JPH0688191A - Galvannealed steel sheet having excellent workability and its production - Google Patents

Abstract

PURPOSE:To produce a galvannealed steel sheet excellent in powdering resis tance, flaking generation resistance, drawability and also in workability. CONSTITUTION:The galvannealed steel sheet having an alloyed plating layer which contains 8 to 13wt.% Fe, <0.5wt.% Al and 0.2 to 0.5wt.% Cr, <=0.5mum thickness of the GAMMA phase of the boundary of the base iron, has no eta phases and zeta phases existing on the surface of the plating layer and has 45 to 90g/m<2> deposition is produced by plating the rteel sheet in such a manner that the deposition of at least one surface attains 45 to 90g/m<2> by using a galvanizing bath contg. <0.2wt.% Al and 0.1 to 1.0wt.% Cr and then, heating the steel shleet for 2 to 40 seconds at 450 to 500 deg.C.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、耐パウダリング性、耐
フレーキング性及びプレス成形性に優れている加工性に
優れた合金化溶融亜鉛めっき鋼板とその製造方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloyed hot-dip galvanized steel sheet having excellent powdering resistance, flaking resistance and press formability and excellent workability, and a method for producing the same.

【０００２】[0002]

【従来技術】従来より溶融亜鉛めっき鋼板の耐食性に加
えて、塗装性、塗膜密着性、溶接性及び加工性を付与す
るために、鋼板に溶融亜鉛めっきした後に加熱処理を施
してめっき層を鉄−亜鉛合金化した合金化溶融亜鉛めっ
き鋼板が製造され、自動車や家電製品や建築など様々な
分野に使用されている。2. Description of the Related Art Conventionally, in order to impart paintability, coating adhesion, weldability and workability in addition to the corrosion resistance of hot-dip galvanized steel sheets, hot-dip galvanized steel sheets are subjected to heat treatment to form a plating layer. Iron-zinc alloyed hot-dip galvanized steel sheets are manufactured and used in various fields such as automobiles, home appliances and construction.

【０００３】[0003]

【発明が解決しようとする問題点】このように鋼板に溶
融亜鉛めっきを施した後に加熱処理を施した場合、合金
化が進むにつれて鉄と亜鉛との相互拡散によりζ相（Fe
Zn₁₃）、δ₁ 相（FeZn₇ ）、Γ相（Fe₅ Zn₂₁）が順次生
成する。When the steel sheet is subjected to hot dip galvanizing and then heat treatment as described above, the ζ phase (Fe
Zn ₁₃ ), δ ₁ phase (FeZn ₇ ) and Γ phase (Fe ₅ Zn ₂₁ ) are sequentially formed.

【０００４】このような溶融亜鉛めっき鋼板において、
その加工性と合金化めっき層構造とに関する従来からの
研究の結果から、次のことが判明している。即ち、合金
化めっき層表面にη相又はζ相が存在すると、これらの
相が比較的柔らかいためプレス成形時に金型との摺動抵
抗が大きくなり、鋼板の金型への滑り込みが阻害されて
鋼板の切断や金型へのめっき層の焼付けを招く恐れがあ
る。一方、Γ相が厚く成長すると、Γ相は硬く脆いため
にプレス成形時にめっき層がパウダリング状に剥離する
いわゆるパウダリング現象を起こすようになり、このパ
ウダリング現象が著しい場合には合金化めっき層の耐食
性が低下するばかりでなくプレス作業性にも悪影響を及
ぼすことになる。更に、Γ相が比較的薄い場合でもめっ
き層表面にζ相が存在すると、柔らかいζ相がカジリを
生じ、この剪断応力によって硬くて脆いΓ相がフレーク
状に剥離するいわゆるフレーキング現象となる。したが
って理想的には鋼板表面から合金化めっき層表面まで均
一なδ₁ 相であることが望ましいが熱拡散処理によって
合金化する限り実際上不可能である。In such a galvanized steel sheet,
From the results of conventional studies on the workability and the alloyed plating layer structure, the following has been found. That is, when the η phase or the ζ phase exists on the surface of the alloyed plating layer, these phases are relatively soft, so that the sliding resistance with the mold during press molding becomes large and the slip of the steel sheet into the mold is hindered. This may lead to cutting of the steel plate and baking of the plating layer on the mold. On the other hand, when the Γ phase grows thick, the Γ phase is hard and brittle, so that a so-called powdering phenomenon occurs in which the plating layer peels in a powdering state during press forming. When this powdering phenomenon is remarkable, alloying plating occurs. Not only the corrosion resistance of the layer is lowered, but also the workability of the press is adversely affected. Further, even if the Γ phase is relatively thin, if the ζ phase exists on the surface of the plating layer, the soft ζ phase causes galling, and this shear stress causes a so-called flaking phenomenon in which the hard and brittle Γ phase is separated into flakes. Therefore, ideally, it is desirable that the δ ₁ phase is uniform from the surface of the steel sheet to the surface of the alloyed plating layer, but it is practically impossible as long as the alloy is alloyed by the thermal diffusion treatment.

【０００５】[0005]

【発明が解決しようとする課題】従来、このようなδ₁
単相に近い合金化めっき層を得るための技術として、例
えば特開昭６４−６８４５６号公報等に開示されてい
る。しかし、この方法でη相、ζが存在しないように合
金化するためには、めっき浴中の有効Al量を０．１０％
以下とし且つ鋼板のめっき浴中への浸漬時間を３秒以下
好ましくは２秒以下という非常に高速な通板速度とする
ことが必要であり、しかも本発明者等の研究によると５
００℃以上の加熱温度が必要である。しかし、５００℃
以上の温度ではΓ相の成長が速く、Γ相の厚さを充分に
制御できず、６０ｇ／ｍ² 以上の付着量では例えばΓ相
が０．５〜３．０μｍとなり耐パウダリング性が充分で
なくなる。Conventionally, such δ ₁
A technique for obtaining an alloyed plating layer close to a single phase is disclosed in, for example, JP-A-64-68456. However, in order to alloy such that the η phase and ζ do not exist by this method, the effective Al amount in the plating bath is set to 0.10%.
It is necessary to make the steel sheet soaked in the plating bath for 3 seconds or less, preferably 2 seconds or less, which is a very high sheet passing speed.
A heating temperature of 00 ° C or higher is required. However, 500 ° C
At the above temperature, the growth of the Γ phase is fast, and the thickness of the Γ phase cannot be controlled sufficiently. At the adhesion amount of 60 g / m ² or more, for example, the Γ phase becomes 0.5 to 3.0 μm and the powdering resistance is sufficient. No longer.

【０００６】一方、Γ相の厚さを制御するためにはより
低い温度で合金化することが望ましく、例えば５００℃
未満で合金化するとΓ相の成長は充分制御されるが、ζ
相が残存し易くプレス成形性及び耐フレーキング性が低
下する。このように、ζ相とΓ相とを抑制できる温度域
が相反するために何れか片方しか制御できず、両方共制
御した合金化溶融亜鉛めっき鋼板を製造するためには合
金化度を測定しながら厳しく管理する必要がある。しか
し、現在の方法ではめっき層表面にζ相を存在させず且
つΓ相も耐パウダリング性を十分なレベルまで制御でき
る手段が存在していない。On the other hand, it is desirable to alloy at a lower temperature in order to control the thickness of the Γ phase, for example, 500 ° C.
If the alloying ratio is less than 1, the growth of the Γ phase is well controlled.
The phases are likely to remain and press moldability and flaking resistance are deteriorated. Thus, only one of them can be controlled because the temperature regions where the ζ phase and the Γ phase can be suppressed are contradictory, and both are controlled to measure the alloying degree in order to produce a controlled galvannealed steel sheet. However, it must be strictly managed. However, in the current method, there is no means for controlling the powdering resistance of the Γ phase to a sufficient level without allowing the ζ phase to exist on the surface of the plating layer.

【０００７】本発明はこのような従来技術の問題点を解
決し、合金化めっき層表面にη相のみならずζ相も存在
させず、且つΓ相も耐パウダリング性が十分なレベルま
で制御できる加工性に優れた合金化溶融亜鉛めっき鋼板
とその製造方法を提供することを課題とする。The present invention solves the problems of the prior art as described above, and not only the η phase but also the ζ phase does not exist on the surface of the alloyed plating layer, and the Γ phase is controlled to a sufficient level of powdering resistance. An object of the present invention is to provide an alloyed hot-dip galvanized steel sheet which is excellent in workability and a manufacturing method thereof.

【０００８】[0008]

【課題を解決するための手段】本発明者らは上記課題を
解決すべく鋭意努力した結果、めっき浴中にCrを添加す
ることによりΓ相の厚さを充分制御できる４５０〜５０
０℃という温度でもζ相の生成を抑制できることを究明
し、地鉄界面のΓ相の厚さが０．５μｍ以下であり、合
金化めっき層表面をＸ線回折で測定してもη相、ζ相が
存在せず、且つ付着量が４５〜９０ｇ／ｍ² の合金化め
っき層を、少なくとも片面に有する加工性に優れた合金
化亜鉛めっき鋼板とその製造方法の開発に成功したもの
である。The inventors of the present invention have made diligent efforts to solve the above problems, and as a result, the thickness of the Γ phase can be sufficiently controlled by adding Cr to the plating bath 450 to 50.
It was clarified that the generation of the ζ phase can be suppressed even at a temperature of 0 ° C., the thickness of the Γ phase at the base iron interface is 0.5 μm or less, and the η phase, even if measured on the surface of the alloyed plating layer by X-ray diffraction, The present invention succeeds in the development of an alloyed galvanized steel sheet which does not have a ζ phase and has an alloyed plated layer having an adhesion amount of 45 to 90 g / m ² on at least one surface and which is excellent in workability and a manufacturing method thereof. .

【０００９】すなわち、本発明にかかる加工性に優れた
合金化溶融亜鉛めっき鋼板は、Fe：８〜１３重量％、A
l：０．５重量％未満、Cr：０．２〜１．５重量％を含
有し残部がZn及び不可避的不純物よりなる組成であって
且つ地鉄界面のΓ相の厚さが０．５μｍ以下であり合金
化めっき層表面にη相、ζ相が存在せず付着量が４５〜
９０ｇ／ｍ² の合金化めっき層を少なくとも片面に有す
ることを特徴とする。That is, the alloyed hot-dip galvanized steel sheet according to the present invention which is excellent in workability is Fe: 8 to 13% by weight, A
l: less than 0.5% by weight, Cr: 0.2 to 1.5% by weight, the balance being Zn and inevitable impurities, and the thickness of the Γ phase at the base iron interface is 0.5 μm. The following is the case where the η phase and the ζ phase do not exist on the surface of the alloyed plating layer and the adhesion amount is 45 to
It is characterized by having an alloyed plating layer of 90 g / m ² on at least one side.

【００１０】また本発明に係る加工性に優れた合金化溶
融亜鉛めっき鋼板の製造方法は、Al: ０．２重量％未
満、Cr：０．１〜１．０重量％を含有し、残部がZn及び
不可避的不純物よりなる溶融亜鉛めっき浴を用いて少な
くとも片面に４５〜９０ｇ／ｍ² となる溶融亜鉛めっき
を行った後、４５０〜５００℃の温度で２〜４０秒加熱
して地鉄界面のΓ相の厚さが０．５μｍ以下であり且つ
めっき層表面にη相、ζ相が存在しないように合金化処
理することを特徴とする。The method for producing a galvannealed steel sheet having excellent workability according to the present invention contains Al: less than 0.2% by weight, Cr: 0.1 to 1.0% by weight, and the balance is After performing hot dip galvanizing at 45 to 90 g / m ² on at least one surface using a hot dip galvanizing bath consisting of Zn and unavoidable impurities, heating at a temperature of 450 to 500 ° C. for 2 to 40 seconds is followed by a base metal interface. The Γ phase has a thickness of 0.5 μm or less and is alloyed so that the η phase and the ζ phase do not exist on the surface of the plating layer.

【００１１】[0011]

【作用】以下、本発明で用いる亜鉛めっき浴組成、合金
化処理温度及びめっき層の組成の限定理由について説明
する。 Al：Alは鋼板とめっき層との界面にFr−Al金属間化合物
の層を形成してめっき層中のZn−Fe相互拡散を抑制し、
かつ溶融亜鉛めっき浴の粘度を引き下げるのに有効に作
用する。しかし、溶融亜鉛めっき浴中のAl濃度が０．２
重量％以上になると、Zn−Fe相互拡散が極めて抑制され
るために合金化反応が著しく遅滞し、本発明方法におけ
るような低い合金化温度では、実際上インラインの合金
化炉で合金化処理が不可能となる。よって本発明方法で
は、溶融亜鉛めっき浴中へのAl添加量は０．２重量％未
満とした。The function of the galvanizing bath composition, the alloying treatment temperature and the composition of the plating layer used in the present invention will be described below. Al: Al forms a layer of Fr-Al intermetallic compound at the interface between the steel plate and the plating layer to suppress Zn-Fe interdiffusion in the plating layer,
And it works effectively to reduce the viscosity of the hot dip galvanizing bath. However, the Al concentration in the hot dip galvanizing bath is 0.2
When the content is more than wt%, the alloying reaction is significantly delayed because Zn-Fe interdiffusion is extremely suppressed, and at a low alloying temperature as in the method of the present invention, the alloying process is practically performed in an in-line alloying furnace. It will be impossible. Therefore, in the method of the present invention, the amount of Al added to the hot dip galvanizing bath is less than 0.2% by weight.

【００１２】次いで、合金化めっき層中のAlの組成範囲
について述べる。一般に、Alを含む溶融亜鉛めっき浴に
よって鋼板に溶融亜鉛めっきした場合には、鋼板−めっ
き層界面にFe−Al金属間化合物の層が優先析出し、溶融
亜鉛めっき浴のAl濃度と比べてめっき層中のAl濃度が高
くなる傾向があることが知られている。本発明における
溶融亜鉛めっき処理においても全く同じ傾向が認められ
る。前記Al濃度の溶融亜鉛めっき浴によって溶融亜鉛め
っきを行った場合に生成するめっき層のAl濃度は、０．
５重量％未満となる。従って、本発明に係る合金化溶融
亜鉛めっき鋼板における合金化めっき層中のAl濃度は
０．５重量％未満とした。Next, the composition range of Al in the alloyed plating layer will be described. In general, when hot dip galvanizing a steel sheet with a hot dip galvanizing bath containing Al, a layer of Fe-Al intermetallic compound is preferentially deposited at the steel sheet-plating layer interface, and plating is performed in comparison with the Al concentration of the hot dip galvanizing bath. It is known that the Al concentration in the layer tends to increase. The same tendency is observed in the hot dip galvanizing treatment of the present invention. The Al concentration of the plating layer generated when hot dip galvanizing is performed in the hot dip galvanizing bath having the above Al concentration is 0.
It will be less than 5% by weight. Therefore, the Al concentration in the alloyed plated layer in the galvannealed steel sheet according to the present invention is set to less than 0.5% by weight.

【００１３】Cr：Crはζ相の生成を抑制し、かつ５００
℃以下の低い温度で合金化処理を行うために添加する。
Crの溶融亜鉛めっき浴中への添加量が０．１重量％未満
では、ζ相の生成抑制効果が充分でなく、５００℃以下
で合金化処理した場合にζ相が残存しやすく、また１．
０重量％を越えて添加するためには、めっき浴温度を高
くしなければならないが、めっき浴温度を高くするとΓ
相が生成し易くなり、地鉄界面のΓ相を０．５μｍ以下
に抑制することが事実上不可能となる。よって、本発明
方法では溶融亜鉛めっき浴中へのCrの添加量は０．１〜
１．０重量％に限定した。Cr: Cr suppresses the formation of ζ phase, and
It is added to carry out the alloying treatment at a low temperature of ℃ or less.
If the amount of Cr added to the hot dip galvanizing bath is less than 0.1% by weight, the effect of suppressing the formation of the ζ phase is not sufficient, and the ζ phase tends to remain when alloying at 500 ° C. or less. ．
To add more than 0% by weight, it is necessary to raise the plating bath temperature.
A phase is easily generated, and it becomes virtually impossible to suppress the Γ phase at the base steel interface to 0.5 μm or less. Therefore, in the method of the present invention, the amount of Cr added to the hot dip galvanizing bath is 0.1
It was limited to 1.0% by weight.

【００１４】次いで、合金化めっき層中のCrの組成範囲
について述べる。Crは、めっき層中に優先的に析出して
めっき浴中の濃度よりも高くなる傾向を示す。前記のめ
っき浴組成の溶融亜鉛めっき浴によって溶融亜鉛めっき
を行った場合に生成するめっき層中のCrの濃度は、０．
２〜１．５重量％となる。従って本発明の合金化溶融亜
鉛めっき鋼板における合金化めっき層中のCr濃度は０．
２〜１．５重量％とする。Next, the composition range of Cr in the alloyed plating layer will be described. Cr tends to preferentially precipitate in the plating layer and become higher than the concentration in the plating bath. The concentration of Cr in the plated layer produced when hot dip galvanizing is performed in a hot dip galvanizing bath having the above-mentioned plating bath composition is 0.
It becomes 2 to 1.5% by weight. Therefore, the Cr concentration in the alloyed plating layer in the galvannealed steel sheet of the present invention is 0.
2 to 1.5% by weight.

【００１５】Fe：本発明に係る加工性に優れた合金化溶
融亜鉛めっき鋼板のめっき層構造では、めっき層表面に
η相、ζ相が存在せず且つΓ相の厚さが０．５μｍ以下
であり、このような構成の合金化めっき層中のFe濃度は
８〜１３重量％であるので８〜１３重量％とした。Fe: In the plating layer structure of the galvannealed steel sheet excellent in workability according to the present invention, the η phase and the ζ phase are not present on the surface of the plating layer and the thickness of the Γ phase is 0.5 μm or less. Since the Fe concentration in the alloyed plating layer having such a constitution is 8 to 13% by weight, it was set to 8 to 13% by weight.

【００１６】合金化処理温度：溶融亜鉛めっき鋼板のめ
っき層を５００℃を越えて加熱して合金化するとΓ相が
生成し易く地鉄界面のΓ相が０．５μｍを越えるので好
ましくない。一方、４５０℃未満で合金化すると、前記
組成のCr濃度ではζ相の生成を抑制する効果が薄くなっ
てめっき層表面にζ相が残存しやすく、本発明合金化溶
融亜鉛めっき層構造の特徴であるめっき層表面にη相、
ζ相が存在せず且つ地鉄界面のΓ相が０．５μｍ以下の
合金層を形成させることができない。従って本発明方法
における合金化温度は４５０〜５００℃とした。Alloying temperature: If the coating layer of the hot-dip galvanized steel sheet is heated to more than 500 ° C. and alloyed, a Γ phase is likely to be formed, and the Γ phase at the base iron interface exceeds 0.5 μm, which is not preferable. On the other hand, when alloying at less than 450 ° C., the effect of suppressing the formation of the ζ phase is reduced at the Cr concentration of the above composition, and the ζ phase is apt to remain on the surface of the plated layer, which is a feature of the alloyed hot dip galvanized layer structure of the present invention. Η phase on the surface of the plating layer,
It is impossible to form an alloy layer in which the ζ phase does not exist and the Γ phase at the base iron interface is 0.5 μm or less. Therefore, the alloying temperature in the method of the present invention was set to 450 to 500 ° C.

【００１７】加熱時間：４５０〜５００℃という合金化
処理温度であっても、加熱時間が短いとめっき層表面に
η相やζ相が残存し、また加熱時間が長すぎると地鉄界
面のΓ相が０．５μｍ以上形成されるので本発明者らは
種々検討した結果、２〜４０秒の範囲で加熱すると地鉄
界面のΓ相厚さが０．５μｍ以下でありめっき相表面に
η相、ζ相が存在しない合金化めっき層形成されること
が判明した。従って加熱時間は２〜４０秒とした。Heating time: Even at the alloying treatment temperature of 450 to 500 ° C., if the heating time is short, the η phase and the ζ phase remain on the surface of the plating layer, and if the heating time is too long, the Γ of the base metal interface is Since the phase is formed in 0.5 μm or more, the present inventors have made various studies and as a result, when heated in the range of 2 to 40 seconds, the Γ phase thickness of the base iron interface is 0.5 μm or less, and the η phase is present on the plating phase surface. , It was found that an alloyed plating layer without ζ phase was formed. Therefore, the heating time was set to 2 to 40 seconds.

【００１８】合金化溶融亜鉛めっき層の厚さ：本発明に
係る合金化溶融亜鉛めっき鋼板においては、付着量とし
て４５〜９０ｇ／ｍ² が適用できる範囲である。４５ｇ
／ｍ²未満では従来の技術で耐パウダリング性、耐フレ
ーキング性及びプレス成形性を共に満足できる合金化溶
融亜鉛めっき鋼板は製造可能であり、本発明鋼板が特に
有利というわけではない。また９０ｇ／ｍ² を越えると
耐フレーキング性及びプレス成形性は満足できるが耐パ
ウダリング性が低下するので、本発明合金化溶融亜鉛め
っき鋼板の適用できる付着量を４５〜９０ｇ／ｍ² とし
た。但し、耐フレーキング性及びプレス成形性を満足し
ていれば良い場合には４５〜１５０ｇ／ｍ² まで適用で
きる。めっき付着量が１５０ｇ／ｍ² を越えると地鉄界
面のΓ相が０．５μｍ以下でめっき層表面にη相、ζ相
が存在しないめっき層は実際上製造できなくなる。Thickness of alloyed hot-dip galvanized layer: In the alloyed hot-dip galvanized steel sheet according to the present invention, the applied amount is in the range of 45 to 90 g / m ² . 45 g
If it is less than / m ² , alloyed hot-dip galvanized steel sheets that satisfy the powdering resistance, flaking resistance and press formability can be produced by conventional techniques, and the steel sheet of the present invention is not particularly advantageous. If it exceeds 90 g / m ² , flaking resistance and press formability are satisfactory, but powdering resistance is deteriorated. Therefore, the applicable amount of the alloyed hot-dip galvanized steel sheet of the present invention is 45 to 90 g / m ² . did. However, when it is sufficient that the flaking resistance and the press moldability are satisfied, 45 to 150 g / m ² can be applied. If the coating weight exceeds 150 g / m ² , the Γ phase at the base iron interface is 0.5 μm or less, and it is practically impossible to manufacture a plating layer having neither η phase nor ζ phase on the surface of the plating layer.

【００１９】その他の合金化めっき層の組成：合金化め
っき層の組成としてFe、Al、Crのみを規定したが、他の
成分例えばPb、Sbなどを少量添加しても本発明の効果は
変わらない。Other composition of alloyed plating layer: Only Fe, Al and Cr are specified as the composition of the alloyed plating layer, but the effect of the present invention is changed even if a small amount of other components such as Pb and Sb is added. Absent.

【００２０】[0020]

【実施例】次に本発明に係る加工性に優れた合金化溶融
亜鉛めっき鋼板の実施例を比較例と共にさらに具体的に
説明する。ゼンジマー型の無酸化炉方式の連続溶融亜鉛
めっきラインのめっき浴中に投入するAl量、Cr量を変化
させて、０．７ｍｍ厚さ×１，０００ｍｍ幅の低炭素冷
延鋼板をめっき原板として、めっき付着量が本発明にお
ける合金化溶融亜鉛めっき層の付着量の範囲４５〜９０
ｇ／ｍ² 内の種々の溶融亜鉛めっき鋼板を製造し、続い
てこれらの溶融亜鉛めっき鋼板を合金化処理炉により種
々の温度、時間で加熱して、合金層のFe濃度が異なる種
々の合金化溶融亜鉛めっき鋼板を製造した。EXAMPLES Next, examples of the galvannealed steel sheet having excellent workability according to the present invention will be described more specifically together with comparative examples. A low carbon cold-rolled steel sheet with a thickness of 0.7 mm and a width of 1,000 mm is used as a plating original plate by changing the amount of Al and Cr to be put into the plating bath of a continuous hot dip galvanizing line of a Zenzimer type non-oxidizing furnace system. The coating amount is in the range of 45 to 90 of the coating amount of the galvannealed layer in the present invention.
Various hot-dip galvanized steel sheets within g / m ² are produced, and then these hot-dip galvanized steel sheets are heated at various temperatures and times by an alloying treatment furnace to obtain various alloys having different Fe concentrations in the alloy layer. A galvanized steel sheet was manufactured.

【００２１】上記の方法で製造したこれらの合金化溶融
亜鉛めっき鋼板について、次に述べる種々の試験を実施
した。These alloyed hot-dip galvanized steel sheets produced by the above method were subjected to various tests described below.

【００２２】（１）η相、ζ相の有無 Ｘ線回折法で測定して、η相、ζ相の存在を示すピーク
が現れるか否かで判定した。(1) Presence or absence of η phase and ζ phase It was determined by measuring by X-ray diffractometry whether or not a peak showing the existence of η phase and ζ phase appears.

【００２３】（２）耐パウダリング試験 図１に示すごとく、試験面を内側にして試験片の板厚ｔ
の６倍の直径の円弧部が試験面に構成されるように１８
０度曲げを行った後に曲げ戻しを行い、その試験面にセ
ロハン粘着テープを点着した後にそのセロハン粘着テー
プを引き剥がしてセロハン粘着テープに付着したパウダ
ー状のめっき金属量を次に示す基準で、目視により評価
した。 ５：付着めっき金属なし ４：付着めっき金属量小 ３：付着めっき金属量中 ２：付着めっき金属量大 １：テープなしで多量のめっき金属剥離 この基準において評価５〜３が実用上問題のない範囲で
ある。(2) Powdering resistance test As shown in FIG. 1, the plate thickness t of the test piece with the test surface inside.
18 so that an arc part with a diameter 6 times larger than
After bending 0 degree, bend back, apply cellophane adhesive tape to the test surface, and then peel off the cellophane adhesive tape to determine the amount of powder metal plating adhered to the cellophane adhesive tape according to the following criteria. It was visually evaluated. 5: No adhered plating metal 4: Small amount of adhered plated metal 3: Medium amount of adhered plated metal 2: Large amount of adhered plated metal 1: Peeling of large amount of plated metal without tape Evaluation 5 to 3 in this standard has no practical problem It is a range.

【００２４】（３）プレス成形性試験 同一防錆油を使用して図２に示す条件でのカップ絞り試
験による外径比によって評価したものである。 試験片 絞り成形前円盤の直径（Ｄ₀ ）：７５ｍｍ 絞り成形に使用する鋼板の板厚：ｔｍｍ 金型 絞り成形に使用するポンチ直径（ｄ）：４０ｍｍ 絞り成形に使用するポンチ先端半径：５ｍｍ 絞り成形に使用するダイス肩部半径：５ｔｍｍ 絞り成形時のしわ押え力：１，０００ｋｇｆ 試験後の状態 絞り成形により絞りこむ深さ：２０ｍｍ 絞り成形後のフランジ部の直径：Ｄ₁ ｍｍ 外径比：Ｄ₁ ／Ｄ₀ この外径比０．７３４〜０．７４３が冷延鋼板レベルで
ある。(3) Press-formability test The same rust preventive oil was used and evaluated by the outer diameter ratio in a cup drawing test under the conditions shown in FIG. Test piece Diameter of disk before drawing (D ₀ ): 75 mm Thickness of steel sheet used for drawing: tmm Die punch diameter used for drawing (d): 40 mm Punch tip radius used for drawing: 5 mm Drawing Die used for molding Radius of shoulder: 5tmm Wrinkle pressing force during drawing: 1,000kgf State after test Depth of drawing by drawing: 20mm Diameter of flange after drawing: D ₁ mm Outer diameter ratio: D ₁ / D ₀ This outer diameter ratio of 0.734 to 0.743 is the cold rolled steel sheet level.

【００２５】（４）耐フレーキング性試験 図３に示すごとく幅３０ｍｍ×２６０ｍｍのサンプルＳ
を内径４２ｍｍの貫通孔を有するダイスと高さ３ｍｍの
ビードしわ押え２とでしわ押さえ力５００ｋｇｆで挟持
し、直径４０ｍｍのポンチ３により成形高さ５０ｍｍの
絞り成形を行ったときの目視によるめっき金属の剥離状
態を次に示す基準により評価した。 ４：剥離せず ３：剥離小 ２：剥離中 １：剥離大 この基準において評価４〜３が実用上問題のない範囲で
ある。(4) Flaking resistance test As shown in FIG. 3, sample S having a width of 30 mm × 260 mm
Is clamped with a die having a through hole having an inner diameter of 42 mm and a bead crease retainer 2 having a height of 3 mm with a wrinkle holding force of 500 kgf, and a punched metal having a forming height of 50 mm is formed by a punch 3 having a diameter of 40 mm. The peeled state of was evaluated by the following criteria. 4: No peeling 3: Small peeling 2: During peeling 1: Large peeling Evaluation 4 to 3 is a range where there is no practical problem in this criterion.

【００２６】各試験結果を纏めて表１及び表２に示す。The results of each test are summarized in Tables 1 and 2.

【００２７】[0027]

【表１】 [Table 1]

【００２８】[0028]

【表２】 [Table 2]

【００２９】[0029]

【発明の効果】以上詳述した如く、本発明に係る加工性
に優れた合金化溶融亜鉛めっき鋼板は付着量が４５〜９
０ｇ／ｍ² という厚めっきでも優れた加工性を有してい
るので合金化溶融亜鉛めっき鋼板の用途拡大が期待で
き、また本発明に係る加工性に優れた合金化亜鉛めっき
鋼板の製造方法はこのように優れた特性を有する合金化
溶融亜鉛めっき鋼板を工業的に安定して連続的に製造で
きる画期的な方法である。As described above in detail, the alloyed hot-dip galvanized steel sheet having excellent workability according to the present invention has an adhesion amount of 45-9.
Since the alloyed hot-dip galvanized steel sheet can be expected to have a wider range of applications because it has excellent workability even with a thick plating of 0 g / m ^2, the method for producing an alloyed galvanized steel sheet having excellent workability according to the present invention is This is an epoch-making method that enables industrially stable and continuous production of alloyed hot-dip galvanized steel sheets having such excellent properties.

【図面の簡単な説明】[Brief description of drawings]

【図１】耐パウダリング性の試験方法を説明する図あで
る。FIG. 1 is a diagram illustrating a method for testing powdering resistance.

【図２】プレス成形性の試験方法を説明する図である。FIG. 2 is a diagram illustrating a test method of press formability.

【図３】耐フレーキング性の試験方法を説明するFIG. 3 illustrates a flaking resistance test method.

【符号の説明】[Explanation of symbols]

１：ダイス ２：しわ押さえ ３：ポンチ Ｓ：サンプル 1: Dice 2: Wrinkle holder 3: Punch S: Sample

─────────────────────────────────────────────────────
─────────────────────────────────────────────────── ───

【手続補正書】[Procedure amendment]

【提出日】平成４年１１月２６日[Submission date] November 26, 1992

【手続補正１】[Procedure Amendment 1]

【補正対象書類名】明細書[Document name to be amended] Statement

【補正対象項目名】０００４[Correction target item name] 0004

【補正方法】変更[Correction method] Change

【補正内容】[Correction content]

【０００４】このような溶融亜鉛めっき鋼板において、
その加工性と合金化めっき層構造とに関する従来からの
研究の結果から、次のことが判明している。即ち、合金
化めっき層表面にη相又はζ相が存在すると、これらの
相が比較的柔らかいためプレス成形時に金型との摺動抵
抗が大きくなり、鋼板の金型への滑り込みが阻害されて
鋼板の切断や金型へのめっき層の焼付けを招く恐れがあ
る。一方、Γ相が厚く成長すると、Γ相は硬く脆いため
にプレス成形時にめっき層がパウダー状に剥離するいわ
ゆるパウダリング現象を起こすようになり、このパウダ
リング現象が著しい場合には合金化めっき層の耐食性が
低下するばかりでなくプレス作業性にも悪影響を及ぼす
ことになる。更に、Γ相が比較的薄い場合でもめっき層
表面にζ相が存在すると、柔らかいζ相がカジリを生
じ、この剪断応力によって硬くて脆いΓ相がフレーク状
に剥離するいわゆるフレーキング現象となる。したがっ
て理想的には鋼板表面から合金化めっき層表面まで均一
なδ_１相であることが望ましいが熱拡散処理によって合
金化する限り実際上不可能である。In such a galvanized steel sheet,
From the results of conventional studies on the workability and the alloyed plating layer structure, the following has been found. That is, when the η phase or the ζ phase exists on the surface of the alloyed plating layer, these phases are relatively soft, so that the sliding resistance with the mold during press molding becomes large and the slip of the steel sheet into the mold is hindered. This may lead to cutting of the steel plate and baking of the plating layer on the mold. On the other hand, when the Γ phase grows thick, the Γ phase is hard and brittle, so that the so-called powdering phenomenon occurs in which the plating layer peels off in powder form during press forming. Not only will the corrosion resistance of the steel be reduced, but also the workability of the press will be adversely affected. Further, even if the Γ phase is relatively thin, if the ζ phase exists on the surface of the plating layer, the soft ζ phase causes galling, and this shear stress causes a so-called flaking phenomenon in which the hard and brittle Γ phase is separated into flakes. Therefore, ideally, it is desirable that the δ ₁ phase is uniform from the surface of the steel sheet to the surface of the alloyed plating layer, but it is practically impossible as long as the alloy is alloyed by the thermal diffusion treatment.

【手続補正２】[Procedure Amendment 2]

【補正対象書類名】明細書[Document name to be amended] Statement

【補正対象項目名】０００５[Name of item to be corrected] 0005

【補正方法】変更[Correction method] Change

【補正内容】[Correction content]

【０００５】[0005]

【発明が解決しようとする課題】従来、このようなδ_１
単相に近い合金化めっき層を得るための技術として、例
えば特開昭６４−６８４５６号公報等に開示されてい
る。しかし、この方法でη相、ζ相が存在しないように
合金化するためには、めっき浴中の有効Ａｌ量を０．１
０％以下とし且つ鋼板のめっき浴中への浸漬時間を３秒
以下好ましくは２秒以下という非常に高速な通板速度と
することが必要であり、しかも本発明者等の研究による
と５００℃以上の加熱温度が必要である。しかし、５０
０℃以上の温度ではΓ相の成長が速く、Γ相の厚さを充
分に制御できず、６０ｇ／ｍ^２以上の付着量では例えば
Γ相が０．５〜３．０μｍとなり耐パウダリング性が充
分でなくなる。Conventionally, such δ ₁
A technique for obtaining an alloyed plating layer close to a single phase is disclosed in, for example, JP-A-64-68456. However, in order to alloy with this method so that the η phase and the ζ phase do not exist, the effective Al amount in the plating bath is set to 0.1
It is necessary that the steel sheet is immersed in the plating bath at a very high speed of 0% or less and 3 seconds or less, preferably 2 seconds or less. The above heating temperature is required. But 50
At a temperature of 0 ° C. or higher, the Γ phase grows rapidly, and the thickness of the Γ phase cannot be sufficiently controlled. At an adhesion amount of 60 g / m ² or more, for example, the Γ phase becomes 0.5 to 3.0 μm and the powdering resistance is improved. Is not enough.

【手続補正３】[Procedure 3]

【補正対象書類名】明細書[Document name to be amended] Statement

【補正対象項目名】００１１[Correction target item name] 0011

【補正方法】変更[Correction method] Change

【補正内容】[Correction content]

【００１１】[0011]

【作用】以下、本発明で用いる亜鉛めっき浴組成、合金
化処理温度及びめっき層の組成の限定理由について説明
する。 Ａｌ：Ａｌは鋼板とめっき層との界面にＦｅ−Ａｌ金属
間化合物の層を形成してめっき層中のＺｎ−Ｆｅ相互拡
散を抑制し、かつ溶融亜鉛めっき浴の粘度を引き下げる
のに有効に作用する。しかし、溶融亜鉛めっき浴中のＡ
ｌ濃度が０．２重量％以上になると、Ｚｎ−Ｆｅ相互拡
散が極めて抑制されるために合金化反応が著しく遅滞
し、本発明方法におけるような低い合金化温度では、実
際上インラインの合金化炉で合金化処理が不可能とな
る。よって本発明方法では、溶融亜鉛めっき浴中へのＡ
ｌ添加量は０．２重量％未満とした。The function of the galvanizing bath composition, the alloying treatment temperature and the composition of the plating layer used in the present invention will be described below. Al: Al effectively forms a layer of Fe-Al intermetallic compound at the interface between the steel plate and the plating layer to suppress Zn-Fe interdiffusion in the plating layer and to reduce the viscosity of the hot dip galvanizing bath. To work. However, A in the hot dip galvanizing bath
When the l concentration is 0.2% by weight or more, the alloying reaction is significantly delayed because Zn-Fe interdiffusion is extremely suppressed, and at a low alloying temperature as in the method of the present invention, practical in-line alloying occurs. The furnace makes alloying impossible. Therefore, in the method of the present invention, A
The amount of 1 added was less than 0.2% by weight.

【手続補正４】[Procedure amendment 4]

【補正対象書類名】明細書[Document name to be amended] Statement

【補正対象項目名】００１７[Correction target item name] 0017

【補正方法】変更[Correction method] Change

【補正内容】[Correction content]

【００１７】加熱時間：４５０〜５００℃という合金化
処理温度であっても、加熱時間が短いとめっき層表面に
η相やζ相が残存し、また加熱時間が長すぎると地鉄界
面のΓ相が０．５μｍ以上形成されるので本発明者らは
種々検討した結果、２〜４０秒の範囲で加熱すると地鉄
界面のΓ相厚さが０．５μｍ以下でありめっき層表面に
η相、ζ相が存在しない合金化めっき層が形成されるこ
とが判明した。従って加熱時間は２〜４０秒とした。Heating time: Even at the alloying treatment temperature of 450 to 500 ° C., if the heating time is short, the η phase and the ζ phase remain on the surface of the plating layer, and if the heating time is too long, the Γ of the base metal interface is Since the phase is formed in 0.5 μm or more, the present inventors have made various investigations, and as a result, when heated in the range of 2 to 40 seconds, the Γ phase thickness of the base iron interface is 0.5 μm or less, and the η phase is present on the plating layer surface. , It was found that an alloyed plating layer without ζ phase was formed. Therefore, the heating time was set to 2 to 40 seconds.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 橘 高 敏 晴 大阪府堺市石津西町５番地 日新製鋼株式 会社鉄鋼研究所表面処理研究部内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiharu Tachibana No.5 Ishizu Nishimachi, Sakai City, Osaka Prefecture Nisshin Steel Co., Ltd.

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 Ｆｅ：８〜１３重量％、Ａｌ：０．５重
量％未満、Ｃｒ：０．２〜１．５重量％を含有し、残部
がＺｎ及び不可避的不純物より成る組成であって、地鉄
界面のΓ相厚さが０．５μｍ以下でありめっき層表面に
η相、ζ相が存在せず且つ付着量が４５〜９０ｇ／ｍ^２
の合金化めっき層を少なくとも片面に有することを特徴
とする加工性に優れた合金化溶融亜鉛めっき鋼板。1. A composition containing Fe: 8 to 13% by weight, Al: less than 0.5% by weight, Cr: 0.2 to 1.5% by weight, and the balance Zn and unavoidable impurities. , The Γ phase thickness of the base metal interface is 0.5 μm or less, the η phase and the ζ phase do not exist on the plating layer surface, and the adhesion amount is 45 to 90 g / m ^2.
An alloyed hot-dip galvanized steel sheet excellent in workability, characterized in that it has the alloyed plating layer of at least one side. 【請求項２】 Ａｌ：０．２重量％未満、Ｃｒ：０．１
〜１．０重量％を含有し、残部がＺｎ及び不可避的不純
物よりなる溶融亜鉛めっき浴を用いて少なくとも片面の
付着量が４５〜９０ｇ／ｍ^２となる溶融亜鉛めっきを行
った後、４５０〜５００℃で２〜４０秒間加熱して地鉄
界面のΓ相の厚さが０．５μｍ以下であり且つめっき層
表面にη相、ζ相が存在しないように合金化処理するこ
とを特徴とする加工性の優れた合金化溶融亜鉛めっき鋼
板の製造方法。2. Al: less than 0.2% by weight, Cr: 0.1
After performing hot dip galvanizing so that the amount of adhesion on at least one side is 45 to 90 g / m ² using a hot dip galvanizing bath containing 1.0 to 1.0 wt% and the balance Zn and unavoidable impurities, 450 to It is characterized in that it is heated at 500 ° C. for 2 to 40 seconds and is alloyed so that the thickness of the Γ phase at the base iron interface is 0.5 μm or less and the η phase and the ζ phase do not exist on the plating layer surface. A method for producing a galvannealed steel sheet having excellent workability.