JPS6323261B2 - - Google Patents
Info
- Publication number
- JPS6323261B2 JPS6323261B2 JP54111731A JP11173179A JPS6323261B2 JP S6323261 B2 JPS6323261 B2 JP S6323261B2 JP 54111731 A JP54111731 A JP 54111731A JP 11173179 A JP11173179 A JP 11173179A JP S6323261 B2 JPS6323261 B2 JP S6323261B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- toughness
- steels
- present
- strength
- 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
- 229910000831 Steel Inorganic materials 0.000 claims description 54
- 239000010959 steel Substances 0.000 claims description 54
- 229910052758 niobium Inorganic materials 0.000 claims description 10
- 229910052719 titanium Inorganic materials 0.000 claims description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 239000002436 steel type Substances 0.000 description 9
- 229910052720 vanadium Inorganic materials 0.000 description 8
- 230000000694 effects Effects 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 4
- 229910000975 Carbon steel Inorganic materials 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000007669 thermal treatment Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
Description
本発明は、調質することなく、十分な強度と靭
性を有する機械構造用強靭鋼にかかわるものであ
る。
従来、機械構造用強靭鋼は、主として調質、す
なわち、焼入焼戻しをして使用されている。鋼の
調質処理は、その鋼の強度と靭性との兼ね合いを
最高度に引き出すための手段として、広く活用さ
れてきた。しかし、石油危機が叫ばれる昨今、調
質処理のための熱エネルギーのコスト高によつ
て、調質鋼に代替出来る鋼が必要になつて来る。
一般に、鋼の靭性を無視して、強度のみ高くす
ることは、非調質であつても、比較的容易である
けれども、このような鋼は、用途が限定され、従
来の調質鋼に代替出来るものではない。
鋼の調質処理は、組識を微細化すること、特に
セメンタイトを微細分散させることによつて、鋼
に強靭性を附与するものである。そこで本発明者
らは、このような手段に代えて、Si，Mnさらに
はCr，Niを多くすることによる地鉄の強化と、
Ti，Ｖ，Nbによる析出強化による鋼の高強度化
をはかるとともに、Ti，Ｖ，Nbによつて、組識
を微細化し、鋼の高靭化をはかることについて検
討した。
中炭、高炭素鋼にTi，Ｖ，Nbを添加すると、
鋼は強化される。しかし、この種の鋼において
は、その効果にも増して、靭性が害される。特に
Tiにおいて、その傾向が著しい。これは分析等
より、種々検討したところ、低炭素鋼に比較し
て、中炭、高炭素鋼では、鋼中の炭素ポテンシヤ
ルが高く、Ti，Ｖ，Nbが炭化物主体の析出物に
なることに原因することがわかつた。
そこで、鋼中のＮを多くして、Ti，Ｖ，Nbの
析出物を窒化物主体のものにすることを試みた。
その結果、靭性が著しく向上することを見出し
た。この場合、鋼中のＮ量は、少なくとも析出物
TiNのTiに見合うＮ量以上、すなわち、0.29Ti
％以上が必要である。
さらに、Ｃ：0.45％，Si：0.25％，Mn：1.0％，
Ｖ：0.05％を基本成分とする鋼において、Ti，Ｎ
の量を種々変化させて、それらの適力を検討し
た。その結果、Ti：0.01〜0.05％のもので、Ｎ／
0.29Tiと60mmφ鍛造材の20℃におけるJIS3号試験
片の吸収エネルギー、uE20との関係を第１図に
示したが、この図からわかるように、Ｎ：0.29Ti
％超で靭性が著しく向上することが明らかであ
る。
本発明は、このような知見に基いて、なされた
ものであつて、熱間圧延あるいは熱間鍛造の
まゝ、また、場合によつては焼ならしのみで、調
質することなく、従来の調質強靭鋼に匹敵する強
度と靭性とを兼ねそなえた鋼である。
すなわち、本発明の要旨とするところは、Ｃ：
0.3〜0.8％，Si：0.15〜1.5％，Mn：0.5〜２％，
Ti：0.01〜0.05％，Ｎ：0.29Ti〜0.025％，さらに
Ｖ：0.01〜0.1％，Nb：0.01〜0.1％の１種または
２種を含有し、または、これらに、さらに、
Cr：２％以下，Ni：２％以下の１種または２種
以上を含み、残部が鉄および不純物からなること
を特徴とする非調質強靭鋼にある。
次に、本発明のこれら成分の限定理由について
述べる。
Ｃは、強度を得るために、0.3％以上を必要と
するが、1.8％超になると、初析セメンタイトが
生じ、靭性が害される。
Siは、脱酸剤として製鋼上必要な元素であると
ともに、強度を得るためにも、有効な元素であ
る。これらのためには、0.15％以上必要とする
が、1.5％超では靭性が劣化する。Mnは、Siと同
じく、脱酸剤、強度を確保するために0.5％以上
必要である。しかし、２％超になると、強度が高
くなりすぎ、靭性が劣化する。
Tiは、鋼中に窒化物主体の析出物を形成せし
め、析出強化とともに組識を微細化し、靭性を向
上させるものである。これらのために、0.01％未
満では効果が小さく、0.01％以上必要とするが、
0.05％超になると、靭性がかえつて劣化する。
Ｖ，Nbは、いずれも、Tiの効果を補足するも
のであつて、0.01％以上を必要とするが、0.1％
超では靭性が劣化する。
Ｎは、鋼中に、Ti，Ｖ，Nbの窒化物主体の析
出物を形成せしめるに必要であつて、第１図に示
したごとく、0.29Ti％未満では、靭性が低い。即
ち鋼の靭性向上のためには、0.29Ti％以上を必要
とする。しかし、0.025％超では靭性がかえつて
劣化する。
さらに、強靭性を必要とする場合、上記成分に
加え、Cr：２％以下、Ni：２％以下を１種また
は２種以上添加する。Crは、２％超になると、
靭性を害する。Niは、鋼を強靭にするに有用な
元素であるが、２％超になると、それらの効果が
飽和する。
なお、本発明鋼は、強靭性を附与するために清
浄度をよくすることが望ましく、そのために、製
造に際して溶鋼段階でAl，Ca，Mg，REM等お
よびこれらの合金により、十分なる脱酸を行なう
ものであるが、これら元素および化合物は、本発
明鋼においては不純物として残存する程度であ
る。
以下、実施例について、本発明の効果を、さら
に、具体的に述べる。
第１表に示す化学成分からなる鋼、すなわち、
鋼１〜３は、市販されている従来の調質鋼の代表
The present invention relates to a strong steel for mechanical structures that has sufficient strength and toughness without being tempered. BACKGROUND ART Conventionally, strong steel for machine structures has been mainly used after being tempered, that is, quenched and tempered. Thermal treatment of steel has been widely used as a means to maximize the balance between strength and toughness of the steel. However, in these days of the oil crisis, the high cost of thermal energy for heat treatment has created a need for steel that can replace heat treated steel. In general, it is relatively easy to ignore the toughness of steel and only increase its strength, even if it is not heat-treated, but such steel has limited uses and cannot be used as an alternative to conventional heat-treated steel. It's not possible. Thermal treatment of steel imparts toughness to steel by refining the structure, particularly by finely dispersing cementite. Therefore, instead of such means, the present inventors strengthened the base steel by increasing Si, Mn, and even Cr and Ni.
In addition to increasing the strength of steel by precipitation strengthening with Ti, V, and Nb, we also investigated the use of Ti, V, and Nb to refine the structure and increase the toughness of steel. When Ti, V, and Nb are added to medium-carbon and high-carbon steels,
Steel is strengthened. However, in addition to this effect, the toughness of this type of steel is impaired. especially
This tendency is remarkable in Ti. This is because, after various studies such as analysis, the carbon potential in the steel is higher in medium- and high-carbon steels than in low-carbon steels, and Ti, V, and Nb become precipitates mainly composed of carbides. I found out what caused it. Therefore, an attempt was made to increase the amount of N in the steel so that the Ti, V, and Nb precipitates were mainly nitrides.
As a result, it was found that the toughness was significantly improved. In this case, the amount of N in the steel is at least
More than the amount of N corresponding to the Ti of TiN, i.e. 0.29Ti
% or more is required. Furthermore, C: 0.45%, Si: 0.25%, Mn: 1.0%,
In steel with V: 0.05% as a basic component, Ti, N
The suitability of these was examined by varying the amount of As a result, with Ti: 0.01 to 0.05%, N/
Figure 1 shows the relationship between the absorbed energy and uE20 of JIS No. 3 test pieces of 0.29Ti and 60mmφ forged materials at 20℃.As can be seen from this figure, N: 0.29Ti
%, it is clear that the toughness is significantly improved. The present invention has been made based on such knowledge, and it is possible to use hot rolling or hot forging as it is, or in some cases, just normalizing without heat refining. It is a steel with strength and toughness comparable to that of tempered tough steel. That is, the gist of the present invention is C:
0.3-0.8%, Si: 0.15-1.5%, Mn: 0.5-2%,
Contains one or two of Ti: 0.01 to 0.05%, N: 0.29Ti to 0.025%, V: 0.01 to 0.1%, and Nb: 0.01 to 0.1%, or in addition to these,
It is a non-tempered tough steel characterized by containing one or more of Cr: 2% or less and Ni: 2% or less, with the balance consisting of iron and impurities. Next, the reasons for limiting these components of the present invention will be described. C needs to be present in an amount of 0.3% or more in order to obtain strength, but if it exceeds 1.8%, pro-eutectoid cementite will occur and toughness will be impaired. Si is an element necessary for steel manufacturing as a deoxidizing agent, and is also an effective element for obtaining strength. For these purposes, 0.15% or more is required, but if it exceeds 1.5%, the toughness deteriorates. Like Si, Mn is a deoxidizing agent and requires 0.5% or more to ensure strength. However, when it exceeds 2%, the strength becomes too high and the toughness deteriorates. Ti forms nitride-based precipitates in the steel, strengthens the steel by precipitation, refines the structure, and improves toughness. For these reasons, less than 0.01% has little effect, and 0.01% or more is required.
If it exceeds 0.05%, the toughness will actually deteriorate. Both V and Nb supplement the effect of Ti and require 0.01% or more, but 0.1%
If it is too thick, the toughness will deteriorate. N is necessary to form precipitates consisting mainly of nitrides of Ti, V, and Nb in the steel, and as shown in FIG. 1, if the content is less than 0.29 Ti%, the toughness is low. That is, in order to improve the toughness of steel, 0.29% or more of Ti is required. However, if it exceeds 0.025%, the toughness will deteriorate. Furthermore, if toughness is required, one or more of Cr: 2% or less and Ni: 2% or less are added in addition to the above components. When Cr exceeds 2%,
Damages toughness. Ni is a useful element for making steel tough, but its effects become saturated when it exceeds 2%. It is desirable that the steel of the present invention has good cleanliness in order to impart toughness, and for this purpose, it is sufficiently deoxidized with Al, Ca, Mg, REM, etc. and alloys thereof at the molten steel stage during manufacturing. However, these elements and compounds only remain as impurities in the steel of the present invention. Hereinafter, the effects of the present invention will be described in more detail with reference to Examples. Steel consisting of the chemical components shown in Table 1, i.e.
Steels 1 to 3 are representative of conventional tempered steels on the market.
【表】【table】
【表】
○印の鋼は本発明鋼。
であり、鋼種４〜11は、試作鋼で、これらのう
ち、鋼種４〜６は比較鋼であり、鋼７〜11は本発
明鋼である。
鋼種１〜３の市販鋼は、50mmφ×200mm（ただ
し鋼種１は30mmφ×200mm）素材を850℃−２時間
加熱後、油冷し、600℃−２時間焼戻したものに
ついて試験した。
鋼種４〜11の試作鋼は、100Kg鋼塊を溶製し、
50mmφに鍛造したまゝのもの、鋼種10のみ、鍛造
後、800℃−２時間焼ならしたものについて試験
した。その結果を第２表に示した。
同表からわかるように、鋼種１〜３と本発明鋼
の鋼種７〜12を比較して、本発明鋼は従来の調質
強度鋼と遜色ないものであるといえる。
しかし、鋼４〜６の比較鋼の結果をみると、こ
れらの鋼種は、靭性が劣ることが明らかである。
以上、述べたところより明らかなごとく、本発
明鋼は、調質することなく、従来の調質強靭鋼に
匹敵する性質を有するものであつて、今後の省エ
ネルギーに対応するものである。[Table] Steels marked with ○ are steels of the present invention.
Steel types 4 to 11 are trial steels, among which steel types 4 to 6 are comparative steels, and steels 7 to 11 are steels of the present invention. Commercially available steels of steel types 1 to 3 were tested by heating a 50 mmφ x 200 mm (30 mmφ x 200 mm for steel type 1) material at 850°C for 2 hours, cooling with oil, and tempering at 600°C for 2 hours. Prototype steel for steel types 4 to 11 is produced by melting a 100Kg steel ingot.
Tests were conducted on as-forged specimens to 50 mmφ, only steel type 10, and those normalized at 800°C for 2 hours after forging. The results are shown in Table 2. As can be seen from the table, by comparing Steel Types 1 to 3 and Steel Types 7 to 12 of the steel of the present invention, it can be said that the steel of the present invention is comparable in strength to conventional tempered steel. However, looking at the results of comparative steels 4 to 6, it is clear that these steel types are inferior in toughness. As is clear from the above description, the steel of the present invention has properties comparable to conventional tempered tough steel without being tempered, and is compatible with future energy savings.
【表】【table】
【表】
注：○印の鋼は本発明鋼。
引張試験片はJIS 4号。
シヤルピー試験片はJIS 3号で、常
温で試験。
[Table] Note: Steels marked with ○ are steels of the present invention.
The tensile test piece is JIS No. 4.
Shalpey test pieces are JIS No. 3 and tested at room temperature.
第１図は、２mmＶノツチ・シヤルピー値
（uE20）とＮ／0.29Tiとの関係を示す図である。
FIG. 1 is a diagram showing the relationship between the 2 mmV notch sharpy value (uE20) and N/0.29Ti.
Claims (1)
〜２％、Ti：0.01〜0.05％、Ｎ：0.29Ti〜0.025
％、さらにＶ：0.01〜0.1％、Nb：０・01〜0.1％
の１種または２種を含有し、残部が鉄および不純
物からなることを特徴とする非調質強靭鋼。 ２ Ｃ：0.3〜0.8％、Si：0.15〜1.5％、Mn：0.5
〜２％、Ti：0.01〜0.05％、Ｎ：0.29Ti〜0.025
％、さらにＶ：0.01〜0.1％、Nb：0.01〜0.1％の
１種または２種を含有し、これにさらにCr：２
％以下、Ni：２％以下の１種または２種を含み、
残部が鉄および不純物からなることを特徴とする
非調質強靭鋼。[Claims] 1 C: 0.3 to 0.8%, Si: 0.15 to 1.5%, Mn: 0.5
~2%, Ti: 0.01~0.05%, N: 0.29Ti~0.025
%, further V: 0.01~0.1%, Nb: 0.01~0.1%
A non-thermal toughened steel characterized by containing one or two of the following, with the remainder consisting of iron and impurities. 2 C: 0.3-0.8%, Si: 0.15-1.5%, Mn: 0.5
~2%, Ti: 0.01~0.05%, N: 0.29Ti~0.025
%, further contains one or two of V: 0.01 to 0.1%, Nb: 0.01 to 0.1%, and further contains Cr: 2
% or less, Ni: Contains one or two types of 2% or less,
A non-heat treated strong steel characterized by the balance being iron and impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11173179A JPS5638448A (en) | 1979-09-03 | 1979-09-03 | Nonrefined tough steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11173179A JPS5638448A (en) | 1979-09-03 | 1979-09-03 | Nonrefined tough steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5638448A JPS5638448A (en) | 1981-04-13 |
| JPS6323261B2 true JPS6323261B2 (en) | 1988-05-16 |
Family
ID=14568740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11173179A Granted JPS5638448A (en) | 1979-09-03 | 1979-09-03 | Nonrefined tough steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5638448A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5858252A (en) * | 1981-10-02 | 1983-04-06 | Kawasaki Steel Corp | Steel for steel pipe for oil well |
| JPS59143045A (en) * | 1983-02-07 | 1984-08-16 | Nippon Kokan Kk <Nkk> | Unnormalized steel with superior toughness |
| JPS62119035A (en) * | 1985-11-20 | 1987-05-30 | 三菱製鋼株式会社 | High-strength, heat-resistant and corrosion-resistant clad shape steel and manufacture thereof |
| DE3719569C2 (en) * | 1986-07-05 | 1988-06-23 | Thyssen Edelstahlwerke Ag | Microalloyed steels. |
| US5221373A (en) * | 1989-06-09 | 1993-06-22 | Thyssen Edelstahlwerke Ag | Internal combustion engine valve composed of precipitation hardening ferritic-pearlitic steel |
| JP2743116B2 (en) * | 1990-07-27 | 1998-04-22 | 愛知製鋼 株式会社 | Non-heat treated steel for hot forging |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52114419A (en) * | 1976-03-19 | 1977-09-26 | Jones & Laughlin Steel Corp | High strength steel articles and production of it |
| JPS5466322A (en) * | 1977-11-05 | 1979-05-28 | Nippon Steel Corp | Hot rolling method for mo-added tough steel |
-
1979
- 1979-09-03 JP JP11173179A patent/JPS5638448A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52114419A (en) * | 1976-03-19 | 1977-09-26 | Jones & Laughlin Steel Corp | High strength steel articles and production of it |
| JPS5466322A (en) * | 1977-11-05 | 1979-05-28 | Nippon Steel Corp | Hot rolling method for mo-added tough steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5638448A (en) | 1981-04-13 |
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