JP2019136766A - Exothermic front powder for continuous casting - Google Patents
Exothermic front powder for continuous casting Download PDFInfo
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- 239000000843 powder Substances 0.000 title claims abstract description 58
- 238000009749 continuous casting Methods 0.000 title claims description 17
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 36
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 claims abstract description 28
- 229910052751 metal Inorganic materials 0.000 claims abstract description 28
- 239000002184 metal Substances 0.000 claims abstract description 28
- 229910001092 metal group alloy Inorganic materials 0.000 claims abstract description 10
- 229910000288 alkali metal carbonate Inorganic materials 0.000 claims abstract description 7
- 150000008041 alkali metal carbonates Chemical class 0.000 claims abstract description 7
- -1 alkali metal hydrogen-carbonate Chemical class 0.000 claims abstract description 7
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 5
- 229910001963 alkali metal nitrate Inorganic materials 0.000 claims abstract description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 16
- 230000020169 heat generation Effects 0.000 claims description 8
- 230000005484 gravity Effects 0.000 claims description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 60
- 229910052799 carbon Inorganic materials 0.000 abstract description 58
- 239000000463 material Substances 0.000 abstract description 9
- 229910000831 Steel Inorganic materials 0.000 description 28
- 239000010959 steel Substances 0.000 description 28
- 235000013980 iron oxide Nutrition 0.000 description 16
- 239000007800 oxidant agent Substances 0.000 description 16
- 239000002893 slag Substances 0.000 description 10
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 9
- 230000001590 oxidative effect Effects 0.000 description 9
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 8
- 238000005266 casting Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 8
- 229910014458 Ca-Si Inorganic materials 0.000 description 6
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 6
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 229910052748 manganese Inorganic materials 0.000 description 5
- 229910004298 SiO 2 Inorganic materials 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 229910000029 sodium carbonate Inorganic materials 0.000 description 4
- 239000004317 sodium nitrate Substances 0.000 description 4
- 235000010344 sodium nitrate Nutrition 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 235000010333 potassium nitrate Nutrition 0.000 description 3
- 239000004323 potassium nitrate Substances 0.000 description 3
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 3
- 235000017557 sodium bicarbonate Nutrition 0.000 description 3
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 229910017082 Fe-Si Inorganic materials 0.000 description 2
- 229910017133 Fe—Si Inorganic materials 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 239000000378 calcium silicate Substances 0.000 description 2
- 229910052918 calcium silicate Inorganic materials 0.000 description 2
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 239000000571 coke Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 2
- 229910052808 lithium carbonate Inorganic materials 0.000 description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
- PPNAOCWZXJOHFK-UHFFFAOYSA-N manganese(2+);oxygen(2-) Chemical class [O-2].[Mn+2] PPNAOCWZXJOHFK-UHFFFAOYSA-N 0.000 description 2
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 description 2
- 235000011181 potassium carbonates Nutrition 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910018134 Al-Mg Inorganic materials 0.000 description 1
- 229910018467 Al—Mg Inorganic materials 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical class OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910018068 Li 2 O Inorganic materials 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 229910000676 Si alloy Inorganic materials 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 235000010216 calcium carbonate Nutrition 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical class OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- BDAGIHXWWSANSR-NJFSPNSNSA-N hydroxyformaldehyde Chemical compound O[14CH]=O BDAGIHXWWSANSR-NJFSPNSNSA-N 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 235000014380 magnesium carbonate Nutrition 0.000 description 1
- 239000011656 manganese carbonate Substances 0.000 description 1
- 235000006748 manganese carbonate Nutrition 0.000 description 1
- 229940093474 manganese carbonate Drugs 0.000 description 1
- 229910000016 manganese(II) carbonate Inorganic materials 0.000 description 1
- XMWCXZJXESXBBY-UHFFFAOYSA-L manganese(ii) carbonate Chemical compound [Mn+2].[O-]C([O-])=O XMWCXZJXESXBBY-UHFFFAOYSA-L 0.000 description 1
- 230000001404 mediated effect Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000011736 potassium bicarbonate Substances 0.000 description 1
- 229910000028 potassium bicarbonate Inorganic materials 0.000 description 1
- 235000015497 potassium bicarbonate Nutrition 0.000 description 1
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 1
- 229940086066 potassium hydrogencarbonate Drugs 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 229910000018 strontium carbonate Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000010456 wollastonite Substances 0.000 description 1
- 229910052882 wollastonite Inorganic materials 0.000 description 1
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- Continuous Casting (AREA)
Abstract
Description
本発明は、鋼の連続鋳造において鋳造開始時にモールド内に供給される発熱型フロントパウダーに関する。 The present invention relates to a heat generating front powder supplied into a mold at the start of casting in continuous casting of steel.
鋼の連続鋳造において、モールドに注入された溶鋼表面に、溶鋼表面の保温、溶鋼の再酸化防止、溶鋼から浮上する介在物の吸収除去、モールドと凝固シェルの潤滑、凝固シェルからモールドへの抜熱制御を目的として、モールドパウダーが供給される。上記のように溶鋼表面上へ供給されたモールドパウダーは、溶鋼からの熱を受けて溶融する。このとき上方から未溶融の原パウダー層、焼結層、溶融スラグ層からなる層状構造を形成し、溶融スラグはモールドと凝固シェル間に流入する。 In continuous casting of steel, the molten steel surface injected into the mold is kept warm, the reoxidation of molten steel is prevented, the inclusions floating from the molten steel are absorbed, the mold and the solid shell are lubricated, and the solid shell is removed from the mold. Mold powder is supplied for the purpose of heat control. The mold powder supplied onto the surface of the molten steel as described above is melted by receiving heat from the molten steel. At this time, a layered structure including an unmelted raw powder layer, a sintered layer, and a molten slag layer is formed from above, and the molten slag flows between the mold and the solidified shell.
連続鋳造開始時は冷えた銅製鋳型内に溶鋼が注入されるため、溶鋼表面にデッケルが発生しやすい。デッケルとは溶鋼表面で凝固した鋼のことである。デッケルが発生すると、モールドパウダーに熱が伝わりにくくなるためモールドパウダーの溶融が遅れ、溶融スラグ層が形成されにくくなる。溶融スラグ層が十分に形成されないと、モールドと凝固シェルの間隙に流入するためのスラグが不足するため凝固シェルの潤滑が不良となる。デッケルが発生しないまでも、溶鋼表面の温度が低下すると、凝固シェルの先端が延びて所謂爪状凝固シェルを形成し、溶鋼中から浮上してきた介在物や気泡が爪状凝固シェルに捕捉されて介在物欠陥やピンホール欠陥の原因となる。また、溶融スラグ層が十分でないとカーボンを含んだ未溶融のモールドパウダーが溶鋼に直接接触し、溶鋼へのカーボンピックアップやパウダーの巻き込みを起こす原因となる。 At the start of continuous casting, molten steel is poured into a cold copper mold, so that deckle is likely to occur on the surface of the molten steel. Deckel is steel that has solidified on the surface of the molten steel. When the deckle is generated, heat is not easily transmitted to the mold powder, so that the melting of the mold powder is delayed and the molten slag layer is hardly formed. If the molten slag layer is not formed sufficiently, the slag for flowing into the gap between the mold and the solidified shell is insufficient, and the solidified shell is poorly lubricated. Even if deckle does not occur, if the temperature of the molten steel surface decreases, the solidified shell tip extends to form a so-called claw-shaped solidified shell, and inclusions and bubbles that have floated from the molten steel are captured by the claw-shaped solidified shell. It causes inclusion defects and pinhole defects. In addition, if the molten slag layer is not sufficient, the unmelted mold powder containing carbon directly contacts the molten steel, causing carbon pick-up and powder entrainment in the molten steel.
上記のような鋳造開始時の問題点を解決するため、金属と酸化剤を添加した発熱型フロントパウダーが鋳造開始時に使用されている。発熱型フロントパウダーは、金属と酸化剤の反応により、短時間に発熱し溶鋼表面に熱を供給し、デッケルや爪状凝固シェルの生成を防止する。また発熱によって速やかに溶融スラグ層を形成する。 In order to solve the problems at the start of casting as described above, a heat-generating front powder to which a metal and an oxidizing agent are added is used at the start of casting. The exothermic front powder generates heat in a short time due to the reaction between the metal and the oxidant and supplies heat to the surface of the molten steel, thereby preventing the formation of deckles and claw-like solidified shells. Moreover, a molten slag layer is quickly formed by heat generation.
発熱型フロントパウダーは、金属の酸化によって発熱する。前記金属としては、一般的にＳｉやＣａ‐Ｓｉ合金等反応性の比較的低い金属、金属合金が使用され、また、前記酸化剤としては炭酸ナトリウム、炭酸カリウム、炭酸リチウム、硝酸ナトリウム、硝酸カリウム、酸化鉄、酸化マンガンなどが使用されている。 The exothermic front powder generates heat due to metal oxidation. As the metal, generally a metal having a relatively low reactivity, such as Si or Ca-Si alloy, a metal alloy is used, and as the oxidizing agent, sodium carbonate, potassium carbonate, lithium carbonate, sodium nitrate, potassium nitrate, Iron oxide, manganese oxide, etc. are used.
特許文献１には、ＣａＯおよびＳｉＯ２を主成分とし、全Ｃａ濃度をＣａＯ含有率として、また全Ｓｉ濃度をＳｉＯ２含有率として各質量％で換算するとき、該ＣａＯ含有率を該ＳｉＯ２含有率で除した比であるＣａＯ／ＳｉＯ２の値が１．０〜１．９であり、質量％で、Ａｌ２Ｏ３含有率が２〜１８％、Ｎａ２Ｏ、Ｌｉ２ＯおよびＦの合計含有率が２〜２５％であり、炭酸塩が炭素換算含有率２．５〜７．０％で、硝酸ソーダが含有率５．１〜８．０％で、炭素が含有率０〜５％で、Ｃａ-Ｓｉ合金および／または金属Ｓｉが含有率７〜２０％でそれぞれ配合され、酸化鉄濃度がＦｅ２Ｏ３換算含有率で２．０％未満および酸化マンガン濃度がＭｎＯ換算含有率で３．０％未満であり、凝固温度が１０５０〜１２５０℃であり、そして１３００℃における粘度が０．０４〜１．５Ｐａ・ｓであることを特徴とする鋼の連続鋳造用モールドパウダーが開示されている。しかしながら、以下に詳しく説明するように酸化鉄がカーボンピックアップの原因となるにもかかわらず、ここでは実施例に酸化鉄を排除した例は見当たらず、依然として溶鋼へのカーボンピックアップをなくすことができなかった。 In Patent Document 1, when CaO and SiO 2 are the main components, the total Ca concentration is converted into CaO content, and the total Si concentration is converted into SiO 2 content in each mass%, the CaO content is converted to the SiO 2. The value of CaO / SiO 2 , which is the ratio divided by the content rate, is 1.0 to 1.9, and by mass%, the Al 2 O 3 content rate is 2 to 18%, Na 2 O, Li 2 O and F The total content is 2 to 25%, the carbonate content is 2.5 to 7.0% in terms of carbon, the sodium nitrate content is 5.1 to 8.0%, and the carbon content is 0 to 0%. 5%, Ca—Si alloy and / or metal Si is blended at a content rate of 7 to 20%, the iron oxide concentration is less than 2.0% in terms of Fe 2 O 3 content, and the manganese oxide concentration is in terms of MnO content The solidification temperature is 1050 to 1250 ° C. Continuous casting mold powder of steel, wherein the viscosity at 1300 ° C. is 0.04~1.5Pa · s Te have been disclosed. However, as described in detail below, although iron oxide causes carbon pickup, there is no example in which iron oxide is excluded in the examples, and it is still impossible to eliminate carbon pickup for molten steel. It was.
特許文献２には、鋼の連続鋳造用モールドパウダーであって、全カーボン：０〜１．５質量％、炭酸塩：０〜５質量％ならびに金属粉末発熱剤としてＣａ−Ｓｉ合金、金属ＳｉおよびＳｉ合金の１種もしくは２種以上：３質量％以上を含有することを特徴とする、鋳造の開始を円滑に行うための連続鋳造開始用モールドパウダーが開示されている。しかし実施例には全炭素が１mass％含有しているものが開示されているのみで、炭素を排除した例は見当たらず依然として溶鋼へのカーボンピックアップをなくすことができなかった。 Patent Document 2 discloses a mold powder for continuous casting of steel, in which total carbon: 0 to 1.5 mass%, carbonate: 0 to 5 mass%, and a Ca—Si alloy, metal Si and There is disclosed a mold powder for starting continuous casting for smoothly starting casting, which contains one or more of Si alloys: 3% by mass or more. However, only examples containing 1 mass% of total carbon were disclosed in the examples, and no examples of excluding carbon were found, and it was still impossible to eliminate carbon pickup for molten steel.
特に極低炭素鋼の鋳造では、鋳造開始時のカーボンピックアップが問題となるため、発熱型フロントパウダーの遊離炭素を無添加とすることで、一定の効果を上げてきた。しかし遊離炭素を含まない発熱型フロントパウダーを使用してもカーボンピックアップの低減は不十分であり、よりカーボンピックアップを抑制する技術が求められていた。 Especially in the casting of ultra-low carbon steel, the carbon pick-up at the start of casting becomes a problem. Therefore, a certain effect has been achieved by adding no free carbon in the exothermic front powder. However, even if the exothermic front powder containing no free carbon is used, the reduction of the carbon pickup is insufficient, and a technique for suppressing the carbon pickup has been demanded.
金属を添加した発熱型フロントパウダーは、金属と酸化剤との反応によって発熱する。酸化剤として炭酸塩が添加されるが、当該炭酸塩は金属との反応によってＣＯ2もしくはＣＯガスとなって大気中に拡散するため、溶鋼がカーボンピックアップすることはないと考えられてきた。 The exothermic front powder to which the metal is added generates heat due to the reaction between the metal and the oxidizing agent. Although carbonate is added as an oxidizing agent, it has been thought that molten steel does not pick up carbon because the carbonate reacts with metal to form CO 2 or CO gas and diffuses into the atmosphere.
しかし、酸化剤としてさらに酸化鉄または酸化マンガンを添加していると、ＳｉやＣａ-Ｓｉ合金などによって鉄またはマンガンに還元される。還元された鉄またはマンガンがＣＯ2またはＣＯガスを溶解吸収して、カーボン濃度の高い鉄、マンガン、炭化鉄、炭化マンガンとなることが確認できた。当該カーボン濃度の高い鉄、マンガン、炭化鉄、炭化マンガンは、カーボンピックアップの原因となることが確認できた。 However, when iron oxide or manganese oxide is further added as an oxidizing agent, it is reduced to iron or manganese by Si or Ca—Si alloy. It was confirmed that the reduced iron or manganese dissolved and absorbed CO 2 or CO gas to become iron, manganese, iron carbide, and manganese carbide having a high carbon concentration. It was confirmed that iron, manganese, iron carbide, and manganese carbide having a high carbon concentration cause carbon pickup.
また、モールドパウダー中に含有される有機物も、完全燃焼するのではなく残留した炭素分が鉄、マンガンに溶け込み、溶鋼中に入ることによってカーボンピックアップの原因となることを見出した。 It was also found that the organic matter contained in the mold powder is not completely burned, but the remaining carbon is dissolved in iron and manganese and enters the molten steel to cause carbon pickup.
更に、発熱型フロントパウダーの全炭素（以下Ｔ．Ｃという）をゼロにしたとしても、発熱型フロントパウダーに続いて投入される定常用モールドパウダーは通常カーボンを含有している。そのため定常用モールドパウダーのカーボンが発熱型フロントパウダーの酸化鉄、酸化マンガンを介して溶鋼へのカーボンピックアップの原因となっていた。 Furthermore, even if the total carbon (hereinafter referred to as TC) of the exothermic front powder is reduced to zero, the stationary mold powder introduced after the exothermic front powder usually contains carbon. For this reason, the carbon of the mold powder for stationary use causes carbon pick-up to the molten steel through the iron oxide and manganese oxide of the exothermic front powder.
本発明は上記従来の事情の鑑みて提案されたものであって、鋳造開始時のカーボンピックアップを極限まで低減することができる発熱型フロントパウダーを提供することを目的とする。 The present invention has been proposed in view of the above-described conventional circumstances, and an object thereof is to provide a heat generating type front powder capable of reducing the carbon pickup at the start of casting to the limit.
本発明は、金属または金属合金３〜２０質量％、アルカリ金属硝酸塩３〜１５質量％を含む連続鋳造用発熱型フロントパウダーであって、全炭素０．３質量％以下、Ｆｅ２Ｏ３換算した酸化鉄とＭｎＯ換算した酸化マンガンの合計量が３質量％以下である連続鋳造用発熱型フロントパウダーである（第一発明）。また第一発明において、アルカリ金属炭酸塩とアルカリ金属炭酸水素塩の合計量を１質量％以下とした連続鋳造用発熱型フロントパウダーである（第二発明）。また第一発明、第二発明において、緩め充てんかさ比重が０．８０〜１．０５ ｇ／ｃｍ３の範囲である連続鋳造用発熱型フロントパウダーである（第三発明）。 The present invention is a continuous casting exothermic front powder containing 3 to 20% by mass of a metal or metal alloy and 3 to 15% by mass of an alkali metal nitrate, wherein the total carbon is 0.3% by mass or less and converted to Fe 2 O 3 . A heat-generating front powder for continuous casting in which the total amount of iron oxide and manganese oxide in terms of MnO is 3% by mass or less (first invention). Further, in the first invention, there is provided a heat generating front powder for continuous casting in which the total amount of alkali metal carbonate and alkali metal bicarbonate is 1% by mass or less (second invention). Further, in the first and second inventions, the present invention relates to a heat generating front powder for continuous casting having a loose packed bulk specific gravity in the range of 0.80 to 1.05 g / cm 3 (third invention).
上記発熱型モールドパウダーの原料はカーボンピックアップの原因となる可能性のある全炭素を原則ゼロとしており、また、カーボンピックアップを媒介する酸化鉄と酸化マンガンも原則として無添加とする。これによって、カーボンピックアップを極限にまで低減することができる。 The raw material of the exothermic mold powder is essentially zero in total carbon that can cause carbon pickup, and iron oxide and manganese oxide that mediate the carbon pickup are not added in principle. As a result, the carbon pickup can be reduced to the limit.
本発明では、連続鋳造用発熱型フロントパウダーによるカーボンピックアップを低減するためには、カーボン含有原料、すなわちカーボンブラック、コークス、黒鉛等を無添加とすることが原則である。加えて、上記したように、酸化剤として添加される酸化鉄あるいは酸化マンガンによって、酸化剤として添加した炭酸塩より発生するＣＯ２やＣＯに含まれる炭素が、溶鋼中に取り込まれカーボンピックアップを引き起こすことになると考えられる。従って、さらに、炭酸ナトリウム、炭酸水素ナトリウム等の炭酸塩化合物、有機物、さらに、酸化鉄あるいは酸化マンガンも原則無添加とするのが望ましい。 In the present invention, in order to reduce the carbon pick-up by the exothermic front powder for continuous casting, it is a principle that no carbon-containing raw material, that is, carbon black, coke, graphite or the like is added. In addition, as described above, by the iron oxide or manganese oxide added as the oxidant, CO 2 or carbon contained in the CO generated from the carbonate added as the oxidant is taken into the molten steel and causes carbon pickup. It is thought that it will be. Accordingly, it is desirable to add no carbonate compounds such as sodium carbonate and sodium hydrogen carbonate, organic substances, and iron oxide or manganese oxide in principle.
以上の観点から本発明は、モールドパウダーとしての基材に、発熱材としてのＳｉ、Ａｌ、Ｃａ−Ｓｉ、Ｃａ−Ａｌ、Ａｌ−Ｍａ、Ａｌ−Ｃａ―Ｍａ、Ｆｅ−Ｓｉの内の少なくとも１種を３〜２０質量％、酸素供給材としてのアルカリ金属の硝酸塩３〜１５質量％を添加するようにしている。 In view of the above, the present invention provides at least one of Si, Al, Ca—Si, Ca—Al, Al—Ma, Al—Ca—Ma, and Fe—Si as the heat generating material on the base material as the mold powder. 3 to 20% by mass of seeds and 3 to 15% by mass of alkali metal nitrate as an oxygen supply material are added.
すなわち、カーボンブラック、コークス、黒鉛等の炭素単体を無添加とするだけでなく、炭酸ナトリウム、炭酸水素ナトリウム等の炭酸塩化合物中の炭素と、有機物の炭素を無添加とし、さらにカーボンピックアップを媒介する酸化鉄（ＦｅＯ，Ｆｅ３Ｏ４，Ｆｅ２Ｏ３等）と酸化マンガン（ＭｎＯ，Ｍｎ２Ｏ３，ＭｎＯ２等）も無添加としたものである。 In other words, not only carbon black, coke, graphite and other carbon alone are added, but also carbon in carbonate compounds such as sodium carbonate and sodium bicarbonate and organic carbon are not added, and carbon pickup is mediated. Iron oxide (FeO, Fe 3 O 4 , Fe 2 O 3 etc.) and manganese oxide (MnO, Mn 2 O 3 , MnO 2 etc.) to be added are not added.
上記のように、本発明では酸化剤として通常使用するアルカリ金属炭酸塩、酸化鉄、酸化マンガンなどを使用しない。これらに代わる酸化剤として硝酸ナトリウムや硝酸カリウムを添加するが、添加量が多くなりすぎると金属との酸化発熱反応時に褐色の二酸化窒素を放出し作業環境悪化、大気汚染の原因となるため好ましくない。そのため添加量が制限され、従来の酸化剤を使用したものよりも酸素源が不足気味となる。酸素源を補うため大気との接触面積が増えるよう、発熱型モールドパウダーのかさ比重を小さくすることが有効となる。 As described above, in the present invention, alkali metal carbonates, iron oxides, manganese oxides and the like that are usually used as oxidizing agents are not used. Sodium nitrate or potassium nitrate is added as an oxidant instead of these. However, if the amount added is too large, brown nitrogen dioxide is released during the oxidation exothermic reaction with the metal, which causes undesirable working environment and air pollution. Therefore, the amount of addition is limited, and the oxygen source is deficient as compared with the conventional oxidant. In order to supplement the oxygen source, it is effective to reduce the bulk specific gravity of the exothermic mold powder so that the contact area with the atmosphere increases.
モールドパウダーの基材としては、公知のけい酸カルシウムを主体とした鉱物質原料やけい酸ナトリウムを主体としたガラス質原料などが使用できる。例えば、合成けい酸カルシウム、ウォラストナイト、ポルトランドセメント、ソーダガラス等が使用できる。 As a base material of the mold powder, a known mineral material mainly composed of calcium silicate or a glassy material mainly composed of sodium silicate can be used. For example, synthetic calcium silicate, wollastonite, Portland cement, soda glass and the like can be used.
発熱材として、金属または金属合金を添加する。金属または金属合金としてＳｉ，Ａｌ，Ｃａ‐Ｓｉ，Ｃａ‐Ａｌ，Ａｌ‐Ｍｇ，Ａｌ‐Ｃａ‐Ｍｇ，Ｆｅ‐Ｓｉ等が使用でき、これら金属または金属合金の一種または二種以上を組み合わせて使用することができる。金属または金属合金の添加量は３〜２０質量％が好ましい。金属または金属合金の含有量が３質量％より少ないと発熱効果が得られない。金属または金属合金の含有量が２０質量％を超えると、発熱量が大きくなりすぎ危険であり、さらに酸化剤の量も多く必要となって基材成分が少なくなりスラグ組成の調整が困難になる。 A metal or metal alloy is added as a heat generating material. Si, Al, Ca-Si, Ca-Al, Al-Mg, Al-Ca-Mg, Fe-Si, etc. can be used as a metal or metal alloy, and these metals or metal alloys can be used alone or in combination. can do. The addition amount of the metal or metal alloy is preferably 3 to 20% by mass. When the content of the metal or metal alloy is less than 3% by mass, the heat generation effect cannot be obtained. If the content of the metal or metal alloy exceeds 20% by mass, the calorific value becomes excessively large, which is dangerous, and the amount of the oxidant is also required, and the base material component is reduced, making it difficult to adjust the slag composition. .
金属の酸化剤として、従来使用してきたアルカリ金属炭酸塩、アルカリ金属炭酸水素塩はカーボンピックアップの原因となるため、原則として使用しない。たとえ不純物として、前記原料に含まれるとしても、１質量％以下に制限される。尚、アルカリ金属炭酸塩、アルカリ金属炭酸水素塩としては、炭酸リチウム、炭酸ナトリウム、炭酸カリウム等のアルカリ金属炭酸塩、炭酸水素ナトリウム、炭酸水素カリウム等のアルカリ炭酸水素塩、炭酸マグネシウム、炭酸カルシウム、炭酸バリウム、炭酸ストロンチウム等のアルカリ土類金属炭酸塩、炭酸マンガン等の其の他の炭酸塩を挙げることができる。 Alkali metal carbonates and alkali metal hydrogen carbonates that have been conventionally used as metal oxidizers cause carbon pickup and are not used in principle. Even if it is contained in the raw material as an impurity, it is limited to 1% by mass or less. In addition, as alkali metal carbonates and alkali metal hydrogen carbonates, alkali metal carbonates such as lithium carbonate, sodium carbonate and potassium carbonate, alkali hydrogen carbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate, magnesium carbonate, calcium carbonate, Examples thereof include alkaline earth metal carbonates such as barium carbonate and strontium carbonate, and other carbonates such as manganese carbonate.
更に、金属の酸化剤として、従来使用してきた酸化鉄、酸化マンガンもカーボンピックアップの原因となるため、原則として使用しない。原料中に不純物として少量含まれているとしても、酸化鉄、酸化マンガンの合計含有量はモールドパウダー全体に対して３％以下が好ましく、より好ましくは１．５％以下である。 Furthermore, iron oxide and manganese oxide, which have been conventionally used as metal oxidizers, also cause carbon pickup, and therefore are not used in principle. Even if a small amount is contained as an impurity in the raw material, the total content of iron oxide and manganese oxide is preferably 3% or less, more preferably 1.5% or less, based on the entire mold powder.
上記炭酸塩、炭酸水素塩、酸化鉄、酸化マンガンに代わる酸化剤として、硝酸ナトリウム、硝酸カリウムを使用する。その添加量は合計で３〜１５質量％が好ましい。３質量％より少ないと酸化剤が不足して金属が酸化されないため期待した発熱量が得られない。１５質量％より多いと金属との酸化発熱反応が早く激しくなりすぎ、酸化剤として過剰な二酸化窒素が大気中に放出され作業環境が悪化するため好ましくない。 Sodium nitrate and potassium nitrate are used as oxidizing agents in place of the carbonates, bicarbonates, iron oxides and manganese oxides. The total addition amount is preferably 3 to 15% by mass. If it is less than 3% by mass, the oxidant is insufficient and the metal is not oxidized, so that the expected calorific value cannot be obtained. If it exceeds 15% by mass, the oxidative exothermic reaction with the metal becomes too rapid and excessive, and excess nitrogen dioxide is released into the atmosphere as an oxidant, which is not preferable.
金属と酸化剤以外の残分の種類、量については使用する目的に応じて適宜調整できる。例えばフラックス成分としてフッ化物を添加することができる。フッ化物の添加量としては７〜２０質量％が好ましい。発熱型フロントパウダーの形態は粉末が好ましい。
発熱型フロントパウダーのかさ比重は、０．８０〜１．０５ ｇ／ｃｍ３の範囲が好ましく、０．８５〜１．００ ｇ／ｃｍ３であることがより好ましい。ここでかさ比重の測定方法はメスシリンダーに１００ ｇを投入し、振動させずに緩め充てんしたときの容積から求めた値とする。
The type and amount of the residue other than the metal and the oxidizing agent can be appropriately adjusted according to the purpose of use. For example, fluoride can be added as a flux component. The addition amount of fluoride is preferably 7 to 20% by mass. The form of the exothermic front powder is preferably a powder.
Bulk density of exothermic front powder is preferably in the range of 0.80~1.05 g / cm 3, more preferably 0.85~1.00 g / cm 3. Here, the bulk specific gravity is measured by taking 100 g into a measuring cylinder and taking the value obtained from the volume when loosely packed without vibration.
表１に示す割合で本発明の実施例１〜８の発熱型フロントパウダーを用意し、更に、表２に示す割合で比較例８〜１３の発熱型フロントパウダーを用意し、当該本発明の実施例および比較例に示す発熱型フロントパウダーを実機鋳造でテストした。 The exothermic front powders of Examples 1 to 8 of the present invention were prepared at the ratio shown in Table 1, and the exothermic front powders of Comparative Examples 8 to 13 were prepared at the ratio shown in Table 2 to implement the present invention. The exothermic front powder shown in Examples and Comparative Examples was tested by actual casting.
テスト条件としてはモールドサイズ：２５０×１１５０ｍｍ、鋼種は極低炭素鋼（Ｃ：０．００３％）である。発熱型フロントパウダーの使用量は１０ ｋｇとし、発熱フロントパウダーに続いて通常のカーボンを含有した定常用モールドパウダーを投入した。 The test conditions are mold size: 250 × 1150 mm, and the steel type is extremely low carbon steel (C: 0.003%). The amount of the exothermic front powder used was 10 kg, and a normal mold powder containing normal carbon was introduced following the exothermic front powder.
発熱状況は目視で金属による発熱を確認できた場合を良好、出来なかった場合を不良とした。デッケル発生状況は、発熱型フロントパウダーに続いて定常用パウダーを投入した直後に鉄製棒で溶鋼を攪拌した時に、デッケルを確認できた場合に有りとした。カーボンピックアップ量は、タンディッシュから採取した溶鋼と、鋳片のボトムから５０ｃｍ部分のカーボン濃度の差から求めた。カーボン濃度の差が５ｐｐｍ未満の場合はカーボンピックアップなし、５ｐｐｍ以上の場合をカーボンピックアップ有りとした。ピンホールは、ボトム鋳片表面をスカーフィングして気泡欠陥が認められた場合に有りとした。 As for the heat generation situation, the case where the heat generation due to the metal was confirmed visually was good, and the case where the heat generation was not possible was judged as bad. The state of deckle generation was considered to be present when the deckle was confirmed when the molten steel was stirred with an iron bar immediately after the steady powder was added after the exothermic front powder. The amount of carbon pick-up was determined from the difference in carbon concentration from the molten steel collected from the tundish and the 50 cm portion from the bottom of the slab. When the difference in carbon concentration was less than 5 ppm, the carbon pickup was not present, and when it was 5 ppm or more, the carbon pickup was present. The pinhole was determined to be present when bubble defects were found by scarfing the bottom slab surface.
本発明例１〜７についてはカーボンピックアップが無く、大きな発熱反応が認められ、火炎や白煙が大量発生することなく、溶融後のスラグ状態も良好であり、デッケルが発生することなく、鋳片にピンホール、介在物も認められず良好であった。 For the inventive examples 1 to 7, there is no carbon pickup, a large exothermic reaction is observed, a large amount of flame and white smoke is not generated, the slag state after melting is good, no deckle is generated, and the slab No pinholes or inclusions were observed.
一方、比較例８〜１２についてはカーボンピックアップが認められた。比較例９は炭酸塩を用いていないにもかかわらず、カーボンピックアップが認められることから、発熱型フロントパウダーの後に続いて添加された定常用モールドパウダーのカーボンが発熱型フロントパウダーの酸化鉄と反応して溶鋼中に入ったと考えられる。比較例８、１１でのカーボンピックアップは炭酸塩由来と考えられる。比較例１０のカーボンピックアップは炭酸塩と有機物、カーボン由来と考えられる。比較例１２については、金属添加量が不足していたため発熱量が不十分でデッケルが発生すると共に、発熱型フロントパウダーの溶融が遅く溶融スラグ層が薄くて定常用パウダーのカーボンがピックアップを起こしたと考えられる。比較例１３は金属量に対して酸化剤が足りず、かさ比重が大きく大気中の空気との反応も促進されなかったため酸化発熱が足りず、デッケルが発生し、鋳片にピンホールが多く認められた。 On the other hand, the carbon pickup was recognized about Comparative Examples 8-12. In Comparative Example 9, carbon pick-up was observed even though no carbonate was used. Therefore, carbon in the stationary mold powder added after the exothermic front powder reacted with iron oxide in the exothermic front powder. It is thought that it entered the molten steel. The carbon pickups in Comparative Examples 8 and 11 are considered to be derived from carbonate. The carbon pickup of Comparative Example 10 is considered to be derived from carbonate, organic matter, and carbon. For Comparative Example 12, since the amount of metal added was insufficient, the amount of heat generation was insufficient and deckle was generated, and the melting of the exothermic front powder was slow, the molten slag layer was thin, and the carbon of the stationary powder caused pickup. Conceivable. In Comparative Example 13, the amount of metal was insufficient, the bulk specific gravity was large, and the reaction with air in the atmosphere was not promoted. Therefore, oxidation heat generation was insufficient, deckle was generated, and many pinholes were observed in the slab. It was.
以上説明したように、本発明はカーボンピックアップがなく、鋳片にピンホール、介在物も認められないので、鋼の連続鋳造用発熱型フロントパウダーに適用することができる。 As described above, the present invention has no carbon pickup, and pinholes and inclusions are not observed in the slab. Therefore, the present invention can be applied to a heat-generating front powder for continuous casting of steel.
Claims (3)
全炭素０．３質量％以下、Ｆｅ２Ｏ３換算した酸化鉄とＭｎＯ換算した酸化マンガンの合計量が３質量％以下である連続鋳造用発熱型フロントパウダー。 A heat generation type front powder for continuous casting containing 3 to 20% by mass of metal or metal alloy and 3 to 15% by mass of alkali metal nitrate,
An exothermic front powder for continuous casting in which the total amount of iron oxide in terms of Fe 2 O 3 and manganese oxide in terms of MnO is 3% by mass or less.
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| CN115106491A (en) * | 2021-03-19 | 2022-09-27 | 宝山钢铁股份有限公司 | Casting-on covering slag for continuous casting crystallizer and preparation method thereof |
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| CN115106491B (en) * | 2021-03-19 | 2024-06-04 | 宝山钢铁股份有限公司 | Casting mold flux for continuous casting mold and preparation method thereof |
| CN113290216A (en) * | 2021-06-07 | 2021-08-24 | 西峡龙成冶金材料有限公司 | Casting slag for stainless steel continuous casting and application thereof |
| CN113290216B (en) * | 2021-06-07 | 2022-09-16 | 西峡龙成冶金材料有限公司 | Casting slag for stainless steel continuous casting and application thereof |
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