JP2012201909A - Hot tool steel - Google Patents
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- JP2012201909A JP2012201909A JP2011065369A JP2011065369A JP2012201909A JP 2012201909 A JP2012201909 A JP 2012201909A JP 2011065369 A JP2011065369 A JP 2011065369A JP 2011065369 A JP2011065369 A JP 2011065369A JP 2012201909 A JP2012201909 A JP 2012201909A
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- 229910001315 Tool steel Inorganic materials 0.000 title claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 6
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 5
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 4
- -1 N: 0.015% or less Substances 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims 1
- 238000005242 forging Methods 0.000 abstract description 6
- 238000004512 die casting Methods 0.000 abstract description 5
- 238000005266 casting Methods 0.000 abstract description 4
- 229910052804 chromium Inorganic materials 0.000 abstract description 4
- 238000001192 hot extrusion Methods 0.000 abstract description 4
- 229910052748 manganese Inorganic materials 0.000 abstract description 4
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 229910000831 Steel Inorganic materials 0.000 description 19
- 230000000052 comparative effect Effects 0.000 description 19
- 239000010959 steel Substances 0.000 description 18
- 230000000694 effects Effects 0.000 description 14
- 239000000047 product Substances 0.000 description 13
- 239000000126 substance Substances 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 10
- 238000007711 solidification Methods 0.000 description 10
- 230000008023 solidification Effects 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 150000001247 metal acetylides Chemical class 0.000 description 9
- 238000010791 quenching Methods 0.000 description 7
- 230000000171 quenching effect Effects 0.000 description 7
- 238000005496 tempering Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 238000005204 segregation Methods 0.000 description 2
- 229910000717 Hot-working tool steel Inorganic materials 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
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Abstract
Description
本発明は、熱間鍛造、熱間押出、鋳造、ダイカストなどの金型用の熱間工具鋼に関するものである。 The present invention relates to hot tool steel for dies such as hot forging, hot extrusion, casting, and die casting.
従来、プレス型、鍛造型、ダイカスト型などの素材として用いられる工具鋼としては、ＪＩＳに制定されているＳＫＤ６１、ＳＫＤ６、ＳＫＴなどのほか、３Ｃｒ−３Ｍｏ系鋼、セミハイス系鋼などが使用されている。近年、数値制御による切削加工のさらなる進歩により、金型加工等の自動化、高速化が進み、工具鋼におけるより優れた靱性が求められている。 Conventionally, as tool steels used as raw materials for press dies, forging dies, die casting dies, 3Cr-3Mo steels, semi-high steels, etc. are used in addition to SKD61, SKD6, and SKT established by JIS. Yes. In recent years, further progress in cutting by numerical control has led to the automation and speeding up of die processing and the like, and higher toughness in tool steel has been demanded.
例えば、特許第４５１６２１１号公報（特許文献１）に開示されているように、Ｃ：０．３〜０．４％、Ｍｎ：０．２〜０．８％、Ｃｒ：４〜６％、Ｍｏ：１．８〜３％、Ｖ：０．４〜０．６％、Ｓｉ：≦０．２５％、Ｎ：≦０．０１０％、Ｏ：≦１０ｐｐｍ、Ｐ：≦０．０１０％、Ｓ：≦０．０００８％で焼入焼戻しにて４５ＨＲＣを超える硬度が得られる熱間加工工具鋼が提案されている。
上述した特許文献１には、ＮとＴｉの低減が凝固時に生成するＭＸ系晶出物（Ｍ：Ｖ，Ｔｉ、Ｘ：Ｃおよび／またはＮ）を軽減することが述べられている。しかしながら、Ｔｉを含むＶ炭化物は鋼材基地組織中に固溶しにくく、鋼材製品の靱性の低下を招き、凝固時のＴｉ含有Ｖ炭化物の晶出を完全には低減することができない。 Patent Document 1 described above describes that the reduction of N and Ti reduces the MX crystallized product (M: V, Ti, X: C and / or N) generated during solidification. However, the V carbide containing Ti is hardly dissolved in the steel base structure, leading to a decrease in the toughness of the steel product, and the crystallization of the Ti-containing V carbide during solidification cannot be reduced completely.
上述したような問題を解消するために発明者らは鋭意開発した結果、不純物としてのＴｉとＮの含有量を制御することで、靱性に有害な凝固時の晶出物形成量を低減する。また、適正な固溶化熱処理を加えて鋼材製品に残存する晶出物をさらに減少させることで、優れた靱性を得ることを見出し発明に至った。 As a result of diligent development by the inventors in order to solve the above-described problems, the amount of crystals formed during solidification harmful to toughness is reduced by controlling the contents of Ti and N as impurities. Further, the inventors have found that excellent toughness can be obtained by further reducing the crystallized matter remaining in the steel product by applying an appropriate solution heat treatment.
その発明の要旨とするところは、
質量％で、Ｃ：０．３〜０．４５％、Ｓｉ：０．２５％超〜１．２％、Ｍｎ：０．２〜１．０％、Ｃｒ：３〜６％、ＭｏまたはＷのいずれか１種または２種をＭｏ当量（Ｍｏ＋１／２Ｗ）：１．０〜３．５％、ＶまたはＮｂのいずれか１種または２種をＶ当量（Ｖ＋１／２Ｎｂ）：０．３〜１．０％、残部がＦｅおよび不可避的不純物よりなり、該不純物としては、Ｎ：０．０１５％以下、Ｔｉ：０．００５％以下、かつ、ＮとＴｉのバランスが、Ｎ≦Ｒ≡１．４６×１０-4×Ｔｉ-0.736からなることを特徴とする熱間工具鋼にある。
The gist of the invention is that
In mass%, C: 0.3 to 0.45%, Si: more than 0.25% to 1.2%, Mn: 0.2 to 1.0%, Cr: 3 to 6%, Mo or W Either one or two of them is equivalent to Mo (Mo + 1 / 2W): 1.0 to 3.5%, and one or two of V or Nb is equivalent to V (V + 1 / 2Nb): 0.3 to 1 0.0%, the balance being Fe and inevitable impurities, including N: 0.015% or less, Ti: 0.005% or less, and the balance of N and Ti is N ≦ R≡1. It is a hot tool steel characterized by comprising 46 × 10 −4 × Ti −0.736 .
以上述べたように、本発明鋼は、高強度材における問題であった、靱性が大きく改善されたことで、熱間鍛造、熱間押出、鋳造、ダイカストなどの金型用の熱間工具鋼として優れた工具寿命をもたらすものであり、その効果は非常に大きい。 As described above, the steel of the present invention is a problem in high-strength materials, and the toughness is greatly improved, so that hot tool steel for dies such as hot forging, hot extrusion, casting, die casting, etc. As a result, the tool life is excellent, and the effect is very large.
以下、本発明鋼の成分範囲の限定理由について述べる。
Ｃ：０．３〜０．４５％
Ｃは、十分な焼入性を確保し、炭化物を形成させることで硬度、耐摩耗性や強度を得るための元素である。しかし、０．３％未満では十分な強度、耐摩耗性が得られない。また、０．４５％を超えると、凝固偏析を助長し、炭窒化物の晶出が生じ易くなり、靱性を阻害する。したがって、その範囲を０．３〜０．４５％とした。
Hereinafter, the reason for limiting the component range of the steel of the present invention will be described.
C: 0.3 to 0.45%
C is an element for securing sufficient hardenability and obtaining hardness, wear resistance and strength by forming carbides. However, if it is less than 0.3%, sufficient strength and wear resistance cannot be obtained. On the other hand, if it exceeds 0.45%, solidification segregation is promoted, carbonitride crystallization is likely to occur, and toughness is impaired. Therefore, the range was made 0.3 to 0.45%.
Ｓｉ：０．２５％超〜１．２％
Ｓｉは、製鋼での脱酸効果、焼入性確保として必要な元素である。しかし、０．２５％以下であると、その効果が十分でなく、また、１．２％を超えると靱性を低下させ、また、熱間工具鋼として重要な物性値である熱伝導率を低下させることから、その範囲を０．２５％超〜１．２％とした。
Si: more than 0.25% to 1.2%
Si is an element necessary for ensuring the deoxidation effect and hardenability in steelmaking. However, if it is 0.25% or less, the effect is not sufficient, and if it exceeds 1.2%, the toughness is reduced, and the thermal conductivity, which is an important physical property value for hot tool steel, is reduced. Therefore, the range is made more than 0.25% to 1.2%.
Ｍｎ：０．２〜１．０％
Ｍｎは、焼入性を確保するための元素である。しかし、０．２％未満ではその効果が十分でなく、また、１．０％を超えると加工性を低下させることから、その範囲を０．２〜１．０％とした。
Mn: 0.2 to 1.0%
Mn is an element for ensuring hardenability. However, if it is less than 0.2%, the effect is not sufficient, and if it exceeds 1.0%, the workability deteriorates, so the range was made 0.2 to 1.0%.
Ｃｒ：３〜６％
Ｃｒは、焼入性を改善するための元素である。しかし、３％未満ではその効果が十分でなく、また、６％を超えると焼入焼戻し時にＣｒ系の炭化物が過多に形成され、高温強度および軟化抵抗性を低下させることから、その範囲を３〜６％とした。
Cr: 3-6%
Cr is an element for improving hardenability. However, if it is less than 3%, the effect is not sufficient, and if it exceeds 6%, excessive amounts of Cr-based carbides are formed during quenching and tempering, and the high temperature strength and softening resistance are lowered. -6%.
Ｍｏ＋１／２Ｗ：１．０〜３．５％
Ｍｏ、Ｗは、共に焼入性と二次硬化、耐摩耗性に寄与する析出炭化物を得るためと、焼入れ時に未固溶となった微細な炭化物が結晶粒の粗大化を抑制するための元素である。ただし、その効果はＭｏの方がＷよりも２倍強く、同じ効果を得るのに、ＷはＭｏの２倍必要である。この両元素の効果は、Ｍｏ当量（Ｍｏ＋１／２Ｗ）で表すことができる。しかし、Ｍｏ＋１／２Ｗが１．０％未満ではその効果が十分でない。また、過剰に添加しても効果が飽和するばかりか、炭化物が粗大凝集することにより靱性を低下させることから、その範囲を１．０〜３．５％とした。
Mo + 1 / 2W: 1.0-3.5%
Both Mo and W are elements for obtaining precipitated carbides that contribute to hardenability, secondary hardening, and wear resistance, and for suppressing the coarsening of crystal grains by fine carbides that have become insoluble during quenching. It is. However, the effect of Mo is twice as strong as that of W. To obtain the same effect, W needs to be twice that of Mo. The effect of both elements can be expressed by Mo equivalent (Mo + 1 / 2W). However, when Mo + 1 / 2W is less than 1.0%, the effect is not sufficient. Moreover, even if it adds excessively, not only will the effect be saturated, but the toughness is reduced by coarse aggregation of carbides, so the range was made 1.0 to 3.5%.
Ｖ＋１／２Ｎｂ：０．３〜１．０％
Ｖ、Ｎｂは、焼戻し時に微細で硬質な炭化物、炭窒化物を析出し、強度や耐摩耗性に寄与する。また、焼入れ時には微細な炭化物、炭窒化物が結晶粒の粗大化を抑制し、靱性の低下を抑制する。ただし、その効果はＶの方がＮｂよりも２倍強く、同じ効果を得るのに、ＮｂはＶの２倍必要である。この両元素の効果は、Ｖ当量（Ｖ＋１／２Ｎｂ）で表すことができる。しかし、０．３％未満ではその効果が十分でない。また、多過ぎると、凝固時に粗大な晶出物を生成し、靱性を低下させることから、その範囲を０．３〜１．０％とした。
V + 1 / 2Nb: 0.3-1.0%
V and Nb precipitate fine and hard carbides and carbonitrides during tempering, and contribute to strength and wear resistance. Further, during the quenching, fine carbides and carbonitrides suppress the coarsening of the crystal grains and suppress the decrease in toughness. However, the effect of V is twice as strong as that of Nb, and Nb needs to be twice that of V to obtain the same effect. The effect of both elements can be expressed in terms of V equivalent (V + 1 / 2Nb). However, if it is less than 0.3%, the effect is not sufficient. Moreover, when too much, a coarse crystallized substance will be produced | generated at the time of solidification and toughness will be reduced, Therefore The range was made into 0.3 to 1.0%.
Ｎ：０．０１５％以下、Ｔｉ：０．００５％以下、かつ、ＮとＴｉのバランスが、Ｎ≦Ｒ≡１．４６×１０-4×Ｔｉ-0.736
Ｎ、Ｔｉは、不純物としてのＮとＴｉの含有量を制御することで、靱性に有害な凝固時の晶出物形成量を低減するもので、Ｎは０．０１５％を超え、また、Ｔｉは０．００５％を超える場合は、晶出物が固溶しにくく、十分な靱性を得ることができないことから、それぞれの上限を０．０１５％、０．００５％とした。ただし、Ｎ≦Ｒ≡１．４６×１０-4×Ｔｉ-0.736とした理由は、上記式を満たさない条件でＮおよびＴｉを制御した場合、凝固時に形成される晶出物は固溶され難い組成になり、固溶化熱処理後の残存量が多くなり、十分な靱性を得ることが出来ないからである。
N: 0.015% or less, Ti: 0.005% or less, and the balance between N and Ti is N ≦ R≡1.46 × 10 −4 × Ti −0.736
N and Ti reduce the amount of crystallized matter formed during solidification, which is harmful to toughness, by controlling the contents of N and Ti as impurities. N exceeds 0.015%, and Ti When the content exceeds 0.005%, the crystallized product is hardly dissolved, and sufficient toughness cannot be obtained. Therefore, the upper limits were set to 0.015% and 0.005%, respectively. However, the reason why N ≦ R≡1.46 × 10 −4 × Ti −0.736 is that when N and Ti are controlled under the conditions not satisfying the above formula, the crystallized product formed during solidification is not easily dissolved. This is because the remaining amount after the solution heat treatment is increased and sufficient toughness cannot be obtained.
以下、本発明について実施例によって具体的に説明する。
表１に示す化学成分の鋼を真空溶解炉にて、Ｎｏ．１〜１４は１００ｋｇ、Ｎｏ．１５〜２０は５０ｋｇの溶解を行い、５０ｋｇずつの小鋼塊を製造した。Ｎｏ．１〜１４は小鋼塊の片方は固溶化熱処理を実施し、もう一方は固溶化熱処理を行わず、Ｎｏ．１５〜２０は固溶化熱処理を実施した。いずれの小鋼塊も圧鍛を加えて、比較試験に供した。その結果を表２に示す。
Hereinafter, the present invention will be specifically described with reference to examples.
In the vacuum melting furnace, the steels having the chemical components shown in Table 1 were No. 1-14 are 100 kg, No.1. 15-20 melt | dissolved 50 kg and manufactured the small steel ingot of 50 kg each. No. In Nos. 1 to 14, one of the small steel ingots was subjected to solution heat treatment, and the other was not subjected to solution heat treatment. 15-20 performed the solution heat treatment. All of the small steel ingots were subjected to forging and subjected to a comparative test. The results are shown in Table 2.
表２の内、Ｎｏ．１〜１４は、固溶化熱処理を実施していない。一方、Ｎｏ．１５〜３４は、１２５０℃での固溶化熱処理を実施した鋼材であり、固溶化熱処理の時間は、工業的に日常連続操業が可能な２０時間とした。また、晶出物量は、１００ｍｍ径の圧鍛材の中心部より、圧延方向に平行な面にて幅１０ｍｍで長さ１６ｍｍの試験片を採取し、観察を実施した。最終バフ研磨にて鏡面研磨仕上げをした後、光学顕微鏡にて４００倍で観察を行い、晶出物が多い箇所を３０視野選択し、晶出物の面積率を算出して晶出物量とした。 In Table 2, no. 1-14 does not implement the solution heat treatment. On the other hand, no. 15 to 34 are steel materials subjected to a solution heat treatment at 1250 ° C., and the time for the solution heat treatment was set to 20 hours capable of industrial daily continuous operation. Further, the amount of crystallized substance was observed by collecting a test piece having a width of 10 mm and a length of 16 mm on a surface parallel to the rolling direction from the center of a 100 mm diameter forged material. After finishing mirror polishing by final buffing, observation was performed at 400 times with an optical microscope, 30 visual fields were selected at a location where there were many crystallized substances, and the area ratio of the crystallized substances was calculated to obtain the amount of crystallized substances. .
また、靱性は、シャルピー衝撃試験により評価した。試験片は、１００ｍｍ径の圧鍛材の中心部より圧延方向と垂直方向より採取した。試験片は、焼入焼戻しにより４４〜４６ＨＲＣの範囲内の硬さに収まるように調質し、ＪＩＳ Ｚ ２２４２に従い、深さ２ｍｍのＵノッチを圧延方向に垂直となる面に加工した。さらに、高温特性は、焼入焼戻しにより４４〜４６ＨＲＣに調質した各鋼材を６５０℃にて５０時間保持し、この鋼材を空冷した後に硬度を測定し、初期の調質硬さとの差（硬度低下度）にて評価した。 The toughness was evaluated by a Charpy impact test. Test specimens were collected from the center of a 100 mm diameter forged material from the rolling direction and the vertical direction. The test piece was tempered by quenching and tempering so that it had a hardness within the range of 44 to 46 HRC, and a U-notch having a depth of 2 mm was processed into a surface perpendicular to the rolling direction in accordance with JIS Z 2242. Furthermore, the high temperature characteristics are as follows. Each steel material tempered to 44 to 46 HRC by quenching and tempering is held at 650 ° C. for 50 hours, and after the steel material is air-cooled, the hardness is measured and the difference from the initial tempered hardness (hardness) (Degree of decrease).
表２に示すように、比較例Ｎｏ．８は、Ｔｉ含有量が高く、かつ、Ｎは本発明の範囲内であるが、Ｎ≦Ｒを満たしていないことから、晶出物量を低減することができず、残存する晶出物量が多くなってしまい、靱性が劣る。比較例Ｎｏ．９は、Ｔｉ含有量が高いために、晶出物量を低減することができず、靱性が劣る。比較例Ｎｏ．１０は、ＴｉとＮの含有量が共に高いために、比較例Ｎｏ．９と同様に、晶出物量を低減することができず、靱性が劣る。 As shown in Table 2, Comparative Example No. No. 8 has a high Ti content and N is within the scope of the present invention, but N ≦ R is not satisfied, so the amount of crystallized matter cannot be reduced, and the amount of residual crystallized product is large. And toughness is inferior. Comparative Example No. In No. 9, since the Ti content is high, the amount of crystallized product cannot be reduced, and the toughness is inferior. Comparative Example No. No. 10 is comparative example No. 10 because the contents of Ti and N are both high. Similar to 9, the amount of crystallized material cannot be reduced, and the toughness is inferior.
比較例Ｎｏ．１１は、ＴｉとＮの含有量は共に本発明の範囲内であるが、Ｎ≦Ｒを満たしていないことから、残存する晶出物量が多くなってしまい、靱性が悪い。比較例Ｎｏ．１２は、Ｎ含有量が高いために、晶出物量を低減することができず、晶出物量が非常に多くなってしまい、靱性が悪い。比較例Ｎｏ．１３は、Ｔｉ含有量が高く、Ｎは本発明の範囲内であるが、Ｎ≦Ｒを満たしていないことから、晶出物量を低減することができず、晶出物量が非常に多くなってしまい、靱性が悪い。 Comparative Example No. In No. 11, the contents of Ti and N are both within the scope of the present invention, but N ≦ R is not satisfied, so that the amount of the remaining crystallized product increases and the toughness is poor. Comparative Example No. In No. 12, since the N content is high, the amount of crystallized substances cannot be reduced, the amount of crystallized substances becomes very large, and the toughness is poor. Comparative Example No. No. 13 has a high Ti content and N is within the scope of the present invention. However, since N ≦ R is not satisfied, the amount of crystallized product cannot be reduced, and the amount of crystallized product becomes very large. The toughness is poor.
比較例Ｎｏ．１４は、ＴｉとＮの含有量は共に本発明の範囲内であるが、Ｎ≦Ｒを満たしていないことから、残存する晶出物量が多くなってしまい、靱性が劣る。なお、比較例Ｎｏ．２２〜２８は、比較例Ｎｏ．８〜１４に係る化学成分が本発明の成分含有量の範囲外である条件での、１２５０℃での固溶化熱処理を実施した鋼材であるが、いずれも晶出物量の面積％が大きい。すなわち、晶出物量が多くなってしまい、靱性が十分でない。また、Ｎｏ．２２〜２８の合金元素含有量は、Ｎｏ．８〜１４と同等であることから、高温特性は評価しない。 Comparative Example No. No. 14, the contents of Ti and N are both within the scope of the present invention. However, since N ≦ R is not satisfied, the amount of the remaining crystallized product increases and the toughness is inferior. Comparative Example No. 22-28 are comparative example No.2. Although it is the steel material which implemented the solution heat treatment at 1250 degreeC on the conditions which the chemical component which concerns on 8-14 is outside the range of the component content of this invention, all are area% of the amount of crystallized substances. That is, the amount of crystallized substances increases and the toughness is not sufficient. No. The alloy element contents of 22 to 28 are No. Since it is equivalent to 8-14, a high temperature characteristic is not evaluated.
比較例Ｎｏ．２９は、靱性は良いがＣ含有量が低いために、高温特性が劣り、十分な耐摩耗性が得られない。比較例Ｎｏ．３０は、Ｓｉ含有量が低く、かつ、ＶおよびＶｅｑが多過ぎるために、焼入性を十分確保できず、また、凝固時に粗大な晶出物生成し、十分な靱性が得られない。比較例Ｎｏ．３１は、Ｍｎ、Ｃｒの含有量が高いために、加工性および焼入焼戻し時にＣｒ系の炭化物が過多に形成され、高温強度および軟化抵抗性が得られない。 Comparative Example No. No. 29 has good toughness, but has a low C content, so the high temperature characteristics are inferior and sufficient wear resistance cannot be obtained. Comparative Example No. In No. 30, since the Si content is low and V and Veq are too much, sufficient hardenability cannot be secured, and coarse crystallized products are generated during solidification, and sufficient toughness cannot be obtained. Comparative Example No. Since No. 31 has a high content of Mn and Cr, excessive amounts of Cr-based carbides are formed during workability and quenching and tempering, and high temperature strength and softening resistance cannot be obtained.
比較例Ｎｏ．３２は、Ｓｉ含有量が多過ぎ、かつＣｒ含有量が少なく、Ｖｅｑは低いために、晶出物量は少ないが、靱性が悪く、熱間工具鋼としての熱伝導性が悪い。比較例Ｎｏ．３３は、Ｃ含有量が高く、Ｍｎ含有量が低く、Ｍｏｅｑが高いため、特にＣ含有量が過多のため、凝固偏析を助長し、炭窒化物の晶出が生じ易くなり、靱性を阻害し、また、Ｍｎが低いために、焼入性を確保することができず、高温特性が得られず、さらに、Ｍｏｅｑが多過ぎるため、炭化物が粗大凝集し、靱性をさらに悪くする。 Comparative Example No. No. 32 has too much Si content, low Cr content, and low Veq, so the amount of crystallized matter is small, but the toughness is poor and the thermal conductivity as hot tool steel is poor. Comparative Example No. No. 33 has a high C content, a low Mn content, and a high Moeq. In particular, since the C content is excessive, solidification segregation is promoted, and crystallization of carbonitrides is likely to occur, thereby inhibiting toughness. Moreover, since Mn is low, hardenability cannot be ensured, high temperature characteristics cannot be obtained, and, since Moeq is too much, carbides are coarsely aggregated and toughness is further deteriorated.
比較例Ｎｏ．３４は、Ｍｏｅｑが低いために、高温特性が得られない。これに対し、本発明例Ｎｏ．１〜７は、いずれも本発明の条件を満足していることから、その特性とする靱性および高温特性の優れた金型用の熱間工具鋼を得ることを可能とした。 Comparative Example No. Since No. 34 has low Moeq, high temperature characteristics cannot be obtained. On the other hand, the present invention example No. Since Nos. 1 to 7 all satisfied the conditions of the present invention, it was possible to obtain hot tool steel for molds having excellent toughness and high temperature characteristics.
以上のように、本発明により不純物としてのＴｉとＮの含有量を制御することで、靱性に有害な凝固時の晶出物形成量を低減し、適正な固溶化熱処理を加えて鋼材製品に残存する晶出物をさらに減少させることで、優れた靱性と優れた高温強度とを兼ね備え熱間鍛造、熱間押出、鋳造、ダイカストなどの金型用の熱間工具鋼として優れた工具寿命をもたらす熱間工具鋼を提供することを可能とした。
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 controlling the contents of Ti and N as impurities according to the present invention, the amount of crystallized matter formed at the time of solidification harmful to toughness is reduced, and an appropriate solution heat treatment is added to the steel product. By further reducing the remaining crystallized material, it has excellent tool life as hot tool steel for dies such as hot forging, hot extrusion, casting, die casting, etc. with excellent toughness and excellent high-temperature strength. It has become possible to provide hot working tool steel.
Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina
Claims (1)
Ｃ：０．３〜０．４５％、
Ｓｉ：０．２５％超〜１．２％、
Ｍｎ：０．２〜１．０％、
Ｃｒ：３〜６％、
ＭｏまたはＷのいずれか１種または２種をＭｏ当量（Ｍｏ＋１／２Ｗ）：１．０〜３．５％、ＶまたはＮｂのいずれか１種または２種をＶ当量（Ｖ＋１／２Ｎｂ）：０．３〜１．０％、残部がＦｅおよび不可避的不純物よりなり、該不純物としては、
Ｎ：０．０１５％以下、
Ｔｉ：０．００５％以下、
かつ、ＮとＴｉのバランスが、Ｎ≦Ｒ≡１．４６×１０-4×Ｔｉ-0.736からなることを特徴とする熱間工具鋼。 % By mass
C: 0.3 to 0.45%,
Si: more than 0.25% to 1.2%,
Mn: 0.2 to 1.0%,
Cr: 3 to 6%,
One or two of Mo or W is Mo equivalent (Mo + 1 / 2W): 1.0 to 3.5%, and one or two of V or Nb is V equivalent (V + 1 / 2Nb): 0 .3-1.0%, the balance consisting of Fe and inevitable impurities,
N: 0.015% or less,
Ti: 0.005% or less,
A hot work tool steel characterized in that the balance of N and Ti is N ≦ R≡1.46 × 10 −4 × Ti −0.736 .
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| CN104278200A (en) * | 2014-09-17 | 2015-01-14 | 北京科技大学 | High-hot-strength spray-formed hot work die steel and preparation method thereof |
| WO2017111680A1 (en) * | 2015-12-22 | 2017-06-29 | Uddeholms Ab | Hot work tool steel |
| CN109487166A (en) * | 2018-12-21 | 2019-03-19 | 北京科技大学 | A kind of high strength at high temperature low-carbon heated die steel and preparation method thereof |
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| KR101751530B1 (en) | 2015-12-28 | 2017-06-27 | 주식회사 포스코 | Steel sheet for tool and method of manufacturing for the same |
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| JP2002509986A (en) * | 1998-03-27 | 2002-04-02 | ウッデホルム トウリング アクテイエボラーグ | Steel materials for hot working tools |
| JP2003268486A (en) * | 2002-03-11 | 2003-09-25 | Nippon Koshuha Steel Co Ltd | Tool steel for hot working |
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| JP2002509986A (en) * | 1998-03-27 | 2002-04-02 | ウッデホルム トウリング アクテイエボラーグ | Steel materials for hot working tools |
| JP2003268486A (en) * | 2002-03-11 | 2003-09-25 | Nippon Koshuha Steel Co Ltd | Tool steel for hot working |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104278200A (en) * | 2014-09-17 | 2015-01-14 | 北京科技大学 | High-hot-strength spray-formed hot work die steel and preparation method thereof |
| WO2017111680A1 (en) * | 2015-12-22 | 2017-06-29 | Uddeholms Ab | Hot work tool steel |
| JP2019504197A (en) * | 2015-12-22 | 2019-02-14 | ウッデホルムズ アーベー | Hot work tool steel |
| US11131012B2 (en) | 2015-12-22 | 2021-09-28 | Uddeholms Ab | Hot work tool steel |
| JP7045315B2 (en) | 2015-12-22 | 2022-03-31 | ウッデホルムズ アーベー | Hot tool steel |
| CN109487166A (en) * | 2018-12-21 | 2019-03-19 | 北京科技大学 | A kind of high strength at high temperature low-carbon heated die steel and preparation method thereof |
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