JP3587885B2

JP3587885B2 - Manufacturing method of hot-dip galvanized steel sheet for corrosion-resistant refractory structure

Info

Publication number: JP3587885B2
Application number: JP17766894A
Authority: JP
Inventors: 徹藤田; 征一浜中; 照夫田中
Original assignee: Nisshin Steel Co Ltd
Current assignee: Nippon Steel Nisshin Co Ltd
Priority date: 1993-07-07
Filing date: 1994-07-06
Publication date: 2004-11-10
Anticipated expiration: 2019-11-10
Also published as: JPH0770647A

Description

【０００１】
【産業上の利用分野】
本発明は、建築分野等における構造物として使用され、構造物の高強度化を可能とし、火災時においても十分な強度を維持する耐食性に優れた溶融亜鉛めっき鋼板を製造する方法に関する。
【０００２】
【従来の技術】
鉄骨構造物に使用されるＪＩＳ規格鋼材として、一般構造用圧延鋼板（ＪＩＳＧ３１０１），溶接構造用圧延鋼板（Ｇ３１０６），溶接構造用耐候性熱間圧延鋼材（Ｇ３１１４）等がある。また、構造用軽量形鋼や構造用鋼管等の素材として、熱間圧延軟質鋼板（Ｇ３１３２），溶融亜鉛めっき鋼板（Ｇ３３０２）等が広く使用されている。
構造物として使用される鋼材には、火災時における安全性を確保する上から鋼材温度が３５０℃を超えないように耐火被覆を施すことが義務付けられている。しかし、十分な高温強度が確保される場合、無被覆で鋼材を使用することも可能となる。そこで、高温においても高い耐力を呈する鋼材の使用が種々検討されている。
【０００３】
鋼材の高温強度は、古くから調査・研究されているものであり、ボイラー用鋼板，圧力容器用鋼板等に関し規格化されている。この種の鋼材は、ボイラー，圧力容器等として高温で数万時間といった長時間使用の場合の強度、すなわちクリープ強度の高い鋼材である。これに対し、本発明で問題としている強度は、火災時の数時間以内の強度である。この点、従来の高温用鋼板は、常温における強度が高過ぎ、冷間加工性、更に溶接性が構造用鋼板に比較して大幅に劣る。そのため、ボイラー用鋼板，圧力容器用鋼板等は、構造用鋼板には適さない。
構造用鋼板では、火災時の数時間の間に高温雰囲気に構造物が曝されたとき、必要な構造強度をもつことが要求される。
高温強度を高めた建築用の鋼板として、特開平４−１３６１１８号公報，特開平４−１０２８０２号公報等では、Ｍｏ及びＶを添加している。ＭｏやＶは、火災時に鋼材が高温に曝される過程で微細な炭化物として析出し、必要な高温耐力を鋼材に与える。しかし、高価なＭｏを合金元素とすることから製造コストが上昇する。また、鋼板の長寿命化に対して耐食性が不十分である。
【０００４】
【発明が解決しようとする課題】
本発明の目的は、高温特性，軽量鉄骨等への成形加工性，母材の耐食性に優れ、更に製鋼工程〜熱間圧延工程に特別な手段を使用せず、普通鋼に近い鋼組成で、経済的に優れた耐食性耐火構造用溶融亜鉛めっき鋼板の製造方法の提供にある。具体的には、Ｐ，Ｃｕ添加を基本成分とすることで耐食性を向上させるものである。また、Ｃｕは高温時にε−Ｃｕを析出し、高温強度を高める作用をも有することから、Ｍｏ添加量を減らすことが可能となり、製造コストが安価となる。
【０００５】
【課題を解決するための手段】
本発明の耐食性耐火構造用溶融亜鉛めっき鋼板の製造方法は、その目的を達成するため、Ｃ：０．０３〜０．２０重量％，Ｓｉ：０．１重量％以下，Ｍｎ：０．３〜２．０重量％，Ｐ：０．０３〜０．１５重量％，Ｓ：０．０２重量％以下，Ａｌ：０．００５〜０．１重量％，Ｍｏ：０．０５〜１．０重量％，Ｃｕ：０．６〜２．０重量％及びＮｉ：０．３〜２．０重量％を含み、残部が実質的にＦｅからなる組成の鋼に熱間圧延及び酸洗を施した後、連続溶融亜鉛めっき設備で４５０〜７５０℃の温度範囲で加熱還元し、次いで溶融亜鉛めっきを施すことを特徴とする。
使用する鋼は、更にＣｒ：０．０５〜１．０重量％，Ｖ：０．００５〜０．２重量％，Ｗ：０．０１〜１．０重量％，Ｔｉ：０．００５〜０．２重量％，Ｎｂ：０．００５〜０．２重量％及びＢ：０．０００３〜０．００３重量％の１種又は２種以上を含むことができる。
【０００６】
【作用】
本発明者等は、６００℃における鋼板強度及び母材の耐食性に及ぼす化学成分，製造条件等について種々調査・研究した。その結果、普通鋼に近い組成系に規定量のＭｏ，Ｃｕ及びＰを添加するとき、高温強度及び母材耐食性に優れた耐食性耐火構造用溶融亜鉛めっき鋼板が得られることを見い出した。得られた鋼板は、室温の降伏強度に対する６００℃の降伏強度の比が０．６以上であり、高温雰囲気に曝されても高温強度を大きく低下することがない。特に、含有量が厳格に規定されたＣｕは、耐食性の向上に有効であるばかりでなく、高温時に鋼中にε−Ｃｕとして析出し、高温強度を上昇させる。その結果、Ｍｏ添加量を減少することができ、製造コストが低減する。高温強度及び母材耐食性は、Ｃｒ，Ｖ，Ｗ，Ｔｉ，Ｎｂ及びＢの１種又は２種以上を添加することによって更に改善される。
【０００７】
以下、本発明で使用される鋼材の合金元素及びその含有量を説明する。
Ｃ：０．０３〜０．２０重量％
鋼材に必要な強度を付与する上で有効な合金元素であり、０．０３重量％以上の含有量が必要である。しかし、０．２０重量％を超える多量のＣを含有させると、加工性，溶接性，靭性等が劣化する。
Ｓｉ：０．１重量％以下
Ｓｉは、強度向上元素として有効であるが、本発明の目的である高温強度及び耐食性の向上効果は比較的小さいので０．１０重量％以下に限定した。
Ｍｎ：０．３〜２．０重量％
鋼材の高強度化に有効な合金元素であり、０．３０重量％以上で効果を発揮する。しかし、２．０重量％を超える多量のＭｎ含有は、加工性を劣化させる。
【０００８】
Ｐ：０．０３〜０．１５重量％
鋼材の強度向上に有効な合金元素である。また、Ｃｕと複合して添加するとき、耐食性の改善に寄与する。このような効果を得るためには、０．０３重量％以上のＰを含有させることが必要である。しかし、０．１５重量％を超えて多量のＰを含有させると、脆化を助長させる。
Ｓ：０．０２重量％以下
母材鋼にとって本質的に有害な元素であり、低ければ低いほど好ましい。Ｓ含有量は、本発明の鋼では０．０２重量％まで許容される。
Ａｌ：０．００５〜０．１重量％
脱酸剤として添加される元素であるが、鋼中のＮをＡｌＮとして固定する作用も呈する。このためには、０．００５重量％以上が必要である。しかし、Ａｌ含有量が０．１重量％を超えると、介在物が増大し、加工性及び表面品質を劣化させる。
【０００９】
Ｍｏ：０．０５〜１．０重量％
本発明鋼において重要な合金元素であり、鋼中に固溶し或いは炭化物を析出することにより、鋼材の高温強度を向上させる。このような効果は、Ｍｏ含有量０．０５重量％以上で顕著になる。しかし、１．０重量％を超える多量のＭｏを含有させても、高価なＭｏ含有量の増加に見合った効果が得られず、却って高強度化に起因した加工性の劣化を招く。
Ｃｕ：０．６〜２．０重量％
本発明鋼における重要な合金元素であり、鋼中に固溶し或いはε−Ｃｕとして微細に析出し、鋼材の高温強度を向上させる。また、Ｐとの相互作用によって緻密な腐食生成物を形成し、耐食性も向上する。高温強度を向上させる効果は、Ｃｕ含有量０．６重量％以上で顕著になり、２．０重量％で飽和する。また、２．０重量％を超えて多量のＣｕを含有させると、熱間圧延時に脆化を生じ易く、高温割れ等の原因となる。
【００１０】
Ｎｉ：０．３〜２．０重量％
Ｃｕ添加に起因した熱間脆性の低下防止にも有効である。この点で、Ｎｉの含有量は、Ｃｕ含有量とほぼ同量、すなわち０．３０〜２．０重量％の範囲に設定する。
Ｃｒ：０．０５〜１．０重量％
母材の耐食性を改善するために必要に応じ添加される合金元素であり、高温強度を向上させる。このような効果は、０．０５重量％以上のＣｒを含有させるとき顕著になる。しかし、１．０重量％を超える多量のＣｒを含有させても、Ｃｒの増量に見合った効果の改善がみられない。
Ｖ，Ｔｉ，Ｎｂ：０．００５〜０．２重量％
室温強度及び高温強度を向上させる上で有効な合金元素であり、それぞれ含有量０．００５重量％以上で顕著な効果が得られる。しかし、０．２重量％を超えて含有させても、増量に見合った効果が得られない。そこで、Ｖ，Ｔｉ，Ｎｂ等を添加する場合には、それぞれの含有量を０．００５〜０．２重量％の範囲に定める。
【００１１】
Ｗ：０．０１〜１．０重量％
必要に応じて添加される合金元素であり、鋼中に固溶し或いは炭化物を析出し、鋼材の高温強度を向上させる効果を発揮する。Ｗ添加の効果は、０．０１
重量％以上で顕著に現れ、１．０重量％で飽和する。
Ｂ：０．０００３〜０．００３重量％
焼入れ性を向上させると共に粒界を強化することから、必要に応じて添加される合金元素である。Ｂ添加の効果は、０．０００３重量％以上で顕著になり
、０．００３重量％で飽和する。
【００１２】
以上の成分・組成をもつ鋼を通常の工程でスラブにした後、熱間圧延によって所定板厚の鋼板とする。熱間圧延は、加熱温度１０５０〜１２５０℃，仕上げ温度８００〜９５０℃及び巻取り温度５００〜７００℃の条件で行うことが好ましい。
熱延鋼板は、酸洗後、連続溶融めっき設備に導入される。連続溶融めっき設備では、還元性雰囲気中で表面温度４５０〜７５０℃に熱延鋼板が加熱され、鋼板表面にある異物や酸化皮膜等が除去される。
加熱温度は、鋼板表面の活性度を高め、めっき金属に対する濡れ性を改善する上で、表面温度４５０〜７５０℃に定められる。４５０℃未満の加熱温度では、活性化が不十分となり、溶融亜鉛めっき層の密着性が低下する。逆に、７５０℃を超える加熱温度では、めっき性の改善に寄与する効果が飽和し、却って過大な熱エネルギーを必要とすることから生産効率を損なう。
【００１３】
【実施例】
表１に示した組成の鋼を溶製し、常法に従ってスラブにした後、熱間圧延して板厚３．２ｍｍの熱延鋼板を得た。表１におけるＡグループは、本発明に従った鋼を示す。Ｂグループは、何れもＣｕを含有していない比較鋼を示す。
熱延鋼板を酸洗した後、連続溶融めっき設備で目付け量４５ｇ／ｍ^２の溶融亜鉛めっきを施した。熱間圧延及び溶融亜鉛めっきの条件を、表２に示す。
【００１４】
【表１】

【００１５】
【表２】

【００１６】
溶融亜鉛めっき鋼板からＪＩＳＺ２２０１に規定する５号試験片を切り出し、室温における引張り試験に供した。また、ＪＩＳＧ０５６７に準拠した高温引張り試験片を作成し、試験片を６００℃に１５分保持した後、引張り強さ及び降伏強度を測定した。高温強度の指標としては、室温での降伏強度に対する６００℃での降伏強度の比を採用した。
耐食性は、腐食試験後の最大侵食深さで評価した。すなわち、溶融亜鉛めっき鋼板から切り出された７０ｍｍ×１５０ｍｍの試験片を、図１に示した条件の塩水噴霧，乾燥及び湿潤（３サイクル／日）の複合サイクル腐食試験に供した。この腐食試験を２４０サイクル（８０日）繰り返し、腐食生成物を除去した上で最大侵食深さを測定した。
調査結果を示す表３から明らかなように、試験番号Ｂ１の試験片は、室温で優れた強度及び延性を示すものの、６００℃における降伏強度の低下が大きく、降伏強度比が０．６未満となっている。すなわち、高温強度に劣る材料である。また、最大侵食深さも１．０４ｍｍと深く、耐食性にも劣っている。
【００１７】
【表３】

【００１８】
試験番号Ｂ２及びＢ３の試験片は、室温における延性の低下がみられず、降伏強度比０．６以上の要求を満足し、６００℃における降伏強度の低下が小さいことから、高温強度に優れた材料といえる。しかし、最大侵食深さがＢ２では０．８８ｍｍ，Ｂ３では０．８２ｍｍと深く、耐食性に劣っている。
これに対し、本発明に従ったＡグループの試験片は、何れも室温における大きな延性の低下がみられず、６００℃における降伏強度においても優れた特性を示している。また、最大侵食深さもＢ１〜Ｂ３に比較して浅く、耐食性に優れていることが判る。特に、Ｃｒ，Ｖ，Ｗを複合添加した試験片Ａ８及びＮｂ，Ｂを複合添加した試験片Ａ１３は、それぞれ降伏強度比において０．７０及び０．７４、最大侵食深さにおいて０．５３ｍｍ及び０．４８ｍｍと示されているように、高温特性及び耐食性の何れにおいても優れた特性を備えている。
【００１９】
【発明の効果】
以上に説明したように、本発明においては、製鋼工程や熱間圧延工程に特別な手段を必要とすることなく、普通鋼に近い組成で経済的に優れた耐食性耐火構造用溶融亜鉛めっき鋼板が製造される。得られためっき鋼板は、高温特性，耐食性，成形加工性等に優れていることから、広範な分野において耐火構造物材料として使用される。
【図面の簡単な説明】
【図１】本発明実施例で採用した複合サイクル腐食試験[0001]
[Industrial applications]
The present invention relates to a method for producing a hot-dip galvanized steel sheet which is used as a structure in the field of construction and the like, enables high strength of the structure and maintains sufficient strength even in a fire, and has excellent corrosion resistance.
[0002]
[Prior art]
Examples of JIS standard steel materials used for steel structures include rolled steel plates for general structures (JIS G3101), rolled steel plates for welded structures (G3106), and weather-resistant hot-rolled steel materials for welded structures (G3114). Further, as a material for a structural lightweight section steel or a structural steel pipe, a hot-rolled soft steel plate (G3132), a hot-dip galvanized steel plate (G3302), and the like are widely used.
Steel materials used as structures are required to be provided with a fire-resistant coating so that the steel material temperature does not exceed 350 ° C. in order to ensure safety in the event of a fire. However, when sufficient high-temperature strength is secured, it is possible to use a steel material without coating. Thus, various studies have been made on the use of steel materials that exhibit high proof stress even at high temperatures.
[0003]
The high-temperature strength of steel has been investigated and studied since ancient times, and is standardized for steel plates for boilers, steel plates for pressure vessels, and the like. This type of steel material has high strength when used as a boiler, pressure vessel or the like at high temperatures for a long period of time of tens of thousands of hours, that is, a steel material having high creep strength. On the other hand, the strength of the present invention is the strength within several hours at the time of fire. In this respect, the conventional high-temperature steel sheet has too high strength at room temperature, and is significantly inferior in cold workability and weldability to structural steel sheets. Therefore, steel plates for boilers, steel plates for pressure vessels, and the like are not suitable for structural steel plates.
Structural steel sheets are required to have necessary structural strength when the structure is exposed to a high-temperature atmosphere during several hours during a fire.
In Japanese Patent Application Laid-Open Nos. 4-136118 and 4-102802, Mo and V are added as steel plates for building with increased high-temperature strength. Mo and V precipitate as fine carbides in the process of exposing the steel material to a high temperature in the event of a fire, and give the steel material the required high-temperature strength. However, since expensive Mo is used as an alloy element, the manufacturing cost increases. Further, the corrosion resistance is insufficient for extending the life of the steel sheet.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a steel composition close to ordinary steel without using any special means in the steelmaking process to hot rolling process, having excellent high-temperature characteristics, workability in forming into a lightweight steel frame and the like, and corrosion resistance of a base material. An object of the present invention is to provide a method of manufacturing a galvanized steel sheet for a corrosion-resistant fire-resistant structure that is economically excellent. Specifically, the corrosion resistance is improved by adding P and Cu as basic components. Further, since Cu also precipitates ε-Cu at a high temperature and also has an effect of increasing the high-temperature strength, the amount of Mo added can be reduced, and the production cost is reduced.
[0005]
[Means for Solving the Problems]
In order to achieve the object, the method for producing a hot-dip galvanized steel sheet for a corrosion-resistant refractory structure according to the present invention comprises C: 0.03 to 0.20% by weight, Si: 0.1% by weight or less, and Mn: 0.3 to 0.3%. 2.0 wt%, P: 0.03-0.15 wt%, S: 0.02 wt% or less, Al: 0.005-0.1 wt%, Mo: 0.05-1.0 wt% , Cu: 0.6 to 2.0 wt% and Ni: 0.3 to 2.0 wt% only containing, after being subjected to hot rolling and pickling the steel composition the balance being substantially Fe And reducing by heating in a continuous hot-dip galvanizing facility in a temperature range of 450 to 750 ° C., and then performing hot-dip galvanizing.
The steel to be used further contains Cr: 0.05 to 1.0% by weight, V: 0.005 to 0.2% by weight, W: 0.01 to 1.0% by weight, and Ti: 0.005 to 0. One or more of 2% by weight, 0.005 to 0.2% by weight of Nb and 0.0003 to 0.003% by weight of B can be contained.
[0006]
[Action]
The present inventors have conducted various investigations and researches on chemical components, production conditions, and the like that affect the strength of a steel sheet at 600 ° C. and the corrosion resistance of a base material. As a result, it has been found that when a specified amount of Mo, Cu and P is added to a composition system close to ordinary steel, a hot-dip galvanized steel sheet for a corrosion-resistant refractory structure excellent in high-temperature strength and base metal corrosion resistance can be obtained. The ratio of the yield strength at 600 ° C. to the yield strength at room temperature of the obtained steel sheet is 0.6 or more, and the high-temperature strength does not significantly decrease even when exposed to a high-temperature atmosphere. In particular, Cu whose content is strictly defined is not only effective for improving corrosion resistance, but also precipitates as ε-Cu in steel at high temperatures to increase high-temperature strength. As a result, the amount of Mo added can be reduced, and the manufacturing cost is reduced. High temperature strength and base metal corrosion resistance are further improved by adding one or more of Cr, V, W, Ti, Nb and B.
[0007]
Hereinafter, alloying elements of steel materials used in the present invention and their contents will be described.
C: 0.03 to 0.20% by weight
It is an effective alloying element for imparting necessary strength to steel, and requires a content of 0.03% by weight or more. However, when a large amount of C exceeding 0.20% by weight is contained, workability, weldability, toughness and the like are deteriorated.
Si: 0.1% by weight or less Si is effective as a strength improving element, but is limited to 0.10% by weight or less because the effects of improving high temperature strength and corrosion resistance, which are objects of the present invention, are relatively small.
Mn: 0.3 to 2.0% by weight
It is an effective alloying element for increasing the strength of steel, and exhibits an effect at 0.30% by weight or more. However, a large content of Mn exceeding 2.0% by weight deteriorates workability.
[0008]
P: 0.03 to 0.15% by weight
It is an effective alloy element for improving the strength of steel. Further, when added in combination with Cu, it contributes to improvement of corrosion resistance. In order to obtain such an effect, it is necessary to contain 0.03% by weight or more of P. However, when a large amount of P is contained in excess of 0.15% by weight, embrittlement is promoted.
S: 0.02% by weight or less S is an essentially harmful element for base steel, and the lower the better, the better. The S content is allowed up to 0.02% by weight in the steel according to the invention.
Al: 0.005 to 0.1% by weight
Although it is an element added as a deoxidizing agent, it also has an effect of fixing N in steel as AlN. For this purpose, 0.005% by weight or more is required. However, if the Al content exceeds 0.1% by weight, inclusions increase and workability and surface quality deteriorate.
[0009]
Mo: 0.05 to 1.0% by weight
It is an important alloying element in the steel of the present invention, and improves the high-temperature strength of a steel material by forming a solid solution or precipitating carbide in the steel. Such effects become remarkable when the Mo content is 0.05% by weight or more. However, even if Mo is contained in a large amount exceeding 1.0% by weight, the effect corresponding to the increase in the expensive Mo content cannot be obtained, and rather the workability is deteriorated due to the high strength.
Cu: 0.6 to 2.0% by weight
It is an important alloying element in the steel of the present invention, and forms a solid solution in the steel or precipitates finely as ε-Cu to improve the high-temperature strength of the steel material. Further, a dense corrosion product is formed by the interaction with P, and the corrosion resistance is also improved. The effect of improving the high-temperature strength becomes remarkable when the Cu content is 0.6% by weight or more, and saturates at 2.0% by weight. Further, if a large amount of Cu is contained in excess of 2.0% by weight, embrittlement is likely to occur during hot rolling, which causes high-temperature cracking and the like.
[0010]
Ni: 0.3 to 2.0% by weight
It is also effective in preventing reduction in hot brittleness due to the addition of Cu. At this point, the Ni content is set to be substantially the same as the Cu content, that is, in the range of 0.30 to 2.0% by weight.
Cr: 0.05 to 1.0% by weight
It is an alloying element added as needed to improve the corrosion resistance of the base material, and improves the high-temperature strength. Such an effect becomes remarkable when 0.05% by weight or more of Cr is contained. However, even when a large amount of Cr exceeding 1.0% by weight is contained, the effect corresponding to the increase in Cr is not improved.
V, Ti, Nb: 0.005 to 0.2% by weight
It is an effective alloy element for improving the room temperature strength and the high temperature strength. A remarkable effect can be obtained when the content is 0.005% by weight or more, respectively. However, even if the content exceeds 0.2% by weight, an effect commensurate with the increased amount cannot be obtained. Therefore, when V, Ti, Nb, etc. are added, their contents are set in the range of 0.005 to 0.2% by weight.
[0011]
W: 0.01 to 1.0% by weight
It is an alloy element added as needed, and exhibits an effect of improving the high-temperature strength of a steel material by forming a solid solution or precipitating carbide in steel. The effect of W addition is 0.01
It appears remarkably when it is equal to or more than 10% by weight and saturates at 1.0% by weight.
B: 0.0003 to 0.003% by weight
It is an alloying element that is added as necessary because it improves hardenability and strengthens grain boundaries. The effect of the addition of B becomes significant at 0.0003% by weight or more, and saturates at 0.003% by weight.
[0012]
After the steel having the above-described components and compositions is formed into a slab by a normal process, a steel sheet having a predetermined thickness is formed by hot rolling. The hot rolling is preferably performed under the conditions of a heating temperature of 1050 to 1250C, a finishing temperature of 800 to 950C, and a winding temperature of 500 to 700C.
After pickling, the hot-rolled steel sheet is introduced into a continuous hot-dip plating facility. In the continuous hot-dip plating equipment, a hot-rolled steel sheet is heated to a surface temperature of 450 to 750 ° C. in a reducing atmosphere to remove foreign substances and oxide films on the steel sheet surface.
The heating temperature is set at a surface temperature of 450 to 750 ° C. in order to increase the activity of the steel sheet surface and improve the wettability to the plated metal. If the heating temperature is lower than 450 ° C., the activation becomes insufficient, and the adhesion of the hot-dip galvanized layer is reduced. Conversely, at a heating temperature exceeding 750 ° C., the effect of contributing to the improvement of the plating property is saturated, and rather excessive heat energy is required, thereby impairing the production efficiency.
[0013]
【Example】
A steel having the composition shown in Table 1 was melted, formed into a slab according to a conventional method, and then hot-rolled to obtain a hot-rolled steel sheet having a thickness of 3.2 mm. Group A in Table 1 indicates steel according to the invention. Group B shows comparative steels each containing no Cu.
After pickling the hot-rolled steel sheet, hot-dip galvanizing was applied with a basis weight of 45 g / m ^{2 in} a continuous hot-dip plating facility. Table 2 shows the conditions of hot rolling and hot dip galvanizing.
[0014]
[Table 1]

[0015]
[Table 2]

[0016]
A No. 5 test piece specified in JIS Z2201 was cut out from the hot-dip galvanized steel sheet and subjected to a tensile test at room temperature. Further, a high-temperature tensile test piece in accordance with JIS G0567 was prepared, and after maintaining the test piece at 600 ° C. for 15 minutes, the tensile strength and the yield strength were measured. As an index of the high temperature strength, the ratio of the yield strength at 600 ° C. to the yield strength at room temperature was adopted.
The corrosion resistance was evaluated by the maximum erosion depth after the corrosion test. That is, a 70 mm × 150 mm test piece cut out from a hot-dip galvanized steel sheet was subjected to a combined cycle corrosion test of salt spray, drying and wetness (3 cycles / day) under the conditions shown in FIG. This corrosion test was repeated for 240 cycles (80 days), and the maximum erosion depth was measured after removing corrosion products.
As is clear from Table 3 showing the inspection results, although the test piece of Test No. B1 shows excellent strength and ductility at room temperature, the yield strength at 600 ° C has a large decrease, and the yield strength ratio is less than 0.6. Has become. That is, the material is inferior in high-temperature strength. Further, the maximum erosion depth is as deep as 1.04 mm, and the corrosion resistance is poor.
[0017]
[Table 3]

[0018]
The test pieces of Test Nos. B2 and B3 did not show a decrease in ductility at room temperature, satisfied the requirement of a yield strength ratio of 0.6 or more, and were excellent in high-temperature strength because the decrease in yield strength at 600 ° C. was small. It can be said that it is a material. However, the maximum erosion depth is as deep as 0.88 mm for B2 and 0.82 mm for B3, and is inferior in corrosion resistance.
On the other hand, the test pieces of Group A according to the present invention did not show any significant decrease in ductility at room temperature, and exhibited excellent properties in yield strength at 600 ° C. Also, the maximum erosion depth is shallower than B1 to B3, which indicates that the erosion resistance is excellent. In particular, the test piece A8 to which Cr, V, and W were added in combination and the test piece A13 to which Nb and B were added in combination have a yield strength ratio of 0.70 and 0.74 and a maximum pit depth of 0.53 mm and 0, respectively. As shown by .48 mm, it has excellent characteristics in both high-temperature characteristics and corrosion resistance.
[0019]
【The invention's effect】
As described above, in the present invention, a hot-dip galvanized steel sheet for a corrosion-resistant refractory structure that is economically excellent in composition close to ordinary steel without requiring any special means in the steelmaking process or hot rolling process. Manufactured. The resulting plated steel sheet has excellent high-temperature properties, corrosion resistance, formability, and the like, and is therefore used as a refractory structural material in a wide range of fields.
[Brief description of the drawings]
FIG. 1 shows a combined cycle corrosion test employed in an embodiment of the present invention.

Claims

C: 0.03 to 0.20% by weight, Si: 0.1% by weight or less, Mn: 0.3 to 2.0% by weight, P: 0.03 to 0.15% by weight, S: 0.02 % By weight, Al: 0.005 to 0.1% by weight, Mo: 0.05 to 1.0% by weight, Cu: 0.6 to 2.0% by weight, and Ni: 0.3 to 2.0% by weight. % only contains, after the balance has been subjected to hot rolling and pickling the steel composition consisting essentially Fe, and heated and reduced in a temperature range of 450 to 750 ° C. in a continuous galvanizing line, followed by galvanizing A method for producing a hot-dip galvanized steel sheet for a corrosion-resistant refractory structure, the method comprising:

C: 0.03 to 0.20% by weight, Si: 0.1% by weight or less, Mn: 0.3 to 2.0% by weight, P: 0.03 to 0.15% by weight, S: 0.02 % By weight, Al: 0.005 to 0.1% by weight, Mo: 0.05 to 1.0% by weight, Cu: 0.6 to 2.0% by weight, and Ni: 0.3 to 2.0% by weight. %: Cr: 0.05 to 1.0% by weight, V: 0.005 to 0.2% by weight, W: 0.01 to 1.0% by weight, Ti: 0.005 to 0.2% wt%, Nb: 0.005 to 0.2 wt% and B: 0.0003 to 0.003 wt% observed including one or more of the heat in the steel composition the balance being substantially Fe After hot-rolling and pickling, it is heated and reduced in a continuous hot-dip galvanizing facility at a temperature in the range of 450 to 750 ° C., and then hot-dip galvanized. Manufacturing method of hot-dip galvanized steel sheet.