JP5850005B2 - Method for producing hot-dip galvanized steel sheet - Google Patents
Method for producing hot-dip galvanized steel sheet Download PDFInfo
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- JP5850005B2 JP5850005B2 JP2013167288A JP2013167288A JP5850005B2 JP 5850005 B2 JP5850005 B2 JP 5850005B2 JP 2013167288 A JP2013167288 A JP 2013167288A JP 2013167288 A JP2013167288 A JP 2013167288A JP 5850005 B2 JP5850005 B2 JP 5850005B2
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- 229910001335 Galvanized steel Inorganic materials 0.000 title claims description 21
- 239000008397 galvanized steel Substances 0.000 title claims description 21
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- 229910000831 Steel Inorganic materials 0.000 claims description 51
- 238000005096 rolling process Methods 0.000 claims description 51
- 239000010959 steel Substances 0.000 claims description 51
- 238000005246 galvanizing Methods 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 15
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 13
- 229910052725 zinc Inorganic materials 0.000 claims description 13
- 239000011701 zinc Substances 0.000 claims description 13
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010960 cold rolled steel Substances 0.000 claims description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 238000007747 plating Methods 0.000 description 24
- 238000005097 cold rolling Methods 0.000 description 18
- 238000000137 annealing Methods 0.000 description 8
- 238000009826 distribution Methods 0.000 description 8
- 230000003746 surface roughness Effects 0.000 description 8
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 238000005554 pickling Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- -1 aluminum-zinc-silicon Chemical compound 0.000 description 2
- 238000005422 blasting Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000007598 dipping method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 229910000611 Zinc aluminium Inorganic materials 0.000 description 1
- 229910001297 Zn alloy Inorganic materials 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- HXFVOUUOTHJFPX-UHFFFAOYSA-N alumane;zinc Chemical compound [AlH3].[Zn] HXFVOUUOTHJFPX-UHFFFAOYSA-N 0.000 description 1
- DQIPXGFHRRCVHY-UHFFFAOYSA-N chromium zinc Chemical compound [Cr].[Zn] DQIPXGFHRRCVHY-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- KFZAUHNPPZCSCR-UHFFFAOYSA-N iron zinc Chemical compound [Fe].[Zn] KFZAUHNPPZCSCR-UHFFFAOYSA-N 0.000 description 1
- QELJHCBNGDEXLD-UHFFFAOYSA-N nickel zinc Chemical compound [Ni].[Zn] QELJHCBNGDEXLD-UHFFFAOYSA-N 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 description 1
- YJVLWFXZVBOFRZ-UHFFFAOYSA-N titanium zinc Chemical compound [Ti].[Zn] YJVLWFXZVBOFRZ-UHFFFAOYSA-N 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
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- Metal Rolling (AREA)
- Coating With Molten Metal (AREA)
Description
本発明は、熱延鋼板を酸洗後、冷間タンデム圧延機にて所定の板厚まで圧延し、さらに表面を溶融亜鉛系めっきする溶融亜鉛系めっき鋼板の製造の際に表面にできる模様の調整方法に関する。 In the present invention, a hot-rolled steel sheet is pickled and then rolled to a predetermined thickness with a cold tandem rolling mill. It relates to the adjustment method.
一般に、溶融亜鉛系めっき鋼板の表面には、溶融亜鉛層が凝固する際に、その凝固核を中心に亜鉛（もしくは亜鉛合金）が溶融状態のまま樹枝状に結晶する結果、いわゆるスパングルと称される華紋状の模様が発生する。
近年、めっき条件や母板条件を調整することにより、スパングルの大きさを極小さなものとするか、あるいは完全に無くすことも出来るようになっている。一方で、スパングルの独特の模様を外観上の特徴として、意識的に残した鋼板も製造されている。
スパングルの大きさは当然厳密に一定となるものではなく、数ｍｍから数十ｍｍの範囲でばらつきがある。それぞれの大きさのスパングルがランダムに散在している場合は外観上問題にならないが、スポット状あるいは幅方向、長手方向の線上に大きさの分布が異なる部分が存在する場合は、スパングルのばらつきが視認されるため、いわゆるスパングルムラとよばれる不良となる。
In general, when the molten zinc layer solidifies on the surface of the hot dip galvanized steel sheet, zinc (or zinc alloy) crystallizes in a dendritic state around the solidification nucleus, so-called spangles. A wavy pattern appears.
In recent years, the size of spangles can be made extremely small or completely eliminated by adjusting the plating conditions and the base plate conditions. On the other hand, steel plates that are consciously left with a unique spangle pattern are also produced.
Of course, the size of the spangle is not strictly constant, and varies in the range of several mm to several tens of mm. If the spangles of each size are scattered randomly, there is no problem in appearance, but if there are parts with different size distribution on the spot shape or the line in the width direction and the longitudinal direction, the spangle variation will be Since it is visually recognized, it becomes a defect called so-called spangle unevenness.
スパングルの大きさを調整する方法として、特許文献1に、「十点平均粗さ（Ｒｚ）が１〜５μｍであり、中心線平均粗さ（Ｒａ）が、０．１〜１．５μｍである冷延鋼板に溶融亜鉛めっきを施して得られる、外観性に優れた溶融亜鉛めっき鋼板」が記載されている。確かに、この方法によると、スパングルの大きさを調整することができる。しかしこの方法で製造した場合、スパングルムラが見られることがある。例えば、アルミニウム-亜鉛-ケイ素を含む溶融亜鉛めっき鋼板であるガルバニウム鋼板を製造すると、スパングルの大きさが局所的かつ連続的に周辺部と異なる異常が見られ、充分均質なスパングル表面が得られずスパングルムラが見られることがある。 As a method for adjusting the size of spangle, Patent Document 1 states that “10-point average roughness (R z ) is 1 to 5 μm and center line average roughness (Ra) is 0.1 to 1.5 μm. A hot dip galvanized steel sheet excellent in appearance, obtained by subjecting a cold-rolled steel sheet to hot dip galvanizing is described. Certainly, according to this method, the size of the spangle can be adjusted. However, when manufactured by this method, spangle unevenness may be observed. For example, when a galvanium steel sheet, which is a hot-dip galvanized steel sheet containing aluminum-zinc-silicon, is manufactured, abnormalities that are locally and continuously different from the periphery are observed, and a sufficiently uniform spangle surface cannot be obtained. Spangle unevenness may be seen.
スパングルムラをなくす製造方法として、特許文献２に記載のように鋼中成分および熱延工程でのデスケーリングを調整する方法、特許文献３に記載のようにめっき浴温度および鋼板温度を調整する方法、特許文献４に記載のようにスパングル自体を無くすために酸洗やブラスト処理によりめっき用の原板に凹凸を付ける方法が知られている。
しかし、これらの製造方法でもスパングルムラが発生することがあった。特許文献２には鋼板表面の凹凸がスパングルムラの原因になることが示唆されているが、十分な対策が無いと記述されており、スパングルムラを防止できていなかった。特許文献４では酸洗やブラスト処理を行うことによりめっき用原板の表面に凹凸を付けることで溶融亜鉛が凝固する際の結晶核生成サイトとして機能させ、亜鉛結晶を微細化することにより、スパングル模様を抑えて均一な表面外観を得ることが記述されているが、やはり、完全にスパングルムラを無くすことはできなかった。
As a production method for eliminating spangle unevenness, a method for adjusting descaling in steel components and hot rolling process as described in Patent Document 2, and a method for adjusting plating bath temperature and steel plate temperature as described in Patent Document 3 In order to eliminate spangles themselves as described in Patent Document 4, there is known a method for forming irregularities on a plate for plating by pickling or blasting.
However, even in these manufacturing methods, spangle unevenness may occur. Patent Document 2 suggests that unevenness on the surface of the steel sheet causes spangle unevenness, but it is described that there is no sufficient countermeasure, and spangle unevenness has not been prevented. In Patent Document 4, the surface of the original plate for plating is made uneven by performing pickling or blasting to function as a crystal nucleation site when molten zinc solidifies, and by making the zinc crystal finer, a spangle pattern is obtained. Although it is described that a uniform surface appearance can be obtained by suppressing the above, spangle unevenness cannot be completely eliminated.
本発明者等は上記背景技術を検討し、ある分布を持った大きさのスパングルをランダムに発生させれば、スパングルムラとして知覚される外観ムラを安定してなくすことができることを知見し本発明をなした。 The inventors of the present invention have studied the above-mentioned background art, and found that the appearance unevenness perceived as spangle unevenness can be stably eliminated by randomly generating spangles having a certain distribution size. Made.
本発明者等は、上記目的を達成すべく鋭意研究した結果、冷間タンデム圧延において最終スタンドに供給する鋼板表面を特定範囲の粗面として、最終スタンドをダルロールとし、特定の圧延荷重として冷間ダルロール圧延すれば、特定の分布を持った大きさのスパングルをランダムに発生させることができ、結果として外観ムラを安定して無くすことができることがわかった。 As a result of diligent research to achieve the above object, the present inventors have determined that the steel sheet surface supplied to the final stand in cold tandem rolling is a rough surface in a specific range, the final stand is a dull roll, and a cold is applied as a specific rolling load. It was found that spangles having a specific distribution can be randomly generated by dull roll rolling, and as a result, uneven appearance can be stably eliminated.
すなわち、本発明は、以下を提供する。
（１）鋼板表面の凹凸の大きさの分布が十点平均粗さ（Ｒｚjis）が１〜５μｍであり、中心線平均粗さ（Ｒａ）が、０．１〜１．５μｍである冷延鋼板を、冷間タンデム圧延の最終スタンドに供給し、前記最終スタンドは、圧延荷重を０ｋＮ/ｍｍ超〜４．０ｋＮ/ｍｍ以下でダルロールで圧延する、溶融亜鉛系めっき用鋼板の製造方法。
（２）前記溶融亜鉛系めっき鋼板がアルミニウム、亜鉛、珪素を含む合金亜鉛めっき鋼板である（１）に記載の溶融亜鉛系めっき用鋼板の製造方法。
（３）前記最終スタンドに用いるダルロールの中心線平均粗さ（Ｒａ）が２．０μｍ以上である（１）または（２）に記載の溶融亜鉛系めっき用鋼板の製造方法。
That is, the present invention provides the following.
(1) Cold rolled steel sheet having a ten-point average roughness (Rzjis) of 1 to 5 μm and a center line average roughness (Ra) of 0.1 to 1.5 μm. Is supplied to the final stand of cold tandem rolling, and the final stand is rolled with a dull roll at a rolling load of more than 0 kN / mm to 4.0 kN / mm or less.
(2) The method for producing a hot-dip galvanized steel sheet according to (1), wherein the hot-dip galvanized steel sheet is an alloy galvanized steel sheet containing aluminum, zinc, and silicon.
(3) The method for producing a hot-dip galvanized steel sheet according to (1) or (2), wherein the center line average roughness (Ra) of the dull roll used in the final stand is 2.0 μm or more.
本発明によれば、特別な装置や工程が必要なく簡易な製造方法で、表面のスパングルムラのない溶融亜鉛系めっき鋼板が提供される。 According to the present invention, a hot dip galvanized steel sheet having no surface spangle unevenness is provided by a simple manufacturing method that does not require a special apparatus or process.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
本発明の溶融亜鉛系めっき用鋼板は、低炭素鋼スラブを熱間圧延した後、酸洗し、さらに冷間圧延して製造される。製造された溶融亜鉛系めっき用鋼板は、焼鈍、溶融亜鉛系めっき、必要な場合は加熱合金化処理をされて、合金化溶融亜鉛系めっき鋼板を得る。
酸洗条件は、従来から行われている方法で実施できる、例えば、５０℃以上の塩酸中に鋼板を浸漬する。
The steel sheet for hot dip galvanizing of the present invention is manufactured by hot rolling a low carbon steel slab, pickling, and further cold rolling. The manufactured hot dip galvanized steel sheet is annealed, hot dip galvanized and, if necessary, heat-alloyed to obtain an galvannealed steel sheet.
Pickling conditions can be carried out by a conventional method. For example, the steel sheet is immersed in hydrochloric acid at 50 ° C. or higher.
＜冷間圧延工程＞
本発明の溶融亜鉛系めっき用鋼板の製造方法は冷間圧延工程に特徴を有する。
冷間圧延には、図１に例示するような複数スタンドからなるタンデム・ミルを使用する。図１の装置例は、４段式の圧延スタンドを全部で５スタンド直列に配置したもので、第１スタンドに高粗度のワーク・ロール３を、第２〜４スタンドにブライト・ワーク・ロール４を、最終スタンドにダル加工ワーク・ロール５を配置している。鋼帯１の進行方向および圧延後の最終冷延板２が矢印で示される。
<Cold rolling process>
The manufacturing method of the hot dip galvanizing steel sheet of the present invention is characterized by a cold rolling process.
For cold rolling, a tandem mill consisting of a plurality of stands as illustrated in FIG. 1 is used. In the example of the apparatus shown in FIG. 1, four stages of rolling stands are arranged in series in a total of five stands, a high-roughness work roll 3 is provided in the first stand, and bright work rolls are provided in the second to fourth stands. 4 and a dull processing work roll 5 is arranged on the final stand. The direction of travel of the steel strip 1 and the final cold-rolled sheet 2 after rolling are indicated by arrows.
しかしながら、本発明では、圧延機の段数スタンド数は図１の例に限られるものではない。最終スタンドに配置するロールはダル加工ワークロールであり、ロールの表面粗度が２．０μｍ以上３．０μｍ以下とするのが好ましい。この理由は、この範囲であれば本発明の圧延荷重範囲で所定の表面状態を作り込むことが容易となり、冷間圧延後に行う溶融亜鉛系めっき処理でのスパングルムラを抑えることができるからである。原板粗さの影響を最小限にするため、前段側で高粗度のロールを使用することが好ましく、第１スタンドに高粗度のワーク・ロール３を用いたが、これに限ることはなく、高粗度のワーク・ロール３は、最終スタンドから３番目までに少なくとも１ケ所配置すればよい。ただし、第１スタンドへの適用を規準として、後段側にスタンド数を増やしていくことが好ましい。 However, in the present invention, the number of stages of the rolling mill is not limited to the example of FIG. The roll placed on the final stand is a dull work roll, and the surface roughness of the roll is preferably 2.0 μm or more and 3.0 μm or less. This is because, within this range, it becomes easy to create a predetermined surface state within the rolling load range of the present invention, and spangle unevenness in hot dip galvanizing treatment performed after cold rolling can be suppressed. . In order to minimize the influence of the roughness of the original plate, it is preferable to use a high-roughness roll on the front stage side, and a high-roughness work roll 3 is used for the first stand, but this is not restrictive. The high-roughness work roll 3 may be arranged at least one place from the last stand to the third. However, it is preferable to increase the number of stands on the rear side with reference to application to the first stand.
なお、本発明では、高粗度のロール３の種類は、ショット・ダル加工ロールでもスクラッチ・ダル加工ロールのいずれでも良い。これは、冷延後の鋼板表面に適切なメタル・フローを付与するには、該ロールの表面粗度が大きいことのみが必要十分条件だからである。ただし所定の圧下率を付与するためにスクラッチ・ダル加工ロールであることが好ましい。それ以外のスタンドで使用するブライトロールのＲａは、０．５μｍ以下、さらには０．３μｍ以下が好ましい。０．５μｍを超えて大きいと、最終スタンドでの粗さ制御が困難となり効果が得られないからである。
タンデム・ミルを用い、本発明に係る製造方法では、どのように冷延鋼板を製造するかを、図１に示した５スタンドのタンデム・ミルでの例で、以下に説明する。
In the present invention, the type of the high roughness roll 3 may be either a shot dull processing roll or a scratch dull processing roll. This is because only a large surface roughness of the roll is a necessary and sufficient condition for imparting an appropriate metal flow to the steel sheet surface after cold rolling. However, in order to provide a predetermined rolling reduction, it is preferably a scratch / dull processing roll. The brightness of the bright roll used in other stands is preferably 0.5 μm or less, more preferably 0.3 μm or less. This is because if it exceeds 0.5 μm, it becomes difficult to control the roughness at the final stand, and the effect cannot be obtained.
In the manufacturing method according to the present invention using a tandem mill, how to manufacture a cold-rolled steel sheet will be described below using the example of the 5-stand tandem mill shown in FIG.
まず、最初の第１スタンドにロール表面のＲａが１μｍと高い円筒研磨・ダル加工・ロール３を配置して、熱延原板１を圧延し、該原板表面のＲａを１．５μｍ程度とする。その原板１を、引き続き、第２〜４スタンドでＲａが０．３μｍのブライト・ロール４を用いて圧延し、母板の表面粗さの影響を除いた平滑な表面にする。 First, cylindrical polishing / dull processing / roll 3 having a high Ra of 1 μm on the roll surface is placed on the first first stand, and the hot-rolled original sheet 1 is rolled so that the Ra of the original sheet surface is about 1.5 μm. Subsequently, the original plate 1 is rolled using a bright roll 4 with Ra of 0.3 μm on the second to fourth stands to obtain a smooth surface excluding the influence of the surface roughness of the mother plate.
最終スタンドに供給する鋼板表面の凹凸の大きさの分布は、十点平均粗さ（Ｒｚjis）が１〜３μｍであり、中心線平均粗さ（Ｒａ）が、０．１０〜０．４μｍである。ここで十点平均粗さ、中心線平均粗さとも接触式表面粗さ計で測定した値である。測定条件は、カットオフ０．８ｍｍ、測定長４ｍｍであり、鋼板巾方向に１０個測定した場合の平均値である。 The distribution of the unevenness on the surface of the steel sheet supplied to the final stand has a ten-point average roughness (Rz jis ) of 1 to 3 μm and a center line average roughness (Ra) of 0.10 to 0.4 μm. is there. Here, the ten-point average roughness and the center line average roughness are values measured by a contact-type surface roughness meter. The measurement conditions are a cut-off of 0.8 mm, a measurement length of 4 mm, and an average value when 10 pieces are measured in the steel plate width direction.
そして、第５スタンドで、ダル仕上げロール５で最終調整を行い、所望の溶融亜鉛系めっき用の冷延原板２を得る。このとき本発明の方法では、最終スタンドのダルロールで圧延荷重を０ｋＮ/ｍｍ超〜４．０ｋＮ/ｍｍ以下で圧延して溶融亜鉛系めっき用鋼板を得る。 Then, final adjustment is performed with the dull finish roll 5 on the fifth stand, and the desired cold-rolled original sheet 2 for hot dip galvanizing is obtained. At this time, in the method of the present invention, a hot-dip galvanized steel sheet is obtained by rolling with a dull roll of the final stand at a rolling load of more than 0 kN / mm to 4.0 kN / mm.
＜冷間圧延後の工程＞
焼鈍は、冷延による延伸組織が十分に再結晶する条件であればよく、例えば７５０℃以上８５０℃以下の均熱温度で３０秒以上１５０秒以内で加熱する。好ましくは、８００℃で１２０秒、等の工程が挙げられる。
焼鈍後は、溶融亜鉛系めっき、加熱合金化処理を行う。溶融亜鉛系めっきの成分は特に限定されず公知の亜鉛、または亜鉛系合金めっき（以下亜鉛めっきを含めて亜鉛系めっきという）をすることができる。亜鉛系めっき鋼板とは、例えば、亜鉛めっき鋼板、亜鉛−ニッケルめっき鋼板、亜鉛−鉄めっき鋼板、亜鉛−クロムめっき鋼板、亜鉛−アルミニウムめっき鋼板、亜鉛−アルミニウム−ケイ素めっき鋼板、亜鉛−チタンめっき鋼板、亜鉛−マグネシウムめっき鋼板、亜鉛−マンガンめっき鋼板等の溶融めっき鋼板であり、亜鉛を含む溶融めっきが施された鋼板であれば特に制限されない。
亜鉛系めっき浴の温度は４４０℃〜５００℃で、鋼板をめっき浴に浸漬して引き上げる。特に、本発明はめっき金属として、アルミニウム（Ａｌ）５５質量％＋亜鉛（Ｚｎ）４３．４質量％＋珪素（Ｓｉ）１．６質量％の合金を用いて溶融めっきし、ガルバリウム鋼板を製造する場合に本発明の溶融亜鉛系めっき用鋼板を用いるとスパングルムラを防止する効果が最も顕著となるので好ましい。本発明の溶融亜鉛系めっき用鋼板が特にガルバリウム鋼板を製造する場合に、特にスパングルムラがみられない理由は、不明であるが、表面粗さプロフィールにおける、特に凸部の形態・分布が影響していると考えられる。Ａｌはめっき層表面に強固な不動態皮膜を形成して、めっき層の耐食性を上げる。
溶融亜鉛系めっき後、ワイピングでめっき付着量が３５〜５０ｇ／ｍ2となるよう調整する。好ましくは窒素ガスによるガスワイビングを行う。
加熱合金化する場合は、温度は４８０〜５６０℃とすることが好ましい。以上のような条件で製造することで、外観品位に優れた溶融亜鉛系めっき鋼板を製造できる。
<Process after cold rolling>
The annealing may be performed under the condition that the stretched structure by cold rolling is sufficiently recrystallized. For example, the annealing is performed at a soaking temperature of 750 ° C. or more and 850 ° C. or less for 30 seconds or more and 150 seconds or less. Preferably, a step such as 120 seconds at 800 ° C. is used.
After annealing, hot dip galvanizing and heat alloying are performed. The components of the hot dip galvanizing are not particularly limited, and known zinc or zinc based alloy plating (hereinafter referred to as zinc galvanizing including galvanizing) can be performed. Examples of galvanized steel sheets include galvanized steel sheets, zinc-nickel plated steel sheets, zinc-iron plated steel sheets, zinc-chromium plated steel sheets, zinc-aluminum plated steel sheets, zinc-aluminum-silicon plated steel sheets, and zinc-titanium plated steel sheets. , Zinc-magnesium-plated steel sheet, zinc-manganese-plated steel sheet, etc.
The temperature of the zinc-based plating bath is 440 ° C. to 500 ° C., and the steel plate is immersed in the plating bath and pulled up. In particular, according to the present invention, a galbarium steel sheet is manufactured by hot-dip plating using an alloy of aluminum (Al) 55 mass% + zinc (Zn) 43.4 mass% + silicon (Si) 1.6 mass% as the plating metal. In this case, it is preferable to use the hot dip galvanized steel sheet according to the present invention because the effect of preventing spangle unevenness is most remarkable. When the hot-dip galvanized steel sheet of the present invention produces a galvalume steel sheet in particular, the reason why spangle unevenness is not particularly seen is unclear, but the surface roughness profile affects the shape / distribution of the projections in particular. It is thought that. Al forms a strong passive film on the surface of the plating layer and improves the corrosion resistance of the plating layer.
After hot-dip galvanized coating weight in the wiping is adjusted to be 35~50g / m 2. Preferably, gas wiping with nitrogen gas is performed.
In the case of alloying by heating, the temperature is preferably 480 to 560 ° C. By producing under the above conditions, a hot-dip galvanized steel sheet having excellent appearance quality can be produced.
通常、溶融亜鉛系めっき鋼板は、製鋼工程で成型されたスラブを、熱間圧延、酸洗、冷間圧延により所定の厚みに圧延した後、連続溶融めっきラインにより焼鈍と鋼板表面へのめっき層形成が連続的に行われることにより製造される。冷間圧延工程で最終スタンドにダルロールを用いると、原板における不純物による表面欠陥や、各製造工程における微小な疵の影響を最小限にできる利点がある。冷間圧延後の鋼板表面には主にロールのダル目が転写することによる凹凸が形成されるが、これまでこの鋼板表面の凹凸とスパングルムラ発生の関係は明確になっていなかった。
本発明者らは、冷間圧延後の鋼板の粗さプロフィールを調整することにより、適当な大きさと分布を有するスパングルを残しても、それがムラとして視認されない方法があるのではないかと考え、粗さとスパングルムラ発生との関係の調査を実施した。
Usually, hot-dip galvanized steel sheets are obtained by rolling a slab formed in the steelmaking process to a predetermined thickness by hot rolling, pickling, and cold rolling, and then annealing and plating layers on the steel sheet surface using a continuous hot dipping line. It is manufactured by forming continuously. When a dull roll is used for the final stand in the cold rolling process, there is an advantage that the influence of surface defects due to impurities in the original plate and fine wrinkles in each manufacturing process can be minimized. Irregularities are formed mainly on the surface of the steel sheet after cold rolling due to the transfer of the rolls of the rolls, but the relationship between the irregularities on the surface of the steel sheet and the occurrence of spangle unevenness has not been clarified so far.
The present inventors think that there is a method in which even if a spangle having an appropriate size and distribution is left by adjusting the roughness profile of the steel sheet after cold rolling, it is not visually recognized as unevenness. We investigated the relationship between roughness and the occurrence of spangles.
特に冷間タンデム圧延最終スタンドの粗さ転写形態とスパングルムラの関係に着目した。冷間タンデム圧延機にて厚み０．８ｍｍの冷間圧延したサンプルを鋼板表面の凹凸を３種類に変えて用意し、ラボ圧延機にて冷間タンデム圧延機の最終スタンドを模擬した冷間圧延機で圧延荷重、圧下率を変更して冷間圧延実験を実施したのち、焼鈍、亜鉛系めっきを行った。 In particular, we focused on the relationship between roughness transfer form and spangle unevenness in the final stand of cold tandem rolling. Prepare a cold rolled tandem rolling mill sample with a thickness of 0.8 mm, changing the surface irregularities of the steel sheet to three types, and simulating the final stand of the cold tandem rolling mill with a laboratory rolling mill After changing the rolling load and rolling reduction with a machine and conducting a cold rolling experiment, annealing and zinc plating were performed.
焼鈍は８００℃で１２０秒、溶融亜鉛系めっきは、浴温４６０℃のＺｎ−０．１３質量％Ａｌめっき浴、または４３．４質量％Ｚｎ−５５質量％Ａｌ＋１．６質量％Ｓｉの合金めっきを用いてに３秒浸し、ワイピングでめっき付着量が４５ｇ／ｍ2となるよう調整し、５００℃の温度で合金化処理した。なお、スパングルムラに対する鋼板表面凹凸の影響を調査するため、サンプル端部にめっきしない部分を残した。 Annealing is 800 ° C. for 120 seconds, and hot dip galvanizing is a Zn-0.13 mass% Al plating bath with a bath temperature of 460 ° C., or an alloy plating of 43.4 mass% Zn-55 mass% Al + 1.6 mass% Si. Was immersed for 3 seconds, adjusted to a plating adhesion of 45 g / m 2 by wiping, and alloyed at a temperature of 500 ° C. In addition, in order to investigate the influence of the unevenness of the steel sheet surface on the spangle unevenness, a portion not plated was left at the end of the sample.
実験の結果、図４〜６に示すように、特定の圧延荷重・圧下率範囲でスパングルムラが発生することがわかった。本調査では、ムラは全て長手方向に走るものであり、幅方向の一部分だけが他に比べてスパングルが小さくなっていた。同一サンプル内でめっきしない部分における粗さを測定したが、スパングルムラに対応した粗さの違いは見られなかった。
溶融亜鉛系めっきの合金成分、Ｚｎ−０．１３質量％Ａｌめっき、または４３．４質量％Ｚｎ−５５質量％Ａｌ＋１．６質量％Ｓｉめっきによる上記傾向の変動は見られなかったが、４３．４質量％Ｚｎ−５５質量％Ａｌ＋１．６質量％Ｓｉめっきの方がより圧下率と圧延荷重の好適範囲が狭かった。図４〜６は、４３．４質量％Ｚｎ−５５質量％Ａｌ＋１．６質量％Ｓｉ溶融めっきの結果を示す。
As a result of the experiment, as shown in FIGS. 4 to 6, it was found that spangle unevenness occurred in a specific rolling load and rolling reduction range. In this survey, all of the unevenness runs in the longitudinal direction, and only a part of the width direction has a smaller spangle than the others. Roughness was measured at the portion of the same sample that was not plated, but no difference in roughness corresponding to spangle unevenness was found.
While the alloy component of hot dip galvanizing, Zn-0.13% by mass Al plating, or 43.4% by mass Zn-55% by mass Al + 1.6% by mass Si plating did not show any change in the above tendency. 4 mass% Zn-55 mass% Al + 1.6 mass% Si plating had a narrower suitable ratio of rolling reduction and rolling load. 4-6 shows the result of 43.4 mass% Zn-55 mass% Al + 1.6 mass% Si hot dipping.
図２に鋼板サンプルのめっき前の表面の三次元粗さプロフィールを示す。図２Ａでは溶融亜鉛系めっき後スパングルムラが発生したサンプルの冷間圧延終了状態の鋼板表面の凹凸を示している。図２Ａでは、圧延方向の線との角度が１２０度〜６０度で交差する圧延方向線上にあらわれる直線または曲線状の凸部（以下、線上凸部という）が矢印で示されている。一方図２Ｂでは、鋼板表面の凹凸で、圧延方向の線上に交差する凸部が見られなかった。図２Ｂの溶融亜鉛系めっき用鋼板を溶融亜鉛系めっきしたところスパングルムラは発生しなかった。
スパングルムラが発生した線上凸部が形成される図２Ａの圧延条件では、図３Ｂに示すように冷間タンデム圧延において、ロール表面の凹凸部の凸部が鋼板表面に食い込み相対滑りを起こすことによって圧延方向と交差する方向に線上凸部が形成されていることがわかった。
線上凸部が見られない冷間タンデム圧延後のサンプルは、その後溶融亜鉛系めっきしてもその表面にスパングルムラがみられない。なお、該当線上凸部の形態、分布、高さ、長さについて、スパングルムラの発生した部位に対応した変化は見られなかった。すなわち、転写した粗さに不均一があってそれに対応してスパングルムラが発生するのではなく、スパングルムラの発生が全体的な粗さによって決まることを明らかにしたのである。
この線上凸部の有無で表面粗さパラメータＲｓｋ（ゆがみ度）、Ｒｋｕ（とがり度）で整理したところ、−６≦Ｒｓｋ≦０．２、または、２．２≦Ｒｋｕ≦２．８の範囲でスパングルムラを防止できることがわかった。
FIG. 2 shows a three-dimensional roughness profile of the surface of the steel plate sample before plating. In FIG. 2A, the unevenness | corrugation of the steel plate surface of the cold rolling completion state of the sample which the spangle nonuniformity generate | occur | produced after hot-dip galvanizing is shown. In FIG. 2A, straight or curved convex portions (hereinafter referred to as linear convex portions) appearing on the rolling direction line intersecting at an angle of 120 degrees to 60 degrees with the rolling direction line are indicated by arrows. On the other hand, in FIG. 2B, the convex part which cross | intersects on the line of a rolling direction was not seen by the unevenness | corrugation on the steel plate surface. When the hot dip galvanizing steel plate of FIG. 2B was hot dip galvanized, spangle unevenness did not occur.
In the rolling condition of FIG. 2A where the line-shaped convex part where spangle unevenness has occurred is formed, in the cold tandem rolling as shown in FIG. 3B, the convex part of the uneven part of the roll surface bites into the steel sheet surface and causes relative slip. It turned out that the convex part on a line is formed in the direction which cross | intersects a rolling direction.
The sample after the cold tandem rolling in which no line convex part is seen does not show spangle unevenness on the surface even after hot-dip galvanizing. In addition, regarding the form, distribution, height, and length of the corresponding convex portion on the line, no change corresponding to the portion where spangle unevenness occurred was observed. In other words, it has been clarified that the unevenness of the transferred roughness does not cause the spangle unevenness and the occurrence of the spangle unevenness is determined by the overall roughness.
When the surface roughness parameters R sk (distortion degree) and R ku (degree of sharpness) are arranged based on the presence or absence of the convex portion on the line, −6 ≦ R sk ≦ 0.2 or 2.2 ≦ R ku ≦ 2. It was found that spangle unevenness can be prevented in the range of 8.
本発明の粗面の測定は、ＪＩＳ Ｂ ０６０１：２０１３に従って行った。 The measurement of the rough surface of the present invention was performed according to JIS B 0601: 2013.
すなわち図２Ａで示される線上凸部が見られない図２Ｂの条件は、冷間圧延の最終スタンドで、ロール表面の凹凸の凸部が鋼板表面に食い込み相対滑りを起こさない条件である。冷間タンデム圧延において、鋼板表面の凹凸の大きさの分布が十点平均粗さ（Ｒｚjis）が１〜５μｍであり、中心線平均粗さ（Ｒａ）が、０．１〜１．５μｍである冷延鋼板を、冷間タンデム圧延の最終スタンドに供給し、最終スタンドを、圧延荷重を０ｋＮ/ｍｍ超〜４．０ｋＮ/ｍｍ以下でダルロールで圧延して鋼板を得る製造方法であることがわかった。圧延荷重が０ｋＮ/ｍｍであるということはすなわち圧延しないということであり、スパングルムラを防止することができず、０ｋＮ/ｍｍ超である必要があるが０近傍では条件設定のバラツキが大きいので０．１ｋＮ/ｍｍ〜４．０ｋＮ/ｍｍが好ましく、１．０ｋＮ/ｍｍ〜４．０ｋＮ/ｍｍがさらに好ましい。 That is, the condition of FIG. 2B in which the linear convex part shown in FIG. 2A is not seen is a condition in which the convex part of the irregularities on the roll surface bites into the steel sheet surface and does not cause relative slip in the final stand of cold rolling. In the cold tandem rolling, the distribution of the size of the irregularities on the surface of the steel sheet is 10-point average roughness (R zjis ) of 1 to 5 μm, and the center line average roughness (Ra) is 0.1 to 1.5 μm. A certain cold-rolled steel sheet is supplied to a final stand of cold tandem rolling, and the final stand is rolled by a dull roll with a rolling load of more than 0 kN / mm to 4.0 kN / mm to obtain a steel sheet. all right. That the rolling load is 0 kN / mm means that rolling is not performed, and spangle unevenness cannot be prevented and needs to be more than 0 kN / mm. 0.1 kN / mm to 4.0 kN / mm is preferable, and 1.0 kN / mm to 4.0 kN / mm is more preferable.
以下に実施例を示して本発明を具体的に説明する。ただし、本発明はこれらに限定されない。 The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.
（１）用材
低炭素鋼材（ＳＧＣＣ相当、ＪＩＳ ＺＧ３３０２）を、３．０ｍｍから仕上げ厚０．７８ｍｍにまで以下の条件で冷間圧延した。
冷間タンデム圧延機を用いた。詳細には、第１から４スタンドはワークロール径６００ｍｍで、ロール表面粗さは中心線平均粗さ（Ｒａ）が、０．３μｍ（円筒研磨）であった。最終スタンドである第５スタンドはワークロール径３８０ｍｍで、ロール表面粗さは中心線平均粗さ（Ｒａ）が、２．２μｍ（放電ダル加工）であった。
鋼板表面の凹凸を３種類に変えて用意し、ラボ圧延機にて冷間タンデム圧延機の最終スタンドを模擬した冷間圧延機で圧延荷重、圧下率を変更して冷間圧延実験を実施したのち、焼鈍、亜鉛系めっきを行った。
鋼板表面の凹凸は、
１）十点平均粗さ（Ｒｚjis）が０．８μｍであり、中心線平均粗さ（Ｒａ）が、０．１μｍである鋼板を溶融亜鉛系めっき用鋼板を用いた場合の結果を図４に示した。
２）十点平均粗さ（Ｒｚjis）が１〜５μｍであり、中心線平均粗さ（Ｒａ）が、０．１〜１．５μｍである鋼板を溶融亜鉛系めっき用鋼板を用いた場合の結果を図５に示した。
３）十点平均粗さ（Ｒｚjis）が５μｍであり、中心線平均粗さ（Ｒａ）が、１．８μｍである鋼板を溶融亜鉛系めっき用鋼板に用いた場合の結果を図６に示した。
(1) Material Low carbon steel material (SGCC equivalent, JIS ZG3302) was cold-rolled from 3.0 mm to a finished thickness of 0.78 mm under the following conditions.
A cold tandem rolling mill was used. Specifically, each of the first to fourth stands had a work roll diameter of 600 mm, and the roll surface roughness had a center line average roughness (Ra) of 0.3 μm (cylindrical polishing). The fifth stand, which is the final stand, had a work roll diameter of 380 mm, and the roll surface roughness was centerline average roughness (Ra) of 2.2 μm (discharge dull processing).
We prepared three types of unevenness on the surface of the steel sheet, and performed a cold rolling experiment by changing the rolling load and rolling reduction with a cold rolling mill that simulated the final stand of a cold tandem rolling mill with a laboratory rolling mill. After that, annealing and zinc plating were performed.
The unevenness of the steel sheet surface is
1) FIG. 4 shows the results when a hot-dip galvanized steel sheet is used for a steel sheet having a ten-point average roughness (R zjis ) of 0.8 μm and a center line average roughness (Ra) of 0.1 μm. It was shown to.
2) When a hot-dip galvanized steel sheet is used for a steel sheet having a ten-point average roughness (R zjis ) of 1 to 5 μm and a centerline average roughness (Ra) of 0.1 to 1.5 μm. The results are shown in FIG.
3) FIG. 6 shows the results when a steel sheet having a ten-point average roughness (R zjis ) of 5 μm and a centerline average roughness (Ra) of 1.8 μm is used for a hot dip galvanizing steel sheet. It was.
焼鈍は８００℃で１２０秒、溶融亜鉛系めっきは、浴温４６０℃のＺｎ−０．１３質量％Ａｌめっき浴、または４３．４質量％Ｚｎ−５５質量％Ａｌ＋１．６質量％Ｓｉの合金めっきを用いてに３秒浸し、ワイピングでめっき付着量が４５ｇ／ｍ2となるよう調整し、５００℃の温度で合金化処理した。 Annealing is 800 ° C. for 120 seconds, and hot dip galvanizing is a Zn-0.13 mass% Al plating bath with a bath temperature of 460 ° C., or an alloy plating of 43.4 mass% Zn-55 mass% Al + 1.6 mass% Si. Was immersed for 3 seconds, adjusted to a plating adhesion of 45 g / m 2 by wiping, and alloyed at a temperature of 500 ° C.
図４〜６に示す○：スパングルムラなしと、×：スパングルムラありの評価は、目視にて行った。 Evaluations of ○: no spangle unevenness and x: spangle unevenness shown in FIGS. 4 to 6 were made visually.
１ 熱延原板（鋼帯）
２ 最終冷延板
３ 高粗度ロール
４ ブライト・ロール
５ 最終スタンドのダル仕上げ用ロール
1 Hot rolled sheet metal (steel strip)
2 Final cold rolled sheet 3 High roughness roll 4 Bright roll 5 Final stand roll for dull finish
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| JPS58103905A (en) * | 1981-12-14 | 1983-06-21 | Kawasaki Steel Corp | Controlling method for surface roughness of cold rolled thin steel sheet |
| JP3271749B2 (en) * | 1997-09-24 | 2002-04-08 | 川崎製鉄株式会社 | Hot-dip galvanized steel sheet excellent in appearance and method for producing the same |
| JPH11200005A (en) * | 1998-01-20 | 1999-07-27 | Nkk Corp | Thin coating galvanized steel sheet excellent in brightness after coating and original sheet thereof |
| JP2001038403A (en) * | 1999-07-28 | 2001-02-13 | Nisshin Steel Co Ltd | Method of manufacturing thin sheet for shadow mask |
| JP2001288549A (en) * | 2000-03-31 | 2001-10-19 | Kawasaki Steel Corp | Manufacturing method of cold rolled steel plate excellent in press forming property and plated steel plate |
| JP4506357B2 (en) * | 2004-08-27 | 2010-07-21 | 住友金属工業株式会社 | Galvanized steel sheet and its manufacturing method |
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2013
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111527231A (en) * | 2017-12-26 | 2020-08-11 | Posco公司 | Zinc alloy plated steel material having excellent corrosion resistance and surface smoothness, and method for producing same |
| CN111527231B (en) * | 2017-12-26 | 2022-07-08 | Posco公司 | Zinc alloy plated steel material having excellent corrosion resistance and surface smoothness, and method for producing same |
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| JP2015036426A (en) | 2015-02-23 |
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