JP4922971B2 - Composite roll for hot rolling and manufacturing method thereof - Google Patents
Composite roll for hot rolling and manufacturing method thereof Download PDFInfo
- Publication number
- JP4922971B2 JP4922971B2 JP2008058409A JP2008058409A JP4922971B2 JP 4922971 B2 JP4922971 B2 JP 4922971B2 JP 2008058409 A JP2008058409 A JP 2008058409A JP 2008058409 A JP2008058409 A JP 2008058409A JP 4922971 B2 JP4922971 B2 JP 4922971B2
- Authority
- JP
- Japan
- Prior art keywords
- mass
- hot rolling
- less
- composite roll
- 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.)
- Active
Links
- 238000005098 hot rolling Methods 0.000 title claims description 82
- 239000002131 composite material Substances 0.000 title claims description 71
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- 229910052751 metal Inorganic materials 0.000 claims description 59
- 239000002184 metal Substances 0.000 claims description 59
- 239000010410 layer Substances 0.000 claims description 43
- 229910000831 Steel Inorganic materials 0.000 claims description 33
- 239000010959 steel Substances 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 32
- 239000011162 core material Substances 0.000 claims description 28
- 238000005096 rolling process Methods 0.000 claims description 27
- 238000012360 testing method Methods 0.000 claims description 27
- 238000001816 cooling Methods 0.000 claims description 25
- 238000010438 heat treatment Methods 0.000 claims description 23
- 230000003647 oxidation Effects 0.000 claims description 17
- 238000007254 oxidation reaction Methods 0.000 claims description 17
- 238000005496 tempering Methods 0.000 claims description 17
- 239000013078 crystal Substances 0.000 claims description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 238000003466 welding Methods 0.000 claims description 10
- 210000001787 dendrite Anatomy 0.000 claims description 7
- 229910052750 molybdenum Inorganic materials 0.000 claims description 7
- 230000035939 shock Effects 0.000 claims description 7
- 229910052721 tungsten Inorganic materials 0.000 claims description 7
- 229910002804 graphite Inorganic materials 0.000 claims description 6
- 239000010439 graphite Substances 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 5
- 238000003754 machining Methods 0.000 claims description 5
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 239000002344 surface layer Substances 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 238000005253 cladding Methods 0.000 claims description 2
- PTVDYARBVCBHSL-UHFFFAOYSA-N copper;hydrate Chemical compound O.[Cu] PTVDYARBVCBHSL-UHFFFAOYSA-N 0.000 claims 1
- 238000010606 normalization Methods 0.000 claims 1
- 230000000052 comparative effect Effects 0.000 description 26
- 230000000694 effects Effects 0.000 description 18
- 150000001247 metal acetylides Chemical group 0.000 description 13
- 239000010936 titanium Substances 0.000 description 11
- 239000011651 chromium Substances 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 239000000126 substance Substances 0.000 description 9
- 239000013067 intermediate product Substances 0.000 description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
- 239000010955 niobium Substances 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 238000009749 continuous casting Methods 0.000 description 7
- 230000005674 electromagnetic induction Effects 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- 238000010791 quenching Methods 0.000 description 6
- 230000000171 quenching effect Effects 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 5
- 238000002425 crystallisation Methods 0.000 description 5
- 230000008025 crystallization Effects 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 230000005496 eutectics Effects 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 238000013001 point bending Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 238000009750 centrifugal casting Methods 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000000879 optical micrograph Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 206010013786 Dry skin Diseases 0.000 description 1
- 229910001141 Ductile iron Inorganic materials 0.000 description 1
- 229910000997 High-speed steel Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910001037 White iron Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- -1 chromium carbides Chemical class 0.000 description 1
- GETQUXSKPMRGCK-UHFFFAOYSA-N chromium;methane Chemical compound C.C.C.[Cr].[Cr].[Cr].[Cr].[Cr].[Cr].[Cr] GETQUXSKPMRGCK-UHFFFAOYSA-N 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000002054 inoculum Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 102200082816 rs34868397 Human genes 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000009751 slip forming Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Description
本発明は、鋼材の圧延において、特に、棒鋼、線材、あるいは形鋼の熱間圧延において、圧延機群のなかで、特に圧延速度が遅い上流側の粗圧延機の使用に適した熱間圧延用複合ロール及びその製造方法に関する。 The present invention is a hot rolling suitable for the use of an upstream rough rolling machine having a slow rolling speed among rolling mills, particularly in the rolling of steel materials, particularly in the hot rolling of steel bars, wire rods or section steels. The present invention relates to a composite roll and a manufacturing method thereof.
従来、圧延用のロールとしては、主としてダクタイル鋳鉄製のロールが使用されてきた。しかし、近年、鋼材の圧延においては、寸法精度と形状精度が高い製品への要求が高まり、一方では、生産性の向上が望まれており、製品品質やその生産効率に直接影響する圧延用ロールに、摩耗並びに消耗が少ないことが強く要求されてきた。
そこで、例えば、特許文献１に開示されたいわゆるハイス系ロールが開発された。このハイス系ロールは、摩耗が極めて少ないことから、鋼板の圧延や、棒鋼、線材、あるいは形鋼の熱間圧延において、仕上げ及び中間圧延機群に広く適用されている。
例えば、鋼系材料からなる芯材の周囲に、質量％で、Ｃ：１．５〜２．４％、Ｖ：３．０〜６．０％、及びＣｒ、Ｍｏ、及びＷの少なくとも１種の元素を含有し、必要により接種材として、Ａｌ：０．０５〜０．２０％、及びＴｉ：０．０２〜０．１０％のいずれか１種又は２種の元素を添加し、残部Ｆｅ及び不可避的不純物からなる溶湯を溶着させて外層材を形成する連続鋳掛け鋳造法を用いて複合ロールとし、外層材の組織が３０〜１５０μｍの結晶粒径を有すると共に、その粒界に、共晶炭化物で囲まれた金属組織、あるいは上記結晶の基地組織内に、更に初晶炭化物が分散晶出した金属組織からなり、ショアー硬さを７５〜９０の範囲にして使用している。
また、特許文献２には、遠心鋳造法にて、前記した溶湯を外層材として溶着させた複合ロールが開示されている。
Conventionally, a roll made of ductile cast iron has been mainly used as a roll for rolling. However, in recent years, in the rolling of steel materials, there has been an increasing demand for products with high dimensional accuracy and shape accuracy. On the other hand, improvement in productivity is desired, and a roll for rolling that directly affects product quality and production efficiency. In addition, there has been a strong demand for less wear and wear.
Therefore, for example, a so-called high-speed roll disclosed in Patent Document 1 has been developed. Since this high-speed roll has very little wear, it is widely applied to finishing and intermediate rolling mills in rolling steel sheets and hot rolling steel bars, wire rods or section steels.
For example, around a core material made of a steel material, by mass%, C: 1.5 to 2.4%, V: 3.0 to 6.0%, and at least one of Cr, Mo, and W And, if necessary, as an inoculum, add one or two elements of Al: 0.05-0.20% and Ti: 0.02-0.10%, and the balance Fe And a composite roll using a continuous casting method in which a molten metal composed of inevitable impurities is deposited to form an outer layer material, and the outer layer structure has a crystal grain size of 30 to 150 μm, and a eutectic crystal at the grain boundary. It consists of a metal structure surrounded by carbides, or a metal structure in which primary crystal carbides are dispersed and crystallized in the matrix structure of the crystal, and is used with a Shore hardness in the range of 75-90.
Patent Document 2 discloses a composite roll in which the above-described molten metal is welded as an outer layer material by centrifugal casting.
しかしながら、前記したハイス系ロールの使用は、圧延速度の大きな仕上げ及び中間圧延機群での使用に限定されていた。なぜなら、このハイス系ロールを、圧延速度が小さな粗圧延機群に使用する場合、ロールが高温となった鋼材と比較的長い時間接触することにより、熱伝導によってロールの内部まで温度が上昇し、また水冷による冷却がロールの回転ごとに繰り返されることにより、ロールの表面から深いき裂が生じるからである。このため、このき裂が起点となって、ロールの表面が損傷し、ひいては表面の一部が剥離するため、全く使用に耐えるものではなかった。 However, the use of the above-described high-speed roll has been limited to finishing with a high rolling speed and use in an intermediate rolling mill group. Because, when this high-speed roll is used in a rough rolling mill group with a small rolling speed, the temperature rises to the inside of the roll by heat conduction by contacting the steel material with a relatively high temperature for a long time, Moreover, it is because a deep crack arises from the surface of a roll by repeating cooling by water cooling for every rotation of a roll. For this reason, since this crack became the starting point, the surface of the roll was damaged, and eventually a part of the surface was peeled off.
本発明はかかる事情に鑑みてなされたもので、熱間粗圧延において、特に熱疲労き裂に対して、損傷が小さく、かつこの種のロールが有する耐摩耗性を適度に有して消耗が少ない熱間圧延用複合ロール及びその製造方法を提供することを目的とする。 The present invention has been made in view of such circumstances, and in hot rough rolling, particularly against thermal fatigue cracks, the damage is small, and the wear resistance of this type of roll is moderately worn and consumed. It aims at providing few composite rolls for hot rolling, and its manufacturing method.
前記目的に沿う第１の発明に係る熱間圧延用複合ロールは、金属製の中空式冷却型の上部内側面に冷却緩衝材を有する組合せモールドの内部に、鋼を素材とする中実又は中空の芯材を同心垂直に挿入し、該芯材の外周の環状空隙部に溶湯を注入して該芯材を連続的に降下させ、該芯材の外表面に前記溶湯を溶着させながら冷却により凝固させ、該芯材の外周に肉盛層を形成した後、熱処理と機械加工を行って製造される熱間圧延用複合ロールであって、
前記溶湯は、Ｃ：１．０質量％以上２．０質量％以下、Ｓｉ：０．２質量％以上２．０質量％以下、Ｍｎ：０．２質量％以上２．０質量％以下、Ｖ：４．０質量％以上８．０質量％以下、Ｃｒ：２．０質量％以上５．０質量％以下、Ｍｏ及びＷのいずれか１種又は２種を２．０質量％以上８．０質量％以下、及びＴｉ：０．０５質量％以上０．３０質量％以下含有し、残部がＦｅ及び不可避的不純物元素からなり、
かつ、前記肉盛層に晶出したＭ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物の占有率を３．０面積％以下、及び前記金属炭化物のサイズと前記肉盛層の二次デンドライト組織の結晶粒サイズを、それぞれ５０μｍ以下に微細化した。
The composite roll for hot rolling according to the first invention that meets the above object is a solid or hollow steel made of steel in a combination mold having a cooling buffer material on the inner inner surface of a hollow cooling mold made of metal. The core material is inserted concentrically and vertically, and molten metal is poured into the annular space on the outer periphery of the core material, the core material is continuously lowered, and cooling is performed while the molten metal is welded to the outer surface of the core material. It is a composite roll for hot rolling manufactured by solidifying and forming a built-up layer on the outer periphery of the core, and then performing heat treatment and machining,
The molten metal is C: 1.0 mass% or more and 2.0 mass% or less, Si: 0.2 mass% or more and 2.0 mass% or less, Mn: 0.2 mass% or more and 2.0 mass% or less, V : 4.0% by mass or more and 8.0% by mass or less, Cr: 2.0% by mass or more and 5.0% by mass or less, and any one or two of Mo and W are 2.0% by mass or more and 8.0% by mass. Less than mass%, and Ti: 0.05 mass% or more and 0.30 mass% or less, and the balance consists of Fe and inevitable impurity elements,
And, M 2 C, which crystallized on the cladding layer, M 6 C, and M 7 C 3 of the occupancy of the metal carbide consisting of either one or two or more 3.0 area% or less, and the metal The size of the carbide and the crystal grain size of the secondary dendrite structure of the overlay layer were each refined to 50 μm or less.
第１の発明に係る熱間圧延用複合ロールにおいて、前記溶湯は、更に、Ｎｉ：１．０質量％以上５．０質量％以下、Ｃｏ：１．０質量％以上５．０質量％以下、及びＮｂ：０．０２質量％以上０．２０質量％以下のいずれか１種又は２種以上を含有することが好ましい。 In the composite roll for hot rolling according to the first invention, the molten metal further includes Ni: 1.0% by mass to 5.0% by mass, Co: 1.0% by mass to 5.0% by mass, And Nb: It is preferable to contain any 1 type or 2 types or more of 0.02 mass% or more and 0.20 mass% or less.
第１の発明に係る熱間圧延用複合ロールにおいて、前記熱処理により、前記肉盛層の硬さを、ショアー硬さ：４５以上７５以下、かつ破壊靱性値ＫＩＣ又は疲労破壊靱性値ＫＩＣｆ：３０ＭＰａ・ｍ０．５以上とすることが好ましい。 In the composite roll for hot rolling according to the first aspect of the present invention, by the heat treatment, the hardness of the build-up layer is Shore hardness: 45 to 75, and the fracture toughness value K IC or the fatigue fracture toughness value K ICf : It is preferable to be 30 MPa · m 0.5 or more.
第１の発明に係る熱間圧延用複合ロールにおいて、大気雰囲気のもと９００℃で２４時間保持した場合、酸化による前記肉盛層の重量増加量が、１時間あたり１６ｇ／ｍ２以下の耐高温酸化特性を有することが好ましい。 When the composite roll for hot rolling according to the first invention is held at 900 ° C. for 24 hours in an air atmosphere, the increase in the weight of the overlay layer due to oxidation is 16 g / m 2 or less per hour. It preferably has high temperature oxidation properties.
第１の発明に係る熱間圧延用複合ロールにおいて、大気雰囲気のもと８００℃で１５分間の熱間摩耗試験を行った場合、前記肉盛層の熱間摩耗量が８ｍｇ以下である耐熱間摩耗特性を有することが好ましい。 In the composite roll for hot rolling according to the first invention, when a hot wear test is performed at 800 ° C. for 15 minutes in an air atmosphere, the hot wear amount of the overlay layer is 8 mg or less. It preferably has wear characteristics.
第１の発明に係る熱間圧延用複合ロールにおいて、８００℃の温度からの急冷に対し、前記肉盛層の表層部にき裂が発生しない耐熱衝撃特性を有することが好ましい。 The composite roll for hot rolling according to the first aspect of the invention preferably has a thermal shock property that does not generate cracks in the surface layer portion of the build-up layer against rapid cooling from a temperature of 800 ° C.
第１の発明に係る熱間圧延用複合ロールを、棒鋼、線材、又は形鋼からなる鋼材の熱間圧延における粗圧延に適用した場合、該熱間圧延による純摩耗損耗量が、前記鋼材の圧延量１００００トンにつき０．６ｍｍ以下であることが好ましい。 When the composite roll for hot rolling according to the first invention is applied to rough rolling in hot rolling of a steel material made of steel bars, wire rods, or shaped steel, the amount of pure wear and wear due to the hot rolling is that of the steel material. The rolling amount is preferably 0.6 mm or less per 10,000 tons.
前記目的に沿う第２の発明に係る熱間圧延用複合ロールの製造方法は、第１の発明に係る熱間圧延用複合ロールを製造する方法であって、前記組合せモールドとして、前記冷却緩衝材が黒鉛の銅製水冷モールドを使用し、前記芯材を１０ｍｍ／分以上１５０ｍｍ／分以下の範囲の速度で引抜く。 The manufacturing method of the composite roll for hot rolling according to the second invention that meets the above object is a method for manufacturing the composite roll for hot rolling according to the first invention, wherein the cooling buffer material is used as the combination mold. Uses a graphite copper water-cooled mold and draws the core material at a speed in the range of 10 mm / min to 150 mm / min.
前記目的に沿う第３の発明に係る熱間圧延用複合ロールの製造方法は、第１の発明に係る熱間圧延用複合ロールを製造する方法であって、前記熱処理として、焼入れ又は焼ならし後に、５５０℃以上７１０℃以下の温度範囲内で焼戻しを行う。 The method for producing a hot-rolling composite roll according to the third invention according to the third object is a method for producing the hot-rolling composite roll according to the first invention, wherein the heat treatment includes quenching or normalizing. Thereafter, tempering is performed within a temperature range of 550 ° C. or more and 710 ° C. or less.
請求項１〜７記載の熱間圧延用複合ロール、及び請求項８、９記載の熱間圧延用複合ロールの製造方法は、Ｃ量とＶ量の調整を行い、更にＴｉを所定量添加することにより、熱衝撃による熱き裂の伝播が優先的に発生するＭ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物を、粒状でかつ微細に分布できる。また、Ｃｒ量と、Ｍｏ及びＷのいずれか１種又は２種の量を調整することにより、肉盛層に晶出するこの金属炭化物の量を調整できる。
これにより、肉盛層に晶出したＭ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物の占有率を３．０面積％以下にできると共に、肉盛層におけるこの金属炭化物のサイズと二次デンドライト組織の結晶粒サイズを、それぞれ５０μｍ以下に微細化できるので、熱間粗圧延機でのロール損耗が著しく減少する。その結果、大量の鋼材の連続圧延が可能となり、経済的でしかも圧延製品の生産性の向上が図れ、更に圧延製品の品質向上がなされるため、工業的に大きな価値を有する。
The manufacturing method of the composite roll for hot rolling of Claims 1-7 and the composite roll for hot rolling of Claims 8 and 9 adjusts the C amount and the V amount, and further adds a predetermined amount of Ti. By virtue of this, the metal carbide composed of one or more of M 2 C, M 6 C, and M 7 C 3 in which the propagation of thermal cracks due to thermal shock occurs preferentially is granular and finely distributed. it can. Moreover, the amount of this metal carbide crystallized in the build-up layer can be adjusted by adjusting the amount of Cr and any one or two of Mo and W.
Thereby, while the occupancy rate of the metal carbide consisting of any one or more of M 2 C, M 6 C, and M 7 C 3 crystallized in the overlay layer can be reduced to 3.0 area% or less, Since the size of the metal carbide and the grain size of the secondary dendrite structure in the build-up layer can be refined to 50 μm or less, roll wear in a hot roughing mill is significantly reduced. As a result, it is possible to continuously roll a large amount of steel material, which is economical and can improve the productivity of the rolled product, and further improve the quality of the rolled product.
特に、請求項２記載の熱間圧延用複合ロールは、溶湯が、更に、Ｎｉ、Ｃｏ、及びＮｂのいずれか１種又は２種以上を含有するので、肉盛層の合金化を促進でき、熱間圧延用複合ロールの製品品質を向上できる。 Particularly, in the composite roll for hot rolling according to claim 2, since the molten metal further contains any one or more of Ni, Co, and Nb, alloying of the overlay layer can be promoted, Product quality of the composite roll for hot rolling can be improved.
請求項３記載の熱間圧延用複合ロールは、肉盛層の硬さを、ショアー硬さ：４５以上７５以下、かつ破壊靱性値ＫＩＣ又は疲労破壊靱性値ＫＩＣｆ：３０ＭＰａ・ｍ０．５以上にするので、熱間圧延用複合ロールとして必要な硬さを備える範囲で、従来よりも軟らかくでき、熱間圧延用複合ロールの寿命を伸ばすことができる。
また、所定の疲労破壊靱性値ＫＩＣｆを有するので、圧延の操業トラブルに遭遇した際のき裂発生や進展によるロール損耗を抑制できる。
The composite roll for hot rolling according to claim 3 has a hardness of the overlay layer of Shore hardness: 45 to 75, and fracture toughness value K IC or fatigue fracture toughness value K ICf : 30 MPa · m 0.5 Since it is set as the above, in the range provided with hardness required as a composite roll for hot rolling, it can be made softer than before and the life of the composite roll for hot rolling can be extended.
Moreover, since it has the predetermined fatigue fracture toughness value K ICf , roll wear due to crack generation and progress when encountering a rolling operation trouble can be suppressed.
請求項４記載の熱間圧延用複合ロールは、所定の耐高温酸化特性を有するので、熱間圧延用複合ロールの高温での使用に際し、熱間摩耗特性、肌荒れ性、及び焼付き性現象を改善できるため、製品の表面品質も良好にできる。 The composite roll for hot rolling according to claim 4 has a predetermined high-temperature oxidation resistance. Therefore, when the composite roll for hot rolling is used at a high temperature, it exhibits hot wear characteristics, skin roughness, and seizure phenomena. Since it can be improved, the surface quality of the product can also be improved.
請求項５記載の熱間圧延用複合ロールは、所定の耐熱間摩耗特性を有するので、熱間圧延用複合ロールの長寿命化が図れ、ランニングコストの低減が図れて経済的である。 Since the composite roll for hot rolling according to claim 5 has predetermined heat-resistant wear characteristics, the life of the composite roll for hot rolling can be extended and the running cost can be reduced, which is economical.
請求項６記載の熱間圧延用複合ロールは、所定の耐熱衝撃特性を有するので、熱間圧延用複合ロールと圧延する鋼材との摩擦発熱、及び鋼材の加工発熱が加わる際に、熱間圧延用複合ロールに大きな熱負荷がかかり、その後、熱間圧延用複合ロール表面が急冷された場合にも、き裂の発生を防止できる。 Since the composite roll for hot rolling according to claim 6 has predetermined thermal shock resistance, hot rolling is performed when frictional heat generation between the composite roll for hot rolling and the steel material to be rolled and processing heat generation of the steel material are applied. Even when a large heat load is applied to the composite roll, and then the surface of the composite roll for hot rolling is rapidly cooled, generation of cracks can be prevented.
請求項７記載の熱間圧延用複合ロールは、棒鋼、線材、又は形鋼からなる鋼材の熱間圧延における粗圧延に適用した場合、熱間圧延による純摩耗損耗量が、鋼材の圧延量１００００トンにつき０．６ｍｍ以下であるので、従来よりも熱間圧延用複合ロールの寿命を伸ばすことができ、ランニングコストの低減が図れて経済的である。 When the composite roll for hot rolling according to claim 7 is applied to rough rolling in hot rolling of a steel material made of steel bar, wire, or shaped steel, the amount of pure wear and wear due to hot rolling is 10,000 the rolling amount of the steel material. Since it is 0.6 mm or less per ton, it is possible to extend the life of the composite roll for hot rolling as compared with the prior art, and it is economical because the running cost can be reduced.
請求項８記載の熱間圧延用複合ロールの製造方法は、組合せモールドとして、冷却緩衝材が黒鉛の銅製水冷モールドを使用するので、溶湯が急激に冷却されることを防止でき、その結果、芯材を１０ｍｍ／分以上１５０ｍｍ／分以下の速度で引抜いても、割れが発生しない肉盛層を芯材の外表面に形成できる。 The manufacturing method of the composite roll for hot rolling according to claim 8 can prevent the molten metal from being rapidly cooled because the cooling buffer material uses a graphite water cooling mold made of graphite as the combination mold. Even if the material is pulled out at a speed of 10 mm / min or more and 150 mm / min or less, it is possible to form an overlay layer on which the crack does not occur on the outer surface of the core material.
続いて、添付した図面を参照しつつ、本発明を具体化した実施の形態につき説明し、本発明の理解に供する。
ここで、図１は本発明の一実施の形態に係る熱間圧延用複合ロールの製造方法の説明図である。
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is explanatory drawing of the manufacturing method of the composite roll for hot rolling which concerns on one embodiment of this invention.
図１に示すように、本発明の一実施の形態に係る熱間圧延用複合ロール（以下、単にロールともいう）は、金属製の中空式冷却型１０の上部内側面に冷却緩衝材１１を有する組合せモールド１２の内部に、鋼を素材とする中実又は中空の芯材１３を同心垂直に挿入し、芯材１３の外周の環状空隙部に溶湯１４を注入して芯材１３を連続的に降下させ、芯材１３の外表面に溶湯１４を溶着させながら冷却により凝固させて（連続鋳掛け鋳造法）、芯材１３の外周に肉盛層１５を形成した後、熱処理と機械加工を行って製造されるものである。以下、詳しく説明する。 As shown in FIG. 1, a composite roll for hot rolling according to an embodiment of the present invention (hereinafter also simply referred to as a roll) includes a cooling buffer material 11 on an upper inner surface of a metal hollow cooling mold 10. A solid or hollow core material 13 made of steel is inserted concentrically and vertically into the combination mold 12 having the melt, and the molten metal 14 is poured into the annular gap on the outer periphery of the core material 13 so that the core material 13 is continuously formed. Then, the molten metal 14 is deposited on the outer surface of the core material 13 and solidified by cooling (continuous casting method). After forming the build-up layer 15 on the outer periphery of the core material 13, heat treatment and machining are performed. Are manufactured. This will be described in detail below.
熱間圧延用複合ロールを構成する肉盛層１５は、耐摩耗性を確保し、かつ耐熱き裂性を向上するため、硬い粒状の炭化物であるＭＣ金属炭化物（Ｍは金属、Ｃは炭素を意味し、ＭＣからなる金属炭化物である。以下、ＭＣ型炭化物、又はＭＣ炭化物もいう）を主体に使用するものである。
このＭＣ炭化物の晶出量は、面積率（占有率）で５％以上（５面積％以上）確保することが必要である。
一方、ＭＣ炭化物と同時に晶出するＭ７Ｃ３炭化物、Ｍ２Ｃ炭化物、Ｍ６Ｃ炭化物、及びＭ３Ｃ炭化物は、少量では、本発明の効果を損なうものではなく、耐摩耗性の確保に有効なものであるが、耐熱き裂伝播特性においては望ましくないので、合計で５面積％以下にすることが必要である。
The build-up layer 15 constituting the composite roll for hot rolling is an MC metal carbide (M for metal, C for carbon), which is a hard granular carbide to ensure wear resistance and improve heat cracking resistance. This means a metal carbide composed of MC.Hereafter, MC type carbide or MC carbide) is mainly used.
It is necessary to ensure the crystallization amount of the MC carbide in an area ratio (occupancy ratio) of 5% or more (5 area% or more).
On the other hand, M 7 C 3 carbide, M 2 C carbide, M 6 C carbide, and M 3 C carbide that crystallize simultaneously with MC carbide do not impair the effect of the present invention in a small amount, and ensure wear resistance. However, since it is not desirable in the heat-resistant crack propagation characteristic, it is necessary to make it 5% by area or less in total.
特に、肉盛層に晶出したＭ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物（特に、Ｍ２Ｃ金属炭化物）の占有率は、３．０面積％（好ましくは、２．０面積％）以下とする。ここで、占有率が３．０面積％を超える場合、この金属炭化物量が多くなり過ぎ、これに沿ってき裂が伝播する。一方、この金属炭化物は、その量が少なければ好ましいため、下限値については規定していないが、実際には、少なくとも０．１面積％程度存在する。
これらの事項に基づき、熱間圧延用複合ロールの肉盛層１５を形成する溶湯の化学成分、及びその量を限定した理由について、以下説明する。
In particular, the occupation ratio of metal carbide (particularly M 2 C metal carbide) composed of one or more of M 2 C, M 6 C, and M 7 C 3 crystallized in the overlay layer is 3 0.0 area% (preferably 2.0 area%) or less. Here, when the occupation ratio exceeds 3.0 area%, the amount of the metal carbide becomes too large, and the crack propagates along this. On the other hand, since this metal carbide is preferable if its amount is small, the lower limit value is not specified, but in reality, it exists at least about 0.1 area%.
Based on these matters, the chemical components of the molten metal forming the overlay layer 15 of the composite roll for hot rolling, and the reason for limiting the amount thereof will be described below.
Ｃ（炭素）：１．０質量％以上２．０質量％以下
Ｃは、ロールの性能に直接影響する硬さを得るために最も重要な元素である。
しかし、含有量が１．０質量％より少ない場合、耐摩耗性及び耐肌荒れ性を向上するために有効な硬い炭化物の晶出量が少なくなり、更に基地に固溶するＣが不足する。このため、焼入れによっても十分な基地硬さを得られなくなると同時に、合金添加の効果を十分発揮できず、耐摩耗性が著しく劣化する。一方、含有量が２．０質量％を超える場合、本来は脆い炭化物の晶出量が増加し、特に、粗大な炭化物が凝集して結晶粒界に晶出し、前述の通り、圧延中にこれが表層から剥離し、圧延製品を損傷し、使用に耐えない。
以上のことから、Ｃの含有量を１．０質量％以上２．０質量％以下としたが、より効果を高めるため、上限を１．８質量％、下限を１．５質量％とすることが好ましい。
C (carbon): 1.0% by mass or more and 2.0% by mass or less C is the most important element for obtaining hardness that directly affects the performance of the roll.
However, when the content is less than 1.0% by mass, the amount of crystallization of hard carbide effective for improving the wear resistance and the rough skin resistance is reduced, and further, C that is dissolved in the base is insufficient. For this reason, sufficient base hardness cannot be obtained even by quenching, and at the same time, the effect of alloy addition cannot be fully exhibited, and the wear resistance is remarkably deteriorated. On the other hand, if the content exceeds 2.0% by mass, the amount of crystallization of originally brittle carbides increases, and in particular, coarse carbides aggregate and crystallize at the grain boundaries. It peels off from the surface layer, damages the rolled product, and cannot be used.
From the above, the content of C is set to 1.0% by mass or more and 2.0% by mass or less, but in order to further enhance the effect, the upper limit is 1.8% by mass and the lower limit is 1.5% by mass. Is preferred.
Ｓｉ（ケイ素）：０．２質量％以上２．０質量％以下、Ｍｎ（マンガン）：０．２質量％以上２．０質量％以下
ＳｉとＭｎは、本発明を特徴づけるものではないが、共に脱酸効果と溶湯の流動性を高めることを目的として、一般の高速度鋼に含まれる量、即ち各々０．２質量％以上２．０質量％以下含有させている。なお、ＳｉとＭｎの各含有量が０．２質量％未満の場合、その効果が不十分であり、一方２．０質量％を超える場合、靱性が低下する。
以上のことから、ＳｉとＭｎの含有量を、各々０．２質量％以上２．０質量％以下としたが、それぞれ上限を１．５質量％、下限を０．３質量％とすることが好ましい。
Si (silicon): 0.2% by mass or more and 2.0% by mass or less, Mn (manganese): 0.2% by mass or more and 2.0% by mass or less Si and Mn do not characterize the present invention. In order to increase the deoxidation effect and the fluidity of the molten metal, the amount contained in general high speed steel, that is, 0.2% by mass or more and 2.0% by mass or less, respectively. In addition, when each content of Si and Mn is less than 0.2 mass%, the effect is inadequate, and when it exceeds 2.0 mass%, toughness falls.
From the above, the contents of Si and Mn were 0.2% by mass or more and 2.0% by mass or less, respectively, but the upper limit was 1.5% by mass and the lower limit was 0.3% by mass. preferable.
Ｖ（バナジウム）：４．０質量％以上８．０質量％以下
Ｖは、優先的にＣと結合し、前記した既存のロールに認められるセメンタイト（Ｆｅ３Ｃ）やクロム炭化物（Ｃｒ７Ｃ３）に比べ、極めて硬い粒状のＭＣ型炭化物であるＶＣ炭化物を晶出させ、耐摩耗性を向上させるため、極めて有効な元素である。
また、本実施の形態においては、Ｍ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物のサイズを５０μｍ以下、更には３０μｍ以下まで微細にすることが望ましく、微小で粒状に晶出させ、かつ極めて硬いＶＣ炭化物を積極的に利用することが不可欠である。このＶＣ炭化物は、溶湯より優先的に初晶として晶出し、凝固組織を決定する理由からも、Ｖは重要な元素であり、その含有量はＣ量との関係で選択される。
V (vanadium): 4.0 wt% to 8.0 wt% or less V is preferentially bound by C, cementite found in existing rolls mentioned above (Fe 3 C) or chromium carbide (Cr 7 C 3 ) Is an extremely effective element for crystallizing VC carbide, which is an extremely hard granular MC type carbide, and improving wear resistance.
In the present embodiment, the size of the metal carbide composed of one or more of M 2 C, M 6 C, and M 7 C 3 is reduced to 50 μm or less, and further to 30 μm or less. Is desirable, and it is indispensable to positively use VC carbide which is fine and granular and crystallizes. This VC carbide crystallizes out as a primary crystal preferentially over the molten metal, and V is an important element from the reason of determining the solidification structure, and its content is selected in relation to the C content.
ここで、前記したＣの含有量が１．０質量％以上２．０質量％以下の範囲では、Ｖの含有量が４．０質量％未満の場合、ＶＣ炭化物が晶出せず、耐摩耗性を向上させ得ない。一方、含有量が８．０質量％を超える場合、前記した通り、初晶の炭化物が多量に晶出し、材料靱性を損なうと共に、炭化物が粒界に偏析して、これが圧延使用中に欠け落ち、耐肌荒れ性を損なう。
以上のことから、Ｖの含有量を４．０質量％以上８．０質量％以下としたが、より効果を高めるため、上限を７．０質量％、下限を５．０質量％とすることが好ましい。
Here, when the C content is in the range of 1.0% by mass or more and 2.0% by mass or less, when the V content is less than 4.0% by mass, the VC carbide does not crystallize and wear resistance is increased. Cannot be improved. On the other hand, when the content exceeds 8.0% by mass, as described above, a large amount of primary crystal carbides are crystallized and the toughness of the material is impaired, and the carbides are segregated at the grain boundaries, which are lost during rolling use. Impairs rough skin resistance.
From the above, the content of V is set to 4.0% by mass or more and 8.0% by mass or less. However, in order to further improve the effect, the upper limit is 7.0% by mass and the lower limit is 5.0% by mass. Is preferred.
Ｃｒ（クロム）：２．０質量％以上５．０質量％以下
Ｃｒは、一部が基地組織にも固溶して焼入れにより硬さを向上させ、更に焼戻しにおいて二次析出効果を促進し、Ｃｒも一部が基地組織に固溶し、高温での強度及び硬さを向上する。
このため、熱間圧延に供した場合、耐摩耗性を向上させる作用を有しており、その効果を現わすために、Ｃｒの含有量を２．０質量％以上５．０質量％以下としたが、より効果を高めるため、上限を４．０質量％、下限を３．０質量％とすることが好ましい。
Cr (chromium): 2.0% by mass or more and 5.0% by mass or less Cr is partly dissolved in the base structure to improve the hardness by quenching, and further promote the secondary precipitation effect in tempering, A part of Cr also dissolves in the matrix structure and improves strength and hardness at high temperatures.
For this reason, it has the effect | action which improves abrasion resistance, when it uses for hot rolling, and in order to show the effect, content of Cr is 2.0 mass% or more and 5.0 mass% or less However, in order to enhance the effect, it is preferable to set the upper limit to 4.0% by mass and the lower limit to 3.0% by mass.
Ｍｏ（モリブデン）及びＷ（タングステン）のいずれか１種又は２種（以下、共晶炭化物形成材ともいう）を２．０質量％以上８．０質量％以下
ＭｏとＷは、主として硬いＭ２Ｃ型の共晶炭化物（即ち、Ｍ２Ｃ金属炭化物）を形成し、耐摩耗性を向上させるもので、前記した特許文献１においては、積極的に用いられていた。この炭化物は、棒状となって結晶粒界に晶出する。この点では、前記Ｖで説明した凝集して晶出するセメンタイトやクロム炭化物ほど著しく有害ではないが、複数の炭化物が密集して晶出した場合には、結果的に大きな炭化物としてみなされ、これが欠け落ちる。このため、炭化物の晶出量を少量に抑制することが不可欠であり、実用的には、組織に占める面積率で３．０％以下とすることが望ましい。なお、熱間圧延用複合ロールの肉盛層は、鋳造時に晶出したＭ２Ｃ型炭化物が、その後の熱処理工程を経てＭ６Ｃ型炭化物になる。
One or two of Mo (molybdenum) and W (tungsten) (hereinafter also referred to as eutectic carbide forming material) is 2.0 mass% or more and 8.0 mass% or less. Mo and W are mainly hard M 2. A C-type eutectic carbide (that is, M 2 C metal carbide) is formed to improve wear resistance, and in the above-mentioned Patent Document 1, it has been actively used. This carbide is rod-shaped and crystallizes at the grain boundary. In this respect, it is not as harmful as the cementite and chromium carbides which are agglomerated and crystallized as described in the above V. However, when a plurality of carbides are crystallized densely, it is regarded as a large carbide as a result. Chipped. For this reason, it is indispensable to suppress the crystallization amount of the carbide to a small amount, and it is practically desirable that the area ratio in the structure is 3.0% or less. In the overlay layer of the composite roll for hot rolling, the M 2 C type carbide crystallized at the time of casting becomes the M 6 C type carbide through the subsequent heat treatment process.
一方、ＭｏはＣｒと同様、一部が基地組織にも固溶して焼入れにより硬さを向上させ、更に焼戻しにおいて二次析出効果を促進し、Ｗも一部が基地組織に固溶し、高温での強度及び硬さを向上する。
このため、熱間圧延に供した場合、耐摩耗性を向上させる作用を有しており、その効果が現れるためには、１種又は２種を前記した量含有することが必要である。なお、前記したＭ２Ｃ金属炭化物の量を考慮した場合、ＭｏとＷの両元素の総量を、２．０質量％以上８．０質量％以下としたが、より効果を高めるため、上限を６．０質量％、下限を３．０質量％とすることが好ましい。
On the other hand, Mo, like Cr, partly dissolves in the base structure and improves hardness by quenching, further promotes the secondary precipitation effect in tempering, and W also partly dissolves in the base structure, Improves strength and hardness at high temperatures.
For this reason, when it uses for hot rolling, it has the effect | action which improves abrasion resistance, and in order for the effect to appear, it is necessary to contain 1 type or 2 types as mentioned above. In consideration of the amount of M 2 C metal carbide described above, the total amount of both Mo and W elements was set to 2.0% by mass or more and 8.0% by mass or less. It is preferable that 6.0 mass% and a minimum be 3.0 mass%.
Ｔｉ（チタン）：０．０５質量％以上０．３０質量％以下
Ｔｉは、極めて微細で、かつ極めて硬いＴｉＣ炭化物を生成するが、併せてＭＣ炭化物の晶出核の役目を果たし、炭化物の分散を促進することで有効である。その含有量は、少量でも効果があるが、実用的な下限値は０．０５質量％である。しかし、Ｔｉは極めて強い酸化元素であり、酸化生成物を介在物欠陥として肉盛層に残存させないため、０．３０質量％を上限とした。
なお、ＡｌとＺｒも、それぞれ０．２０質量％以下含有することで、Ｔｉと同様の効果をそれぞれ奏するため、ＡｌとＺｒが含まれていても、本願発明の効果を損なうものではない。
以上のことから、Ｔｉを０．０５質量％以上０．３０質量％以下としたが、上限を０．２５質量％、下限を０．０７質量％とすることが好ましい。
Ti (titanium): 0.05% by mass or more and 0.30% by mass or less Ti forms extremely fine and extremely hard TiC carbides, but also serves as a crystallization nucleus for MC carbides and disperses the carbides. It is effective in promoting. The content is effective even with a small amount, but a practical lower limit is 0.05% by mass. However, Ti is an extremely strong oxidizing element, and the oxidation product is not left as an inclusion defect in the build-up layer, so 0.30% by mass was made the upper limit.
In addition, since each of Al and Zr contains 0.20% by mass or less and exhibits the same effect as Ti, the effects of the present invention are not impaired even if Al and Zr are included.
From the above, Ti is set to 0.05 mass% or more and 0.30 mass% or less, but the upper limit is preferably 0.25 mass% and the lower limit is preferably 0.07 mass%.
以上に示した化学成分を有し、残部がＦｅ及び不可避的不純物からなるものが原溶湯である。
これにより、肉盛層１５に晶出したＭ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物の占有率を３．０面積％（更には、２．０面積％）以下にできると共に、この金属炭化物のサイズ（最大幅）と肉盛層１５の二次デンドライト組織の結晶粒サイズ（二次デンドライトアームの間隔）を、それぞれ５０μｍ以下（この金属炭化物については、３０μｍ以下、更には２０μｍ以下）に微細化できる。
また、以上に示した溶湯は、更にＮｉ、Ｃｏ、及びＮｂのいずれか１種又は２種以上を含有してもよい。
The raw molten metal having the above-described chemical components, the balance being Fe and inevitable impurities.
Thereby, the occupation rate of the metal carbide consisting of any one or more of M 2 C, M 6 C, and M 7 C 3 crystallized in the build-up layer 15 is 3.0 area% (further, 2.0 area%) or less, and the size (maximum width) of the metal carbide and the crystal grain size of the secondary dendrite structure of the overlay layer 15 (interval of the secondary dendrite arms) are each 50 μm or less (this metal About carbide, it can refine | miniaturize to 30 micrometers or less, Furthermore, 20 micrometers or less.
Moreover, the molten metal shown above may further contain any one or more of Ni, Co, and Nb.
Ｎｉ（ニッケル）：１．０質量％以上５．０質量％以下
Ｎｉは、１．０質量％以上添加すると、焼入れ性を向上させる効果を有する。
直径の大きいロール等で大きな硬度深度が要求される場合には、その要求に応じて添加するとよい。しかし、多量に添加すると、残留オーステナイトが過剰となり、かえって高硬度が得られなくなるため、５．０質量％以下の範囲で用いることが有効である。
以上のことから、Ｎｉを添加する場合、その量を、１．０質量％以上５．０質量％以下としたが、上限を３．０質量％、更には２．０質量％、下限を１．５質量％とすることが好ましい。
Ni (nickel): 1.0% by mass or more and 5.0% by mass or less Ni, when added in an amount of 1.0% by mass or more, has an effect of improving hardenability.
When a large depth of hardness is required with a roll having a large diameter or the like, it may be added according to the requirement. However, when added in a large amount, the retained austenite becomes excessive and high hardness cannot be obtained. Therefore, it is effective to use in a range of 5.0% by mass or less.
From the above, when Ni is added, the amount is set to 1.0% by mass or more and 5.0% by mass or less, but the upper limit is 3.0% by mass, further 2.0% by mass, and the lower limit is 1%. It is preferable to set it as 5 mass%.
Ｃｏ（コバルト）：１．０質量％以上５．０質量％以下
Ｃｏは、１．０質量％以上添加すると、高温使用下で基地の硬さと強度を向上させると共に、耐食性にも効果がある。また、熱処理時には、焼戻し抵抗を増大させるため、高温での焼戻し処理が可能になる。一方、５．０質量％を超える量を添加する場合は、鋳造時の溶湯の流動性を悪くすると共に、基地の靱性を悪くするため、５．０質量％以下の範囲で用いることが有効である。
以上のことから、Ｃｏを添加する場合、その量を、１．０質量％以上５．０質量％以下とするが、上限を４．０質量％、下限を２．０質量％とすることが好ましい。
Co (cobalt): 1.0% by mass or more and 5.0% by mass or less Co, when added in an amount of 1.0% by mass or more, improves the hardness and strength of the matrix under high temperature use, and also has an effect on corrosion resistance. Further, during the heat treatment, the tempering resistance is increased, so that a tempering treatment at a high temperature becomes possible. On the other hand, when adding an amount exceeding 5.0% by mass, it is effective to use in the range of 5.0% by mass or less in order to deteriorate the fluidity of the molten metal during casting and the toughness of the base. is there.
From the above, when adding Co, the amount is set to 1.0 mass% or more and 5.0 mass% or less, but the upper limit is 4.0 mass% and the lower limit is 2.0 mass%. preferable.
Ｎｂ（ニオブ）：０．０２質量％以上０．２０質量％以下
Ｎｂは、Ｖと同様にＭＣ型炭化物を生成するため、Ｖの代替元素として、０．０２質量％以上０．２０質量％以下添加することが有効である。ここで、Ｎｂの添加により過共晶域となり、初晶としてＭＣ型炭化物が偏析して晶出しない範囲として、０．２０質量％を上限値とした。
以上のことから、Ｎｂを添加する場合、その量を、０．０２質量％以上０．２０質量％以下とするが、上限を０．１７質量％、下限を０．０５質量％とすることが好ましい。
Nb (niobium): 0.02% by mass or more and 0.20% by mass or less Nb generates MC-type carbides similarly to V. Therefore, as an alternative element for V, 0.02% by mass or more and 0.20% by mass or less It is effective to add. Here, the upper limit was set to 0.20% by mass as a range in which the addition of Nb resulted in a hypereutectic region and MC type carbides segregated as primary crystals and did not crystallize.
From the above, when Nb is added, the amount is 0.02% by mass or more and 0.20% by mass or less, but the upper limit is 0.17% by mass and the lower limit is 0.05% by mass. preferable.
以上に示した化学成分を有する溶湯１４を芯材１３の外表面に溶着させて、芯材１３の外周に肉盛層１５を形成した中間品に対し、更に熱処理が施されている。
この熱処理としては、まず中間品の肉盛層に焼入れ又は焼きならしを施す。具体的には、従来技術と同様、まず熱処理炉にて中間品全体を９００℃以上１１００℃以下の温度範囲内に加熱し、一定時間（例えば、１〜１０時間程度）保持した後、大気中もしくは衝風にて、常温近くまで冷却する。これにより、肉盛層１５の生地を、硬いマルテンサイトもしくはベイナイトにできる。
この後で、５５０℃以上かつＡ１変態点（即ち７１０℃）以下の温度範囲内で焼戻しを施し、必要に応じて、更にもう１回、もしくは２回以上、５５０℃以上７１０℃以下の温度範囲内からの焼戻しを行う。
The intermediate product in which the molten metal 14 having the chemical components shown above is welded to the outer surface of the core material 13 and the build-up layer 15 is formed on the outer periphery of the core material 13 is further subjected to heat treatment.
As the heat treatment, first, the intermediate build-up layer is quenched or normalized. Specifically, as in the prior art, first, the whole intermediate product is first heated in a temperature range of 900 ° C. to 1100 ° C. in a heat treatment furnace, held for a certain time (for example, about 1 to 10 hours), and then in the atmosphere. Or cool to near normal temperature with a blast. Thereby, the dough of the build-up layer 15 can be made into hard martensite or bainite.
Thereafter, tempering is performed within a temperature range of 550 ° C. or more and A 1 transformation point (ie, 710 ° C.) or less, and if necessary, a temperature of 550 ° C. or more and 710 ° C. or less once more or twice. Temper from within the range.
従来技術においては、焼入れ又は焼ならし後、５００〜６００℃の温度範囲内で、１回もしくは２回以上の焼戻しを実施し、これにより、肉盛層のシュアー硬さ（ＨＳ）を７５〜９０にしていた。しかし、本願発明では、従来よりも高い焼戻し温度で、１回もしくは２回以上の焼戻しを行い、ショアー硬さ（ＨＳ）を４５以上７５以下（好ましくは、上限を７０、下限を５０）に調質して、基地組織に対して十分に靱性を与える。
また、ショアー硬さは、焼戻し温度と基本的には対応するが、従来のハイス系ロールと比べて破壊靱性値が向上する７５以下とし、下限値は本発明の化学成分範囲で耐摩耗性の向上が可能な４５とした。
In the prior art, after quenching or normalizing, tempering is performed once or twice in a temperature range of 500 to 600 ° C., and thereby the surfacing layer has a Shure hardness (HS) of 75 to It was 90. However, in the present invention, tempering is performed once or twice or more at a higher tempering temperature than before, and the Shore hardness (HS) is adjusted to 45 to 75 (preferably, the upper limit is 70 and the lower limit is 50). And provide sufficient toughness to the base tissue.
Further, the Shore hardness basically corresponds to the tempering temperature, but the fracture toughness value is improved to 75 or less as compared with the conventional high-speed roll, and the lower limit value is wear resistance within the chemical component range of the present invention. 45 which can be improved.
このようにして製造した中間品に対し、寸法と形状を整える機械加工が施されることにより、熱間圧延用複合ロールとなる。
なお、熱間圧延用複合ロールを圧延に使用するに際し、圧延速度が比較的遅い使用条件の場合は、前記した焼戻し温度範囲内の高温側で焼戻しを実施して、前記したショアー硬さ範囲内で低いショアー硬さに調整する。一方、圧延速度が比較的速い使用条件で熱間圧延用複合ロールを使用する場合は、前記した焼戻し温度範囲内の低温側で焼戻しを実施して、前記したショアー硬さ範囲内で高いショアー硬さに調整する。
このような熱間圧延用複合ロールを、棒鋼、線材、又は形鋼からなる鋼材の熱間圧延に適用した場合、熱間圧延による熱間圧延用複合ロールの純摩耗損耗量が、鋼材の圧延量１００００トンにつき片肉で０．６ｍｍ以下となる。
The intermediate product thus manufactured is subjected to machining for adjusting the size and shape, thereby forming a composite roll for hot rolling.
When using the composite roll for hot rolling for rolling, if the rolling speed is relatively slow, tempering is performed on the high temperature side within the tempering temperature range described above, and within the Shore hardness range described above. Adjust to a low Shore hardness. On the other hand, when using a composite roll for hot rolling under conditions where the rolling speed is relatively high, tempering is performed on the low temperature side within the tempering temperature range described above, and high shore hardness within the shore hardness range described above. Adjust it.
When such a hot-rolling composite roll is applied to hot rolling of a steel material made of steel bar, wire, or shape steel, the amount of pure wear and wear of the hot-rolling composite roll by hot rolling is reduced by rolling the steel material. It becomes 0.6 mm or less in one piece per 10,000 tons.
続いて、前記した熱間圧延用複合ロール１０を製造する連続鋳掛け肉盛溶接用モールド装置（以下、単に肉盛溶接用モールド、連続鋳掛け肉盛溶接用モールドともいう）１６について、図１を参照しながら説明する。なお、肉盛溶接用モールド１６は、特開２０００−１７６６２８号公報に開示された連続鋳掛け肉盛溶接用モールドと略同様の構成を有している。
肉盛溶接用モールド１６は、銅製水冷モールドである組合せモールド１２を有している。この組合せモールド１２は、金属製の中空式冷却型１０を有し、その上部内側面には、黒鉛で構成された冷却緩衝材１１が設けられている。
この組合せモールド１２の上方には、電磁誘導加熱コイル１７で外包された中空環状の耐火枠１８が配置されている。
なお、図１において、１９はガラスコーティング層、２０は予熱用の電磁誘導加熱コイルを、それぞれ示している。
Subsequently, with reference to FIG. 1 for a continuous casting overlay welding mold apparatus 16 (hereinafter also simply referred to as overlay welding mold or continuous casting overlay welding mold) 16 for manufacturing the above-described hot rolling composite roll 10. While explaining. The overlay welding mold 16 has substantially the same configuration as the continuous casting overlay welding mold disclosed in Japanese Unexamined Patent Publication No. 2000-176628.
The overlay welding mold 16 has a combination mold 12 which is a copper water-cooled mold. This combination mold 12 has a hollow cooling mold 10 made of metal, and a cooling buffer material 11 made of graphite is provided on the upper inner surface thereof.
Above this combination mold 12, a hollow annular refractory frame 18 enclosed by an electromagnetic induction heating coil 17 is disposed.
In FIG. 1, 19 indicates a glass coating layer, and 20 indicates a preheating electromagnetic induction heating coil.
次に、本発明の一実施の形態に係る熱間圧延用複合ロールの製造方法について、図１を参照しながら説明する。
まず、連続鋳掛け肉盛溶接用モールド１６の中央に、芯材１３を同心垂直に立てて挿入し、この芯材１３全体を、予熱用の電磁誘導加熱コイル２０により予熱しながら、下方へ引抜く。このとき、前記した化学成分を有し、融点を超える所定の温度に調整した溶湯１４を、耐火枠１８と芯材１３との環状空隙部に注入して、電磁誘導加熱コイル１７により、溶湯１４の温度を前記所定の温度範囲となるように、誘導加熱を行って調整する。そして、耐火枠１８の下方に配置した組合せモールド１２により、溶湯１４を凝固させて肉盛層１５を形成し、しかる後、一体となった肉盛層１５と芯材１３を順次下方へ連続的に引き出して、熱間圧延用複合ロールの中間品を製造する。
Next, the manufacturing method of the composite roll for hot rolling which concerns on one embodiment of this invention is demonstrated, referring FIG.
First, the core material 13 is inserted concentrically and vertically into the center of the continuous casting overlay welding mold 16, and the entire core material 13 is pulled down while being preheated by the preheating electromagnetic induction heating coil 20. . At this time, the molten metal 14 having the above-described chemical components and adjusted to a predetermined temperature exceeding the melting point is injected into the annular gap between the refractory frame 18 and the core member 13, and is melted by the electromagnetic induction heating coil 17. The temperature is adjusted by induction heating so that the temperature falls within the predetermined temperature range. Then, the molten metal 14 is solidified by the combination mold 12 disposed below the fireproof frame 18 to form the build-up layer 15, and then the built-up build-up layer 15 and the core material 13 are successively successively lowered downward. To produce an intermediate product of a composite roll for hot rolling.
従来技術では、組合せモールドとして、黒鉛を内装した鉄製モールドが用いられてきた。しかし、本願発明においては、肉盛層１５の組織を緻密にするため、凝固冷却速度を増大する必要があり、従来の鉄製モールドに代えて、熱伝導が極めて良好で肉盛層１５からの脱熱を飛躍的に向上できる銅製水冷モールド（銅合金製水冷モールドでもよい）を採用した。その結果、肉盛層１５は、理想的な鋳造組織となり、かつ遠心鋳造等のような他の方法に比べ、極めて緻密な組織が得られる。
以上の方法により、芯材１３を、１０ｍｍ／分以上１５０ｍｍ／分以下（好ましくは、２０ｍｍ／分以上１３０ｍｍ／分以下）の範囲の速度で、順次下方へ引抜くことができる。
In the prior art, as a combination mold, an iron mold with an internal graphite has been used. However, in the present invention, in order to make the structure of the overlay layer 15 dense, it is necessary to increase the solidification cooling rate. Instead of the conventional iron mold, the heat conduction is extremely good and the removal from the overlay layer 15 is necessary. A copper water-cooled mold (or a copper alloy water-cooled mold may be used) capable of dramatically improving heat. As a result, the built-up layer 15 has an ideal cast structure, and an extremely dense structure can be obtained as compared with other methods such as centrifugal casting.
By the above method, the core material 13 can be sequentially drawn downward at a speed in the range of 10 mm / min to 150 mm / min (preferably 20 mm / min to 130 mm / min).
このようにして製造した中間品に、更に前記した熱処理を施す。
この熱処理としては、熱処理炉にて中間品全体を９００℃以上１１００℃以下の温度範囲内に加熱し、一定時間（例えば、１〜１０時間程度）保持した後、大気中もしくは衝風にて、常温近くまで冷却して、中間品の肉盛層１５に焼入れ又は焼きならしを施す。
そして、５５０℃以上７１０℃以下の温度範囲内で焼戻しを施し、更に再度、もしくは２回以上５５０℃以上７１０℃以下の温度範囲内から焼戻しを行う。
これにより、芯材１３の外周に形成した肉盛層１５の硬さを、ショアー硬さ：４５以上７５以下、かつ破壊靱性値ＫＩＣ又は疲労破壊靱性値ＫＩＣｆ：３０ＭＰａ・ｍ０．５以上（好ましくは、３５ＭＰａ・ｍ０．５以上）にできる。
このように、熱処理が施された中間品に対して、寸法と形状を整える機械加工を施すことにより、熱間圧延用複合ロールが製造される。
The intermediate product thus manufactured is further subjected to the heat treatment described above.
As this heat treatment, the whole intermediate product is heated in a temperature range of 900 ° C. or more and 1100 ° C. or less in a heat treatment furnace, held for a certain time (for example, about 1 to 10 hours), and then in the atmosphere or in a blast, After cooling to near room temperature, the intermediate overlay layer 15 is quenched or normalized.
Then, tempering is performed within a temperature range of 550 ° C. or more and 710 ° C. or less, and tempering is performed again or twice or more within a temperature range of 550 ° C. or more and 710 ° C. or less.
Thereby, the hardness of the built-up layer 15 formed on the outer periphery of the core material 13 is Shore hardness: 45 or more and 75 or less, and the fracture toughness value K IC or the fatigue fracture toughness value K ICf : 30 MPa · m 0.5 or more. (Preferably, 35 MPa · m 0.5 or more).
In this way, a composite roll for hot rolling is manufactured by subjecting the intermediate product subjected to the heat treatment to machining for adjusting the size and shape.
次に、本発明の作用効果を確認するために行った実施例について説明する。
ここでは、図１に示す肉盛溶接用モールド１６を使用して前記した方法により、表１に示す化学成分及びその量を有する溶湯から、熱間圧延用複合ロールの中間品を製造し、試験片を切り出した。そして、この試験片に対して前記した熱処理を行い、これを実施例及び比較例とした。なお、実施例１〜５は、各化学成分の量を前記した範囲内に設定した結果であり、一方、比較例１は炭素成分の量を、また比較例２はチタン成分の量を、それぞれ前記した範囲外（比較例１の炭素成分：２．２質量％、比較例２のチタン成分：０質量％）に設定した結果である。
ここで、実施例１〜５、比較例１、２、及び参考例（一般のハイス材）の化学成分とその熱処理条件を、表１、表２にそれぞれ示す。なお、表１に示す化学成分以外の残部は、Ｆｅ及び不可避的不純物である。
Next, examples carried out for confirming the effects of the present invention will be described.
Here, the intermediate product of the composite roll for hot rolling is manufactured from the molten metal having the chemical components shown in Table 1 and the amount thereof by the method described above using the overlay welding mold 16 shown in FIG. A piece was cut out. And this heat processing was performed with respect to this test piece, and this was made into the Example and the comparative example. In addition, Examples 1-5 are the results which set the quantity of each chemical component in the above-mentioned range, On the other hand, the comparative example 1 is the quantity of a carbon component, and the comparative example 2 is the quantity of a titanium component, respectively. It is the result set outside the above-mentioned range (carbon component of Comparative Example 1: 2.2% by mass, titanium component of Comparative Example 2: 0% by mass).
Here, Tables 1 and 2 show chemical components and heat treatment conditions of Examples 1 to 5, Comparative Examples 1 and 2, and Reference Example (general high-speed material), respectively. The balance other than the chemical components shown in Table 1 is Fe and inevitable impurities.
比較例１、２の代表的な光学顕微鏡写真（ＡＭ）と、実施例１〜５の代表的な光学顕微鏡写真を、図２（Ａ）、（Ｂ）にそれぞれ示すが、比較例と実施例の金属組織は共に、微細な粒状のＭＣ金属炭化物が主体となっていた。しかし、比較例は実施例と比較して、大きな板状（もしくは層状）のＭ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物（図２（Ａ）、（Ｂ）中の黒部分）が多く晶出していた。
ここで、実施例１〜５、比較例１、２、及び参考例について、晶出した金属炭化物（ＭＣ炭化物、Ｍ２Ｃ炭化物、及びその合計値）の占有率と、結晶粒サイズ（２−ＤＡＳ、ＭＣ炭化物、及びＭ２Ｃ炭化物）の測定結果を、それぞれ表３に示す。
Representative optical micrographs (AM) of Comparative Examples 1 and 2 and representative optical micrographs of Examples 1 to 5 are shown in FIGS. 2 (A) and 2 (B), respectively. Comparative Examples and Examples Both of these metal structures were mainly composed of fine granular MC metal carbide. However, in the comparative example, compared to the example, a metal carbide composed of any one or more of large plate (or layered) M 2 C, M 6 C, and M 7 C 3 (FIG. 2 ( A) and a black part in (B) were crystallized a lot.
Here, with respect to Examples 1 to 5, Comparative Examples 1 and 2, and Reference Example, the occupancy of the crystallized metal carbide (MC carbide, M 2 C carbide, and the total value thereof) and the crystal grain size (2- Table 3 shows the measurement results of DAS, MC carbide, and M 2 C carbide.
表３に示すＭＣ炭化物の占有率は、実施例１〜５のいずれについても比較例１、２より高く、Ｍ２Ｃ炭化物（Ｍ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物が存在するが、主としてＭ２Ｃ金属炭化物）の占有率は、比較例１、２と比べて極端に低減できることを確認できた。なお、実施例１〜５は、Ｍ２Ｃ炭化物の占有率をいずれも３．０面積％以下に低減できた。 The occupancy ratio of MC carbide shown in Table 3 is higher than those of Comparative Examples 1 and 2 in any of Examples 1 to 5, and any one of M 2 C carbide (M 2 C, M 6 C, and M 7 C 3 ). It has been confirmed that the occupancy ratio of mainly M 2 C metal carbide) can be extremely reduced as compared with Comparative Examples 1 and 2 , although metal carbide composed of seeds or two or more kinds exists. In Examples 1 to 5, the occupation ratio of the M 2 C carbide could be reduced to 3.0 area% or less.
また、実施例１〜５の２−ＤＡＳ（二次デンドライト組織のアームの間隔、即ち二次デンドライト組織の結晶粒サイズ）は、いずれも比較例１、２、及び参考例より小さく、５０μｍ以下にできることを確認できた。
更に、実施例１〜５のＭ２Ｃ炭化物の結晶粒サイズは、いずれも比較例１、２、及び参考例よりも小さく、３０μｍ以下にできることを確認できた。
In addition, the 2-DAS (secondary dendrite structure arm spacing, that is, the crystal grain size of the secondary dendrite structure) of Examples 1 to 5 is smaller than those of Comparative Examples 1 and 2 and the reference example, and is 50 μm or less. I was able to confirm that I could do it.
Further, it was confirmed that the crystal grain sizes of the M 2 C carbides of Examples 1 to 5 were smaller than those of Comparative Examples 1 and 2 and the reference example, and could be 30 μm or less.
この実施例１〜５、比較例１、２、及び参考例について、その基礎物性の１つである破壊靱性値（ＫＩＣ）を室温で測定した。なお、破壊靱性値の測定は、深さ１２．５ｍｍのノッチが形成された厚み２５ｍｍの３点曲げ試験片を、間隔１００ｍｍのスパン上に載置し、ＡＳＴＭ−Ｅ８１３−８１に基づいて行った。この３点曲げ試験片のノッチは、その深さが２段となっており、１段目の深さが１０ｍｍ、内幅が２ｍｍ、２段目の内幅が０．２ｍｍである。
測定の結果、実施例１〜５の破壊靱性値Ｋ１Ｃは、比較例１、２、及び参考例よりも高い数値（３０ＭＰａ・ｍ０．５以上、ここでは、３５ＭＰａ・ｍ０．５以上）であった。なお、実施例１〜５のショアー硬さは、４５以上７５以下の範囲内であった。
For Examples 1 to 5, Comparative Examples 1 and 2, and Reference Example, the fracture toughness value (K IC ), which is one of the basic physical properties, was measured at room temperature. The fracture toughness value was measured based on ASTM-E813-81 by placing a 25-mm-thick three-point bending test piece having a notch with a depth of 12.5 mm on a span with a spacing of 100 mm. . The depth of the notch of this three-point bending test piece is two steps, the depth of the first step is 10 mm, the inner width is 2 mm, and the inner width of the second step is 0.2 mm.
As a result of the measurement, the fracture toughness values K 1C of Examples 1 to 5 are higher than those of Comparative Examples 1 and 2 and the reference example (30 MPa · m 0.5 or more, here, 35 MPa · m 0.5 or more). Met. In addition, the Shore hardness of Examples 1-5 was in the range of 45 or more and 75 or less.
続いて、実施例３と比較例１の試験片を使用し、耐高温酸化特性について検討した結果について説明する。
高温酸化試験を行うに際し、試験片（２５×１２．５×１２．５ｍｍｔ）をアセトンで超音波洗浄し、乾燥した後、その質量を測定して、酸化試験に供した。酸化試験では、大気雰囲気中の電気炉に９００℃で１２時間維持した後、また２４時間維持した後、それぞれアルミナ坩堝を用いて冷却を行った。そして、酸化試験後の試験片と、捕集したスケールの質量を測定し、酸化増量（酸化による重量増加量）を算出した。この結果を、表４に示す。
Then, the result of having examined the high temperature oxidation resistance using the test piece of Example 3 and the comparative example 1 is demonstrated.
When performing the high temperature oxidation test, the test piece (25 × 12.5 × 12.5 mmt) was ultrasonically washed with acetone and dried, and then its mass was measured and subjected to an oxidation test. In the oxidation test, after maintaining in an electric furnace in an air atmosphere at 900 ° C. for 12 hours and again for 24 hours, each was cooled using an alumina crucible. And the mass of the test piece after an oxidation test and the collected scale was measured, and the oxidation increase (weight increase by oxidation) was calculated. The results are shown in Table 4.
表４に示すように、酸化による重量増加量は、９００℃で１２時間と２４時間のいずれも、比較例１が１時間あたり２０ｇ／ｍ２程度であったが、実施例３では、１０ｇ／ｍ２程度まで低減できた（９００℃で２４時間保持した場合の酸化による重量増加量：１時間あたり１６ｇ／ｍ２以下、ここでは、１１ｇ／ｍ２以下）。
以上のことから、実施例３の試験片は、耐高温酸化特性を有することを確認できた。
As shown in Table 4, the weight increase due to oxidation was about 20 g / m 2 per hour in Comparative Example 1 at 900 ° C. for both 12 hours and 24 hours. It could be reduced to about m 2 (weight increase due to oxidation when kept at 900 ° C. for 24 hours: 16 g / m 2 or less per hour, here 11 g / m 2 or less).
From the above, it was confirmed that the test piece of Example 3 had high-temperature oxidation resistance.
次に、耐熱衝撃特性について検討した結果について説明する。
熱衝撃試験を行うに際し、試験片（２５×１２．５×１２．５ｍｍｔ）に対して浸透探傷試験法（ＰＴ検査）を用い、熱き裂の有無を、試験前に事前確認した。そして、所定テスト温度（５００〜８００℃）に保持した大気中の電気炉に投入し、５分間保持した後、予め準備した水槽（５００ｍＬの容器中、水温２５℃±２℃）の中へ投入した（水中焼入れ方式）。
この結果、実施例１〜５のいずれについても、５７０℃以下の温度からの急冷に対し、試験片の表層部にき裂が発生せず、特に実施例１は、８００℃までの温度についてもき裂の発生がなかった。
以上のことから、実施例１〜５の試験片は、耐熱衝撃特性を有することを確認できた。
Next, the results of studying the thermal shock characteristics will be described.
In conducting the thermal shock test, the penetration test method (PT inspection) was used for the test piece (25 × 12.5 × 12.5 mmt), and the presence or absence of a thermal crack was confirmed in advance before the test. Then, it is put into an electric furnace in the atmosphere held at a predetermined test temperature (500 to 800 ° C.), held for 5 minutes, and then put into a previously prepared water tank (water temperature 25 ° C. ± 2 ° C. in a 500 mL container). (In-water quenching method).
As a result, in all of Examples 1 to 5, no cracks occurred in the surface layer portion of the test piece with respect to rapid cooling from a temperature of 570 ° C. or less, and in particular, Example 1 also had a temperature up to 800 ° C. There was no cracking.
From the above, it was confirmed that the test pieces of Examples 1 to 5 had thermal shock resistance characteristics.
続いて、耐熱間摩耗特性について検討した結果について説明する。
熱間摩耗試験を行うに際しては、大気雰囲気のもと６００℃で、Ｓ４５Ｃ製の円盤状（直径１００ｍｍ、厚み１５ｍｍ）の対向材を回転速度１００回／分に設定し、この対向材に、試験片を荷重１０ｋｇで２時間押付け、その摩耗量を測定した。また、同様に、８００℃で、対向材に試験片を１５分間押付け、その摩耗量を測定した。この結果を、前記した表４に示す。
表４に示す６００℃で２時間の試験結果から、実施例３の方が、基地の硬さが高くＭＣ金属炭化物の量が多いため、比較例１より摩耗減量が少ないことが分かった。しかし、８００℃で１５分間の試験結果では、耐高温酸化性や耐高温特性が優れた実施例３の方が摩耗減量が少ないことが分かった。
なお、実施例３は、熱間摩耗量が１ｍｇ程度（８ｍｇ以下）であり、比較例１の試験片と比較して、耐熱間摩耗特性を有することを確認できた。
Then, the result of having examined the wear characteristics during heat resistance will be described.
When performing the hot wear test, an S45C disk-shaped (diameter 100 mm, thickness 15 mm) facing material was set at a rotation speed of 100 times / minute at 600 ° C. in an air atmosphere. The piece was pressed for 2 hours with a load of 10 kg, and the amount of wear was measured. Similarly, the test piece was pressed against the facing material for 15 minutes at 800 ° C., and the amount of wear was measured. The results are shown in Table 4 described above.
From the test results for 2 hours at 600 ° C. shown in Table 4, it was found that Example 3 had less wear loss than Comparative Example 1 because the hardness of the base was higher and the amount of MC metal carbide was larger. However, the test results for 15 minutes at 800 ° C. showed that Example 3 with superior high-temperature oxidation resistance and high-temperature resistance has less wear loss.
In Example 3, the amount of hot wear was about 1 mg (8 mg or less), and compared with the test piece of Comparative Example 1, it was confirmed that it had hot wear characteristics.
最後に、耐疲労き裂伝播特性について検討した結果について説明するが、この評価は、内野、小田、鈴木、橋本、「熱間圧延におけるハイス系白鋳鉄ロールのき裂伝ぱについての解析」：日本機械学会論文集（Ａ編）、７０巻、６９４号（２００４−６）、ｐ８５８−ｐ８６４の内容に基づいているため、その評価方法については、以下簡単に説明する。
疲労き裂伝播試験には、前記した破壊靱性値の３点曲げ試験片を用いた。なお、切欠き先端部は、ワイヤーカット法を用いて、半径０．１ｍｍに加工した。そして、耐疲労き裂伝播特性は、試験片の両側の切欠き前方に、クラックゲージを貼り、き裂長さの変化を測定した。なお、応力比Ｒ（Ｐｍｉｎ／Ｐｍａｘ）＝０．３の片振り条件のもとで、８．３３Ｈｚ（５００ｃｐｍ）の交番曲げモーメントを付加した。
この試験結果を用い、き裂長さａと繰返し数Ｎから疲労き裂伝播速度ｄａ／ｄＮを求め、得られた疲労き裂伝播速度ｄａ／ｄＮと応力拡大係数幅ΔＫＩとの関係を、図３に示す。なお、応力拡大係数幅ΔＫＩは、下限界応力拡大係数ΔＫｔｈより大きい範囲で、Ｐａｒｉｓ−Ｅｒｄｏｇａｎの関係式 ｄａ／ｄＮ＝Ｃ（ΔＫＩ）ｍ が成り立つことが知られている。
Lastly, we will explain the results of a study on fatigue crack propagation characteristics. This evaluation is based on Uchino, Oda, Suzuki, Hashimoto, “Analysis of crack propagation in high-speed white cast iron rolls in hot rolling”: Japan Since it is based on the content of JSME Transactions (A), 70, 694 (2004-6), p858-p864, the evaluation method will be briefly described below.
For the fatigue crack propagation test, the above-mentioned three-point bending specimen having the fracture toughness value was used. In addition, the notch front-end | tip part was processed into the radius of 0.1 mm using the wire cut method. For fatigue crack propagation resistance, a crack gauge was attached in front of the notches on both sides of the test piece, and changes in crack length were measured. Note that an alternating bending moment of 8.33 Hz (500 cpm) was applied under the one-way swing condition of the stress ratio R (P min / P max ) = 0.3.
Using this test result, it can determine the crack length a and the fatigue from the repetitive number N crack propagation rate da / dN, a relationship between the obtained fatigue crack propagation rate da / dN and the stress intensity factor range [Delta] K I, FIG. 3 shows. It is known that the stress intensity factor width ΔK I satisfies the Paris-Erdogan relational expression da / dN = C (ΔK I ) m in a range larger than the lower limit stress intensity factor ΔK th .
図３において、ΔＫＩがある値以上になるとき、き裂が伝播し始め、その速度は、ΔＫＩとの相関関係を示し、ΔＫＩが増加すると共に、伝播速度は大きくなる。
ここで、耐疲労き裂伝播特性の曲線（ｄａ／ｄＮ−ΔＫＩ）から、下限界応力拡大係数ΔＫｔｈを求めた結果、実施例３と比較例２のΔＫｔｈは、それぞれ１７．１ＭＰａ・ｍ０．５、１２．２ＭＰａ・ｍ０．５であった。この下限界応力拡大係数ΔＫｔｈは、初期き裂の発生抵抗値を示しており、この値が大きいほど、疲労寿命が長いといわれている。
また、上限界応力拡大係数を求めた結果、実施例３と比較例２とでは、それぞれ２７ＭＰａ・ｍ０．５、１７．７ＭＰａ・ｍ０．５であった。なお、実施例３の下限界応力拡大係数は、参考例である一般ハイス材の結果（１０．５ＭＰａ・ｍ１／２）より高い値を示した。このとき、疲労き裂伝播速度ｄａ／ｄＮは、８×１０−５以上２×１０−４以下（１０−６以上１０−３以下の範囲内）である。
In FIG. 3, when ΔK I exceeds a certain value, the crack starts to propagate, and its speed shows a correlation with ΔK I, and as ΔK I increases, the propagation speed increases.
Here, from the curve of the fatigue crack propagation properties (da / dN-ΔK I) , the result of obtaining the lower critical stress intensity factor [Delta] K th, [Delta] K th of Comparative Example 2 and Example 3, 17.1MPa · respectively m 0.5 and 12.2 MPa · m 0.5 . This lower limit stress intensity factor ΔK th indicates an initial crack initiation resistance value, and it is said that the larger this value, the longer the fatigue life.
Moreover, results of obtaining the maximum field stress intensity factor, in Comparative Example 2 and Example 3, respectively 27 MPa · m 0.5, was 17.7 MPa · m 0.5. In addition, the lower limit stress intensity factor of Example 3 showed a higher value than the result (10.5 MPa · m 1/2 ) of the general high-speed material as a reference example. At this time, the fatigue crack propagation rate da / dN is 8 × 10 −5 or more and 2 × 10 −4 or less (within a range of 10 −6 or more and 10 −3 or less).
ここで、実施例３の下限界応力拡大係数と上限界応力拡大係数から求められる直線の傾きを表すｍ値は、実施例３が比較例２に比べて２倍以上低いことから、実施例３の疲労き裂伝播速度は非常に遅く、優れた耐疲労き裂伝播特性を有することを確認できた（応力拡大係数幅ΔＫＩ：１６ＭＰａ・ｍ０．５以上２７ＭＰａ・ｍ０．５以下、疲労き裂伝播速度ｄａ／ａＮ：１０−６以上１０−３以下）。
なお、不安定破壊（突発的な脆性破壊）が発生する疲労破壊靱性値については、ＫＩＣｆ＝Ｋｍａｘと定義すれば、実施例の疲労破壊靱性値ＫＩＣｆが３０ＭＰａ・ｍ０．５以上となり、比較例や参考例に比べて高い値を示すことも確認できた。
Here, since the m value representing the slope of the straight line obtained from the lower limit stress intensity factor and the upper limit stress intensity factor of Example 3 is twice or more lower than that of Comparative Example 2, Example 3 It was confirmed that the fatigue crack propagation rate of the steel was very slow and had excellent fatigue crack propagation characteristics (stress intensity factor width ΔK I : 16 MPa · m 0.5 or more and 27 MPa · m 0.5 or less, fatigue Crack propagation speed da / aN: 10 −6 or more and 10 −3 or less).
Note that the fatigue fracture toughness value at which unstable fracture (sudden brittle fracture) occurs is defined as K ICf = K max , the fatigue fracture toughness value K ICf of the example is 30 MPa · m 0.5 or more. It was also confirmed that the values were higher than those of the comparative examples and reference examples.
従って、実施例は、疲労き裂特性因子の全てが、比較例や参考例に比べて優れることを確認できた。
以上のことから、本発明の熱間圧延用複合ロールを使用することで、熱間粗圧延、特に熱疲労き裂に対し、損傷が小さくかつこの種のロールが有する耐摩耗性を適度に有して消耗を少なくできることを確認できた。
Therefore, the Example has confirmed that all the fatigue crack characteristic factors were superior to those of the comparative example and the reference example.
From the above, by using the composite roll for hot rolling according to the present invention, it is suitable for hot rough rolling, particularly against thermal fatigue cracks, and has moderate wear resistance possessed by this type of roll. As a result, it was confirmed that consumption could be reduced.
以上、本発明を、実施の形態を参照して説明してきたが、本発明は何ら上記した実施の形態に記載の構成に限定されるものではなく、特許請求の範囲に記載されている事項の範囲内で考えられるその他の実施の形態や変形例も含むものである。例えば、前記したそれぞれの実施の形態や変形例の一部又は全部を組合せて本発明の熱間圧延用複合ロール及びその製造方法を構成する場合も本発明の権利範囲に含まれる。 The present invention has been described above with reference to the embodiments. However, the present invention is not limited to the configurations described in the above-described embodiments, and the matters described in the claims are not limited. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the composite roll for hot rolling of the present invention and the manufacturing method thereof are configured by combining a part or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
１０：中空式冷却型、１１：冷却緩衝材、１２：組合せモールド、１３：芯材、１４：溶湯、１５：肉盛層、１６：連続鋳掛け肉盛溶接用モールド、１７：電磁誘導加熱コイル、１８：耐火枠、１９：ガラスコーティング層、２０：予熱用の電磁誘導加熱コイル 10: hollow cooling type, 11: cooling buffer material, 12: combination mold, 13: core material, 14: molten metal, 15: overlaying layer, 16: mold for continuous casting overlay welding, 17: electromagnetic induction heating coil, 18: Fireproof frame, 19: Glass coating layer, 20: Electromagnetic induction heating coil for preheating
Claims (9)
前記溶湯は、Ｃ：１．０質量％以上２．０質量％以下、Ｓｉ：０．２質量％以上２．０質量％以下、Ｍｎ：０．２質量％以上２．０質量％以下、Ｖ：４．０質量％以上８．０質量％以下、Ｃｒ：２．０質量％以上５．０質量％以下、Ｍｏ及びＷのいずれか１種又は２種を２．０質量％以上８．０質量％以下、及びＴｉ：０．０５質量％以上０．３０質量％以下含有し、残部がＦｅ及び不可避的不純物元素からなり、
かつ、前記肉盛層に晶出したＭ２Ｃ、Ｍ６Ｃ、及びＭ７Ｃ３のいずれか１種又は２種以上からなる金属炭化物の占有率を３．０面積％以下、及び前記金属炭化物のサイズと前記肉盛層の二次デンドライト組織の結晶粒サイズを、それぞれ５０μｍ以下に微細化したことを特徴とする熱間圧延用複合ロール。 A solid or hollow core material made of steel is inserted concentrically and vertically into a combination mold having a cooling buffer material on the upper inner surface of a metal hollow cooling mold, and an annular gap around the outer periphery of the core material The core material is continuously lowered by pouring the molten metal into the part, and solidified by cooling while welding the molten metal on the outer surface of the core material, and after forming a built-up layer on the outer periphery of the core material, heat treatment And a hot-rolling composite roll manufactured by machining,
The molten metal is C: 1.0 mass% or more and 2.0 mass% or less, Si: 0.2 mass% or more and 2.0 mass% or less, Mn: 0.2 mass% or more and 2.0 mass% or less, V : 4.0% by mass or more and 8.0% by mass or less, Cr: 2.0% by mass or more and 5.0% by mass or less, and any one or two of Mo and W are 2.0% by mass or more and 8.0% by mass. Less than mass%, and Ti: 0.05 mass% or more and 0.30 mass% or less, and the balance consists of Fe and inevitable impurity elements,
And, M 2 C, which crystallized on the cladding layer, M 6 C, and M 7 C 3 of the occupancy of the metal carbide consisting of either one or two or more 3.0 area% or less, and the metal A composite roll for hot rolling, wherein the carbide size and the crystal grain size of the secondary dendrite structure of the build-up layer are each refined to 50 μm or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2008058409A JP4922971B2 (en) | 2008-03-07 | 2008-03-07 | Composite roll for hot rolling and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2008058409A JP4922971B2 (en) | 2008-03-07 | 2008-03-07 | Composite roll for hot rolling and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2009214122A JP2009214122A (en) | 2009-09-24 |
| JP4922971B2 true JP4922971B2 (en) | 2012-04-25 |
Family
ID=41186561
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2008058409A Active JP4922971B2 (en) | 2008-03-07 | 2008-03-07 | Composite roll for hot rolling and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4922971B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102118543B1 (en) | 2015-03-04 | 2020-06-03 | 후지코 가부시키가이샤 | Briquette roller and method for producing same |
| CN106544596B (en) * | 2017-01-19 | 2018-07-13 | 西安工程大学 | A kind of aluminium alloying high-boron high-speed steel composite roller and preparation method thereof |
| CN110343983B (en) * | 2018-04-08 | 2021-09-14 | 南京理工大学 | Preparation method of multi-grain-scale multi-layer magnesium alloy |
Family Cites Families (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5499760A (en) * | 1978-01-24 | 1979-08-06 | Kobe Steel Ltd | Roll for cold rolling |
| JPS6099408A (en) * | 1983-11-04 | 1985-06-03 | Nippon Steel Corp | Rolling roll made of high chrome cast iron |
| JPH0762207B2 (en) | 1989-07-24 | 1995-07-05 | 関東特殊製鋼株式会社 | Forging roll for hot rolling and its manufacturing method |
| US5419973A (en) * | 1990-06-13 | 1995-05-30 | Nippon Steel Corporation | Composite roll for rolling and process for producing the same |
| JP2946129B2 (en) | 1991-07-09 | 1999-09-06 | 新日本製鐵株式会社 | Wear-resistant and heat-resistant crack roll material for hot rolling |
| US5514065A (en) * | 1993-03-31 | 1996-05-07 | Hitachi Metals, Ltd. | Wear- and seizing-resistant roll for hot rolling and method of making the roll |
| JP3104472B2 (en) * | 1993-06-15 | 2000-10-30 | 関東特殊製鋼株式会社 | Roll material for hot rolling |
| JP3222660B2 (en) * | 1993-10-26 | 2001-10-29 | 松下電工株式会社 | Substrate surface treatment method |
| JPH07178535A (en) * | 1993-12-24 | 1995-07-18 | Kubota Corp | Production of composite high speed steel-based rotating member containing graphite |
| JPH08165544A (en) * | 1994-12-13 | 1996-06-25 | Sumitomo Metal Ind Ltd | Roll for hot rolling |
| JP3383180B2 (en) * | 1997-04-08 | 2003-03-04 | 新日本製鐵株式会社 | Composite work roll for high wear resistance cold rolling |
| JP3962838B2 (en) * | 1998-08-03 | 2007-08-22 | 日立金属株式会社 | Hot rolling roll |
| JP3195777B2 (en) * | 1999-03-31 | 2001-08-06 | 虹技株式会社 | Outer layer material of rolling roll |
| JP3927347B2 (en) * | 2000-03-06 | 2007-06-06 | 日鉄住金ロールズ株式会社 | Outer layer material of composite roll for rolling |
| JP3896478B2 (en) * | 2001-04-02 | 2007-03-22 | 株式会社フジコー | Materials for building up and composite tools with excellent corrosion resistance, wear resistance and seizure resistance |
| JP3641597B2 (en) | 2001-05-28 | 2005-04-20 | 新日本製鐵株式会社 | Composite roll for hot rolling and hot rolling method using the same |
| JP2006342422A (en) * | 2005-05-10 | 2006-12-21 | Hitachi Metals Ltd | External layer material for rolling roll, and rolling roll |
-
2008
- 2008-03-07 JP JP2008058409A patent/JP4922971B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2009214122A (en) | 2009-09-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4725216B2 (en) | Low alloy steel for oil well pipes with excellent resistance to sulfide stress cracking | |
| TWI712697B (en) | Outer layer for roll and composite roll for roll | |
| JP7400718B2 (en) | Centrifugal casting composite roll for rolling and its manufacturing method | |
| JP6474038B2 (en) | Composite roll for continuous casting and overlay casting | |
| CN112760561B (en) | Wire rod for hand tool and preparation method thereof | |
| EP0533929A1 (en) | Composite roll for use in rolling and manufacture thereof | |
| WO1998045493A1 (en) | Composite work roll for cold rolling | |
| JP6516093B2 (en) | Composite roll for continuous cast overlay casting rolling | |
| JP6515957B2 (en) | Roll outer layer material for rolling having excellent wear resistance and composite roll for rolling | |
| JP4922971B2 (en) | Composite roll for hot rolling and manufacturing method thereof | |
| JP3755396B2 (en) | Hot roll outer layer material and centrifugal cast hot roll composite roll with excellent crack resistance | |
| JP3581028B2 (en) | Hot work tool steel and high temperature members made of the hot work tool steel | |
| EP2660344A1 (en) | Centrifugally cast roll for last finishing stands in hot strip mills | |
| JP2015080813A (en) | Composite rolling-roll made by centrifugal casting | |
| JP4123903B2 (en) | Hot roll outer layer material and hot roll composite roll | |
| JP4196501B2 (en) | Steel for seamless steel pipe with high strength and excellent toughness | |
| JP2006297427A (en) | Method for manufacturing forged sleeve roll for rolling wide flange shape | |
| JP4223442B2 (en) | Steel for plastic molds with excellent texture and machinability | |
| JP6518314B2 (en) | Composite roll for rolling | |
| JP4596312B2 (en) | Outer layer material for rolling roll excellent in wear resistance and heat crack resistance and rolling roll using the same | |
| JPH08209299A (en) | High seizing resistant roll material for hot rolling and its production | |
| JP6866958B2 (en) | Roll for hot rolling Outer layer material and composite roll for hot rolling | |
| JP3030077B2 (en) | Abrasion-resistant composite roll excellent in crack resistance and method for producing the same | |
| JP4650737B2 (en) | Composite roll for rolling | |
| JP4650735B2 (en) | Composite roll for rolling |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20100407 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20111209 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20120110 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20120206 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 4922971 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20150210 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20150210 Year of fee payment: 3 |
|
| R157 | Certificate of patent or utility model (correction) |
Free format text: JAPANESE INTERMEDIATE CODE: R157 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R157 | Certificate of patent or utility model (correction) |
Free format text: JAPANESE INTERMEDIATE CODE: R157 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |