JP2530939B2 - Method for manufacturing high-strength hot-dip galvanized steel sheet containing high Si - Google Patents
Method for manufacturing high-strength hot-dip galvanized steel sheet containing high SiInfo
- Publication number
- JP2530939B2 JP2530939B2 JP2329549A JP32954990A JP2530939B2 JP 2530939 B2 JP2530939 B2 JP 2530939B2 JP 2329549 A JP2329549 A JP 2329549A JP 32954990 A JP32954990 A JP 32954990A JP 2530939 B2 JP2530939 B2 JP 2530939B2
- Authority
- JP
- Japan
- Prior art keywords
- oxide film
- film thickness
- iron oxide
- reduction
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、高Si含有鋼の高張力溶融亜鉛めっき鋼板の
製造方法に関するもので、特に、鋼中Si濃度が0.3％以
上の高Si含有鋼板に対して亜鉛めっき外観の均一性、密
着性等を確保するための焼鈍条件を制御する方法にあ
る。TECHNICAL FIELD The present invention relates to a method for producing a high-strength hot-dip galvanized steel sheet for a high Si-containing steel, and particularly to a high Si-containing steel having a Si concentration of 0.3% or more. It is a method of controlling the annealing conditions for ensuring the uniformity of the galvanized appearance and the adhesion to the steel sheet.
（従来の技術） 従来、建材等での構造用部材としての多様される裸鋼
材の高寿命化或いは意匠向上にあたっては一定の成形加
工後に、めっきや塗装と言った何らかの後処理が、需要
家でなされていたが工程省略による使用鋼材の低コスト
化から供給鋼材の表面処理化が強く要求される状況にあ
る。このなかで、最近では、特に、高張力鋼板の表面処
理化要求が高まりつつある。この高張力鋼板の防錆力向
上を主目的とした表面処理方法としては、生産性の点か
ら容易に厚めっき化が可能なゼンジマー式溶融亜鉛めっ
き法がある。(Prior art) Conventionally, in order to extend the life or improve the design of bare steel materials, which are variously used as structural members in building materials, etc., some post-processing such as plating and painting is required by the customer after a certain forming process. Although it has been done, the surface treatment of the supplied steel material is strongly required due to the cost reduction of the steel material used by omitting the process. Of these, recently, the demand for surface treatment of high-strength steel sheets is increasing. As a surface treatment method whose main purpose is to improve the rust-preventive power of this high-strength steel sheet, there is a Zenzimer hot-dip galvanizing method which can easily achieve thick plating in terms of productivity.
このゼンジマー式溶融亜鉛めっき法を用いて、酸素を
含む酸化炉中で鋼板表面の圧延油を除去し、適度な酸化
膜を形成せしめた後、水素を含む雰囲気中で、還元焼鈍
後、炉内で板温を調節し、めっきする方法が、既に特開
昭55−122865号公報で知られている。すなわち、酸素を
含まない無酸化炉方式では、鋼表面の油を除去すること
ができるが、酸化性雰囲気が弱いため、酸化され易いS
i,Mn,Alが表面に拡散酸化されるため、これらの酸化物
が鋼表面を形成する。しかも、これらの酸化物は、還元
炉では、還元されず、めっきの濡れ不良、めっき密着不
良の原因となる。そのために鋼板の表面に酸化膜の厚み
400〜10000Åになるように酸化した後、水素を含む雰囲
気で焼鈍し、溶融めっきするというものである。Using this Sendzimer hot dip galvanizing method, after removing the rolling oil on the surface of the steel sheet in an oxidation furnace containing oxygen to form an appropriate oxide film, after reducing annealing in an atmosphere containing hydrogen, the inside of the furnace A method for controlling the plate temperature and plating is already known in JP-A-55-122865. That is, in the non-oxidation furnace system containing no oxygen, oil on the steel surface can be removed, but since the oxidizing atmosphere is weak, S
These oxides form the steel surface because i, Mn, and Al are diffusion-oxidized to the surface. Moreover, these oxides are not reduced in the reduction furnace and cause poor wetting of the plating and poor adhesion of the plating. Therefore, the thickness of the oxide film on the surface of the steel sheet
After being oxidized to 400 to 10000Å, it is annealed in an atmosphere containing hydrogen and hot-dipped.
（発明が解決しようとする課題） しかしながら、従来技術は上記のように無酸化炉の空
気比を高くして加熱し、Fe酸化膜を生成した後、還元加
熱すると、良好なめっき性が得られるという知見のみで
あって、実際の操業ラインにおけるラインスピード、炉
温、ヒートサイクル等が常に変化する連続ラインにおい
ては、一定の高空気比においても、めっき性は安定せ
ず、実用化には問題点があった。そこで、本発明は、高
生産性のラインにあって、従来法とは異なり、連続ライ
ンに制御システムを採用することにより、不めっきを伴
うことなく、安定した品位で均一外観の優れためっき密
着性の良好な高Si含有高張力溶融亜鉛めっき鋼板を得る
方法を提供することにある。(Problems to be Solved by the Invention) However, in the related art, when the air ratio of the non-oxidizing furnace is increased and heated to generate the Fe oxide film, and then reduction heating is performed, good plating property is obtained. In a continuous line where the line speed, furnace temperature, heat cycle, etc. in the actual operation line are constantly changing, the plating property is not stable even at a constant high air ratio, and there is a problem in practical application. There was a point. Therefore, the present invention is a highly productive line, and unlike the conventional method, by adopting a control system in a continuous line, plating adhesion with stable quality and excellent uniform appearance is achieved without non-plating. It is intended to provide a method for obtaining a high-Si high-strength hot-dip galvanized steel sheet having good properties.
（課題を解決するための手段） 上述した問題点を解決し、その目的を達成するため
に、本発明の要旨とするところは、 （１）鋼中Si濃度0.3％以上の高張力溶融亜鉛めっき鋼
板の製造方法において、焼鈍炉の酸化帯での生成した鉄
酸化膜厚を酸化膜厚計にて実測し、一方還元帯での鉄酸
化膜還元能力をヒートサイクル、ラインスピード、還元
帯水素濃度を用いて計算し、該酸化帯での実測した生成
した鉄酸化膜厚に基づいて、 鉄酸化膜厚＋ａ（Å）≦還元能力（Å）≦鉄酸化膜厚＋
ｂ≦（鉄酸化膜厚）２（Å） 鉄酸化膜厚≦1000Å a:鉄酸化膜余裕代 b:鋼中Si量により決まる定数 なるように焼鈍条件を制御することを特徴とする高Si含
有高張力溶融亜鉛めっき鋼板の製造方法。(Means for Solving the Problem) In order to solve the above-mentioned problems and achieve the object, the gist of the present invention is: (1) High-strength hot-dip galvanizing with Si concentration in steel of 0.3% or more In the steel sheet manufacturing method, the iron oxide film thickness produced in the oxidation zone of the annealing furnace was measured by an oxide film thickness meter, while the iron oxide film reduction capacity in the reduction zone was measured by heat cycle, line speed, hydrogen concentration in the reduction zone. Calculated based on the measured iron oxide film thickness in the oxidation zone, iron oxide film thickness + a (Å) ≦ reduction capacity (Å) ≦ iron oxide film thickness +
b ≤ (iron oxide film thickness) 2 (Å) iron oxide film thickness ≤ 1000 Å a: iron oxide film allowance b: high Si content characterized by controlling annealing conditions to be a constant determined by the amount of Si in steel Method for manufacturing high-strength hot-dip galvanized steel sheet.
（２）鋼中Si濃度0.3％以上の高張力溶融亜鉛めっき鋼
板の製造方法において、焼鈍炉の酸化帯での生成した鉄
酸化膜厚を酸化膜厚計にて実測し、一方還元帯での鉄酸
化膜還元能力をヒートサイクル、ラインスピード、還元
帯水素濃度を用いて計算し、該酸化帯での実測した生成
した鉄酸化膜厚に基づいて、 入側鉄酸化膜厚＋ａ（Å）≦還元能力（Å）≦入側鉄酸
化膜厚＋ｂ×（入側鉄酸化膜厚）２（Å） 入側鉄酸化膜厚≦1000Å a:鉄酸化膜余裕代 b:鋼中Si量により決まる定数 になるように焼鈍条件を制御すると共に、めっき前の生
成した鉄酸化膜厚を酸化膜厚計にて実測し、還元帯出側
での鉄酸化膜厚ｄ≦50Åに保持するための焼鈍条件をフ
ィードバック制御することを特徴とする高Si含有高張力
溶融亜鉛めっき鋼板の製造方法にある。(2) In the manufacturing method of high-strength hot-dip galvanized steel sheet with Si concentration of 0.3% or more in the steel, the iron oxide film thickness produced in the oxidation zone of the annealing furnace was measured by an oxide film thickness meter, while in the reduction zone The iron oxide film reducing ability was calculated using the heat cycle, line speed, and hydrogen concentration in the reduction zone, and based on the measured iron oxide film thickness in the oxidation zone, the iron oxide film thickness on the inlet side + a (Å) ≤ Reduction capacity (Å) ≤ iron oxide film thickness on incoming side + b × (iron oxide film thickness on incoming side) 2 (Å) Iron oxide film thickness on incoming side ≤ 1000 Å a: allowance for iron oxide film b: constant determined by the amount of Si in steel The annealing condition is controlled so that the iron oxide film thickness before plating is measured by an oxide film thickness meter, and the annealing condition for maintaining the iron oxide film thickness d ≦ 50Å on the reduction zone side is obtained. A method for producing a high-Si high-strength hot-dip galvanized steel sheet characterized by feedback control.
以下本発明について詳細に説明する。本発明におい
て、鋼中にSi濃度が0.3％以上の高Si含有鋼の場合に
は、一般には難めっき材の呼ばれ、鋼中のSi,Mn,Al,Pな
どが、鋼板表面の加熱によって、酸化物として鋼板表層
に拡散されるため、これら酸化物が濃化し、鋼表面を形
成する。そのため、これらの酸化物は、還元炉中でも還
元されず、めっきの濡れ性を阻害し、めっき密着性を悪
くする。従ってこれら難めっき材を対象とした鋼材への
溶融亜鉛めっきを高生産性のラインにおいて、不めっき
のない、しかも均一外観の優れためっきを可能としたこ
とにある。そのための焼鈍条件として、第１は鉄酸化膜
厚＋ａ≦還元能力（Å）であること。すなわち、この条
件はめっき浴に浸漬する際に、めっき性を阻害するFe酸
化膜が残存していないことを示すものである。ここで、
鉄酸化膜厚は、酸化帯出側での生成した鉄酸化膜厚を酸
化膜計で実測した値であり、定数ａは、鋼板の幅方向で
のFe酸化膜のばらつきの余裕代で、通常は100Å程度の
値を入れる必要がある。また還元能力とは、鉄酸化膜厚
が十分に多いときな還元帯全体で還元する能力を示し、
通常は1000Å程度である。従って鉄酸化膜厚＋ａが還元
能力より少なければ、めっき前には、鉄酸化膜はないの
で、良好なめっき密着性が得られる。更に還元能力
（Å）≦鉄酸化膜厚＋ｂ＋（鉄酸化膜厚）２（Å）なる
条件は、めっき浴に浸漬する際に、めっき密着性を阻害
するSi酸化膜が表面濃化していないことを示すものであ
る。定数ｂは、鋼中Si濃度、鋼板温度、ラインスピード
に依存する定数である。従って鋼中Siの表面濃度が起こ
らないことがめっき密着性不良、不めっきの発生を防止
する理由であり、そのための前提条件及び濃化現象につ
いて、第１に表層300ÅまでのSi濃化量を1.5mg/m2以下
に抑えれば、良好なめっき性が得られること。第２にSi
表面濃化は鉄酸化膜がなくなった時点から開始するこ
と。第３はSiの表面濃化は、鉄酸化膜が還元された後の
純鉄層を、Si原子が拡散する過程で律速となり、時間の
平方根に比例して、表面Si量は増加するものである。こ
れらの現象を発明者らは種々の実験の結果見出し、次の
関係を式で示すことができる。すなわち、Siの表面濃化
量は鋼中Si濃度Csiに比例し、鉄酸化膜厚Oxに反比例
し、時間の平方根 に比例する故、 ここで、Si濃化量：〔mg/m2〕 A:定数〔mg/m2・Å・sec−1/2〕 Csi:鋼中Si濃度〔％〕 Ox:鉄酸化膜厚〔Å〕 t:還元帯滞在時間〔sec〕 t1:還元帯に入ってから鉄酸化膜厚が還元されるまでの
時間〔sec〕 このSi濃化量が1.5mg/m2を超えると、表面全体がSiOX皮
膜で被われるので、良好なめっき密着性を得るための条
件は、 Si濃化量≦1.5mg/m2 ……（２） 両辺を２乗して A2・（Csi/OX）２・（ｔ−t1）≦2.25…（４）ここで還
元速度をVr〔Å/sec〕，還元能力をＲ〔Å〕とすると、
還元能力はｔ〔sec〕間での還元量であるから、 Ｒ＝Vr・ｔ ……（５） また、t1〔sec〕間でOx〔Å〕の酸化膜を還元するか
ら、 Ox＝Vr・t1 ……（６） これより、 ｔ＝R/Vr、t1＝Ox/Vr ……（７） この２式を（４）式に代入して A2・（Csi/OX）２・1/Vr・（Ｒ−Ox）≦2.25……｛８） これを整理して、 Ｒ≦Ox＋2.25・Vr/A・1/Csi2・Ox2 定数Ａと還元速度Vrは実験的に求められ、還元帯での鋼
板の平均温度である600℃では、 Ａ＝127〔mg/m2・Å・sec−1/2〕 Vr＝11.6〔Å/sec〕 よって、条件は Ｒ≦Ox＋1.6×103/Csi2Ox2 従って、Siの表面濃化によるめっき密着性不良を防止す
る条件は、 還元能力≦鉄酸化膜厚＋1.6×10-3/Csi2・（鉄酸化膜
厚）２すなわち、定数ｂは、1.6×10-3/Csi2で表すこと
ができる。The present invention will be described in detail below. In the present invention, in the case of high Si-containing steel having a Si concentration of 0.3% or more in the steel, it is generally called a difficult-to-plate material, Si, Mn, Al, P, etc. in the steel are heated by heating the steel plate surface. Since these are diffused as oxides in the surface layer of the steel sheet, these oxides are concentrated and form the steel surface. Therefore, these oxides are not reduced even in the reduction furnace, and hinder the wettability of the plating and deteriorate the plating adhesion. Therefore, it is intended to enable hot-dip galvanizing of steel for these difficult-to-plate materials in a highly productive line without plating and with excellent uniform appearance. As the annealing condition for that, the first is that the iron oxide film thickness + a ≦ reduction capacity (Å). That is, this condition indicates that, when immersed in the plating bath, no Fe oxide film that inhibits the plating property remains. here,
The iron oxide film thickness is a value obtained by actually measuring the iron oxide film thickness generated on the oxide zone side with an oxide film meter, and the constant a is a margin of variation in the Fe oxide film in the width direction of the steel sheet, and is usually It is necessary to enter a value of around 100Å. In addition, the reducing ability indicates the ability to reduce in the entire reduction zone when the iron oxide film thickness is sufficiently large,
It is usually about 1000Å. Therefore, if the iron oxide film thickness + a is less than the reducing ability, there is no iron oxide film before plating, and good plating adhesion can be obtained. Furthermore, the condition of reducing ability (Å) ≤ iron oxide film thickness + b + (iron oxide film thickness) 2 (Å) is that the surface of the Si oxide film that hinders the plating adhesion is not concentrated when immersed in the plating bath. Is shown. The constant b is a constant that depends on the Si concentration in steel, the steel plate temperature, and the line speed. Therefore, the fact that the surface concentration of Si in steel does not occur is the reason to prevent the occurrence of poor plating adhesion and non-plating. Regarding the preconditions and thickening phenomenon, firstly, the Si concentration up to 300 Å of the surface layer If it is kept below 1.5 mg / m 2 , good plating properties can be obtained. Secondly Si
Surface enrichment should start when the iron oxide film is gone. Thirdly, the surface concentration of Si is the rate-determining process in the process of diffusion of Si atoms in the pure iron layer after the reduction of the iron oxide film, and the amount of surface Si increases in proportion to the square root of time. is there. The inventors of the present invention can find out these phenomena as a result of various experiments, and can express the following relationships by equations. That is, the surface concentration of Si is proportional to the Si concentration Csi in steel, inversely proportional to the iron oxide film thickness Ox, and the square root of time. Is proportional to Here, Si concentrated amount: ## mg / m 2] A: constant [mg / m 2 · Å · sec -1/2 ] Csi: steel Si concentration [%] Ox: Iron oxide film thickness [Å] t : Retention time in the reduction zone [sec] t 1 : Time from entry into the reduction zone until the iron oxide film thickness is reduced [sec] If the Si concentration exceeds 1.5 mg / m 2 , the entire surface is covered with SiO 2. Since it is covered with the X film, the conditions for obtaining good plating adhesion are the Si concentration ≤1.5 mg / m 2 (2) Square both sides to A 2 · (Csi / O X ) 2 · (t−t 1 ) ≦ 2.25… (4) where the reduction rate is Vr [Å / sec] and the reduction capacity is R [Å] ,
The reduction capacity is the reduction amount during t [sec], so R = Vr · t (5) Also, since the oxide film of Ox [Å] is reduced during t 1 [sec], Ox = Vr・ T 1・ ・ ・ (6) From this, t = R / V r , t 1 ＝ Ox / Vr ・ ・ ・ (7) Substituting these two formulas into formula (4), A 2・ (Csi / O X ). 2・ 1 / Vr ・ (R−Ox) ≦ 2.25 …… {8) By rearranging this, R ≦ Ox ＋ 2.25 ・ Vr / A ・ 1 / Csi 2・ Ox 2 constant A and reduction rate Vr are experimental. At 600 ℃, which is the average temperature of the steel sheet in the reduction zone, A = 127 [mg / m 2 · Å · sec −1/2 ] Vr = 11.6 [Å / sec] Therefore, the condition is R ≦ Ox + 1 .6 × 10 3 / Csi 2 Ox 2 Therefore, the condition to prevent poor plating adhesion due to surface concentration of Si is: reduction capacity ≤ iron oxide film thickness + 1.6 × 10 -3 / Csi 2 · (iron oxide film Thickness) 2, that is, the constant b can be represented by 1.6 × 10 −3 / Csi 2 .
以上のことを模式的に説明したものが第１図に示す模
式図である。すなわち、第１図は酸化、還元バランスを
時間の変化として表したもので、鉄酸化膜厚は酸化帯に
おいて増加し、その後還元帯で、酸化膜は還元され、t1
後にFeO還元は完了し、引続きSi濃化が開始されｔ−t1
時間内でSiの濃化が進むと共に、還元能力の許容範囲ま
で還元が行われる状態を示している。また第２図は酸
化、還元バランスの軌跡を模式的に示したもので、酸化
・還元過程は亜鉛浴中に入る際、未だ酸化膜が残って
いるため、合金化特性は不良状態を示す。次に酸化・還
元過程は鉄酸化膜が残存する限界を示す。さらに酸化
・還元過程は本発明に係るもので、適正操業範囲に属
する。またはSiの表面濃化の限界点を示し、Si原子が
鈍鉄層（酸化膜が還元された後の鉄の層）の表層まで到
達していない状態であ、は亜鉛浴に入り合金化する
際、SiOx皮膜が表面にあり、鋼板と浴との反応を阻害す
るため、めっき密着性は不良の結果を生ずる。従って
，，は従来における酸化・還元過程を経るもので
あり、本発明は及びに該当するも、は本発明の限
界点に当たる。また第３図は還元能力と鉄酸化膜厚とに
関係を示す図であって、Si濃度1.0％のときの本発明の
操業範囲を定めている。Ａ線は鉄酸化膜残留限界曲線を
示し、下部に当たる鉄酸化膜残留領域では、めっき密着
性は不良となる。また、Ｂ曲線はSi濃化限界線であっ
て、該Ｂ曲線上部はSiの表面濃化によるめっき密着性不
良を起こす領域に該当する。従って、鉄酸化膜残留限界
曲線Ａの上部で、かつSi濃化限界曲線Ｂの下部に当たる
Ｓ部の範囲内に保持できるように、調節する必要があ
る。更に鉄酸化膜はＣ垂直線以下、すなわち1000Å以下
を必要とする。これを超えるとFe−Zn反応が過剰に起こ
り、Fe−Zn界面に脆い合金層が形成し、（過剰合金層成
長領域Ｄ）めっき密着性不良になる。これらを、実操業
連続ラインに採用する。第４図は本発明に係る設備帯概
略図であって、冷間圧延後の鋼帯１を予熱炉２で予め加
熱した後、鋼板に対して垂直に火炎を噴射するバーナー
を用いた加熱炉３で鋼帯の表面生成酸化膜量を1000Åを
超えない範囲で制御しながら、加熱した後、次の還元帯
である均熱炉４及び焼鈍炉５に入る前に、加熱炉での、
表面生成酸化膜量を酸化膜厚計６を用いて実測し、この
実測値に基づいて、前記還元能力をヒートサイクル、ラ
インスピード、還元帯水素濃度を用いて計算し、最適範
囲（Ｓ領域）になるように焼鈍炉５で還元をし、引続き
徐冷帯７および急冷帯８にて、最高850℃の鋼帯温度を4
50〜500℃に急冷する。その後の鋼帯は、ホットブライ
ドル、スナウトを経て、還元雰囲気状態で亜鉛浴10に浸
漬され、ワイピング装置で付着量が調整され、溶融亜鉛
めっき鋼板が得られる。第５図は、本発明の制御システ
ムを示す図であって、鋼帯１は、直火加熱炉３の燃焼廃
ガス廃熱を利用した予熱炉２で予熱された後、直火加熱
炉３で最高約700℃まで鋼帯表面を加熱し、その場合に
鋼板に対して垂直に火炎を噴射するバーナー11を千鳥状
に配設し、酸化膜量を最大1000Åを超えない範囲で急速
加熱する。その結果を酸化膜厚計６からの指令に基づ
き、目標酸化膜比較演算機によって、酸化膜厚検出値と
別に設定した目標値とを比較し、その差信号によって、
直火加熱炉をフイードバック制御する。一方、設定され
た酸化膜厚目標値は還元指令装置に指示され、還元帯で
ある焼鈍炉５に指令され、酸化膜厚を最大50Å以下に保
持するように制御する。この結果を還元帯出速酸化膜厚
計９によって再確認し、もし仮に目標酸化膜厚を超える
場合には、還元指令装置を介して焼鈍炉における還元能
力をフイードバック制御することによって最適目標の酸
化膜厚とするものである。その最適酸化膜厚の状態で徐
冷、急冷して、亜鉛浴10に浸漬され、溶融亜鉛めっき鋼
板が得られる。FIG. 1 is a schematic diagram schematically explaining the above. That is, FIG. 1 shows the oxidation-reduction balance as a change with time. The iron oxide film thickness increases in the oxidation zone, and then the oxide film is reduced in the reduction zone, and t 1
After that, FeO reduction was completed, and Si enrichment was subsequently started. T-t 1
It shows a state in which the concentration of Si progresses within the time and the reduction is carried out within the allowable range of the reducing ability. Further, FIG. 2 schematically shows the locus of the oxidation-reduction balance. During the oxidation / reduction process, the oxide film still remains when entering the zinc bath, so that the alloying characteristics show a poor state. Next, the oxidation / reduction process shows the limit of remaining iron oxide film. Furthermore, the oxidation / reduction process is related to the present invention and belongs to the proper operating range. Or it shows the limit of surface concentration of Si, and when Si atoms do not reach the surface of the blunt iron layer (iron layer after the oxide film is reduced), enters into the zinc bath and alloys At this time, the SiOx film is present on the surface and inhibits the reaction between the steel plate and the bath, resulting in poor adhesion of the plating. Therefore, and are those which have undergone the conventional oxidation / reduction process, and the present invention corresponds to and, but is the limit point of the present invention. FIG. 3 is a diagram showing the relationship between the reducing ability and the iron oxide film thickness, and defines the operating range of the present invention when the Si concentration is 1.0%. Line A shows an iron oxide film residual limit curve, and the plating adhesion becomes poor in the iron oxide film residual region corresponding to the lower part. Further, the B curve is a Si concentration limit line, and the upper portion of the B curve corresponds to a region in which poor plating adhesion is caused by Si surface concentration. Therefore, it is necessary to make adjustments so that the upper limit of the iron oxide film residual limit curve A and the lower limit of the Si concentration limit curve B can be maintained within the range of S part. Further, the iron oxide film needs to have a C vertical line or less, that is, 1000 Å or less. If it exceeds this, the Fe-Zn reaction occurs excessively, a brittle alloy layer is formed at the Fe-Zn interface, and the (excess alloy layer growth region D) plating adhesion becomes poor. These are adopted for the continuous line of actual operation. FIG. 4 is a schematic view of an equipment strip according to the present invention, in which a steel strip 1 after cold rolling is preheated in a preheating furnace 2 and then a heating furnace using a burner for injecting a flame perpendicularly to a steel plate. After heating while controlling the amount of oxide film formed on the surface of the steel strip in the range not exceeding 1000Å in 3 above, before entering the soaking furnace 4 and the annealing furnace 5 which are the next reduction zones, in the heating furnace,
The amount of surface-generated oxide film was actually measured using an oxide film thickness meter 6, and based on the measured value, the reduction capacity was calculated using heat cycle, line speed, and hydrogen concentration in reduced zone, and the optimum range (S region) was calculated. In the annealing furnace 5 and then in the annealing zone 7 and the quenching zone 8 the steel strip temperature up to 850 ° C is increased to 4
Quench to 50-500 ℃. After that, the steel strip passes through a hot bridle and a snout, is immersed in a zinc bath 10 in a reducing atmosphere, and the amount of adhesion is adjusted by a wiping device to obtain a hot dip galvanized steel sheet. FIG. 5 is a diagram showing the control system of the present invention, in which the steel strip 1 is preheated in the preheating furnace 2 utilizing the waste heat of the combustion waste gas of the direct heating furnace 3, and then the direct heating furnace 3 In this case, the surface of the steel strip is heated to a maximum of about 700 ° C, and in that case, the burners 11 that inject a flame perpendicularly to the steel plate are arranged in a staggered manner, and the oxide film amount is rapidly heated within a range not exceeding 1000 Å at the maximum. . Based on the result from the command from the oxide film thickness meter 6, the target oxide film comparison calculator compares the oxide film thickness detection value with a target value set separately, and by the difference signal,
Feedback control of the open flame heating furnace. On the other hand, the set target value of the oxide film thickness is instructed by the reduction command device and is instructed to the annealing furnace 5 which is the reduction zone, and the oxide film thickness is controlled so as to be kept at 50 Å or less at maximum. This result is reconfirmed by the reduction zone output speed oxide film thickness meter 9, and if the target oxide film thickness is exceeded, feedback control of the reducing ability in the annealing furnace is carried out via the reduction command device to achieve the optimum target oxide film thickness. It should be thick. In the state of the optimum oxide film thickness, it is gradually cooled and rapidly cooled and immersed in the zinc bath 10 to obtain a hot dip galvanized steel sheet.
（実施例） 実施例１ C:0.11％ Si:1.0％ Mn:1.50％ Al:0.02％残Feから成
る鋼成分を有する高張力60K残留ｒハイテンを、予熱炉
にて約350℃に加熱し、その後、直火加熱炉にて約700℃
まで加熱をする。この加熱された鋼帯を酸化膜厚計を用
いて生成酸化膜実測し、この実測値が目標酸化膜比較演
算機に送られ、その検出値と別に設定した目標値とを比
較し、その差信号によって、もし仮に1000Åを超す酸化
膜厚の場合には直火加熱炉にフイードバック制御する。
目標酸化膜厚であれば還元指令装置に送られ、焼鈍炉に
て約850℃に加熱される。この加熱された鋼板は均熱、
焼鈍され、徐冷の後450〜500℃に急冷され、亜鉛浴中を
通過させ、エア−ワイピングでめっき量を40g/m2とし
た。その結果を第１表に示すような評価によれば全く亀
裂、剥離が見られなかった。(Example) Example 1 C: 0.11% Si: 1.0% Mn: 1.50% Al: 0.02% High tensile 60K residual r high ten having a steel component consisting of residual Fe was heated to about 350 ° C in a preheating furnace, After that, in an open fire heating furnace at about 700 ℃
Heat up to. This heated steel strip is used to measure the generated oxide film using an oxide film thickness meter, and this measured value is sent to the target oxide film comparison calculator, and the detected value is compared with the target value set separately, and the difference is calculated. If the oxide film thickness exceeds 1000Å, feedback control is applied to the direct heating furnace by the signal.
If it is the target oxide film thickness, it is sent to the reduction command device and heated to about 850 ° C in the annealing furnace. This heated steel plate is soaked,
It was annealed, gradually cooled and then rapidly cooled to 450 to 500 ° C., passed through a zinc bath, and air-wiped to a plating amount of 40 g / m 2 . According to the evaluation results shown in Table 1, no cracks or peeling were observed.
実施例２ C:0.15％ Si:1.2％ Mn:1.50％ Al;0.04％残Feから成
る鋼成分を有する高張力80K残留ｒハイテンを、予熱炉
にて約300℃に加熱し、その後、直火加熱炉にて約700℃
まで加熱をする。この加熱された鋼帯を酸化膜厚計を用
いて生成酸化膜を実測し、この実測値が目標酸化比較演
算機に送られ、その検出値と別に設定した目標値とを比
較し、その差信号によって、もし仮に1200Åの酸化膜厚
の場合には直火加熱炉にフイードバック制御して、空気
比を下げる。目標酸化膜厚であれば還元指令装置に送ら
れ、焼鈍炉にて約850℃に加熱される。この加熱された
鋼板を還元帯である焼鈍炉出側の酸化膜厚計で再確認
し、もし仮に50Å超える酸化膜厚のときは、還元指令装
置を介して、超える分だけを焼鈍炉の水素濃度を上げる
ことによって、目標酸化膜厚の調整をした。その調節後
の酸化膜厚の状態で、450〜500℃に急冷して、亜鉛浴中
を通過させ、エア−ワイピングでめっき量を40g/m2とし
た。その結果を第１表に示す評価によれば４点を得た。Example 2 C: 0.15% Si: 1.2% Mn: 1.50% Al; 0.04% A high-tensile 80K residual r high-tensile steel having a steel component consisting of residual Fe was heated to about 300 ° C. in a preheating furnace, and then an open flame was used. About 700 ℃ in the heating furnace
Heat up to. The oxide film formed on this heated steel strip is measured using an oxide film thickness meter, and the measured value is sent to a target oxidation comparison calculator, and the detected value is compared with a target value set separately, and the difference is calculated. If the oxide film thickness is 1200 Å according to the signal, feedback control is applied to the direct-fired heating furnace to lower the air ratio. If it is the target oxide film thickness, it is sent to the reduction command device and heated to about 850 ° C in the annealing furnace. This heated steel sheet is reconfirmed with an oxide film thickness meter on the exit side of the annealing furnace, which is the reduction zone.If the oxide film thickness exceeds 50Å, only the excess amount of hydrogen in the annealing furnace is passed through the reduction command device. The target oxide film thickness was adjusted by increasing the concentration. The oxide film thickness after the adjustment was rapidly cooled to 450 to 500 ° C., passed through a zinc bath, and the amount of plating was adjusted to 40 g / m 2 by air-wiping. According to the evaluation results shown in Table 1, 4 points were obtained.
（発明の効果） 以上述べたように、本発明は従来の異なり、連続ライ
ンに制御システムを採用し、かつ鉄酸化膜厚と還元能力
との関係を満たすため、酸化帯出側ないしは還元帯出側
をも検出器を設けて酸化膜厚を修正するようにしたの
で、Si含有高張力鋼板であっても、溶融亜鉛めっき条件
をいたずらに変更することなく、普通鋼と同様のめっき
密着性が得られ、亀裂、剥離等を伴うことなく、安定し
た品位で均一な外観の溶融亜鉛めっき鋼板を実用上極め
て有利な高効率適、かつ高生産性を可能ならしめる。 (Effects of the Invention) As described above, the present invention adopts a control system in a continuous line, which is different from the conventional one, and satisfies the relationship between the iron oxide film thickness and the reducing capacity. Since a detector is also provided to correct the oxide film thickness, even with Si-containing high-strength steel sheets, the same plating adhesion as ordinary steel can be obtained without unnecessarily changing the hot dip galvanizing conditions. A hot-dip galvanized steel sheet with stable quality and uniform appearance without cracks, peeling, etc. can be made highly efficient, suitable for practical use, and highly productive.
第１図は酸化、還元バランスを時間の変化として表した
模式図。第２図は酸化、還元バランスの軌跡を模式的に
示した図。第３図は還元能力と酸化帯での生成鉄酸化膜
厚との関係を示す図。第４図は本発明に係る設備概略
図、第５図は本発明の制御システムを示す図である。 Ａ……鉄酸化膜残留限界線、Ｂ……Si濃化限界曲線、Ｃ
……鉄酸化膜厚1000Å垂直線、Ｄ……過剰合金層成長領
域、Ｓ……本発明領域、ａ……余裕代 １……鋼帯、２……予熱炉、３……直火加熱炉 ４……均熱炉、５……焼鈍炉、６……酸化膜厚計 ７……徐冷、８……急冷、９……還元帯出側酸化膜厚
計、10……亜鉛浴、11……バーナーFIG. 1 is a schematic diagram showing the oxidation-reduction balance as a change with time. FIG. 2 is a diagram schematically showing a locus of oxidation-reduction balance. FIG. 3 is a diagram showing the relationship between the reducing ability and the iron oxide film thickness formed in the oxidation zone. FIG. 4 is a schematic view of equipment according to the present invention, and FIG. 5 is a view showing a control system of the present invention. A: Iron oxide film residual limit line, B: Si concentration limit curve, C
…… Iron oxide film thickness 1000 Å vertical line, D …… Excessive alloy layer growth area, S …… Inventive area, a …… Margin allowance 1 …… Steel strip, 2 …… Preheating furnace, 3 …… Direct fire heating furnace 4 ... Soaking furnace, 5 ... Annealing furnace, 6 ... Oxide thickness gauge 7 ... Slow cooling, 8 ... Quenching, 9 ... Reduction zone oxide thickness gauge, 10 ... Zinc bath, 11 ... …burner
フロントページの続き (72)発明者 笠井 研治 千葉県君津市君津１番地 新日本製鐵株 式会社君津製鐵所内 (56)参考文献 特開 昭55−131167（ＪＰ，Ａ)Front page continued (72) Inventor Kenji Kasai 1 Kimitsu, Kimitsu-shi, Chiba Inside Nippon Steel Corporation Kimitsu Works (56) Reference JP-A-55-131167 (JP, A)
Claims (2)
っき鋼板の製造方法において、焼鈍炉の酸化帯での生成
した鉄酸化膜厚を酸化膜厚計にて実測し、一方還元帯で
の鉄酸化膜還元能力をヒートサイクル、ラインスピー
ド、還元帯水素濃度を用いて計算し、該酸化帯での実測
した生成した鉄酸化膜厚に基づいて、 鉄酸化膜厚＋ａ（Å）≦還元能力（Å）≦鉄酸化膜厚＋
ｂ×（鉄酸化膜厚）２（Å） 鉄酸化膜厚≦1000Å a:鉄酸化膜余裕代 b:鋼中Si量により決まる定数 になるように焼鈍条件を制御することを特徴とする高Si
含有高張力溶融亜鉛めっき鋼板の製造方法。1. In a method for producing a high-strength hot-dip galvanized steel sheet having a Si concentration of 0.3% or more in steel, the iron oxide film thickness produced in the oxidation zone of an annealing furnace is measured by an oxide film thickness meter, and the reduction zone is measured. The reduction rate of iron oxide film in the iron oxide film was calculated using the heat cycle, line speed, and hydrogen concentration in the reduction zone, and based on the measured iron oxide film thickness in the oxidation zone, iron oxide film thickness + a (Å) ≤ Reduction capacity (Å) ≤ iron oxide film thickness +
b × (iron oxide film thickness) 2 (Å) iron oxide film thickness ≦ 1000 Å a: iron oxide film allowance b: high Si characterized by controlling the annealing conditions so that it is a constant determined by the amount of Si in the steel
Method for producing high-strength hot-dip galvanized steel sheet containing steel.
っき鋼板の製造方法において、焼鈍炉の酸化帯での生成
した鉄酸化膜厚を酸化膜厚計にて実測し、一方還元帯で
の鉄酸化膜還元能力をヒートサイクル、ラインスピー
ド、還元帯水素濃度を用いて計算し、該酸化帯での実測
した生成した鉄酸化膜厚に基づいて、 入側鉄酸化膜厚＋ａ（Å）≦還元能力（Å）≦入側鉄酸
化膜厚＋ｂ×（入側鉄酸化膜厚）２（Å） 入側鉄酸化膜厚≦1000Å a:鉄酸化膜余裕代 b:鋼中Si量により決まる定数 なるように焼鈍条件を制御すると共に、めっき前の鉄酸
化膜厚を酸化膜厚計にて実測し、還元帯出側での鉄酸化
膜厚ｄ≦50Åに保持するための焼鈍条件をフィードバッ
ク制御することを特徴とする高Si含有高張力溶融亜鉛め
っき鋼板の製造方法。2. In a method for producing a high-strength hot-dip galvanized steel sheet having a Si concentration of 0.3% or more in steel, the iron oxide film thickness produced in the oxidation zone of the annealing furnace is measured by an oxide film thickness meter, and the reduction zone is measured. Of the iron oxide film reduction rate at the heating side, line speed, and hydrogen concentration in the reduction zone were calculated, and the iron oxide film thickness on the inlet side + a (Å ) ≤ Reduction capacity (Å) ≤ Inlet iron oxide film thickness + b × (Inlet iron oxide film thickness) 2 (Å) Inlet iron oxide film thickness ≤ 1000 Å a: Iron oxide film allowance b: Depending on the amount of Si in steel The annealing conditions are controlled so that the constants are determined, the iron oxide film thickness before plating is measured with an oxide film thickness meter, and the annealing condition for maintaining the iron oxide film thickness d ≦ 50Å on the reduction zone output side is fed back. A method for producing a high-Si high-strength hot-dip galvanized steel sheet characterized by controlling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2329549A JP2530939B2 (en) | 1990-11-30 | 1990-11-30 | Method for manufacturing high-strength hot-dip galvanized steel sheet containing high Si |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2329549A JP2530939B2 (en) | 1990-11-30 | 1990-11-30 | Method for manufacturing high-strength hot-dip galvanized steel sheet containing high Si |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04202633A JPH04202633A (en) | 1992-07-23 |
| JP2530939B2 true JP2530939B2 (en) | 1996-09-04 |
Family
ID=18222602
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2329549A Expired - Lifetime JP2530939B2 (en) | 1990-11-30 | 1990-11-30 | Method for manufacturing high-strength hot-dip galvanized steel sheet containing high Si |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2530939B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008001934A (en) * | 2006-06-21 | 2008-01-10 | Kobe Steel Ltd | Hot-dip galvanization equipment |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2782326B1 (en) * | 1998-08-13 | 2000-09-15 | Air Liquide | METHOD FOR GALVANIZING A METAL STRIP |
| WO2006068169A1 (en) | 2004-12-21 | 2006-06-29 | Kabushiki Kaisha Kobe Seiko Sho | Method and facility for hot dip zinc plating |
| JP5966528B2 (en) | 2011-06-07 | 2016-08-10 | Ｊｆｅスチール株式会社 | High strength hot-dip galvanized steel sheet with excellent plating adhesion and method for producing the same |
| KR101657862B1 (en) | 2012-04-17 | 2016-09-19 | 제이에프이 스틸 가부시키가이샤 | Method for producing alloyed hot-dip galvanized steel sheet having excellent adhesion to plating and excellent sliding properties |
| JP5920249B2 (en) | 2013-03-05 | 2016-05-18 | Ｊｆｅスチール株式会社 | High strength hot-dip galvanized steel sheet with excellent plating adhesion and method for producing the same |
| JP5962582B2 (en) | 2013-05-21 | 2016-08-03 | Ｊｆｅスチール株式会社 | Method for producing high-strength galvannealed steel sheet |
| KR101797417B1 (en) | 2013-12-13 | 2017-11-13 | 제이에프이 스틸 가부시키가이샤 | Method for producing high-strength galvannealed steel sheets |
| US10648054B2 (en) | 2014-09-08 | 2020-05-12 | Jfe Steel Corporation | Method and facility for producing high-strength galavanized steel sheets |
| JP6237937B2 (en) | 2016-03-11 | 2017-11-29 | Ｊｆｅスチール株式会社 | Method for producing high-strength hot-dip galvanized steel sheet |
| KR102231412B1 (en) | 2016-10-25 | 2021-03-23 | 제이에프이 스틸 가부시키가이샤 | Manufacturing method of high-strength hot-dip galvanized steel sheet |
-
1990
- 1990-11-30 JP JP2329549A patent/JP2530939B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008001934A (en) * | 2006-06-21 | 2008-01-10 | Kobe Steel Ltd | Hot-dip galvanization equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04202633A (en) | 1992-07-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2647687C (en) | Hot dip coating process for a steel plate product made of high strengthheavy-duty steel | |
| US20230082367A1 (en) | Method of producing high-strength hot-dip galvanized steel sheet | |
| JP2587724B2 (en) | Method for producing high Si content high tensile galvanized steel sheet with good plating adhesion | |
| JP2530939B2 (en) | Method for manufacturing high-strength hot-dip galvanized steel sheet containing high Si | |
| JP2513532B2 (en) | Method for producing high-strength hot-dip galvanized steel sheet of high Si content steel | |
| US6635313B2 (en) | Method for coating a steel alloy | |
| JP2007191745A (en) | High-strength hot-dip galvanized steel sheet, its manufacturing device, and manufacturing method of high-strength hot dip zincing steel sheet | |
| JP2587725B2 (en) | Method for producing P-containing high tensile alloyed hot-dip galvanized steel sheet | |
| JP2970445B2 (en) | Hot-dip galvanizing method for Si-added high tensile steel | |
| JP3415191B2 (en) | Manufacturing method of high-strength hot-dip galvanized steel sheet | |
| JPH04254531A (en) | Method for annealing high si-containing high tensile strength steel before galvanizing | |
| JPH04254532A (en) | Manufacture of galvannealed steel sheet having excellent workability | |
| JPH05331609A (en) | Production of galvannealed steel sheet excellent in image clarity after coating | |
| JP2002030403A (en) | Hot dip galvannealed steel sheet and its production method | |
| JP2704819B2 (en) | Method for producing high-Si hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet | |
| US4123292A (en) | Method of treating steel strip and sheet surfaces for metallic coating | |
| JP2618308B2 (en) | High Si content High tensile galvanized steel sheet | |
| JPH0748662A (en) | Production of galvanized steel sheet excellent in plating adhesion and appearance | |
| US4123291A (en) | Method of treating steel strip and sheet surfaces, in sulfur-bearing atmosphere, for metallic coating | |
| JP2576329B2 (en) | Method for producing high-strength alloyed hot-dip galvanized steel sheet with excellent coating uniformity and powdering resistance | |
| JP2618306B2 (en) | High P content high tensile galvanized steel sheet | |
| JP2648772B2 (en) | High P content high tensile galvanized steel sheet | |
| JP3166568B2 (en) | Manufacturing method of hot-dip galvanized steel | |
| JP2700516B2 (en) | Method for producing high Si content strength galvannealed steel sheet with good plating adhesion | |
| JPH04254530A (en) | Method for annealing high p-containing high tensile strength steel before galvannealing |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080627 Year of fee payment: 12 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090627 Year of fee payment: 13 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090627 Year of fee payment: 13 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100627 Year of fee payment: 14 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100627 Year of fee payment: 14 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110627 Year of fee payment: 15 |
|
| EXPY | Cancellation because of completion of term | ||
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110627 Year of fee payment: 15 |