JPH0672280B2 - High toughness carburizing steel - Google Patents

High toughness carburizing steel

Info

Publication number
JPH0672280B2
JPH0672280B2 JP60138797A JP13879785A JPH0672280B2 JP H0672280 B2 JPH0672280 B2 JP H0672280B2 JP 60138797 A JP60138797 A JP 60138797A JP 13879785 A JP13879785 A JP 13879785A JP H0672280 B2 JPH0672280 B2 JP H0672280B2
Authority
JP
Japan
Prior art keywords
carburizing
less
core
toughness
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.)
Expired - Lifetime
Application number
JP60138797A
Other languages
Japanese (ja)
Other versions
JPS621843A (en
Inventor
公博 柴田
隆 松本
勝典 高田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daido Steel Co Ltd
Nissan Motor Co Ltd
Original Assignee
Daido Steel Co Ltd
Nissan Motor Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Daido Steel Co Ltd, Nissan Motor Co Ltd filed Critical Daido Steel Co Ltd
Priority to JP60138797A priority Critical patent/JPH0672280B2/en
Publication of JPS621843A publication Critical patent/JPS621843A/en
Publication of JPH0672280B2 publication Critical patent/JPH0672280B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Description

【発明の詳細な説明】 (産業上の利用分野) 本発明は優れた靱性を有する浸炭用鋼に関する。TECHNICAL FIELD The present invention relates to a carburizing steel having excellent toughness.

(従来の技術及び問題点) 自動車用ハイポイドギヤ、差動ギヤなど衝撃的な荷重を
受ける部品には、靱性のよい鋼種が浸炭処理して用いら
れている。
(Prior Art and Problems) Steel parts with good toughness are carburized and used for parts such as automobile hypoid gears and differential gears that receive an impact load.

しかし乍ら、自動車用エンジンの高出力化やギヤの小型
化に対応して、それらの部品に要求される耐衝撃強度は
次第に高くなってきているため、現在使われており、比
較的靱性のよいと云われているクロム・モリブデン鋼や
ニッケル・クロム・モリブデン鋼でも上記要求強度を満
足しない例もある。
However, the impact strength required for these parts is gradually increasing in response to the higher output of automobile engines and the downsizing of gears. There are some examples of chromium / molybdenum steel and nickel / chromium / molybdenum steel, which are said to be good, that do not satisfy the required strength.

その対応策としては、かゝる鋼種からなる部品の面粗度
の管理を厳密に行う方法がとられることがあるが、それ
では著しく生産性が阻害されてしまうという問題があ
る。
As a countermeasure, there is a method of strictly controlling the surface roughness of parts made of such steel types, but there is a problem that productivity is significantly hindered.

(発明の目的) 本発明は、上記従来技術の欠点を解消するためになされ
たものであって、従来の浸炭用鋼よりも優れた靱性を有
し、しかも生産性を阻害することなく必要部品を製造し
得る高靱性浸炭用鋼を提供することを目的とするもので
ある。
(Object of the Invention) The present invention has been made in order to solve the above-mentioned drawbacks of the prior art, has a toughness superior to that of the conventional carburizing steel, and is a necessary component without impairing the productivity. It is an object of the present invention to provide a high toughness carburizing steel that can be manufactured.

(発明の構成) 上記目的を達成するため、本発明者等は、従来技術の欠
点の原因究明に努め、その対策を見い出すべく研究を重
ねたところ、Mo及びSiの添加により、浸炭温度において
も心部は安定したフェライトとオーステナイトの2相組
織を保ち、Ti添加によって浸炭層にはTi炭化物、窒化物
を析出させ、心部及び浸炭層ともに微細組織とし、更に
基地をMoで強化して、高い耐衝撃強度を与えることによ
り、可能であるとの知見を得て、更に詳細に検討を加え
た結果、こゝに本発明をなしたものである。
(Structure of the Invention) In order to achieve the above object, the inventors of the present invention endeavored to investigate the cause of the drawbacks of the prior art, and conducted research to find out a countermeasure thereof. By adding Mo and Si, even at the carburizing temperature. The core retains a stable two-phase structure of ferrite and austenite, Ti carbide and nitride are precipitated in the carburized layer by addition of Ti, the core and carburized layer both have a fine structure, and the base is strengthened with Mo. The present invention has been made as a result of further detailed investigations by finding that it is possible to give high impact strength.

すなわち、本発明にかゝる高靱性浸炭用鋼は、C:0.05〜
0.2%、Mo:0.5%超〜1.0%で、かつ、Mo+Si:1〜2%、
Mn:0.3〜1.5%及びTi:0.05〜0.2%含むことを基本成分
とし、更に必要に応じて、Cr:1.5%以下及びNi:2.0%以
下のうちの1種又は2種、及び/又は、結晶粒微細化元
素としてAl:0.1%以下及びN:0.03%以下のうちの1種又
は2種を含み、残部が実質的にFeからなり、オーステナ
イト−フェライト2相領域で浸炭することにより浸炭処
理後の組織として、心部は結晶粒度番号で9番以上の整
細粒のフェライト−マルテンサイト二相組織で、浸炭層
も結晶粒度番号で9番以上の整細粒であり、心部のシャ
ルピー衝撃値が12kgf・m/cm2以上であることを骨子とす
るものである。
That is, the high toughness carburizing steel according to the present invention has a C: 0.05-
0.2%, Mo: over 0.5% to 1.0%, and Mo + Si: 1 to 2%,
Mn: 0.3 to 1.5% and Ti: 0.05 to 0.2% as a basic component, and if necessary, one or two of Cr: 1.5% or less and Ni: 2.0% or less, and / or Carburizing by including one or two of Al: 0.1% or less and N: 0.03% or less as a grain refinement element, the balance consisting essentially of Fe, and carburizing in the austenite-ferrite two-phase region As the subsequent structure, the core has a fine grained ferrite-martensite two-phase structure with a grain size number of 9 or more, and the carburized layer also has a grain size of 9 grain or more with a grain size of 9 or more. The main point is that the impact value is 12 kgf · m / cm 2 or more.

以下に本発明を実施例に基づいて詳細に説明する。The present invention will be described in detail below based on examples.

まず、本発明に係る高靱性浸炭用鋼の成分範囲(wt%)
の限定理由について示す。
First, the composition range (wt%) of the high toughness carburizing steel according to the present invention
The reason for the limitation is shown below.

C:0.05〜0.2% Cは機械構造用鋼としての強度、特に焼入れ後の硬さ確
保に有効な元素であり、浸炭処理後の心部強化のために
最低0.05%の添加が必要である。しかし、0.2%を超え
て添加すると、浸炭温度でオーステナイト単相となり、
心部組織の微細化が困難となるので、上限値は0.2%と
する。
C: 0.05 to 0.2% C is an element effective for securing the strength as a steel for machine structural use, especially the hardness after quenching, and it is necessary to add at least 0.05% for strengthening the core after carburizing. However, if it exceeds 0.2%, it becomes an austenite single phase at the carburizing temperature,
Since it is difficult to refine the core tissue, the upper limit is set to 0.2%.

Mo:0.5%超〜1.0%、かつ、Mo+Si:1〜2% Moは焼入れ硬さの確保及び基地の強化による靱性向上に
有効な元素であり、またSiと共に高温でフェライトを安
定化させるため、浸炭温度で微細なフェライト−オース
テナイト二相組織を実現し、靱性の向上を図るために
は、Mo:0.5%を超える量で、かつ、Mo+Si:1%以上の添
加が必要である。また、Mo:0.5%を超える量の添加で高
靱性を得るためには、Moの添加量を最大1%で、かつ、
Mo+Siを最大2%で十分であり、それ以上添加しても高
靱性化の効果が飽和する。したがって、Moの添加量を0.
5%超〜1.0%で、かつ、Mo+Siの添加量を1%以上、2
%以下に限定する。
Mo: more than 0.5% to 1.0%, and Mo + Si: 1 to 2% Mo is an element that is effective in improving the toughness by securing quenching hardness and strengthening the matrix, and also stabilizes ferrite at high temperature with Si, In order to realize a fine ferrite-austenite two-phase structure at the carburizing temperature and improve the toughness, it is necessary to add Mo in an amount exceeding 0.5% and Mo + Si: 1% or more. Further, in order to obtain high toughness by adding Mo in an amount exceeding 0.5%, the maximum amount of Mo added is 1%, and
A maximum of 2% Mo + Si is sufficient, and the effect of increasing toughness saturates even if more than this is added. Therefore, the addition amount of Mo is 0.
More than 5% to 1.0%, and the addition amount of Mo + Si is 1% or more, 2
% Or less.

Mn:0.3〜1.5% Mnは脱酸、脱硫に有効な元素である。十分な脱酸、脱硫
の効果を得るためには0.3%以上の添加が必要である
が、1.5%を超えて添加すると靱性が劣化するので、1.5
%添加を上限値とする。
Mn: 0.3-1.5% Mn is an element effective for deoxidation and desulfurization. To obtain sufficient deoxidizing and desulfurizing effects, it is necessary to add 0.3% or more, but if added over 1.5%, the toughness deteriorates, so 1.5
% Addition is the upper limit.

Ti:0.05〜0.2% TiはTi炭化物、窒化物などの析出物を形成し、心部及び
浸炭層の組織微細化に有効であるので、最低0.05%の添
加を必要とするが、0.2%を超えて多量に添加すると靱
性が低下するので、上限値を0.2%とする。
Ti: 0.05-0.2% Ti forms precipitates such as Ti carbide and nitride, and is effective for refining the microstructure of the core and carburized layer, so it is necessary to add at least 0.05%, but 0.2% If added in excess, the toughness will decrease, so the upper limit is made 0.2%.

Cr:1.5%以下、Ni:2.0%以下 Cr、Niは鋼の焼入れ性をより一層向上させて基地の強化
を図るのに有効な元素であり、必要に応じて添加するこ
とができる。しかし、Crが1.5%を超え、又はNiが2.0%
を超える量で添加すると靱性が低下するので、添加する
ときはCr:1.5%以下、Ni:2.0%以下のうちの1種又は2
種を添加する。
Cr: 1.5% or less, Ni: 2.0% or less Cr and Ni are effective elements for further improving the hardenability of steel and strengthening the matrix, and can be added if necessary. However, Cr exceeds 1.5% or Ni is 2.0%
If it is added in an amount exceeding 1, the toughness will decrease. Therefore, when adding it, one or two of Cr: 1.5% or less and Ni: 2.0% or less.
Add seeds.

Al:0.1%以下、N:0.03%以下 Al、Nは炭窒化物を形成し、結晶粒を微細化させ、鋼の
靱性を向上するのに有効な元素であるので、必要に応じ
てAl及びNの1種又は2種を添加することができる。し
かし、Alの添加量が0.1%を超えると炭窒化物が粗大化
し、結晶粒微細化の効果が低下して靱性が低下するの
で、0.1%を添加の上限値とする。
Al: 0.1% or less, N: 0.03% or less Al, N is an element effective in forming carbonitrides, refining crystal grains, and improving the toughness of steel. One or two of N can be added. However, if the amount of Al added exceeds 0.1%, the carbonitrides become coarse, the effect of grain refinement decreases and the toughness decreases, so 0.1% is made the upper limit of addition.

また、N含有量が0.03%を超えるとNのブローホール生
成によって鋼塊又は鋳片の健全性が損われるので、Nの
含有量は0.03%以下の範囲とする。
Further, when the N content exceeds 0.03%, the soundness of the steel ingot or the slab is impaired due to the generation of N blowholes, so the N content is set to 0.03% or less.

なお、被削性を向上させるためにPb:0.4%以下、S:0.4
%以下、Te:0.1%以下の範囲で、それらの元素の1種又
は2種以上を適宜含有させることも、必要に応じて望ま
しい。
In order to improve machinability, Pb: 0.4% or less, S: 0.4
%, Te: 0.1% or less, it is also desirable to appropriately contain one or more of these elements, if necessary.

以上のように成分調整した鋼をオーステナイト−フェラ
イト2相領域で浸炭処理することにより、心部は結晶粒
度番号で9番以上(通常、10番以上)の整細粒のフェラ
イト−マルテンサイト二相組織が得られ、浸炭層は結晶
粒度番号で9番以上(通常、10番以上)の整細粒組織が
得られ、心部のシャルピー衝撃値がJIS3号試験片で12kg
f・m/cm2以上となるため、優れた靱性を要求される部
品、特に自動車用ハイポイドギヤ、差動ギヤなどのディ
ファレンシャル部品を製造することが可能となる。
By carburizing the steel whose composition has been adjusted as described above in the austenite-ferrite two-phase region, the core has fine-grained ferrite-martensite two-phase grains with a grain size number 9 or more (usually 10 or more). The structure is obtained, and the carburized layer has a fine-grained structure with a grain size number of 9 or more (usually 10 or more), and the Charpy impact value of the core is 12 kg for JIS 3 test pieces.
Since it is f / m / cm 2 or more, it becomes possible to manufacture parts that require excellent toughness, particularly differential parts such as automobile hypoid gears and differential gears.

なお、本発明鋼に適用する浸炭処理の条件は特に制限さ
れるものではなく、既述の従来の浸炭用鋼の場合と同様
に適用可能である。
The conditions of the carburizing treatment applied to the steel of the present invention are not particularly limited and can be applied similarly to the case of the conventional carburizing steel described above.

次に本発明の実施例を示す。Next, examples of the present invention will be described.

(実施例1) 第1表に示す化学組成の鋼を溶製、造塊し、鍛造により
直径35mmの丸棒を製作した。次いで、925℃に加熱し60
分間均熱保持後空冷する焼きならし処理を施した後、直
径25mmに旋削加工し、第2表に示す条件にて真空浸炭処
理を行った。そして、各々について浸炭層のオーステナ
イト平均結晶粒度及び心部のオーステナイトとフェライ
トの平均結晶粒度を測定した。また、第2表と同一条件
にて真空浸炭処理を施した直径25mmの丸棒の心部よりJI
S3号Uノッチシャルピー試験片を切り出し、シャルピー
衝撃試験を行って衝撃値を測定した。これらの結果を第
1表に示す。
Example 1 Steel having a chemical composition shown in Table 1 was melted, ingoted, and forged to manufacture a round bar having a diameter of 35 mm. Then heat to 925 ℃ 60
After normalizing by air-cooling after soaking for a minute, it was turned to a diameter of 25 mm and vacuum carburized under the conditions shown in Table 2. Then, the average grain size of austenite in the carburized layer and the average grain size of austenite and ferrite in the core were measured for each. Also, from the core of a 25 mm diameter round bar that has been vacuum carburized under the same conditions as in Table 2, JI
A S3 U-notch Charpy test piece was cut out and subjected to a Charpy impact test to measure the impact value. The results are shown in Table 1.

なお、比較鋼として、SNCM420H、SCM420Hの直径25mm丸
棒に対し、第3表に示す条件にて真空浸炭処理を施し、
上記と同様の測定を行った結果も第1表に併記した。
As comparative steel, a 25 mm diameter round bar of SNCM420H and SCM420H was vacuum carburized under the conditions shown in Table 3,
The results of the same measurements as above are also shown in Table 1.

第1表に示すように、本発明鋼(No.1〜5)はいずれ
も、浸炭層のオーステナイト平均結晶粒度は粒度番号で
9番以上であり、心部はフェライトとマルテンサイトの
二相組織で、その平均結晶粒度は9番以上であって、著
しく組織が微細化されている。この組織微細化と靱性向
上元素であるMoの適量添加とにより、シャルピー衝撃値
が12kgf・m/cm2以上を示し、比較鋼のSNCM420Hの浸炭焼
入れ焼戻し材心部と同等乃至それ以上の靱性を有してい
る。なお、他の比較鋼は本発明範囲外の化学組成を有
し、いずれもシャルピー衝撃値が低く、12kgf・m/cm2
は及ばない靱性である。
As shown in Table 1, in all of the steels of the present invention (No. 1 to 5), the austenite average grain size of the carburized layer is 9 or more in grain size, and the core has a two-phase structure of ferrite and martensite. The average grain size is 9 or more, and the structure is remarkably refined. With this refinement of structure and addition of an appropriate amount of Mo, which is a toughness improving element, a Charpy impact value of 12 kgf ・ m / cm 2 or more is exhibited, and a toughness equivalent to or higher than that of the carburized and tempered core of SNCM420H, a comparative steel, is exhibited. Have The other comparative steels have chemical compositions outside the range of the present invention, all have low Charpy impact values, and have toughness not exceeding 12 kgf · m / cm 2 .

次に、第1表のNo.1鋼と、第4表に示す被削性向上元素
を添加したNo.16〜19鋼に対し、第5表に示す条件で被
削性試験を行った。その結果を第6表に示す。同表に示
すように、被削性向上元素を添加することにより、ドリ
ル穴あけ個数の増加が認められ、被削性の著しい向上が
確認された。
Next, the machinability test was conducted on the No. 1 steel in Table 1 and the Nos. 16 to 19 steels containing the machinability improving element shown in Table 4 under the conditions shown in Table 5. The results are shown in Table 6. As shown in the table, by adding the machinability improving element, an increase in the number of drill holes was confirmed, and a remarkable improvement in machinability was confirmed.

(実施例2) 第7表に示す化学組成のNo.20〜22鋼並びにSNCM420H、S
CM420Hについて、実施例1と同一手順で直径25mmの丸棒
を作製し、第8表に示す条件にて高温真空浸炭処理を行
い、実施例1と同様、浸炭層及び心部の平均結晶粒度並
びにシャルピー衝撃値を測定した。それらの結果を第7
表に示す。
(Example 2) No. 20-22 steel and SNCM420H, S having the chemical composition shown in Table 7
With respect to CM420H, a round bar having a diameter of 25 mm was prepared by the same procedure as in Example 1, and high-temperature vacuum carburizing treatment was performed under the conditions shown in Table 8. As in Example 1, the average crystal grain size of the carburized layer and the core and The Charpy impact value was measured. Seventh of those results
Shown in the table.

第7表から明らかなように、本発明鋼No.20は、Mo及びS
iの適量添加により、浸炭処理温度が高温でもフェライ
トが安定であるため、高温浸炭処理後も心部は著しく微
細なフェライトとマルテンサイトの二相組織を保ち、更
にTi添加の効果によって浸炭層のオーステナイトも著し
く微細となり、したがって、微細組織とMo添加による基
地強化との相乗効果により、シャルピー衝撃値は12.5kg
f・m/cm2と優れている。これに対し、比較鋼は、いずれ
も高温浸炭処理後のシャルピー衝撃値が低い。
As is clear from Table 7, the steel No. 20 of the present invention contains Mo and S.
With the addition of an appropriate amount of i, ferrite is stable even at high carburizing temperatures, so the core retains a remarkably fine two-phase structure of ferrite and martensite even after high-temperature carburizing, and the effect of Ti addition causes Austenite also becomes extremely fine, so the Charpy impact value is 12.5 kg due to the synergistic effect of the microstructure and matrix strengthening by adding Mo.
Excellent at f · m / cm 2 . On the other hand, all the comparative steels have a low Charpy impact value after the high temperature carburizing treatment.

(発明の効果) 以上詳述したように、本発明による浸炭用鋼は、MoとSi
の添加により、浸炭温度においても心部が安定なフェラ
イトとオーステナイトの二相組織を保ち、またTi添加に
よって浸炭層にはTi炭化物、窒化物を析出させ、心部及
び浸炭層ともに微細組織を有し、更に基地をMoで強化す
ることを基本としているため、SNCM420H鋼等の従来の浸
炭用鋼以上の優れた靱性を有するものである。また、従
来とられていたような格別厳しい面粗度管理も必要とせ
ずに上記効果を得ることができる。
(Effects of the Invention) As described in detail above, the carburizing steel according to the present invention contains Mo and Si.
The addition of Ti maintains a two-phase structure of ferrite and austenite that is stable in the core even at the carburizing temperature, and Ti addition causes Ti carbide and nitride to precipitate in the carburized layer, and the core and carburized layer have a fine structure. However, since the base is basically strengthened with Mo, it has superior toughness to conventional carburizing steels such as SNCM420H steel. Further, the above effect can be obtained without the need for exceptionally strict surface roughness management that has been taken conventionally.

したがって、本発明による高靱性浸炭用鋼を用いれば、
靱性に優れた自動車用ハイポイドギヤ、差動ギヤなどの
ディファレンシャル部品の製造が可能となる。
Therefore, by using the high toughness carburizing steel according to the present invention,
It is possible to manufacture differential parts such as automobile hypoid gears and differential gears with excellent toughness.

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭59−232252(JP,A) 特開 昭57−192248(JP,A) ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-232252 (JP, A) JP-A-57-192248 (JP, A)

Claims (4)

【特許請求の範囲】[Claims] 【請求項1】重量%で(以下、同じ)、C:0.05〜0.2
%、Mo:0.5%超〜1.0%で、かつ、Mo+Si:1〜2%、Mn:
0.3〜1.5%及びTi:0.05〜0.2%を含み、残部がFe及び不
可避的不純物からなり、オーステナイト−フェライト2
相領域で浸炭することにより浸炭処理後の心部及び浸炭
層の結晶粒が結晶粒度番号9番以上の整細粒で、心部の
シャルピー衝撃値が12kgf・m/cm2以上であることを特徴
とする高靱性浸炭用鋼。
1. In weight% (hereinafter the same), C: 0.05 to 0.2
%, Mo: over 0.5% to 1.0%, and Mo + Si: 1 to 2%, Mn:
Austenite-ferrite 2 containing 0.3 to 1.5% and Ti: 0.05 to 0.2%, the balance being Fe and unavoidable impurities
After carburizing in the phase region, the core and carburized layer after carburization are fine-grained grains with grain size number 9 or more, and the core has a Charpy impact value of 12 kgf ・ m / cm 2 or more. Characteristically high toughness steel for carburizing.
【請求項2】C:0.05〜0.2%、Mo:0.5%超〜1.0%で、か
つ、Mo+Si:1〜2%、Mn:0.3〜1.5%及びTi:0.05〜0.2
%を含み、更にCr:1.5%以下及びNi:2.0%以下のうちの
1種又は2種を含み、残部がFe及び不可避的不純物から
なり、オーステナイト−フェライト2相領域で浸炭する
ことにより浸炭処理後の心部及び浸炭層の結晶粒が結晶
粒度番号9番以上の整細粒で、心部のシャルピー衝撃値
が12kgf・m/cm2以上であることを特徴とする高靱性浸炭
用鋼。
2. C: 0.05 to 0.2%, Mo: more than 0.5% to 1.0%, and Mo + Si: 1 to 2%, Mn: 0.3 to 1.5% and Ti: 0.05 to 0.2.
%, And further contains one or two of Cr: 1.5% or less and Ni: 2.0% or less, the balance being Fe and inevitable impurities, and carburizing by carburizing in the austenite-ferrite two-phase region. High-toughness carburizing steel characterized in that the subsequent core and carburized layer have fine grains with grain size number 9 or more and the Charpy impact value of the core is 12 kgf · m / cm 2 or more.
【請求項3】C:0.05〜0.2%、Mo:0.5%超〜1.0%で、か
つ、Mo+Si:1〜2%、Mn:0.3〜1.5%及びTi:0.05〜0.2
%を含み、更にAl:0.1%以下及びN:0.03%以下のうちの
1種又は2種を含み、残部がFe及び不可避的不純物から
なり、オーステナイト−フェライト2相領域で浸炭する
ことにより浸炭処理後の心部及び浸炭層の結晶粒が結晶
粒度番号9番以上の整細粒で、心部のシャルピー衝撃値
が12kgf・m/cm2以上であることを特徴とする高靱性浸炭
用鋼。
3. C: 0.05-0.2%, Mo: over 0.5% -1.0%, and Mo + Si: 1-2%, Mn: 0.3-1.5% and Ti: 0.05-0.2.
%, And further 1% or less of Al: 0.1% or less and N: 0.03% or less, the balance being Fe and unavoidable impurities, and carburizing by carburizing in the austenite-ferrite two-phase region. High-toughness carburizing steel characterized in that the subsequent core and carburized layer have fine grains with grain size number 9 or more and the Charpy impact value of the core is 12 kgf · m / cm 2 or more.
【請求項4】C:0.05〜0.2%、Mo:0.5%超〜1.0%で、か
つ、Mo+Si:1〜2%、Mn:0.3〜1.5%及びTi:0.05〜0.2
%を含み、更にCr:1.5%以下及びNi:2.0%以下のうちの
1種又は2種を含み、更にAl:0.1%以下及びN:0.03%以
下のうちの1種又は2種を含み、残部がFe及び不可避的
不純物からなり、オーステナイト−フェライト2相領域
で浸炭することにより浸炭処理後の心部及び浸炭層の結
晶粒が結晶粒度番号9番以上の整細粒で、心部のシュル
ピー衝撃値が12kgf・m/cm2以上であることを特徴とする
高靱性浸炭用鋼。
4. C: 0.05 to 0.2%, Mo: more than 0.5% to 1.0%, and Mo + Si: 1 to 2%, Mn: 0.3 to 1.5%, and Ti: 0.05 to 0.2.
%, And further Cr: 1.5% or less and Ni: 2.0% or less one or more, further Al: 0.1% or less and N: 0.03% or less one or more, The balance consists of Fe and unavoidable impurities, and by carburizing in the austenite-ferrite two-phase region, the crystal grains of the core and carburized layer after carburizing are fine grains with a grain size of No. 9 or more, and the shuffle of the core High toughness carburizing steel characterized by an impact value of 12 kgf · m / cm 2 or more.
JP60138797A 1985-06-25 1985-06-25 High toughness carburizing steel Expired - Lifetime JPH0672280B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP60138797A JPH0672280B2 (en) 1985-06-25 1985-06-25 High toughness carburizing steel

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP60138797A JPH0672280B2 (en) 1985-06-25 1985-06-25 High toughness carburizing steel

Publications (2)

Publication Number Publication Date
JPS621843A JPS621843A (en) 1987-01-07
JPH0672280B2 true JPH0672280B2 (en) 1994-09-14

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Country Link
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Publication number Priority date Publication date Assignee Title
US5545747A (en) * 1990-08-16 1996-08-13 Kanto Kagaku Kabushiki Kaisha Cyclobutanecarboxylic acid derivatives and liquid crystalline compositions containing them
JP3883782B2 (en) * 2000-05-17 2007-02-21 山陽特殊製鋼株式会社 Case-hardened steel with excellent pitting resistance
JP5558887B2 (en) * 2010-03-30 2014-07-23 山陽特殊製鋼株式会社 Manufacturing method of high strength parts using Ti and B added steels with excellent low cycle fatigue strength

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JPS57192248A (en) * 1981-05-22 1982-11-26 Daido Steel Co Ltd Bit for excavating stratum
JPH0454736B2 (en) * 1983-06-13 1992-09-01 Daido Steel Co Ltd

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