JPH09296285A - Method for pickling austenitic stainless hot rolled steel strip - Google Patents
Method for pickling austenitic stainless hot rolled steel stripInfo
- Publication number
- JPH09296285A JPH09296285A JP11177696A JP11177696A JPH09296285A JP H09296285 A JPH09296285 A JP H09296285A JP 11177696 A JP11177696 A JP 11177696A JP 11177696 A JP11177696 A JP 11177696A JP H09296285 A JPH09296285 A JP H09296285A
- Authority
- JP
- Japan
- Prior art keywords
- pickling
- steel strip
- sulfuric acid
- austenitic stainless
- solution
- 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.)
- Withdrawn
Links
Landscapes
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明はオーステナイト系ス
テンレス鋼熱延鋼帯の表面酸化スケールを脱スケールす
る酸洗方法に係わり、酸洗を安定して行うとともに、酸
洗後の表面性状を良好ならしめた熱延板の酸洗方法に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pickling method for descaling the surface oxide scale of austenitic stainless steel hot rolled steel strip, which is capable of performing stable pickling and providing good surface properties after pickling. The present invention relates to a pickling method for a hot rolled sheet.
【0002】[0002]
【従来の技術】ステンレス鋼板および鋼帯の製造方法
は、連続鋳造スラブを熱間圧延し熱延板を製造し、焼鈍
を省略もしくは焼鈍して脱スケールし製品板厚まで冷間
圧延した後仕上げ溶体化処理し酸洗、または光輝焼鈍し
調質圧延する工程からなる。2. Description of the Related Art A method of manufacturing a stainless steel plate and a steel strip is as follows. A continuously cast slab is hot-rolled to manufacture a hot-rolled plate, and annealing is omitted or annealed to descale and cold-rolled to a product sheet thickness, and then finished. It consists of a step of solution treatment followed by pickling, or bright annealing and temper rolling.
【0003】熱間圧延さらに加えて焼鈍などの熱履歴を
受けたオーステナイト系ステンレス鋼熱延板の表面に生
成したスケールを除去する方法としては、一般にショッ
トブラストにより機械的に脱スケールを施した後、硝酸
−弗酸の混酸で酸洗することにより酸洗する方法が広く
採用されている。通常用いられる酸濃度はオーステナイ
ト系ステンレス鋼の場合、硝酸が5〜15%、弗酸が1
〜5%である(「ステンレス鋼便覧」昭和48年版P.
842)。As a method for removing the scale formed on the surface of an austenitic stainless steel hot-rolled sheet which has undergone heat history such as annealing in addition to hot rolling, generally, after mechanical descaling by shot blasting, A method of pickling by pickling with a mixed acid of nitric acid-hydrofluoric acid is widely adopted. In the case of austenitic stainless steel, the commonly used acid concentrations are 5 to 15% nitric acid and 1 hydrofluoric acid.
~ 5% ("Stainless Steel Handbook" 1973 edition P.
842).
【0004】この硝酸−弗酸の混酸による酸洗法は表面
仕上がり状況が良好であるが、NOx ガスを発生するた
め、このガスを処理する高価な設備を必要とする。ま
た、この混酸は酸洗の進行に伴う溶液中へ溶け込みイオ
ンの影響が大きく、溶け込みイオンの増加で能力不足に
なるため、頻繁に液を更新することが必要になる。この
ため、液コストや廃酸処理にコストがかかるという欠点
を有する。さらには酸洗槽の材質として硝酸−弗酸特有
の高価な耐酸材料を必要とし、設備を設置する費用並び
に維持管理する費用の点からも高価な酸洗法である。The pickling method using a mixed acid of nitric acid and hydrofluoric acid has a good surface finish, but it generates NOx gas and requires expensive equipment for treating this gas. Further, this mixed acid is greatly affected by the ions dissolved in the solution as the pickling progresses, and the capacity becomes insufficient due to an increase in the dissolved ions, so that the liquid needs to be frequently renewed. Therefore, there is a drawback that liquid cost and waste acid treatment are expensive. Furthermore, an expensive acid-resistant material peculiar to nitric acid-hydrofluoric acid is required as the material for the pickling tank, and it is an expensive pickling method from the viewpoint of equipment installation costs and maintenance costs.
【0005】一方、フェライト系ステンレス鋼について
は硫酸酸洗法が適用実施されている。この硫酸酸洗法は
NOx ガスを発生せず、ガス処理設備が不要である。ま
た、酸洗の進行に伴う溶液中への溶け込みイオンの影響
が小さく、液コストや廃酸処理が安価である。さらには
酸洗槽の耐酸材料として安価な材料で充分である。この
ようなことから、硝酸−弗酸の混酸に代わる酸洗法とし
て硫酸を基本酸洗溶液とした酸洗性能の優れた酸洗方法
が切望されていた。On the other hand, the sulfuric acid pickling method is applied to ferritic stainless steel. This sulfuric acid pickling method does not generate NOx gas and requires no gas treatment equipment. Further, the effect of dissolved ions in the solution accompanying the progress of pickling is small, and liquid cost and waste acid treatment are inexpensive. Furthermore, an inexpensive material is sufficient as an acid resistant material for the pickling tank. From this, there has been a strong demand for a pickling method which uses sulfuric acid as a basic pickling solution and has excellent pickling performance as an alternative to the nitric acid-hydrofluoric acid mixed acid.
【0006】このような硫酸溶液を使ったオーステナイ
ト系ステンレス熱延鋼帯への酸洗法としては、例えば特
公昭61−25783号公報において、ショットブラス
ト後に硫酸処理し、酸洗主溶液として硫酸第二鉄−硫酸
溶液による酸洗を行い、後処理として硝酸中で酸洗する
か、あるいは塩酸後硝酸中で酸洗する方法がある。しか
しながら、この酸洗法を適用しても、硫酸第二鉄−硫酸
の操業濃度範囲が狭いため、範囲外になることが頻発
し、酸洗が全く不能な状態になった。また、酸洗が充分
に行われた場合も酸洗後の表面に3〜7μm程度の径で
深さも同様程度の孔食が生じ、引き続き行われる冷延で
修復することなく製品板で疵として残存し、マクロ的に
は白濁化した鋼板となる問題があった。As a method of pickling an austenitic stainless hot-rolled steel strip using such a sulfuric acid solution, for example, in Japanese Patent Publication No. 61-25783, a sulfuric acid treatment is performed after shot blasting, and a sulfuric acid first solution is used as the pickling main solution. There is a method in which pickling with a diiron-sulfuric acid solution is performed, and as a post-treatment, pickling is performed in nitric acid or hydrochloric acid and then nitric acid. However, even if this pickling method is applied, the operating concentration range of ferric sulfate-sulfuric acid is narrow, so that it often goes out of the range, making pickling impossible. Even when the pickling is sufficiently performed, pitting corrosion of a diameter of about 3 to 7 μm and a similar depth occurs on the surface after the pickling, and the product plate is not damaged by subsequent cold rolling and has a flaw. There was a problem that it remained and became a macroscopically opaque steel plate.
【0007】また、酸洗時に通電する電解酸洗法も検討
されており、例えば特開平1−316500号公報にお
いては硫酸およびCr6+イオンを含有する溶液中で、熱
延鋼帯を陰極に通電することによって高速溶解を得て酸
洗する方法が開示されている。しかしながら、この酸洗
法においては大電流を酸洗中に継続して通電する必要が
あり、また、Cr6+イオンを溶液中に含有させるため高
価な化合物を添加するため、通電の設備費と共に電力や
溶液等に要する操業コストを増大させる問題があり、安
価な酸洗法の開発が望まれていた。Also, an electrolytic pickling method in which electricity is applied during pickling has been studied. For example, in JP-A-1-316500, a hot-rolled steel strip is used as a cathode in a solution containing sulfuric acid and Cr 6+ ions. A method of obtaining high-speed dissolution by applying electricity and pickling is disclosed. However, in this pickling method, it is necessary to continuously apply a large current during pickling, and since an expensive compound is added to contain Cr 6+ ions in the solution, the equipment cost for energizing is increased. There is a problem that the operating cost required for electric power, solution, etc. is increased, and development of an inexpensive pickling method has been desired.
【0008】[0008]
【発明が解決しようとする課題】本発明はオーステナイ
ト系ステンレス熱延板の安価な酸洗方法として、硫酸溶
液を用い、安定した酸洗操業と酸洗後の表面性状を良好
にする酸洗法を可能ならしめるもので、これにより酸液
コストおよび設備費が安価で高品質なオーステナイト系
ステンレス鋼薄板製造を可能にすることを目的とするも
のである。SUMMARY OF THE INVENTION The present invention relates to an inexpensive pickling method for hot-rolled austenitic stainless steel sheets by using a sulfuric acid solution to stabilize pickling operations and improve the surface properties after pickling. It is an object of the present invention to make it possible to manufacture a high-quality austenitic stainless steel thin plate with low acid solution cost and equipment cost.
【0009】[0009]
【課題を解決するための手段】本発明者等は、硫酸溶液
を用いオーステナイト系ステンレス熱延鋼帯を酸洗する
方法について鋭意検討を加えた結果、硫酸酸洗中に酸洗
が進行しなくなることと硫酸酸洗後の表面に生じる孔食
は、硫酸第二鉄からのFeイオンや、酸洗の進行に伴っ
て硫酸溶液中に濃化するFeイオン、Crイオン、Ni
イオンが影響しており、これらのイオンによって生ずる
不動態化が原因であることをつきとめた。さらに、電気
的に鋼帯を陰極とし通電することで活性溶液を容易に開
始させ、デスケーリングのための酸洗時間を短縮し、酸
洗後の表面粗さを小さくし、なおかつ孔食発生を防止で
きることを見いだし、その知見に基づいて本発明を完成
させるに至った。Means for Solving the Problems The inventors of the present invention have made earnest studies on a method of pickling an austenitic stainless hot-rolled steel strip using a sulfuric acid solution, and as a result, pickling does not proceed during sulfuric acid pickling. That is, pitting corrosion that occurs on the surface after sulfuric acid pickling is caused by Fe ions from ferric sulfate, Fe ions, Cr ions, and Ni that are concentrated in the sulfuric acid solution as pickling progresses.
It was determined that the ions were affected and that the passivation caused by these ions was the cause. Furthermore, by electrically energizing the steel strip as the cathode, the active solution can be easily started, the pickling time for descaling can be shortened, the surface roughness after pickling can be reduced, and pitting corrosion can be prevented. They have found that they can be prevented, and have completed the present invention based on their findings.
【0010】すなわち本発明は、オーステナイト系ステ
ンレス鋼スラブを熱間圧延して得られた熱延鋼帯を、硫
酸濃度が50〜600g/l(リットル)、温度50〜
120℃の硫酸溶液中で鋼帯を陰極とし、該陰極に対向
して設けられた陽極との間に電流密度30〜200A/
dm2 を通電して酸洗を開始させることを特徴とするオー
ステナイト系ステンレス熱延鋼帯の酸洗方法である。That is, according to the present invention, the hot rolled steel strip obtained by hot rolling an austenitic stainless steel slab has a sulfuric acid concentration of 50 to 600 g / l (liter) and a temperature of 50 to 600 g / l.
A steel strip is used as a cathode in a sulfuric acid solution at 120 ° C., and a current density between the anode and the anode provided facing the cathode is 30 to 200 A /
A method for pickling an austenitic stainless hot rolled steel strip is characterized in that dm 2 is energized to start pickling.
【0011】[0011]
【発明の実施の形態】酸洗が進行しFeイオン、Crイ
オンやNiイオンが酸洗溶液中に増加すると、メカニカ
ルデスケーリングした鋼板を浸漬しただけでは酸洗が開
始しないことが判明した。このため、Cr含有量17%
以下のフェライト系ステンレス鋼か普通鋼であらかじめ
活性溶解させた材料を接触させて酸洗を開始させること
で実験を行った。ショットブラスト平均粒径400μ
m、投射速度50m/sec、単位面積当たりの投射量を7
5kg/m2 としてメカニカルデスケーリングした後の鋼
帯を300g/l(リットル)H2 SO4 にFeイオ
ン、Crイオン、Niイオンの溶け込み総量を50g/
lとした90℃の溶液中で酸洗した。DESCRIPTION OF THE PREFERRED EMBODIMENTS It has been found that when Fe pickling, Cr ions and Ni ions increase in the pickling solution as pickling progresses, pickling does not start just by immersing the mechanically descaled steel sheet. Therefore, Cr content is 17%
An experiment was carried out by bringing the following ferritic stainless steels or ordinary steels into which active materials were previously dissolved and bringing them into contact with each other to start pickling. Shot blast average particle size 400μ
m, projection speed 50 m / sec, projection amount per unit area 7
The steel strip after mechanical descaling at 5 kg / m 2 is 300 g / l (liter) H 2 SO 4 and the total amount of Fe, Cr, and Ni ions dissolved is 50 g / l.
It was pickled in a 90 ° C. solution designated as 1.
【0012】その結果、デスケーリングに要する酸洗時
間は270sec 以上必要であり、酸洗後の表面粗さはR
maxで50μmを超える粗さになり従来の硝酸−弗酸
の混酸による酸洗表面の値の2倍を越えた。さらに酸洗
表面には3〜7μm程度の直径で深さも同様程度の孔食
が生じていた。これらを冷間圧延後光輝焼鈍し調質圧延
後、製品表面ではかぶさり状の疵とマクロ的には白濁し
た表面になり、従来の硝弗酸酸洗で製造した場合に得ら
れる光沢の良い鏡面とは著しく相違した表面になった。As a result, the pickling time required for descaling is 270 seconds or more, and the surface roughness after pickling is R.
The maximum roughness was more than 50 μm, which was more than twice the value of the conventional pickled surface with nitric acid-hydrofluoric acid. Furthermore, the pickled surface had pitting corrosion with a diameter of 3 to 7 μm and a similar depth. After cold rolling and bright annealing and temper rolling, the product surface has a scab-like flaw and a macroscopically opaque surface, which gives a glossy mirror surface obtained by conventional nitric hydrofluoric acid pickling. The surface was markedly different from.
【0013】このような酸洗の不活性、酸洗時間の長時
間化、酸洗後の表面粗さや孔食発生はいずれも問題であ
る。酸洗の活性溶解を開始させるために通電による方法
を検討し、電流密度と活性溶解の発生頻度の対応を調べ
る実験を行った。図1に示すように、電流密度が30A
/dm2 以上で活性溶解が安定して生じる。さらに、図
2、図3で、デスケーリング完了時間やデスケーリング
完了時点での表面粗さの結果を示すように、30A/dm
2 以上の電流を3sec 以上加えることでデスケーリング
に必要な酸洗時間は90sec 以内に短縮し、表面粗さも
Rmax25μm以下になり、さらに高電流密度化と通
電時間の長時間化で20μm以下にも調整できる。また
これら30A/dm2 以上通電した表面には孔食発生は認
められなかった。Such inactivation of pickling, prolongation of pickling time, surface roughness and pitting corrosion after pickling are all problems. The method of applying current to start the active dissolution of pickling was examined, and an experiment was conducted to examine the correspondence between the current density and the frequency of active dissolution. As shown in FIG. 1, the current density is 30 A
/ Dm 2 or more, active dissolution occurs stably. Furthermore, as shown in FIGS. 2 and 3, the result of the surface roughness at the time of completion of descaling and the time of completion of descaling is 30 A / dm.
By applying a current of 2 or more for 3 seconds or more, the pickling time required for descaling can be shortened to 90 seconds or less, and the surface roughness can be reduced to Rmax 25 μm or less, and even 20 μm or less due to higher current density and longer energization time. Can be adjusted. Further, no pitting corrosion was observed on the surface to which current of 30 A / dm 2 or more was applied.
【0014】このようにして得られた表面粗さが25μ
m以下の酸洗板を3mm厚から0.7mm厚まで冷間圧延し
た後に光輝焼鈍し調質圧延した後、製品としての表面性
状を調べた。この結果、光沢の良い鏡面が製造できるこ
とが分かった。浸漬酸洗や30A/dm2 未満の電流密度
で酸洗した表面粗さの25μmを越えた、表面に孔食を
有する酸洗板を同様に冷延し光輝焼鈍し調質圧延して製
造したが、マクロ的には白濁した表面となり、製品表面
としては問題のある表面となった。The surface roughness thus obtained is 25 μm.
The pickled sheet of m or less was cold-rolled from 3 mm to 0.7 mm in thickness, bright-annealed and temper-rolled, and then the surface properties of the product were examined. As a result, it was found that a glossy mirror surface can be manufactured. A pickled plate having a surface roughness of more than 25 μm, which has been subjected to immersion pickling or pickling at a current density of less than 30 A / dm 2 and having pitting corrosion on the surface, was similarly cold-rolled, bright-annealed and temper-rolled. However, it became a cloudy surface macroscopically, and became a problem surface as a product surface.
【0015】このような酸洗の初期に陰極電流を付与す
ることで活性溶解が容易に発生し、酸洗時間の短縮、表
面粗さを低減し孔食発生を防止できるのは、不動態化し
やすいFeイオン、Crイオン、Niイオンを含む溶液
中で鋼帯表面電位を活性溶解電位に変化させ、この電位
では鋼帯表面が均一に活性溶解するためであると考えら
れる。By applying a cathodic current in the initial stage of such pickling, active dissolution easily occurs, the pickling time is shortened, the surface roughness is reduced, and the occurrence of pitting corrosion can be prevented. This is considered to be because the surface potential of the steel strip is changed to the active dissolution potential in a solution containing easy Fe ions, Cr ions and Ni ions, and the surface of the steel strip is uniformly active dissolved at this potential.
【0016】次に限定理由について説明する。陰極電流
密度については図1、図2、図3で示したように陰極電
流として30A/dm2 以上付与すると活性溶解発生率を
安定化し、酸洗時間を短縮し、酸洗後の表面粗さや孔食
を軽減できる。これらの効果は電流密度を上げるほど有
効に作用するが、200A/dm2 を超えると液温の急激
な上昇が生じ、温度管理がむつかしく表面も過酸洗状態
となるので30〜200A/dm2 とした。通電方法は鋼
板と溶液中で対向して平行に設けられたコイル巾と同じ
電極巾で、長さ300〜500mmの一対の電極間に直流
電源を接続して間接通電により電流を流すことによって
得られる。また、片方の電極をコンダクターロールを用
いることによって直接鋼帯表面に通電することによって
も得られる。特に間接通電の場合は鋼帯表面が陽極にな
る極の電流密度を80A/dm2 以下にするように制限す
る必要がある。これは80A/dm2 を超えて鋼帯に陽極
電流を流すと、陽極通電位置の鋼帯を活性溶解電位から
不動態化電位に移行させ活性溶解を停止する作用があ
り、安定した酸洗が得られないためである。Next, the reason for limitation will be described. Regarding the cathode current density, as shown in FIG. 1, FIG. 2 and FIG. 3, when a cathode current of 30 A / dm 2 or more is applied, the active dissolution generation rate is stabilized, the pickling time is shortened, and the surface roughness after pickling and Can reduce pitting corrosion. These effects act effectively higher the current density, but, 200A / dm 2 by weight, the rapid rise of liquid temperature occurs, 30~200A / dm 2 and the surface temperature control Mutsukashiku also becomes excessive pickling conditions And The energization method is obtained by connecting a direct current power supply between a pair of electrodes with a length of 300 to 500 mm and flowing a current through indirect energization with the same electrode width as the coil width provided in parallel with the steel plate facing the solution. To be Further, it can also be obtained by directly supplying electricity to the surface of the steel strip by using one of the electrodes with a conductor roll. Particularly in the case of indirect energization, it is necessary to limit the current density of the electrode whose surface is the steel strip to be 80 A / dm 2 or less. This is because when an anodic current is passed through the steel strip exceeding 80 A / dm 2 , the steel strip at the current-carrying position of the anode has a function of shifting from the active dissolution potential to the passivation potential to stop the active dissolution, and stable pickling can be performed. This is because it cannot be obtained.
【0017】H2 SO4 溶液については、酸洗初期の電
流密度を確保すればFeイオン、Crイオン、Niイオ
ンを多く含有するH2 SO4 溶液中でも問題なく酸洗が
進行し、H2 SO4 濃度が50〜600g/lの範囲で
有効である。H2 SO4 の濃度増は高速酸洗には有効で
50g/l以上で効果を発揮するが600g/lを超え
ると飽和する。また、操業が安定的に行うことができる
のは100g/l以上400g/l以下の範囲である。
なお、酸洗温度は沸点(120℃)までの範囲で高温ほ
ど高速酸洗が可能であるが50℃未満では、溶解能力が
小さくなるので50〜120℃とした。[0017] For the H 2 SO 4 solution, if secure the pickling initial current density Fe ions, Cr ions, the pickling without problems H 2 SO 4 solution containing a large amount of Ni ions proceeds, H 2 SO 4 Effective in a concentration range of 50 to 600 g / l. Increasing the concentration of H 2 SO 4 is effective for high-speed pickling and is effective at 50 g / l or more, but becomes saturated when it exceeds 600 g / l. Further, the stable operation can be performed in the range of 100 g / l or more and 400 g / l or less.
It should be noted that the pickling temperature is within the range up to the boiling point (120 ° C.), so that the higher the temperature, the higher the speed of the pickling is possible, but if it is less than 50 ° C., the dissolving ability becomes small, so it was set to 50 to 120 ° C.
【0018】この酸洗法においてもメカニカルデスケー
リングの作用は重要で、不充分な場合は酸洗開始に悪影
響を及ぼすので充分なメカニカルデスケーリングを必要
とする。ショットブラスト、砂鉄粒を含有した高圧水吹
き付け法、砥粒ブラシにより研削する方法、テンション
レベラー等を用い行う。Also in this pickling method, the effect of mechanical descaling is important, and when it is insufficient, it adversely affects the start of pickling, so sufficient mechanical descaling is required. Shot blasting, high pressure water spraying containing iron sand particles, grinding with an abrasive brush, tension leveler, etc. are used.
【0019】H2 SO4 酸洗直後の表面には黒い酸洗生
成物があり、デスケの判定を困難にするため、10〜1
50g/l(リットル)HNO3 および10〜400g
/l(リットル)HCl,50〜100℃の混合溶液中
に浸漬あるいはスプレーし、白色化する必要がある。白
色化にはHNO3 量は10g/l未満では不足し、15
0g/lを超えると表面粗さを増大させる。又HNO3
に共存するHCl量は高速白色化には有効で、10g/
l以上で効果を発揮するが400g/lを超えると効果
が飽和する。温度は100℃を超えると表面の肌荒れを
生じ、50℃未満では白色化効果が小さい。高速白色化
の点と操業上の観点からは80〜90℃が望ましい。There is a black pickling product on the surface immediately after the H 2 SO 4 pickling.
50 g / l (liter) HNO 3 and 10-400 g
It is necessary to immerse or spray in a mixed solution of 1 / l (liter) HCl and 50 to 100 ° C. to whiten it. If the amount of HNO 3 is less than 10 g / l, it is insufficient for whitening.
When it exceeds 0 g / l, the surface roughness is increased. Also HNO 3
The amount of HCl coexisting with is effective for high-speed whitening and is 10 g /
The effect is exhibited at 1 or more, but the effect is saturated at more than 400 g / l. If the temperature exceeds 100 ° C, the surface becomes rough, and if it is less than 50 ° C, the whitening effect is small. From the viewpoint of high speed whitening and operation, 80 to 90 ° C is desirable.
【0020】また、白色化には50〜200g/l(リ
ットル)HNO3 および10〜250g/l(リット
ル)HF、40〜100℃の混合溶液中に浸漬あるいは
スプレーし、白色化することも有用である。白色化には
HNO3 量は50g/l未満では不足し、200g/l
を超えると表面粗さを増大させる。又HNO3 に共存す
るHF量は高速白色化には有効で、10g/l以上で効
果を発揮するが250g/lを超えると効果が飽和す
る。温度は100℃を超えると表面の肌荒れを生じ、4
0℃未満では白色化効果が小さい。高速白色化の点と操
業上の観点からは70〜90℃が望ましい。For whitening, it is also useful to whiten by dipping or spraying in a mixed solution of 50 to 200 g / l (liter) HNO 3 and 10 to 250 g / l (liter) HF at 40 to 100 ° C. Is. HNO 3 amount of less than 50 g / l is insufficient for whitening, and 200 g / l
When it exceeds, the surface roughness is increased. The amount of HF coexisting with HNO 3 is effective for high-speed whitening, and the effect is exhibited at 10 g / l or more, but the effect is saturated when it exceeds 250 g / l. When the temperature exceeds 100 ° C, the surface becomes rough, and 4
If it is less than 0 ° C, the whitening effect is small. From the viewpoint of high-speed whitening and operation, 70 to 90 ° C is desirable.
【0021】[0021]
【実施例】本発明の実施例を次に説明する。1200℃
に加熱した250mm厚、1000mm巾、6000mm長の
スラブを熱間圧延し、30mm厚、1100℃で粗圧延を
終了し、引き続き7パスで3mm厚980℃で熱間圧延を
終了し、450℃で巻き取った、表面に熱間で生成した
スケールのある18%Cr−8%Ni鋼(SUS30
4)をショットブラスト、砂鉄粒を含んだ高圧水吹き付
け法、砥粒ブラシにより研削する方法およびテンション
レベラーによりメカニカルデスケーリングし、(Feイ
オン+Crイオン+Niイオン)濃度の異なるH2 SO
4 溶液中に浸漬し、酸洗初期に通電酸洗し酸洗した後の
デスケーリング時間、表面凹凸、冷延し光輝焼鈍し調質
圧延した後の製品表面性状について調査した結果を図1
に示した。なお、すべての条件はH2 SO4 後120g
/l(リットル)HNO3 、60g/l(リットル)H
Cl、70℃,20sec 浸漬し白色化した後を酸洗後と
して評価した。Embodiments of the present invention will be described below. 1200 ° C
The slab of 250mm thickness, 1000mm width, and 6000mm length heated to 30mm thickness is finished by 30mm thickness, rough rolling at 1100 ° C, then 7mm by 3mm thickness at 980 ° C and then 450 ° C. Rolled 18% Cr-8% Ni steel with hot-generated scale on the surface (SUS30
4) is subjected to shot blasting, a high-pressure water spraying method including sand iron particles, a method of grinding with an abrasive grain brush, and mechanical descaling by a tension leveler, and H 2 SO having different (Fe ion + Cr ion + Ni ion) concentrations.
Immersed in 4 solution, descaling time after energization pickled pickled pickling initial, surface irregularities, the results of investigating the product surface texture after rolling cold rolled bright-annealed temper FIG
It was shown to. All conditions were 120g after H 2 SO 4
/ L (liter) HNO 3 , 60 g / l (liter) H
After being soaked in Cl, 70 ° C., 20 seconds for whitening, evaluation was performed after pickling.
【0022】鋼帯を陰極とし、該陰極に対向して設けら
れた陽極との間に電流密度30〜200A/dm2 を通電
して酸洗を開始させることで、酸洗時間を短時間化し、
酸洗後の表面粗さを小さくし、孔食発生をなくし、冷延
し光輝焼鈍して調質圧延した後の製品表面性状について
良好な結果が得られることを確認した。The pickling time can be shortened by using the steel strip as a cathode and passing a current density of 30 to 200 A / dm 2 between the cathode and the anode provided facing the cathode to start pickling. ,
It was confirmed that the surface roughness after pickling was reduced, pitting corrosion was eliminated, and good results were obtained for the product surface properties after cold rolling, bright annealing and temper rolling.
【0023】[0023]
【表1】 [Table 1]
【0024】[0024]
【発明の効果】本発明はオーステナイト系ステンレス鋼
薄板を製造するに際し、安価な硫酸酸洗においても安定
した酸洗と酸洗後の表面性状を良好にする酸洗法を可能
にし、冷延焼鈍後の製品板の表面として高品質な光沢の
良い鏡面を得ることを可能ならしめたもので、その工業
的効果は甚大である。INDUSTRIAL APPLICABILITY The present invention enables stable pickling even in inexpensive sulfuric acid pickling and a pickling method for improving the surface quality after pickling when producing an austenitic stainless steel thin plate, and cold rolling annealing is performed. This is what makes it possible to obtain a high-quality mirror surface with high gloss as the surface of the later product plate, and its industrial effect is enormous.
【図1】SUS304の熱延鋼帯にショットブラスト平
均粒径400μm、投射速度50m/sec、単位面積当た
りの投射量を75kg/m2 としてメカニカルデスケーリ
ングした後の鋼帯を、300g/l(リットル)H2 S
O4 でFeイオン、Crイオン、Niイオンの溶け込み
総量を50g/lとした90℃の溶液中で通電し、電流
密度と活性溶解発生率との関係を示す図。FIG. 1 shows a 300 g / l steel strip after mechanical descaling on a hot rolled steel strip of SUS304 with a shot blasting average grain size of 400 μm, a projection speed of 50 m / sec, and a projection amount per unit area of 75 kg / m 2. Liter) H 2 S
O 4 in Fe ions, Cr ions, the penetration amount of Ni ions energized in a solution of 90 ° C. which was 50 g / l, diagram showing the relationship between the current density and the active dissolution incidence.
【図2】図1と同じ条件のショットブラストと酸洗溶液
を用い酸洗した場合の酸洗初期に通電した電流密度と通
電時間とデスケーリング完了時間との関係を示す図であ
り、30A/dm2 未満を含めてすべて活性溶解を開始し
た酸洗についての結果を示している。FIG. 2 is a diagram showing a relationship between a current density, an energization time, and a descaling completion time, which are supplied with electricity in the initial stage of pickling when pickling using a shot blasting and pickling solution under the same conditions as in FIG. The results are shown for pickling in which all active solubilization including less than dm 2 was started.
【図3】図2に対応したデスケーリング完了直後の表面
粗さを電流密度と通電時間に対して示したものである。FIG. 3 shows surface roughness immediately after completion of descaling corresponding to FIG. 2 with respect to current density and energization time.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 田所 裕 福岡県北九州市戸畑区飛幡町1番1号 新 日本製鐵株式会社八幡製鐵所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Tadokoro No. 1-1 Tobata-cho, Tobata-ku, Kitakyushu, Fukuoka Prefecture Nippon Steel Corporation Yawata Works
Claims (1)
熱間圧延して得られた熱延鋼帯を、硫酸濃度が50〜6
00g/l(リットル)、温度50〜120℃の硫酸溶
液中で鋼帯を陰極とし、該陰極に対向して設けられた陽
極との間に電流密度30〜200A/dm2 を通電して酸
洗を開始させることを特徴とするオーステナイト系ステ
ンレス熱延鋼帯の酸洗方法。1. A hot rolled steel strip obtained by hot rolling an austenitic stainless steel slab has a sulfuric acid concentration of 50 to 6
A steel strip is used as a cathode in a sulfuric acid solution of 00 g / l (liter) and a temperature of 50 to 120 ° C., and a current density of 30 to 200 A / dm 2 is passed between the steel strip and an anode provided facing the cathode to generate an acid. A method for pickling an austenitic stainless hot-rolled steel strip, which comprises starting washing.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11177696A JPH09296285A (en) | 1996-05-02 | 1996-05-02 | Method for pickling austenitic stainless hot rolled steel strip |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11177696A JPH09296285A (en) | 1996-05-02 | 1996-05-02 | Method for pickling austenitic stainless hot rolled steel strip |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH09296285A true JPH09296285A (en) | 1997-11-18 |
Family
ID=14569887
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11177696A Withdrawn JPH09296285A (en) | 1996-05-02 | 1996-05-02 | Method for pickling austenitic stainless hot rolled steel strip |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH09296285A (en) |
-
1996
- 1996-05-02 JP JP11177696A patent/JPH09296285A/en not_active Withdrawn
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