JP2004183087A - Hot rolling method for Si-containing steel - Google Patents
Hot rolling method for Si-containing steel Download PDFInfo
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- JP2004183087A JP2004183087A JP2002355209A JP2002355209A JP2004183087A JP 2004183087 A JP2004183087 A JP 2004183087A JP 2002355209 A JP2002355209 A JP 2002355209A JP 2002355209 A JP2002355209 A JP 2002355209A JP 2004183087 A JP2004183087 A JP 2004183087A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 56
- 239000010959 steel Substances 0.000 title claims abstract description 56
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000005098 hot rolling Methods 0.000 title claims abstract description 20
- 239000011248 coating agent Substances 0.000 claims abstract description 38
- 238000000576 coating method Methods 0.000 claims abstract description 38
- 238000010438 heat treatment Methods 0.000 claims abstract description 38
- 239000010445 mica Substances 0.000 claims abstract description 8
- 229910052618 mica group Inorganic materials 0.000 claims abstract description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 7
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims abstract description 6
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims abstract description 6
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 6
- 239000010439 graphite Substances 0.000 claims abstract description 6
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 6
- 235000014413 iron hydroxide Nutrition 0.000 claims abstract description 6
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 claims abstract description 6
- 239000010452 phosphate Substances 0.000 claims abstract description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000011230 binding agent Substances 0.000 claims description 4
- 239000011347 resin Substances 0.000 claims description 4
- 229920005989 resin Polymers 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 3
- 238000005096 rolling process Methods 0.000 abstract description 26
- 239000000463 material Substances 0.000 abstract description 23
- 238000010586 diagram Methods 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 7
- 239000010410 layer Substances 0.000 description 7
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 6
- 239000011148 porous material Substances 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 239000012634 fragment Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 229910000160 potassium phosphate Inorganic materials 0.000 description 2
- 235000011009 potassium phosphates Nutrition 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- TUSDEZXZIZRFGC-UHFFFAOYSA-N 1-O-galloyl-3,6-(R)-HHDP-beta-D-glucose Natural products OC1C(O2)COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC1C(O)C2OC(=O)C1=CC(O)=C(O)C(O)=C1 TUSDEZXZIZRFGC-UHFFFAOYSA-N 0.000 description 1
- 239000001263 FEMA 3042 Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- LRBQNJMCXXYXIU-PPKXGCFTSA-N Penta-digallate-beta-D-glucose Natural products OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-PPKXGCFTSA-N 0.000 description 1
- 229920002253 Tannate Polymers 0.000 description 1
- 239000006061 abrasive grain Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 229910021538 borax Inorganic materials 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 1
- 229910000397 disodium phosphate Inorganic materials 0.000 description 1
- 235000019800 disodium phosphate Nutrition 0.000 description 1
- 238000004299 exfoliation Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000002688 persistence Effects 0.000 description 1
- 235000011007 phosphoric acid Nutrition 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- 229910000162 sodium phosphate Inorganic materials 0.000 description 1
- 235000011008 sodium phosphates Nutrition 0.000 description 1
- 235000010339 sodium tetraborate Nutrition 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- LRBQNJMCXXYXIU-NRMVVENXSA-N tannic acid Chemical compound OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-NRMVVENXSA-N 0.000 description 1
- 229940033123 tannic acid Drugs 0.000 description 1
- 235000015523 tannic acid Nutrition 0.000 description 1
- 229920002258 tannic acid Polymers 0.000 description 1
- 238000007751 thermal spraying Methods 0.000 description 1
- VLCLHFYFMCKBRP-UHFFFAOYSA-N tricalcium;diborate Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]B([O-])[O-].[O-]B([O-])[O-] VLCLHFYFMCKBRP-UHFFFAOYSA-N 0.000 description 1
- WUUHFRRPHJEEKV-UHFFFAOYSA-N tripotassium borate Chemical compound [K+].[K+].[K+].[O-]B([O-])[O-] WUUHFRRPHJEEKV-UHFFFAOYSA-N 0.000 description 1
- BSVBQGMMJUBVOD-UHFFFAOYSA-N trisodium borate Chemical compound [Na+].[Na+].[Na+].[O-]B([O-])[O-] BSVBQGMMJUBVOD-UHFFFAOYSA-N 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
Images
Landscapes
- Metal Rolling (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
【課題】加熱前の鋼材に予め被膜を形成させることにより、加熱中に生成するスケールを抑制するとともに、圧延前のデスケーリングを効率的に行うことを可能とし、スケール起因の疵の抑制および生産性の向上、歩留の向上、操業コストの低減を図ることのできるＳｉ含有鋼の熱間圧延方法を提供する。
【解決手段】Ｓｉ含有鋼を加熱するに先立ち、予め鋼材の表面に雲母含有被膜、燐酸塩系被膜、硼酸塩系被膜、黒鉛系被膜、炭酸塩系被膜、水酸化鉄被膜等を形成させた後、加熱を行うことにより、加熱中のスケール生成の抑制およびデスケーリング性の向上を可能とするＳｉ含有鋼の熱間圧延方法。
【選択図】 なし[PROBLEMS] To suppress scale generated during heating by forming a film on a steel material before heating in advance, and to efficiently perform descaling before rolling, to suppress and produce flaws caused by scale. Provided is a hot rolling method for Si-containing steel, which can improve the workability, improve the yield, and reduce the operation cost.
A mica-containing coating, a phosphate-based coating, a borate-based coating, a graphite-based coating, a carbonate-based coating, an iron hydroxide coating, and the like are previously formed on the surface of a steel material before heating a Si-containing steel. Thereafter, a hot rolling method for Si-containing steel, in which heating is performed to suppress generation of scale during heating and improve descalability.
[Selection diagram] None
Description
【０００１】
【発明の属する技術分野】
本発明は、Ｓｉ含有鋼の熱間圧延方法に関し、特に高張力鋼や電磁鋼等の高Ｓｉ含有鋼の熱間圧延における加熱中のスケール生成を抑制しデスケーリング性を改善することのできるＳｉ含有鋼の熱間圧延方法に関する。
【０００２】
【従来の技術】
スラブ等の鋼材を熱間圧延するために加熱すると、鋼材表面が酸化されて、スケールが生成する。このスケールが付着したまま圧延されると部分的に鋼板上にスケールが残存し、押し込み疵等の原因となり、表面品質を著しく低下させるため、圧延に先立ちスケールは除去（デスケーリング）される。
近年、需要が増えつつある高張力鋼等の高Ｓｉ含有鋼の熱間圧延では、耐剥
離性の高いファイアライト（２ＦｅＯ・ＳｉＯ２ ）が生成するため、通常のデスケーリングでは完全に除去できない場合があり、その改善が必須の状況下にある。
【０００３】
デスケーリング性を向上させる方法としては、粗圧延において異周速圧延を行い、圧延後の鋼板表面に研磨剤を投射、もしくはブラシロールでスケールを除去する方法（特許文献１、特許文献２参照）や高水圧ジェットの高圧化や高水圧ジェットに砥粒を混合することにより強力にスケールを除去すること（特許文献３、特許文献４参照）等が行われている。さらに、加熱前にアルミニウム・ペイントを塗布し、そのうえにアルミナ粉の塗膜を形成させ、スケールとアルミナを反応させて、スケールを改質することでデスケーリング性を確保する方法（特許文献５参照）や、鋼材表面に加熱温度以下で溶融する塗布材を加熱前に塗布して加熱中に生成する気孔内に充填させることにより、スケールを緻密化して、冷却時に発生するき裂を母材表面まで到達させてデスケーリング性を向上する方法（特許文献６参照）などが知られている。
【０００４】
【特許文献１】
特開昭５５−３４６８８号公報
【特許文献２】
特開昭５６−９９０１０号公報
【特許文献３】
特開平６−２７９９２３号公報
【特許文献４】
特開平７−８０５３５号公報
【特許文献５】
特開昭５２−１４３９２５号公報
【特許文献６】
特開平４−２５９３９０号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、これらの従来技術の方法であっても高Ｓｉ含有高張力鋼等では完全にスケールを除去できていないのが実状といえる。さらに、高圧水ジェットの超高圧化に関しても技術的にも限界があること、また工業的にも莫大な投資が必要となるなど実現には相当困難を伴う。
また、異周速圧延による方法では、異周速圧延で鋼板の先後端で反りが発生し、その後の通板が困難になるなどの問題を有しており、圧延性の観点からも実現は難しい。
【０００６】
加熱前に塗布し、鉄スケールとアルミナとの複合酸化物にした場合は、高融点物質のため、スケールが強固化し、却ってデスケーリング性を阻害することになる。また、生成スケールの気孔に低融点物質を充填して緻密化する場合も
、低融点な為にデスケーリング時も溶融状態あるいは変形し易い状態にあり、さほど気孔を強固化するには至らず、デスケーリング性の大きな改善は望めない。
【０００７】
そこで、本発明は、これらの従来技術では困難であった高Ｓｉ含有高張力鋼や電磁鋼等に生成する耐剥離性の高いスケールを容易に除去できるＳｉ含有鋼の熱間圧延方法を提供することを目的とするものである。
【０００８】
【課題を解決するための手段】
本発明者らは、上記課題に関して鋭意研究を行った結果、以下に記述する構成によって課題を解決できることを見出し、本発明を完成させた。
（１）Ｓｉを０．１質量％から４質量％含有する鋼を熱間圧延する際に、加熱に先立ち、鋼片表面に、水あるいは樹脂バインダー中に雲母粉末を分散あるいは膨潤させた液体を塗布、乾燥させて被膜を形成させた後、加熱を行うことを特徴とするＳｉ含有鋼の熱間圧延方法。
【０００９】
（２）Ｓｉを０．１質量％から４質量％含有する鋼を熱間圧延する際に、加熱に先立ち、鋼片表面に、燐酸塩系被膜と、硼酸塩系被膜のうちの少なくとも１種類以上で構成された被膜を形成させた後、加熱を行うことを特徴とするＳｉ含有鋼の熱間圧延方法。
【００１０】
（３）Ｓｉを０．１質量％から４質量％含有する鋼を熱間圧延する際に、加熱に先立ち、鋼片表面に、形成被膜が水酸化鉄被膜あるいは黒鉛系被膜、炭酸塩系被膜の少なくとも１種類以上で構成された被膜を形成させた後、加熱を行うことを特徴とするＳｉ含有鋼の熱間圧延方法。
【００１１】
【発明の実施の形態】
加熱中の鋼材（スラブ、ビレット、ブルーム等の鋼片）のスケール生成を抑制する方法としては、一つには鋼材表面（界面）での酸素あるいはＦｅやＳｉ等の合金元素の拡散を防止することが考えられる。これを可能とするには加熱に先立ち鋼材表面に拡散を防止する被膜を形成させたのち、加熱する方法が考えられる。
【００１２】
本発明者らは、このような拡散防止被膜を種々検討した結果、耐熱性に優れ、被膜を形成し易い雲母含有被膜が、塗布加熱後のスケール剥離性が高いことを明らかにした。このような被膜の塗布方法としては、樹脂バインダー中に雲母粒子を分散させた溶液ないしは水に膨潤する膨潤雲母溶液を塗布乾燥すればよい。あるいは８０〜１５０℃程度に予熱した鋼材へスプレーあるいは刷毛等で塗布すれば素早く被膜を形成させることができる。雲母は主成分がＭｇＯ，ＳｉＯ２ であり、高融点で耐熱性を有し、酸素や合金元素の拡散を抑制するとともに、冷却時に基地からの剥離性を高める効果を有する。ジルコニア被膜でも同様な効果が期待できる。また、膨潤雲母の場合、水に分散しやすく、より簡便な塗布が可能となる。なお、その他に溶射にても被膜を形成することができる。
【００１３】
また、本発明者らは、加熱中の鋼材のスケール生成を抑制する他の方法を検討した結果、表層に塗布し形成した被膜と本来生成するスケールとを反応させ、低融点の複合スケールとなすことで、デスケーリング時に溶融に近い条件からのデスケーリングによる急冷効果でデスケーリング性を高めることができることを明らかにした。低融点の複合スケールとするためには、予め鋼材表面に少なくとも燐酸塩系あるいは硼酸塩系被膜の１種類以上を形成させることで達成することができる。この場合も被膜形成にはこれらを含有する溶液を塗布乾燥させることで行うことができる。
【００１４】
燐酸塩系溶液としては、燐酸、燐酸ナトリウム、燐酸水素ナトリウム、燐酸カリ、燐酸カリシウム等を溶解あるいは分散させて使用することができる。一方、硼酸塩系溶液としては、硼酸、硼酸ナトリウム、硼酸カリ、硼酸カルシウム等を溶解もしくは分散させて使用することができる。燐酸塩系被膜と硼酸塩系被膜とを交互に形成させても同様な効果が得られる。
【００１５】
さらに、本発明者らは、加熱中の鋼材のスケール生成を抑制する方法として、冷却時にスケール中に発生するき裂がスケール中に存在する気孔を伝播することに着目し、検討を重ねた結果、加熱中にガスを発生させ、生成スケールの母材近傍に沢山の気孔を形成させることにより、スケールの剥離性を高めることが可能なことを見出した。この場合、鋼材表面に予め黒鉛系被膜あるいは炭酸塩被膜、水酸化鉄被膜の少なくとも１種類以上の被膜を形成することにより、黒鉛系被膜および炭酸塩被膜では炭酸ガスが、水酸化鉄被膜では、水素および酸素が発生し、気孔となる。この場合、気孔は、母材直上の約１００μｍまでの断面でみた状態で面積率３０％以上存在することが好ましい。
【００１６】
黒鉛系被膜は、黒鉛粉末を水溶性樹脂バインダーに分散させた液体を塗布乾燥させて得ることができ、炭酸塩被膜は炭酸カリ、炭酸ナトリウム等を溶解あるいは分散させた溶液を塗布乾燥して得ることができる。一方、水酸化鉄被膜は、タンニン酸溶液を塗布することで得られ、そのまま乾燥させることで黒色に近いタンニン酸鉄被膜が形成される。各々の被膜を重ね合わせても同様の効果が得られる。
【００１７】
形成被膜の厚みは厚いほど効果が得られるが、スケール生成抑制およびデスケーリング効果を得るためには５μｍ以上必要である。上限は被膜処理のためのコスト、作業性から決めればよく、通常１ｍｍ以下で十分である。
【００１８】
粗圧延前の鋼材に上記の被膜を加熱前に形成させ、加熱を行った後、粗圧延
前および仕上圧延前でデスケーリングを行い、粗圧延あるいは仕上圧延を行うことにより、スケール残存の少ない鋼材を得ることができる。この場合、デスケーリングはブラシロールあるいは高圧水ジェットにて可能である。高圧水ジェットの場合はＳｉ含有量により耐剥離性が異なるため必要水圧も異なるが、５ＭＰａ以上あればよい。
【００１９】
【実施例】
加熱炉から抽出された鋼材（スラブ）を粗圧延の第１スタンドで圧延する場合をシミュレーションしたモデルミル実験（加熱−圧延一貫実験）を行い、加熱前に被膜形成した場合の評価を行った。
モデルミルの概要を模式的に図１に示す。図中１は圧延ロール、２は熱延鋼板（被圧延材）、３はスケール除去用ブラシ、４は圧延前のスケール層、５は圧延後のスケール層、６は破片状スケール除去用ブラシをかけた後のスケール層である。
なお、圧延実験は、加熱炉挿入から、圧延、冷却、取り出しまで、真空下（１０−３Ｐａ以下）で行われ、実験中にスケールが生成しないようにした。
試料を取り出した後、ブラシにより破片状のスケールを除去し、その材料の断面観察を行って残存スケール層厚を調査し、被膜塗布無しの比較材と比較した。
【００２１】
【表１】
表２に、圧延前のスケール厚みと、圧延後ブラシでデスケーリングを行った後の表面スケール残存量を示す。
【００２３】
【表２】
本発明による加熱前予塗布材では、圧延前のスケール生成が比較材に比べ少なく、加熱中のスケール生成量を抑制するとともに、圧延後の残留スケール厚みも予塗布無しの比較材に比べて、大幅に削減できることが判る。
【００２５】
【発明の効果】
上記本発明によるスケール生成の抑制およびデスケーリング性の向上により、超高圧水によるデスケーリングの必要はなくなり、かつ加熱条件等の制約もなく高Ｓｉ鋼特有の難剥離性スケールを既存の設備で簡便に除去可能となり、生産性の向上、歩留の向上、操業コストの低減が可能となるなどその産業上のメリットは大きい。
【図面の簡単な説明】
【図１】スケール残存性を評価するための試験機の構成を示す模式図である。
【符号の説明】
１ 圧延ロール
２ 熱延鋼板（被圧延材）
３ スケール除去用ブラシ
４ 圧延前のスケール層
５ 圧延後のスケール層
６ 破片状スケール除去用ブラシをかけた後のスケール層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hot rolling method for a Si-containing steel, and particularly to a Si rolling method capable of suppressing scale generation during heating in hot rolling of a high Si-containing steel such as a high-tensile steel or an electromagnetic steel and improving descaling property. The present invention relates to a method for hot rolling steel containing steel.
[0002]
[Prior art]
When a steel material such as a slab is heated for hot rolling, the surface of the steel material is oxidized to form scale. If the scale is rolled with the scale adhered, the scale partially remains on the steel sheet, causing indentation flaws and the like, and significantly reducing the surface quality. Therefore, the scale is removed (descaling) prior to rolling.
In recent years, hot rolling of high Si content steel such as high tensile steel, which has been increasing in demand, generates firelite (2FeO.SiO2) having high exfoliation resistance, and thus cannot be completely removed by ordinary descaling. Yes, and its improvement is essential.
[0003]
As a method of improving the descaling property, a method of performing different peripheral speed rolling in rough rolling and projecting an abrasive on the surface of the steel sheet after rolling or removing scale with a brush roll (see
[0004]
[Patent Document 1]
JP-A-55-34688 [Patent Document 2]
JP-A-56-99010 [Patent Document 3]
JP-A-6-279923 [Patent Document 4]
JP-A-7-80535 [Patent Document 5]
JP 52-143925 A [Patent Document 6]
JP-A-4-259390
[Problems to be solved by the invention]
However, it can be said that even with these conventional methods, scale cannot be completely removed with high Si content high strength steel or the like. Further, there is a technical limit to the ultra-high pressure of the high-pressure water jet, and a huge investment is required industrially.
In addition, the method using different peripheral speed rolling has a problem in that warpage occurs at the front and rear ends of the steel sheet due to different peripheral speed rolling, which makes it difficult to subsequently pass the steel sheet. difficult.
[0006]
When applied before heating to form a composite oxide of iron scale and alumina, the scale is solidified due to the high melting point substance, which rather impairs the descaling property. Also, in the case where the pores of the formed scale are filled with a low-melting substance to be densified, they are in a molten state or easily deformed even at the time of descaling because of the low melting point. No significant improvement in descaling can be expected.
[0007]
Thus, the present invention provides a hot rolling method for Si-containing steel that can easily remove scales having high peeling resistance generated in high-Si-content high-strength steels, electromagnetic steels, and the like, which were difficult with these conventional techniques. It is intended for that purpose.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on the above problems, and as a result, have found that the problems can be solved by the configuration described below, and have completed the present invention.
(1) When hot rolling a steel containing 0.1% to 4% by mass of Si, prior to heating, a liquid obtained by dispersing or swelling mica powder in water or a resin binder is applied to the surface of the steel piece. A hot rolling method for Si-containing steel, which comprises heating after applying and drying to form a film.
[0009]
(2) When hot rolling a steel containing 0.1 to 4% by mass of Si, at least one of a phosphate-based coating and a borate-based coating is applied to the surface of the steel slab prior to heating. A hot rolling method for Si-containing steel, comprising heating after forming the coating formed as described above.
[0010]
(3) When hot rolling a steel containing 0.1% to 4% by mass of Si, prior to heating, a formed film is formed on the surface of the slab such as an iron hydroxide film, a graphite film, or a carbonate film. Forming a film composed of at least one of the following, followed by heating.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
As a method of suppressing the scale generation of a steel material (steel pieces such as slabs, billets, and blooms) during heating, one of the methods is to prevent diffusion of oxygen or alloy elements such as Fe and Si on the steel material surface (interface). It is possible. To make this possible, a method of heating after forming a coating for preventing diffusion on the surface of the steel material prior to heating may be considered.
[0012]
The present inventors have conducted various studies on such a diffusion-preventing coating film, and as a result, have found that a mica-containing coating film that is excellent in heat resistance and easily forms a coating film has high scale peelability after application and heating. As a method for applying such a coating, a solution in which mica particles are dispersed in a resin binder or a swollen mica solution which swells in water may be applied and dried. Alternatively, a steel film preheated to about 80 to 150 [deg.] C. can be quickly formed by spraying or applying it with a brush or the like. Mica is mainly composed of MgO and SiO2, has a high melting point and heat resistance, suppresses the diffusion of oxygen and alloy elements, and has an effect of increasing the releasability from the matrix during cooling. A similar effect can be expected with a zirconia coating. In the case of swelled mica, it is easy to disperse in water, so that a more simple application is possible. In addition, a coating can be formed by thermal spraying.
[0013]
In addition, the present inventors have studied other methods for suppressing the formation of scale of a steel material during heating, and as a result, react the coating formed on the surface layer with the originally generated scale to form a composite scale having a low melting point. In this way, it was clarified that the descaling property can be improved by the quenching effect by the descaling from the condition close to melting at the time of descaling. In order to obtain a composite scale having a low melting point, it can be achieved by previously forming at least one kind of a phosphate-based or borate-based coating on the surface of a steel material. Also in this case, the film can be formed by applying and drying a solution containing these.
[0014]
As the phosphate-based solution, phosphoric acid, sodium phosphate, sodium hydrogen phosphate, potassium phosphate, potassium phosphate or the like can be used by dissolving or dispersing it. On the other hand, as the borate-based solution, boric acid, sodium borate, potassium borate, calcium borate, or the like can be dissolved or dispersed and used. Similar effects can be obtained by alternately forming a phosphate-based coating and a borate-based coating.
[0015]
Furthermore, the inventors of the present invention focused on the fact that cracks generated in the scale at the time of cooling propagate the pores present in the scale as a method of suppressing scale formation of the steel material during heating, and as a result of repeated studies. By generating gas during heating and forming many pores near the base material of the produced scale, it was found that the peelability of the scale could be improved. In this case, by forming at least one or more of a graphite coating or a carbonate coating and an iron hydroxide coating on the steel material surface in advance, carbon dioxide gas is generated in the graphite coating and the carbonate coating, and in the iron hydroxide coating, Hydrogen and oxygen are generated, forming pores. In this case, it is preferable that the pores exist in an area ratio of 30% or more when viewed in a cross section up to about 100 μm immediately above the base material.
[0016]
The graphite-based coating can be obtained by applying and drying a liquid in which graphite powder is dispersed in a water-soluble resin binder, and the carbonate coating can be obtained by applying and drying a solution in which potassium carbonate, sodium carbonate, or the like is dissolved or dispersed. be able to. On the other hand, the iron hydroxide coating is obtained by applying a tannic acid solution, and is dried as it is to form an iron tannate coating close to black. The same effect can be obtained by overlapping the respective films.
[0017]
The effect is obtained as the thickness of the formed film increases, but it is required to be 5 μm or more in order to suppress the scale generation and obtain the descaling effect. The upper limit may be determined based on cost and workability for coating treatment, and usually 1 mm or less is sufficient.
[0018]
The above-mentioned film is formed on the steel material before rough rolling before heating, and after heating, descaling is performed before rough rolling and before finishing rolling, and rough rolling or finish rolling is performed, thereby reducing the scale remaining steel material. Can be obtained. In this case, descaling is possible with a brush roll or a high pressure water jet. In the case of a high-pressure water jet, the required water pressure is different because the peeling resistance is different depending on the Si content, but it is sufficient if it is 5 MPa or more.
[0019]
【Example】
A model mill experiment (simultaneous heating-rolling experiment) was performed to simulate the case where the steel material (slab) extracted from the heating furnace was rolled at the first stand of rough rolling, and the case where a film was formed before heating was evaluated.
An outline of the model mill is schematically shown in FIG. In the figure, 1 is a rolling roll, 2 is a hot-rolled steel plate (rolled material), 3 is a brush for removing scale, 4 is a scale layer before rolling, 5 is a scale layer after rolling, and 6 is a brush for removing flake scale. This is the scale layer after being applied.
Note that the rolling experiment was performed under vacuum (10-3 Pa or less) from the insertion of the heating furnace to the rolling, cooling, and removal, so that no scale was generated during the experiment.
After the sample was taken out, the scale in the form of fragments was removed with a brush, the cross section of the material was observed, and the thickness of the remaining scale layer was investigated.
[0021]
[Table 1]
Table 2 shows the scale thickness before rolling and the remaining amount of surface scale after descaling with a brush after rolling.
[0023]
[Table 2]
In the pre-coated material before heating according to the present invention, the scale generation before rolling is smaller than that of the comparative material, and the amount of scale generated during heating is suppressed, and the residual scale thickness after rolling is also smaller than the comparative material without pre-coated, It can be seen that it can be significantly reduced.
[0025]
【The invention's effect】
The suppression of scale generation and improvement of descaling properties according to the present invention eliminates the need for descaling with ultra-high-pressure water, and makes it easy to use easily removable scales peculiar to high-Si steel with existing facilities without restrictions on heating conditions and the like. This has great industrial advantages, such as improved productivity, improved yield, and reduced operating costs.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of a tester for evaluating scale persistence.
[Explanation of symbols]
1 Roll roll 2 Hot rolled steel sheet (rolled material)
3 brush for removing scale 4 scale layer before rolling 5 scale layer after rolling 6 scale layer after applying brush for removing fragment scale
Claims (3)
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| JP2002355209A JP4105938B2 (en) | 2002-12-06 | 2002-12-06 | Hot rolling method for Si-containing steel |
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| JP2002355209A JP4105938B2 (en) | 2002-12-06 | 2002-12-06 | Hot rolling method for Si-containing steel |
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| JP4105938B2 JP4105938B2 (en) | 2008-06-25 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101140921B1 (en) | 2009-05-26 | 2012-05-03 | 현대제철 주식회사 | Method for manufacturing hot rolled steel sheet |
| JP2020040082A (en) * | 2018-09-10 | 2020-03-19 | 日本製鉄株式会社 | Rolling lubrication equipment and rolling method |
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2002
- 2002-12-06 JP JP2002355209A patent/JP4105938B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101140921B1 (en) | 2009-05-26 | 2012-05-03 | 현대제철 주식회사 | Method for manufacturing hot rolled steel sheet |
| JP2020040082A (en) * | 2018-09-10 | 2020-03-19 | 日本製鉄株式会社 | Rolling lubrication equipment and rolling method |
| JP7107113B2 (en) | 2018-09-10 | 2022-07-27 | 日本製鉄株式会社 | rolling method |
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