JP2007107045A - Method for pickling stainless steel material and method for producing the same - Google Patents
Method for pickling stainless steel material and method for producing the same Download PDFInfo
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本発明は、ステンレス鋼材の酸洗方法及び製造方法に関し、特に塩酸溶液による酸洗を行うにあたって、酸洗処理に要する時間を短縮させるのに効果的な酸洗方法及びその酸洗方法を用いたステンレス鋼材の製造方法に関する。 The present invention relates to a pickling method and a manufacturing method for stainless steel materials, and in particular, when performing pickling with a hydrochloric acid solution, an effective pickling method and the pickling method for reducing the time required for pickling treatment are used. The present invention relates to a method for producing a stainless steel material.
ステンレス鋼を製造する工程においては、熱延または焼鈍時に生成したスケールや表面の脱Cr層を除去するために、硫酸、塩酸、硝酸、弗酸などの酸、またはそれらの混合酸に鋼を浸漬して地鉄を溶解する、いわゆる酸洗処理が行なわれる。そして、酸洗処理に用いられる酸洗液としては、硝酸と弗酸の組み合わせによる混合酸液がその処理能力の優位性から、現在、多く用いられている。しかし、硝酸や弗酸を用いる方法は、酸洗処理時に硝酸が分解して有害なNOxガスや弗化水素ガスが多量に発生し、環境上大きな問題がある。このため、排ガスを浄化処理する必要があるが、近年の公害規制の強化とともにその処理費用は著しく増大している。また、弗酸は毒性が強いため、これを使用する酸洗作業では常に危険が伴い、その取り扱いには注意しなければならない。このような背景から、近年では酸洗液として硝酸や弗酸の酸洗液を用いない酸洗方法の開発が強く求められている。 In the process of manufacturing stainless steel, the steel is immersed in acids such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, or a mixture of these to remove the scale and surface de-Cr layer formed during hot rolling or annealing. Then, so-called pickling treatment for dissolving the base iron is performed. As a pickling solution used for the pickling treatment, a mixed acid solution using a combination of nitric acid and hydrofluoric acid is currently widely used because of its superior processing ability. However, the method using nitric acid or hydrofluoric acid has a large environmental problem because nitric acid is decomposed during the pickling treatment to generate a large amount of harmful NOx gas or hydrogen fluoride gas. For this reason, it is necessary to purify the exhaust gas, but the cost of the treatment has increased remarkably with the recent tightening of pollution regulations. Also, since hydrofluoric acid is highly toxic, pickling work using it is always dangerous and must be handled with care. Against this background, in recent years, there has been a strong demand for the development of pickling methods that do not use nitric acid or hydrofluoric acid pickling solutions.
このような現状の中で、酸洗液として塩酸を用いた酸洗方法が開発されている。塩酸は硝酸と弗酸の混合酸液を用いる酸洗方法よりも酸洗能力は劣るものの、硝酸や弗酸に比べて酸洗液のコスト、および廃液処理に要する設備コストが安価であるという利点がある。例えば、塩酸を用いた酸洗技術として、特許文献１では、塩酸濃度と液温を管理することによる酸洗方法が開示されている。また、塩酸を用いた酸洗能力を向上させる技術として、特許文献2では、塩酸溶液中に過酸化水素を注入する方法が開示されている。さらに、特許文献３では、塩酸溶液中へ亜硫酸水素ナトリウムを添加する方法が開示されている。
しかしながら、特許文献１に記載された技術を施しても、酸洗処理時間を大幅に短縮することはできない。 However, even if the technique described in Patent Document 1 is applied, the pickling time cannot be significantly reduced.
また、特許文献２に記載されている技術では酸洗処理時の過酸化水素の分解が早く、大量の補給を余儀なくされるため、安定した酸洗液の維持が困難であり、操業コストが嵩むといった問題がある。また、過酸化水素の多量添加はピッティングを生じさせ酸洗後の表面性状も劣化する。 Moreover, in the technique described in Patent Document 2, hydrogen peroxide is rapidly decomposed during the pickling treatment, and a large amount of replenishment is unavoidable. Therefore, it is difficult to maintain a stable pickling solution, and the operation cost increases. There is a problem. Moreover, the addition of a large amount of hydrogen peroxide causes pitting, and the surface properties after pickling are also deteriorated.
特許文献３に記載されている技術では、有害な亜硫酸ガスを発生するため、公害上大きな問題がある。 In the technique described in Patent Document 3, harmful sulfurous acid gas is generated.
以上より、本発明は、係る従来の問題点に省みてなされたもので、塩酸溶液を用いて効率的に酸洗処理を行い、その酸洗時間を短縮することのできるステンレス鋼材の酸洗方法及びその酸洗方法を用いたステンレス鋼材の製造方法を提供することを目的とする。 As described above, the present invention has been made in view of the conventional problems, and it is possible to efficiently perform pickling treatment using a hydrochloric acid solution and shorten the pickling time of the stainless steel material. And it aims at providing the manufacturing method of stainless steel material using the pickling method.
本発明者らは上記課題を解決するために、酸洗液としての塩酸溶液とそこに添加する酸洗促進剤に着目し、研究を進めた。前述の通り、ステンレス鋼材の酸洗能力としては硝酸と弗酸との混合酸に比べて塩酸溶液はやや劣るが、NOxガスや弗化水素ガスを発生させない。そこで、まず、塩酸溶液を用いた場合の酸洗能力を改善するために、塩酸溶液中に含まれる成分と、酸洗促進剤としての種々の添加剤について検討した。その結果、Feイオン、Crイオン、Niイオンの少なくとも一つ以上を含む塩酸溶液においては、Feイオン、Crイオン、Niイオンの各イオンの総和量を50g/L以上とし、かつ全塩素量を50g/L以上とした上で塩酸溶液に塩化ニッケルを添加することすることが酸洗処理を促進させる上で有効であり、酸洗能力が飛躍的に向上することを見出した。また、このときの塩化ニッケルの添加量は、1〜50g/Lが好適である。 In order to solve the above-mentioned problems, the present inventors paid attention to a hydrochloric acid solution as a pickling solution and a pickling accelerator to be added thereto, and advanced research. As described above, the pickling ability of the stainless steel material is slightly inferior to the mixed acid of nitric acid and hydrofluoric acid, but does not generate NOx gas or hydrogen fluoride gas. Therefore, first, in order to improve the pickling ability when using a hydrochloric acid solution, the components contained in the hydrochloric acid solution and various additives as a pickling accelerator were examined. As a result, in a hydrochloric acid solution containing at least one of Fe ions, Cr ions, and Ni ions, the total amount of each of the Fe ions, Cr ions, and Ni ions is 50 g / L or more, and the total chlorine amount is 50 g. It was found that the addition of nickel chloride to the hydrochloric acid solution after setting to at least / L was effective in promoting the pickling treatment, and the pickling ability was dramatically improved. Moreover, the addition amount of nickel chloride at this time is preferably 1 to 50 g / L.
さらに、本発明では、ステンレス熱延板の酸洗において、例えば、一般的に行なわれているショットブラスト、もしくはベンディングによるメカニカルな予備脱スケール処理を施した後に上記のように規定した酸洗液を用いた酸洗処理を行うことで顕著な効果が得られることも見出した。 Furthermore, in the present invention, in pickling of stainless hot-rolled sheets, for example, a general pre-scale treatment by shot blasting or bending is performed, and then the pickling solution defined above is used. It has also been found that a remarkable effect can be obtained by performing the pickling treatment used.
本発明は、以上の知見に基づきなされたもので、その要旨は以下のとおりである。
［１］ステンレス鋼材を酸洗液により酸洗するにあたり、該酸洗液は、塩化ニッケルを添加した塩酸溶液からなり、該塩酸溶液は、Feイオン、Crイオン、Niイオンの少なくとも一つ以上を含み、Feイオン、Crイオン、Niイオンの各イオンの総和量が50g/L以上であり、かつ全塩素量が50g/L以上であることを特徴とするステンレス鋼材の酸洗方法。
［２］前記［１］において、前記塩化ニッケルを1〜50g/Lの添加量で添加することを特徴とするステンレス鋼材の酸洗方法。
［３］前記［１］または［２］において、前記塩酸溶液の濃度は5〜30%であることを特徴とする［ステンレス鋼材の酸洗方法。
［４］フェライト系ステンレス鋼からなる熱延板または熱延焼鈍板に、予備脱スケール処理を施した後、前記[1]〜［３］のいずれかに記載の酸洗を行うことを特徴とするステンレス鋼材の製造方法。
The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] In pickling a stainless steel material with a pickling solution, the pickling solution comprises a hydrochloric acid solution to which nickel chloride is added, and the hydrochloric acid solution contains at least one of Fe ions, Cr ions, and Ni ions. A method for pickling stainless steel, characterized in that the total amount of Fe ions, Cr ions, and Ni ions is 50 g / L or more and the total chlorine amount is 50 g / L or more.
[2] The pickling method for a stainless steel material according to [1], wherein the nickel chloride is added in an addition amount of 1 to 50 g / L.
[3] In the above [1] or [2], the concentration of the hydrochloric acid solution is 5 to 30%. [Pickling method for stainless steel material]
[4] A hot-rolled sheet or a hot-rolled annealed sheet made of ferritic stainless steel is subjected to a preliminary descaling treatment and then pickled according to any one of [1] to [3]. To produce stainless steel.
本発明によれば、ステンレス鋼材の酸洗処理が効率的に行え、その結果、酸洗時間を従来に比べ、短縮することが可能となる。 According to the present invention, the pickling treatment of the stainless steel material can be performed efficiently, and as a result, the pickling time can be shortened as compared with the prior art.
ステンレス鋼材のスケールおよび表面の脱Cr層を酸洗により除去する場合、母材溶解による酸洗液への金属イオンの溶出が工業上不可避であり、これらの金属イオンは塩素イオンと錯体を形成し、酸洗促進の役割を果たす遊離塩素量の低下を招くため、一般的に酸洗能力が低下する。しかし、本発明によれば、酸洗能力を大幅に向上させることが可能であり、酸洗ラインの通板速度の増速などで産業上格段の効果を奏することとなる。 When removing the stainless steel scale and surface Cr removal layer by pickling, elution of metal ions into the pickling solution due to dissolution of the base material is unavoidable industrially, and these metal ions form a complex with chlorine ions. In general, the pickling ability is reduced because the amount of free chlorine that plays the role of promoting pickling is reduced. However, according to the present invention, it is possible to greatly improve the pickling ability, and an industrially remarkable effect can be obtained by increasing the plate passing speed of the pickling line.
以下、本発明について具体的に説明する。
まず、本発明を完成するに至った実験結果について説明する。
通常の方法で製造したSUS410Lの熱延焼鈍板に対して、ショットブラストを施した後、酸洗処理を行い、この時の酸洗減量を調査した。実験を行うにあたって、酸洗液としては、実際の工場の塩酸酸洗ラインから採取した11%塩酸溶液に塩化ニッケルを表１に示す条件にて0〜90g/L添加した溶液を用いた。また30mm×40mmの熱延焼鈍板を用いて、酸洗前後での重量変化を測定し、単位面積あたりの酸洗減量を算出して評価を行なった。なお、実験に用いた酸洗液を分析した結果、酸洗液中にはFeイオン、Crイオン、Niイオンがそれぞれ125g/L、3g/L、1g/L含まれていた。以上により得られた結果を条件と併せて表１に示す。
Hereinafter, the present invention will be specifically described.
First, the experimental results that led to the completion of the present invention will be described.
Shot blasting was performed on a SUS410L hot-rolled annealed plate manufactured by a normal method, and then pickling treatment was performed, and the pickling loss at this time was investigated. In conducting the experiment, as the pickling solution, a solution in which 0 to 90 g / L of nickel chloride was added to an 11% hydrochloric acid solution collected from a hydrochloric acid pickling line in an actual factory under the conditions shown in Table 1 was used. Further, using a 30 mm × 40 mm hot-rolled annealed plate, the weight change before and after pickling was measured, and the pickling loss per unit area was calculated and evaluated. As a result of analyzing the pickling solution used in the experiment, the pickling solution contained 125 g / L, 3 g / L, and 1 g / L of Fe ions, Cr ions, and Ni ions, respectively. The results obtained above are shown in Table 1 together with the conditions.
表１の結果を基に、酸洗液中の塩化ニッケルの添加量と酸洗減量との関係を図１に示す。表１及び図１から、塩化ニッケルを添加することにより、酸洗減量は急激に増加し酸洗が促進されていることがわかる。 Based on the results in Table 1, the relationship between the amount of nickel chloride added in the pickling solution and the pickling reduction is shown in FIG. From Table 1 and FIG. 1, it can be seen that by adding nickel chloride, the pickling loss increased rapidly and the pickling was promoted.
そこで、本発明者らは、塩化ニッケル添加による大幅な酸洗促進メカニズムを解明するため、金属イオンを含まない市販の塩酸試薬を用いて、上記の塩酸酸洗ラインから採取した塩酸溶液と同じ11%塩酸溶液を調合し、これに塩化ニッケルを0〜90g/L添加した酸洗液を作製し、上記と同様の試験材を用い、上記と同様の方法にて酸洗減量を調べた。得られた結果を、詳細な条件と併せて表２に示す。又、表２の結果に基づいて、酸洗液中の塩化ニッケルの添加量と酸洗減量との関係を図２に示す。 Therefore, in order to elucidate a significant pickling promotion mechanism by adding nickel chloride, the present inventors used a commercially available hydrochloric acid reagent not containing metal ions and used the same hydrochloric acid solution collected from the above hydrochloric acid pickling line. A pickling solution containing 0% to 90 g / L of nickel chloride was prepared by preparing a% hydrochloric acid solution, and the pickling weight loss was examined by the same method as described above using the same test material as described above. The obtained results are shown in Table 2 together with detailed conditions. Moreover, based on the result of Table 2, the relationship between the addition amount of nickel chloride in the pickling solution and the pickling reduction amount is shown in FIG.
図２から、金属イオンを含まない市販の塩酸試薬を使用した酸洗液においては、前述したような酸洗減量の大幅な増加は認められないばかりか、逆に塩化ニッケルを添加するほど酸洗減量は低下する傾向であることがわかる。 As shown in FIG. 2, in the pickling solution using a commercially available hydrochloric acid reagent not containing metal ions, not only a significant increase in the pickling loss as described above is observed, but conversely, the pickling is increased as nickel chloride is added. It can be seen that the weight loss tends to decrease.
そこで、本発明者らは、上記の実際の工場の塩酸酸洗ラインから採取した塩酸溶液と市販の塩酸試薬から作製した塩酸溶液へ、各々塩化ニッケルを添加した場合に、酸洗促進への効果が相反する結果になっていることについて、塩酸溶液中の塩素イオンの存在形態が重要な鍵になっていると考え、前記両方の塩酸溶液のFe、Cr、Niの各イオン量、および全塩素量の分析を行なった。なお、全塩素量の分析は硝酸銀滴定により行った。結果を上記表１及び表２に併せて示す。表１及び表２より、塩酸酸洗ラインから採取した塩酸溶液の方が市販の塩酸試薬から作製した塩酸溶液に比べ、全塩素量が多い（２倍強）ことがわかる。また、市販の塩酸試薬を用いた場合はFe、Cr、Niの各イオンは含まれていない。 Therefore, the present inventors have the effect of promoting pickling when nickel chloride is added to each of the hydrochloric acid solution collected from the hydrochloric acid pickling line of the actual factory and the hydrochloric acid solution prepared from a commercially available hydrochloric acid reagent. The existence form of chlorine ions in hydrochloric acid solution is considered to be an important key, and the amounts of Fe, Cr, Ni ions in both hydrochloric acid solutions, and total chlorine Quantity analysis was performed. The total chlorine amount was analyzed by silver nitrate titration. The results are shown in Tables 1 and 2 above. From Tables 1 and 2, it can be seen that the total amount of chlorine is more (2 times more) in the hydrochloric acid solution collected from the hydrochloric acid pickling line than in the hydrochloric acid solution prepared from a commercially available hydrochloric acid reagent. Moreover, when a commercially available hydrochloric acid reagent is used, each ion of Fe, Cr, and Ni is not included.
実際の生産ラインでは、酸洗処理において消費される水素イオンを補填するため、随時、新しい酸洗液を投入し、塩酸濃度を維持して操業するのが通常である。この場合、塩酸溶液中の水素イオンは一定に保たれるが、塩素イオンは増加することになる。それゆえ、表１において、塩酸酸洗ラインから採取した塩酸溶液では、11%塩酸液の塩素量（塩素濃度：113g/L）から考えられる塩素量よりも多い全塩素量（231g/L）が分析されたと考えられる。 In an actual production line, in order to make up for hydrogen ions consumed in the pickling treatment, it is usual to add a new pickling solution and maintain the hydrochloric acid concentration at any time. In this case, hydrogen ions in the hydrochloric acid solution are kept constant, but chlorine ions increase. Therefore, in Table 1, in the hydrochloric acid solution collected from the hydrochloric acid pickling line, the total chlorine amount (231 g / L) is higher than the chlorine amount considered from the chlorine amount of 11% hydrochloric acid solution (chlorine concentration: 113 g / L). It is thought that it was analyzed.
また、塩酸酸洗ラインでは、普通鋼およびステンレス鋼などの酸洗を行うため、これらのスケールおよび母材部分が溶出し、酸洗液中にFe、Cr、Niイオンなどを多く含有することになり、これらの金属イオンは、塩素イオンと錯体を形成することが一般的に知られている。そのため、金属イオンとの錯体形成で固定されていない塩素（以下、遊離塩素とよぶ）の量は、全塩素量よりも少なくなることになる。 Also, the pickling line for hydrochloric acid pickles plain steel and stainless steel, so these scales and base metal parts are eluted, and the pickling solution contains a lot of Fe, Cr, Ni ions, etc. Thus, it is generally known that these metal ions form a complex with chlorine ions. Therefore, the amount of chlorine not fixed by complex formation with metal ions (hereinafter referred to as free chlorine) is less than the total amount of chlorine.
このように、通常の工業的な塩酸酸洗工程では、塩酸溶液中に多くの金属イオンが存在し、それらが塩素イオンを錯体として固定してしまうため、市販の塩酸試薬から調合した同じ酸濃度の塩酸溶液よりも酸洗能力が劣るものと考えられる。しかし、鉄鋼材料の酸洗処理を行う場合は、酸溶液中への金属イオンの溶出は避けられない。 Thus, in the usual industrial hydrochloric acid pickling process, there are many metal ions in the hydrochloric acid solution, and they fix the chlorine ions as a complex, so the same acid concentration prepared from a commercially available hydrochloric acid reagent It is considered that the pickling ability is inferior to that of the hydrochloric acid solution. However, elution of metal ions into the acid solution is unavoidable when pickling the steel material.
そこで、通常の工業的な塩酸酸洗工程における酸洗能力を向上させるために、金属イオンを含有する塩酸溶液への塩化ニッケル添加が必要になる。塩化ニッケル添加による酸洗促進作用は、金属イオンが形成している塩化物の錯体平衡に変化を与えて、遊離塩素量を増加させると考えられる。 Therefore, in order to improve the pickling ability in a normal industrial hydrochloric acid pickling process, it is necessary to add nickel chloride to the hydrochloric acid solution containing metal ions. It is considered that the pickling promotion effect by adding nickel chloride gives a change to the complex equilibrium of chloride formed by metal ions and increases the amount of free chlorine.
例えば、ステンレス鋼の熱延板および熱延焼鈍板の酸洗工程においては黒皮スケールと表面の脱Cr層を溶解除去する必要があり、その必要酸洗減量は概ね約80g/m2程度である。表１において、塩化ニッケルを添加していない実験NoA-1では11%塩酸溶液中で60秒酸洗した場合の酸洗減量は24g/m2であるから、80g/m2の酸洗減量を得るためには、200秒の浸漬時間が必要となる。一方、塩化ニッケルを20g/L添加した実験NoA-6では11%塩酸溶液中で60sec浸漬した場合の酸洗減量は49.8g/m2であるから、80g/m2の酸洗減量を得るためには、96秒の浸漬で必要な酸洗減量を得られ、操業上の通板速度は2倍以上増速することが可能となる。
以上より、本発明では、ステンレス鋼材を酸洗液により酸洗するにあたり、酸洗液として、塩化ニッケルを添加した塩酸溶液を用いることとする。
For example, in the pickling process of stainless steel hot-rolled sheet and hot-rolled annealed sheet, it is necessary to dissolve and remove the black scale and the surface Cr-free layer, and the necessary pickling reduction amount is about 80 g / m 2 is there. In Table 1, in Experiment NoA-1 where no nickel chloride was added, the pickling weight loss when pickled in an 11% hydrochloric acid solution for 60 seconds was 24 g / m 2 , so the pickling weight loss of 80 g / m 2 was reduced. To obtain it, an immersion time of 200 seconds is required. On the other hand, in Experiment NoA-6 where nickel chloride was added at 20 g / L, the pickling weight loss when immersed in an 11% hydrochloric acid solution for 60 seconds was 49.8 g / m 2 , so that a pickling weight loss of 80 g / m 2 was obtained. In this case, the necessary pickling loss can be obtained by dipping for 96 seconds, and the plate speed during operation can be increased more than twice.
From the above, in the present invention, when pickling a stainless steel material with a pickling solution, a hydrochloric acid solution to which nickel chloride is added is used as the pickling solution.
次に、本発明者らは、塩酸溶液に塩化ニッケル添加した場合に酸洗促進作用が有効となる塩酸溶液中に含まれる金属イオンの量について検討を行なった。試験材として、通常の方法で製造したSUS410Lの熱延焼鈍板を用い、ショットブラスト処理による予備脱スケール処理を行ない、次いで、表３に示す条件にて酸洗処理を行い、酸洗減量を調べた。酸洗液は、金属イオンを含まない市販の塩酸試薬に普通鋼、SUS材を種々の割合で溶解し、塩酸溶液中のFe、Cr、Niイオン量を変化させたのち、塩酸濃度を11%に調合した。これらの酸洗液に含まれるFe、Cr、Niの各イオンの分析結果を表３に併せて示す。 Next, the present inventors examined the amount of metal ions contained in a hydrochloric acid solution, in which the pickling promoting action is effective when nickel chloride is added to the hydrochloric acid solution. As a test material, SUS410L hot-rolled annealed plate manufactured by a normal method is used, and pre-descaling treatment is performed by shot blast treatment, and then pickling treatment is performed under the conditions shown in Table 3 to examine pickling loss. It was. Pickling solution is obtained by dissolving ordinary steel and SUS in various proportions in a commercial hydrochloric acid reagent that does not contain metal ions, changing the amount of Fe, Cr, Ni ions in the hydrochloric acid solution, and then adjusting the hydrochloric acid concentration to 11%. It was formulated. Table 3 also shows the analysis results of each ion of Fe, Cr, and Ni contained in these pickling solutions.
表３より、Fe、Cr、Niイオンの総和量が50g/L以上の実験No.C-3、C-4、C-5、C-6では、35g/ m2以上の酸洗減量が得られているのに対し、Fe、Cr、Niイオンの総和量が50g/Lに満たない実験No.C-1とC-2では、20g/ m2以下の酸洗減量しか得られていないことがわかる。これは、塩酸溶液中の金属イオンの総和は少ないが、母材溶解により生じたFeイオンとCrイオンと添加した塩化ニッケルからのNiイオンが、塩素と錯体を形成したために遊離塩素量が少なくなり、酸洗能力が低下したものと考えられる。 Table 3 shows that pickling weight loss of 35 g / m 2 or more was obtained in Experiment Nos. C-3, C-4, C-5, and C-6 where the total amount of Fe, Cr, and Ni ions was 50 g / L or more. In contrast, in Experiment Nos. C-1 and C-2, where the total amount of Fe, Cr, and Ni ions is less than 50 g / L, only pickling reduction of 20 g / m 2 or less is obtained. I understand. This is because the total amount of metal ions in the hydrochloric acid solution is small, but the amount of free chlorine decreases because Fe ions, Cr ions, and Ni ions from the added nickel chloride form a complex with chlorine. It is considered that the pickling ability was lowered.
この実験結果より、塩酸溶液への酸洗促進剤として塩化ニッケルの添加が効果を奏するのは、その塩酸溶液に含まれるFe、Cr、Niの各イオンの総和量が50g/L以上の場合である。 From this experimental result, the addition of nickel chloride as an acid pickling accelerator to a hydrochloric acid solution is effective when the total amount of Fe, Cr, and Ni ions contained in the hydrochloric acid solution is 50 g / L or more. is there.
このように、塩酸溶液へ塩化ニッケルを添加し、さらに塩酸溶液に含まれるFe、Cr、Niの各イオンの総和量が50g/L以上の場合に、酸洗性が大幅に向上するメカニズムについては現状では明らかではないが、前述のように、金属イオンが形成している塩化物の錯体平衡に変化を与えて、遊離塩素量を増加させることによるものと推定している。すなわち、C-1、C-2のように塩酸溶液中の金属イオンの総和が50g/L未満では、錯体平衡バランスが変化せず、添加した塩化ニッケルからのNiイオンによる錯体形成により、遊離塩素量が低下して酸洗性が低下し、一方、C-3〜C-5のように金属イオンの総和が50g/L以上では錯体平衡が変化して遊離塩素量が増加して酸洗性が向上したものと考えられる。 Thus, when nickel chloride is added to a hydrochloric acid solution, and the total amount of Fe, Cr, and Ni ions contained in the hydrochloric acid solution is 50 g / L or more, the mechanism for greatly improving the pickling performance is as follows. Although it is not clear at present, as described above, it is presumed that the amount of free chlorine is increased by changing the complex equilibrium of chloride formed by metal ions. That is, when the total amount of metal ions in the hydrochloric acid solution is less than 50 g / L as in C-1 and C-2, the complex equilibrium balance does not change, and free chlorine is formed by complex formation with Ni ions from the added nickel chloride. On the other hand, when the total amount of metal ions is 50 g / L or more, as in C-3 to C-5, the complex equilibrium changes and the amount of free chlorine increases and the pickling property decreases. Is considered to have improved.
また、塩酸溶液の塩酸濃度は、5%未満では十分な酸洗減量が得られない。よって、塩酸溶液中の全塩素量は50g/L以上とする。また、30%を超える濃度の塩酸溶液で酸洗を行なった場合、ピッティングにより酸洗後の表面性状が劣化する。よって、5〜30%の塩酸溶液を用いるのが好ましい。なお、ここで、塩酸濃度の「%」は重量%を示している。 Further, if the hydrochloric acid concentration of the hydrochloric acid solution is less than 5%, sufficient pickling loss cannot be obtained. Therefore, the total amount of chlorine in the hydrochloric acid solution is 50 g / L or more. In addition, when pickling with a hydrochloric acid solution having a concentration exceeding 30%, surface properties after pickling deteriorate due to pitting. Therefore, it is preferable to use a 5-30% hydrochloric acid solution. Here, “%” of the hydrochloric acid concentration indicates wt%.
本発明では、ステンレス鋼材のスケールおよび表面の脱Cr層を塩酸溶液中で酸洗するに際し、塩化ニッケルを添加することにより、酸洗を促進させる。その効果は50g/L超の添加では飽和傾向にあり、またコストの観点から塩化ニッケルの添加量は1〜50g/Lの範囲にすることが好適である。さらに、塩化ニッケルは、無水物、水和物のいずれを用いてもよい。なお、本発明の塩酸溶液中への塩化ニッケル添加による酸洗促進作用は、酸洗液中の塩素イオンと錯体を形成する金属イオンが存在する場合のみに有効であり、表3の実験結果からFe、Cr、Niイオンの総和量が50g/L以上で酸洗促進効果が認められることから、塩酸溶液中のFe、Cr、Niイオンの総和量を50g/L以上とする。 In the present invention, the pickling is promoted by adding nickel chloride when pickling the scale of the stainless steel material and the de-Cr layer on the surface in a hydrochloric acid solution. The effect tends to saturate when added in excess of 50 g / L, and the addition amount of nickel chloride is preferably in the range of 1 to 50 g / L from the viewpoint of cost. Furthermore, nickel chloride may be either an anhydride or a hydrate. In addition, the pickling promoting action by adding nickel chloride to the hydrochloric acid solution of the present invention is effective only when a metal ion that forms a complex with a chlorine ion in the pickling solution is present. Since the pickling promotion effect is observed when the total amount of Fe, Cr and Ni ions is 50 g / L or more, the total amount of Fe, Cr and Ni ions in the hydrochloric acid solution is set to 50 g / L or more.
なお、本発明の酸洗処理は、鋼材の酸洗前処理、鋼種、さらには熱延板、冷延板によらず、効果を奏するものである。しかし、工業生産する上で酸洗工程を一層効率良く行うためには、脱スケールにおいて一般に行なわれる酸洗前のメカニカルな予備脱スケール処理をすることが好ましい。メカニカルな予備脱スケール処理としては、例えば、ショットブラスト、あるいはベンディングなどである。また、難脱スケール鋼材であるNi含有オーステナイト系ステンレス鋼やMo含有ステンレス鋼においても本発明の効果は得られるものの、フェライト系ステンレス鋼において、本発明はより効果的である。とくにフェライト系ステンレス鋼からなる熱延板または熱延焼鈍板に、予備脱スケール処理を施した後、上記の本発明の酸洗工程を経てステンレス鋼材を製造することが好ましい。 In addition, the pickling process of this invention has an effect irrespective of the pickling pre-processing of steel materials, steel types, and also a hot-rolled sheet and a cold-rolled sheet. However, in order to perform the pickling process more efficiently in industrial production, it is preferable to perform a mechanical preliminary descaling treatment before pickling generally performed in descaling. Examples of the mechanical preliminary descaling process include shot blasting and bending. Moreover, although the effect of this invention is acquired also in Ni containing austenitic stainless steel and Mo containing stainless steel which are difficult-to-deviate scale steel materials, this invention is more effective in ferritic stainless steel. In particular, it is preferable that a hot-rolled sheet or hot-rolled annealed sheet made of ferritic stainless steel is subjected to a pre-descaling treatment, and then a stainless steel material is produced through the pickling step of the present invention described above.
さらに、SUS430鋼などの最終製品での高水準の鋼板表面の白色度、光沢度が要求される製品については、本発明の酸洗の次工程として、硝弗酸などによる仕上酸洗を行なってもよい。 Furthermore, for products that require a high level of whiteness and gloss on the steel sheet surface, such as SUS430 steel, finish pickling with nitric hydrofluoric acid or the like is performed as the next step of the pickling of the present invention. Also good.
以下、本発明を実施例に基づいて具体的に説明する。
通常の方法で製造したSUS410L、SUS430の熱延板および熱延焼鈍板を、表４に示す条件にて酸洗を行ない、ステンレス鋼板を製造し、酸洗減量を調べた。得られた結果を表４に併せて示す。なお、実験方法等は前述した表１の方法と同様である。
Hereinafter, the present invention will be specifically described based on examples.
SUS410L and SUS430 hot-rolled sheets and hot-rolled annealed sheets manufactured by a normal method were pickled under the conditions shown in Table 4 to produce stainless steel sheets, and the pickling weight loss was examined. The obtained results are also shown in Table 4. The experimental method and the like are the same as those in Table 1 described above.
表４に示されるとおり、本発明例であるFe、Cr、Niの各イオンの総和量が50g/L以上で、かつ全塩素量が50g/L以上の塩酸溶液中へ塩化ニッケルを添加した実験No.2、3、4、5、6、11、13、15、16、17、18、19、24は、塩化ニッケルを添加していない実験No.1、10、12、14、23、および塩化ニッケルを添加している場合でも塩酸溶液中のFe、Cr、Niイオンの総和量が本発明範囲外の50g/L未満である実験No.3、4、および全塩素量が50g/L未満である実験No.2、8に比べて、酸洗減量が大幅に優れている。 As shown in Table 4, nickel chloride was added to a hydrochloric acid solution in which the total amount of each ion of Fe, Cr, and Ni, which is an example of the present invention, was 50 g / L or more and the total chlorine amount was 50 g / L or more. Nos. 2, 3, 4, 5, 6, 11, 13, 15, 16, 17, 18, 19, 24 are experimental Nos. 1, 10, 12, 14, 23, and no nickel chloride added. Experiment No. 3 and 4 where the total amount of Fe, Cr and Ni ions in the hydrochloric acid solution is less than 50 g / L outside the scope of the present invention even when nickel chloride is added, and the total chlorine amount is less than 50 g / L Compared with Experiment No. 2 and 8 which are, pickling weight loss is significantly superior.
本発明の酸洗方法は、酸洗処理が効率的に行え、その結果、酸洗時間を従来に比べ、短縮することが可能となるので、ステンレス鋼材に限らず、あらゆる鋼板に対しても利用が可能となりうる。 The pickling method of the present invention can efficiently perform pickling treatment, and as a result, the pickling time can be shortened as compared with the conventional one, so that it is not limited to stainless steel materials and can be used for all steel plates. Can be possible.
Claims (4)
A method for producing a stainless steel material, comprising subjecting a hot-rolled sheet or a hot-rolled annealed sheet made of ferritic stainless steel to preliminary descaling, and then performing pickling according to any one of claims 1 to 3. .
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| JPS63216986A (en) * | 1987-03-03 | 1988-09-09 | Sumitomo Metal Ind Ltd | High-speed pickling method for low cr steel |
| JPH01100287A (en) * | 1987-10-12 | 1989-04-18 | Sumitomo Metal Ind Ltd | Pickling method for low chromium steel strip |
| JPH10330900A (en) * | 1997-06-04 | 1998-12-15 | Nkk Corp | Hot dip plating method for hot rolled steel sheet |
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| JPS63216986A (en) * | 1987-03-03 | 1988-09-09 | Sumitomo Metal Ind Ltd | High-speed pickling method for low cr steel |
| JPH01100287A (en) * | 1987-10-12 | 1989-04-18 | Sumitomo Metal Ind Ltd | Pickling method for low chromium steel strip |
| JPH10330900A (en) * | 1997-06-04 | 1998-12-15 | Nkk Corp | Hot dip plating method for hot rolled steel sheet |
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