JPH05195182A - Hot-dip aluminizing method of high cr ferritic stainless steel sheet - Google Patents
Hot-dip aluminizing method of high cr ferritic stainless steel sheetInfo
- Publication number
- JPH05195182A JPH05195182A JP3150392A JP3150392A JPH05195182A JP H05195182 A JPH05195182 A JP H05195182A JP 3150392 A JP3150392 A JP 3150392A JP 3150392 A JP3150392 A JP 3150392A JP H05195182 A JPH05195182 A JP H05195182A
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- Prior art keywords
- stainless steel
- plating
- hot
- hydrogen
- bath
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、欠陥がなく加工性に優
れた溶融アルミめっき高Ｃｒフェライト系ステンレス鋼
板を製造する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hot-dip aluminum plated high Cr ferritic stainless steel sheet having no defects and excellent workability.
【０００２】[0002]
【従来の技術】溶融アルミめっき鋼板は、優れた耐食
性，耐熱性を示し、自動車の排気系，建材，家電製品の
部材等として広範な分野で使用されている。しかし、母
材として炭素鋼板，低Ｃｒステンレス鋼板等を使用する
と、過酷な腐食環境では比較的短期間に切断端面，疵
部，曲げ加工部等に赤錆が発生する。この赤錆は、切
断，加工等によってアルミめっき層に欠陥が発生し、母
材鋼が露出した部分を起点とする。アルミめっき層欠陥
部に発生した赤錆は、母材全域に進行し、全面的な赤錆
や母材を貫通する孔明きに至ることがある。2. Description of the Related Art Hot-dip aluminized steel sheets exhibit excellent corrosion resistance and heat resistance, and are used in a wide range of fields such as automobile exhaust systems, building materials, and home electric appliances. However, when a carbon steel plate, a low Cr stainless steel plate or the like is used as the base material, red rust occurs on the cut end face, the flaw portion, the bent portion, etc. in a relatively short period of time in a severe corrosive environment. This red rust originates from the part where the base metal steel is exposed due to the occurrence of defects in the aluminum plating layer due to cutting and processing. The red rust generated in the defective portion of the aluminum plating layer may progress to the entire area of the base material and may lead to red rust on the entire surface or perforation that penetrates the base material.
【０００３】母材の耐食性を高めるためには、従来の炭
素鋼板，低Ｃｒステンレス鋼板等に替え、耐食性の優れ
た高Ｃｒステンレス鋼板を使用される。たとえば、塩害
に晒される海岸地帯，海上等の建築物、融雪剤が散布さ
れる寒冷地を走行する自動車等の構造材として、溶融ア
ルミめっきを施した高Ｃｒステンレス鋼板を使用するこ
とが進められてきた。In order to enhance the corrosion resistance of the base material, a high Cr stainless steel sheet having excellent corrosion resistance is used instead of the conventional carbon steel sheet, low Cr stainless steel sheet or the like. For example, it has been promoted to use high Cr stainless steel plate plated with hot-dip aluminum as a structural material for coastal areas exposed to salt damage, buildings on the sea, automobiles running in cold regions where snow-melting agents are sprayed, and the like. Came.
【０００４】しかし、高Ｃｒステンレス鋼板の表面に形
成されている不動態皮膜は、強固で緻密な酸化物層とな
っており、通常の連続溶融アルミめっきラインにおける
還元焼鈍工程で還元除去することができない。そして、
不動態皮膜が残存したままで高Ｃｒステンレス鋼板を溶
融アルミめっき浴に導入すると、溶融アルミに対する鋼
板表面の濡れ性が悪いことから、不めっき等の欠陥をも
つアルミめっき層が形成される。However, the passivation film formed on the surface of the high Cr stainless steel sheet is a strong and dense oxide layer, and it can be reduced and removed by the reduction annealing process in a normal continuous hot dip aluminum coating line. Can not. And
When a high Cr stainless steel sheet is introduced into a hot-dip aluminizing bath while the passivation film remains, an aluminum plating layer having defects such as non-plating is formed because the wettability of the steel sheet surface to the hot-dip aluminum is poor.
【０００５】不めっきを防止するため、高Ｃｒステンレ
ス鋼板の表面に予めＦｅ，Ｆｅ−Ｂ，Ｎｉ，Ｆｅ−Ｎｉ
等のプレめっき層を形成し、このプレめっき層の上に溶
融アルミめっき層を形成する方法が採られている（たと
えば、特開昭６０−２６２９５０号公報，特開平１−２
８３５１号公報等参照）。In order to prevent non-plating, Fe, Fe-B, Ni, Fe-Ni are previously formed on the surface of the high Cr stainless steel plate.
And the like, and a hot-dip aluminum plating layer is formed on the pre-plated layer (for example, JP-A-60-262950 and JP-A 1-2).
8351 gazette etc.).
【０００６】[0006]
【発明が解決しようとする課題】Ｆｅ，Ｆｅ−Ｂ，Ｎ
ｉ，Ｆｅ−Ｎｉ等をプレめっきすることにより、母材で
あるステンレス鋼板に施された溶融アルミめっき層に発
生する不めっき等の欠陥が少なくなる。しかし、めっき
されたステンレス鋼板に高度の加工を施すとき、割れが
発生する新たな問題が生じる。割れ発生の傾向は、ステ
ンレス鋼のＣｒ含有量が高くなるに従って顕著になる。Problems to be Solved by the Invention Fe, Fe-B, N
By pre-plating i, Fe-Ni and the like, defects such as non-plating that occur in the hot-dip aluminized layer applied to the stainless steel plate as the base material are reduced. However, when the plated stainless steel sheet is subjected to a high degree of processing, a new problem occurs in which cracks occur. The tendency of cracking becomes more significant as the Cr content of stainless steel increases.
【０００７】割れ発生は、Ｆｅ，Ｆｅ−Ｂ，Ｎｉ，Ｆｅ
−Ｎｉ等のプレめっき時に発生した水素ガス，熱処理時
に炉内雰囲気に含まれている水素ガス等がステンレス鋼
に侵入したことに原因があるものと推察される。すなわ
ち、水素ガスの侵入によってステンレス鋼の水素濃度が
上昇し、水素脆化を起こし、ステンレス鋼の割れ感受性
を高める結果、加工時に割れが発生し易くなる。Cracking is caused by Fe, Fe-B, Ni, Fe
It is presumed that the cause is that hydrogen gas generated during pre-plating of Ni or the like, hydrogen gas contained in the furnace atmosphere during heat treatment, etc., penetrated into the stainless steel. That is, the intrusion of hydrogen gas increases the hydrogen concentration of the stainless steel, causes hydrogen embrittlement, and increases the crack susceptibility of the stainless steel. As a result, cracks are likely to occur during processing.
【０００８】本発明は、このような問題を解消すべく案
出されたものであり、プレめっき時に吸収した水素を自
然放出させたステンレス鋼板を溶融アルミめっき直前に
還元性雰囲気中で加熱することにより、割れ感受性を高
める水素濃度を低減し、加工性に優れた溶融アルミめっ
き高Ｃｒフェライト系ステンレス鋼板を製造することを
目的とする。The present invention has been devised in order to solve such a problem, in which a stainless steel plate on which hydrogen absorbed during pre-plating is spontaneously released is heated in a reducing atmosphere immediately before hot dip aluminum plating. Thus, it is an object of the present invention to produce a hot-dip aluminum-plated high Cr ferritic stainless steel sheet having excellent workability by reducing the hydrogen concentration that enhances cracking susceptibility.
【０００９】[0009]
【課題を解決するための手段】本発明の溶融アルミめっ
き方法は、その目的を達成するため、１６〜３５重量％
のＣｒを含有するフェライト系ステンレス鋼板をプレめ
っきして２４時間以上放置した後、水素ガス濃度が５０
体積％以下で露点が−３０℃以下の水素−窒素雰囲気中
で加熱し、引き続いて溶融アルミ浴又は溶融アルミ合金
浴に導入することを特徴とする。In order to achieve the object, the hot-dip aluminum plating method of the present invention is 16 to 35% by weight.
After pre-plating the Cr-containing ferritic stainless steel sheet and leaving it for 24 hours or more, the hydrogen gas concentration becomes 50
It is characterized in that it is heated in a hydrogen-nitrogen atmosphere having a dew point of -30 ° C or less at a volume% or less and subsequently introduced into a molten aluminum bath or a molten aluminum alloy bath.
【００１０】プレめっきは、特に限定されるものではな
いが、Ｆｅ−Ｂプレめっきが好ましい。また、溶融アル
ミ浴又は溶融アルミ合金浴の温度Ｔを基準として、加熱
中の最高到達温度がＴ＋１００℃以下、溶融アルミ浴又
は溶融アルミ合金浴に導入される直前の温度がＴ±５０
℃に維持されるように、水素−窒素雰囲気中で高Ｃｒス
テンレス鋼板を加熱することが好ましい。Pre-plating is not particularly limited, but Fe-B pre-plating is preferred. Further, based on the temperature T of the molten aluminum bath or molten aluminum alloy bath, the maximum temperature reached during heating is T + 100 ° C. or lower, and the temperature immediately before being introduced into the molten aluminum bath or molten aluminum alloy bath is T ± 50.
It is preferable to heat the high Cr stainless steel plate in a hydrogen-nitrogen atmosphere so that the temperature is maintained at 0 ° C.
【００１１】[0011]
【作 用】本発明者等は、溶融アルミめっき高フェライ
ト系Ｃｒステンレス鋼板の水素濃度を低減させる方法に
付いて、めっき欠陥をも考慮しながら詳細に調査・研究
した。また、プレめっきから溶融アルミめっきまでに至
る過程で、ステンレス鋼板に含まれている水素の挙動を
調査した。[Operation] The present inventors have conducted a detailed investigation and research on a method of reducing the hydrogen concentration of a hot-dip aluminum-plated high-ferrite Cr stainless steel sheet, taking plating defects into consideration. In addition, the behavior of hydrogen contained in the stainless steel sheet was investigated in the process from pre-plating to hot dip aluminum coating.
【００１２】Ｆｅ−Ｂプレめっき直後におけるステンレ
ス鋼板の水素濃度は、めっき前に比較し３〜４倍増加し
ていた。そのため、プレめっきされたステンレス鋼板を
連続して溶融アルミめっき浴に導入して溶融めっきを行
うと、得られた製品の水素濃度が高く、水素脆化に起因
する割れが発生し易いものとなる。The hydrogen concentration of the stainless steel plate immediately after the Fe-B pre-plating was increased 3 to 4 times as compared with that before the plating. Therefore, when the pre-plated stainless steel plate is continuously introduced into the hot dip aluminum plating bath and hot dip plating is performed, the hydrogen concentration of the obtained product is high, and cracks due to hydrogen embrittlement easily occur. ..
【００１３】これに対し、プレめっきされたステンレス
鋼板を２４時間以上放置すると、水素濃度は、プレめっ
き前とほぼ同じレベルまで減少していた。水素濃度の減
少は、放置されたステンレス鋼板に吸収されている水素
が自然に放散されることに由来するものであり、２４時
間以上の放置によってプレめっき時に吸収された水素が
ほぼ全量放散される。プレめっき時に吸収された水素の
放散は、Ｆｅ−Ｂプレめっきに限らず、Ｆｅ，Ｎｉ，Ｆ
ｅ−Ｎｉ等のプレめっきにおいても同様であった。On the other hand, when the pre-plated stainless steel plate was left for 24 hours or more, the hydrogen concentration was reduced to almost the same level as before the pre-plating. The decrease in hydrogen concentration is due to the fact that the hydrogen absorbed by the left-standing stainless steel plate is naturally released, and the hydrogen absorbed during the pre-plating is released almost entirely when left for 24 hours or more. . The release of hydrogen absorbed during pre-plating is not limited to Fe-B pre-plating, but Fe, Ni, F
The same was true for pre-plating with e-Ni or the like.
【００１４】また、溶融アルミめっき直前の雰囲気ガス
によっても、ステンレス鋼板の水素濃度が変動すること
を解明した。すなわち、水素濃度５０体積％以下，露点
−３０℃以下の水素−窒素雰囲気を使用するとき、ステ
ンレス鋼板に対する水素ガスの侵入が減少し、且つ形成
された溶融アルミめっき層に不めっき等の欠陥が発生し
ないことを見い出した。Further, it has been clarified that the hydrogen concentration of the stainless steel plate also varies depending on the atmospheric gas immediately before the hot dip aluminum coating. That is, when a hydrogen-nitrogen atmosphere having a hydrogen concentration of 50% by volume or less and a dew point of -30 ° C or less is used, invasion of hydrogen gas into a stainless steel plate is reduced, and defects such as non-plating are generated in the formed molten aluminum plating layer. I found that it does not happen.
【００１５】他方、水素濃度が５０体積％を超える雰囲
気でステンレス鋼板を加熱するとき、雰囲気ガスからの
水素吸収が多くなる。また、露点−３０℃を超える湿潤
雰囲気では、プレめっき層が酸化がし易く、不めっきの
発生原因となる。On the other hand, when the stainless steel sheet is heated in an atmosphere having a hydrogen concentration of more than 50% by volume, hydrogen absorption from the atmosphere gas increases. Further, in a humid atmosphere having a dew point of -30 ° C or higher, the pre-plated layer is easily oxidized, which causes non-plating.
【００１６】水素吸収は、溶融アルミめっき直前におけ
るステンレス鋼板の加熱温度によっても影響される。す
なわち、ステンレス鋼板の温度が高すぎると、水素吸収
反応や雰囲気中の水分の分解反応等が活発になり、ステ
ンレス鋼板の水素濃度を上昇させる。この点、溶融アル
ミめっき浴又は溶融アルミ合金めっき浴の温度Ｔに対し
加熱時の最高到達温度をＴ＋１００℃に維持しておく
と、水素濃度が低いままでステンレス鋼板を溶融アルミ
めっき浴又は溶融アルミ合金めっき浴に導入することが
できる。Hydrogen absorption is also affected by the heating temperature of the stainless steel plate immediately before hot dip aluminum coating. That is, if the temperature of the stainless steel sheet is too high, the hydrogen absorption reaction, the decomposition reaction of moisture in the atmosphere, etc. become active, and the hydrogen concentration of the stainless steel sheet is increased. In this respect, if the maximum temperature reached during heating is maintained at T + 100 ° C with respect to the temperature T of the hot dip aluminum plating bath or hot dip aluminum alloy plating bath, the stainless steel sheet will remain hot in the hot dip aluminum plating bath or hot dip aluminum It can be introduced into the alloy plating bath.
【００１７】また、溶融アルミめっき直前の温度をＴ±
５０℃に維持するとき、めっきされるステンレス鋼板と
溶融アルミめっき浴又は溶融アルミ合金めっき浴との温
度差が小さくなる。そのため、めっき浴に導入されたス
テンレス鋼板の表面温度が急激に変動することがなく、
めっき金属が円滑に鋼板表面に付着・成長する。Further, the temperature immediately before hot dip aluminum plating is T ±
When maintained at 50 ° C, the temperature difference between the stainless steel plate to be plated and the hot dip aluminum plating bath or hot dip aluminum alloy plating bath becomes small. Therefore, the surface temperature of the stainless steel plate introduced into the plating bath does not change rapidly,
The plated metal smoothly adheres to and grows on the steel plate surface.
【００１８】この点、溶融アルミめっき直前の温度が高
過ぎると、めっき浴に導入されたステンレス鋼板が急激
に冷却される。逆に、溶融アルミめっき直前の温度が低
過ぎると、めっき浴に導入されたステンレス鋼板によっ
て周囲のめっき金属が急激に冷却される。このような急
激な温度変動は、円滑なめっき金属の付着を阻害し、形
成された溶融アルミめっき層に不めっき等の欠陥を発生
させる。In this respect, if the temperature immediately before the hot dip aluminum coating is too high, the stainless steel plate introduced into the plating bath is cooled rapidly. On the contrary, if the temperature immediately before the hot dip aluminum coating is too low, the surrounding plated metal is rapidly cooled by the stainless steel plate introduced into the plating bath. Such a sudden temperature change hinders smooth adhesion of the plated metal and causes defects such as non-plating in the formed molten aluminum plating layer.
【００１９】このようにして、本発明においては、プレ
めっき後に水素を自然放散させるための放置，溶融アル
ミめっき前の加熱雰囲気の調節及び加熱温度の制御によ
り、水素濃度を低く抑えた高Ｃｒフェライト系ステンレ
ス鋼に対する溶融アルミめっきが可能となる。その結
果、水素脆化に起因する割れ等を発生することなく、加
工性に優れた溶融アルミめっき高Ｃｒフェライト系ステ
ンレス鋼が得られる。また、耐食性に優れた溶融アルミ
めっき層及び高Ｃｒフェライト系ステンレス鋼の組合せ
により、過酷な腐食環境でも優れた耐食性を呈する材料
となる。As described above, in the present invention, the high Cr ferrite in which the hydrogen concentration is suppressed to a low level by allowing the hydrogen to naturally diffuse after pre-plating, adjusting the heating atmosphere before hot dip aluminum coating and controlling the heating temperature. Enables hot-dip aluminum plating on stainless steel. As a result, a hot-dip aluminum-plated high Cr ferritic stainless steel excellent in workability can be obtained without causing cracks and the like due to hydrogen embrittlement. Further, the combination of the hot dip aluminum plating layer having excellent corrosion resistance and the high Cr ferritic stainless steel provides a material having excellent corrosion resistance even in a severe corrosive environment.
【００２０】本発明で使用する高Ｃｒフェライト系ステ
ンレス鋼は、耐食性及び加工性を確保することから、１
６〜３５重量％のＣｒを含むことが必要である。一般
に、炭素鋼板，低Ｃｒステンレス鋼板等を母材とする溶
融アルミめっき鋼板では、過酷な腐食環境に晒されたと
き、切断端面，疵部，曲げ加工部等に比較的短時間で赤
錆が発生する。この赤錆発生部分から母材の侵食が進行
し、全面的な赤錆や母材を貫通する孔明きに至ることが
ある。The high Cr ferritic stainless steel used in the present invention ensures corrosion resistance and workability.
It is necessary to contain 6 to 35% by weight of Cr. In general, hot-dip aluminized steel sheets that use carbon steel sheets, low Cr stainless steel sheets, etc. as base materials, generate red rust on the cut edges, flaws, bent parts, etc. in a relatively short time when exposed to a severe corrosive environment. To do. Corrosion of the base material progresses from the portion where the red rust is generated, which may lead to full-scale red rust or perforation that penetrates the base material.
【００２１】高Ｃｒフェライト系ステンレス鋼を母材と
して使用すると、赤錆，全面腐食，孔明き等の問題が解
消される。高Ｃｒフェライト系ステンレス鋼は、Ｃｒ含
有量の増加に従って腐食電位が上昇し、耐食性が向上す
る。そして、めっき層に何らかの原因で部分的な剥離，
亀裂等が生じても、母材露出部の耐食性が優れているた
め、赤錆等の腐食発生が抑制される。また、めっき層で
あるアルミの腐食生成物による防食効果も期待できる。When high Cr ferritic stainless steel is used as a base material, problems such as red rust, general corrosion and perforation are solved. In the high Cr ferritic stainless steel, the corrosion potential increases as the Cr content increases, and the corrosion resistance improves. Then, the plating layer is partially peeled off for some reason,
Even if cracks or the like occur, the corrosion resistance of the exposed portion of the base material is excellent, so that the occurrence of corrosion such as red rust is suppressed. In addition, the anticorrosion effect of the corrosion product of aluminum, which is the plating layer, can be expected.
【００２２】このような耐食性の改善には、１６重量％
以上のＣｒ含有量が必要である。Ｃｒ含有量が１６重量
％未満であると、耐食性改善効果が小さい。逆に、３５
重量％を超えるＣｒ含有量では、ステンレス鋼自体の硬
度が高くなり、高度の加工を行うことができなくなる。
したがって、耐食性及び加工性の面から、母材である高
Ｃｒフェライト系ステンレス鋼板のＣｒ含有量を１６〜
３５重量％の範囲に規定した。To improve such corrosion resistance, 16% by weight is used.
The above Cr content is required. If the Cr content is less than 16% by weight, the effect of improving corrosion resistance is small. Conversely, 35
When the Cr content is more than wt%, the hardness of the stainless steel itself becomes high and it becomes impossible to perform high-level processing.
Therefore, from the viewpoint of corrosion resistance and workability, the Cr content of the high Cr ferritic stainless steel sheet as the base material is 16 to
It was defined in the range of 35% by weight.
【００２３】本発明で使用する高Ｃｒフェライト系ステ
ンレス鋼板は、耐食性，耐熱性，靭性等，機械的強度を
付与するため、Ｃｒ以外に他の合金元素を含むことがで
きる。たとえば、Ｍｏ：０．３〜６重量％，Ａｌ：０．
０１〜０．５重量％，Ｎｂ：０．１〜０．６重量％，Ｔ
ｉ：０．０５〜０．３重量％，Ｃｕ：０．１〜１．０重
量％，Ｚｒ：０．０５〜０．３重量％等の合金元素の１
種又は２種以上を必要に応じて添加することができる。The high Cr ferritic stainless steel sheet used in the present invention can contain other alloying elements besides Cr in order to impart mechanical strength such as corrosion resistance, heat resistance and toughness. For example, Mo: 0.3 to 6% by weight, Al: 0.
01-0.5% by weight, Nb: 0.1-0.6% by weight, T
1 of alloying elements such as i: 0.05 to 0.3% by weight, Cu: 0.1 to 1.0% by weight, Zr: 0.05 to 0.3% by weight
One kind or two or more kinds can be added as necessary.
【００２４】[0024]
【実施例】表１に示した化学成分のステンレス鋼を溶製
し、熱間圧延によって板厚３．５ｍｍの熱延板を製造し
た。次いで、熱延板を板厚０．８ｍｍまで冷間圧延し、
１０００〜１０５０℃で仕上げ焼鈍したものを、溶融ア
ルミめっき鋼板のめっき原板として供した。Example A stainless steel sheet having a chemical composition shown in Table 1 was melted and hot-rolled to produce a hot-rolled sheet having a thickness of 3.5 mm. Then, the hot rolled sheet is cold rolled to a sheet thickness of 0.8 mm,
What was finish-annealed at 1000 to 1050 ° C. was used as a plating original plate of a hot-dip aluminized steel sheet.
【００２５】[0025]
【表１】 めっき原板から５０ｍｍ×１５０ｍｍの試験片を切り出
し、Ｆｅ−Ｂのプレめっきを施した。Ｆｅ−Ｂプレめっ
きには、ＦｅＳＯ4・７Ｈ2 Ｏ−Ｈ3 ＢＯ3 −Ｎａ2 ＳＯ
4 浴を使用した。浴温５０℃に維持したプレめっき浴に
試験片を浸漬し、電流密度６０Ａ／ｄｍ2 で電気めっき
した。プレめっき層は、片面当りの目付け量２ｇ／ｍ2
で形成した。[Table 1] A test piece of 50 mm × 150 mm was cut out from the plating original plate and pre-plated with Fe—B. Fe-B in the pre-plating, FeSO 4 · 7H 2 O- H 3 BO 3 -Na 2 SO
4 baths were used. The test piece was immersed in a pre-plating bath maintained at a bath temperature of 50 ° C. and electroplated at a current density of 60 A / dm 2 . The pre-plating layer has a basis weight of 2 g / m 2 per side.
Formed by.
【００２６】プレめっき直後の試験片に対し、ＪＩＳ
Ｚ２２４８で規定された押曲げ法に準拠して２ｔ，１ｔ
及び密着曲げ試験を行った。また、プレめっき後に大気
中に２４時間及び７日間放置した試験片に付いても、同
様な試験を行った。試験結果を、表２に示す。表２にお
ける◎印は密着曲げ試験で割れが発生しない試験片を、
○印は密着曲げ試験で割れが発生した試験片を、△印は
１ｔ曲げ試験で割れが発生した試験片を、×印は２ｔ曲
げ試験で割れが発生した試験片をそれぞれ示す。JIS was applied to the test piece immediately after pre-plating.
2t, 1t based on the pressing and bending method specified by Z2248
And a contact bending test was performed. Further, the same test was performed on a test piece left in the atmosphere for 24 hours and 7 days after pre-plating. The test results are shown in Table 2. The ⊚ mark in Table 2 indicates a test piece that does not crack in the contact bending test.
The mark ◯ indicates a test piece in which a crack occurred in the close contact bending test, the mark Δ indicates a test piece in which a crack occurred in the 1t bending test, and the cross indicates a test piece in which a crack occurred in the 2t bending test.
【００２７】[0027]
【表２】 [Table 2]
【００２８】表２から明らかなように、プレめっき後に
２４時間以上放置することによって、プレめっきされた
ステンレス鋼板の耐割れ性が改善されていることが判
る。他方、プレめっき直後の試験片では、何れも密着曲
げ及びそれより緩やかな条件下での曲げ試験で割れが発
生している。また、プレめっき直後では、何れの試験片
においても２ｔ曲げで破断又は割れが検出された。この
割れ発生状況の相違は、大気中にステンレス鋼板を放置
することにより、プレめっき時に吸収された水素が放出
されることを示すものである。As is apparent from Table 2, it is understood that the crack resistance of the pre-plated stainless steel sheet is improved by leaving it for 24 hours or more after the pre-plating. On the other hand, in the test pieces immediately after the pre-plating, cracks were generated in the contact bending and the bending test under the milder condition. Immediately after pre-plating, breakage or cracking was detected at 2 t bending in any of the test pieces. This difference in the crack generation state indicates that the hydrogen absorbed during the pre-plating is released by leaving the stainless steel plate in the atmosphere.
【００２９】そこで、プレめっきされた試験片を大気中
に放置することにより、放出される水素量を定量的に調
べた。試験方法は、ＪＩＳ Ｚ２６１４に準拠し、プレ
めっき後の試験番号１，８及び９の試験片を対象とし
た。そして、試験片の水素濃度とＦｅ−Ｂプレめっき後
の放置期間との関係を調べたところ、両者の間に図１に
示す関係が成立していた。なお、図１における○，△及
び□はそれぞれ試験番号１，８及び９の試験片における
プレめっき後の水素濃度を示す。また、●，黒三角及び
黒四角は、プレめっきされていない試験番号１，８及び
９の試験片における水素濃度を示す。Therefore, the amount of hydrogen released was quantitatively examined by leaving the pre-plated test piece in the atmosphere. The test method was based on JIS Z2614, and the test pieces of test numbers 1, 8 and 9 after pre-plating were targeted. Then, when the relationship between the hydrogen concentration of the test piece and the standing period after the Fe-B pre-plating was examined, the relationship shown in FIG. 1 was established between them. In addition, ◯, Δ and □ in FIG. 1 represent hydrogen concentrations after pre-plating in the test pieces of test numbers 1, 8 and 9, respectively. Further, ●, black triangles and black squares show the hydrogen concentration in the test pieces of test numbers 1, 8 and 9 which were not pre-plated.
【００３０】図１から明らかなように、Ｆｅ−Ｂプレめ
っき直後では、何れの試験片も、プレめっき前の試験片
に比較して３〜４倍程度に水素濃度が増加していること
が判る。しかし、試験片の水素濃度は、放置期間の経過
と共に減少し、２４時間以上の放置でプレめっき前の水
素濃度とほぼ同じレベルまで下がっている。また、水素
濃度の減少は、試験番号１，８及び９の試験片の何れに
おいてもほぼ同じ傾向を示した。As is clear from FIG. 1, immediately after the Fe-B pre-plating, the hydrogen concentration in each of the test pieces was increased by about 3 to 4 times as compared with the test piece before the pre-plating. I understand. However, the hydrogen concentration of the test piece decreased with the passage of the standing period, and dropped to nearly the same level as the hydrogen concentration before pre-plating after standing for 24 hours or longer. Further, the decrease in hydrogen concentration showed almost the same tendency in all of the test pieces of Test Nos. 1, 8 and 9.
【００３１】Ｆｅ−Ｂプレめっきを施した後で２４時間
放置した試験片に、溶融アルミめっきを施した。溶融め
っき装置としては、試料準備室，雰囲気及び加熱条件を
自由に調節することができるイメージ炉及びポットを工
程順に配列したものを使用した。The test piece which had been left for 24 hours after the Fe-B pre-plating was subjected to hot dip aluminum plating. As the hot-dip galvanizing apparatus, a sample preparation chamber, an image furnace whose atmosphere and heating conditions can be freely adjusted, and a pot arranged in the order of steps were used.
【００３２】溶融Ａｌめっき浴に導入される前の試験片
が通過する水素−窒素雰囲気は、露点−４０〜−４５℃
の範囲に維持し、水素含有量を５〜７５体積％の範囲で
変化させた。そして、最高到達温度が７００℃，溶融Ａ
ｌめっき浴に導入される直前の温度が６８０℃となるよ
うに設定し、試験片が水素−窒素雰囲気を通過する時間
が８０秒間となるように試験片を搬送した。The hydrogen-nitrogen atmosphere through which the test piece passes before being introduced into the molten Al plating bath has a dew point of -40 to -45 ° C.
And the hydrogen content was changed in the range of 5-75% by volume. And, the highest temperature reaches 700 ℃, melting A
The temperature of the test piece was set to 680 ° C. immediately before it was introduced into the plating bath, and the test piece was conveyed such that the time for the test piece to pass through the hydrogen-nitrogen atmosphere was 80 seconds.
【００３３】溶融アルミめっき浴は、Ａｌ−５重量％Ｓ
ｉ合金を溶融して６６０℃に保持したものを用意した。
この溶融アルミめっき浴に対する試験片の浸漬時間を２
秒に設定し、溶融アルミめっき層の目付け量を両面で８
０〜１００ｇ／ｍ2 を目標とした。The molten aluminum plating bath is Al-5 wt% S
The i alloy was melted and kept at 660 ° C.
The immersion time of the test piece in this hot dip aluminum bath is 2
Set to seconds and set the unit weight of the molten aluminum plating layer to 8 on both sides.
The target was 0 to 100 g / m 2 .
【００３４】溶融アルミめっき後の試験片に対し、ＪＩ
Ｓ Ｚ２２４８の押曲げ法に準拠した２ｔ，１ｔ及び密
着曲げ試験を行った。そして、溶融アルミめっきされた
試験片の曲げ試験による割れ発生状況を炉内のガス組成
との関係で調べた。また、試験番号３，５，６，８及び
９の試験片に付いては水素濃度を測定し、水素濃度を炉
内のガス組成との関係を調べた。調査結果を表３に示
す。表３における試験番号３，５，６，８及び９の欄に
おける上段は割れ発生状況（評価は表２と同じ）を示
し、下段は水素濃度（単位：ｐｐｍ）を示す。JI was applied to the test piece after hot dip aluminum plating.
A 2t, 1t and contact bending test based on the pressing and bending method of SZ2248 were performed. Then, the state of crack generation in the bending test of the hot-dip aluminized test piece was examined in relation to the gas composition in the furnace. Further, with respect to the test pieces of test numbers 3, 5, 6, 8 and 9, the hydrogen concentration was measured, and the relationship between the hydrogen concentration and the gas composition in the furnace was investigated. The survey results are shown in Table 3. In the columns of test numbers 3, 5, 6, 8 and 9 in Table 3, the upper row shows the crack generation status (evaluation is the same as in Table 2), and the lower row shows the hydrogen concentration (unit: ppm).
【００３５】[0035]
【表３】 [Table 3]
【００３６】表３から明らかなように、雰囲気ガスに含
まれている水素が減少するに従って、溶融アルミめっき
された試験片の曲げ加工性が改善されていることが判
る。また、Ｃｒ及びＭｏの含有量が多くなるほど、母材
自体の靭性が低下して割れ感受性が高くなり、鋼中に僅
かな水素が侵入することによっても割れ易くなることか
らことから、Ｃｒ含有量及びＭｏ含有量が多いステンレ
ス鋼ほど水素濃度の低減が必要であることも判る。As is clear from Table 3, the bending workability of the test piece plated with hot dip aluminum is improved as the hydrogen contained in the atmospheric gas is reduced. Further, as the contents of Cr and Mo increase, the toughness of the base material itself decreases and the cracking susceptibility increases, and it becomes easy to crack even if a small amount of hydrogen penetrates into the steel. It can also be seen that the lower the hydrogen concentration is, the lower the stainless steel content is.
【００３７】炉内の雰囲気を２５体積％Ｈ2 −７５体積
％Ｎ2 の一定したガス組成に保ち、加熱条件及び露点を
変えて試験番号９の試験片に溶融アルミめっきを施し
た。そして、加熱条件及び露点がめっき後の試験片にお
ける曲げ試験結果，水素濃度及び不めっき発生に与える
影響を調べた。なお、不めっきの発生は、めっきされた
試験片の外観を観察することによって判定した。調査結
果を、表４に示す。表４における＊印は、本発明で規定
した範囲を外れていることを示す。The atmosphere in the furnace was kept at a constant gas composition of 25% by volume H 2 -75% by volume N 2 and the heating condition and the dew point were changed, and the test piece of test number 9 was subjected to hot dip aluminum plating. Then, the effects of the heating conditions and the dew point on the bending test result, hydrogen concentration, and non-plating occurrence in the test piece after plating were investigated. The occurrence of non-plating was determined by observing the appearance of the plated test piece. The survey results are shown in Table 4. The asterisk * in Table 4 indicates that it is outside the range specified in the present invention.
【００３８】[0038]
【表４】 [Table 4]
【００３９】表４から明らかなように、浴温６６０℃の
溶融アルミめっき浴に導入される前に加熱される試験片
の最高到達温度を７００℃（＝６６０℃＋４０℃）、導
入直前の温度を６８０℃（＝６６０℃＋２０℃）に設定
し、雰囲気ガスの露点を−４０℃とした本発明例では、
溶融アルミめっきされた試験片の水素濃度が低く、密着
曲げ試験でも割れが検出されなかった。また、試験片表
面に形成された溶融アルミめっき層は、不めっき等の欠
陥がない健全なものであった。As is clear from Table 4, the highest temperature reached of the test piece heated before being introduced into the molten aluminum plating bath having a bath temperature of 660 ° C. was 700 ° C. (= 660 ° C. + 40 ° C.), the temperature just before the introduction. Is set to 680 ° C. (= 660 ° C. + 20 ° C.), and the dew point of the atmospheric gas is −40 ° C.
The hydrogen concentration of the test piece plated with hot dip aluminum was low, and no crack was detected in the contact bending test. Further, the hot dip aluminum plating layer formed on the surface of the test piece was sound without any defects such as non-plating.
【００４０】これに対し、溶融アルミめっき浴に導入さ
れる前に試験片を過度に加熱した比較例では、めっき後
の試験片における水素濃度が高く、密着曲げ試験で割れ
が発生した。これは、過熱によって雰囲気ガスから試験
片への水素吸収が活発に行われた証拠である。また、過
熱温度が低過ぎる比較例では、水素の吸収が少ないもの
の、不めっきの発生が顕著になった。これは、めっき浴
に導入された直後の試験片及び周辺のめっき金属に急激
な温度変動が生じたことに起因する。更に、露点が−２
５℃と湿潤雰囲気中で試験片を加熱した比較例では、密
着曲げ試験で本発明例と同等の耐割れ性を示すものの、
形成された溶融アルミめっき層に不めっきがみられた。On the other hand, in the comparative example in which the test piece was excessively heated before being introduced into the molten aluminum plating bath, the hydrogen content in the test piece after plating was high, and cracking occurred in the contact bending test. This is evidence that hydrogen was actively absorbed from the atmospheric gas into the test piece due to overheating. Further, in the comparative example in which the overheating temperature was too low, although the absorption of hydrogen was small, the occurrence of non-plating became remarkable. This is because the temperature of the test piece immediately after being introduced into the plating bath and the surrounding plated metal fluctuated sharply. Furthermore, the dew point is -2
In the comparative example in which the test piece was heated in a humid atmosphere at 5 ° C., although a crack resistance equivalent to that of the inventive example was shown in the contact bending test,
Non-plating was observed in the formed hot dip aluminum plating layer.
【００４１】[0041]
【発明の効果】以上に説明したように、本発明によると
き、不めっき等の欠陥を発生させることなく、加工性に
優れた溶融Ａｌめっき高Ｃｒフェライト系ステンレス鋼
板を製造することができる。得られた製品は、高度の加
工を施しても母材の割れ，めっき層の亀裂，剥離等の欠
陥を生じることがないため、用途に対応した各種形状に
加工することができる。しかも、母材及びめっき層の相
乗的な作用によって極めて優れた耐食性を呈し、過酷な
腐食雰囲気に晒される構造材料，部品等として広範な分
野で使用される。As described above, according to the present invention, it is possible to produce a hot-dip Al-plated high Cr ferritic stainless steel sheet having excellent workability without causing defects such as non-plating. The obtained product does not cause defects such as cracks in the base material, cracks in the plating layer, and peeling even if it is subjected to a high degree of processing, and thus can be processed into various shapes suitable for the intended use. Moreover, it exhibits extremely excellent corrosion resistance due to the synergistic action of the base material and the plating layer, and is used in a wide range of fields as structural materials and parts exposed to a severe corrosive atmosphere.
【図１】 Ｆｅ−Ｂプレめっきされた高Ｃｒフェライト
系ステンレス鋼の水素濃度とプレめっき後の放置期間と
の関係を示したグラフFIG. 1 is a graph showing the relationship between the hydrogen concentration of Fe-B pre-plated high Cr ferritic stainless steel and the standing period after pre-plating.
Claims (3)
ライト系ステンレス鋼板をプレめっきして２４時間以上
放置した後、水素ガス濃度が５０体積％以下で露点が−
３０℃以下の水素−窒素雰囲気中で加熱し、引き続いて
溶融アルミ浴又は溶融アルミ合金浴に導入することを特
徴とする高Ｃｒフェライト系ステンレス鋼板の溶融アル
ミめっき方法。1. A ferritic stainless steel sheet containing 16 to 35% by weight of Cr is pre-plated and allowed to stand for 24 hours or more, after which the hydrogen gas concentration is 50% by volume or less and the dew point is −.
A hot-dip aluminum plating method for a high Cr ferritic stainless steel sheet, which comprises heating in a hydrogen-nitrogen atmosphere at 30 ° C or lower and subsequently introducing it into a hot-dip aluminum bath or hot-dip aluminum alloy bath.
レめっきであることを特徴とする高Ｃｒフェライト系ス
テンレス鋼板の溶融アルミめっき方法。2. A hot-dip aluminum plating method for a high Cr ferritic stainless steel sheet, wherein the pre-plating according to claim 1 is Fe-B pre-plating.
ンレス鋼は、溶融アルミ浴又は溶融アルミ合金浴の温度
Ｔを基準として、加熱中の最高到達温度がＴ＋１００℃
以下、溶融アルミ浴又は溶融アルミ合金浴に導入される
直前の温度がＴ±５０℃に維持されることを特徴とする
高Ｃｒフェライト系ステンレス鋼板の溶融アルミめっき
方法。3. The ferritic stainless steel according to claim 1 or 2, wherein the maximum attainable temperature during heating is T + 100 ° C. based on the temperature T of the molten aluminum bath or molten aluminum alloy bath.
Hereinafter, a method for hot dip aluminum plating of a high Cr ferritic stainless steel sheet, characterized in that the temperature immediately before being introduced into the hot dip aluminum bath or the hot aluminum alloy bath is maintained at T ± 50 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3150392A JPH05195182A (en) | 1992-01-22 | 1992-01-22 | Hot-dip aluminizing method of high cr ferritic stainless steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3150392A JPH05195182A (en) | 1992-01-22 | 1992-01-22 | Hot-dip aluminizing method of high cr ferritic stainless steel sheet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05195182A true JPH05195182A (en) | 1993-08-03 |
Family
ID=12333037
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3150392A Withdrawn JPH05195182A (en) | 1992-01-22 | 1992-01-22 | Hot-dip aluminizing method of high cr ferritic stainless steel sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05195182A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009033066A (en) * | 2007-07-30 | 2009-02-12 | Nisshin Steel Co Ltd | Method for installing solar power generating module on building |
| JP2011249849A (en) * | 2011-08-31 | 2011-12-08 | Nisshin Steel Co Ltd | Photovoltaic module installation rack |
| KR101105986B1 (en) * | 2004-04-29 | 2012-01-18 | 포스코강판 주식회사 | Process for hot dip aluminum coated stainless steel through the control of gas partial pressure |
-
1992
- 1992-01-22 JP JP3150392A patent/JPH05195182A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101105986B1 (en) * | 2004-04-29 | 2012-01-18 | 포스코강판 주식회사 | Process for hot dip aluminum coated stainless steel through the control of gas partial pressure |
| JP2009033066A (en) * | 2007-07-30 | 2009-02-12 | Nisshin Steel Co Ltd | Method for installing solar power generating module on building |
| JP2011249849A (en) * | 2011-08-31 | 2011-12-08 | Nisshin Steel Co Ltd | Photovoltaic module installation rack |
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