efficient. If an Ag compound such as Ag 2 S present on the surface is physically removed by surface grinding, a grinding oil containing an S additive is used to prevent the formation of the Ag compound. Since it cannot be used, there arises a problem that the surface grinding efficiency cannot be increased. For this reason, in the production method of the present invention, a stainless hot-rolled steel sheet surface-ground using the grinding oil containing the S additive as described above was immersed in a mixed acid aqueous solution of nitric acid and hydrofluoric acid to form on the steel sheet surface. After the Ag compound was removed and metal Ag was newly present on the surface of the steel sheet after that, cold rolling was performed, and bright annealing was performed, and if necessary, a stainless cold-rolled steel sheet was obtained through a manufacturing process of skin pass rolling.
[0025]
Here, when immersed in the mixed acid aqueous solution, the Ag compound such as Ag 2 S is removed by the action of nitric acid and hydrofluoric acid, and after that, metal Ag newly appears on the surface of the steel sheet. The amount of metal Ag that can exhibit antibacterial action existing on the surface of the metal increases as compared with the case where it is not immersed in the mixed acid aqueous solution.
[0026]
In the manufacturing method according to the embodiment of the present invention described above, in order to improve the surface grinding efficiency of the stainless hot-rolled steel sheet, the surface of the stainless hot-rolled steel sheet containing silver is ground using the grinding oil containing the S additive. Then, it is immersed in a mixed acid aqueous solution of nitric acid and hydrofluoric acid to remove the Ag compound formed on the surface of the steel sheet, and after the metal Ag is newly present on the surface of the subsequent steel sheet, cold rolling and bright annealing are performed. Therefore, the surface grinding efficiency of the stainless hot-rolled steel sheet can be increased, and antibacterial properties can be advantageously expressed particularly in a stainless cold-rolled steel sheet having a specular gloss skin such as SUS304 BA material.
[0027]
At that time, the ratio of the number of metal Ag defined by the number of Ag in the metal state / (the number of Ag in the metal state + the number of Ag compounds) × 100 (%) on the surface of the stainless hot-rolled steel sheet before cold rolling is 80% or more. It is preferable to do.
[0028]
The reason for this is that the antibacterial properties of the stainless cold-rolled steel sheet manufactured by cold rolling, bright annealing, and skin pass rolling as necessary were measured as described later on the surface of the hot-rolled steel sheet, and the number ratio of Ag metal on the steel sheet surface. This is because it was found that a BA-finished stainless cold-rolled steel sheet having antibacterial properties can be economically produced by setting the metal Ag number ratio on the surface of the stainless hot-rolled steel sheet to 80% or more. Needless to say, a steel plate immersed in a mixed acid aqueous solution of nitric acid and hydrofluoric acid is usually subjected to a washing treatment, a rinsing treatment, a drying treatment, and the like.
[0029]
The stainless hot-rolled steel sheet for cold rolling to be used for cold rolling thus obtained has a surface formed by reacting with the S additive added to the grinding oil by surface grinding, and the Ag compound produced by reacting with nitric acid. It is removed by being immersed in a mixed acid aqueous solution of hydrofluoric acid, and thereafter has newly contained metal Ag.
[0030]
When the Ag compound is removed by being immersed in the mixed acid aqueous solution, the metal Ag existing thereunder is taken out to the outermost surface, and the metal Ag that is made to exist on the outermost surface is referred to as new metal Ag. The stainless hot-rolled steel sheet for cold rolling according to the invention has a new metal Ag on its surface.
[0031]
By the way, when the surface of a stainless hot-rolled steel sheet containing silver is ground using a grinding oil that does not contain an S additive, no Ag compound is generated on the steel sheet surface, so that the new metal Ag does not exist on the steel sheet surface. The stainless hot-rolled steel sheet for cold rolling in which both the new metal Ag and the Ag compound are not present on the surface of the steel sheet is manufactured by reducing the surface grinding efficiency of the hot-rolled steel sheet. The cost of
[0032]
On the other hand, in order to improve the surface grinding efficiency of the stainless hot-rolled steel sheet, the surface of the stainless-steel hot-rolled steel sheet containing silver is ground using a grinding oil containing S additive, and then mixed in a mixed acid aqueous solution of nitric acid and hydrofluoric acid. When not immersed, the Ag compound produced on the steel sheet surface is not removed and remains on the surface of the cold-rolled stainless hot-rolled steel sheet, and the new metal Ag does not exist on the steel sheet surface. Stainless steel hot rolled steel sheet for cold rolling, which has no new metal Ag on the surface of the steel sheet and has an Ag compound, is manufactured with a high surface grinding efficiency of the hot rolled steel sheet, but economically removes the Ag compound. However, it is difficult to newly provide metal Ag on the surface of the steel sheet to obtain an antibacterial stainless cold-rolled steel sheet.
[0033]
In the manufacturing method according to the embodiment of the present invention, the annealing temperature of the stainless hot-rolled steel sheet is a known temperature range of 1050 to 1150 ° C., and the bright annealing (BA treatment) is a known temperature under a known reducing atmosphere. It can be set as 1050-1150 degreeC which is the range. Moreover, in the manufacturing method which concerns on embodiment of this invention, the reduction rate at the time of cold rolling is 55 to 95%, and the elongation rate at the time of skin pass rolling after bright annealing is 0.1 to 1. It can be 2%.
[0034]
【Example】
An austenitic stainless hot rolled steel sheet SUS304 containing 350 ppm of silver and having a thickness of 4 mm is annealed at 1100 ° C., then pickled, and subsequently the surface is 100 μm by a hot coil grinder using grinding oil containing S additive. Grinded. The plate passing speed at the time of surface grinding was 200% when no S additive was contained. Stainless steel hot rolled steel sheet SUS304 surface-ground using a grinding oil containing S additive is immersed in a mixed acid aqueous solution (temperature: 50 ° C., nitric acid concentration: 5 vol%, hydrofluoric acid concentration: 4 vol%), and then cold rolled. A stainless steel cold-rolled steel sheet having a thickness of 1 mm was manufactured by bright annealing and skin pass rolling, and was used as an invention example. The surface condition and antibacterial properties of the obtained stainless cold-rolled steel sheet were examined. The stainless hot-rolled steel sheet was cold-rolled using a 20-stage Sendzimir mill, and the bright annealing treatment was performed at a temperature of 1100 ° C. in a reducing atmosphere.
[0035]
The temperature and immersion time of the mixed acid aqueous solution are shown in FIG. 1. The number of Ag in the metal state / (the number of Ag in the metal state + Ag on the surface of the stainless hot-rolled steel sheet surface-ground using the grinding oil containing the S additive). The pickling conditions were such that the metal Ag number ratio defined by (number of compounds) × 100 was 90% or more.
[0036]
FIG. 1 shows a plurality of hot coils of stainless steel hot rolled steel sheet SUS304 whose surface is ground by a hot coil grinder using a grinding oil containing the above S additive. varied to give the Ag 2 S of each hot coil surface by performing a preliminary experiment to be removed by pickling. The mixed acid aqueous solution had a nitric acid concentration of 5 vol% and a hydrofluoric acid concentration of 4 vol%. Here, the metal Ag number ratio is obtained by measuring the number of Ag in a metal state measured by Ag-based precipitates and the number of Ag compounds such as Ag 2 S and Ag oxide using sample plates collected from each hot coil. Calculated as described above. These numbers can be measured using AES and TEM equipment. For 20 or more Ag-based precipitates per one sample plate, the average of the five Ag ratios was determined, and this was defined as the metal Ag number ratio.
[Surface condition] It was visually evaluated whether or not the surface had a specular gloss skin. When a poor gloss portion due to grinding failure generated during surface grinding of the hot-rolled steel sheet was observed, it was determined that a mirror gloss skin was not obtained.
[Antibacterial property test] It was evaluated in accordance with the film adhesion method (JIS Z 2801) of the Antibacterial Product Technical Council.
(1) Wash and degrease the specimen (50 mm × 50 mm) with absorbent cotton containing 99.9% ethanol. (2) Disperse E. coli in 1/500 NB solution. (The number of bacteria was adjusted to 2.0 × 10 5 to 1.0 × 10 6 cfu / ml. The 1/500 NB solution is a normal buoyant medium (NB) diluted 500 times with sterilized purified water. (3) Inoculate the test solution (3 each) at a rate of 0.4 ml / 25 cm 2 . (4) Put a polyethylene film on the surface of the specimen. (5) Store for 24 hours under conditions of
Bactericidal rate = (viable bacterial count of comparative steel-viable bacterial count of sample plate) / viable bacterial count of comparative steel x 100
However, the viable count of the comparative steel refers to the viable count after the antibacterial test of the stainless cold-rolled steel sheet not subjected to the antibacterial treatment.
[0037]
However, Comparative Examples 1 and 2 use stainless hot-rolled steel sheets of the same standard as the inventive examples, anneal and pickle under the same conditions as the inventive examples, and subsequently surface grind using the grinding oil shown in Table 2, A sample plate was taken from a stainless cold-rolled steel plate obtained by hot rolling, bright annealing, and skin pass rolling. The plate passing speed at the time of surface grinding of the stainless hot-rolled steel sheets in Comparative Examples 1 and 2 was the same as that of the invention examples.
[0038]
Table 1 shows components of hot-rolled steel sheet SUS304 containing silver in the invention examples. Table 2 shows the surface condition and antibacterial results of the BA-finished sample plates in Invention Examples and Comparative Examples 1 and 2.
[0039]
[Table 1]
[0040]
[Table 2]
[0041]
In the invention example, since the grinding oil containing the S additive was used, the surface grinding efficiency of the stainless hot-rolled steel sheet can be increased and surface grinding can be performed, and the surface grinding can be performed using the grinding oil containing the S additive. The stainless hot-rolled steel sheet is immersed in a mixed acid aqueous solution of nitric acid and hydrofluoric acid, Ag 2 S formed on the surface is removed, and after the metal Ag is newly present on the surface of the subsequent steel sheet, cold rolling is performed. Since it did it, it was able to express antibacterial property in the sample board which has specular gloss skin.
[0042]
On the other hand, in Comparative Example 1, a grinding oil containing no S additive was used, and the passing speed when surface grinding a stainless hot-rolled steel sheet was the same as that of the invention example. Occurs on the board. In Comparative Example 2, surface grinding was performed using a grinding oil containing an S additive, and cold rolling was performed without removing Ag 2 S generated on the surface, so that the sample plate could not exhibit antibacterial properties. .
[0043]
By using a hot coil pickled under the same conditions as used in the preliminary experiment, and examining the antibacterial properties of the sample plate obtained by cold rolling, bright annealing, and skin pass rolling, the ratio of the number of metal Ag ( %) = Ag number in the metal state / (Ag number in the metal state + Ag compound number) × 100 was set to 80% or more, and antibacterial properties were recognized.
[0044]
In order to make the metal Ag number ratio on the surface of the austenitic stainless hot-rolled steel sheet surface-ground using a grinding oil containing an S additive and then pickled, as shown in FIG. May be immersed in a mixed acid aqueous solution (
[0045]
【The invention's effect】
According to the present invention, the surface grinding efficiency of a stainless hot-rolled steel sheet can be improved, and a stainless cold-rolled steel sheet having a specular gloss skin and exhibiting antibacterial properties can be produced economically.
[Brief description of the drawings]
FIG. 1 is a graph showing the influence of the temperature and immersion time of a mixed acid aqueous solution on the metal Ag ratio when the stainless hot-rolled steel sheet SUS304 used in the examples is immersed in a mixed acid aqueous solution.
Claims (4)
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JP2015206070A (en) * | 2014-04-18 | 2015-11-19 | 株式会社神戸製鋼所 | Method for manufacturing antibacterial titanium alloy material |
CN109332418A (en) * | 2018-09-27 | 2019-02-15 | 山西太钢不锈钢股份有限公司 | For improve 300 be stainless steel BA plate surface grade technique |
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JP2015206070A (en) * | 2014-04-18 | 2015-11-19 | 株式会社神戸製鋼所 | Method for manufacturing antibacterial titanium alloy material |
CN109332418A (en) * | 2018-09-27 | 2019-02-15 | 山西太钢不锈钢股份有限公司 | For improve 300 be stainless steel BA plate surface grade technique |
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