JP2021171768A - Crystal grain refining determination method from cooling curve - Google Patents

Crystal grain refining determination method from cooling curve Download PDF

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JP2021171768A
JP2021171768A JP2020074733A JP2020074733A JP2021171768A JP 2021171768 A JP2021171768 A JP 2021171768A JP 2020074733 A JP2020074733 A JP 2020074733A JP 2020074733 A JP2020074733 A JP 2020074733A JP 2021171768 A JP2021171768 A JP 2021171768A
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敏雄 鋤田
Toshio Sukita
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ECO SYSTEM KK
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Abstract

To provide a crystal grain refining determination method from a cooling curve capable of determining the refining of crystal grains made into a solidification structure at the step of a molten metal.SOLUTION: A crystal grain refining determination method from a cooling curve has a process where, in the cooling curve of a molten metal utilized for casting, the refining of crystal grains is determined from a solidification speed in an optional range within a range from a primary crystal super-cooling degree and from a primary crystal temperature to an eutectic temperature.SELECTED DRAWING: Figure 3

Description

本発明は、鋳造の溶湯の冷却過程において、凝固組織の結晶粒が微細化になるか粗大化になるかを冷却曲線から判定する、冷却曲線からの結晶粒微細化判定方法に関する。 The present invention relates to a method for determining crystal grain miniaturization from a cooling curve, which determines from a cooling curve whether the crystal grains of a solidified structure become finer or coarser in the cooling process of a molten metal for casting.

溶湯が冷却された凝固組織の結晶粒が微細化された方が、強度や靭性等の機械的性質や切削性等の機械加工性が高まることから、結晶粒を微細化させるために、例えば結晶形成の核となる異質核として微量のチタンをアルミニウム溶湯に添加することが行われている。 When the crystal grains of the solidified structure in which the molten metal is cooled are refined, the mechanical properties such as strength and toughness and the machinability such as machinability are enhanced. Therefore, in order to refine the crystal grains, for example, crystals A small amount of titanium is added to the molten aluminum as a heterogeneous nucleus that becomes the core of formation.

特許文献1には、鋳造に利用する溶湯の清浄度判定方法において、該溶湯の冷却曲線上の初晶過冷度幅から該溶湯の清浄度の判定をする冷却曲線から溶湯の清浄度判定をする方法が開示されている。また、前記溶湯の冷却曲線上において液相中に固相が晶出するまでの範囲内で設定した第一の凝固温度に到達した時間と、固相の状態になった直後の温度から温度降下中の範囲内で設定した第二の凝固温度に到達した時間との差の判定凝固時間から、あるいは、前記差の判定凝固時間及び初晶過冷度幅からから、前記溶湯の清浄度の判定をする冷却曲線から溶湯の清浄度判定をする方法が開示されている。 In Patent Document 1, in the method for determining the cleanliness of a molten metal used for casting, the cleanliness of the molten metal is determined from the cooling curve for determining the cleanliness of the molten metal from the primary crystal supercooling width on the cooling curve of the molten metal. The method of doing so is disclosed. Further, the temperature drops from the time when the first solidification temperature set within the range until the solid phase crystallizes in the liquid phase on the cooling curve of the molten metal and the temperature immediately after the solid phase state is reached. Judgment of the cleanliness of the molten metal from the judgment of the difference from the time when the second solidification temperature was reached set within the range of the inside, or from the judgment of the difference from the solidification time and the primary crystal supercooling width. A method of determining the cleanliness of a molten metal from a cooling curve is disclosed.

特許文献2には、鋳造に利用する溶湯の清浄度を冷却曲線から得られるデータから判定する清浄度判定方法において、初晶温度到達時から共晶温度到達時までの間で設定した任意の2つの温度間の凝固速度から、その時点における結晶の核とならない不要物質を判定し、共晶温度到達時から固相状態になるまでの共晶反応時間から、その時点における結晶の核とならない不要物質を判定し、及び、固相状態になった直後の温度から温度降下中の範囲で設定した任意の2つの温度間の共晶完了後冷却速度から、その時点における結晶の核とならない不要物質を判定することで、溶湯の清浄度の判定をする冷却曲線から溶湯の清浄度判定方法が開示されている。 Patent Document 2 describes any 2 set between the time when the primary crystal temperature is reached and the time when the eutectic temperature is reached in the cleanliness determination method for determining the cleanliness of the molten metal used for casting from the data obtained from the cooling curve. From the solidification rate between two temperatures, the unnecessary substance that does not become the nucleus of the crystal at that time is determined, and from the eutectic reaction time from the time when the eutectic temperature is reached to the state of the solid phase, the unnecessary substance that does not become the nucleus of the crystal at that time is unnecessary. Unnecessary substance that does not become the nucleus of the crystal at that time from the cooling rate after eutectic completion between any two temperatures set in the range from the temperature immediately after the solid phase state to the temperature drop A method for determining the cleanliness of the molten metal is disclosed from the cooling curve for determining the cleanliness of the molten metal.

特許第4368933号公報Japanese Patent No. 4368933 特許第5427973号公報Japanese Patent No. 5427973

特許文献1の発明は、凝固したときの合金が材料としての欠陥を有することになる原因の不純物などの介在物が溶湯中に浮遊する量的レベルを判定する、すなわち清浄度を判定する方法であり、前記介在物としては核にならない不純物のみを対象としているので、結晶粒の微細化を判定することができないという問題があった。 The invention of Patent Document 1 is a method of determining the quantitative level at which impurities and other inclusions that cause the alloy to have defects as a material when solidified are suspended in the molten metal, that is, determining the cleanliness. Therefore, since only impurities that do not become nuclei are targeted as the inclusions, there is a problem that the miniaturization of crystal grains cannot be determined.

特許文献2の発明は、初晶温度から共晶温度までの間で設定した任意の2つの温度間の凝固速度から、その時点における結晶の核とならない不純物の有無を判定する方法であり、結晶粒の微細化を判定することができないという問題があった。 The invention of Patent Document 2 is a method of determining the presence or absence of impurities that do not become the nucleus of a crystal at that time from the solidification rate between any two temperatures set between the primary crystal temperature and the eutectic temperature. There was a problem that the fineness of grains could not be determined.

特許文献1及び2ともに、溶湯の段階で清浄度の判定ができるので、凝固組織となった金属の強度や靭性等の機械的性質が保証された、清浄度の高い溶湯を型に流し込むという有利な効果を奏するが、凝固組織になった鋳物の切削性等の機械加工性を溶湯の段階で保証できないという問題があった。 Since the cleanliness of both Patent Documents 1 and 2 can be determined at the stage of molten metal, it is advantageous to pour a highly clean molten metal into a mold, which guarantees mechanical properties such as strength and toughness of the metal having a solidified structure. However, there is a problem that the machinability such as machinability of a solidified casting cannot be guaranteed at the stage of molten metal.

本発明はこうした問題に鑑み創案されたもので、凝固組織になったときの結晶粒の微細化を溶湯の段階で判定できる、冷却曲線からの結晶粒微細化判定方法を提供することを課題とする。 The present invention has been devised in view of these problems, and an object of the present invention is to provide a method for determining crystal grain miniaturization from a cooling curve, which can determine the miniaturization of crystal grains when a solidified structure is formed at the stage of molten metal. do.

本発明において、溶湯金属自身の中から起こる核を自己生成核(均質核ともいう。)といい、溶湯に添加する核になる元素を異質核といい、溶湯の中に浮遊したり凝固組織に存在する、核にならない元素等を不純物という。 In the present invention, nuclei generated from the molten metal itself are called self-generated nuclei (also referred to as homogeneous nuclei), and the nuclei added to the molten metal are called heterogeneous nuclei, which float in the molten metal or form a solidified structure. Existing non-nucleating elements are called impurities.

請求項1に記載の冷却曲線からの結晶粒微細化判定方法は、鋳造に利用する溶湯の冷却曲線において、初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化の判定をすることを特徴とする。 The method for determining crystal grain fineness from the cooling curve according to claim 1 is any method within the range from the primary crystal supercooling degree and the primary crystal temperature to the eutectic temperature in the cooling curve of the molten metal used for casting. It is characterized in that the fineness of crystal grains is determined from the solidification rate in the range.

請求項2に記載の冷却曲線からの結晶粒微細化判定方法は、鋳造に利用する溶湯の冷却曲線において、初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化を判定する第一判定ステップと、前記第一判定ステップの判定結果に応じて、不純物の除去をする清浄化溶湯処理、及び/又は、結晶粒を微細化させるために異質核となる元素の添加を実施する溶湯改善ステップと、前記溶湯改善ステップ後に、初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化を判定する第二判定ステップと、を備えることを特徴とする。 The method for determining crystal grain fineness from the cooling curve according to claim 2 is any method within the range from the primary crystal supercooling degree and the primary crystal temperature to the eutectic temperature in the cooling curve of the molten metal used for casting. The first determination step of determining the fineness of the crystal grains from the solidification rate in the range, the cleaning molten metal treatment for removing impurities according to the determination result of the first determination step, and / or the refinement of the crystal grains. A molten metal improvement step in which an element serving as a heterogeneous nucleus is added in order to cause the reaction, and after the molten metal improvement step, the primary crystal supercooling degree and the solidification rate in an arbitrary range within the range from the primary crystal temperature to the eutectic temperature. It is characterized by comprising a second determination step of determining the miniaturization of crystal grains from the above.

請求項1又は2に記載の冷却曲線からの結晶粒微細化判定方法は、凝固組織となった鋳造製品の機械的性質及び加工性を溶湯の段階で判定できるという顕著な効果を奏する。これにより、結晶粒が粗大化するようであれば溶湯に添加剤を投入して結晶粒の微細化を狙い通りにすることができ、機械的性質や機械加工性が基準レベルをクリアした溶湯のみを型に流し込むことができ、製造コストの抑制や材料費の低減となる効果も奏する。 The method for determining grain refinement from the cooling curve according to claim 1 or 2 has a remarkable effect that the mechanical properties and processability of the cast product having a solidified structure can be determined at the stage of molten metal. As a result, if the crystal grains become coarse, additives can be added to the molten metal to achieve finer crystal grains as intended, and only the molten metal whose mechanical properties and machinability have cleared the standard level. Can be poured into a mold, which also has the effect of reducing manufacturing costs and material costs.

また、核となる自己生成核が結晶粒の微細化には不足する場合に、添加する異質核となる、例えばチタンの添加量を適正な量にすることができるという効果を奏する。 Further, when the self-generated nucleation as a nucleus is insufficient for the miniaturization of crystal grains, the effect of being able to add an appropriate amount of titanium, for example, which becomes a heterogeneous nucleus to be added, is obtained.

共晶合金となる溶湯の共晶型2元系状態図及び冷却曲線である。It is a eutectic type binary phase diagram and a cooling curve of the molten metal which becomes a eutectic alloy. 図1における初晶過冷度の範囲aの拡大説明図である。It is an enlarged explanatory view of the range a of the primary supercooling degree in FIG. 図1における初晶温度から共晶温度までの範囲bの拡大説明図である。It is an enlarged explanatory view of the range b from the primary crystal temperature to the eutectic temperature in FIG. 図3における図の下半分の範囲の拡大説明図である。It is an enlarged explanatory view of the range of the lower half of the figure in FIG.

アルミニウム等の鋳物の凝固組織には、結晶粒が微細化された組織、又は、結晶粒が粗大化された組織などが見られる。結晶粒が微細化されている凝固組織の方が、結晶粒が粗大化されている凝固組織より強度や靭性等の機械的性質が高く、かつ切断加工等の機械加工性も高い。 As the solidified structure of a casting such as aluminum, a structure in which crystal grains are refined or a structure in which crystal grains are coarsened can be seen. The solidified structure in which the crystal grains are finely divided has higher mechanical properties such as strength and toughness than the solidified structure in which the crystal grains are coarsened, and also has higher machinability such as cutting.

溶湯の中に結晶の核が少ないと核同士の間隔が広いので粒成長は大きく成長し粗大化結晶粒に成長し、溶湯の中に結晶の核が多いと核同士の間隔が狭いので粒成長は互いに抑制しあって微細化結晶粒となる。 If there are few crystal nuclei in the molten metal, the distance between the nuclei is wide, so the grain growth grows large and grows into coarse crystal grains. Suppress each other and become fine crystal grains.

そのため、微細な結晶粒にするために、溶湯金属自身の中から起こる自己生成核に加えて、鋳型や不純物元素等の異質なところを核として起こる異質核生成を行うように、結晶の核となる元素を溶湯に添加する方法が行われている。しかし、結晶の核となる可能性のある元素を多く添加すると、核にならない元素が不純物として増加することによって機械的性質が低下し製品としての品質を満足させることができない。一方、結晶の核となる元素を添加しないと、結晶となる核は自己生成核のみとなるので、結晶となる核が少なく結晶粒の粗大化が進み機械的性質及び機械加工性が低下する。そのため、適量の結晶の核となる元素を添加する必要がある。 Therefore, in order to make fine crystal grains, in addition to the self-generated nuclei generated from the molten metal itself, heteronuclear nucleation occurs with foreign parts such as templates and impurity elements as nuclei. The method of adding the element to the molten metal has been carried out. However, if a large amount of elements that may become nuclei of crystals are added, the elements that do not become nuclei increase as impurities, which deteriorates the mechanical properties and makes it impossible to satisfy the quality as a product. On the other hand, if the element that becomes the nucleus of the crystal is not added, the nucleus that becomes the crystal is only the self-generated nuclei, so that the number of nuclei that become the crystal is small and the grain size is promoted, and the mechanical properties and machinability are deteriorated. Therefore, it is necessary to add an appropriate amount of the element that becomes the core of the crystal.

発明者は、溶湯の段階で、鋳物の凝固組織の微細化を促進させ、しかも核とならない元素や不純物が少ない凝固組織をつくる制御ができるように、炉から汲みだして坩堝に注入した溶湯の冷却曲線と結晶粒の微細化及び不純物との関係性を探るべく種々トライして本発明を想到するに至った。 The inventor of the molten metal pumped out of the furnace and injected into the pit so as to promote the miniaturization of the solidified structure of the casting at the stage of the molten metal and to control the formation of a solidified structure with few non-core elements and impurities. We have come up with the present invention by making various trials to investigate the relationship between the cooling curve, the miniaturization of crystal grains, and impurities.

本発明の冷却曲線からの結晶粒微細化判定方法は、鋳造に利用する溶湯の冷却曲線において、初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化の判定をする冷却曲線からの結晶粒微細化判定方法である。 In the cooling curve of the molten metal used for casting, the method for determining crystal grain fineness from the cooling curve of the present invention solidifies the primary crystal supercooling degree and solidification in an arbitrary range within the range from the primary crystal temperature to the eutectic temperature. This is a method for determining crystal grain fineness from a cooling curve, which determines crystal grain fineness based on speed.

本発明は、第一段階の判定と第二段階の判定とから構成されている。第一段階は初晶過冷度から結晶粒微細化判定方法で、第二段階は初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒微細化判定方法である。 The present invention comprises a first-stage determination and a second-stage determination. The first step is a method for determining crystal grain miniaturization from the primary supercooling degree, and the second step is a method for determining crystal grain miniaturization from the solidification rate in an arbitrary range from the primary crystal temperature to the eutectic temperature.

ここで、図1において、元素Aと元素Sとの共晶合金となる溶湯の共晶型2元系状態図及び冷却曲線について説明する。液相Lは元素Aと元素Sが溶解している液相Lで、固相線Pはα相への元素Sの固溶限界を示し、液相線Qは液相から固相に変わる温度を示す。α相の元素Sの濃度を、C、C1、C2で表す。 Here, in FIG. 1, a eutectic binary phase diagram and a cooling curve of a molten metal which is a eutectic alloy of element A and element S will be described. The liquid phase L is the liquid phase L in which the element A and the element S are dissolved, the solid phase line P indicates the solid solution limit of the element S in the α phase, and the liquid phase line Q is the temperature at which the liquid phase changes to the solid phase. Is shown. The concentration of the element S in the α phase is represented by C, C1 and C2.

図1において、例えば元素Aと元素Sの2元素の共晶型の亜共晶の場合で、α相の元素Sの濃度が濃度C%の場合、温度T0の液相Lの溶湯が凝固速度mで冷却されて液相線Qに達して初晶温度T1になったときに、初晶が晶出せず、さらに温度が下がって過冷却になって温度t1、t2又はt3で初晶が晶出し、液相Lからα相に変わる状態変化の際に潜熱を発熱して温度が上昇し、初晶温度T1で核形成による潜熱の発熱と溶湯の冷却とが平衡して温度一定の時間帯sがある。 In FIG. 1, for example, in the case of a eutectic subeutectic of two elements, element A and element S, when the concentration of element S in the α phase is C%, the molten metal in the liquid phase L at temperature T0 solidifies. When it is cooled at m and reaches the liquidus line Q to reach the primary crystal temperature T1, the primary crystals do not crystallize, and the temperature drops further to become supercooled, and the primary crystals crystallize at temperatures t1, t2 or t3. When the state changes from the liquid phase L to the α phase, latent heat is generated and the temperature rises. At the eutectic temperature T1, the latent heat generated by nucleation and the cooling of the molten metal are in equilibrium and the temperature is constant. There is s.

前記初晶が晶出時に過冷却になるときに、溶湯の液相L中には、異質核を添加しない溶湯の液相L中に浮遊するのは、核にならない元素等の不純物と、溶湯金属自身の中から起こる自己生成核とが存在し、異質核を添加した溶湯の液相L中に浮遊するのは、核にならない元素等の不純物と、溶湯金属自身の中から起こる自己生成核と、核となる異質核が存在する。 When the primary crystals are supercooled at the time of crystallization, impurities such as non-nucleating elements and impurities floating in the liquid phase L of the molten metal to which foreign nuclei are not added in the liquid phase L of the molten metal and the molten metal are suspended. There are self-generated nuclei generated from the metal itself, and impurities such as non-nucleating elements and self-generated nuclei generated from the molten metal itself are suspended in the liquid phase L of the molten metal to which the foreign nuclei are added. And there is a heterogeneous nucleus that becomes the nucleus.

初晶温度T1から共晶温度T2に至る範囲は、図1の冷却曲線及び共晶型2元系状態図において、初晶温度T1から共晶温度T2まで温度降下する範囲bであり、この間の組織はα相と液相Lとが存在している。共晶温度T2まで温度降下すると共晶温度T2で核形成による潜熱の発熱と溶湯の冷却とが平衡して温度一定の時間帯kがある。 The range from the primary crystal temperature T1 to the eutectic temperature T2 is the range b in which the temperature drops from the primary crystal temperature T1 to the eutectic temperature T2 in the cooling curve and the eutectic binary phase diagram of FIG. The structure has an α phase and a liquid phase L. When the temperature drops to the eutectic temperature T2, the heat generation of latent heat due to nucleation and the cooling of the molten metal are in equilibrium at the eutectic temperature T2, and there is a time zone k where the temperature is constant.

そして、図1において、初晶温度T1と共晶温度T2との間の温度T3のときは、α相と液相Lとの量比は、(α相):(液相L)=(C2−C0):(C0−C1)で変化する。よって、初晶温度T1と共晶温度T2との間においては、温度降下になるに従い、α相が液相線Qの変化によって徐々に形成されることが示されている。 Then, in FIG. 1, when the temperature T3 is between the primary crystal temperature T1 and the eutectic temperature T2, the quantitative ratio between the α phase and the liquid phase L is (α phase) :( liquid phase L) = (C2). -C0): Changes with (C0-C1). Therefore, it is shown that between the primary crystal temperature T1 and the eutectic temperature T2, the α phase is gradually formed by the change of the liquidus line Q as the temperature drops.

溶湯の温度降下にしたがって前記α相が徐々に増加するときに、結晶粒が粗大化になる場合と微細化になる場合とで冷却時の放熱速度が異なり凝固速度が異なると仮説した。 It was hypothesized that when the α phase gradually increases as the temperature of the molten metal drops, the heat dissipation rate during cooling differs depending on whether the crystal grains become coarser or finer, and the solidification rate differs.

次に、鋳造に利用する溶湯を坩堝に注入した後の冷却曲線において、第一段階の初晶過冷度からの結晶粒微細化判定と、第二段階の初晶温度T1から共晶温度T2に至る範囲内の任意の範囲における凝固速度nから結晶粒微細化判定のためのデータを把握する。 Next, in the cooling curve after injecting the molten metal used for casting into the crucible, the crystal grain miniaturization determination from the primary crystal supercooling degree in the first stage and the crystal grain refinement determination from the primary crystal temperature T1 to the eutectic temperature T2 in the second stage Data for determining crystal grain miniaturization is grasped from the solidification rate n in an arbitrary range within the range up to.

前記データ把握のために、アルムニウム合金鋳物AC4C(アルミニウム90.1〜93.3%、珪素6.5〜7.5%、その他元素0.2〜2.4%)を使用し、測定装置はアルミ熱分析装置(型式ALTEC−12ST、エコ・システム有限会社製)と坩堝(型式ES−CP01、エコ・システム有限会社製)を使用し、前記坩堝から取り出した試料の切断面の観察に使用した顕微鏡写真は公的機関で撮影した。 In order to grasp the data, alumnium alloy casting AC4C (aluminum 90 to 93.3%, silicon 6.5 to 7.5%, other elements 0.2 to 2.4%) was used, and the measuring device was used. An aluminum thermal analyzer (model ALTEC-12ST, manufactured by Eco System Co., Ltd.) and a crucible (model ES-CP01, manufactured by Eco System Co., Ltd.) were used to observe the cut surface of the sample taken out from the crucible. Microscopic photographs were taken by a public institution.

溶湯の試料は、清浄化溶湯処理して不純物が少ない溶湯の試料I、ゴミを多く添加して不純物を多くした溶湯の試料III、前記試料Iと前記試料IIIの中間の不純物が中程度の試料II、前記試料I〜IIIのいずれに対しても、異質核となるチタンを添加しなかったケースa、異質核となるチタンを多く添加したケースc、前記ケースaと前記ケースcとの中間の量の異質核となるチタンを中程度添加したケースbを実施した。すなわち、試料I―a、試料I―b、試料I―c、試料II―a、試料II―b、試料II―c、試料III―a、試料III―b、試料III―cを造り、その結果を表1に示す。 The molten metal samples are the sample I of the molten metal that has been treated with a purified molten metal and has few impurities, the sample III of the molten metal that has increased impurities by adding a large amount of dust, and the sample with medium impurities between the sample I and the sample III. For any of II and the samples I to III, a case a in which titanium as a foreign nucleus was not added, a case c in which a large amount of titanium as a foreign nucleus was added, and an intermediate between the case a and the case c. Case b was carried out in which a moderate amount of titanium, which is a heterogeneous nucleus, was added. That is, sample I-a, sample I-b, sample I-c, sample II-a, sample II-b, sample II-c, sample III-a, sample III-b, and sample III-c are prepared. The results are shown in Table 1.

Figure 2021171768
Figure 2021171768

表1から、異質核の添加量や不純物の添加量などの試料配分と顕微鏡写真とでは、異質核・自己生成核、不純物の量はほぼ一致していた。本発明で実現させる凝固組織は結晶粒の微細化が形成され不純物が少ない試料であり、初晶過冷度R3で凝固速度D3又はD4が好ましい。 From Table 1, the amounts of foreign nuclei, self-generated nuclei, and impurities were almost the same in the sample distribution such as the amount of foreign nuclei added and the amount of impurities added and the micrograph. The solidified structure realized by the present invention is a sample in which fine crystal grains are formed and impurities are small, and a solidification rate D3 or D4 is preferable at a primary crystal supercooling degree R3.

次に、鋳造に利用する溶湯を坩堝に注入した後の冷却曲線において、第一段階の初晶過冷度からの結晶粒微細化判定について説明する。そのため、表1を初晶過冷度の範囲別に変え、その結果を表2に示す。 Next, in the cooling curve after injecting the molten metal used for casting into the crucible, the determination of grain refinement from the primary crystal supercooling degree of the first stage will be described. Therefore, Table 1 is changed according to the range of primary supercooling degree, and the results are shown in Table 2.

Figure 2021171768
Figure 2021171768

図2及び表2に示すように、前記過冷却になったときの温度t1、t2又はt3と、初晶温度T1との温度差である初晶過冷度が、液相L中に浮遊する不純物の量により変化する。図2において、低い温度t1で初晶が晶出したときを深い初晶過冷度とし、初晶温度T1未満の範囲で比較的高い温度t3で初晶が晶出したときを浅い初晶過冷度とし、温度t1と温度t2との中間帯の温度t2で初晶が晶出したときを中程度の初晶過冷度とする。 As shown in FIGS. 2 and 2, the primary crystal supercooling degree, which is the temperature difference between the temperatures t1, t2 or t3 at the time of supercooling and the primary crystal temperature T1, floats in the liquid phase L. It depends on the amount of impurities. In FIG. 2, when the primary crystal crystallizes at a low temperature t1, the deep primary crystal supercooling degree is defined as, and when the primary crystal crystallizes at a relatively high temperature t3 within the range of the primary crystal temperature T1 or less, the shallow primary crystal supercooling is defined. The degree of coldness is defined as the degree of supercooling of the primary crystal when the primary crystal crystallizes at the temperature t2 in the intermediate zone between the temperature t1 and the temperature t2.

そして、前記深い初晶過冷度より少し高めの温度以下の温度で初晶が晶出する範囲を初晶過冷度範囲R1とし、前記浅い初晶過冷度より少し低めの温度以上で初晶温度T1未満の温度で初晶が晶出する範囲を初晶過冷度範囲R3とし、前記初晶過冷度範囲R1より高温側で前記初晶過冷度範囲R3より低温側の温度で初晶が晶出する範囲を初晶過冷度範囲R2とする。 Then, the range in which the primary crystals crystallize at a temperature slightly higher than the deep primary crystal supercooling degree is defined as the primary crystal supercooling degree range R1, and the first crystal is formed at a temperature slightly lower than the shallow primary crystal supercooling degree. The range in which the primary crystals crystallize at a temperature lower than the crystal temperature T1 is defined as the primary crystal supercooling range R3, and the temperature on the higher temperature side than the primary crystal supercooling range R1 and on the lower temperature side than the primary crystal supercooling range R3. The range in which the primary crystals crystallize is defined as the primary crystal supercooling temperature range R2.

また、表2から、核になる異質核と、溶湯金属自身の中から起こる自己生成核と、核にならない不純物との合計で初晶過冷度が変化することが示唆されている。異質核と自己生成核との合計が多い場合には不純物の数にかかわらず初晶過冷度は浅くなり、不純物が多い場合には異質核と自己生成核との合計にかかわらず初晶過冷度は浅くなることが示されている。初晶過冷度が同じレベルであっても、核になる異質核や自己生成核が多いのか、又は、核にならない不純物が多いのかの判定が困難であることが示されている。好ましいのは異質核や自己生成核が多く不純物が少ない場合である。 In addition, Table 2 suggests that the primary supercooling degree changes in total of the heteronuclear nuclei, the self-generated nuclei generated from the molten metal itself, and the impurities that do not become nuclei. When the total of heterologous nuclei and self-generated nuclei is large, the primary supercooling degree becomes shallow regardless of the number of impurities, and when the total of foreign nuclei and self-generated nuclei is large, the primary crystal supercooling becomes shallow regardless of the total number of impurities. It has been shown that the coldness becomes shallower. It has been shown that even if the primary supercooling degree is at the same level, it is difficult to determine whether there are many foreign nuclei or self-generated nuclei that become nuclei, or there are many impurities that do not become nuclei. It is preferable that there are many foreign nuclei and self-generated nuclei and few impurities.

また、初晶過冷度範囲R3の深い場合は、異質核と自己生成核との合計が少ない場合でかつ不純物が少ない場合である。よって、初晶過冷度範囲R3の場合は不純物は少ないが、核が少ないのでこのまま凝固すれば凝固組織の結晶粒は粗大化結晶粒となる。 Further, when the primary supercooling range R3 is deep, it is a case where the total of the heterologous nuclei and the self-generated nuclei is small and the impurities are small. Therefore, in the case of the primary crystal supercooling range R3, there are few impurities, but since there are few nuclei, if solidification is carried out as it is, the crystal grains of the solidified structure become coarse crystal grains.

凝固組織の結晶粒の微細化を図るには、核が多いほど好ましく、機械的性質の低下を防ぐには核にならない不純物が少ないことが好ましい。なお、溶湯には異質核は意図的に添加しないと少量しか存在しない In order to refine the crystal grains of the solidified structure, it is preferable that the number of nuclei is large, and in order to prevent deterioration of mechanical properties, it is preferable that there are few impurities that do not become nuclei. In addition, only a small amount of foreign nuclei exist in the molten metal unless it is intentionally added.

次に、鋳造に利用する溶湯を坩堝に注入した後の冷却曲線において、第二段階の初晶温度T1から共晶温度T2に至る範囲内の任意の範囲における凝固速度nから結晶粒微細化判定について説明する。そのため、表1を初晶温度T1から共晶温度T2に至る範囲内の任意の範囲における凝固速度n別に変え、その結果を表3に示す。前記初晶温度T1から共晶温度T2に至る範囲内の任意の範囲とは、図3において、前記初晶温度T1から共晶温度T2に至る範囲Wでもよいし、前記範囲Wのうちの範囲W1でも凝固速度nは略同一であるのでよい。 Next, in the cooling curve after injecting the molten metal used for casting into the crucible, the grain refinement determination is made from the solidification rate n in an arbitrary range within the range from the primary crystal temperature T1 to the eutectic temperature T2 in the second stage. Will be described. Therefore, Table 1 is changed according to the solidification rate n in an arbitrary range within the range from the primary crystal temperature T1 to the eutectic temperature T2, and the results are shown in Table 3. In FIG. 3, the arbitrary range within the range from the primary crystal temperature T1 to the eutectic temperature T2 may be the range W from the primary crystal temperature T1 to the eutectic temperature T2, or the range W within the range W. Even in W1, the solidification rate n may be substantially the same.

図3、図4及び表3において、顕微鏡写真で結晶粒の大きさを「粗大化、中程度、微細化、超微細化」の4つに区分し、不純物の量を「多い、中程度、少ない」の3つに区分し、それらの組み合わせに合わせて凝固速度の速い・遅いというレベルに応じて4つに区分した。すなわち、最も遅い凝固速度n1の近傍の範囲を範囲D1、範囲D1より少し早い凝固速度n2の近傍の範囲を範囲D2、最も早い凝固速度n4の近傍の範囲を範囲D4、範囲D2と範囲D4との間の凝固速度n3の範囲を範囲D3とした。 In FIGS. 3, 4 and 3, the size of the crystal grains is classified into four, "coarse, medium, fine, and ultrafine" in the micrograph, and the amount of impurities is "high, medium,". It was divided into 3 categories, "less", and 4 categories according to the level of fast / slow solidification rate according to the combination of them. That is, the range near the slowest solidification rate n1 is the range D1, the range near the solidification rate n2 slightly faster than the range D1 is the range D2, and the range near the fastest solidification rate n4 is the range D4, the range D2 and the range D4. The range of the solidification rate n3 between the two was defined as the range D3.

Figure 2021171768
Figure 2021171768

表3から、不純物の多少にかかわらず結晶粒の大きさによって凝固速度に相違が生ずることが示されている。結晶粒が微細化された方が放熱速度が速くなり凝固速度が速くなり、結晶粒が粗大化された方が放熱速度が遅くなり凝固速度が遅くなることが示され仮説が立証された。 Table 3 shows that the solidification rate differs depending on the size of the crystal grains regardless of the amount of impurities. The hypothesis was proved by showing that the finer the crystal grains, the faster the heat dissipation rate and the faster the solidification rate, and the coarser the crystal grains, the slower the heat dissipation rate and the slower the solidification rate.

よって、表2の初晶過冷度と表3の凝固速度から、異質核と自己生成核と不純物の存在の量を判定し、凝固速度で結晶粒の大きさを判定することにより、炉内の溶湯の結晶粒の微細化を実現させることができる。 Therefore, the amount of foreign nuclei, self-generated nuclei, and impurities is determined from the primary supercooling degree in Table 2 and the solidification rate in Table 3, and the size of crystal grains is determined by the solidification rate. It is possible to realize the refinement of the crystal grains of the molten metal.

前記表1〜表3から、第一段階の判定と第二段階の判定とから、溶湯の中の不純物を減少させ結晶粒の微細化を実現されることができるかという結晶粒微細化の判定をすることができる。 From Tables 1 to 3 above, from the first-stage determination and the second-stage determination, the determination of crystal grain refinement as to whether or not the impurities in the molten metal can be reduced and the crystal grain refinement can be realized. Can be done.

次に、前記第一段階の判定と第二段階の判定とから構成される、凝固速度から結晶粒微細化判定方法を繰り返すことによって、例えば不純物が多くて自己生成核が少ない溶湯であっても、不純物が少なく核になる異質核が多い溶湯に改善でき、改善しなかったら結晶粒が粗大化し不純物が多い凝固組織になり機械的性質が劣り機械加工性が劣る金属鋳物になるところを、前記改善を適切に実施することにより結晶粒が微細化し不純物が少ない凝固組織になり機械的性質が優れ機械加工性が優れる金属鋳物を造ることができる。そのためには不純物が少なくかつ結晶粒の微細化を実現できる溶湯であるかを判定できることが不可欠である。 Next, by repeating the grain refinement determination method based on the solidification rate, which is composed of the first stage determination and the second stage determination, for example, even if the molten metal has a large amount of impurities and a small amount of self-generated nuclei. It can be improved to a molten metal with few impurities and many heterogeneous nuclei. By appropriately carrying out the improvement, it is possible to produce a metal casting in which the crystal grains are refined to have a solidified structure with few impurities, and the mechanical properties are excellent and the workability is excellent. For that purpose, it is indispensable to be able to determine whether the molten metal has few impurities and can realize the miniaturization of crystal grains.

すなわち、冷却曲線からの結晶粒微細化判定方法は、鋳造に利用する溶湯の冷却曲線において、初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化を判定する第一判定ステップと、前記第一判定ステップの判定結果に応じて、不純物の除去をする清浄化溶湯処理、及び/又は、結晶粒を微細化させるために異質核となる元素の添加を実施する溶湯改善ステップと、前記溶湯改善ステップ後に、初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化を判定する第二判定ステップと、を備える。 That is, the method for determining crystal grain fineness from the cooling curve is the primary crystal supercooling degree and the solidification rate in an arbitrary range within the range from the primary crystal temperature to the eutectic temperature in the cooling curve of the molten metal used for casting. The first determination step for determining the fineness of the crystal grains from the above, the cleaning molten metal treatment for removing impurities according to the determination result of the first determination step, and / or the heterogeneity for making the crystal grains finer. After the molten metal improvement step of adding the core element and the molten metal improvement step, the crystal supercooling degree and the solidification rate in an arbitrary range from the primary crystal temperature to the eutectic temperature indicate the crystal grains. It includes a second determination step for determining miniaturization.

次に、本発明の実施例を説明する。実施例はこれに限定されるものではなく、冷却曲線の初晶過冷度と、初晶温度から共晶温度までの凝固速度との測定結果により、凝固組織の結晶粒の微細化を実現させるための種々の対応ができる。 Next, examples of the present invention will be described. Examples are not limited to this, and the miniaturization of crystal grains of the solidified structure is realized by the measurement results of the primary supercooling degree of the cooling curve and the solidification rate from the primary crystal temperature to the eutectic temperature. Various measures can be taken for this.

まず、アルミニウムと珪素の共晶合金の鋳物になる溶湯を炉内から汲み上げて検査用の坩堝に注入し、該坩堝内の溶湯の冷却曲線の初晶過冷度を測定し第一段階の判定をし、初晶温度から共晶温度までの凝固速度とを測定し第二段階の判定をする。 First, the molten metal, which is a casting of a eutectic alloy of aluminum and silicon, is pumped from the furnace and injected into a crucible for inspection, and the primary crystal supercooling degree of the cooling curve of the molten metal in the crucible is measured to determine the first stage. Then, the solidification rate from the primary crystal temperature to the eutectic temperature is measured to determine the second stage.

ケース1として、まず、第一判定ステップである。第一段階の初晶過冷度が深く初晶過冷度範囲R1で、第二段階の凝固速度が遅く凝固速度D1の場合は、凝固組織の機械的性質及び機械的加工性に係る、結晶粒の微細化について炉内の溶湯の判定は、不純物は許容範囲内であるが核の数が少なく結晶粒が粗大化するという判定をする。そして、溶湯改善ステップとして、炉内の溶湯に異質核となる元素、例えばチタンを多く添加して溶湯の改善をする。次に、第二判定ステップである。第2回目の溶湯を炉内から汲み上げて検査用の坩堝に注入し、該坩堝内の溶湯の冷却曲線の初晶過冷度を測定し第一段階の判定をし、初晶温度から共晶温度までの凝固速度を測定し第二段階の判定をする。 Case 1 is the first determination step. When the primary crystal supercooling degree of the first stage is deep and the primary crystal supercooling degree range R1 and the solidification rate of the second stage is slow and the solidification rate D1, the crystals are related to the mechanical properties and mechanical processability of the solidified structure. Regarding grain refinement The judgment of the molten metal in the furnace is that the impurities are within the permissible range, but the number of nuclei is small and the crystal grains become coarse. Then, as a molten metal improvement step, a large amount of an element that becomes a heterogeneous nucleus, for example, titanium, is added to the molten metal in the furnace to improve the molten metal. Next is the second determination step. The second molten metal is pumped from the furnace and injected into the crucible for inspection, the primary crystal supercooling degree of the cooling curve of the molten metal in the crucible is measured, the first stage judgment is made, and the eutectic is determined from the primary crystal temperature. The solidification rate up to the temperature is measured and the second stage is judged.

その結果、第一段階の初晶過冷度が浅く初晶過冷度範囲R3となり、第二段階の凝固速度が速く凝固速度範囲D3になった場合は、凝固組織の機械的性質及び機械的加工性に係る、結晶粒の微細化について炉内の溶湯の判定は、不純物は許容範囲内であり核の数が多く結晶粒の微細化が実現するという判定をする。初晶過冷度範囲R1が初晶過冷度範囲R3に変わった理由は、第一判定ステップ以降に不純物を添加していないことと、凝固速度がD1からD3に速くなったことから、核になる異質核が増加したことが理由と考えられる。 As a result, when the primary crystal supercooling degree of the first stage is shallow and the primary crystal supercooling degree range R3 is reached, and when the solidification rate of the second stage is high and the solidification rate range D3 is reached, the mechanical properties and mechanical properties of the solidified structure are reached. Regarding the fineness of crystal grains related to workability, the judgment of the molten metal in the furnace is that the impurities are within the permissible range, the number of nuclei is large, and the fineness of the crystal grains is realized. The reason why the primary supercooling range R1 was changed to the primary supercooling range R3 is that no impurities were added after the first determination step and the solidification rate increased from D1 to D3. It is considered that the reason is that the number of supercooled nuclei has increased.

ケース2として、まず、第一判定ステップである。第一段階の初晶過冷度が浅く初晶過冷度範囲R3で、第二段階の凝固速度が遅く凝固速度範囲D1の場合は、凝固組織の機械的性質及び機械的加工性に係る、結晶粒の微細化について炉内の溶湯の判定は、不純物は許容範囲を超えており核の数が少なく結晶粒が粗大化するという判定をする。そして、溶湯改善ステップとして、炉内の溶湯に清浄化を図る清浄化溶湯処理をし、炉内の溶湯に異質核となる元素、例えば元素チタンを比較的多く添加して溶湯の改善をする。次に、第二判定ステップである。第2回目の溶湯を炉内から汲み上げて検査用の坩堝に注入し、該坩堝内の溶湯の冷却曲線の初晶過冷度を測定し第一段階の判定をし、初晶温度から共晶温度までの凝固速度を測定し第二段階の判定をする。 Case 2 is the first determination step. When the primary crystal supercooling degree of the first stage is shallow and the primary crystal supercooling degree range R3 and the solidification rate of the second stage is slow and the solidification rate range D1, it relates to the mechanical properties and mechanical workability of the solidified structure. Regarding the refinement of crystal grains The judgment of the molten metal in the furnace is that the impurities exceed the permissible range, the number of nuclei is small, and the crystal grains become coarse. Then, as a step for improving the molten metal, a cleaning molten metal treatment for purifying the molten metal in the furnace is performed, and a relatively large amount of an element that becomes a heterogeneous nucleus, for example, elemental titanium, is added to the molten metal in the furnace to improve the molten metal. Next is the second determination step. The second molten metal is pumped from the furnace and injected into the crucible for inspection, the primary crystal supercooling degree of the cooling curve of the molten metal in the crucible is measured, the first stage judgment is made, and the eutectic is determined from the primary crystal temperature. The solidification rate up to the temperature is measured and the second stage is judged.

その結果、第一段階の初晶過冷度が浅く初晶過冷度範囲R3で変わらず、第二段階の凝固速度が速くなって凝固速度範囲D3になった場合は、凝固組織の機械的性質及び機械的加工性に係る、結晶粒の微細化について炉内の溶湯の判定は、不純物は許容範囲内に改善され異質核の数が増加して結晶粒の微細化が実現するという判定をする。不純物は清浄化溶湯処理で減少させたが、代わりに核になる異質核が増加して初晶過冷度範囲R3は変わらずと判定する。 As a result, when the primary crystal supercooling degree of the first stage is shallow and does not change in the primary crystal supercooling degree range R3, and the solidification rate of the second stage becomes faster and reaches the solidification rate range D3, the solidification structure is mechanical. Regarding the refinement of crystal grains related to properties and mechanical processability, the judgment of the molten metal in the furnace was that impurities were improved within the permissible range, the number of foreign nuclei increased, and the refinement of crystal grains was realized. do. Although the impurities were reduced by the purified molten metal treatment, it is judged that the heterogeneous nuclei that become nuclei increase instead and the primary supercooling range R3 does not change.

ケース3として、まず、第一判定ステップである。第一段階の初晶過冷度が浅く初晶過冷度範囲R3で、第二段階の凝固速度が最速で凝固速度範囲D4の場合は、凝固組織の機械的性質及び機械的加工性に係る、結晶粒の微細化について炉内の溶湯の判定は、不純物は許容範囲内であり核の数も多く結晶粒が超微細化するという判定をする。ここで、初晶過冷度範囲R3の原因は一般的には不純物が多いことが理由であるが、凝固速度は最速の凝固速度範囲D4であることから、初晶過冷度範囲R3の原因は異質核と自己生成核が多く存在していることが理由である。溶湯改善ステップで異質核を添加しなくても異質核が溶湯に多く存在している理由は、一例として、すでにチタン等の異質核を添加した鋳物をリターン材として溶解させた場合である。なお、この場合は、第二判定ステップは不要である。 Case 3 is the first determination step. When the primary crystal supercooling degree of the first stage is shallow and the primary crystal supercooling degree range R3 and the solidification rate of the second stage is the fastest and the solidification rate range D4, it relates to the mechanical properties and mechanical workability of the solidified structure. Regarding the refinement of crystal grains, the judgment of the molten metal in the furnace is that the impurities are within the permissible range, the number of nuclei is large, and the crystal grains become ultrafine. Here, the cause of the primary crystal supercooling range R3 is generally that there are many impurities, but since the solidification rate is the fastest solidification rate range D4, the cause of the primary crystal supercooling range R3. Is because there are many foreign nuclei and self-generated nuclei. The reason why a large amount of foreign nuclei are present in the molten metal without adding foreign nuclei in the molten metal improvement step is, for example, when a casting to which foreign nuclei such as titanium have already been added is melted as a return material. In this case, the second determination step is unnecessary.

ケース4として、まず、第一判定ステップである。第一段階の初晶過冷度が中程度で初晶過冷度範囲R2で、第二段階の凝固速度が遅く凝固速度範囲D1の場合は、凝固組織の機械的性質及び機械的加工性に係る、結晶粒の微細化について炉内の溶湯の判定は、不純物は許容範囲を少し超えており核の数が少なく結晶粒が粗大化するという判定をする。そして、溶湯改善ステップとして、炉内の溶湯に清浄化を図る清浄化溶湯処理をし、炉内の溶湯に異質核となる、例えば元素チタンを多く添加して溶湯の改善をする。次に、第二判定ステップである。第2回目の溶湯を炉内から汲み上げて検査用の坩堝に注入し、該坩堝内の溶湯の冷却曲線の初晶過冷度を測定し第一段階の判定をし、初晶温度から共晶温度までの凝固速度を測定し第二段階の判定をする。 Case 4 is the first determination step. When the primary crystal supercooling degree of the first stage is medium and the primary crystal supercooling degree range R2, and the solidification rate of the second stage is slow and the solidification rate range D1, the mechanical properties and mechanical workability of the solidified structure Regarding the fineness of the crystal grains, the judgment of the molten metal in the furnace is that the impurities are slightly beyond the permissible range, the number of nuclei is small, and the crystal grains are coarsened. Then, as a molten metal improvement step, a cleaning molten metal treatment for purifying the molten metal in the furnace is performed, and a large amount of elemental titanium, which is a heterogeneous nucleus, is added to the molten metal in the furnace to improve the molten metal. Next is the second determination step. The second molten metal is pumped from the furnace and injected into the crucible for inspection, the primary crystal supercooling degree of the cooling curve of the molten metal in the crucible is measured, the first stage judgment is made, and the eutectic is determined from the primary crystal temperature. The solidification rate up to the temperature is measured and the second stage is judged.

その結果、第一段階の初晶過冷度が浅くなって初晶過冷度範囲R3となり、第二段階の凝固速度が速くなり凝固速度範囲D3になった場合は、凝固組織の機械的性質及び機械的加工性に係る、結晶粒の微細化について炉内の溶湯の判定は、不純物は許容範囲内に改善され異質核の数が増加し結晶粒の微細化が実現するという判定をする。 As a result, when the primary crystal supercooling degree of the first stage becomes shallow and the primary crystal supercooling degree range R3 is reached, and when the solidification rate of the second stage becomes high and the solidification rate range D3 is reached, the mechanical properties of the solidified structure And regarding the fineness of crystal grains related to mechanical processability, the judgment of the molten metal in the furnace is that impurities are improved within the permissible range, the number of foreign nuclei increases, and the fineness of crystal grains is realized.

以上のように、溶湯の状況に応じて凝固組織の機械的性質及び機械的加工性を向上させる、溶湯の清浄化(不純物減少化と同じ意味である。)及び結晶粒の微細化を実現させることができる。そのため、第一段階の初晶過冷度に応じて初晶過冷度範囲R3に変えるための、かつ、第二段階の凝固速度に応じて凝固速度D3又はD4に変えるための異質核の添加量のデータを収集すれば効果的に実施することができる。 As described above, it is possible to improve the mechanical properties and mechanical processability of the solidified structure according to the condition of the molten metal, to realize the purification of the molten metal (which has the same meaning as the reduction of impurities) and the miniaturization of crystal grains. be able to. Therefore, addition of a foreign nucleus for changing to the primary crystal supercooling range R3 according to the primary crystal supercooling degree in the first stage and for changing to the solidification rate D3 or D4 according to the solidification rate in the second stage. It can be effectively implemented by collecting a large amount of data.

1 共晶型2元系状態図
2 冷却曲線
L 液相
Q 液相線
P 固相線
T1 初晶温度
T2 共晶温度
m 凝固速度
n 凝固速度
R 範囲
D 範囲
W 範囲
s 時間帯
k 時間帯
1 Eutectic binary system State Fig. 2 Cooling curve L Liquid phase Q Liquid phase line P Solid phase line T1 Primary crystal temperature T2 Eutectic temperature m Solidification rate n Solidification rate R Range D Range W Range s Time zone k Time zone

Claims (2)

鋳造に利用する溶湯の冷却曲線において、初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化を判定することを特徴とする冷却曲線からの結晶粒微細化判定方法。 In the cooling curve of the molten metal used for casting, it is characterized in that the miniaturization of crystal grains is determined from the primary crystal supercooling degree and the solidification rate in an arbitrary range within the range from the primary crystal temperature to the eutectic temperature. Crystal grain miniaturization determination method from the cooling curve. 鋳造に利用する溶湯の冷却曲線において、
初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化を判定する第一判定ステップと、
前記第一判定ステップの判定結果に応じて、不純物の除去をする清浄化溶湯処理、及び/又は、結晶粒を微細化させるために異質核となる元素の添加を実施する溶湯改善ステップと、
前記溶湯改善ステップ後に、初晶過冷度、及び、初晶温度から共晶温度に至る範囲内の任意の範囲における凝固速度から結晶粒の微細化を判定する第二判定ステップと、を備えることを特徴とする冷却曲線からの結晶粒微細化判定方法。
In the cooling curve of the molten metal used for casting
The first determination step of determining the grain refinement from the primary crystal supercooling degree and the solidification rate in an arbitrary range from the primary crystal temperature to the eutectic temperature, and
According to the determination result of the first determination step, a purification molten metal treatment for removing impurities and / or a molten metal improvement step for adding an element which becomes a heterogeneous nucleus in order to refine the crystal grains.
After the molten metal improvement step, a second determination step of determining the refinement of crystal grains from the primary crystal supercooling degree and the solidification rate in an arbitrary range from the primary crystal temperature to the eutectic temperature is provided. A method for determining grain refinement from a cooling curve characterized by.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05223759A (en) * 1991-05-10 1993-08-31 Toyota Central Res & Dev Lab Inc Crystal grain fragmentation judgment device for magnesium alloy melt
JPH07209220A (en) * 1994-01-25 1995-08-11 Nippon Light Metal Co Ltd Quality control method for molten metal
JP2014098193A (en) * 2012-11-15 2014-05-29 Nippon Light Metal Co Ltd Aluminum alloy sheet for battery case excellent in moldability and weldability
JP2018070899A (en) * 2016-10-24 2018-05-10 日本軽金属株式会社 Hypereutectic Al-Mn Aluminum Alloy Casting Material and Method for Producing the Same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05223759A (en) * 1991-05-10 1993-08-31 Toyota Central Res & Dev Lab Inc Crystal grain fragmentation judgment device for magnesium alloy melt
JPH07209220A (en) * 1994-01-25 1995-08-11 Nippon Light Metal Co Ltd Quality control method for molten metal
JP2014098193A (en) * 2012-11-15 2014-05-29 Nippon Light Metal Co Ltd Aluminum alloy sheet for battery case excellent in moldability and weldability
JP2018070899A (en) * 2016-10-24 2018-05-10 日本軽金属株式会社 Hypereutectic Al-Mn Aluminum Alloy Casting Material and Method for Producing the Same

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