JP2007291444A - Hot work tool steel with high toughness, and its manufacturing method - Google Patents

Hot work tool steel with high toughness, and its manufacturing method Download PDF

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JP2007291444A
JP2007291444A JP2006120286A JP2006120286A JP2007291444A JP 2007291444 A JP2007291444 A JP 2007291444A JP 2006120286 A JP2006120286 A JP 2006120286A JP 2006120286 A JP2006120286 A JP 2006120286A JP 2007291444 A JP2007291444 A JP 2007291444A
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toughness
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tool steel
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JP4739105B2 (en
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Daien Yokoi
大円 横井
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Sanyo Special Steel Co Ltd
山陽特殊製鋼株式会社
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<P>PROBLEM TO BE SOLVED: To provide hot work tool steel having excellent toughness and its manufacturing method. <P>SOLUTION: The hot work tool steel with high toughness can be obtained by subjecting steel which has a composition consisting of, by mass, 0.30 to 0.50% C, 4.0 to 5.5% Cr, 0.5 to 2.0% Mo, 0.5 to 1.5% V and the balance Fe with inevitable impurities to rolling forging at 950 to 1,250°C rolling forging temperature, regulating the finishing temperature of the rolling forging to 900 to 1,150°C and then carrying out annealing at ≥0.05°C/sec cooling rate after the rolling forging. Its manufacturing method is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、靱性に優れた熱間工具鋼およびその製造方法に関するものである。   The present invention relates to a hot work tool steel having excellent toughness and a method for producing the same.
従来、熱間鍛造、アルミ押出し、ダイキャストでは、サイクルタイムの向上に伴い、金型の使用環境も苛酷になっており、金型寿命の向上が重要な課題になっている。金型寿命向上のため、様々な取り組みがなされてるが、なかでも熱間工具鋼の靱性改善は本質的に重要な課題である。そのための手段として、熱間工具鋼の靱性には、均質性、結晶粒度、清浄度、炭化物分布、マトリックス組織など様々な要因に影響されることが知られており、再溶解、ソーキング(均質化熱処理)、鍛錬比増、P/Sなどの不純物低減など様々な対策が行われている。   Conventionally, in hot forging, aluminum extrusion, and die casting, as the cycle time is improved, the usage environment of the mold has become severe, and improvement of the mold life has become an important issue. Various efforts have been made to improve the tool life, but in particular, improving the toughness of hot work tool steel is an essential issue. As a means for that, it is known that the toughness of hot tool steel is affected by various factors such as homogeneity, grain size, cleanliness, carbide distribution, matrix structure, remelting, soaking (homogenization) Various measures are taken, such as heat treatment), increasing the forging ratio, and reducing impurities such as P / S.
このように、成分変更、ソーキング(均質化熱処理)、再溶解法など様々な方法により靱性改善が図られているが、一方でコスト高、過剰品質になるなど市場のニーズに応えられていないのが実状である。また、金型寿命向上が必要な用途には、これまで成分を改良した開発鋼が使用されてきたが、金型加工時の切削性が劣るし、コスト高になるなど様々な欠点がある。そこで、特性バランスに優れ、汎用性の高いSKD61クラスの靱性向上が望まれてきた。   In this way, toughness has been improved by various methods such as component change, soaking (homogenization heat treatment), and remelting method, but on the other hand, it has not been able to meet market needs due to high cost and excessive quality. Is real. In addition, developed steels with improved components have been used for applications that require an increase in mold life. However, there are various drawbacks such as inferior machinability during mold processing and high costs. Therefore, it has been desired to improve the toughness of the SKD61 class, which has excellent property balance and high versatility.
例えば特開2004−269981号公報(特許文献1)「棒鋼の製造方法」に開示されているように、鍛造品と同等の靱性を有する棒鋼を分塊圧延で製造する方法であり、製造寸法に応じたソーキング(均質化熱処理)条件を規定している。すなわち、熱間ダイス鋼からなる鋼塊に対し、鋼種の状態図における固相線温度未満でかつ固相線温度より100℃低い温度より高い温度の温度域で、(1)目的とする棒鋼の直径が170〜200mmである場合には25時間以上、(2)目的とする棒鋼の直径が200〜250mmである場合には50時間以上の均熱処理を施し、分塊圧延して目的とする直径に整形する棒鋼の製造方法が提案されている。   For example, as disclosed in Japanese Patent Application Laid-Open No. 2004-269981 (Patent Document 1) “Manufacturing Method of Steel Bars”, it is a method of manufacturing a steel bar having toughness equivalent to that of a forged product by partial rolling. The corresponding soaking (homogenization heat treatment) conditions are specified. That is, for a steel ingot made of hot die steel, in the temperature range below the solidus temperature in the phase diagram of the steel type and higher than the temperature lower than the solidus temperature by 100 ° C., (1) When the diameter is 170 to 200 mm, 25 hours or more. (2) When the target steel bar has a diameter of 200 to 250 mm, a soaking treatment is performed for 50 hours or more, and the desired diameter is obtained by performing the batch rolling. There has been proposed a method of manufacturing a steel bar to be shaped into a flat shape.
また、特開2005−314788号公報(特許文献2)「靱性に優れた熱間工具鋼およびその製造方法」に開示されているように、質量%で、C:0.2〜0.7%、Cr:0.5〜7.0%を含有する熱間工具鋼において、Al:0.04%以下に規制され、かつ基地組成のCrの偏析度合いが±0.2質量%以内である靱性に優れた熱間工具鋼。
すなわち、合金元素の偏析度合い、窒化アルミニウムを規制しているものが提案されている。
特開2004−269981号公報 特開2005−314788号公報
Further, as disclosed in Japanese Patent Application Laid-Open No. 2005-314788 (Patent Document 2) “Hot Tool Steel Excellent in Toughness and Method for Producing the Same”, in mass%, C: 0.2 to 0.7% , Cr: Hot tool steel containing 0.5 to 7.0%, toughness with Al: 0.04% or less and the segregation degree of the base composition Cr is within ± 0.2 mass% Excellent hot work tool steel.
That is, what regulates the degree of segregation of alloy elements and aluminum nitride has been proposed.
JP 2004-269981 A JP 2005-314788 A
しかしながら、上述した特許文献1では、本発明で課題とした炭化物の分布に関しては全く考慮されていない。また、特許文献2では、合金元素の偏析度合い、窒化アルミニウムを規制しているものの、特許文献1と同様に、本発明で課題とした炭化物の分布に関しては全く考慮されていない。本発明は、コスト大の要因となる再溶解や長時間のソーキング(均質化熱処理)を行うことなく、炭化物分布およびミクロ偏析を最適化することにより、JIS−SKD61クラスの靱性向上を図ることにある。   However, in the above-mentioned Patent Document 1, no consideration is given to the distribution of carbides which is a problem in the present invention. Further, in Patent Document 2, although the segregation degree of alloy elements and aluminum nitride are regulated, as in Patent Document 1, no consideration is given to the distribution of carbides which is the subject of the present invention. The present invention aims to improve the toughness of the JIS-SKD61 class by optimizing the carbide distribution and microsegregation without performing remelting and soaking (homogenization heat treatment) that cause cost increase. is there.
熱間工具鋼の製造工程は溶解、凝固、ソーキング、圧延・鍛造、焼鈍からなり、金型として使用するときは、硬さが45〜54HRCになるように焼入れ焼戻しされる。また熱間工具鋼の靱性は焼入れ焼戻し状態で評価されるが、その材料特性は金型加工前の焼鈍まででほぼ決まる。本発明では、熱間工具鋼の靱性は焼鈍状態でほぼ決まり、炭化物分布、ミクロ偏析がその評価尺度になることを見出した。VARやESRなどの再溶解法とソーキングを組み合わせれば、均質な組織とすることができるが、コスト高となり、汎用性に欠ける。そこで大気溶解後、ソーキング、圧鍛条件を最適化することで組織を最適化し、靱性向上を図った。ここで圧鍛とは、分塊圧延、鍛造、圧延によるものを言う。   The manufacturing process of hot tool steel consists of melting, solidification, soaking, rolling / forging, and annealing, and when used as a mold, it is quenched and tempered so that the hardness is 45 to 54 HRC. Further, the toughness of hot tool steel is evaluated in the quenched and tempered state, but the material properties are almost determined by the annealing before the mold processing. In the present invention, it has been found that the toughness of hot tool steel is almost determined in the annealed state, and carbide distribution and microsegregation are the evaluation scale. If a solubilization method such as VAR or ESR is combined with a soaking, a homogeneous structure can be obtained, but the cost is high and the versatility is lacking. Therefore, the structure was optimized and the toughness was improved by optimizing soaking and forging conditions after dissolution in the atmosphere. Here, the pressure forging refers to a method by partial rolling, forging, or rolling.
また、ソーキングは高温・長時間で処理するほど合金元素が拡散し、均質な組織になることが知られているが、一方で、コスト高の要因となる。そこで、適切なソーキング条件を設定した。さらに、炭化物の分布状態は、最終的には焼鈍で決まるが、実際には圧鍛条件によってその分布状態が左右されることを見出し、圧鍛加熱温度、圧鍛終止温度、圧鍛後の冷却速度を規定することで均一な炭化物の分散が得られるようにして発明を完成したものである。   In addition, it is known that soaking is performed at a high temperature and for a long time, so that the alloy element diffuses and becomes a homogeneous structure. Therefore, appropriate soaking conditions were set. Furthermore, the distribution state of carbides is ultimately determined by annealing, but in reality, the distribution state depends on the forging conditions, and it is found that the forging heating temperature, the forging end temperature, and the cooling after forging. The invention has been completed in such a manner that uniform carbide dispersion can be obtained by defining the speed.
その発明の要旨とするところは、
(1)質量%で、C:0.30〜0.50%、Cr:4.0〜5.5%、Mo:0.5〜2.0%、V:0.5〜1.5%がFeと不可避的不純物から成る鋼を、圧鍛加熱温度950〜1250℃にて圧延鍛造し、その圧鍛終止温度を900〜1150℃とした後、該圧鍛後の冷却速度0.05℃/sec以上にて焼鈍してなることを特徴とする高靱性熱間工具鋼。
(2)質量%で、Si:0.3〜1.2%、Mn:0.30〜0.60%、Ni:0.04〜0.15%、Cu:≦0.20%、Al:0.001〜0.020%の内の1種または2種以上を含有することを特徴とする前記(1)に記載の高靱性熱間工具鋼。
(3)質量%で、C:0.30〜0.50%、Cr:4.0〜5.5%、Mo:0.5〜2.0%、V:0.5〜1.5%、残部がFeと不可避的不純物から成る鋼を鋳造後、温度1150〜1300℃、10〜100時間でのソーキングを行い、引続き圧鍛加熱温度950〜1250℃にて圧延鍛造し、その圧鍛終止温度を900〜1150℃とした後、該圧鍛後の冷却速度0.05℃/sec以上にて焼鈍してなることを特徴とする高靱性熱間工具鋼の製造方法。
(4)質量%で、Si:0.3〜1.2%、Mn:0.30〜0.60%、Ni:0.04〜0.15%、Cu:≦0.20%、Al:0.001〜0.020%の内の1種または2種以上を含有することを特徴とする前記(3)に記載の高靱性熱間工具鋼の製造方法にある。
The gist of the invention is that
(1) By mass%, C: 0.30 to 0.50%, Cr: 4.0 to 5.5%, Mo: 0.5 to 2.0%, V: 0.5 to 1.5% Is formed by rolling and forging a steel composed of Fe and inevitable impurities at a forging heating temperature of 950 to 1250 ° C., and setting the end temperature of the forging to 900 to 1150 ° C., and then cooling rate after the forging is 0.05 ° C. High toughness hot work tool steel, characterized by annealing at / sec or more.
(2) By mass%, Si: 0.3-1.2%, Mn: 0.30-0.60%, Ni: 0.04-0.15%, Cu: ≦ 0.20%, Al: The high toughness hot tool steel according to (1) above, containing one or more of 0.001 to 0.020%.
(3) By mass%, C: 0.30 to 0.50%, Cr: 4.0 to 5.5%, Mo: 0.5 to 2.0%, V: 0.5 to 1.5% Then, after casting steel composed of Fe and inevitable impurities, soaking at a temperature of 1150 to 1300 ° C. for 10 to 100 hours, followed by rolling forging at a pressure forging heating temperature of 950 to 1250 ° C., the end of the forging A method for producing high toughness hot work tool steel, characterized by annealing at a cooling rate of 0.05 ° C./sec or more after the forging after setting the temperature to 900 to 1150 ° C.
(4) In mass%, Si: 0.3-1.2%, Mn: 0.30-0.60%, Ni: 0.04-0.15%, Cu: ≦ 0.20%, Al: It exists in the manufacturing method of the high toughness hot tool steel as described in said (3) characterized by containing 1 type, or 2 or more types in 0.001-0.020%.
以上述べたように、本発明による圧鍛条件の最適化による炭化物の均一分散化および合金元素のミクロ偏析を判定して製造条件に反映させ、低コストで信頼性の高い熱間工具鋼およびその製造方法を提供する。   As described above, the uniform dispersion of carbides by optimization of the forging conditions according to the present invention and the microsegregation of the alloy elements are judged and reflected in the production conditions, and the hot tool steel with high reliability at low cost and its A manufacturing method is provided.
以下、本発明に係る成分組成の限定理由について説明する。   Hereinafter, the reasons for limiting the component composition according to the present invention will be described.
C:0.30〜0.50%
Cは、焼入れ性と硬さおよび強度の確保に寄与する重要な元素であることから、本発明の対象を熱間工具とする場合には、特に本発明の有用性を向上させる。しかし、0.30%未満ではその効果が十分でなく、また、0.50%を超えると靱性、熱間加工性を低下させることから、その上限を0.50%とした。好ましくは0.35〜0.45%とする。
C: 0.30 to 0.50%
Since C is an important element that contributes to ensuring hardenability, hardness, and strength, the utility of the present invention is particularly improved when the object of the present invention is a hot tool. However, if it is less than 0.30%, the effect is not sufficient, and if it exceeds 0.50%, the toughness and hot workability are lowered, so the upper limit was made 0.50%. Preferably it is 0.35 to 0.45%.
Cr:4.0〜5.5%
Crは、鋼の焼入れ性を高めて硬度および強度に寄与する元素である。しかし、4.0%未満ではその効果が十分でなく、また、5.5%を超えると靱性を低下させることから、その上限を5.5%とした。
Cr: 4.0 to 5.5%
Cr is an element that increases the hardenability of steel and contributes to hardness and strength. However, if it is less than 4.0%, the effect is not sufficient, and if it exceeds 5.5%, the toughness is lowered, so the upper limit was made 5.5%.
Mo:0.5〜2.0%
Moは、炭化物を形成して基地の強度や硬さおよび耐熱性を向上させる効果を持つ元素である。しかし、0.5%未満ではその効果が十分でなく、また、2.0%を超えると靱性、熱間加工性を低下させることから、その上限を2.0%とした。
Mo: 0.5-2.0%
Mo is an element that has the effect of forming carbides and improving the strength, hardness and heat resistance of the matrix. However, if it is less than 0.5%, the effect is not sufficient, and if it exceeds 2.0%, the toughness and hot workability are lowered, so the upper limit was made 2.0%.
V:0.5〜1.5%
Vは、炭化物を形成し、基地の強度や硬さおよび耐熱性を向上させる効果を持つ元素である。しかし、0.5%未満ではその効果が十分でなく、また、1.5%を超えると靱性、熱間加工性を低下させることから、その上限を1.5%とした。
V: 0.5 to 1.5%
V is an element that forms carbides and has the effect of improving the strength, hardness and heat resistance of the matrix. However, if it is less than 0.5%, the effect is not sufficient, and if it exceeds 1.5%, the toughness and hot workability are lowered, so the upper limit was made 1.5%.
なお、本発明の熱間工具鋼の成分組成は、上記の成分を含む以外には、例えば必要に応じて、Si,Mn,Ni,Cu,Alなどを添加することができ、また、P,S,N,Oを規制することができる。   In addition, the component composition of the hot work tool steel of the present invention can include, for example, Si, Mn, Ni, Cu, Al, etc., if necessary, other than the above components. S, N, and O can be regulated.
Si:0.3〜1.2%
Siは、脱酸剤として有用であり、本発明においては靱性向上のために脱酸剤として最も多用されるAlを0.020%以下に抑える必要があるので、脱酸剤としてSiを用いる。そのためには0.3%以上の添加が必要である。しかし、1.2%を超えると靱性、熱間加工性を低下させることから、その上限を1.2%とした。
Si: 0.3-1.2%
Si is useful as a deoxidizing agent, and in the present invention, it is necessary to suppress Al, which is most frequently used as a deoxidizing agent, in order to improve toughness, so that Si is used as a deoxidizing agent. For that purpose, addition of 0.3% or more is necessary. However, if it exceeds 1.2%, the toughness and hot workability are lowered, so the upper limit was made 1.2%.
Mn:0.30〜0.60%
Mnは、Siと同様に、脱酸元素であり、0.30%未満ではその効果が十分でなく、0.60%を超えると靱性、熱間加工性を低下させることから、その上限を0.60%とした。
Mn: 0.30 to 0.60%
Like Si, Mn is a deoxidizing element, and if it is less than 0.30%, its effect is not sufficient, and if it exceeds 0.60%, the toughness and hot workability are lowered. 60%.
Ni0.04〜0.15%
Niは、焼入れ性および靱性を向上させる元素であり、0.04%以上の添加が必要である。しかし、0.15%を超えると高温強度を低下させることから、0.15%とした。
Ni 0.04-0.15%
Ni is an element that improves hardenability and toughness, and needs to be added in an amount of 0.04% or more. However, if it exceeds 0.15%, the high temperature strength is lowered, so the content was made 0.15%.
Cu:≦0.20%
Cuは、靱性を低下させることから、その上限を0.20%以下とした。
Cu: ≦ 0.20%
Since Cu reduces toughness, the upper limit was made 0.20% or less.
Al:0.001〜0.020%
Alは、精錬時に脱酸元素として使用される。しかし、0.001%未満ではその効果は十分でなく、また、0.020%を超えるとAlN形成して靱性を劣化させることから、その上限を0.020%とする。
Al: 0.001 to 0.020%
Al is used as a deoxidizing element during refining. However, if it is less than 0.001%, the effect is not sufficient, and if it exceeds 0.020%, AlN is formed and the toughness is deteriorated, so the upper limit is made 0.020%.
P:≦0.021%、S:≦0.009%、N≦204ppm,O≦20ppm
P,S,NおよびOは、いずれも靱性を劣化させることから、その上限をそれぞれ0.021%以下、0.009%以下、204ppm、20ppm以下とした。
P: ≦ 0.021%, S: ≦ 0.009%, N ≦ 204 ppm, O ≦ 20 ppm
Since P, S, N, and O all deteriorate toughness, the upper limit is set to 0.021% or less, 0.009% or less, 204 ppm, or 20 ppm or less, respectively.
圧鍛加熱温度950〜1250℃ 圧鍛加熱温度を950〜1250℃としたのは、熱間加工をするためには950℃以上必要である。しかし、1250℃を超えると結晶粒が大きくなり、焼鈍時に炭化物が不均一に分布し靱性を低下させることから、その範囲を950〜1250℃とした。好ましくは1000〜1150℃とする。   Forging heating temperature 950 to 1250 ° C The forging heating temperature is set to 950 to 1250 ° C in order to perform hot working at 950 ° C or more. However, when the temperature exceeds 1250 ° C., the crystal grains become large, and carbides are unevenly distributed during annealing to lower the toughness. Therefore, the range is set to 950 to 1250 ° C. Preferably it is 1000-1150 degreeC.
圧鍛終止温度を900〜1150℃
圧鍛終止温度を900℃としたのは、熱間加工をするためには900℃以上必要な温度である。しかし、1150℃を超えると再結晶による結晶粒微細化の効果がなくなり、焼鈍時に炭化物が不均一に分布し易くなるために、その上限を1150℃とした。好ましくは950〜1100℃とする。
The forging end temperature is 900-1150 ° C.
The end temperature of the forging is set to 900 ° C., which is a temperature necessary to be 900 ° C. or higher for hot working. However, if the temperature exceeds 1150 ° C., the effect of refining crystal grains by recrystallization is lost, and the carbide tends to be unevenly distributed during annealing, so the upper limit was set to 1150 ° C. Preferably it is set to 950-1100 degreeC.
圧鍛後の冷却速度0.05℃/sec以上
圧鍛後の冷却速度0.05℃/sec以上としたのは、圧延後に緩冷却すると、粗いベイナイトが生成し、焼鈍時に炭化物が不均一に析出する。炭化物の不均一な分布は靱性を低下させる。すなわち、一定以上の速度で冷却すると、マルテンサイトまたは細かいベイナイトになり、焼鈍時に炭化物が均一に分散し易くなるためである。望ましくは0.1℃/sec以上とする。
Cooling rate after forging 0.05 ° C / sec or more The cooling rate after forging 0.05 ° C / sec or more is that when gradual cooling is performed after rolling, coarse bainite is generated, and carbides are not uniform during annealing. Precipitate. The uneven distribution of carbides reduces toughness. That is, when it is cooled at a certain speed or higher, it becomes martensite or fine bainite, and carbides are easily dispersed uniformly during annealing. Desirably, it is set to 0.1 ° C./sec or more.
ソーキング温度1150〜1300℃、10〜100時間
ソーキング温度1150℃未満、10時間未満では成分変動幅を小さくするには不十分である。しかし、ソーキング温度1300℃を超え、100時間を超えると拡散効果が飽和し、コスト高となることから、その上限を1300℃、100時間とした。
A soaking temperature of 1150 to 1300 ° C. for 10 to 100 hours and a soaking temperature of less than 1150 ° C. and less than 10 hours are insufficient to reduce the component fluctuation range. However, when the soaking temperature exceeds 1300 ° C. and exceeds 100 hours, the diffusion effect is saturated and the cost is increased. Therefore, the upper limit is set to 1300 ° C. and 100 hours.
以下、本発明に係る実施例によって具体的に説明する。
表1に示すような供試材の化学成分をもつ鋼を誘導溶解炉で溶製し、その溶鋼を鋳型にて凝固させ、1〜20t鋼塊を製造した。その鋼塊の高幅比(高さ/平均径)=2.0〜4.0、傾斜比〔(上部径−下部径)/高さ(mm/M)〕=30〜120のものを供試材とした。また、処理条件については、表2に示すように、ソーキング温度1150〜1300℃、時間10〜100時間で調整した。圧鍛は分塊圧延、鋳造、圧延によるものである。また、焼鈍は800〜950℃で1〜30時間、加熱保持後、1〜30℃/時間で冷却した。その結果を表2に示す。
Hereinafter, the present invention will be described in detail by way of examples.
Steels having the chemical components of the test materials as shown in Table 1 were melted in an induction melting furnace, and the molten steel was solidified in a mold to produce 1 to 20 t steel ingots. The steel ingot has a high width ratio (height / average diameter) = 2.0 to 4.0 and a slope ratio [(upper diameter−lower diameter) / height (mm / M)] = 30 to 120. Samples were used. Moreover, about the process conditions, as shown in Table 2, it adjusted by soaking temperature 1150-1300 degreeC and time 10 to 100 hours. Forging is by split rolling, casting, or rolling. Moreover, annealing was cooled at 1 to 30 ° C./hour after heating and holding at 800 to 950 ° C. for 1 to 30 hours. The results are shown in Table 2.
表2に示す炭化物分布状況は400倍の光学顕微鏡にて判定した。また、焼入焼戻し条件は焼入れ温度1010〜1050℃−0.5時間保持、空冷または油冷、焼戻条件は550〜650℃−1時間保持後空冷を2回以上行った。その評価としての炭化物分布状態については、炭化物の均一分散の良好なものを○とし、悪いものを×で表示した。さらに、シャルピー衝撃値はT面ノッチ、2mmUノッチでの値を示す。 The carbide distribution status shown in Table 2 was determined with a 400 × optical microscope. Further, quenching and tempering conditions were maintained at a quenching temperature of 1010 to 1050 ° C. for 0.5 hours, air cooling or oil cooling, and tempering conditions were maintained at 550 to 650 ° C. for 1 hour and then air cooling was performed twice or more. With respect to the carbide distribution state as an evaluation thereof, a good one with uniform dispersion of the carbides was indicated by ◯, and a bad one was indicated by x. Further, the Charpy impact value is a value at a T-plane notch and 2 mmU notch.
表2に示すように、鋼種A−2,3、B−2,3、C−2、D−2,3、E−2、F−2、G−2、H−2、I−2は比較例であって、比較例鋼種A−2は圧鍛加熱温度が高いために、炭化物分布状態の均一分散化が悪く、かつT方向シャルピー衝撃値が低い。比較例鋼種A−3はソーキング温度が高いために、炭化物分布状態の均一分散化が悪く、かつT方向シャルピー衝撃値が低い。比較例鋼種B−2はソーキング時間が短く、かつ、圧鍛終止温度が低いために、炭化物分布状態の均一分散化が悪く、かつT方向シャルピー衝撃値が低い。比較例鋼種B−3は圧鍛加熱温度が低いために、炭化物分布状態の均一分散化が悪く、かつ鋼材に割れた。   As shown in Table 2, steel types A-2, 3, B-2, 3, C-2, D-2, 3, E-2, F-2, G-2, H-2, and I-2 are Since it is a comparative example and comparative example steel type A-2 has a high pressure forging heating temperature, the uniform distribution of the carbide distribution state is poor and the T-direction Charpy impact value is low. Since the comparative example steel type A-3 has a high soaking temperature, the uniform distribution of the carbide distribution state is poor, and the T-direction Charpy impact value is low. Since comparative steel type B-2 has a short soaking time and a low pressure forging end temperature, the uniform distribution of the carbide distribution state is poor and the T-direction Charpy impact value is low. Since the comparative example steel type B-3 had a low pressure forging heating temperature, the uniform distribution of the carbide distribution state was poor and the steel material was cracked.
比較例鋼種C−2はソーキング温度が低いために、T方向シャルピー衝撃値が低い。比較例鋼種D−2は圧鍛後冷却速度が遅いために、炭化物分布状態の均一分散化が悪く、かつT方向シャルピー衝撃値が低い。比較例鋼種D−3は圧鍛終止温度が高いために、炭化物分布状態の均一分散化が悪く、かつT方向シャルピー衝撃値が低い。比較例鋼種E−2はソーキング時間が長過ぎるためにコストが大きい。F−2はソーキング温度が高いために、炭化物分布状態の均一分散化が悪い。G−2は圧鍛加熱温度が低いために、炭化物分布状態の均一分散化が悪い。H−2はソーキング時間が短く、かつ圧鍛終止温度が低いために、炭化物分布状態の均一分散化が悪い。I−2は圧鍛終止温度が高いために、炭化物分布状態の均一分散化が悪いことがそれぞれ分かる。   Since the comparative steel type C-2 has a low soaking temperature, the T-direction Charpy impact value is low. Since comparative example steel type D-2 has a slow cooling rate after forge, the uniform distribution of the carbide distribution state is poor and the T-direction Charpy impact value is low. Since the comparative example steel type D-3 has a high pressure forging end temperature, uniform distribution of the carbide distribution state is poor and the T-direction Charpy impact value is low. The comparative steel type E-2 is expensive because the soaking time is too long. Since F-2 has a high soaking temperature, uniform distribution of the carbide distribution state is poor. Since G-2 has a low pressure forging heating temperature, the uniform distribution of the carbide distribution state is poor. Since H-2 has a short soaking time and a low pressure forging end temperature, uniform distribution of the carbide distribution state is poor. It can be seen that I-2 is poor in uniform distribution of the carbide distribution state because of the high end pressure forging.
これに対して、本発明例である鋼種A−1、B−1、C−1、D−1、E−1、F−1、G−1、H−1、I−1については、いずれも本発明の条件を満足していることから、炭化物分布状態の均一分散化が図られ良好な炭化物分布状態が得られ、しかも焼入焼戻後の硬さ、並びにT方向シャルピー衝撃値の高いことが分かる。   On the other hand, about steel types A-1, B-1, C-1, D-1, E-1, F-1, G-1, H-1, and I-1 which are examples of the present invention, Since the conditions of the present invention are satisfied, uniform distribution of the carbide distribution state is achieved and a good carbide distribution state is obtained, and the hardness after quenching and tempering and the T-direction Charpy impact value are high. I understand that.
上述したように、本発明による衝撃値に及ぼす炭化物分布、ミクロ偏析の影響および圧鍛条件、ソーキング条件を最適にすることで、低コストで信頼性の高い熱間工具鋼を得ることが出来る極めて優れた効果を奏するものである。


特許出願人 山陽特殊製鋼株式会社
代理人 弁理士 椎 名 彊
As described above, by optimizing the carbide distribution, the effect of micro-segregation and the forging and soaking conditions on the impact value according to the present invention, it is possible to obtain a hot tool steel with high reliability at low cost. It has an excellent effect.


Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina

Claims (4)

  1. 質量%で、
    C:0.30〜0.50%、
    Cr:4.0〜5.5%、
    Mo:0.5〜2.0%、
    V:0.5〜1.5%、 残部がFeと不可避的不純物から成る鋼を、圧鍛加熱温度950〜1250℃にて圧延鍛造し、その圧鍛終止温度を900〜1150℃とした後、該圧鍛後の冷却速度0.05℃/sec以上にて焼鈍してなることを特徴とする高靱性熱間工具鋼。
    % By mass
    C: 0.30 to 0.50%,
    Cr: 4.0 to 5.5%,
    Mo: 0.5 to 2.0%,
    V: 0.5 to 1.5% After the steel consisting of the balance Fe and inevitable impurities is rolled and forged at a pressure forging heating temperature of 950 to 1250 ° C., and the pressure forging end temperature is set to 900 to 1150 ° C. A high toughness hot tool steel characterized by being annealed at a cooling rate of 0.05 ° C./sec or more after the forge.
  2. 質量%で、
    Si:0.3〜1.2%、
    Mn:0.30〜0.60%、
    Ni:0.04〜0.15%、
    Cu:≦0.20%、
    Al:0.001〜0.020%
    の内の1種または2種以上を含有することを特徴とする請求項1に記載の高靱性熱間工具鋼。
    % By mass
    Si: 0.3-1.2%
    Mn: 0.30 to 0.60%
    Ni: 0.04 to 0.15%,
    Cu: ≦ 0.20%
    Al: 0.001 to 0.020%
    The high toughness hot tool steel according to claim 1, comprising one or more of the above.
  3. 質量%で、
    C:0.30〜0.50%、
    Cr:4.0〜5.5%、
    Mo:0.5〜2.0%、
    V:0.5〜1.5%、 残部がFeと不可避的不純物から成る鋼を鋳造後、温度1150〜1300℃、10〜100時間でのソーキングを行い、引続き圧鍛加熱温度950〜1250℃にて圧延鍛造し、その圧鍛終止温度を900〜1150℃とした後、該圧鍛後の冷却速度0.05℃/sec以上にて焼鈍してなることを特徴とする高靱性熱間工具鋼の製造方法。
    % By mass
    C: 0.30 to 0.50%,
    Cr: 4.0 to 5.5%,
    Mo: 0.5 to 2.0%,
    V: 0.5 to 1.5%, the balance is Fe and inevitable impurities. After casting, the steel is soaked at a temperature of 1150 to 1300 ° C for 10 to 100 hours, and then the forging heating temperature is 950 to 1250 ° C. A high toughness hot tool characterized by being rolled and forged at an end temperature of 900 to 1150 ° C. and then annealed at a cooling rate of 0.05 ° C./sec or more after the forge. Steel manufacturing method.
  4. 質量%で、
    Si:0.3〜1.2%、
    Mn:0.30〜0.60%、
    Ni:0.04〜0.15%、
    Cu:≦0.20%、
    Al:0.001〜0.020%
    の内の1種または2種以上を含有することを特徴とする請求項3に記載の高靱性熱間工具鋼の製造方法。
    % By mass
    Si: 0.3-1.2%
    Mn: 0.30 to 0.60%
    Ni: 0.04 to 0.15%,
    Cu: ≦ 0.20%
    Al: 0.001 to 0.020%
    The manufacturing method of the high toughness hot tool steel of Claim 3 containing 1 type (s) or 2 or more types of these.
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JP6004142B2 (en) * 2014-07-23 2016-10-05 日立金属株式会社 Hot tool material, hot tool manufacturing method and hot tool
JP2017155306A (en) * 2016-03-03 2017-09-07 山陽特殊製鋼株式会社 Hot tool steel having excellent high temperature strength and toughness
JP2018031045A (en) * 2016-08-23 2018-03-01 株式會社三共合金鑄造所 Liner material for red-hot coke transportation buckets and method for producing the same
CN107904510A (en) * 2017-11-21 2018-04-13 重庆文理学院 Comprehensive high performance hot die steel of one kind and preparation method thereof

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* Cited by examiner, † Cited by third party
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CN105002337A (en) * 2015-07-21 2015-10-28 北京奥普科星技术有限公司 H13 die steel heat treating method and H13 die steel obtained through same

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JPH0297619A (en) * 1988-09-30 1990-04-10 Sumitomo Metal Ind Ltd Method for forming low-alloy steel for high-temperature service
JPH1161362A (en) * 1997-08-14 1999-03-05 Sanyo Special Steel Co Ltd Tool steel for hot working
JP2003286545A (en) * 2002-03-28 2003-10-10 Nippon Koshuha Steel Co Ltd Hot-working tool steel

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JPH0297619A (en) * 1988-09-30 1990-04-10 Sumitomo Metal Ind Ltd Method for forming low-alloy steel for high-temperature service
JPH1161362A (en) * 1997-08-14 1999-03-05 Sanyo Special Steel Co Ltd Tool steel for hot working
JP2003286545A (en) * 2002-03-28 2003-10-10 Nippon Koshuha Steel Co Ltd Hot-working tool steel

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Publication number Priority date Publication date Assignee Title
JP6004142B2 (en) * 2014-07-23 2016-10-05 日立金属株式会社 Hot tool material, hot tool manufacturing method and hot tool
JP2017155306A (en) * 2016-03-03 2017-09-07 山陽特殊製鋼株式会社 Hot tool steel having excellent high temperature strength and toughness
JP2018031045A (en) * 2016-08-23 2018-03-01 株式會社三共合金鑄造所 Liner material for red-hot coke transportation buckets and method for producing the same
CN107904510A (en) * 2017-11-21 2018-04-13 重庆文理学院 Comprehensive high performance hot die steel of one kind and preparation method thereof

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