JP2546045B2 - Case hardening steel - Google Patents
Case hardening steelInfo
- Publication number
- JP2546045B2 JP2546045B2 JP2217125A JP21712590A JP2546045B2 JP 2546045 B2 JP2546045 B2 JP 2546045B2 JP 2217125 A JP2217125 A JP 2217125A JP 21712590 A JP21712590 A JP 21712590A JP 2546045 B2 JP2546045 B2 JP 2546045B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- machinability
- steel
- hardness
- hardening 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 - Fee Related
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- Heat Treatment Of Steel (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Description
【発明の詳細な説明】 「発明の目的」 （産業上の利用分野） 本発明は肌焼鋼に係り、省エネルギー、省工程的で漬
炭時の歪も小さい肌焼鋼を提供しようとするものであ
る。DETAILED DESCRIPTION OF THE INVENTION “Object of the Invention” (Field of Industrial Application) The present invention relates to case-hardening steel, which is intended to provide energy-saving, process-saving case-hardening steel with small strain during carburizing. Is.
（従来の技術） 肌焼鋼を用いた部品の加工工程として、熱間鍛造−焼
ならし−切削仕上−浸炭処理がある。即ち熱間鍛造によ
る成形時には加熱温度が1200℃程度になり、結晶粒度が
大きく、鍛造後の硬度が高いため被削性が悪い。そこで
一般的には熱間鍛造後に焼ならしを行って組織を微細化
し、硬さを低減させて切削を行うものである。(Prior Art) There are hot forging, normalizing, cutting finish, and carburizing as the processing steps of parts made of case hardening steel. That is, when forming by hot forging, the heating temperature is about 1200 ° C., the grain size is large, and the hardness after forging is high, resulting in poor machinability. Therefore, generally, after hot forging, normalization is performed to refine the structure and reduce hardness to perform cutting.
しかしこのような熱処理（焼ならし）を行うことは製
造工程が煩雑で熱エネルギーを増大し、コスト高を招く
ことから特公昭61−54844ではTi、Zr、Hfの１種以上を
含有させて結晶粒の微細化を図っている。However, performing such heat treatment (normalization) complicates the manufacturing process, increases thermal energy, and raises the cost, so in Japanese Examined Patent Publication No. 61-54844, at least one of Ti, Zr, and Hf is contained. We are trying to make the crystal grains finer.
また肌焼鋼は最終形状に加工された後、920℃程度で
数時間加熱し漬炭されるため結晶粒度が大きくなり易
い。これについては多くの研究がなされており、Al、N
b、Ti等の析出物を用いて結晶粒粗大化防止を図ってお
り、特公昭61−54844ではTiなどによって対処してい
る。Further, since the case-hardening steel is processed into the final shape, it is heated at about 920 ° C. for several hours to be carburized, so that the grain size tends to be large. Much research has been done on this, and Al, N
Precipitates such as b and Ti are used to prevent the coarsening of crystal grains, and in JP-B-61-54844, Ti is used to deal with the problem.
（発明が解決しようとする課題） 上記したような析出物を用いた結晶粒粗大化防止技術
によるものは熱間鍛造時と浸炭時の加熱温度差が大きい
ため同じ析出物で結晶粒粗大化防止を図ることは困難で
ある。(Problems to be Solved by the Invention) Since the crystal grain coarsening prevention technique using the above-described precipitates has a large heating temperature difference between hot forging and carburizing, the same precipitates prevent crystal grain coarsening. Is difficult to achieve.
又特公昭61−54844によるものでは焼ならし本来の目
的である硬さの低減ないし被削性の向上が必ずしも有効
に得られていない。Further, according to Japanese Examined Patent Publication No. 61-54844, reduction of hardness or improvement of machinability, which is the original purpose of normalizing, is not necessarily effectively obtained.
従って製造工程の煩雑且つ高コスト化を避け、しかも
被削性が良好で、浸炭処理時に結晶粒粗大化を生じない
ような肌焼鋼は未だ得られるに到っていない。Therefore, a case-hardening steel that avoids the complexity and cost increase of the manufacturing process, has good machinability, and does not cause crystal grain coarsening during carburizing treatment has not yet been obtained.
「発明の構成」 （課題を解決するための手段） 本発明は上記したような従来技術における課題を解消
するように鋭意研究した結果、Tiの微量添加、Ｓの添
加、焼入性指数制御により焼ならしを行うことなしに被
削性を向上させ、且つAlとＮのバランス制御を行うこと
により浸炭時の結晶粒粗大化防止を図ることに成功した
ものであって、以下の如くである。"Structure of the Invention" (Means for Solving the Problems) The present invention has been eagerly studied so as to solve the problems in the above-described conventional techniques, and as a result, it is possible to add a small amount of Ti, add S, and control the hardenability index. The machinability was improved without normalizing, and the balance control of Al and N was performed to succeed in preventing the coarsening of crystal grains during carburization. .
C:0.15〜0.35wt％、Si:0.5wt％以下、 Mn:0.5wt％以下、Cr:1.5wt％以下、 Mo:0.25wt％以下、 S:0.03〜0.05wt％、 Ti:0.005〜0.015wt％、 Al/N＊:1.5〜2.8 DI:85〜90mm を含有し、残部がFeおよび不可避的不純物から成ること
を特徴とした肌焼鋼。C: 0.15-0.35wt%, Si: 0.5wt% or less, Mn: 0.5wt% or less, Cr: 1.5wt% or less, Mo: 0.25wt% or less, S: 0.03-0.05wt%, Ti: 0.005-0.015wt %, Al / N * : 1.5 to 2.8 D I : 85-90mm A case-hardening steel containing, and the balance consisting of Fe and inevitable impurities.
（作用） 上記したような本発明における成分組成範囲をwt％
（以下単に「％」という）によって説明すると、以下の
如くである。(Function) The composition range of the present invention as described above is set to wt%.
It will be described below by (hereinafter simply referred to as “%”).
C:0.15〜0.35％。C: 0.15 to 0.35%.
Ｃは、強度確保のため0.15％以上を必要とするが、0.
35％を超えると心部の靭性が低下するので、0.15〜0.35
％とする。C requires 0.15% or more to secure the strength, but 0.
When it exceeds 35%, the toughness of the core decreases, so 0.15 to 0.35
%.
Si:0.5％以下。Si: 0.5% or less.
脱酸に必要な元素であるが、0.5％を超えると靭性が
劣化するので0.5％以下とする。It is an element necessary for deoxidation, but if it exceeds 0.5%, the toughness deteriorates, so it is made 0.5% or less.
Mn:1.5％以下。Mn: 1.5% or less.
焼入性確保のため必要であるが、1.5％を超えると焼
入性が大きくなり過ぎるので1.5％以下とした。It is necessary to ensure hardenability, but if it exceeds 1.5%, the hardenability becomes too large, so it was made 1.5% or less.
Cr:1.5％以下。Cr: 1.5% or less.
Crも、焼入性確保のため必要であるが、1.5％を超え
ることにより焼入性が大きくなり過ぎるので1.5％を上
限とする。Cr is also necessary to secure hardenability, but if it exceeds 1.5%, the hardenability becomes too large, so 1.5% is made the upper limit.
Mo:0.25％以下。Mo: 0.25% or less.
Moも、Mn、Crと同じに焼入性を得るために必要である
けれども、このMoは0.25％を超えることによって焼入性
が大きくなり過ぎるから0.25％以下とすることが必要で
ある。Mo is also required to obtain hardenability like Mn and Cr, but since Mo exceeds 0.25%, the hardenability becomes too large, so Mo is required to be 0.25% or less.
S:0.03〜0.05％。S: 0.03 to 0.05%.
Ｓは、被削性を向上させる元素であり、0.03％以上を
必要とする。然し0.05％を超えると疲労特性、靭性など
に悪影響を及ぼすのでこれを上限とし、0.03〜0.05％の
範囲内とする。S is an element that improves machinability and requires 0.03% or more. However, if it exceeds 0.05%, it has an adverse effect on fatigue properties, toughness, etc., so this is made the upper limit, and made within the range of 0.03 to 0.05%.
Ti:0.005〜0.015％。Ti: 0.005 to 0.015%.
Tiは、Ｎと結合してTiNとなり、熱間鍛造のような高
温に加熱したときにオーステナイト結晶粒の粗大化を防
止する作用があるので0.005％以上を必要とするが、一
方TiN粒子は硬質なためその量が増すと被削性などに悪
影響を及ぼすので0.015％以下とする。Ti combines with N to become TiN, which has a function of preventing coarsening of austenite crystal grains when heated to a high temperature such as hot forging, so 0.005% or more is required, while TiN particles are hard. Therefore, if the amount increases, machinability will be adversely affected, so 0.015% or less.
Ｎは、Tiと結合してTiNとなる以外に多量に添加しAl
とも結合し、漬炭時におけるオーステナイト結晶粒の粗
大化を防止する作用があるので（Ti/3.42＋0.01）％以
上を必要とするが、一方0.02％を超えると靭性が劣化す
るので0.02％以下とする。 N is added to Ti in addition to TiN to add a large amount of Al
(Ti / 3.42 + 0.01)% or more is required because it has the effect of preventing the coarsening of austenite crystal grains during carburizing, but on the other hand, if it exceeds 0.02%, the toughness deteriorates, so 0.02% Below.
Al/N＊:1.5〜2.8 Ｎと結合してAlNとなり、浸炭時のオーステナイト結
晶粒粗大化防止を図るが、Tiと結合した残りのＮ
（Ｎ＊：有効窒素）との比率が1.5〜2.8のときに効果が
あり、この範囲外では結晶粒が粗大化するので上記範囲
内とする。Al / N * : Combined with 1.5 to 2.8 N to become AlN, which prevents coarsening of austenite crystal grains during carburization, but the remaining N combined with Ti
It is effective when the ratio with (N * : available nitrogen) is 1.5 to 2.8, and crystal grains become coarse outside this range, so the range is set to the above range.
DI:85〜90mm 焼入指数DIを規定するのは85mm以下では焼入性が低過
ぎて不完全焼入を生じ易く、一方90mm以上では熱間鍛造
後の硬さが高くなり過ぎて被削性に悪影響を及ぼす。従
って85mm以上90mm以下とする。D I : 85 to 90 mm The quenching index D I is specified because if it is 85 mm or less, the hardenability is too low and incomplete quenching easily occurs, while if it is 90 mm or more, the hardness after hot forging is too high. It adversely affects machinability. Therefore, it should be 85 mm or more and 90 mm or less.
（実施例） 本発明者等は本発明の成分範囲内で、DI値の異る鋼を
溶製し、これを60mmφに圧延し、1200℃加熱による熱間
鍛造にて30mmφにした場合の硬さ、工具寿命の関係を要
約したのが第１図である。(Example) The present inventors have within composition range of the present invention, it was melted and different Ru steel D I value, which was rolled to 60 mm, in the case of a 30mmφ by hot forging by 1200 ° C. heating FIG. 1 summarizes the relationship between hardness and tool life.
即ち第１図に示すようにDI値が90mmを超えると硬さが
高くなり、被削性が劣化する。Tiの如何によるミクロ組
織を第２図に示した。即ちTiの有無でDI値のほぼ同等の
２鋼種を30mmφに熱間鍛造後のミクロ組織を第２図に示
すが、Ti添加鋼の組織はフェライト・パーライト、Ti無
添加鋼の組織は、フェライト・ベイナイトでTi添加によ
り細粒化し焼入性が低下しベイナイトが出にくくなって
いることが知られる。That is, as shown in FIG. 1, when the D I value exceeds 90 mm, the hardness becomes high and the machinability deteriorates. The microstructure according to the type of Ti is shown in FIG. That is, Fig. 2 shows the microstructures of two steel types with almost the same D I value with and without Ti after hot forging to 30 mmφ. The microstructure of Ti-added steel is ferrite / pearlite, and the microstructure of Ti-free steel is It is known that ferrite and bainite become fine-grained by the addition of Ti and the hardenability deteriorates, making it difficult to form bainite.
更にAlとＮの添加量を種々変えた鋼を溶製し、1200℃
に加熱し、30mmφに鍛伸し、その後、920℃で５時間の
浸炭を行い、旧オーステナイト粒を観察した。第３図に
は粗大粒（粒度No.5以下）発生の有無を示すが、この第
３図より、粗大化防止に、Ｎ＊は0.01％以上必要であ
り、またAl/N＊:1.5〜2.8となる必要があることが知ら
れる。Furthermore, the steel with various addition amounts of Al and N was melted, and the temperature was 1200 ℃.
Then, it was forged to 30 mmφ and then carburized at 920 ° C. for 5 hours to observe old austenite grains. Fig. 3 shows the presence or absence of coarse particles (grain size No. 5 or less). From this Fig. 3, N * must be 0.01% or more to prevent coarsening, and Al / N * : 1.5- It is known that it needs to be 2.8.
本発明によるものの具体的な製造例について説明する
と以下の如くである。A concrete production example of the device according to the present invention is as follows.
本発明者等は次の第１表に示すような化学成分を有す
る鋼を溶製し、1200℃に加熱し、30mmφに鍛伸した。The present inventors melted steel having the chemical composition shown in Table 1 below, heated it to 1200 ° C., and forged it to 30 mmφ.
上記のようにして得られたものは、その後硬さ、被削
性、漬炭粒度、ジョミニー焼入性試験を行った。即ち硬
さは、ブリネル硬度計を用い測定し、被削性は、ハイス
（SKH51）チップを用い、切削速度120m/min、切込み2m
m、送り0.1mm/revで旋削にて工具寿命を測定した。又浸
炭粒度は、850〜1100℃の間を25℃間隔で５時間保持
後、焼入れて、旧オーステナイト粒を測定し、粒度No.5
以下の粗大粒が発生する温度を粗大化温度とした。更に
ジョミニー焼入性試験は、JIS G0561に基づいて行っ
た。このような試験測定の結果は次の第２表の如くであ
る。 The thus obtained material was then tested for hardness, machinability, grain size of the pickled coal, and Jominy hardenability test. That is, the hardness is measured using a Brinell hardness tester, and the machinability is a high speed (SKH51) tip, cutting speed 120 m / min, depth of cut 2 m
Tool life was measured by turning at m and feed of 0.1 mm / rev. For the carburizing particle size, hold the temperature between 850 and 1100 ℃ at 25 ℃ intervals for 5 hours, quench, and measure old austenite particles.
The temperature at which the following coarse particles are generated was defined as the coarsening temperature. Furthermore, the Jominy hardenability test was conducted based on JIS G 0561. The results of such test measurements are shown in Table 2 below.
即ち、このような第２表の結果によるならば、本発明
に従って本発明鋼１〜３は、熱間鍛造ままで、被削性が
良好であるとともに、浸炭時の結晶粒粗大化温度も高
い。これに対し比較鋼１は、Ti無添加でDI値が高いこと
もあり、鍛造後の硬さが高く、被削性が悪い。比較鋼２
は鍛造後の被削性は良いものの、DI値が低く、浸炭後の
強度が得られない。又比較鋼３は、Tiの添加量が多過ぎ
ることと、Al/N＊が2.8以上のため、被削性が劣り、浸
炭後の結晶粒粗大化温度が低い。然して比較鋼４は、Al
/N＊が1.6以下のため、浸炭後の結晶粒粗大化温度が低
い。更に比較鋼５はＳ量が低いため、被削性が劣る。比
較鋼６は、通常のSCM420で焼ならしを行ったものであ
り、これは被削性が良好であるが、鍛造ままでは、硬さ
が高くなり過ぎて、被削性が劣る。 That is, according to the results of Table 2, the steels 1 to 3 of the present invention according to the present invention have good machinability in the as-hot-forged state and have a high crystal grain coarsening temperature during carburization. . On the other hand, Comparative Steel 1 has a high D I value without Ti addition, has a high hardness after forging, and has poor machinability. Comparative steel 2
Has good machinability after forging, but has a low D I value and cannot obtain strength after carburization. Further, in Comparative Steel 3, since the amount of Ti added was too large and the Al / N * was 2.8 or more, the machinability was poor and the crystal grain coarsening temperature after carburization was low. However, Comparative Steel 4 is Al
Since / N * is 1.6 or less, the crystal grain coarsening temperature after carburization is low. Further, Comparative Steel 5 has a low S content, and therefore has poor machinability. Comparative Steel 6 was normalized with normal SCM420, and has good machinability, but if it is forged, the hardness becomes too high and the machinability deteriorates.
「発明の効果」 以上説明したような本発明によるときは熱間鍛造後に
焼ならしを行わなくても被削性を劣化することがなく、
又浸炭後も結晶粒粗大化を生じ難いので製造上における
省工程、省エネルギーを充分にもたらし、更に浸炭時の
歪みも小さくなり、低コストに好ましい肌焼鋼を提供し
得るものであるから工業的にその効果の大きい発明であ
る。"Effects of the Invention" In the case of the present invention as described above, machinability is not deteriorated without normalizing after hot forging.
In addition, since it is difficult to cause crystal grain coarsening even after carburization, it can bring about sufficient process saving and energy saving in manufacturing, and further, distortion during carburizing becomes small, and it is possible to provide a preferable case hardening steel at low cost industrially. It is an invention that has a great effect.
図面は本発明の技術的内容を示すものであって、第１図
はDI値と硬さ及び工具寿命の関係を示した図表、第２図
はTiの有無による顕微鏡金属組織を比較して示した写真
で（Ａ）はTi添加なし、（Ｂ）は添加ありの場合を示
し、第３図は有効窒素およびsol.Alと粗大粒の発生状態
を要約して示した図表である。The drawings show the technical contents of the present invention. FIG. 1 is a table showing the relationship between D I value and hardness and tool life, and FIG. 2 is a comparison of microscopic metallographic structures with and without Ti. In the photograph shown, (A) shows the case where Ti is not added and (B) shows the case where Ti is added, and FIG. 3 is a chart summarizing the generation state of effective nitrogen and sol.Al and coarse particles.
Claims (1)
を特徴とした肌焼鋼。1. C: 0.15-0.35 wt%, Si: 0.5 wt% or less, Mn: 1.5 wt% or less, Cr: 1.5 wt% or less, Mo: 0.25 wt% or less, S: 0.03-0.05 wt%, Ti : 0.005-0.015wt%, Al / N * : 1.5 to 2.8 D I : 85-90mm A case-hardening steel containing, and the balance consisting of Fe and inevitable impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2217125A JP2546045B2 (en) | 1990-08-20 | 1990-08-20 | Case hardening steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2217125A JP2546045B2 (en) | 1990-08-20 | 1990-08-20 | Case hardening steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0499843A JPH0499843A (en) | 1992-03-31 |
| JP2546045B2 true JP2546045B2 (en) | 1996-10-23 |
Family
ID=16699246
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2217125A Expired - Fee Related JP2546045B2 (en) | 1990-08-20 | 1990-08-20 | Case hardening steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2546045B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101967606A (en) * | 2010-11-02 | 2011-02-09 | 武汉钢铁(集团)公司 | Hot rolled steel strip for straight slit electric resistance welding petroleum casing pipe and production method thereof |
| CN104789878B (en) * | 2015-05-05 | 2017-03-15 | 内蒙古包钢钢联股份有限公司 | A kind of high-hardenability oil casing collar material seamless steel pipe and preparation method |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5719324A (en) * | 1980-05-30 | 1982-02-01 | Nippon Steel Corp | Production of steel for machine structural use for forging having fine structure at high temperature |
| JPS6247425A (en) * | 1985-08-23 | 1987-03-02 | Sumitomo Metal Ind Ltd | Manufacture of face hardened steel |
| JPS634042A (en) * | 1986-06-24 | 1988-01-09 | Daido Steel Co Ltd | Case hardening steel for cold and warm forging |
| JP2595609B2 (en) * | 1988-01-26 | 1997-04-02 | 大同特殊鋼株式会社 | Free cutting steel for carburizing and quenching |
-
1990
- 1990-08-20 JP JP2217125A patent/JP2546045B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0499843A (en) | 1992-03-31 |
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