JP3499425B2 - Manufacturing method of cold tool steel - Google Patents
Manufacturing method of cold tool steelInfo
- Publication number
- JP3499425B2 JP3499425B2 JP02130298A JP2130298A JP3499425B2 JP 3499425 B2 JP3499425 B2 JP 3499425B2 JP 02130298 A JP02130298 A JP 02130298A JP 2130298 A JP2130298 A JP 2130298A JP 3499425 B2 JP3499425 B2 JP 3499425B2
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- Prior art keywords
- carbide
- tempering
- steel
- less
- life
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Description
【0001】[0001]
【発明の属する技術分野】本発明は、耐疲労強度の優れ
た高寿命型用冷間工具鋼の製造方法に関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a long-life cold work tool steel having excellent fatigue strength.
【0002】[0002]
【従来の技術】従来、冷間加工用工具には、JIS−S
KD11が広く使用されている。しかし、塑性加工技術
の進歩や被加工材の高強度化に伴い、使用される工具へ
の応力負荷が大きくなり、500℃焼き戻しで60HR
Cの硬さが得られるSKD11でさえ、粗大なM7 C3
型炭化物により耐摩耗性は確保しているが、一方で、M
7 C3 型炭化物は型寿命の低下をもたらす一因となって
いる。このような問題に対して、例えば特開平1−20
1442号公報、特開平2−247357号公報、特開
平2−277745号公報、特開平3−134136号
公報、および特開平5−156407号公報の発明が提
案されている。2. Description of the Related Art Conventionally, JIS-S has been used for cold working tools.
KD11 is widely used. However, plastic processing technology
To the tools used with the progress of
Stress load increases and 60HR can be obtained by tempering at 500 ℃
Even SKD11, which can obtain the hardness of C, has a coarse M7C3
Wear resistance is secured by the type carbide, but on the other hand, M
7C3Mold carbide is one of the causes of shortening mold life
There is. For such a problem, for example, Japanese Patent Laid-Open No. 1-20
1442, JP-A-2-247357, JP-A
JP-A-2-277745, JP-A-3-134136
The inventions disclosed in JP-A-5-156407 and JP-A-5-156407 are proposed.
Is being proposed.
【0003】この特開平1−201442号公報は、重
量%で、C:0.90〜1.35%、Si:0.70〜
1.40%、Mn:1.0%以下、S:0.004%以
下、Cr:8.0〜10.0、MoとWの1種または2
種をMo+W/2で1.5〜2.5%、VとNbの1種
または2種をV+Nb/2で0.15〜2.5%を含
み、残部Feおよび不可避的不純物からなり、さらに焼
入れ焼もどし組織において、M7 C3 型炭化物の面積率
を2%以上9%以下、MC炭化物の面積率を2.5%以
下とした転造ダイス用鋼がある。確かに、この発明に
は、炭化物についての面積率、および粒径を規制してい
るが、しかし、主に靱性の向上、炭化物の連鎖状分布を
経路とした亀裂伝播の抑制を目的としたものである。こ
れに対し、本発明は金型寿命のばらつき、極度な低寿命
をもたらす因子がM7 C3 型炭化物の割れによる亀裂発
生、および亀裂伝播が大きな要因であることを見出し、
そのためにはM7 C3 型炭化物を15μm以下とするこ
とにより、金型寿命のばらつき、および極度な低寿命金
型を低減し、金型の平均寿命の向上をはかると言うもの
である。In Japanese Patent Laid-Open No. 1-204442, C: 0.90 to 1.35%, Si: 0.70 to 70% by weight.
1.40%, Mn: 1.0% or less, S: 0.004% or less, Cr: 8.0 to 10.0, one or two of Mo and W or 2
1.5 to 2.5% of Mo + W / 2 as a seed, 0.15 to 2.5% of one or two of V and Nb as V + Nb / 2, and the balance Fe and inevitable impurities. There is a steel for rolling dies in which the area ratio of M 7 C 3 type carbides is 2% or more and 9% or less and the area ratio of MC carbides is 2.5% or less in the quenched and tempered structure. Certainly, in the present invention, the area ratio and the grain size of the carbide are regulated, but the purpose is mainly to improve the toughness and to suppress the crack propagation through the chain distribution of the carbide. Is. On the other hand, in the present invention, it is found that the factors that cause the variation of die life, the extremely short life, are crack generation due to cracking of M 7 C 3 type carbide and crack propagation,
For that purpose, it is said that by making the M 7 C 3 type carbide to be 15 μm or less, it is possible to improve the average life of the die by reducing the variation of die life and the die of extremely short life.
【0004】また、特開平2−247357号公報は、
上述の特開平1−201442号公報に、さらに、不純
物であるAs,Sn,Sb,Cu,B,Pb,Biの合
計量が0.13%以下からなる転造ダイス用鋼にある。
さらに、特開平2−277745号公報は、焼入焼もど
し組織において、粒径2μm以上のMC型残留炭化物と
M6 C型残留炭化物の1種または2種の合計の面積率が
3%以下、粒径2μm以上のM7 C3 型残留炭化物の面
積率が1%以下と規制したものである。いずれも、特開
平1−201442号公報と同様に、主に靱性の向上、
炭化物の連鎖状分布を経路とした亀裂伝播の抑制を目的
としたものである。これに対し、本発明は、前述のよう
に、M7 C3 型炭化物の割れによる亀裂発生、および亀
裂伝播が大きな要因であることを見出し、しかも、その
M7 C3 型炭化物の破壊起点が粒径15μm以下である
ことを見出したものである。Further, Japanese Patent Laid-Open No. 2-247357 discloses that
The above-mentioned JP-A-1-201442 further discloses a steel for a rolling die, in which the total amount of impurities As, Sn, Sb, Cu, B, Pb and Bi is 0.13% or less.
Further, JP-A-2-277745, in quenching and tempering tissue, one or two of a total area ratio of the particle size 2μm or more MC type residual carbides and M 6 C type residual carbides 3% or less, The area ratio of the M 7 C 3 type residual carbide having a particle size of 2 μm or more was regulated to 1% or less. In both cases, the toughness is mainly improved, as in JP-A-1-201442.
The purpose is to suppress crack propagation along the chain distribution of carbides. On the other hand, as described above, the present invention has found that the crack generation and crack propagation due to the cracking of the M 7 C 3 type carbide are major factors, and that the fracture starting point of the M 7 C 3 type carbide is It was found that the particle size is 15 μm or less.
【0005】特開平3−134136号公報も、上述の
特開平1−201442号公報に、さらに、不可避的不
純物のうち、Pは0.02%以下、Sは0.005%以
下、Oは30ppm以下、Nは300ppm以下であ
り、さらに焼入焼もどし組織において、粒径2μm以上
のM7 C3 型残留炭化物の面積率が8%以下、粒径2μ
m以上のMC型残留炭化物およびM6 C型残留炭化物の
1種または2種の合計の面積率が3%以下である高硬
度、高靱性冷間工具であり、また、特開平5−1564
07号公報は、焼入焼もどし後において、M7 C3 型一
次炭化物が面積率で4.0%以下、MC型一次炭化物が
面積率で0.5%以下、一次炭化物の最大粒径が実質的
に20μm以下で基地中に均一に分散したミクロ組織と
なり、さらに1050℃〜1100℃の焼入温度から、
500℃までの焼入冷却速度を25℃/minとして焼
入れし、これを高温焼もどしした場合の硬さがHRC6
4以上を得ることのできる高性能転造ダイス用鋼にあ
る。Japanese Unexamined Patent Publication (Kokai) No. 3-134136 also discloses the above-mentioned Japanese Unexamined Patent Publication (Kokai) No. 1-104442 in which P is 0.02% or less, S is 0.005% or less, and O is 30 ppm. Hereinafter, N is 300 ppm or less, and in the quenching and tempering structure, the area ratio of M 7 C 3 type residual carbide having a particle size of 2 μm or more is 8% or less, and the particle size is 2 μm.
high hardness one or of the total area ratio of the above MC type residual carbides and M 6 C type residual carbides m is 3% or less, a high toughness cold work tool, also, JP-A 5-1564
No. 07 gazette discloses that after quenching and tempering, the M 7 C 3 type primary carbides have an area ratio of 4.0% or less, the MC type primary carbides have an area ratio of 0.5% or less, and the maximum grain size of the primary carbides is Substantially 20 μm or less to form a microstructure uniformly dispersed in the matrix, and from the quenching temperature of 1050 ° C. to 1100 ° C.,
Hardening at a quenching cooling rate of up to 500 ° C at 25 ° C / min and high temperature tempering has a hardness of HRC6.
It is a steel for high performance rolling dies that can obtain 4 or more.
【0006】さらに、特開平6−212253号公報
は、C:0.75〜1.75%、Si:0.5〜3.0
%、Mn:0.1〜2.0%、Cr:5.0〜11.0
%、Mo:1.3〜5.0%、V:0.1〜5.0%を
含有し、残部Feおよび不純物からなる鋼材を450℃
以上の温度で焼もどすことを特徴とする冷間工具鋼の製
造方法にある。すなわち、特開平3−134136号公
報、および特開平5−156407号公報のいずれも、
主に靱性の向上、炭化物の連鎖状分布を経路とした亀裂
伝播の抑制を目的としたものである。また、特開平6−
212253号公報は、450℃以上の温度で高温焼も
どしすることにより、焼入れ時の残留応力が除去されて
安定組織となるとともに二次硬化硬さが増加し、硬さお
よび靱性が共に優れ、工具としての使用時のかじりを起
こし、あるいは放電加工時により工具に熱が生ずる場合
にも割れを生ずることなく工具寿命が延長され加工性が
大幅に向上する。しかし焼もどし温度が450℃未満で
は充分に発揮されないというものである。Further, in JP-A-6-212253, C: 0.75 to 1.75%, Si: 0.5 to 3.0.
%, Mn: 0.1 to 2.0%, Cr: 5.0 to 11.0
%, Mo: 1.3 to 5.0%, V: 0.1 to 5.0%, and a steel material containing the balance Fe and impurities at 450 ° C.
A method of manufacturing a cold work tool steel is characterized by tempering at the above temperature. That is, both Japanese Patent Application Laid-Open No. 3-134136 and Japanese Patent Application Laid-Open No. 5-156407,
Its main purpose is to improve toughness and suppress crack propagation through the chain distribution of carbides. In addition, JP-A-6-
No. 212253 discloses that by high-temperature tempering at a temperature of 450 ° C. or higher, residual stress at the time of quenching is removed to form a stable structure and secondary hardening hardness increases, and both hardness and toughness are excellent, The tool life is extended and the workability is greatly improved without cracking even when the tool is galvanized during use or when heat is generated in the tool due to electric discharge machining. However, if the tempering temperature is less than 450 ° C, it will not be fully exhibited.
【0007】これに対し、本発明は前述同様に、M7 C
3 型炭化物の割れによる亀裂発生、および亀裂伝播が大
きな要因であることを見出し、しかも、そのM7 C3 型
炭化物の破壊起点が粒径15μmであることから、M7
C3 型炭化物を15μm以下とすると共に、高い応力が
加わる過酷な環境下で使用される工具において、焼戻温
度を150〜500℃の低温焼戻しをすることにより、
高温焼もどしよりも、残留オーステナイト量が多く形成
され、炭化物への応力集中が残留オーステナイトによっ
て緩和され、炭化物の割れが抑制され、また、炭化物の
割れによる亀裂発生および亀裂伝播が抑制され、より優
れた金型寿命のばらつき、および極度な低寿命金型を低
減し、金型の平均寿命の向上を図ることにある。On the other hand, the present invention is similar to the above, in the case of M 7 C
Cracking due to cracks in the 3 -type carbide, and found that crack propagation is a major factor, moreover, since the fracture origin of the M 7 C 3 type carbide is the particle size 15 [mu] m, M 7
By making the C 3 -type carbide 15 μm or less and using a low tempering temperature of 150 to 500 ° C. in a tool used in a severe environment where high stress is applied,
Larger amount of retained austenite is formed than in high temperature tempering, stress concentration on carbide is relaxed by retained austenite, cracking of carbide is suppressed, and crack generation and crack propagation due to cracking of carbide are suppressed. It is to improve the average life of the mold by reducing the variation of the mold life and the extremely short life of the mold.
【0008】[0008]
【発明が解決しようとする課題】上述した従来技術は、
靱性また強度の点から炭化物サイズを規制したものであ
る。この理由は、一次炭化物の欠落による微少欠損を生
じたり、クラックの進展経路となることを防ぐためであ
る。これに対し、近年の塑性加工技術の進歩や被加工材
の高強度化に伴い、工具の耐摩耗性向上を目的に、さら
に耐疲労性を兼ね供えた金型に適した工具鋼が必要とさ
れることから、本発明は、耐摩耗性を兼ね供えた引張圧
縮疲労強度の極めて優れた高寿命が得られる冷間工具鋼
の製造方法を提供することを目的とするものである。The above-mentioned conventional technique is
The carbide size is regulated in terms of toughness and strength. The reason for this is to prevent the occurrence of minute defects due to the lack of primary carbides and the formation of crack propagation paths. On the other hand, with the recent progress in plastic working technology and higher strength of work materials, it is necessary to have tool steel suitable for dies that also has fatigue resistance for the purpose of improving wear resistance of tools. Therefore, it is an object of the present invention to provide a method for producing a cold work tool steel having excellent wear resistance and excellent tensile and compression fatigue strength and a long life.
【0009】[0009]
【課題を解決するための手段】その発明の要旨とすると
ころは、
(1)重量%で、C:0.65〜1.3%、Si:2.
0%以下、Mn:0.1〜2.0%、Cr:5.0〜1
1.0%、MoまたはWのいずれか1種または2種をM
o当量(Mo+1/2W):0.7〜5.0%、Vまた
はNbのいずれか1種または2種をV当量(V+1/2
Nb):0.1〜2.5%、残部Feおよび不可避的不
純物よりなる鋼を、850〜1200℃で鍛造または熱
間圧延した後、焼きなまして、M7 C3 型炭化物の粒径
を5〜15μm、面積率1〜9%を有する鋼材とし、該
鋼材を焼入し、続いて150〜500℃の温度で焼戻す
ことを特徴とする冷間工具鋼の製造方法。
(2)前記(1)に記載の焼戻温度を150〜450℃
未満で焼戻すことを特徴とする冷間工具鋼の製造方法に
ある。Means for Solving the Problems The gist of the invention is as follows: (1) wt%, C: 0.65 to 1.3%, Si: 2.
0% or less, Mn: 0.1 to 2.0%, Cr: 5.0 to 1
1.0%, either 1 or 2 of Mo or W is M
o Equivalent (Mo + 1 / 2W): 0.7 to 5.0%, one or two of V or Nb is V equivalent (V + 1/2)
Nb): 0.1 to 2.5%, steel consisting of balance Fe and unavoidable impurities is forged or hot-rolled at 850 to 1200 ° C. and then annealed so that the grain size of M 7 C 3 type carbide is 5 15 m, the steel having 1-9% area ratio, the
A method for producing a cold work tool steel, which comprises quenching a steel material and subsequently tempering it at a temperature of 150 to 500 ° C. (2) The tempering temperature described in (1) above is 150 to 450 ° C.
It is a method for producing a cold work tool steel, which is characterized by tempering at a temperature lower than that.
【0010】[0010]
【発明の実施の形態】以下に、本発明鋼の各化学成分の
作用およびその限定理由を説明する。Cは、焼入焼戻に
より、十分なマトリックス硬さを与えると共に、Cr,
Mo,V,Nbなどと結合して炭化物を形成し、高温強
度、耐摩耗性を与える元素である。しかし、添加量が多
過ぎると、凝固時に粗大炭化物が過剰に析出し靱性を阻
害することから、Cの上限を1.3%とした。一方、
0.65%未満では、十分な二次硬化硬さが得られない
ので、その下限を0.65%としたが、強度と靱性の最
適バランスを得るためには、0.75〜1.1%の範囲
が望ましい。BEST MODE FOR CARRYING OUT THE INVENTION The actions of each chemical component of the steel of the present invention and the reasons for limiting the chemical components will be described below. C gives sufficient matrix hardness by quenching and tempering, and
It is an element that combines with Mo, V, Nb and the like to form a carbide, which gives high temperature strength and wear resistance. However, if the addition amount is too large, coarse carbides will excessively precipitate during solidification and inhibit the toughness, so the upper limit of C was made 1.3%. on the other hand,
If it is less than 0.65%, sufficient secondary hardening hardness cannot be obtained, so the lower limit was made 0.65%, but in order to obtain the optimum balance between strength and toughness, 0.75 to 1.1 The range of% is desirable.
【0011】Siは、主に脱酸剤として添加されると共
に、耐酸化性、焼入性に有効な元素であると共に、焼戻
過程において炭化物の凝集を抑え二次硬化を促進する元
素である。しかし、2.0%を越えて添加すると、靱性
を低下させるので、その上限を2.0%とした。Mn
は、Siと同様に脱酸剤として添加し鋼の清浄度を高め
ると共に焼入れ性を高める元素である。しかしながら、
2.0%を越えて添加すると、冷間加工性を阻害するう
えに靱性を低下させるので、その上限を2.0%とし
た。Si is an element that is mainly added as a deoxidizer and is effective for oxidation resistance and hardenability, and is an element that suppresses agglomeration of carbides in the tempering process and promotes secondary hardening. . However, if added over 2.0%, the toughness is lowered, so the upper limit was made 2.0%. Mn
Is an element which, like Si, is added as a deoxidizer to enhance the cleanliness of steel and to enhance the hardenability. However,
If added over 2.0%, the cold workability is impaired and the toughness is lowered, so the upper limit was made 2.0%.
【0012】Crは、焼入れ性を高めると共に、焼戻軟
化抵抗を高める有効な元素である。この効果を満足する
ためには、少なくとも5.0%以上必要である。従っ
て、その下限を5.0%とした。一方、Crは、凝固時
にCと結合して巨大一次炭化物を形成し易く、過剰な添
加は、靱性を低下させるため、その上限を11.0%、
とした。[0012] Cr is an effective element that enhances the hardenability and the temper softening resistance. To satisfy this effect, at least 5.0% or more is necessary. Therefore, the lower limit is set to 5.0%. On the other hand, Cr easily combines with C during solidification to form a giant primary carbide, and excessive addition thereof lowers toughness, so its upper limit is 11.0%,
And
【0013】MoおよびWは、共に微細な炭化物を形成
し、二次硬化に寄与する重要な元素であると共に、耐軟
化抵抗性を改善する元素である。ただし、その効果はM
o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。本発明成分系
においては、Mo当量で少なくとも0.7%以上が必要
である。逆に、Mo当量の過剰添加は、靱性を低下を招
くので、その上限を5.0%とした。Mo and W are both important elements that form fine carbides and contribute to secondary hardening, and also improve softening resistance. However, the effect is M
O is twice as strong as W, and W needs twice as much Mo as to obtain the same effect. The effects of these two elements can be expressed by the Mo equivalent (Mo + 1 / 2W). In the component system of the present invention, Mo equivalent of at least 0.7% is required. On the other hand, excessive addition of the Mo equivalent causes a decrease in toughness, so the upper limit was made 5.0%.
【0014】V、Nbは、共に二次硬化に有効であり、
Cと硬い炭化物を形成して耐摩耗性の向上に大きく寄与
すると共に結晶粒を微細化する。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。本発明成分系にお
いては、高温焼戻し硬度を得るためには、V当量で少な
くとも0.1%以上が必要である。過剰な添加は靱性を
劣化させるため、その上限を2.5%とした。Both V and Nb are effective for secondary curing,
It forms a hard carbide with C, greatly contributes to the improvement of wear resistance, and refines the crystal grains. However, the effect is V
Is twice as strong as Nb, and Nb
Is required to be twice V. The effect of these two elements is V equivalent (V
+ 1 / 2Nb). In the component system of the present invention, V equivalent of at least 0.1% or more is required to obtain high temperature tempering hardness. Excessive addition deteriorates toughness, so the upper limit was made 2.5%.
【0015】次に、冷間工具鋼において、凝固時に晶出
する共晶炭化物であるが、従来は靱性、または強度の点
から炭化物のサイズを規定していたものである。その理
由は、一次炭化物の欠落による微小欠損を生じたり、ク
ラックの進展経路となることを防ぐために規制したもの
である。しかし、この点を詳しく究明した結果、本発明
の最大の特徴は、特に冷間工具鋼としての金型ダイス等
の工具寿命を左右する要因としての引張圧縮疲労での優
れた寿命が必要で、実際の金型において、疲労に起因し
た破損は、M7 C3 型炭化物の割れによる亀裂発生、お
よび亀裂伝播が大きな要因を占めていることを見出し、
そのためには、M7 C3 型炭化物の粒径が15μm以下
の場合に著しく軽減することを見出したものである。Next, in cold work tool steels, eutectic carbides that crystallize during solidification, but conventionally, the size of the carbides has been specified in terms of toughness or strength. The reason for this is that it is regulated in order to prevent minute defects due to lack of primary carbides and to prevent cracks from becoming the path of propagation. However, as a result of investigating this point in detail, the greatest feature of the present invention is that excellent life in tensile compression fatigue as a factor that influences the tool life of a die such as a cold die tool steel is particularly required. In an actual die, it was found that the fatigue-induced damage is mainly caused by crack generation due to cracking of M 7 C 3 -type carbide and crack propagation.
To that end, they have found that the M 7 C 3 type carbide is remarkably reduced when the particle size is 15 μm or less.
【0016】図1は、M7 C3 型炭化物サイズと破断繰
返し数および耐摩耗性との関係を示す図である。この図
によれば、引張圧縮疲労試験の結果によれば、M7 C3
型炭化物の粒径が15μmを越えると著しく破断繰返し
数(N)が減少することが判明した。一方、大越式摩耗
試験の結果によると、M7 C3 型炭化物の粒径が5μm
未満で著しく耐摩耗性の減少が現れることが判明した。
その結果、両者の要因による金型寿命によって、M7 C
3 型炭化物の粒径を5〜15μmの範囲に規制すること
が最適であることを究明した。すなわち、M7 C3 型炭
化物の粒径について、引張圧縮疲労と疲労に起因した破
損から15μm以下が好ましい。また、耐摩耗性の観点
から5μm以上が望ましい。さらに、M7 C3 型炭化物
の面積率は、耐摩耗性の観点からは炭化物が多いほど良
好となり、少なくとも1%以上のM7 C3 型炭化物が必
要となる。一方、耐疲労特性の点から、炭化物をできる
かぎり均一に分散させるため、9%以下とすることが望
ましい。従って、M7 C3型炭化物の面積率を1〜9%
とした。FIG. 1 is a diagram showing the relationship between the size of M 7 C 3 type carbides, the number of repeated fractures, and the wear resistance. According to this figure, according to the result of the tensile compression fatigue test, M 7 C 3
It was found that the number of repeated fractures (N) remarkably decreased when the grain size of the type carbides exceeded 15 μm. On the other hand, according to the results of the Ogoshi-type wear test, the grain size of M 7 C 3 type carbide is 5 μm.
It was found that the wear resistance was remarkably reduced when the amount was less than 1.
As a result, due to the mold life due to both factors, M 7 C
It has been clarified that it is optimum to regulate the grain size of the type 3 carbide in the range of 5 to 15 μm. That is, the grain size of the M 7 C 3 type carbide is preferably 15 μm or less due to tensile compression fatigue and damage due to fatigue. Further, from the viewpoint of wear resistance, 5 μm or more is desirable. Further, the area ratio of the M 7 C 3 -type carbide becomes better as the amount of the carbide increases from the viewpoint of wear resistance, and at least 1% or more of the M 7 C 3 -type carbide is required. On the other hand, from the viewpoint of fatigue resistance, it is desirable to be 9% or less in order to disperse the carbide as uniformly as possible. Therefore, the area ratio of M 7 C 3 -type carbide is 1 to 9%.
And
【0017】図2は、M7 C3 型炭化物サイズと金型寿
命(ショット数)との関係を示す図である。この図によ
れば、摩耗による金型の廃却、および炭化物の割れに起
因した廃却からの金型寿命を試験した結果、比較鋼E
(焼戻し180℃)では、摩耗による金型の廃却とな
り、また、比較鋼F(焼戻し300℃)の場合は低温焼
戻ではあるが、炭化物の割れに起因した廃却となり、さ
らに、500℃超〜550℃の高温焼戻しでは、本発明
による150〜500℃の低温焼戻しに比較して炭化物
の割れによる廃却から金型寿命としての指数であるショ
ット数の低いことが分かる。すなわち、150〜500
℃の低温焼戻の場合と500℃を超えて550℃の高温
焼戻の場合を比較すると、高温焼戻に比べて低温焼戻の
場合の方が金型寿命の延長が図られていることが明確に
分かる。FIG. 2 is a graph showing the relationship between M 7 C 3 type carbide size and die life (number of shots). According to this figure, as a result of testing the mold life due to wear and the mold life from the scrap due to the cracking of carbides, the comparative steel E
At (tempering 180 ° C.), the die is abandoned due to wear, and in the case of comparative steel F (tempering 300 ° C.), although it is a low temperature tempering, it is abandoned due to cracking of carbide, and further 500 ° C. It can be seen that in the high temperature tempering of super to 550 ° C., the number of shots, which is an index as the life of the die, is lower than the low temperature tempering of 150 to 500 ° C. according to the present invention because of the scrapping due to the cracking of the carbide. That is, 150 to 500
Comparing the case of low temperature tempering of ℃ ℃ and the case of high temperature tempering exceeding 500 ℃ to 550 ℃, die life is extended in the case of low temperature tempering as compared to high temperature tempering Is clearly understood.
【0018】図3は、焼戻温度と金型寿命(ショット
数)との関係を示す図である。この図3に示すように、
例えばA鋼およびC鋼での焼戻温度での金型寿命(ショ
ット数)は焼戻温度が150〜500℃において、いず
れも、ほぼ同様な傾向でショット数30000以上を得
ることが出来るのに対して、焼戻温度500℃を超える
温度で処理した場合には、ショット数30000以下と
なり、金型寿命が低下していることが分かる。このこと
から明らかなように、本発明における焼戻温度を150
〜500℃に規制した。なお、好ましくは焼戻温度とし
ては、150〜450℃未満とする。FIG. 3 is a graph showing the relationship between tempering temperature and die life (number of shots). As shown in this FIG.
For example, the die life (the number of shots) at the tempering temperature of the A steel and the C steel can obtain a shot number of 30,000 or more in almost the same tendency when the tempering temperature is 150 to 500 ° C. On the other hand, when the tempering temperature is higher than 500 ° C., the number of shots is 30,000 or less, which means that the die life is shortened. As is clear from this, the tempering temperature in the present invention is 150.
It was regulated to ~ 500 ° C. The tempering temperature is preferably 150 to less than 450 ° C.
【0019】[0019]
【実施例】以下に、本発明を実施例に基づいて具体的に
説明する。表1に示す化学組成を有する鋼を真空誘導溶
解炉にて溶製した。鋼種A〜Dは本発明鋼であり、E,
Fは比較鋼である。これらの鋼塊を850〜1200℃
で鍛造又は熱間圧延して、860℃で焼なまして、それ
ぞれを供試材とした。これら供試材を1040℃から焼
入れ後、表2に示す焼戻温度で焼戻して本発明鋼及び比
較鋼の工具鋼とする。また、引張圧縮疲労試験は、平行
部、径5×15mmの試験片を加工後、油圧サーボ試験
機を用い、応力振幅1300MPa、応力比R=−1、
室温の条件下で行った。EXAMPLES The present invention will be specifically described below based on examples. Steel having the chemical composition shown in Table 1 was melted in a vacuum induction melting furnace. Steel types A to D are steels of the present invention, and E,
F is a comparative steel. These steel ingots at 850 to 1200 ° C
Was forged or hot rolled, and annealed at 860 ° C. to obtain test materials. After quenching these test materials from 1040 ° C., they are tempered at the tempering temperatures shown in Table 2 to obtain tool steels of the present invention steel and comparative steel. Further, in the tensile compression fatigue test, after processing a test piece having a parallel portion and a diameter of 5 × 15 mm, a stress amplitude 1300 MPa, a stress ratio R = −1, using a hydraulic servo tester.
It was performed at room temperature.
【0020】[0020]
【表1】 [Table 1]
【0021】大越式摩耗試験は、SCM420(86H
RB)を相手材とし、摩耗距離200m、最終荷重62
Nの条件下で行い、試験結果は比較鋼9の摩耗量を10
0として表した。さらに、実機での金型試験は、径12
0×100mmの鍛造用金型を作製し、SCM420を
被加工材として試験を行った。金型は摩耗または割れに
よって廃却となり、割れによって廃却された金型は、廃
却金型の内部を調査した結果、炭化物の割れが破壊起点
となった。また、炭化物の規定方法としては、測定面、
T面1/4部、粒径は画像処理装置による円相当径、面
積率は画像処理装置により測定し、M7 C3 炭化物につ
いては、本発明では、2μm以上の炭化物を全てM7 C
3 型炭化物とみなした。The Ogoshi-type wear test is conducted using the SCM420 (86H
RB) as the mating material, wear distance 200m, final load 62
The test results show that the amount of wear of the comparative steel 9 is 10
Expressed as 0. In addition, the die test on the actual machine is 12
A 0 × 100 mm forging die was prepared and tested using SCM420 as a work material. The die was abandoned due to wear or cracks, and the die abandoned due to the cracks was examined inside the abandoned die, and as a result, the cracking of the carbide was the starting point of the fracture. In addition, as a method of defining the carbide, the measurement surface,
T surface 1/4 part, particle size was measured by an image processing device, and area ratio was measured by an image processing device. For M 7 C 3 carbide, in the present invention, all carbides of 2 μm or more were M 7 C.
It was regarded as type 3 carbide.
【0022】その結果を表2に示す。表2に示すよう
に、本発明鋼No1〜8はいずれもM 7 C3 炭化物粒径
5〜15μmであり、しかも、M7 C3 炭化物面積率
(%)が1〜9%の範囲であり、焼戻し温度が150〜
500℃の範囲内で行ったもので、その場合の硬さ(H
RC)は、いずれも59HRC以上の硬さを維持した上
で、従来の冷間工具鋼No9〜12よりもはるかに優れ
た引張圧縮疲労寿命、金型寿命延長をはかることが出来
た。The results are shown in Table 2. As shown in Table 2
In the present invention steel Nos. 1 to 8 are all M 7C3Carbide particle size
5 to 15 μm and M7C3Carbide area ratio
(%) Is in the range of 1 to 9%, and the tempering temperature is 150 to
Hardness in that case (H
(RC) has a hardness of 59 HRC or higher.
Is far superior to conventional cold work tool steel No. 9-12
It is possible to extend the tensile compression fatigue life and mold life.
It was
【0023】[0023]
【表2】 [Table 2]
【0024】[0024]
【発明の効果】以上述べたように、本発明鋼は、冷間工
具鋼としての一定範囲のM7 C3 炭化物の粒径およびM
7 C3 炭化物の面積率を一定範囲に規制、並びに焼戻温
度で焼戻しすることにより、極めて優れた型寿命を確保
することが可能となり、金型用工具鋼として従来のもの
に比べて経済的で極めて有利なものとなった。As described above, the steel of the present invention has a certain range of M 7 C 3 carbide grain size and M as a cold tool steel.
By controlling the area ratio of 7 C 3 carbide within a certain range and tempering at the tempering temperature, it becomes possible to secure an extremely long mold life and it is more economical than conventional tool steel for molds. It became very advantageous in.
【図1】M7 C3 型炭化物サイズと破断繰返し数および
耐摩耗性との関係を示す図である。FIG. 1 is a diagram showing the relationship between the size of M 7 C 3 type carbides, the number of repeated fractures, and the wear resistance.
【図2】M7 C3 型炭化物サイズと金型寿命(ショット
数)との関係を示す図である。FIG. 2 is a diagram showing a relationship between M 7 C 3 type carbide size and die life (number of shots).
【図3】焼戻温度と金型寿命(ショット数)との関係を
示す図である。FIG. 3 is a diagram showing a relationship between tempering temperature and die life (number of shots).
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7,DB名) C21D 6/00 C22C 38/00 - 38/60 ─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. 7 , DB name) C21D 6/00 C22C 38/00-38/60
Claims (2)
o+1/2W):0.7〜5.0%、 VまたはNbのいずれか1種または2種をV当量(V+
1/2Nb):0.1〜2.5%、 残部Feおよび不可避的不純物よりなる鋼を、850〜
1200℃で鍛造または熱間圧延した後、焼きなまし
て、M7 C3 型炭化物の粒径を5〜15μm、面積率1
〜9%を有する鋼材とし、該鋼材を焼入し、続いて15
0〜500℃の温度で焼戻すことを特徴とする冷間工具
鋼の製造方法。1. By weight%, C: 0.65 to 1.3%, Si: 2.0% or less, Mn: 0.1 to 2.0%, Cr: 5.0 to 11.0%, Any one or two of Mo and W is equivalent to Mo (M
o + 1 / 2W): 0.7 to 5.0%, one or two of V or Nb in V equivalent (V +
1/2 Nb): 0.1 to 2.5%, steel consisting of balance Fe and unavoidable impurities,
After forging or hot rolling at 1200 ° C., it is annealed to have a grain size of M 7 C 3 type carbide of 5 to 15 μm and an area ratio of 1
Steel material having ˜9%, quenching the steel material , followed by 15
A method for producing cold work tool steel, which comprises tempering at a temperature of 0 to 500 ° C.
50℃未満で焼戻すことを特徴とする冷間工具鋼の製造
方法。2. The tempering temperature according to claim 1 is 150 to 4.
A method for producing a cold work tool steel, which comprises tempering at a temperature of less than 50 ° C.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP02130298A JP3499425B2 (en) | 1998-02-02 | 1998-02-02 | Manufacturing method of cold tool steel |
EP98109889A EP0930374B1 (en) | 1998-01-06 | 1998-05-29 | Production of cold working tool steel |
AT98109889T ATE206485T1 (en) | 1998-01-06 | 1998-05-29 | THE PRODUCTION OF COLD WORK TOOL STEEL |
US09/086,487 US6053991A (en) | 1998-01-06 | 1998-05-29 | Production of cold working tool steel |
DE69801890T DE69801890T2 (en) | 1998-01-06 | 1998-05-29 | The production of a cold work tool steel |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP02130298A JP3499425B2 (en) | 1998-02-02 | 1998-02-02 | Manufacturing method of cold tool steel |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH11222624A JPH11222624A (en) | 1999-08-17 |
JP3499425B2 true JP3499425B2 (en) | 2004-02-23 |
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ID=12051361
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KR20110042131A (en) * | 2002-06-13 | 2011-04-22 | 우데홀름스 악티에보라그 | Cold work steel and cold work tool |
JP5748983B2 (en) * | 2010-11-15 | 2015-07-15 | 山陽特殊製鋼株式会社 | Aluminum can tool excellent in seizure resistance and manufacturing method thereof |
EP2662166A1 (en) * | 2012-05-08 | 2013-11-13 | Böhler Edelstahl GmbH & Co KG | Material with high wear resistance |
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