JPS646247B2 - - Google Patents
Info
- Publication number
- JPS646247B2 JPS646247B2 JP16740280A JP16740280A JPS646247B2 JP S646247 B2 JPS646247 B2 JP S646247B2 JP 16740280 A JP16740280 A JP 16740280A JP 16740280 A JP16740280 A JP 16740280A JP S646247 B2 JPS646247 B2 JP S646247B2
- Authority
- JP
- Japan
- Prior art keywords
- carbides
- annealing
- present
- precipitation
- temperature
- 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.)
- Expired
Links
- 238000000034 method Methods 0.000 claims description 15
- 238000000137 annealing Methods 0.000 claims description 14
- 229910001566 austenite Inorganic materials 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 10
- 238000001816 cooling Methods 0.000 claims description 7
- 229910000734 martensite Inorganic materials 0.000 claims description 7
- 229910001315 Tool steel Inorganic materials 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000005469 granulation Methods 0.000 claims description 3
- 230000003179 granulation Effects 0.000 claims description 3
- 238000000354 decomposition reaction Methods 0.000 claims description 2
- 230000009466 transformation Effects 0.000 claims description 2
- 150000001247 metal acetylides Chemical class 0.000 description 13
- 238000001556 precipitation Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 5
- 230000000717 retained effect Effects 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000822 Cold-work tool steel Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- -1 but in this case Chemical class 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/02—Hardening by precipitation
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Articles (AREA)
- Forging (AREA)
Description
本発明は工具鋼の耐用寿命を大きく支配する焼
なまし組織を改善するものであり、詳しくは、連
鎖状炭化物の析出を防止し、均一微細な炭化物組
織の生成を目的としたものである。
工具鋼の焼なまし組織を改善する方法として
は、焼なまし時の熱処理曲線の改善に関するもの
が多く提案されている。また、このほかに熱間加
工后焼鈍前に焼ならしを施す方法がおこなわれて
いた。この方法は、オーステナイト域に加熱する
ことによつて炭化物を基地に固溶させ、これを急
冷することによつて結晶粒界への炭化物の優先析
出を防止するものである。しかしながら上記方法
によつては炭化物の粒界析出を完全に抑制するこ
とは困難であつた。
本発明は、炭化物の粒界析出を効果的に抑えて
完全な球状化焼なまし組織を得る新規な方法であ
り、その要旨は、熱間加工または／およびオース
テナイト化温度以上に加熱の後、マルテンサイト
変態の生ずる温度以下に冷却し、その後残留オー
ステナイトの分解する温度以上に加熱し、または
常温以下に冷却する等の残留オーステナイトの分
解処理をおこない、次いで粒状化焼なましをする
ことを特徴とする均一に分散した焼なまし組織を
得る工具鋼の製造方法である。
従来の工具鋼の製造工程においては、前述した
如く圧延または鍛造等の塑性加工後、またはオー
ステナイト化温度に加熱後、そのまま球状化焼な
まし処理がおこなわれていたが、本発明者は球状
化焼なまし後の粒界炭化物の生成は、球状化焼な
まし前の組織中にある残留オーステナイトに関係
することを知見した。即ち従来工程においては、
球状化焼なまし前にマルテンサイト組織と残留オ
ーステナイト組織が混在しているが、残留オース
テナイト組織は粒状化焼なまし処理時の加熱で、
炭化物の粒界優先析出を生ずる。しかも残留オー
ステナイト組織は周囲のマルテンサイト組織に比
較して基地中の炭素含有量が多いので粒界析出量
も多い。一方、マルテンサイト組織においても、
球状化焼なましの際の加熱によつて炭化物の析出
が生ずるが、この場合は粒界だけでなく、マルテ
ンサイト葉状模様のへき開面にも析出するので、
粒界析出量は極めて少ない。上記理由から、球状
化焼なまし前に残留オーステナイトの存在する従
来工程材においては、炭化物の粒界析出量が多
い。
本発明は、これらの知見にもとづき、球状化焼
なまし前に残留オーステナイトを分解しマルテン
サイトの単一相にし、球状化焼なまし後、炭化物
の均一に分散した組織を得るものであり、本発明
材は、粒界での局部的劣化が生じないため工具と
して使用した場合、長寿命が得られる。
尚、本発明方法において、熱間加工後またはオ
ーステナイト化温度に加熱後は、衝風冷却または
油冷等の急冷をおこなうことが望ましい。また、
本発明方法は、冷間工具鋼、熱間工具鋼およびそ
の他の炭化物を形成する工具鋼に対して適用出来
る。
次に本発明の効果を実施例にもとづいて説明す
る。
第１表に試験供試材の化学組成、熱処理条件お
よび衝撃試験結果を示す。本発明法は、従来法に
比べていづれの鋼種も著しく高い靭性を有するこ
とがわかる。
The present invention aims to improve the annealing structure, which largely controls the service life of tool steel, and specifically aims to prevent the precipitation of chain carbides and generate a uniform and fine carbide structure. As methods for improving the annealed structure of tool steel, many methods have been proposed that involve improving the heat treatment curve during annealing. In addition, a method of normalizing after hot working and before annealing has been used. In this method, carbides are dissolved in the matrix by heating to the austenite region, and by rapidly cooling the matrix, preferential precipitation of carbides at grain boundaries is prevented. However, it has been difficult to completely suppress grain boundary precipitation of carbides using the above method. The present invention is a novel method for obtaining a completely spheroidized annealed structure by effectively suppressing the grain boundary precipitation of carbides. It is characterized by performing decomposition treatment of residual austenite, such as cooling to a temperature below which martensitic transformation occurs, then heating above a temperature at which residual austenite decomposes, or cooling to below room temperature, followed by granulation annealing. This is a method for producing tool steel that obtains a uniformly dispersed annealed structure. In the conventional tool steel manufacturing process, as described above, after plastic working such as rolling or forging, or after heating to an austenitizing temperature, spheroidizing annealing treatment was performed as is. It was found that the formation of grain boundary carbides after annealing is related to retained austenite present in the structure before spheroidizing annealing. That is, in the conventional process,
Before spheroidizing annealing, martensite structure and retained austenite structure coexist, but retained austenite structure is formed by heating during granulation annealing treatment.
Precipitation of carbides occurs at grain boundaries. Furthermore, since the retained austenite structure has a higher carbon content in the matrix than the surrounding martensite structure, the amount of grain boundary precipitation is also greater. On the other hand, in martensitic tissue,
Heating during spheroidizing annealing causes precipitation of carbides, but in this case, carbides precipitate not only at the grain boundaries but also on the cleavage planes of the martensite leaf pattern.
The amount of grain boundary precipitation is extremely small. For the above reasons, in conventionally processed materials in which residual austenite exists before spheroidizing annealing, the amount of carbide precipitated at grain boundaries is large. Based on these findings, the present invention decomposes residual austenite into a single phase of martensite before spheroidizing annealing, and obtains a structure in which carbides are uniformly dispersed after spheroidizing annealing. The material of the present invention has a long life when used as a tool because no local deterioration occurs at grain boundaries. In the method of the present invention, after hot working or after heating to the austenitizing temperature, it is desirable to perform rapid cooling such as blast cooling or oil cooling. Also,
The method of the present invention can be applied to cold work tool steels, hot work tool steels, and other tool steels that form carbides. Next, the effects of the present invention will be explained based on examples. Table 1 shows the chemical composition, heat treatment conditions, and impact test results of the test specimens. It can be seen that the method of the present invention has significantly higher toughness than the conventional method for all steel types.
【表】
第１図は、供試材No.１の顕微鏡組織写真（倍率
400倍）である。1200℃に加熱後鍛造し、850℃×
5Hrで焼なましをした従来法の試料には炭化物の
粒界析出が認められるが、同様の条件で鍛造後
200℃迄冷却し600℃×3Hrの残留オーステナイト
の分解処理をおこなつて後、850℃×5Hrで焼な
ましをおこなつた本発明法の試料は、粒状炭化物
が均一に分布している。
第２表は、第１表の供試材を各種金型として使
用した場合の金型寿命を示す。本発明法により製
造した金型は、従来法のそれに比べて２〜３倍の
長寿命をもつことが判明した。[Table] Figure 1 is a microscopic structure photograph (magnification
400 times). Forged after heating to 1200℃, 850℃×
Grain boundary precipitation of carbides is observed in the conventional specimen annealed for 5 hours, but after forging under similar conditions,
In the sample obtained by the method of the present invention, which was cooled to 200°C, decomposed the retained austenite at 600°C for 3 hours, and then annealed at 850°C for 5 hours, granular carbides were uniformly distributed. Table 2 shows the mold life when the sample materials in Table 1 are used as various molds. It has been found that the molds manufactured by the method of the present invention have a lifespan two to three times longer than those manufactured by the conventional method.
【表】【table】
【表】
以上説明のとおり、本発明は工具鋼の焼鈍組織
を改善するうえに極めて効果的な方法であり、工
業的価値は著しく高い。[Table] As explained above, the present invention is an extremely effective method for improving the annealed structure of tool steel, and has extremely high industrial value.
第１図ａは従来製造法、ｂは本発明法を用いた
鋼材の顕微鏡組織写真である。
FIG. 1a is a micrograph of a steel material manufactured using the conventional manufacturing method, and FIG. 1b is a photograph of a steel material manufactured using the method of the present invention.
Claims (1)
度以上に加熱の後、マルテンサイト変態の生ずる
温度以下に冷却し、その後、残留オーステナイト
の分解処理をおこない、次いで粒状化焼なましを
することを特徴とする均一に分散した焼なまし組
織を得る工具鋼の製造方法。1. After hot working and/or heating above the austenitizing temperature, cooling below the temperature at which martensitic transformation occurs, followed by decomposition treatment of residual austenite, and then granulation annealing. A method for manufacturing tool steel that obtains a uniformly distributed annealed structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16740280A JPS5792128A (en) | 1980-11-29 | 1980-11-29 | Production of tool steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16740280A JPS5792128A (en) | 1980-11-29 | 1980-11-29 | Production of tool steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5792128A JPS5792128A (en) | 1982-06-08 |
| JPS646247B2 true JPS646247B2 (en) | 1989-02-02 |
Family
ID=15849031
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16740280A Granted JPS5792128A (en) | 1980-11-29 | 1980-11-29 | Production of tool steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5792128A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111560499B (en) * | 2020-05-18 | 2022-03-22 | 南京钢铁股份有限公司 | Annealing process of steel for high-strength-grade mining chain |
-
1980
- 1980-11-29 JP JP16740280A patent/JPS5792128A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5792128A (en) | 1982-06-08 |
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