JP4123618B2 - Hot work tool steel with excellent high temperature strength and toughness - Google Patents
Hot work tool steel with excellent high temperature strength and toughness Download PDFInfo
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【０００１】
【発明の属する技術分野】
本発明は、例えば熱間鍛造用金型、押し出し型、ダイカスト金型の使用に適した、高温強度と靱性に優れた熱間工具鋼に関するものである。
【０００２】
【従来の技術】
熱間での鍛造、押し出し、ダイカスト等の金型に使用される工具鋼は、使用時の熱応力や作業応力によるヒートチェックの発生、大割れ、摩耗に耐え得るだけの十分な高温強度と靱性が要求される。
【０００３】
【発明が解決しようとする課題】
熱間工具鋼としては、ＪＩＳ Ｇ ４４０４に多種類のものが規定されているが、中でも５Ｃｒ−Ｍｏ−Ｖ系のＳＫＤ６１やＳＫＤ６２等、３Ｃｒ−３Ｍｏ−Ｖ系のＳＫＤ７、及び、Ｎｉ−Ｃｒ−Ｍｏ−Ｖ系の低合金鋼であるＳＫＴ３やＳＫＴ４等が多用されている。しかしながら、これらの工具鋼では前記の要求される高温強度と靱性を共に満足することは不可能である。
【０００４】
そこで、本出願人は、Ｂを添加することにより、靱性の低下を伴わずに焼戻し後の高温強度を上昇させるものを、特開平８−２６９６２５号で開示している。また、本出願人は、特願平１０−７４３４６号で、焼入時のマルテンサイト組織にベイナイト組織を混合させることによって、マルテンサイト組織に比べて靱性は若干低下するものの、焼戻し後の高温強度を上昇させるものを提案している。しかしながら、これらにあっても、用途によっては、前記の要求される特性を得るには不十分である。
【０００５】
本発明は、上記した現状に鑑みてなされたものであり、高温強度と靱性が共に優れた熱間工具鋼を提供することを目的としている。
【０００６】
【課題を解決するための手段】
上記した目的を達成するために、本発明の高温強度と靱性に優れた熱間工具鋼は、Ｂを添加すると共に、焼入時の組織がマルテンサイト＋ベイナイトで、そのうちのベイナイト率が５〜８０％とすることとしている。そして、このようにすることで、高温強度と靱性を高いレベルで両立させることができる。
【０００７】
【発明の実施の形態】
高温強度を上昇させるために、Ｂを添加したり、焼入時のマルテンサイト組織にベイナイト組織を混合させることが有効であることは、上記した特開平８−２６９６２５号や特願平１０−７４３４６号によって判明しているが、本発明者らのその後の研究により、ある特定範囲のベイナイト率のときには、夫々の単独の技術では成し得なかった高温強度レベルが得られることを知見した。
【０００８】
すなわち、焼入組織へのベイナイトの混合比率を増加させることによって、マルテンサイト組織に比べて靱性が若干低下するものの高温強度を上昇させることができるのは、ベイナイトとマルテンサイトから析出する炭化物の形態に起因している。すなわち、焼戻し後のベイナイトは、マルテンサイトと比較すると、粗大な炭化物が析出するので、靱性が低下するものの、Ｍｏ2 Ｃが微細析出するので、高温強度が上昇するからである。一方、Ｂを添加した場合には、炭化物を微細に析出させる効果があり、高温強度の低下を抑えることになる。
【０００９】
しかしながら、ベイナイト率が０〜４％と低い場合には、ベイナイトからの微細炭化物の析出量が少ないので、高温強度を上昇させる効果が小さい。反対に、ベイナイトの混合率が８０％を超えると、微細な炭化物量は増加するものの、粗大な炭化物も多くなるので、靱性を大きく低下させると考えられる。つまり、ベイナイトの混合率が５〜８０％の場合に、Ｂを添加した場合には、粗大な炭化物量が少なく、微細な炭化物量が多くなって、図１に示すように、高温強度と靱性を高いレベルで両立させることができる。
【００１０】
本発明の高温強度と靱性に優れた熱間工具鋼は、上記知見に加え、その他の元素の影響を調査した結果に基づいて成されたものであり、重量％で、Ｃ：０．２５〜０．４０％、Ｓｉ：０．１０〜１．００％未満、Ｍｎ：０．３０〜１．５０％、Ｎｉ：１．０７〜２．００％、Ｃｒ：２．７０〜５．５０％、Ｍｏ：２．１８〜３．００％、Ｖ：０．５０％を超え、１．００％以下、Ｂ：０．０００５〜０．０１００％、Ａｌ：０．００５〜０．１０％未満を含有し、残部はＦｅ及び不可避的不純物で、不純物中のＰは０．０１５％以下、Ｓは０．００５％以下、Ｎは０．０１５％以下であり、かつ、焼入時の組織がマルテンサイト＋ベイナイトで、そのうちのベイナイト率が５〜８０％であること要旨とするものである。
【００１１】
以下に、本発明の高温強度と靱性に優れた熱間工具鋼における成分組成を限定する理由について説明する。
Ｃ：Ｃは鋼の焼入性を高め、靱性を向上させ、焼戻し時に炭窒化物として二次析出して高温強度を向上させる作用を有する。しかし、その含有量が０．２５％未満では添加効果が乏しく、０．４０％を超えて含有させると、被削性の低下を引き起こすため、本発明ではその含有量を０．２５〜０．４０％とした。
【００１２】
Ｓｉ：Ｓｉは鋼の被削性を向上する作用を有する。しかし、その含有量が０．１０％未満では添加効果に乏しく、１．００％以上であると靱性、高温強度を共に低下させて熱間工具寿命の低下を引き起こす。そこで、本発明ではその含有量を０．１０〜１．００％未満とした。特に望ましい範囲は０．１０〜０．３０％未満である。
【００１３】
Ｍｎ：Ｍｎは鋼の焼入性を向上させて靱性を高めるのに有効な元素である。しかし、その含有量が０．３０％未満では添加効果が得られず、１．５０％を超えると偏析が生じて靱性、強度を低下するようになるので、本発明ではその含有量を０．３０〜１．５０％とした。
【００１４】
Ｎｉ：ＮｉもＭｎと同様に焼入性を向上させて靱性を改善するのに有効な元素であるが、その含有量が１．０７％未満ではその効果が乏しく、２．００％を超えると変態点を下げて高温強度の低下を招く。従って、本発明ではその含有量を１．０７〜２．００％とした。
【００１５】
Ｃｒ：Ｃｒは靱性、耐摩耗性の向上に有効な元素であるが、その含有量が２．７０％未満では十分な効果が得られず、５．５０％を超えると高温強度の低下を招くようになるので、本発明ではその含有量を２．７０〜５．５０％とした。より望ましい範囲は、３．５０〜４．５０％である。
【００１６】
Ｍｏ：Ｍｏは鋼の焼入性と焼戻し軟化抵抗を向上させて、靱性と高温強度を高める作用を有する。しかし、その含有量が２．１８％未満では添加効果が得られない。一方、３．００％を超えると被削性、靱性が低下する。従って、本発明ではその含有量を２．１８〜３．００％とした。
【００１７】
Ｖ：Ｖは高温強度を高めるのに必要な元素である。Ｖの含有量が０．５０％未満であるとその効果が乏しく、１．００％以上では被削性と靱性を悪化させる。そこで、本発明ではその含有量を０．５０％を超え、１．００％以下とした。
【００１８】
Ｂ：Ｂは鋼中で固溶Ｂを形成し、高温時の炭化物の粒成長を抑制し、高温強度の低下を防止する。しかし、０．０００５％未満ではその効果が得られず、０．０１００％を超えると靱性が低下するので、本発明ではその含有量を０．０００５〜０．０１００％とした。
【００１９】
Ａｌ：Ａｌは鋼の脱酸の安定化及び均質化を図るのに有効な元素であり、その含有量が０．００５％未満ではその効果を得ることができない。また、０．１０％以上では被削性の低下や鋼中の地きずの原因となる。そのため、本発明ではその含有量を０．００５〜０．１０％未満とした。
【００２０】
本発明の熱間工具鋼では、不純物元素としてのＰ，Ｓ及びＮの含有量を夫々下記の通り規制する。
Ｐ：Ｐは含有量が多いと偏析が大きくなり、靱性の低下や熱亀裂の発生を助長するので、その含有量は可能な限り少ないことが望ましい。そこで、本発明ではその含有量を０．０１５％以下に限定した。
【００２１】
Ｓ：Ｓは硫化物を形成し、被削性を向上させるが、靱性を低下させるので、含有量は可能な限り少ないことが望ましい。そこで、本発明ではその含有量を０．００５％以下に限定した。
【００２２】
Ｎ：ＮはＶと窒化物を形成して焼入加熱時の固溶Ｖ量を減少させる。固溶Ｖ量が少ないと焼戻し時に二次析出するＶ炭窒化物の量が減少し、高温強度が低下する。そこで、本発明ではその含有量を０．０１５％以下に限定した。
【００２３】
焼入組織：本発明が対象とする焼入時の組織はマルテンサイトとベイナイトの混合組織に限定される。この時の混合組織のベイナイトの混合比率を示すベイナイト率は、厚さ１０ｍｍの素材を焼入れする際に、水冷した場合の素材の硬さをＨ１、室温まで２０時間かけて冷却した場合の素材の硬さをＨ２とし、実際に熱処理をしたときの素材の硬さをＨとしたとき、下記の▲１▼式によって算出される。なお、硬さはビッカース硬さで表示する。
ベイナイト率（％）＝１００−（Ｈ−Ｈ２）／（Ｈ１−Ｈ２）×１００…▲１▼
【００２４】
本発明者らの実験によれば、図１に示したように、ベイナイト率が０（１００％マルテンサイト）〜４％のときは、Ｂを添加しても、高温強度の低下が著しく、反対に、ベイナイト率が８０％を超えるときは、Ｂ添加による高温強度の低下の抑制効果がなく、しかも、靱性の低下をも招く。そこで、本発明ではベイナイト率を５〜８０％に限定した。
【００２５】
【実施例】
本発明の熱間工具鋼の効果を実施例に基づいて説明する。
下記表１に示す成分組成を有する本発明鋼（Ｎｏ．２８、Ｎｏ．３０〜３２、Ｎｏ．３５〜３７）、並びに、＊印を付した成分が本発明で規定する範囲から外れる比較鋼（Ｎｏ．１〜Ｎｏ．２１及びＮｏ．３８〜Ｎｏ．５１、このうちＮｏ．１６はＪＩＳ ＳＫＤ６１）を、電気炉で溶製して得た鋼塊を分塊し、鍛錬比５以上で鍛造した後、８００〜８５０℃で焼鈍した。焼入組織を変化させるために、厚さを１０〜８００ｍｍにし、９００〜１０５０℃から水冷、油冷、炉冷により焼入を実施した。そして、引き続き、焼戻しを５５０〜６４０℃で行い、硬さＨＳ５５〜６０に調整して金型を製造し、高温強度試験と破壊靱性試験を実施した。このうち、高温強度試験は、ＪＩＳ １４Ａ 号試験片（直径Ｄ＝６ｍｍ）にて、ＪＩＳ Ｇ ０５６７に準拠し、７００℃の試験温度で行い、０．２％耐力を測定した。また、破壊靱性試験は、ＡＳＴＭ Ｅ３９９ ８３に準じて測定した。
【００２６】
経験的に、破壊靱性値が１００ｋｇｆ／ｍｍ3/2 以上、かつ、６００℃の０．２％耐力が１００ｋｇｆ／ｍｍ2 以上のとき、高温強度と靱性が高いレベルで両立し、工具寿命が優れることが判っている。下記表１に示される本発明鋼は、下記表２に示すように、破壊靱性値、６００℃の０．２％耐力のすべてが高いレベルで両立し、比較鋼よりも優れている。また、本発明鋼を熱間鍛造金型として評価した例を下記表３に示すが、いずれも比較鋼よりも工具寿命が長かった。
【００２７】
【表１】
【表２】
【表３】
【発明の効果】
以上説明したように、本発明の熱間工具鋼は、高温強度と靱性を、従来技術では成し得なかった高いレベルで両立させることができ、熱間鍛造、押し出し、ダイカストに用いられる金型や、マンドレル等に使用した場合には、その工具寿命を延ばすことが可能である。
【図面の簡単な説明】
【図１】ベイナイト率を変化させた場合の、破壊靱性値と、０．２％耐力を、Ｂを添加した場合と、添加しない場合とで測定した結果を示した図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hot work tool steel excellent in high-temperature strength and toughness suitable for use in, for example, a hot forging die, an extrusion die, and a die casting die.
[0002]
[Prior art]
Tool steel used in hot forging, extrusion, die casting and other molds has sufficient high-temperature strength and toughness to withstand the occurrence of heat checks due to thermal stress and working stress during use, large cracks, and wear. Is required.
[0003]
[Problems to be solved by the invention]
As hot tool steel, JIS G 4404 defines many types of steel, among which 5Cr-Mo-V SKD61 and SKD62, 3Cr-3Mo-V SKD7, and Ni-Cr- SKT3 and SKT4, which are Mo-V based low alloy steels, are frequently used. However, these tool steels cannot satisfy both the required high-temperature strength and toughness.
[0004]
Therefore, the present applicant discloses in JP-A-8-269625 that the addition of B increases the high-temperature strength after tempering without reducing toughness. In addition, in the Japanese Patent Application No. 10-74346, the applicant of the present invention mixed a bainite structure with a martensite structure at the time of quenching, but the toughness is slightly lower than that of the martensite structure, but the high-temperature strength after tempering. Proposes something to raise. However, these are insufficient to obtain the required characteristics depending on the application.
[0005]
The present invention has been made in view of the above-described present situation, and an object of the present invention is to provide a hot tool steel excellent in both high-temperature strength and toughness.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the hot work tool steel excellent in high temperature strength and toughness according to the present invention includes B, and the structure at the time of quenching is martensite + bainite, and the bainite ratio thereof is 5 to 5. 80%. And by doing in this way, high temperature strength and toughness can be made compatible at a high level.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In order to increase the high-temperature strength, it is effective to add B or to mix a bainite structure with the martensite structure at the time of quenching, as described in JP-A-8-269625 and Japanese Patent Application No. 10-74346. However, it has been found by subsequent studies by the present inventors that, at a specific range of bainite ratio, a high-temperature strength level that cannot be achieved by each single technique can be obtained.
[0008]
That is, by increasing the mixing ratio of bainite to the quenched structure, the high temperature strength can be increased although the toughness is slightly reduced compared to the martensite structure, the form of carbide precipitated from bainite and martensite Due to That is, bainite after tempering has coarse carbides precipitated as compared with martensite, so that the toughness is reduced, but Mo 2 C is finely precipitated, so the high-temperature strength is increased. On the other hand, when B is added, there is an effect of precipitating carbides finely, and a decrease in high temperature strength is suppressed.
[0009]
However, when the bainite ratio is as low as 0 to 4%, the amount of fine carbides precipitated from bainite is small, so the effect of increasing the high temperature strength is small. On the contrary, when the mixing ratio of bainite exceeds 80%, although the amount of fine carbides increases, coarse carbides also increase, so it is considered that the toughness is greatly reduced. That is, when the mixing ratio of bainite is 5 to 80%, when B is added, the amount of coarse carbide is small and the amount of fine carbide is large, and as shown in FIG. Can be achieved at a high level.
[0010]
The hot work tool steel excellent in high temperature strength and toughness according to the present invention is based on the results of investigating the influence of other elements in addition to the above knowledge, and in weight%, C: 0.25 0.40%, Si: 0.10 to less than 1.00%, Mn: 0.30 to 1.50%, Ni: 1.07 to 2.00%, Cr: 2.70 to 5.50%, Mo: 2. 18 to 3.00%, V: more than 0.50%, 1.00% or less, B: 0.0005 to 0.0100%, Al: less than 0.005 to 0.10%, the balance is Fe and inevitable impurities, P in the impurities is 0.015% or less, S is 0.005% or less, N is 0.015% or less, and the structure at the time of quenching is martensite + bainite, Of these, the gist is that the bainite ratio is 5 to 80%.
[0011]
Below, the reason for limiting the component composition in the hot tool steel excellent in the high temperature strength and toughness of the present invention will be described.
C: C enhances the hardenability of steel, improves toughness, and has a function of improving high temperature strength by secondary precipitation as carbonitride during tempering. However, if the content is less than 0.25%, the effect of addition is poor, and if the content exceeds 0.40%, the machinability is lowered. Therefore, in the present invention, the content is 0.25 to 0. 40%.
[0012]
Si: Si has the effect of improving the machinability of steel. However, if the content is less than 0.10%, the effect of addition is poor, and if it is 1.00% or more, both the toughness and the high-temperature strength are lowered and the hot tool life is reduced. Therefore, in the present invention, the content is made 0.10 to less than 1.00%. A particularly desirable range is 0.10 to less than 0.30%.
[0013]
Mn: Mn is an element effective for improving the hardenability of steel and increasing toughness. However, if the content is less than 0.30%, the effect of addition cannot be obtained. If the content exceeds 1.50%, segregation occurs and the toughness and strength are lowered. 30 to 1.50%.
[0014]
Ni: Ni is an element effective for improving hardenability and improving toughness in the same manner as Mn. However, when its content is less than 1.07 %, its effect is poor, and when it exceeds 2.00%. Lowering the transformation point leads to a decrease in high temperature strength. Therefore, in the present invention, the content is set to 1.07 to 2.00%.
[0015]
Cr: Cr is an element effective for improving toughness and wear resistance. However, if its content is less than 2.70%, a sufficient effect cannot be obtained, and if it exceeds 5.50%, high temperature strength is reduced. Therefore, in the present invention, the content is set to 2.70 to 5.50%. A more desirable range is 3.50 to 4.50%.
[0016]
Mo: Mo improves the hardenability and temper softening resistance of steel and has the effect of increasing toughness and high-temperature strength. However, its content is 2. If it is less than 18 %, the effect of addition cannot be obtained. On the other hand, if it exceeds 3.00%, machinability and toughness are lowered. Therefore, in the present invention, the content is 2. 18 to 3.00%.
[0017]
V: V is an element necessary for increasing the high temperature strength. If the V content is less than 0.50%, the effect is poor, and if it is 1.00% or more, the machinability and toughness are deteriorated. Therefore, in the present invention, the content exceeds 0.50% and is set to 1.00% or less.
[0018]
B: B forms solid solution B in the steel, suppresses the grain growth of carbides at high temperatures, and prevents a decrease in high temperature strength. However, if it is less than 0.0005%, the effect cannot be obtained, and if it exceeds 0.0100%, the toughness decreases. Therefore, in the present invention, the content is made 0.0005 to 0.0100%.
[0019]
Al: Al is an element effective for stabilizing and homogenizing deoxidation of steel. If the content is less than 0.005%, the effect cannot be obtained. On the other hand, if the content is 0.10% or more, machinability is deteriorated and a ground defect in the steel is caused. Therefore, in the present invention, the content is made 0.005 to less than 0.10%.
[0020]
In the hot tool steel of the present invention, the contents of P, S and N as impurity elements are regulated as follows.
P: When the content of P is large, segregation increases and promotes the reduction of toughness and the occurrence of thermal cracks. Therefore, the content of P is desirably as small as possible. Therefore, in the present invention, the content is limited to 0.015% or less.
[0021]
S: S forms sulfides and improves machinability, but lowers toughness, so the content is preferably as small as possible. Therefore, in the present invention, the content is limited to 0.005% or less.
[0022]
N: N forms nitrides with V to reduce the amount of dissolved V during quenching heating. If the amount of solute V is small, the amount of V carbonitride that secondarily precipitates during tempering decreases and the high temperature strength decreases. Therefore, in the present invention, the content is limited to 0.015% or less.
[0023]
Hardened structure: The hardened structure targeted by the present invention is limited to a mixed structure of martensite and bainite. The bainite ratio indicating the mixing ratio of the bainite of the mixed structure at this time is the hardness of the material when water-cooled when quenching a material having a thickness of 10 mm to H1, the material when cooled to room temperature over 20 hours When the hardness is H2, and the hardness of the material when actually heat-treated is H, it is calculated by the following equation (1). The hardness is displayed as Vickers hardness.
Bainite ratio (%) = 100− (H−H2) / (H1−H2) × 100 (1)
[0024]
According to the experiments by the present inventors, when the bainite ratio is 0 (100% martensite) to 4%, as shown in FIG. In addition, when the bainite ratio exceeds 80%, there is no effect of suppressing the decrease in high-temperature strength due to the addition of B, and the toughness is also decreased. Therefore, in the present invention, the bainite ratio is limited to 5 to 80%.
[0025]
【Example】
The effect of the hot tool steel of the present invention will be described based on examples.
Steels of the present invention (No. 28 , No. 30 to 32, No. 35 to 37) having the composition shown in Table 1 below, and comparative steels with components marked with * deviating from the range defined in the present invention (Nanba1～nanba21 and Nanba38～nanba51, these No.16 is JIS SKD61) and the steel ingot obtained by melting in an electric furnace and blooming, forged at the forging ratio of 5 or more And then annealed at 800-850 ° C. In order to change the quenching structure, the thickness was set to 10 to 800 mm, and quenching was performed from 900 to 1050 ° C. by water cooling, oil cooling, and furnace cooling. Subsequently, tempering was performed at 550 to 640 ° C., the mold was manufactured by adjusting the hardness to HS 55 to 60, and a high temperature strength test and a fracture toughness test were performed. Among these, the high-temperature strength test was performed at a test temperature of 700 ° C. according to JIS G 0567 using a JIS 14A test piece (diameter D = 6 mm), and 0.2% proof stress was measured. The fracture toughness test was measured according to ASTM E39983.
[0026]
Empirically, when the fracture toughness value is 100 kgf / mm 3/2 or more and the 0.2% proof stress at 600 ° C. is 100 kgf / mm 2 or more, high temperature strength and toughness are compatible at a high level, and the tool life is excellent. I know that. As shown in Table 2 below, the steel of the present invention shown in Table 1 below is superior to the comparative steel in that both the fracture toughness value and the 0.2% proof stress at 600 ° C. are compatible at a high level. Moreover, although the example which evaluated this invention steel as a hot forging metal mold | die is shown in following Table 3, all had tool life longer than the comparison steel.
[0027]
[Table 1]
[Table 2]
[Table 3]
【The invention's effect】
As described above, the hot tool steel of the present invention can achieve both high-temperature strength and toughness at a high level that could not be achieved by the prior art, and is used for hot forging, extrusion, and die casting. In addition, when used for a mandrel or the like, the tool life can be extended.
[Brief description of the drawings]
FIG. 1 is a diagram showing the results of measurement of fracture toughness values and 0.2% proof stress when B is added and when B is not added.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| JP02838599A JP4123618B2 (en) | 1999-02-05 | 1999-02-05 | Hot work tool steel with excellent high temperature strength and toughness |
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| Application Number | Priority Date | Filing Date | Title |
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| JP02838599A JP4123618B2 (en) | 1999-02-05 | 1999-02-05 | Hot work tool steel with excellent high temperature strength and toughness |
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| JP2000226635A JP2000226635A (en) | 2000-08-15 |
| JP4123618B2 true JP4123618B2 (en) | 2008-07-23 |
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| JP02838599A Expired - Fee Related JP4123618B2 (en) | 1999-02-05 | 1999-02-05 | Hot work tool steel with excellent high temperature strength and toughness |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102337464A (en) * | 2011-09-02 | 2012-02-01 | 上海大学 | Steel for high-strength continuous pipe-mill core rod and preparation process thereof |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102162071B (en) * | 2010-02-23 | 2013-06-19 | 宝山钢铁股份有限公司 | Limit mandrel steel material for rolled tubes and preparation method thereof |
| JP5907415B2 (en) * | 2011-03-03 | 2016-04-26 | 日立金属株式会社 | Hot work tool steel with excellent toughness |
| JP5907416B2 (en) * | 2011-07-04 | 2016-04-26 | 日立金属株式会社 | Method for producing hot work tool steel with excellent toughness |
| EP2662462A1 (en) * | 2012-05-07 | 2013-11-13 | Valls Besitz GmbH | Low temperature hardenable steels with excellent machinability |
| EP2662460A1 (en) * | 2012-05-07 | 2013-11-13 | Valls Besitz GmbH | Tough bainitic heat treatments on steels for tooling |
| CN103103459B (en) * | 2013-02-18 | 2014-12-10 | 无锡市派克重型铸锻有限公司 | Large-scale forging and manufacture process wind electricity slewing bearing forging and manufacturing process |
| US20160010168A1 (en) * | 2013-03-01 | 2016-01-14 | Rovalma, S.A. | High thermal diffusivity, high toughness and low crack risk during heat treatment tool steel |
| US20170096719A1 (en) * | 2014-03-18 | 2017-04-06 | Innomaq 21, Sociedad Limitada | Extremely high conductivity low cost steel |
| CN115181901B (en) * | 2022-04-07 | 2023-09-26 | 燕山大学 | High-strength and high-toughness hard low-temperature bainite hot work die steel and preparation method thereof |
| CN114737035A (en) * | 2022-04-25 | 2022-07-12 | 武钢集团襄阳重型装备材料有限公司 | Method for improving hardness uniformity of hot work die steel 56NiCrMoV7 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102337464A (en) * | 2011-09-02 | 2012-02-01 | 上海大学 | Steel for high-strength continuous pipe-mill core rod and preparation process thereof |
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