JPH02125840A - Tool steel for hot working - Google Patents
Tool steel for hot workingInfo
- Publication number
- JPH02125840A JPH02125840A JP27716888A JP27716888A JPH02125840A JP H02125840 A JPH02125840 A JP H02125840A JP 27716888 A JP27716888 A JP 27716888A JP 27716888 A JP27716888 A JP 27716888A JP H02125840 A JPH02125840 A JP H02125840A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- toughness
- medium
- hot working
- less
- 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.)
- Pending
Links
- 229910001315 Tool steel Inorganic materials 0.000 title claims abstract description 8
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 38
- 239000010959 steel Substances 0.000 claims abstract description 38
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 12
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 11
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 7
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 6
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 6
- 229910052758 niobium Inorganic materials 0.000 claims abstract 4
- 229910052804 chromium Inorganic materials 0.000 abstract description 3
- 229910052720 vanadium Inorganic materials 0.000 abstract description 3
- 238000007788 roughening Methods 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 21
- 238000010791 quenching Methods 0.000 description 13
- 230000000171 quenching effect Effects 0.000 description 13
- 238000005242 forging Methods 0.000 description 12
- 230000007423 decrease Effects 0.000 description 9
- 150000001247 metal acetylides Chemical class 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 239000013078 crystal Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 230000009466 transformation Effects 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000005496 tempering Methods 0.000 description 4
- 238000005336 cracking Methods 0.000 description 3
- 230000001681 protective effect Effects 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、熱間鍛造加工、特に型面からの強水冷のもと
に行なわれる熱間高速精密鍛造加工に用いられる工具鋼
に関するものである。[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a tool steel used in hot forging, particularly hot high-speed precision forging performed under strong water cooling from the mold surface. be.
鍛造加工の分野では、鍛造成形後の仕上加工工数の削減
を目的として型面からの強水冷のもとに行なわれる高速
精密鍛造が発展してきたが、この用途の金型は、鍛造し
た製品の寸法精度が厳しく要求されるため、従来高湿強
度の特に高い熱間工具鋼５ＫＤ７や５ＫＤ８が使用され
ている。In the field of forging, high-speed precision forging, which is performed under strong water cooling from the mold surface, has been developed with the aim of reducing the number of finishing steps after forging. Since dimensional accuracy is strictly required, hot work tool steels 5KD7 and 5KD8, which have particularly high high humidity strength, have been used.
しかしながら、最近実際に使用された熱間高速精密鍛造
加工工具の損耗形態のＩＪ１察を行なってみると、５Ｋ
Ｄ７系の材料を材質とする加工工具は、肌荒れ、割れに
より寿命に至っており、肌荒れは初期硬度、高温強度の
不足によるヒートクラックの発生と、加工面直下が昇温
し軟化した部分が塑性流動することによる自流れの二つ
が主要因であり、割れは、焼入性、靭性の不足によりク
ラックが進展し易いことに起因している。However, when we conducted an IJ1 analysis of the wear and tear of hot high-speed precision forging tools that were actually used recently, we found that 5K
Machining tools made of D7-based materials reach the end of their lifespans due to surface roughness and cracking. Surface roughness is caused by heat cracks due to insufficient initial hardness and high-temperature strength, and plastic flow in the area directly below the machined surface that has become heated and softened. The two main factors are self-flow caused by the cracking, and cracks are caused by the fact that cracks tend to propagate due to lack of hardenability and toughness.
一方、５ＫＤ８は高温強度は大きいが、巨大炭化物が熱
間加工方向に沿って紐状に分布した組織を持つため、ク
ラックの発生、進展の感受性が高く、使用時の割れ事故
が頻発している。本発明者らは、５ＫＤ８の初期硬度や
高温強度を維持しつつ、靭性面を大幅に改良した温間お
よび熱間加工工具（特開昭６２−１１２７６１号）を先
に提案しているが、熱間高速精密鍛造の加工工具に適用
するについては、初期硬度が高すぎ靭性が不足するので
、これより初期硬度のやや低いレベルの工具材料の開発
が必要である。On the other hand, 5KD8 has high high-temperature strength, but because it has a structure in which giant carbides are distributed in a string-like manner along the hot working direction, it is highly susceptible to crack initiation and propagation, resulting in frequent cracking accidents during use. . The present inventors had previously proposed a warm and hot working tool (Japanese Patent Application Laid-Open No. 112761/1982) that maintained the initial hardness and high temperature strength of 5KD8 while significantly improving toughness. When applied to processing tools for hot high-speed precision forging, the initial hardness is too high and toughness is insufficient, so it is necessary to develop a tool material with a slightly lower initial hardness.
前記特開昭６２−１１２７６１号と似たような思想の下
に開発された鋼が特公昭５７−５１４５６号に開示され
ているが、成分的に初期硬度、高温強度の面が不足して
おり、また工具使用時の昇温による軟化及び耐焼付性に
問題点があった。A steel developed based on a concept similar to that of JP-A-62-112761 is disclosed in JP-A-57-51456, but it lacks initial hardness and high-temperature strength due to its composition. Also, there were problems with softening and seizure resistance due to temperature rise during tool use.
本発明者等は以上の問題点を改善した鋼を特願昭６１−
３１０６１５号にて提案したが、高温域における靭性が
高速精密鍛造の用途には、若干不足していた。The inventors of the present invention have developed a steel that has improved the above-mentioned problems in a patent application filed in 1983-
Although it was proposed in No. 310615, the toughness in the high-temperature range was somewhat insufficient for high-speed precision forging applications.
本発明の課題は、以上説明した従来鋼の問題点を改善し
、熱間高速精密鍛造加工用の工具として最適な熱間加工
用工具鋼を提供することにある。An object of the present invention is to improve the problems of conventional steels explained above and to provide a tool steel for hot working that is optimal as a tool for hot high-speed precision forging.
本発明鋼の化学組成はかかる問題点を解決すべく、低〜
中Ｃ−中Ｃｒ量の５ＫＤ７をベースとし。In order to solve this problem, the chemical composition of the steel of the present invention has a low to low
Based on 5KD7 with medium C-medium Cr content.
Ｃ量を上げることにより初期硬さを高め、Ｃｒ量を下げ
ること、およびＭｏ，Ｗを適量添加することによって高
温強度を著しく改善した中Ｃ−低〜中Ｃｒ−中（Ｗ、Ｍ
ｏ）−中Ｖ量を基本成分としている。併せて、Ｎｂ添加
さらにはＮ添加による結晶粒の微細化に特徴を有する。Medium C-low to medium Cr-medium (W, M
o)-Medium V amount is used as the basic component. In addition, it is characterized by refinement of crystal grains due to Nb addition and further N addition.
すなわち、特に型材の昇温温度が高い場合、軟化抵抗を
高めるために焼入温度を高くすることが有効であるが、
結晶粒粗大化により靭性が低下する。これを抑えるため
にはＮｂの添加が特に効果的である。この効果は、Ｎｉ
を含有せしめることにより更に顕著となる。In other words, especially when the heating temperature of the mold material is high, it is effective to increase the quenching temperature to increase the softening resistance.
Toughness decreases due to coarsening of crystal grains. Addition of Nb is particularly effective in suppressing this. This effect is due to Ni
It becomes even more noticeable by containing.
すなわち、Ｎｉ添加による基地の靭性改善とあいまって
、特に優れた靭性付与を可能とするのである。That is, in combination with the improvement in the toughness of the base by adding Ni, it is possible to impart particularly excellent toughness.
また熱間での耐摩耗性付与のためにＣｏさらにはＹ、Ｃ
ｅ、Ｍｇの添加により、使用時の昇温により工具表面に
緻密で固着性の大きい酸化被膜を形成させ、これによる
潤滑作用、断熱効果により母材の強度とあいまって、熱
間での耐摩耗性、耐肌荒れ性の改善を可能にした。In addition, Co, Y, and C are used to provide hot wear resistance.
e. By adding Mg, a dense and highly adhesive oxide film is formed on the tool surface as the temperature rises during use, and the resulting lubrication and insulation effects combine with the strength of the base material to improve wear resistance in hot conditions. This made it possible to improve skin properties and rough skin resistance.
すなわち本発明は、重量％でＣ０．３５〜０．４７％。That is, in the present invention, C is 0.35 to 0.47% by weight.
Ｓｉ １．００％以下、Ｍｎ１．００％以下、Ｎｉ ０
．２０〜０．９５％、Ｃｒ ２．２０−４．００％、Ｗ
およびＭｏを１種または２種で１／２Ｗ＋Ｍｏ ２．２
０−４．００％、Ｖ ０．５０〜１．００％、Ｎｂ０．
０１〜０．２０％および場合によってはＣｏ ０．５０
−４．００％。Si 1.00% or less, Mn 1.00% or less, Ni 0
．． 20-0.95%, Cr 2.20-4.00%, W
and 1/2W+Mo 2.2 with one or two types of Mo
0-4.00%, V 0.50-1.00%, Nb0.
01-0.20% and possibly Co 0.50
-4.00%.
Ｎ ０．０３〜０．１０％、Ｍｇ、Ｙ、Ｃｅの１種また
は２種以上で０．３０％以下を適宜含有し、残部Ｆｅ及
び不可避的不純物からなることを特徴とする熱間加工用
工具鋼である。For hot processing, containing 0.03 to 0.10% N, 0.30% or less of one or more of Mg, Y, and Ce, and the balance consisting of Fe and inevitable impurities. It is tool steel.
次に本発明鋼の成分範囲の限定理由について述べる。 Next, the reason for limiting the composition range of the steel of the present invention will be described.
Ｃは、本発明鋼の高い焼入焼もどし硬さおよび高温強度
を維持し、またＷ、Ｍｏ、Ｖ、Ｃｒなどの炭化物形成元
素と結合して、炭化物を形成し、結晶粒の微細化、耐摩
耗性、焼もどし軟化抵抗、高温強度を与えるために添加
するものである。C maintains the high quenching and tempering hardness and high-temperature strength of the steel of the present invention, and also combines with carbide-forming elements such as W, Mo, V, and Cr to form carbides and refine grains. It is added to provide wear resistance, temper softening resistance, and high temperature strength.
多すぎると、本分野の加工工具に適用する初期硬さのレ
ベルを越えてしまうため、０．４７％以下とし、低すぎ
ると上記添加の効果が得られないので０．３５％以上と
する。If the amount is too high, the initial hardness level applied to processing tools in this field will be exceeded, so the content should be 0.47% or less. If the content is too low, the effect of the above addition cannot be obtained, so the content should be 0.35% or more.
Ｓ」添加は、使用中の昇温による酸化被膜の生成量を減
少させ、また熱伝導性を小さくするので、用途、昇温度
、使用雰囲気等を考慮しつつ、１．００％以下添加する
。The addition of ``S'' reduces the amount of oxide film formed due to temperature rise during use and also reduces thermal conductivity, so it should be added in an amount of 1.00% or less, taking into consideration the application, temperature rise, use atmosphere, etc.
Ｍｎは、酸化被膜の生成量を増加させる効果があり、焼
入性を向上させる。多すぎると、Ａ１変態点を過度に低
下させ、焼なまし硬さを過度に高くし、被切削性を低下
させるので１．０部以下とする。Mn has the effect of increasing the amount of oxide film produced and improves hardenability. If it is too large, the A1 transformation point will be excessively lowered, the annealing hardness will be excessively increased, and the machinability will be decreased, so the content should be 1.0 part or less.
Ｎ１は、焼入冷却速度の低下に伴うベイナイト組織の形
態や量を制御することにより、本発明鋼に優れた焼入性
、靭性を付与するものであるが、本分野で使用される加
工工具はさほど大きい焼入冷却速度で焼入されることは
なく、またＮｉ量が多すぎると、高温加熱時に炭化物の
凝集が早い時期に起こり、高温強度が大きくならないこ
と、及びＡ３変態点を下げ、昇温による軟化が起こり易
くなり、塑性流動に対する抵抗性が小さくなること、耐
焼付性が低下すること、焼なまし硬さが高くなり機械加
工性を低下することから、０．９５％を上限とし、低す
ぎると上記添加の効果が得られないので０．２０％以上
とする。N1 imparts excellent hardenability and toughness to the steel of the present invention by controlling the form and amount of bainite structure as the quenching cooling rate decreases, but the processing tools used in this field is not quenched at a very high quenching cooling rate, and if the amount of Ni is too large, carbide agglomeration will occur early during high temperature heating, high temperature strength will not increase, and the A3 transformation point will be lowered. The upper limit is 0.95% because softening due to temperature rise tends to occur, resistance to plastic flow decreases, seizure resistance decreases, and annealing hardness increases and machinability decreases. If it is too low, the effect of the above addition cannot be obtained, so the content should be 0.20% or more.
Ｃｒは、適切な添加量の設定により焼もどし軟化抵抗お
よび高温強度の向上、また適度の酸化被膜特性の付与、
Ａ□変態点の向上、焼入性の向上および窒化特性の向上
の効果を有するものであるが、高すぎると炭化物の析出
凝集を促進し、高温強度の低下をまねくため、上限を４
．００％とし、低すぎると上記添加の効果が得られない
ので下限を２．２０％とする。Cr improves tempering softening resistance and high-temperature strength by setting an appropriate amount of addition, as well as imparting appropriate oxide film properties.
A□It has the effect of improving the transformation point, improving hardenability, and improving nitriding properties, but if it is too high, it will promote precipitation and aggregation of carbides, leading to a decrease in high-temperature strength, so the upper limit is set to 4.
．． If it is too low, the effect of the above addition cannot be obtained, so the lower limit is set to 2.20%.
Ｗは、焼入時基地に固溶し、焼入温度を高める効果を持
ち、焼もどし時には微細な炭化物を分散析出して高温耐
力を高める効果を持っている。これらの効果が、本発明
鋼に優れた初期硬さ、高温強度を付与している。W forms a solid solution in the matrix during quenching and has the effect of increasing the quenching temperature, and during tempering, disperses and precipitates fine carbides and has the effect of increasing high-temperature yield strength. These effects give the steel of the present invention excellent initial hardness and high temperature strength.
Ｍｏは、Ｗと同様特殊炭化物を形成し、初期硬さ高温強
度を付与するものである。Like W, Mo forms a special carbide and imparts initial hardness and high temperature strength.
Ｗ、Ｍｏは」二記の効果を得るために添加されるもので
あるが、多すぎると焼入温度、初期硬さを過度に高くし
、また靭性を低下させるため、ＷおよびＭｏを１種また
は２種で１／２Ｗ＋Ｍｏで４．００％以下とし、低すぎ
ると本発明鋼の特徴である優れた初期硬さ、高温強度が
得られなくなるため２．２０％以上とする。W and Mo are added in order to obtain the effects mentioned in 2. However, if they are too large, the quenching temperature and initial hardness will become excessively high, and the toughness will decrease, so W and Mo are added in one kind. Alternatively, for the two types, 1/2W+Mo is set at 4.00% or less, and if it is too low, the excellent initial hardness and high temperature strength that are the characteristics of the steel of the present invention cannot be obtained, so it is set at 2.20% or more.
■は、Ｗ、Ｍｏと同様、焼入加熱時基地に固溶して焼も
どし時、微細な凝集しにくい炭化物を析出し、大きな高
温耐力を与える効果を持つ。また、結晶粒を微細化して
靭性を向上させるとともに、Ａ□変態点を上げ、優れた
高温強度とあいまって、耐ヒートクラツク性を向上させ
る効果をもたらす。Like W and Mo, (2) dissolves solidly in the matrix during quenching and heating, precipitates fine carbides that are difficult to agglomerate during tempering, and has the effect of imparting a large high-temperature yield strength. In addition, it refines the crystal grains to improve toughness and raises the A□ transformation point, which, together with excellent high-temperature strength, has the effect of improving heat crack resistance.
多すぎると、固溶しにくい巨大炭化物を形成し、これが
熱間加工方向に沿って紐状に分布し、この方向の靭性を
著しく損なうので、１．５０％以下とし、低すぎると上
記添加の効果が得られないので０．５０％以上とする。If the amount is too high, giant carbides that are difficult to dissolve in solid form will be formed, which will be distributed like strings along the hot working direction, significantly impairing the toughness in this direction. Since no effect can be obtained, the content should be 0.50% or more.
Ｎｂは、軟化抵抗、高温強度を高めるために、高目の温
度で焼入する時の結晶粒粗大化を抑制する効果を有し、
本発明鋼の特徴である優れた高温強度と靭性の兼備をも
たらすための重要な元素で ｑ−
ある。Nb has the effect of suppressing grain coarsening during quenching at a high temperature in order to increase softening resistance and high-temperature strength,
q- is an important element for providing the excellent high-temperature strength and toughness that are the characteristics of the steel of the present invention.
多すぎると、固溶しにくい炭化物を形成し、靭性を低下
させるので、０．２０％以下とし、低すぎると上記添加
の効果が得られないので０．０１％以上とする。If it is too large, it forms carbides that are difficult to form a solid solution and reduces toughness, so the content should be 0.20% or less, and if it is too low, the effect of the above addition cannot be obtained, so the content should be 0.01% or more.
Ｃｏ添加により使用中の昇温時、極めて緻密な密着性の
良い保護酸化被膜を形成し、これにより被加工材との金
属接触が減じ、金属表面の温度上昇を防ぐ断熱効果、保
護作用があり、耐ヒートクラツク性の向上、クラック起
点発生の抑制に効果を持つ。When the temperature rises during use, the addition of Co forms an extremely dense protective oxide film with good adhesion, which reduces metal contact with the workpiece and has an insulating and protective effect that prevents the metal surface from rising in temperature. , is effective in improving heat crack resistance and suppressing the occurrence of crack initiation points.
Ｃｏは、本発明鋼に上記の効果をもたらすため、０．５
％以上添加するが、多すぎると靭性を低下させるので４
．００％以下とする。Since Co brings the above-mentioned effects to the steel of the present invention, the content of Co is 0.5
% or more, but too much will reduce toughness, so
．． 00% or less.
Ｍｇ、Ｙ、ＣｅはＣｏと同様に昇温時の酸化被膜の固着
性を高め、耐ヒートクラツク性を改善する効果を有する
。しかし、多量の添加は必要なく、むしろ介在物の増加
、造塊時のマクロ偏析の助長をまねくので、Ｍｇ、Ｙ、
Ｃｅの１種または２種以上で０．３０％以下とする。Like Co, Mg, Y, and Ce have the effect of increasing the adhesion of the oxide film during temperature rise and improving heat crack resistance. However, large amounts of Mg, Y,
The content of one or more types of Ce is 0.30% or less.
Ｎは、結晶粒の微細化をもたらし、靭性向上の効果を持
つもので、この目的のために添加を行なう。多量の添加
は巨大炭化物の晶出を招き、また製造上の理由から０．
０３〜０．１０％以下とする。N brings about refinement of crystal grains and has the effect of improving toughness, and is added for this purpose. Adding a large amount will lead to crystallization of giant carbides, and for manufacturing reasons, 0.
0.03 to 0.10% or less.
以下、本発明を実施例に基づき詳細に説明する。 Hereinafter, the present invention will be explained in detail based on examples.
第１表に本発明鋼、比較鋼および従来鋼の化学組成を示
す。第２表は本発明鋼および従来鋼の標準的な熱処理条
件における高温強度とＴ方向の靭性を示す。Table 1 shows the chemical compositions of the invention steel, comparative steel, and conventional steel. Table 2 shows the high temperature strength and T-direction toughness of the steel of the present invention and the conventional steel under standard heat treatment conditions.
高温強度は１２０ｍｍφ鋼材からＬ方向（鍛伸平行方向
）に採取した試料による７００℃における引張強さで示
し、Ｔ方向の靭性は１２０ｎ＋＋φ鋼材からＴ方向（鍛
伸直角方向）に採取した試料による１０ ａｍ Ｒシャ
ルピー衝撃試験の結果で示す。High-temperature strength is shown as the tensile strength at 700°C using a sample taken from a 120mmφ steel material in the L direction (parallel to forging and stretching), and toughness in the T direction is based on a sample taken from a 120n++φ steel material in the T direction (perpendicular to the forging and stretching direction). The results are shown in the results of a 10 am R Charpy impact test.
第 表 従来鋼Ｍ（ＳＫＤ７）は、硬度および高温強度が低い。No. table Conventional steel M (SKD7) has low hardness and high temperature strength.
硬度が低いのは、Ｃ量が低すぎるためであり、高温強度
が低いのは、高温強度に寄与するｖ量が低すぎるためで
ある。The reason why the hardness is low is because the amount of C is too low, and the reason why the high temperature strength is low is because the amount of v that contributes to the high temperature strength is too low.
従来鋼Ｎ（ＳＫＤ８）は、Ｔ方向の靭性が低い。Conventional steel N (SKD8) has low toughness in the T direction.
これは、Ｖ量が高すぎ、ＶＣ炭化物の鍛伸方向への紐状
分布傾向が強いためである。This is because the amount of V is too high and the VC carbide tends to have a string-like distribution in the forging direction.
第３表に本発明鋼Ｂおよび比較鋼Ｋを各種温度で焼入し
た場合のオーステナイト結晶粒度、高温強度（７００℃
引張強さ）および靭性
第３表から本発明鋼Ｂおよび比較鋼に共に焼入温度が高
いほど高温強度を増すことが明らかであるが、比較鋼に
は焼入温度の上昇とともに靭性が低下する。これは焼入
温度の上昇とともに焼入組織のオーステナイト結晶粒が
粗大化し、組織が粗くなるためである。これに対し、Ｎ
ｂを添加した本発明鋼Ｂは焼入温度が上昇しても靭性が
低下しない。これはＮｂがオーステナイト結晶粒の粗大
成長を防ぐためであり、特に高温強度、軟化抵抗が重要
な用途に対するＮｂの重要性が認識される。Table 3 shows the austenite grain size and high temperature strength (700°C
Tensile strength) and toughness From Table 3, it is clear that the higher the quenching temperature, the higher the high-temperature strength of both the invention steel B and the comparative steel, but the comparative steel has a lower toughness as the quenching temperature increases. . This is because as the quenching temperature increases, the austenite crystal grains in the quenched structure become coarser and the structure becomes coarser. On the other hand, N
Steel B of the present invention to which b is added does not exhibit a decrease in toughness even when the quenching temperature increases. This is because Nb prevents coarse growth of austenite crystal grains, and the importance of Nb is recognized particularly for applications where high temperature strength and softening resistance are important.
第
表
第４表に本発明鋼および比較鋼の高温焼付試験における
焼付臨界荷重（比）を示す。試料は円柱状試料で、熱処
理、研磨仕上後あらかじめ５５０℃における空気酸化処
理を行なったのち、７００℃に加熱した鋼材（相手材）
に高速で回転しながら、端面を押しつけた場合の焼付が
起らない最大荷重（臨界荷重）を求め、従来鋼Ｍ（ＳＫ
Ｄ７）の焼付臨界荷重を１００として指数で示したもの
である。Table 4 shows the baking critical load (ratio) in the high temperature baking test of the invention steel and comparative steel. The sample is a cylindrical sample, and after heat treatment and polishing, it was previously subjected to air oxidation treatment at 550℃, and then heated to 700℃.
The maximum load (critical load) at which seizure does not occur when the end face is pressed while rotating at high speed is determined, and conventional steel M (SK
It is expressed as an index with the seizure critical load of D7) set as 100.
本発明鋼は従来鋼り、Ｍより明らかに焼付臨界荷重が高
いこと、またＣｏ、Ｍｇ、Ｙ、Ｃｅを添加したＤ −Ｈ
ｌＪが優れていることがわかる。The steel of the present invention has a clearly higher seizure critical load than conventional steel, M, and D-H with added Co, Mg, Y, and Ce.
It can be seen that lJ is excellent.
従来鋼りはＮｉが１．１％と本発明鋼より多いが、Ｎｉ
を０．９５％を越えて過剰に添加するとＡ３変態点の低
下をもたらし、試験片の温度上昇とともに、オーステナ
イト変態しやすく、熱伝導率の低下と硬度の低下が、相
手材との焼付を促進するため、本発明鋼より耐焼付性が
劣るのである。また、本発明鋼のうちＣｏ、Ｍｇ、Ｙ、
Ｃｅが添加されたものは、上記酸化処理により本発明鋼
の試料表面に形成された緻密で剥離しにくい酸化被膜の
保護作用ならびに潤滑作用により、耐焼付性が一段と優
れている。Conventional steel contains 1.1% Ni, which is higher than the steel of the present invention, but Ni
Excessive addition of more than 0.95% lowers the A3 transformation point, and as the temperature of the test piece increases, it tends to transform into austenite, and the decrease in thermal conductivity and hardness promotes seizure with the mating material. Therefore, the seizure resistance is inferior to the steel of the present invention. In addition, among the steels of the present invention, Co, Mg, Y,
Those to which Ce is added have even better seizure resistance due to the protective and lubricating effects of the dense and hard-to-peel oxide film formed on the surface of the steel sample of the present invention by the above-mentioned oxidation treatment.
Claims (1)
％以下、Ｍｎ１．００％以下、Ｎｉ０．２０〜０．９５
％、Ｃｒ２．２０〜４．００％、ＷおよびＭｏを１種ま
たは２種で１／２Ｗ＋Ｍｏ２．２０〜４．００％、Ｖ０
．５０〜１．００％、Ｎｂ０．０１〜０．２０％、残部
Ｆｅ及び不可避的不純物からなることを特徴とする熱間
加工用工具鋼。 ２ 重量％で、Ｃ０．３５〜０．４７％、Ｓｉ１．００
％以下、Ｍｎ１．００％以下、Ｎｉ０．２０〜０．９５
％、Ｃｒ２．２０〜４．００％、ＷおよびＭｏを１種ま
たは２種で１／２Ｗ＋Ｍｏ２．２０〜４．００％、Ｖ０
．５０〜１．００％、Ｎｂ０．０１〜０．２０％、並び
にＣｏ０．５０〜４．００％、およびＭｇ、Ｙ、Ｃｅの
１種または２種以上を０．３０％以下のいずれか一方、
または双方、残部Ｆｅ及び不可避的不純物からなること
を特徴とする熱間加工用工具鋼。 ３ 重量％で、Ｃ０．３５〜０．４７％、Ｓｉ１．００
％以下、Ｍｎ１．００％以下、Ｎｉ０．２０〜０．９５
％、Ｃｒ２．２０〜４．００％、ＷおよびＭｏを１種ま
たは２種で１／２Ｗ＋Ｍｏ２．２０〜４．００％、Ｖ０
．５０〜１．００％、Ｎｂ０．０１〜０．２０％、Ｎ０
．０３〜０．１０％、残部Ｆｅ及び不可避的不純物から
なることを特徴とする熱間加工用工具鋼。 ４ 重量％で、Ｃ０．３５〜０．４７％、Ｓｉ１．００
％以下、Ｍｎ１．００％以下、Ｎｉ０．２０〜０．９５
％、Ｃｒ２．２０〜４．００％、ＷおよびＭｏを１種ま
たは２種で１／２Ｗ＋Ｍｏ２．２０〜４．００％、Ｖ０
．５０〜１．００％、Ｎｂ０．０１〜０．２０％、Ｎ０
．０３〜０．１０％並びにＣｏ０．５０〜４．００％、
およびＭｇ、Ｙ、Ｃｅの１種または２種以上を０．３０
％以下のいずれか一方、または双方、残部Ｆｅ及び不可
避的不純物からなることを特徴とする熱間加工用工具鋼
。[Claims] 1% by weight, C0.35-0.47%, Si1.00
% or less, Mn 1.00% or less, Ni 0.20 to 0.95
%, Cr2.20-4.00%, 1/2 W + Mo2.20-4.00% with one or two types of W and Mo, V0
．． A tool steel for hot working characterized by comprising 50-1.00% Nb, 0.01-0.20% Nb, and the balance Fe and unavoidable impurities. 2% by weight, C0.35-0.47%, Si1.00
% or less, Mn 1.00% or less, Ni 0.20 to 0.95
%, Cr2.20-4.00%, 1/2 W + Mo2.20-4.00% with one or two types of W and Mo, V0
．． 50 to 1.00%, Nb 0.01 to 0.20%, and Co 0.50 to 4.00%, and one or more of Mg, Y, and Ce at 0.30% or less,
Or a tool steel for hot working, characterized in that both of them are composed of Fe and unavoidable impurities. 3% by weight, C0.35-0.47%, Si1.00
% or less, Mn 1.00% or less, Ni 0.20 to 0.95
%, Cr2.20-4.00%, 1/2 W + Mo2.20-4.00% with one or two types of W and Mo, V0
．． 50-1.00%, Nb0.01-0.20%, N0
．． A tool steel for hot working, characterized in that the steel comprises 0.03 to 0.10%, the balance being Fe and unavoidable impurities. 4% by weight, C0.35-0.47%, Si1.00
% or less, Mn 1.00% or less, Ni 0.20 to 0.95
%, Cr2.20-4.00%, 1/2 W + Mo2.20-4.00% with one or two types of W and Mo, V0
．． 50-1.00%, Nb0.01-0.20%, N0
．． 03-0.10% and Co0.50-4.00%,
and one or more of Mg, Y, and Ce at 0.30%
% or less, the balance being Fe and unavoidable impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27716888A JPH02125840A (en) | 1988-11-01 | 1988-11-01 | Tool steel for hot working |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27716888A JPH02125840A (en) | 1988-11-01 | 1988-11-01 | Tool steel for hot working |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02125840A true JPH02125840A (en) | 1990-05-14 |
Family
ID=17579752
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP27716888A Pending JPH02125840A (en) | 1988-11-01 | 1988-11-01 | Tool steel for hot working |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02125840A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7494618B2 (en) * | 2004-01-26 | 2009-02-24 | Daido Tokushuko Kabushiki Kaisha | Alloy tool steel |
| JP2014508218A (en) * | 2011-01-13 | 2014-04-03 | ロヴァルマ エス．アー． | Tool steel with high thermal diffusivity and high wear resistance |
| JP2014512456A (en) * | 2011-03-04 | 2014-05-22 | ウッデホルムス アーベー | Hot working tool steel and method for producing hot working tool steel |
| JP2017512913A (en) * | 2014-03-18 | 2017-05-25 | イノマク ２１，ソシエダ リミターダ | Super high conductivity low cost steel |
| WO2018182480A1 (en) * | 2017-03-29 | 2018-10-04 | Uddeholms Ab | Hot work tool steel |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58207359A (en) * | 1982-05-29 | 1983-12-02 | Nachi Fujikoshi Corp | Hot working tool steel |
| JPS6059053A (en) * | 1983-09-09 | 1985-04-05 | Daido Steel Co Ltd | Hot working tool steel |
| JPS62112761A (en) * | 1985-11-12 | 1987-05-23 | Hitachi Metals Ltd | Tool steel for warm and hot working |
| JPS63162840A (en) * | 1986-12-25 | 1988-07-06 | Hitachi Metals Ltd | Tool steel for hot working |
-
1988
- 1988-11-01 JP JP27716888A patent/JPH02125840A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58207359A (en) * | 1982-05-29 | 1983-12-02 | Nachi Fujikoshi Corp | Hot working tool steel |
| JPS6059053A (en) * | 1983-09-09 | 1985-04-05 | Daido Steel Co Ltd | Hot working tool steel |
| JPS62112761A (en) * | 1985-11-12 | 1987-05-23 | Hitachi Metals Ltd | Tool steel for warm and hot working |
| JPS63162840A (en) * | 1986-12-25 | 1988-07-06 | Hitachi Metals Ltd | Tool steel for hot working |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7494618B2 (en) * | 2004-01-26 | 2009-02-24 | Daido Tokushuko Kabushiki Kaisha | Alloy tool steel |
| JP2014508218A (en) * | 2011-01-13 | 2014-04-03 | ロヴァルマ エス．アー． | Tool steel with high thermal diffusivity and high wear resistance |
| JP2014512456A (en) * | 2011-03-04 | 2014-05-22 | ウッデホルムス アーベー | Hot working tool steel and method for producing hot working tool steel |
| JP2017512913A (en) * | 2014-03-18 | 2017-05-25 | イノマク ２１，ソシエダ リミターダ | Super high conductivity low cost steel |
| JP2020111829A (en) * | 2014-03-18 | 2020-07-27 | イノマク ２１，ソシエダ リミターダ | Extremely high conductivity low cost steel |
| WO2018182480A1 (en) * | 2017-03-29 | 2018-10-04 | Uddeholms Ab | Hot work tool steel |
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