JP3201312B2 - Galvannealed steel sheet with excellent press formability - Google Patents
Galvannealed steel sheet with excellent press formabilityInfo
- Publication number
- JP3201312B2 JP3201312B2 JP19531097A JP19531097A JP3201312B2 JP 3201312 B2 JP3201312 B2 JP 3201312B2 JP 19531097 A JP19531097 A JP 19531097A JP 19531097 A JP19531097 A JP 19531097A JP 3201312 B2 JP3201312 B2 JP 3201312B2
- Authority
- JP
- Japan
- Prior art keywords
- steel sheet
- base material
- plating film
- xxx
- plating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Coating With Molten Metal (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、自動車、家電製
品、建築材料等に使用される、表面の摺動性と耐パウダ
リング性が良好でプレス成形性に優れた合金化溶融亜鉛
めっき鋼板に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a galvannealed steel sheet having excellent surface slidability and powdering resistance and excellent press formability, which is used for automobiles, home appliances, building materials and the like. .
【０００２】[0002]
【従来の技術】溶融亜鉛めっき鋼板を自動車、家電製
品、建築材料等に使用する場合、亜鉛めっき皮膜をＦｅ
−Ｚｎ合金として、めっき皮膜と塗膜との密着性を改善
した合金化溶融めっき鋼板が広く用いられている。2. Description of the Related Art When a hot-dip galvanized steel sheet is used for automobiles, home appliances, building materials, etc., the galvanized film is made of Fe.
-As a Zn alloy, a galvannealed steel sheet having improved adhesion between a plating film and a coating film is widely used.
【０００３】この合金化溶融めっき鋼板は、通常、母材
となる鋼板を連続炉において予熱し、水素、窒素混合ガ
スで構成される還元雰囲気中で加熱、焼鈍し、めっき浴
温度前後にまで冷却し、溶融亜鉛めっき浴に浸漬してめ
っきし、熱処理炉で４８０〜５５０℃に３〜３０秒保持
してＺｎめっき皮膜をＦｅ−Ｚｎ合金めっき皮膜にして
製造される。連続炉での還元雰囲気の露点が高くなると
不めっきが生じる場合があるので、露点は、通常、−２
０℃以下に調整される。[0003] This alloyed hot-dip coated steel sheet is usually preheated in a continuous furnace in a continuous furnace, heated and annealed in a reducing atmosphere composed of a mixed gas of hydrogen and nitrogen, and cooled to about the plating bath temperature. Then, it is immersed in a hot-dip galvanizing bath, plated, and kept in a heat treatment furnace at 480 to 550 ° C. for 3 to 30 seconds to produce a Zn plating film as an Fe—Zn alloy plating film. When the dew point of the reducing atmosphere in the continuous furnace is high, non-plating may occur.
Adjusted to 0 ° C or less.
【０００４】合金化溶融Ｚｎめっき鋼板の母材には低炭
素Ａｌキルド鋼が多用されてきた。しかし、近年その用
途の拡大に伴って深絞り性が要求されることが多くな
り、母材にＴｉやＮｂを添加した極低炭素鋼を用い、プ
レス成形性を大幅に改善した合金化溶融亜鉛めっき鋼板
が提案されている。この母材としては、重量％で、Ｃ：
≦０．００３％、Ｓｉ：≦０．０４％、Ｍｎ：０．１２
〜０．４０％、Ｐ：０．０１〜０．０５％、Ｓ：０．０
０８〜０．０２％、Ｎ：≦０．０１％、Ａｌ：０．０１
５〜０．０５％、Ｔｉ：０．０２〜０．０６％、Ｎｂ：
≦０．０１５％を含有する鋼が広く用いられている。た
だし、Ｎｂは添加されない場合があり、また、フェライ
ト粒界の脆化防止のために２０ｐｐｍ以下のＢが添加さ
れる場合もある。A low-carbon Al-killed steel has been frequently used as a base material of an alloyed hot-dip galvanized steel sheet. However, in recent years, with the expansion of applications, deep drawability has often been required, and the use of ultra-low carbon steel with Ti or Nb added to the base material has greatly improved the press formability of alloyed molten zinc. Plated steel sheets have been proposed. As the base material, C:
≦ 0.003%, Si: ≦ 0.04%, Mn: 0.12
0.40%, P: 0.01-0.05%, S: 0.0
08-0.02%, N: ≦ 0.01%, Al: 0.01
5 to 0.05%, Ti: 0.02 to 0.06%, Nb:
Steels containing <0.015% are widely used. However, Nb may not be added in some cases, and 20 ppm or less of B may be added in order to prevent embrittlement of ferrite grain boundaries.
【０００５】合金化溶融亜鉛めっき鋼板のプレス成形性
をよくするには、めっき皮膜自体の加工性がよいことが
必要である。合金化処理しためっき皮膜の加工性で特に
問題になるのはパウダリングとフレーキングである。[0005] In order to improve the press formability of an alloyed hot-dip galvanized steel sheet, it is necessary that the plating film itself has good workability. Powdering and flaking are particularly problematic in the workability of the alloyed plating film.
【０００６】パウダリングは、めっき皮膜が圧縮変形を
受けた場合に、めっき皮膜内部で合金層が粉状に砕かれ
て剥離する現象であり、Ｆｅ−Ｚｎ合金相が硬質で脆い
ために生じる。パウダリングが生じると、剥離しためっ
き皮膜片が金型内部に堆積し、金型に対するめっき鋼板
の摺動性を阻害し、割れ不良が生じる原因になる。ま
た、剥離片が堆積して押し込み疵の原因にもなる。一般
に、合金化溶融亜鉛めっき鋼板では、めっき皮膜中のＦ
ｅ含有量を低めに管理することによりパウダリングの発
生を抑制できることが知られている。[0006] Powdering is a phenomenon in which when a plating film undergoes compressive deformation, the alloy layer is crushed into powder and peels off inside the plating film, and is generated because the Fe-Zn alloy phase is hard and brittle. When powdering occurs, the stripped plating film pieces accumulate inside the mold, hindering the slidability of the plated steel sheet with respect to the mold and causing cracking failure. In addition, the separated pieces accumulate and cause indentation flaws. Generally, in an alloyed hot-dip galvanized steel sheet, F
It is known that the occurrence of powdering can be suppressed by controlling the e content to be low.
【０００７】フレーキングは、めっき皮膜表面の摺動性
が悪く、金型との摩擦係数が大きくなったときに、めっ
き皮膜に作用する剪断力によりめっき皮膜が剥離する現
象である。低炭素Ａｌキルド鋼を母材とする合金化溶融
亜鉛めっき鋼板では、めっき皮膜中のＦｅ含有量を高め
てめっき皮膜を硬質にすることで摺動性を改善し、フレ
ーキングを減少させることができる。亜鉛めっき浴中の
Ａｌ含有量を高くすれば、合金化処理が高温でおこなえ
るようになるので、めっき皮膜の合金組成を、より硬質
なδ1 相にしやすくなる。[0007] Flaking is a phenomenon in which the plating film peels off due to the shearing force acting on the plating film when the surface of the plating film has poor slidability and the coefficient of friction with the mold increases. For alloyed hot-dip galvanized steel sheets based on low-carbon Al-killed steel, increasing the Fe content in the plating film to make the plating film harder can improve sliding properties and reduce flaking. it can. If the content of Al in the zinc plating bath is increased, the alloying treatment can be performed at a high temperature, so that the alloy composition of the plating film can be easily changed to a harder δ 1 phase.
【０００８】しかし、極低炭素鋼を母材とし、これにＡ
ｌ含有量が高い亜鉛めっき浴で亜鉛めっきして合金化処
理を施すとめっき皮膜に深い凹部が発生する。この凹部
の発生頻度が増すと、プレス加工時の金型に対するめっ
き鋼板の摺動性が低下し、母材のｒ値や延性が良好であ
っても、プレス加工時に型カジリ不良や割れ不良を生じ
る原因になる。この凹部は、母材として通常の低炭素Ａ
ｌキルド鋼を用いた場合にはあまり発生しないが、Ｔｉ
やＮｂを添加した極低炭素鋼を母材とし、めっき浴中の
有効Ａｌ含有量が０．１３重量％を超える高Ａｌ浴でめ
っきする場合に発生しやすい。このため、自動車用とし
て好適な母材であるＴｉやＮｂを添加した極低炭素鋼を
母材にした、めっき浴中のＡｌ含有量を高め、密着性の
改善とともに表面の凹部の発生を抑制して摺動性を改善
した鋼板は得られていない。However, a very low carbon steel is used as a base material,
When galvanizing is performed in a zinc plating bath having a high l content and subjected to alloying treatment, deep recesses are generated in the plating film. When the frequency of occurrence of these recesses increases, the slidability of the plated steel sheet with respect to the mold at the time of press working decreases, and even if the r-value or ductility of the base material is good, the mold galling failure or cracking failure at the time of press working is reduced. Cause. This recess has a low carbon A content as a base material.
It does not occur so much when using 1-killed steel,
It tends to occur when plating is performed in a high Al bath in which the effective Al content in the plating bath exceeds 0.13% by weight, using an ultra-low carbon steel to which Nb or Nb is added as a base metal. For this reason, the Al content in the plating bath is increased by using a very low carbon steel to which Ti or Nb, which is a suitable base material for automobiles, is added as a base material, thereby improving the adhesion and suppressing the occurrence of concave portions on the surface. Thus, a steel sheet having improved slidability has not been obtained.
【０００９】合金化溶融亜鉛めっき鋼板のめっき皮膜の
表面状態を改善してプレス成形性を向上させる方法が提
案されている。There has been proposed a method of improving the surface condition of a plating film of an alloyed hot-dip galvanized steel sheet to improve press formability.
【００１０】特開平７−１８４０１号公報には、めっき
皮膜の最表層部に形成される凹凸の凹部の深さを３〜１
０μｍ、凸部の高さを３μｍ以下に限定したプレス成形
性と塗装後鮮映性のよい合金化溶融亜鉛めっき鋼板が開
示されている。この鋼板は、めっき前原板の表面粗度と
調質圧延ロールの表面粗度を限定し、幅１ｍ当たり３０
０〜３５０トンの高い圧延荷重のもとで調質圧延して製
造される。しかし、めっき皮膜表面に形成される凹凸形
状は母材の結晶粒径やめっき浴中のＡｌ含有量により大
きく変動する。このため、この方法ではめっき皮膜表面
の凹部の深さは限定できるとしても凹凸の発生頻度が制
御できず、安定した表面形状が得られない。Japanese Patent Application Laid-Open No. 7-18401 discloses that the depth of a concave portion of an unevenness formed in the outermost layer portion of a plating film is 3 to 1
There is disclosed an alloyed hot-dip galvanized steel sheet having a press formability of 0 μm and a height of the projections of 3 μm or less and good visibility after coating. This steel sheet limits the surface roughness of the pre-plated original sheet and the surface roughness of the temper rolling roll to 30
It is manufactured by temper rolling under a high rolling load of 0 to 350 tons. However, the irregularities formed on the plating film surface vary greatly depending on the crystal grain size of the base material and the Al content in the plating bath. For this reason, in this method, even if the depth of the concave portion on the plating film surface can be limited, the frequency of occurrence of the concave and convex cannot be controlled, and a stable surface shape cannot be obtained.
【００１１】特開平７−１８４０２号公報には、合金化
溶融亜鉛めっき鋼板のめっき表層部に、深さ２μｍ以上
の凹部の個数が２００〜８２００／ｍｍ2 、その深さが
２μｍ以上である凹部の長さ比率が３０％〜９０％であ
るめっき皮膜を備えた、プレス成形性と塗装後鮮映性の
よい合金化溶融亜鉛めっき鋼板が開示されている。この
鋼板のめっき皮膜の凹部の発生頻度は、母材表層部の結
晶粒径を母材の化学組成、焼鈍条件または再結晶焼鈍前
の鋼板表面への歪付与等の方法で変更ですることで調整
できるとしている。しかし、めっき皮膜の合金層の成長
速度は母材表面の結晶の面方位によって異なるため、上
述の方法では深さ２μｍ以上の凹部を安定して得ること
はできない。Japanese Patent Application Laid-Open No. 7-18402 discloses that the number of recesses having a depth of 2 μm or more is 200 to 8200 / mm 2 , and the recesses having a depth of 2 μm or more are formed on the surface layer of a galvannealed steel sheet. An alloyed hot-dip galvanized steel sheet having a good press-formability and good post-painting clarity provided with a plating film having a length ratio of 30% to 90% is disclosed. The frequency of occurrence of recesses in the plating film of this steel sheet can be changed by changing the crystal grain size of the surface layer of the base material by the chemical composition of the base material, annealing conditions, or by applying strain to the steel sheet surface before recrystallization annealing. It can be adjusted. However, since the growth rate of the alloy layer of the plating film varies depending on the plane orientation of the crystal on the surface of the base material, the above-described method cannot stably obtain a concave portion having a depth of 2 μm or more.
【００１２】特開平７−１８００１８号公報には、Ｒａ
が０．８μｍ以下の表面粗さのロールを用いて冷延した
母材に、Ａｌを０．１０〜０．２５重量％含有するめっ
き浴を用いてめっきして合金化処理し、Ｒａが０．５μ
以下の表面粗さのロールを用いて調質圧延する、塗装後
鮮映性を有しプレス性および耐パウダリング性に優れた
合金化溶融亜鉛めっき鋼板の製造方法が開示されてい
る。しかし、めっき皮膜の合金層の成長速度は母材表面
の結晶の面方位によって異なるため、上述の方法では表
面形状の制御性は十分ではないうえ、ロールの摩耗によ
る交換頻度が増加し生産性が好ましくない。Japanese Patent Application Laid-Open No. Hei 7-180018 discloses Ra
The base material cold-rolled using a roll having a surface roughness of 0.8 μm or less is plated and alloyed using a plating bath containing 0.10 to 0.25% by weight of Al. .5μ
A method for producing an alloyed hot-dip galvanized steel sheet which has a sharpness after painting, is excellent in pressability and powdering resistance, and is subjected to temper rolling using a roll having the following surface roughness. However, since the growth rate of the alloy layer of the plating film varies depending on the crystal orientation of the crystal of the base material surface, the above-described method does not provide sufficient control over the surface shape, and the frequency of replacement due to roll wear increases, thereby increasing productivity. Not preferred.
【００１３】以上述べたように、特に自動車用途に好適
な極低炭素鋼を母材とした合金化溶融亜鉛めっき鋼板に
おいて、母材の成形性と共にめっき皮膜の摺動性を改善
し、総合的に優れたプレス成形性が発揮できる合金化溶
融亜鉛めっき鋼板は未だ知られていない。As described above, in a galvannealed steel sheet using ultra-low carbon steel as a base material, which is particularly suitable for automotive applications, the formability of the base material and the slidability of the plating film are improved together with the base material. An alloyed hot-dip galvanized steel sheet capable of exhibiting excellent press formability has not yet been known.
【００１４】[0014]
【発明が解決しようとする課題】本発明が解決しようと
する課題は、プレス加工時に良好な摺動性を維持し、パ
ウダリングおよびフレーキングが発生しにくいプレス成
形性に優れる合金化溶融亜鉛めっき鋼板を提供すること
にある。The problem to be solved by the present invention is to provide a hot-dip galvanized alloy which maintains good slidability during press working and is excellent in press formability in which powdering and flaking hardly occur. It is to provide a steel plate.
【００１５】[0015]
【課題を解決するための手段】本発明の要旨は、下記の
合金化溶融亜鉛めっき鋼板にある。The gist of the present invention resides in the following galvannealed steel sheet.
【００１６】表層部の平均結晶粒径が１５μｍ以下、下
記式および式で表される表層部の結晶の（２２２）
面配向性指数が１３以下である母材の少なくとも片面
に、Ｆｅ：８〜１５重量％、Ａｌ：０．１２〜０．５重
量％を含有する亜鉛めっき皮膜を備える合金化溶融亜鉛
めっき鋼板であって、その亜鉛めっき皮膜は、底部のめ
っき厚さが平均のめっき厚さの５０％に満たない凹部
を、断面長さ率で１〜１０％有し、中心線平均粗さで
１．２μｍ以下の表面粗さを備えたものであることを特
徴とするプレス成形性に優れた合金化溶融亜鉛めっき鋼
板。The average crystal grain size of the surface layer portion is 15 μm or less, and (222)
An alloyed hot-dip galvanized steel sheet having a galvanized film containing Fe: 8 to 15% by weight and Al: 0.12 to 0.5% by weight on at least one surface of a base material having a plane orientation index of 13 or less. The galvanized film has a recess having a bottom plating thickness of less than 50% of the average plating thickness in a cross-sectional length ratio of 1 to 10%, and a center line average roughness.
An alloyed hot-dip galvanized steel sheet having excellent press formability, characterized by having a surface roughness of 1.2 μm or less .
【００１７】[0017]
【数１】 (Equation 1)
【００１８】[0018]
【数２】 (Equation 2)
【００１９】但し、Ｉ(XXX) ：Ｘ線回折における(XXX)
面の積分強度 ＩＦ(XXX) ：Ｘ線回折における(XXX) 面の積分強度比率 ＩＦＲ(XXX) ：Ｘ線回折におけるＡＳＴＭカード記載の
(XXX) 面強度比率 通常プレス加工時には鋼板は金型に強い圧力で押しつけ
られる。鋼板と金型との間の摺動抵抗を低減するため
に、両者の接触界面に潤滑作用を持つ油膜などを介在さ
せて界面での摩擦力を低減させる。摺動性を改善するに
は、鋼板表面での油膜の保持能力を維持することが重要
である。鋼板表面に適度の広がりと深さを持つ凹部が適
度の密度で分布していれば、優れた油膜保持性が発揮さ
れる。鋼板表面の箇々の凹部が広すぎると、凹部の中で
油膜切れが生じ摺動性が損なわれる。凹部の数が少なす
ぎても、めっき皮膜表面で保持できる潤滑油量が不足す
るので、同様に油膜が破壊されて摺動性が損なわれる。
亜鉛めっき皮膜は金型に比較してはるかに軟質であるの
で、亜鉛めっき鋼板が金型に強圧されるとめっき皮膜が
塑性流動し、表面の凹凸がつぶされて平滑になりやす
い。したがって、亜鉛めっき鋼板の摺動性を維持するに
は、そのめっき皮膜表面に、金型に強圧されても残存で
きるだけの深さがある凹部が、適度の密度で分布してい
るものが望ましい。However, I (XXX): (XXX) in X-ray diffraction
Integrated intensity of plane IF (XXX): Integrated intensity ratio of (XXX) plane in X-ray diffraction IFR (XXX): ASTM card description in X-ray diffraction
(XXX) Surface strength ratio Normally, a steel plate is pressed against a mold with a strong pressure during press working. In order to reduce the sliding resistance between the steel plate and the mold, a frictional force at the interface is reduced by interposing an oil film or the like having a lubricating action at the contact interface between the two. In order to improve the slidability, it is important to maintain the ability of retaining the oil film on the steel sheet surface. If the concave portions having an appropriate spread and depth are distributed at an appropriate density on the surface of the steel sheet, excellent oil film retention is exhibited. If the recesses on the surface of the steel sheet are too wide, an oil film breaks in the recesses and the slidability is impaired. Even if the number of the concave portions is too small, the amount of lubricating oil that can be held on the plating film surface is insufficient, so that the oil film is similarly broken and slidability is impaired.
Since the galvanized film is much softer than the mold, when the galvanized steel sheet is strongly pressed by the mold, the plated film plastically flows, and the unevenness of the surface is crushed and the surface tends to be smooth. Therefore, in order to maintain the slidability of the galvanized steel sheet, it is desirable that the concave portions having a depth enough to remain even if strongly pressed by the mold are distributed at an appropriate density on the surface of the plating film.
【００２０】図２は、ＴｉとＮｂを添加した極低炭素鋼
を母材とした合金化溶融亜鉛めっき鋼板の、めっき皮膜
表面の凹凸状況の概念を示す断面図である。めっき皮膜
表面には、多数の微小な凹凸に混じって、めっき皮膜表
面が深く陥没した凹部が発生している。この凹部の平面
的な大きさは平均直径で３〜２０μｍであり、母材の鋼
の特定の結晶方位の結晶粒に対応して発生している場合
が多い。本発明者らは、極低炭素Ｔｉ添加鋼をめっき母
材としたときのめっき皮膜の平滑性について検討した結
果、めっき皮膜の平均厚さＨ1 の５０％以上の深さを持
つ凹部１０（以後、単に「５０％凹部」と記す）が、め
っき皮膜表面に適度の頻度で存在すれば、プレス加工な
どに際して鋼板が金型に強圧されても潤滑油が保持され
ることを知見した。FIG. 2 is a cross-sectional view showing the concept of the state of irregularities on the surface of a galvanized steel sheet of an alloyed hot-dip galvanized steel sheet whose base material is an ultra-low carbon steel to which Ti and Nb are added. On the surface of the plating film, a concave portion in which the surface of the plating film is deeply depressed occurs, being mixed with a large number of minute irregularities. The planar size of the concave portion is 3 to 20 μm in average diameter, and is often generated corresponding to a crystal grain having a specific crystal orientation of the base material steel. The present inventors have recesses 10 having a plating smoothness results of investigation of the film, an average thickness of 50% or more of the depth of an H 1 of plated film when the ultra-low carbon Ti added steel and the plating base material ( Hereafter, it has been found that if the “50% concave portion” is present at an appropriate frequency on the surface of the plating film, the lubricating oil is retained even if the steel sheet is strongly pressed into the mold during press working or the like.
【００２１】めっき皮膜の合金化が進展する過程におい
て、通常、母材の結晶粒界では、Ｆｅ−Ｚｎ合金化反応
が急激に進展するバースト反応が生じる。Ｆｅ−Ｚｎ合
金化反応は体積の膨張を伴う。このため、バースト反応
が進展すると、結晶粒界に添って結晶内部よりも盛り上
がった凸部が形成される。また、合金化処理時の母材表
層部でのＦｅ−Ｚｎ拡散反応速度は結晶方位によって異
なり、特にα鉄結晶の（１１１）面では他の結晶面に較
べて合金化反応が遅いことが知られている（例えば、鉄
と鋼、Ｖｏｌ．８０（１９９４）、Ｎｏ８、ｐ７０）。
このため、めっき皮膜表面には、母材の表層部の結晶方
位に応じて凹凸が形成される。上述の５０％凹部は、結
晶粒界を起点として発生するバースト反応部に、合金化
反応速度が遅い結晶方位の結晶表面近傍のＺｎが吸収さ
れるために発生するものと考えられる。したがって、め
っきされる直前のめっき母材表層部の結晶粒径と結晶方
位を調整することで、５０％凹部の形成を最適化でき
る。In the course of the progress of alloying of the plating film, a burst reaction in which the Fe-Zn alloying reaction rapidly progresses usually occurs at the crystal grain boundary of the base material. The Fe—Zn alloying reaction involves volume expansion. For this reason, when the burst reaction progresses, a protruding portion which is higher than the inside of the crystal is formed along the crystal grain boundary. It is also known that the rate of the Fe—Zn diffusion reaction in the surface layer of the base material during the alloying treatment differs depending on the crystal orientation. In particular, the alloying reaction is slower on the (111) plane of the α-iron crystal than on other crystal planes. (For example, iron and steel, Vol. 80 (1994), No. 8, p70).
Therefore, irregularities are formed on the surface of the plating film according to the crystal orientation of the surface layer of the base material. It is considered that the above-described 50% concave portion is generated because Zn in the vicinity of the crystal surface having a crystal orientation with a low alloying reaction rate is absorbed in the burst reaction portion generated from the crystal grain boundary as a starting point. Therefore, by adjusting the crystal grain size and crystal orientation of the surface layer portion of the plating base material immediately before plating, the formation of the 50% concave portion can be optimized.
【００２２】極低炭素Ｔｉ添加鋼を母材とする場合に
は、めっき浴中のＡｌ含有量を高めれば、低炭素Ａｌキ
ルド鋼の場合に較べて、合金化温度が高くできるので、
ζ相（ＦｅＺｎ13）からなる粗大な柱状晶の形成が防止
でき、表面粗さが過度に粗くなるのを防ぐことができ
る。また、ζ相よりも硬質なδ1 相（ＦｅＺｎ7 ）が形
成されるので、耐フレーキング性も向上する。When a very low carbon Ti-added steel is used as a base material, increasing the Al content in the plating bath can increase the alloying temperature as compared with the case of a low carbon Al-killed steel.
The formation of coarse columnar crystals composed of the ζ phase (FeZn 13 ) can be prevented, and the surface roughness can be prevented from becoming excessively rough. Further, since a δ 1 phase (FeZn 7 ) which is harder than the ζ phase is formed, the flaking resistance is also improved.
【００２３】本発明はこれらの知見を基にして完成され
たものである。The present invention has been completed based on these findings.
【００２４】[0024]
【発明の実施の形態】以下に、本発明の実施の形態につ
いて詳細に説明する。なお、以下に記す合金元素の含有
量は重量％で表示する。Embodiments of the present invention will be described below in detail. In addition, the content of the alloy elements described below is indicated by weight%.
【００２５】母材表層部の平均結晶粒径 合金化溶融亜鉛めっき鋼板の母材の表層部の平均結晶粒
径は１５μｍ以下とする。母材の表層部の平均結晶粒径
が１５μｍを超えると、結晶粒界を起点として発生する
バースト部分の間隔が長くなり、凹部の大きさが大きく
なりすぎてめっき皮膜の摺動性が損なわれる。好ましく
は、母材表層部の平均結晶粒径は１２μｍ以下である。
表層の結晶粒径の下限は、特に規定するものではない
が、過度に小さくするのは技術的に困難であるうえ摺動
性に及ぼす影響も飽和するので、５μｍ以上とするのが
よい。Average crystal grain size of base material surface layer The average crystal grain size of the surface layer of the base material of the galvannealed steel sheet is set to 15 μm or less. When the average crystal grain size of the surface layer portion of the base material exceeds 15 μm, the interval between the burst portions generated from the crystal grain boundaries becomes long, and the size of the concave portion becomes too large, thereby impairing the slidability of the plating film. . Preferably, the average crystal grain size of the surface layer portion of the base material is 12 μm or less.
Although the lower limit of the crystal grain size of the surface layer is not particularly specified, it is preferable to be 5 μm or more because it is technically difficult to make the crystal size excessively and the effect on the slidability is saturated.
【００２６】ここで、母材表層部の平均の結晶粒径と
は、母材の表面から観察して認められる結晶粒径を意味
する。めっき鋼板の母材の界面は、例えばインヒビター
を添加した塩酸水溶液などでめっき皮膜を溶解除去する
などの方法で現出させることができる。Here, the average grain size of the surface layer of the base material means a crystal grain size observed from the surface of the base material. The interface of the base material of the plated steel sheet can be revealed by, for example, dissolving and removing the plating film with an aqueous hydrochloric acid solution to which an inhibitor is added.
【００２７】母材の表層部の細粒である領域の深さは、
結晶粒１個分の直径に相当する１５μｍあれば、その効
果が十分に発揮することができる。これは、合金化処理
時のＦｅ−Ｚｎ合金層の形成に影響する母材の範囲が、
合金化処理時に消費されるＦｅ量から、厚くとも母材界
面から５μｍ以内の深さであると推測されるからであ
る。それよりも内部の母材の結晶組織は、母材の成形性
などから必要とされる組織（平均結晶粒径が１５μを超
えるもの）にするのが望ましい。The depth of the region which is a fine grain in the surface portion of the base material is
If the diameter is 15 μm corresponding to the diameter of one crystal grain, the effect can be sufficiently exhibited. This is because the range of the base material that affects the formation of the Fe-Zn alloy layer during the alloying process is
This is because from the amount of Fe consumed during the alloying treatment, it is estimated that the depth is at most 5 μm from the base material interface. It is desirable that the crystal structure of the inner base material be a structure required for the formability of the base material and the like (the average crystal grain size exceeds 15μ).
【００２８】めっき母材表層部の結晶粒径は、母材が亜
鉛めっき浴に浸漬される迄の製造工程で決定される。母
材表層部の結晶粒径は冷間圧延時の圧下率の調整、めっ
き前に施される加熱の前に母材表層部に研削等により残
留応力を付与する、および／または還元焼鈍時の焼鈍温
度の変更などの方法で調整すればよい。The crystal grain size of the surface layer of the plating base material is determined in the manufacturing process until the base material is immersed in the galvanizing bath. The crystal grain size of the base metal surface layer is adjusted by adjusting the rolling reduction during cold rolling, applying residual stress to the base metal surface layer by grinding or the like before heating applied before plating, and / or during reduction annealing. It may be adjusted by a method such as changing the annealing temperature.
【００２９】母材表層部の結晶方位 溶融亜鉛が母材表面と接したときに生じるＦｅとＺｎの
合金化反応速度は、Ｚｎが接している母材表面の結晶方
位によって異なる。この結晶方位が（２２２）またはこ
れに近い方位の結晶面では、Ｆｅ原子の溶出速度が遅い
ため、結晶粒界や他の方位の結晶面よりも合金化が遅れ
る。このため、（２２２）面またはこれに近い方位の結
晶面近傍では５０％凹部が形成されやすい。５０％凹部
の断面長さ率を１０％以下にするために、合金化溶融亜
鉛めっき鋼板のめっきされた母材の表層部の結晶組織の
（２２２）面配向性指数を１３以下、より好ましくは１
０以下とする。ここで（２２２）面配向性指数はランダ
ム方位の鋼板の（２２２）面の解析強度に対する母材表
面の（２２２）面の解析強度の比率であり、下記の式
、から求められる。本発明では、ランダム方位の鋼
板として、ＡＳＴＭカードに記載されている面強度比を
用いる。Crystal Orientation of Base Material Surface Layer The alloying reaction rate of Fe and Zn generated when molten zinc comes into contact with the surface of the base material depends on the crystal orientation of the surface of the base material with which Zn contacts. In a crystal plane having a crystal orientation of (222) or a direction close thereto, alloying is delayed as compared with crystal grain boundaries or crystal planes in other orientations because the elution rate of Fe atoms is low. For this reason, a 50% concave portion is likely to be formed in the vicinity of the (222) plane or a crystal plane having an orientation close thereto. In order to reduce the cross-sectional length ratio of the 50% concave portion to 10% or less, the (222) plane orientation index of the crystal structure of the surface layer portion of the plated base material of the galvannealed steel sheet is preferably 13 or less, more preferably. 1
0 or less. Here, the (222) plane orientation index is a ratio of the analysis strength of the (222) plane of the base material surface to the analysis strength of the (222) plane of the steel sheet having a random orientation, and is obtained from the following equation. In the present invention, the surface strength ratio described in the ASTM card is used as the steel sheet having the random orientation.
【００３０】[0030]
【数１】 (Equation 1)
【００３１】[0031]
【数２】 (Equation 2)
【００３２】但し、Ｉ(XXX) ：Ｘ線回折における(XXX)
面の積分強度 ＩＦ(XXX) ：Ｘ線回折における(XXX) 面の積分強度比率 ＩＦＲ(XXX) ：Ｘ線回折におけるＡＳＴＭカード記載の
(XXX) 面強度比率 但し、鋼板の深絞り性は（２２２）面配向性指数が高い
ほど優れるので、上記の結晶方位の規定は、結晶粒径と
同様の理由により、母材表層から５μｍの深さまで抑制
されていれば、十分効果を発揮する。それよりも内部に
関しては成形性を向上させるために（２２２）面配向性
指数が高いほどよい。Here, I (XXX): (XXX) in X-ray diffraction
Integrated intensity of plane IF (XXX): Integrated intensity ratio of (XXX) plane in X-ray diffraction IFR (XXX): ASTM card description in X-ray diffraction
(XXX) Plane strength ratio However, the higher the (222) plane orientation index is, the better the deep drawability of the steel sheet is. Therefore, the above crystal orientation is defined by 5 μm from the base material surface layer for the same reason as the crystal grain size. If it is suppressed to the depth, the effect is sufficiently exhibited. In order to improve the moldability, the higher the (222) plane orientation index is, the better.
【００３３】上記の配向性指数は、Ｍｏ管球を用いたＸ
線回折において加速電圧３０ｋｖ、電流１００ｍＡの条
件で測定するのが適当である。めっき鋼板から測定対象
の母材の表面を露出させるには、インヒビターを含有す
る酸液でめっき皮膜を除去する方法が適当である。The above-mentioned orientation index is expressed by X using a Mo bulb.
In the line diffraction, it is appropriate to measure under conditions of an acceleration voltage of 30 kv and a current of 100 mA. In order to expose the surface of the base material to be measured from the plated steel sheet, a method of removing the plating film with an acid solution containing an inhibitor is suitable.
【００３４】母材表層部の結晶方位の（２２２）面への
配向性は、結晶粒径と同様、冷延時の圧下率と冷延鋼板
表層部に研削等により所定の残留応力を付与することに
より調整できる。The orientation of the crystal orientation of the surface layer portion of the base material to the (222) plane is, as in the case of the crystal grain size, that a given residual stress is applied to the surface layer portion of the cold-rolled steel sheet by grinding or the like. Can be adjusted.
【００３５】めっき皮膜 めっき皮膜の化学組成：Ｚｎめっき皮膜中にはＦｅを８
〜１５％含有させる。Ｆｅ含有量が８％に満たない場合
には、めっき皮膜の表層部にζ相（ＦｅＺｎ13）が残存
する可能性が高い。めっき皮膜の表層にζ相が残存する
と、ζ相自体が他の合金相に較べて軟質であることと、
表面粗度が大きくなることから、合金化溶融亜鉛めっき
鋼板の摺動性が低下する。また、めっき皮膜中のＦｅ含
有量が１５％を超えるとパウダリング性が大幅に低下す
る。めっき皮膜中のＦｅ含有量は、耐パウダリング性と
耐フレーキング性の両立を図るには、より好ましくは９
〜１２％である。Plating film Chemical composition of plating film: Fe contained 8 in Zn plating film.
-15%. When the Fe content is less than 8%, there is a high possibility that the ζ phase (FeZn 13 ) remains on the surface layer of the plating film. When the ζ phase remains on the surface layer of the plating film, the ζ phase itself is softer than other alloy phases,
Since the surface roughness increases, the slidability of the galvannealed steel sheet decreases. Further, when the Fe content in the plating film exceeds 15%, the powdering property is significantly reduced. The Fe content in the plating film is more preferably 9 in order to achieve both powdering resistance and flaking resistance.
~ 12%.
【００３６】めっき浴に含有されるＡｌは、めっき皮
膜、特に鋼板／めっき皮膜の界面に濃化しＦｅ−Ｚｎ合
金化反応を抑制する作用を有する。皮膜中のＡｌ含有量
が０．１２％未満の場合には、５０％凹部の断面長さ率
は容易に１０％以下に低減できるが、めっき浴中のＡｌ
含有量が低いと、合金化時の合金化速度が速くなり過合
金になるおそれが増すので合金化温度は低めに設定され
る。合金化温度を低くするとζ相からなる粗大柱状晶が
めっき表面に形成される。このため表面粗度が大きくな
り摩擦係数が増すのでＡｌ含有量は０．１２％以上とす
る。Ａｌ含有量が０．５％を超えると合金化速度が遅く
なりすぎて、めっき作業の操業性が大幅に低下する。こ
のため、Ａｌ含有量は０．１２〜０．５％の範囲とす
る。より好ましくは０．２〜０．４％である。Al contained in the plating bath is concentrated at the plating film, particularly at the interface between the steel sheet and the plating film, and has an effect of suppressing the Fe—Zn alloying reaction. When the Al content in the coating is less than 0.12%, the cross-sectional length ratio of the 50% concave portion can be easily reduced to 10% or less.
When the content is low, the alloying speed at the time of alloying is increased and the possibility of over-alloying increases, so the alloying temperature is set lower. When the alloying temperature is lowered, coarse columnar crystals composed of the ζ phase are formed on the plating surface. For this reason, the surface roughness increases and the coefficient of friction increases, so the Al content is set to 0.12% or more. If the Al content exceeds 0.5%, the alloying speed becomes too slow, and the operability of the plating operation is greatly reduced. For this reason, the Al content is in the range of 0.12 to 0.5%. More preferably, it is 0.2 to 0.4%.
【００３７】めっき皮膜の化学組成は、上記の元素以外
はＺｎおよび不可避的不純物である。溶融亜鉛めっきと
共用の亜鉛浴ポットを用いる場合には、溶融亜鉛めっき
鋼板のスパングルを形成する元素であるＰｂ、Ｓｂなど
が亜鉛浴に混入する場合があるが、合金化溶融亜鉛めっ
き鋼板の耐パウダリング性を損なわないためには、不可
避的不純物としてのこれらの元素の亜鉛ポットへの混入
量はいずれも０．０５％以下にするのが望ましい。The chemical composition of the plating film is Zn and inevitable impurities other than the above elements. When a zinc bath pot shared with hot-dip galvanizing is used, Pb, Sb, etc., which are elements that form spangles of hot-dip galvanized steel sheet, may be mixed into the zinc bath. In order not to impair the powdering property, the content of these elements as unavoidable impurities in the zinc pot is desirably 0.05% or less.
【００３８】亜鉛めっき皮膜は、めっき皮膜の平均厚さ
Ｈ1 の５０％以上の深さを持つ凹部を、断面長さ率で１
〜１０％有している。In the zinc plating film, a concave portion having a depth of 50% or more of the average thickness H 1 of the plating film has a cross-sectional length ratio of 1%.
-10%.
【００３９】本発明の５０％凹部の断面長さ率は、図２
に示すように、めっき皮膜の任意の垂直切断面上で、め
っき厚さの５０％の位置でめっき面に平行に引いた長さ
Ｌの線分Ｈm と交わる凹部の長さＤi を求め、線分Ｌに
対するＤi の和の比率（ΣＤi／Ｌ ）を複数の垂直切断
面について求め、これらの算術平均値として算出され
る。The sectional length ratio of the 50% concave portion of the present invention is shown in FIG.
As shown in, on any vertical cut surface of the plating film, obtains the length D i of a recess intersects the line segment H m of length L drawn parallel to the plating surface with 50% of the positions of the plating thickness , the ratio of the sum of D i for the line L a (.SIGMA.D i / L) determined for a plurality of vertical cutting plane, is calculated as these arithmetic mean value.
【００４０】５０％凹部の断面長さ率が１０％を超える
割合で存在すると、めっき皮膜の表面粗度が過度に大き
くなり、摺動性が低下する。他方、この断面長さ率が１
％に満たない場合には、成形時にプレス油が保持できな
くなり、潤滑が不足して型カジリやプレス割れが生じる
おそれが増す。このため５０％凹部の断面長さ率は１〜
１０％とする。好ましくは１〜５％とするのがよい。If the cross-sectional length ratio of the 50% concave portion exceeds 10%, the surface roughness of the plating film becomes excessively large, and the slidability decreases. On the other hand, if this section length ratio is 1
%, Press oil cannot be retained at the time of molding, and lubrication is insufficient, and there is an increased possibility that mold galling and press cracking may occur. Therefore, the cross-sectional length ratio of the 50% concave portion is 1 to
10%. Preferably, it is good to be 1 to 5%.
【００４１】このめっき皮膜中にζ相からなる巨大な柱
状晶が表層に形成されると表面粗度が過度に大きくなり
摺動性には好ましくない。このため、めっき皮膜の表面
粗度は中心線平均粗さで１．２μｍ以下とする。 If giant columnar crystals composed of the ζ phase are formed on the surface layer of the plating film, the surface roughness becomes excessively large, which is not preferable for slidability. For this reason, the surface roughness of the plating film is set to be not more than 1.2 μm in center line average roughness .
【００４２】めっき皮膜の付着量は、特に限定するもの
ではないが、付着量を過度に少なくするのは制御上の問
題が生じる。また、過度に厚くすると加工時にパウダリ
ングが生じるおそれが増す。このため、めっき付着量は
片面当たり３０〜８０ｇ／ｍ2 とするのが望ましい。The amount of the plating film to be deposited is not particularly limited, but an excessively small amount of deposition causes a control problem. On the other hand, if the thickness is too large, the possibility of powdering during processing increases. For this reason, it is desirable that the plating adhesion amount is 30 to 80 g / m 2 per one side.
【００４３】以下に本発明のプレス成形性に優れた合金
化溶融亜鉛めっき鋼板の製造法の概要を説明する。The outline of the method for producing an alloyed hot-dip galvanized steel sheet having excellent press formability according to the present invention will be described below.
【００４４】めっき母材は極低炭素系の冷間圧延鋼板が
望ましいが、これに限定されることはなく、低炭素系の
冷間圧延鋼板や各種の高張力鋼板でも構わない。これら
の母材鋼板は、通常の方法により製鋼され、熱間圧延さ
れ、酸洗され、所定の冷間圧延圧下率で冷間圧延された
後溶融亜鉛めっきされる。溶融亜鉛めっき前に、連続焼
鈍などの方法で必要な再結晶焼鈍を施しても構わない。
溶融亜鉛めっきは、必要に応じて洗浄や表面研削などが
施された後、通常おこなわれている方法で加熱、還元さ
れ、母材が未焼鈍材の場合には焼鈍され、めっき浴の温
度近傍まで冷却され、所定の化学組成のめっき浴に浸漬
されて亜鉛めっきされる。溶融亜鉛めっきされた後は通
常の方法に従って所定の合金化処理温度に加熱され、所
定の時間保持して合金化された後冷却される。合金化処
理時の加熱方法は、輻射加熱、通電加熱、高周波誘導加
熱などいずれの方法でも良い。The base material for the plating is desirably an ultra-low carbon cold rolled steel sheet, but is not limited thereto, and may be a low carbon cold rolled steel sheet or various high tensile steel sheets. These base steel sheets are manufactured by a usual method, hot-rolled, pickled, cold-rolled at a predetermined cold rolling reduction, and then hot-dip galvanized. Prior to hot-dip galvanizing, necessary recrystallization annealing may be performed by a method such as continuous annealing.
Hot-dip galvanizing is, after being subjected to washing and surface grinding as necessary, heated and reduced by a usual method, and is annealed when the base material is an unannealed material, near the temperature of the plating bath. , And immersed in a plating bath having a predetermined chemical composition to perform zinc plating. After the hot-dip galvanizing, the steel sheet is heated to a predetermined alloying treatment temperature in accordance with a usual method, held for a predetermined time, alloyed, and then cooled. As a heating method at the time of the alloying treatment, any method such as radiant heating, electric heating, and high-frequency induction heating may be used.
【００４５】合金化処理が施された後は必要に応じて調
質圧延による材質の調整や、レベリング等による平坦形
状の調整、さらには必要に応じてクロメート処理その他
の通常おこなわれる後処理を施しても構わない。After the alloying treatment, if necessary, the material is adjusted by temper rolling, the flat shape is adjusted by leveling or the like, and if necessary, chromate treatment or other post-treatment which is usually performed is performed. It does not matter.
【００４６】[0046]
（実施例１）表１に示す化学組成からなる厚さ０．７０
ｍｍの冷間圧延鋼板から得た幅１００ｍｍ、長さ２００
ｍｍの母材切り板を用いて合金化溶融亜鉛めっき鋼板を
製造した。(Example 1) Thickness 0.70 having the chemical composition shown in Table 1
100mm width and 200mm length obtained from cold-rolled steel sheet
An alloyed hot-dip galvanized steel sheet was manufactured using a base material having a thickness of 2 mm.
【００４７】[0047]
【表１】 [Table 1]
【００４８】この母材切り板に縦型の溶融Ｚｎめっき装
置を用い、以下の条件でめっきを行った。母材切り板
を、濃度１０重量％、温度７５℃のＮａＯＨ水溶液を用
いて脱脂洗浄し、水素２０体積％、残り窒素からなる露
点−４０℃の雰囲気中で、７６０〜８６０℃に加熱し６
０秒間保持して焼鈍した。焼鈍後、４６０℃近傍まで冷
却し、Ａｌを０．０７〜０．３重量％含有し、残りＺｎ
および不可避的不純物からなる、４６０℃に保たれた亜
鉛めっき浴に浸漬し、２秒間浸漬した後、高圧空気を吹
き付けてめっき付着量を片面当たり６０ｇ／ｍ2 に調整
した。その後、常温まで冷却し、めっき鋼板を５００℃
の塩浴に１５〜３０秒間浸漬して合金化処理を行った。
合金化後０．８％伸び率で調質圧延を施した。Using a vertical hot-dip Zn plating apparatus, the base material was plated under the following conditions. The base metal cutting plate is degreased and washed using a NaOH aqueous solution having a concentration of 10% by weight and a temperature of 75 ° C, and heated to 760 to 860 ° C in an atmosphere of 20% by volume of hydrogen and a dew point of -40 ° C consisting of the remaining nitrogen.
It was annealed while holding for 0 seconds. After annealing, it is cooled to around 460 ° C., contains 0.07 to 0.3% by weight of Al,
It was immersed in a galvanizing bath maintained at 460 ° C. and kept at 460 ° C. and immersed for 2 seconds, and then sprayed with high-pressure air to adjust the coating weight to 60 g / m 2 per side. After that, it is cooled down to room temperature,
For 15 to 30 seconds to perform an alloying treatment.
After alloying, temper rolling was performed at an elongation of 0.8%.
【００４９】一部の母材切り板については、冷間圧延圧
下率、未焼鈍母材の表面をブラシ研削して残留応力を付
加する、または、焼鈍温度を変更する、等の方法により
（２２２）面配向性指数を変更した。また、めっき浴中
のＡｌ含有量、めっき浴に浸漬される母材切り板の温度
などを変更してめっき皮膜の５０％凹部の断面長さ率を
変更した。For some of the base metal cut plates, a cold rolling reduction ratio, a residual stress is applied by brush grinding the surface of the unannealed base material, or an annealing temperature is changed (222). ) The plane orientation index was changed. Also, the cross-sectional length ratio of the 50% concave portion of the plating film was changed by changing the Al content in the plating bath, the temperature of the base metal plate immersed in the plating bath, and the like.
【００５０】調質圧延後の鋼板（以下、「合金化鋼板」
と記す）から２５ｍｍφの試料片を採取し、インヒビタ
ーを０．５容積％含有した１０％塩酸水溶液でめっき皮
膜を溶解し、この溶解液を誘導結合高周波プラズマ分光
分析法（ＩＣＰ法）でめっき皮膜の化学組成を求めると
ともに、得られた母材の表層部の結晶方位をＸ線回折法
により求めた。Steel sheet after temper rolling (hereinafter referred to as “alloyed steel sheet”)
), A plating film was dissolved in a 10% hydrochloric acid aqueous solution containing 0.5% by volume of an inhibitor, and the solution was plated by inductive coupling high frequency plasma spectroscopy (ICP method). And the crystal orientation of the surface layer of the obtained base material was determined by an X-ray diffraction method.
【００５１】５０％凹部の断面長さ率は、合金化鋼板の
垂直切断面を研磨し、その研磨面を走査型電子顕微鏡に
よって倍率５００倍で観察し、めっき皮膜の平均厚さの
５０％の位置で、めっき皮膜表面に平行な長さ５００μ
ｍの仮想した線分の間に観察される凹部の長さを測定
し、それらの和の５００μｍに対する比率として算出し
た。このような測定を任意の方向に切断した５個の切断
面について実施し、その平均値を求めた。The cross-sectional length ratio of the 50% concave portion was determined by polishing a vertically cut surface of the alloyed steel plate, observing the polished surface with a scanning electron microscope at a magnification of 500 times, and measuring 50% of the average thickness of the plating film. 500μ length parallel to the plating film surface at the position
The lengths of the recesses observed between the m imaginary line segments were measured and calculated as the ratio of the sum of them to 500 μm. Such a measurement was performed on five cut surfaces cut in arbitrary directions, and the average value was obtained.
【００５２】めっき皮膜の耐パウダリング性を下記の方
法で求めた。The powdering resistance of the plating film was determined by the following method.
【００５３】合金化鋼板から直径６０ｍｍの円盤を打ち
抜き、動粘度１０．５ｍｍ2 ／ｓの防錆油（出光興産製
ＳＫＷ９２）を２ｇ／ｍ2 塗油し、ポンチ直径：３０ｍ
ｍ、ダイス直径：３５．４ｍｍ、ダイス型半径：３Ｒ、
しわ押さえ力：５００ｋｇｆで円筒絞り試験を行った。
得られた成形品に付着している剥離しためっき皮膜片を
アセトンによる溶剤脱脂で除去した後、成形品の重量を
測定し、円筒絞り前の重量との差からめっき皮膜のパウ
ダリング量を測定した。パウダリング量は、１個当たり
２５ｍｇ以下の場合を良好と判断した。A disc having a diameter of 60 mm was punched from an alloyed steel sheet, and 2 g / m 2 of rust-preventive oil (SKW92 manufactured by Idemitsu Kosan) having a kinematic viscosity of 10.5 mm 2 / s was applied, and the punch diameter was 30 m.
m, die diameter: 35.4 mm, die shape radius: 3R,
A cylinder drawing test was performed at a wrinkle holding force of 500 kgf.
After removing the peeled plating film pieces adhering to the obtained molded product by solvent degreasing with acetone, the weight of the molded product is measured, and the powdering amount of the plating film is measured from the difference from the weight before the cylindrical drawing. did. A powdering amount of 25 mg or less per piece was judged to be good.
【００５４】図１は、合金化鋼板の摺動性を評価するた
めに用いた高面圧Ｕ溝成形試験法の概念を示す図であ
る。ダイ４の間隔Ｈd は３２ｍｍ、ダイの肩半径Ｒd は
５ｍｍである。ポンチ２の幅Ｈp ：３０ｍｍ、長さ：６
０ｍｍ、ポンチの肩半径Ｒp は５ｍｍである。ブランク
ホルダー３には、半径５ｍｍの半円柱状のしわ押さえ５
が設けられている。ポンチ２とブランクホルダー３には
それぞれ独立に圧力が調節可能な加圧装置（図示せず）
が設けられている。これらの工具の表面は＃６００のエ
メリー紙を用いて、互いに直交する２方向に研磨されて
いる。FIG. 1 is a view showing the concept of a high surface pressure U groove forming test method used for evaluating the slidability of an alloyed steel sheet. Distance H d of the die 4 is 32 mm, the shoulder radius R d of the die is 5 mm. Punch 2 width Hp : 30 mm, length: 6
0mm, the shoulder radius R p of the punch is 5mm. The blank holder 3 has a semi-cylindrical wrinkle holder 5 having a radius of 5 mm.
Is provided. A pressurizing device (not shown) in which the pressure can be adjusted independently for the punch 2 and the blank holder 3.
Is provided. The surfaces of these tools are polished in two directions orthogonal to each other using # 600 emery paper.
【００５５】この高面圧Ｕ溝成形試験機に、合金化鋼板
から採取した幅：３０ｍｍ、長さ：２７０ｍｍの試験片
に防錆油（出光興産製ＳＫＷ９２）を２ｇ／ｍ2 の割合
で塗布して、ダイ４とブランクホルダー３の間にこの試
験片をセットし、ブランクホルダー力Ｐを種々変更して
ポンチとダイによってＵ字形に成形した。ブランクホル
ダー力Ｐは７５０〜１５００ｋｇｆの範囲で変更した。
ポンチの圧入速度は６０ｍｍ／分とした。ポンチ圧入時
の最大荷重Ｆmax.を求め、摩擦係数μをμ＝ｄＦmax.／
（２ｄＰ）により求めた。この評価方法では摩擦係数が
０．２３以下であれば摺動性が良好と判断した。A rust-preventive oil (SKW92, manufactured by Idemitsu Kosan Co., Ltd.) was applied at a rate of 2 g / m 2 to a test piece having a width of 30 mm and a length of 270 mm sampled from an alloyed steel plate on this high surface pressure U-groove forming tester. Then, this test piece was set between the die 4 and the blank holder 3, and the blank holder force P was variously changed to form a U-shape with a punch and a die. The blank holder force P was changed in the range of 750 to 1500 kgf.
The punch injection speed was 60 mm / min. Seeking the maximum load F max. At punch press fitting, a friction coefficient μ μ = dF max. /
(2dP). In this evaluation method, if the coefficient of friction was 0.23 or less, it was determined that the slidability was good.
【００５６】これらの測定結果を表２に示した。Table 2 shows the results of these measurements.
【００５７】[0057]
【表２】 [Table 2]
【００５８】表２に示されているように、本発明の規定
する条件範囲を満たす試番１〜１０はいずれも良好なパ
ウダリング性と摺動性を示している。これに対し、めっ
き皮膜中のＦｅ含有量が高すぎた試番１５はパウダリン
グが好ましくない。また、５０％凹部の断面長さ率が高
すぎる試番１１、１２、１３、１７および低すぎる試番
１６は摩擦係数が高く、摺動性が好ましくない。試番１
４では、めっき皮膜中のＦｅ含有量が不足したために摺
動性が低下した。As shown in Table 2, Test Nos. 1 to 10 satisfying the condition range specified by the present invention all show good powdering properties and sliding properties. On the other hand, the powder No. 15 in which the Fe content in the plating film is too high is not preferable. In addition, Test Nos. 11, 12, 13, and 17 in which the cross-sectional length ratio of the 50% concave portion is too high and Test No. 16 in which the cross-sectional length ratio is too low have a high coefficient of friction and poor slidability. Trial number 1
In No. 4, the slidability was reduced due to an insufficient Fe content in the plating film.
【００５９】[0059]
【発明の効果】本発明の合金化溶融亜鉛めっき鋼板は、
平均のめっき皮膜厚さの５０％以上の深さの凹部を適度
の比率で有するので、プレス成形時の潤滑油の保持性が
優れる。このため鋼板の摺動性に優れ、過酷な加工を受
けても割れや型カジリが発生しにくい。また、めっき皮
膜中のＡｌ含有量を高めているので、プレス加工時にパ
ウダリングおよびフレーキングが発生しにくく、良好な
プレス成形性が発揮される。The alloyed hot-dip galvanized steel sheet of the present invention comprises:
Since the concave portions having a depth of 50% or more of the average plating film thickness are provided at an appropriate ratio, the lubricating oil retention during press molding is excellent. For this reason, the sliding property of the steel sheet is excellent, and cracking and mold galling hardly occur even under severe processing. In addition, since the Al content in the plating film is increased, powdering and flaking hardly occur during press working, and good press formability is exhibited.
【図１】めっき試験片の摺動性を評価するために用いる
高面圧Ｕ溝成形試験法の概念を示す図である。FIG. 1 is a view showing the concept of a high surface pressure U-groove forming test method used for evaluating the slidability of a plating test piece.
【図２】ＴｉとＮｂを含有した極低炭素鋼を母材とした
合金化溶融亜鉛めっき鋼板のめっき皮膜の凹凸状況の概
念を示す断面図である。FIG. 2 is a cross-sectional view showing the concept of the state of unevenness of a plating film of an alloyed hot-dip galvanized steel sheet using a very low carbon steel containing Ti and Nb as a base material.
１・・・鋼板、２・・・ポンチ、３・・・ブランクホル
ダー、４・・・ダイ、５・・・押さえビード、10・・・
５０％凹部、Ｈ1・・・平均めっき厚、Ｈm・・・平均め
っき厚の５０％の位置。1 ... steel plate, 2 ... punch, 3 ... blank holder, 4 ... die, 5 ... holding bead, 10 ...
50% recess, H 1 ... Average plating thickness, H m .. 50% of average plating thickness.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 広瀬 洋三 大阪府大阪市中央区北浜４丁目５番33号 住友金属工業株式会社内 (58)調査した分野(Int.Cl.7，ＤＢ名) C23C 2/00 - 2/40 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yozo Hirose 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. (58) Field surveyed (Int. Cl. 7 , DB name) C23C 2/00-2/40
Claims (1)
記式および式で表される表層部の結晶の（２２２）
面配向性指数が１３以下である母材の少なくとも片面
に、Ｆｅ：８〜１５重量％、Ａｌ：０．１２〜０．５重
量％を含有する亜鉛めっき皮膜を備える合金化溶融亜鉛
めっき鋼板であって、その亜鉛めっき皮膜は、めっき厚
さが平均のめっき厚さの５０％に満たない凹部を断面長
さ率で１〜１０％有し、中心線平均粗さで１．２μｍ以
下の表面粗さを備えたものであることを特徴とするプレ
ス成形性に優れた合金化溶融亜鉛めっき鋼板。 【数１】 【数２】 但し、Ｉ(XXX) ：Ｘ線回折における(XXX) 面の積分強度 ＩＦ(XXX) ：Ｘ線回折における(XXX) 面の積分強度比率 ＩＦＲ(XXX) ：Ｘ線回折におけるＡＳＴＭカード記載の
(XXX) 面強度比率An average crystal grain size of the surface layer portion is 15 μm or less, and the following formula and the formula (222)
An alloyed hot-dip galvanized steel sheet having a galvanized film containing Fe: 8 to 15% by weight and Al: 0.12 to 0.5% by weight on at least one surface of a base material having a plane orientation index of 13 or less. The galvanized film has a recess having a plating thickness of less than 50% of the average plating thickness in a sectional length ratio of 1 to 10% and a center line average roughness of 1.2 μm or less.
An alloyed hot-dip galvanized steel sheet having excellent press formability, characterized by having the following surface roughness . (Equation 1) (Equation 2) Where I (XXX): integrated intensity of (XXX) plane in X-ray diffraction IF (XXX): integrated intensity ratio of (XXX) plane in X-ray diffraction IFR (XXX): described in ASTM card in X-ray diffraction
(XXX) Surface strength ratio
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19531097A JP3201312B2 (en) | 1997-07-22 | 1997-07-22 | Galvannealed steel sheet with excellent press formability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19531097A JP3201312B2 (en) | 1997-07-22 | 1997-07-22 | Galvannealed steel sheet with excellent press formability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1136058A JPH1136058A (en) | 1999-02-09 |
| JP3201312B2 true JP3201312B2 (en) | 2001-08-20 |
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ID=16339036
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19531097A Expired - Fee Related JP3201312B2 (en) | 1997-07-22 | 1997-07-22 | Galvannealed steel sheet with excellent press formability |
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| Country | Link |
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| JP (1) | JP3201312B2 (en) |
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