JP2023160552A - Method for heating continuously cast slab - Google Patents
Method for heating continuously cast slab Download PDFInfo
- Publication number
- JP2023160552A JP2023160552A JP2022070986A JP2022070986A JP2023160552A JP 2023160552 A JP2023160552 A JP 2023160552A JP 2022070986 A JP2022070986 A JP 2022070986A JP 2022070986 A JP2022070986 A JP 2022070986A JP 2023160552 A JP2023160552 A JP 2023160552A
- Authority
- JP
- Japan
- Prior art keywords
- slab
- heating
- temperature
- less
- heating furnace
- 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.)
- Pending
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 240
- 238000000034 method Methods 0.000 title claims abstract description 62
- 238000009749 continuous casting Methods 0.000 claims abstract description 17
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 12
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 12
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 6
- 238000005336 cracking Methods 0.000 abstract description 17
- 229910052717 sulfur Inorganic materials 0.000 abstract description 2
- 230000035882 stress Effects 0.000 description 38
- 229910000831 Steel Inorganic materials 0.000 description 35
- 239000010959 steel Substances 0.000 description 35
- 239000002344 surface layer Substances 0.000 description 18
- 230000000694 effects Effects 0.000 description 14
- 238000004458 analytical method Methods 0.000 description 13
- 230000008646 thermal stress Effects 0.000 description 12
- 238000005096 rolling process Methods 0.000 description 11
- 230000005856 abnormality Effects 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 238000001816 cooling Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 230000009466 transformation Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000005266 casting Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 238000004093 laser heating Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Images
Abstract
Description
本願は連続鋳造鋳片の加熱方法を開示する。 This application discloses a method for heating continuously cast slabs.
近年、様々な技術分野において高張力鋼が使用されている。例えば、自動車の分野においては、燃費改善を実現するために、高張力鋼の適用による自動車車体の軽量化が進められている。また、搭乗者の安全性確保のためにも、自動車車体に高張力鋼が多く使用されるようになってきている。 In recent years, high-strength steel has been used in various technical fields. For example, in the field of automobiles, efforts are being made to reduce the weight of automobile bodies by applying high-strength steel in order to improve fuel efficiency. Furthermore, high-tensile steel is increasingly being used in automobile bodies to ensure the safety of passengers.
高張力鋼は、強度の向上を狙って、C、Si及びMnが多量に添加されてなる。ここで、C、Si及びMnの多量の添加は鋼材を脆化させることが知られている。そのため、C、Si及びMnが多量に添加された鋼を連続鋳造して鋳片を得た後に、当該鋳片を加熱炉にて加熱すると、鋳片の表面と内部との温度差に起因する熱ひずみや、変態に伴う変態ひずみによって、鋳片に割れが発生し易い。 High-strength steel is made by adding large amounts of C, Si, and Mn to improve strength. Here, it is known that addition of large amounts of C, Si, and Mn makes the steel material brittle. Therefore, when a slab is obtained by continuous casting of steel to which large amounts of C, Si, and Mn are added, and then heated in a heating furnace, the temperature difference between the surface and the inside of the slab results in Cracks tend to occur in slabs due to thermal strain and transformation strain associated with transformation.
従来技術においては、連続鋳造後の鋳片を加熱炉にて加熱する際、脆化域における加熱速度を制御し、緩やかな加熱(スローヒート)を行って鋳片表面と内部との温度偏差を低減することにより、応力やひずみを抑制する対策がとられてきた(特許文献1~3)。また、鋳片を加熱炉に装入する前に、所定の温度域で鋳片を加熱及び圧下して鋳片中心のポロシティを圧着することで、加熱炉にて加熱した際の鋳片割れを抑制する技術も開示されている(特許文献4)。 In conventional technology, when a slab after continuous casting is heated in a heating furnace, the heating rate in the embrittlement region is controlled, and the temperature deviation between the surface and inside of the slab is controlled by performing slow heating. Measures have been taken to suppress stress and strain by reducing them (Patent Documents 1 to 3). In addition, before charging the slab into the heating furnace, the slab is heated in a predetermined temperature range and pressed down to compress the porosity at the center of the slab, thereby suppressing cracking of the slab when heated in the heating furnace. A technique to do so has also been disclosed (Patent Document 4).
特許文献1~3に開示されているように加熱炉における鋳片の加熱速度を細かく制御することや、特許文献4に開示されているように加熱炉において鋳片を加熱する前に鋳片に対して圧下を加えることは、設備や物流の制約上、難しい場合がある。この点、加熱炉における加熱の際に鋳片の割れを抑制可能な新たな技術が必要である。 As disclosed in Patent Documents 1 to 3, the heating rate of the slab in the heating furnace is finely controlled, and as disclosed in Patent Document 4, the heating rate of the slab in the heating furnace is controlled. However, it may be difficult to apply pressure due to equipment and logistics constraints. In this regard, a new technology is needed that can suppress cracking of slabs during heating in a heating furnace.
本願は上記課題を解決するための手段の一つとして、
連続鋳造方法により鋳造された鋳片を、加熱炉に装入する前に加熱する方法であって、
前記鋳片が、質量%で、C:0.02~0.60%、Si:0.5~3.0%、Mn:1.0~3.0%、P:0.100%以下、S:0.010%以下、Al:0.005~1.000%、及び、N:0.0100%以下を含有し、
前記鋳片の表面の少なくとも一部が急速加熱され、
前記急速加熱により、前記鋳片の表面から鋳片厚みの10%以内の領域が、150℃/min以上の昇温速度、且つ、150℃以上の温度上昇量で、Ae1点未満の温度まで加熱され、
前記急速加熱の後、前記鋳片が前記加熱炉に装入される、
連続鋳造鋳片の加熱方法
を開示する。
This application, as one of the means to solve the above problems,
A method of heating a slab cast by a continuous casting method before charging it into a heating furnace, the method comprising:
The slab, in mass %, C: 0.02 to 0.60%, Si: 0.5 to 3.0%, Mn: 1.0 to 3.0%, P: 0.100% or less, Contains S: 0.010% or less, Al: 0.005 to 1.000%, and N: 0.0100% or less,
At least a portion of the surface of the slab is rapidly heated,
By the rapid heating, a region within 10% of the thickness of the slab from the surface of the slab is heated to a temperature below Ae 1 point at a temperature increase rate of 150 ° C / min or more and a temperature increase of 150 ° C or more. is,
After the rapid heating, the slab is charged into the heating furnace.
A method for heating continuously cast slabs is disclosed.
本開示の方法においては、前記鋳片の幅方向に沿った表面の少なくとも一部が急速加熱されてもよい。 In the method of the present disclosure, at least a portion of the surface of the slab along the width direction may be rapidly heated.
本開示の方法においては、前記鋳片の幅方向に沿った両面の各々の少なくとも一部が急速加熱されてもよい。 In the method of the present disclosure, at least a portion of each of both sides of the slab in the width direction may be rapidly heated.
本開示の方法においては、前記鋳片の幅方向に沿った表面の一部が急速加熱され、且つ、急速加熱される前記表面の幅WHが鋳片の全幅Wの1/8以上3/4以下であってもよい。 In the method of the present disclosure, a part of the surface along the width direction of the slab is rapidly heated, and the width W H of the rapidly heated surface is 1/8 or more and 3/8 of the total width W of the slab. It may be 4 or less.
本開示の方法によれば、加熱炉において鋳片を加熱した際、鋳片の割れが発生し難い。 According to the method of the present disclosure, when the slab is heated in a heating furnace, cracking of the slab is less likely to occur.
従来技術においては、加熱炉における加熱速度を制御して、鋳片を緩やかに加熱して、鋳片の表面と内部との間にできるだけ温度差を設けないようにすることで、加熱炉での加熱過程における鋳片の割れを抑制している。しかしながら、設備や物流の制約上、このような温度制御が難しい場合がある。本発明者は、加熱炉での加熱過程において鋳片の割れを抑制できる方法を、熱応力解析を活用して探索した。その結果、加熱炉における加熱の前に、鋳片表面の少なくとも一部を急速加熱して熱履歴を付与することにより、加熱炉での加熱過程において鋳片中心部に発生する応力を低減でき、鋳片の割れを顕著に抑制できることを見出した。以下、本開示の連続鋳造鋳片の加熱方法について詳細に説明する。 In the conventional technology, the heating rate in the heating furnace is controlled, the slab is heated slowly, and the temperature difference between the surface and the inside of the slab is minimized as much as possible. This suppresses cracking of slabs during the heating process. However, such temperature control may be difficult due to equipment and logistics constraints. The present inventor utilized thermal stress analysis to search for a method that can suppress cracking of slabs during the heating process in a heating furnace. As a result, by rapidly heating at least a portion of the surface of the slab to give it a thermal history before heating in the heating furnace, it is possible to reduce the stress generated in the center of the slab during the heating process in the heating furnace. It has been found that cracking of slabs can be significantly suppressed. Hereinafter, the method of heating continuously cast slabs of the present disclosure will be described in detail.
本開示の方法は、連続鋳造方法により鋳造された鋳片を、加熱炉に装入する前に加熱する方法である。前記鋳片は、質量%で、C:0.02~0.60%、Si:0.5~3.0%、Mn:1.0~3.0%、P:0.100%以下、S:0.010%以下、Al:0.005~1.000%、及び、N:0.0100%以下を含有する。本開示の方法においては、前記鋳片の表面の少なくとも一部が急速加熱される。前記急速加熱により、前記鋳片の表面から鋳片厚みの10%以内の領域が、150℃/min以上の昇温速度、且つ、150℃以上の温度上昇量にて、Ae1点未満の温度まで加熱される。本開示の方法においては、前記急速加熱の後、前記鋳片が前記加熱炉に装入される。 The method of the present disclosure is a method in which a slab cast by a continuous casting method is heated before being charged into a heating furnace. The slab contains, in mass%, C: 0.02 to 0.60%, Si: 0.5 to 3.0%, Mn: 1.0 to 3.0%, P: 0.100% or less, Contains S: 0.010% or less, Al: 0.005 to 1.000%, and N: 0.0100% or less. In the method of the present disclosure, at least a portion of the surface of the slab is rapidly heated. By the rapid heating, the area within 10% of the thickness of the slab from the surface of the slab reaches a temperature of less than 1 point Ae at a temperature increase rate of 150 ° C / min or more and a temperature increase of 150 ° C or more. heated. In the method of the present disclosure, after the rapid heating, the slab is charged into the heating furnace.
1.連続鋳造鋳片
本開示の方法においては、まず、連続鋳造方法により鋳片を得る。連続鋳造条件は特に限定されるものではなく、従来と同様の条件であってよい。
1. Continuous Casting Slab In the method of the present disclosure, first, a slab is obtained by a continuous casting method. Continuous casting conditions are not particularly limited, and may be the same as conventional conditions.
1.1 鋳片の形状
連続鋳造方法により鋳造される鋳片は、スラブであっても、ブルームであっても、ビレットであってもよい。特に、スラブ又はブルームであることが好ましく、スラブであることがより好ましい。鋳片は、連続鋳造方向と直交する断面形状において、幅及び厚みを有し、また、連続鋳造方向に長さを有するものであってよい。鋳片がスラブである場合、その幅は、連続鋳造方向と直交する断面形状における長辺(鋳型長辺と対応)に相当し、その厚みは、当該断面形状における短辺(鋳型短辺と対応)に相当する。また、鋳片がブルームまたはビレットである場合、一般に、スラブに比べてアスペクト比(長辺の長さ/短辺の長さ)が小さい。断面形状が円の場合、その厚みや幅とは、断面の直径をいうものとする。鋳片がスラブである場合、その幅は、例えば、800mm以上1500mm以下であってもよく、その厚みは、例えば、100mm以上300mm以下であってもよく、その長さは、例えば、5m以上9m以下であってもよい。
1.1 Shape of slab The slab cast by the continuous casting method may be a slab, bloom, or billet. In particular, a slab or a bloom is preferable, and a slab is more preferable. The slab may have a width and a thickness in a cross-sectional shape perpendicular to the continuous casting direction, and may have a length in the continuous casting direction. If the slab is a slab, its width corresponds to the long side (corresponding to the long side of the mold) in the cross-sectional shape perpendicular to the continuous casting direction, and its thickness corresponds to the short side (corresponding to the short side of the mold) in the cross-sectional shape. ). Further, when the slab is a bloom or a billet, the aspect ratio (long side length/short side length) is generally smaller than that of a slab. When the cross-sectional shape is a circle, the thickness and width refer to the diameter of the cross-section. When the slab is a slab, its width may be, for example, 800 mm or more and 1500 mm or less, its thickness may be, for example, 100 mm or more and 300 mm or less, and its length may be, for example, 5 m or more and 9 m or less. It may be the following.
1.2 鋳片の化学組成
鋳片は、C、Si、Mnを所定量以上含むもので、例えば、高張力鋼板の素材として用いられるものであってよい。本願において「高張力鋼板」とは、引張強さが500MPa以上の鋼板をいう。引張強さは780MPa以上、980MPa以上、1180MPa以上又は1470MPa以上であってよく、2100MPa以下、2000MPa以下又は1900MPa以下であってもよい。尚、鋼板の引張試験は、例えば、JIS Z 2241に準拠し、試験片の長手方向が鋼板の圧延直角方向と平行になる向きからJIS5号試験片を採取して行う。
1.2 Chemical composition of slab The slab contains C, Si, and Mn in a predetermined amount or more, and may be used as a material for high-strength steel sheets, for example. In this application, the term "high-strength steel plate" refers to a steel plate with a tensile strength of 500 MPa or more. The tensile strength may be 780 MPa or more, 980 MPa or more, 1180 MPa or more, or 1470 MPa or more, and may be 2100 MPa or less, 2000 MPa or less, or 1900 MPa or less. The tensile test of the steel plate is performed, for example, in accordance with JIS Z 2241, by taking a JIS No. 5 test piece from a direction in which the longitudinal direction of the test piece is parallel to the direction perpendicular to the rolling direction of the steel plate.
鋳片は、質量%で、C:0.02~0.60%、Si:0.5~3.0%、Mn:1.0~3.0%、P:0.100%以下、S:0.010%以下、Al:0.005~1.000%、及び、N:0.0100%以下を含有する。C、Si及びMnの含有量がこのような範囲である場合、鋳片の脆性が低下し易く、加熱炉での加熱過程における割れの問題が発生し易いところ、本開示の方法によって、当該割れを抑制できる。尚、本願において、数値範囲を示す「~」とは、特に断りがない場合、その前後に記載される数値を下限値及び上限値として含む意味で使用される。 The slab contains C: 0.02 to 0.60%, Si: 0.5 to 3.0%, Mn: 1.0 to 3.0%, P: 0.100% or less, S : 0.010% or less, Al: 0.005 to 1.000%, and N: 0.0100% or less. When the content of C, Si, and Mn is in such a range, the brittleness of the slab tends to decrease, and cracks are likely to occur during the heating process in a heating furnace. can be suppressed. In this application, unless otherwise specified, "~" indicating a numerical range is used to include the numerical values written before and after it as the lower limit and upper limit.
(C:0.02~0.60%)
Cは鋼の静的強度だけでなく、疲労強度、靭性、延性に影響する最も基本的な元素である。Cが少な過ぎると鋼の静的強度及び疲労強度が不十分となる場合がある。この点、Cの含有量の下限は0.02質量%、0.05質量%、0.10質量%又は0.15質量%であってもよい。また、Cが多過ぎると鋼の靭性が過度に劣化し易い。この点、Cの含有量の上限は0.60質量%、0.50質量%、0.40質量%又は0.30質量%であってもよい。
(C: 0.02-0.60%)
C is the most fundamental element that affects not only the static strength of steel, but also its fatigue strength, toughness, and ductility. If C is too small, the static strength and fatigue strength of the steel may become insufficient. In this regard, the lower limit of the C content may be 0.02% by mass, 0.05% by mass, 0.10% by mass, or 0.15% by mass. Moreover, if there is too much C, the toughness of the steel tends to deteriorate excessively. In this regard, the upper limit of the content of C may be 0.60% by mass, 0.50% by mass, 0.40% by mass, or 0.30% by mass.
(Si:0.5~3.0%)
SiはCに次いで固溶強化能が大きい重要な元素である。高張力鋼を得る場合はSiの濃度を高濃度とする。具体的には、Siの含有量の下限は0.5質量%、0.8質量%又は1.0質量%であってもよい。一方で、Siの含有量が多過ぎると靭性や加工性を劣化させる虞がある。この点、Siの含有量の上限は3.0質量%、2.5質量%又は2.0質量%であってもよい。
(Si: 0.5-3.0%)
Si is an important element that has the highest solid solution strengthening ability next to C. When obtaining high tensile strength steel, the concentration of Si is increased. Specifically, the lower limit of the Si content may be 0.5% by mass, 0.8% by mass, or 1.0% by mass. On the other hand, if the Si content is too high, there is a risk that toughness and workability will be deteriorated. In this regard, the upper limit of the Si content may be 3.0% by mass, 2.5% by mass, or 2.0% by mass.
(Mn:1.0~3.0%)
Mnは焼入れ性を向上させ、冷却速度が不十分な場合でも鋼材の内部まで硬度を確保するのに重要な元素である。高張力鋼を得る場合はMnの濃度を高濃度とする。具体的には、Mnの含有量の下限は1.0質量%又は1.5質量%であってもよい。一方で、Mnが多過ぎると靭性や加工性を劣化させる虞がある。この点、Mnの含有量の上限は3.0質量%又は2.8質量%であってもよい。
(Mn: 1.0-3.0%)
Mn is an important element for improving hardenability and ensuring hardness deep into the steel material even when the cooling rate is insufficient. When obtaining high tensile strength steel, the Mn concentration is increased. Specifically, the lower limit of the Mn content may be 1.0% by mass or 1.5% by mass. On the other hand, too much Mn may deteriorate toughness and workability. In this regard, the upper limit of the Mn content may be 3.0% by mass or 2.8% by mass.
(P:0.100%以下)
Pは、溶鋼の凝固過程において未凝固部へのMn濃化を促進する元素であり、負偏析部のMn濃度を下げ、フェライトの面積率の増加を促す元素であり、少ないほど好ましい。また、Pを過度に含有すると鋼強度は増加する一方で鋼の脆性的な破壊を招く場合がある。この点、Pの含有量の上限は、0.100質量%、0.050質量%又は0.010質量%であってもよい。一方で、Pの含有量の下限は特に限定されるものではなく、0質量%であってもよいが、Pの含有量を0.001質量%未満に制御することは精錬時間の増大とともに、製造コストの増加を招く虞がある。製造コストの上昇を防ぐ狙いからは、Pの含有量は0.001質量%以上であってもよい。
(P: 0.100% or less)
P is an element that promotes Mn concentration in the unsolidified portion during the solidification process of molten steel, lowers the Mn concentration in the negatively segregated portion, and promotes an increase in the area ratio of ferrite, and the smaller the amount, the better. Furthermore, while excessive P content may increase steel strength, it may cause brittle fracture of the steel. In this regard, the upper limit of the P content may be 0.100% by mass, 0.050% by mass, or 0.010% by mass. On the other hand, the lower limit of the P content is not particularly limited and may be 0% by mass, but controlling the P content to less than 0.001% by mass increases the refining time and This may lead to an increase in manufacturing costs. In order to prevent an increase in manufacturing costs, the P content may be 0.001% by mass or more.
(S:0.010%以下)
Sは、鋼中でMnS等の非金属介在物を生成し、鋼の延性の低下を招く元素であり、少ないほど好ましい。この点、Sの含有量の上限は、0.010質量%、0.008質量%又は0.005質量%であってもよい。一方で、Sの含有量の下限は特に限定されるものではなく、0質量%であってもよく、0.001質量%であってもよい。
(S: 0.010% or less)
S is an element that generates nonmetallic inclusions such as MnS in steel and causes a decrease in the ductility of the steel, and the smaller the amount, the better. In this regard, the upper limit of the S content may be 0.010% by mass, 0.008% by mass, or 0.005% by mass. On the other hand, the lower limit of the S content is not particularly limited, and may be 0% by mass or 0.001% by mass.
(Al:0.005~1.000%)
Alは、鋼の脱酸剤として作用しフェライトを安定化する元素である。Alの含有量が0.005質量%以上である場合に、このような効果が得られ易い。Alの含有量は0.010質量%以上であってもよい。一方、Alを過度に含有すると下工程における焼鈍時の冷却過程でのフェライト変態及びベイナイト変態が過度に促進されて鋼の強度が低下する場合がある。Alの含有量が1.000質量%以下である場合に、このような問題が回避され易い。Alの含有量は0.800質量%以下であってもよい。
(Al: 0.005-1.000%)
Al is an element that acts as a deoxidizer for steel and stabilizes ferrite. Such effects are likely to be obtained when the Al content is 0.005% by mass or more. The content of Al may be 0.010% by mass or more. On the other hand, if Al is contained excessively, ferrite transformation and bainite transformation may be excessively promoted during the cooling process during annealing in the lower process, resulting in a decrease in the strength of the steel. Such problems can be easily avoided when the Al content is 1.000% by mass or less. The content of Al may be 0.800% by mass or less.
(N:0.0100%以下)
Nは、粗大な窒化物を形成し、鋼の加工性を低下させる元素であり、少ないほど好ましい。Nの含有量は0質量%であってもよく、0.0001質量%以上であってもよく、0.0010質量%以上であってもよく、また、0.0100質量%以下であってもよく、0.0050質量%以下であってもよい。
(N: 0.0100% or less)
N is an element that forms coarse nitrides and reduces the workability of steel, and the smaller the amount, the better. The content of N may be 0% by mass, 0.0001% by mass or more, 0.0010% by mass or more, or 0.0100% by mass or less. It may be 0.0050% by mass or less.
鋳片は、上記の基本元素のほか、上記以外の任意元素を含んでいてもよい。任意元素は含まれなくてもよいため、その下限は0%である。鋳片は、例えば、質量%で、Ti:0~0.500%、Co:0~0.500%、Ni:0~0.500%、Mo:0~0.500%、Cr:0~2.000%、O:0~0.0100%、B:0~0.0100%、Nb:0~0.500%、V:0~0.500%、Cu:0~0.500%、W:0~0.1000%、Ta:0~0.1000%、Sn:0~0.0500%、Sb:0~0.0500%、As:0~0.0500%、Mg:0~0.0500%、Ca:0~0.0500%、Y:0~0.0500%、Zr:0~0.0500%、La:0~0.0500%、及び、Ce:0~0.0500%から選ばれる1種以上を含んでいてもよい。尚、上記の任意元素の種類及び含有量は単なる例示であり、鋳片に含まれ得る任意元素の種類や量は、上記のもの限定されない。 In addition to the above-mentioned basic elements, the slab may contain arbitrary elements other than those mentioned above. Since the optional element does not need to be included, the lower limit is 0%. The slab has, for example, Ti: 0-0.500%, Co: 0-0.500%, Ni: 0-0.500%, Mo: 0-0.500%, Cr: 0-0. 2.000%, O: 0 to 0.0100%, B: 0 to 0.0100%, Nb: 0 to 0.500%, V: 0 to 0.500%, Cu: 0 to 0.500%, W: 0-0.1000%, Ta: 0-0.1000%, Sn: 0-0.0500%, Sb: 0-0.0500%, As: 0-0.0500%, Mg: 0-0 .0500%, Ca: 0-0.0500%, Y: 0-0.0500%, Zr: 0-0.0500%, La: 0-0.0500%, and Ce: 0-0.0500% It may contain one or more types selected from. Note that the types and amounts of the above-mentioned arbitrary elements are merely examples, and the types and amounts of the arbitrary elements that can be included in the slab are not limited to those described above.
1.3 急速加熱前の鋳片の温度
鋳片の温度は、加熱炉への装入の前に後述する急速加熱を実施可能である限り、特に限定されるものではない。鋳片は放冷等を経て冷却されたものであってもよい。後述の急速加熱を行う前において、鋳片の表面温度は、Ae1から150℃超低い温度であってもよく、例えば、0℃以上600℃以下であってもよい。また、後述の急速加熱を行う前において、鋳片の中心温度は、Ae1から150℃超低い温度であってもよく、例えば、0℃以上600℃以下であってもよい。また、後述の急速加熱を行う前において、鋳片の表面温度と鋳片の中心温度との差の絶対値は、例えば、0℃以上600℃以下であってもよい。尚、後述する急速加熱による効果は、急速加熱の開始時点での鋳片温度に実質的に左右されない。すなわち、急速加熱前の鋳片がどのような温度であったとしても、急速加熱によって所望の効果が奏される。
1.3 Temperature of slab before rapid heating The temperature of the slab is not particularly limited as long as rapid heating described below can be performed before charging into the heating furnace. The slab may be cooled through cooling or the like. Before performing the rapid heating described below, the surface temperature of the slab may be more than 150°C lower than Ae1, for example, 0°C or more and 600°C or less. Moreover, before performing the rapid heating described below, the center temperature of the slab may be more than 150° C. lower than Ae1, for example, 0° C. or more and 600° C. or less. Further, before performing the rapid heating described below, the absolute value of the difference between the surface temperature of the slab and the center temperature of the slab may be, for example, 0° C. or more and 600° C. or less. Note that the effects of rapid heating, which will be described later, are not substantially affected by the temperature of the slab at the start of rapid heating. That is, no matter what temperature the slab is before rapid heating, the desired effect can be achieved by rapid heating.
2.急速加熱
本開示の方法においては、鋳片を加熱炉に装入する前に、鋳片表面の少なくとも一部を急速加熱することで、鋳片表面の少なくとも一部に圧縮の塑性変形を生じさせ、これにより、加熱炉での加熱過程において鋳片内部に生じる引張応力を低減する。通常、加熱炉内での加熱過程においては、輻射熱により鋳片の表面から加熱される。そのため、鋳片表面が熱膨張し、これに伴い鋳片内部に引張応力が生じ、割れへと繋がる。これに対し、本開示の方法によって鋳片表面に予め圧縮の塑性変形を生じさせることで、加熱炉での加熱過程で鋳片表面が熱膨張したとしても、鋳片内部に生じる引張応力は大きくなり難く、結果として、鋳片の割れが抑制される。具体的には、本開示の方法においては、上述の鋳片が加熱炉に装入される前に、鋳片の表面の少なくとも一部が急速加熱され、当該急速加熱により、鋳片の表面から鋳片厚みの10%以内の領域が、150℃/min以上の昇温速度、且つ、150℃以上の温度上昇量にて、Ae1点未満の温度まで加熱される。
2. Rapid Heating In the method of the present disclosure, at least a portion of the surface of the slab is rapidly heated before charging the slab into the heating furnace, thereby causing compressive plastic deformation on at least a portion of the surface of the slab. This reduces the tensile stress generated inside the slab during the heating process in the heating furnace. Usually, during the heating process in a heating furnace, the surface of the slab is heated by radiant heat. As a result, the surface of the slab undergoes thermal expansion, which causes tensile stress to occur inside the slab, leading to cracking. In contrast, by creating compressive plastic deformation on the slab surface in advance using the method of the present disclosure, even if the slab surface thermally expands during the heating process in the heating furnace, the tensile stress generated inside the slab will be large. As a result, cracking of the slab is suppressed. Specifically, in the method of the present disclosure, at least a portion of the surface of the slab is rapidly heated before the slab is charged into the heating furnace, and due to the rapid heating, the surface of the slab is heated. A region within 10% of the slab thickness is heated to a temperature below Ae 1 point at a temperature increase rate of 150° C./min or more and a temperature increase amount of 150° C. or more.
2.1 鋳片表面において急速加熱される部分
本開示の方法においては、鋳片の表面のうち少なくとも一部が急速加熱されればよい。加熱炉での加熱過程において鋳片の割れの発生を抑制したい箇所に応じて、鋳片表面のうち急速加熱される部分が決定される。本開示の方法においては、鋳片表面の全体が急速加熱されてもよいし、鋳片表面の一部が急速加熱されてもよい。
2.1 Portion to be rapidly heated on the surface of the slab In the method of the present disclosure, at least a portion of the surface of the slab may be rapidly heated. The portion of the surface of the slab that is rapidly heated is determined depending on the location where it is desired to suppress the occurrence of cracks in the slab during the heating process in the heating furnace. In the method of the present disclosure, the entire surface of the slab may be rapidly heated, or a portion of the surface of the slab may be rapidly heated.
本開示の方法においては、図1及び2に示されるように、鋳片の幅方向に沿った表面(鋳片の広い面)の少なくとも一部が急速加熱されることが好ましい。鋳片の幅方向に沿った面が急速加熱された場合、急速加熱された部分と鋳片中心との距離が近く、急速加熱によって生じる圧縮塑性変形による効果が、鋳片中心にまで及び易くなり、加熱炉での加熱過程において鋳片内部に生じる引張応力が一層低減され易い。 In the method of the present disclosure, as shown in FIGS. 1 and 2, it is preferable that at least a portion of the surface along the width direction of the slab (the wide surface of the slab) is rapidly heated. When the surface along the width of the slab is rapidly heated, the distance between the rapidly heated part and the center of the slab is close, and the effect of compressive plastic deformation caused by rapid heating is likely to reach the center of the slab. , the tensile stress generated inside the slab during the heating process in the heating furnace is more likely to be reduced.
また、本開示の方法においては、図1及び2に示されるように、鋳片の幅方向に沿った両面の各々の少なくとも一部が急速加熱されることがより好ましい。特に、図1及び2に示されるように、鋳片の鋳造方向に対して直交する断面において、鋳片の幅方向に沿った両面の各々の少なくとも一部が急速加熱され、且つ、一方の面の急速加熱される部分A1と、多方の面の急速加熱される部分A2とが、鋳片中心Oを挟んで互いに対向することが好ましい。このように、鋳片の両面を急速加熱することで、鋳片の反りや変形が抑えられるとともに、急速加熱によって生じる圧縮塑性変形による効果が、鋳片中心にまで一層及び易くなり、加熱炉での加熱過程において鋳片内部に生じる引張応力が特に顕著に低減され易い。 Further, in the method of the present disclosure, as shown in FIGS. 1 and 2, it is more preferable that at least a portion of each of both sides of the slab along the width direction is rapidly heated. In particular, as shown in FIGS. 1 and 2, in a cross section perpendicular to the casting direction of the slab, at least a portion of each of both sides along the width direction of the slab is rapidly heated, and one side It is preferable that the rapidly heated portion A1 on the other side and the rapidly heated portion A2 on many sides face each other with the slab center O in between. In this way, by rapidly heating both sides of the slab, warpage and deformation of the slab can be suppressed, and the effect of compressive plastic deformation caused by rapid heating can be more easily extended to the center of the slab, making it possible to The tensile stress generated inside the slab during the heating process is particularly likely to be significantly reduced.
また、本開示の方法においては、図1及び2に示されるように、鋳片の厚み方向に沿った表面(鋳片の狭い面)ではなく、鋳片の幅方向に沿った表面のみが急速加熱されることが好ましい。鋳片の厚み方向に沿った表面については、急速加熱を施しても、圧縮塑性変形による効果が鋳片の中心にまで届き難い。本開示の方法においては、鋳片の幅方向に沿った表面のみが急速加熱されることで充分な効果が得られる。 In addition, in the method of the present disclosure, as shown in FIGS. 1 and 2, only the surface along the width direction of the slab, rather than the surface along the thickness direction of the slab (the narrow side of the slab), is rapidly Preferably, it is heated. Even if rapid heating is applied to the surface along the thickness direction of the slab, the effect of compressive plastic deformation is difficult to reach the center of the slab. In the method of the present disclosure, a sufficient effect can be obtained by rapidly heating only the surface along the width direction of the slab.
また、本開示の方法においては、図1及び2に示されるように、鋳片の幅方向に沿った表面の一部が急速加熱され、且つ、急速加熱される表面の幅WHが鋳片の全幅Wの1/8以上3/4以下であることが好ましい。特に、図2に示されるように、幅WHが幅Wの1/8以上3/4以下で、且つ、急速加熱される部分が鋳片の幅方向中央を含んでいることが好ましく、急速加熱される部分の幅方向中央が、鋳片の幅方向中央と実質的に一致していることがより好ましい。本発明者の知見によれば、鋳片の幅全体ではなく一部のみを加熱することで、エネルギーコストを抑えることができるほか、幅方向の圧縮応力を抑えることができ、すなわち、圧縮応力を鋳片の長手方向に生じさせ易くなり、鋳片の長手方向に圧縮塑性ひずみを発生させ易くなり、加熱炉での加熱過程における鋳片割れの発生を一層効果的に抑制することができる。また、加熱炉での加熱過程における鋳片割れは、鋳片の中心Oの近傍(すなわち、幅方向中央近傍)において特に生じ易いところ、鋳片の幅方向中央近傍のみが急速加熱されることで、急速加熱による圧縮塑性変形の効果が鋳片の中心へと一層及び易くなり、加熱炉での加熱過程において鋳片中心に生じる引張応力が一層低減され易くなる。 Furthermore, in the method of the present disclosure, as shown in FIGS. 1 and 2, a part of the surface along the width direction of the slab is rapidly heated, and the width W H of the rapidly heated surface is It is preferable that the total width W is 1/8 or more and 3/4 or less. In particular, as shown in FIG. 2, it is preferable that the width W H is 1/8 or more and 3/4 or less of the width W, and that the portion to be rapidly heated includes the center in the width direction of the slab. More preferably, the widthwise center of the portion to be heated substantially coincides with the widthwise center of the slab. According to the findings of the present inventor, by heating only a part of the slab width instead of the entire width, energy costs can be reduced and compressive stress in the width direction can be suppressed. This makes it easier to generate compressive plastic strain in the longitudinal direction of the slab, making it easier to generate compressive plastic strain in the longitudinal direction of the slab, making it possible to more effectively suppress the occurrence of cracks in the slab during the heating process in the heating furnace. In addition, slab cracking during the heating process in the heating furnace is particularly likely to occur near the center O of the slab (i.e., near the center in the width direction), but by rapidly heating only the vicinity of the center in the width direction of the slab, The effect of compressive plastic deformation due to rapid heating is more likely to reach the center of the slab, and the tensile stress generated at the center of the slab during the heating process in the heating furnace is more likely to be reduced.
また、本開示の方法においては、図1に示されるように、鋳片の幅方向に沿った表面の少なくとも一部が、鋳片の長手方向(長さ方向)の全長に亘って急速加熱されることが好ましい。これにより、急速加熱部において長手方向の圧縮応力を強く発生させることができ、長手方向の圧縮塑性ひずみを発生させることができ、加熱炉での加熱過程における鋳片割れの発生を一層効果的に抑制することができる。 Further, in the method of the present disclosure, as shown in FIG. 1, at least a part of the surface of the slab along the width direction is rapidly heated over the entire length of the slab in the longitudinal direction (length direction). It is preferable that As a result, it is possible to generate strong compressive stress in the longitudinal direction in the rapid heating section, and compressive plastic strain in the longitudinal direction, which more effectively suppresses the occurrence of slab cracking during the heating process in the heating furnace. can do.
2.2 鋳片断面において急速加熱される領域
急速加熱による鋳片表層の圧縮応力は、鋳片内部の引張応力とバランスする。仮に、鋳片断面(長さ方向と直交する断面)において急速加熱により加熱される領域(図2の領域A1、A2)が厚過ぎると、それとバランスするための引張応力が生じる領域(図2の領域B)が相対的に小さくなり過ぎることから、急速加熱による圧縮塑性変形によって、むしろ、鋳片中心に大きな引張応力が生じ易くなる。すなわち、加熱炉に装入する前から鋳片の中心に大きな引張応力が生じてしまい、鋳片の割れがむしろ生じ易くなる。例えば、本発明者が確認した限りでは、鋳片の表面から鋳片厚みの10%を急速加熱した場合は、鋳片内部には降伏応力の25%の引張応力が生じ、鋳片厚みの17%を急速加熱した場合は、鋳片内部には降伏応力の50%の引張応力が生じる。この点、本開示の方法においては、急速加熱により、鋳片の表面から鋳片厚みの10%以内の領域が加熱されることが重要である。言い換えれば、本開示の方法においては、図2に示されるように、急速加熱される領域A1、A2の各々の厚みTHと鋳片の厚みTとの比TH/Tが0.1以下である。このように、鋳片のごく表層のみが急速加熱され、それよりも深部においては急速加熱による圧縮変形ができるだけ生じないようにすることで、結果として、鋳片の中心における引張応力が抑制される。急速加熱される領域を鋳片厚みの10%以内とするためには、例えば、後述するように、加熱時間を1分以内としたり、或いは、加熱手段として鋳片のごく表層のみを加熱可能な手段を使用したりすればよい。
2.2 Area that is rapidly heated in the cross section of the slab The compressive stress on the surface layer of the slab due to rapid heating is balanced with the tensile stress inside the slab. If the area heated by rapid heating (areas A1 and A2 in Figure 2) in the slab cross section (cross section perpendicular to the length direction) is too thick, the area where tensile stress is generated to balance it (areas A1 and A2 in Figure 2) is too thick. Since region B) becomes relatively too small, large tensile stress is more likely to be generated at the center of the slab due to compressive plastic deformation due to rapid heating. That is, a large tensile stress is generated at the center of the slab even before it is charged into the heating furnace, making the slab more likely to crack. For example, as far as the present inventor has confirmed, when 10% of the slab thickness is rapidly heated from the surface of the slab, a tensile stress of 25% of the yield stress is generated inside the slab, and 17% of the slab thickness is generated inside the slab. %, a tensile stress of 50% of the yield stress is generated inside the slab. In this regard, in the method of the present disclosure, it is important that the rapid heating heats a region within 10% of the thickness of the slab from the surface of the slab. In other words, in the method of the present disclosure, as shown in FIG. 2, the ratio T H /T of the thickness T H of each of rapidly heated regions A1 and A2 to the thickness T of the slab is 0.1 or less. It is. In this way, only the very surface layer of the slab is rapidly heated, and by minimizing compressive deformation due to rapid heating in deeper parts, the tensile stress at the center of the slab is suppressed. . In order to keep the area to be rapidly heated within 10% of the thickness of the slab, for example, as described later, the heating time must be within 1 minute, or the heating means can heat only the very surface layer of the slab. You can use any means.
2.3 急速加熱による昇温速度
急速加熱による昇温速度が小さ過ぎる場合、鋳片を所望の温度にまで昇温させるために長時間を要し、鋳片断面において急速加熱される領域が過度に厚くなり易い。その結果、上述の通り、鋳片中心に大きな引張応力が生じてしまい、鋳片が割れ易くなる。急速加熱による昇温速度が高速であるほど、鋳片のごく表層のみに大きな圧縮塑性変形を生じさせることができ、高い効果が確保され易くなる。この点、本開示の方法においては、急速加熱による昇温速度が150℃/min以上であることが重要である。昇温速度の上限は特に限定されるものではない。昇温速度は、150℃/min以上、155℃/min以上、160℃/min以上、165℃/min以上、又は、170℃/min以上であってもよく、600℃/min以下、550℃/min以下、500℃/min以下、又は、450℃/min以下であってもよい。
2.3 Temperature increase rate due to rapid heating If the temperature increase rate due to rapid heating is too low, it will take a long time to heat the slab to the desired temperature, and the rapidly heated area of the slab cross section will be excessively heated. It tends to become thick. As a result, as described above, a large tensile stress is generated at the center of the slab, making the slab susceptible to cracking. The faster the temperature increase rate due to rapid heating, the greater compressive plastic deformation can be caused only in the very surface layer of the slab, and the higher the effect is likely to be ensured. In this regard, in the method of the present disclosure, it is important that the temperature increase rate by rapid heating is 150° C./min or more. The upper limit of the temperature increase rate is not particularly limited. The temperature increase rate may be 150°C/min or more, 155°C/min or more, 160°C/min or more, 165°C/min or more, or 170°C/min or more, and 600°C/min or less, 550°C /min or less, 500°C/min or less, or 450°C/min or less.
2.4 急速加熱による温度上昇量
急速加熱による温度上昇量が小さ過ぎると、上述した圧縮塑性変形を生じさせることができず、十分な効果が得られなくなる。急速加熱による温度上昇量が大きいほど、鋳片のごく表層において大きな圧縮塑性変形を生じさせることができ、高い効果が確保され易くなる。この点、本開示の方法においては、急速加熱により、鋳片の表面から鋳片厚みの10%以内の領域が、150℃/min以上の昇温速度、且つ、150℃以上の温度上昇量にて加熱されることが重要である。すなわち、鋳片の表面から鋳片厚みの10%以内の領域において、急速加熱前後の温度差が150℃以上となる。温度上昇量は、150℃以上、155℃以上、160℃以上、165℃以上又は170℃以上であってもよく、600℃以下、550℃以下、500℃以下、450℃以下、400℃以下、350℃以下又は300℃以下であってもよい。
2.4 Amount of Temperature Increase Due to Rapid Heating If the amount of temperature increase due to rapid heating is too small, the above-mentioned compressive plastic deformation cannot be produced, and sufficient effects cannot be obtained. The larger the amount of temperature rise due to rapid heating, the more compressive plastic deformation can be caused in the very surface layer of the slab, making it easier to ensure high effects. In this regard, in the method of the present disclosure, by rapid heating, an area within 10% of the thickness of the slab from the surface of the slab reaches a temperature increase rate of 150°C/min or more and a temperature increase amount of 150°C or more. It is important that the material is heated. That is, in a region within 10% of the thickness of the slab from the surface of the slab, the temperature difference before and after rapid heating is 150° C. or more. The temperature increase amount may be 150°C or higher, 155°C or higher, 160°C or higher, 165°C or higher, or 170°C or higher, 600°C or lower, 550°C or lower, 500°C or lower, 450°C or lower, 400°C or lower, The temperature may be 350°C or lower or 300°C or lower.
2.5 急速加熱による加熱温度
加熱炉での加熱過程における鋳片割れを抑制する観点のみからは、上記の加熱領域、昇温速度及び温度上昇量が満たされる限り、急速加熱による加熱温度に特に制限はない。ただし、加熱温度がAe1点以上となると、急速加熱された部分が変態し易く、鋳片の機械特性に過度のバラつきが生じる虞がある。この点、本開示の方法においては、急速加熱により、鋳片の表面から鋳片厚みの10%以内の領域が、150℃/min以上の昇温速度、且つ、150℃以上の温度上昇量にて、Ae1点未満の温度まで加熱されることが重要である。急速加熱による加熱温度は、Ae1点未満の温度であり、700℃以下、680℃以下又は650℃以下の温度であってもよい。
2.5 Heating temperature by rapid heating From the perspective of suppressing slab cracking during the heating process in a heating furnace, there are no particular restrictions on the heating temperature by rapid heating as long as the above heating range, heating rate, and amount of temperature rise are met. There isn't. However, if the heating temperature is Ae 1 or higher, the rapidly heated portion is likely to undergo transformation, and there is a risk that the mechanical properties of the slab will vary excessively. In this regard, in the method of the present disclosure, by rapid heating, an area within 10% of the thickness of the slab from the surface of the slab reaches a temperature increase rate of 150°C/min or more and a temperature increase amount of 150°C or more. Therefore, it is important that the material be heated to a temperature below the Ae1 point. The heating temperature by rapid heating is a temperature below the Ae 1 point, and may be a temperature of 700°C or lower, 680°C or lower, or 650°C or lower.
尚、任意の組成を有する鋼のAe1点を特定する方法は公知である。例えば、K.W. Andrews: JISI, vol. 203, 1965, p.721に記載された以下の式に基づいて、Ae1点が特定され得る。 Note that a method for specifying the Ae1 point of steel having an arbitrary composition is known. For example, the Ae1 point can be specified based on the following formula described in K.W. Andrews: JISI, vol. 203, 1965, p.721.
Ae1(℃)=727-10.7[Mn]-16.9[Ni]+29.1[Si]+16.9[Cr]+6.38[W]+290[As]
(ここで、[Mn]、[Ni]、[Si]、[Cr]、[W]、[As]は、鋳片における各々の元素の含有量(質量%)である。)
Ae1 (℃) = 727-10.7 [Mn] - 16.9 [Ni] + 29.1 [Si] + 16.9 [Cr] + 6.38 [W] + 290 [As]
(Here, [Mn], [Ni], [Si], [Cr], [W], and [As] are the content (mass%) of each element in the slab.)
2.6 急速加熱による加熱時間
急速加熱による加熱時間は、鋳片の表面から鋳片厚みの10%以内の領域が、上記条件にて急速加熱される限り、特に限定されるものではない。本発明者が確認した限りでは、加熱時間が長過ぎると、急速加熱される領域を鋳片の表面から鋳片厚みの10%以内とすることが難しくなる。この点、加熱時間は、例えば、1分以下であることが好ましい。加熱時間の下限は特に限定されず、0秒超、1秒以上、3秒以上、5秒以上又は10秒以上であってもよい。
2.6 Heating time by rapid heating The heating time by rapid heating is not particularly limited as long as a region within 10% of the thickness of the slab from the surface of the slab is rapidly heated under the above conditions. As far as the present inventor has confirmed, if the heating time is too long, it becomes difficult to keep the rapidly heated region within 10% of the thickness of the slab from the surface of the slab. In this regard, the heating time is preferably, for example, 1 minute or less. The lower limit of the heating time is not particularly limited, and may be more than 0 seconds, 1 second or more, 3 seconds or more, 5 seconds or more, or 10 seconds or more.
2.7 急速加熱手段
急速加熱の手段は、上記の加熱条件が実現されるものであればよい。本開示の方法においては、例えば、高周波誘導加熱、レーザー加熱、及び、プラズマ加熱のうちの少なくとも1つによって急速加熱が行われることが好ましい。尚、本開示の方法において、鋳片の全長を急速加熱する場合、鋳片の全長を同時に急速加熱する必要はなく、例えば、鋳片搬送路の上方及び/又は下方にバーヒータを設置しておき、バーヒータ出力や鋳片の搬送速度を調整しつつ、バーヒータを鋳片の長手方向へと相対的に移動させることで、鋳片の全長が急速加熱されるようにしてもよい。或いは、鋳片の長さと同程度以上の長さを有するバーヒータを、鋳片の幅方向へと相対的に移動させること等によって、鋳片表面の全長を急速加熱してもよい。
2.7 Rapid heating means Any rapid heating means may be used as long as the above heating conditions are achieved. In the method of the present disclosure, rapid heating is preferably performed by at least one of high-frequency induction heating, laser heating, and plasma heating, for example. In addition, in the method of the present disclosure, when rapidly heating the entire length of the slab, it is not necessary to rapidly heat the entire length of the slab at the same time. For example, bar heaters may be installed above and/or below the slab conveying path. Alternatively, the entire length of the slab may be rapidly heated by moving the bar heater relatively in the longitudinal direction of the slab while adjusting the bar heater output and conveying speed of the slab. Alternatively, the entire length of the surface of the slab may be rapidly heated by, for example, moving a bar heater having a length comparable to or longer than the length of the slab relatively in the width direction of the slab.
3.加熱炉への装入及び加熱炉での加熱
上述の通り、急速加熱された鋳片は、上記の圧縮塑性変形を有した状態で、加熱炉へ挿入される。加熱炉は一般的な加熱炉であればよい。鋳片を加熱炉へと挿入する方法も一般的な方法によればよい。加熱炉に装入された鋳片は、加熱炉において所定の温度にまで加熱される。例えば、加熱炉において、鋳片は、熱間圧延に適した温度にまで加熱されてもよい。加熱炉における加熱温度は、例えば、1000℃以上1300℃以下であってもよい。加熱炉における加熱時間は、例えば、30分以上240分以下であってもよい。
3. Charge to Heating Furnace and Heating in Heating Furnace As described above, the rapidly heated slab is inserted into the heating furnace in a state having the above-mentioned compressive plastic deformation. The heating furnace may be any general heating furnace. The method for inserting the slab into the heating furnace may also be a general method. The slab charged into the heating furnace is heated to a predetermined temperature in the heating furnace. For example, the slab may be heated in a heating furnace to a temperature suitable for hot rolling. The heating temperature in the heating furnace may be, for example, 1000°C or more and 1300°C or less. The heating time in the heating furnace may be, for example, 30 minutes or more and 240 minutes or less.
本開示の方法においては、上述の通り、急速加熱によって鋳片の表層に予め圧縮塑性変形が付与されており、加熱炉での加熱過程で鋳片の表層が加熱されて熱膨張したとしても、鋳片の中心に生じる引張応力が大きくなり難い。その結果、加熱過程における鋳片割れを抑制することができる。よって、本開示の方法においては、加熱炉での加熱過程において、従来のスローヒートのように鋳片の加熱温度を細かく制御する必要がなく、加熱炉における加熱条件の自由度が高い。上述したようにC、Si及びMnを多量に含む鋳片は、本来、加熱炉での加熱過程において割れ易いところ、本開示の方法によれば、例えば、加熱炉における平均昇温速度が10℃/min以上と高速であったとしても、鋳片割れが発生し難い。加熱炉における平均昇温速度は、13℃/min以上又は16℃/min以上であってもよい。 In the method of the present disclosure, as described above, compressive plastic deformation is applied to the surface layer of the slab in advance by rapid heating, and even if the surface layer of the slab is heated and thermally expanded during the heating process in the heating furnace, Tensile stress generated at the center of the slab is difficult to increase. As a result, cracking of the slab during the heating process can be suppressed. Therefore, in the method of the present disclosure, in the heating process in the heating furnace, there is no need to finely control the heating temperature of the slab unlike in the conventional slow heat, and there is a high degree of freedom in the heating conditions in the heating furnace. As mentioned above, slabs containing large amounts of C, Si, and Mn are naturally prone to cracking during the heating process in a heating furnace, but according to the method of the present disclosure, for example, the average temperature increase rate in the heating furnace is 10°C. Even if the speed is higher than /min, cracking of slabs is difficult to occur. The average temperature increase rate in the heating furnace may be 13° C./min or more or 16° C./min or more.
4.補足
尚、急速加熱で生じた圧縮側の応力及び塑性ひずみは、その後の放冷過程で生じる引張側の応力及び塑性ひずみよりも大きいため、仮に急速加熱後に鋳片が放冷されたとしても、本開示の方法による効果を得ることができる。すなわち、本開示の方法においては、急速加熱後、且つ、加熱炉への装入前において、鋳片の温度が低下してもよい。ただし、より高い効果が確保される観点から、本開示の方法においては、鋳片を急速加熱後、加熱炉に装入するまでの鋳片の温度変化量が、300℃以内、250℃以内、200℃以内又は150℃以内であることが好ましい。また、急速加熱後、且つ、加熱炉への装入前における鋳片の冷却速度(降温速度)は、放冷速度以下であることが好ましく、例えば、150℃/min未満、100℃/min以下、又は、50℃/min以下であることが好ましい。
4. Note: The stress and plastic strain on the compression side caused by rapid heating are larger than the stress and plastic strain on the tension side that occur during the subsequent cooling process, so even if the slab is allowed to cool after rapid heating, The effects of the method of the present disclosure can be obtained. That is, in the method of the present disclosure, the temperature of the slab may be lowered after rapid heating and before charging into the heating furnace. However, from the viewpoint of ensuring a higher effect, in the method of the present disclosure, the amount of temperature change of the slab after rapidly heating the slab until it is charged into the heating furnace is within 300°C, within 250°C, The temperature is preferably within 200°C or within 150°C. Further, the cooling rate (temperature reduction rate) of the slab after rapid heating and before charging into the heating furnace is preferably equal to or lower than the cooling rate, for example, less than 150°C/min, 100°C/min or less. , or preferably 50° C./min or less.
以上の通り、本開示の方法によれば、加熱炉での加熱過程において、鋳片に割れが生じ難い。また、本開示の方法においては、従来技術のように鋳片の加熱速度を細かく制御する必要がない。また、加熱炉における昇温速度を高速とした場合でも、鋳片の割れが生じ難い。 As described above, according to the method of the present disclosure, cracks are unlikely to occur in the slab during the heating process in the heating furnace. Furthermore, in the method of the present disclosure, there is no need to finely control the heating rate of the slab as in the prior art. Moreover, even when the heating rate in the heating furnace is set at a high rate, cracks in the slab are less likely to occur.
以下に本発明に係る実施例を示すが、本発明はこの一条件例に限定されるものではない。本発明においては、その要旨を逸脱せず、その目的を達する限りにおいて、種々の条件が採用され得る。 Examples according to the present invention are shown below, but the present invention is not limited to this example of one condition. In the present invention, various conditions may be adopted as long as the purpose is achieved without departing from the gist thereof.
1.熱応力解析
連続鋳造後の鋳片に対して急速加熱を実施することなく150℃で加熱炉に装入したことを想定して熱応力解析を行い、これを評価基準とした。また、連続鋳造後の鋳片に対して加熱炉への装入前に急速加熱を実施した後に150℃で加熱炉に装入したことを想定して同様に熱応力解析を行った。急速加熱の条件を種々変化させて、鋳片中心の引張応力が評価基準に対して20%以上低下したものを「●」、低下しなかったものを「×」と判定した。図3に、鋳片表面の加熱時間と加熱前後の温度差とを各々変化させた場合の熱応力解析結果を示す。図3に示されるように、引張応力低減効果を発現させるためには、鋳片のごく表層(厚みの10%程度まで、例えば、加熱時間を1分以内とすることで達成)のみを急速加熱して、当該表層の温度を加熱開始時の温度から150℃以上上昇させることが有効であるといえる。
1. Thermal Stress Analysis A thermal stress analysis was performed assuming that the slab after continuous casting was charged into a heating furnace at 150° C. without being rapidly heated, and this was used as the evaluation standard. Further, thermal stress analysis was similarly performed on the assumption that the slab after continuous casting was rapidly heated before being charged into the heating furnace and then charged into the heating furnace at 150°C. The rapid heating conditions were variously changed, and those in which the tensile stress at the center of the slab decreased by 20% or more with respect to the evaluation criteria were evaluated as "●", and those in which the tensile stress did not decrease were evaluated as "×". FIG. 3 shows the results of thermal stress analysis when the heating time of the slab surface and the temperature difference before and after heating were varied. As shown in Figure 3, in order to exhibit the tensile stress reduction effect, only the very surface layer of the slab (up to about 10% of the thickness, achieved by heating for less than 1 minute) must be rapidly heated. Therefore, it can be said that it is effective to raise the temperature of the surface layer by 150° C. or more from the temperature at the start of heating.
図4に、鋳片の幅方向に沿った表面の一部を、長手方向の全長に亘って急速に加熱した場合における熱応力解析結果の一例を示す(長手・幅方向対称モデルで計算)。図4(a)が鋳片の温度、(b)が鋳片に生じる応力、(c)が鋳片に生じる塑性ひずみの状態を示している。図4(a)~(c)に示されるように、急速加熱部には圧縮応力とこれに伴う圧縮側の塑性ひずみが生じる。これは加熱された表層が温度上昇に伴い熱膨張するものの、低温の非加熱領域に拘束されることに起因するものと考えられる。 FIG. 4 shows an example of the thermal stress analysis results when a part of the surface along the width direction of the slab is rapidly heated over the entire length in the longitudinal direction (calculated using a symmetric model in the longitudinal and width directions). FIG. 4(a) shows the temperature of the slab, FIG. 4(b) shows the stress generated in the slab, and FIG. 4(c) shows the state of plastic strain generated in the slab. As shown in FIGS. 4(a) to 4(c), compressive stress and accompanying plastic strain on the compression side occur in the rapidly heated portion. This is thought to be due to the fact that although the heated surface layer thermally expands as the temperature rises, it is constrained to a low-temperature non-heated region.
図5に、図4に示される条件にて急速加熱を行った後、鋳片を放冷して温度を低下させた場合における熱応力解析結果を示す。図5(a)が鋳片の温度、(b)が鋳片に生じる応力、(c)が鋳片に生じる塑性歪みの状態を示している。図5(c)に示されるように、急速加熱によって生じた圧縮の塑性ひずみは、鋳片の温度が低下しても残ることが分かる。 FIG. 5 shows the results of thermal stress analysis when the slab is cooled to lower the temperature after rapid heating under the conditions shown in FIG. 4. FIG. 5(a) shows the temperature of the slab, FIG. 5(b) shows the stress generated in the slab, and FIG. 5(c) shows the state of plastic strain generated in the slab. As shown in FIG. 5(c), it can be seen that the compressive plastic strain caused by rapid heating remains even when the temperature of the slab decreases.
通常、加熱炉内では鋳片表層から加熱され、鋳片表層が熱膨張することに伴い鋳片内部に引張応力が生じ、これにより鋳片割れが生じる。これに対し、上記の熱応力解析結果から、加熱炉に装入する前に鋳片のごく表層に対して急速加熱を行い、鋳片のごく表層に圧縮塑性変形を付与しておくことにより、加熱炉での加熱過程において鋳片表面が熱膨張して伸びが生じたとしても、鋳片中心に生じる引張応力を低く抑えることができるものといえる。 Usually, in a heating furnace, the surface layer of the slab is heated, and as the surface layer of the slab thermally expands, tensile stress is generated inside the slab, which causes cracking of the slab. On the other hand, from the above thermal stress analysis results, we found that by rapidly heating the very surface layer of the slab before charging it into the heating furnace and applying compressive plastic deformation to the very surface layer of the slab, Even if the surface of the slab undergoes thermal expansion and elongation during the heating process in the heating furnace, it can be said that the tensile stress generated at the center of the slab can be kept low.
2.実機試験
熱応力解析による結果が妥当であることを実機試験で確かめた。まず、所定の成分からなる溶鋼を連続鋳造しスラブを製造した。下記表1に連続鋳造により製造したスラブの化学組成を示す。連続鋳造は、鋳造速度0.7~1.5m/minで、厚み240~280mm、幅1100mmのスラブ鋳造用の鋳型を用いて行った。その後、スラブを所定の長さに切断し、冷却を行った。
2. Actual Machine Test The validity of the thermal stress analysis results was confirmed through an actual machine test. First, molten steel made of predetermined components was continuously cast to produce a slab. Table 1 below shows the chemical composition of the slab manufactured by continuous casting. Continuous casting was performed at a casting speed of 0.7 to 1.5 m/min using a slab casting mold with a thickness of 240 to 280 mm and a width of 1100 mm. Thereafter, the slab was cut into predetermined lengths and cooled.
その後、下記表2に示される条件にてスラブの幅方向に沿った両面の一部又は全部を急速加熱した。ここで、急速加熱には高周波誘導加熱装置を用い、周波数を1500Hzとし、出力を調整することにより表2に示される昇温速度となるようにした。また、急速加熱開始前と終了後のスラブ温度をサーモビューアで測温するとともに、測定された加熱温度と、金属の固有値(固有抵抗、比透磁率)と、周波数により算出される浸透深さとを用いて、3次元の伝熱解析より、加熱深さを算出するとともに、鋳片厚みの10%以内の領域の急速加熱開始時点の温度、及び、急速加熱終了時点の温度を算出した。 Thereafter, part or all of both sides of the slab along the width direction were rapidly heated under the conditions shown in Table 2 below. Here, a high frequency induction heating device was used for rapid heating, the frequency was set to 1500 Hz, and the temperature increase rate shown in Table 2 was achieved by adjusting the output. In addition, the temperature of the slab before and after rapid heating is measured using a thermoviewer, and the penetration depth calculated from the measured heating temperature, the specific values of the metal (specific resistance, relative magnetic permeability), and the frequency. Using the three-dimensional heat transfer analysis, the heating depth was calculated, and the temperature at the start of rapid heating and the temperature at the end of rapid heating in an area within 10% of the thickness of the slab was calculated.
急速加熱後、表2に示される温度となったスラブを、加熱炉に装入して、表2に示される平均昇温速度にて1210~1250℃まで加熱し、その後、熱間圧延における粗圧延までを実施して鋼板を得た。鋼板を冷却後、割れや筋状の異常がないか、目視で確認した。結果を下記表2に示す。 After rapid heating, the slab that reached the temperature shown in Table 2 was charged into a heating furnace and heated to 1210 to 1250°C at the average temperature increase rate shown in Table 2, and then roughened in hot rolling. A steel plate was obtained by performing steps up to rolling. After cooling the steel plate, it was visually checked for cracks or streak-like abnormalities. The results are shown in Table 2 below.
表2において、「T」は、スラブの厚みであり、図2に示されるTと対応する。
「WH」は、急速加熱領域の幅であり、図2に示されるWHと対応する。
「W」は、スラブの全幅であり、図2に示されるWと対応する。
尚、実施例8については、スラブの全周を急速加熱した例であり、スラブの幅方向に沿った表面及び厚み方向に沿った表面の双方を全面急速加熱したことで、WH/Wが1/1となった例である。実施例1~7については、スラブの幅方向に沿った表面のみ急速加熱を行い、スラブの厚み方向に沿った表面については急速加熱を行わなかった。
「昇温速度」は、スラブの厚みの10%以内の領域における急速加熱時の昇温速度を意味する。
「急速加熱開始温度」は、スラブ厚みの10%以内の領域における急速加熱開始時点の温度を意味する。
「急速加熱終了温度」は、スラブ厚みの10%以内の領域における急速加熱終了直後の温度を意味する。
「温度上昇量」は、スラブ厚みの10%以内の領域における「急速加熱終了温度」と「急速加熱開始温度」との差である。
「加熱深さ」は、スラブ厚みTに占める急速加熱領域の厚みTHの割合((TH/T)×100)を意味し、「T」及び「TH」は、各々、図2のT及びTHと対応する。
「装入温度」は、加熱炉に装入された時点におけるスラブ表面の温度(急速加熱された場合は、急速加熱された部分のスラブ厚みの10%以内の領域の温度)を意味する。
「平均昇温速度」は、加熱炉にて設定された平均昇温速度をいう。
In Table 2, "T" is the thickness of the slab and corresponds to T shown in FIG.
“W H ” is the width of the rapid heating region and corresponds to W H shown in FIG.
"W" is the total width of the slab and corresponds to W shown in FIG.
In addition, Example 8 is an example in which the entire circumference of the slab was rapidly heated, and by rapidly heating both the surface along the width direction and the surface along the thickness direction of the slab, W H /W was increased. This is an example where the ratio was 1/1. In Examples 1 to 7, rapid heating was performed only on the surface along the width direction of the slab, and no rapid heating was performed on the surface along the thickness direction of the slab.
"Temperature increase rate" means the temperature increase rate during rapid heating in a region within 10% of the thickness of the slab.
"Rapid heating start temperature" means the temperature at the start of rapid heating in a region within 10% of the slab thickness.
"Rapid heating end temperature" means the temperature immediately after rapid heating ends in a region within 10% of the slab thickness.
The "temperature increase amount" is the difference between the "rapid heating end temperature" and the "rapid heating start temperature" in a region within 10% of the slab thickness.
“Heating depth” means the ratio of the thickness T H of the rapid heating region to the slab thickness T ((T H /T)×100), and “T” and “T H ” are each shown in FIG. Corresponds to T and T H.
"Charging temperature" means the temperature of the surface of the slab at the time it is charged into the heating furnace (in the case of rapid heating, the temperature of the area within 10% of the slab thickness of the rapidly heated portion).
"Average temperature increase rate" refers to the average temperature increase rate set in the heating furnace.
表2に示される結果から以下のことが分かる。 The following can be seen from the results shown in Table 2.
比較例1については、粗圧延後の鋼板に割れや異常が確認された。比較例1については、加熱炉に装入する前にスラブの急速加熱を行わなかったため、加熱炉における加熱の際、スラブ表層が熱膨張することに伴いスラブ内部に引張応力が生じ、これが粗圧延後の割れや異常に繋がったものと考えられる。 Regarding Comparative Example 1, cracks and abnormalities were observed in the steel plate after rough rolling. Regarding Comparative Example 1, since the slab was not rapidly heated before being charged into the heating furnace, tensile stress was generated inside the slab due to thermal expansion of the surface layer of the slab during heating in the heating furnace, which caused the rough rolling. This is thought to have led to later cracks and abnormalities.
比較例2についても、粗圧延後の鋼板に割れや異常が確認された。比較例2については、加熱炉に装入する前にスラブの加熱を行ったものの、その加熱速度が小さく、加熱時間が長時間となった結果、加熱深さがスラブ厚みの15%と深くなり過ぎ、鋳片表面から深い部分にまで圧縮塑性変形が生じて、これとバランスするように鋳片中心に大きな引張応力が生じたものと考えられ、これが粗圧延後の割れや異常に繋がったものと考えられる。 In Comparative Example 2, cracks and abnormalities were also observed in the steel plate after rough rolling. Regarding Comparative Example 2, although the slab was heated before being charged into the heating furnace, the heating rate was low and the heating time was long, resulting in a heating depth of 15% of the slab thickness. It is thought that compressive plastic deformation occurred deep from the surface of the slab, and to balance this, a large tensile stress was generated at the center of the slab, which led to cracks and abnormalities after rough rolling. it is conceivable that.
比較例3については、粗圧延後の鋼板に割れや異常は確認されなかったものの、鋼板の金属組織が所望のものとならず、所望の機械特性が確保できなかった。比較例3については、加熱炉に装入する前にスラブの急速加熱を行った際、スラブの表層の温度がAe1点を超えたことから、変態によりスラブの表層と内部とで金属組織にバラつきが生じるなどして、機械特性が低下したものと考えられる。 Regarding Comparative Example 3, although no cracks or abnormalities were observed in the steel plate after rough rolling, the metal structure of the steel plate was not as desired, and desired mechanical properties could not be secured. Regarding Comparative Example 3, when the slab was rapidly heated before being charged into the heating furnace, the temperature of the surface layer of the slab exceeded the Ae1 point, so there was variation in the metal structure between the surface layer and the inside of the slab due to transformation. It is thought that the mechanical properties deteriorated due to the occurrence of.
比較例4及び5については、粗圧延後の鋼板に割れや異常が確認された。比較例4及び5については、加熱炉に装入する前にスラブの加熱を行ったものの、その加熱速度が小さく、温度上昇量も小さかったため、スラブの表層に圧縮の塑性変形を十分に生じさせることができなかったものと考えられ、加熱炉での加熱過程においてスラブの中心に大きな引張応力が生じ、これが粗圧延後の割れや異常に繋がったものと考えられる。 Regarding Comparative Examples 4 and 5, cracks and abnormalities were observed in the steel sheets after rough rolling. Regarding Comparative Examples 4 and 5, although the slabs were heated before being charged into the heating furnace, the heating rate was low and the amount of temperature rise was also small, so that sufficient compressive plastic deformation was generated in the surface layer of the slabs. It is thought that this caused a large tensile stress to occur at the center of the slab during the heating process in the heating furnace, which led to cracks and abnormalities after rough rolling.
これに対し、実施例1~8については、いずれも、粗圧延後の鋼板に割れや異常は生じなかった。比較例1~5及び実施例1~8の結果から、以下の条件を満たす場合に、加熱炉での加熱過程において鋳片の割れを抑制でき、その後に圧延を施した場合でも割れや異常を抑制できるものといえる。 In contrast, in Examples 1 to 8, no cracks or abnormalities occurred in the steel sheets after rough rolling. From the results of Comparative Examples 1 to 5 and Examples 1 to 8, when the following conditions are met, cracks in the slab can be suppressed during the heating process in the heating furnace, and cracks and abnormalities can be suppressed even when rolling is performed afterwards. This can be said to be something that can be suppressed.
(1)鋳片が、質量%で、C:0.02~0.60%、Si:0.5~3.0%、Mn:1.0~3.0%、P:0.100%以下、S:0.010%以下、Al:0.005~1.000%、及び、N:0.0100%以下を含有する。
(2)鋳片の表面の少なくとも一部が急速加熱され、当該急速加熱により、鋳片の表面から鋳片厚みの10%以内の領域が、150℃/min以上の昇温速度、且つ、150℃以上の温度上昇量で、Ae1点未満の温度まで加熱される。
(3)急速加熱の後、鋳片が加熱炉に装入される。
(1) The slab is mass%: C: 0.02 to 0.60%, Si: 0.5 to 3.0%, Mn: 1.0 to 3.0%, P: 0.100% Below, S: 0.010% or less, Al: 0.005 to 1.000%, and N: 0.0100% or less are contained.
(2) At least a part of the surface of the slab is rapidly heated, and due to the rapid heating, an area within 10% of the slab thickness from the surface of the slab is heated at a rate of 150°C/min or more, and With a temperature increase of ℃ or more, it is heated to a temperature below 1 point of Ae.
(3) After rapid heating, the slab is charged into a heating furnace.
Claims (4)
前記鋳片が、質量%で、C:0.02~0.60%、Si:0.5~3.0%、Mn:1.0~3.0%、P:0.100%以下、S:0.010%以下、Al:0.005~1.000%、及び、N:0.0100%以下を含有し、
前記鋳片の表面の少なくとも一部が急速加熱され、
前記急速加熱により、前記鋳片の表面から鋳片厚みの10%以内の領域が、150℃/min以上の昇温速度、且つ、150℃以上の温度上昇量で、Ae1点未満の温度まで加熱され、
前記急速加熱の後、前記鋳片が前記加熱炉に装入される、
連続鋳造鋳片の加熱方法。 A method of heating a slab cast by a continuous casting method before charging it into a heating furnace, the method comprising:
The slab, in mass %, C: 0.02 to 0.60%, Si: 0.5 to 3.0%, Mn: 1.0 to 3.0%, P: 0.100% or less, Contains S: 0.010% or less, Al: 0.005 to 1.000%, and N: 0.0100% or less,
At least a portion of the surface of the slab is rapidly heated,
By the rapid heating, a region within 10% of the thickness of the slab from the surface of the slab is heated to a temperature below Ae 1 point at a temperature increase rate of 150 ° C / min or more and a temperature increase of 150 ° C or more. is,
After the rapid heating, the slab is charged into the heating furnace.
Method of heating continuously cast slabs.
請求項1に記載の方法。 At least a portion of the surface along the width direction of the slab is rapidly heated;
The method according to claim 1.
請求項1に記載の方法。 At least a portion of each of both sides along the width direction of the slab is rapidly heated.
The method according to claim 1.
請求項1~3のいずれか1項に記載の方法。 A part of the surface along the width direction of the slab is rapidly heated, and the width W H of the rapidly heated surface is 1/8 or more and 3/4 or less of the total width W of the slab.
The method according to any one of claims 1 to 3.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2022070986A JP2023160552A (en) | 2022-04-22 | 2022-04-22 | Method for heating continuously cast slab |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2022070986A JP2023160552A (en) | 2022-04-22 | 2022-04-22 | Method for heating continuously cast slab |
Publications (1)
Publication Number | Publication Date |
---|---|
JP2023160552A true JP2023160552A (en) | 2023-11-02 |
Family
ID=88516080
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2022070986A Pending JP2023160552A (en) | 2022-04-22 | 2022-04-22 | Method for heating continuously cast slab |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2023160552A (en) |
-
2022
- 2022-04-22 JP JP2022070986A patent/JP2023160552A/en active Pending
Similar Documents
Publication | Publication Date | Title |
---|---|---|
RU2588755C2 (en) | Steel strip with low ratio of yield strength to ultimate strength and high impact strength and method for production thereof | |
US20190338402A1 (en) | Method for manufacturing railway vehicle wheel | |
JP5387720B2 (en) | Hot-pressed steel plate member, hot-pressed steel plate member, and method for producing them | |
JP5900303B2 (en) | High-strength steel sheet for sour-resistant pipes with excellent material uniformity in the steel sheet and its manufacturing method | |
EP3042976A1 (en) | Steel sheet for thick-walled high-strength line pipe having exceptional souring resistance, crush resistance properties, and low-temperature ductility, and line pipe | |
JP5333700B1 (en) | Low alloy oil well pipe steel with excellent resistance to sulfide stress cracking and method for producing low alloy oil well pipe steel | |
KR20180059915A (en) | Hydrogen organic cracking resistance pressure vessel steel plate and manufacturing method thereof | |
JP4254663B2 (en) | High strength thin steel sheet and method for producing the same | |
JP5440203B2 (en) | Manufacturing method of high carbon hot rolled steel sheet | |
JP5070947B2 (en) | Hardened steel plate member, hardened steel plate and manufacturing method thereof | |
JP2009242820A (en) | Steel, steel for die and die using the same | |
JP6065121B2 (en) | High carbon hot rolled steel sheet and manufacturing method thereof | |
JP6065120B2 (en) | High carbon hot rolled steel sheet and manufacturing method thereof | |
JP4984933B2 (en) | Hot rolled steel sheet for tailored blanks and tailored blanks | |
KR20140111002A (en) | High carbon hot-rolled steel sheet with excellent hardenability and minimal in-plane anisotropy, and method for producing same | |
JP5727400B2 (en) | Steel for plastic mold and method for producing the same | |
JP6417977B2 (en) | Steel plate blank | |
KR20170043662A (en) | Steel strip for electric-resistance-welded steel pipe or tube, electric-resistance-welded steel pipe or tube, and process for producing steel strip for electric-resistance-welded steel pipe or tube | |
JP6003837B2 (en) | Manufacturing method of high strength pressed parts | |
JP4867320B2 (en) | High strength steel member and manufacturing method thereof | |
JP2023160552A (en) | Method for heating continuously cast slab | |
JP5195802B2 (en) | Billet manufacturing method | |
JP5187151B2 (en) | Thick steel plate excellent in bending workability by linear heating and its manufacturing method | |
JP4876972B2 (en) | Thick steel plate for welded structure having excellent fatigue crack propagation characteristics in the thickness direction and method for producing the same | |
JP2015063737A (en) | High strength hot rolled steel sheet excellent in fatigue strength and production method thereof |