JPS60159116A - Manufacture of steel parts having high hardenability and toughness - Google Patents
Manufacture of steel parts having high hardenability and toughnessInfo
- Publication number
- JPS60159116A JPS60159116A JP1303184A JP1303184A JPS60159116A JP S60159116 A JPS60159116 A JP S60159116A JP 1303184 A JP1303184 A JP 1303184A JP 1303184 A JP1303184 A JP 1303184A JP S60159116 A JPS60159116 A JP S60159116A
- Authority
- JP
- Japan
- Prior art keywords
- toughness
- hardenability
- coarsening
- austenite
- austenite crystal
- 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
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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/78—Combined heat-treatments not provided for above
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)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本考案は焼入性と強靭性の良好な鋼部品の製造方法、よ
り詳しくは低合金鋼を用いて、表面部のオーステナイト
結晶粒（側杖に、内部のそれを粗粒にすることにより、
焼入性と強靭性との改善を計った部品の製造方法に関す
る。Detailed Description of the Invention (Industrial Field of Application) The present invention provides a method for manufacturing steel parts with good hardenability and toughness, and more specifically, a method for manufacturing steel parts with good hardenability and toughness. By coarsening the inside of the cane,
This invention relates to a method for manufacturing parts with improved hardenability and toughness.
（従来技術）
鋼部品の焼入性は、通常、合金元素の種類や酷加量、マ
スの大きさ、オーステナイト結晶粒径等によって決定さ
れる。特にオーステナイト結晶粒径に関しては、それが
大きい程焼入性を向上させるものとなり、にれは焼入に
際して焼入温度を高めることやＡｉ Ｎ、ＴｉＮ等オー
ステナイト結晶粒成長抑制粒子量の低減によって可能で
あるが、一様に粗大化してしまう。（なお、加熱時間を
延長することによでも達成可能である。）
一方、鋼部品の性能は通常、最大応力発生部位である表
面部の強靭性に負うところが大きく、この意味で、部品
表面部は可及的にオーステナイト結晶粒径が小さくかつ
完全焼入組織が得られることが望まれる。(Prior Art) The hardenability of steel parts is usually determined by the type of alloying element, amount of stress, mass size, austenite grain size, etc. In particular, regarding the austenite crystal grain size, the larger it is, the better the hardenability is, and cracking can be achieved by increasing the quenching temperature during quenching and reducing the amount of particles that inhibit austenite crystal grain growth, such as AiN and TiN. However, it becomes uniformly coarse. (This can also be achieved by extending the heating time.) On the other hand, the performance of steel parts usually depends largely on the toughness of the surface area, which is the area where the maximum stress occurs; It is desired that the austenite crystal grain size be as small as possible and that a completely quenched structure be obtained.
すなわち、オーステナイト結晶粒に関しては、焼入性の
面からは可及的に大きく、強靭性の面からは可及的に小
さいことが望ましい訳であるが、このオーステナイト結
晶粒径は、素材の製造履歴（製鋼条件、鍛圧条件等）の
影響を除けば、前記した焼入条件によって一義的に決ま
る。このため、オーステナイト結晶粒径の調整によって
、前記二つの性能面を同時に満足させることは実質不可
能で、従来は高価な合金元素の添加によって、あるいは
浸炭、窒化等の表面処理によって、それら性能を保証し
ていた。In other words, it is desirable that the austenite crystal grains be as large as possible from the viewpoint of hardenability and as small as possible from the viewpoint of toughness, but the austenite crystal grain size is determined by the manufacturing process of the material. Excluding the influence of history (steel manufacturing conditions, forging conditions, etc.), it is uniquely determined by the above-mentioned quenching conditions. For this reason, it is virtually impossible to satisfy the above two performance aspects at the same time by adjusting the austenite grain size. Conventionally, these performances have been improved by adding expensive alloying elements or by surface treatments such as carburizing and nitriding. It was guaranteed.
（発明の目的）
本発明は上記従来技術の背景に鑑み、表面部のオーステ
ナイト結晶粒を細粒に、内部のそれを粗粒にすることに
より、焼入性と強靭性の双方を同時に改善し、もって使
用材料の低級化を計ることができる鋼部品の製造方法を
提供することを目的とする。(Object of the Invention) In view of the background of the prior art described above, the present invention improves both hardenability and toughness at the same time by making the austenite crystal grains in the surface part finer and the inner parts coarser. The object of the present invention is to provide a method for manufacturing steel parts that can reduce the grade of materials used.
（発明の構成）
そして、この目的は０．Ｏ１〜０．１ω１２ 丁１０．
０２〜０．ｆＪ Ａ４のうち少くとも一種を含みかつ窒
素を１００ｐｐＨ以下に抑えた低合金鋼を素材にし、始
め素材のオーステナイト結晶粒粗大化温度より低い温度
で浸窒処理を施し、后オーステナイト結晶粒粗大化温度
より高い温度に加熱して焼入処理を施すようにした鋼部
品の製造方法によって達成される。(Structure of the invention) This purpose is 0. O1~0.1ω12 D10.
02~0. A low alloy steel that contains at least one type of fJ A4 and suppresses nitrogen to 100 ppH or less is used as a material, and is nitrided at a temperature lower than the austenite grain coarsening temperature of the initial material, and then the austenite grain coarsening temperature is lowered. This is achieved by a method of manufacturing steel parts that is heated to a higher temperature and subjected to quenching treatment.
本発明において、低合金鋼を素材の対象としたのは、Ｏ
ｒ 、 Ｍｏ 、 Ｎｉ等を多量に含む中、高合金銅で
は、それ自体焼入性が良好でかつ高強靭性を具備してお
り、オーステナイト結晶粒径を調整してもあまり意味が
ない理由による。In the present invention, low alloy steel is used as the material because O
This is because high-alloy copper, which contains a large amount of r, Mo, Ni, etc., has good hardenability and high strength and toughness, so adjusting the austenite grain size does not make much sense. .
また、本発明において、ＴｉおよびＡｇＬを添加元素と
して選択したのは、Ｔｉ、Ａｌｌとも窒化物形成能力が
大きくて、浸窒処理により容易にＴｉＮ −あるいはＡ
ＩＮを形成し、これら窒化物が部品表面部のオーステナ
イト結晶粒成長の抑制作用を果す理由による。そして、
Ｔ１を特に０．０１〜０．１ ωｔＸの範囲としたのは
、それが０．Ｏ１ωｔＸ未満では生成するＴｉＮの量が
不足し、０．１ ωｔｚを越えるといたずらにＴｉＮ量
を増やして部品性能を低下させるためであり７、一方、
Ａｉを特に０．０２〜０，５ωを駕の範囲としたのは
、０．０２ωｔｚ未満では生成するＡｕＮ量が不足し、
０．５ωｔ％を越えると、Ｔ１の場合と同様いたずらに
ＡｕＮ量を増やして部品性能を低下させるためである。In addition, in the present invention, Ti and AgL were selected as additive elements because both Ti and All have a large nitride forming ability, and they can be easily formed into TiN - or A by nitriding treatment.
This is because IN is formed and these nitrides act to suppress the growth of austenite crystal grains on the surface of the component. and,
The reason why T1 is specifically set in the range of 0.01 to 0.1 ωtX is that it is 0.01 to 0.1 ωtX. If it is less than O1ωtX, the amount of TiN generated will be insufficient, and if it exceeds 0.1ωtz, the amount of TiN will increase unnecessarily and the performance of the part will deteriorate7. On the other hand,
The reason why Ai is particularly set in the range of 0.02 to 0.5ω is that if it is less than 0.02ωtz, the amount of AuN generated is insufficient.
This is because if it exceeds 0.5 ωt%, as in the case of T1, the amount of AuN will increase unnecessarily and the performance of the part will deteriorate.
さらに、鋼中の窒素を１１００ｐｐ以下に抑えたのは、
これを越えると、前記添加元素Ｔｉ、Ａ文との間に合金
溶製段階で多量の窒化物が形成されるようになり、これ
ら窒化物の分散によって部品の内部のオーステナイト結
晶粒の粗大化が困難になる理由による。Furthermore, the nitrogen content in the steel was kept below 1100pp by
If this value is exceeded, a large amount of nitrides will be formed between the additive elements Ti and A during the alloy melting stage, and the dispersion of these nitrides will cause the austenite crystal grains inside the part to become coarser. Depends on why it becomes difficult.
（実施例） 以下、本発明の実施例を添付図面も参照して説明する。(Example) Embodiments of the present invention will be described below with reference to the accompanying drawings.
第１図は本発明の方法を実行する基本的な熱処理方法の
一例を示したものである。本実施例の特徴とするところ
は、浸窒処理を施す第１工程Ｉとオーステナイト結晶粒
の粗大化処理を施す第２王程１１とを組合せた点にある
。FIG. 1 shows an example of a basic heat treatment method for carrying out the method of the present invention. The feature of this embodiment is that the first step I, which performs nitriding treatment, and the second step 11, which performs coarsening treatment of austenite crystal grains, are combined.
すなわち、０．０１〜９．１ ωｔ Ｚ Ｐｉ 、 ０
．１〜０．３ωｔ％Ａｌｌのうちの少くとも一種を含み
、かつ窒素含有量を１００ＰＰＩＩ以下に抑えた低合金
鋼素材から部品を形成し、これを、先ず浸窒雰囲気中の
所定温度Ｔｌ（オーステナイト結晶粒粗大化温度未満）
に所定時間ｔだけ保持すると（第１工程Ｉ）、部品表面
から窒素が侵入して表面部に多量のＴｉＮあるいは＾ｆ
ＬＮが形成される。その后、素材に特有のオーステナイ
ト結晶粒の粗大化温度以上である所定温度Ｔ２に所定時
下ｔだけ保持すると（第２工程ＩＩ）、部品表面部は前
記ＴｉＮあるいはＡ！ｌＮの存在によりオーステナイト
結晶粒の粗大化が抑制され、一方、部品内部は前記した
制約条件がないため、オーステナイト結晶粒が粗大化す
る。That is, 0.01 to 9.1 ωt Z Pi , 0
．． A part is formed from a low alloy steel material containing at least one type of 1 to 0.3 ωt% All and with a nitrogen content of 100 PPII or less, and is first heated to a predetermined temperature Tl (austenite below grain coarsening temperature)
When held for a predetermined time t (first step I), nitrogen enters from the surface of the part and a large amount of TiN or ^f is deposited on the surface.
LN is formed. After that, when held at a predetermined temperature T2, which is higher than the coarsening temperature of austenite crystal grains peculiar to the material, for a predetermined time t (second step II), the surface of the part is formed of the TiN or A! The presence of IN suppresses the coarsening of austenite crystal grains, while the interior of the component does not have the above-mentioned constraint conditions, so the austenite crystal grains become coarse.
第２工程■を終えた部品は、そのま〜急冷焼入処理され
るものとなり、この時、表面部は、その部分自体の冷却
速度が大きくかつ固溶窒素の存在により焼入性が良ｌｆ
になっているため、はＣ完全なる焼入組織（マルテンサ
イト）が得られるようになり、一方、内部はオーステナ
イト結晶粒の粗大化によって焼入性が良好になっている
ため、同様には釘完全なる焼入組織が得られるようにな
る。The parts that have completed the second step (2) are subjected to a rapid cooling and hardening treatment, and at this time, the surface portion has good hardenability due to the large cooling rate of that portion itself and the presence of solid solution nitrogen.
As a result, a completely C hardened structure (martensite) can be obtained.On the other hand, the inside has good hardenability due to coarsening of austenite crystal grains, so it is also possible to obtain a hardened structure (martensite). A complete hardened structure can be obtained.
なお、焼入性は部品の大きさによっても影響を受けるの
で、前記焼入性に見合った部品大きさが選択されること
はもちろんである。また、ｂ記焼入処理後は、通常の焼
もどし処理が施される。In addition, since the hardenability is also affected by the size of the part, it goes without saying that the size of the part should be selected in accordance with the hardenability. Further, after the quenching process b, a normal tempering process is performed.
第２図は本発明の方法を実行する熱処理方法の他の例を
示したものである。本実施例の特徴とするところは、既
存の浸炭焼入あるいは浸炭窒化焼入を施す第１工程工′
と前記同様の、オーステナイト結晶粒の粗大化処理であ
る第２の工程■とを組合せた点にある。FIG. 2 shows another example of a heat treatment method for carrying out the method of the present invention. The feature of this embodiment is that the first step is to perform the existing carburizing and quenching or carbonitriding and quenching.
and the second step (2), which is a coarsening treatment of austenite crystal grains, as described above.
すなわち、前記同様のＴｉ、ＡＭ等を含む低合金鋼から
部品を形成し、これを浸炭あるいは浸炭浸窒雰囲気中の
所定の温度Ｔ３に所定時間ｔ３保持すると（第１工程１
′）、浸炭雰囲気の場合には雰囲気中の窒素が分解して
、一方、浸炭浸窒雰囲気の場合には積極的に添加したＮ
Ｈ３ガスが分解して１部品表面に侵入し、該部品表面
にはＴｉＮあるいはＡｉＮが形成される。その后、部品
を変態点Ａ１以下に冷却し、続いて前記同様にオーステ
ナイト結晶粒の粗大化温度以上である所定温度Ｔ２に所
定時間ｔ２だけで保持すると（第２王程■）、部品内部
のオーステナイト結晶粒が粗大化し、以降の焼入によっ
て、部品内外部ははぐ完全なる焼入組織が得られるよう
になる具体例として、合金組成が重量パーセント（ωｔ
Ｄで、０．３Ｇ−０，８Ｍｎ −０，２５Ｓｉ−０，２
Ｃｒ −０，２４Ａｎ −０，００２３Ｂ −０，０９
５Ｎ−Ｂａｉ 、Ｆｅからなる素材を用いて、試験片を
形成し、これを第２図に示す熱処理線図にしたがって処
理した。That is, when a part is formed from a low alloy steel containing Ti, AM, etc. similar to the above, and is held at a predetermined temperature T3 in a carburizing or carbo-nitriding atmosphere for a predetermined time t3 (first step 1
') In the case of a carburizing atmosphere, nitrogen in the atmosphere decomposes, while in the case of a carburizing atmosphere, the actively added N
The H3 gas decomposes and enters the surface of one component, forming TiN or AiN on the surface of the component. After that, if the part is cooled to below the transformation point A1 and then held at a predetermined temperature T2, which is above the coarsening temperature of austenite crystal grains, for a predetermined time t2 in the same manner as described above, the inside of the part As a specific example, the austenite crystal grains become coarse and a complete quenched structure is obtained that peels off the inside and outside of the part through subsequent quenching.
D, 0.3G-0,8Mn-0,25Si-0,2
Cr -0,24An -0,0023B -0,09
A test piece was formed using a material consisting of 5N-Bai and Fe, and was treated according to the heat treatment diagram shown in FIG.
熱処理条件は、雰囲気：浸＊（Ｒ１ガス＋ブタン）、浸
炭温度Ｔ ： ９５０ ’Ｏ１浸炭時間ｔ：３００分、
粗大化温度Ｔ ： ８５０°Ｃ１粗大化時間ｔ：４５分
とした。The heat treatment conditions were: atmosphere: immersion* (R1 gas + butane), carburizing temperature T: 950'O1 carburizing time t: 300 minutes,
Coarsening temperature T: 850°C1 Coarsening time t: 45 minutes.
第３図は、上記処理后の部品における表面部のＡ文Ｎ濃
度分布を示したもので、これにより、 ＡｉＮ量は表面
から内部に向けて急激に濃度を低下させているものの、
表面からは＜ ０．４■深さまで多量に存在することが
確認できた。Figure 3 shows the AiN concentration distribution on the surface of the part after the above treatment, and it shows that although the AiN concentration decreases rapidly from the surface to the inside,
It was confirmed that it existed in large quantities down to a depth of <0.4 ■ from the surface.
また、同じく部品表面のミクロ組織を顕微鏡によって確
認したとこる、第４図（写真）に示す結果が得られた。Further, the microstructure of the surface of the component was also confirmed using a microscope, and the results shown in FIG. 4 (photo) were obtained.
すなわち、写真中、網状の黒線が前オーステナイト結晶
粒界を表わしており、オーステナイト結晶粒は、表面か
ら０．３＋ｅｍ深さイづ近までは非常に細かく、それよ
り内部側では非常に粗大化している様子が明らかである
。In other words, in the photograph, the net-like black lines represent the pre-austenite grain boundaries, and the austenite grains are very fine up to a depth of 0.3+em from the surface, and become very coarse inside. It is clear that
このように１本発明の方法によれば、部品表面部のオー
ステナイト結晶粒を細粒に、部品内部のオーステナイト
結晶粒を粗粒に調整できることとなり、部品は全体とし
てその性能が十分に確保されるものとなる。As described above, according to the method of the present invention, the austenite crystal grains on the surface of the part can be adjusted to fine grains, and the austenite crystal grains inside the part can be adjusted to coarse grains, and the performance of the part as a whole can be sufficiently ensured. Become something.
（発明の効果）
以上詳細に説明したように、本発明はＴｉ とＡ文のう
ちの少くとも一種を含みかつ含有窒素を低く抑えた低合
金鋼を素材にして、始め表面に浸窒処理を、続いてオー
ステナイト結晶粒の粗大化処理を施すようにした鋼部品
の製造方法を確立したもので、これにより１部品表面部
のオーステナイト結晶粒が微細に、部品内部のオーステ
ナイト結晶粒が粗大になって、部品は全体として焼入性
が改善されるようになり、結果的に、より低級の使用材
料の選択が可能になる効果が得られた。また部品表面部
は、組織的にち密でかつ高硬度に調質されるものとなり
。(Effects of the Invention) As explained in detail above, the present invention uses a low alloy steel containing at least one of Ti and A and containing low nitrogen content, and first nitriding the surface. Subsequently, a method for manufacturing steel parts was established in which the austenite crystal grains were coarsened.This process made the austenite crystal grains on the surface of the part finer and the austenite crystal grains inside the part coarser. As a result, the hardenability of the parts was improved as a whole, and as a result, it was possible to select lower-grade materials. In addition, the surface of the part is thermally refined to have a dense structure and high hardness.
より強靭性が向上するという効果が得られた。The effect of further improving toughness was obtained.
第１図と第２図は本発明の方法を実行する熱処理線図、
第３図は本発明の方法により得た鋼部品の表面部の＾９
．Ｎ濃度分布図、第４図は処理済みの鋼部品の表面部ミ
クロ組織を示す顕微鏡写真である。
特許出願人 トヨタ自動車株式会社
代理人 弁理士 萼 優 ！！！！（ほか１名）％１図
Ｉｎ
２２Ｆ！！Ｊ
矛３ 図
？４１1 and 2 are heat treatment diagrams for carrying out the method of the present invention,
Figure 3 shows the surface of a steel part obtained by the method of the present invention.
．． The N concentration distribution diagram, FIG. 4, is a microscopic photograph showing the surface microstructure of the treated steel part. Patent applicant Toyota Motor Corporation Representative Patent attorney Yu Sae! ! ! ! (1 other person) %1 figure in 22F! ! J spear 3 figure? 41
Claims (1)
０．０２〜０．５％ ＡＩＬ（７） ウちの少くとも
一種を含みかつ窒素を１１００ｐｐ以下に抑えた低合金
鋼を素材にし、始め浸窒処理を施し、后オーステナイト
結晶粒粗大化温度に保持して焼入処理を施すことを特徴
とする焼入性と強靭性の良好な鋼部品の製造方法。(+) 0.01-0.1 (1) t% Ti,
0.02-0.5% AIL (7) The material is made of low-alloy steel that contains at least one of the following and has nitrogen suppressed to 1100 pp or less, is first subjected to nitriding treatment, and then maintained at the austenite grain coarsening temperature. A method for producing steel parts with good hardenability and toughness, characterized by subjecting the steel parts to hardenability and toughness.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1303184A JPS60159116A (en) | 1984-01-27 | 1984-01-27 | Manufacture of steel parts having high hardenability and toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1303184A JPS60159116A (en) | 1984-01-27 | 1984-01-27 | Manufacture of steel parts having high hardenability and toughness |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS60159116A true JPS60159116A (en) | 1985-08-20 |
Family
ID=11821757
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1303184A Pending JPS60159116A (en) | 1984-01-27 | 1984-01-27 | Manufacture of steel parts having high hardenability and toughness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60159116A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5503687A (en) * | 1993-10-05 | 1996-04-02 | Berns; Hans | Nitrogen enrichment of surface and near surface regions to produce a high-strength austenitic surface layer in stainless steels |
| CN102864343A (en) * | 2012-08-29 | 2013-01-09 | 河北工业大学 | Preparation method for in-situ aluminium base composite material inoculant |
-
1984
- 1984-01-27 JP JP1303184A patent/JPS60159116A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5503687A (en) * | 1993-10-05 | 1996-04-02 | Berns; Hans | Nitrogen enrichment of surface and near surface regions to produce a high-strength austenitic surface layer in stainless steels |
| CN102864343A (en) * | 2012-08-29 | 2013-01-09 | 河北工业大学 | Preparation method for in-situ aluminium base composite material inoculant |
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