JPH09310163A - High strength galvanized steel sheet excellent in press workability and plating adhesion - Google Patents
High strength galvanized steel sheet excellent in press workability and plating adhesionInfo
- Publication number
- JPH09310163A JPH09310163A JP14791096A JP14791096A JPH09310163A JP H09310163 A JPH09310163 A JP H09310163A JP 14791096 A JP14791096 A JP 14791096A JP 14791096 A JP14791096 A JP 14791096A JP H09310163 A JPH09310163 A JP H09310163A
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- Prior art keywords
- steel sheet
- plating
- oxide
- oxides
- hot
- 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.)
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- Coating With Molten Metal (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明はプレス加工性及びメ
ッキ密着性に優れる高強度溶融亜鉛メッキ鋼板に関し、
自動車車体用などに用いられ、かつ必要に応じて合金化
処理を施した高強度溶融亜鉛メッキ鋼板に関する。TECHNICAL FIELD The present invention relates to a high-strength galvanized steel sheet having excellent press workability and plating adhesion,
The present invention relates to a high-strength hot-dip galvanized steel sheet used for automobile bodies and the like, and optionally subjected to alloying treatment.
【０００２】[0002]
【従来の技術】近年、排気ガス規制の観点から自動車車
体の軽量化が必要となっている。車体の軽量化の有効な
手段の一つとして板厚を薄くするという方法があるが、
安全性確保のため板厚を薄くする分、板の強度を向上さ
せる必要がある。そのため、鋼中にＳｉ、Ｍｎ、Ｃｒ、
Ｐなどの固溶強化元素を複合化したり、もしくは主とし
てＣ、Ｍｎを添加するなどして鋼板の高強度化が図られ
ている。2. Description of the Related Art In recent years, it has become necessary to reduce the weight of automobile bodies from the viewpoint of exhaust gas regulations. One of the effective ways to reduce the body weight is to reduce the thickness of the body.
In order to ensure safety, it is necessary to improve the strength of the board by reducing the board thickness. Therefore, Si, Mn, Cr,
It has been attempted to increase the strength of a steel sheet by compounding solid solution strengthening elements such as P or mainly adding C and Mn.
【０００３】前者の鋼板はＳｉを０．１ｗｔ％以上、Ｍ
ｎを０．５ｗｔ％以上添加するなど、主としてＳｉ、Ｍ
ｎの複合添加によって鋼板の高強度化を図るタイプの高
強度鋼板であり、また後者はＳｉをほとんど添加せず代
わりにＭｎを０．５ｗｔ％以上添加し、かつＣを０．０
３％以上添加してやることにより高強度化を図るタイプ
の高強度鋼板であり、両者とも自動車車体の軽量化を目
的とした鋼板である。そのため、これらの鋼板にメッキ
を施すことにより機械的特性並びに防錆性の優れる表明
処理鋼板が得られることになる。高強度鋼板は冷間圧延
後に優れた材質を確保するため通常８００℃以上の高温
で焼鈍する必要がある。The former steel sheet contains 0.1 wt% or more of Si and M
n, 0.5% by weight or more, such as Si, M
It is a high-strength steel sheet of the type that aims to increase the strength of the steel sheet by the composite addition of n, and the latter does not add Si at all but 0.5 wt% or more of Mn, and 0.0% of C.
It is a high-strength steel sheet of a type that is strengthened by adding 3% or more, and both steel sheets are intended to reduce the weight of an automobile body. Therefore, by plating these steel sheets, an expression-treated steel sheet excellent in mechanical properties and rust prevention can be obtained. The high-strength steel sheet usually needs to be annealed at a high temperature of 800 ° C. or higher in order to secure an excellent material after cold rolling.
【０００４】また耐食性を付与するためにはその後メッ
キや化成処理などを施す。通常、還元焼鈍はＮ2-Ｈ 2雰
囲気で行う。この雰囲気はＦｅにとっては還元性の雰囲
気であっても、Ｓｉ、Ｍｎ、Ｃｒ、Ｐなどにとっては酸
化性の雰囲気である。そのため、これらの元素は選択的
に酸化されて酸化物となり鋼板表面に濃化する。この鋼
板に溶融亜鉛メッキを施す場合、これらの酸化物が溶融
亜鉛との濡れ性を低下させ、結果として鋼板表面でいわ
ゆる不メッキをしばしば引き起こす。また鋼板の脱脂、
酸洗によってもこれらの酸化物は完全には除去できない
ため、一度、連続焼鈍炉（Ｃｏｎｔｉｎｕｏｕｓ Ａｎ
ｎｅａｌｉｎｇ Ｌｉｎｅ：ＣＡＬ）を通した後に改め
て溶融亜鉛メッキを施してもこれら不メッキの発生を完
全には抑えることはできない。その結果として、先に述
べた高強度鋼板、すなわちＳｉ、Ｍｎ、Ｃｒ、Ｐなどの
固溶強化元素を複合添加した高強度鋼板、及び、主とし
てＣ、Ｍｎを添加するなどして高強度化を図るタイプの
高強度鋼板の、何れのタイプの高強度鋼板に溶融亜鉛メ
ッキを施すことは困難であるため、結果として、プレス
加工性及びメッキ密着性に優れる高強度溶融亜鉛メッキ
鋼板を製造することは困難であった。Further, in order to impart corrosion resistance, plating or chemical conversion treatment is then performed. Generally, reduction annealing is performed in an N 2 —H 2 atmosphere. Although this atmosphere is a reducing atmosphere for Fe, it is an oxidizing atmosphere for Si, Mn, Cr, P and the like. Therefore, these elements are selectively oxidized to form oxides, which are concentrated on the surface of the steel sheet. When this steel sheet is subjected to hot dip galvanizing, these oxides reduce the wettability with hot dip zinc, and as a result often cause so-called non-plating on the surface of the steel sheet. Also degreasing of steel sheets,
Since these oxides cannot be completely removed by pickling, the continuous annealing furnace (Continuous An
Even if hot-dip galvanizing is performed again after passing through the nealing line (CAL), the occurrence of such non-plating cannot be completely suppressed. As a result, the high-strength steel sheet described above, that is, the high-strength steel sheet to which solid solution strengthening elements such as Si, Mn, Cr, and P are added in a complex manner, and C and Mn are mainly added to enhance the strength. Since it is difficult to apply hot dip galvanizing to any type of high strength steel plate of the type intended, it is necessary to produce a high strength hot dip galvanized steel plate having excellent press workability and plating adhesion. Was difficult.
【０００５】これらを改善する従来の方法の一つとし
て、特公昭６１−９３８６号公報のように、溶融メッキ
に先立って鋼板の表面にＮｉの下地メッキを施す方法が
ある。しかしこの方法では、Ｓｉを０．１ｗｔ％以上
３．０ｗｔ％以下含有する鋼板、もしくはＣを０．０３
〜０．１０ｗｔ％、Ｓｉを０．００１〜０．１０ｗｔ
％、Ｍｎを０．５〜２．０ｗｔ％、Ｐを０．００１〜
０．１０ｗｔ％、Ｍｏを０．５０ｗｔ％以下、それぞれ
含有する鋼板を対象とする場合付着量が１０ｇ／ｍ2以
上のＮｉメッキを施すことが必要になるためコストの上
昇を招くほか、このような大量のＮｉメッキを施した場
合には、溶融亜鉛メッキの濡れ性は改善されるものの、
合金化過程でメッキ表面にＳｉ、Ｎｉに起因する欠陥が
多発するという問題が生じる。As one of the conventional methods for improving these, there is a method of applying Ni undercoat on the surface of a steel sheet prior to hot dipping, as in Japanese Patent Publication No. 61-9386. However, in this method, a steel sheet containing 0.1 wt% or more and 3.0 wt% or less of Si or C of 0.03
~ 0.10wt%, Si 0.001 ~ 0.10wt
%, Mn 0.5-2.0 wt%, P 0.001-
When targeting steel plates containing 0.10 wt% and Mo of 0.50 wt% or less, it is necessary to perform Ni plating with an adhesion amount of 10 g / m 2 or more, which causes an increase in cost. When a large amount of Ni plating is applied, the wettability of hot dip galvanizing is improved,
In the alloying process, there arises a problem that many defects due to Si and Ni occur on the plating surface.
【０００６】このＮｉメッキ以外にも、例えば特開昭５
７−７０２６８号公報のように、溶融メッキに先立って
鋼板の表面にＦｅの下地メッキを施す方法がある。この
方法でも、下地メッキによってＳｉ添加鋼の不メッキを
防止することは可能であるが、そのためには５ｇ／ｍ2
以上のＦｅのメッキをする必要があり、極めて不経済的
である。Other than this Ni plating, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Publication No. 7-70268, there is a method of applying Fe undercoat on the surface of a steel sheet prior to hot dipping. Even with this method, it is possible to prevent the non-plating of the Si-added steel by the base plating, but for that purpose, 5 g / m 2
It is necessary to plate the above Fe, which is extremely uneconomical.
【０００７】さらに、他の方法としては、特開昭５５−
１２２８６５号公報や特開平４−２５４５３１号公報の
ように、あらかじめ鋼板を酸化して鉄酸化膜を形成さ
せ、その後還元焼鈍することにより合金元素の酸化物皮
膜の形成を抑制してメッキする方法がある。この方法
は、還元焼鈍でメッキ前に残存する鉄酸化膜厚量を一定
値以下に制御する方法であるため、還元焼鈍で還元され
すぎてしまい、合金元素が表面濃化してメッキ性が不良
となる問題、すなわち酸化膜と還元量とのバランスが崩
れるという問題がある。それに、この還元されすぎを防
ぐには膨大な鉄酸化物量が必要になるため、ロールなど
によって鉄酸化物が剥離してしまい、その後の還元焼鈍
時に合金元素の選択酸化が起こってメッキ性が阻害され
たり、剥離した鉄酸化物皮膜が炉内に散乱して操業に悪
影響を及ぼすという問題がある。このようなことから、
自動車用高強度材料として魅力のある高強度鋼板も、こ
れを溶融メッキするための実際的な手段を欠いているの
が実情である。Furthermore, as another method, Japanese Patent Laid-Open No. 55-
As disclosed in Japanese Patent No. 122865 and Japanese Patent Laid-Open No. 4-254531, there is a method in which a steel plate is previously oxidized to form an iron oxide film, and then reduction annealing is performed to suppress the formation of an oxide film of an alloy element and perform plating. is there. Since this method is a method of controlling the iron oxide film thickness remaining before plating by reduction annealing to be a certain value or less, it is excessively reduced by reduction annealing, and the alloy element is concentrated on the surface to cause poor plating property. However, there is a problem that the balance between the oxide film and the reduction amount is lost. In addition, since a huge amount of iron oxide is required to prevent this excessive reduction, the iron oxide is peeled off by rolls, etc., and selective oxidation of alloying elements occurs during subsequent reduction annealing, which hinders plating performance. There is a problem that the iron oxide film that is peeled off or peeled off is scattered in the furnace and adversely affects the operation. From such a thing,
High-strength steel sheets, which are attractive as high-strength materials for automobiles, also lack practical means for hot-dip coating.
【０００８】[0008]
【発明が解決しようとする課題】本発明はこのような実
状に基づいてなされたもので、Ｓｉを０．１ｗｔ％以上
３．０ｗｔ％以下含有する鋼板、もしくはＣを０．０３
〜０．１０ｗｔ％、Ｓｉを０．００１〜０．１０ｗｔ％
未満、Ｍｎを０．５〜２．０ｗｔ％、Ｐを０．００１〜
０．１０ｗｔ％、Ｍｏを０．５０ｗｔ％以下、それぞれ
含有する鋼板を母材として、溶融メッキ時の不メッキを
生じさせることなくメッキすることができ、かつ、プレ
ス加工性およびメッキ密着性に優れた高強度溶融亜鉛メ
ッキ鋼板又は合金化溶融亜鉛メッキ鋼板を提供すること
が本発明の課題である。The present invention has been made based on such an actual situation, and is a steel plate containing 0.1 wt% or more and 3.0 wt% or less of Si, or 0.03 C of C.
~ 0.10 wt%, Si 0.001-0.10 wt%
Less, Mn 0.5-2.0 wt%, P 0.001-
A steel plate containing 0.10 wt% and Mo of 0.50 wt% or less can be plated as a base material without causing non-plating during hot dipping, and is excellent in press workability and plating adhesion. It is an object of the present invention to provide a high strength galvanized steel sheet or an alloyed hot dip galvanized steel sheet.
【０００９】[0009]
【課題を解決するための手段】Ｓｉ，Ｍｎ等の固溶強化
元素が複合添加されている高強度鋼をメッキする場合、
これらが表面濃化し皮膜を形成して溶融亜鉛との濡れ性
を阻害するため不メッキが発生する。そこで、高強度鋼
板にメッキを施す場合、この表面濃化を抑制することが
必要となる。表面濃化量とメッキ性、合金化速度には相
関があり、表面濃化量の少ない方がめっき性がよくなる
し、合金化速度は速くなることが確認されている。Means for Solving the Problems When plating high strength steel to which solid solution strengthening elements such as Si and Mn are added,
Non-plating occurs because these thicken the surface and form a film to impede the wettability with molten zinc. Therefore, when plating is applied to a high strength steel plate, it is necessary to suppress this surface concentration. It has been confirmed that there is a correlation between the amount of surface concentration, the plating property and the alloying rate, and the smaller the amount of surface concentration, the better the plating property and the faster the alloying rate.
【００１０】表面濃化を抑制するための鋼板の表面構造
の詳細な検討を行ったところ、Ｓｉを０．１ｗｔ％以
上、３．０％以下含有する高強度鋼板もしくはＣを０．
０３〜０．１０ｗｔ％、Ｓｉを０．００１〜０．１０ｗ
ｔ％未満、Ｍｎを０．５〜２．０ｗｔ％、Ｐを０．０１
〜０．１０ｗｔ％、Ｍｏを０．５０ｗｔ％以下をそれぞ
れ含有する高強度鋼板の表層の結晶粒界、あるいは結晶
粒内、あるいは結晶粒界および結晶粒内に予めＳｉＯ
2 、ＭｎＯ、ＦｅＳｉＯ3 、Ｆｅ2 ＳｉＯ4 、ＭｎＳｉ
Ｏ3 、Ｍｎ2 ＳｉＯ4 、Ｐ2 Ｏ5 などの酸化物を生成さ
せておくと、Ｃ、Ｓｉ、Ｍｎ、Ｐ、Ｃｒなどの強化元素
が複合添加されている高強度鋼板の溶融メッキ性を飛躍
的に向上させることが可能となることを我々は見出し
た。A detailed examination of the surface structure of the steel sheet for suppressing the surface thickening revealed that a high strength steel sheet containing 0.1 wt% or more and 3.0% or less of Si or C.
03-0.10wt%, Si 0.001-0.10w
less than t%, Mn 0.5 to 2.0 wt%, P 0.01
.About.0.10 wt% and Mo in an amount of 0.50 wt% or less.
2 , MnO, FeSiO 3 , Fe 2 SiO 4 , MnSi
When oxides such as O 3 , Mn 2 SiO 4 and P 2 O 5 are generated, the hot dip galvanizability of high strength steel plates to which strengthening elements such as C, Si, Mn, P and Cr are added in combination is improved. We have found that it can be dramatically improved.
【００１１】本発明はこれらの知見に基いて完成された
もので、その技術手段はＣ、Ｓｉ、Ｍｎなどの固溶強化
元素が複合添加されている高強度鋼板のメッキ層直下の
高強度鋼板の表層の結晶粒界、あるいは結晶粒内、ある
いは結晶粒界および結晶粒内に酸化物を有することを特
徴とするプレス加工性及びメッキ密着性に優れる高強度
溶融亜鉛メッキ鋼板、及びこのような高強度溶融亜鉛メ
ッキ鋼板がさらに合金化されているプレス加工性及びメ
ッキ密着性に優れる合金化高強度溶融亜鉛メッキ鋼板に
ある。The present invention has been completed based on these findings, and its technical means is a high-strength steel sheet immediately below a plating layer of a high-strength steel sheet to which solid solution strengthening elements such as C, Si, and Mn are added in combination. A high-strength hot-dip galvanized steel sheet having excellent press workability and plating adhesion, characterized by having an oxide in the crystal grain boundary of the surface layer, or in the crystal grain, or in the crystal grain boundary and the crystal grain, and such a The high-strength hot-dip galvanized steel sheet is further alloyed. It is an alloyed high-strength hot-dip galvanized steel sheet having excellent press workability and plating adhesion.
【００１２】すなわち、本発明の第１発明は、Ｓｉを
０．１ｗｔ％以上、３．０ｗｔ％以下含有する高強度鋼
板の表層の結晶粒界及び／又は結晶粒内に酸化物を有す
ることを特徴とするプレス加工性及びメッキ密着性に優
れる高強度溶融亜鉛メッキ鋼板である。この場合、酸化
物は、Ｓｉの酸化物、Ｆｅ酸化物、その両者又はＳｉと
Ｆｅの複合酸化物である。That is, the first aspect of the present invention is that a high-strength steel sheet containing Si in an amount of 0.1 wt% or more and 3.0 wt% or less has an oxide in the grain boundaries and / or crystal grains in the surface layer. It is a high-strength galvanized steel sheet with excellent press workability and plating adhesion. In this case, the oxide is an oxide of Si, an oxide of Fe, both of them, or a composite oxide of Si and Fe.
【００１３】本発明の第２の発明は、 Ｃ：０．０３〜０．１０ｗｔ％ Ｓｉ：０．００１〜０．１０ｗｔ％未満 Ｍｎ：０．５〜２．０ｗｔ％ Ｐ：０．０１〜０．１０ｗｔ％ Ｍｏ：０．５０ｗｔ％以下 を含有する高強度鋼板の表層の結晶粒界及び／又は結晶
粒内に酸化物を有することを特徴とするプレス加工性及
びメッキ密着性に優れる高強度溶融亜鉛メッキ鋼板であ
る。この場合、酸化物は、Ｓｉ、Ｍｎ、Ｐ、Ｆｅのうち
少なくとも１種を含む酸化物もしくはＳｉ、Ｍｎ、Ｐ、
Ｆｅの複数を含む複合酸化物である。上記第１、第２の
発明において、上記酸化物がＳｉＯ2 、ＭｎＯ、ＦｅＳ
ｉＯ3 、Ｆｅ2 ＳｉＯ4 、ＭｎＳｉＯ3 、Ｍｎ2 ＳｉＯ
4 及びＰ2 Ｏ5 からなる群から選ばれた１種以上であ
り、前記酸化物の分布範囲が表層から０．１〜１００μ
ｍであると好適であり、前記鋼板がさらに加熱合金化処
理されていると、一層すぐれたプレス加工性及びメッキ
密着性に優れる高強度合金化溶融亜鉛メッキ鋼板を得る
ことができる。A second aspect of the present invention is C: 0.03 to 0.10 wt% Si: 0.001 to less than 0.10 wt% Mn: 0.5 to 2.0 wt% P: 0.01 to 0 10 wt% Mo: 0.50 wt% or less, and a high-strength melt having excellent press workability and plating adhesion characterized by having an oxide in the crystal grain boundaries and / or crystal grains in the surface layer of the high-strength steel sheet. It is a galvanized steel sheet. In this case, the oxide is an oxide containing at least one of Si, Mn, P and Fe, or Si, Mn, P,
It is a composite oxide containing a plurality of Fe. In the first and second inventions, the oxide is SiO 2 , MnO, FeS.
iO 3 , Fe 2 SiO 4 , MnSiO 3 , Mn 2 SiO
At least one selected from the group consisting of 4 and P 2 O 5 , and the range of distribution of the oxide is 0.1 to 100 μm from the surface layer.
m is preferable, and when the steel sheet is further heat-alloyed, a high-strength galvannealed steel sheet having excellent press workability and plating adhesion can be obtained.
【００１４】[0014]
【発明の実施の形態】以下、本発明について詳細に説明
する。鋼中にＳｉを０．１ｗｔ％以上、３．０ｗｔ％以
下含有する高強度鋼板もしくはＣを０．０３〜０．１０
ｗｔ％、Ｓｉを０．００１〜０．１０ｗｔ％未満、Ｍｎ
を０．５〜２．０ｗｔ％、Ｐを０．０１〜０．１０ｗｔ
％、Ｍｏを０．５０ｗｔ％以下をそれぞれ含有する高強
度鋼板を通常のプロセスで溶融メッキすると、メッキ前
の焼鈍過程で鋼中のＳｉやＭｎが鋼板表面の加熱によっ
て選択的に酸化され鋼板表層に拡散されるため、Ｓｉや
Ｍｎの酸化物が鋼板表面に形成する。このＳｉやＭｎの
酸化物は還元焼鈍でも還元されないので、鋼中のＳｉ含
有量の増加に伴い溶融亜鉛との濡れ性が急激に低下す
る。その結果、不メッキが発生し製造が不可能となる。
しかし、本発明では鋼板表層の酸化物の存在により表面
濃化が抑制され、ＳｉやＭｎの酸化物が鋼板表面に形成
しないため、Ｓｉを０．１ｗｔ％以上もしくはＭｎを
０．５％以上含有する鋼板でも問題なく製造が可能とな
る。そのため、特にＳｉを０．１ｗｔ％以上もしくはＭ
ｎを０．５ｗｔ％以上含有する鋼板で、本発明の効果が
もっともよく現れる。BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. High-strength steel sheet containing 0.1 wt% or more and 3.0 wt% or less of Si in steel or C of 0.03 to 0.10.
wt%, 0.001 to less than 0.10 wt% Si, Mn
0.5 to 2.0 wt%, P 0.01 to 0.10 wt
%, And high-strength steel sheets containing 0.50 wt% or less of Mo respectively are hot-dipped by a normal process, Si or Mn in the steel is selectively oxidized by the heating of the steel sheet surface in the annealing process before plating, and the steel sheet surface layer Oxides of Si and Mn are formed on the surface of the steel sheet. Since the oxides of Si and Mn are not reduced even by reduction annealing, the wettability with molten zinc sharply decreases as the Si content in steel increases. As a result, non-plating occurs and manufacturing becomes impossible.
However, in the present invention, the surface concentration is suppressed by the presence of the oxide on the surface layer of the steel sheet, and oxides of Si and Mn do not form on the surface of the steel sheet. Therefore, Si of 0.1 wt% or more or Mn of 0.5% or more is contained. It will be possible to manufacture even steel sheets without problems. Therefore, in particular, 0.1 wt% or more of Si or M
The effect of the present invention is most manifested in a steel sheet containing 0.5 wt% or more of n.
【００１５】溶融メッキは溶融亜鉛メッキに限らず、溶
融アルミニウムメッキや溶融アルミニウム−亜鉛メッキ
である５％アルミニウム−亜鉛メッキやいわゆるガルバ
リウムメッキ等の溶融メッキでも構わない。これはＳｉ
やＭｎなどの酸化物の表面への濃化が抑制されるため、
亜鉛に限らずアルミニウムなどの他の溶融金属との濡れ
性が改善されるため、同様に不メッキが抑えられるため
である。従って、結局のところ高強度鋼板の表層に予め
酸化物を生成せしめておくことによって、ＳｉやＭｎな
どの酸化物の表面への濃化が抑制されるため、ＳｉやＭ
ｎの添加量の多い高強度鋼板でも金属種を問わず溶融メ
ッキ性が良好になるわけである。The hot-dip galvanization is not limited to hot-dip galvanizing, and hot-dip aluminum plating, hot-dip galvanizing such as 5% aluminum-zinc plating which is hot-dip aluminum-zinc plating, or so-called galvalume plating may be used. This is Si
Since the concentration of oxides such as Mn and Mn on the surface is suppressed,
This is because the wettability with not only zinc but also other molten metals such as aluminum is improved, and thus non-plating is similarly suppressed. Therefore, after all, since the oxides such as Si and Mn are suppressed from being concentrated on the surface by forming the oxides on the surface layer of the high strength steel plate in advance, Si and M
Even in the case of a high-strength steel sheet containing a large amount of n, the hot-dip galvanizability will be good regardless of the metal species.
【００１６】また、合金化についても同様で、表面濃化
量と相関があるのはメッキ性だけでなく、合金化速度と
も相関があり、表面濃化量の少ない方がメッキ性がよく
なるし、合金化速度は速くなることが確認されている。
加えて、巻取処理時には結晶粒界に酸化物が析出してい
たにも関わらず、溶融メッキ直前の焼鈍時に地鉄組織が
再結晶を起こしたため、この再結晶後の組織と酸化物の
分布とは対応しなくなる。すなわち、巻取時に生成した
酸化物が、再結晶後の組織の結晶粒界に存在しているわ
けではないので、これら酸化物がメッキ後の結晶粒界に
おける合金化反応を阻害するものではない。つまり内部
酸化物は合金化反応を抑制するものではない。従って、
Ｓｉ、Ｍｎ、Ｃｒ、Ｐなどの強化元素が添加された高強
度冷延鋼板のメッキ性を飛躍的に向上させるためには、
結局のところＳｉ、Ｍｎなどの表面酸化を顕著に抑制す
ることが最も効果的かつ適切である。焼鈍時にそのよう
な効果を得るために、前述のような従来の問題点を解決
すべく鋭意検討した結果、Ｃ、Ｓｉ、Ｍｎなどの固溶強
化元素が複合添加されている高強度鋼板のメッキ層直下
の高強度鋼板の表層の結晶粒界、あるいは結晶粒内、あ
るいは結晶粒界及び結晶粒内に酸化物を有することによ
り、プレス加工性及びメッキ密着性に優れる高強度溶融
亜鉛メッキ鋼板を得ることができ、さらにこのような高
強度溶融亜鉛メッキ鋼板が合金化されているプレス加工
性及びメッキ密着性に優れる合金化高強度溶融亜鉛メッ
キ鋼板が得られるということを見出し、高強度溶融亜鉛
メッキ鋼板のプレス加工性及びメッキ密着性を飛躍的に
向上させると言う課題を解決するに至った。The same applies to alloying. Correlation with the amount of surface enrichment is not only related to the plating property but also to the alloying speed. The smaller the amount of surface enrichment, the better the plating property. It has been confirmed that the alloying rate becomes faster.
In addition, since the base iron structure recrystallized during the annealing just before hot dip coating, even though the oxide was precipitated at the grain boundary during the winding treatment, the structure and oxide distribution after this recrystallization And will not correspond. That is, since the oxide generated during winding does not exist in the crystal grain boundary of the structure after recrystallization, these oxides do not hinder the alloying reaction in the crystal grain boundary after plating. . That is, the internal oxide does not suppress the alloying reaction. Therefore,
In order to dramatically improve the plating property of the high-strength cold-rolled steel sheet to which reinforcing elements such as Si, Mn, Cr, and P are added,
After all, it is most effective and appropriate to significantly suppress the surface oxidation of Si, Mn and the like. In order to obtain such an effect at the time of annealing, as a result of diligent studies to solve the above-mentioned conventional problems, plating of a high-strength steel sheet to which solid solution strengthening elements such as C, Si and Mn are added A high-strength hot-dip galvanized steel sheet excellent in press workability and plating adhesion by having an oxide in the crystal grain boundary of the high-strength steel sheet immediately below the layer, or in the crystal grain, or in the crystal grain boundary and in the crystal grain. It has been found that an alloyed high-strength galvanized steel sheet that is excellent in press workability and plating adhesion can be obtained, and that such a high-strength hot-dip galvanized steel sheet is alloyed. We have solved the problem of dramatically improving the press workability and plating adhesion of plated steel sheets.
【００１７】第１の発明におけるＳｉ量もしくは第２の
発明におけるＭｎ量のそれぞれ下限を設定したのは、こ
れより少ない範囲では本発明を適用しなくても通常のラ
ジアントチューブ（ＲＴＨ）型や無酸化炉（ＮＯＦ）型
のＣＧＬで溶融亜鉛メッキが可能であるからである。ま
た、合金化反応についても特に合金化反応速度の低下は
見られず、従来と同様の合金化設備や合金化温度、合金
化時間、加熱時の昇温速度、冷却時の冷却速度などにて
合金化が可能であることから第１の発明におけるＳｉ量
は０．１ｗｔ％以上もしくは第２の発明におけるＭｎ量
は０．５ｗｔ％以上とする。The lower limits of the Si amount in the first invention and the Mn amount in the second invention are set, respectively. The lower limit is set to the normal radiant tube (RTH) type or the non-existent type without applying the present invention. This is because hot dip galvanizing is possible with an oxidation furnace (NOF) type CGL. Also, regarding the alloying reaction, no particular decrease in the alloying reaction rate was observed, and the same alloying equipment and alloying temperature as before, alloying time, heating rate during heating, cooling rate during cooling, etc. Since alloying is possible, the Si amount in the first invention is 0.1 wt% or more, or the Mn amount in the second invention is 0.5 wt% or more.
【００１８】またＳｉ，Ｍｎ上限を設定したのは、第１
の発明におけるＳｉ量が３．０ｗｔ％を越えるかもしく
は第２の発明におけるＭｎ量が２．０ｗｔ％を越える
と、表面に酸化膜を形成し、溶融亜鉛等との濡れ性を著
しく低下させるため、第１の発明のＳｉ量は３．０ｗｔ
％以下もしくは第２の発明のＭｎ量は２．０ｗｔ％以下
とする。また、合金化反応も顕著に低下することがあ
り、そのため第１の発明のＳｉ量は３．０ｗｔ％以下も
しくは第２の発明のＭｎ量は２．０ｗｔ％以下とする。
第２の発明におけるＳｉは、Ｓｉが０．１０ｗｔ％未満
の場合に、上述のようにＭｎを規定することにより、本
願の特性を有する高強度溶融亜鉛メッキ鋼板を得ること
ができる。この第２の発明においてＳｉの下限である
０．００１ｗｔ％は不可避含有量である。The upper limits of Si and Mn are set first.
When the amount of Si in the invention of 3 exceeds 3.0 wt% or the amount of Mn in the second invention exceeds 2.0 wt%, an oxide film is formed on the surface and the wettability with molten zinc or the like is significantly reduced. , The amount of Si in the first invention is 3.0 wt
% Or less, or the amount of Mn in the second invention is 2.0 wt% or less. Further, the alloying reaction may be significantly reduced, so that the Si amount in the first invention is 3.0 wt% or less or the Mn amount in the second invention is 2.0 wt% or less.
When Si is less than 0.10 wt% in the second invention, by defining Mn as described above, a high strength galvanized steel sheet having the characteristics of the present application can be obtained. In the second invention, the lower limit of Si, 0.001 wt%, is an unavoidable content.
【００１９】同様に、鋼中にＣｒを０．１ｗｔ％以上、
２．０ｗｔ％以下含有する高強度鋼板においても、鋼中
のＣｒが焼鈍過程において鋼板表面の加熱によって選択
的に酸化され、鋼板表面に拡散されるため、これらの酸
化物が濃化し、鋼板表面で皮膜を形成する。その結果、
溶融亜鉛との濡れ性を著しく阻害し、メッキ密着性を悪
くするため、鋼板に溶融亜鉛が付着しない、いわゆる不
メッキがしばしば起こる。しかし、本発明では高強度鋼
板の表層の結晶粒界、あるいは結晶粒内、あるいは結晶
粒界及び結晶粒内に酸化物を生成させると、Ｓｉ、Ｍ
ｎ、Ｐ、Ｃｒなどの表面濃化が抑制され、これらの酸化
物が鋼板表面に形成しないため、不メッキやはじき、付
着量むらが起こらない。そのため、鋼中にＣｒを０．０
１ｗｔ％以上、２．０ｗｔ％以下含有する高強度鋼板が
好ましい。Similarly, 0.1 wt% or more of Cr in steel,
Even in a high-strength steel sheet containing 2.0 wt% or less, Cr in the steel is selectively oxidized by heating the steel sheet surface in the annealing process and diffused to the steel sheet surface, so these oxides are concentrated and the steel sheet surface To form a film. as a result,
Since the wettability with molten zinc is significantly impaired and the plating adhesion is deteriorated, so-called non-plating in which molten zinc does not adhere to the steel sheet often occurs. However, in the present invention, when an oxide is generated in the crystal grain boundary of the surface layer of the high-strength steel sheet, or in the crystal grain, or in the crystal grain boundary and the crystal grain, Si, M
Surface enrichment of n, P, Cr, etc. is suppressed, and these oxides do not form on the surface of the steel sheet, so that non-plating, repelling, and uneven adhesion amount do not occur. Therefore, Cr in the steel is 0.0
A high strength steel sheet containing 1 wt% or more and 2.0 wt% or less is preferable.
【００２０】また、Ｐは深絞り性の劣化が少なく鋼を硬
化できることから０．０１ｗｔ％以上を含有することが
好ましく、Ｂは鋼の二次加工脆性に絶大な効果を有する
ことから、高強度鋼板には好ましい元素である。これら
は、焼鈍過程において鋼板表面の加熱によって選択的に
酸化され、鋼板表面に拡散されるが、溶融亜鉛との濡れ
性を著しく阻害することはない。また焼鈍後の脱脂酸洗
が十分でなく表層に残存したとしても不メッキやはじ
き、化成処理むらなどの原因にもなりにくい。しかし、
Ｐについては多量に含有すると合金化遅延を引き起こす
恐れがあることから０．１０ｗｔ％以下とする。Ｂにつ
いては特に含有量の限定は必要ない。Further, P is preferably contained in an amount of 0.01 wt% or more because it can harden the steel with little deterioration in deep drawability, and B has a great effect on the secondary work embrittlement of the steel, and therefore has high strength. It is a preferred element for steel sheets. These are selectively oxidized by heating the steel sheet surface during the annealing process and are diffused to the steel sheet surface, but do not significantly impair the wettability with the molten zinc. Further, even if degreasing and pickling after annealing is not sufficient and remains on the surface layer, it is unlikely to cause non-plating, repellency, uneven chemical conversion treatment and the like. But,
If P is contained in a large amount, it may cause alloying delay, so the content of P is set to 0.10 wt% or less. It is not necessary to limit the content of B.
【００２１】また、上述のように溶融亜鉛めっきを可能
とするため巻取温度を高めた場合に強度が不足する可能
性があるが、Ｍｏ，Ｃｒなどの鋼板の機械的特性を向上
させる効果のある元素の添加により解決することができ
る。また、酸化物層の厚みを０．１μｍ以上、１００μ
ｍ以下に限定したのは、０．１μｍ未満であると、酸化
物の生成量そのものが少ないため、表面濃化を抑制する
ことができなくなるからであり、１００μｍを越える
と、酸化物は脆いため鋼板自身の機械的特性が劣化する
恐れがある。このような理由から、酸化物の厚みは０．
１μｍ以上、１００μｍ以下であることが必要であり、
このように限定した。Further, as described above, since hot-dip galvanizing is possible, the strength may be insufficient when the coiling temperature is raised, but it has the effect of improving the mechanical properties of steel sheets such as Mo and Cr. It can be solved by adding an element. Further, the thickness of the oxide layer is 0.1 μm or more and 100 μm.
The reason for limiting the thickness to m or less is that if the thickness is less than 0.1 μm, the amount of oxide itself is small, so that the surface concentration cannot be suppressed, and if it exceeds 100 μm, the oxide is brittle. The mechanical properties of the steel sheet itself may deteriorate. For this reason, the oxide has a thickness of 0.
It is necessary to be 1 μm or more and 100 μm or less,
This is limited.
【００２２】上記のような困難を解決する鋼板として、
本発明ではメッキ層直下の鋼板地鉄表層の結晶粒界、あ
るいは結晶粒内、あるいは結晶粒界及び結晶粒内に酸化
物を有するものとした。この鋼板の表層の結晶粒界、あ
るいは結晶粒内、あるいは結晶粒界及び結晶粒内に存在
する酸化物は熱間圧延時に生成するものであり、特にコ
イル巻取り温度が高く、その後の冷却速度が遅い場合に
成長し形成していることを発見した。この熱間圧延時に
形成した粒界酸化物は図１に示すように黒皮直下に観察
される。また、熱延鋼板の表層のレプリカを取りＴＥＭ
（透過型電子顕微鏡）により観察した結果を図２に示
す。図２中の酸化物１（結晶粒内）及び酸化物２（結晶
粒界）をＥＤＸ（エネルギー分散型Ｘ線検出器）により
元素の成分分析を行った結果は次の通りである。As a steel plate for solving the above difficulties,
In the present invention, the surface layer of the steel plate base metal immediately below the plating layer has an oxide in the crystal grain boundary, in the crystal grain, or in the crystal grain boundary and the crystal grain. Oxides existing in the crystal grain boundaries of the surface layer of the steel sheet, or in the crystal grains, or in the crystal grain boundaries and the crystal grains are generated during hot rolling, and particularly the coil winding temperature is high and the cooling rate after that is high. It has been found that when it is slow, it grows and forms. The grain boundary oxide formed during this hot rolling is observed immediately below the black skin as shown in FIG. Also, a replica of the surface layer of the hot rolled steel sheet is taken and TEM
The result of observation with (transmission electron microscope) is shown in FIG. The results of elemental composition analysis of oxide 1 (inside crystal grains) and oxide 2 (crystal grain boundaries) in FIG. 2 by EDX (energy dispersive X-ray detector) are as follows.
【００２３】酸化物の元素分析値（金属元素のみ：ｗｔ
％） 酸化物１：Ｓｉ＝３０、Ｍｎ＝３３、Ｆｅ＝３７ 酸化物２：Ｓｉ＝６０、Ｍｎ＝４０ このように結晶粒界だけでなく表層の結晶粒内にも析出
物が確認される。また、結晶粒界については、Ｆｅ、Ｍ
ｎ、Ｓｉなど、結晶粒内についてはＭｎ、Ｓｉなどが確
認できる。次にこの析出物の軽元素定性分析（ＥＥＬＳ
測定）を行った結果を図３、図４に示す。図３は結晶粒
内部、図４は結晶粒界部である。いずれも、レプリカ由
来の炭素（Ｃ）以外に酸素（Ｏ）の存在が確認される。
これら成分分析結果及びレプリカにより剥離可能である
こと、またこれらの元素の鋼中における存在形態を鑑み
ることにより、これらの元素は酸化物を形成しているも
のと考えられる。Elemental analysis value of oxide (metal element only: wt
%) Oxide 1: Si = 30, Mn = 33, Fe = 37 Oxide 2: Si = 60, Mn = 40 Thus, not only the crystal grain boundaries but also the precipitates are confirmed in the crystal grains of the surface layer. . Regarding the crystal grain boundaries, Fe, M
In the crystal grains such as n and Si, Mn and Si can be confirmed. Next, a light element qualitative analysis of this precipitate (EELS
The measurement results are shown in FIGS. 3 and 4. FIG. 3 shows the inside of the crystal grain, and FIG. 4 shows the crystal grain boundary portion. In each case, the presence of oxygen (O) is confirmed in addition to the carbon (C) derived from the replica.
It is considered that these elements form oxides in view of the results of the component analysis and the fact that they can be peeled off by the replica and the existence form of these elements in the steel.
【００２４】本発明で開示した鋼板表層直下に存在する
酸化物は、熱間圧延段階で形成した黒皮直下の酸化物
が、その後の酸洗、冷延、焼鈍などの工程を経ても残存
しているものである。図５にはメッキ後の鋼板表層断面
の走査型電子顕微鏡（ＳＥＭ）写真を示す。メッキ層の
下面が鋼板表層であり、この表層に析出物（酸化物層）
が明瞭に見られる。この鋼板表層に分布している微細な
析出物が、熱延板巻き取り後に生成した内部酸化物であ
る。内部酸化物は熱延板を酸洗、冷間圧延、焼鈍した後
も鋼板表層中に残存するが、焼鈍時に鋼板組織は再結晶
するため、再結晶後には酸化物の分布と鋼板の結晶粒界
とは必ずしも対応しない。しかし、内部酸化物は依然と
して残存するため、このように溶融メッキ板の断面の電
子顕微鏡観察にてこれら酸化物の存在を観察することが
できる。As for the oxides present immediately below the surface layer of the steel sheet disclosed in the present invention, the oxides immediately below the black skin formed in the hot rolling stage remain even after the subsequent steps such as pickling, cold rolling and annealing. It is what FIG. 5 shows a scanning electron microscope (SEM) photograph of the surface cross section of the steel sheet after plating. The lower surface of the plating layer is the steel plate surface layer, and precipitates (oxide layer) on this surface layer
Can be seen clearly. The fine precipitates distributed on the surface of the steel sheet are internal oxides formed after winding the hot rolled sheet. The internal oxide remains in the steel sheet surface layer after pickling, cold rolling and annealing of the hot rolled sheet, but since the steel sheet structure recrystallizes during annealing, the distribution of oxides and crystal grains of the steel sheet after recrystallization It does not necessarily correspond to the world. However, since the internal oxides still remain, the presence of these oxides can be observed by observing the cross section of the hot-dip plated sheet with an electron microscope.
【００２５】図６には焼鈍後のグロー放電（ＧＤＳ）に
よる表層から１０μｍ程度の深さ方向元素分析結果を示
した。表層からの深さ０．５〜３μｍ程度に見えるＳ
ｉ、Ｍｎ，Ｐのピークが上記の酸化物に相当する。通常
ＣＧＬでの還元焼鈍では、Ｓｉ、Ｍｎなどは選択酸化さ
れて表面濃化するが、本発明のように鋼板表層直下に緻
密に酸化物が存在すると、これらの酸化物がＳｉ、Ｍｎ
等の金属元素のバルクから表面への移動に対する拡散障
壁となり、結果として最表面での表面濃化が抑制される
ものと考えられる。また、主に結晶粒界では粒内に比
べ、鋼板表層から浸透してくる酸素の分圧が相対的に高
く、生成酸化物がより高位の酸化物となり、たとえば合
金元素が主としてＳｉ−Ｍｎ系の鋼板ではＦｅＯ・Ｓｉ
Ｏ2 や（ＦｅＯ）2 ・ＳｉＯ2 等が生成している。これ
らは先述したＴＥＭ−ＥＤＸの結果に加え、Ｂｒ2■Ｍ
ｅＯＨ法にて抽出したこれら酸化物を赤外スペクトルに
かけることにより確認することができる。FIG. 6 shows the results of elemental analysis in the depth direction of about 10 μm from the surface layer by glow discharge (GDS) after annealing. S visible at a depth of 0.5 to 3 μm from the surface layer
The peaks of i, Mn, and P correspond to the above oxide. Normally, in reduction annealing with CGL, Si, Mn, etc. are selectively oxidized and the surface is thickened. However, when the oxides are densely present immediately below the surface layer of the steel sheet as in the present invention, these oxides are Si, Mn.
It is considered that it acts as a diffusion barrier against the movement of the metal element such as the above from the bulk to the surface, and as a result, the surface concentration on the outermost surface is suppressed. Further, mainly in the grain boundaries, the partial pressure of oxygen that permeates from the surface layer of the steel sheet is relatively higher than in the grains, and the produced oxide becomes a higher-order oxide. Of steel sheet is FeO / Si
O 2 and (FeO) 2 · SiO 2 are generated. In addition to the results of TEM-EDX described above, these are Br 2 M
It can be confirmed by applying an infrared spectrum to these oxides extracted by the eOH method.
【００２６】図７は抽出酸化物のＩＲスペクトルの波数
に対する透過率％を示すものである。図７中◎★□印は
それぞれ（ＦｅＯ）2 ・ＳｉＯ2 、ＦｅＯ・ＳｉＯ2 、
ＳｉＯ2 を示している。ところがこれら酸化物は酸化性
でありＳｉやＭｎ等を酸化還元反応により酸化物として
トラップする効果を持ち合わせる。ＩＣＰ法により焼鈍
前後の鋼板の抽出酸化物中に存在するＳｉＯ2 、Ｍｎ
Ｏ、ＦｅＯ等の酸化物量の変化（重量％）を定量した結
果は表１の通りである。FIG. 7 shows the transmittance% with respect to the wave number of the IR spectrum of the extracted oxide. In FIG. 7, ◎ ★ □ indicates (FeO) 2 · SiO 2 , FeO · SiO 2 ,
It shows SiO 2 . However, these oxides are oxidative and have the effect of trapping Si, Mn and the like as oxides by a redox reaction. SiO 2 and Mn existing in the extracted oxides of the steel sheet before and after annealing by the ICP method
Table 1 shows the results of quantifying the change (wt%) in the amount of oxides such as O and FeO.
【００２７】[0027]
【表１】 [Table 1]
【００２８】表１から明らかなように、焼鈍前後におい
てＦｅ酸化物の減少及びＳｉやＭｎ酸化物の増大が確認
できた。従って、以上の２要素、すなわち、粒内に緻密
に存在する酸化物による拡散抑制及び主として粒界に存
在する高位の酸化物によるＳｉやＭｎ等の酸化トラップ
による効果によって、鋼板表面にはメッキ密着性を悪く
するＳｉ、Ｍｎなどの酸化物皮膜が存在せず、これらの
性能は良好となる。これにより、Ｓｉ、Ｍｎ等の合金元
素が複合添加されている高強度鋼板の溶融メッキ性を飛
躍的に向上させ、効果的にＳｉ、Ｍｎ等の合金元素が複
合添加されている高強度鋼板をメッキすることが可能と
なる。As is clear from Table 1, decrease of Fe oxide and increase of Si and Mn oxide were confirmed before and after annealing. Therefore, due to the above two factors, that is, the effect of suppressing the diffusion due to the oxides that are densely present in the grains and the oxidation trap of Si, Mn, etc. mainly due to the high-level oxides present at grain boundaries, the plating adhesion to the steel plate surface There is no oxide film of Si, Mn, etc. that deteriorates the properties, and these properties are good. Thereby, the hot dip galvanizing property of the high strength steel plate to which alloy elements such as Si and Mn are added is dramatically improved, and the high strength steel plate to which the alloy elements such as Si and Mn are effectively added is improved. It becomes possible to plate.
【００２９】本発明の酸化物の存在する鋼板と従来の酸
化物のない鋼板との光学顕微鏡による断面観察結果の模
写図を図８、図９に示す。図８のメッキ層直下に観察さ
れる黒い筋状のものが酸化物（内部酸化層）である。図
９は内部酸化層がない。このメッキ層直下の鋼板内部に
存在する酸化物の断面観察は、１％ナイタール液により
数秒〜数十秒のエッチング、もしくは先に述べたように
断面の電子顕微鏡による観察により存在が確認可能であ
る。プレス加工時において、主に圧縮応力を受けること
によりメッキが剥離することが知られている。本発明に
おける溶融亜鉛メッキ鋼板のメッキ層直下の酸化物の存
在する鋼板は、従来の酸化物の存在しない鋼板に比べ、
鋼板表層が表面濃化の抑制により極めて清浄に保たれて
おり、結果として溶融亜鉛と鉄との反応の活性点が多い
ため、合金化時の合金層が図のように極めて緻密なもの
になる。そのため、プレス加工時に与えられる応力を充
分に吸収することができるため、結果としてプレス加工
時におけるメッキ密着性が良好になる。FIG. 8 and FIG. 9 show copy diagrams of the results of observing the cross section of the steel sheet containing the oxide of the present invention and the conventional steel sheet having no oxide by an optical microscope. The black streak observed directly below the plating layer in FIG. 8 is an oxide (internal oxide layer). FIG. 9 has no internal oxide layer. The cross-sectional observation of the oxide existing inside the steel sheet immediately below the plating layer can be confirmed by etching with a 1% Nital solution for several seconds to several tens of seconds, or by observing the cross section with an electron microscope as described above. . It is known that during press working, the plating is mainly peeled off by receiving a compressive stress. The steel sheet in which the oxide immediately below the plating layer of the hot-dip galvanized steel sheet in the present invention is compared with the conventional steel sheet in which no oxide is present.
The surface layer of the steel sheet is kept extremely clean by suppressing surface thickening, and as a result, there are many active points of the reaction between molten zinc and iron, so the alloy layer during alloying becomes extremely dense as shown in the figure. . Therefore, the stress applied during the press working can be sufficiently absorbed, and as a result, the plating adhesion during the press working becomes good.
【００３０】本発明が開示した技術によるプレス加工時
におけるメッキ密着性の向上は、断面を光学顕微鏡で観
察し、メッキ層直下の酸化物が少量でも観察されれば効
果が確認できた。本発明ではメッキ層について特に限定
するものではないが、耐食性などの観点から自動車用鋼
板としては、溶融亜鉛メッキ鋼板を合金化した後の通常
Ｚｎ−Ｆｅ合金の付着量は２５〜９０ｇ／ｍ2 、メッキ
層中のＦｅ含有率としては８〜１３ｗｔ％が適当であ
る。また、同様に溶融亜鉛メッキ浴条件についても特に
限定するものではないが、メッキ浴中のアルミ濃度は
０．１３〜０．１５ｗｔ％程度、Ｆｅ濃度０．０１ｗｔ
％〜飽和が適当であると思われ、また、さらに浴中にＰ
ｂ、Ｍｇ、Ｍｎ等を含有してもよい。The effect of improving the plating adhesion during press working by the technique disclosed by the present invention was confirmed by observing the cross section with an optical microscope and observing even a small amount of oxide immediately below the plating layer. In the present invention, the plating layer is not particularly limited, but from the viewpoint of corrosion resistance and the like, as a steel sheet for automobiles, the deposition amount of a normal Zn-Fe alloy after alloying a hot-dip galvanized steel sheet is 25 to 90 g / m 2. The appropriate Fe content in the plated layer is 8 to 13 wt%. Similarly, although the conditions of the hot dip galvanizing bath are not particularly limited, the aluminum concentration in the plating bath is about 0.13 to 0.15 wt% and the Fe concentration is 0.01 wt.
% -Saturation seems to be appropriate, and further P in the bath
b, Mg, Mn, etc. may be contained.
【００３１】必要に応じて、その後直ちに加熱合金化処
理され、合金化溶融亜鉛メッキ鋼板が製造される。合金
化に際しての加熱処理は、４６０℃未満の場合長時間の
加熱が必要であり生産性が低下するため４６０℃以上、
プレス成型時の密着性より６００℃以下が適当である。Immediately thereafter, if necessary, a heat alloying treatment is carried out to produce a galvannealed steel sheet. The heat treatment for alloying requires heating for a long time when the temperature is lower than 460 ° C, which lowers the productivity.
600 ° C. or less is suitable from the viewpoint of adhesion during press molding.
【００３２】次に、本発明のメッキ鋼板の母板の製造方
法について説明する。鋼板表層の結晶粒界及び／又は結
晶粒内の酸化物は例えば熱間圧延時にコイル巻き取り温
度６５０℃で巻取り、その後の冷却を５０℃／ｈｒで行
うことにより生成する。この結果粒界、あるいは粒内、
あるいは結晶粒界及び粒内、の酸化物は、黒皮（酸化
鉄）が高温にて酸素を解離したものが鋼板内部に浸透し
た結果生成したものであり、黒皮（酸化鉄）の高温での
解離酸素分圧における地鉄表層部の内部酸化により生成
するものである。内部酸化の速度は時間と温度との関数
であるので、温度が高いほど、または時間が長いほど酸
化反応は進行し、結晶粒界、あるいは粒内、あるいは結
晶粒界及び粒内、の酸化物の量は増加する。Next, a method for manufacturing the mother plate of the plated steel sheet according to the present invention will be described. Oxides in the crystal grain boundaries and / or crystal grains in the surface layer of the steel sheet are generated, for example, by winding at a coil winding temperature of 650 ° C. during hot rolling and then cooling at 50 ° C./hr. As a result, at grain boundaries, or within grains,
Alternatively, the oxides at the grain boundaries and inside the grains are generated as a result of the dissociation of oxygen at high temperature in the black skin (iron oxide) permeating inside the steel sheet, and at the high temperature of the black skin (iron oxide). It is generated by the internal oxidation of the surface layer of the base metal at the dissociated oxygen partial pressure. Since the rate of internal oxidation is a function of time and temperature, the higher the temperature or the longer the time is, the more the oxidation reaction proceeds, and the grain boundary, or within the grain, or the oxide at the grain boundary and within the grain. The amount of will increase.
【００３３】[0033]
【実施例】以下、実施例に基づき本発明を説明する。表
２に示す組成の高強度鋼板を熱間圧延後、酸洗し冷間圧
延した。その後、各種表面処理方法にて表２に挙げたよ
うな表面処理鋼板を製造した。その条件は、１２００か
ら１２５０℃でスラブ加熱を実施し熱延を行った後、８
６０〜９１０℃にて仕上げ圧延し巻き取り温度は４５０
〜７７０℃で巻き取りを行った。ついで、酸洗で黒皮を
除去し、その後冷延、還元焼鈍、各種表面処理を施し
た。還元焼鈍は鋼種Ｎｏ．１を８８０℃、鋼種Ｎｏ．２
を８５０℃、鋼種Ｎｏ．３を８６０℃、鋼種Ｎｏ．４を
８６０℃、鋼種Ｎｏ．５を８４０℃、鋼種Ｎｏ．６を８
６０℃、鋼種Ｎｏ．７を８７０℃、鋼種Ｎｏ．８を８７
０℃、鋼種Ｎｏ．９を８３０℃で行った。EXAMPLES The present invention will be described below based on examples. The high-strength steel sheets having the compositions shown in Table 2 were hot-rolled, then pickled and cold-rolled. Then, the surface-treated steel plate as listed in Table 2 was manufactured by various surface treatment methods. The conditions are slab heating at 1200 to 1250 ° C., hot rolling, and then 8
Finish rolling at 60-910 ° C and take-up temperature 450
Winding was performed at ˜770 ° C. Next, the scale was removed by pickling, followed by cold rolling, reduction annealing, and various surface treatments. Reduction annealing is performed with steel type No. 1 at 880 ° C. and steel type No. Two
850 ° C., steel type No. 3 at 860 ° C. and steel type No. 4 at 860 ° C. and steel type No. 5 at 840 ° C. and steel type No. 6 to 8
60 ° C, steel type No. 7 at 870 ° C., steel grade No. 8 to 87
0 ° C, steel type No. 9 was performed at 830 ° C.
【００３４】溶融メッキ方法について説明する。溶融亜
鉛メッキ浴はアルミ濃度を０．１５ｗｔ％添加した浴
で、メッキ温度は４９０℃とした。メッキの外観性につ
いては、目視で観察した上で良好か否か、不メッキ発生
があるか否か等を判断した。合金化処理温度については
４６０℃から５６０℃で行った。合金化状態については
合金化後、目視で合金化ムラ、合金化遅延などが起こっ
ていないかどうか確認したうえで評価した。鋼板表層直
下の酸化物の有無観察は、断面研摩後１％ナイタール液
によりエッチングして行った。プレス加工性評価試験
は、合金化溶融亜鉛メッキ鋼板を９０度曲げ伸ばしを行
い、圧着側をテープ剥離して亜鉛の剥離量を蛍光Ｘ線に
て測定した。The hot dip plating method will be described. The hot dip galvanizing bath was a bath to which an aluminum concentration of 0.15 wt% was added, and the plating temperature was 490 ° C. Regarding the appearance of the plating, it was visually observed to determine whether or not it was good and whether or not non-plating occurred. The alloying treatment temperature was 460 ° C to 560 ° C. Regarding the alloying state, it was evaluated after visually confirming whether uneven alloying, delayed alloying, etc., occurred after alloying. The presence or absence of oxides immediately below the surface layer of the steel sheet was observed by polishing the section and then etching with a 1% nital solution. In the press workability evaluation test, an alloyed hot-dip galvanized steel sheet was bent and stretched at 90 degrees, the pressure-bonded side was tape-peeled, and the amount of zinc peeled was measured by fluorescent X-ray.
【００３５】上記のようにして製造した各種表面処理の
結果を表３に示す。表３中で「厚み」とは鋼板表層から
の酸化物層の分布範囲の厚みを表す。適切な厚みの表層
酸化物が結晶粒界、結晶内又はその両者に存在する場
合、メッキ状態は良好であった。表層酸化物が非常に薄
い場合もおおむね良好であったが酸化物層がない場合、
不メッキが発生した。また、同様にして製造した溶融亜
鉛メッキ鋼板を４６０℃〜５６０℃で加熱合金化処理し
て合金化溶融亜鉛メッキ鋼板を製造した。その結果を表
４に示す。プレス加工性は次のランク付けで示した。Table 3 shows the results of various surface treatments produced as described above. In Table 3, "thickness" represents the thickness of the distribution range of the oxide layer from the surface layer of the steel sheet. When the surface oxide having an appropriate thickness was present in the crystal grain boundary, in the crystal, or both, the plating state was good. It was generally good when the surface oxide was very thin, but when there was no oxide layer,
Non-plating has occurred. A hot-dip galvanized steel sheet produced in the same manner was heat-alloyed at 460 ° C to 560 ° C to produce an alloyed hot-dip galvanized steel sheet. The results are shown in Table 4. The press workability is shown by the following ranking.
【００３６】蛍光Ｘ線によるカウント数……プレス加工
性評価（ランク） ０〜５００ …… ランク１（良） ５００〜１０００ …… ２ １０００〜２０００ …… ３ ２０００〜３０００ …… ４ ３０００以上 …… ランク５（劣） 比較例１〜９では不メッキが発生し、プレス加工性、密
着性も不良であった。しかし、実施例１〜１１では、表
面外観、プレス加工性、密着性とも良好であった。Count by fluorescent X-ray: Press workability evaluation (rank) 0 to 500 ... Rank 1 (good) 500 to 1000 ... 2 1000 to 2000 ... 3 2000 to 3000 ... 4 3000 or more ... Rank 5 (poor) In Comparative Examples 1 to 9, non-plating occurred, and press workability and adhesion were also poor. However, in Examples 1 to 11, the surface appearance, press workability, and adhesion were good.
【００３７】[0037]
【表２】 [Table 2]
【００３８】[0038]
【表３】 [Table 3]
【００３９】[0039]
【表４】 [Table 4]
【００４０】[0040]
【発明の効果】以上述べたように、鋼板表層の結晶粒界
あるいは結晶粒内、あるいは結果粒界及び結晶粒内に酸
化物を有することにより、Ｓｉ、Ｍｎ、Ｃｒなどを含有
していても、普通鋼と同様に効率的に、かつプレス加工
性及びメッキ密着性に優れた高強度溶融亜鉛メッキ鋼板
又は合金化溶融亜鉛メッキ鋼板の製造に対して極めて効
果的である。As described above, even if Si, Mn, Cr, etc. are contained by having an oxide in the crystal grain boundary of the steel sheet surface layer or in the crystal grain boundary, or the resultant grain boundary and crystal grain boundary. It is extremely effective for producing a high-strength hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet that is as efficient as ordinary steel and is excellent in press workability and plating adhesion.
【図１】実施例の熱延板の断面のＳＥＭ写真である。FIG. 1 is an SEM photograph of a cross section of a hot rolled sheet of an example.
【図２】実施例の熱延板の断面のＴＥＭ写真（レプリカ
法による）である。FIG. 2 is a TEM photograph (by a replica method) of a cross section of a hot rolled sheet of an example.
【図３】析出物の軽元素定性分析結果（ＥＥＬＳ法によ
る）を示すグラフである。FIG. 3 is a graph showing a light element qualitative analysis result (by EELS method) of a precipitate.
【図４】析出物の軽元素定性分析結果（ＥＥＬＳ法によ
る）を示すグラフである。FIG. 4 is a graph showing a light element qualitative analysis result (by EELS method) of a precipitate.
【図５】実施例の溶融亜鉛メッキ鋼板の断面のＳＥＭ写
真である。FIG. 5 is a SEM photograph of a cross section of a hot-dip galvanized steel sheet according to an example.
【図６】ＧＤＳによる深さ方向分析を示すチャートであ
る。FIG. 6 is a chart showing a depth profile analysis by GDS.
【図７】抽出酸化物のＩＲスペクトルを示すグラフであ
る。FIG. 7 is a graph showing an IR spectrum of an extracted oxide.
【図８】実施例の溶融亜鉛メッキ板の光学顕微鏡による
断面観察結果の模式図である。FIG. 8 is a schematic diagram of a result of observing a cross section of the hot-dip galvanized sheet of the example with an optical microscope.
【図９】比較例の溶融亜鉛メッキ板の光学顕微鏡による
断面観察結果の模式図である。FIG. 9 is a schematic diagram of a cross-sectional observation result of a galvanized sheet of a comparative example by an optical microscope.
Claims (5)
以下含有する高強度鋼板の表層の結晶粒界及び／又は結
晶粒内に酸化物を有することを特徴とするプレス加工性
及びメッキ密着性に優れる高強度溶融亜鉛メッキ鋼板。1. Si in an amount of 0.1 wt% or more and 3.0 wt%
A high-strength hot-dip galvanized steel sheet having excellent press workability and plating adhesion, which has an oxide in a crystal grain boundary and / or crystal grain in a surface layer of a high-strength steel sheet contained below.
粒内に酸化物を有することを特徴とするプレス加工性及
びメッキ密着性に優れる高強度溶融亜鉛メッキ鋼板。2. C: 0.03 to 0.10 wt% Si: 0.001 to less than 0.10 wt% Mn: 0.5 to 2.0 wt% P: 0.01 to 0.10 wt% Mo: 0.0. A high-strength hot-dip galvanized steel sheet having excellent press workability and plating adhesion, which has an oxide in the crystal grain boundaries and / or crystal grains of the surface layer of the high-strength steel sheet containing 50 wt% or less.
ｉＯ3 、Ｆｅ2 ＳｉＯ4 、ＭｎＳｉＯ3 、Ｍｎ2 ＳｉＯ
4 及びＰ2 Ｏ5 からなる群から選ばれた１種以上である
ことを特徴とする請求項１又は２記載の高強度溶融亜鉛
メッキ鋼板。3. The oxide is SiO 2 , MnO or FeS.
iO 3 , Fe 2 SiO 4 , MnSiO 3 , Mn 2 SiO
The high-strength hot-dip galvanized steel sheet according to claim 1 or 2, which is one or more selected from the group consisting of 4 and P 2 O 5 .
〜１００μｍであることを特徴とする、請求項１〜３の
いずれかに記載のプレス加工性及びメッキ密着性に優れ
る高強度溶融亜鉛メッキ鋼板。4. The distribution range of the oxide is 0.1 from the surface layer.
It is 100-100 micrometers, The high-strength hot-dip galvanized steel sheet excellent in the press workability and plating adhesiveness in any one of Claims 1-3 characterized by the above-mentioned.
いることを特徴とする請求項１〜４の何れかに記載のプ
レス加工性及びメッキ密着性に優れる高強度溶融亜鉛メ
ッキ鋼板。5. The high-strength hot-dip galvanized steel sheet having excellent press workability and plating adhesion according to any one of claims 1 to 4, wherein the steel sheet is further heat-alloyed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08147910A JP3130470B2 (en) | 1996-05-20 | 1996-05-20 | High-strength hot-dip galvanized steel sheet with excellent press workability and plating adhesion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08147910A JP3130470B2 (en) | 1996-05-20 | 1996-05-20 | High-strength hot-dip galvanized steel sheet with excellent press workability and plating adhesion |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09310163A true JPH09310163A (en) | 1997-12-02 |
| JP3130470B2 JP3130470B2 (en) | 2001-01-31 |
Family
ID=15440886
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP08147910A Expired - Fee Related JP3130470B2 (en) | 1996-05-20 | 1996-05-20 | High-strength hot-dip galvanized steel sheet with excellent press workability and plating adhesion |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002322551A (en) * | 2001-04-25 | 2002-11-08 | Kobe Steel Ltd | Galvanized steel sheet |
| EP1548142A1 (en) * | 2003-12-25 | 2005-06-29 | Kabushiki Kaisha Kobe Seiko Sho | High-strength cold-rolled steel sheet excellent in coating film adhesion |
| JP2008038168A (en) * | 2006-08-02 | 2008-02-21 | Nippon Steel Corp | High-strength hot-dip galvanized steel sheet excellent in metal-plating property, and producing method thereof |
| JP2011026674A (en) * | 2009-07-28 | 2011-02-10 | Jfe Steel Corp | High-strength hot-dip galvanized steel sheet having excellent plating peeling resistance |
| US8592049B2 (en) * | 2006-01-30 | 2013-11-26 | Nippon Steel & Sumitomo Metal Corporation | High strength hot dip galvanized steel sheet and high strength galvannealed steel sheet excellent in shapeability and plateability |
| WO2020111884A1 (en) * | 2018-11-30 | 2020-06-04 | 주식회사 포스코 | Aluminum-based plated steel plate for hot press having excellent resistance against hydrogen delayed fracture and spot weldability, and method for manufacturing same |
| KR20200066237A (en) * | 2018-11-30 | 2020-06-09 | 주식회사 포스코 | STEEL SHEET PLATED WITH Al FOR HOT PRESS FORMING HAVING IMPROVED RESISTANCE AGAINST HYDROGEN DELAYED FRACTURE AND SPOT WELDABILITY, AND MANUFACTURING METHOD THEREOF |
-
1996
- 1996-05-20 JP JP08147910A patent/JP3130470B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002322551A (en) * | 2001-04-25 | 2002-11-08 | Kobe Steel Ltd | Galvanized steel sheet |
| EP1548142A1 (en) * | 2003-12-25 | 2005-06-29 | Kabushiki Kaisha Kobe Seiko Sho | High-strength cold-rolled steel sheet excellent in coating film adhesion |
| US8592049B2 (en) * | 2006-01-30 | 2013-11-26 | Nippon Steel & Sumitomo Metal Corporation | High strength hot dip galvanized steel sheet and high strength galvannealed steel sheet excellent in shapeability and plateability |
| EP1980638B2 (en) † | 2006-01-30 | 2022-05-11 | Nippon Steel Corporation | High-strength hot-dip zinced steel sheet excellent in moldability and suitability for plating, high-strength alloyed hot-dip zinced steel sheet, and processes for producing these |
| JP2008038168A (en) * | 2006-08-02 | 2008-02-21 | Nippon Steel Corp | High-strength hot-dip galvanized steel sheet excellent in metal-plating property, and producing method thereof |
| JP2011026674A (en) * | 2009-07-28 | 2011-02-10 | Jfe Steel Corp | High-strength hot-dip galvanized steel sheet having excellent plating peeling resistance |
| WO2020111884A1 (en) * | 2018-11-30 | 2020-06-04 | 주식회사 포스코 | Aluminum-based plated steel plate for hot press having excellent resistance against hydrogen delayed fracture and spot weldability, and method for manufacturing same |
| KR20200066237A (en) * | 2018-11-30 | 2020-06-09 | 주식회사 포스코 | STEEL SHEET PLATED WITH Al FOR HOT PRESS FORMING HAVING IMPROVED RESISTANCE AGAINST HYDROGEN DELAYED FRACTURE AND SPOT WELDABILITY, AND MANUFACTURING METHOD THEREOF |
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|---|---|
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