JPH0816261B2 - Method for producing galvannealed steel sheet having excellent press formability and powdering resistance - Google Patents
Method for producing galvannealed steel sheet having excellent press formability and powdering resistanceInfo
- Publication number
- JPH0816261B2 JPH0816261B2 JP2327283A JP32728390A JPH0816261B2 JP H0816261 B2 JPH0816261 B2 JP H0816261B2 JP 2327283 A JP2327283 A JP 2327283A JP 32728390 A JP32728390 A JP 32728390A JP H0816261 B2 JPH0816261 B2 JP H0816261B2
- Authority
- JP
- Japan
- Prior art keywords
- bath
- plating
- alloying
- phase
- steel
- 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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- 229910000831 Steel Inorganic materials 0.000 title claims description 54
- 239000010959 steel Substances 0.000 title claims description 54
- 238000000227 grinding Methods 0.000 title claims description 33
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 238000007747 plating Methods 0.000 claims description 70
- 238000010438 heat treatment Methods 0.000 claims description 66
- 238000005275 alloying Methods 0.000 claims description 60
- 230000006698 induction Effects 0.000 claims description 24
- 239000011248 coating agent Substances 0.000 claims description 16
- 238000000576 coating method Methods 0.000 claims description 16
- 229910001335 Galvanized steel Inorganic materials 0.000 claims description 11
- 239000008397 galvanized steel Substances 0.000 claims description 11
- 230000035515 penetration Effects 0.000 claims description 11
- 239000011701 zinc Substances 0.000 claims description 11
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 6
- 229910052725 zinc Inorganic materials 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910052712 strontium Inorganic materials 0.000 claims description 3
- 229910052720 vanadium Inorganic materials 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 32
- 239000010410 layer Substances 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 14
- 238000000034 method Methods 0.000 description 14
- 229910000655 Killed steel Inorganic materials 0.000 description 7
- 229910001297 Zn alloy Inorganic materials 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 239000002436 steel type Substances 0.000 description 4
- 230000001629 suppression Effects 0.000 description 4
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 230000003449 preventive effect Effects 0.000 description 3
- 238000000137 annealing Methods 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 229910001315 Tool steel Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 229910000905 alloy phase Inorganic materials 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003618 dip coating Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 238000007586 pull-out test Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910000601 superalloy Inorganic materials 0.000 description 1
- -1 that is Substances 0.000 description 1
Landscapes
- Coating With Molten Metal (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、自動車の車体、足回り部品等に用いられ
る合金化溶融亜鉛めっき鋼板、より詳細には所謂IF鋼を
めっき原板とし、プレス成形時に要求される耐パウダリ
ング性に優れ、しかも摩擦特性がコイル内で安定した合
金化溶融亜鉛めっき鋼板の製造方法に関する。The present invention relates to an alloyed hot dip galvanized steel sheet used for automobile bodies, underbody parts, and the like, more specifically, so-called IF steel, which is used as a plating base sheet, and is press-formed. The present invention relates to a method for producing an alloyed hot-dip galvanized steel sheet which is excellent in powdering resistance, which is sometimes required, and whose frictional characteristics are stable in a coil.
合金化溶融亜鉛めっき鋼板は優れた塗装後耐食性や溶
接性を有するため、自動車用防錆鋼板としてその需要が
近年増加しており、特に最近では、耐食性を確保するた
め皮膜が厚目付化する傾向にある。また、このような合
金化溶融亜鉛めっき鋼板のめっき原板として所謂IF鋼
（Interstitial Free Steel）が用いられている。Since galvannealed steel sheets have excellent post-painting corrosion resistance and weldability, the demand for them as rust preventive steel sheets for automobiles has been increasing in recent years, and in particular, recently, the coating tends to be thicker in order to ensure corrosion resistance. It is in. In addition, a so-called IF steel (Interstitial Free Steel) is used as a plating original plate of such an alloyed hot-dip galvanized steel sheet.
この種のめっき鋼板には、優れたプレス成形性とプレ
ス成形時の耐皮膜剥離性、所謂耐パウダリング性が要求
される。特に最近ではこれらについてより厳しい性能が
求められ、とりわけ上記のような皮膜の厚目付化に伴
い、耐パウダリング性の確保がより大きな課題となりつ
つある。This type of plated steel sheet is required to have excellent press formability, film peeling resistance during press forming, and so-called powdering resistance. Particularly in recent years, more stringent performances have been demanded for these, and particularly with the increase in the coating weight of the film as described above, securing powdering resistance is becoming a greater issue.
このような耐パウダリング性を改善する方法として、
例えば、特公昭59−14541号公報等に示されるように、
めっき鋼板を急速加熱で１次加熱して皮膜の一部を合金
化させた後、バッチ焼鈍で２次加熱を行うという技術が
知られているが、この方法は耐パウダリング性の改善に
は有効であるものの、製造コストが高いという欠点があ
る。As a method of improving such powdering resistance,
For example, as shown in Japanese Patent Publication No. 59-14541,
A technique is known in which a plated steel sheet is primarily heated by rapid heating to partially alloy the coating, and then secondary annealing is performed by batch annealing, but this method is effective for improving powdering resistance. Although effective, it has the drawback of high manufacturing costs.
一方、インラインにおいて耐パウダリング性を改善す
る技術として、特開昭64−17843号公報において、Al:0.
003〜0.13％めっき浴でめっき後、低温（520〜470℃の
範囲で且つAl％が低いほど低温側）で合金化処理を施す
ことにより、めっき表層に耐パウダリング性に有効なζ
相を残留させるという技術が開示されている。On the other hand, as a technique for improving the powdering resistance in-line, in JP-A 64-17843, Al: 0.
After plating with a 003 to 0.13% plating bath, alloying treatment is performed at a low temperature (in the range of 520 to 470 ° C and the lower the Al%, the lower the temperature), so that the plating surface layer is effective for powdering resistance ζ.
A technique of leaving a phase is disclosed.
しかし、この方法は低温で合金化処理するため、処理
時間が長くなり、ライン速度を遅くするか、設備を大型
化することが必要となり、いずれにしても生産性の低下
や設備コストの増大が避けられない。However, since this method performs alloying treatment at a low temperature, the treatment time becomes long, and it is necessary to slow down the line speed or enlarge the equipment, and in any case, the productivity is lowered and the equipment cost is increased. Unavoidable.
さらに、通常用いられているガス直火加熱方式の合金
炉では、ストリップ幅方向及び長さ方向での板温の変動
が起りやすいため、上述したような皮膜構造の厳密な制
御は困難であり、得られるめっき皮膜は部分的に過合金
或いはη相（純亜鉛相）が残留したものとなってしま
う。したがって、得られるめっき鋼板は場所によってζ
相の量が不均一な、すなわち、鋼板の各部で耐パウダリ
ング性が不均一なものとなってしまう。Furthermore, in the alloy furnace of the gas direct-fired heating method which is usually used, since the variation of the strip temperature in the strip width direction and the length direction is likely to occur, it is difficult to strictly control the coating structure as described above. The obtained plating film partially becomes a superalloy or an η phase (pure zinc phase) remains. Therefore, the obtained plated steel sheet may be ζ depending on the location.
The amount of phases is non-uniform, that is, the powdering resistance is non-uniform in each part of the steel sheet.
また、上記のような合金化めっき層上に上層めっきを
施すことにより摩擦係数を減少させ、プレス成形性を改
善することができるが、上記のようにζ相の量が不均一
な状態では、そのプレス成形性も不安定なものとなって
しまう。Further, by applying the upper layer plating on the alloyed plating layer as described above, the friction coefficient can be reduced and the press formability can be improved, but in the state where the amount of ζ phase is non-uniform as described above, The press formability also becomes unstable.
以上のような従来の問題に対し、本発明者らは、ま
ず、溶融亜鉛めっき鋼板の合金化反応に関して検討を行
い、その結果、ｉ）ζ相は495℃以下の反応により発生
し、それ以上では発生しないこと、ii）したがって、49
5℃以下で主要な反応（溶融亜鉛相がなくなるまでの反
応）を起し、その後冷却すれば、ζ相が残留した皮膜を
形成することができること、が明らかとなった。第１図
（ａ）、（ｂ）は溶融亜鉛めっき鋼板の450℃、500℃で
の恒温合金化反応による相変化の一例を示すもので、45
0℃での合金化ではζ相が発生するのに対し、500℃での
合金化ではζ相はほとんど発生しない。With respect to the conventional problems as described above, the present inventors first investigated the alloying reaction of hot-dip galvanized steel sheet, and as a result, i) ζ phase was generated by the reaction at 495 ° C. or lower, and further Ii) Therefore, 49
It was clarified that a major reaction (reaction until the molten zinc phase disappears) occurs at 5 ° C or lower, and then the film is cooled to form a film in which the ζ phase remains. FIGS. 1 (a) and 1 (b) show an example of the phase change of the galvanized steel sheet at 450 ° C. and 500 ° C. due to the isothermal alloying reaction.
In the alloying at 0 ° C, the ζ phase is generated, whereas in the alloying at 500 ° C, the ζ phase is hardly generated.
しかし上述したように、このように低温で合金化する
方法では合金化完了までに長時間を要するため、ライン
スピードの低下、設備の大型化を余儀なくされる。さら
に、通常の直火加熱方式の合金化炉を用いて上記条件で
合金化すると、焼きムラが発生し易く、不均一な合金層
が形成されてしまう。このような焼きムラを防止しよう
とすると炉温を上げて合金化する必要があるが、高温で
の合金化処理ではζ相が残留せず、耐パウダリング性の
劣ったもととなる。一方、IF鋼はAlキルド鋼に較べ粒界
での反応性に富むため、ζ相を適切に形成させるために
は、合金化に関しAlキルド鋼とは異なる配慮が必要とな
るものと考えられる。However, as described above, in such a method of alloying at a low temperature, it takes a long time to complete the alloying, so that the line speed is lowered and the equipment is inevitably enlarged. Furthermore, when alloying is performed under the above conditions using a normal direct-fired heating type alloying furnace, uneven baking is likely to occur and a non-uniform alloy layer is formed. In order to prevent such burning unevenness, it is necessary to raise the furnace temperature for alloying, but in the alloying treatment at a high temperature, the ζ phase does not remain, resulting in poor powdering resistance. On the other hand, IF steel is more reactive at grain boundaries than Al-killed steel, so it is considered that different alloying considerations from Al-killed steel are necessary in order to properly form the ζ phase.
このようなことから、IF鋼を素材とする合金化溶融亜
鉛めっき鋼板に関し、耐パウダリング性とプレス成形性
の両者を安定的に得る方法について検討を重ねた結果、
以下のような知見を得た。From this, regarding the alloyed hot-dip galvanized steel sheet made of IF steel, as a result of repeated studies on a method for stably obtaining both powdering resistance and press formability,
The following findings were obtained.
ζ相は浴中でも495℃以下で形成され、Alキルド鋼
の場合には、低Al浴で且つ高めの侵入板温という条件で
めっきを施すことにより、めっき浴中で積極的にζ相を
形成させることができる。The ζ phase is formed at 495 ° C or less even in the bath, and in the case of Al killed steel, the ζ phase is positively formed in the plating bath by plating in a low Al bath and with a high penetration plate temperature. Can be made.
しかし、原板がIF鋼の場合には、低Al浴で且つ高めの
侵入板温によりめっき浴中で積極的にζ相形成反応を起
こさせると、これとほぼ同時に局部的且つ急激な合金化
反応（アウトバースト反応）が発生する。浴中でこのよ
うな反応が起こると、めっきがシンクロールとの接触に
より掻き落されてドロス発生の原因となる他、アウトバ
ースト反応発生直後にΓ相が成長し始めるため、最終的
に得られる皮膜はΓ相の厚く発達したものとなり、耐パ
ウダリグ性が非常に劣ったものとなる。したがって、め
っき原板がIF鋼の場合には浴中での合金化反応（アウト
バースト反応）を極力抑える必要がある。However, when the base plate is IF steel, when the ζ-phase forming reaction is positively caused in the plating bath with a low Al bath and a high intrusion plate temperature, a local and rapid alloying reaction occurs almost at the same time. (Outburst reaction) occurs. When such a reaction occurs in the bath, the plating is scraped off by contact with the sink roll and causes dross generation, and the Γ phase begins to grow immediately after the outburst reaction occurs, so it is finally obtained. The film has a thick developed Γ phase and is extremely inferior in powder rig resistance. Therefore, when the plating base plate is IF steel, it is necessary to suppress the alloying reaction (outburst reaction) in the bath as much as possible.
めっき原板がIF鋼の場合には、浴中で合金化抑制相
であるFe2Al5を厚く生成させることにより合金化反応に
抑え、その後の合金化処理を高周波誘導加熱方式の加熱
炉を用いて行うことにより、ストリップの幅方向、長手
方向で均一な量のζ相が残留した皮膜を短時間の合金化
処理で得ることができる。When the plating base plate is IF steel, the alloying reaction is suppressed by forming Fe 2 Al 5 that is an alloying suppression phase thickly in the bath, and the subsequent alloying treatment is performed using a high-frequency induction heating type heating furnace. By performing the above, it is possible to obtain a film in which a uniform amount of ζ phase remains in the width direction and the length direction of the strip by a short-time alloying treatment.
また、このようにして得られる合金化めっき皮膜
は、上述したようなマクロ的な均一性のみならず、ミク
ロ的にも合金化反応が均一に起きるため、この面からも
優れた耐パウダリング性が得られる， 浴条件と高周波誘導加熱方式の加熱炉の出側板温条
件を規定することにより、厳密な皮膜の制御が可能であ
る。In addition, the alloyed plating film thus obtained has not only the above-mentioned macroscopic uniformity but also the microscopically uniform alloying reaction. Strict control of the coating is possible by defining the bath conditions and the exit side plate temperature conditions of the high-frequency induction heating type heating furnace.
具体的には、浴中での合金化反応を抑えるには、浴中
のAl量を高め、しかも侵入板温を浴中Al量との関係で規
定される高めの温度とすることが有効である。すなわ
ち、このような条件でめっきを行うことにより、浴中に
侵入直後の鋼板表面に合金化抑制相であるFe2Al5が厚く
生成し、これが合金化を抑制する。Specifically, in order to suppress the alloying reaction in the bath, it is effective to increase the Al content in the bath and set the penetration plate temperature to a higher temperature defined by the relationship with the Al content in the bath. is there. That is, by performing plating under such conditions, a thick Fe 2 Al 5 alloying suppressing phase is formed on the surface of the steel sheet immediately after entering the bath, which suppresses alloying.
さらに、このように合金化反応を抑えられた鋼板は合
金化炉で合金化処理されるが、この際、加熱手段として
高周波誘導加熱方式の加熱炉を用い、しかも、加熱炉出
側での板温を495℃以下に管理して行うことにより、上
記、で述べたように均一且つ優れた耐パウダリグ性
を有する皮膜を得ることができる。Further, the steel sheet thus suppressed in alloying reaction is alloyed in an alloying furnace. At this time, a high-frequency induction heating type heating furnace is used as a heating means, and the plate on the exit side of the heating furnace is used. By controlling the temperature at 495 ° C. or lower, it is possible to obtain a film having uniform and excellent powder rig resistance as described above.
上記のようにして合金化されためっき皮膜に上層め
っきを施すことにより、少ない付着量で良好且つ均一な
プレス成形性が得られる。By applying the upper layer plating to the plating film alloyed as described above, good and uniform press formability can be obtained with a small adhesion amount.
本発明はこのような知見に基づきなされたもので、そ
の特徴とするところは、IF鋼、すなわちTi、Nb、Sr、Ｖ
等の炭化物形成元素を含み、これら元素の添加量Ｘと炭
素含有量〔Ｃ〕の原子％比がΣX/〔Ｃ〕≧１を満足する
鋼からなる鋼板をめっき原板とし、該鋼板に、Alを含有
し、残部Znおよび不可避的不純物からなる亜鉛めっき浴
でめっきを施した後、目付量調整を行い、加熱炉で皮膜
中のFe含有量が８〜12％となるように合金化処理を行う
合金化溶融亜鉛めっき鋼板の製造方法において、浴中Al
量:0.13％以上、浴温度:470℃以下で、且つ、浴中Al量
と鋼板のめっき浴中への侵入板温とが、 571×〔Al％〕＋410≧Ｔ≧571×〔Al％〕＋390 但し、〔Al％〕：浴中Al量（％） T:侵入板温（℃） を満足する条件でめっきを行うことにより、浴中で合金
化反応を抑制し、めっき後、高周波誘導加熱炉で加熱炉
出側の板温が495℃以下となるように加熱し、所定時間
保持後冷却し、次いで、上層めっきとしてFe含有量が50
％以上のFe系めっきを1g/m2以上施すようにしたことに
ある。The present invention has been made on the basis of such knowledge, and is characterized in that it is an IF steel, that is, Ti, Nb, Sr, V
A steel plate containing a carbide-forming element such as Al and having an atomic ratio of the addition amount X of these elements to the carbon content [C] satisfying ΣX / [C] ≧ 1 is used as a plating base plate, and the steel plate is made of Al. Containing zinc and plating with a zinc plating bath consisting of the balance Zn and unavoidable impurities, then adjusting the basis weight and alloying in a heating furnace so that the Fe content in the coating becomes 8-12%. In the method for producing an alloyed hot-dip galvanized steel sheet, the Al in the bath is
Amount: 0.13% or more, bath temperature: 470 ° C or less, and the amount of Al in the bath and the plate temperature of the steel plate that penetrates into the plating bath are 571 x [Al%] + 410 ≥ T ≥ 571 x [Al%] +390 However, [Al%]: Al amount in bath (%) T: Penetration plate temperature (° C) By plating under the conditions, the alloying reaction is suppressed in the bath, and high frequency induction heating is performed after plating. In the heating furnace, the plate temperature on the outlet side of the heating furnace is heated to 495 ° C or lower, kept for a predetermined time and then cooled, and then the Fe content is 50% as the upper layer plating.
% Of Fe-based plating is applied at 1 g / m 2 or more.
従来、めっき鋼板の合金化処理を高周波誘導加熱によ
り行うという技術は、例えば、特公昭60−8289号公報、
特開平２−37425号公報等において知られている。しか
し、これらに開示された技術は、高周波誘導加熱を単に
急速加熱の一手段として用いているに過ぎない。Conventionally, a technique of performing alloying treatment of a plated steel sheet by high frequency induction heating is disclosed in, for example, Japanese Patent Publication No. 60-8289.
It is known from JP-A-2-37425. However, the techniques disclosed therein merely use high-frequency induction heating as a means of rapid heating.
これに対して本発明は、浴中で合金化抑制相であるFe
2Al5を厚く生成させることにより合金化反応を極力抑制
し、且つこのように合金化が抑制されためっき皮膜に対
し、高周波誘導加熱による合金化処理を特定の条件で実
施することにより、Γ相が少なく鋼板各部においてζ相
が非常に均一に形成された、すなわち均一且つ優れた耐
パウダリング性を有するめっき鋼板が得られることを見
出したものである。On the other hand, the present invention is characterized in that the alloying suppression phase Fe
By suppressing the alloying reaction as much as possible by forming 2 Al 5 thickly, and performing the alloying treatment by the high frequency induction heating on the plating film in which the alloying is suppressed under such a condition, It was found that a plated steel sheet having few phases and very uniform ζ phase formed in each part of the steel sheet, that is, having uniform and excellent powdering resistance can be obtained.
本発明の製造法において、上述のような優れた特性の
めっき鋼板が得られるのは次のような理由によるものと
推定される。In the production method of the present invention, it is presumed that the reason why the plated steel sheet having the above excellent properties is obtained is as follows.
まず、第１に、合金化処理において高周波誘導加熱方
式を用いることにより、鋼板自体を直接加熱することが
でき、しかも、めっき皮膜に接する界面が最も加熱され
るため、雰囲気加熱方式に較べ界面におけるFe−Zn反応
が短時間でしかもストリップ上の位置に無関係に均一に
起き、このため、鋼板各部で均一な量のζ相が残留し、
均一な耐パウダリング性が得られるものと推定される。First, by using the high frequency induction heating method in the alloying process, the steel sheet itself can be directly heated, and the interface in contact with the plating film is heated most, so that the interface heating in the interface is higher than that in the atmosphere heating method. The Fe-Zn reaction takes place uniformly in a short time regardless of the position on the strip.Therefore, a uniform amount of ζ phase remains in each part of the steel sheet,
It is estimated that uniform powdering resistance can be obtained.
第２に、高周波誘導加熱は上記のように鋼板側からの
加熱であるため、微視的にも均一な合金化反応が生じる
ことによるものと推定される。すなわち、従来一般に行
われているガス加熱による合金化処理では、皮膜の外側
から熱が加えられるため加熱が不均一となり易く、この
ため合金化反応が微視的に不均一に生じ易い。特にIF鋼
は結晶粒界での反応性に富むため、所謂アウトバースト
反応が生じ易く、このようにアウトバースト組織が発生
すると、この部分からΓ相が成長し始め、このΓ相の形
成により耐パウダリング性が劣化する。これに対し、高
周波誘導加熱は鋼板側からの加熱であるため、上記のよ
うな合金化の局部的なバラツキが少なく、ミクロ的にも
均一な合金化皮膜が得られるものと思われる。Secondly, since the high-frequency induction heating is heating from the steel sheet side as described above, it is presumed that a uniform alloying reaction occurs microscopically. That is, in the conventional alloying treatment by gas heating, which is generally performed, heat is applied from the outside of the film, so that the heating is likely to be nonuniform, and thus the alloying reaction is likely to be microscopically nonuniform. In particular, IF steel is highly reactive at the grain boundaries, so the so-called outburst reaction is likely to occur, and when an outburst structure is generated in this way, the Γ phase begins to grow from this part, and due to the formation of this Γ phase The powdering property deteriorates. On the other hand, since the high-frequency induction heating is heating from the steel sheet side, it is considered that the above-mentioned local alloying variation is small and a microscopically uniform alloyed film can be obtained.
第３に、本発明は合金化抑制相であるFe2Al5を浴中で
形成させることによりFe−Zn反応を抑制し、続く加熱処
理においてζ相を形成させることを特徴としているが、
上記のように高周波誘導加熱は鋼板側からの加熱である
ため、合金化時にFe2Al5が容易に拡散しζ相を形成す
る。つまり、Fe−Zn反応を適切に抑制するためにFe2Al5
を厚く形成させても、合金化時にこれを確実且つ均一に
拡散することができる。この結果、合金化がミクロ的に
も均一化し、厚いFe2Al5の形成により浴中でのΓ相の発
生が抑制されることと相俟って、優れた耐パウダリング
性が得られるものと考えられる。Thirdly, the present invention is characterized in that the Fe—Zn reaction is suppressed by forming Fe 2 Al 5 which is an alloying suppression phase in the bath, and the ζ phase is formed in the subsequent heat treatment.
Since high-frequency induction heating is heating from the steel sheet side as described above, Fe 2 Al 5 easily diffuses during alloying to form a ζ phase. That is, in order to suppress the Fe-Zn reaction appropriately, Fe 2 Al 5
Even if it is formed thick, it can be diffused reliably and uniformly during alloying. As a result, alloying is microscopically uniform, and the formation of thick Fe 2 Al 5 suppresses the generation of the Γ phase in the bath, resulting in excellent powdering resistance. it is conceivable that.
第４に、高周波誘導加熱はめっき皮膜を短時間で合金
化できることからΓ相の成長時間が短いことが挙げられ
る。そして、本発明では浴中でのΓ相の発生も抑えられ
るため、最終的なΓ相の形成量が少なく、このことも耐
パウダリング性の向上に大きく寄与しているものと考え
られる。Fourthly, since the high frequency induction heating can alloy the plating film in a short time, the Γ phase growth time is short. Further, in the present invention, since the generation of the Γ phase in the bath can be suppressed, the final formation amount of the Γ phase is small, which is also considered to greatly contribute to the improvement of the powdering resistance.
また、プレス成形性に関しても、上記したように合金
化がマクロ、ミクロに均一になされる結果、安定的且つ
均一なプレス成形性が得られ、しかも溶融めっき後の加
熱を高周波誘導加熱で行うと、めっき表面が酸化されな
いため、合金化めっき層上に上層めっきを適切に付着さ
せることができ、このためガス加熱で合金化処理した場
合に較べ少ない付着量の上層めっきにより安定したプレ
ス成形性が得られるものと考えられる。As for the press formability, as described above, the alloying is made macroscopically and microscopically uniform, so that stable and uniform press formability can be obtained, and if the heating after hot dip coating is performed by high frequency induction heating. Since the plating surface is not oxidized, the upper layer plating can be properly adhered to the alloyed plating layer. Therefore, a smaller amount of the upper layer plating than that in the case of alloying treatment by gas heating provides stable press formability. It is thought to be obtained.
以下、本発明の構成とその限定理由について説明す
る。Hereinafter, the configuration of the present invention and the reason for the limitation will be described.
本発明におけるめっき原板は所謂IF鋼である。IF鋼は
Ti、Nb、Sr、Ｖ等の炭化物形成元素を含み、これらの元
素の添加量Ｘと炭素含有量〔Ｃ〕の原子％比がΣX/
〔Ｃ〕≧１を満足する鋼として定義することができる。
鋼中に微量の固溶Ｃが存在する場合、結晶粒界に偏析し
て存在する。アウトバースト反応は結晶粒界で優先的に
形成されるため、IF鋼のように粒界で清浄化された鋼で
はこの部分での反応性が高まり、アウトバースト反応が
起きやすくなる。The plating original plate in the present invention is so-called IF steel. IF steel
It contains carbide forming elements such as Ti, Nb, Sr and V, and the atomic% ratio of the addition amount X of these elements and the carbon content [C] is ΣX /
It can be defined as steel satisfying [C] ≧ 1.
When a small amount of solute C is present in steel, it is segregated and present in the grain boundaries. Since the outburst reaction is preferentially formed at the grain boundaries, in steels that have been cleaned at the grain boundaries, such as IF steel, the reactivity at this part is increased and the outburst reaction easily occurs.
本発明では、めっき浴中での合金化反応を極力抑制す
るため、めっき浴中のAl量、めっき浴に侵入する際の鋼
板の板温及び浴温度が規定される。特に、本発明では高
Al浴で且つ浴中Al量との関係で規定される高目の侵入板
温とすることにより、めっき浴中での合金化反応を抑制
することが特徴の１つである。In the present invention, in order to suppress the alloying reaction in the plating bath as much as possible, the amount of Al in the plating bath, the plate temperature of the steel sheet when entering the plating bath, and the bath temperature are specified. Especially in the present invention,
One of the features is that the alloying reaction in the plating bath is suppressed by using a high penetration plate temperature that is defined in relation to the Al bath and the amount of Al in the bath.
めっき浴中のAlは浴侵入直後の鋼板表面にFe2Al5を形
成し、Fe−Zn合金の発生を抑制する。Al量が0.13％未満
ではこのような抑制効果が小さく、粒界での反応性に富
むIF鋼の場合には浴中でアウトバースト反応が発生して
しまう。このため浴中のAl量は0.13％以上とする。Al in the plating bath forms Fe 2 Al 5 on the surface of the steel sheet immediately after entering the bath, and suppresses the generation of Fe-Zn alloy. When the Al content is less than 0.13%, such a suppressing effect is small, and in the case of IF steel having high reactivity at grain boundaries, an outburst reaction occurs in the bath. Therefore, the amount of Al in the bath should be 0.13% or more.
Al量を0.13％以上含む浴では侵入板温を上昇させると
鋼板侵入直後の反応温度が高くなり、Fe2Al5が厚く形成
されるようになる。この結果、浴中でのFe−Zn合金発生
が抑制される。但し、侵入板温は浴中Alとの関係で下記
関係式の条件を満足する必要がある。In a bath containing 0.13% or more of Al, when the temperature of the invading plate is increased, the reaction temperature immediately after the intrusion of the steel plate becomes high, and Fe 2 Al 5 becomes thick. As a result, generation of Fe-Zn alloy in the bath is suppressed. However, the intrusion plate temperature must satisfy the conditions of the following relational expression in relation to Al in the bath.
571×〔Al％〕＋410≧Ｔ≧571×〔Al％〕＋390 但し、〔Al％〕：浴中Al量（％） T:侵入板温（℃） 上述したように本発明は高Al浴、高侵入板温を基本と
するものであるが、侵入板温が浴中Al量との関係で上記
上限を超えると、Feの拡散速度が増すため、Fe2Al5によ
る抑制効果が不十分となり、浴中で部分的にアウトバー
スト組織が生成するため、耐パウダリング性が劣化して
しまう。一方、侵入温度が上記下限を下回るとFe2Al5の
形成量が十分でなく、浴中でのFe−Zn合金反応の抑制作
用が適切に得られない。571 × [Al%] + 410 ≧ T ≧ 571 × [Al%] + 390 However, [Al%]: Al amount in bath (%) T: Penetration plate temperature (° C.) As described above, the present invention is a high Al bath, It is based on a high penetration plate temperature, but if the penetration plate temperature exceeds the above upper limit in relation to the amount of Al in the bath, the diffusion rate of Fe increases, so the suppression effect by Fe 2 Al 5 becomes insufficient. The outburst structure is partially generated in the bath, so that the powdering resistance is deteriorated. On the other hand, if the penetration temperature is below the above lower limit, the amount of Fe 2 Al 5 formed is insufficient, and the effect of suppressing the Fe—Zn alloy reaction in the bath cannot be obtained appropriately.
なお、侵入板温が520℃を超えると、Fe2Al5が局部的
に過剰に生成され易くなるため焼きムラが発生し、耐パ
ウダリング性が劣化してしまう。また、ポットへの入熱
量増加により浴温冷却手段等の付加的設備が必要にな
り、さらに、浴中でのドロス発生量が増加し、表面欠陥
が多発する等の問題を生じる。このため侵入板温は、浴
中Al量に関係なく520℃以下とすることが好ましい。If the intrusion plate temperature exceeds 520 ° C., Fe 2 Al 5 is likely to be locally excessively generated, so that uneven baking occurs and the powdering resistance deteriorates. In addition, an increase in the amount of heat input to the pot requires additional equipment such as a bath temperature cooling means, which further increases the amount of dross generated in the bath, resulting in frequent surface defects. Therefore, the penetration plate temperature is preferably 520 ° C. or lower regardless of the amount of Al in the bath.
めっき浴温度が高いと浴中における合金化反応が促進
されるため、本発明では浴温度を470℃以下とする。ま
た、浴温度が高過ぎると浴中に浸漬された構造物が侵食
され、ドロスが発生するなどの問題を生じる。When the plating bath temperature is high, the alloying reaction in the bath is promoted, so the bath temperature is 470 ° C. or lower in the present invention. Further, if the bath temperature is too high, the structure immersed in the bath is eroded, which causes a problem such as generation of dross.
めっきされた鋼板は、高周波誘導加熱炉において合金
化のための加熱処理される。本発明では、上記のような
浴条件の規定に加え、この高周波誘導加熱炉による加熱
処理が大きな特徴であり、上述したように通常行なわれ
ているガス加熱では、本発明の目的とする合金化めっき
皮膜は全く得られない。この合金化処理では、炉出側の
板温が495℃以下となるように加熱し、所定時間保持後
冷却する。上述したようにζ相を形成させるためには49
5℃以下での加熱が必要であり、本発明においては浴中
での合金化が抑制されためっきをここで合金化し、ζ相
を形成させる。本発明において高周波誘導加熱炉出側の
板温を管理する理由は、その部分が合金化熱サイクルで
の最高板温となるためである。また、合金相の成長速度
はこの付近で最大となるため、出側板温を管理すること
により、その温度での合金化反応を起すことが可能にな
る。The plated steel sheet is heat-treated for alloying in a high frequency induction heating furnace. In the present invention, in addition to the stipulation of bath conditions as described above, the heat treatment by this high-frequency induction heating furnace is a major feature. No plating film is obtained. In this alloying treatment, heating is performed so that the plate temperature on the exit side of the furnace is 495 ° C. or lower, and after holding for a predetermined time, it is cooled. As described above, in order to form the ζ phase, 49
Heating at 5 ° C. or lower is required, and in the present invention, plating in which alloying in the bath is suppressed is alloyed here to form a ζ phase. The reason for controlling the plate temperature on the outlet side of the high frequency induction heating furnace in the present invention is that that part becomes the maximum plate temperature in the alloying heat cycle. Further, since the growth rate of the alloy phase becomes maximum around this, it becomes possible to cause the alloying reaction at that temperature by controlling the outlet plate temperature.
本発明は皮膜中のFe含有量が８〜12％の合金化溶融亜
鉛めっき鋼板の製造を目的としている。皮膜中のFe含有
量が12％を超えると、皮膜が硬質になり、耐パウダリン
グ性が劣化する。高周波誘導加熱炉出側以降合金化を進
めると固体内拡散反応により皮膜中のFe含有量が上昇し
てしまう。一方、Fe含有量が８％未満では、η相（純亜
鉛相）が表面に残留するため、プレス成形時に焼付け
（フレーキング）と呼ばれる現象が起り好ましくない。The present invention aims to produce an alloyed hot-dip galvanized steel sheet having a Fe content of 8 to 12% in the coating. If the Fe content in the coating exceeds 12%, the coating becomes hard and the powdering resistance deteriorates. If alloying proceeds from the high-frequency induction heating furnace exit side, the Fe content in the coating will increase due to the diffusion reaction in the solid. On the other hand, when the Fe content is less than 8%, the η phase (pure zinc phase) remains on the surface, which is not preferable because a phenomenon called baking (flaking) occurs during press molding.
従来では、被覆中のFe含有量により皮膜構造が一義的
に決まると考えられていたが、本発明のように浴条件を
適当な選択し、しかも合金化処理を高周波誘導加熱で行
うことにより、皮膜中のFe含有量にかかわらず、本発明
が目的とするような特定の皮膜構造が得られる。Conventionally, it was thought that the film structure is uniquely determined by the Fe content in the coating, but by appropriately selecting the bath conditions as in the present invention, and by performing the alloying treatment by high frequency induction heating, Regardless of the Fe content in the coating, a specific coating structure as intended by the invention is obtained.
このようにして得られた合金化めっき皮膜は、表層側
から均一なζ相、δ１相、および極く薄いΓ相が存在す
る構造となる。The alloyed plating film thus obtained has a structure in which a uniform ζ phase, a δ 1 phase, and an extremely thin Γ phase are present from the surface layer side.
以上のような合金化処理後、摩擦係数を減少させプレ
ス成形性を改善するために、上層めっきとしてFe含有量
が50％以上のFe系めっきを1g/m2以上施す。摩擦係数を
低下させるには上層めっきをα単相とすることが好まし
く、Fe系めっきでは、第２図に示すようにFe含有量がほ
ぼ50％以上でα単相となる。After the alloying treatment as described above, in order to reduce the friction coefficient and improve the press formability, 1 g / m 2 or more of Fe-based plating having an Fe content of 50% or more is applied as the upper layer plating. In order to reduce the friction coefficient, it is preferable that the upper layer plating is α single phase, and in Fe-based plating, as shown in FIG. 2, when the Fe content is approximately 50% or more, it becomes α single phase.
また、上層めっきの付着量が1g/m2未満では摩擦係数
の低減が十分ではない。第３図は上層めっき量と摩擦係
数との関係を示すもので、めっき量を1g/m2以上とする
ことにより、0.13以下の摩擦係数が得られていることが
判る。また、このめっき付着量に特に上限はないが、コ
スト面から3g/m2以下とすることが好ましい。本発明の
ように溶融めっき後の加熱を高周波誘導加熱で行うと、
めっき表面が酸化されないため、合金化めっき層上に上
層めっきを適切に付着させることができ、このためガス
加熱で合金化処理した場合に較べ上層めっきの付着量を
少なくすることができる。Further, if the amount of the upper layer plating deposited is less than 1 g / m 2 , the friction coefficient is not sufficiently reduced. FIG. 3 shows the relationship between the upper layer plating amount and the friction coefficient. It can be seen that a friction coefficient of 0.13 or less is obtained by setting the plating amount to 1 g / m 2 or more. Further, although there is no particular upper limit to the coating amount, it is preferably 3 g / m 2 or less in terms of cost. When the heating after hot dip plating is performed by high frequency induction heating as in the present invention,
Since the plating surface is not oxidized, the upper layer plating can be properly adhered to the alloyed plating layer, and thus the amount of the upper layer plating adhered can be reduced as compared with the case where the alloying treatment is performed by gas heating.
なお、同図によれば、上層めっきを施した鋼板と上層
めっきを施さない鋼板（付着量:0g/m2）とを較べると、
後者ではζ相の形成量の多少によって摩擦係数に大きな
差があるのに対し、前者ではζ相の形成量が摩擦係数に
及ぼす影響は後者ほどではなく、上層めっきの形成によ
り、ζ相の形成量が多くても摩擦係数の低減化が効果的
になされていることが判る。According to the figure, comparing the steel plate with the upper layer plating with the steel plate without the upper layer plating (adhesion amount: 0 g / m 2 ),
In the latter, there is a large difference in the friction coefficient depending on the amount of ζ-phase formation, whereas in the former, the effect of the amount of ζ-phase formation on the friction coefficient is not as great as in the latter. It can be seen that the friction coefficient is effectively reduced even if the amount is large.
〔実施例〕 本発明の実施例を第１表に示す。[Examples] Table 1 shows examples of the present invention.
この実施例では、IF鋼および通常のAlキルド鋼から製
造された冷延鋼板を素材とし、第１表に示される条件で
溶融亜鉛めっき、加熱処理および上層めっきを行った。
この上層めっきは、ライン出側に設置された電気めっき
設備で実施した。また、上記加熱処理はガス加熱方式お
よび高周波誘導加熱方式を用いた。第１表中の各鋼種の
成分は以下の通りである。In this example, cold-rolled steel sheets manufactured from IF steel and ordinary Al-killed steel were used as raw materials, and hot dip galvanizing, heat treatment, and upper layer plating were performed under the conditions shown in Table 1.
This upper layer plating was carried out in an electroplating facility installed on the line outlet side. Moreover, the said heat processing used the gas heating system and the high frequency induction heating system. The components of each steel type in Table 1 are as follows.
鋼種Al:0.0025％Ｃ−0.04％Sol.Al−0.07％Ti ;Ti/C≧１ 鋼種A2:0.0027％Ｃ−0.05％Sol.Al−0.05％Ti−0.01％N
b ;12Ti/48C＋12Nb/93C≧１ 鋼種B:0.03％Ｃ−0.02％Sol.Al（Alキルド鋼） 本実施例において、鋼板のめっき浴中への侵入温度は
放射型温度計で測定した浸漬直前の鋼板の表面温度であ
る。また、加熱炉出側の板温は放射型温度計で測定した
鋼板の表面温度である。Steel type Al: 0.0025% C-0.04% Sol.Al-0.07% Ti; Ti / C ≧ 1 Steel type A2: 0.0027% C-0.05% Sol.Al-0.05% Ti-0.01% N
b; 12Ti / 48C + 12Nb / 93C ≧ 1 Steel type B: 0.03% C-0.02% Sol.Al (Al killed steel) In this example, the penetration temperature of the steel sheet into the plating bath was immediately before immersion measured by a radial thermometer. Is the surface temperature of the steel sheet. The plate temperature on the outlet side of the heating furnace is the surface temperature of the steel plate measured by a radiation thermometer.
また、めっき浴中Al量は下式に定義される有効Al濃度
である。The amount of Al in the plating bath is the effective Al concentration defined by the following formula.
〔有効Al濃度〕＝〔浴中全Al濃度〕−〔浴中鉄濃度〕 ＋0.03 皮膜中Fe％は浴条件、加熱条件および冷却条件に依存
する。冷却条件は本発明の特徴の一つである皮膜構造の
マクロ或いはミクロな均一性にほとんど影響を及ぼさな
いが、合金化度（皮膜中Fe％）を変化させることにより
特性に影響を及ぼす。したがって、本実施例では冷却用
のブロアの風量、ミストの量を調整し、皮膜中のFe％を
制御した。[Effective Al concentration] = [Total Al concentration in bath]-[Iron concentration in bath] +0.03 Fe% in the coating depends on bath conditions, heating conditions and cooling conditions. The cooling conditions have almost no effect on the macro- or micro-uniformity of the film structure, which is one of the features of the present invention, but affect the properties by changing the alloying degree (Fe% in the film). Therefore, in this example, the air amount of the cooling blower and the amount of mist were adjusted to control the Fe% in the film.
また、各特性に関する試験、評価方法は以下の通りで
ある。The tests and evaluation methods for each property are as follows.
○製品皮膜中ζ相の量： 得られた皮膜をＸ線回折し、ζ相についてはｄ＝1.90
0のピーク強度Ｉζ（421）を、またδ１相についてはｄ
＝1.990のピーク強度Ｉζδ（249）をそれぞれ取り、下
式で示すピーク強度比をもって皮膜中のζ相の量を表し
た。なお、IBGはバックグランドであり、Z/Dが20以下な
らば実質的にζ相は存在しない。○ Amount of ζ phase in the product film: The obtained film was subjected to X-ray diffraction, and d = 1.90 for the ζ phase.
A peak intensity I ζ (421) of 0 and d for the δ 1 phase
The peak intensity I ζδ (249) of = 1.990 was taken, and the amount of ζ phase in the film was expressed by the peak intensity ratio shown by the following formula. Note that I BG is the background, and if Z / D is 20 or less, the ζ phase does not substantially exist.
Z/D＝（Ｉζ（421）−IBG）／（Ｉδ１（249）−IBG）
×100 ○耐パウダリング性： 試験片に防錆油（パーカー興産（株）製ノックスラス
ト530F）を1g/m2塗布した後、ビード半径R:0.5mm、押し
付け荷重P:500kg、押し込み深さh:4mmでビード引き抜き
試験を行い、テープ剥離後、成形前後の重量変化から剥
離量を算出した。なお、表中の数値は複数の測定値（５
×５＝25個）の平均値である。Z / D = (I ζ (421) −I BG ) / (I δ1 (249) −I BG ).
× 100 ○ Powdering resistance: After applying 1g / m 2 of rust preventive oil (Noxlast 530F manufactured by Parker Kosan Co., Ltd.) to the test piece, bead radius R: 0.5mm, pressing load P: 500kg, indentation depth A bead pull-out test was performed at h: 4 mm, and after peeling the tape, the peeling amount was calculated from the weight change before and after molding. The values in the table are for multiple measured values (5
× 5 = 25 pieces).
○耐パウダリング性の板幅方向最大偏差： 操業条件が安定した箇所で、鋼板長さ方向５点、鋼板
幅方向５点（両エッジ、1/4の位置およびセンター部）
で上記耐パウダリング性をそれぞれ測定し、最大値と最
小値の差をとった。○ Maximum deviation of powdering resistance in the plate width direction: 5 points in the steel plate length direction, 5 points in the steel plate width direction (both edges, 1/4 position and center part) where the operating conditions are stable.
The above powdering resistance was measured and the difference between the maximum value and the minimum value was taken.
○摩擦係数： 試験片に防錆油（パーカー興産（株）製ノックスラス
ト530F）を1g/m2塗布した後、工具鋼SKD11製の圧子を荷
重400kgで押し付け、1m/minの引き抜き速度で引き抜き
を行い、引き抜き荷重と押し付け荷重との比を摩擦係数
とした。なお、表中の数値は複数の測定値（５×５＝25
個）の平均値である。○ Friction coefficient: After applying 1g / m 2 of rust preventive oil (Knox Thrust 530F manufactured by Parker Kosan Co., Ltd.) to the test piece, press an indenter made of tool steel SKD11 with a load of 400kg and pull out at a pulling speed of 1m / min. Then, the ratio between the pulling load and the pressing load was taken as the friction coefficient. The values in the table are for multiple measured values (5 x 5 = 25
The average value of
○摩擦係数の板幅方向最大偏差： 耐パウダリング性と同一箇所で摩擦係数をそれぞれ測
定し、最大値と最小値の差をとった。○ Maximum deviation of friction coefficient in the plate width direction: The friction coefficient was measured at the same location as the powdering resistance, and the difference between the maximum value and the minimum value was taken.
第１表において、比較例１は侵入板温高過ぎるため、
また、比較例２は浴中Al量が低過ぎるため、それぞれ浴
中でアウトバースト組織が発生し、このため耐パウダリ
ング性が劣っており、またそのバラツキも大きい。In Table 1, since Comparative Example 1 is too hot for the intrusion plate,
Further, in Comparative Example 2, since the amount of Al in the bath was too low, an outburst structure was generated in each of the baths, so that the powdering resistance was poor and the variation was large.
比較例３および比較例４は侵入板温が低いためにFe2A
l5の形成量が十分でなく、浴中でのFe−Zn合金反応の抑
制作用が適切に得られていない。このため耐パウダリン
グ性が悪い。In Comparative Example 3 and Comparative Example 4, Fe 2 A
The amount of l 5 formed is not sufficient, and the effect of suppressing the Fe-Zn alloy reaction in the bath is not properly obtained. Therefore, the powdering resistance is poor.
比較例５および比較例６は上層めっきの付着量に関す
る比較例である。Comparative examples 5 and 6 are comparative examples relating to the amount of the upper layer plating deposited.
比較例７は浴中でのFe−Zn合金反応の抑制作用は得ら
れているものの、高周波誘導加熱での加熱温度が高過ぎ
るため製品皮膜中にはζ相は存在していない。このため
耐パウダリング性が劣っている。In Comparative Example 7, the effect of suppressing the Fe-Zn alloy reaction in the bath was obtained, but since the heating temperature in the high frequency induction heating was too high, no ζ phase was present in the product film. Therefore, the powdering resistance is inferior.
比較例８〜比較例10は加熱をガス加熱で行なった例で
ある。このうち比較例８は加熱温度で高過ぎるため製品
皮膜中にはζ相は存在しておらず、また、焼きムラのた
め局部的に厚いΓ相が形成されているため、耐パウダリ
ング性が極めて悪く、また、そのバラツキも大きい。比
較例９および比較例10は、加熱温度が低いため製品皮膜
中にはζ相は存在しているものの、焼きムラにより局部
的にΓ相が厚く形成されるため耐パウダリング性、プレ
ス成形性とも板幅方向で大きなバラツキを生じており、
したがって、これら特性値自体も悪い。また、合金化相
のミクロ的な均一性にも劣っており、この面からも耐パ
ウダリング性に劣っている。Comparative Examples 8 to 10 are examples in which heating is performed by gas heating. Among them, in Comparative Example 8, since the heating temperature is too high, the ζ phase does not exist in the product film, and the thick Γ phase is locally formed due to uneven baking, so that the powdering resistance is low. It is extremely bad and its variation is large. In Comparative Example 9 and Comparative Example 10, since the heating temperature is low, the ζ phase is present in the product film, but since the Γ phase is locally formed thick due to uneven baking, the powdering resistance and the press formability are high. Both have large variations in the width direction,
Therefore, these characteristic values themselves are also bad. In addition, the microscopic uniformity of the alloying phase is also inferior and the powdering resistance is also inferior in this respect.
比較例11〜13は、通常のAlキルド鋼の場合であり、こ
のうち比較例11、12は加熱を高周波誘導加熱で行なって
いるが、素材がAlキルド鋼であるために浴中で合金化が
過度に抑制され、このため加熱が急速加熱となってアウ
トバーアウト組織が発生し、耐パウダリング性が悪い。
また、比較例13は加熱をガス加熱で行なっているため、
耐パウダリング性、プレス成形性とも板幅方向で大きな
バラツキを生じており、したがって、これら特性値自体
も悪い。Comparative Examples 11 to 13 are cases of normal Al-killed steel, of which Comparative Examples 11 and 12 are heated by high frequency induction heating, but alloyed in a bath because the material is Al-killed steel. Is excessively suppressed, which causes rapid heating to generate an outburr out structure, resulting in poor powdering resistance.
Further, in Comparative Example 13, since heating is performed by gas heating,
Both the powdering resistance and the press formability show large variations in the plate width direction, and therefore these characteristic values themselves are also poor.
従来例１〜従来例４では、浴中でのFe−Zn合金反応の
抑制作用は得られておらず、このため従来例３のように
加熱を高周波誘導加熱で行なっても耐パウダリング性が
劣り、またそのバラツキも大きい。In Conventional Example 1 to Conventional Example 4, the effect of suppressing the Fe-Zn alloy reaction in the bath is not obtained, and therefore, even if heating is performed by high frequency induction heating as in Conventional Example 3, the powdering resistance is low. It is inferior and its variation is large.
第１図（ａ）、（ｂ）は、溶融亜鉛めっき鋼板の450
℃、500℃での恒温合金化反応による相変化の一例を示
すものである。第２図は電着Fe−Zn合金の相構成を示す
ものである。第３図は上層めっき量と摩擦係数との関係
を示すものである。1 (a) and 1 (b) show 450 of hot dip galvanized steel sheet.
It shows an example of a phase change due to an isothermal alloying reaction at ℃ and 500 ℃. FIG. 2 shows the phase constitution of the electrodeposited Fe-Zn alloy. FIG. 3 shows the relationship between the upper layer plating amount and the friction coefficient.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 平谷 晃 東京都千代田区丸の内１丁目１番２号 日 本鋼管株式会社内 (72)発明者 森田 正哉 東京都千代田区丸の内１丁目１番２号 日 本鋼管株式会社内 (56)参考文献 特開 平２−66148（ＪＰ，Ａ) 特開 平２−11745（ＪＰ，Ａ) 特開 平２−254146（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Hiratani Akira Marunouchi 1-2-2, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Masaya Morita 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Date (56) Reference JP-A-2-66148 (JP, A) JP-A-2-11745 (JP, A) JP-A-2-254146 (JP, A)
Claims (1)
み、これら元素の添加量Ｘと炭素含有量〔Ｃ〕の原子％
比がΣX/〔Ｃ〕≧１を満足する鋼からなる鋼板をめっき
原板とし、該鋼板に、Alを含有し、残部Znおよび不可避
的不純物からなる亜鉛めっき浴でめっきを施した後、目
付量調整を行い、加熱炉で皮膜中のFe含有量が８〜12％
となるように合金化処理を行う合金化溶融亜鉛めっき鋼
板の製造方法において、浴中Al量:0.13％以上、浴温度:
470℃以下で、且つ、浴中Al量と鋼板のめっき浴中への
侵入板温とが、 571×〔Al％〕＋410≧Ｔ≧571×〔Al％〕＋390 但し、〔Al％〕：浴中Al量（％） T:侵入板温（℃） を満足する条件でめっきを行うことにより、浴中で合金
化反応を抑制し、めっき後、高周波誘導加熱炉で加熱炉
出側の板温が495℃以下となるように加熱し、所定時間
保持後冷却し、次いで、上層めっきとしてFe含有量が50
％以上のFe系めっきを1g/m2以上施すことを特徴とする
プレス成形性および耐パウダリング性の優れた合金化溶
融亜鉛めっき鋼板の製造方法。1. A carbide-forming element such as Ti, Nb, Sr, V, etc., which is added at an amount X of these elements and a carbon content [C] of atomic%.
A steel plate made of steel having a ratio of ΣX / [C] ≧ 1 is used as a plating base plate, and the steel plate is plated with a zinc plating bath containing Al and the balance Zn and inevitable impurities, and then the basis weight is calculated. Adjusted and the Fe content in the coating is 8-12% in the heating furnace
In the method for producing an alloyed hot-dip galvanized steel sheet, which is subjected to an alloying treatment so that the Al content in the bath is 0.13% or more, and the bath temperature is:
470 ° C or less, and the amount of Al in the bath and the plate temperature of the steel plate invading the plating bath are 571 x [Al%] + 410 ≥ T ≥ 571 x [Al%] + 390, however, [Al%]: bath Medium Al content (%) T: The alloying reaction is suppressed in the bath by plating under conditions that satisfy the penetration plate temperature (° C), and after plating, the plate temperature at the heating furnace exit side in the high frequency induction heating furnace Is heated to 495 ° C or less, held for a predetermined time and then cooled, and then the Fe content is 50% as the upper layer plating.
% Of Fe-based plating is applied at 1 g / m 2 or more, and a method for producing an alloyed hot-dip galvanized steel sheet having excellent press formability and powdering resistance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2327283A JPH0816261B2 (en) | 1990-11-28 | 1990-11-28 | Method for producing galvannealed steel sheet having excellent press formability and powdering resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2327283A JPH0816261B2 (en) | 1990-11-28 | 1990-11-28 | Method for producing galvannealed steel sheet having excellent press formability and powdering resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04193938A JPH04193938A (en) | 1992-07-14 |
| JPH0816261B2 true JPH0816261B2 (en) | 1996-02-21 |
Family
ID=18197397
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2327283A Expired - Fee Related JPH0816261B2 (en) | 1990-11-28 | 1990-11-28 | Method for producing galvannealed steel sheet having excellent press formability and powdering resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0816261B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2658608B2 (en) * | 1991-02-28 | 1997-09-30 | 日本鋼管株式会社 | Method for producing alloyed hot-dip galvanized steel sheet excellent in press formability and powdering resistance |
| JP5201477B2 (en) * | 2009-01-05 | 2013-06-05 | 新日鐵住金株式会社 | Method for producing galvannealed steel sheet |
| JP5187205B2 (en) | 2009-01-20 | 2013-04-24 | 井関農機株式会社 | Lawn mower |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2610948B2 (en) * | 1988-06-29 | 1997-05-14 | 川崎製鉄 株式会社 | Manufacturing method of galvannealed steel sheet with excellent spot weldability |
| JPH0266148A (en) * | 1988-08-30 | 1990-03-06 | Sumitomo Metal Ind Ltd | Multilayer plated steel sheet with excellent flaking resistance |
| JPH02254146A (en) * | 1989-03-27 | 1990-10-12 | Nkk Corp | Induction heating device, induction heating-type alloying furnace, and alloying method |
-
1990
- 1990-11-28 JP JP2327283A patent/JPH0816261B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04193938A (en) | 1992-07-14 |
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