JP2000501787A - Plating method for steel sheet containing alloy elements that are easily oxidized - Google Patents
Plating method for steel sheet containing alloy elements that are easily oxidizedInfo
- Publication number
- JP2000501787A JP2000501787A JP9521803A JP52180397A JP2000501787A JP 2000501787 A JP2000501787 A JP 2000501787A JP 9521803 A JP9521803 A JP 9521803A JP 52180397 A JP52180397 A JP 52180397A JP 2000501787 A JP2000501787 A JP 2000501787A
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- JP
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- Prior art keywords
- steel sheet
- steel
- atmosphere
- annealing
- plating
- Prior art date
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- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 116
- 239000010959 steel Substances 0.000 title claims abstract description 116
- 238000007747 plating Methods 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 29
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 19
- 239000000956 alloy Substances 0.000 title claims abstract description 19
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 70
- 238000000137 annealing Methods 0.000 claims abstract description 46
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 35
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 21
- 239000010703 silicon Substances 0.000 claims abstract description 21
- 230000001590 oxidative effect Effects 0.000 claims abstract description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 238000004320 controlled atmosphere Methods 0.000 claims description 3
- 239000006104 solid solution Substances 0.000 claims description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 17
- 239000010410 layer Substances 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 238000012360 testing method Methods 0.000 description 8
- 229910000976 Electrical steel Inorganic materials 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000005121 nitriding Methods 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 229910001337 iron nitride Inorganic materials 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- 229910001327 Rimmed steel Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Coating With Molten Metal (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Manufacturing Of Steel Electrode Plates (AREA)
- Chemical Treatment Of Metals (AREA)
Abstract
(57)【要約】 鋼板を０．００５％〜１％のアンモニアを含む非酸化性アニーリング雰囲気中でアニーリングした後にメッキ浴中に熱浸漬する方法。特に酸化し易い合金元素として０．２％以上のケイ素を含む鋼に適用される。鋼の初期機械的および／または電気的特性を維持したままメッキ浴中での鋼の湿潤性を向上させる。 (57) [Summary] A method in which a steel sheet is annealed in a non-oxidizing annealing atmosphere containing 0.005% to 1% ammonia and then hot-immersed in a plating bath. In particular, it is applied to steel containing 0.2% or more of silicon as an easily oxidizable alloy element. Improve the wettability of the steel in the plating bath while maintaining the initial mechanical and / or electrical properties of the steel.
Description
【発明の詳細な説明】 酸化し易い合金元素を含む鋼板のメッキ方法 本発明は酸化し易い合金元素（添加元素）、特にケイ素を含む鋼板のメッキ方 法に関するものである。 鋼板の用途、特に電気分野や機械強度を必要とする用途では酸化し易い合金元 素、特にケイ素を含む鋼が用いられる。これらの用途では高い耐腐食性も求めら れる。しかし、メッキによって十分な耐腐食性を得ることはこれまで困難である とされてきた。 この問題は鋼板に含まれる酸化し易い合金元素、特にケイ素の存在によってメ ッキ浴中で鋼板が十分に湿らないこと（湿潤不良）から生じ、結果的には被膜の 性質、特に均質性が低下する。 ケイ素鋼の場合、ケイ素含有率が約０．２％に達すると湿潤性に問題が生じ、 それ以下の含有率でも問題が生じることがある。 酸化し易い合金元素の含有率が低い鋼は従来法でメッキでき、被覆すべき鋼板 を清浄し、非酸化性または還元性雰囲気中でアニーリング処理した後、鋼板をメ ッキ浴中に浸漬する公知の方法で被覆することができる。 問題が生じるのは、高い耐腐食性と機械強度または特殊な電気特性の両方を同 時に有するメッキ鋼板を得るために合金元素の含有率の高い鋼にメッキをする場 合である。 一方、酸化し易い合金元素高濃度に含む、例えばケイ素を０．３〜３％含む鋼 にメッキする方法が知られている。この方法では鋼板に追加の処理をしてからメ ッキ浴中に浸漬する。例えば日本特許第JP-51-40711号には、鋼板を処理溶液中 に浸漬して窒化鉄（ＦｅＮ）の薄い複合層を付ける追加の電気化学的処理が記載 されている。この複合層は１ｇ／ｍ2以下の厚さで、３％以下のケイ素を含む鋼 板に形成でき、これによってメッキ浴中での鋼板の湿潤性は大幅に改良される。 しかし、この特許に記載の解決策はメッキ鋼板の製造に追加の操作を必要とし 、経済的に不利である。また、鋼板／メッキ層界面で鋼板を過度に窒化したり、 および／または、１ｇ／界面ｍ2以上の厚さに相当する過度に厚い窒化鉄の 層を形成すると、鋼の機械的または電気的特性が低下する危険性がある。 既に述べたように、酸化し易い合金元素、特にケイ素を含む鋼は特殊な機械的 および／または電気的特性を利用するために用いられている。 本発明の目的は、鋼の機械的および／または電気的特性を低下させずに、酸化 し易い合金元素、特にケイ素を高い含有率で含む鋼板にメッキする経済な方法を 提供することにある。 本発明の対象は、鋼板を非酸化性のアニーリング雰囲気中でアニーリングした 後にメッキ浴中に熱浸漬する方法において、アニーリング雰囲気が０．００５％ 〜１％のアンモニアを含むことを特徴とする方法にある。 本発明は均質なメッキ被膜が得るのに必要なメッキ浴中での鋼板の湿潤性を妨 げるような比率で酸化し易い合金元素を含む鋼板に適用することができる。 本発明は特に０．２％以上のケイ素を含む鋼板に適用される。 本発明は下記特性ａ）および／またはｂ）をさらに有することができる： ａ） アニーリング雰囲気が０．０２％〜０．５％のアンモニアを含む。 ｂ） 鋼板のアニーリング雰囲気中の滞留時間は３分以下である。 本発明の他の対象は、制御された雰囲気中で鋼板をアニーリングする手段と、 この手段の下流に設けられたアニーリング済み鋼板をメッキ浴中に熱浸漬する手 段と、雰囲気を制御する手段とを有する請求項１〜３のいずれか一項に記載の方 法を実施するための鋼板のメッキ装置において、鋼板がアニーリング手段に入る 位置の近くで雰囲気中にアンモニアを導入し、雰囲気制御手段は雰囲気中のアン モニア濃度を０．００５〜１％に維持することを特徴とする装置にある。 本発明のさらに他の対象は、鋼とメッキ層との間に固溶体の窒素を含む境界 層を有する本発明方法でメッキされた酸化し易い合金元素、特にケイ素を含む鋼 板において、境界層の厚さが境界面積１ｍ2当たり少なくとも１グラムに相当す ることを特徴とする鋼板にある。 本発明の鋼は少なくとも０．２％のケイ素を合金元素としてに含むことがで きる。 本発明は以下の説明からより良く理解できよう。しかし、本発明が下記の記 載に限定されるものではない。 本発明で使用するメッキプラントは、制御された雰囲気中で鋼のストリップ をアニーリングする手段と、この手段の下流に配置されて鋼板をメッキ浴中に熱 浸漬する手段と、雰囲気を制御する手段とを有する。 アニーリング手段は温度の異なる複数の帯域に分けることができる。特に、鋼 がメッキ浴に入る前に冷却帯を設けることができる。この冷却帯の雰囲気はメッ キ浴表面上側の雰囲気と連通させることができる。各帯の雰囲気を制御する。 鋼板アニーリング手段、鋼板熱浸漬手段および雰囲気制御手段はそれ自体公知 である。雰囲気制御手段はそれ自体公知な方法でアンモニアをアニーリング帯に 導入し、アニーリング雰囲気のアンモニア含有率を０．０５〜１％に制御するよ うになっている。 本発明の好ましい実施例では、鋼板がアニーリング手段に入る位置の近くで、 アニーリング雰囲気にアンモニアを導入する。 メッキ装置のこの特別な構成はアニーリング雰囲気にガスを供給する従来の設 計とは逆である。すなわち、従来の設計では基本的に鋼板がアニーリング手段か ら出る位置からガス、特に窒素や水素を導入するので、ガスはアニーリング手段 内を鋼板と逆方向に流れる。 以下、本発明のメッキ方法を記載する。 本発明方法は酸化し易い合金元素を含む鋼板に適用することができる。 本発明方法は特にケイ素鋼、特に０．２％以上のケイ素を含む鋼板に適用する ことができる。 本発明方法ではケイ素鋼の鋼板を上記プラントで下記のようにしてメッキする 。すなわち、メッキされるケイ素鋼を公知な方法、例えば裸の鋼板を火炎中を通 して、被覆すべき表面を脱脂する。次に、鋼を望ましく再結晶し、必要な場合に は洗浄後の鋼板の表面に存在する酸化鉄を還元できるようなそれ自体公知の温度 、時間およびアニーリング雰囲気組成下で鋼板をアニーリング手段でアニーリン グする。 本発明では、アニーリング雰囲気組成に関する上記条件に加えて、雰囲気のア ンモニア含有率を０．００５％〜１％にするという条件が存在する。これは上記 雰囲気制御手段を用いて行うことができる。 アンモニア含有率は０．０２〜０．５％に維持するのが好ましい。 アニーリング時間すなわちアニーリング手段に鋼板を通す時間は３分以下にす るのが好ましい。 アニーリング温度は一般に５００℃〜９００℃にする。 必要な場合には、メッキ浴に鋼板を浸漬する前にアニーリング手段の１つの帯 域内で冷却操作をさらに行うことができる。 アンモニア含有雰囲気中で鋼板をアニーリング（必要に応じてさらに鋼板冷却 操作）をした後に、アニーリング済みの鋼板を実際にメッキする方法自体は公知 である。例えば、メッキ浴中に鋼板を熱浸漬し、浴から鋼板を取り出し、鋼板上 の随伴メッキ溶液を除去して所望のメッキ被膜の厚さを得た後、鋼板を冷却する 。 本発明では、アンモニア含有率が極めて低い（１％以下）アニーリング雰囲気 中でも、酸化し易い合金元素、特に０．２％以上のケイ素を含む鋼のメッキ浴中 での湿潤性を改良するという効果が得られる。 しかも、この効果は従来のメッキ鋼板の製造方法に追加の操作を必要とせず、 また、使用する鋼の機械的および／または電気的特性を低下させずに得られる。 驚くべきことに、この効果はアニーリング時間すなわち鋼板をアンモニアに曝 す時間が３分以下でも得られる。 本発明方法で得られた鋼板はアニーリング後の鋼板の表面または鋼／メッキ層 界面に固溶体の窒素を含む鋼からなる中間層および／または窒化物からなる中間 層を有する。 この中間層の厚さは１ｇ／ｍ2以下にするのが好ましい。 この薄い中間層は鋼の機械的および電気的特性を維持する役割をする。 本発明によって、初期機械的および／または電気的特性を維持したまま、耐腐 食性およびケイ素鋼のメッキ鋼板の表面外観を改良することができる。 本発明の上記の好ましいメッキ装置を使用する実施例では、鋼板がアニーリン グ手段に入る位置の近くで雰囲気中にアンモニアを導入することによって鋼の湿 潤性がさらに向上する。 本発明はケイ素以外の酸化し易い合金元素、特にチタン、マンガン、クロムお よびアルミニウムを有する鋼にも有利に適用することができる。 以下、本発明の実施例を説明する。比較例1 この比較例は本発明が解決しようとする問題を説明するために示す。 メッキされる試験片は０．３％のケイ素を含む鋼板である。メッキの前に１５％ の水素を含み、残部は窒素と不可避不純物とである還元性雰囲気中で試験片をア ニーリングする。メッキ方法の他の条件は約１４０ｇ／ｍ2の亜鉛膜を得るため の公知の条件である。 この比較例ではメッキ浴中での試験片の湿潤性に問題が見られる。これは被膜 の接着性および均質性、従って被膜の耐腐食性にとって有害である。実施例1 この実施例は本発明のメッキ方法を説明するためのものである。 比較例１と同じ種類の試験片に対して比較例１と同じ操作を行うが、本発明に従 ってアニーリング雰囲気は０．０３％のアンモニアを含む。 メッキ浴中での試験片の湿潤性に全く問題は見られず、亜鉛被膜は有効に試験 片を防食することができた。すなわち、アニーリング雰囲気中の極めて低いアン モニア含有率によって比較例１で直面する湿潤性の問題を解決する。しかし、メ ッキ鋼板を製造する方法に追加の操作を追加する必要がない。実施例2 この試験の目的は本発明でメッキ前のアニーリング雰囲気中に低い含有率でア ンモニアを存在させることによって“ＨＳ綱”すなわち高力鋼と一般によばれる ケイ素鋼板の機械的特性が事実上変化しないことを説明することにある。 アンモニア含有率のみを変えた雰囲気中でアニーリングしてからメッキした鋼 板の試験片の機械的特性を測定した。このアンモニア含有率（「ＮＨ3含有率」 ）を除いてメッキ条件は実施例１と同じにした。 使用した鋼のグレードはソラック（SOLLAC）社“SOLDUR 490”に相当し、０． ２〜０．３％のケイ素を含む。 実施例１と同様に、湿潤性は全く問題が見られない（少なくともアニーリング 雰囲気がアンモニアを極めて低い含有率で含む場合でも）。 機械的特性を評価するために０．２％の降伏応力いわゆるＲｐ0.2と引張強 度いわゆるＲｍを従来方法で測定した。測定単位はメガパスカル（ＭＰａ）。得 られた結果は下表の通り 本発明では、アニーリング雰囲気中のアンモニア含有率が１％または１％を大 幅に下回る値にとどまる限り、機械的特性に大きな変化は見られない。 アニーリング雰囲気中のアンモニア含有率が１％を越えた時すなわち従来技術 で既に記載の条件にした場合は、機械特性はかなり低下する。比較例２ この比較例は、英国特許GB 1,396,419号と同様に、本発明の濃度より高濃度の アンモニアを含む雰囲気中で鋼をアニーリングし、メッキ処理した場合の欠点を 示すためのものである。 この比較例の別の目的は、高濃度の酸化し易い合金元素を含む鋼以外の鋼にメ ッキ処理を施した時の欠点を示すことにある。この処理では本発明と同様に低濃 度のアンモニアを含む雰囲気中で鋼をアニーリングする。 実施例２と同じ操作を行うが、“ＩＦＴｉ”、すなわち“Interstitial free ”（格子間型元素を有しない）とよばれる、２５０ｐｐｍ以下のケイ素を含む鋼 の試験片を用いた。この“ＩＦＴｉ”鋼は公知方法で液体鋼の製造中にチタンを 導入して得られる。チタンは液体鋼に含まれる炭素を析出して隙間をふさがない ようにするためのものである。 得られた機械特性の結果は下表の通り アンモニア中でのアニーリングが鋼板の機械的特性をかなり大きく変えること が分かる。 この結果は、機械特性を制御（初期レベルに維持）するのが望ましい鋼をメッ キする目的ではメッキ業者にアンモニア中でのアニーリングを思いとどまらせる のに十分であろう。 上記英国特許GB 1,396,419号に記載の鋼線の窒化方法は高濃度のアンモニアを 含む（＞１５％）還元雰囲気アニーリング処理を含む。これは被覆すべき表面を 窒化する効果がある。この特殊なメッキ処理は鋼線（鋼板ではない）およびリム ド鋼とよばれる鋼に対して行われる。リムド鋼は「キルド鋼」ではなく、従って 酸化し易い元素を含まないのでメッキ浴中での湿潤性に問題がない。この特許で メッキ前の鋼表面を窒化して得られる望ましい効果はメッキ層の接着力が高まる ことで、これは鋼線にとって特に重要な問題である。この特許に記載の手段すな わち高濃度のアンモニアをアニーリング雰囲気中に導入することは本発明の分野 以外の鋼に適用される。この型の鋼は湿潤性に問題がなく、この手段は湿潤性に 特別な効果はない。 さらに、この特許に記載された手段を酸化し易い合金元素、例えばＩＦＳ鋼（ ＩＦＳ＝“Interstitial Free Steel）を含まない鋼に適用した場合には、上記 の表（ＮＨ3含有率：２％、５％および１０％）に示されるように、機械的特性 が低下するという欠点がある。従って、メッキ業者は機械特性の低下を恐れて、 高力鋼の湿潤性の問題を解決するためにこの窒化方法を適用しようとは思わない だろう。 本発明の低濃度のアンモニア（ＮＨ3含有率０．５％および１％）を用いて得 られた結果が示すように、機械特性の変化に関する比較例２の結果は、本発明の 実施例２の結果と反対である。低濃度のアンモニアを含む実施例２では機械特性 は良く維持されるが、低濃度のアンモニアを含む比較例２ではかなり低下する。Description: TECHNICAL FIELD The present invention relates to a method for plating a steel sheet containing an easily oxidizable alloy element (additional element), particularly silicon. In steel plate applications, particularly in the electric field and applications requiring mechanical strength, steel elements containing easily oxidizable alloy elements, particularly silicon, are used. In these applications, high corrosion resistance is also required. However, it has heretofore been difficult to obtain sufficient corrosion resistance by plating. This problem arises from the fact that the steel sheet is not sufficiently wetted in the plating bath (poor wetting) due to the presence of easily oxidizable alloy elements, particularly silicon, contained in the steel sheet, and as a result, the properties of the coating, particularly the homogeneity, are reduced. . In the case of silicon steel, when the silicon content reaches about 0.2%, there is a problem in wettability, and a lower content may cause a problem. A steel having a low content of easily oxidizable alloy elements can be plated by a conventional method, and the steel sheet to be coated is cleaned, annealed in a non-oxidizing or reducing atmosphere, and then the steel sheet is immersed in a plating bath. It can be coated in a manner. A problem arises when plating steel with a high content of alloying elements in order to obtain a plated steel sheet which has both high corrosion resistance and high mechanical strength or special electrical properties. On the other hand, there is known a method of plating steel containing a high concentration of easily oxidizable alloy elements, for example, 0.3 to 3% of silicon. In this method, the steel sheet is subjected to additional treatment and then immersed in a plating bath. For example, Japanese Patent No. JP-51-40711 describes an additional electrochemical treatment in which a steel sheet is immersed in a treatment solution to provide a thin composite layer of iron nitride (FeN). The composite layer can be formed on a steel sheet having a thickness of less than 1 g / m 2 and containing less than 3% of silicon, thereby greatly improving the wettability of the steel sheet in the plating bath. However, the solution described in this patent requires additional operations in the production of plated steel sheets and is economically disadvantageous. Also, if the steel sheet is excessively nitrided at the steel sheet / plated layer interface and / or if an excessively thick iron nitride layer corresponding to a thickness of 1 g / m 2 or more is formed, the mechanical or electrical There is a risk that the characteristics will be degraded. As already mentioned, steels containing oxidizable alloy elements, especially silicon, have been used to take advantage of special mechanical and / or electrical properties. It is an object of the present invention to provide an economical method for plating steel sheets containing a high content of easily oxidizable alloy elements, especially silicon, without deteriorating the mechanical and / or electrical properties of the steel. An object of the present invention is to provide a method of annealing a steel sheet in a non-oxidizing annealing atmosphere and then immersing the steel sheet in a plating bath, wherein the annealing atmosphere contains 0.005% to 1% ammonia. is there. The present invention can be applied to a steel sheet containing an alloy element which is easily oxidized in such a ratio as to prevent wettability of the steel sheet in a plating bath necessary for obtaining a uniform plating film. The invention applies in particular to steel sheets containing 0.2% or more of silicon. The invention can further have the following properties a) and / or b): a) The annealing atmosphere comprises 0.02% to 0.5% ammonia. b) The residence time of the steel sheet in the annealing atmosphere is 3 minutes or less. Another object of the present invention is a means for annealing a steel sheet in a controlled atmosphere, a means for hot-immersing an annealed steel sheet provided downstream of the means in a plating bath, and a means for controlling the atmosphere. 4. A plating apparatus for a steel sheet for performing the method according to any one of claims 1 to 3, wherein ammonia is introduced into the atmosphere near a position where the steel sheet enters the annealing means; Wherein the ammonia concentration is maintained at 0.005 to 1%. Still another object of the present invention is to provide a steel plate containing an easily oxidizable alloy element, particularly silicon, plated by the method of the present invention, having a boundary layer containing solid solution nitrogen between the steel and the plating layer. in the steel sheet, characterized in that corresponding to at least 1 g Saga boundary area 1 m 2 per. The steel of the present invention may contain at least 0.2% of silicon as an alloying element. The invention will be better understood from the following description. However, the present invention is not limited to the following description. The plating plant used in the present invention comprises means for annealing a strip of steel in a controlled atmosphere, means for downstream immersing the means for hot immersing the steel sheet in a plating bath, and means for controlling the atmosphere. Having. The annealing means can be divided into a plurality of zones with different temperatures. In particular, a cooling zone can be provided before the steel enters the plating bath. The atmosphere in the cooling zone can be communicated with the atmosphere above the plating bath surface. Control the atmosphere in each zone. The steel sheet annealing means, the steel sheet hot dipping means and the atmosphere control means are known per se. The atmosphere control means introduces ammonia into the annealing zone by a method known per se, and controls the ammonia content of the annealing atmosphere to 0.05 to 1%. In a preferred embodiment of the invention, ammonia is introduced into the annealing atmosphere near the point where the steel sheet enters the annealing means. This particular configuration of the plating apparatus is contrary to conventional designs that supply gas to the annealing atmosphere. That is, in the conventional design, gas, particularly nitrogen or hydrogen, is introduced from the position where the steel sheet exits the annealing means, so that the gas flows in the annealing means in the opposite direction to the steel sheet. Hereinafter, the plating method of the present invention will be described. The method of the present invention can be applied to a steel sheet containing an alloy element that is easily oxidized. The method according to the invention can be applied in particular to silicon steel, in particular to steel plates containing 0.2% or more of silicon. In the method of the present invention, a silicon steel plate is plated in the above-mentioned plant as follows. That is, the surface to be coated is degreased by passing the silicon steel to be plated through a known method, for example, passing a bare steel plate through a flame. Then, the steel is desirably recrystallized and, if necessary, the steel sheet is annealed by means of annealing at a temperature, time and annealing atmosphere composition known per se such that the iron oxide present on the surface of the steel sheet after cleaning can be reduced. I do. In the present invention, there is a condition that the ammonia content of the atmosphere is set to 0.005% to 1% in addition to the above-described conditions regarding the annealing atmosphere composition. This can be performed using the above atmosphere control means. The ammonia content is preferably maintained between 0.02 and 0.5%. The annealing time, that is, the time for passing the steel sheet through the annealing means is preferably 3 minutes or less. The annealing temperature is generally between 500C and 900C. If necessary, a further cooling operation can be performed in one zone of the annealing means before immersing the steel sheet in the plating bath. The method itself of annealing the steel sheet in an ammonia-containing atmosphere (further cooling operation of the steel sheet as necessary) and then actually plating the annealed steel sheet is known. For example, the steel sheet is hot immersed in a plating bath, the steel sheet is taken out of the bath, and the accompanying plating solution on the steel sheet is removed to obtain a desired plating film thickness, and then the steel sheet is cooled. In the present invention, even in an annealing atmosphere having an extremely low ammonia content (1% or less), the effect of improving the wettability of a steel containing an easily oxidizable alloy element, particularly 0.2% or more of silicon, in a plating bath is obtained. can get. Moreover, this effect can be obtained without requiring any additional operation in the conventional method for producing a plated steel sheet and without deteriorating the mechanical and / or electrical properties of the steel used. Surprisingly, this effect is obtained even with an annealing time, ie a time of exposing the steel sheet to ammonia of less than 3 minutes. The steel sheet obtained by the method of the present invention has an intermediate layer made of steel containing solid solution nitrogen and / or an intermediate layer made of nitride on the surface of the steel sheet after annealing or at the interface between the steel and the plating layer. The thickness of the intermediate layer is preferably 1 g / m 2 or less. This thin interlayer serves to maintain the mechanical and electrical properties of the steel. According to the present invention, it is possible to improve the corrosion resistance and the surface appearance of a silicon steel plated steel sheet while maintaining the initial mechanical and / or electrical properties. In an embodiment using the above preferred plating apparatus of the present invention, the wettability of the steel is further improved by introducing ammonia into the atmosphere near the point where the steel sheet enters the annealing means. The present invention can be advantageously applied to steels containing easily oxidizable alloy elements other than silicon, particularly titanium, manganese, chromium and aluminum. Hereinafter, embodiments of the present invention will be described. Comparative Example 1 This comparative example is shown to explain the problem to be solved by the present invention. The test specimen to be plated is a steel sheet containing 0.3% silicon. Prior to plating, the specimens are annealed in a reducing atmosphere containing 15% hydrogen and the balance nitrogen and unavoidable impurities. Other conditions of the plating method are known conditions for obtaining a zinc film of about 140 g / m 2 . In this comparative example, there is a problem in wettability of the test piece in the plating bath. This is detrimental to the adhesion and homogeneity of the coating and thus the corrosion resistance of the coating. Example 1 This example illustrates the plating method of the present invention. The same operation as in Comparative Example 1 is performed on a test piece of the same type as in Comparative Example 1, but according to the invention the annealing atmosphere contains 0.03% ammonia. No problem was observed in the wettability of the test piece in the plating bath, and the zinc coating was able to effectively protect the test piece from corrosion. That is, the problem of wettability encountered in Comparative Example 1 is solved by the extremely low ammonia content in the annealing atmosphere. However, there is no need to add an additional operation to the method of manufacturing a plated steel sheet. Example 2 The purpose of this test is that the present invention does not substantially change the mechanical properties of the "HS class" or silicon steel plate commonly referred to as high strength steel by the presence of a low content of ammonia in the annealing atmosphere before plating. Is to explain. The mechanical properties of the test pieces of the plated steel sheet after annealing in an atmosphere in which only the ammonia content was changed were measured. Except for the ammonia content (“NH 3 content”), the plating conditions were the same as in Example 1. The grade of steel used corresponds to "SOLDUR 490" manufactured by SOLAC, Contains 2 to 0.3% silicon. As in Example 1, there is no problem with wettability (at least even if the annealing atmosphere contains ammonia at a very low content). To evaluate the mechanical properties, a 0.2% yield stress, so-called Rp 0.2, and a tensile strength, so-called Rm, were measured by conventional methods. The unit of measurement is megapascal (MPa). The results obtained are shown in the table below In the present invention, as long as the ammonia content in the annealing atmosphere remains at 1% or a value significantly lower than 1%, no significant change is observed in the mechanical properties. When the ammonia content in the annealing atmosphere exceeds 1%, ie under the conditions already described in the prior art, the mechanical properties are considerably reduced. COMPARATIVE EXAMPLE 2 This comparative example is intended to show the drawbacks in the case where the steel is annealed and plated in an atmosphere containing a higher concentration of ammonia than the concentration of the present invention, as in GB 1,396,419. Another object of this comparative example is to show the disadvantages of plating steel other than steel containing a high concentration of easily oxidizable alloy elements. In this treatment, as in the present invention, the steel is annealed in an atmosphere containing a low concentration of ammonia. The same operation as in Example 2 was performed, except that a test piece of steel containing 250 ppm or less of silicon called "IFTi", that is, "Interstitial free" (having no interstitial element) was used. This "IFTi" steel is obtained in a known manner by introducing titanium during the production of liquid steel. Titanium is for precipitating carbon contained in the liquid steel so as not to block the gap. The results of the obtained mechanical properties are shown in the table below. It can be seen that annealing in ammonia significantly changes the mechanical properties of the steel sheet. This result would be sufficient to discourage the plating company from annealing in ammonia for the purpose of plating steel where it is desirable to control (maintain initial levels) mechanical properties. The method of nitriding steel wire described in GB 1,396,419 involves a reducing atmosphere annealing treatment containing a high concentration of ammonia (> 15%). This has the effect of nitriding the surface to be coated. This special plating process is performed on steel wires (not steel plates) and steels called rimmed steels. The rimmed steel is not a "killed steel" and therefore does not contain any easily oxidizable elements, so that there is no problem in wettability in the plating bath. The desired effect obtained by nitriding the steel surface prior to plating in this patent is to increase the adhesion of the plating layer, which is a particularly important issue for steel wires. The measures described in this patent, i.e. introducing high concentrations of ammonia into the annealing atmosphere, apply to steels outside the field of the invention. This type of steel has no problem with wettability, and this measure has no special effect on wettability. Further, when the means described in this patent is applied to a steel that does not contain an easily oxidizable alloy element, for example, IFS steel (IFS = “Interstitial Free Steel”), the above table (NH 3 content: 2%, (5% and 10%), there is the disadvantage that the mechanical properties are reduced.Therefore, plating companies are afraid of the reduced mechanical properties, and this nitriding method is used to solve the problem of wettability of high strength steel. will not want trying to apply. this as the results obtained with a low concentration of ammonia (NH 3 content of 0.5% and 1%) of the invention, comparison of changes in the mechanical properties example 2 Are opposite to the results of Example 2 of the present invention, while the mechanical properties are well maintained in Example 2 containing a low concentration of ammonia, but are considerably reduced in Comparative Example 2 containing a low concentration of ammonia.
Claims (1)
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9514835A FR2742449B1 (en) | 1995-12-14 | 1995-12-14 | METHOD FOR GALVANIZING A STEEL SHEET CONTAINING OXIDIZABLE ADDITION ELEMENTS |
| FR95/14835 | 1995-12-14 | ||
| PCT/FR1996/001978 WO1997021846A1 (en) | 1995-12-14 | 1996-12-11 | Method for galvanising a steel sheet containing oxidisable alloying elements |
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| Publication Number | Publication Date |
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| JP2000501787A true JP2000501787A (en) | 2000-02-15 |
| JP2000501787A5 JP2000501787A5 (en) | 2004-10-07 |
| JP4247320B2 JP4247320B2 (en) | 2009-04-02 |
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| JP52180397A Expired - Lifetime JP4247320B2 (en) | 1995-12-14 | 1996-12-11 | Method of galvanizing steel sheets containing alloy elements that are easily oxidized |
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| EP (1) | EP0870069B1 (en) |
| JP (1) | JP4247320B2 (en) |
| KR (1) | KR100441807B1 (en) |
| AT (1) | ATE203284T1 (en) |
| CA (1) | CA2238831C (en) |
| DE (1) | DE69614000T2 (en) |
| ES (1) | ES2158370T3 (en) |
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| WO (1) | WO1997021846A1 (en) |
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|---|---|---|---|---|
| DE19758140A1 (en) * | 1997-12-19 | 1999-07-08 | Mannesmann Ag | Process for producing composite metal products |
| TWI452170B (en) * | 2002-03-01 | 2014-09-11 | Jfe Steel Corp | Hot-dip galvanizing steel sheet and method for manufacturing a coated steel sheet |
| DE10258531B3 (en) * | 2002-12-14 | 2004-04-08 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Production of a steel with a corrosion protection coating used in the production of an automobile chassis comprises annealing the steel, treating the surface of the steel using high energy, and coating the surface of the steel |
| EP2009128A1 (en) | 2007-06-29 | 2008-12-31 | ArcelorMittal France | Galvanized or galvannealed silicon steel |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1552041A (en) * | 1924-05-09 | 1925-09-01 | Frederick M Crapo | Protected metal and process of making it |
| GB424373A (en) * | 1934-01-24 | 1935-02-20 | Rylands Brothers Ltd | Improvements in or relating to methods and apparatus for galvanizing or zinc coating iron or steel articles |
| GB1396419A (en) * | 1972-08-17 | 1975-06-04 | Gkn South Wales Ltd | Hot-dip zinc galvanizing of ferrous articles |
| JPS5974236A (en) * | 1983-09-05 | 1984-04-26 | Sumitomo Metal Ind Ltd | Production of galvanized steel sheet for deep drawing having excellent formability |
| FR2661426B1 (en) * | 1990-04-27 | 1992-08-07 | Maubeuge Fer | PROCESS FOR GALVANIZING WITH QUENCH AND CONTINUOUS. |
-
1995
- 1995-12-14 FR FR9514835A patent/FR2742449B1/en not_active Expired - Fee Related
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1996
- 1996-12-11 WO PCT/FR1996/001978 patent/WO1997021846A1/en active IP Right Grant
- 1996-12-11 KR KR10-1998-0704153A patent/KR100441807B1/en not_active IP Right Cessation
- 1996-12-11 EP EP96942384A patent/EP0870069B1/en not_active Expired - Lifetime
- 1996-12-11 JP JP52180397A patent/JP4247320B2/en not_active Expired - Lifetime
- 1996-12-11 CA CA002238831A patent/CA2238831C/en not_active Expired - Lifetime
- 1996-12-11 ES ES96942384T patent/ES2158370T3/en not_active Expired - Lifetime
- 1996-12-11 AT AT96942384T patent/ATE203284T1/en active
- 1996-12-11 DE DE69614000T patent/DE69614000T2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| KR100441807B1 (en) | 2004-11-10 |
| ES2158370T3 (en) | 2001-09-01 |
| JP4247320B2 (en) | 2009-04-02 |
| WO1997021846A1 (en) | 1997-06-19 |
| ATE203284T1 (en) | 2001-08-15 |
| DE69614000D1 (en) | 2001-08-23 |
| FR2742449A1 (en) | 1997-06-20 |
| KR19990071869A (en) | 1999-09-27 |
| CA2238831A1 (en) | 1997-06-19 |
| CA2238831C (en) | 2004-11-30 |
| DE69614000T2 (en) | 2001-11-29 |
| EP0870069B1 (en) | 2001-07-18 |
| FR2742449B1 (en) | 1998-01-09 |
| EP0870069A1 (en) | 1998-10-14 |
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