JPH06248341A - Production of steel with high strength and high toughness from non-heat-treated steel - Google Patents
Production of steel with high strength and high toughness from non-heat-treated steelInfo
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- JPH06248341A JPH06248341A JP3368793A JP3368793A JPH06248341A JP H06248341 A JPH06248341 A JP H06248341A JP 3368793 A JP3368793 A JP 3368793A JP 3368793 A JP3368793 A JP 3368793A JP H06248341 A JPH06248341 A JP H06248341A
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、熱間鍛造用高強度非調
質鋼の製造方法、特に熱間鍛造・圧延を施した後、例え
ば空冷もしくは衝風冷却することにより、ベイナイト組
織が生成することを特徴とする熱間鍛造用高強度非調質
鋼の製造方法である。FIELD OF THE INVENTION The present invention relates to a method for producing a high strength non-heat treated steel for hot forging, in particular, after hot forging and rolling, a bainite structure is formed by, for example, air cooling or blast cooling. It is a method for producing a high-strength non-heat treated steel for hot forging.
【０００２】[0002]
【従来の技術】現在、引張強度724N/mm2級の非調質鋼は
実用化されているが、最近は、工程省略、コスト低減を
目的とした非調質鋼化から一歩進み、例えば自動車用材
料としては、環境問題を考慮した軽量化 (高強度化) に
よる燃費向上を目的とし高強度非調質鋼の開発ニーズが
高まっている。 2. Description of the Related Art At present, a non-heat treated steel having a tensile strength of 724 N / mm 2 is put into practical use, but recently, one step has been taken from the non-heat treated steel for the purpose of omitting steps and reducing costs. As a material for use, there is an increasing need for the development of high-strength non-heat treated steel with the aim of improving fuel efficiency through weight reduction (higher strength) in consideration of environmental issues.
【０００３】従来の非調質鋼は、フェライト・パーライ
ト組織を有するものであって、熱間鍛造後の冷却途上に
おけるＶ、Nb等の化合物の析出硬化を利用したものであ
る。しかし、靱性が調質鋼に比べて劣る。また、フェラ
イト・パーライト組織であるため、Ｓ、Ti等の細粒化元
素を添加しても強度、靱性を両立させるのは困難であ
る。Conventional non-heat treated steel has a ferrite-pearlite structure and utilizes precipitation hardening of compounds such as V and Nb during cooling after hot forging. However, its toughness is inferior to that of heat-treated steel. In addition, since it has a ferrite-pearlite structure, it is difficult to achieve both strength and toughness even if fine-grained elements such as S and Ti are added.
【０００４】そこで、化学成分を調整し、組織をベイナ
イト組織にし、高強度かつ高靱性を実現する非調質鋼が
提案されてきた。例えば引張強度 980 N/mm2、シャルピ
ー衝撃値49J という非調質タイプの材料もみられるよう
になった。しかしながら、ベイナイト組織の欠点として
フェライト・パーライト系に比べて降伏比(YR)、つまり
降伏比(YR)＝ (降伏強さ) ／ (引張強さ) が低いという
問題がある。これは機械構造部品において重大な問題で
ある。Therefore, a non-heat treated steel has been proposed which adjusts the chemical composition and makes the structure a bainite structure to realize high strength and high toughness. For example, a non-heat treated type material with a tensile strength of 980 N / mm 2 and a Charpy impact value of 49 J has also come to be seen. However, a disadvantage of the bainite structure is that the yield ratio (YR), that is, the yield ratio (YR) = (yield strength) / (tensile strength) is lower than that of the ferrite-pearlite system. This is a serious problem in mechanical structural parts.
【０００５】[0005]
【発明が解決しようとする課題】ここに、本発明の目的
は、非調質鋼であっても高強度かつ高靱性を備えるとと
もに降伏比(YR)が高い鋼の製造方法を提供することであ
る。本発明の具体的な目的は、引張強さ980 N/mm2 以
上、降伏強さ784 N/mm2 以上、シャルピー値uE+20 ≧4
9、uE-50 ≧15であって降伏比(YR) 0.8以上の非調質タ
イプの材料を提供することである。SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a steel having high strength and high toughness and a high yield ratio (YR) even if it is a non-heat treated steel. is there. The specific objects of the present invention are tensile strength of 980 N / mm 2 or more, yield strength of 784 N / mm 2 or more, and Charpy value uE +20 ≧ 4.
9. It is to provide a non-heat treated type material having a yield ratio (YR) of 0.8 or more with uE -50 ≧ 15.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、高強度か
つ高靱性を得るためにベイナイト組織が好ましいと考え
るとともに、そのような鋼を歪時効効果を利用すること
で、YR (降伏比) の向上を図ることに着目した。The present inventors consider that a bainite structure is preferable in order to obtain high strength and high toughness, and by utilizing the strain aging effect in such steel, YR (yield ratio ) Was focused on.
【０００７】すなわち、ベイナイト組織は低温域での変
態であるため、フェライト・パーライト組織のようなYR
を得ることができないが、その後に冷間加工による歪導
入を行うことによって鋼中の転位密度を高くし、次いで
時効処理によってそれらを平衡状態にすることにより、
高強度かつ高靱性を確保したままYRを向上させることが
できることを知り、本発明を完成した。That is, since the bainite structure is a transformation in the low temperature region, it is a YR like ferrite / pearlite structure.
However, by increasing the dislocation density in the steel by subsequently introducing strain by cold working, and then equilibrating them by aging treatment,
The inventors have completed the present invention knowing that YR can be improved while ensuring high strength and high toughness.
【０００８】かくして、本発明の要旨とするところは、
重量％で、Ｃ: 0.05〜0.25％、 Si: 0.10〜1.00
％、Mn: 0.50〜3.00％、 Ｐ: 0.025 ％以下、Cr:
0.30〜3.00％、 Mo: 1.00％以下、Ｂ: 0.0005〜0.
0050％、 Ti: 0.010 〜0.100 ％、Al: 0.010 〜0.100
％、 Ｎ: 0.0200％以下、さらに必要に応じて、次の群
〜から選んだ少なくとも１種を含み、 Cu: 1.0 ％以下、Ｖ: 0.01〜0.30％の１種もしくは２
種を含有し、 Ni: 1.0 ％以下、Nb: 0.010 〜0.100 ％、Zr: 0.20％
以下、Ｓ: 0.100 ％以下の１種もしくは２種以上、 Pb: 0.50％以下、Ca:0.0100 ％以下、Te:0.20 ％以
下、Se:0.50 ％以下、Bi:0.40 ％以下の１種もしくは２
種以上 残部Feおよび不可避的不純物から成る鋼組成を有し、熱
間加工を施した後、例えば空冷もしくは衝風冷却するこ
とにより、ベイナイト組織とした非調質鋼に、次いで歪
量で10％以下の冷間加工を加え、さらに50〜300 ℃の範
囲で10分以上の焼戻しを行うことを特徴とする非調質鋼
からの高強度高靱性鋼の製造方法である。Thus, the gist of the present invention is as follows.
% By weight, C: 0.05 to 0.25%, Si: 0.10 to 1.00
%, Mn: 0.50 to 3.00%, P: 0.025% or less, Cr:
0.30 to 3.00%, Mo: 1.00% or less, B: 0.0005 to 0.
0050%, Ti: 0.010 to 0.100%, Al: 0.010 to 0.100
%, N: 0.0200% or less and, if necessary, at least one selected from the following groups, Cu: 1.0% or less, V: 0.01 to 0.30%, or 2
Contains seeds, Ni: 1.0% or less, Nb: 0.010 to 0.100%, Zr: 0.20%
1 or 2 or more of S: 0.100% or less, Pb: 0.50% or less, Ca: 0.0100% or less, Te: 0.20% or less, Se: 0.50% or less, Bi: 0.40% or less.
It has a steel composition consisting of at least one kind of balance Fe and unavoidable impurities, and after hot working, for example, by air cooling or air blast cooling, it becomes a non-heat treated steel with bainite structure, and then a strain amount of 10%. A method for producing a high-strength, high-toughness steel from a non-heat treated steel, which comprises performing the following cold working and further tempering for 10 minutes or more in a range of 50 to 300 ° C.
【０００９】[0009]
【作用】次に、本発明において上述のように鋼組成およ
び加工条件を限定した理由を詳述する。まず、本発明に
おける鋼組成の成分の限定理由は次の通りである。Next, the reason why the steel composition and working conditions are limited as described above in the present invention will be described in detail. First, the reasons for limiting the components of the steel composition in the present invention are as follows.
【００１０】Ｃ：0.05〜0.25％ Ｃは鋼に所定の静的強度を付与するのに必要な元素であ
り、最低減の静的強度を得るためには0.05％以上が必要
である。一方、0.25％を超えると、Ｂによる靱性の向上
効果が低減する。従って、Ｃ量を0.05〜0.25％と限定す
る。C: 0.05 to 0.25% C is an element necessary for imparting a predetermined static strength to steel, and 0.05% or more is necessary to obtain the minimum static strength. On the other hand, if it exceeds 0.25%, the effect of improving the toughness due to B is reduced. Therefore, the C content is limited to 0.05 to 0.25%.
【００１１】Si：0.10〜1.00％ Siは鋼の脱酸に必要であるとともに、所定の静的強度を
付与するのに必要な元素である。最低限の静的強度を付
与するためには、0.10％以上が必要である。しかし、1.
00％を超えると粒界に偏析し、粒界脆化が著しくなるた
め、Si量は0.10〜1.00％と限定する。Si: 0.10 to 1.00% Si is an element necessary for deoxidizing steel and imparting a predetermined static strength. 0.10% or more is required to give the minimum static strength. But 1.
If it exceeds 00%, segregation occurs at the grain boundaries, and grain boundary embrittlement becomes significant, so the Si content is limited to 0.10 to 1.00%.
【００１２】Mn：0.50〜3.00％ MnはSi同様、鋼の脱酸に必要な元素であり、また焼入れ
性を向上させるのに有効な元素である。その効果を充分
発揮させるためには、0.50％以上の添加が必要である。
一方、3.00％を超えて添加すると粒界脆化を生じ靱性を
低下させる。従って、Mn量は0.50〜3.00％とする。Mn: 0.50 to 3.00% Like Si, Mn is an element necessary for deoxidizing steel and is an element effective for improving hardenability. In order to fully bring out the effect, it is necessary to add 0.50% or more.
On the other hand, if added in excess of 3.00%, grain boundary embrittlement occurs and toughness decreases. Therefore, the Mn content is 0.50 to 3.00%.
【００１３】Ｐ:0.025％以下 Ｐは粒界に偏析し、靱性を低下する。特に0.025 ％を超
えるとその影響は大きくなる。従って、0.025 ％以下に
抑える必要がある。P: 0.025% or less P segregates at grain boundaries and reduces toughness. Especially when the content exceeds 0.025%, the effect becomes large. Therefore, it is necessary to keep it below 0.025%.
【００１４】Cr：0.30〜3.00％ Crは鋼に所定の焼入性を付与し、静的強度を向上させる
のに有効な元素である。その効果を充分発揮させるため
には、0.30％以上の添加が必要である。一方、3.00％を
越えて添加するとCr炭化物が生成し、靱性を低下させ
る。従って、Cr量は0.30〜3.00％とする。Cr: 0.30 to 3.00% Cr is an element effective for imparting a predetermined hardenability to steel and improving static strength. In order to fully bring out the effect, it is necessary to add 0.30% or more. On the other hand, if added in excess of 3.00%, Cr carbides are formed and the toughness is reduced. Therefore, the Cr content is 0.30 to 3.00%.
【００１５】Mo：1.00％以下 MoはNi同様、鋼に所定の焼入性を付与し、静的強度、靱
性を向上させるのに有効な元素である。任意に添加する
ことができるが、1.0 ％を超えて添加することができる
が、1.0 ％を超えて添加してもその効果は飽和し、経済
性を損なうので上限を1.0 ％とする。Mo: 1.00% or less Like Ni, Mo is an element effective for imparting a predetermined hardenability to steel and improving static strength and toughness. Although it can be added arbitrarily, it can be added in an amount of more than 1.0%, but even if added in an amount of more than 1.0%, its effect is saturated and the economy is impaired, so the upper limit is made 1.0%.
【００１６】Ｂ:0.0005 〜0.0050％ Ｂは焼入性を向上させると同時に靱性を向上させる効果
がある。その効果を充分発揮させるためには0.0005％以
上の添加が必要である。一方、0.0050％を超えて添加す
ると、結晶粒が粗大化し、靱性が低下するので、Ｂ量は
0.0005〜0.0050％に制御する必要がある。B: 0.0005 to 0.0050% B has the effect of improving hardenability and at the same time improving toughness. In order to fully bring out the effect, addition of 0.0005% or more is necessary. On the other hand, if added in excess of 0.0050%, the crystal grains become coarse and the toughness decreases, so the B content is
It is necessary to control 0.0005 to 0.0050%.
【００１７】Ti：0.010 〜0.100 ％ TiはTiN として窒化物を生成させ、結晶粒を微細化する
効果がある。また、本発明の目的であるＢ添加による強
度、靱性の向上を図るためにはTiを添加し、窒化物を生
成させＮを固定する必要がある。それに必要な最低減の
添加量は0.010％である。一方、0.100 ％を超えて含有
させると巨大なTi窒化物が生成し、靱性を低下させる。
従って、Tiの添加量は0.010 〜0.100 ％とする。Ti: 0.010 to 0.100% Ti has the effect of forming nitrides as TiN and refining the crystal grains. Further, in order to improve the strength and toughness by adding B, which is the object of the present invention, it is necessary to add Ti to form a nitride and fix N. The minimum amount of addition necessary for that is 0.010%. On the other hand, if the content exceeds 0.100%, a huge Ti nitride is formed and the toughness is reduced.
Therefore, the addition amount of Ti is set to 0.010 to 0.100%.
【００１８】Al：0.010 〜0.100 ％ AlはSi、Mn同様、鋼の脱酸に必要な元素である。また、
Al窒化物を生成し、結晶粒を微細化する効果がある。ま
た、本発明の目的であるＢ添加による強度・靱性の向上
を図るためには、前述のTiに加え、Alを添加し、Ｎを固
定する必要がある。それに必要な最低減の添加量は0.01
0 ％である。しかし、0.100 ％を超えて添加すると巨大
なAl酸化物が生成し、疲労強度を低下させる。さらに結
晶粒が粗大化し、靱性が低下する。従ってAlの添加量は
0.010 〜0.100 ％とする。Al: 0.010 to 0.100% Al, like Si and Mn, is an element necessary for deoxidizing steel. Also,
It has the effect of producing Al nitrides and refining the crystal grains. Further, in order to improve the strength and toughness by adding B, which is the object of the present invention, it is necessary to add Al and fix N in addition to the above-mentioned Ti. The minimum amount of addition required for that is 0.01
It is 0%. However, if it is added in excess of 0.100%, a huge Al oxide will be formed and the fatigue strength will be reduced. Furthermore, the crystal grains become coarser and the toughness decreases. Therefore, the amount of Al added is
0.010 to 0.100%
【００１９】Ｎ: 0.0200％以下 ＮはTi、Al等と結合して窒化物を生成し、結晶粒を微細
化する効果がある。本発明の目的であるＢ添加による強
度・靱性向上を図るためには、ＮをTi、Alで固定する必
要がある。しかし、0.0200％を超えて添加すると、Ti、
AlによるＮの固定は困難となり、Ｂの効果が低減する。
従って、Ｎ含有量の上限を0.0200％とする。N: 0.0200% or less N has an effect of combining with Ti, Al or the like to form a nitride and refining crystal grains. In order to improve the strength and toughness by adding B, which is the object of the present invention, it is necessary to fix N with Ti and Al. However, if added over 0.0200%, Ti,
Fixing N with Al becomes difficult, and the effect of B is reduced.
Therefore, the upper limit of the N content is 0.0200%.
【００２０】本発明はあっては、さらに必要に応じて、
下記群〜の元素を少なくとも１種適正量添加するこ
とによって一層その効果が発揮される。 Cu: 1.0 ％以下、Ｖ: 0.01〜0.30％の１種または２種 これらは更なる強度改善をはかるために必要に応じて添
加するものである。In the present invention, further, if necessary,
The effect is further exhibited by adding an appropriate amount of at least one element of the following groups. Cu: 1.0% or less, V: 0.01 to 0.30%, 1 type or 2 types These are added as needed in order to further improve the strength.
【００２１】Cu: 1.0 ％以下 Cuは鋼の静的強度を向上させるのに有効な元素である。
その効果を発揮させるためには適宜添加すればよいが、
1.0 ％を超えて含有させると熱間加工性が低下する。従
って上限を1.0 ％とする。Cu: 1.0% or less Cu is an element effective for improving the static strength of steel.
It may be added as appropriate in order to exert its effect,
If the content exceeds 1.0%, the hot workability decreases. Therefore, the upper limit is 1.0%.
【００２２】Ｖ: 0.01〜0.30％ Ｖは鋼の高温強度を向上させるのに有効な元素である。
その効果を十分発揮させるためには0.01％以上添加する
必要がある。しかし、0.30％を超えて含有させるとCu同
様熱間加工性が低下する。従って、上限を0.30％とす
る。V: 0.01 to 0.30% V is an effective element for improving the high temperature strength of steel.
In order to bring out the effect sufficiently, it is necessary to add 0.01% or more. However, if the content exceeds 0.30%, the hot workability deteriorates like Cu. Therefore, the upper limit is 0.30%.
【００２３】Ni: 1.00％以下、Nb: 0.010 〜0.100
％、Zr: 0.20％以下、Ｓ: 0.10％以下の１種もしくは２
種以上 これらは特に結晶の微細化を通じて靱性の改善をさらに
図るために必要に応じて添加するものである。Ni: 1.00% or less, Nb: 0.010 to 0.100
%, Zr: 0.20% or less, S: 0.10% or less 1 or 2
Species and above These are added as necessary in order to further improve the toughness, especially through the refinement of crystals.
【００２４】Ni: 1.00％以下 Niは鋼に所定の焼入性を付与し、静的強度および靱性を
向上させるので有効である。任意に添加することができ
るが1.00％を超えて添加してもその効果は飽和し、経済
性を損なうので上限を1.00％とする。Ni: 1.00% or less Ni is effective because it imparts a predetermined hardenability to steel and improves static strength and toughness. Although it can be added arbitrarily, the effect is saturated even if it is added in excess of 1.00% and the economical efficiency is impaired, so the upper limit is made 1.00%.
【００２５】Nb: 0.010 〜0.100 ％ Nbは窒化物を生成し結晶粒を微細化し、靱性を向上させ
る効果がある。その効果を十分に発揮させるためには少
なくとも0.010 ％以上の添加が必要である。しかし、0.
100 ％を超えて添加してもその効果は飽和するとともに
熱間加工性を低下させる。従って、Nbの添加量は0.010
〜0.100 ％とする。Nb: 0.010 to 0.100% Nb has the effect of forming nitrides and refining the crystal grains to improve toughness. In order to fully bring out the effect, it is necessary to add at least 0.010%. But 0.
Even if added over 100%, the effect is saturated and the hot workability is deteriorated. Therefore, the amount of Nb added is 0.010.
~ 0.100%
【００２６】Zr: 0.20％以下 Zrは介在物を微細均一に分散させ、結晶粒粗大化を防止
し靱性を向上させる働きがある。しかしながら、0.20％
を超えて添加するとZr化合物が粗大析出し、逆に靱性を
低下させる。従って、上限を0.20％とする。Zr: 0.20% or less Zr has a function of finely and uniformly dispersing inclusions, preventing coarsening of crystal grains, and improving toughness. However, 0.20%
If it is added over the range, the Zr compound coarsely precipitates, and conversely reduces toughness. Therefore, the upper limit is 0.20%.
【００２７】Ｓ: 0.100 ％以下 ＳはMnＳとして切削性を向上させる働きがあると同時に
結晶粒を微細化、靱性を向上させる働きがある。しかし
ながら、0.100 ％を超えて添加すると巨大なMnＳが生成
し、疲労特性を低下させる。従って上限を0.100 ％とす
る。S: 0.100% or less S has the function of improving the machinability as MnS, and at the same time has the function of refining the crystal grains and improving the toughness. However, if it is added in excess of 0.100%, huge MnS will be produced and the fatigue properties will be deteriorated. Therefore, the upper limit is 0.100%.
【００２８】Pb: 0.50％以下、Ca: 0.010 ％以下、T
e: 0.20％以下、Se: 0.50％以下、Bi:0.40％以下の１種
もしくは２種以上 これらはいわゆる快削性元素であって、得られる鋼の快
削性を改善するために必要に応じて添加するものであ
る。Pb: 0.50% or less, Ca: 0.010% or less, T
e: 0.20% or less, Se: 0.50% or less, Bi: 0.40% or less, one or more of these are so-called free-cutting elements, and if necessary to improve the free-cutting property of the obtained steel. Is to be added.
【００２９】Pb: 0.50％以下 Pbは切削性を向上させる元素であるが、0.50％を超えて
添加すると疲労特性が著しく低下する。従って上限を0.
50％とする。Pb: 0.50% or less Pb is an element that improves the machinability, but if it is added in an amount exceeding 0.50%, the fatigue properties are significantly reduced. Therefore, the upper limit is 0.
50%
【００３０】Ca: 0.0100％以下 CaはPb同様、切削性を向上させる元素であるが、0.0100
％を超えて添加すると靱性が著しく低下する。従って上
限を0.0100％とする。Ca: 0.0100% or less Ca, like Pb, is an element that improves machinability.
If added in excess of%, the toughness will be significantly reduced. Therefore, the upper limit is set to 0.0100%.
【００３１】Te: 0.20％以下 Teは切削性を向上させる元素である。しかし、0.20％を
超えて添加すると靱性を低下させる。従って、0.20％を
上限とする。Te: 0.20% or less Te is an element that improves machinability. However, if added over 0.20%, the toughness decreases. Therefore, the upper limit is 0.20%.
【００３２】Se: 0.50％以下 SeもTe同様、切削性を向上させる元素である。しかし、
0.50％を超えて添加すると靱性を低下させる。従って上
限を0.50％とする。Se: 0.50% or less Se, like Te, is an element that improves machinability. But,
If added in excess of 0.50%, toughness decreases. Therefore, the upper limit is 0.50%.
【００３３】Bi: 0.40％以下 BiもTe、Se同様、切削性を向上させる元素である。しか
し、0.40％を超えて添加すると、靱性を低下させる。従
って上限を0.40％とする。Bi: 0.40% or less Bi, like Te and Se, is an element that improves machinability. However, if added over 0.40%, the toughness decreases. Therefore, the upper limit is 0.40%.
【００３４】かかる鋼組成を有するいわゆる非調質鋼は
熱間圧延、熱間鍛造等の熱間加工によって所定部品の形
状に加工してから、通常は空冷または衝風冷却すること
によりベイナイト組織が生成されるが、本発明によれば
このようにして成形された非調質鋼に対して、次いでさ
らに冷間加工そして焼戻処理 (時効処理) が行われる。
熱間鍛造などの熱間加工および冷却条件は特に制限され
ない。慣用の手段を用いればよい。しかし、本発明にお
いて加えられる冷間加工は転位導入のためであって、通
常の成形用の冷間加工とは区別される。そこで、本発明
において行う冷間加工および時効処理条件の限定理由に
ついて以下説明する。A so-called non-heat treated steel having such a steel composition is processed into a predetermined component shape by hot working such as hot rolling and hot forging, and then usually bainite structure is obtained by air cooling or wind blast cooling. According to the present invention, the non-heat treated steel thus formed is then subjected to further cold working and tempering treatment (aging treatment).
Hot working such as hot forging and cooling conditions are not particularly limited. Conventional means may be used. However, the cold work added in the present invention is for introducing dislocations, and is distinguished from the normal cold work for forming. Therefore, the reasons for limiting the cold working and aging treatment conditions performed in the present invention will be described below.
【００３５】冷間加工: 歪量 (加工率) 10％以下 目標の降伏比を得るには歪量 (加工率) 10％以下の冷間
加工で十分に効果が得られる。特に、１〜10％、好まし
くは５％の冷間加工での効果が発揮する。すでに鍛造な
どの熱間加工によって所定形状としていることから成形
は必要としないのである。Cold Working: Strain Amount (Working Rate) 10% or Less In order to obtain a target yield ratio, cold working with a strain amount (working rate) of 10% or less is sufficiently effective. In particular, the effect in cold working of 1 to 10%, preferably 5% is exerted. Since it has already been formed into a predetermined shape by hot working such as forging, molding is not required.
【００３６】時効温度: 50〜300 ℃ 時効効果が得られるためには最低限50℃以上が必要であ
る。しかし、300 ℃を超えると所定の強度が著しく低下
する。Aging temperature: 50 to 300 ° C. In order to obtain the aging effect, at least 50 ° C. or higher is required. However, when the temperature exceeds 300 ° C, the predetermined strength is significantly reduced.
【００３７】時効時間: 10分以上 時効温度と同様に、時効効果を得るためには最低限10分
以上が必要である。処理時間の上限は特に制限ないが、
一般には経済性を考慮すれば12分程度で十分である。次
に、本発明の作用効果について実施例によってさらに具
体的に説明する。Aging time: 10 minutes or more As with the aging temperature, at least 10 minutes or more is required to obtain the aging effect. The upper limit of processing time is not particularly limited,
Generally, about 12 minutes is sufficient considering the economy. Next, the function and effect of the present invention will be described more specifically by way of examples.
【００３８】[0038]
【実施例】150 kg大気溶製材を1250℃に１時間加熱し直
径50mmに鍛伸した。さらに、1250℃に加熱して直径30mm
に鍛伸 (仕上げ温度: 1100℃) し、供試材とした。直径
30mmの放冷材を引張試験により、0.5 〜12％の歪を与え
30〜350 ℃の範囲で５〜30分の焼戻し処理を行った。[Example] A 150 kg air-melted material was heated to 1250 ° C for 1 hour and forged to a diameter of 50 mm. Furthermore, it is heated to 1250 ℃ and the diameter is 30mm.
It was forged (finishing temperature: 1100 ° C) into a test material. diameter
Applying a strain of 0.5 to 12% to a 30 mm cooled material by a tensile test.
A tempering treatment was performed in the range of 30 to 350 ° C. for 5 to 30 minutes.
【００３９】表１に供試鋼の化学成分、表２、表３、表
４、表５に試験結果を示す。本例において、歪を与える
には図１に示す装置を使用し、万能試験機10の保持部12
に両端を支持された供試材14には引張りによる歪みが付
与され、その中心に取付けられた歪測定子16によって歪
み量が計測され、そのデータは歪測定器20に記録され
る。本例では引張加工時の歪量でもって代用している。Table 1 shows the chemical composition of the test steel, and Table 2, Table 3, Table 4 and Table 5 show the test results. In this example, the apparatus shown in FIG. 1 is used to apply the strain, and the holding section 12 of the universal testing machine 10 is used.
Strain due to tension is applied to the test material 14 whose both ends are supported, and the amount of strain is measured by the strain gauge 16 attached to the center thereof, and the data is recorded in the strain measuring instrument 20. In this example, the strain amount at the time of tensile processing is used instead.
【００４０】表１、表２から明らかなように本発明によ
り製造された鋼は引張強度、シャルピー吸収エネルギー
値は、共に目標値を満足する。一方、比較例の鋼の中で
もＣ、Si、Mn、Ｐ、Cr、Ｂ、Ti、Alが規定値よりも高目
に外れたものは衝撃特性が劣り、目標値を満足しない。
また、Ｃ、Ｂ、Ti、Alが規定値よりも低目に外れたもの
は強度が低下し、目標値を満足しない。さらに、Ｎが規
定値よりも高目に外れたものについては強度が低下し、
目標値を満足しない。As is clear from Tables 1 and 2, the steels manufactured according to the present invention both satisfy the target values for the tensile strength and the Charpy absorbed energy value. On the other hand, among the steels of Comparative Examples, those in which C, Si, Mn, P, Cr, B, Ti, and Al deviate higher than the specified values have poor impact properties and do not satisfy the target values.
Further, if C, B, Ti, and Al deviate below the specified values, the strength decreases and the target values are not satisfied. Furthermore, if N is higher than the specified value, the strength will decrease,
Does not meet the target value.
【００４１】以上のようにＣ、Si、Mn、Ｐ、Cr、Mo、
Ｂ、Ti、Al、Ｎを厳密に制御することによって、強度・
靱性の優れた熱間鍛造非調質鋼が得られた。表３から明
らかなように１％未満の歪では、鋼中の転位密度があま
り高くならないため、YRはあまり向上しない。また、10
％を超えると、その効果は飽和しYRは逆に低下し始め
る。As described above, C, Si, Mn, P, Cr, Mo,
By strictly controlling B, Ti, Al and N, strength and
A hot forged non-heat treated steel with excellent toughness was obtained. As is clear from Table 3, when the strain is less than 1%, the dislocation density in the steel does not increase so much, so that the YR does not improve so much. Also, 10
When it exceeds%, the effect is saturated and YR starts to decrease.
【００４２】表４から明らかなように50℃未満の時効温
度では平衡状態になりにくいため、YRはあまり向上しな
い。また、300 ℃を超えると過時効となりYRは低下す
る。表５から明らかなように、時効時間が10分未満では
十分な時効処理が行われず、YR向上はあまり望めない。As is clear from Table 4, YR does not improve so much at an aging temperature of less than 50 ° C. because it is difficult to reach an equilibrium state. If the temperature exceeds 300 ° C, overaging will occur and YR will decrease. As is clear from Table 5, when the aging time is less than 10 minutes, sufficient aging treatment is not performed, and YR improvement cannot be expected so much.
【００４３】[0043]
【表１】 [Table 1]
【００４４】[0044]
【表２】 [Table 2]
【００４５】[0045]
【表３】 [Table 3]
【００４６】[0046]
【表４】 [Table 4]
【００４７】[0047]
【表５】 [Table 5]
【００４８】[0048]
【発明の効果】本発明によれば、化学成分を調整し、組
織をベイナイト組織にし、高強度かつ高靱性を得ること
ができ、しかも、歪量で10％以下の冷間加工により鋼中
の転位密度を高くし、さらに50〜300 ℃の範囲で10分以
上の焼戻しにより平衡状態に保たせることによって、YR
を向上させることができる。したがって、非調質鋼を重
要構造材として使用でき、自動車などの構造物の一層の
軽量化を簡便かつ安価な手段でもって図ることが可能と
なる。According to the present invention, the chemical composition can be adjusted, the structure can be made into a bainite structure, and high strength and high toughness can be obtained, and moreover, the strain amount in the steel is 10% or less by cold working. By increasing the dislocation density and further maintaining the equilibrium state by tempering for 10 minutes or more in the range of 50 to 300 ° C, the YR
Can be improved. Therefore, non-heat treated steel can be used as an important structural material, and the weight of a structure such as an automobile can be further reduced by a simple and inexpensive means.
【図１】実施例で使用した歪付与装置の概略説明図であ
る。FIG. 1 is a schematic explanatory diagram of a strain imparting device used in an example.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 宇野 光男 北九州市小倉北区許斐町１番地 住友金属 工業株式会社小倉製鉄所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Uno No. 1 Konomi-cho, Kokurakita-ku, Kitakyushu City Sumitomo Metal Industries, Ltd. Kokura Works
Claims (4)
間加工を施した後、ベイナイト組織とした非調質鋼に、
歪量で10％以下の冷間加工を加え、さらに50〜300 ℃の
範囲で10分以上の焼戻し処理を行うことを特徴とする高
強度高靱性鋼の製造方法。1. By weight%, C: 0.05 to 0.25%, Si: 0.10 to 1.00%, Mn: 0.50 to 3.00%, P: 0.025% or less, Cr: 0.30 to 3.00%, Mo: 1.00% or less, B : 0.0005 to 0.0050%, Ti: 0.010 to 0.100%, Al: 0.010 to 0.100%, N: 0.0200% or less, with a steel composition consisting of the balance Fe and inevitable impurities, and after hot working, bainite structure To non-heat treated steel,
A method for producing high-strength and high-toughness steel, which comprises performing cold working with a strain amount of 10% or less and further performing tempering treatment for 10 minutes or more in a range of 50 to 300 ° C.
を含む、請求項１記載の高強度高靱性鋼の製造方法。2. The method for producing a high-strength and high-toughness steel according to claim 1, wherein the steel composition further contains, by weight, one or two of Cu: 1.0% or less and V: 0.01 to 0.30%.
下、Ｓ: 0.100 ％以下の１種もしくは２種以上、を含
む、請求項１または請求項２記載の高強度高靱性鋼の製
造方法。3. The composition further comprises, by weight, one or more of Ni: 1.0% or less, Nb: 0.010 to 0.100%, Zr: 0.20% or less, and S: 0.100% or less. The method for producing the high-strength and high-toughness steel according to claim 1 or 2.
Se:0.50 ％以下、 Bi:0.40 ％以下の１種もしくは２種以上を含む、請求項
１ないし請求項３のいずれかに記載の高強度高靱性鋼の
製造方法。4. The steel composition further comprises, by weight%, Pb: 0.50% or less, Ca: 0.0100% or less, Te: 0.20% or less,
The method for producing a high-strength and high-toughness steel according to any one of claims 1 to 3, comprising one or more of Se: 0.50% or less and Bi: 0.40% or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3368793A JPH06248341A (en) | 1993-02-23 | 1993-02-23 | Production of steel with high strength and high toughness from non-heat-treated steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3368793A JPH06248341A (en) | 1993-02-23 | 1993-02-23 | Production of steel with high strength and high toughness from non-heat-treated steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06248341A true JPH06248341A (en) | 1994-09-06 |
Family
ID=12393345
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3368793A Withdrawn JPH06248341A (en) | 1993-02-23 | 1993-02-23 | Production of steel with high strength and high toughness from non-heat-treated steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06248341A (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06287679A (en) * | 1993-04-05 | 1994-10-11 | Nippon Steel Corp | Production of non-refining steel for hot forging and non-refining hot forged product and non-refining hot forged product |
| JPH09511282A (en) * | 1995-01-24 | 1997-11-11 | キャタピラー インコーポレイテッド | Deep-hardening boron steel with improved fracture resistance and wear properties |
| FR2756298A1 (en) * | 1996-11-26 | 1998-05-29 | Ascometal Sa | STEEL AND PROCESS FOR THE MANUFACTURE OF A MECHANICAL PART HAVING A BATH STRUCTURE |
| EP0851038A1 (en) * | 1996-12-31 | 1998-07-01 | Ascometal | Steel and process for forming a steel article by cold plastic working |
| WO1999028518A1 (en) * | 1997-11-27 | 1999-06-10 | Mannesmann Ag | Use of an air-hardening steel deoxidized before casting as material for producing a high-strength, weldable, semi-finished product |
| JP2003160833A (en) * | 2001-11-22 | 2003-06-06 | Kobe Steel Ltd | Non-heat-treated thick steel plate with high toughness and high tension, and manufacturing method therefor |
| WO2009138586A2 (en) * | 2008-05-15 | 2009-11-19 | Arcelormittal Gandrange | Micro-alloyed steel for hot forging parts having high mechanical characteristics |
| JP2010215986A (en) * | 2009-03-18 | 2010-09-30 | Jfe Bars & Shapes Corp | Steel for aging treatment |
| EP1375694B2 (en) † | 2002-06-19 | 2010-11-17 | Rautaruukki Oyj | Hot-rolled steel strip and method for manufacturing the same |
| JP2013533919A (en) * | 2010-04-07 | 2013-08-29 | アスコメタル | Steel high-performance machine parts and their manufacturing methods |
| JP2013245363A (en) * | 2012-05-24 | 2013-12-09 | Nippon Steel & Sumitomo Metal Corp | Age-hardenable steel and method for manufacturing machine part |
| JP2018131678A (en) * | 2017-02-17 | 2018-08-23 | 新日鐵住金株式会社 | High strength steel plate and method for producing the same |
| KR20200083718A (en) * | 2018-12-28 | 2020-07-09 | 주식회사 세아창원특수강 | Low Carbon Bainite Micro-alloyed Steels for Cold Heading Applications having High Strength and High Impact Toughness and Method for Manufacturing the Same |
| CN115074634A (en) * | 2022-07-08 | 2022-09-20 | 北京高创智信冶金科技有限公司 | High-strength non-quenched and tempered steel front shaft for heavy-duty automobile and production process thereof |
-
1993
- 1993-02-23 JP JP3368793A patent/JPH06248341A/en not_active Withdrawn
Cited By (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06287679A (en) * | 1993-04-05 | 1994-10-11 | Nippon Steel Corp | Production of non-refining steel for hot forging and non-refining hot forged product and non-refining hot forged product |
| JPH09511282A (en) * | 1995-01-24 | 1997-11-11 | キャタピラー インコーポレイテッド | Deep-hardening boron steel with improved fracture resistance and wear properties |
| FR2756298A1 (en) * | 1996-11-26 | 1998-05-29 | Ascometal Sa | STEEL AND PROCESS FOR THE MANUFACTURE OF A MECHANICAL PART HAVING A BATH STRUCTURE |
| EP0845544A1 (en) * | 1996-11-26 | 1998-06-03 | Ascometal | Steel product made from bainitic steel and process for making the steel product |
| EP0851038A1 (en) * | 1996-12-31 | 1998-07-01 | Ascometal | Steel and process for forming a steel article by cold plastic working |
| FR2757877A1 (en) * | 1996-12-31 | 1998-07-03 | Ascometal Sa | STEEL AND PROCESS FOR THE MANUFACTURE OF A STEEL PART SHAPED BY COLD PLASTIC DEFORMATION |
| JPH10204585A (en) * | 1996-12-31 | 1998-08-04 | Ascometal | Steel for producing steel product by cold plastic deformation, and its production |
| US5919415A (en) * | 1996-12-31 | 1999-07-06 | Ascometal | Steel and process for the manufacture of a steel component formed by cold plastic deformation |
| WO1999028518A1 (en) * | 1997-11-27 | 1999-06-10 | Mannesmann Ag | Use of an air-hardening steel deoxidized before casting as material for producing a high-strength, weldable, semi-finished product |
| JP2003160833A (en) * | 2001-11-22 | 2003-06-06 | Kobe Steel Ltd | Non-heat-treated thick steel plate with high toughness and high tension, and manufacturing method therefor |
| EP1375694B2 (en) † | 2002-06-19 | 2010-11-17 | Rautaruukki Oyj | Hot-rolled steel strip and method for manufacturing the same |
| WO2009138586A2 (en) * | 2008-05-15 | 2009-11-19 | Arcelormittal Gandrange | Micro-alloyed steel for hot forging parts having high mechanical characteristics |
| WO2009138586A3 (en) * | 2008-05-15 | 2010-01-07 | Arcelormittal Gandrange | Micro-alloyed steel for hot forging parts having high mechanical characteristics |
| FR2931166A1 (en) * | 2008-05-15 | 2009-11-20 | Arcelormittal Gandrange Sa | HOT FORGED STEEL WITH HIGH MECHANICAL CHARACTERISTICS OF THE PARTS PRODUCED |
| JP2010215986A (en) * | 2009-03-18 | 2010-09-30 | Jfe Bars & Shapes Corp | Steel for aging treatment |
| JP2013533919A (en) * | 2010-04-07 | 2013-08-29 | アスコメタル | Steel high-performance machine parts and their manufacturing methods |
| JP2013245363A (en) * | 2012-05-24 | 2013-12-09 | Nippon Steel & Sumitomo Metal Corp | Age-hardenable steel and method for manufacturing machine part |
| JP2018131678A (en) * | 2017-02-17 | 2018-08-23 | 新日鐵住金株式会社 | High strength steel plate and method for producing the same |
| KR20200083718A (en) * | 2018-12-28 | 2020-07-09 | 주식회사 세아창원특수강 | Low Carbon Bainite Micro-alloyed Steels for Cold Heading Applications having High Strength and High Impact Toughness and Method for Manufacturing the Same |
| CN115074634A (en) * | 2022-07-08 | 2022-09-20 | 北京高创智信冶金科技有限公司 | High-strength non-quenched and tempered steel front shaft for heavy-duty automobile and production process thereof |
| CN115074634B (en) * | 2022-07-08 | 2023-01-06 | 北京高创智信冶金科技有限公司 | High-strength non-quenched and tempered steel front shaft for heavy-duty automobile and production process thereof |
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