JPH11222624A - Production of cold tool steel - Google Patents
Production of cold tool steelInfo
- Publication number
- JPH11222624A JPH11222624A JP2130298A JP2130298A JPH11222624A JP H11222624 A JPH11222624 A JP H11222624A JP 2130298 A JP2130298 A JP 2130298A JP 2130298 A JP2130298 A JP 2130298A JP H11222624 A JPH11222624 A JP H11222624A
- Authority
- JP
- Japan
- Prior art keywords
- carbide
- tempering
- less
- temperature
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
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 producing a long-life cold work tool steel having excellent fatigue resistance.
【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
KD11 is widely used. However, plastic working technology
Tools to be used in accordance with the progress of
Stress load is large, and 60 HR
Even SKD11, which gives C hardness, has a coarse M7CThree
The wear resistance is secured by the type carbide, but M
7CThreeMold carbides contribute to reduced mold life
I have. To solve such a problem, see, for example,
1442, JP-A-2-247357, JP-A-2-247357
JP-A-2-277745, JP-A-3-134136
And the inventions of JP-A-5-156407.
Is being planned.
【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。[0003] Japanese Patent Application Laid-Open No. Hei 1-2201442 discloses that C: 0.90 to 1.35% and Si: 0.70% 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
A species containing 1.5 to 2.5% of Mo + W / 2 and one or two of V and Nb of 0.15 to 2.5% of V + Nb / 2, the balance being Fe and unavoidable impurities; In a quenched and tempered structure, there is a rolling die steel in which the area ratio of M 7 C 3 type carbide is 2% or more and 9% or less, and the area ratio of MC carbide is 2.5% or less. Certainly, the present invention regulates the area ratio and the grain size of carbides, but mainly aims at improving toughness and suppressing crack propagation through a chain distribution of carbides. It is. On the other hand, the present invention has found that factors that cause variation in mold life and extremely low life are major factors such as crack generation and crack propagation due to cracking of M 7 C 3 type carbide,
To this end, by setting the M 7 C 3 type carbide to 15 μm or less, it is possible to reduce the variation in the life of the mold and the extremely low life mold, thereby improving the average life of the mold.
【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 Application Laid-Open No. 2-247357 discloses that
Japanese Unexamined Patent Publication (Kokai) No. Hei 1-2201442 further discloses a rolling die steel having a total amount of impurities of As, Sn, Sb, Cu, B, Pb, and Bi of 0.13% or less.
Further, Japanese Patent Application Laid-Open No. 2-277745 discloses that in a quenched and tempered structure, the total area ratio of one or two of MC-type residual carbide and M 6 C-type residual carbide having a particle size of 2 μm or more is 3% or less, The area ratio of the M 7 C 3 type residual carbide having a particle size of 2 μm or more is regulated to 1% or less. In each case, as in JP-A-1-201442, mainly improvement in toughness,
The purpose is to suppress crack propagation through the chain distribution of carbides. In contrast, the present invention has found that, as described above, crack generation and crack propagation due to cracks in M 7 C 3 type carbides are major factors, and furthermore, the fracture origin of the M 7 C 3 type carbides is It has been 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 Application Publication No. 3-134136 also discloses the above-mentioned Japanese Unexamined Patent Application Publication No. Hei 1-2201442. Further, among the unavoidable impurities, 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 further, in the quenched and tempered 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.
A high-hardness, high-toughness cold tool having a total area ratio of one or two types of residual carbides of MC type and M 6 C type having a m of not less than 3% is 3% or less.
No. 07 discloses that after quenching and tempering, the M 7 C 3 type primary carbide has an area ratio of 4.0% or less, the MC type primary carbide has an area ratio of 0.5% or less, and the maximum particle size of the primary carbide is 0.5% or less. Substantially a microstructure uniformly dispersed in the matrix at 20 µm or less, and further from a quenching temperature of 1050 ° C to 1100 ° C,
The hardness when quenching at a quenching cooling rate of up to 500 ° C. of 25 ° C./min and tempering at a high temperature is HRC6.
High performance rolling die steel 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, JP-A-6-212253 discloses that C: 0.75 to 1.75% and 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 the balance of Fe and impurities is 450 ° C.
A method for producing a cold tool steel characterized by tempering at the above temperature. That is, in each of JP-A-3-134136 and JP-A-5-156407,
The main purpose is to improve toughness and to suppress crack propagation through the chain distribution of carbides. In addition, Japanese Unexamined Patent Publication No.
No. 212253 discloses that by performing high-temperature tempering at a temperature of 450 ° C. or more, residual stress during quenching is removed, a stable structure is obtained, secondary hardening hardness is increased, and both hardness and toughness are excellent. When the tool is used as a tool, the tool life is extended and the workability is greatly improved without cracking even when the tool generates heat due to electric discharge machining. However, if the tempering temperature is lower than 450 ° C., it cannot be sufficiently 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, according to the present invention, 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
While less 15μm to C 3 -type carbides in tools used in harsh environments where high stress is applied, by low-temperature tempering of 150 to 500 ° C. The tempering temperature,
Compared to high-temperature tempering, the amount of retained austenite is formed more, stress concentration on carbides is alleviated by the retained austenite, carbide cracking is suppressed, and crack generation and crack propagation due to carbide cracking are suppressed, which is more excellent. It is an object of the present invention to reduce the variation in the mold life and the extremely low life mold to improve the average 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 prior art described above is
The size of the carbide 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 the primary carbides and the prevention of cracks from becoming a propagation path. On the other hand, with the recent progress of plastic working technology and the strengthening of the work material, tool steel suitable for molds with more fatigue resistance is required for the purpose of improving wear resistance of tools. Accordingly, an object of the present invention is to provide a method for producing a cold tool steel which has 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
純物よりなり、M7 C3 型炭化物の粒径を5〜15μ
m、面積率1〜9%を有する鋼材を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。SUMMARY OF THE INVENTION The gist of the present invention is as follows: (1) C: 0.65 to 1.3% by weight;
0% or less, Mn: 0.1 to 2.0%, Cr: 5.0 to 1
1.0%, any one or two of Mo or W
o equivalent (Mo + 1 / 2W): 0.7-5.0%, one or two of V or Nb is V equivalent (V + 1/2)
Nb): 0.1 to 2.5%, the balance being Fe and unavoidable impurities, and the particle size of M 7 C 3 type carbide is 5 to 15 μm.
m, tempering a steel material having an area ratio of 1 to 9% at a temperature of 150 to 500 ° C. (2) The tempering temperature according to (1) is set to 150 to 450 ° C.
A method for producing cold tool steel, characterized by tempering at less than.
【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 function of each chemical component of the steel of the present invention and the reasons for limiting the same will be described below. C provides sufficient matrix hardness by quenching and tempering, and Cr,
It is an element that combines with Mo, V, Nb, etc. to form carbides and imparts high-temperature strength and wear resistance. However, if the added amount is too large, coarse carbides are excessively precipitated during solidification and hinder toughness. Therefore, the upper limit of C is set to 1.3%. on the other hand,
If it is less than 0.65%, sufficient secondary hardening hardness cannot be obtained. Therefore, the lower limit is set to 0.65%. However, in order to obtain an optimum balance between strength and toughness, 0.75 to 1.1 is required. % 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 deoxidizing agent, is effective in oxidation resistance and hardenability, and suppresses agglomeration of carbides during tempering and promotes secondary hardening. . However, if added in excess of 2.0%, the toughness is reduced, so the upper limit was made 2.0%. Mn
Is an element that is added as a deoxidizing agent similarly to Si to increase the cleanliness of the steel and increase the hardenability. However,
If added in excess of 2.0%, the cold workability is impaired and the toughness is reduced, 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 hardenability and also enhances tempering softening resistance. To satisfy this effect, at least 5.0% or more is required. Therefore, the lower limit was set to 5.0%. On the other hand, Cr is easily combined with C at the time of solidification to form a giant primary carbide, and excessive addition lowers toughness, so the 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 are elements that improve resistance to softening. However, the effect is M
o is twice as strong as W and W is twice as much as Mo to get the same effect. The effect of these two elements can be represented by the Mo equivalent (Mo + / W). In the component system of the present invention, the Mo equivalent is required to be at least 0.7% or more. Conversely, excessive addition of Mo equivalents causes toughness to decrease, 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。V and Nb are both effective for secondary curing.
It forms hard carbides with C to greatly contribute to improvement of wear resistance and to refine crystal grains. However, the effect is V
Is twice as strong as Nb, and to obtain the same effect, Nb
Is twice as large as V. The effect of these two elements is V equivalent (V
+ 1 / 2Nb). In the component system of the present invention, in order to obtain a high temperature tempering hardness, at least 0.1% or more in V equivalent is necessary. Excessive addition degrades 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 the cold tool steel, eutectic carbide which is crystallized at the time of solidification is conventionally defined in terms of toughness or strength. The reason is that it is regulated in order to prevent the occurrence of minute defects due to the loss of the primary carbides and the prevention of cracks from forming a propagation path. However, as a result of elucidating this point in detail, the greatest feature of the present invention is that an excellent life in tensile and compression fatigue as a factor that affects the tool life of a mold die and the like as a cold tool steel is necessary, In the actual mold, the failure due to fatigue was found to be mainly caused by crack generation and crack propagation due to cracking of M 7 C 3 type carbide,
For this purpose, it has been found that when the particle diameter of the M 7 C 3 type carbide is 15 μm or less, it is significantly reduced.
【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 graph showing the relationship between the M 7 C 3 type carbide size, the number of repetitions of fracture and the wear resistance. According to the figure, according to the results of the tensile compression fatigue test, M 7 C 3
It has been found that when the grain size of the type carbide exceeds 15 μm, the number of repetitions of fracture (N) is significantly reduced. On the other hand, according to the results of the Ogoshi type abrasion test, the particle size of the M 7 C 3 type carbide was 5 μm.
It has been found that when the amount is less than 1, a marked decrease in wear resistance appears.
As a result, M 7 C
It has been found that it is optimal to regulate the particle size of the type 3 carbide in the range of 5 to 15 μm. That is, the particle size of the M 7 C 3 type carbide is preferably 15 μm or less in view of tensile compression fatigue and breakage caused by fatigue. Further, from the viewpoint of abrasion resistance, 5 μm or more is desirable. Furthermore, 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, the content is desirably 9% or less in order to disperse 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 diagram showing the relationship between the M 7 C 3 type carbide size and the mold life (number of shots). According to this figure, as a result of testing the mold life from the disposal of the mold due to wear and the disposal due to the cracking of the carbide, the comparative steel E
(Temperature 180 ° C.), the mold was discarded due to abrasion, and in the case of comparative steel F (tempered 300 ° C.), although it was low-temperature tempering, it was scrapped due to cracking of carbide, and further 500 ° C. It can be seen that the number of shots, which is an index as a tool life, is lower in the high-temperature tempering of from super to 550 ° C. than in the low-temperature tempering of 150 to 500 ° C. according to the present invention due to the discard due to carbide cracking. That is, 150 to 500
When comparing the case of low-temperature tempering at 500 ° C with the case of high-temperature tempering exceeding 550 ° C, the life of the mold is longer in the case of low-temperature tempering than in the case of 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 diagram showing the relationship between the tempering temperature and the mold life (number of shots). As shown in FIG.
For example, the mold life (the number of shots) at the tempering temperature of steel A and steel C can be obtained at a tempering temperature of 150 to 500 [deg.] C., although the number of shots can be more than 30,000 with almost the same tendency. On the other hand, when the treatment was performed at a temperature exceeding the tempering temperature of 500 ° C., the number of shots was 30,000 or less, which indicates that the mold life was shortened. As is clear from this, the tempering temperature in the present invention is set to 150
Regulated to ~ 500 ° C. Preferably, the tempering temperature is 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。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Steel having the chemical composition shown in Table 1 was melted in a vacuum induction melting furnace. Steel types A to D are the steels of the present invention.
F is a comparative steel. 850-1200 ° C
Forging or hot rolling, and annealing 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 and comparative steels. Further, the tensile compression fatigue test was performed by processing a test piece having a parallel portion and a diameter of 5 × 15 mm, and then using a hydraulic servo testing machine to obtain a stress amplitude of 1300 MPa, a stress ratio of R = −1,
The test 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 abrasion test was performed using SCM420 (86H
RB) as the mating material, wear distance 200m, final load 62
The test results showed that the wear amount of the comparative steel 9 was 10
It was expressed as 0. In addition, the mold test on the actual
A 0 × 100 mm forging die was prepared, and a test was performed using SCM420 as a workpiece. The mold was discarded due to abrasion or cracking, and as a result of investigating the inside of the discarded mold, the cracks of the carbides became the destruction starting point. In addition, as a method for defining the carbide, the measurement surface,
A 1/4 part of the T plane, the particle diameter was measured by an image processing device, and the area ratio was measured by an image processing device. As for M 7 C 3 carbide, in the present invention, all of the carbide having a size of 2 μm or more was M 7 C
It was considered 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。Table 2 shows the results. As shown in Table 2
The steels Nos. 1 to 8 of the present invention all have M 7CThreeCarbide particle size
5 to 15 μm, and M7CThreeCarbide area ratio
(%) Is in the range of 1 to 9%, and the tempering temperature is 150 to
The test was performed within the range of 500 ° C, and the hardness (H
RC), while maintaining a hardness of 59 HRC or more
In, much better than conventional cold tool steel No. 9-12
Extended tensile and compression fatigue life and extended mold life
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 particle size and M
By regulating the area ratio of 7 C 3 carbide to a certain range and tempering at the tempering temperature, it is possible to secure an extremely excellent mold life, and it is more economical as a tool steel for molds than conventional steel. Became very advantageous.
【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 graph showing the relationship between the M 7 C 3 type carbide size, 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 mold 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 a tempering temperature and a mold life (the number of shots).
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
避的不純物よりなり、M7 C3 型炭化物の粒径を5〜1
5μm、面積率1〜9%を有する鋼材を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。C. 0.65 to 1.3%, Si: 2.0% or less, Mn: 0.1 to 2.0%, Cr: 5.0 to 11.0% by weight%. One or two of Mo and W are used at the Mo equivalent (M
o + 1 / 2W): 0.7-5.0%, one or two of V or Nb is V equivalent (V +
NNb): 0.1 to 2.5%, the balance being Fe and unavoidable impurities, and the particle size of the M 7 C 3 type carbide is 5 to 1
5 to 50% of steel material having an area ratio of 1 to 9%
A method for producing cold tool steel, characterized by tempering at a temperature of ° 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, wherein the tempering temperature is 150-4.
A method for producing cold tool steel, characterized by tempering at less than 50 ° C.
Priority Applications (5)
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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 |
DE69801890T DE69801890T2 (en) | 1998-01-06 | 1998-05-29 | The production of a cold work tool steel |
US09/086,487 US6053991A (en) | 1998-01-06 | 1998-05-29 | Production of cold working tool steel |
Applications Claiming Priority (1)
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JP02130298A JP3499425B2 (en) | 1998-02-02 | 1998-02-02 | Manufacturing method of cold tool steel |
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JPH11222624A true JPH11222624A (en) | 1999-08-17 |
JP3499425B2 JP3499425B2 (en) | 2004-02-23 |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005530041A (en) * | 2002-06-13 | 2005-10-06 | ウッデホルム トウリング アクテイエボラーグ | Cold work steel and cold work tool |
JP2012107265A (en) * | 2010-11-15 | 2012-06-07 | Sanyo Special Steel Co Ltd | Tool for manufacturing aluminum can having excellent seizure resistance and method for manufacturing the same |
JP2013234387A (en) * | 2012-05-08 | 2013-11-21 | Boehler Edelstahl Gmbh & Co Kg | Material with high wear resistance |
-
1998
- 1998-02-02 JP JP02130298A patent/JP3499425B2/en not_active Expired - Fee Related
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005530041A (en) * | 2002-06-13 | 2005-10-06 | ウッデホルム トウリング アクテイエボラーグ | Cold work steel and cold work tool |
JP4805574B2 (en) * | 2002-06-13 | 2011-11-02 | ウッデホルムス アーベー | Cold work steel and cold work tool |
KR101360922B1 (en) * | 2002-06-13 | 2014-02-11 | 우데홀름스 악티에보라그 | Cold work steel and cold work tool |
US8900382B2 (en) * | 2002-06-13 | 2014-12-02 | Uddeholm Tooling Aktiebolag | Hot worked steel and tool made therewith |
JP2012107265A (en) * | 2010-11-15 | 2012-06-07 | Sanyo Special Steel Co Ltd | Tool for manufacturing aluminum can having excellent seizure resistance and method for manufacturing the same |
JP2013234387A (en) * | 2012-05-08 | 2013-11-21 | Boehler Edelstahl Gmbh & Co Kg | Material with high wear resistance |
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