JP6191697B2 - Steel cooling method, steel manufacturing method, steel cooling equipment and steel manufacturing equipment - Google Patents
Steel cooling method, steel manufacturing method, steel cooling equipment and steel manufacturing equipment Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims description 181
- 239000010959 steel Substances 0.000 title claims description 181
- 238000001816 cooling Methods 0.000 title claims description 87
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 239000000463 material Substances 0.000 claims description 169
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 71
- 238000000034 method Methods 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000007598 dipping method Methods 0.000 claims description 4
- 238000007654 immersion Methods 0.000 description 18
- 238000010791 quenching Methods 0.000 description 10
- 230000000171 quenching effect Effects 0.000 description 10
- 238000010586 diagram Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 239000013077 target material Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/62—Quenching devices
- C21D1/63—Quenching devices for bath quenching
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- Organic Chemistry (AREA)
- Heat Treatments In General, Especially Conveying And Cooling (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Description
本発明は、鋼材の冷却方法、鋼材の製造方法、鋼材冷却設備および鋼材製造設備に関するものである。 The present invention relates to a steel material cooling method, a steel material manufacturing method, a steel material cooling facility, and a steel material manufacturing facility.
厚鋼板など肉厚の厚い鋼材の製造において、多量の合金成分の添加を行わずに高強度および高靭性を得るためには、一般的に、オフラインでローラークエンチする方法で焼入れ処理を行う。しかしながら、例えば、板厚が100mmを超えるような鋼材の場合、テーブルローラーが撓むなど、搬送の問題が生じる。そこでこのような厚物鋼材の場合、水中に浸漬させて冷却する方法で焼入れ処理を行っている。 In producing a thick steel material such as a thick steel plate, in order to obtain high strength and high toughness without adding a large amount of alloy components, quenching is generally performed by a method of roller quenching offline. However, for example, in the case of a steel material having a plate thickness exceeding 100 mm, a conveyance problem such as bending of the table roller occurs. Therefore, in the case of such a thick steel material, the quenching treatment is performed by a method of immersing in water and cooling.
水中に浸漬させて冷却する鋼材の焼入れ処理(以下、単に浸漬冷却と称することもある。)は、図1または図2に示すような設備において、鋼材1を台車2付きの加熱炉3で加熱した後、クレーンなどの吊り具4で鋼材1を吊って、水5で満たされた水槽6内に鋼材の広面部長辺方向が垂直または水平になるようにして浸漬させて行う。焼入れ中の冷却速度を速くするほど、高強度で高靭性の材質の鋼材が得られる。
The quenching treatment of steel material that is immersed and cooled in water (hereinafter sometimes simply referred to as immersion cooling) is performed by heating the
水中に浸漬させて鋼材を冷却する方法として、特許文献1の技術がある。特許文献1は、鋼片広面が側面となるように水中に垂直方向に浸漬させ、鋼片両面から水噴射を行うことを特徴とする鋼片の水冷方法であり、鋼片の急速かつ均一な冷却を図るものである。
As a method for cooling a steel material by immersing it in water, there is a technique of
しかしながら、特許文献1の方法のように、加熱炉から抽出した鋼材の広面部を垂直にして浸漬させる場合、図3に示すように、板長が長い鋼材では、自重によって吊上げ時に鋼材1が変形するという問題がある。例えば、板厚150mm、板長13mの場合は、吊上げ時に変形して全長で500mm程度の反りが生じてしまう。
However, when the wide surface portion of the steel material extracted from the heating furnace is immersed vertically as in the method of
また、加熱炉から抽出した鋼材の広面部を水平にして水に浸漬させる場合、図4に示すように、鋼材1の上面に発生する蒸気泡7は、滞留せずに矢印の方向に移動する。しかしながら、鋼材1の下面では、発生した蒸気泡7が滞留して蒸気膜8が形成されると、鋼材下面と水とが直接接触しなくなるため、熱伝達が阻害される。したがって、鋼材1の上面と比較して下面は冷えにくくなり、平均冷却速度の低下や上下面の冷却不均一が起こる。その結果、強度や靭性の低下、冷却中に反りが生じるという問題がある。例えば、板厚150mmの鋼材の広面部を水平にして浸漬させた時、上下面の温度履歴は図5のようになり、鋼材の下面温度が上面温度に比べて最大350℃高くなる。
Moreover, when the wide surface part of the steel material extracted from the heating furnace is leveled and immersed in water, the steam bubbles 7 generated on the upper surface of the
このため、加熱炉から抽出した鋼材の広面部を水平にして水に浸漬させる場合、鋼材上下面の冷却を均一にするためには、水噴流などの冷却装置を用いて下面の冷却を促進する必要がある。しかしながら、例えば、板幅2m、板長10m以上の鋼材の焼入れ処理を行う場合、多数のノズル設置や多量の冷却水が必要となり、設備コストおよびランニングコストがかかる。さらに、ノズル配置によって冷却むらができてしまうという問題もある。 For this reason, when the wide surface portion of the steel material extracted from the heating furnace is leveled and immersed in water, the cooling of the lower surface is promoted by using a cooling device such as a water jet in order to make the upper and lower surfaces of the steel material uniform. There is a need. However, for example, when quenching a steel material having a plate width of 2 m and a plate length of 10 m or more, a large number of nozzles are installed and a large amount of cooling water is required, resulting in equipment costs and running costs. Further, there is a problem that uneven cooling is caused by the nozzle arrangement.
本発明は、上記実情に鑑みてなされたものであって、鋼材下面の冷却を促進させ、高強度および高靭性の材質を得られるうえに、冷却中に反りの生じない鋼材の冷却方法を提供することを目的とする。 The present invention has been made in view of the above circumstances, and provides a method for cooling a steel material that promotes cooling of the lower surface of the steel material to obtain a high-strength and high-toughness material and that does not warp during cooling. The purpose is to do.
本発明は、前記した従来の問題点を解決するためになされたものであって、その手段は下記のとおりである。
[1]鋼材の広面部を上下面として、鋼材の広面部短辺方向の水平面からの傾斜角度を15°以上45°以下になるように、鋼材を鋼材体積の20倍以上の水を蓄えた水槽内に浸漬することを特徴とする鋼材の冷却方法。
[2]鋼材の広面部を上下面として、鋼材の広面部短辺方向の水平面からの傾斜角度を15°以上75°以下になるように、鋼材を鋼材体積の20倍以上の水を蓄えた水槽内に浸漬することを特徴とする鋼材の冷却方法。
[3]鋼材を加熱する工程と、加熱された鋼材の広面部を上下面として、鋼材の広面部短辺方向の水平面からの傾斜角度を15°以上45°以下になるように、鋼材を鋼材体積の20倍以上の水を蓄えた水槽内に浸漬する工程とを有することを特徴とする鋼材の製造方法。
[4]鋼材を加熱する工程と、加熱された鋼材の広面部を上下面として、鋼材の広面部短辺方向の水平面からの傾斜角度を15°以上75°以下になるように、鋼材を鋼材体積の20倍以上の水を蓄えた水槽内に浸漬する工程とを有することを特徴とする鋼材の製造方法。
[5]鋼材体積の20倍以上の水を蓄えた水槽と、前記鋼材の広面部短辺方向の水平面からの傾斜角度を15°以上45°以下になるように、前記鋼材を前記水槽内に保持する浸漬部材とを備えることを特徴とする鋼材冷却設備。
[6]鋼材体積の20倍以上の水を蓄えた水槽と、前記鋼材の広面部短辺方向の水平面からの傾斜角度を15°以上75°以下になるように、前記鋼材を前記水槽内に保持する浸漬部材とを備えることを特徴とする鋼材冷却設備。
[7][5]または[6]に記載の鋼材冷却設備を有することを特徴とする鋼材製造設備。The present invention has been made to solve the above-described conventional problems, and the means thereof is as follows.
[1] The steel material was stored with water more than 20 times the steel material volume so that the wide surface portion of the steel material was the upper and lower surfaces, and the inclination angle from the horizontal plane in the short side direction of the steel material was 15 ° to 45 °. A method for cooling a steel material, wherein the method is immersed in a water tank.
[2] With the wide surface portion of the steel material as the upper and lower surfaces, the steel material was stored with water more than 20 times the volume of the steel material so that the inclination angle from the horizontal plane in the short side direction of the steel material was 15 ° or more and 75 ° or less. A method for cooling a steel material, wherein the method is immersed in a water tank.
[3] The step of heating the steel material and the steel material so that the inclined angle from the horizontal surface in the short side direction of the wide surface portion of the steel material is 15 ° or more and 45 ° or less with the wide surface portion of the heated steel material as the upper and lower surfaces. And a step of immersing in a water tank storing water of 20 times or more in volume.
[4] The step of heating the steel material and the steel material so that the inclined angle from the horizontal plane in the short side direction of the wide surface portion of the steel material is 15 ° or more and 75 ° or less with the wide surface portion of the heated steel material as the upper and lower surfaces. And a step of immersing in a water tank storing water of 20 times or more in volume.
[5] The steel material is stored in the water tank so that an inclination angle from a horizontal surface in the short side direction of the wide surface portion of the steel material is 15 ° or more and 45 ° or less, with water stored 20 times or more of the steel material volume. A steel material cooling facility comprising a dipping member to be held.
[6] The steel material is stored in the water tank so that an angle of inclination from a horizontal surface in the short side direction of the wide surface portion of the steel material is 15 ° or more and 75 ° or less, with water stored 20 times or more of the steel material volume. A steel material cooling facility comprising a dipping member to be held.
[7] A steel material production facility comprising the steel material cooling facility according to [5] or [6].
本発明によれば、鋼材下面の冷却を促進させることができる。その結果、鋼材全面を均一に冷却することができるため、冷却中に反りの生じない、高強度および高靭性の材質の鋼材を製造することができる。また、本発明では、鋼材の広面部を垂直にして浸漬させる必要がないため、吊り上げ時に鋼材が変形するという問題もない。 According to the present invention, cooling of the lower surface of the steel material can be promoted. As a result, the entire surface of the steel material can be uniformly cooled, so that it is possible to manufacture a steel material of high strength and high toughness that does not warp during cooling. Further, in the present invention, since it is not necessary to immerse the wide surface portion of the steel material vertically, there is no problem that the steel material is deformed when it is lifted.
以下、本発明について説明する。 The present invention will be described below.
本発明の鋼材の冷却方法は、鋼材の広面部を上下面として、鋼材の広面部短辺方向の水平面からの傾斜角度を15°以上45°以下になるように水中に浸漬することを特徴とする。 The steel material cooling method according to the present invention is characterized in that the wide surface portion of the steel material is used as upper and lower surfaces, and the steel material is immersed in water so that the inclination angle from the horizontal surface in the short side direction of the steel material is 15 ° to 45 °. To do.
浸漬冷却中、鋼材1の下面で発生する蒸気泡7は、浮力によって鉛直方向上向きに上昇しようとする。鋼材1の広面部を上下面として、鋼材1を傾斜させた状態で浸漬すると、図6に示すように、鋼材1の下面で発生した蒸気泡7は、浮力により、滞留することなく鋼材1の下面に沿って、鋼材1の傾斜方向上端部に向かって移動する。さらに、蒸気泡7の上昇に伴い、冷却水の対流が発生する(図6の破線矢印)。このため、下面に発生する蒸気膜が消失し、下面の冷却が促進される。したがって、鋼材1の下面において、蒸気膜8が形成されにくい。そして、蒸気膜8に起因した熱伝達の阻害が起こらず、平均冷却速度の低下や上下面の冷却不均一が生じない。その結果、鋼材1の下面の冷却が促進され、浸漬冷却中の反りが起こらず、高強度および高靭性の材質の鋼材を製造することができる。
During the immersion cooling, the vapor bubbles 7 generated on the lower surface of the
本発明では、鋼材の広面部短辺方向の傾斜角度を15°以上とする。鋼材の広面部短辺方向の傾斜角度、すなわち、水平面からの傾斜角度が15°未満で浸漬冷却すると、鋼材下面に沿って上昇する蒸気泡の速度が遅く、蒸気膜の形成を十分に抑制することができない。また、十分な対流効果を得られない。このため、鋼材下面の冷却が促進されず、高強度および高靭性の材質の鋼材を得ることができないうえに、浸漬冷却中に鋼材反りが生じてしまう。なお、上下面冷却均一性の観点から、傾斜角度は、30°以上であることが好ましい。 In the present invention, the inclination angle in the short side direction of the wide surface portion of the steel material is set to 15 ° or more. When immersion cooling is performed at an inclination angle in the short side direction of the wide surface portion of the steel material, that is, an inclination angle from the horizontal plane of less than 15 °, the speed of the vapor bubbles rising along the lower surface of the steel material is slow, and the formation of the vapor film is sufficiently suppressed. I can't. Moreover, sufficient convection effect cannot be obtained. For this reason, the cooling of the lower surface of the steel material is not promoted, and a steel material having a high strength and a high toughness cannot be obtained. Further, the steel material warpage occurs during the immersion cooling. In addition, from the viewpoint of upper and lower surface cooling uniformity, the inclination angle is preferably 30 ° or more.
傾斜角度は、75°以下であればよい。これは、後述するように本発明においては鋼材の広面部短辺方向に傾斜させるため、仮に傾斜角度が75°であっても、鋼材浸漬時の鋼材傾斜方向下端部から上端部までの長さが、鋼材浸漬時の上下方向を鋼材長手方向とする従来方法に比べて短くなり、水槽の深さも浅くすることができるからである。 The inclination angle may be 75 ° or less. As will be described later, in order to incline in the short side direction of the wide surface portion of the steel material in the present invention, even if the inclination angle is 75 °, the length from the lower end portion to the upper end portion in the steel material inclination direction when the steel material is immersed. However, it is because it becomes shorter compared with the conventional method which makes the up-down direction at the time of steel material immersion the steel material longitudinal direction, and the depth of a water tank can also be made shallow.
なお、鋼材の傾斜角度が大きいほど、鋼材下面に沿って上昇する蒸気泡の速度は大きくなる。しかしながら、鋼材の傾斜角度が大きいほど、浸漬時の鋼材高さが高くなり、水槽を深くする必要がある。また、鋼材の傾斜角度が大きいほど、鋼材を傾斜させるための装置が大掛かりとなるため、設備コストがかかる。したがって、傾斜角度の上限を75°とする。傾斜角度は小さいほうが好ましく、具体的には、65°以下が好ましく、55°以下がさらに好ましく、45°以下がいっそう好ましい。 In addition, the speed | rate of the vapor bubble which rises along a steel material lower surface becomes large, so that the inclination-angle of steel materials is large. However, the greater the inclination angle of the steel material, the higher the steel material height during immersion, and the deeper the water tank needs to be. Moreover, since the apparatus for inclining steel materials becomes large, so that the inclination-angle of steel materials is large, installation cost starts. Therefore, the upper limit of the tilt angle is 75 °. The inclination angle is preferably small, specifically, 65 ° or less is preferable, 55 ° or less is more preferable, and 45 ° or less is even more preferable.
鋼材の傾斜方向については、鋼材の広面部を上下面として、鋼材の広面部短辺方向に傾斜させる。短辺方向に傾斜させることにより、鋼材浸漬時の鋼材傾斜方向下端部から上端部までの高さが短くなり、水槽深さを浅くすることができる。例えば、鋼材広面部が、短辺3m×長辺10mの長方形である鋼材を、傾斜角度30°に傾斜させて浸漬冷却させる場合、短辺方向に傾斜させると浸漬時の鋼材高さは1.5mとなる。これに対して、長辺方向に傾斜させると5mとなるため、水槽が大きくなり設備コストが膨大となる。さらに、本発明では、鋼材の広面部を垂直にして浸漬させる必要がないため、吊上げ時に自重により鋼材が変形するという問題がない。したがって、板長の長い鋼材も問題なく製造できる。 About the inclination direction of steel materials, it is made to incline in the wide side part short side direction of steel materials by making the wide surface part of steel materials into an up-and-down surface. By inclining in the short side direction, the height from the lower end portion to the upper end portion in the steel material inclination direction during immersion of the steel material is shortened, and the water tank depth can be reduced. For example, in the case where a steel material having a rectangular wide surface portion having a short side of 3 m × long side of 10 m is immersed and cooled at an inclination angle of 30 °, the steel material height at the time of immersion is 1. 5m. On the other hand, since it will be 5 m if it inclines in a long side direction, a water tank will become large and installation cost will become enormous. Furthermore, in the present invention, since it is not necessary to immerse the wide surface portion of the steel material vertically, there is no problem that the steel material is deformed by its own weight at the time of lifting. Therefore, a steel material having a long plate length can be produced without any problem.
鋼材の冷却設備としては、鋼材体積の20倍以上の水を蓄えた水槽内で冷却する。鋼材体積の20倍以上の水を蓄えた水槽内で冷却することにより、冷却中に水槽内の水温が上昇して冷却能力が低下することがなくなり、その結果、高強度および高靭性の材質の鋼材をより安定的に確保することができる。水槽内の水が鋼材体積の20倍未満である場合、冷却中に水槽内の水温が上昇して冷却能力が低下し、強度および靭性が低下してしまう。なお、水温上昇抑制の点から、50倍以上の水が好ましい。また、水槽内の水の量の上限は特に規定されない。しかし、水槽内の水が鋼材体積の300倍を超えると、冷却能力を安定的に確保する効果が飽和するので、300倍以下であることが好ましい。 As a cooling equipment for steel materials, cooling is performed in a water tank storing water of 20 times or more the steel material volume. By cooling in a water tank that has stored water more than 20 times the volume of the steel material, the water temperature in the water tank will not rise during cooling and the cooling capacity will not be reduced. As a result, the material of high strength and high toughness A steel material can be secured more stably. When the water in the water tank is less than 20 times the volume of the steel material, the water temperature in the water tank rises during cooling, the cooling capacity decreases, and the strength and toughness decrease. In addition, 50 times or more of water is preferable from the viewpoint of suppression of water temperature rise. Moreover, the upper limit of the amount of water in the water tank is not particularly defined. However, when the water in the water tank exceeds 300 times the volume of the steel material, the effect of stably securing the cooling capacity is saturated, and therefore it is preferably 300 times or less.
また、鋼材の冷却設備における水槽内では、鋼材の広面部短辺方向の傾斜角度を15°以上に保持するために、例えば、浸漬具を用いることができる。浸漬具としては、鋼材の広面部短辺方向の傾斜角度を15°以上に保持することができる浸漬具であればよい。例えば、図7のような傾斜架台9、図8のようなCフック10、図9のような浸漬装置11等が挙げられる。なお、図7の傾斜架台9は安価に製造できる。その一方で、図8のCフック10や、図9の浸漬装置11は設備コストがかかる。このため、本発明では、図7のような傾斜架台9が好ましい。
Moreover, in the water tank in the steel material cooling facility, for example, an immersion tool can be used in order to maintain the inclination angle of the wide surface portion short side direction of the steel material at 15 ° or more. The immersion tool may be any immersion tool that can maintain the inclination angle of the wide surface portion short side direction of the steel material at 15 ° or more. For example, an
鋼材の焼入れ処理に際して、本発明の冷却方法を用いる場合には、冷却開始前の鋼材の温度を、鋼材全体の組織が十分にオーステナイト化される温度に加熱することが好ましい。これにより、その後の浸漬冷却によって十分に焼きが入り、均一な材質の鋼材が得られる。また、鋼材温度が1150℃超えでは、加熱中にオーステナイト粒が粗大化し、最終的な鋼組織も粗大化し、靭性が低くなってしまい、材質が確保できない可能性がある。このため、鋼材温度は1150℃以下とすることが好ましい。また、冷却停止温度としては、焼入れ処理が十分に完了すればよく、例えば、100℃以下であればよい。 When using the cooling method of the present invention at the time of quenching the steel material, it is preferable to heat the temperature of the steel material before the start of cooling to a temperature at which the entire structure of the steel material is sufficiently austenitized. As a result, the steel is sufficiently fired by subsequent immersion cooling, and a steel material of a uniform material is obtained. On the other hand, if the steel material temperature exceeds 1150 ° C., the austenite grains coarsen during heating, the final steel structure also coarsens, the toughness becomes low, and the material may not be secured. For this reason, it is preferable that steel material temperature shall be 1150 degrees C or less. Moreover, as a cooling stop temperature, a quenching process should just be completed sufficiently, for example, should just be 100 degrees C or less.
なお、本発明の冷却方法は厚板の熱処理工程で用いれば大きな効果を発揮する。本発明はこれに限るものではなく、鍛造品などの鋼材全般の熱処理工程に適用できる。本発明の冷却方法を用いることにより、冷却中に反りの生じない、高強度および高靭性の材質の鋼材を製造することができる。 Note that the cooling method of the present invention exerts a great effect when used in the heat treatment step of the thick plate. The present invention is not limited to this, and can be applied to a heat treatment process for general steel materials such as forged products. By using the cooling method of the present invention, it is possible to produce a steel material of high strength and high toughness that does not warp during cooling.
以下、本発明の実施例について説明する。 Examples of the present invention will be described below.
図2に示すような、台車付き加熱炉を有する冷却設備を用いて、重量25トン、板厚(t)150mmの鋼材1を900℃まで再加熱した後、台車2によって鋼材1を加熱炉3から抽出し、Cフッククレーンで鋼材1を吊り上げた。水槽6上方に鋼材1を移動させて、鋼材の広面部短辺方向に水平面から10°、15°、30°、45°、75°のいずれかの傾斜角度で傾斜させた状態で浸漬させて、冷却停止温度が100℃以下になるまで鋼材1を冷却した。
The
800℃から400℃の間の平均冷却速度の値に基づき、鋼材の評価を行った。すなわち、本実施例で用いた鋼において目標とする材質(強度・靭性)の鋼材を確保するためには、板厚方向上面(1/4t)および板厚方向下面(3/4t)において、それぞれ平均冷却速度を1.1℃/s以上にする必要があり、また、板厚中心(1/2t)においては、平均冷却速度を0.9℃/s以上にする必要がある。また、冷却中の反りを抑制するためには、板厚方向上面と板厚方向下面との平均冷却速度の差(絶対値)を、板厚方向上面の平均冷却速度の10%以内にする必要がある。ここで、板厚方向上面(1/4t)部の温度は、上面から板厚1/4t部まで穴を開けて取り付けた熱電対により、測定した。板厚方向下面(3/4t)部の温度は、上面から板厚3/4t部まで穴を開けて取り付けた熱電対により、測定した。板厚中心(1/2t)部の温度は、上面から板厚中心(1/2t)部まで穴を開けて取り付けた熱電対により、測定した。800℃から400℃まで各温度を測定し、温度降下量と時間とから、平均冷却速度を算出した。
The steel material was evaluated based on the average cooling rate value between 800 ° C and 400 ° C. That is, in order to secure a steel material of a target material (strength / toughness) in the steel used in this example, on the plate thickness direction upper surface (1/4 t) and the plate thickness direction lower surface (3/4 t), respectively. The average cooling rate needs to be 1.1 ° C./s or more, and the average cooling rate needs to be 0.9 ° C./s or more at the plate thickness center (1 / 2t). In order to suppress warpage during cooling, the difference (absolute value) in the average cooling rate between the upper surface in the thickness direction and the lower surface in the thickness direction must be within 10% of the average cooling rate in the upper surface in the thickness direction. There is. Here, the temperature of the plate thickness direction upper surface (1/4 t) portion was measured by a thermocouple attached by opening a hole from the upper surface to the
各条件および平均冷却速度を表1に示す。 Each condition and average cooling rate are shown in Table 1.
発明例1では、鋼材の広面部短辺方向に水平面から15°傾斜させた状態で、鋼材体積の80倍の水を蓄えた水槽に浸漬させて、全ての部分が100℃以下になるまで冷却して製造した。平均冷却速度は、板厚方向1/4tで1.15℃/s、3/4t位置で1.10℃/s、板厚中心で0.90℃/sとなった。また、板厚方向上面と板厚方向下面との平均冷却速度の差は0.05となり、板厚方向上面の平均冷却速度の10%以内(0.115℃/s以内)を満足した。 In Invention Example 1, the steel plate is immersed in a water tank in which 80 times the volume of the steel material is stored while being inclined at 15 ° from the horizontal plane in the short side direction of the wide surface portion of the steel material, and is cooled until all the portions become 100 ° C. or less. And manufactured. The average cooling rate was 1.15 ° C./s at 1/4 t in the plate thickness direction, 1.10 ° C./s at the 3/4 t position, and 0.90 ° C./s at the center of the plate thickness. The difference in average cooling rate between the upper surface in the plate thickness direction and the lower surface in the plate thickness direction was 0.05, which was within 10% (within 0.115 ° C./s) of the average cooling rate on the upper surface in the plate thickness direction.
発明例2では、鋼材の広面部短辺方向に水平面から30°傾斜させた状態で、鋼材体積の80倍の水を蓄えた水槽に浸漬させて、全ての部分が100℃以下になるまで冷却して製造した。平均冷却速度は、板厚方向1/4tで1.15℃/s、3/4t位置で1.15℃/s、板厚中心で0.92℃/sとなった。また、板厚方向上面と板厚方向下面との平均冷却速度の差は0.00となり、板厚方向上面の平均冷却速度の10%以内(0.115℃/s以内)を満足した。 In Invention Example 2, in a state where the steel is inclined 30 ° from the horizontal plane in the short side direction of the wide surface portion, the steel material is immersed in a water tank storing water 80 times the volume of the steel material, and cooled until all portions become 100 ° C. or less. And manufactured. The average cooling rate was 1.15 ° C./s at 1/4 t in the plate thickness direction, 1.15 ° C./s at the 3/4 t position, and 0.92 ° C./s at the center of the plate thickness. The difference in average cooling rate between the upper surface in the plate thickness direction and the lower surface in the plate thickness direction was 0.00, which was within 10% (within 0.115 ° C./s) of the average cooling rate on the upper surface in the plate thickness direction.
発明例3では、鋼材の広面部短辺方向に水平面から15°傾斜させた状態で、鋼材体積の20倍の水を蓄えた水槽に浸漬させて、全ての部分が100℃以下になるまで冷却して製造した。平均冷却速度は、板厚方向1/4tで1.15℃/s、3/4t位置で1.10℃/s、板厚中心で0.90℃/sとなった。また、板厚方向上面と板厚方向下面との平均冷却速度の差は0.05となり、板厚方向上面の平均冷却速度の10%以内(0.115℃/s以内)を満足した。 In invention example 3, in the state which inclined 15 degrees from the horizontal surface in the wide-surface part short side direction of steel materials, it was immersed in the water tank which stored 20 times the water of steel materials volume, and it cooled until all parts became 100 degrees C or less. And manufactured. The average cooling rate was 1.15 ° C./s at 1/4 t in the plate thickness direction, 1.10 ° C./s at the 3/4 t position, and 0.90 ° C./s at the center of the plate thickness. The difference in average cooling rate between the upper surface in the plate thickness direction and the lower surface in the plate thickness direction was 0.05, which was within 10% (within 0.115 ° C./s) of the average cooling rate on the upper surface in the plate thickness direction.
発明例4では、鋼材の広面部短辺方向に水平面から45°傾斜させた状態で、鋼材体積の80倍の水を蓄えた水槽に浸漬させて、全ての部分が100℃以下になるまで冷却して製造した。平均冷却速度は、板厚方向1/4tで1.15℃/s、3/4t位置で1.18℃/s、板厚中心で0.93℃/sとなった。また、板厚方向上面と板厚方向下面との平均冷却速度の差は0.03となり、板厚方向上面の平均冷却速度の10%以内(0.115℃/s以内)を満足した。 In Invention Example 4, in a state where the wide surface portion of the steel material is inclined by 45 ° from the horizontal surface in the direction of the short side, the steel material is immersed in a water tank storing 80 times the volume of the steel material and cooled until all portions become 100 ° C. or less. And manufactured. The average cooling rate was 1.15 ° C./s at 1/4 t in the plate thickness direction, 1.18 ° C./s at the 3/4 t position, and 0.93 ° C./s at the plate thickness center. The difference in average cooling rate between the upper surface in the plate thickness direction and the lower surface in the plate thickness direction was 0.03, which was within 10% (within 0.115 ° C./s) of the average cooling rate on the upper surface in the plate thickness direction.
発明例5では、鋼材の広面部短辺方向に水平面から75°傾斜させた状態で、鋼材体積の80倍の水を蓄えた水槽に浸漬させて、全ての部分が100℃以下になるまで冷却して製造した。平均冷却速度は、板厚方向1/4tで1.15℃/s、3/4t位置で1.20℃/s、板厚中心で0.94℃/sとなった。また、板厚方向上面と板厚方向下面との平均冷却速度の差は0.05となり、板厚方向上面の平均冷却速度の10%以内(0.115℃/s以内)を満足した。
比較例1では、鋼材の広面部短辺方向に水平面から10°傾斜させた状態で、鋼材体積の80倍の水を蓄えた水槽に浸漬させて、全ての部分が100℃以下になるまで冷却して製造した。平均冷却速度は板厚方向1/4t位置で1.15℃/s、3/4t位置で1.00℃/s、板厚中心で0.86℃/sとなった。これは、水平面からの傾斜角度が10°では、蒸気泡の上昇速度が遅いため、下面の冷却が促進されず均一に冷却されなかったためと考えられる。また、板厚方向上面と板厚方向下面との平均冷却速度の差は0.15となり、板厚方向上面の平均冷却速度の10%以内(0.115℃/s以内)を満足しなかった。In Invention Example 5, in a state where the wide surface portion of the steel material is inclined by 75 ° from the horizontal plane in a short side direction, the steel material is immersed in a water tank storing 80 times as much water as the steel material volume, and cooled until all portions become 100 ° C. or less. And manufactured. The average cooling rate was 1.15 ° C./s at 1/4 t in the plate thickness direction, 1.20 ° C./s at the 3/4 t position, and 0.94 ° C./s at the plate thickness center. The difference in average cooling rate between the upper surface in the plate thickness direction and the lower surface in the plate thickness direction was 0.05, which was within 10% (within 0.115 ° C./s) of the average cooling rate on the upper surface in the plate thickness direction.
In Comparative Example 1, the steel plate was immersed in a water tank in which water of 80 times the volume of the steel material was stored while being tilted by 10 ° from the horizontal plane in the short side direction of the wide surface portion of the steel material, and cooled until all portions were 100 ° C. or less. And manufactured. The average cooling rate was 1.15 ° C./s at the 1/4 t position in the plate thickness direction, 1.00 ° C./s at the 3/4 t position, and 0.86 ° C./s at the plate thickness center. This is considered to be because when the inclination angle from the horizontal plane is 10 °, the rising speed of the steam bubbles is slow, so that the cooling of the lower surface is not promoted and is not uniformly cooled. Further, the difference in average cooling rate between the upper surface in the plate thickness direction and the lower surface in the plate thickness direction was 0.15, and did not satisfy within 10% (within 0.115 ° C./s) of the average cooling rate on the upper surface in the plate thickness direction. .
比較例2では、鋼材の広面部短辺方向に水平面から15°傾斜させた状態で、鋼材体積の15倍の水を蓄えた水槽に浸漬させて、全ての部分が100℃以下になるまで冷却して製造した。平均冷却速度は板厚方向1/4t位置で1.00℃/s、3/4t位置で0.95℃/s、板厚中心で0.78℃/sとなった。これは、水槽中の水量が少ないため、冷却中に水槽内の水温が上昇して冷却能力が低下してしまったためと考えられる。 In Comparative Example 2, the steel material was immersed in a water tank in which 15 times the steel material volume was stored in a state where the steel material was tilted 15 ° from the horizontal plane in the direction of the short side of the wide surface portion, and cooled until all portions were 100 ° C. or lower. And manufactured. The average cooling rate was 1.00 ° C./s at the 1/4 t position in the plate thickness direction, 0.95 ° C./s at the 3/4 t position, and 0.78 ° C./s at the plate thickness center. This is probably because the amount of water in the aquarium is small, so that the water temperature in the aquarium rises during cooling and the cooling capacity decreases.
1 鋼材
2 台車
3 加熱炉
4 吊り具
5 水
6 水槽
7 蒸気泡
8 蒸気膜
9 傾斜架台
10 Cフック
11 浸漬装置DESCRIPTION OF
Claims (4)
加熱された鋼材の広面部を上下面として、鋼材の広面部短辺方向の水平面からの傾斜角度を30°以上45°以下になるように、鋼材を鋼材体積の20倍以上の水を蓄えた水槽内に浸漬する工程と
を有することを特徴とする鋼材の製造方法。 Heating the steel material with a plate thickness exceeding 100 mm;
With the wide surface portion of the heated steel material as the upper and lower surfaces, the steel material was stored with water more than 20 times the steel material volume so that the inclination angle from the horizontal surface in the short side direction of the steel material was 30 ° or more and 45 ° or less. And a step of immersing in a water tank.
前記鋼材の広面部短辺方向の水平面からの傾斜角度を30°以上45°以下になるように、前記鋼材を前記水槽内に保持する浸漬部材と
を備えることを特徴とする鋼材冷却設備。 A water tank storing water more than 20 times the steel material volume of a steel material having a plate thickness exceeding 100 mm;
A steel material cooling facility comprising: a dipping member that holds the steel material in the water tank so that an inclination angle of the steel material from a horizontal plane in the short side direction of the wide surface portion is 30 ° or more and 45 ° or less.
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