JPS6261113B2 - - Google Patents
Info
- Publication number
- JPS6261113B2 JPS6261113B2 JP8206082A JP8206082A JPS6261113B2 JP S6261113 B2 JPS6261113 B2 JP S6261113B2 JP 8206082 A JP8206082 A JP 8206082A JP 8206082 A JP8206082 A JP 8206082A JP S6261113 B2 JPS6261113 B2 JP S6261113B2
- Authority
- JP
- Japan
- Prior art keywords
- salt bath
- scale
- added
- pickling
- amount
- 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.)
- Expired
Links
- 150000003839 salts Chemical class 0.000 claims description 29
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 21
- 238000005554 pickling Methods 0.000 claims description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 5
- 239000011780 sodium chloride Substances 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 description 8
- 239000011651 chromium Substances 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 229910001220 stainless steel Inorganic materials 0.000 description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 5
- 229910052804 chromium Inorganic materials 0.000 description 5
- 230000001590 oxidative effect Effects 0.000 description 5
- 239000010935 stainless steel Substances 0.000 description 5
- 238000000137 annealing Methods 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000007800 oxidant agent Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 150000002823 nitrates Chemical class 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 235000013372 meat Nutrition 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/28—Cleaning or pickling metallic material with solutions or molten salts with molten salts
- C23G1/32—Heavy metals
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Description
本発明は高クロム含有鋼のような難デスケーリ
ング性のステンレス鋼、耐熱鋼などの表面に生成
する酸化スケールを酸洗によつて除去する際に使
用される酸化スケール改質用溶融塩浴に関するも
のである。
ステンレス鋼板は焼鈍又は熱間圧延する際に板
の表面に酸化スケールを生成するので、通常は硝
酸や弗化水素酸を含む硝酸液による酸洗により除
去されている。この場合、板の表面に生じた緻密
な酸化スケールを直接酸洗によつて除去しようと
すると酸化スケールを除去するのに長時間を要
し、かつ表面が肌荒れした製品となる欠陥を有し
ている。このため、通常は酸洗の前に水酸化ナト
リウムを主成分とする溶融塩浴中に浸漬して酸化
スケールの改質を行なつている。これにより酸化
度の不均一なスケールは、さらに酸化されて酸に
溶けやすい形に変わり短時間の酸洗によつて除去
されて表面状態のよい製品ができると同時に酸洗
による肉減りも最少限に抑えられるのである。こ
のような酸化スケール改質用塩浴としては従来よ
り“コーリンNo.１ソルト”（NaNO330〜35％、
Nacl5〜10％、残部NaOH及び不純物）や“DGS
ソルト“（NaNO39〜15％、NaCl5〜15％、KOH8
〜20％、残部NaOH及び不純物）と呼ばれる塩浴
が知られている。しかしながら、これらの塩浴は
通常のステンレス鋼（例えば18Cr―8Niステンレ
ス鋼）の焼鈍によつて生じた酸化スケールに対し
ては充分な効果を示すが、クロム含有量が20％以
上のステンレス鋼、耐熱鋼の焼鈍或は熱間圧延に
よつて生じた酸化スケールに対しては充分な効果
を示さず、後工程の酸洗によつて酸化スケールが
除去できなかつたり、もしできたとしても長時間
を要したり肌荒れや肉減りの大きな製品ができる
欠点を有している。
このように、所謂難デスケーリング性の高Cr
含有鋼に生成される酸化スケールに対して、前記
の従来の溶融塩浴が充分な機能を発揮し得ないの
は、これらの塩浴の酸化力が不足しているためと
推測されたので、NaNO3、KNO3よりもさらに強
力な酸化剤であるKMnO4又はNaMnO4の如き過
マンガン酸塩を添加した塩浴について検討した結
果、本発明に至つたもので、重量％で、
NaNO3、KNO3の１種又は２種 ５〜40％、
KMnO4、NaMnO4の１種又は２種 0.5〜10％、
また必要に応じNacl5〜15％、KOH5〜20％の一
方又は双方を含有させ残部NaOH及び不純物より
成るものである。
本発明は上記のような組成を有し、従来のもの
に比し酸化力が強いので次のような効果を有す
る。
(1) 前述の高クロム含有鋼の場合には、Cr含有
量の高い緻密な酸化スケール（Cr2O3を主体と
し酸に不溶性）が生成するので、これを過マン
ガン酸塩の強力な酸化力によつて酸に可溶なス
ケール（CrO3主体）に変えると同時に酸化ス
ケールの緻密さをも減少し酸洗液が地金にまで
浸透するようにして地金の溶解により酸洗を進
行せしめる。
(2) 熱間圧延によつて生じたスケールは厚いの
で、酸化力の弱い従来の溶融塩浴ではスケール
の改質に長時間を要してコストアツプとなる
が、本発明塩浴によれば比較的短時間でスケー
ルの改質が可能となる。
(3) 塩浴の温度を下げても従来のものと同等以上
の酸化力をもつており、省エネルギーにも役立
つている。
次に本発明にかゝる塩浴の成分を限定した理由
を述べて併せて本発明の特徴について説明する。
NaNO3、KNO3：酸化剤として働き、酸化度の
不充分なスケールを酸化するためのものである。
その最適添加量は処理しようとする材料の種類や
過マンガン酸塩の添加量によつても異なるが40％
以上の添加ではNaNO3、KNO3自体が分解し易く
なるので40％以下とした。また過マンガン酸塩が
添加してあればNaNO3及び（又は）KNO3は添加
しなくても塩浴の脱スケール能はある程度保たれ
るが、過マンガン酸塩は硝酸塩に比べて高価なの
で経済的な見地からは硝酸塩を５％以上添加し、
これに0.5〜10％の過マンガン酸塩を添加するの
が望ましい。
KMnO4、NaMnO4：NaNO3、KNO3と共に酸化
剤として働き酸化度の不充分なスケールを強力に
酸化するためのものであり、添加量が増すほど溶
融塩浴の酸化力は増すが、硝酸塩が前述のように
存在する場合には0.5％以上の添加で充分本発明
の目的を達成する。また10％以上の添加では過マ
ンガン酸自体が分解し易くなるので添加量は0.5
〜10％とする。
Nacl：脱スケール能には直接影響を及ぼさな
いが５％以上添加すれば溶融塩浴の粘度を下げ、
浸漬された板に付着して浴外に持ち出される浴の
量（持ち出し量）を減ずる効果を有する（特に浴
の温度が480℃と比較的高温の場合）。しかし15％
以上の添加ではかえつて持ち出し量が増加するの
で添加量は５〜15％とする。
KOH：脱スケール能には直接的な影響はない
が５％以上添加すれば溶融塩浴の持ち出し量を減
少させる効果を有する。しかし20％以上の添加で
はかえつて持ち出し量が増えるので添加量は５〜
20％とする。
NaOH：酸化スケール中のクロムを酸に可溶な
６価のクロムに変えるために必要なアルカリであ
り、KOHとの合計量が35％以上であれば充分で
ある。
次に実施例によつて本発明の効果を説明する。
下記第１表に示す組成の供試材（試験片のサイ
ズ：1.0（ｔ）×30×50mm）を、第２表に示す焼鈍
条件にて焼鈍し試験片表面に酸化スケールを生成
させ、第３表に示す組成の溶融塩浴に10秒間浸漬
した後浴から引き上げ、水中に投入して溶融塩を
溶解し、次いで第４表に示す酸洗条件で酸洗した
後試験片表面の脱スケール状態を光学顕微鏡で観
察した結果を第５表に示す。
The present invention relates to a molten salt bath for modifying oxide scales, which is used to remove oxide scales generated on the surfaces of stainless steels, heat-resistant steels, etc. that are difficult to descale, such as high chromium-containing steels, by pickling. It is something. When stainless steel sheets are annealed or hot rolled, oxide scale is generated on the surface of the sheet, so it is usually removed by pickling with a nitric acid solution containing nitric acid or hydrofluoric acid. In this case, if you try to remove the dense oxide scale that has formed on the surface of the board by direct pickling, it will take a long time to remove the oxide scale, and the surface will be rough. There is. For this reason, before pickling, the oxide scale is usually modified by immersing it in a molten salt bath containing sodium hydroxide as the main component. As a result, scales with uneven oxidation degree are further oxidized into a form that is easily soluble in acid, and are removed by a short pickling process, resulting in a product with a good surface condition, and at the same time, the loss of thickness due to pickling is minimized. This can be suppressed to . As a salt bath for such oxidation scale modification, "Colin No. 1 Salt" (NaNO 3 30-35%,
(NaCl5-10%, balance NaOH and impurities) and “DGS”
Salt “( NaNO3 9-15%, NaCl5-15%, KOH8
~20%, balance NaOH and impurities) salt baths are known. However, these salt baths are sufficiently effective against oxidized scales caused by annealing ordinary stainless steel (e.g. 18Cr-8Ni stainless steel), but they are not effective against oxidation scale caused by annealing of ordinary stainless steel (e.g. 18Cr-8Ni stainless steel), but they It is not sufficiently effective against oxidized scale caused by annealing or hot rolling of heat-resistant steel, and the oxidized scale may not be removed by pickling in the post-process, or even if it is removed, it may take a long time. It has the disadvantage that it requires a lot of heat and can result in a product with rough skin and a large amount of meat loss. In this way, high Cr, which has so-called difficult descaling,
It was speculated that the reason why the conventional molten salt baths described above cannot perform adequately against the oxidized scale generated in steel containing steel is that the oxidizing power of these salt baths is insufficient. The present invention was developed as a result of studies on salt baths to which permanganates such as KMnO 4 or NaMnO 4 , which are stronger oxidizing agents than NaNO 3 and KNO 3 , are added.
One or two of NaNO 3 and KNO 3 5-40%,
One or both of KMnO 4 and NaMnO 4 0.5-10%,
Further, if necessary, one or both of NaCl 5 to 15% and KOH 5 to 20% may be contained, with the remainder consisting of NaOH and impurities. The present invention has the above-mentioned composition and has stronger oxidizing power than conventional ones, so it has the following effects. (1) In the case of the above-mentioned high chromium-containing steel, a dense oxide scale with a high Cr content (mainly composed of Cr 2 O 3 and insoluble in acids) is formed, so this can be removed by strong oxidation of permanganate. At the same time, the density of the oxidized scale is reduced by applying force to acid-soluble scale (mainly composed of 3 CrO), allowing the pickling solution to penetrate into the base metal, and proceeding with pickling by dissolving the base metal. urge (2) Since the scale produced by hot rolling is thick, it takes a long time to modify the scale in a conventional molten salt bath with weak oxidizing power, which increases the cost, but with the salt bath of the present invention, compared to The scale can be modified in a short period of time. (3) Even if the temperature of the salt bath is lowered, it has the same or higher oxidizing power than conventional salt baths, and is also useful for energy saving. Next, the reasons for limiting the components of the salt bath according to the present invention will be described, and the characteristics of the present invention will also be explained. NaNO 3 , KNO 3 : Acts as an oxidizing agent and oxidizes scale with insufficient oxidation degree.
The optimum amount of permanganate added varies depending on the type of material to be treated and the amount of permanganate added, but it is 40%.
If added above, NaNO 3 and KNO 3 themselves become easily decomposed, so the content was set at 40% or less. Also, if permanganate is added, the descaling ability of the salt bath can be maintained to some extent even without adding NaNO 3 and/or KNO 3 , but permanganate is more expensive than nitrate, so it is not economical. From a practical standpoint, nitrates should be added at least 5%,
It is desirable to add 0.5-10% permanganate to this. KMnO 4 , NaMnO 4 : Together with NaNO 3 and KNO 3 , they act as oxidizing agents to strongly oxidize scales with insufficient oxidation degree.The oxidizing power of the molten salt bath increases as the amount added increases, but nitrates When it is present as mentioned above, addition of 0.5% or more is sufficient to achieve the purpose of the present invention. Also, if it is added more than 10%, permanganic acid itself will be easily decomposed, so the amount added should be 0.5% or more.
~10%. Nacl: Does not directly affect descaling ability, but adding 5% or more will lower the viscosity of the molten salt bath.
It has the effect of reducing the amount of bath that adheres to the immersed board and is taken out of the bath (especially when the bath temperature is relatively high at 480°C). But 15%
If the above amount is added, the amount taken out will increase, so the amount added should be 5 to 15%. KOH: Although it does not have a direct effect on the descaling ability, if it is added in an amount of 5% or more, it has the effect of reducing the amount carried out from the molten salt bath. However, if it is added more than 20%, the amount taken out will increase, so the amount added should be 5~
It shall be 20%. NaOH: An alkali necessary to convert chromium in the oxide scale into acid-soluble hexavalent chromium, and it is sufficient if the total amount with KOH is 35% or more. Next, the effects of the present invention will be explained with reference to Examples. A sample material (test piece size: 1.0 (t) x 30 x 50 mm) with the composition shown in Table 1 below was annealed under the annealing conditions shown in Table 2 to generate oxide scale on the surface of the test piece. After being immersed in a molten salt bath with the composition shown in Table 3 for 10 seconds, the test piece was taken out of the bath and put into water to dissolve the molten salt, and then pickled under the pickling conditions shown in Table 4 to descale the surface of the test piece. Table 5 shows the results of observing the condition with an optical microscope.
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】
上記第５表より明らかなように供試材１
（SUS304相当材）のような普通のオーステナイト
ステンレス鋼の場合には本発明浴と比較塩浴（従
来の塩浴）の脱スケール能にはあまり顕著な差は
認められなかつたが供試材２、３のような高クロ
ム含有鋼の場合には本発明塩浴は比較塩浴に比べ
てはるかに脱スケール能がすぐれており、特に塩
浴の温度が低い時にその差が顕著に現われてい
る。
このように本発明塩浴は従来困難とされていた
高クロム含有鋼の酸洗によるデスケーリングを容
易にするものであり、酸洗時間の短縮、酸洗によ
る溶解ロスの減少と酸洗液の節約、溶融塩浴の温
度低下による省エネルギーなどその効果は極めて
大きい。[Table] As is clear from Table 5 above, sample material 1
In the case of ordinary austenitic stainless steel such as SUS304 (equivalent to SUS304), there was no significant difference in descaling ability between the bath of the present invention and the comparative salt bath (conventional salt bath). In the case of high chromium-containing steels such as No. 3, the salt bath of the present invention has much better descaling ability than the comparative salt bath, and the difference is particularly noticeable when the temperature of the salt bath is low. . In this way, the salt bath of the present invention facilitates the descaling of high chromium-containing steel by pickling, which was previously considered difficult. The effects are extremely large, such as saving money and saving energy by lowering the temperature of the molten salt bath.
Claims (1)
〜40％、KMnO4、NaMnO4の１種又は２種 0.5
〜10％、残部NaOH及び不純物より成ることを特
徴とする酸洗用溶融塩浴。 ２ 重量％でNaNO3、KNO3の１種又は２種 ５
〜40％、KMnO4、NaMnO4の１種又は２種 0.5
〜10％、及びNaCl5〜15％、KOH5〜20％の一方
又は双方並びに残部NaOH及び不純物より成るこ
とを特徴とする酸洗用溶融塩浴。[Claims] 1. One or both of NaNO 3 and KNO 3 in weight% 5
~40%, one or both of KMnO 4 and NaMnO 4 0.5
A molten salt bath for pickling, characterized in that it consists of ~10%, the balance NaOH and impurities. 2 One or two of NaNO 3 and KNO 3 in weight% 5
~40%, one or both of KMnO 4 and NaMnO 4 0.5
10%, and one or both of 5 to 15% NaCl and 5 to 20% KOH, and the balance NaOH and impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8206082A JPS58199880A (en) | 1982-05-15 | 1982-05-15 | Molten salt bath for pickling |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8206082A JPS58199880A (en) | 1982-05-15 | 1982-05-15 | Molten salt bath for pickling |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58199880A JPS58199880A (en) | 1983-11-21 |
| JPS6261113B2 true JPS6261113B2 (en) | 1987-12-19 |
Family
ID=13763959
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8206082A Granted JPS58199880A (en) | 1982-05-15 | 1982-05-15 | Molten salt bath for pickling |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58199880A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012036430A (en) * | 2010-08-05 | 2012-02-23 | Parker Corp | Molten salt composition modifying oxidized scale |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60121285A (en) * | 1983-12-02 | 1985-06-28 | Nisshin Steel Co Ltd | Molten salt composition for pretreating stainless steel before pickling |
| DE10135491A1 (en) * | 2001-07-20 | 2003-02-06 | Zwez Chemie Gmbh | Solid mixture used in the production and regeneration of a burnishing bath comprises sodium hydroxide, and oxidant selected from alkali nitrite, alkali nitrate, alkali chlorate and alkali perchlorate |
| CN103898577A (en) * | 2013-06-03 | 2014-07-02 | 无锡市锡山区鹅湖镇荡口青荡金属制品厂 | Pretreatment process of electroplating chromium on surface of magnesium alloy die casting |
| CN104610927B (en) * | 2015-02-03 | 2017-12-12 | 湖北科技学院 | Low melting point fused salt mixt heat accumulation heat-transfer matcrial and preparation method thereof |
-
1982
- 1982-05-15 JP JP8206082A patent/JPS58199880A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012036430A (en) * | 2010-08-05 | 2012-02-23 | Parker Corp | Molten salt composition modifying oxidized scale |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58199880A (en) | 1983-11-21 |
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