JPH09209107A - Galvannealed steel sheet excellent in press formability - Google Patents
Galvannealed steel sheet excellent in press formabilityInfo
- Publication number
- JPH09209107A JPH09209107A JP8013970A JP1397096A JPH09209107A JP H09209107 A JPH09209107 A JP H09209107A JP 8013970 A JP8013970 A JP 8013970A JP 1397096 A JP1397096 A JP 1397096A JP H09209107 A JPH09209107 A JP H09209107A
- Authority
- JP
- Japan
- Prior art keywords
- steel sheet
- plating layer
- content
- plating
- dip galvanized
- 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.)
- Granted
Links
Landscapes
- Coating With Molten Metal (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、プレス成形の際に
金型とめっき層間で優れた摺動特性を発揮して良好な成
形加工性を示す合金化溶融亜鉛めっき鋼板に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloyed hot-dip galvanized steel sheet which exhibits excellent sliding properties between a die and a plating layer during press forming and exhibits good formability.
【0002】[0002]
【従来の技術】近年、鋼板の表面にめっき処理を施した
表面処理鋼板の使用が増大しているが、なかでも合金化
溶融亜鉛めっき鋼板は、溶接性、塗装性、塗装後の耐食
性等に優れていることから、自動車や家電製品等に多用
されている。これらの製品は、プレス成形、組立ておよ
び塗装等の工程を経て製作されるが、プレス成形の際
に、材料である合金化溶融亜鉛めっき鋼板に割れが発生
して製品とならない場合がある。2. Description of the Related Art In recent years, the use of surface-treated steel sheets whose surfaces have been plated is increasing. Among them, alloyed hot-dip galvanized steel sheets have excellent weldability, paintability, and corrosion resistance after painting. Being excellent, it is widely used in automobiles and home appliances. These products are manufactured through steps such as press forming, assembling, and painting, but during press forming, the alloyed hot-dip galvanized steel sheet as a material may be cracked and may not be a product.
【0003】こうした問題が生じる原因としては、材料
の機械的特性が十分でないことの他に、めっき層表面と
プレス金型との摺動状況が悪く、材料が金型にスムーズ
に流入しないことが挙げられる。こうした状況に対応す
るために、従来から金型に関してはその表面にクロムめ
っき処理等が行なわれている。一方、材料側では潤滑油
の改良や均一塗布等の工夫が行なわれると共に、めっき
層の相構造の改善が行なわれている。The causes of such problems are that the mechanical properties of the material are not sufficient and that the sliding condition between the surface of the plating layer and the press die is poor and the material does not flow smoothly into the die. Can be mentioned. In order to deal with such a situation, the surface of the mold has conventionally been subjected to chrome plating treatment or the like. On the other hand, on the material side, improvements have been made to the lubricating oil, uniform coating, and the phase structure of the plating layer has been improved.
【0004】合金化溶融亜鉛めっき層には、Γ相(Fe
3 Zn10)若しくはΓ1 相(以下では、これらを総称し
て「Γ相」と呼ぶ)、δ1 相(FeZn7 )およびζ相
(FeZn13)の3種類の合金相が生成する。これらの
合金相のうちΓ相が鉄含有率が最も高くて硬質であり、
次いでδ1 相であり、ζ相は鉄含有率が最も少なく且つ
最も軟質である。これらの合金相は基本的には、地鉄側
からΓ相、δ1 相およびζ相の三相構造となっており、
合金化の程度を更に進めるとζ相は消滅し、Γ相とδ1
相の二相構造へと変化する。The alloyed hot-dip galvanized layer contains a Γ phase (Fe
3 Zn 10 ) or Γ 1 phase (hereinafter, these are collectively referred to as “Γ phase”), δ 1 phase (FeZn 7 ) and ζ phase (FeZn 13 ) are formed. Of these alloy phases, the Γ phase has the highest iron content and is hard,
Next is the δ 1 phase, which has the lowest iron content and the softest. These alloy phases basically have a three-phase structure of Γ phase, δ 1 phase and ζ phase from the base metal side,
When the degree of alloying is further advanced, the ζ phase disappears and the Γ phase and δ 1
The phase changes to a two-phase structure.
【0005】ここで最も軟質なζ相がめっき層表面に生
成していると、金型との摺動にて凝着が起こり、摩擦抵
抗が増加して金型への材料流入が阻害され、材料割れを
引き起こし易くなると言われている。こうしたことか
ら、ζ相をδ1 相へと変化させることを目的として、合
金化の程度を更に進める様に、合金化炉の設定温度を高
めたり、ラインスピードを低下させたりして熱処理条件
をコントロールすることが実施されている。If the softest ζ phase is generated on the surface of the plating layer, adhesion occurs due to sliding with the mold, frictional resistance increases, and the flow of material into the mold is hindered. It is said that material cracks are likely to occur. Therefore, in order to change the ζ phase to the δ 1 phase, the set temperature of the alloying furnace is increased or the line speed is decreased to improve the heat treatment conditions so as to further advance the degree of alloying. Control is being implemented.
【0006】[0006]
【発明が解決しようとする課題】しかしながら、上記し
た方法で合金化の程度が高くなる様にして製造された合
金化溶融亜鉛めっき鋼板の場合においても、材料の機械
的性質が十分であるにも拘らず、材料割れの発生を効果
的に抑制できていないのが現状である。こうしたことか
ら、材料割れの発生を効果的に防止することのできる合
金化溶融亜鉛めっき鋼板の実現が強く望まれているのが
実情である。本発明は上記事情に鑑みてなされたもので
あって、その目的は、プレス成形の際に金型との摺動特
性が安定して良好なめっき層を有する合金化溶融亜鉛め
っき鋼板を提供することにある。However, even in the case of an alloyed hot-dip galvanized steel sheet produced by the above-mentioned method with a high degree of alloying, the mechanical properties of the material are sufficient. Regardless, the current situation is that the occurrence of material cracks cannot be effectively suppressed. Under these circumstances, the actual situation is that there is a strong demand for the realization of an alloyed hot-dip galvanized steel sheet that can effectively prevent the occurrence of material cracks. The present invention has been made in view of the above circumstances, and an object thereof is to provide an alloyed hot-dip galvanized steel sheet having a favorable plating layer with stable sliding characteristics with a mold during press molding. Especially.
【0007】[0007]
【課題を解決するための手段】上記課題を解決すること
ができた本発明の合金化溶融亜鉛めっき鋼板は、素地鋼
板の表面に合金化溶融亜鉛めっき層が形成された合金化
溶融亜鉛めっき鋼板において、前記合金化溶融亜鉛めっ
き層は、めっき層厚が2μm以下の凹部がめっき層表面
の水平方向長さ3mm当たりで70個以下である点に要
旨を有するものである。The alloyed hot-dip galvanized steel sheet of the present invention which has been able to solve the above-mentioned problems is an alloyed hot-dip galvanized steel sheet in which an alloyed hot-dip galvanized layer is formed on the surface of a base steel sheet. In the above, the alloyed hot-dip galvanized layer has a gist in that the number of recesses having a plating layer thickness of 2 μm or less is 70 or less per horizontal length 3 mm of the plating layer surface.
【0008】本発明の合金化溶融亜鉛めっき鋼板におい
ては、前記素地鋼板は、P:0.005〜0.2%を含
むものであることが好ましい。また前記めっき層は、A
l:0.15〜0.7%を含むものであることが好まし
い。In the galvannealed steel sheet of the present invention, the base steel sheet preferably contains P: 0.005 to 0.2%. The plating layer is A
It is preferable that the content of l: 0.15 to 0.7% is included.
【0009】上記の構成を採用することによって本発明
の目的が達成されるが、必要によって合金化溶融亜鉛め
っき層の表面にケイ酸またはケイ酸塩含有皮膜を被覆
し、この被膜中のケイ酸またはケイ酸塩が、乾燥後のS
i重量に換算して1〜200mg/m2 である様な構成
を採用することも有効であり、これによってめっき層の
潤滑性を向上させて合金化溶融亜鉛めっき鋼板における
摺動特性の更なる向上を図ることができる。Although the object of the present invention is achieved by adopting the above-mentioned constitution, the surface of the alloyed hot-dip galvanized layer is coated with a silicic acid or a silicate-containing coating if necessary, and the silicic acid in this coating is Or silicate is S after drying
It is also effective to adopt a configuration in which it is 1 to 200 mg / m 2 in terms of i weight, which improves the lubricity of the plating layer and further improves the sliding characteristics of the galvannealed steel sheet. It is possible to improve.
【0010】[0010]
【発明の実施の形態】金型との摺動特性が安定して良好
であるめっき層を得るために、まず上述した様に合金化
の程度が比較的高くなる様にして製造された合金化溶融
亜鉛めっき鋼板について、プレス成形時の材料割れの原
因を調査した。このとき、材料の機械的性質はほぼ同程
度になる様に調整した。そして、まず摺動特性を支配す
るめっき層についてその断面組織を詳細に検討した。BEST MODE FOR CARRYING OUT THE INVENTION In order to obtain a plating layer having stable and favorable sliding characteristics with respect to a mold, first, as described above, an alloy formed by making the degree of alloying relatively high. The cause of material cracking during press forming was investigated for the hot-dip galvanized steel sheet. At this time, the mechanical properties of the materials were adjusted to be almost the same. Then, first, the cross-sectional structure of the plating layer that governs the sliding characteristics was examined in detail.
【0011】その結果、各めっき鋼板毎にめっき層の厚
さの均一性が異なり、例えば図1に示す様に、めっき厚
さがほぼ均一なめっき層(但し、表面には合金化溶融亜
鉛めっき層に特有な微細な凹凸が存在している)を有す
るめっき鋼板[図1(a)]と、めっき層の厚さが極端
に薄い凹部が局部的に生成してめっき厚さが均一でない
めっき層を有するめっき鋼板[図1(b)]とが観察さ
れ、また材料によってはこれらの中間程度の凹部を有す
るものも認められた。As a result, the uniformity of the thickness of the plated layer is different for each plated steel sheet. For example, as shown in FIG. 1, a plated layer having a substantially uniform plated thickness (however, the surface is alloyed hot dip galvanized) Plated steel sheet (having fine unevenness peculiar to the layer) [Fig. 1 (a)], and plating where the thickness of the plating layer is extremely thin locally generated and the plating thickness is not uniform A plated steel sheet having a layer [FIG. 1 (b)] was observed, and some materials had recesses in the middle of these.
【0012】次に本発明者らは、上記凹部と材料割れと
の関係について検討した。このとき凹部の生成量を定量
化するために、めっき膜厚が2μm以下の凹部の生成箇
所の個数をめっき層断面の水平方向長さ3mm当たりで
観察し、材料割れとの関係について調査した。このとき
凹部をめっき膜厚が2μm以下の部分としたのは、2μ
m以下の部分は通常の合金化溶融亜鉛めっき鋼板の膜厚
である約4〜8μmに対し、極端に薄い部分として明確
に区別できるためである。Next, the present inventors examined the relationship between the recess and the material crack. At this time, in order to quantify the amount of formation of the recesses, the number of locations of the recesses having a plating film thickness of 2 μm or less was observed per 3 mm in the horizontal direction of the cross section of the plating layer, and the relationship with the material crack was investigated. At this time, the concave portion is defined as a portion having a plating film thickness of 2 μm or less is 2 μm.
This is because a portion of m or less can be clearly distinguished as an extremely thin portion with respect to a film thickness of about 4 to 8 μm which is a thickness of a normal galvannealed steel sheet.
【0013】その結果を図2に示す。図2から明らかな
様に、凹部の個数が増加するにつれて材料割れは増加
し、この数が70個以下では材料の割れは認められない
が、これを超えると材料割れが発生し始めることがわか
る。従って、材料割れを効果的に防止するためには、前
記凹部の個数を70個以下にする必要があることがわか
る。The results are shown in FIG. As is clear from FIG. 2, material cracking increases as the number of recesses increases, and if the number is 70 or less, no material cracking is observed, but if this number is exceeded, material cracking begins to occur. . Therefore, it is understood that the number of the recesses must be 70 or less in order to effectively prevent material cracking.
【0014】本発明者らは、凹部の発生機構およびその
発生を防止するための具体的手段について鋭意研究した
ところ、下記のことが明らかになった。即ち、凹部はめ
っきまたは合金化の初期段階にて、地鉄結晶粒界(素地
鋼板の結晶粒界)上で起こるアウトバースト反応(Zn
−Fe合金層の局部的な異常成長をもたらすZn−Fe
合金化反応)で成長したZn−Fe合金層へ、合金化反
応速度の遅い地鉄結晶粒内の上に存在する亜鉛が合金化
加熱の作用によって拡散移動するために、前記凹部が生
成することが判明した。即ち、合金化反応速度の大きい
地鉄結晶粒界上では、めっき層は凸状になり、合金化反
応速度の小さい地結晶粒内では凹部となるのである。The inventors of the present invention have made earnest studies on the mechanism of formation of recesses and specific means for preventing the formation of the recesses, and have found the following. That is, the concave portion is an outburst reaction (Zn that occurs on the base iron crystal grain boundary (crystal grain boundary of the base steel sheet) at the initial stage of plating or alloying.
Zn-Fe which causes local abnormal growth of -Fe alloy layer
The above-mentioned recess is formed because zinc existing in the base iron crystal grains having a slow alloying reaction rate diffuses and moves to the Zn-Fe alloy layer grown by the alloying reaction) by the action of alloying heating. There was found. That is, the plating layer has a convex shape on the base iron crystal grain boundary having a high alloying reaction rate, and has a concave portion in the base crystal grain having a low alloying reaction rate.
【0015】上記の様に凸状めっき層へは周囲の亜鉛が
拡散移動するので、この部分の亜鉛量が増加することに
なり、この部分めっき層表面では鉄濃度の少ないζ相が
多く生成し、めっき層表面は金型との摺動にて凝着が起
こり易い状態となり、摩擦抵抗が大きくなって金型への
材料流入が阻害され、材料割れを引き起こし易くなるも
のと考えられる。また地鉄結晶粒界上での合金化めっき
速度が大きくなる理由は、地鉄結晶粒界内に比べて不純
物量が少なく、極めて清浄な状況となり、ZnとFeの
反応性が高くなり、早期にZn−Fe合金層が生成、成
長するためと考えられる。そこで凹部の生成を抑制する
ためには、地鉄結晶粒界と地鉄結晶粒内における合金化
反応速度の差を小さくする必要があると考えられる。As described above, since the surrounding zinc diffuses and moves to the convex plating layer, the amount of zinc in this portion increases, and a large amount of ζ phase having a low iron concentration is formed on the surface of this partial plating layer. It is considered that the surface of the plating layer is in a state where adhesion easily occurs due to sliding with the mold, the frictional resistance increases, the material inflow into the mold is hindered, and material cracking is likely to occur. In addition, the reason why the alloying plating rate on the base iron crystal grain boundary is high is that the amount of impurities is small compared to the inside of the base metal crystal grain boundary, resulting in an extremely clean situation, the reactivity of Zn and Fe becomes high, and It is considered that this is because the Zn-Fe alloy layer is generated and grows. Therefore, in order to suppress the formation of recesses, it is considered necessary to reduce the difference in the alloying reaction rate between the base iron crystal grain boundary and the base iron crystal grain.
【0016】本発明者らはこうした知見に基づき、その
ための具体的手段についても検討した。そしてまず、地
鉄結晶粒界での合金化速度を低下させるべく地鉄結晶粒
界の純度を低下させるために、粒界に偏析し易い各種元
素の素地鋼板への添加を検討した。その結果、図3に示
す様に素地鋼板中のP含有量と生成凹部の個数とには明
確な相関関係が認められ、Pの添加によって凹部の生成
数は大幅に減少することを明らかにした。Based on these findings, the present inventors also examined specific means therefor. Then, first, in order to reduce the purity of the base iron crystal grain boundary in order to reduce the alloying rate at the base iron crystal grain boundary, the addition of various elements, which are easily segregated to the grain boundary, to the base steel sheet was examined. As a result, as shown in FIG. 3, a clear correlation was found between the P content in the base steel sheet and the number of generated recesses, and it was clarified that the addition number of P significantly reduced the number of generated recesses. .
【0017】また図3から明らかな様に、素地鋼板中の
P含有量が0.005%未満では、凹部の生成数はプレ
ス成形時に材料割れを引き起こす70個を超えるが、
0.005%以上では70個以下になり、P含有量の増
加と共に凹部の個数は低下していることがわかる。As is clear from FIG. 3, when the P content in the base steel sheet is less than 0.005%, the number of recesses generated exceeds 70 which causes material cracking during press forming,
At 0.005% or more, the number becomes 70 or less, and it can be seen that the number of recesses decreases as the P content increases.
【0018】一方、凹部の生成には、めっき層中のAl
含有量が関連していることが判明した。図4はめっき層
中のAl含有量と凹部の生成数との関係を示すグラフで
ある。この図から明らかな様に、Al含有量に増加に従
って凹部の生成数は大幅に増加し、Al含有量が0.7
%を超えると凹部の生成数はプレス時に材料割れを引き
起こす70個を超えるが、0.7%以下では凹部の生成
数は70個以下となり、Al含有量の減少とともに凹部
の生成数は低下している。On the other hand, the formation of the recesses requires Al in the plating layer.
It was found that the content was related. FIG. 4 is a graph showing the relationship between the Al content in the plating layer and the number of recesses generated. As is clear from this figure, the number of recesses formed increased significantly as the Al content increased, and the Al content was 0.7%.
%, The number of generated recesses exceeds 70 which causes material cracking during pressing, but at 0.7% or less, the number of generated recesses becomes 70 or less, and the number of generated recesses decreases as the Al content decreases. ing.
【0019】めっき層中のAl含有量によって凹部の生
成数が変化する原因については、次の様に考えることが
できた。めっき層中のAlはめっき浴へ添加されたAl
に由来するものであり、めっき浴中のAl濃度が高くな
るとめっき層中のAl含有量も当然高くなる。めっき浴
に添加されたAlは、めっきの段階にて地鉄都の反応に
よって極めて薄いFe−Al合金層を形成するので、合
金化過程ではこの層を挟んでのFeとZnの拡散反応と
なる。ここでめっき浴中のAl濃度換言すればめっき層
中のAl含有量が低いとこの生成量が少なくなり、めっ
き層の大量のZnがこの層を通過して地鉄の結晶粒界と
結晶粒内を問わず、激しく合金化反応を起こすので、結
晶粒界と結晶粒内との合金化反応の差がなくなり、アウ
トバースト反応が抑制され、めっき層断面の凹部の生成
数が少なくなるものと考えられる。一方、めっき浴中の
Al濃度即ちめっき層中のAl含有量が高くなると、F
e−Al合金層の生成量が多くなり、地鉄面に到達する
めっき層のZnが大幅に制限され、僅かの量のZnが地
鉄の結晶粒界と結晶粒内にて合金化反応を起こす様にな
るので、結晶粒界と結晶粒内における合金化反応速度の
差が顕在化し、結晶粒界でのアウトバースト反応が促進
され、めっき層の凹部の生成数が多くなるものと考えら
れる。The reason why the number of recesses formed varies depending on the Al content in the plating layer can be considered as follows. Al in the plating layer is Al added to the plating bath
As a result, the higher the Al concentration in the plating bath, the higher the Al content in the plating layer. Since Al added to the plating bath forms an extremely thin Fe-Al alloy layer by the reaction of the base metal in the plating step, during the alloying process, a diffusion reaction of Fe and Zn occurs between the layers. . Here, in other words, the Al concentration in the plating bath, in other words, when the Al content in the plating layer is low, the amount of this generation is small, and a large amount of Zn in the plating layer passes through this layer and the grain boundaries of the base iron and the crystal grains. Since the alloying reaction occurs violently regardless of the inside, there is no difference in the alloying reaction between the grain boundaries and the inside of the crystal grains, the outburst reaction is suppressed, and the number of recesses on the cross section of the plating layer is reduced. Conceivable. On the other hand, when the Al concentration in the plating bath, that is, the Al content in the plating layer becomes high, F
The production amount of the e-Al alloy layer increases, Zn in the plating layer reaching the base iron surface is significantly limited, and a small amount of Zn causes an alloying reaction in the crystal grain boundaries of the base iron and in the crystal grains. It is considered that the difference in the alloying reaction rate between the crystal grain boundary and the crystal grain becomes apparent, the outburst reaction at the crystal grain boundary is promoted, and the number of recesses formed in the plating layer increases. .
【0020】本発明は、めっき層表面の凹部の生成数を
70個以下に調整する点に最大の特徴を有するものであ
り、これによってプレス成形の際に金型とめっき層間で
優れた摺動特性を発揮して良好な成形加工性を示して材
料割れの発生を防止するものであり、その為には上記の
ごとく素地鋼板中のP含有量を0.005%以上とする
ことが好ましいのであるが、このP含有量が過剰になる
とPが地鉄結晶粒界に大幅に濃化して材料の靭性を損な
うことがある。こうした観点から、P含有量は0.2%
以下とするのが好ましい。P含有量より好ましい範囲
は、0.01〜0.15%程度である。The present invention is most characterized in that the number of recesses formed on the surface of the plating layer is adjusted to 70 or less, which allows excellent sliding between the die and the plating layer during press molding. It is intended to exhibit characteristics and exhibit good forming workability to prevent the occurrence of material cracks. For that purpose, it is preferable that the P content in the base steel sheet be 0.005% or more as described above. However, if the P content becomes excessive, P may be significantly concentrated in the base iron crystal grain boundaries and impair the toughness of the material. From this viewpoint, the P content is 0.2%
It is preferable to set the following. A more preferable range than the P content is about 0.01 to 0.15%.
【0021】一方、めっき層中のAl含有量について
は、めっき表面の凹部の生成数を70個以下とするため
には、0.7%以下にすることが好ましいことは前述し
た通りであるが、このAl含有量が微量になって0.1
5%未満になると、合金化の反応速度が著しく速くな
り、めっき耐剥離性に悪影響を及ぼすΓ相の成長を抑制
することができなくなる。こうした観点から、めっき層
中のAl含有量は、0.15〜0.7%とするのが良
く、より好ましくは0.2〜0.6%程度とするのが良
い。On the other hand, as described above, the Al content in the plating layer is preferably 0.7% or less in order to reduce the number of recesses formed on the plating surface to 70 or less. , The Al content became very small and was 0.1
If it is less than 5%, the reaction rate of alloying becomes remarkably high, and it becomes impossible to suppress the growth of the Γ phase, which adversely affects the plating peel resistance. From this point of view, the Al content in the plated layer is preferably 0.15 to 0.7%, more preferably about 0.2 to 0.6%.
【0022】尚めっき層中には、合金化の際に必然的に
Feも含まれることになるが、このFeの含有量は8%
以上とするのが好ましく、8%未満であるとめっき層に
ζ相が多く存在することになり、材料割れを引き起こす
ことになる。またこのFe含有量が過剰になって17%
を超えると、めっき耐剥離性悪影響を及ぼすΓ相のの成
長を抑えることができなくなる。こうした観点から、め
っき層中のFe含有量は、8〜17%とするのが良く、
より好ましくは9〜16%程度とするのが良い。Although Fe is inevitably contained in the plated layer during alloying, the Fe content is 8%.
The above content is preferable, and if it is less than 8%, a large amount of ζ phase exists in the plating layer, which causes material cracking. In addition, the Fe content becomes excessive and is 17%.
If it exceeds, it becomes impossible to suppress the growth of the Γ phase, which adversely affects the plating peeling resistance. From this viewpoint, the Fe content in the plating layer is preferably 8 to 17%,
More preferably, it is about 9 to 16%.
【0023】前述のごとく本発明の合金化溶融亜鉛めっ
き鋼板のめっき層表面には、必要によってケイ酸または
ケイ酸塩含有皮膜を被覆しても良く、これによって前記
しためっき層の効果と相俟って摺動特性の更なる向上を
図ることができる。即ち、この皮膜は微細なシリカ粒子
からなる強固な硬質皮膜であり、この様な皮膜を形成す
ることによってめっき層表面の潤滑性が向上し、プレス
成形の際にめっき表層部に加えられる摺動変形抵抗を小
さくすることができるのである。またこの皮膜形成する
ことによって、化成処理性も向上することになる。As described above, the surface of the plated layer of the galvannealed steel sheet of the present invention may be coated with a silicic acid- or silicate-containing coating, if necessary, which contributes to the effect of the above-mentioned plated layer. Therefore, the sliding characteristics can be further improved. That is, this film is a strong hard film composed of fine silica particles, and by forming such a film, the lubricity of the plating layer surface is improved, and the sliding applied to the plating surface layer during press molding. The deformation resistance can be reduced. Further, by forming this film, the chemical conversion treatability is also improved.
【0024】上記皮膜による効果を発揮させるために
は、前述の如くこの被膜中のケイ酸またはケイ酸塩が、
乾燥後のSiO2 重量に換算して1〜200mg/m2
であることが必要である。その理由について図面を用い
て詳細に説明する。In order to exert the effect of the above-mentioned film, the silicic acid or silicate in this film is
1 to 200 mg / m 2 converted to the weight of SiO 2 after drying
It is necessary to be. The reason will be described in detail with reference to the drawings.
【0025】図5は、合金化溶融亜鉛めっき鋼板にケイ
酸またはケイ酸塩含有皮膜を塗布した場合の、SiO2
の含有量と、潤滑性および化成処理性との関係を示すグ
ラフである。このとき潤滑性の指標としては摩擦係数を
用い、化成処理性についてはリン酸処理性で代表させ
た。また合金化溶融亜鉛めっき鋼板は、素地鋼中のPの
含有量が0.06%、めっき層中のAl含有量が0.4
0%、めっき層中のFeの含有量が11.0%、めっき
表面の凹部の個が35個(めっき層表面の水平方向3m
m当たり)のものを用いた。FIG. 5 shows SiO 2 when a coating film containing silicic acid or a silicate is applied to a galvannealed steel sheet.
3 is a graph showing the relationship between the content of the above and the lubricity and chemical conversion treatability. At this time, the friction coefficient was used as an index of lubricity, and the chemical conversion treatability was represented by phosphoric acid treatability. The alloyed hot-dip galvanized steel sheet has a P content of 0.06% in the base steel and an Al content of 0.4 in the plating layer.
0%, the content of Fe in the plating layer is 11.0%, the number of recesses on the plating surface is 35 (the horizontal direction of the plating layer is 3 m.
(per m) was used.
【0026】このうち、摩擦係数は以下に示す平面摺動
試験にて測定した。 [サンプルサイズ]:40×300mm [工具]:平面工具(18×20mm) [加圧力]:5kg/mm2 [摺動速度]:300mm/min [摺動長さ]:150mm [塗油]:ノックスラスト550(パーカー興産製),
2g/m2 具体的には、引き抜き荷重を測定し、面圧と引き抜荷重
から摩擦係数を算出した。Of these, the coefficient of friction was measured by the following plane sliding test. [Sample size]: 40 × 300 mm [Tool]: Flat tool (18 × 20 mm) [Pressing force]: 5 kg / mm 2 [Sliding speed]: 300 mm / min [Sliding length]: 150 mm [Coating oil]: Knox Last 550 (manufactured by Parker Kosan),
2 g / m 2 Specifically, the pulling load was measured, and the friction coefficient was calculated from the surface pressure and the pulling load.
【0027】また、リン酸塩処理は、以下の方法で評価
した。 [リン酸塩処理液]:SD5000(日本ペイント社
製) [工程]:脱脂→水洗→表面調整→リン酸塩処理 [リン酸塩皮膜の判定]:SEMにより皮膜を観察し、
以下に示す評価基準に従って分類した。 ○:皮膜が均一に形成 △:部分的に皮膜が形成 ×:皮膜が形成されないThe phosphate treatment was evaluated by the following method. [Phosphate treatment liquid]: SD5000 (manufactured by Nippon Paint Co., Ltd.) [Process]: Degreasing → Washing → Surface adjustment → Phosphate treatment [Phosphate film determination]: SEM observation of the film,
It was classified according to the following evaluation criteria. :: Uniform film formation △: Partial film formation ×: No film formation
【0028】図5から明らかな様に、SiO2 含有量が
1mg/m2 以上になると、摩擦係数は顕著に低下して
いることがわかる。しかしながら、SiO2 含有量が2
00mg/m2 を超えると、潤滑性は良好であるが、リ
ン酸処理性が著しく劣化していることがわかる。この結
果から明らかな様に、ケイ酸またはケイ酸塩含有皮膜を
被覆する場合には、被膜中のケイ酸またはケイ酸塩が、
乾燥後のSiO2 重量に換算して1〜200mg/m2
であることが必要である。尚上記SiO2 含有量の好ま
しい下限値は、20mg/m2 であり、より好ましくは
40mg/m2である。また上記SiO2 含有量の好ま
しい上限値は、100mg/m2 であり、より好ましく
は80mg/m2 である。As is apparent from FIG. 5, when the SiO 2 content is 1 mg / m 2 or more, the friction coefficient is remarkably lowered. However, if the SiO 2 content is 2
It can be seen that when the amount exceeds 00 mg / m 2 , the lubricity is good, but the phosphoric acid treatment property is significantly deteriorated. As is clear from this result, when coating a silicic acid- or silicate-containing coating, the silicic acid or silicate in the coating is
1 to 200 mg / m 2 converted to the weight of SiO 2 after drying
It is necessary to be. The lower limit of the SiO 2 content is preferably 20 mg / m 2 , and more preferably 40 mg / m 2 . The preferable upper limit of the SiO 2 content is 100 mg / m 2 , and more preferably 80 mg / m 2 .
【0029】尚合金化溶融亜鉛めっき鋼板にケイ酸また
はケイ酸塩含有皮膜を被覆するには、具体的には該鋼板
にケイ酸コロイド溶液またはケイ酸塩水溶液を塗布して
乾燥すれば良い。このとき用いるケイ酸コロイド溶液と
しては、コロイダルシリカの市販品(例えば、日産化学
製スノーテックスシリーズ)等を用いれば良い。またケ
イ酸塩水溶液としては、ケイ酸ナトリウム,ケイ酸カリ
ウム,ケイ酸リチウム等が挙げられる。In order to coat the alloyed hot-dip galvanized steel sheet with the silicic acid- or silicate-containing coating, specifically, the steel sheet may be coated with a silicic acid colloidal solution or a silicate aqueous solution and dried. As the silicic acid colloid solution used at this time, a commercially available product of colloidal silica (for example, Snowtex series manufactured by Nissan Chemical Co., Ltd.) may be used. Examples of the silicate aqueous solution include sodium silicate, potassium silicate, lithium silicate and the like.
【0030】上記ケイ酸コロイド溶液やケイ酸塩水溶液
を合金化溶融亜鉛めっき鋼板の表面に塗布する方法につ
いては、特に限定されるものではないが、例えば上記水
溶液中に浸漬させる方法、ロールコータで塗布する方
法、スプレーで塗布する方法の他、通常知られている一
般的な様々な方法を適宜選択することができる。The method of applying the silicic acid colloidal solution or the silicate aqueous solution to the surface of the galvannealed steel sheet is not particularly limited, but it may be immersed in the aqueous solution or a roll coater, for example. In addition to the application method and the spray application method, various commonly known general methods can be appropriately selected.
【0031】以下、実施例に基づいて本発明を詳述する
が、下記実施例は本発明を制限するものではなく、前・
後記の趣旨を逸脱しない範囲で変更実施することは全て
本発明の技術範囲に包含される。Hereinafter, the present invention will be described in detail based on examples, but the following examples do not limit the present invention.
Modifications and alterations that do not depart from the spirit described below are all included in the technical scope of the present invention.
【0032】[0032]
実施例1 Tiを0.04%含む極低炭素鋼を用い、溶融亜鉛めっ
きラインにて溶融亜鉛めっき処理および合金化処理を施
し、下記表1に示す様に、素地鋼板中のP含有量、めっ
き層中のAl含有量およびFe含有量を変化させた各種
の合金化溶融亜鉛めっき鋼板を製造した。得られた合金
化溶融亜鉛めっき鋼板について、めっき層表面の凹部の
生成数(めっき層表面の水平方向長さ3mm当たりの個
数)を測定すると共に、自動車実プレステストに供試
し、材料割れの発生状況について調査した。Example 1 Using an ultra low carbon steel containing 0.04% of Ti, hot dip galvanizing and alloying were performed in a hot dip galvanizing line, and as shown in Table 1 below, P content in a base steel sheet, Various alloyed hot-dip galvanized steel sheets in which the Al content and the Fe content in the plated layer were changed were manufactured. With respect to the obtained galvannealed steel sheet, the number of recesses formed on the surface of the plating layer (the number per horizontal length of 3 mm of the plating layer surface) was measured and tested in an actual automobile press test to cause material cracking. I investigated the situation.
【0033】その結果を、表1に併記するが、本発明で
規定する要件を全て満足する実施例のものは、いずれも
優れたプレス成形性を示し、材料割れの発生が効果的に
防止されていることがわかる。The results are also shown in Table 1. All of the examples satisfying all the requirements specified in the present invention exhibit excellent press formability and the occurrence of material cracks is effectively prevented. You can see that
【0034】[0034]
【表1】 [Table 1]
【0035】実施例2 Tiを0.04%含む極低炭素鋼を用い、溶融亜鉛めっ
きラインにて溶融亜鉛めっき処理および合金化処理を施
し、下記表2に示す様に、素地鋼板中のP含有量、めっ
き層中のAl含有量およびFe含有量を変化させた各種
の合金化溶融亜鉛めっき鋼板を製造した。Example 2 Using ultra-low carbon steel containing 0.04% of Ti, hot dip galvanizing and alloying were performed in a hot dip galvanizing line, and as shown in Table 2 below, P in the base steel sheet Various alloyed hot-dip galvanized steel sheets having different contents, Al contents in the plating layer and Fe contents were manufactured.
【0036】この合金化溶融亜鉛めっき鋼板について、
めっき層表面の凹部の生成数(めっき層表面の水平方向
長さ3mm当たりの個数)を測定した後、この合金化溶
融亜鉛めっき鋼板の表面にケイ酸(SiO2 コロイド溶
液)またはケイ酸塩を、絞りロールを用いて塗布した。
塗布後80℃で乾燥し、硬質のSiO2 皮膜を形成させ
た。Regarding this alloyed hot-dip galvanized steel sheet,
After measuring the number of recesses formed on the surface of the plating layer (the number per horizontal length of 3 mm on the surface of the plating layer), silicic acid (SiO 2 colloidal solution) or silicate was applied to the surface of the galvannealed steel sheet. It was applied using a squeeze roll.
After coating, it was dried at 80 ° C. to form a hard SiO 2 film.
【0037】得られた材料について、自動車実プレステ
ストに供試し、材料割れの発生状況について調査すると
共に、前記した方法によって摩擦係数、リン酸塩処理性
を評価した。その結果を、表2に併記するが、本発明で
規定する要件を全て満足する実施例のものは、いずれも
優れたプレス成形性を示し、材料割れの発生が効果的に
防止されていることがわかる。またケイ酸またはケイ酸
塩含有皮膜を被覆することによって、良好な潤滑性と共
にリン酸塩処理性にも優れたものとなっていることがわ
かる。The obtained material was tested in an actual press test for automobiles, the occurrence of material cracks was investigated, and the friction coefficient and the phosphate treatment property were evaluated by the above-mentioned methods. The results are also shown in Table 2, and all of the examples satisfying all the requirements specified in the present invention show excellent press formability, and the occurrence of material cracks is effectively prevented. I understand. Further, it can be seen that the coating of the silicic acid- or silicate-containing film provides excellent lubricity as well as excellent phosphatability.
【0038】[0038]
【表2】 [Table 2]
【0039】[0039]
【発明の効果】本発明は上記の様に構成されており、め
っき層の金型との摺動特性を向上させてプレス成形性を
良好にし、プレス成形時の材料割れの発生を防止できる
合金化溶融亜鉛めっき鋼板が実現でき、この鋼板は特に
自動車用として有用である。EFFECTS OF THE INVENTION The present invention is constituted as described above, and is an alloy capable of improving the sliding property of the plating layer with respect to the mold to improve press formability and preventing the occurrence of material cracks during press forming. A hot-dip galvanized steel sheet can be realized, and this steel sheet is particularly useful for automobiles.
【図1】合金化溶融亜鉛めっき鋼板の表面性状を模式的
に示した図である。FIG. 1 is a view schematically showing the surface texture of an alloyed hot-dip galvanized steel sheet.
【図2】めっき層中に存在する凹部の個数と材料割れの
関係について示したグラフである。FIG. 2 is a graph showing the relationship between the number of recesses present in the plating layer and material cracking.
【図3】鋼中のP含有量と凹部の生成数との関係を示す
グラフである。FIG. 3 is a graph showing the relationship between the P content in steel and the number of recesses formed.
【図4】めっき層中のAl含有量と凹部の生成数との関
係を示すグラフである。FIG. 4 is a graph showing the relationship between the Al content in the plating layer and the number of recesses formed.
【図5】塗膜のSiO2 の含有量と、潤滑性および化成
処理性との関係を示すグラフである。FIG. 5 is a graph showing the relationship between the content of SiO 2 in the coating film and the lubricity and chemical conversion treatability.
Claims (4)
層が形成された合金化溶融亜鉛めっき鋼板において、前
記合金化溶融亜鉛めっき層は、めっき層厚が2μm以下
の凹部がめっき層表面の水平方向長さ3mm当たりで7
0個以下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。1. An alloyed hot-dip galvanized steel sheet in which an alloyed hot-dip galvanized layer is formed on the surface of a base steel sheet, wherein the alloyed hot-dip galvanized layer has recesses with a plating layer thickness of 2 μm or less on the surface of the plating layer. 7 per horizontal length of 3 mm
An alloyed hot-dip galvanized steel sheet excellent in press formability, which is characterized in that the number is 0 or less.
2%(質量%の意味、以下同じ)を含むものである請求
項1に記載の合金化溶融亜鉛めっき鋼板。2. The base steel sheet, P: 0.005 ~ 0.
The alloyed hot-dip galvanized steel sheet according to claim 1, which contains 2% (meaning mass%, the same applies hereinafter).
7%を含むものである請求項1または2に記載の合金化
溶融亜鉛めっき鋼板。3. The plating layer comprises Al: 0.15 to 0.
The galvannealed steel sheet according to claim 1 or 2, which contains 7%.
またはケイ酸塩含有皮膜が被覆され、該被膜中のケイ酸
またはケイ酸塩が、乾燥後のSiO2 重量に換算して1
〜200mg/m2 である請求項1〜3のいずれかに記
載の合金化溶融亜鉛めっき鋼板。4. A silicic acid- or silicate-containing film is coated on the surface of the galvannealed layer, and the silicic acid or silicate in the film is 1 in terms of SiO 2 weight after drying.
-200 mg / m < 2 > The galvannealed steel sheet according to any one of claims 1 to 3.
Priority Applications (1)
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JP01397096A JP3275686B2 (en) | 1996-01-30 | 1996-01-30 | Galvannealed steel sheet with excellent press formability |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP01397096A JP3275686B2 (en) | 1996-01-30 | 1996-01-30 | Galvannealed steel sheet with excellent press formability |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH09209107A true JPH09209107A (en) | 1997-08-12 |
JP3275686B2 JP3275686B2 (en) | 2002-04-15 |
Family
ID=11848089
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Application Number | Title | Priority Date | Filing Date |
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JP01397096A Expired - Fee Related JP3275686B2 (en) | 1996-01-30 | 1996-01-30 | Galvannealed steel sheet with excellent press formability |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11217660A (en) * | 1998-01-30 | 1999-08-10 | Sumitomo Metal Ind Ltd | Hot dip galvannealed steel sheet and its production |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0718403A (en) * | 1993-06-30 | 1995-01-20 | Nkk Corp | Galvannealed steel sheet excellent in press formability |
JPH0827556A (en) * | 1994-07-12 | 1996-01-30 | Nkk Corp | Galvannealed steel sheet excellent in press formability, image clarity after coating and powdering resistance |
JPH08253849A (en) * | 1995-03-16 | 1996-10-01 | Nippon Steel Corp | Galvannealed steel sheet excellent in electrodeposition coating suitability |
-
1996
- 1996-01-30 JP JP01397096A patent/JP3275686B2/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0718403A (en) * | 1993-06-30 | 1995-01-20 | Nkk Corp | Galvannealed steel sheet excellent in press formability |
JPH0827556A (en) * | 1994-07-12 | 1996-01-30 | Nkk Corp | Galvannealed steel sheet excellent in press formability, image clarity after coating and powdering resistance |
JPH08253849A (en) * | 1995-03-16 | 1996-10-01 | Nippon Steel Corp | Galvannealed steel sheet excellent in electrodeposition coating suitability |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11217660A (en) * | 1998-01-30 | 1999-08-10 | Sumitomo Metal Ind Ltd | Hot dip galvannealed steel sheet and its production |
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