201114946 六、發明說明： t明戶斤屬戈^老^軒々真^^ 3 發明領域 本發明係有關一種高耐蝕性Zn_Al_Mg系熔融鍍敷鋼 板’其可以作為例如家電用或汽車用、建材用的铜板應用 在各種用途。特別是有關一種外觀優良的Zn-Al-Mg系溶融 鍍敷鋼板與其製造方法。 本申請案係基於2009年6月30曰在曰本提出申請的特 願2009-156018號主張優先權’將其内容引用至此。 【先前技術3 發明背景201114946 VI. Description of the invention: t ming jin gen ge ^ ^ ^ 々 々 ^ ^ ^ 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 The copper plate is used in a variety of applications. In particular, it relates to a Zn-Al-Mg-based molten plated steel sheet excellent in appearance and a method for producing the same. The present application claims priority based on Japanese Patent Application No. 2009-156018, filed on Jun. 30, 2009, the entire content of [Prior Art 3 Background of the Invention]
Zn-Al-Mg系熔融鑛敷鋼板因為耐蝕性優異，近年來其 使用量正在增加。但是，因為採用多元系合金之熔融鍍敷 的凝固反應複雜，在Zn-Al-Mg系熔融鍍敷中容易引起各種 外觀不良。過去以來，為使Zn-Al-Mg系熔融鍍敷鋼板之外 觀良好而提出過各種技術。 例如’採用三元共晶點附近的鑛浴組成之情形，錢層 之金屬組織中會有容易變色且表面外觀劣化的ZniiMg2* 的相發生局部結晶之問題。 為解決該問題’專利文獻1中揭示了一種技術，係藉由 控制鍍浴之浴溫在470°C以上且鍍敷後的冷卻速度在〇.5。匚/ 秒以上’並在[Al/Zn/Zr^Mg的三元共晶組織]之基體中形成 具有[初晶A1相]或混雜有[初晶A1]與[Zn單相]之金屬組織的 鍍層’以抑制容易變色且表面外觀劣化的ZnnMg2系的相發 201114946 生局部結晶。 專利文獻2中亦揭示了，若令鍍層中的Al/Zn/MgZn合金 之二元共晶組織之結晶的6〇%以上達到圓相當徑ι〇〇μίη以 上’就會獲得不易變色的組織。 另外’專利文獻2中亦揭示了藉由在鍍層中含有具特定 晶格面之金屬間化合物，令Α1相的枝晶一次臂在< 110>方 向大量成長，以使Α1相的結晶獲得微細且均勻的等軸晶。 其結果’就沒有因Α1相的枝晶之不均勻成長造成的鍍敷凹 凸’會獲得平滑外觀者揭示於專利文獻2。The Zn-Al-Mg-based molten ore-coated steel sheet is used in recent years because of its excellent corrosion resistance. However, since the solidification reaction by the molten plating using the multicomponent alloy is complicated, various appearance defects are likely to occur in the Zn-Al-Mg-based melt plating. In the past, various techniques have been proposed for making the Zn-Al-Mg-based hot-dip coated steel sheet look good. For example, in the case of using a mineral bath near the ternary eutectic point, there is a problem that the phase of ZniiMg2* which is easily discolored and whose surface appearance is deteriorated in the metal structure of the money layer. In order to solve this problem, Patent Document 1 discloses a technique in which the bath temperature of the plating bath is controlled to be 470 ° C or higher and the cooling rate after plating is 〇.5.匚 / sec or more 'and forming a metal structure with [primary crystal A1 phase] or mixed with [primary crystal A1] and [Zn single phase] in the matrix of [Al/Zn/Zr^Mg ternary eutectic structure] The coating of the ZnnMg2 system, which is easy to discolor and deteriorates in surface appearance, is partially crystallized in 201114946. Further, in Patent Document 2, it is revealed that a structure in which the crystal of the binary eutectic structure of the Al/Zn/MgZn alloy in the plating layer is 6% or more of a circle equivalent to a circle equivalent diameter ι〇〇μίη is obtained. Further, in Patent Document 2, it is also disclosed that the intermetallic compound having a specific lattice plane is contained in the plating layer, so that the dendrite primary arm of the Α1 phase grows in a large amount in the <110> direction, so that the crystallization of the Α1 phase is fine. And uniform equiaxed crystals. As a result, there is no plating appearance due to uneven growth of the dendrites of the Α phase, and a smooth appearance is obtained in Patent Document 2.
Zn-Al-Mg系熔融鍍敷鋼板中亦有區別於如上所述的外 觀不良之梨皮的問題。Zn-Al-Mg系熔融鍍敷鋼板之表面係 如第1圖所示地’混雜有不定形狀的白色部與圓形狀的光澤 P呈現出微細散佈的如同梨皮狀的表面外觀。較詳細地 5兒’如第2圖所示，白色部係露出鍍敷表面的A1相之枝晶， 光澤部係三元共晶組織。 因為s玄梨皮一般並不美麗，所以即使鍍敷表面沒有如 上所述的外觀不良(鍍敷的凹凸），在進一步要求美麗外觀之 情形，依然必須改善該梨皮之狀態。 車又佳的梨皮係上述的白色部與光澤部分別微細分散 所明表面之纹理具有微細的外觀，且平滑的光澤部多。 4皮的光澤部係由三元共晶構成與白色部相比具有平滑 的表面狀態。 仁疋’梨皮之狀態在每個製品中差異較大。特別是如 果錢數附著量多’每個白色部之面積與每個光澤部之面積 201114946 就會增大，有不美麗狀態之梨皮增加的傾向。 在習知技術中，難以安定地形成紋理微細的良好梨皮 之鑛敷表面。 先前技術文獻 專利文獻 專利文獻1:日本國專利第3179401號公報 專利文獻2:曰本國特開2006-283155號公報 非專利文獻 非專利文獻1 :鐵與鋼，第81卷，1995年，第6號，ρ·643 【發明内容】 發明概要 發明欲解決之課題 於是，本發明中，目的係在Zn-Al-Mg系熔融鑛敷鋼板 中，明確得知必要的熔融鍍層之條件，獲得紋理微細，而 且平滑光澤部多的梨皮，同時安定地製造具有這種梨皮之 溶融鑛敷鋼板。 用以欲解決課題之手段 本發明人等製作梨皮之狀態不同的Zn-Al-Mg系熔融鍍 敷鋼板且調查其特徵。其結果得知，當每單位面積的白色 部之個數多時，以及光澤部的面積比例大時，就有獲得良 好梨皮的傾向。特別是發現如果白色部的個數增多，梨皮 的狀態就變良好。The Zn-Al-Mg-based hot-dip coated steel sheet also has a problem of being distinguished from the poor-looking pear skin as described above. The surface of the Zn-Al-Mg-based hot-dip coated steel sheet is as shown in Fig. 1 'The white portion mixed with the indefinite shape and the rounded luster P exhibit a finely dispersed surface appearance like a pear-like shape. In more detail, as shown in Fig. 2, the white portion exposes the dendrites of the A1 phase on the plated surface, and the gloss portion is a ternary eutectic structure. Since the sacred pear skin is generally not beautiful, even if the plating surface does not have a poor appearance (plated unevenness) as described above, it is necessary to improve the state of the pear skin in the case where a beautiful appearance is further required. The white pear and the glossy portion of the pear skin are finely dispersed, respectively. The texture of the surface has a fine appearance and a smooth glossy portion. The gloss portion of the skin is composed of a ternary eutectic having a smooth surface state as compared with the white portion. The state of Ren's skin is quite different in each product. In particular, if the amount of money is attached, the area of each white portion and the area of each gloss portion will increase, and there is a tendency for the pear skin which is not in a beautiful state to increase. In the prior art, it is difficult to stably form a mineralized surface of a finely textured fine pear skin. CITATION LIST Patent Literature Patent Literature 1: Japanese Patent No. 3179401 Patent Document 2: Japanese Laid-Open Patent Publication No. 2006-283155 Non-Patent Literature Non-Patent Document 1: Iron and Steel, Vol. 81, 1995, No. 6 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION In the present invention, in the Zn-Al-Mg-based molten ore-coated steel sheet, the conditions of the necessary molten plating are clearly known, and the texture is fine. Moreover, the pear skin having a smooth luster portion is smooth, and the molten ore steel sheet having the pear skin is stably produced. Means for Solving the Problem The inventors of the present invention produced a Zn-Al-Mg-based hot-dip coated steel sheet having different states of pear skin and investigated the characteristics thereof. As a result, it has been found that when the number of white portions per unit area is large and the area ratio of the glossy portion is large, good pear skin tends to be obtained. In particular, it has been found that if the number of white portions increases, the state of the pear skin becomes good.
於是，本發明人等就構成鋼板表面之白色部的A1相之 方位及樹枝結晶（枝晶結晶）之結構作了調查。首先，利用X 201114946 射線繞射(XRD)測定就A1相之方位進行調查之結果，發現在 呈現良好梨皮的鋼板中’與不呈現良好梨皮之鋼板相比， (200)面油板表面平行的晶㈣，（lu)面與鋼板表面平行 的晶粒少。 另外，利用EBSD法或掃描電子顯微鏡(SEM)分析_ 的樹枝結晶之結構的結果，發現在平行於呈現良好梨皮之 鋼板的鍍層表面的面中，類似十字形狀的樹枝結晶多，類 似六角形狀的樹枝結晶少。 本發明人等經過如上所述的檢討，完成了本發明。本 發明之要旨係如下所述。 (1) 關於本發明之一態樣的Zn-Al-Mg系炫融鐘敷鋼 板係具備鋼板與熔融鍍層，該熔融鍍層含有4質量％以上22 質量°/〇以下的A1與1質量％以上5質量％以下的Mg，且剩餘部 分含Zn及不可避免的雜質；平行於前述熔融鍍層表面的前 述熔融鍍層之截面中，A1相的（200)面之X射線繞射強度 1(200)與A1相的（111)面之X射線繞射強度1(111)之比，即繞 射強度比1(200)/1(111)在0.8以上。 (2) 在上述（1)記載的Zn-Al-Mg系炫·融鍵敷鋼板中’前 述熔融鍍層亦可含有0.0001質量％以上2.0質量％以下的Si。 (3) 在上述（1)或（2)記載的Zn-Al-Mg系熔融鍍敷鋼板 中，前述熔融鍍層亦可以單獨或複合形式進一步含有 0.0001 質量％以上〇.質量％以下的Fe、Sb、Pb、Sn、Ca、Co、 Μη、P ' B、Bi、Cr、3族元素、REM、Hf、不可避免的雜 201114946 (4) 在上述（1)或(2)記載的Zn-Al-Mg系熔融鍍敷鋼板 中’前述熔融鍍層亦可以單獨或複合形式進一步含有 〇'〇〇〇1質量％以上〇_5質量％以下的Ni、Ti、Zr、Sr。 (5) 在上述（1)或(2)記載的Zn-Al-Mg系熔融鍍敷鋼板 中’平行於前述熔融鍍層表面的前述熔融鍍層之截面中， A1相的類似十字形狀之樹枝結晶的面積率亦可在前述熔融 鍍層總截面積的5%以上。 (6) 在上述（1)或（2)記載的Zn-Al-Mg系熔融鍍敷鋼板 中’前述熔融鍍層表面的白色部個數在1〇〇個/cm2以上，而 &述炫融鍍層表面的光澤部面積率在前述溶融鐘層總表 面積的94。/„以上亦可。 (7) 在上述（1)或(2)記載的Zn-Al-Mg系熔融鍍敷鋼板 ’别述熔融鍍層中每單面的鍍敷附著量亦可為50〜 3〇〇g/m2 〇 (8) 在Zn_Al-Mg系熔融鍍敷鋼板之製造方法中，其係 製造如上述⑴或(2)記載的Zn-Al-Mg系熔融鍍敷鋼板者，即 將擦核1的前述熔融鍍層之溫度係超過Zn-Al-Mg系熔融鍍敷 金屬之凝固開始溫度，剛擦拭後的前述熔融鍍層之溫度係 車父前述Zn-Al-Mg系熔融鍍敷金屬之凝固開始溫度低1 〇°C以 下。 (9) 在上述（8)記載的Zn-Al-Mg系、熔融鑛敷鋼板之製 造方法中，其中擦拭後，亦可wl〇〇C/sec以下的冷卻速度進 行冷卻直到前述Zn-Al-Mg系熔融鍍敷金屬的前述A1相之凝 固結束溫度為止。 3- 7 201114946 (10)在上述（8)或（9)記載的Zn-Al-Mg系熔融鍍敷鋼板 之製造方法中，前述熔融鍍層中每單面的鍍敷附著量亦可 控制在50〜300g/m2。 發明效果 若依據本發明’可以令每個製品之品質沒有差異且安 定地提供一種Zn-Al-Mg系熔融鍍敷鋼板，其紋理微細，而 且具有平滑部分多的梨皮之優良外觀。 圖式簡單說明 第1圖係使用照片的Zn-Al-Mg系炼融鍍敷鋼板表面之 梨皮的說明圖。 第2圖係利用了電子顯微鏡照片之梨皮的說明圖。 第3圖係利用了電子顯微鏡照片之梨皮的說明圖。 第4圖係梨皮表面之白色部個數及光澤部面積與梨皮 評分之關係的示意圖。 第5圖係平行於溶融鍍敷鋼板之表面的面利用xrd測 疋獲得之繞射圖案之一例的示意圖。 第6圖係鍍層中繞射強度比1(2〇〇)/1(111)與鍍敷鋼板表 面的梨皮評分之關係的示意圖。 第7A圖係利用[BSD法測定鑛層之結果所得之圖像之 一例。 第7B圖係第7A圖所示之圖像經2值化以使(2〇〇)面方位 的邛刀成為白色的圖像之一例。 第8圖係鍍層表面類似十字形狀的樹枝結晶之面積率 與鍍數鋼板表面之梨皮評分之_的示意圓。 201114946 第9圖係錢層中繞射強度比1(200)/1(111)及類似十字形 的樹枝結晶之面積率與梨皮評分之關係的示意圖。 【實施冷式】 用以實施發明之形態 本發明之一實施形態中，熔融鍍浴係在熔融Zn浴中添 加A1 ’且進一步依需要添加有Si、Mg之一種或兩種的鍍浴。 本貫施开^態中，限定A1之含量在4質量％以上22質量％ 以下之理由，是因為不足4質量％的八丨’提高耐蝕性的效果 就不充分，在22質量％以上，提高耐蝕性的效果就會飽和。 另外，A1的含量不足4質量％時，因A1相不會以初晶形式結 晶’就不會引起由初晶A1相產生的梨皮之問題。 這樣，A1之含量不足4質量％時，提高耐蝕性之效果就 不充分。另外’ A1之含量若超過22質量％，提高耐蝕性的 效果就會飽和。因此’ A1之含量為4質量％以上22質量％以 下。為進一步提高耐触性，A1之含量以5質量。/〇以上為佳， 10質量％以上較佳。另外，為降低鍍浴之熔點，同時提高 鍍敷密合性’A1之含量以20質量％以下為佳，15質量％以下 較佳。Then, the inventors of the present invention investigated the orientation of the A1 phase and the structure of dendritic crystals (dendritic crystals) constituting the white portion of the surface of the steel sheet. First, using the X 201114946 ray diffraction (XRD) measurement to investigate the orientation of the A1 phase, it was found that in the steel sheet exhibiting good pear skin, the surface of the (200) oil slab surface was compared with the steel sheet which did not exhibit good pear skin. Parallel crystals (4), (lu) planes are less parallel to the surface of the steel sheet. Further, as a result of analyzing the structure of the crystal of the dendrites by the EBSD method or a scanning electron microscope (SEM), it was found that in the surface parallel to the surface of the plating layer of the steel sheet exhibiting a good pear skin, the branches resembling a cross shape crystallized more like a hexagonal shape. The branches are less crystalline. The present inventors completed the present invention by reviewing as described above. The gist of the present invention is as follows. (1) The Zn-Al-Mg system of the present invention is provided with a steel sheet and a molten plating layer, and the molten plating layer contains A1 and 1% by mass or more of 4% by mass or more and 22% by mass or less. 5 mass% or less of Mg, and the remainder contains Zn and unavoidable impurities; in the cross section of the molten plating layer parallel to the surface of the molten plating layer, the X-ray diffraction intensity (200) of the (200) plane of the A1 phase is The ratio of the X-ray diffraction intensity 1 (111) of the (111) plane of the A1 phase, that is, the diffraction intensity ratio of 1 (200) / 1 (111) is 0.8 or more. (2) In the Zn-Al-Mg-based dahnea-bonded steel sheet according to the above (1), the molten plating layer may contain 0.0001% by mass or more and 2.0% by mass or less of Si. (3) In the Zn-Al-Mg-based hot-dip-plated steel sheet according to the above-mentioned (1) or (2), the melt-plated layer may further contain 0.0001% by mass or more and 质量.% by mass or less of Fe or Sb. , Pb, Sn, Ca, Co, Μη, P' B, Bi, Cr, Group 3 element, REM, Hf, unavoidable miscellaneous 201114946 (4) Zn-Al- described in (1) or (2) above In the Mg-based hot-melt-plated steel sheet, the molten-plated layer may further contain Ni, Ti, Zr, and Sr in an amount of 〇 〇〇〇 1% by mass or more 〇 5% by mass or less, in a single or composite form. (5) In the Zn-Al-Mg-based hot-dip coated steel sheet according to the above (1) or (2), in a cross section of the molten plating layer parallel to the surface of the molten plating layer, a cross-shaped branch crystal of the A1 phase is crystallized. The area ratio may be 5% or more of the total cross-sectional area of the molten plating layer. (6) In the Zn-Al-Mg-based hot-melt-plated steel sheet according to the above (1) or (2), the number of white portions on the surface of the molten plating layer is 1〇〇/cm2 or more, and & The gloss area ratio of the surface of the plating layer was 94 of the total surface area of the aforementioned molten clock layer. (7) In the Zn-Al-Mg-based hot-dip coated steel sheet described in the above (1) or (2), the amount of plating per one side of the molten plating layer may be 50 to 3 〇〇g/m2 〇(8) In the method for producing a Zn_Al-Mg-based molten-plated steel sheet, the Zn-Al-Mg-based hot-dip-plated steel sheet according to the above (1) or (2) is produced. The temperature of the molten plating layer of 1 exceeds the solidification starting temperature of the Zn-Al-Mg-based molten plating metal, and the temperature of the molten plating layer immediately after wiping is the solidification of the Zn-Al-Mg-based molten plating metal by the father. (9) In the method for producing a Zn-Al-Mg-based or molten ore-coated steel sheet according to the above (8), after the wiping, the cooling rate may be less than or equal to C/sec. The cooling is performed until the solidification end temperature of the A1 phase of the Zn-Al-Mg-based hot-melt-plated metal. 3- 7 201114946 (10) The Zn-Al-Mg-based hot-dip plating described in the above (8) or (9) In the method for producing a coated steel sheet, the amount of plating per one surface of the molten plating layer may be controlled to 50 to 300 g/m 2 . There is no difference in the quality of the products, and a Zn-Al-Mg-based hot-dip coated steel sheet is provided with a fine texture and a fine appearance of a smooth portion of the pear skin. The drawing is simple. -Al-Mg is an explanatory view of the pear skin on the surface of the smelting-plated steel sheet. Fig. 2 is an explanatory view of a pear skin using an electron microscope photograph. Fig. 3 is an explanatory view of a pear skin using an electron microscope photograph. Fig. 4 is a schematic diagram showing the relationship between the number of white portions on the surface of the pear skin and the area of the glossy portion and the pear skin score. Fig. 5 is an example of a diffraction pattern obtained by xrd measurement parallel to the surface of the surface of the molten plated steel sheet. Figure 6 is a schematic diagram showing the relationship between the diffraction intensity ratio of 1 (2 〇〇) / 1 (111) and the pear skin score on the surface of the plated steel sheet. Figure 7A shows the determination of the ore layer by the BSD method. An example of the image obtained as a result. Fig. 7B is an example of an image in which the image shown in Fig. 7A is binarized so that the (2〇〇) plane orientation is white. The area ratio of the crystals of the cross-shaped branches and the number of plated steel plates A schematic circle of the pear skin score. 201114946 Fig. 9 is a schematic diagram showing the relationship between the area ratio of the diffraction intensity ratio of 1 (200)/1 (111) and the cross-shaped tree branches in the money layer and the pear skin score. In the embodiment of the present invention, the molten plating bath is a plating bath in which one or two of Si and Mg are further added to the molten Zn bath. In the case of the open state, the reason why the content of A1 is 4% by mass or more and 22% by mass or less is limited because the effect of improving the corrosion resistance of the gossip of less than 4% by mass is insufficient, and the corrosion resistance is improved by 22% by mass or more. The effect will be saturated. On the other hand, when the content of A1 is less than 4% by mass, the A1 phase does not crystallize in the form of primary crystals, and the problem of the pear skin produced by the primary crystal A1 phase is not caused. Thus, when the content of A1 is less than 4% by mass, the effect of improving the corrosion resistance is insufficient. Further, if the content of A1 exceeds 22% by mass, the effect of improving corrosion resistance is saturated. Therefore, the content of 'A1' is 4% by mass or more and 22% by mass or less. In order to further improve the contact resistance, the content of A1 is 5 mass. / 〇 or more is preferred, and 10% by mass or more is preferred. Further, in order to lower the melting point of the plating bath, the content of the plating adhesion 'A1 is preferably 20% by mass or less, preferably 15% by mass or less.
Mg之含量不足1質量％時，提高对#性的效果就會不充 分。另外’Mg之含量若超過5質量％，鍍層就會變脆且密合 性降低。因此’ Mg之含量在1質量％以上5質量％以下。為 進一步提高耐蚀性’ Mg之含量以2質量％以上為佳，3質量 %以上較佳。此外，為進一步提高鍍層之密合性，Mg含量 以4.5質量％以下為佳，4質量％以下較佳。 9 201114946 在不添加A1及Mg以外之元素時，其剩餘部分係由Zn及 不可避免的雜質構成。 此外，亦可形成上述的基本組成中添加有0.0001質量％ 以上2質量％以下的Si之鍍層。含有Si係為提高耐蝕性，不 過即使添加2質量％以上的Si，提高耐#性的效果也會飽和。 Si之下限濃度設在0.0001質量％的理由是因為Si在0.0001質 量％以下之濃度時，工業上的濃度會難以控制。 鍍浴中，在上述成分(Zn、Al、Mg、Si)以外亦可以單 獨或者複合形式含有〇. 〇 〇 〇 1質量％以上〇. 5質量％以下的F e、 Sb、Pb、Sn以及不可避免的雜質。另外，在鍍浴中以單獨 或者複合形式含有0.0001質量％以上0.5質量％以下的Ca、 Co、Μη、P、B、Bi、Cr、3族元素、REM、Hf亦不會損害 本發明之效果，依其含量有時還會有進一步改善耐蝕性等 良好情形。上述成分(Fe、Sb、Pb、Sn、不可避免的雜質、 Ca、Co、Μη、P、B、Bi、Cr、3族元素、REM、Hf)之下 限濃度設在0.0001質量％之理由，是因為該等之成分在 0.0001質量％以下的濃度時，工業上的濃度會難以控制。 此外，鍍浴中亦可以單獨或者複合形式含有0.0001質 量％以上0.5質量％以下的Ni、Ti、Zr、Sr。該等之元素的任 一種均會在A1之間結晶成金屬間化合物，有提高表面平滑 性之效果。但是，各自的元素(Ni、Ti、Zr、Sr)若超過上限 之含量，鍍敷後的外觀就變粗糙，有時會產生外觀不良。 Ni、Ti、Zr、Sr之下限濃度設在0.0001質量％的理由是因為 該等之成分在0.0001質量％以下之濃度時，工業上的濃度會 10 201114946 難以控制。 本發明中’A1相係在鍍層中具有明確的界限且類似島 狀或枝晶狀的相。A1相相當於例如Zn-Al-Mg的三元系平衡 狀態圖中在高溫下的「A1相」（固溶Zn的A1固溶體）。該高 溫下的A1相係依據鍍浴的Ai濃度固溶的〜量會不同。該高 溫下的A1相係分離常溫下微細的Ai相與微細的zn相，在常 溫下所見的島狀或枝晶狀之形狀可以看作保留有高溫下之 A1相的構架者。來自該高溫下的八丨相（稱為A1初晶）且形狀上 保留A1相之構架的相在本說明書中稱為ai相。 A1相在Al-Zn-Mg之3元系、Al-Zn-Mg-Si之4元系中，依 據鍍浴的合金濃度固溶的元素量會不同，在常溫下的相形 態亦不同。不過在任一種情形下，A1相都保留來自A1初晶 的構条’因在顯微鏡觀察下可以明確區分，故在本說明壹 中將其稱為A1相。 此處，不好的梨皮之狀態如第丨圖所示，係不定形的白 色部與圓形狀之光澤部發生混雜’在表面呈現散佈的如同 梨皮狀的表面外觀之狀態。在該狀態下，白色部大，而且 光澤部之面積率低。因而，可以用白色部之尺寸與該白色 部占鍍敷表面之比例來評估梨皮外觀之程度。在本實施形 態中，熔融鍍層之表面以面積率計含有94%以上之光澤部， 且白色部之個數在Η)0個/cm2以上是合適的。這樣處理就°可 以提供外觀良好的Zn-Al-Mg系炫融鍍敷鋼板。在任意的鋼 板中’較詳細地說，如第2、3圖所示，白色部為鍛敷表面 露出的A1相之枝晶發生聚集之部分，光澤部騎敷表面用 11 201114946 二元共晶組織所覆蓋的部分。本發明人等觀察的鍍敷表面 A1相之枝晶露出的部分係長邊〜1〇(^m左右的尺寸，枝 晶的枝厚度為5〜50μιη左右的尺寸。 本說明書所述梨皮的白色部係鍍敷表面露出的Α1相之 枝晶發生聚集的部分。另外，評估梨皮的白色部數量之際， 係將目視上呈一體化的該梨皮之白色部當作一個白色部評 估。 此處，三元共晶係Zn-Al-Mg的3元系，或者Zn-Al-Mg-Si 的4元系之鍍敷鋼板中，上述成分濃度範圍之鍍層發生最終 凝固之際生成的凝固組織。 本發明人等透過改變鍍敷組成或鍍敷後之冷卻速度等 之條件來製作大量的Zn-Al-Mg系熔融鍍敷鋼板，從其中採 集梨皮之狀態不同的試料並調查其特徵。 依據所採集之試料的梨皮狀態，從合適的狀態依序賦 予各試料1〜6的評分（梨皮評分）。再者，將可以判定為「良 好」的界限之梨皮設定為基準的評分3。調查各試料中的光 澤部面積率與白色部個數的關係。將其結果示於第4圖。 由第4圖得知，若白色部(含叫目之部分）的個數在⑽ 個W以上，而且光澤部（含三元共晶之部分）的面積率在 辦以上（不含1〇〇%)，Zn-A1_M#炫融錢敷鋼板就傾向於 呈現評分3以下的良好梨皮。若白色部微細分散，白色部之 個數就增多。另外，若光澤部之面積率升高，白色部之面 積率就減小，而，從每單位面積的白色部之個數與光澤 部之面積率，可以表現白色部微細且平滑的光澤部多的梨When the content of Mg is less than 1% by mass, the effect of improving the properties of # may not be sufficient. Further, when the content of "Mg exceeds 5% by mass, the plating layer becomes brittle and the adhesion is lowered. Therefore, the content of Mg is 1% by mass or more and 5% by mass or less. In order to further improve the corrosion resistance, the content of Mg is preferably 2% by mass or more, and more preferably 3% by mass or more. Further, in order to further improve the adhesion of the plating layer, the Mg content is preferably 4.5% by mass or less, and preferably 4% by mass or less. 9 201114946 When no elements other than A1 and Mg are added, the remainder is composed of Zn and unavoidable impurities. Further, a plating layer in which 0.0001% by mass or more and 2% by mass or less of Si is added to the above basic composition may be formed. When the Si-based system is used to improve the corrosion resistance, even if 2% by mass or more of Si is added, the effect of improving the resistance is saturated. The reason why the lower limit concentration of Si is set to 0.0001% by mass is because the concentration of Si is not more than 0.0001% by mass, and the industrial concentration is difficult to control. In the plating bath, in addition to the above components (Zn, Al, Mg, Si), 〇. 〇〇〇1% by mass or more 〇. 5 mass% or less of F e, Sb, Pb, Sn, and not may be contained. Avoid impurities. Further, the inclusion of 0.0001% by mass or more and 0.5% by mass or less of Ca, Co, Μη, P, B, Bi, Cr, Group 3 elements, REM, and Hf in the plating bath alone or in combination does not impair the effects of the present invention. Depending on its content, there are occasions such good conditions that further improve corrosion resistance. The reason why the lower limit concentration of the above components (Fe, Sb, Pb, Sn, unavoidable impurities, Ca, Co, Μη, P, B, Bi, Cr, Group 3 elements, REM, Hf) is 0.0001% by mass is Since the components are at a concentration of 0.0001% by mass or less, the industrial concentration is difficult to control. Further, in the plating bath, Ni, Ti, Zr, and Sr may be contained in an amount of 0.0001% by mass or more and 0.5% by mass or less, either singly or in combination. Any of these elements crystallizes into an intermetallic compound between A1, which has an effect of improving surface smoothness. However, if the respective elements (Ni, Ti, Zr, and Sr) exceed the upper limit, the appearance after plating becomes rough, and appearance defects may occur. The reason why the lower limit concentration of Ni, Ti, Zr, and Sr is set to 0.0001% by mass is because the concentration of the components is 0.0001% by mass or less, and the industrial concentration is difficult to control 10 201114946. In the present invention, the 'A1 phase system has a well-defined boundary in the plating layer and is similar to an island-like or dendritic phase. The A1 phase corresponds to, for example, the "A1 phase" at a high temperature in the ternary equilibrium state diagram of Zn-Al-Mg (A1 solid solution of solid solution Zn). The A1 phase at this high temperature will differ depending on the amount of solid solution dissolved in the Ai concentration of the plating bath. The A1 phase at this high temperature separates the fine Ai phase and the fine zn phase at normal temperature, and the island-like or dendritic shape seen at normal temperature can be regarded as a framework in which the A1 phase at a high temperature is retained. The phase derived from the barium phase at this high temperature (referred to as A1 primary crystal) and retaining the framework of the A1 phase in shape is referred to as the ai phase in this specification. The A1 phase is different in the ternary system of Al-Zn-Mg and the quaternary system of Al-Zn-Mg-Si, depending on the alloy concentration of the plating bath, and the phase state at normal temperature is also different. However, in either case, the A1 phase retains the structure from the A1 primary crystal. Because it can be clearly distinguished under the microscope observation, it is referred to as the A1 phase in the present specification. Here, the state of the bad pear skin is as shown in the figure, and the white portion of the amorphous shape is mixed with the shiny portion of the round shape, and the surface appearance of the surface which is scattered like a pear-like shape appears on the surface. In this state, the white portion is large and the area ratio of the glossy portion is low. Therefore, the degree of appearance of the pear skin can be evaluated by the ratio of the size of the white portion to the ratio of the white portion to the plating surface. In the present embodiment, the surface of the molten plating layer contains 94% or more of the gloss portion in the area ratio, and the number of the white portions is preferably 个) 0 / cm 2 or more. By this treatment, it is possible to provide a Zn-Al-Mg-based slab-plated steel sheet having a good appearance. In any steel plate, in more detail, as shown in Figs. 2 and 3, the white portion is the portion where the dendrites of the A1 phase exposed on the forged surface are concentrated, and the gloss portion is applied to the surface 11 201114946 binary eutectic. The part covered by the organization. The portion exposed by the dendrites of the plated surface A1 observed by the inventors of the present invention has a length of about 1 〇 (a size of about 2 m, and a dendrite thickness of about 5 to 50 μm). The white of the pear skin described in the present specification. The portion where the dendrites of the Α1 phase were exposed on the surface of the plating system was evaluated. When the number of white portions of the pear skin was evaluated, the white portion of the pear skin which was visually integrated was evaluated as a white portion. Here, in the ternary system of the ternary eutectic Zn-Al-Mg or the galvanized steel sheet of the Zn-Al-Mg-Si ternary system, solidification occurs at the time of final solidification of the plating layer in the above-mentioned component concentration range The inventors of the present invention produced a large number of Zn-Al-Mg-based hot-dip coated steel sheets by changing the plating composition or the cooling rate after plating, and collected samples of different state of the pear skin and investigated the characteristics thereof. According to the state of the pear skin of the sample to be collected, the scores of each sample 1 to 6 (pear skin score) are sequentially given from an appropriate state. Further, the pear skin which can be judged as "good" is set as a reference. Rating 3. Investigate the glossy surface in each sample The relationship between the rate and the number of white parts. The result is shown in Fig. 4. It is seen from Fig. 4 that if the number of white parts (including the part of the name) is (10) W or more, and the gloss part (including three) The area ratio of the part of the eutectic crystal is above (excluding 1%), and the Zn-A1_M# Hyunrong Qianzi steel plate tends to exhibit a good pear skin with a score of 3 or less. If the white part is finely dispersed, the white part In addition, when the area ratio of the gloss portion is increased, the area ratio of the white portion is decreased, and the number of white portions per unit area and the area ratio of the glossy portion can be expressed as fine white portions. And a smooth, glossy part of the pear
12 201114946 皮。 已知梨皮之白色部係如上所述的生成樹枝狀之初晶A1 相。本發明人等認為該A1相之結晶構造定會根據白色部之 分散狀態而不同。 於是，本發明人等利用XRD測定調查了 Zn-Al-Mg系熔 融鍍敷鋼板表面的X射線繞射圖案。其結果，發現在呈現評 分在3以下的良好梨皮之鋼板中，A1結晶（初晶的A1相）之 (200)面與鋼板表面平行的晶粒多，A1結晶之（111)面與鋼板 表面平行的晶粒少。 第5圖顯示利用平行於Zn_Ai_Mg系熔融鍍層中鋼板之 表面的面之XRD測定所得之繞射圖案之一例。 使用CuKa,線時’源自A1結晶的繞射圖案中，在2Θ為 38.4°之位置與2Θ為44.8。之位置產生波峰。2Θ為38.4。之位置 (晶面間距d為2.34A)係對應A1結晶的（111)面。2Θ為44.8。之 位置（晶面間距d為2.02A)係對應A1結晶的（2〇〇)面。因此， 若38.4。的波峰之繞射強度值高，（lu)面與鋼板表面平行的 晶粒就多。而，若44.8。的波峰之繞射強度值高，（2〇〇)面與 鋼板表面平行的晶粒就多。 此外’本發明人等針對平行於梨皮評分不同的 Zn-Al-Mg系炼融鍍敷鋼板之熔融鑛層的表面之鑛層（炼融 鑛層）的截面進行XRD測定，從所狀又射線繞射圖 案求取 A1相之(2〇〇)面的χ射線繞射強度聯〇)與相之（⑴）面的 X射線繞射強度1(111)之比’亦即繞射強度比丨(鹰洲⑴）， 以調查繞射強度比與鋼板之梨皮評分的關係、。此處，χ射線 滅 13 201114946 繞射強度1(200)及X射線繞射強度1(丨丨丨)係由各波峰之面積 分別求得。 再者’調整鋼板兩面之鍍敷附著量以形成1〇〇〜 350g/m之鍍層。將繞射強度比i(2〇〇)/i(i 11)與鋼板的梨皮評 分之關係示於第6圖。從第6圖之結果得知，若繞射強度比 1(200)/1(111)之數值在〇.8以上，就會獲得鋼板的梨皮評分之 數值為3以下的良好Zn-Al-Mg系熔融鍍敷鋼板。此處，繞射 強度比I(200)/I(m)之上限並無特殊限制。因此，繞射強度 比1(200)/1( 111)之上限為無限大。 另外，繞射強度比ipoovKm)之數值在〇8以上，針對 鋼板之梨皮評分值為3以下的鋼板測定白色部個數之結果， 任一鋼板之白色部個數均在100個/cm2以上。再者，白色部 係以肉眼統計炫融鑛層之表面。此處，可以用肉眼統計之 白色部個數的上限為10000個/cm2亦可。 接著，與專利文獻2同樣地利用EBSD法調查平行於A1 相之樹枝結晶的鐘敷表面的面之結構。其結果得知在X 射線繞射強度比1(200)/1(111)大，且呈現評分為3以下之良 好梨皮之Zn-Al-Mg系炼融鍍敷鋼板中，類似十字形狀的樹 枝結晶（十字形樹枝結晶）多，類似六角形狀之樹枝結晶少。 再者，EBSD<電子背散減射）法係以—定的間隔（一定 的照射點間距離）在SEM(掃描電子顯微鏡)之鏡筒内固定的 試料照射收斂電子束，從照射點產生背散射電子繞射像 (EBSD像），由該背散射f子繞射像分析構成多晶材料之每 個結晶之構造和方位的方法。再者，在該E B s D法中，係使 201114946 用熔融鍍層之表面經鏡面研磨的試料。換言之，係平行於 熔融鍍層之表面的熔融鍍層之截面的結晶結構和方位受到 分析。 針對梨皮評分不同的Zn_A1_Mg系熔融鍍敷鋼板，從採 用EBSD法測定之結構所得之EBSD像，以圖像處理僅挑選 類似十字形狀的樹枝結晶之部分以評估類似十字形狀之樹 枝結晶的面積率。第7A圖中顯示了利用EBSD法獲得之圖像 之一例。另外，第7B圖中顯示了第7A圖的圖像經2值化以 使(200)面方位之部分成為白色的圖像之一例。 將利用EBSD像之圖像分析獲得之類似十字形狀的樹 枝結晶之面積率與鋼板之梨皮評分之關係示於第8圖。從第 8圖之結果’得知如果A1相的類似十字形狀之樹枝結晶之面 積率為熔融鍍層總截面積的5%以上，就會獲得鋼板之梨皮 評分值為3以下的良好Ζη_Α1_Μ^^、熔融鍍敷鋼板。再者，若 考慮Zn-Al-Mg系熔融鍍層之合金組成，類似十字形狀之樹 枝結晶的面積率之上限為50%以下亦可。 另外’針對類似十字形狀之樹枝結晶之面積率在5%以 上的鋼板’測定白色部之個數之結果，任一鋼板的白色部 個數均在100個/cm2以上。 接著’本發明人等調查了 X射線繞射強度比1(200)/1(111) 與類似十字形狀之樹枝結晶的面積率之關係。第9圖中顯示 所得之X射線繞射強度比丨1)及類似十字形狀的樹 枝結晶之面積率與梨皮評分之關係。從第9圖可以媒認，在 梨皮評分為3以下的良好鋼板中，X射線繞射強度比 S- 15 201114946 1(200)/1(111)的數值在0』以上之範圍，類似十字形狀的樹枝 結晶之面積率在5%以上之範圍。 這樣，微細白色部之個數增加，全體白色部減少的梨 皮之改善與，A1結晶之(200)面與鍍敷表面平行之晶粒增加 (換言之，類似十字形狀的樹枝結晶之面積率的增加）相對 應。該理由係考慮如下所述。12 201114946 Leather. It is known that the white portion of the pear skin forms a dendritic primary crystal phase A1 as described above. The inventors of the present invention thought that the crystal structure of the A1 phase would be different depending on the state of dispersion of the white portion. Then, the inventors of the present invention investigated the X-ray diffraction pattern on the surface of the Zn-Al-Mg-based molten-plated steel sheet by XRD measurement. As a result, it was found that in the steel sheet of the good pear skin having a score of 3 or less, the (200) plane of the A1 crystal (the primary phase of the A1 phase) was more parallel to the surface of the steel sheet, and the (111) plane of the A1 crystal was bonded to the steel sheet. There are few grains parallel to the surface. Fig. 5 shows an example of a diffraction pattern obtained by XRD measurement using a surface parallel to the surface of the steel sheet in the Zn_Ai_Mg-based molten plating layer. When CuKa is used, the diffraction pattern derived from the A1 crystal is 44.8 at 2 Θ and 44.8 at 2 。. The position produces a peak. 2Θ is 38.4. The position (the interplanar spacing d is 2.34 A) corresponds to the (111) plane of the A1 crystal. 2Θ is 44.8. The position (the interplanar spacing d is 2.02 A) corresponds to the (2 〇〇) plane of the A1 crystal. Therefore, if 38.4. The peak intensity of the peak is high, and the (lu) plane is more parallel to the surface of the steel sheet. However, if 44.8. The peak intensity of the peak is high, and the (2〇〇) plane is more parallel to the surface of the steel sheet. In addition, the present inventors conducted XRD measurement on the cross section of the ore layer (smelting ore layer) on the surface of the molten ore layer of the Zn-Al-Mg-based smelting-plated steel sheet which is different from the pear skin score, and The diffraction pattern of the X-ray diffraction intensity (111) of the ((1)) plane of the phase (1) plane is obtained by the ray diffraction pattern, that is, the diffraction intensity ratio丨 (Eagle (1)), to investigate the relationship between the diffraction intensity ratio and the pear skin score of the steel plate. Here, X-ray extinction 13 201114946 Diffraction intensity 1 (200) and X-ray diffraction intensity 1 (丨丨丨) are obtained from the areas of the respective peaks. Further, the amount of plating adhesion on both sides of the steel sheet was adjusted to form a plating layer of 1 〇〇 to 350 g/m. The relationship between the diffraction intensity ratio i(2〇〇)/i(i 11) and the pear skin score of the steel sheet is shown in Fig. 6. From the results of Fig. 6, it is found that if the diffraction intensity ratio of 1 (200) / 1 (111) is above 〇.8, a good Zn-Al- of the steel sheet having a pear skin score of 3 or less is obtained. Mg-based melt-plated steel sheet. Here, the upper limit of the diffraction intensity ratio I (200) / I (m) is not particularly limited. Therefore, the upper limit of the diffraction intensity ratio of 1 (200) / 1 (111) is infinite. In addition, the value of the diffraction intensity ratio ipoovKm) is 〇8 or more, and the number of white portions of the steel sheet having a pear skin score of 3 or less is measured, and the number of white portions of any steel sheet is 100/cm 2 or more. . Furthermore, the white part counts the surface of the ore layer with the naked eye. Here, the upper limit of the number of white portions which can be counted by the naked eye is 10,000 pieces/cm2. Next, in the same manner as in Patent Document 2, the structure of the surface of the clock surface parallel to the crystal of the A1 phase was investigated by the EBSD method. As a result, it was found that the Zn-Al-Mg-based smelting plated steel sheet having a large X-ray diffraction intensity ratio of 1 (200)/1 (111) and exhibiting a good pear skin with a score of 3 or less is similar to a cross shape. Branches are crystallized (cross-shaped branches are crystallized), and branches resembling hexagonal shapes are less crystalline. Further, the EBSD <Electronic Backscattering Reduction method irradiates a convergent electron beam with a sample fixed in a SEM (Scanning Electron Microscope) lens barrel at a constant interval (a certain distance between irradiation points), and generates a back from the irradiation spot. A scattering electron diffraction image (EBSD image) is used to analyze the structure and orientation of each crystal of the polycrystalline material from the backscattered fron diffraction image. Further, in the E B s D method, the sample of the surface of the molten coating was mirror-polished by 201114946. In other words, the crystal structure and orientation of the cross section of the molten plating layer parallel to the surface of the molten plating layer were analyzed. For the Zn_A1_Mg-based molten-plated steel sheet with different pear skin scores, from the EBSD image obtained by the structure determined by the EBSD method, only the portion of the crystal of the branch shape resembling a cross shape was selected by image processing to evaluate the area ratio of the branch crystals resembling a cross shape. . An example of an image obtained by the EBSD method is shown in Fig. 7A. Further, Fig. 7B shows an example of an image in which the image of Fig. 7A is binarized so that the portion of the (200) plane orientation becomes white. The relationship between the area ratio of the cross-shaped tree branch crystal obtained by image analysis using the EBSD image and the pear skin score of the steel sheet is shown in Fig. 8. From the result of Fig. 8, it is found that if the area ratio of the crystal of the cross-shaped branch of the A1 phase is 5% or more of the total cross-sectional area of the molten plating layer, a good value of the steel sheet with a pear skin score of 3 or less is obtained Ζη_Α1_Μ^^ , molten plated steel. Further, in consideration of the alloy composition of the Zn-Al-Mg-based molten plating layer, the upper limit of the area ratio of the tree-like crystals having a cross shape may be 50% or less. In addition, as a result of measuring the number of white portions of the steel sheet having an area ratio of 5% or more of the cross-shaped tree crystals, the number of white portions of any of the steel sheets is 100 pieces/cm2 or more. Then, the inventors investigated the relationship between the X-ray diffraction intensity ratio of 1 (200) / 1 (111) and the area ratio of the branch-like crystal of a cross shape. Fig. 9 shows the relationship between the obtained X-ray diffraction intensity ratio 丨1) and the area ratio of the cross-shaped tree branch crystal and the pear skin score. It can be seen from Fig. 9 that in a good steel plate with a pear skin score of 3 or less, the X-ray diffraction intensity ratio is in the range of 0 』 or more than the S- 15 201114946 1 (200)/1 (111), similar to the cross. The area ratio of the shape of the branch crystal is in the range of 5% or more. Thus, the number of fine white portions is increased, and the improvement of the pear skin which is reduced in the entire white portion is increased, and the crystal grains in which the (200) plane of the A1 crystal is parallel to the plating surface are increased (in other words, the area ratio of the crystal of the branch shape similar to the cross shape) Increase) Correspondence. The reason is considered as follows.
Zn-Al-Mg的3元系凝固過程中，已知八丨相的枝晶容易成 長的面係如專利文獻2中記載的（11〇)面。因此，若八丨相的枝 晶平行於鋼板表面成長，從鋼板表面看到的A1結晶向（n〇〇) 面（（100)面、（200)面等）或(mmm)面（(111)面、（222)面等）之 配向性增強。 向（mmm)面的配向性強時’ A1相的枝晶之(_m)面相 對於鍵敷表面成為平行，所以若從鑛敷表面方向觀察_ 的枝晶’就會看到從晶核在6方向延伸枝晶的六角形狀之樹 枝結曰曰曰。另夕卜，向_)面的配向性強時，A1相的枝晶之(n〇〇) 面相對於紐表面成為平行，所以若讀敷表面方向觀察 糾目的枝晶，就會看到從晶核在4方向延伸枝晶的十字形狀 之樹枝結晶。 如上所述，在(_)面的配向性相對高的條件下若從 垂直於_面之方向看’叫目之枝晶係向微細的類似十 字形進行配向。 枝晶係分支成-次枝、二次枝、三次枝持續成長這 些是-個結晶，結晶的成長方向在⑽)方衫變。因此， 若在平行於鍍敷表面的面切割鍍層，任—枝都會類似相同 16 201114946 形，在(nO〇)面具配向性之結晶，任一枝都會類似十字形狀。 與六角形狀的結晶相比，因十字形狀的結晶枝與枝所 成角度寬’推測貫通垂直於鍍敷表面方向之熔液的流路就 合易形成。因此，在鍍敷的凝固過程中A1相之枝晶會在(200) 面配向’從鑛敷表面看，因成為十字形狀者在垂直於鍍敷 表面方向的鎮液之流動性良好，鍍敷表面的A1相之枝晶就 谷易覆蓋鎮敷熔液。也就是說，因鍍敷表面的A1相容易被 最後凝固的二元共晶所覆蓋，所以最終鍍敷表面的白色部 減少，推測梨皮成為良好。 A1相的枝晶在(200)面配向的機制並不明確。但是，透 過5又置將要擦拭前的熔融鍍層之溫度在超過Zn-Al-Mg系熔 融鍍敷金屬的凝固開始溫度之溫度，繼而將擦拭經過1秒後 的平均铜板溫度冷卻到Zn_Al-Mg系熔融鑛敷金屬之凝固開 始溫度-10°C以下，若從A1相之枝晶在(200)面配向考慮，在 '疑固開始階段，認為某一定粒徑以下的微細A1相之晶核發 生大量結晶會影響A1相之配向性。因為微細的八丨相在鍍敷 熔液中比粗大結晶更容易旋轉，推測在容易確保鍍敷熔液 的流動性方向，也就是鍍層的凝固收縮過程中在容易確保 垂直於重要鍍敷表面之方向的鑛敷溶液流動性方向加以配 向，從鍍敷表面看會容易產生類似十字形的A1相。 —般而言，為大量產生微細的晶核，重要的是較大地 。又定在凝固開始點之過冷度。因此，推測利用氣體喷注的 衝擊力在控制鍍敷附著量的擦拭位置開始凝固可以最大地 π定在凝固開始點之過冷度，μ相的晶核會大量產生，從 17 201114946 鍍敷表面看就容易產生類似十字形狀的入丨相。 本發明中，鑛層之厚度不作特殊限制。但是，在薄鍍 層鋼板中，即使不特別控制擦拭後的冷卻，表面外觀也多 會良好。另外，當單面的鍍敷附著量在50〜300g/m2之範圍 時，有時梨皮之狀態會惡化。因此，链層之白色部受到控 制的Zn-Al-Mg系炼融鑛敷鋼板之單面的鑛敷附著量以5〇〜 300g/m2為佳。當較厚地控制鍍敷附著量時，由於擦栻後的 鋼板溫度（炫融鑛層之溫度）難以降低，推測梨皮之狀餘不 良0 製造具有如上所述之良好梨皮的Zn_A1_Mg系熔融鍍敷 鋼板時，基本上要控制熔融鍍層之凝固過程。藉由該凝固 過程的控制，在(200)面方位配向，從垂直於鍍敷表面之方 向看，使微細的類似十字形狀的樹枝結晶之A1結晶的比例 增加。 換吕之，利用以下的方法控制炼融鍍層之凝固過程。 首先，對從熔融鍍浴取出的鋼板吹氣，進行擦掉過剩鍍敷 金屬（Zn-Al-Mg系鍍敷金屬）的擦拭。控制該擦拭之際的冷 卻，々剛擦拭後的鋼板溫度（溶融鐘層之溫度）在低於 Zn-Al-Mg系熔融鍍敷金屬之凝固開始溫度丨〇〇c的溫度以下 (凝固開始溫度-l〇°C以下）。為控制剛擦拭後的鋼板溫度， 亦可控制例如鍵洛之溫度或擦拭氣體之溫度及量等之條 件。此外，擦拭之後可以將鑛敷鋼板放冷，或者，亦可在 10 C/sec以下冷卻。再者，剛擦拭後的鋼板溫度低於凝固開 始溫度10°C的溫度以上時，就無法獲得梨皮良好的鍍敷鋼 18 201114946 板。 過去以來，一般並不實行採用擦拭的鍍層之冷卻控制。 換言之’在擦拭中及剛擦拭後，鍍層多為完全熔融狀態以 可以容易地進行鍍敷量之控制。特別是在擦拭中，為降低 鍍敷之黏度，要設定鍍敷溫度在相比於凝固開始溫度足夠 高的溫度。例如，如非專利文獻1中所示，擦拭時的鍍敷附 者里之刀析係使用層流模裂。因此’在過去以來，控制鍍 敷附著量較厚時，有時梨皮之狀態會降低。 若冷卻剛擦拭後的鋼板(鍍敷鋼板）直到低於凝固開始 溫度10°C的溫度以下為止，伴隨微細且均勻的核生成，從 垂直於鐘敷表面之方向看’會生成類似十字形狀的樹枝結 另一方面，若設定剛擦拭後的鋼板溫度（熔融鍍層之溫 度)在低於凝固開始溫度10°c的溫度以上，在接下來伴隨溫 度降低的凝固過程中，鑛敷表面大的A1相之枝晶就容易成 長，從垂直於鍍敷表面之方向看，容易生成類似六角形狀 的樹枝結晶。 另外，擦拭後若放冷鍍敷金屬直到最終凝固溫度為止， 平滑部分之面積就會增加’梨皮有進一步改善的傾向。 若冷卻速度變慢’推測因可以充分確保鍍敷熔液從垂 直於鍍敷表面方向看自微細的類似十字形狀之樹枝結晶的 枝晶之間隙到鐘層表面冒出的時間，平滑部分之面積會增 加。 實際應用上，為確保生產性’必須一定程度的冷卻速 19 201114946 度。但是，為獲得梨皮較良好的Zn-Al-Mg系熔融錄敷鋼板， 以10 C /sec以下之冷卻速度冷卻為佳。在過去以來，為確保 生產性，多在擦拭後以10°C/sec以上的冷卻速度進行冷卻， 以製造Zn-Al-Mg糸炼融鍵敷鋼板。在該情形下，難以獲得 梨皮良好的鍍敷鋼板。再者，若考慮A1相的枝晶成長(核成 長），亦可進行以1 〇°C /sec以下之冷卻速度的冷卻直到 Zn-Al-Mg系鍍敷金屬的A1相之凝固開始溫度為止。 再者’有必要令擦拭的開始溫度（將要擦拭前的鋼板溫 度）高於鍍敷金屬之凝固開始溫度。換言之，要控制鋼板溫 度令將要擦拭別的鋼板溫度超過Zn-Al-Mg系鑛敷金屬之凝 固開始溫度。 若擦拭的開始溫度低於鑛敷金屬之凝固開始溫度，A1 相之分佈就會不均勻，引起不良的梨皮以外之外觀缺陷。 為容易地實行剛擦拭後的溫度調整，宜在超過凝固開 始溫度，高於凝固開始溫度l〇°C之溫度以下（凝固開始溫度 + 10°C以下）之溫度範圍開始擦拭。 此處，將要擦拭前的鋼板溫度係採用擦拭氣體之冷卻 開始點的鍍敷鋼板之平均溫度。另外，剛擦拭後的鋼板溫 度係從採用擦拭氣體之冷卻開始1秒後的鍍敷鋼板之平均 溫度。鋼板溫度可以利用放射溫度計間接測定，亦可利用 接觸板溫度計直接測定。 再者，上述Zn-Al-Mg系熔融鍍敷鋼板之製造方法係可 以應用於薄鍍層（超過〇g/m2不足50g/m2)之鍍敷鋼板及厚鍍 層（50g/m2以上3〇〇以下）之鍍敷鋼板的兩者。特別是上述 20 201114946In the ternary system of Zn-Al-Mg, it is known that the dendrites of the gossip phase are easily formed into a surface of the (11 Å) surface described in Patent Document 2. Therefore, if the dendrites of the gossip phase grow parallel to the surface of the steel sheet, the A1 crystals seen from the surface of the steel sheet are oriented to the (n〇〇) plane ((100) plane, (200) plane, etc.) or (mmm) plane ((111). The alignment of the face, (222) face, etc. is enhanced. When the orientation to the (mmm) plane is strong, the (_m) plane of the dendrites of the A1 phase is parallel with respect to the surface of the bond, so if the dendrite of the _ is observed from the surface of the ore, it will be seen from the nucleus at 6 The branches of the hexagonal shape that extend in the direction of dendrites are crusted. In addition, when the orientation of the _) plane is strong, the (n〇〇) plane of the dendrites of the A1 phase is parallel with respect to the surface of the new surface, so if the dendrites are observed in the direction of the surface, the crystals are seen. The nucleus crystallizes in the cross shape of the dendrites extending in the four directions. As described above, under the condition that the orientation of the (_) plane is relatively high, the dendrites of the order are aligned from the direction perpendicular to the plane of the _ plane to the fine similar figure. The dendritic branches are branched into sub-branches, secondary branches, and tertiary branches. These are a crystal, and the growth direction of the crystal is changed in (10)). Therefore, if the coating is cut on the surface parallel to the surface of the plating, the branches will be similar to the same 16 201114946 shape, and in the (nO〇) mask alignment crystal, any branch will resemble a cross shape. Compared with the crystal of the hexagonal shape, the flow path of the cross-shaped crystal branch and the branch is wide. It is presumed that the flow path through the melt perpendicular to the direction of the plating surface is easily formed. Therefore, during the solidification of the plating, the dendrites of the A1 phase will be aligned on the (200) plane. From the surface of the mineral deposit, the fluidity of the shale liquid perpendicular to the direction of the plating surface is good due to the shape of the cross. The dendrites of the A1 phase on the surface are easy to cover the molten iron. That is, since the A1 phase on the plating surface is easily covered by the finally solidified binary eutectic, the white portion of the final plating surface is reduced, and it is estimated that the pear skin is good. The mechanism by which the dendrites of the A1 phase are aligned in the (200) plane is not clear. However, the temperature of the molten plating layer to be wiped before passing through 5 is higher than the temperature at the solidification start temperature of the Zn-Al-Mg-based molten plating metal, and then the average copper plate temperature after one second of wiping is cooled to the Zn_Al-Mg system. The solidification starting temperature of the molten ore metal is below -10 °C. If the dendrites of the A1 phase are aligned in the (200) plane, the nucleation of the fine A1 phase below a certain particle size is considered to occur at the beginning of the suspecting stage. A large amount of crystallization affects the orientation of the A1 phase. Since the fine gossaye phase is more easily rotated than the coarse crystal in the plating melt, it is presumed that it is easy to ensure the perpendicularity to the important plating surface in the direction of the fluidity of the plating melt, that is, during the solidification shrinkage of the plating layer. The orientation of the ore solution is oriented in the direction of fluidity, and it is easy to produce a cross-shaped A1 phase from the surface of the plating. In general, it is important to produce a fine crystal nucleus in large quantities. Also set the degree of subcooling at the start of solidification. Therefore, it is presumed that the impact force by gas injection starts to solidify at the wiping position where the amount of plating adhesion is controlled, and the degree of subcooling at the solidification starting point can be maximally π, and the crystal nucleus of the μ phase is generated in a large amount, from 17 201114946 plating surface. It is easy to produce a cross-like shape. In the present invention, the thickness of the ore layer is not particularly limited. However, in the thin-coated steel sheet, the surface appearance is good even if the cooling after wiping is not particularly controlled. Further, when the plating amount of one side plating is in the range of 50 to 300 g/m2, the state of the pear skin may deteriorate. Therefore, the amount of mineral deposit on one side of the Zn-Al-Mg-based smelting ore-plated steel sheet to which the white portion of the chain layer is controlled is preferably 5 Å to 300 g/m2. When the amount of plating adhesion is controlled thickly, it is difficult to reduce the temperature of the steel sheet after rubbing (the temperature of the smelting ore layer), and it is presumed that the shape of the pear skin is poor. 0 Zn_A1_Mg-based hot-dip plating having the good pear skin as described above is produced. When the steel sheet is applied, it is basically necessary to control the solidification process of the molten coating. By the control of the solidification process, the (200) plane orientation is aligned, and the ratio of the A1 crystal which crystallizes the fine cross-shaped branches is increased from the direction perpendicular to the plating surface. For Lu, use the following method to control the solidification process of the smelting coating. First, the steel sheet taken out from the molten plating bath is blown, and wiping off the excess plating metal (Zn-Al-Mg-based plating metal) is performed. Controlling the cooling at the time of wiping, the temperature of the steel sheet immediately after wiping (temperature of the molten clock layer) is lower than the temperature of the solidification start temperature 丨〇〇c of the Zn-Al-Mg-based molten plating metal (solidification start temperature) -l〇°C or less). In order to control the temperature of the steel sheet immediately after wiping, it is also possible to control conditions such as the temperature of the key or the temperature and amount of the wiping gas. In addition, the coated steel plate may be cooled after wiping, or it may be cooled below 10 C/sec. Further, when the temperature of the steel sheet immediately after wiping was lower than the temperature of the solidification starting temperature of 10 ° C, the plated steel of good pear skin 18 201114946 could not be obtained. In the past, cooling control using a wiping coating was generally not practiced. In other words, the plating layer is mostly in a completely molten state during and after wiping, so that the plating amount can be easily controlled. In particular, in wiping, in order to lower the viscosity of plating, it is necessary to set the plating temperature to a temperature sufficiently higher than the solidification start temperature. For example, as shown in Non-Patent Document 1, the knife-out in the plating attachment at the time of wiping uses laminar flow cracking. Therefore, in the past, when the amount of plating adhesion was controlled to be thick, the state of the pear skin sometimes decreased. If the steel sheet (plated steel sheet) just after being cooled is cooled to a temperature lower than the solidification start temperature by 10 ° C or less, with a fine and uniform nucleation, it looks like a cross shape when viewed from a direction perpendicular to the clock surface. On the other hand, if the temperature of the steel sheet immediately after wiping (the temperature of the molten coating layer) is set to be higher than the temperature of 10 ° C below the solidification start temperature, the A1 having a large surface of the mineral deposit is subsequently formed in the solidification process accompanied by the temperature decrease. The dendrites of the phase are easy to grow, and it is easy to form a crystal of a branch resembling a hexagonal shape when viewed perpendicularly to the direction of the plated surface. Further, if the metal is cold-plated after wiping until the final solidification temperature, the area of the smooth portion is increased, and the pear skin tends to be further improved. If the cooling rate becomes slower, it is presumed that the area of the smooth portion can be sufficiently ensured from the gap between the dendrite crystallized from the fine cross-shaped branch crystallized from the direction perpendicular to the plating surface to the surface of the clock layer. Will increase. In practical applications, to ensure productivity, a certain degree of cooling rate must be achieved. However, in order to obtain a Zn-Al-Mg-based melt-coated steel sheet having a good pear skin, it is preferred to cool at a cooling rate of 10 C /sec or less. In the past, in order to ensure productivity, it is often cooled at a cooling rate of 10 ° C /sec or more after wiping to produce a Zn-Al-Mg 糸 smelting bonded steel sheet. In this case, it is difficult to obtain a plated steel sheet having a good pear skin. In addition, considering the dendrite growth (nuclear growth) of the A1 phase, cooling at a cooling rate of 1 〇 ° C /sec or less may be performed until the solidification start temperature of the A1 phase of the Zn-Al-Mg-based plating metal. . Furthermore, it is necessary to make the starting temperature of the wiping (the temperature of the steel sheet to be wiped) higher than the solidification starting temperature of the plating metal. In other words, it is necessary to control the temperature of the steel sheet so that the temperature of the other steel sheet is to be wiped over the solidification start temperature of the Zn-Al-Mg mineral deposit metal. If the starting temperature of the wiping is lower than the solidification starting temperature of the ore metal, the distribution of the A1 phase will be uneven, causing defects in appearance other than the poor pear skin. In order to easily carry out the temperature adjustment immediately after wiping, it is preferable to start wiping at a temperature range exceeding the solidification start temperature and lower than the solidification start temperature l〇 °C (solidification start temperature + 10 ° C or lower). Here, the temperature of the steel sheet to be wiped is the average temperature of the plated steel sheet at the cooling start point of the wiping gas. Further, the temperature of the steel sheet immediately after wiping was the average temperature of the plated steel sheet 1 second after the cooling by the wiping gas. The temperature of the steel sheet can be measured indirectly using a radiation thermometer or directly using a contact plate thermometer. Further, the method for producing the Zn-Al-Mg-based hot-dip coated steel sheet can be applied to a plated steel sheet having a thin plating layer (beyond 〇g/m2 of less than 50 g/m 2 ) and a thick plating layer (50 g/m 2 or more and 3 〇〇 or less). Both of the plated steel sheets. Especially the above 20 201114946
Zn-Al-Mg系熔融鍍敷鋼板之製造方法對於厚鍍層之鍍敷鋼 板可以合適地應用。 以下，將說明本發明之實施例’實施例中採用的條件 係用以確認本發明之可實施性及效果的一條件例。因此本 發明不限定於該例。 實施例1 準備厚度0.8mm的冷軋鋼板，使用無氧化爐型的連續 熔融鍍敷生產線，實行加熱、退火、Zn—ALMg系熔融鍍敷 以製作成鑛敷鋼板。退火氛圍設為1〇體積％氫、9〇體積。/〇氮 的混合氣體氛圍，設定退火溫度為75(rc，退火時間為3分 釦。在熔融鍍敷處理中，係在具有表丨所示組成之43〇。(：的 鍍浴中浸潰鋼板3秒後，用&氣體擦栻來調整鍍敷附著量。 溶1^鑛敷處理後，實行放冷（空冷）或10°C/sec以下之氣體冷 卻。其他的測試條件係表1所示之條件。 鑛敷之外觀係從鍍敷鋼板切出樣品，利用評分評估樣 品表面之梨面（梨皮）。將可以判定為「良好」的界限之梨皮 ，定為基準的評分3，依據採集試料的梨皮狀態，從合適狀 悲依序賦予各樣品1〜6的評分以評估各樣品。 另外’利用目視計算白色部之個數。 。 各式料製作XRD測疋用的§式料與EBSD測定用的試 料’分別進行XRD測定與EBSD測定。 將5平估結果示於表1。實施例的鍍敷鋼板之梨皮良好。 21 201114946A method for producing a Zn-Al-Mg-based molten-plated steel sheet can be suitably applied to a plated steel sheet having a thick plating layer. Hereinafter, the conditions used in the examples of the embodiments of the present invention will be described as a conditional example for confirming the practicability and effects of the present invention. Therefore, the present invention is not limited to this example. Example 1 A cold-rolled steel sheet having a thickness of 0.8 mm was prepared, and a continuous molten plating production line of an oxidizing furnace type was used to carry out heating, annealing, and Zn-ALMg-based hot-dip plating to form an ore-coated steel sheet. The annealing atmosphere was set to 1 vol% hydrogen and 9 〇 volume. / 〇 Nitrogen mixed gas atmosphere, set annealing temperature is 75 (rc, annealing time is 3 deduction. In the melt plating treatment, it is 43 〇 in the composition shown in Table 〇. After the steel plate is used for 3 seconds, the amount of plating adhesion is adjusted by using & gas rubbing. After the treatment, the cooling is performed (air cooling) or gas cooling at 10 ° C/sec or less. Other test conditions are shown in Table 1. The appearance of the mineral deposit is obtained by cutting out the sample from the plated steel plate and evaluating the pear noodle (pear skin) on the surface of the sample by using a score. The pear skin which can be judged as "good" is the benchmark score 3 According to the state of the pear skin of the sample, the scores of each sample 1 to 6 were evaluated from the appropriate order to evaluate each sample. In addition, the number of white parts was calculated by visual inspection. § For the XRD measurement of each type of material The XRD measurement and the EBSD measurement were performed on the sample for the EBSD measurement and the EBSD measurement. The results of the 5 evaluation were shown in Table 1. The pear skin of the plated steel sheet of the example was good. 21 201114946
4£) •w? 4£) 4¾) «? 片 ^fX 評分 m (N (N (Ν in in (N in m 1〇 (N m (N (Ν m (Ν 制ο 想$ 1 某〇 rn <N <Ν 1 ^ oo m m 00 m ΓΛ (N V£) r—Η CN l> 00 oo CN I·1 Η 率樂 梁《彡 {tf mg 00 vd σ\ 00 »—-Η 1 1 Ο <Ν r-H (Ν (Ν ι> τ—η r-H σ^ m (Ν 〇 (N (Ν CN 1 (Ν (Ν 七龙 in ο m σ\ 卜 VO 卜 Tf α\ Ον 〇\ Os 落 Ον ο 0Λ c^ 艺 白色部分 之個轉 個/cm2 o cn 寸 ^Τ) (N ο 1 Η CN m ΓΛ r-H g CN 卜 Ο rO ϊ—^ 00 τ·^ A1 濃度 mass% i—H ψ Ή 1—^ i—H 寸 对 ι—Η < i—H 1—Η <N (N ίΝ (Ν Mg 濃度 mass% cn 寸 in ΓΛ t〇 m VO rn 寸 ΙΤί m m 擦拭後 的冷卻 模式 每· -k 介 韜 韜 韜 韜 ή®ϊ 顴 韜 兩面 锻層1 g/n? Ο m ο m Ο m ο m Ο ΓΟ 〇 m 〇 Ο m Ο ο m 〇 m ο ΓΛ 〇 m 標準 (Ν m 寸 卜 00 〇\ 〇 1—^ CN 22 201114946 實施例2 準備厚度0.4〜2.0mm的冷軋鋼板’使用無氧化爐型的 連續熔融鍍敷生產線，實行加熱、退火、Zn-A1-Mg系熔融 鍍敷以製作成鍍敷鋼板。退火氛圍設為10體積％氫、90體 積％氮的混合氣體氛圍’設定退火溫度為750°C，退火時間 為3分鐘。在熔融鍍敷處理中，係在具有表1所示組成之鍵 浴中浸潰3秒後，用N2氣體擦拭來調整鍍敷附著量。鍍敷後 的冷卻係空冷。其他的測試條件係表2所示之條件。再者， 在表2之情形，鍍敷金屬的凝固開始溫度係428°C。 鍍敷之外觀係與實施例1同樣地用評分作評估。 利用鍍敷表面的鏡面研磨由各樣品製作成X RD測定用 的試料，分別進行XRD測定。 另外’利用接觸板溫度計測定擦拭後1秒後之鋼板溫 度。將經測定之該鋼板溫度作為剛擦拭後之鋼板溫度來評 估。 將評估結果示於表2 ^標準3〜5之實施例的鍍敷鋼板， 其梨皮良好。但是，標準6〜9之比較例的鑛敷鋼板，因其 剛擦拭後的鋼板溫度高（超過418。〇，梨皮之狀態會惡化。 另外’標準1及2的參考例之鍍敷鋼板，因其鍍敷量小，故 梨皮良好。 23 201114946 表2 標準 Mg濃度 mass% AI濃度 mass% 兩面 鍍層 概算 g/m2 板厚 mm 浴溫 °c 剛擦栻 後的鋼 板溫度 °c 繞射強度比 1(200)/1(111) 評分 1 3.5 11 40 0.4 430 403 0.42 2.5 參考例 2 3.5 11 80 0.4 430 403 0.40 2 參考例 3 3.5 11 350 1.2 430 404 1.13 2.5 實施例 4 3.3 11 180 1.2 430 404 1.95 2 實施例 5 3.3 11 120 2 430 412 0.98 2.5 實施例 6 3.3 11 120 1 460 433 0.56 3.5 比較例 7 3.3 11 180 1.2 460 436 0.45 4 比較例 8 3.3 11 270 0.5 460 433 0.43 3.5 比較例 9 3.3 11 270 1 460 433 0.49 4 比較例 產業之可利用性 可以安定地製造一種Zn-Al-Mg系熔融鍍敷鋼板，其紋 理微細，而且具有平滑部分多的梨皮之優良外觀。 【圖式簡單說明3 第1圖係使用照片的Zn-Al-Mg系熔融鍍敷鋼板表面之 梨皮的說明圖。 第2圖係利用了電子顯微鏡照片之梨皮的說明圖。 第3圖係利用了電子顯微鏡照片之梨皮的說明圖。 第4圖係梨皮表面之白色部個數及光澤部面積與梨皮 評分之關係的示意圖。 第5圖係平行於熔融鍍敷鋼板之表面的面利用XRD測 定獲得之繞射圖案之一例的示意圖。 第6圖係鍍層中繞射強度比1(200)/1(111)與鍍敷鋼板表 24 201114946 面的梨皮評分之關係的示意圖。 第7A圖係利用EBSD法測定鍍層之結果所得之圖像之 一例0 第7B圖係第7A圖所示之圖像經2值化以使(200)面方位 的部分成為白色的圖像之一例。 第8圖係鍍層表面類似十字形狀的樹枝結晶之面積率 與鍍敷鋼板表面之梨皮評分之關係的示意圖。 第9圖係鍍層中繞射強度比1(200)/1( 111)及類似十字形 的樹枝結晶之面積率與梨皮評分之關係的示意圖。 【主要元件符號說明】 (無） 254£) • w? 4£) 43⁄4) «? Piece ^fX score m (N (N (Ν in in (N in m 1〇(N m (N (Ν m (Ν m Ν 想 want $ 1 〇 some rn <N <N 1 ^ oo mm 00 m ΓΛ (NV£) r-Η CN l> 00 oo CN I·1 Η rate Leliang "彡{tf mg 00 vd σ\ 00 »—-Η 1 1 Ο <Ν rH (Ν (Ν ι> τ—η rH σ^ m (Ν 1 (N (Ν CN 1 (Ν (Ν七七 in ο m σ\ 卜 VO 卜 Tf α\ Ον 〇 \ Os Ο Ο ο 0Λ c^ Art white part of a turn / cm2 o cn inch ^ Τ) (N ο 1 Η CN m ΓΛ rH g CN Ο Ο rO ϊ-^ 00 τ·^ A1 concentration mass% i-H ψ Ή 1— ^ i—H Inch ι—Η < i—H 1—Η <N (N Ν Ν Ν mas mas 〇 〇 〇 〇 〇 mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm mm韬韬韬韬ή 韬韬韬韬ή ϊ 颧韬 颧韬 颧韬 颧韬 1 1 1 1 1 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准 标准\ 〇1—^ CN 22 20 1114946 Example 2 Preparation of a cold-rolled steel sheet having a thickness of 0.4 to 2.0 mm was carried out by heating, annealing, and Zn-A1-Mg-based hot-dip plating using a continuous hot-dip plating line of an oxidizing-free furnace type to form a plated steel sheet. A mixed gas atmosphere of 10% by volume of hydrogen and 90% by volume of nitrogen was set to an annealing temperature of 750 ° C and an annealing time of 3 minutes. In the molten plating treatment, it was immersed in a key bath having the composition shown in Table 1. After 3 seconds of collapse, the amount of plating adhesion was adjusted by wiping with N2 gas. The cooling after plating was air-cooled. Other test conditions were as shown in Table 2. Further, in the case of Table 2, solidification of the plated metal The starting temperature was 428 ° C. The appearance of the plating was evaluated by scoring in the same manner as in Example 1. Samples for XRD measurement were prepared from each sample by mirror polishing of the plated surface, and XRD measurement was performed. Further, the temperature of the steel sheet 1 second after the wiping was measured by a contact plate thermometer. The measured steel sheet temperature was evaluated as the steel sheet temperature immediately after wiping. The evaluation results are shown in the plated steel sheets of the examples of Table 2^Standards 3 to 5, and the pear skin was good. However, in the case of the mineral-coated steel sheet of the comparative example of the standard 6 to 9, the temperature of the steel sheet immediately after the wiping is high (beyond 418. The state of the pear skin is deteriorated. In addition, the plated steel sheets of the reference examples of the standards 1 and 2, Because of its small amount of plating, the pear skin is good. 23 201114946 Table 2 Standard Mg concentration mass% AI concentration mass% Two-side plating estimate g/m2 Thickness mm Bath temperature °c Steel plate temperature just after rubbing °c Diffraction intensity Ratio 1 (200) / 1 (111) Rating 1 3.5 11 40 0.4 430 403 0.42 2.5 Reference Example 2 3.5 11 80 0.4 430 403 0.40 2 Reference Example 3 3.5 11 350 1.2 430 404 1.13 2.5 Example 4 3.3 11 180 1.2 430 404 1.95 2 Example 5 3.3 11 120 2 430 412 0.98 2.5 Example 6 3.3 11 120 1 460 433 0.56 3.5 Comparative Example 7 3.3 11 180 1.2 460 436 0.45 4 Comparative Example 8 3.3 11 270 0.5 460 433 0.43 3.5 Comparative Example 9 3.3 11 270 1 460 433 0.49 4 Comparable industry availability A Zn-Al-Mg-based melt-plated steel sheet can be stably produced with a fine texture and a fine appearance of a smooth portion of pear skin. Brief description 3 Figure 1 is a photo of Zn-Al-M Fig. 2 is an explanatory view of a pear skin on the surface of a molten-plated steel sheet. Fig. 2 is an explanatory view of a pear skin using an electron microscope photograph. Fig. 3 is an explanatory view of a pear skin using an electron microscope photograph. A schematic diagram showing the relationship between the number of white portions on the surface of the pear skin and the area of the glossy portion and the pear skin score. Fig. 5 is a schematic view showing an example of a diffraction pattern obtained by XRD measurement on a surface parallel to the surface of the molten plated steel sheet. The relationship between the diffraction intensity ratio of the pattern plating layer 1 (200)/1 (111) and the pear skin score of the plated steel sheet 24 201114946. Figure 7A shows the image obtained by the EBSD method. Example 0 Fig. 7B is an example of an image in which the image shown in Fig. 7A is binarized so that the portion of the (200) plane orientation becomes white. Fig. 8 is an area ratio of the crystal of the dendritic surface similar to the cross shape. Schematic diagram of the relationship with the pear skin score on the surface of the plated steel. Fig. 9 is the relationship between the area ratio of the diffraction intensity of the coating in the plating layer of 1 (200)/1 (111) and the shape of the cross-shaped tree and the pear skin score. Schematic. [Main component symbol description] (none) 25