JPH0135909B2 - - Google Patents
Info
- Publication number
- JPH0135909B2 JPH0135909B2 JP56010747A JP1074781A JPH0135909B2 JP H0135909 B2 JPH0135909 B2 JP H0135909B2 JP 56010747 A JP56010747 A JP 56010747A JP 1074781 A JP1074781 A JP 1074781A JP H0135909 B2 JPH0135909 B2 JP H0135909B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- strength
- toughness
- case
- present
- 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
- 239000012535 impurity Substances 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 description 29
- 239000010959 steel Substances 0.000 description 29
- 229910000760 Hardened steel Inorganic materials 0.000 description 9
- 239000000463 material Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 238000005275 alloying Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
Landscapes
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Description
本発明は、一般に要求される表面浸炭硬度を有
し、かつ内部が高強度、高靭性を兼ね備えた肌焼
鋼に関する。
従来より肌焼鋼は種々のものが市販されてお
り、その主体はCr−Mo系およびNi−Cr−Mo系
鋼で、一般に高強度を要求されることが多い。し
かし従来の成分の肌焼鋼では強度を高くすると、
靭性の低下が避けられず、従つてこの点が従来の
肌焼鋼の致命的な欠点とされていた。
材料が高負荷で使用される場合、材料の中心部
には高強度が要求されるが、上記のように中心部
を高強度にすると靭性、特に破壊靭性が低くなる
ため、使用中に表層浸炭部にクラツクが発生する
と、このクラツクの内部への進展を停止しえず、
この材料は瞬時にして破断し、周辺の機器を損傷
あるいは破壊することがあつた。
従来の肌焼鋼には上記のように欠点があつたた
め、鋼の内部が高強度でかつ高靭性を有する肌焼
鋼の開発が望まれていた。
本発明の目的は、従来の肌焼鋼にあつた上記欠
点を解消し、合金成分を適正に含有させて、焼入
性を大きくして、鋼材内部の強度および靭性を高
く保持し、また肉厚の大きい内部が高強度、高靭
性の鋼材にも適用可能な低破壊靭性特性を改善し
た新規な肌焼鋼を提供するにある。
本発明の肌焼鋼の化学成分は重量基準でC0.15
−0.25％、Si0.50％以下、Mn0.20−1.00％、
Ni3.00−3.74％、Cr1.00−2.00％、Mo0.20−0.50
％、V0.05−0.30％、残部Feおよび不可避不純物
である。
本発明の肌焼鋼は上記成分を有するが、このよ
うに合金元素の含有量を限定した理由は下記の通
りである。
Ｃ：焼入性および強度レベルを維持する上で必要
な元素であるが、0.15％未満では強度が低くな
り、高強度鋼には不充分である。また0.25％を
こえると靭性が劣化する。従つて0.15−0.25％
が適当である。
Si：脱酸剤として、また高強度を得るための元素
として必要であるが、多量の添加は靭性の低下
を招くので、その上限を0.50％とした。
Mn：脱酸剤として、また機械的性質を害する
FeSの生成阻止のために最低0.20％必要とし、
上限は経済性を考慮して1.00％とした。
Ni：焼入性および強度ならびに靭性を向上させ
るために必要な元素であるが、3.00％未満の添
加では強度および焼入性を確保する上で問題が
あり、一方3.74％をこえる添加は室温以上の温
度領域での靭性を低下させるので、その範囲を
3.00−3.74％とした。
Cr：Ni、Moと共に焼入性の向上に必要な元素で
あり、1.00％未満では焼入性が不足し、2.00％
をこえると衝撃特性が劣化する。従つてその範
囲を1.00−2.00％とする。
Mo：強度を保持しつつ靭性を確保するために重
要な元素であるが、0.20％未満の添加ではその
効果は不充分でまた多量の添加は靭性の低下を
招く恐れもあり、また経済性を考慮してその範
囲を0.20−0.50％とした。
Ｖ：結晶粒を微細化させて靭性を向上させ、また
強度を向上させるために必要な元素であるが、
0.05％未満の添加ではその効果は不充分であ
り、一方経済性を考慮してその範囲を0.05−
0.30％とした。
以上各合金元素の機能および成分範囲の限定理
由について説明したが、本発明肌焼鋼は、これら
各合金元素の上記成分範囲のつり合いのもとで、
その特性を発揮するものである。
つぎに本発明肌焼鋼の実施例について説明す
る。第１表に本発明肌焼鋼の１実施例と従来の肌
焼鋼の３例との化学成分をそれぞれ示す。
The present invention relates to a case hardening steel that has the generally required surface carburizing hardness and has both high strength and high toughness inside. A variety of case hardening steels have been commercially available, mainly Cr-Mo and Ni-Cr-Mo steels, which are generally required to have high strength. However, when increasing the strength of case hardening steel with conventional composition,
A decrease in toughness is unavoidable, and this point has been considered a fatal drawback of conventional case hardening steels. When a material is used under high loads, high strength is required at the center of the material, but as mentioned above, increasing the strength at the center reduces toughness, especially fracture toughness, so surface carburization is required during use. If a crack occurs in the part, it is impossible to stop the crack from progressing inside.
This material could break instantly, damaging or destroying surrounding equipment. Since conventional case-hardened steels have the drawbacks mentioned above, it has been desired to develop case-hardened steels that have high strength and toughness inside the steel. The purpose of the present invention is to eliminate the above-mentioned drawbacks of conventional case hardening steel, to increase hardenability by appropriately containing alloy components, and to maintain high internal strength and toughness of the steel material. The object of the present invention is to provide a new case-hardened steel with improved low fracture toughness properties that can be applied to steel materials with a large internal thickness and high strength and high toughness. The chemical composition of the case hardening steel of the present invention is C0.15 on a weight basis.
−0.25%, Si0.50% or less, Mn0.20−1.00%,
Ni3.00−3.74%, Cr1.00−2.00%, Mo0.20−0.50
%, V0.05-0.30%, the balance being Fe and unavoidable impurities. Although the case hardening steel of the present invention has the above-mentioned components, the reason why the content of alloying elements is limited in this way is as follows. C: An element necessary to maintain hardenability and strength level, but if it is less than 0.15%, the strength will be low and it is insufficient for high-strength steel. Moreover, when it exceeds 0.25%, toughness deteriorates. Therefore 0.15−0.25%
is appropriate. Si: Necessary as a deoxidizing agent and as an element to obtain high strength, but addition of a large amount leads to a decrease in toughness, so the upper limit was set at 0.50%. Mn: as a deoxidizing agent and also impairs mechanical properties
Requires a minimum of 0.20% to prevent FeS formation,
The upper limit was set at 1.00% in consideration of economic efficiency. Ni: An element necessary to improve hardenability, strength, and toughness, but if it is added less than 3.00%, there is a problem in ensuring strength and hardenability, while if it is added more than 3.74%, it will exceed room temperature. Since the toughness decreases in the temperature range of
It was set at 3.00−3.74%. Cr: Along with Ni and Mo, it is an element necessary to improve hardenability. If it is less than 1.00%, hardenability will be insufficient, and if it is less than 1.00%, hardenability will be insufficient.
If it exceeds this, the impact characteristics will deteriorate. Therefore, the range is set to 1.00-2.00%. Mo: An important element for ensuring toughness while maintaining strength, but if it is added less than 0.20%, its effect will be insufficient, and if it is added in a large amount, it may lead to a decrease in toughness, and it may not be economical. Taking this into consideration, the range was set at 0.20-0.50%. V: An element necessary to refine grains, improve toughness, and improve strength.
Addition of less than 0.05% will not give sufficient effect, but considering economic efficiency, the range should be reduced to 0.05-0.05%.
It was set at 0.30%. The functions of each alloying element and the reasons for limiting the range of the components have been explained above, but the case-hardened steel of the present invention can be made by balancing the above ranges of the components of each alloying element.
It exhibits its characteristics. Next, examples of the case hardening steel of the present invention will be described. Table 1 shows the chemical components of one example of the case hardening steel of the present invention and three examples of conventional case hardening steel.
【表】
これらの鋼は900−950℃にて浸炭後800℃迄徐
冷され、その後室温迄空冷された。さらに800−
840℃に加熱後油焼入され、次いでサブゼロ処理
後200℃以下に焼戻処理が施された。
第２表に、上記第１表の鋼を上記熱処理したも
のの機械的性質を、それぞれ示す。[Table] These steels were carburized at 900-950℃, slowly cooled to 800℃, and then air cooled to room temperature. Another 800−
After heating to 840°C, it was oil quenched, then subjected to sub-zero treatment and then tempered to below 200°C. Table 2 shows the mechanical properties of the steels in Table 1 subjected to the above heat treatment.
【表】
第２表にて明らかなように、本発明肌焼鋼は従
来鋼と同等の表面硬度を有し、かつ従来鋼に比し
て同等あるいはそれ以上の強度と著しく優れた破
壊靭性とを有していることがわかる。
第１図は第１表に示す化学成分を有する本発明
肌焼鋼を用いて、焼入熱処理において焼入れ温度
からの冷却速度を種々に変化させて強度の異なる
試材を調整し、その0.2％耐力と破壊靭性との関
係を上記従来鋼３例と比較して示したもので、こ
の図において本発明肌焼鋼はいずれの強度レベル
においてもその破壊靭性値は従来鋼より遥に優れ
ていることは明らかである。
以上述べたごとく、本発明肌焼鋼は従来のもの
と同等の表面硬度を有し、かつ従来のものに比し
て同等あるいはそれ以上の強度と著しく優れた破
壊靭性とを有している。このことは、本発明の肌
焼鋼は長時間安全な使用に耐えることを保証すこ
とであり、また本肌焼鋼は従来鋼を使用する場合
より寸法の縮少を可能にするものである。さらに
本肌焼鋼は従来鋼に比して合金成分も高くなく、
上記効果と相俟つて経済面からも優れた発明品で
ある。[Table] As is clear from Table 2, the case-hardened steel of the present invention has a surface hardness equivalent to that of conventional steel, and has the same or higher strength and significantly superior fracture toughness than conventional steel. It can be seen that it has Figure 1 shows specimens with different strengths prepared by varying the cooling rate from the quenching temperature during quenching heat treatment using the case-hardened steel of the present invention having the chemical composition shown in Table 1. The relationship between yield strength and fracture toughness is shown in comparison with the three examples of conventional steel mentioned above. This figure shows that the case hardened steel of the present invention has a fracture toughness value far superior to that of conventional steel at all strength levels. That is clear. As described above, the case hardened steel of the present invention has a surface hardness equivalent to that of the conventional steel, and also has strength equal to or greater than that of the conventional steel and significantly superior fracture toughness. This ensures that the case-hardened steel of the present invention can withstand long-term safe use, and also allows the case-hardened steel to be smaller in size than when using conventional steel. . Furthermore, case-hardened steel does not have a high alloy content compared to conventional steel,
In combination with the above-mentioned effects, this invention is also excellent from an economic point of view.
第１図は本発明肌焼鋼の種々の0.2％耐力と破
壊靭性値との関係を従来鋼３例と比較して示した
図である。
FIG. 1 is a diagram showing the relationship between various 0.2% proof strengths and fracture toughness values of case hardening steels of the present invention in comparison with three examples of conventional steels.
Claims (1)
Mn0.20−1.00％、Ni3.00−3.74％、Cr1.00−2.00
％、Mo0.20−0.50％、V0.05−0.30％、残部Feお
よび不可避不純物よりなることを特徴とする高強
度高靭性肌焼鋼。1 C0.15-0.25%, Si0.50% or less on a weight basis,
Mn0.20−1.00%, Ni3.00−3.74%, Cr1.00−2.00
%, Mo0.20-0.50%, V0.05-0.30%, the balance being Fe and unavoidable impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1074781A JPS57126957A (en) | 1981-01-29 | 1981-01-29 | High strength and high toughness case hardening steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1074781A JPS57126957A (en) | 1981-01-29 | 1981-01-29 | High strength and high toughness case hardening steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57126957A JPS57126957A (en) | 1982-08-06 |
| JPH0135909B2 true JPH0135909B2 (en) | 1989-07-27 |
Family
ID=11758894
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1074781A Granted JPS57126957A (en) | 1981-01-29 | 1981-01-29 | High strength and high toughness case hardening steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57126957A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6070166A (en) * | 1983-09-26 | 1985-04-20 | Hitachi Ltd | Creep and oxidation resistant low-alloy steel |
| JPH02243737A (en) * | 1989-03-16 | 1990-09-27 | Aichi Steel Works Ltd | Heat resistant case hardening steel having excellent pitching resistance |
| CN109161658B (en) * | 2018-10-09 | 2020-04-21 | 江阴兴澄特种钢铁有限公司 | Steel for main shaft bearing of wind driven generator and production method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS501339A (en) * | 1973-04-10 | 1975-01-08 | ||
| JPS501340A (en) * | 1973-04-09 | 1975-01-08 |
-
1981
- 1981-01-29 JP JP1074781A patent/JPS57126957A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS501340A (en) * | 1973-04-09 | 1975-01-08 | ||
| JPS501339A (en) * | 1973-04-10 | 1975-01-08 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57126957A (en) | 1982-08-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4157258A (en) | Case-hardening alloy steel and case-hardened article made therefrom | |
| JPS59179762A (en) | Cold tool steel | |
| US2528867A (en) | Production of thermally hardenable boron-titanium steels | |
| US2542220A (en) | Ferritic alloy | |
| JPH0135909B2 (en) | ||
| JPS6263653A (en) | High strength case hardening steel | |
| US2447089A (en) | Low alloy high tensile strength, high impact strength steel | |
| JPH04124217A (en) | Production of high strength gear steel excellent in softening property | |
| JPH0254416B2 (en) | ||
| JPS5916948A (en) | Soft-nitriding steel | |
| JPH0143008B2 (en) | ||
| US4116685A (en) | Tool steel for warm and hot working | |
| US1732202A (en) | Air-toughened alloy steel | |
| JPH0354173B2 (en) | ||
| JP2500948B2 (en) | Manufacturing method of thick 80kgf / mm2 grade high strength steel with excellent weldability | |
| JPS6023187B2 (en) | Thick-walled steel with excellent weldability and sulfide cracking resistance | |
| JPH028020B2 (en) | ||
| JPS61186419A (en) | Production of drive shaft | |
| JPS626614B2 (en) | ||
| JPH07126803A (en) | Steel for carburizing gear | |
| US3136665A (en) | Alloy steel | |
| JPH08176732A (en) | Steel for nitriding having excellent machinability | |
| JPH09241799A (en) | Curburizing steel | |
| JPH0563542B2 (en) | ||
| JPS61253347A (en) | Low carbon steel having superior cold workability |