JPH11256307A - Weather resistant steel and its production - Google Patents
Weather resistant steel and its productionInfo
- Publication number
- JPH11256307A JPH11256307A JP37065198A JP37065198A JPH11256307A JP H11256307 A JPH11256307 A JP H11256307A JP 37065198 A JP37065198 A JP 37065198A JP 37065198 A JP37065198 A JP 37065198A JP H11256307 A JPH11256307 A JP H11256307A
- Authority
- JP
- Japan
- Prior art keywords
- rust
- steel
- temperature
- steel material
- dew point
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Chemical Treatment Of Metals (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、耐候性鋼材に係
り、鋼材表面に耐候性安定さびを早期に形成させ、流れ
さびの発生を防止した耐候性鋼材の製造方法に関する。
本発明における鋼材には、厚鋼板、薄鋼板、棒鋼、形鋼
を含むものとする。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weather-resistant steel material, and more particularly to a method for producing a weather-resistant steel material in which a weather-resistant stable rust is formed on the surface of a steel material at an early stage to prevent occurrence of flow rust.
The steel material in the present invention includes a thick steel plate, a thin steel plate, a bar steel, and a shaped steel.
【０００２】[0002]
【従来の技術】鋼中にＰ、Cu、Cr、Ni等の合金元素を添
加し大気中における耐食性を向上させた耐候性鋼は、船
舶、タンク等の鋼構造物や橋梁等の鋼建築物に広く利用
されている。耐候性鋼は、屋外において腐食の原因であ
る酸素、水を通しにくい安定さびと呼ばれるさびを数年
で形成し、その後の腐食を抑制している。このため、耐
候性鋼は防錆塗料の塗布が不要であり、いわゆる裸使用
が可能な安価な高耐食性材料である。また、この耐候性
鋼の安定さびは、普通鋼におけるさびに比べ暗褐色であ
り、景観に調和するため最近耐候性鋼の使用が増加して
いる。2. Description of the Related Art Weather-resistant steel in which alloy elements such as P, Cu, Cr and Ni are added to steel to improve corrosion resistance in the atmosphere is used for steel structures such as ships and tanks and steel buildings such as bridges. Widely used for Weather-resistant steel forms a rust called stable rust, which is hard to penetrate oxygen and water, which cause corrosion outdoors, in a few years, and suppresses subsequent corrosion. For this reason, the weather-resistant steel does not need to be coated with a rust-preventive paint, and is a so-called inexpensive and highly corrosion-resistant material that can be used naked. The stable rust of the weather-resistant steel is dark brown compared to the rust of ordinary steel, and the use of weather-resistant steel has recently been increasing to harmonize with the landscape.
【０００３】しかしながら、耐候性鋼では、安定さびが
形成されるまでに数年という長い年月を要し、その間、
さび汁と呼ばれる流れさびを発生させるため、景観上あ
るいは環境汚染を引き起こし環境上問題があった。さら
に、耐候性鋼は、海岸地帯では飛来する海塩粒子の作用
により安定さびが形成されにくく、腐食の抑制が認めら
れないという問題もあった。However, in the case of weathering steel, it takes several years for stable rust to be formed.
The generation of flow rust called rust soup has caused environmental problems due to causing landscape or environmental pollution. Furthermore, the weather-resistant steel has a problem that stable rust is hardly formed due to the action of sea salt particles flying in the coastal zone, and the suppression of corrosion is not recognized.
【０００４】このような問題に対し、例えば、特開昭49
-11739号公報には、水、腐食液あるいは両者を作用させ
て形成したさびを有する鋼材上に半透性膜を形成させた
耐候性錆層形成鋼材が提案されている。また、特開平1-
142088号公報には、鉄イオンを含む酸性溶液で鋼板表面
を処理したのち、リン酸塩被膜を形成させる耐候性鋼の
表面処理方法が開示されている。To solve such a problem, see, for example,
JP-11739 proposes a weather-resistant rust-layer-forming steel material in which a semipermeable film is formed on a rusted steel material formed by the action of water, a corrosive liquid, or both. Also, JP-A-1-
Japanese Patent No. 142088 discloses a surface treatment method for weather-resistant steel in which a steel sheet surface is treated with an acidic solution containing iron ions, and then a phosphate film is formed.
【０００５】また、特公平7-37672 号公報には、特殊な
組成からなる錆付け処理液で処理した錆付け耐候性鋼板
が開示されている。また、特開平6-136557号公報には、
硫酸クロム水溶液あるいは硫酸銅水溶液を塗布し、水分
乾燥後さらに有機樹脂被覆を行う鋼材の表面処理方法が
提案されている。さらに、特開平8-13158 号公報には、
アルミニウムイオンを含む水溶液を塗布し、水分乾燥後
さらに有機樹脂被膜を形成する鋼材の表面処理方法が提
案されている。Further, Japanese Patent Publication No. 7-37672 discloses a rust-resistant weather-resistant steel sheet treated with a rust-treating solution having a special composition. Also, JP-A-6-136557 discloses that
There has been proposed a surface treatment method for a steel material in which an aqueous solution of chromium sulfate or an aqueous solution of copper sulfate is applied, dried with water, and further coated with an organic resin. Furthermore, JP-A-8-13158 discloses that
There has been proposed a surface treatment method for a steel material in which an aqueous solution containing aluminum ions is applied, and after moisture drying, an organic resin film is further formed.
【０００６】また、特許番号第2572447 号公報には、極
低Siおよび極低Ｓとし、Ni、AlとNbを複合添加し、さら
にAlとCaの複合酸化物を含有させた、海岸で高い耐食性
を有する鋼材が提案されている。また、特開平6-264256
号公報には、鋼材表面が平均結晶粒径200nm 以下の結晶
性粒径を有するさび層で覆われている耐候性に優れた鋼
材が開示されている。[0006] Also, Japanese Patent No. 2572447 discloses high corrosion resistance on the shore where ultra-low Si and ultra-low S are added, a composite oxide of Ni, Al and Nb is added, and a composite oxide of Al and Ca is further contained. Has been proposed. Also, JP-A-6-264256
The publication discloses a steel material excellent in weather resistance in which the surface of the steel material is covered with a rust layer having a crystal grain size of 200 nm or less in average crystal grain size.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、特開昭
49-11739号公報および特公平7-37672 号公報に記載され
た技術では、大気暴露時の腐食は早期に抑制されるが、
その後の暴露で腐食はさらに進行し、流れさびの形成
や、鉄イオンの流出が完全には防止できないうえ、いず
れも薬品を配合した処理液を使用するため、取扱上問題
を残していた。SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open
With the technology described in JP-A-49-11739 and JP-B-7-37672, corrosion during exposure to the atmosphere is suppressed at an early stage,
Corrosion further progressed with subsequent exposure, and the formation of flow rust and the outflow of iron ions could not be completely prevented. In addition, the treatment solution containing chemicals was used, so that handling problems remained.
【０００８】また、特開平1-142088号公報に記載された
技術では、耐候性安定さびが従来より短期間で形成され
るが、初期の被膜が黒色であるため、日向と日陰等暴露
環境の相違によりさびの進行が異なり、色むらが発生し
外観上問題を残していた。さらに特開平6-136557号公報
および特開平8-13158 号公報に記載された技術では、耐
候性さびが短期間で育成されるが、工程が複雑であるう
え使用する表面処理材が高価であるなどの問題を残して
いた。また、特許番号第2572447 号公報に記載された技
術では、複合酸化物を鋼中に均一に分散させるのに多大
の工夫を要するなど複合酸化物の調整が問題であった。In the technique described in Japanese Patent Application Laid-Open No. 1-142088, weather-resistant and stable rust is formed in a shorter period of time than before, but since the initial film is black, it is difficult to expose to sunshine and shade. The rust progressed differently due to the difference, causing color unevenness and leaving a problem in appearance. Further, in the techniques described in JP-A-6-136557 and JP-A-8-13158, weathering rust is grown in a short period of time, but the process is complicated and the surface treatment material used is expensive. And so on. Further, in the technique described in Japanese Patent No. 2572447, there is a problem in adjusting the composite oxide such that a great deal of work is required to uniformly disperse the composite oxide in the steel.
【０００９】また、特開平6-264256号公報に記載された
技術で製造された鋼材では、環境によっては色むらを生
じるうえ、耐候性も不十分であるという問題があった。
本発明は、上記した問題を有利に解決し、流れさびの発
生を防止し、海岸地帯での使用においても耐候性を向上
させる耐候性安定さびを形成した耐候性鋼材、および耐
候性安定さびを、早期に、しかも経済的に安価な方法で
形成できる、鋼材への耐候性安定さびの形成方法および
耐候性鋼材の製造方法を提案することを目的とする。[0009] Further, the steel material manufactured by the technique described in Japanese Patent Application Laid-Open No. 6-264256 has a problem that, depending on the environment, color unevenness occurs and the weather resistance is insufficient.
The present invention advantageously solves the above-mentioned problems, prevents the occurrence of flow rust, improves weatherability even in use in the coastal zone, forms a weather-resistant steel material having a weather-resistant stable rust, and a weather-resistant stable rust. It is an object of the present invention to propose a method for forming a weather-resistant stable rust on a steel material and a method for manufacturing a weather-resistant steel material, which can be formed early and at a low cost economically.
【００１０】[0010]
【課題を解決するための手段】本発明者らは、上記した
課題を達成するため、まず安定さびについての解析を行
った。本発明者らは、田園地帯および海岸地帯で25年以
上暴露された鋼板表面に生成したさびの断面を偏光顕微
鏡下で観察し、田園地帯で生成したさびには、消光した
部分が多いのに対し、海岸地帯で生成したさびには、偏
光し消光した部分がほとんど見い出せないという知見を
得た。また、田園地帯で暴露された鋼板の腐食速度はほ
とんど０に近かったが、海岸地帯で暴露された鋼板の腐
食速度は暴露初期ほど大きくはないが、暴露初期の約1/
3 程度の腐食速度で腐食が進行していた。これらの事実
から、本発明者らは、安定さびの本質は偏光顕微鏡下で
消光した部分として観察されるさびであり、この部分が
腐食因子である酸素、水の地鉄表面への浸透を抑制して
いるものと推察した。Means for Solving the Problems In order to achieve the above object, the present inventors first analyzed stability rust. The present inventors observed under a polarizing microscope the cross section of rust generated on the surface of the steel sheet exposed for more than 25 years in the countryside and the coastal zone, and the rust generated in the countryside had many quenched parts. On the other hand, it was found that rust generated in the coastal zone could hardly find polarized and quenched parts. In addition, the corrosion rate of the steel sheet exposed in the countryside was almost zero, but the corrosion rate of the steel sheet exposed in the coastal area was not so large as in the early exposure, but was about 1 /
Corrosion was progressing at a corrosion rate of about 3. Based on these facts, the present inventors believe that the essence of stable rust is rust observed as a quenched part under a polarizing microscope, and this part suppresses the penetration of oxygen, which is a corrosion factor, and water, into the surface of the iron base. I suspected that.
【００１１】さらに、本発明者らは、田園地帯で15年間
暴露され、偏光顕微鏡下で消光した部分の多いさびが形
成された鋼板を、さらに海岸地帯で３年間以上暴露する
実験を行ったが、流れさびの発生、腐食速度の増大は見
られなかった。このことは、一度形成された安定さび
は、たとえ海塩粒子の存在下でも安定であることを示唆
しており、本発明者らは、大気中で使用される以前に鋼
材表面に安定さびを形成しておけば、流れさびの発生や
色むらの発生を防止でき、海岸地帯での使用にも十分に
耐えられる鋼材となることに思い至った。Further, the present inventors conducted an experiment of exposing a steel plate which had been exposed in a rural area for 15 years and had rust formed in many parts quenched under a polarizing microscope to a coastal area for more than 3 years. No generation of flow rust and no increase in corrosion rate were observed. This suggests that the once formed stable rust is stable even in the presence of sea salt particles, and the present inventors have found that the stable rust on the steel surface before being used in the atmosphere. I thought that if it was formed, it would be possible to prevent the occurrence of flow rust and uneven color, and it would be a steel material that could withstand use in coastal areas.
【００１２】そこで、本発明者らは、鋼材の製造過程で
安定さびを短期に形成させる方法について鋭意検討し、
偏光顕微鏡下で消光したさびは、相対湿度で決定される
露点より５℃以上低い温度域と露点より５℃以上高い温
度域との間を昇温と降温を繰り返すことにより生成でき
ることを新規に見いだした。さらに、本発明者らは、偏
光顕微鏡下で消光したさびを含む耐候性安定さびについ
て、Ｘ線回折を用いてさらに解析を行った。その結果、
これらのさびは、非晶質さびを50重量％以上含有するさ
びであるという知見を得た。Therefore, the present inventors have intensively studied a method for forming a stable rust in a short period of time in the process of producing a steel material.
We have newly found that rust quenched under a polarizing microscope can be generated by repeatedly raising and lowering the temperature between a temperature range 5 ° C or more lower than the dew point determined by relative humidity and a temperature range 5 ° C or more higher than the dew point. Was. Furthermore, the present inventors further analyzed X-ray diffraction for weatherable stable rust including quenched rust under a polarizing microscope. as a result,
It has been found that these rusts are rusts containing amorphous rust in an amount of 50% by weight or more.
【００１３】本発明は上記した知見をもとにさらに検討
を加え完成されたものである。すなわち、本発明は、表
層にさび層を有する鋼材であって、前記さび層が非晶質
さびを50重量％以上含有することを特徴とする耐候性鋼
材である。また、本発明は、鋼材を、露点温度が一定に
保持された雰囲気内に保持し、該雰囲気内で該鋼材の温
度を、（露点温度＋５℃）以上の温度域と（露点温度−
５℃）以下の温度域との間で繰返し変動させることを特
徴とする耐侯性鋼板の製造方法であり、本発明では、前
記雰囲気は、酸素ガス分圧を15〜50容積％とするのが好
ましく、また、前記鋼材の温度を、昇温速度が0.1 〜２
℃／min 、降温速度が0.01〜２℃／min として変動させ
てもよい。The present invention has been completed by further study based on the above findings. That is, the present invention is a weather-resistant steel material having a rust layer on a surface layer, wherein the rust layer contains 50% by weight or more of amorphous rust. Further, the present invention holds the steel material in an atmosphere in which the dew point temperature is kept constant, and sets the temperature of the steel material in the atmosphere to a temperature range of (dew point temperature + 5 ° C.) or more and (dew point temperature−
5 ° C.) or lower. A method for producing a weather-resistant steel sheet characterized by repeatedly changing the temperature range to 5 ° C. or lower. In the present invention, the atmosphere is set to have an oxygen gas partial pressure of 15 to 50% by volume. Preferably, the temperature of the steel material is increased at a rate of 0.1 to 2.
C./min, and the temperature decreasing rate may be varied as 0.01 to 2 C./min.
【００１４】また、本発明は、露点温度が一定に保持さ
れ酸素ガス分圧が15〜50容積％である雰囲気内で、鋼材
の温度を（露点温度＋５℃）以上の温度域と（露点温度
−５℃）以下の温度域との間で、昇温速度を0.1 〜２℃
／min 、降温速度を0.01〜２℃／min として周期的に変
動させることを特徴とする鋼材表面への耐候性安定さび
の形成方法である。Further, the present invention provides a method for controlling the temperature of a steel material to a temperature range of (dew point temperature + 5 ° C.) or more in an atmosphere in which the dew point temperature is kept constant and the oxygen gas partial pressure is 15 to 50% by volume. -5 ° C) or lower, and the rate of temperature rise is 0.1 to 2 ° C.
/ Min, and a temperature decreasing rate of 0.01 to 2 ° C./min, which is periodically fluctuated to form a weather-resistant stable rust on a steel material surface.
【００１５】[0015]
【発明の実施の形態】まず、本発明の耐候性鋼材の製造
方法および鋼材表面への耐候性安定さびの形成方法につ
いて説明する。本発明では、鋼材を露点が一定に保持さ
れた雰囲気内に保持する。一定に保持する露点の値は、
鋼材に結露できる範囲であればとくに限定する必要はな
い。露点の調整は、雰囲気ガス中に水を噴霧して行うの
が好適である。なお、所定の安定さびを得るためには噴
霧する水は純水を用いるのが好ましい。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a method for producing a weather-resistant steel material according to the present invention and a method for forming a weather-resistant stable rust on a steel material surface will be described. In the present invention, the steel material is kept in an atmosphere where the dew point is kept constant. The value of the dew point that is kept constant is
There is no particular limitation as long as the condensation can be made on the steel material. The adjustment of the dew point is preferably performed by spraying water into the atmospheric gas. In order to obtain a predetermined stable rust, it is preferable to use pure water as the water to be sprayed.
【００１６】また、鋼材を保持する雰囲気は、露点を一
定に保持し、さらに酸素ガス分圧を15〜50容積％に維持
するのが好ましい。酸素ガス分圧が15容積％未満では、
腐食の進行速度が遅く安定さびの形成に長時間を要し生
産能率が低下する。また、酸素ガス分圧が50容積％を超
えると、腐食が進まない。このようなことから、雰囲気
中の酸素ガス分圧は15〜50容積％とするのが好ましい。
なお、窒素ガス中に酸素ガスを混合し、酸素ガス分圧を
調整するのが好ましく、混合する酸素ガスは所定の安定
さびを得るためにできるだけ純度の高いものを用いる。It is preferable that the atmosphere for holding the steel material keeps the dew point constant and further keeps the oxygen gas partial pressure at 15 to 50% by volume. If the oxygen gas partial pressure is less than 15% by volume,
The rate of progress of the corrosion is slow, and it takes a long time to form a stable rust, and the production efficiency decreases. If the oxygen gas partial pressure exceeds 50% by volume, corrosion does not proceed. For this reason, the oxygen gas partial pressure in the atmosphere is preferably set to 15 to 50% by volume.
It is preferable that oxygen gas be mixed with nitrogen gas to adjust the partial pressure of oxygen gas. The oxygen gas to be mixed should be as pure as possible to obtain a predetermined stable rust.
【００１７】また、使用する鋼材は、厚鋼板、薄鋼板あ
るいは形鋼等いずれでもよく、また、とくにその組成は
限定する必要はない。普通鋼あるいは耐候鋼いずれも好
適に使用できるが、耐食性を増加する観点からはＰ、C
u、Cr、Ni等を添加した耐候性鋼を用いるのが好まし
い。鋼材を上記した雰囲気内に保持し、鋼材温度を（露
点温度＋５℃）以上の温度域と（露点温度−５℃）以下
の温度域との間で、繰返し変動させる。（露点温度＋５
℃）以上の温度域と（露点温度−５℃）以下の温度域と
を往復させることにより、鋼材表面が結露と乾燥を繰返
し腐食の進行が速く、安定さびが短期に形成できる。上
記した各温度域での保持は、とくに必要としないが、１
〜60min 間保持しても、一定時間内の繰り返し回数が少
なくなるだけでなんら問題はない。Further, the steel material to be used may be any of a thick steel plate, a thin steel plate or a shaped steel, and its composition is not particularly limited. Both ordinary steel and weathering steel can be used preferably, but from the viewpoint of increasing corrosion resistance, P, C
It is preferable to use weathering steel to which u, Cr, Ni, etc. are added. The steel material is held in the above-described atmosphere, and the temperature of the steel material is repeatedly changed between a temperature range of (dew point temperature + 5 ° C.) or higher and a temperature range of (dew point temperature −5 ° C.) or lower. (Dew point temperature +5
C.) and a temperature range below (dew point temperature −5 ° C.), the steel surface repeats dew condensation and drying, the corrosion progresses rapidly, and stable rust can be formed in a short time. Holding at each of the above temperature ranges is not particularly necessary,
Even if it is held for up to 60 minutes, there is no problem only as the number of repetitions within a certain time is reduced.
【００１８】鋼材温度が（露点温度＋５℃）未満、（露
点温度−５℃）超の範囲では、鋼材表面における結露、
乾燥が不安定であるため、腐食が進行せず安定さび層の
形成が困難となる。また、（露点温度＋５℃）以上の温
度域と（露点温度−５℃）以下の温度域との間の鋼材温
度の昇温、降温は、昇温速度を0.1 〜２℃／min 、降温
速度を0.01〜２℃／min とするのが好ましい。昇温速度
が0.1 ℃／min 未満では、昇温に時間がかかりすぎ能率
的でなく、一方、２℃／min を超えると鋼材表面に消光
層が形成されにくくなる。また、降温速度が0.01℃／mi
n 未満では、降温に時間がかかりすぎ能率的でなく、一
方、２℃／min を超えると結露しにくくなり鋼材表面に
消光層が形成されにくくなる。When the temperature of the steel material is less than (dew point temperature + 5 ° C.) or more than (dew point temperature −5 ° C.), dew condensation on the steel material surface,
Since the drying is unstable, the corrosion does not proceed, and it is difficult to form a stable rust layer. Further, the temperature rise and fall of the steel material temperature between the temperature range of (dew point temperature + 5 ° C) or more and the temperature range of (dew point temperature −5 ° C) or less are performed at a rate of 0.1 to 2 ° C./min. Is preferably 0.01 to 2 ° C./min. If the rate of temperature rise is less than 0.1 ° C./min, it takes too much time to raise the temperature, which is not efficient. On the other hand, if it exceeds 2 ° C./min, it becomes difficult to form a quenching layer on the steel surface. In addition, the temperature drop rate is 0.01 ° C / mi
If it is less than n, it takes too much time to lower the temperature, which is not efficient. On the other hand, if it exceeds 2 ° C./min, it is difficult for dew condensation to occur and a quenching layer is hardly formed on the surface of the steel material.
【００１９】本発明でいう、耐候性安定さびは、偏光顕
微鏡下で消光した部分として観察されるさびであり、腐
食の進行を抑制することができるためには、消光した部
分として観察されるさびの厚さが、全さび厚さに対し少
なくとも0.5 以上となるのが好ましい。本発明でいう耐
候性安定さびは、Ｘ線回折を用いて解析すると、非晶質
さびを多く含有するさびである。The weathering-stable rust referred to in the present invention is a rust observed as a quenched portion under a polarizing microscope. In order to suppress the progress of corrosion, the rust observed as a quenched portion is required. Is preferably at least 0.5 or more with respect to the total rust thickness. The weathering-stable rust referred to in the present invention is a rust containing a large amount of amorphous rust when analyzed using X-ray diffraction.
【００２０】本発明の耐候性鋼材は、鋼材表層にさび層
を有する鋼材であって、前記さび層が非晶質さびを50重
量％以上含有することを特徴とする。なお、さび層は30
0 μm 厚以下とするのが好ましい。さび層の厚さが300
μm を超えても耐候性安定さびとしての性能は顕著に向
上しない。またさび層を厚く形成するためには、長時間
を要しコスト的に不利となる。The weathering steel according to the present invention is a steel having a rust layer on the surface of the steel, wherein the rust layer contains at least 50% by weight of amorphous rust. The rust layer is 30
The thickness is preferably 0 μm or less. Rust layer thickness is 300
Even if the thickness exceeds μm, the performance as a weather resistant stable rust does not significantly improve. In addition, it takes a long time to form a thick rust layer, which is disadvantageous in cost.
【００２１】本発明でいう非晶質さびとは、形成された
さび層について、Ｘ線回折を用いて結晶性さびの含有量
を測定し、さび層の全量から結晶性さびを除いた残りの
さびをいう。非晶質さびは、結晶粒が定義できず粒界も
存在しないことから、粒界からの腐食因子の侵入が考え
られる結晶性さびに比べ、高い防食能を有する。また、
非晶質さびは、鋼板表面との密着性に優れており、暴露
による乾湿の繰り返しによりさらに強固なさび層を形成
する。また、非晶質さびは結合水を多く含んでおり、こ
れらがさび層のミクロ空隙を埋め、結果的にさび層を緻
密とし、腐食因子の侵入を防止し、耐候性を向上させる
ものと考えられる。さらに、暴露により、地鉄から溶出
してきたCr、Cu等の成分を取り込み、さらに耐候性的に
安定なさびとなる。The term "amorphous rust" as used in the present invention refers to the rust layer formed by measuring the content of crystalline rust using X-ray diffraction, and removing the rust layer from the total amount of the rust layer. Say rust. Amorphous rust has higher corrosion protection than crystalline rust, in which a crystal grain cannot be defined and there is no grain boundary, as compared with a crystalline rust in which corrosion factors may enter from the grain boundary. Also,
Amorphous rust has excellent adhesion to the surface of a steel sheet, and forms a stronger rust layer by repeated drying and wetting due to exposure. In addition, amorphous rust contains a large amount of bound water, which is considered to fill the micro voids in the rust layer, thereby making the rust layer denser, preventing corrosion factors from entering, and improving weather resistance. Can be Furthermore, by exposure, it takes in components such as Cr and Cu eluted from the base iron, and becomes rust stable in terms of weather resistance.
【００２２】本発明の耐候性鋼材では、鋼材表面に形成
されるさび層を、非晶質さびが50重量％以上含有される
さび層とする。このようなさび層を形成するには、上記
した処理方法が好適である。非晶質さびの含有量の調整
は、（露点温度＋５℃）以上の温度域と（露点温度−５
℃）以下の温度域での保持時間を調整することにより行
うのが好ましい。In the weather-resistant steel of the present invention, the rust layer formed on the surface of the steel is a rust layer containing 50% by weight or more of amorphous rust. To form such a rust layer, the above-described treatment method is suitable. The adjustment of the amorphous rust content is performed in a temperature range of (dew point temperature + 5 ° C) or more and (dew point temperature −5).
C) is preferably carried out by adjusting the holding time in the temperature range below.
【００２３】さび層が、非晶質さびを50重量％以上含有
することにより、流れさびの発生が抑制される。一方、
非晶質さびが、さび層の50重量％未満では、さび層が粗
く耐候性安定さびとなるまでに地鉄の腐食が進行し、さ
らに流れさびが発生する。さび層が非晶質さびを50重量
％以上含有することにより、流れさびの発生は抑制され
るが、地鉄の腐食を完全に防止するわけではない。僅か
ながら鉄は溶出し、ゆっくりとさび層が増加し、最終的
に安定さびとなるのである。When the rust layer contains at least 50% by weight of amorphous rust, generation of flowing rust is suppressed. on the other hand,
If the amorphous rust is less than 50% by weight of the rust layer, the corrosion of the ground iron proceeds until the rust layer becomes coarse and becomes weather-resistant and stable rust, and further flow rust is generated. When the rust layer contains at least 50% by weight of amorphous rust, generation of flow rust is suppressed, but it does not completely prevent corrosion of the ground iron. A small amount of iron elutes and the rust layer slowly increases, eventually becoming stable rust.
【００２４】結晶性さびには、α−FeOOH 、γ−FeOOH
、Fe3O4 などがあるが、いずれも流れさびの発生を抑
制する能力は小さい。このため、本発明では、さび層中
の結晶性さびの含有量は50重量％未満とする。α−FeOO
H は熱力学的には安定であるが、鋼材表面に密着性に優
れたさび層を形成するのは困難である。また、γ−FeOO
H は、大気中に暴露された鋼材の表面に初期に形成され
るさび形態であり、湿潤環境下では還元され他のさび形
態に変化する。しかし、流れさびの発生を抑制する効果
は小さい。さらに、Fe3O4 は、最終的に安定さびとなる
ことはできないうえ、鋼材表面に形成しても大気中の暴
露により赤錆を発生する。Crystalline rust includes α-FeOOH and γ-FeOOH
, Fe 3 O 4, etc., but all have a small ability to suppress the generation of flow rust. For this reason, in the present invention, the content of crystalline rust in the rust layer is set to less than 50% by weight. α-FeOO
H is thermodynamically stable, but it is difficult to form a rust layer with excellent adhesion on the steel surface. Also, γ-FeOO
H 2 is a rust form initially formed on the surface of a steel material exposed to the atmosphere, and is reduced to another rust form in a wet environment. However, the effect of suppressing the generation of flow rust is small. Furthermore, Fe 3 O 4 cannot eventually become stable rust, and even when formed on the surface of a steel material, red rust is generated by exposure to the atmosphere.
【００２５】本発明を実施するには、鋼材を保持し鋼材
の温度を周期的に変化できる槽と、雰囲気中の水分調整
が可能な装置と、雰囲気中の酸素分圧を変化できる装置
があればよく、安定さびを形成された耐候性鋼材を１カ
月以内程度の極めて短時間で、簡単で安価に製造するこ
とが可能となる。In order to carry out the present invention, there are a tank capable of holding a steel material and periodically changing the temperature of the steel material, a device capable of adjusting moisture in the atmosphere, and a device capable of changing the oxygen partial pressure in the atmosphere. It suffices to manufacture a weather-resistant steel material with a stable rust formed within a very short time of about one month or less in a simple and inexpensive manner.
【００２６】[0026]
【実施例】表１に示す組成の鋼板から切り出した試験片
（５mmt ×50mmw ×100mml）に、図１に示すモデル安定
さび形成設備を用い、表２に示す条件でさびを形成させ
た。鋼No. Ａは普通鋼、鋼No. Ｂは耐候性鋼である。試
験片は各条件３枚を準備した。試験片１をさび形成槽２
内に保持し、露点と酸素ガス分圧を調整した混合ガスを
さび形成槽２に連続的に送り込みながら、さび形成槽２
の温度制御用ヒータ９で試験片１の温度を表２に示す所
定の温度域間を繰返し変動させ、試験片１にさびを形成
させる処理を施した。なお、所定の温度域では、表２に
示す時間だけ保持した。処理期間は20日間とした。EXAMPLE A test piece (5 mmt.times.50 mmw.times.100 mml) cut from a steel sheet having the composition shown in Table 1 was formed with a rust under the conditions shown in Table 2 using the model stable rust forming equipment shown in FIG. Steel No. A is ordinary steel and steel No. B is weather resistant steel. Three test pieces were prepared for each condition. The test piece 1 is placed in a rust forming tank 2
While the mixed gas having the dew point and the oxygen gas partial pressure adjusted is continuously fed into the rust forming tank 2,
The temperature of the test piece 1 was repeatedly fluctuated between predetermined temperature ranges shown in Table 2 by the temperature control heater 9 to perform a process of forming rust on the test piece 1. In a predetermined temperature range, the temperature was maintained for the time shown in Table 2. The treatment period was 20 days.
【００２７】[0027]
【表１】 [Table 1]
【００２８】なお、露点は、水分調整室３で加湿装置４
からの水分を所定露点となるように噴霧して調整し、ま
た、雰囲気中の酸素ガス分圧は、窒素ガス７中に所定酸
素ガス分圧になるよう酸素ガス８を混合し調整した。処
理後、試験片の全面がさびで覆われたものについて、各
条件３枚中１枚を５箇所で切断し、その断面を偏光顕微
鏡で観察し、全さび厚さに対する消光するさび厚さの比
を測定した。また、形成されたさびをスクレーパーでか
きおとし、各試験片について約0.3gのさびを採取し、内
部標準法を用いたＸ線回折法により、さび成分の同定と
定量を行った。標準物質としてはZnO を用いた。解析の
結果、結晶性さびとして、α−FeOOH 、γ−FeOOH 、Fe
3O4 が認められた。測定に供したさびの全量（重量）か
ら結晶性さびの量（重量）を差し引いたさび量（重量）
を非晶質さびの量（重量）とし、さび全量に対する非晶
質さびの割合を算出し、非晶質さびの含有量（重量％）
とした。それらの結果を表２に示す。The dew point is measured by the humidifier 4
Was adjusted by spraying water from the water to a predetermined dew point, and the oxygen gas partial pressure in the atmosphere was adjusted by mixing the oxygen gas 8 in the nitrogen gas 7 so as to have the predetermined oxygen gas partial pressure. After the treatment, for the specimen whose entire surface was covered with rust, one out of three specimens under each condition was cut at five places, and the cross section was observed with a polarizing microscope. The ratio was measured. Further, the formed rust was scraped with a scraper, and about 0.3 g of rust was collected from each test piece, and the rust component was identified and quantified by an X-ray diffraction method using an internal standard method. ZnO was used as a standard substance. As a result of the analysis, as crystalline rust, α-FeOOH, γ-FeOOH, Fe
3 O 4 was observed. Rust amount (weight) obtained by subtracting the amount (weight) of crystalline rust from the total amount (weight) of rust used for measurement
Is the amount (weight) of amorphous rust, and the ratio of amorphous rust to the total amount of rust is calculated, and the content of amorphous rust (% by weight)
And Table 2 shows the results.
【００２９】さらに、残り２枚のさびが形成された試験
片を、田園地帯および海岸地帯で３か月間暴露し、流れ
さびの発生状況を調査した。それらの結果を表２に示
す。なお、流れさびの発生状況は、試験片下部に設置し
たコンクリートの汚染状況を目視により観察した。ま
た、試験片表面の浮きさびの発生状況についても目視で
観察した。Further, the remaining two rust-formed test pieces were exposed for 3 months in a rural area and a coastal area, and the occurrence of flow rust was examined. Table 2 shows the results. In addition, the generation | occurrence | production state of the flow rust was visually observed about the contamination state of the concrete installed under the test piece. The occurrence of floating rust on the surface of the test piece was also visually observed.
【００３０】[0030]
【表２】 [Table 2]
【００３１】[0031]
【表３】 [Table 3]
【００３２】[0032]
【表４】 [Table 4]
【００３３】[0033]
【表５】 [Table 5]
【００３４】表２から本発明の範囲の条件下で処理した
試験片では、全さび厚さに対する消光したさび厚さの比
は、普通鋼で0.53〜0.75、耐候性鋼で0.54〜0.86と高
く、また、非晶質さびの含有量は普通鋼で51〜70重量
％、耐候性鋼で53〜82重量％と高く、いずれも50重量％
以上であり、安定さびが十分に形成されていることがわ
かる。また、これら本発明の範囲で処理された試験片
は、その後の田園地帯および海岸地帯のいずれにおける
暴露でも流れさびの発生、浮きさびの発生は認められな
かった。From the test pieces treated under the conditions within the range of the present invention from Table 2, the ratio of the quenched rust thickness to the total rust thickness is as high as 0.53 to 0.75 for ordinary steel and 0.54 to 0.86 for weathering steel. The content of amorphous rust is as high as 51-70% by weight for ordinary steel and 53-82% by weight for weather-resistant steel, all 50% by weight.
As described above, it can be seen that the stable rust is sufficiently formed. Further, in the test pieces treated in the range of the present invention, generation of flow rust and floating rust were not observed in the subsequent exposure in both the countryside and the coast.
【００３５】一方、本発明の範囲を外れる条件で処理さ
れた試験片では、いずれも全さび厚さに対する消光した
さび厚さの比は、0.50以下と小さく、また、非晶質さび
の含有量はいずれも50重量％未満である。またさびの量
が少なく試験片全面を覆わない場合もあり、その後の田
園地帯および海岸地帯における暴露で流れさびの発生、
浮きさびの発生が認められた。On the other hand, in the test pieces treated under the conditions outside the range of the present invention, the ratio of the quenched rust thickness to the total rust thickness is as small as 0.50 or less, and the content of the amorphous rust is small. Is less than 50% by weight. In addition, the amount of rust may be small and may not cover the entire surface of the test piece, and subsequent exposure in the countryside and coastal areas may cause rust,
The occurrence of floating rust was observed.
【００３６】[0036]
【発明の効果】本発明によれば、経済的に安価な方法で
安定さびを短時間で形成でき、流れさびの発生を防止で
きるうえ、海岸地帯での使用に耐え得る耐候性鋼材を製
造でき、産業上格段の効果を奏する。According to the present invention, it is possible to form a stable rust in a short time by an economically inexpensive method, to prevent the occurrence of flow rust, and to manufacture a weather-resistant steel material that can withstand use in a coastal zone. It has a remarkable industrial effect.
【図１】本発明の実施に好適なモデル安定さび形成設備
を模式的に示す概略図である。FIG. 1 is a schematic view schematically showing a model stable rust forming facility suitable for carrying out the present invention.
１ 試験片（鋼材） ２ さび形成槽 ３ 水分調整室 ４ 加湿装置 ５ 加湿用ヒータ ６ ガス供給装置 ７ 窒素ガス ８ 酸素ガス ９ 温度制御用ヒータ 10 排ガス処理装置 11 水 DESCRIPTION OF SYMBOLS 1 Test piece (steel material) 2 Rust forming tank 3 Moisture adjustment room 4 Humidifier 5 Humidifier heater 6 Gas supply device 7 Nitrogen gas 8 Oxygen gas 9 Temperature control heater 10 Exhaust gas treatment device 11 Water
───────────────────────────────────────────────────── フロントページの続き (72)発明者 西村 公宏 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 (72)発明者 川端 文丸 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 (72)発明者 星野 俊幸 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 (72)発明者 天野 虔一 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kimihiro Nishimura 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. 1-chome (without address) Kawasaki Steel Corporation Mizushima Works (72) Inventor Toshiyuki Hoshino 1-chome, Mizushima-Kawasaki-dori Kurashiki-shi, Okayama Prefecture (without address) Kawasaki Steel Corporation Mizushima Works (72) Inventor Kenichi Amano 1-chome, Kawasaki-dori, Mizushima, Kurashiki City, Okayama Prefecture (without address) Inside the Kawasaki Steel Works, Mizushima Works
Claims (5)
記さび層が非晶質さびを50重量％以上含有することを特
徴とする耐候性鋼材。1. A weather-resistant steel material having a rust layer on its surface, wherein the rust layer contains 50% by weight or more of amorphous rust.
囲気内に保持し、該雰囲気内で該鋼材の温度を、（露点
温度＋５℃）以上の温度域と（露点温度−５℃）以下の
温度域との間で繰返し変動させることを特徴とする耐候
性鋼材の製造方法。2. A steel material is held in an atmosphere in which the dew point temperature is kept constant, and the temperature of the steel material in the atmosphere is set to a temperature range of (dew point temperature + 5 ° C.) or more and (dew point temperature −5 ° C.). A method for producing a weather-resistant steel material, wherein the temperature is repeatedly changed between the following temperature ranges.
積％であることを特徴とする請求項２に記載の耐候性鋼
材の製造方法。3. The method according to claim 2, wherein the atmosphere has an oxygen gas partial pressure of 15 to 50% by volume.
℃／min 、降温速度が0.01〜２℃／min として変動させ
ることを特徴とする請求項２または３に記載の耐候性鋼
材の製造方法。4. The steel material is heated at a rate of 0.1 to 2
The method for producing a weather-resistant steel material according to claim 2 or 3, wherein the temperature is lowered at a rate of 0.01 to 2 ° C / min.
が15〜50容積％である雰囲気内で、鋼材の温度を（露点
温度＋５℃）以上の温度域と（露点温度−５℃）以下の
温度域との間で、昇温速度を0.1 〜２℃／min 、降温速
度を0.01〜２℃／min として周期的に変動させることを
特徴とする鋼材表面への耐候性安定さびの形成方法。5. In an atmosphere where the dew point temperature is kept constant and the oxygen gas partial pressure is 15 to 50% by volume, the temperature of the steel material is set to a temperature range of (dew point temperature + 5 ° C.) or more and (dew point temperature −5 ° C.) The formation of weather-resistant stable rust on the surface of a steel material, wherein the temperature is raised periodically at a rate of 0.1 to 2 ° C./min and at a rate of 0.01 to 2 ° C./min between the following temperature ranges: Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP37065198A JPH11256307A (en) | 1998-01-08 | 1998-12-25 | Weather resistant steel and its production |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10-2645 | 1998-01-08 | ||
| JP264598 | 1998-01-08 | ||
| JP37065198A JPH11256307A (en) | 1998-01-08 | 1998-12-25 | Weather resistant steel and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11256307A true JPH11256307A (en) | 1999-09-21 |
Family
ID=26336090
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP37065198A Pending JPH11256307A (en) | 1998-01-08 | 1998-12-25 | Weather resistant steel and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11256307A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004508466A (en) * | 2000-09-12 | 2004-03-18 | ノバ ケミカルズ（インターナショナル）ソシエテ アノニム | How to treat stainless steel matrix |
| JP2016008346A (en) * | 2014-06-26 | 2016-01-18 | Ｊｆｅスチール株式会社 | Dense rust early formation method of anti-weathering steel material, and anti-weathering steel material produced by method |
-
1998
- 1998-12-25 JP JP37065198A patent/JPH11256307A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004508466A (en) * | 2000-09-12 | 2004-03-18 | ノバ ケミカルズ（インターナショナル）ソシエテ アノニム | How to treat stainless steel matrix |
| JP2016008346A (en) * | 2014-06-26 | 2016-01-18 | Ｊｆｅスチール株式会社 | Dense rust early formation method of anti-weathering steel material, and anti-weathering steel material produced by method |
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