JPH0735527B2 - Method for producing slab for hot dip Al plated steel sheet excellent in heat black resistance - Google Patents
Method for producing slab for hot dip Al plated steel sheet excellent in heat black resistanceInfo
- Publication number
- JPH0735527B2 JPH0735527B2 JP25194186A JP25194186A JPH0735527B2 JP H0735527 B2 JPH0735527 B2 JP H0735527B2 JP 25194186 A JP25194186 A JP 25194186A JP 25194186 A JP25194186 A JP 25194186A JP H0735527 B2 JPH0735527 B2 JP H0735527B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- steel sheet
- less
- plated steel
- hot
- 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 - Fee Related
Links
- 229910000831 Steel Inorganic materials 0.000 title claims description 43
- 239000010959 steel Substances 0.000 title claims description 43
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- 229910052760 oxygen Inorganic materials 0.000 claims description 32
- 229910052799 carbon Inorganic materials 0.000 claims description 21
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 10
- 239000001301 oxygen Substances 0.000 claims description 10
- 238000005266 casting Methods 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 239000000463 material Substances 0.000 description 14
- 238000007747 plating Methods 0.000 description 11
- 229910001327 Rimmed steel Inorganic materials 0.000 description 10
- 238000000034 method Methods 0.000 description 8
- 239000006104 solid solution Substances 0.000 description 8
- 238000009749 continuous casting Methods 0.000 description 7
- 229910000655 Killed steel Inorganic materials 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 238000005275 alloying Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 150000004767 nitrides Chemical class 0.000 description 4
- 238000009849 vacuum degassing Methods 0.000 description 4
- 229910000838 Al alloy Inorganic materials 0.000 description 3
- 238000000137 annealing Methods 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 229910001208 Crucible steel Inorganic materials 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000001579 optical reflectometry Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 229910021364 Al-Si alloy Inorganic materials 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 229910000676 Si alloy Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- RRZKHZBOZDIQJG-UHFFFAOYSA-N azane;manganese Chemical compound N.[Mn] RRZKHZBOZDIQJG-UHFFFAOYSA-N 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 230000001546 nitrifying effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Description
【発明の詳細な説明】 ＜産業上の利用分野＞ 本発明は、優れた耐加熱黒変性を有する溶融Alめっき鋼
板用の鋳片を連続鋳造によって製造する方法に関するも
のである。TECHNICAL FIELD The present invention relates to a method for producing a slab for a hot dip Al plated steel sheet having excellent blackening resistance by heating by continuous casting.
＜従来技術＞ 溶融Alめっき鋼板は鋼自身の持つ優れた強度特性に加え
Alの持つ優れた熱・光反射性をも有することから、電気
・ガス・石油ストーブの熱反射板やヘッド・ライト反射
板のような光反射板用の安価な材料として広く用いられ
ている。これらの用途に用いる溶融Alめっき鋼板に要求
される特性としては、耐加熱黒変性に優れること、すな
わち高温に加熱されてもめっき皮膜と鋼素地との合金化
反応が起きにくい性質、言い換えればめっき皮膜と鋼素
地との合金化開始温度（以下これを黒変化温度と呼ぶ）
が高いことが要求される。<Prior art> Hot-dip Al-plated steel sheet has excellent strength characteristics in addition to the steel itself.
Since it also has the excellent heat / light reflectivity of Al, it is widely used as an inexpensive material for light reflectors such as heat reflectors for electric / gas / oil stoves and head / light reflectors. The properties required for hot-dip Al-plated steel sheets used for these applications include excellent resistance to blackening by heat, that is, the property that an alloying reaction between the plating film and the steel substrate does not easily occur even when heated to a high temperature, in other words, plating. Starting temperature of alloying between the coating and the steel substrate (hereinafter referred to as the black transition temperature)
Is required to be high.
溶融Alめっき鋼板の加熱黒変化現象は、純Alかあるいは
Al-3〜13％Siからなるめっき皮膜と鋼素地とが高温に加
熱されることにより合金化反応が起き、めっき皮膜表面
が光反射性に優れる純AlかあるいはAl-Si合金から光反
射性に劣るFe-Al系合金に置き換えられる結果、生じる
現象である。The hot black change phenomenon of hot dip Al plated steel sheet is pure Al or
An alloying reaction occurs when the plating film made of Al-3 to 13% Si and the steel substrate are heated to a high temperature, and the plating film surface is pure Al or Al-Si alloy with excellent light reflectivity. This phenomenon occurs as a result of being replaced with an inferior Fe-Al alloy.
従来から、溶融Alめっき鋼板の黒変化温度はリムド鋼を
母材とする場合に約520℃ともっとも高く、Alキルド鋼
やTiキルド鋼を母材とする場合には約350℃とリムド鋼
より低いことはよく知られている。このような母材の違
いによる黒変化温度の変化は、鋼中Ｎの存在状態の違い
により決まるものと考えられており、AlNやTiNなどの安
定な窒化物として固定され得ない固溶Ｎが相当量存在す
ることが、リムド鋼を母材とする溶融Alめっき鋼板が優
れた耐加熱黒変性を示すことの原因と理解されている。Conventionally, the blackening temperature of hot-dip Al plated steel sheet is the highest at about 520 ° C when the base material is rimmed steel, and about 350 ° C when the base material is Al-killed steel or Ti-killed steel, which is higher than that of rimmed steel. It is well known that it is low. It is considered that such a change in black change temperature due to the difference in the base material is determined by the difference in the existing state of N in the steel, and solid solution N that cannot be fixed as a stable nitride such as AlN or TiN. It is understood that the presence in a considerable amount is the cause of the excellent heat-blackening resistance of the hot-dip Al-coated steel sheet having the rimmed steel as a base material.
またリムド鋼を母材とする溶融Alめっき鋼板に300℃〜5
00℃の範囲でさらに低温焼鈍を施すと、黒変化温度は約
570℃とさらに上昇することも、特公昭56-34629で開示
される通りよく知られたことである。In addition, 300 ℃ ~ 5
When low temperature annealing is performed in the range of 00 ℃, the black change temperature is about
It is well known that the temperature further rises to 570 ° C as disclosed in Japanese Patent Publication No. 56-34629.
しかしながら、現在では省エネルギーの見地から鋼の製
造工程を造魂一分魂から連続鋳造法へ変換することは至
上命題であるが、リムド鋼を連続鋳造法によって得るこ
とは非常に困難であり、リムド鋼に代わる耐加熱黒変性
溶融Alめっき鋼板用の連鋳鋼の開発が望まれていた。However, from the point of view of energy saving, it is an urgent task to convert the steel manufacturing process from the soul-making one-minute soul to the continuous casting method, but it is very difficult to obtain rimmed steel by the continuous casting method, and the rimmed steel is very difficult to obtain. It has been desired to develop continuous cast steel for heat-resistant black modified hot-dip Al plated steel sheet that replaces steel.
また一方で本発明者らは、リムド鋼に代わる連鋳鋼の製
造方法として、特願昭59-257641では耐つまとび性に優
れたほうろう用鋼鋳片の製造方法を、特願昭60-122774
では亜鉛めっきにおいてブリスターを発生しない加工用
熱延鋼板製造用鋳片の製造方法を、さらに特願昭60-127
045では浸炭焼入性の優れた低炭素熱延鋼板の製造方法
をそれぞれ開示している。しかしながら、これらの技術
により直接的に本発明の目的を達成することは困難であ
った。On the other hand, the inventors of the present invention, as a method for producing continuous cast steel instead of rimmed steel, in Japanese Patent Application No. 59-257641, a method for producing steel slabs for enameled enamel having excellent resistance to bite, Japanese Patent Application No. 60-122774.
Japanese Patent Application No. 60-127 discloses a method for producing a slab for hot-rolled steel sheet for processing that does not cause blisters in galvanizing.
045 discloses a method for producing a low carbon hot rolled steel sheet having excellent carburizing and quenching properties. However, it was difficult to directly achieve the object of the present invention by these techniques.
＜発明の目的＞ 本発明は、耐加熱黒変性に優れた溶融Alめっき鋼板用の
鋳片を連続鋳造によって製造・提供することを目的とす
る。<Purpose of the Invention> An object of the present invention is to produce and provide a slab for hot dip Al plated steel sheet which is excellent in heat black resistance by continuous casting.
＜発明の構成＞ 本発明者らは上述の目的を達成するため種々検討を重ね
た結果、Ｎを固溶Ｎとして確保すること、そのためには
安定な窒化物を形成するAlやTiなどの脱酸元素の使用は
大幅に制限されること、脱酸元素を使用しない条件でCO
気泡発生による鋳片の表面性状を良好に保つためには鋳
造直前の溶鋼中のＣ含有量と自由酸素量の適正範囲を定
めること、などに着目し、本発明を完成したものであ
る。<Structure of the Invention> As a result of various studies to achieve the above-mentioned object, the present inventors ensured that N is a solid solution N, and for that purpose, desorption of Al, Ti, etc., which forms a stable nitride. The use of acid elements is greatly limited, and CO
The present invention has been completed by paying attention to, for example, determining an appropriate range of the C content and the free oxygen content in the molten steel immediately before casting in order to keep the surface quality of the slab due to the generation of bubbles.
すなわち、本発明の要旨とするところは、重量で C:0.020％以下、 Si:0.10％以下、 Mn:0.05〜1.0％ Al:sol.Alとして0.002％以下、 N:0.0005〜0.0050％、 O:全Ｏとして0.0050〜0.0500％、 を含み、残部Feおよび不可避的不純物からなり、 が0.0005％以上である鋼を、鋳造直前の溶鋼の自由酸素
量〔％Ｏ〕を0.0050％以上としなおかつ〔％Ｃ〕×〔％
Ｏ〕を150×10-6以下となるように脱酸調整したのち連
続鋳造することを特徴とする、耐加熱黒変性に優れた溶
融Alめっき鋼板用鋳片の製造方法である。That is, the gist of the present invention is, by weight C: 0.020% or less, Si: 0.10% or less, Mn: 0.05 ~ 1.0% Al: sol.Al 0.002% or less, N: 0.0005 ~ 0.0050%, O: 0.0050-0.0500% as total O, including the balance Fe and unavoidable impurities, Of 0.0005% or more, the free oxygen amount [% O ] of molten steel immediately before casting is 0.0050% or more, and [% C] × [%
[O 2 ] is adjusted to deoxidize to 150 × 10 −6 or less and then continuously cast, which is a method for producing a slab for hot dip Al plated steel sheet excellent in heat black resistance.
Ｃを0.020％以下と限定したのは次の理由による。固溶
Ｎを確保する目的で脱酸元素であり、かつ安定な窒化物
形成元素であるAlの多量使用を避けながらCO気泡発生の
ない良好な表面性状の鋳片を得るためには、鋳造直前の
自由酸素量〔％Ｏ〕との関係において〔％Ｃ〕×〔％
Ｏ〕を150×10-6以下とすることが必要である。Ｃが0.0
20％を超えると必然的に脱酸元素としてのAlの使用量を
増やさねばならないが、それにより固溶Ｎを0.0005％以
上安定して確保することが困難となるので、Ｃ含有量の
上限を0.020％とした。The reason for limiting C to 0.020% or less is as follows. Immediately before casting, in order to obtain a slab with good surface properties without CO bubble generation while avoiding the large use of Al, which is a deoxidizing element and a stable nitride-forming element for the purpose of securing solid solution N In relation to the free oxygen amount [% O ] of [% C] × [%
It is necessary that O 2 ] be 150 × 10 −6 or less. C is 0.0
If it exceeds 20%, the amount of Al used as a deoxidizing element must be necessarily increased. However, it becomes difficult to stably secure the solid solution N of 0.0005% or more. Therefore, the upper limit of the C content is set. It was set to 0.020%.
Siは本発明においては、合金元素としても脱酸元素とし
ても積極的に使用するものではないが、不可避的に含有
される元素であり、その上限を0.10％と限定した。Siは
脱酸力の強い元素であり、0.10％を超えて含有されると
Ｃ含有量と自由酸素量の調整に支障を来たすので、これ
を上限とした。In the present invention, Si is not an element that is positively used as an alloying element or a deoxidizing element, but it is an element that is inevitably contained, and its upper limit is limited to 0.10%. Si is an element having a strong deoxidizing power, and if it is contained in excess of 0.10%, it will hinder the adjustment of the C content and the free oxygen content, so this was made the upper limit.
Mnは0.05〜1.0％の範囲とする。Mnが0.05％以下では熱
間加工性が著しく低下するので、これを下限とした。上
限については１％を超えると製品の加工性を低下させ、
いたずらに製造コストを高めるのみであるので、これを
上限とした。Mn is in the range of 0.05 to 1.0%. If Mn is less than 0.05%, the hot workability is significantly reduced, so this was made the lower limit. If the upper limit exceeds 1%, the workability of the product will be reduced,
This is an upper limit because it only unnecessarily increases the manufacturing cost.
Alは脱酸調整元素として本発明においては非常に重要な
元素である。脱酸元素として用いるが、しかし、sol.Al
として0.002％を超えて鋼中に含有させてはならない。s
ol.Alが0.002％を超えると鋼中Ｎと結合してAlNを形成
して、耐加熱黒変性に有効な固溶Ｎが減少し、黒変化温
度を著しく低下させるばかりではなく、微量のAlNの存
在により、製品の材料特性がきわめて不安定なものとな
るので、これを上限とした。Al is a very important element in the present invention as a deoxidizing adjustment element. Used as a deoxidizing element, but sol.Al
As a result, more than 0.002% must not be contained in steel. s
When ol.Al exceeds 0.002%, it forms AlN by combining with N in the steel to reduce the solid solution N that is effective for blackening resistance under heating, and not only significantly lowers the black transition temperature, but also a small amount of AlN. Due to the presence of, the material properties of the product become extremely unstable, so this was made the upper limit.
Ｎを0.0005〜0.0050％とし、なおかつ を0.0005％以上と限定したのは、次の理由による。溶融
Alめっき鋼板の黒変化温度は母材の により定義される固溶Ｎ含有量によって変化し、固溶Ｎ
が０％ではAlキルド鋼を母材とする場合と同様で黒変化
温度は約350℃、固溶Ｎが０％を超えて0.0005％未満の
範囲では黒変化温度は400℃以上520℃未満の範囲に上昇
するが、そのばらつきは大きく不安定である。固溶Ｎを
0.0005％以上とすることによりはじめて、リムド鋼を母
材とする場合と同様に、黒変化温度は約520℃と高い水
準で安定したものとなるので、これを下限とした。耐加
熱黒変性に関してはＮの上限はないが、Ｎ含有量が0.00
50％を超えると、製品の機械的性質や加工性が著しく劣
化するので、その上限を0.0050％とした。N is 0.0005 to 0.0050%, and Is limited to 0.0005% or more for the following reasons. Melting
The black change temperature of Al plated steel sheet is It depends on the solid solution N content defined by
Is 0% as in the case of using Al killed steel as the base material, the black change temperature is about 350 ° C, and the black change temperature is 400 ° C or more and less than 520 ° C in the range where the dissolved N exceeds 0% and is less than 0.0005%. Although it rises to the range, its variation is large and unstable. Solid solution N
Only when the content is 0.0005% or more, the black change temperature becomes stable at a high level of about 520 ° C, as in the case of using the rimmed steel as the base material, so this was made the lower limit. There is no upper limit of N for heat-resistant blackening, but N content of 0.00
If it exceeds 50%, the mechanical properties and workability of the product will be significantly deteriorated, so the upper limit was made 0.0050%.
Ｏは、耐加熱黒変性に直接的に関与する元素ではない
が、溶鋼を完全に脱酸しないことにより脱酸元素でかつ
窒化物形成元素であるAlの余剰添加を防止し、鋼中に固
溶Ｎを0.0005％以上確保する上で、Ｃとともに本発明の
根幹をなす重要な元素である。まず、CO気泡の発生を抑
止して、良好な表面性状の鋳片を得るためには、〔％
Ｃ〕×〔％Ｏ〕を150×10-6以下とすることが必要であ
る。ここで、Ｏの下限を0.0050％と限定したのは、Ｏを
0.0050％未満とするためには脱酸元素としてのAlを多量
に使用せねばならず、コスト面で不利であるばかりでな
く、酸化物のみならず窒化物をも形成して、耐加熱黒変
性に有効な固溶ＮがAlにより費消されてしまうので、こ
れを下限とした。またＯの上限を0.0500％と限定したの
はＯ含有量が0.0500％を超えると非金属介在物量が増加
することにより、製品の機械的性質の低下に結び付くば
かりでなく、〔％Ｃ〕×〔％Ｏ〕≦150×10-6の条件を
満足させるためにはＣ含有量をきわめて低くしなければ
ならずいたずらに製造コストを高めるのみであるので、
これを上限とした。O is not an element that is directly involved in the blackening resistance to heat resistance, but it does not completely deoxidize molten steel to prevent excessive addition of Al, which is a deoxidizing element and a nitride forming element, and solidifies in the steel. It is an important element that forms the basis of the present invention together with C in order to secure the molten N of 0.0005% or more. First, in order to suppress the generation of CO bubbles and obtain a slab with good surface properties, [%
It is necessary that C] × [% O 2 ] be 150 × 10 −6 or less. Here, the lower limit of O is limited to 0.0050% is that O is
In order to make it less than 0.0050%, a large amount of Al as a deoxidizing element must be used, which is not only disadvantageous in terms of cost but also forms not only an oxide but also a nitride, which is resistant to thermal blackening. Since the effective solid solution N is consumed by Al, this is the lower limit. Further, the upper limit of O is limited to 0.0500% because when the O content exceeds 0.0500%, the amount of non-metallic inclusions increases, which not only leads to deterioration of mechanical properties of the product, but also [% C] × [ % O 2 ] ≦ 150 × 10 −6 In order to satisfy the condition, the C content must be made extremely low, and only the manufacturing cost is unnecessarily increased.
This was set as the upper limit.
鋳造直前の自由酸素量〔％Ｏ〕を0.0050％以上とし、か
つ〔％Ｃ〕×〔％Ｏ〕を150×10-6以下となるように調
整するには、たとえば転炉でＣ含有量を約0.1％以下程
度まで脱炭した未脱酸の溶鋼を、RHなどの真空脱ガス処
理設備を用いてさらにＣ含有量が0.020％以下になるま
で脱炭し、その後Alなどの脱酸元素を溶鋼の自由酸素量
に応じて適量添加すればよい。In order to adjust the free oxygen amount [% O 2 ] immediately before casting to 0.0050% or more and the [% C] × [% O 2 ] to 150 × 10 −6 or less, for example, the C content in a converter is adjusted. Uncarburized molten steel decarburized to approximately 0.1% or less is further decarburized using a vacuum degassing facility such as RH until the C content is 0.020% or less, and then deoxidizing elements such as Al are removed. It may be added in an appropriate amount according to the amount of free oxygen in the molten steel.
＜実施例＞ 表１に示す鋼No.1〜７を転炉‐真空脱ガス処理によって
溶製し、連続鋳造により鋳片とした。真空脱ガス処理は
RH真空脱ガス設備を用いて行い、鋳造直前の自由酸素量
〔％Ｏ〕と〔％Ｃ〕×〔％Ｏ〕を次のようにして調整し
た。<Examples> Steel Nos. 1 to 7 shown in Table 1 were melted by a converter-vacuum degassing process, and cast into slabs by continuous casting. Vacuum degassing process
Using a RH vacuum degassing equipment, the free oxygen amount [% O 2 ] and [% C] × [% O 2 ] immediately before casting were adjusted as follows.
転炉では吹止め炭素濃度〔％Ｃ〕が0.03〜0.06％となる
ように吹錬し、この溶鋼をRH工程で槽内真空度が5Torr
以下になるように真空排気し、この真空度で10〜15分処
理する。これにより〔％Ｃ〕≦0.0070％の溶鋼を得る。
ここまでは通常行われている極低炭素鋼の溶製方法であ
る。In the converter, the blowing carbon concentration [% C] is blown so as to be 0.03 to 0.06%, and this molten steel is subjected to the RH process at a vacuum degree of 5 Torr.
Evacuate as follows and treat at this vacuum for 10 to 15 minutes. As a result, molten steel with [% C] ≦ 0.0070% is obtained.
The process up to this point is the usual melting method for ultra-low carbon steel.
この時点で，溶鋼の自由酸素量（Free〔％Ｏ〕）を測定
し，その測定値に応じてAlの投入量を決定する。この決
定にさいしては，本発明例の場合には,Al添加後のFree
〔％Ｏ〕が20ppm以上200ppm以下となるようにAl投入量
を調整する。Free〔％Ｏ〕がこの範囲にあれば溶鋼中の
Sol.Al量は0.002％以下，実質的にはTr.になる。At this point, the amount of free oxygen (Free [% O ]) in the molten steel is measured, and the amount of Al added is determined according to the measured value. In making this determination, in the case of the example of the present invention, Free after addition of Al
The amount of Al input is adjusted so that [% O 2 ] is 20 ppm or more and 200 ppm or less. If Free [% O ] is in this range,
The amount of Sol.Al is 0.002% or less, which is practically Tr.
実際には〔％Ｃ〕≦0.0070％まで脱炭されたときのFree
〔％Ｏ〕は通常100〜300ppmの範囲であり,Alを0.5〜1.0
kg/tの範囲で添加することにより，溶鋼中のFree〔％
Ｏ〕を20ppm以上200ppm以下の範囲とすることができ
る。そして，この範囲のFree〔％Ｏ〕が得られたか否か
を測定して確認する。もし200ppmを超える場合は，さら
に少量のAlを添加する。なおAl投入量が前記のように0.
5〜1.0kg/tの範囲では,Al投入後のFree〔％Ｏ〕が20ppm
未満となることはない。Actually Free when decarburized to [% C] ≤ 0.0070%
[% O ] is usually in the range of 100 to 300 ppm, and Al is 0.5 to 1.0
When added in the range of kg / t, the free [%
O 2 ] can be in the range of 20 ppm or more and 200 ppm or less. Then, it is measured and confirmed whether Free [% O ] in this range is obtained. If it exceeds 200ppm, add a small amount of Al. The amount of Al input was 0.
In the range of 5 to 1.0 kg / t, Free [% O ] after adding Al is 20 ppm.
It will never be less than.
これにより，処理後の〔％Ｃ〕×〔％Ｏ〕は0.007×0.0
200以下，すなわち150×10-6以下とすることができる。As a result, the [% C] x [% O ] after treatment is 0.007 x 0.0
It can be 200 or less, that is, 150 × 10 −6 or less.
また，窒素については，通常の操業において20ppm程度
以上である。したがって,0.0020−（14/27）×0.002＝
0.00096となり本発明で規定する0.0005％以上は確保さ
れる。なお，これ以上の窒素量が必要な場合は，例えば
窒化マンガンのような加窒剤を添加する。Regarding nitrogen, it is about 20ppm or more in normal operation. Therefore, 0.0020− (14/27) × 0.002 ＝
This is 0.00096, and 0.0005% or more specified in the present invention is secured. In addition, when the nitrogen amount beyond this is required, a nitrifying agent such as manganese nitride is added.
このようにして溶鋼中の自由酸素量〔％Ｏ〕，〔％Ｃ〕
×〔％Ｏ〕，〔％Ｎ〕−14/27〔Sol.Al〕を調整し，た
だちに連続鋳造して鋳片とした後，引続いて加熱温度12
00℃、仕上温度900℃、捲取温度600℃の条件で熱間圧延
して板厚を2.7mm、圧下率70％で板厚0.8mmまで冷間圧延
し、ガス還元型溶融Alめっきラインにより呼称めっき付
着量:80g/m2（両面）でいわゆるTypeI型のAl-9％Si合金
めっきを施したのち、伸び率１％の調質圧延を施したも
のを製品Ａとした。また上記の溶融Alめっきまでの工程
を経たものにさらに400℃×5hr（保持後炉冷）の低温箱
焼鈍を施したのち、伸び率１％の調質圧延を施したもの
を製品Ｂとした。In this way, the amount of free oxygen in molten steel [% O 2 ] and [% C]
× [% O ], [% N] -14/27 [Sol.Al] was adjusted, immediately continuous casting into a slab, and subsequently heating temperature 12
Hot rolling under conditions of 00 ℃, finishing temperature 900 ℃, winding temperature 600 ℃, plate thickness 2.7 mm, 70% reduction, cold rolling to 0.8 mm plate thickness, by gas reduction type molten Al plating line Product A was obtained by performing so-called Type I type Al-9% Si alloy plating with a nominal coating coverage of 80 g / m 2 (both sides) and then temper-rolling with an elongation of 1%. Further, the product that has been subjected to the steps up to the above-mentioned hot dip Al plating is further subjected to low temperature box annealing at 400 ° C. × 5 hr (furnace cooling after holding), and then temper-rolled with an elongation of 1% to obtain product B. .
また、比較材として低炭リムド鋼No.8および低炭Alキル
ド鋼No.9の0.88mm厚の冷延板を母材とする、いわゆるTy
peI型の溶融Alめっき鋼板（名目めっき付着量:80g/m
2（両面））についても、溶融Alめっきののちに伸び率
１％の調質圧延を施したものを製品Ａと、溶融Alめっき
ののちに、さらに400℃×5h、保持後炉冷の低温箱焼鈍
を施したのち、伸び率１％の調質圧延を施した製品Ｂと
を用意した。In addition, as a comparison material, the so-called Ty, which uses low-carbon rimmed steel No. 8 and low-carbon Al-killed steel No. 9 cold-rolled sheets with a thickness of 0.88 mm as the base material,
peI type hot-dip Al-plated steel sheet (nominal coating weight: 80 g / m
For 2 (both sides), hot-dip Al plating followed by temper rolling with an elongation of 1% was applied to product A, and after hot-dip Al plating, 400 ℃ x 5h, low temperature after holding furnace cooling After the box annealing, a product B that was temper-rolled with an elongation of 1% was prepared.
これらの製品について耐加熱黒変性を調べた。製品A,B
から50mm×50mmの試片を取り出し、電気マッフル炉にて
350℃〜600℃の種々の温度に24時間加熱したのち、めっ
き面の目視観察とＸ線回折および断面の光学顕微鏡観察
に供し、Alめっき皮膜の合金化の程度を判定した。ここ
ではAlめっき皮膜中にFe-Al系合金相が検出される最低
温度を黒変化温度と定義した。These products were examined for blackening resistance to heat. Product A, B
Take out a 50 mm x 50 mm sample from the
After heating at various temperatures from 350 ° C. to 600 ° C. for 24 hours, the plated surface was subjected to visual observation, X-ray diffraction and optical microscope observation of the cross section to determine the degree of alloying of the Al plating film. Here, the minimum temperature at which the Fe-Al alloy phase is detected in the Al plating film is defined as the black transition temperature.
No.1〜No.4はいずれも本発明の特許請求範囲内の鋼であ
り、鋳片はピンホール欠陥のきわめて少ない優れた性状
を表面を有し、溶融Alめっき鋼板の黒変化温度は製品Ａ
が520℃、製品Ｂが570℃と、いずれも低炭リムド鋼No.8
を母材とする場合と同等であることが明らかである。No. 1 to No. 4 are all steels within the scope of the claims of the present invention, the slab has a surface with excellent properties with very few pinhole defects, and the black change temperature of the hot dip Al plated steel sheet is the product A
520 ℃, product B is 570 ℃, both are low carbon rimmed steel No.8
It is clear that this is equivalent to the case of using as a base material.
No.5はＯ含有量および〔％Ｃ〕×〔％Ｏ〕が本発明の特
許請求範囲を外れるものであり、鋳片にはピンホール欠
陥が多発し、熱延板の段階で鋼板表面に綿状疵やヘゲ疵
が発生したため、その段階でスクラップ処理された。No. 5 has an O content and [% C] × [% O 2 ] which are outside the scope of the claims of the present invention, pinhole defects frequently occur in the slab, and the steel plate surface is formed at the stage of hot rolling. Since cotton-like flaws and bald spots occurred, they were scrapped at that stage.
No.6,7はAl含有量が本発明の特許請求範囲を 超え、かつ が本発明の特許請求範囲に満たないものであり、鋳片の
表面性状は良好であったが、No.6の溶融Alめっき鋼板の
黒変化温度は製品ＡおよびＢのいずれも350℃と、低炭A
lキルド鋼No.9を母材とする場合と同等であることが明
らかである。No. 6 and 7 have an Al content in the claims of the present invention. Exceed and Is less than the scope of claims of the present invention, the surface quality of the slab was good, the blackening temperature of No. 6 hot-dip Al-plated steel sheet is 350 ℃ for both products A and B, Low charcoal A
l It is clear that this is equivalent to using killed steel No. 9 as the base material.
またNo.7の溶融Alめっき鋼板の黒変化温度は製品Ａが42
0℃、製品Ｂが450℃と低炭Alキルド鋼No.9を母材とする
場合に比べるとかなり低いことが明らかである。The blackening temperature of No. 7 hot-dip Al-coated steel sheet is 42 for product A.
It is clear that the temperature is 0 ° C and product B is 450 ° C, which is considerably lower than the case where the low carbon Al killed steel No. 9 is used as the base material.
＜発明の効果＞ 以上説明したところから明らかなように、本発明を適用
することにより、連続鋳造により、耐加熱黒変性が低炭
リムド鋼を母材とする溶融Alめっき鋼板と同等である溶
融Alめっき鋼板用の鋳片を得ることが可能となる。<Effects of the Invention> As is apparent from the above description, by applying the present invention, the continuous casting results in heat-resistant blackening that is equivalent to that of the hot-dip Al-plated steel sheet using the low carbon rimmed steel as the base material. It becomes possible to obtain a slab for an Al-plated steel sheet.
Claims (1)
量〔％Ｏ〕を0.0050％以上とし、なおかつ〔％Ｃ〕×
〔％Ｏ〕を150×10-6以下となるように脱酸調整したの
ち連続鋳造することを特徴とする、溶融Alめっき鋼板用
鋳片の製造方法。1. By weight%, C: 0.020% or less, Si: 0.10% or less, Mn: 0.05 to 1.0%, Al: sol, 0.002% or less as Al, N: 0.0005 to 0.0050%, O: Total O as 0.0050-0.0500%, containing the balance Fe and unavoidable impurities, Of 0.0005% or more, the free oxygen amount [% O ] of the molten steel immediately before casting is 0.0050% or more, and [% C] ×
A method for producing a cast slab for hot dip Al-plated steel sheet, which comprises deoxidizing the [% O 2 ] to 150 × 10 −6 or less and then continuously casting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25194186A JPH0735527B2 (en) | 1986-10-24 | 1986-10-24 | Method for producing slab for hot dip Al plated steel sheet excellent in heat black resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25194186A JPH0735527B2 (en) | 1986-10-24 | 1986-10-24 | Method for producing slab for hot dip Al plated steel sheet excellent in heat black resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63109110A JPS63109110A (en) | 1988-05-13 |
| JPH0735527B2 true JPH0735527B2 (en) | 1995-04-19 |
Family
ID=17230254
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25194186A Expired - Fee Related JPH0735527B2 (en) | 1986-10-24 | 1986-10-24 | Method for producing slab for hot dip Al plated steel sheet excellent in heat black resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0735527B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110045037A (en) * | 2008-08-04 | 2011-05-03 | 누코 코포레이션 | Low cost manufacturing method of low carbon, low sulfur and low nitrogen steels using conventional steelmaking facilities |
| US11047015B2 (en) | 2017-08-24 | 2021-06-29 | Nucor Corporation | Manufacture of low carbon steel |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101473550B1 (en) | 2010-06-21 | 2014-12-16 | 신닛테츠스미킨 카부시키카이샤 | Hot-dip al-coated steel sheet with excellent thermal blackening resistance and process for production of same |
-
1986
- 1986-10-24 JP JP25194186A patent/JPH0735527B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110045037A (en) * | 2008-08-04 | 2011-05-03 | 누코 코포레이션 | Low cost manufacturing method of low carbon, low sulfur and low nitrogen steels using conventional steelmaking facilities |
| US11047015B2 (en) | 2017-08-24 | 2021-06-29 | Nucor Corporation | Manufacture of low carbon steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63109110A (en) | 1988-05-13 |
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