JPH0765191B2 - Method for producing iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers, which has excellent electrodeposition coatability and workability - Google Patents
Method for producing iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers, which has excellent electrodeposition coatability and workabilityInfo
- Publication number
- JPH0765191B2 JPH0765191B2 JP2338837A JP33883790A JPH0765191B2 JP H0765191 B2 JPH0765191 B2 JP H0765191B2 JP 2338837 A JP2338837 A JP 2338837A JP 33883790 A JP33883790 A JP 33883790A JP H0765191 B2 JPH0765191 B2 JP H0765191B2
- Authority
- JP
- Japan
- Prior art keywords
- layer
- iron
- steel sheet
- based alloy
- electroplating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims description 120
- 238000007747 plating Methods 0.000 title claims description 95
- 229910000831 Steel Inorganic materials 0.000 title claims description 69
- 239000010959 steel Substances 0.000 title claims description 69
- 229910052742 iron Inorganic materials 0.000 title claims description 60
- 229910045601 alloy Inorganic materials 0.000 title claims description 45
- 239000000956 alloy Substances 0.000 title claims description 45
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 238000004070 electrodeposition Methods 0.000 title description 17
- 239000010410 layer Substances 0.000 claims description 186
- 238000009713 electroplating Methods 0.000 claims description 88
- KFZAUHNPPZCSCR-UHFFFAOYSA-N iron zinc Chemical compound [Fe].[Zn] KFZAUHNPPZCSCR-UHFFFAOYSA-N 0.000 claims description 65
- 229910001297 Zn alloy Inorganic materials 0.000 claims description 62
- 238000005868 electrolysis reaction Methods 0.000 claims description 25
- 239000002344 surface layer Substances 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 14
- 230000005611 electricity Effects 0.000 claims description 7
- 238000005246 galvanizing Methods 0.000 claims description 5
- 229910000978 Pb alloy Inorganic materials 0.000 claims 1
- 238000000576 coating method Methods 0.000 description 33
- 239000011248 coating agent Substances 0.000 description 31
- 230000007547 defect Effects 0.000 description 21
- 238000012360 testing method Methods 0.000 description 11
- 229910052725 zinc Inorganic materials 0.000 description 7
- 239000011701 zinc Substances 0.000 description 7
- 229910019142 PO4 Inorganic materials 0.000 description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 6
- 239000010452 phosphate Substances 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 5
- 238000000227 grinding Methods 0.000 description 5
- DPTATFGPDCLUTF-UHFFFAOYSA-N phosphanylidyneiron Chemical compound [Fe]#P DPTATFGPDCLUTF-UHFFFAOYSA-N 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 229910001096 P alloy Inorganic materials 0.000 description 4
- 238000005275 alloying Methods 0.000 description 4
- 239000011324 bead Substances 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 150000001768 cations Chemical class 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- QELJHCBNGDEXLD-UHFFFAOYSA-N nickel zinc Chemical compound [Ni].[Zn] QELJHCBNGDEXLD-UHFFFAOYSA-N 0.000 description 3
- 229910000521 B alloy Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 239000002390 adhesive tape Substances 0.000 description 2
- ZDVYABSQRRRIOJ-UHFFFAOYSA-N boron;iron Chemical compound [Fe]#B ZDVYABSQRRRIOJ-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000007598 dipping method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000007743 anodising Methods 0.000 description 1
- 229910002056 binary alloy Inorganic materials 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000010409 ironing Methods 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910002058 ternary alloy Inorganic materials 0.000 description 1
Landscapes
- Coating With Molten Metal (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
- Electroplating Methods And Accessories (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、電着塗装性および加工性に優れた、複数の
鉄系合金めっき層を有する鉄系合金めっき鋼板の製造方
法に関するものである。TECHNICAL FIELD The present invention relates to a method for producing an iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers, which is excellent in electrodeposition coatability and workability. .
鉄−亜鉛、鉄−ボロン、鉄−燐等の鉄系合金めっき鋼板
は、耐食性および電着塗装性に優れており、自動車用鋼
板等として広く使用されている。近年、このような鉄系
合金めっき鋼板の耐食性に対する要求が、一段と高くな
っており、このような要求を満足させるめっき鋼板とし
て、下層としての厚い合金化溶融鉄−亜鉛合金めっき層
と、上層としての鉄系合金電気めっき層とからなる複数
の鉄系合金めっき層を有する鉄系合金めっき鋼板が知ら
れている。Iron-based alloy-plated steel sheets such as iron-zinc, iron-boron, and iron-phosphorus have excellent corrosion resistance and electrodeposition coating properties, and are widely used as steel sheets for automobiles and the like. In recent years, the demand for corrosion resistance of such iron-based alloy-plated steel sheets has become much higher, and as a plated steel sheet that satisfies such requirements, a thick alloyed molten iron-zinc alloy plating layer as the lower layer and an upper layer. An iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers composed of the iron-based alloy electroplating layer of is known.
鉄系合金めっき鋼板の表面上に対する塗膜の形成は、一
般に、鉄系合金めっき層の表面上に、化成処理によって
燐酸塩被膜を形成し、次いで、カチオンタイプの電着塗
装法により、燐酸塩被膜の上に所定の厚さの塗膜を形成
することにより行われる。Generally, a coating film is formed on the surface of an iron-based alloy plated steel sheet by forming a phosphate film on the surface of the iron-based alloy plating layer by chemical conversion treatment, and then by a cation-type electrodeposition coating method. It is performed by forming a coating film having a predetermined thickness on the coating film.
しかしながら、カチオンタイプの電着塗装法により、鉄
系合金めっき層の表面上に塗膜を形成すると、電着塗装
時に発生しそして塗膜内に閉じ込められた水素ガスによ
って、クレーター状のピンホールが発生する。このよう
な塗膜に発生したクレーター状ピンホールは、塗装面の
外観上の欠陥になる。However, when a coating film is formed on the surface of the iron-based alloy plating layer by the cation type electrodeposition coating method, crater-like pinholes are generated by the hydrogen gas generated during electrodeposition coating and trapped in the coating film. Occur. The crater-like pinholes generated in such a coating film become defects in the appearance of the coated surface.
一方、自動車用鋼板等に使用される鉄系合金めっき鋼板
には、プレスなどによって厳しい成形加工が施される。
このような厳しい成形加工が施されると、鉄系合金めっ
き層の粉状の剥離即ちパウダリング、および、鉄系合金
めっき層の鋼板からの剥離即ちフレーキングが発生す
る。On the other hand, iron-based alloy-plated steel sheets used for automobile steel sheets and the like are subjected to severe forming processing such as pressing.
When such a severe forming process is performed, powdery peeling or powdering of the iron-based alloy plating layer and peeling or flaking of the iron-based alloy plating layer from the steel sheet occur.
上述した問題を解決する、鉄系合金めっき鋼板として、
下記先行技術が知られている。As an iron-based alloy plated steel sheet that solves the above-mentioned problems,
The following prior art is known.
特公昭58−15554号 鋼板の少なくとも１つの表面上に、40wt.％超の亜鉛を
含有する、めっき層の厚い下層としての鉄−亜鉛合金め
っき層と、前記下層としての鉄−亜鉛合金めっき層の上
に形成された、40wt.％以下の亜鉛を含有する、上層と
しての鉄−亜鉛合金電気めっき層とを有する、カチオン
電着塗装用のめっき鋼板（以下、先行技術１という）。Japanese Examined Patent Publication No. S58-15554 Iron-zinc alloy plating layer as a thick lower layer of the plating layer containing zinc of more than 40 wt.% On at least one surface of the steel plate, and iron-zinc alloy plating layer as the lower layer. A plated steel sheet for cationic electrodeposition coating having an iron-zinc alloy electroplating layer as an upper layer, containing 40 wt.% Or less of zinc formed on the above (hereinafter referred to as Prior Art 1).
特開平２−66148号 鋼板の少なくとも１つの表面上に、12wt.％以下の鉄を
含有する下層としての鉄−亜鉛合金めっき層と、前記下
層としての鉄−亜鉛合金めっき層の上に形成された、50
wt.％以上の鉄を含有し、表面摩擦係数が0.22以下であ
る、上層としての鉄系合金めっき層とを有する、耐フレ
ーキング性に優れた多層めっき鋼板（以下、先行技術２
という）。[Patent Document 1] JP-A-2-66148 Formed on at least one surface of a steel plate, an iron-zinc alloy plating layer as a lower layer containing 12 wt.% Or less of iron, and an iron-zinc alloy plating layer as the lower layer. 50
A multi-layer plated steel sheet that contains wt.% or more of iron, has a surface friction coefficient of 0.22 or less, and has an iron-based alloy plating layer as an upper layer, and that has excellent flaking resistance (hereinafter referred to as Prior Art 2).
That).
特開平２−85393号 鋼板の少なくとも１つの表面上に、10〜20wt.％の鉄を
含有する鉄−亜鉛系合金電気めっき層、または、８〜14
wt.％のニッケルを含有するニッケル−亜鉛系合金電気
めっき層からなる、下層としての鉄−亜鉛系またはニッ
ケル−亜鉛系合金電気めっき層と、前記下層としての鉄
−亜鉛系またはニッケル−亜鉛系合金電気めっき層の上
に形成された、0.003〜0.5wt.％の燐を含有する上層と
しての鉄−燐合金電気めっき層とを有する、耐パウダリ
ング性および耐クレーター性に優れた亜鉛系合金電気め
っき鋼板（以下、先行技術３という）。[Patent Document 1] JP-A-2-85393 An iron-zinc alloy electroplating layer containing 10 to 20 wt.% Iron on at least one surface of a steel plate, or 8 to 14
An iron-zinc system or nickel-zinc system alloy electroplating layer as a lower layer comprising a nickel-zinc system alloy electroplating layer containing wt.% nickel, and an iron-zinc system or nickel-zinc system as the lower layer A zinc-based alloy excellent in powdering resistance and crater resistance, having an iron-phosphorus alloy electroplating layer as an upper layer containing 0.003 to 0.5 wt.% Phosphorus formed on the alloy electroplating layer Electroplated steel sheet (hereinafter referred to as Prior Art 3).
上述した先行技術１には、次に述べるような問題があ
る。即ち、下層を厚い合金化溶融鉄−亜鉛合金めっき層
によって形成し、そして、上層を鉄−亜鉛合金電気めっ
き層によって形成した場合、このようなめっき鋼板に対
し、プレスなどによって厳しい成形加工が施されると、
下層としての、厚い合金化溶融鉄−亜鉛合金めっき層
に、亀裂や剥離が発生する。めっき層に亀裂や剥離が発
生すると、露出した鋼板によって、燐酸塩被膜の成形の
ための化成処理時に、めっき層の溶解が促進される結
果、燐酸塩結晶が異常に成長する。このように異常に成
長した燐酸塩結晶は、結晶水を多量に含有しており、こ
の結晶水が、電着塗装の塗膜焼き付け時に、燐酸塩結晶
から離脱しそして蒸発する。この結果、塗膜に気泡状欠
陥が発生する。このような塗膜に発生した気泡状欠陥
は、塗装面の外観上の欠陥になる。The above-mentioned prior art 1 has the following problems. That is, when the lower layer is formed by a thick alloyed molten iron-zinc alloy plating layer and the upper layer is formed by an iron-zinc alloy electroplating layer, such plated steel sheet is subjected to severe forming processing such as pressing. When done,
Cracks and peeling occur in the thick alloyed hot-dip iron-zinc alloy plating layer as the lower layer. When cracks or peeling occur in the plating layer, the exposed steel sheet promotes dissolution of the plating layer during chemical conversion treatment for forming the phosphate coating, resulting in abnormal growth of phosphate crystals. Such abnormally grown phosphate crystals contain a large amount of water of crystallization, and the water of crystallization separates from the phosphate crystals and evaporates during baking of the coating film for electrodeposition coating. As a result, bubble defects occur in the coating film. The bubble-like defects generated in such a coating film become defects in the appearance of the coated surface.
上述した先行技術２および３には、次に述べるような問
題がある。即ち、先行技術２によれば、めっき層の粉状
の剥離即ちパウダリング、および、めっき層の鋼板から
の剥離即ちフレーキングは防止され、また、先行技術３
によれば、パウダリングおよびクレーターの発生は防止
されても、上述した、塗膜に生ずる気泡状欠陥を防止す
ることはできない。むしろ、耐パウダリング性および耐
フレーキング性の防止のために形成された、上層として
の鉄系合金電気めっき層によって、気泡状欠陥の発生が
促進されると考えられる。The above-mentioned prior arts 2 and 3 have the following problems. That is, according to the prior art 2, powdery peeling of the plating layer, that is, powdering, and peeling of the plating layer from the steel plate, that is, flaking are prevented.
According to the above, even if the generation of powdering and craters is prevented, it is not possible to prevent the above-mentioned bubble-like defects occurring in the coating film. Rather, it is considered that the occurrence of bubble defects is promoted by the iron-based alloy electroplating layer as the upper layer, which is formed to prevent the powdering resistance and the flaking resistance.
従って、この発明の目的は、プレス等によって厳しい成
形加工が施されても、塗膜に、下層としての合金化溶融
鉄−亜鉛合金めっき層に発生した亀裂や剥離に基づく気
泡状欠陥が生ぜず、且つ、クレーター状ピンホールも殆
ど生じない、電着塗装および加工性に優れた、複数の鉄
系合金めっき層を有する鉄系合金めっき鋼板を製造する
ための方法を提供することにある。Therefore, an object of the present invention is that even when subjected to severe forming processing such as pressing, the coating film does not cause bubble-like defects due to cracks and peeling generated in the alloyed molten iron-zinc alloy plating layer as the lower layer. Another object of the present invention is to provide a method for producing an iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers, which is excellent in electrodeposition coating and workability, in which crater-shaped pinholes are hardly generated.
本発明者等は、上述した問題を解決すべく、下層として
の合金化溶融鉄−亜鉛合金めっき層と、上層としての鉄
系合金電気めっき層とからなる、複数の鉄系合金めっき
層を有する鉄系合金めっき鋼板の成形加工時に、下層と
しての合金化溶融鉄−亜鉛合金めっき層に亀裂や剥離が
発生する原因について、調査および研究を行った結果、
次のことが分かった。In order to solve the above-mentioned problems, the present inventors have a plurality of iron-based alloy plating layers including an alloyed molten iron-zinc alloy plating layer as a lower layer and an iron-based alloy electroplating layer as an upper layer. At the time of forming the iron-based alloy-plated steel sheet, the cause of cracking and peeling in the alloyed molten iron-zinc alloy plating layer as the lower layer, the result of an investigation and study,
I found the following:
下層としての合金化溶融鉄−亜鉛合金めっき層は、熱的
に形成されているので、めっき層中に内部応力は存在し
ない。これに対し、上層としての鉄系合金電気めっき層
は、金属の析出により形成されているので、めっき層中
に大きな内部応力が存在している。Since the alloyed hot-dip iron-zinc alloy plated layer as the lower layer is formed thermally, there is no internal stress in the plated layer. On the other hand, since the iron-based alloy electroplating layer as the upper layer is formed by metal deposition, a large internal stress exists in the plating layer.
この結果、上層としての、内部応力が大きい鉄系合金電
気めっき層は、下層としての合金化溶融鉄−亜鉛合金め
っき層を強く拘束し、このような拘束は、局部的に集中
する。このために、合金化溶融鉄−亜鉛合金めっき層
は、極めて脆くなり、成形加工時に亀裂が生じて、鋼板
から剥離するように破壊され、このときに気泡状欠陥が
発生する。As a result, the iron-based alloy electroplating layer having a large internal stress as the upper layer strongly restrains the alloyed molten iron-zinc alloy plating layer as the lower layer, and such restraints are locally concentrated. For this reason, the alloyed hot-dip iron-zinc alloy plating layer becomes extremely brittle, cracks occur during the forming process, and is broken so as to separate from the steel sheet, at which time bubble-like defects occur.
このような、気泡状欠陥の発生と、めっき層の破壊の程
度との関連について詳細に調べた結果、気泡状欠陥が発
生していない場合の、下層としての合金化溶融鉄−亜鉛
合金めっき層には、激しい脱落や剥離はなく、微細なク
ラックが全面にわたって均一に発生していることが分か
った。As a result of detailed examination of the relationship between the occurrence of such bubble defects and the degree of destruction of the plating layer, the alloyed molten iron-zinc alloy plating layer as the lower layer when no bubble defects have occurred It was found that there was no severe detachment or peeling, and fine cracks were uniformly generated over the entire surface.
上述したことから、下層としての合金化溶融鉄−亜鉛合
金めっき層が形成された鋼板を陽極電解処理し、めっき
層中における卑な亜鉛リッチの相を優先的に溶解させ、
下層としての合金化溶融鉄−亜鉛合金めっき層の表層に
多数の微細な凹凸を形成し、成形加工時に、下層に意図
的に微細なクラックを均一に発生させれば、成形加工時
における、下層としての合金化溶融鉄−亜鉛合金めっき
層の亀裂や剥離が防止され、塗膜に気泡状欠陥が発生し
なくなる。From the above, the alloyed molten iron as a lower layer-anodic electrolytic treatment of the steel sheet on which the zinc alloy plating layer is formed, preferentially dissolve the base zinc-rich phase in the plating layer,
If a large number of fine irregularities are formed on the surface layer of the alloyed hot-dip iron-zinc alloy plating layer as the lower layer, and during the forming process, intentionally generating fine cracks evenly in the lower layer, the lower layer during the forming process is formed. As a result, cracking and peeling of the alloyed hot-dip iron-zinc alloy plating layer are prevented, and bubble defects do not occur in the coating film.
この発明は、上記知見に基づいてなされたものであっ
て、鋼板を、溶融亜鉛めっき浴が収容された溶融亜鉛め
っき槽に通し、前記鋼板の表面上に亜鉛めっき層を形成
し、次いで、前記鋼板を加熱して前記亜鉛めっき層と前
記鋼板とを合金化させ、かくして、前記鋼板の少なくと
も１つの表面上に、所定めっき量の下層としての合金化
溶融鉄−亜鉛合金めっき層を形成し、次いで、前記下層
としての合金化溶融鉄−亜鉛合金めっき層が形成された
鋼板を、鉄系合金電気めっき浴が収容された複数の電気
めっき槽に順次通し、前記鋼板に陰極電解処理を施すこ
とにより、前記下層としての合金化溶融鉄−亜鉛合金め
っき層の上に、上層としての鉄系合金電気めっき層を形
成する、複数の鉄系合金めっき層を有する鉄系合金めっ
き鋼板の製造方法において、 前記複数の電気めっき槽の初槽において、前記下層とし
ての合金化溶融鉄−亜鉛合金めっき層が形成された鋼板
に対し陽極電解処理を施し、前記下層としての合金化溶
融鉄−亜鉛合金めっき層の一部を溶解させて、その表層
に多数の微細な凹凸を形成し、次いで、以降の電気めっ
き槽において陰極電解処理を施し、表層に微細な凹凸が
形成された下層としての合金化溶融鉄−亜鉛合金めっき
槽の上に、前記上層としての鉄系合金電気めっき層を形
成することに特徴を有するものである。This invention was made on the basis of the above findings, the steel sheet is passed through a hot dip galvanizing bath containing a hot dip galvanizing bath to form a galvanized layer on the surface of the steel sheet, and then the A steel sheet is heated to alloy the galvanized layer and the steel sheet, thus forming an alloyed molten iron-zinc alloy plated layer as a lower layer of a predetermined plating amount on at least one surface of the steel sheet, Then, the steel sheet on which the alloyed molten iron-zinc alloy plating layer as the lower layer is formed is sequentially passed through a plurality of electroplating baths containing an iron-based alloy electroplating bath, and the steel sheet is subjected to cathodic electrolysis treatment. Thereby, on the alloyed molten iron-zinc alloy plating layer as the lower layer, to form the iron-based alloy electroplating layer as the upper layer, in the method for producing an iron-based alloy plated steel sheet having a plurality of iron-based alloy plating layers In the first bath of the plurality of electroplating baths, an anodic electrolytic treatment is applied to the steel sheet on which the alloyed molten iron-zinc alloy plating layer as the lower layer is formed, and the alloyed molten iron-zinc alloy as the lower layer. A part of the plating layer is melted to form a number of fine irregularities on the surface layer, and then cathodic electrolysis is performed in the subsequent electroplating bath to form an alloy as a lower layer with fine irregularities formed on the surface layer. It is characterized by forming an iron-based alloy electroplating layer as the upper layer on the molten iron-zinc alloy plating tank.
〔作用〕 この発明においては、上述したように、下層としての合
金化溶融鉄−亜鉛合金めっき層が形成された鋼板に対
し、複数の電気めっき槽の初槽において陽極電解処理を
施す。この結果、下層としての合金化溶融鉄−亜鉛合金
めっき層中における、卑な亜鉛リッチの相が優先的に溶
解して、下層の表層に多数の微細な凹凸が形成される。
このようにして、表層に多数の微細な凹凸を有する下層
としての合金化溶融鉄−亜鉛合金めっき層が形成された
鋼板を、以降の電気めっき槽において陰極電解処理し、
上記下層の上に、上層としての鉄系合金電気めっき層を
形成する。[Operation] In the present invention, as described above, the steel sheet on which the alloyed molten iron-zinc alloy plating layer as the lower layer is formed is subjected to the anodic electrolytic treatment in the first bath of the plurality of electroplating baths. As a result, the base zinc-rich phase in the alloyed hot-dip iron-zinc alloy plating layer as the lower layer is preferentially dissolved, and a large number of fine irregularities are formed on the lower surface layer.
In this manner, the steel sheet on which the alloyed molten iron-zinc alloy plating layer as the lower layer having many fine irregularities on the surface layer is formed, is subjected to cathodic electrolysis in the subsequent electroplating bath,
An iron-based alloy electroplating layer as an upper layer is formed on the lower layer.
このようにして形成された複数の鉄系合金めっき層を有
する鉄系合金めっき鋼板を成形加工すると、下層として
の合金化溶融鉄−亜鉛合金めっき層に、陽極電解処理に
よってその表層に形成された凹凸を起点とした微細なク
ラックが発生する。この微細なクラックによって、成形
加工時に、上層からの局部応力が下層に集中することは
なく、従って、下層としての合金化溶融鉄−亜鉛合金め
っき層に破壊や剥離が生じないので、塗膜に生ずる気泡
状欠陥が防止される。When an iron-based alloy-plated steel sheet having a plurality of iron-based alloy-plated layers formed as described above is formed and processed, the alloyed molten iron-zinc alloy-plated layer as the lower layer is formed on the surface layer by anodic electrolytic treatment. Fine cracks originate from the unevenness. Due to these fine cracks, the local stress from the upper layer does not concentrate on the lower layer during the molding process, and therefore, the alloyed molten iron-zinc alloy plating layer as the lower layer does not break or peel off, so that the coating film Bubble defects that occur are prevented.
第１図は、この発明方法の１実施態様を示す概略工程図
である。図示しない溶融鉛めっき槽および合金化処理装
置によって、第２図（イ）に模式図で示すように、鋼板
１の表面上に、下層としての合金化溶融鉄−亜鉛合金め
っき層２を形成する。このようにして、表面上に、下層
としての合金化溶融鉄−亜鉛合金めっき層２が形成され
た鋼板１を、鉄系合金電気めっき浴が収容された第１電
気めっき槽４に通し、第１電気めっき槽４において、陽
極電解処理を施す。この結果、第１電気めっき槽４内に
おいて、合金化溶融鉄−亜鉛合金めっき層２中における
卑な亜鉛リッチの相が優先的に溶出し、第２図（ロ）に
示すように、合金化溶融鉄−亜鉛合金めっき層２の表層
に多数の微細な凹凸2aが形成される。FIG. 1 is a schematic process diagram showing one embodiment of the method of the present invention. As shown in the schematic view of FIG. 2 (a), an alloyed molten iron-zinc alloy plating layer 2 as a lower layer is formed on the surface of the steel plate 1 by an unillustrated molten lead plating tank and an alloying treatment device. . In this way, the steel sheet 1 on which the alloyed molten iron-zinc alloy plating layer 2 as a lower layer is formed on the surface is passed through the first electroplating tank 4 containing the iron-based alloy electroplating bath, 1 In the electroplating tank 4, an anodic electrolytic treatment is performed. As a result, in the first electroplating tank 4, the base zinc-rich phase in the alloyed molten iron-zinc alloy plating layer 2 preferentially elutes, and as shown in FIG. A large number of fine irregularities 2a are formed on the surface layer of the molten iron-zinc alloy plating layer 2.
次いで、その表層に多数の微細な凹凸2aを有する下層と
しての合金化溶融鉄−亜鉛合金めっき層２が形成された
鋼板１を、第２電気めっき槽５、第３電気めっき槽６お
よび第４電気めっき槽７に順次通し、各電気めっき槽に
おいて陰極電解処理を施す。この結果、第２図（ハ）に
模式図で示すように、表層に多数の微細な凹凸2aを有す
る下層としての合金化溶融鉄−亜鉛合金めっき層２の上
に、上層としての鉄系合金電気めっき層３が形成され
る。Then, the steel sheet 1 on which the alloyed molten iron-zinc alloy plating layer 2 as a lower layer having a large number of fine irregularities 2a is formed on the surface layer thereof is used as a second electroplating bath 5, a third electroplating bath 6, and a fourth electroplating bath 6. The solution is passed through the electroplating tank 7 in sequence and subjected to cathodic electrolysis treatment in each electroplating tank. As a result, as shown in the schematic view in FIG. 2C, the alloyed molten iron-zinc alloy plating layer 2 as the lower layer having a large number of fine irregularities 2a on the surface layer, and the iron-based alloy as the upper layer The electroplated layer 3 is formed.
このようにして形成された複数の鉄系合金めっき層を有
する鉄系合金めっき鋼板を成形加工すると、前述したよ
うに、下層としての合金化溶融鉄−亜鉛合金めっき層２
に、その表層の凹凸2aを起点とする微細なクラックが発
生し、この微細なクラックによって、成形加工時の応力
の集中が防止される。従って、下層としての合金化溶融
鉄−亜鉛合金めっき層２に破壊や剥離が生ぜず、塗膜に
生ずる気泡状欠陥が防止される。When an iron-based alloy-plated steel sheet having a plurality of iron-based alloy-plated layers thus formed is formed and processed, as described above, the alloyed molten iron-zinc alloy plated layer 2 as the lower layer is formed.
At the same time, fine cracks starting from the unevenness 2a of the surface layer are generated, and these fine cracks prevent concentration of stress during molding. Therefore, the alloyed hot-dip iron-zinc alloy plating layer 2 as the lower layer is not broken or peeled off, and bubble-like defects that occur in the coating film are prevented.
上層としての鉄系合金電気めっき層３としては、50wt.
％以下の亜鉛を有する鉄−亜鉛合金、0.0003〜15wt.％
の燐を含有する鉄−燐合金、0.003〜3wt.％のボロンを
含有する鉄−ボロン合金等からなる２元系合金電気めっ
き層、または、上記合金の組合せからなる３元系合金電
気めっき層が好適である。As the iron-based alloy electroplating layer 3 as the upper layer, 50 wt.
% Fe-zinc alloy with less than 0.003%, 0.0003-15 wt.%
Binary alloy electroplating layer composed of iron-phosphorus alloy containing phosphorus, iron-boron alloy containing 0.003 to 3 wt.% Boron, or ternary alloy electroplating layer composed of a combination of the above alloys Is preferred.
第１電気めっき槽４における陽極電解処理等の電気量
は、１〜50c/dm2の範囲内であることが好ましい。陽極
電解処理時の電気量が1c/dm2未満では、合金化溶融鉄−
亜鉛合金めっき層２の表層に多数の微細な凹凸2aを形成
することができない。一方、陽極電解処理時の電気量が
50c/dm2を超えると、合金化溶融鉄−亜鉛合金めっき層
２が過度に溶解し、耐食性が劣化する。The amount of electricity for the anodic electrolysis in the first electroplating tank 4 is preferably within the range of 1 to 50 c / dm 2 . If the quantity of electricity during anodic electrolysis is less than 1 c / dm 2 , alloyed molten iron-
It is not possible to form a large number of fine irregularities 2a on the surface layer of the zinc alloy plating layer 2. On the other hand, the amount of electricity during anodizing
When it exceeds 50 c / dm 2 , the alloyed hot-dip iron-zinc alloy plating layer 2 is excessively melted and the corrosion resistance is deteriorated.
下層としての合金化溶融鉄−亜鉛合金めっき層２のめっ
き量は、鋼板１の片面当たり30〜120g/m2の範囲内とす
ることが好ましい。下層としての合金化溶融鉄−亜鉛合
金めっき層２のめっき量が鋼板１の片面当たり30g/m2未
満では、耐食性が劣化する。一方、めっき量が鋼板１の
片面当たり120g/m2超では、加工性が劣化する。The alloyed molten iron-zinc alloy plating layer 2 as the lower layer preferably has a plating amount of 30 to 120 g / m 2 per side of the steel sheet 1. When the amount of the alloyed molten iron-zinc alloy plating layer 2 as the lower layer is less than 30 g / m 2 per side of the steel sheet 1, the corrosion resistance deteriorates. On the other hand, if the plating amount exceeds 120 g / m 2 per side of the steel sheet 1, the workability deteriorates.
上層としての鉄系合金電気めっき層３のめっき量は、鋼
板１の片面当たり１〜10g/m2の範囲内とすることが好ま
しい。上層としての鉄系合金電気めっき層３のめっき量
が鋼板１の片面当たり1g/m2未満では、電着塗装性が劣
化し、塗膜にクレーター状ピンホールが発生しやすくな
る。一方、めっき量が、鋼板１の片面当たり10g/m2超で
は、加工性が劣化する。The plating amount of the iron-based alloy electroplating layer 3 as the upper layer is preferably within the range of 1 to 10 g / m 2 per side of the steel sheet 1. When the plating amount of the iron-based alloy electroplating layer 3 as the upper layer is less than 1 g / m 2 per side of the steel sheet 1, the electrodeposition coatability deteriorates and crater-like pinholes are likely to occur in the coating film. On the other hand, if the plating amount exceeds 10 g / m 2 per side of the steel sheet 1, the workability deteriorates.
下層としての合金化溶融鉄−亜鉛合金めっき層２の鉄含
有量は、７〜15wt.％の範囲内であることが好ましい。
鉄含有量が7wt.％未満では、耐食性が劣化する。一方、
鉄含有量が15wt.％超では、加工性が劣化する。The iron content of the alloyed molten iron-zinc alloy plating layer 2 as the lower layer is preferably in the range of 7 to 15 wt.%.
If the iron content is less than 7 wt.%, The corrosion resistance deteriorates. on the other hand,
If the iron content exceeds 15 wt.%, The workability will deteriorate.
次に、この発明の方法を、実施例により、比較例と対比
しながら説明する。Next, the method of the present invention will be described by way of Examples in comparison with Comparative Examples.
〔実施例１〕 板厚0.8mmの冷延鋼板に対し、下記に示す条件で合金化
溶融亜鉛めっき処理を施して、鋼板の表面上に、下層と
しての合金化溶融鉄−亜鉛合金めっき層を形成した。[Example 1] A cold-rolled steel sheet having a thickness of 0.8 mm was subjected to an alloying hot dip galvanizing treatment under the conditions shown below to form an alloyed hot iron-zinc alloy plating layer as a lower layer on the surface of the steel sheet. Formed.
（１） めっき浴化学成分組成： A1:0.12wt.％ Zn:残り （２） めっき温度:460℃ （３） めっき浴浸入供試体温度:470℃ （４） 合金化温度:510℃ （５） 合金化時間：所定の鉄含有量が得られるように
調整 次いで、下層としての合金化溶融鉄−亜鉛合金めっき層
が形成された鋼板を、鉄−亜鉛合金電気めっき浴が収容
された、第１電気めっき槽４、第２電気めっき槽５、第
３電気めっき槽６および第４電気めっき槽７に順次通
し、下記に示す条件で、第１電気めっき槽４において陽
極電解処理を施し、次いで、第２電気めっき槽５、第３
電気めっき槽６および第４電気めっき槽７において、陰
極電解処理を施した。(1) Chemical composition of plating bath: A1: 0.12wt.% Zn: Remaining (2) Plating temperature: 460 ℃ (3) Plating bath immersion sample temperature: 470 ℃ (4) Alloying temperature: 510 ℃ (5) Alloying time: adjusted so as to obtain a predetermined iron content. Then, the steel sheet on which an alloyed molten iron-zinc alloy plating layer as a lower layer was formed was placed in an iron-zinc alloy electroplating bath, the first The electroplating bath 4, the second electroplating bath 5, the third electroplating bath 6 and the fourth electroplating bath 7 are sequentially passed through, and an anodic electrolytic treatment is performed in the first electroplating bath 4 under the following conditions, and then, Second electroplating tank 5, third
In the electroplating bath 6 and the fourth electroplating bath 7, cathodic electrolysis treatment was performed.
（１） めっき浴の化学成分組成： FeSO4・7H2O:380g/ ZnSO4・7H2O:20g/ （２） めっき浴のpH:1.8 （３） めっき浴の温度:50℃ （４） めっき電気量： 第１電気めっき槽（陽極電解）:20c/dm2 第２電気めっき槽（陰極電解）:50A/dm2 第３電気めっき槽（陰極電解）:50A/dm2 第４電気めっき槽（陰極電解）:50A/dm2 このようにして、鋼板の表面上に、表層に多数の微細な
凹凸を有する下層としての合金化溶融鉄−亜鉛合金めっ
き層と、上層としての鉄−亜鉛合金電気めっき層とを有
する、第１表に示すこの発明の鉄−亜鉛合金めっき鋼板
の供試体（以下、本発明供試体という）No.1を調製し
た。(1) Chemical composition of plating bath: FeSO 4 · 7H 2 O: 380g / ZnSO 4 · 7H 2 O: 20g / (2) of the plating bath pH: 1.8 (3) of the plating bath temperature: 50 ° C. (4) Electricity of plating: 1st electroplating bath (anodic electrolysis): 20c / dm 2 2nd electroplating bath (cathodic electrolysis): 50A / dm 2 3rd electroplating bath (cathodic electrolysis): 50A / dm 2 4th electroplating Tank (cathodic electrolysis): 50 A / dm 2 In this way, on the surface of the steel sheet, the alloyed molten iron-zinc alloy plating layer as the lower layer having many fine irregularities on the surface layer and the iron-zinc as the upper layer Sample No. 1 of the iron-zinc alloy-plated steel sheet of the present invention shown in Table 1 (hereinafter referred to as the present invention sample) having an alloy electroplating layer was prepared.
〔実施例２〕 実施例１と同様の方法により、下層としての合金化溶融
鉄−亜鉛合金めっき層が形成された鋼板を、鉄−燐合金
電気めっき浴が収容された第１電気めっき槽４、第２電
気めっき槽５、第３電気めっき槽６および第４電気めっ
き槽７に順次導き、下記に示す条件で、第１電気めっき
槽４において陽極電解処理を施し、第２電気めっき槽
５、第３電気めっき槽６および第４電気めっき槽７にお
いて陰極電解処理を施した。[Example 2] By the same method as in Example 1, a steel sheet on which an alloyed molten iron-zinc alloy plating layer as a lower layer was formed was used as a first electroplating tank 4 containing an iron-phosphorus alloy electroplating bath. , The second electroplating bath 5, the third electroplating bath 6 and the fourth electroplating bath 7 in order, and under the conditions shown below, the first electroplating bath 4 is subjected to an anodic electrolysis treatment, and the second electroplating bath 5 In the third electroplating bath 6 and the fourth electroplating bath 7, cathodic electrolysis treatment was performed.
（１） めっき浴の化学成分組成： FeCl2:150g/ KCl:200g/ クエン酸:10g/ NaH2PO2:2g/ （２） めっき浴のpH:3.0 （３） めっき浴の温度:50℃ （４） めっき電気量： 第１電気めっき槽（陽極電解）:20c/dm2 第２電気めっき槽（陰極電解）:30A/dm2 第３電気めっき槽（陰極電解）:30A/dm2 第４電気めっき槽（陰極電解）:30A/dm2 このようにして、鋼板の表面上に、その表層に多数の微
細な凹凸を有する下層としての合金化溶融鉄−亜鉛合金
めっき層と、上層としての鉄−燐合金電気めっき層とを
有する、第１表に併せて示す本発明供試体No.2を調製し
た。(1) Chemical composition of plating bath: FeCl 2 : 150g / KCl: 200g / Citric acid: 10g / NaH 2 PO 2 : 2g / (2) Plating bath pH: 3.0 (3) Plating bath temperature: 50 ℃ (4) Plating electricity: 1st electroplating bath (anodic electrolysis): 20c / dm 2 2nd electroplating bath (cathodic electrolysis): 30A / dm 2 3rd electroplating bath (cathodic electrolysis): 30A / dm 2 4 Electroplating tank (cathodic electrolysis): 30 A / dm 2 Thus, on the surface of the steel sheet, the alloyed molten iron-zinc alloy plating layer as the lower layer having a large number of fine irregularities on its surface layer, and the upper layer as the upper layer Sample No. 2 of the present invention having the iron-phosphorus alloy electroplating layer of No. 2 shown in Table 1 was prepared.
比較のために、下層としての合金化溶融鉄−亜鉛合金め
っき層が形成された鋼板を、鉄−亜鉛合金電気めっき浴
が収容された、第１電気めっき槽、第２電気めっき槽お
よび第３電気めっき槽に順次通し、各電気めっき槽にお
いて下記電気量で陰極電解処理を施したほかは、実施例
１と同じ条件で、第１表に併せて示す、比較用の鉄−亜
鉛合金電気めっき鋼板の供試体（以下、比較用供試体と
いう）No.1を調製した。For comparison, a steel sheet on which an alloyed molten iron-zinc alloy plating layer was formed as a lower layer was formed into a first electroplating bath, a second electroplating bath and a third electroplating bath in which an iron-zinc alloy electroplating bath was housed. Comparative iron-zinc alloy electroplating under the same conditions as in Example 1 except that they were sequentially passed through an electroplating bath and subjected to cathodic electrolysis treatment in each electroplating bath with the following electricity amount. A steel plate specimen (hereinafter referred to as a comparative specimen) No. 1 was prepared.
第１電気めっき槽（陰極電解）:50A/dm2 第２電気めっき槽（陰極電解）:50A/dm2 第３電気めっき槽（陰極電解）:50A/dm2 このようにして調整された本発明供試体および比較用供
試体の各々について、電着塗装性および加工性を、以下
に述べる性能試験によって調査した。その試験結果を第
１表にて併せて示す。1st electroplating bath (cathodic electrolysis): 50A / dm 2 2nd electroplating bath (cathodic electrolysis): 50A / dm 2 3rd electroplating bath (cathodic electrolysis): 50A / dm 2 The electrodeposition coatability and workability of each of the inventive specimens and comparative specimens thus prepared were investigated by the performance test described below. The test results are also shown in Table 1.
（１） 電着塗装性試験 a.気泡状欠陥試験 本発明供試体および比較用供試体の各々の表面上に、浸
漬処理によって燐酸塩被膜を形成した後、下記条件によ
ってカチオンタイプの電着塗装を施した。(1) Electrodeposition coatability test a. Bubble defect test After forming a phosphate coating by dipping treatment on the surface of each of the sample of the present invention and the sample for comparison, cation type electrodeposition coating was performed under the following conditions. Was applied.
電圧:260V 浴温:27℃ 供試体面積／陽極面積:1/1 塗膜の厚さ:20μｍ 焼き付け温度:270℃ 焼き付け時間:10分 上記のようにして電着塗装を施した供試体の塗膜に生じ
た気泡状欠陥を、目視によって調べ、下記によって評価
した。Voltage: 260V Bath temperature: 27 ° C Specimen area / Anode area: 1/1 Coating thickness: 20μm Baking temperature: 270 ° C Baking time: 10 minutes Coating of the specimen electrodeposited as described above The bubble-like defects generated in the film were visually examined and evaluated by the following.
○：気泡状欠陥 なし △：気泡状欠陥 １〜10個 ×：気泡状欠陥 10個超 b:クレーター状ピンホール試験 本発明供試体および比較用供試体の各々の表面上に、浸
漬処理によって燐酸塩被膜を形成した後、下記条件によ
ってカチオンタイプの電着塗装を施した。○: No bubble defects △: 1 to 10 bubble defects ×: More than 10 bubble defects b: Crater-like pinhole test Phosphoric acid on each surface of the test sample of the present invention and the test sample for comparison by dipping treatment After forming the salt film, cation type electrodeposition coating was applied under the following conditions.
電圧:280V 浴温:27℃ 供試体面積／陽極面積:1/1 塗膜の厚さ:20μｍ 焼き付け温度:170℃ 焼き付け時間:25分 上記のようにして電着塗装を施した供試体の塗膜に生じ
たクレーター状ピンホールを、目視によって調べ、下記
によって評価した。Voltage: 280V Bath temperature: 27 ° C Specimen area / Anode area: 1/1 Coating thickness: 20μm Baking temperature: 170 ° C Baking time: 25 minutes Coating of the specimens electrodeposited as described above The crater-like pinholes formed in the film were visually examined and evaluated by the following.
○：クレーター状ピンホール 20個以下 △：クレーター状ピンホール 20〜100個 ×：クレーター状ピンホール 100個超 （２） 加工性試験 供試体を第３図に示したドロービード試験機を使用して
しごき、めっき被膜の単位面積当たりの剥離量を、以下
に述べる方法により測定した。○: 20 or less crater-shaped pinholes △: 20 to 100 crater-shaped pinholes ×: Over 100 crater-shaped pinholes (2) Workability test Using the draw bead tester shown in Fig. 3 for the test specimen The amount of ironing and peeling of the plating film per unit area was measured by the method described below.
即ち、第３図に概略断面図で示すような、所定長さの実
質的に水平な突条8aを有する雄ダイス８と、雄ダイス８
の突条8aと向き合った所定長さの実質的に水平な溝9aを
有する雌ダイス９とからなるドロービード試験機を使用
し、供試体10を、上述したドロービード試験機の雄ダイ
ス８と雌ダイス９との間の間隙内に垂直に挿入し、雄ダ
イス８と雌ダイス９とを、500Kgfの圧力で押しつけ、そ
して、矢印に示すように上方に引き抜いてしごいた。こ
のようにしてしごかれた供試体10に接着テープを貼り次
いでこれを剥がして、めっき被膜の剥離量を測定した。
なお、雄ダイス８の突条8aの先端は0.5R、雌ダイス９の
肩は1R、そして、雄ダイス８の突条8aおよび雌ダイス９
の溝9aの幅は40mm、供試体10の幅は30mmであった。That is, as shown in the schematic sectional view of FIG. 3, a male die 8 having a substantially horizontal protrusion 8a of a predetermined length, and a male die 8
Using a draw bead tester comprising a ridge 8a of the above and a female die 9 having a substantially horizontal groove 9a of a predetermined length facing each other, and using a test piece 10 as a male die 8 and a female die of the above-mentioned draw bead tester. 9 was vertically inserted into the space between the male die 8 and the female die 9, and the male die 8 and the female die 9 were pressed with a pressure of 500 Kgf and then pulled upward as shown by the arrow. An adhesive tape was attached to the specimen 10 thus squeezed, and then the adhesive tape was peeled off to measure the peeled amount of the plating film.
The tip of the protrusion 8a of the male die 8 is 0.5R, the shoulder of the female die 9 is 1R, and the protrusion 8a of the male die 8 and the female die 9 are
The groove 9a had a width of 40 mm, and the sample 10 had a width of 30 mm.
第１表から明らかなように、下層としての合金化溶融鉄
−亜鉛合金めっき層が形成された鋼板を、鉄−亜鉛合金
電気めっき浴が収容された第１〜第３電気めっき槽の全
部で陰極電解処理を施した比較用供試体No.1は、塗膜中
に気泡状欠陥が多量に発生し、電着塗装性が悪かった。As is clear from Table 1, the steel sheet on which the alloyed molten iron-zinc alloy plating layer was formed as the lower layer was used in all of the first to third electroplating tanks containing the iron-zinc alloy electroplating bath. The comparative sample No. 1 which was subjected to the cathodic electrolysis treatment had a large number of bubble-like defects in the coating film, and the electrodeposition coatability was poor.
これに対して、第１表から明らかなように、本発明供試
体No.1および２は、何れも、塗膜に気泡状欠陥が発生せ
ず、そして、クレーター状ピンホールの発生も少なく、
電着塗装性および加工性に優れていた。On the other hand, as is clear from Table 1, in each of Sample Nos. 1 and 2 of the present invention, no bubble-like defects were generated in the coating film, and the occurrence of crater-like pinholes was small,
It was excellent in electrodeposition paintability and workability.
以上述べたように、この発明によれば、プレス等によっ
て厳しい成形加工が施されても、塗膜に、下層としての
合金化溶融鉄−亜鉛合金めっき層に発生した亀裂や剥離
に基づく気泡状欠陥が生ぜず、且つ、クレーター状ピン
ホールも殆ど生じない、電着塗装性および加工性に優れ
た、複数の鉄系合金めっき層を有する鉄系合金めっき鋼
板を製造することができる、工業上有用な効果がもたら
される。As described above, according to the present invention, even when subjected to severe forming processing such as pressing, the coating film has a bubble shape based on cracks or peeling generated in the alloyed molten iron-zinc alloy plating layer as the lower layer. It is possible to manufacture an iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers, which does not cause defects and hardly causes crater-like pinholes, and which is excellent in electrodeposition paintability and workability. It has a useful effect.
第１図は、この発明の方法の１実施態様を示す工程図、
第２図（イ）〜（ハ）は、この発明の方法による鉄系合
金めっき鋼板の製造過程を示す断面模式図、第３図は、
加工性試験に使用したドロービード試験機の概略断面図
である。 図面において、 １……鋼板、 ２……合金化溶融鉄−亜鉛合金めっき層 2a……微細な凹凸 ３……鉄系合金電気めっき層、 ４……第１電気めっき槽、５……第２電気めっき槽 ６……第３電気めっき槽、７……第４電気めっき槽、 ８……雄ダイス、8a……突条、 ９……雌ダイス、9a……溝、 10……供試体。FIG. 1 is a process drawing showing one embodiment of the method of the present invention,
2 (a) to (c) are schematic cross-sectional views showing the manufacturing process of the iron-based alloy-plated steel sheet according to the method of the present invention, and FIG.
It is a schematic sectional drawing of the draw bead testing machine used for the workability test. In the drawings, 1 ... Steel plate, 2 ... Alloyed molten iron-zinc alloy plating layer 2a ... Fine irregularities 3 ... Iron-based alloy electroplating layer, 4 ... First electroplating tank, 5 ... Second Electroplating tank 6 ... 3rd electroplating tank, 7 ... 4th electroplating tank, 8 ... Male die, 8a ... Rims, 9 ... Female die, 9a ... Groove, 10 ... Specimen.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｃ２５Ｄ 11/34 ３０３ (72)発明者 稲垣 淳一 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 昭63−157847（ＪＰ，Ａ) 特開 昭60−224791（ＪＰ，Ａ)─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification number Reference number within the agency FI Technical indication location C25D 11/34 303 (72) Inventor Junichi Inagaki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihonhon Steel Pipe Co., Ltd. (72) Inventor Masaya Morita 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (56) Reference JP-A-63-157847 (JP, A) JP-A-60-224791 (JP, A)
Claims (2)
融亜鉛めっき槽に通し、前記鋼板の表面上に亜鉛めっき
層を形成し、次いで、前記鋼板を加熱して前記亜鉛めっ
き層と前記鋼板とを合金化させ、かくして、前記鋼板の
少なくとも１つの表面上に、所定めっき量の下層として
の合金化溶融鉄−亜鉛合金めっき層を形成し、次いで、
前記下層としての合金化溶融鉄−亜鉛合金めっき層が形
成された鋼板を、鉄系合金電気めっき浴が収容された複
数の電気めっき槽に順次通し、前記鋼板に陰極電解処理
を施すことにより、前記下層としの合金化溶融鉄−亜鉛
合金めっき層の上に、上層としての鉄系合金電気めっき
層を形成する、複数の鉄系合金めっき層を有する鉄系合
金めっき鋼板の製造方法において、 前記複数の電気めっき槽の初槽において、前記下層とし
の合金化溶融鉄−亜鉛合金めっき層が形成された鋼板に
対し陽極電解処理を施し、前記下層としの合金化溶融鉄
−亜鉛合金めっき層の一部を溶解させて、その表層に多
数の微細な凹凸を形成し、次いで、以降の電気めっき槽
において陰極電解処理を施し、表層に微細な凹凸が形成
された下層としての合金化溶融鉄−亜鉛合金めっき槽の
上に、前記上層としての鉄系合金電気めっき層を形成す
ることを特徴とする、電気塗装性および加工性に優れ
た、複数の鉄系合金めっき層を有する鉄系合金めっき鋼
板の製造方法。1. A steel sheet is passed through a hot dip galvanizing bath containing a hot dip galvanizing bath to form a galvanized layer on the surface of the steel sheet, and then the steel sheet is heated to form the galvanized layer and the galvanized layer. A steel sheet is alloyed, thus forming an alloyed molten iron-zinc alloy plating layer as a lower layer of a predetermined plating amount on at least one surface of the steel sheet, and then,
The steel sheet on which the alloyed molten iron-zinc alloy plating layer is formed as the lower layer is sequentially passed through a plurality of electroplating tanks containing an iron-based alloy electroplating bath, and the steel sheet is subjected to cathodic electrolysis treatment, On the alloyed molten iron-zinc alloy plating layer as the lower layer, the iron-based alloy electroplating layer as the upper layer is formed, in the method for producing an iron-based alloy plated steel sheet having a plurality of iron-based alloy plating layers, In the first bath of a plurality of electroplating baths, anodized electrolytic treatment is applied to the steel sheet on which the alloyed molten iron-zinc alloy plating layer as the lower layer is formed, and the alloyed molten iron-zinc alloy plated layer as the lower layer Part of it is melted to form a large number of fine irregularities on its surface layer, and then subjected to cathodic electrolysis treatment in the subsequent electroplating bath to form an alloyed molten iron as a lower layer having fine irregularities formed on the surface layer. A An iron-based alloy plating having a plurality of iron-based alloy plating layers excellent in electropaintability and workability, characterized in that an iron-based alloy electroplating layer as the upper layer is formed on a lead alloy plating tank. Steel plate manufacturing method.
極電解処理時の電気量が、１〜50c/dm2である請求項１
記載の方法。2. The amount of electricity at the time of anodic electrolysis in the first bath of the plurality of electroplating baths is 1 to 50 c / dm 2.
The method described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2338837A JPH0765191B2 (en) | 1990-11-30 | 1990-11-30 | Method for producing iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers, which has excellent electrodeposition coatability and workability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2338837A JPH0765191B2 (en) | 1990-11-30 | 1990-11-30 | Method for producing iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers, which has excellent electrodeposition coatability and workability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04202788A JPH04202788A (en) | 1992-07-23 |
| JPH0765191B2 true JPH0765191B2 (en) | 1995-07-12 |
Family
ID=18321892
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2338837A Expired - Lifetime JPH0765191B2 (en) | 1990-11-30 | 1990-11-30 | Method for producing iron-based alloy-plated steel sheet having a plurality of iron-based alloy plating layers, which has excellent electrodeposition coatability and workability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0765191B2 (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60224791A (en) * | 1984-04-23 | 1985-11-09 | Nippon Steel Corp | Installation for producing double-layered galvanized steel sheet |
| JPS63157847A (en) * | 1986-12-19 | 1988-06-30 | Nippon Steel Corp | Manufacture of alloying-galvanized steel sheet |
| JPH02145779A (en) * | 1988-11-28 | 1990-06-05 | Kobe Steel Ltd | Zn-fe flash plating method for alloyed hot dip galvanized steel sheet |
| JPH02282488A (en) * | 1989-04-21 | 1990-11-20 | Sumitomo Metal Ind Ltd | Double-ply plated steel sheet |
-
1990
- 1990-11-30 JP JP2338837A patent/JPH0765191B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04202788A (en) | 1992-07-23 |
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