JPH0557351B2 - - Google Patents
Info
- Publication number
- JPH0557351B2 JPH0557351B2 JP15112386A JP15112386A JPH0557351B2 JP H0557351 B2 JPH0557351 B2 JP H0557351B2 JP 15112386 A JP15112386 A JP 15112386A JP 15112386 A JP15112386 A JP 15112386A JP H0557351 B2 JPH0557351 B2 JP H0557351B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- steel
- toughness
- hot working
- crystal grains
- 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
Links
- 229910000746 Structural steel Inorganic materials 0.000 claims description 7
- 239000013078 crystal Substances 0.000 claims description 7
- 229910001566 austenite Inorganic materials 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 5
- 229910052720 vanadium Inorganic materials 0.000 claims description 5
- 229910000851 Alloy steel Inorganic materials 0.000 claims description 3
- 229910001562 pearlite Inorganic materials 0.000 claims description 3
- 229910000859 α-Fe Inorganic materials 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 description 16
- 239000010959 steel Substances 0.000 description 16
- 239000000463 material Substances 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 229910052758 niobium Inorganic materials 0.000 description 5
- 238000012545 processing Methods 0.000 description 4
- 238000005496 tempering Methods 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Description
発明の目的 purpose of invention
本発明は、非調質で、すなわち熱間加工のまま
焼入れ−焼戻しなどの調質処理を行なわずに、す
ぐれた靱性を有する構造用鋼に関する。
The present invention relates to structural steel that has excellent toughness without heat treatment, that is, without undergoing heat treatment such as quenching and tempering while hot working.
一般に構造用鋼からの製品の製造は、熱間加工
ののち調質をしてから切削加工を施すことによつ
て行なわれているが、調質を行なわないで済めば
コストの低下がはかれるとともに、省エネルギー
の要請にこたえることもできる。
そこでこのような鋼の研究がさかんに試みられ
ており、とくに、ＶやNbなどを添加した鋼を熱
間加工後に冷却する過程でこれらの炭化物や窒化
物がフエライト＋パーライト組織中に析出するこ
とを利用して強化する鋼が開発され、一部実用化
されている。熱間加工として圧延を行なつた場合
は、圧延のままで強化した鋼材をそのまま、ある
いは冷間または温間で塑性加工してから切削して
最終製品とする。また、鍛造を行なう場合は、圧
延した鋼材を型打鍛造し、硬化した粗材を切削し
て製品とする。
しかしこのようにして得た製品は、通常の調質
処理をへたものにくらべて、その靱性が低いとい
う弱点がある。
Generally, products are manufactured from structural steel by hot working, tempering, and cutting, but if heat refining can be omitted, costs can be reduced and , it can also meet the demand for energy conservation. Therefore, research on such steels has been actively attempted, and in particular, it has been found that these carbides and nitrides precipitate in the ferrite + pearlite structure during the cooling process after hot working of steels to which V and Nb have been added. Steels that are strengthened using the When rolling is performed as hot working, the steel material is strengthened as it is, or is subjected to cold or warm plastic working and then cutting to form the final product. In addition, when forging is performed, the rolled steel material is die-forged, and the hardened rough material is cut into a product. However, the product obtained in this way has a disadvantage in that its toughness is lower than that of products that undergo ordinary heat treatment.
本発明の目的は、この弱点を克服し、調質鋼に
くらべてそん色のない非調質構造用鋼を提供する
ことにある。
発明の構成
An object of the present invention is to overcome this weakness and provide a non-tempered structural steel that is comparable in color to tempered steel. Composition of the invention
熱間加工のままですぐれた靱性を有する本発明
の非調質構造用鋼は、Ｃ：0.30〜0.60％、Si：
0.10〜2.0％、Mn：0.20〜2.5％、Al：0.005〜0.10
％およびＮ：0.005〜0.030％、ならびに、Ｖ：0.5
％以下およびNb：0.5％以下のいづれか１種また
は２種を含有し、さらに、Ｓ：0.40％以下および
Te：0.10％以下をTe／Ｓ：0.04以上の割合で含
有し、残余が実質的にFeからなる鋼合金を熱間
加工してなり、常温まで冷却した後の組織が、平
均結晶粒度番号５以上の旧オーステナイト結晶粒
を有することを特徴とする。
The non-thermal structural steel of the present invention, which has excellent toughness even after hot working, contains C: 0.30 to 0.60%, Si:
0.10~2.0%, Mn: 0.20~2.5%, Al: 0.005~0.10
% and N: 0.005-0.030%, and V: 0.5
% or less and Nb: 0.5% or less, and further contains S: 0.40% or less and
A steel alloy containing Te: 0.10% or less at a Te/S: 0.04 or more ratio, the remainder being substantially Fe, is hot worked, and the structure after cooling to room temperature has an average grain size number of 5. It is characterized by having the above prior austenite crystal grains.
本発明で採用した合金組成における各成分の役
割と、その限定の理由は、つぎのとおりである。
Ｃ：0.30〜0.60％
必要な強度を確保するため、0.30％以上の存在
が必須である。上限は靱性の観点から定めた。
Si：0.10〜2.0％、好ましくは0.15〜1.0％
Siは脱酸剤として必要な元素であり、0.10％以
上含有させるが、非調質構造用鋼は、熱間加工
後、機械加工により製品とするのがふつうであ
り、被削性が良好であることが望まれる。従つ
て、Siは2.0％以下、好ましくは1.0％までに止め
るべきである。
Mn：0.20〜2.5％、好ましくは0.5〜1.8％
いうまでもなくMnも脱酸剤として作用する
が、非調質鋼においては高い靱性を得る上で重要
である。本発明においても、比較的高含有量、代
表的には1.5％内外を採用する。ただし被削性の
点からは、あまり多量に加えることは避けたい。
Al：0.005〜0.10％、好ましくは0.01〜0.05％
脱酸作用もあるが、主な役割は結晶粒の微細化
である。Alもまた被削性に関してはマイナスに
はたらくので、0.10％以下に限定する。
Ｎ：0.005〜0.30％、好ましくは0.23％までＮの効
果は、ひとつは結晶粒の微細化であり、いまひと
つはＶまたはNbとの窒化物形成による析出強化
である。これも多量にすぎると靱性を損う。
Ｖ：0.5％以下、Nb：0.5％以下（併用の場合は合
計で0.5％以下）
どちらも窒化物を形成し、析出強化および結晶
粒の微細化に寄与する。ただし、鋼材の加工条件
に対してはNbの影響が大きく、高含有量の方が
適切な加工温度の上限が拡がる。上限は熱間加工
性の低下を理由に設けたが、ＶもNbも高価な材
料であるから、添加効果と経済性との調和におい
て添加量を定めればよい。
本発明の鋼の最大の特徴は、前記した旧オース
テナイト結晶粒の大きさが平均結晶粒度番号５以
上であるという特異な組織にある。いうまでもな
く、「旧オーステナイト」結晶粒とは、熱間加工
後常温まで冷却されて生成したフエライト−パー
ライト系の組織のフエライト粒が、高温の状態で
は存在していたオーステナイト結晶粒界をくまど
るように存在し、以然の結晶粒の大きさを示すも
のを意味する。この測定は、JIS Ｇ 0551に定め
る徐冷法に従つて行なう。従来の非調質鋼の組織
が、一般に結晶粒度番号２〜３であることを考慮
すると、本発明でえらんだ組織は、きわめて特異
なものである。
ＳおよびTeは、鋼の靱性の方向性を低くする
ために添加する。Ｓはもちろん被削性の改善に役
立つ元素であるが、ここではむしろ、適量のＳと
Teとの組み合わせにより、鋼中の硫化物系介在
物の形態をコントロールし、靱性の異方性を軽減
する効果が得られるのである。ＳおよびTeの上
限値は、主として熱間加工性にもとづいて定め
た。
上述のような、熱間加工のままで高い靱性を有
する構造用鋼を得るには、前記の組成の鋼合金を
熱間加工して冷却する際の加工条件を、所定の結
晶粒度番号になるようえらばなければならない。
その条件は、えらんだ組成によつて異なるが、最
も支配的な因子はＮおよびNbの含有量である。
いま、これらの含有量の大小に応じて、良好な
結果を与える熱間加工の加熱温度および仕上げ温
度の上限界を示せば、次のとおりである。
The role of each component in the alloy composition adopted in the present invention and the reason for its limitation are as follows. C: 0.30-0.60% In order to ensure the necessary strength, the presence of 0.30% or more is essential. The upper limit was determined from the viewpoint of toughness. Si: 0.10 to 2.0%, preferably 0.15 to 1.0% Si is a necessary element as a deoxidizing agent, and should be contained at 0.10% or more. It is normal to do so, and good machinability is desired. Therefore, Si should be kept at 2.0% or less, preferably 1.0% or less. Mn: 0.20 to 2.5%, preferably 0.5 to 1.8% Needless to say, Mn also acts as a deoxidizing agent, which is important in obtaining high toughness in non-tempered steel. In the present invention, a relatively high content, typically around 1.5%, is used. However, from the viewpoint of machinability, it is best to avoid adding too much. Al: 0.005 to 0.10%, preferably 0.01 to 0.05% Although it also has a deoxidizing effect, its main role is to refine crystal grains. Al also has a negative effect on machinability, so it is limited to 0.10% or less. N: 0.005 to 0.30%, preferably 0.23% One of the effects of N is grain refinement, and the other is precipitation strengthening due to the formation of nitrides with V or Nb. Too much of this also impairs toughness. V: 0.5% or less, Nb: 0.5% or less (total 0.5% or less if used together) Both form nitrides and contribute to precipitation strengthening and crystal grain refinement. However, Nb has a large influence on the processing conditions of steel materials, and the higher the content, the wider the upper limit of the appropriate processing temperature. The upper limit was set for the reason of deterioration in hot workability, but since both V and Nb are expensive materials, the amount added should be determined in harmony with the effect of addition and economical efficiency. The greatest feature of the steel of the present invention is its unique structure in which the size of the prior austenite crystal grains is an average grain size number of 5 or more. Needless to say, "prior austenite" grains are ferrite grains with a ferrite-pearlite structure that are generated when cooled to room temperature after hot working and cross the austenite grain boundaries that existed at high temperatures. It indicates how the crystal grains exist and the size of the crystal grains. This measurement is performed according to the slow cooling method specified in JIS G 0551. Considering that the structure of conventional non-tempered steel generally has a grain size number of 2 to 3, the structure selected in the present invention is extremely unique. S and Te are added to lower the toughness of the steel. Of course, S is an element that helps improve machinability, but here we will focus on an appropriate amount of S.
In combination with Te, it is possible to control the morphology of sulfide inclusions in steel and reduce toughness anisotropy. The upper limits of S and Te were determined mainly based on hot workability. In order to obtain a structural steel with high toughness as described above even after hot working, the processing conditions during hot working and cooling of the steel alloy with the above composition should be adjusted to a predetermined grain size number. I have to choose.
The conditions vary depending on the composition chosen, but the most dominant factors are the N and Nb contents. Now, depending on the magnitude of these contents, the upper limits of the heating temperature and finishing temperature for hot working that give good results are as follows.
【表】
実際の操業条件は、上記限界内で、温度が高い
ほど塑性加工に対する抵抗が低いが、得られる鋼
材の靱性に関する限りは比較的低温が好ましい。
これもまた、両者のバランスをはかつて、それ
ぞれの場合に応じて選択すべきことになる。[Table] The actual operating conditions are within the above limits, and the higher the temperature, the lower the resistance to plastic working, but relatively low temperatures are preferred as far as the toughness of the resulting steel is concerned. Again, the balance between the two must be selected depending on each case.
第１表に示す合金組成の鋼を2tonアーク炉で溶
解し鋳造した。（No.Ｆは*は比較鋼）
Steel having the alloy composition shown in Table 1 was melted and cast in a 2 ton arc furnace. (No.F is * for comparison steel)
【表】
インゴツトを圧延して100mm角のビレツトをつ
くり、加熱温度と仕上げ温度とを下に示す条件に
設定して鍛造し、断面20mm×60mmの素材とした。
比較材は、鍛造後さらに、850度・油冷−600℃・
空冷の条件で焼入れ−焼戻し処理をした。[Table] An ingot was rolled to make a 100 mm square billet, and the heating temperature and finishing temperature were set to the conditions shown below for forging, resulting in a material with a cross section of 20 mm x 60 mm.
Comparison materials were further forged at 850 degrees, oil cooled at -600 degrees Celsius,
Quenching and tempering were performed under air cooling conditions.
【表】
上記のようにして得た素材について、種々試験
した結果を第２表に示す。表中、番号に＊印を付
したものは比較例である。「−」は未測定を意味
する。
シヤルピー衝撃値はJIS3号試験片を用い、室温
で測定したものである。
第２表のデータから、本発明の合金、とくに好
ましい処理条件で加工したものが、所定の大きさ
の旧オーステナイト結晶粒度をもつこと、そして
その条件をみたした鋼材が、硬さ、靱性および靱
性の方向性に関して、調質を行なつた在来品にそ
ん色のない値を示すことがわかり、さらに、適量
のＳおよびTeを含有する場合には靱性の方向性
が著しく改善されることが裏付けられる。[Table] Table 2 shows the results of various tests performed on the materials obtained as described above. In the table, the numbers marked with * are comparative examples. "-" means not measured. The Charpy impact value was measured at room temperature using a JIS No. 3 test piece. From the data in Table 2, it is clear that the alloy of the present invention, particularly that processed under favorable processing conditions, has a prior austenite grain size of a predetermined size, and that steel materials that meet the conditions have good hardness, toughness, and toughness. Regarding the directionality of toughness, it was found that the value was comparable to that of conventional products that underwent thermal refining, and furthermore, when appropriate amounts of S and Te were contained, the directionality of toughness was significantly improved. It is supported.
【表】
発明の効果
本発明によれば、産業機械や自動車などの製造
に広く使われている構造用鋼において、熱間加工
のままで高い強度と靱性をもつた鋼が得られる。
従つて、これまで焼入れ、焼戻しの調質処理を必
要としていた各種機械部品、たとえばクランクシ
ヤフト、コネクテイングロツド、アクスルシヤフ
ト、スピンドル、ステアリングラツクなどの製造
に当つて、熱処理工程を省略することができ、生
産性は大いに高まる。この利益は大量生産品にお
いて一層顕著である。[Table] Effects of the Invention According to the present invention, it is possible to obtain structural steel that has high strength and toughness even after hot working, which is widely used in the manufacture of industrial machinery and automobiles.
Therefore, it is now possible to omit the heat treatment process when manufacturing various mechanical parts that previously required heat treatment such as quenching and tempering, such as crankshafts, connecting rods, axle shafts, spindles, and steering racks. This will greatly increase productivity. This benefit is even more pronounced for mass-produced products.
Claims (1)
0.20〜2.5％、Al：0.005〜0.10％およびＮ：0.005
〜0.030％、ならびにＶ：0.5％以下およびNb：
0.5％以下のいづれか１種または２種を含有し、
さらに、Ｓ：0.40％以下およびTe：0.10％以下を
Te／Ｓ：0.04以上の割合で含有し、残余が実質
的にFeからなる鋼合金を熱間加工してなり、常
温まで冷却した後の組織がフエライト＋パーライ
トであつて、平均結晶粒度番号５以上の旧オース
テナイト結晶粒を有することを特徴とする非調質
構造用鋼。1 C: 0.30-0.60%, Si: 0.10-2.0%, Mn:
0.20~2.5%, Al: 0.005~0.10% and N: 0.005
~0.030%, and V: 0.5% or less and Nb:
Contains 0.5% or less of any one or two types,
Furthermore, S: 0.40% or less and Te: 0.10% or less
It is made by hot working a steel alloy that contains Te/S at a ratio of 0.04 or more and the remainder is substantially Fe, and the structure after cooling to room temperature is ferrite + pearlite, and the average grain size is 5. A non-tempered structural steel characterized by having prior austenite crystal grains of or above.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15112386A JPS6296653A (en) | 1981-10-20 | 1986-06-27 | Non-tempered structural steel |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16775081A JPS5871354A (en) | 1981-10-20 | 1981-10-20 | Non-tempered structural steel and its manufacturing method |
| JP15112386A JPS6296653A (en) | 1981-10-20 | 1986-06-27 | Non-tempered structural steel |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16775081A Division JPS5871354A (en) | 1981-10-20 | 1981-10-20 | Non-tempered structural steel and its manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6296653A JPS6296653A (en) | 1987-05-06 |
| JPH0557351B2 true JPH0557351B2 (en) | 1993-08-23 |
Family
ID=15855402
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16775081A Pending JPS5871354A (en) | 1981-10-20 | 1981-10-20 | Non-tempered structural steel and its manufacturing method |
| JP15112386A Granted JPS6296653A (en) | 1981-10-20 | 1986-06-27 | Non-tempered structural steel |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16775081A Pending JPS5871354A (en) | 1981-10-20 | 1981-10-20 | Non-tempered structural steel and its manufacturing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (2) | JPS5871354A (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4895700A (en) * | 1988-03-10 | 1990-01-23 | Dana Corporation | Low grade material axle shaft |
| JPH01290751A (en) * | 1988-05-19 | 1989-11-22 | Topy Ind Ltd | High-strength non-heattreated steel bar |
| JPH0796695B2 (en) * | 1988-08-10 | 1995-10-18 | 新日本製鐵株式会社 | Medium carbon tough steel |
| JP2669178B2 (en) * | 1991-05-08 | 1997-10-27 | 住友金属工業株式会社 | High toughness and high strength seamless steel pipe |
| CN1039835C (en) * | 1995-07-20 | 1998-09-16 | 张玉田 | Non-quenched and tempered alloy structural steel and its manufacturing process |
| JP5233848B2 (en) * | 2009-06-08 | 2013-07-10 | 新日鐵住金株式会社 | Non-tempered steel bar for direct cutting |
| CN104032214B (en) * | 2013-09-26 | 2015-12-09 | 北大方正集团有限公司 | A kind of non-hardened and tempered steel and production technique thereof |
| JP7009938B2 (en) * | 2017-11-07 | 2022-01-26 | 日産自動車株式会社 | Axle shaft |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4923124A (en) * | 1972-06-23 | 1974-03-01 | ||
| JPS5921369B2 (en) * | 1976-10-25 | 1984-05-19 | 新日本製鐵株式会社 | Manufacturing method for high-tensile, high-carbon steel wire with excellent wire drawability |
| JPS5853708B2 (en) * | 1979-03-15 | 1983-11-30 | 住友金属工業株式会社 | Welded steel pipe with excellent butt toughness |
-
1981
- 1981-10-20 JP JP16775081A patent/JPS5871354A/en active Pending
-
1986
- 1986-06-27 JP JP15112386A patent/JPS6296653A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0140901B1 (en) | 1989-09-01 |
| JPS6296653A (en) | 1987-05-06 |
| JPS5871354A (en) | 1983-04-28 |
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