JPH0673439A - High workability steel sheet excellent in high strengthening characteristic by irradiation with high density energy source - Google Patents
High workability steel sheet excellent in high strengthening characteristic by irradiation with high density energy sourceInfo
- Publication number
- JPH0673439A JPH0673439A JP23057092A JP23057092A JPH0673439A JP H0673439 A JPH0673439 A JP H0673439A JP 23057092 A JP23057092 A JP 23057092A JP 23057092 A JP23057092 A JP 23057092A JP H0673439 A JPH0673439 A JP H0673439A
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- Prior art keywords
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- steel sheet
- strength
- energy source
- density energy
- Prior art date
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Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、加工時には優れた加工
特性を有し、なおかつ高密度エネルギー源からの照射に
よって高強度化して使用することができるような鋼板に
関するものである。なお以下の説明においては、自動車
用部材のひとつであるメンバー類を代表的に取り上げて
説明するが、本発明鋼板の適用対象はこれによって制限
されるものではなく、上記両特性の要求される分野に対
しては広く利用することができる。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel sheet which has excellent working characteristics during working and which can be used after being strengthened by irradiation from a high-density energy source. In the following description, the members, which are one of the members for automobiles, will be described as a representative example, but the application target of the steel sheet of the present invention is not limited by this, and is a field in which both the above characteristics are required. Can be widely used for.
【0002】[0002]
【従来の技術】自動車用部材、特にメンバー類等は加工
性と強度の2つの相反する特性が要求されている。即ち
メンバー類を自動車ボディの滑らかな曲線に添わせるよ
うに配置するためには優れた加工性を有していることが
必要であり、一方いったん装着した後は、走行中の衝突
事故に対して優れた防護作用を発揮するという立場から
所定の部分が希望強度まで高強度化されておらなければ
ならない。そこで加工性に富んだ軟鋼板をプレス成形し
た後で高密度エネルギー源による照射を行い、該プレス
成形部品の所定部分を高強度化するという技術が提案さ
れている(特開昭61−99629)。しかしながら前
記特許公開公報に記載された照射条件によれば、高強度
エネルギー源から例えばレーザ照射を行うと、板厚方向
における熱影響の度合いが不均一となって形状に歪みを
生じ、レーザ処理後の形状修正が必要になること、並び
にレーザ処理の必要照射本数が非常に多くなり、全処理
時間が長くなってしまうという点で実用化が妨げられて
いた。2. Description of the Related Art Automotive members, especially members and the like, are required to have two contradictory characteristics, that is, workability and strength. In other words, it is necessary to have excellent workability in order to arrange the members so that they follow the smooth curve of the car body. From the standpoint of exerting an excellent protective action, it is necessary that the prescribed part be strengthened to the desired strength. Therefore, a technique has been proposed in which a mild steel sheet having high workability is press-formed and then irradiated with a high-density energy source to increase the strength of a predetermined portion of the press-formed part (Japanese Patent Laid-Open No. 61-99629). . However, according to the irradiation conditions described in the above-mentioned patent publication, for example, when laser irradiation is performed from a high intensity energy source, the degree of thermal influence in the plate thickness direction becomes uneven and distortion occurs in the shape, and after laser processing Practical use has been hindered in that the shape correction of No. 1 is required and the number of irradiations required for laser processing is very large, and the total processing time becomes long.
【0003】しかも以下に述べていく様な極低炭素鋼
(Cが少ないため成形性が非常に優れている)において
はレーザ処理によって強度を大幅に向上させるという知
見は全く知られていない。特にレーザ処理による強化の
原理は溶融部及びその周囲の熱影響部に見られる焼き入
れ硬化がその本質と考えられており、高成形性である極
低炭素鋼についてはその適用さえ考えれらておらなかっ
た。高成形性材料においてこの様な強度上昇が可能とな
れば、例えば自動車の軽量化に大きく寄与することが期
待され、その効果は非常に大きいものと考えれる。Moreover, in ultra low carbon steels (which have excellent formability due to a small amount of C) as described below, there is no known knowledge that the strength is significantly improved by laser treatment. In particular, the principle of strengthening by laser treatment is considered to be the quench hardening seen in the melted zone and the heat-affected zone around it, and even its application to ultra-low carbon steel with high formability has been considered. There wasn't. If such a strength increase is possible in a high moldability material, it is expected to greatly contribute to weight reduction of automobiles, for example, and the effect is considered to be very large.
【0004】このようなプレス成形及びその後のレーザ
硬化処理を基本構成とする本技術はプレスラインにおい
て部品をプレス加工した後に高密度エネルギー源による
照射を施す点に特徴があるが、これまで検討されてきた
範囲では、高密度エネルギー源による照射条件と対象鋼
組織との組み合わせをどのように工夫すれば、歪みを少
なくすることができ、しかも十分な強度の上昇を得るこ
とができるか等について、全く知見が得られていない。
そのため、高密度エネルギー源による処理条件と鋼組織
との好ましい組み合わせに関する知見を確立することが
切望されていた。換言すれば、プレス成形時には十分な
加工性を有し、加工後は高密度エネルギー源による処理
によって強度が大幅に上昇し得る様な素材鋼板の開発が
望まれていた。The present technology, which is basically composed of such press molding and subsequent laser hardening treatment, is characterized in that the parts are pressed in the press line and then irradiated with a high-density energy source. In the range that has been set, how to devise the combination of the irradiation condition by the high-density energy source and the target steel structure can reduce the strain and obtain a sufficient increase in strength. No knowledge has been obtained.
Therefore, it has been earnestly desired to establish a knowledge about a preferable combination of a treatment condition with a high-density energy source and a steel structure. In other words, it has been desired to develop a material steel sheet that has sufficient workability during press forming, and whose strength can be significantly increased by processing with a high-density energy source after working.
【0005】特開平4−72010にも、プレス成形品
にレーザ照射を行い強度上昇をはかる技術が開示されて
いる。この特許公開公報においては炭素鋼板を用いてレ
ーザ処理を行ったものでは、強度上昇が得られる旨示さ
れている。しかしながらこの特許公開公報においては、
鋼板組成に関しては炭素量に言及しているのみで、炭素
以外の合金成分や鋼板の組織については全く言及してお
らず、したがって合金成分および組織とレーザ処理条件
についての関係、さらにはそれらと強度上昇量の関係に
ついては全く知見が得られていない。本発明者等の研究
によれば、レーザ処理時の強度上昇は、レーザ処理条件
だけではなく、合金成分や組織にも大きく依存している
ことが明らかになった。従ってレーザ処理によって大幅
な強度上昇を得るためには、この関係を明確にすること
が必要であった。Japanese Unexamined Patent Publication (Kokai) No. 4-72010 also discloses a technique for increasing the strength by irradiating a press-formed product with a laser. In this patent publication, it is shown that the increase in strength can be obtained by performing the laser treatment using a carbon steel sheet. However, in this patent publication,
Regarding the steel sheet composition, it only refers to the amount of carbon, and does not refer to the alloy components other than carbon or the microstructure of the steel sheet at all, and therefore the relationship between the alloy components and microstructure and the laser processing conditions, as well as their strength. No knowledge has been obtained regarding the relationship between the amount of increase. The research conducted by the present inventors has revealed that the increase in strength during laser processing largely depends not only on the laser processing conditions but also on the alloy composition and structure. Therefore, it was necessary to clarify this relationship in order to obtain a large increase in strength by laser processing.
【0006】なお、特開昭61−261462には加工
性に優れたレーザ加工用鋼板に関する知見が示されてい
るが、ここではレーザ切断を行った後にプレス成形等の
加工を行う場合の加工性が問題とされている。これに対
し本発明はレーザ照射による硬化処理を目的とするもの
であり、同じレーザ照射とは言っても上記公開公報のよ
うな切断加工を目的とするものではない点で、技術分野
も技術内容も全く異なるものである。[0006] Incidentally, Japanese Patent Laid-Open No. 61-261462 discloses the knowledge of a steel plate for laser processing having excellent workability. Here, the workability in the case of performing processing such as press forming after performing laser cutting. Is a problem. On the other hand, the present invention is intended for the curing treatment by laser irradiation, and the same laser irradiation is not intended for the cutting process as in the above-mentioned publication, and the technical field is also technical content. Is also completely different.
【0007】更に特開平1−259118には、プレス
用素材の強化必要部位に対して急速再溶融−急速再凝固
処理を行って結晶粒の微細化を図り高強度化する技術が
開示されている。しかしこの公開公報発明は、使用時に
裏面となる部位のみを溶融させるものであり、後に詳述
するような本発明の貫通溶融法とは異なって大きな残留
歪みが生じ、なおかつ十分な強度上昇効果が得られな
い。また上記公開公報発明は強化のメカニズムが結晶粒
の微細化にあり、焼入組織を得るものではない。この点
においても焼入組織の形成をメカニズムとする本発明と
は区別される。Further, Japanese Patent Application Laid-Open No. 1-259118 discloses a technique of performing rapid remelting-rapid resolidification treatment on a portion of a press material to be strengthened so as to make crystal grains finer and to have higher strength. . However, the invention disclosed in this publication only melts a portion which becomes the back surface at the time of use, and unlike the through-melting method of the present invention which will be described in detail later, a large residual strain occurs, and a sufficient strength increasing effect is obtained. I can't get it. Further, in the above-mentioned Japanese Laid-Open Patent Publication, the strengthening mechanism lies in the refinement of crystal grains, and a quenched structure is not obtained. This point is also distinguished from the present invention in which the formation of a quenched structure is a mechanism.
【0008】このように従来知られている方法は、本発
明で採用する様な後述の方法と比べて本質的に異なった
方法と言わなければならない。As described above, it must be said that the conventionally known method is essentially different from the method described below, which is used in the present invention.
【0009】[0009]
【発明が解決しようとする課題】本発明者らは、高密度
エネルギー源による処理性におよぼす合金元素の種類や
組織の影響を鋭意研究した結果、ある一定の照射条件の
もとにおいては、鋼板の合金成分を特定の範囲とし、か
つ構成組織を規定することによって、従来の鋼板におい
ては得られなかった様な優れた処理特性が得られること
を見い出して本発明を完成するに至った。DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied the influence of the type and structure of alloying elements on the processability by a high-density energy source, and as a result, under certain irradiation conditions, steel sheets were produced. The present invention has been completed by finding out that by setting the alloy component of (1) to a specific range and defining the constitutional structure, it is possible to obtain excellent processing characteristics that cannot be obtained in the conventional steel sheet.
【0010】[0010]
【課題を解決するための手段】本発明によって提供され
る鋼板は、加工時には優れた加工性を示しながらレーザ
照射等の様な高密度エネルギー源からの照射を行って板
厚を貫通する様な凝固域を形成した場合には、十分な高
強度化を発揮し、そのことにより広範囲の用途に使用す
ることができるものであって、高強度化特性に優れた高
加工性鋼板である。The steel sheet provided by the present invention has excellent workability during processing and is capable of irradiating from a high-density energy source such as laser irradiation to penetrate the plate thickness. When the solidified region is formed, it exhibits a sufficiently high strength, so that it can be used in a wide range of applications, and is a high workability steel sheet excellent in high strength characteristics.
【0011】本発明にかかる高加工性鋼板の合金組成
は、 C :0.002〜0.02% Si:2.0%以下 Mn:0.1〜2.5% を含み、残部がFe及び不可避的不純物よりなり、かつ
フェライトを主体とした組織を有することを特徴とする
ものである。The alloy composition of the high workability steel sheet according to the present invention contains C: 0.002 to 0.02% Si: 2.0% or less Mn: 0.1 to 2.5%, the balance being Fe and Fe. It is characterized by comprising an unavoidable impurity and having a structure mainly composed of ferrite.
【0012】本発明における基本的合金組成は上記のと
おりであるが、上記必須的元素であるC,Si,Mn以
外の合金元素として、更に、 Ti:0.1%以下 Nb:0.1%以下 よりなる群から選ばれる1種以上を含む場合(A)と、
合金元素として、別に、 P:0.06〜0.2% B :50ppm 以下のいずれか1種以上を含む場合
(B)も本発明に包含される。但し(B)の場合 は、 T=(Mn%+20・P%+250・B%+0.25・
Si%)×C% の計算式で与えられるT値が0.01以上であることを
必要要件とする。The basic alloy composition in the present invention is as described above, but as alloy elements other than the above-mentioned essential elements C, Si and Mn, Ti: 0.1% or less Nb: 0.1% When (A) contains at least one selected from the group consisting of:
The present invention also includes a case (B) in which any one or more of P: 0.06 to 0.2% B: 50 ppm or less is separately contained as an alloying element. However, in the case of (B), T = (Mn% + 20.P% + 250.B% + 0.25.
It is necessary that the T value given by the calculation formula of (Si%) × C% is 0.01 or more.
【0013】尚本発明は(C)の場合として、C含有量
及びMn含有量の各下限値をもう少し高めた場合につい
て次の様に定めている。即ち、 C :0.005〜0.02% Si:2.0%以下 Mn:1.2〜2.5% P :0.06〜0.2% B :50ppm 以下 を含み、更に、 Ti:0.01〜0.1% Nb:0.005〜0.1%以下 を含むものであり、且つ前記計算式で与えられるT値が
0.01以上のものである。In the present invention, the case (C) is defined as follows when the lower limits of the C content and the Mn content are increased a little. That is, C: 0.005-0.02% Si: 2.0% or less Mn: 1.2-2.5% P: 0.06-0.2% B: 50ppm or less, and further Ti: 0.01 to 0.1% Nb: 0.005 to 0.1% or less is included, and the T value given by the above calculation formula is 0.01 or more.
【0014】更に本発明は(D)の場合として、 C :0.002〜0.2% Si:2.0%以下 Mn:0.1〜2.5% を含み、更に、 Cu:2.5%以下 Ni:1.5%以下 Cr:2.5%以下 Mo:1.0%以下 P :0.15%以下 B :50ppm以下 Nb:0.1%以下 Ti:0.1%以下 Zr:0.1%以下 V :0.1%以下 W :0.1%以下 のいずれか1種以上を含む場合、並びに(E)の場合と
して、前記(D)におけるNb及びTiを特に必須元素
として含ませる場合を包含する。この場合のTi含有量
は0.1%以下、Nb含有量は0.1%以下と定める。Further, in the case of (D), the present invention contains C: 0.002 to 0.2% Si: 2.0% or less, Mn: 0.1 to 2.5%, and further, Cu: 2. 5% or less Ni: 1.5% or less Cr: 2.5% or less Mo: 1.0% or less P: 0.15% or less B: 50 ppm or less Nb: 0.1% or less Ti: 0.1% or less Zr : 0.1% or less V: 0.1% or less W: 0.1% or less Any one or more of the following is included, and in the case of (E), Nb and Ti in the above (D) are particularly essential elements. Including the case of including as. In this case, the Ti content is 0.1% or less and the Nb content is 0.1% or less.
【0015】[0015]
【作用】まず、高強度エネルギー源による照射条件につ
いて述べる。ここでは高密度エネルギー源としてレーザ
を用いた例を示したが、プラズマ等を用いることもでき
る。図1には、C:51ppm,Mn:0.99%,T
i:0.053%,Al(脱酸剤としての添加に基づく
不純物元素):0.029%、残部Fe及び不可避的不
純物からなる鋼材を試験片(板厚1.4mm)とし、レー
ザ照射条件を種々変更して強度上昇量との関係を示した
が、エネルギー密度が100J/mm2 以上となる様な照射
を行うと、大幅な強度上昇が得られることが分かる。こ
の範囲は板厚を貫通する溶融相を形成する条件であり、
このような条件にすることによって強度の大幅な上昇が
可能となるのである。またそのような条件にすることに
よって板厚方向に生じる歪が解放されるため、処理後の
残留歪を非常に小さく抑えることができる。First, the irradiation conditions by the high intensity energy source will be described. Although an example in which a laser is used as the high-density energy source is shown here, plasma or the like can also be used. In FIG. 1, C: 51 ppm, Mn: 0.99%, T
i: 0.053%, Al (impurity element based on addition as a deoxidizer): 0.029%, steel material consisting of balance Fe and unavoidable impurities as a test piece (plate thickness 1.4 mm), laser irradiation conditions Although various changes were made to show the relationship with the amount of increase in strength, it can be seen that a significant increase in strength can be obtained by performing irradiation so that the energy density becomes 100 J / mm 2 or more. This range is a condition for forming a molten phase that penetrates the plate thickness,
Under these conditions, the strength can be greatly increased. In addition, since the strain generated in the plate thickness direction is released under such a condition, the residual strain after the treatment can be suppressed to be extremely small.
【0016】次に、本発明鋼板における合金成分の限定
理由について説明する。本発明鋼は、特にプレス成形等
の冷間加工用途に好適なものでなければならずこのため
にはCはその添加量が少ないほど好ましい。本発明では
極低炭素鋼領域を狙っているので、0.002〜0.0
2%と定めた。0.002%未満ではレーザ照射等によ
る強度上昇効果が降伏応力にして20MPa以上の上昇
に至らないので、0.002%以上の添加が必要であ
る。一方0.02%を超えると素材自体の加工性が極低
炭素鋼としての特徴を発揮することができない。Next, the reasons for limiting the alloy components in the steel sheet of the present invention will be explained. The steel of the present invention must be particularly suitable for cold working applications such as press forming. For this purpose, the smaller the amount of C added, the more preferable. Since the present invention aims at the extremely low carbon steel region, 0.002 to 0.0
It was set at 2%. If it is less than 0.002%, the effect of increasing the strength by laser irradiation or the like does not increase the yield stress by 20 MPa or more, so 0.002% or more must be added. On the other hand, if it exceeds 0.02%, the workability of the material itself cannot exhibit the characteristics as an ultra-low carbon steel.
【0017】Siは鋼鈑に要求される強度に応じて添加
する。多く添加し過ぎると、著しい表面肌荒れを起こす
ので、上限を2.0%とした。Mnも鋼鈑に要求される
強度に応じて添加するが、あまり多量に添加すると鋼板
の冷間成形性を損なうので、添加量の上限は2.5%と
する。一方下限量についてはレーザ照射による強度向上
効果を有意義に発揮させる(降伏応力にして20MPa
以上の上昇)という趣旨から0.1%と定めたが、より
確実に強度上昇効果を発揮させるには1.2%以上の添
加が望まれる。本発明鋼における必須的含有元素は上記
のとおりであり、残部はFe及び不可避的不純物である
が、所望によっては以下に示す様な元素を添加すること
もできる。Si is added according to the strength required for the steel plate. If too much is added, the surface will be roughened significantly, so the upper limit was made 2.0%. Mn is also added according to the strength required for the steel plate, but if it is added in a too large amount, the cold formability of the steel sheet is impaired, so the upper limit of the addition amount is 2.5%. On the other hand, regarding the lower limit amount, the strength improvement effect by laser irradiation is meaningfully exerted (the yield stress is 20 MPa.
The content was set to 0.1% for the purpose of (the above increase), but it is desired to add 1.2% or more in order to more reliably exert the strength increasing effect. The essential contained elements in the steel of the present invention are as described above, and the balance is Fe and unavoidable impurities, but if desired, the following elements can be added.
【0018】まずPは鋼板の要求強度に応じて添加す
る。しかし多量に添加し過ぎると結晶粒界強度の低下に
基づく二次加工脆性が現れるので、上限を0.2%とす
る。尚下限値についてはレーザ照射による強度上昇効果
の観点から0.06%とすることが望まれる。First, P is added according to the required strength of the steel sheet. However, if too much is added, secondary work embrittlement appears due to a decrease in grain boundary strength, so the upper limit is made 0.2%. The lower limit is preferably 0.06% from the viewpoint of the effect of increasing the strength by laser irradiation.
【0019】次にBはレーザ照射による強度上昇効果の
発揮に特に有用な元素として添加を推奨する。但し50
ppmを超えると母材の延性を著しく劣化させるので5
0ppmとする。下限値については特に設定する必要が
ないが、5ppm以上の添加を推奨することができる。Next, B is recommended to be added as an element which is particularly useful for exerting the strength increasing effect by laser irradiation. However, 50
If it exceeds ppm, the ductility of the base material will be significantly deteriorated, so 5
It is set to 0 ppm. Although there is no particular need to set the lower limit value, addition of 5 ppm or more can be recommended.
【0020】次に重要な元素はTiとNbである。本発
明においては母材鋼板としての成形性が優秀で、一方レ
ーザ処理後の強度上昇が重要な課題となっている。かか
る観点から炭窒化物形成元素の添加された極低炭素鋼で
あることが有用な手段となる。炭窒化物形成元素は鋼中
のC,Nを析出固定し、優れた成形性を付与するという
観点から添加される。この様な目的に適うものとしては
TiとNbが最も有効であり、その適性添加量はTiで
0.01〜0.1%であり、Nbでは0.005〜0.
1%である。尚これらの上限値は経済性の観点から定め
た。The next most important elements are Ti and Nb. In the present invention, the formability as a base steel sheet is excellent, while increasing the strength after laser treatment is an important issue. From this point of view, a very low carbon steel to which a carbonitride forming element is added is a useful means. The carbonitride forming element is added from the viewpoint of precipitating and fixing C and N in steel and imparting excellent formability. Ti and Nb are the most effective for such purposes, and the suitable addition amount thereof is 0.01 to 0.1% for Ti and 0.005 to 0.
1%. The upper limits of these were set from the viewpoint of economic efficiency.
【0021】次にその他の重要元素について説明する。
Crはレーザ処理による強度上昇に有効であるが、不必
要以上の過剰添加は経済性において損失であるので、上
限を2.5%とした。Moはレーザ処理による強度上昇
に有効であるが、多量の添加は経済性を損なうので上限
を1.0%とする。Next, other important elements will be described.
Cr is effective in increasing the strength by laser treatment, but excessive addition of Cr beyond necessity is economically disadvantageous, so the upper limit was made 2.5%. Mo is effective in increasing strength by laser treatment, but addition of a large amount impairs economic efficiency, so the upper limit is made 1.0%.
【0022】Cuは時効析出によって素材強度を確保す
る機能を発揮するものであり、しかも母材の耐食性を向
上させることができるので、素材の特性向上元素として
有効である。しかしながら多量に添加する場合には鋼板
に表面疵を生じさせるので、Niとの複合添加によって
その改善をはかることが必要になる。従って本発明鋼に
おいてはCuとNiを複合添加するとともに、その添加
量はCuに対しては2.5%以下とし、Niはそのコス
トを考慮して1.5%以下とするのが望ましい。Cu has the function of ensuring the strength of the material by aging precipitation, and can improve the corrosion resistance of the base material, and is therefore an effective element for improving the characteristics of the material. However, when added in a large amount, surface defects are generated in the steel sheet, and therefore it is necessary to improve the effect by adding Ni together. Therefore, in the steel of the present invention, it is desirable to add Cu and Ni together and to add them in an amount of 2.5% or less with respect to Cu, and Ni in the amount of 1.5% or less in consideration of the cost.
【0023】Zr,V,Wの各元素は鋼の強度上昇に有
効であるが、経済的制約から上限は0.1%とする。ま
たREMおよびCaは鋼の介在物形態を制御するために
添加しても良いが、過多に添加すると介在物量が増えて
鋼板の冷間加工性および靭性を劣化させるので、上限を
それぞれ0.02%とする。Although each element of Zr, V and W is effective in increasing the strength of steel, the upper limit is set to 0.1% due to economic constraints. Further, REM and Ca may be added in order to control the inclusion morphology of the steel, but if added in excess, the amount of inclusions increases and the cold workability and toughness of the steel sheet deteriorate, so the upper limits are each 0.02 %.
【0024】Mgは水素脆化防止効果があり、レーザ処
理部の水素脆化防止効果のために添加しても良い。但し
経済的な理由から上限を0.01%とする。不可避的不
純物元素としては、N,O等の他、脱酸性元素として添
加することのあるAlを例示することもできる。特にア
ルミキルド鋼の場合は不可避的に混入してくるが、0.
1%を超えるとc系介在物を多く生成して表面傷の原因
となるので、その上限を0.1%と定める。Mg has an effect of preventing hydrogen embrittlement, and may be added for the purpose of preventing hydrogen embrittlement in the laser-treated portion. However, for economic reasons, the upper limit is made 0.01%. Examples of the unavoidable impurity element include N, O and the like, and Al that may be added as a deoxidizing element. Especially in the case of aluminum killed steel, it is inevitably mixed, but
If it exceeds 1%, a large amount of c-based inclusions are generated and cause surface scratches, so the upper limit is set to 0.1%.
【0025】次に成分と強度上昇量の関係について述べ
る。図2の(a),(b)は、下記計算式 T=(Mn%+20・P%+250・B%+0.25・
Si%)×C% で与えられるT値と降伏応力上昇量の関係を示すもので
る。なお(b)は(a)の要部拡大図である。Next, the relationship between the components and the amount of increase in strength will be described. 2A and 2B show the following calculation formula: T = (Mn% + 20.P% + 250.B% + 0.25.
It shows the relationship between the T value given by (Si%) × C% and the yield stress increase amount. Note that (b) is an enlarged view of a main part of (a).
【0026】先ず(b)によれば、C量が0.002%
未満の領域並びにMnが0.1%未満の領域のもの(比
較鋼)では降伏応力の上昇量が8〜10PMa程度でと
どまっている。図2からT値としては0.01以上にす
ることが好ましいことが分かる。また(a)によればT
値が0.06の前後において大幅な強度上昇を示してい
る部分もあるが、この部分ではr値(深絞り性の指標)
が1.1と低下している。これはC量が0.03%と高
いからであると説明される。図3にはC量とr値の関係
を示すが、Cが0.02%を超えるとr値が著しく低下
する。First, according to (b), the C content is 0.002%.
In the region of less than 1% and in the region of less than 0.1% of Mn (comparative steel), the amount of increase in yield stress remains at about 8 to 10 PMa. It can be seen from FIG. 2 that the T value is preferably 0.01 or more. According to (a), T
There is a portion that shows a significant increase in strength around the value of 0.06, but in this portion, r value (index of deep drawability)
Is decreased to 1.1. It is explained that this is because the C content is as high as 0.03%. FIG. 3 shows the relationship between the amount of C and the r value, but when C exceeds 0.02%, the r value remarkably decreases.
【0027】以上述べたように本発明鋼は、素材段階で
は優れた冷間加工性を示し、いったん加工した後は所望
部分がレーザ照射等によって高強度化されるので、使用
条件の下では大幅な強度上昇が可能である。As described above, the steel of the present invention exhibits excellent cold workability at the material stage and, once processed, the desired portion is strengthened by laser irradiation, etc. It is possible to increase the strength.
【0028】本発明におけるレーザ照射等は、上記鋼板
の強度を高めるものであるから、必要な箇所を適切に選
択して照射部を選択すべきである。従って、(1)加工
必要部と強度上昇必要部が部位的に重なっている場合等
は、材料鋼板を予め所定の形状に加工し、しかる後強度
上昇の必要な部位を狙ってレーザ照射を行うことが推奨
されるが、(2)加工必要部と強度上昇必要部が部位的
に十分区別できる場合等は、材料鋼板に対して強度上昇
の必要な部位を狙ってレーザ照射を行い、しかる後に加
工を行うようにしても良い。Since the laser irradiation or the like in the present invention enhances the strength of the steel sheet, it is necessary to appropriately select a necessary portion and select an irradiation portion. Therefore, (1) When the processing required portion and the strength increasing required portion partially overlap with each other, the material steel plate is processed into a predetermined shape in advance, and then laser irradiation is performed aiming at the portion requiring strength increasing. It is recommended that (2) if the processing required part and the strength increase required part can be sufficiently distinguished in parts, laser irradiation is performed on the material steel sheet aiming at the part requiring strength increase, and after that You may make it process.
【0029】後者の例としては図4に示す場合が挙げら
れる。図4において1は素材鋼板、2は山折れ線、3は
谷折れ線、4はレーザ照射部、5は成形品(前記メンバ
ー)を夫々示し、(a)は素材鋼板の平面図、(b)は
加工部とレーザ照射部の位置分けを示す平面説明図、
(c)は成形品外観を示す斜視説明図であり、まず
(b)に示すように加工部である山折れ線2と谷折れ線
3を避けてレーザ照射を行い、しかる後(c)に示すよ
うに所定形状に加工する。なお図示した形状の場合であ
っても、素材鋼板を先に所定形状に加工し、しかる後、
必要部位にレーザ照射を行う様にしてもよいことは言う
でもない。An example of the latter case is shown in FIG. In FIG. 4, 1 is a material steel plate, 2 is a mountain crease line, 3 is a valley crease line, 4 is a laser irradiation part, 5 is a molded product (the member), respectively, (a) is a plan view of the material steel plate, (b) is Plane explanatory view showing the positioning of the processing unit and the laser irradiation unit,
(C) is a perspective explanatory view showing the external appearance of the molded product. First, as shown in (b), laser irradiation is performed while avoiding the mountain fold line 2 and the valley fold line 3 which are the processed parts, and then as shown in (c). It is processed into a predetermined shape. Even in the case of the illustrated shape, the material steel plate is first processed into a predetermined shape, and thereafter,
It goes without saying that the laser irradiation may be performed on a necessary portion.
【0030】なお、本発明の鋼板は熱延ミル、冷延ミル
のいずれの方法によっても製造することができ、また本
発明の鋼板は各種の表面処理、例えば亜鉛めっき等のめ
っきを施したものとして提供することもできる。The steel sheet of the present invention can be manufactured by either a hot rolling mill or a cold rolling mill, and the steel sheet of the present invention is subjected to various surface treatments such as galvanizing. Can also be provided as.
【0031】[0031]
【発明の効果】本発明鋼にレーザ照射を行い板厚を貫通
した凝固域を形成すると、ビード部のみならず、ビード
の隣接領域においても焼入硬化部が形成される。一方レ
ーザ照射のように急速加熱でしかも高温保持が行われな
い場合には、通常炭化物の溶け込みと合金成分の均一化
を達成する時間が不十分となる。そこで本発明において
は、素材である鋼の組織や合金組成を、溶け込みや均一
化に有効な成分および組織としたのである。特に上記レ
ーザ処理条件に対応した成分、組織としたことは非常に
重要な意味を有するのである。こうすることによって炭
素量や合金量を不必要に増やす必要がなくなり、素材の
加工性を合わせて確保することが可能になる。本発明鋼
の場合には上記効果が発揮されるため、硬化する領域を
広くでき、従って強度が大幅に上昇する。このため、例
えばプレス成形したメンバー等の部品に対し、その必要
な部分のみをレーザ処理することによって強度を維持し
つつメンバーに加工する時点では加工性の維持に必要な
変形能を併せ持つことができる。EFFECTS OF THE INVENTION When the steel of the present invention is irradiated with a laser to form a solidified region penetrating the plate thickness, a quench-hardened portion is formed not only in the bead portion but also in the adjacent region of the bead. On the other hand, in the case where rapid heating and high temperature holding are not performed as in laser irradiation, the time for achieving the penetration of carbides and the homogenization of alloy components is usually insufficient. Therefore, in the present invention, the structure and alloy composition of steel, which is a raw material, are made to be a composition and structure effective for penetration and homogenization. In particular, it is very important to have a composition and structure corresponding to the above laser processing conditions. By doing so, it is not necessary to unnecessarily increase the amount of carbon or the amount of alloy, and it becomes possible to secure the workability of the material as well. In the case of the steel of the present invention, since the above-mentioned effect is exhibited, the area to be hardened can be widened, and therefore the strength is significantly increased. Therefore, for example, when a member such as a press-molded member is laser-processed only in a necessary portion, the member can have the deformability necessary for maintaining the workability while being processed into the member while maintaining the strength. .
【0032】また成形品の種類によってはプレス成形に
影響を及ばさない部分のみをレーザ照射等によって高強
度化することもあり、そのような場合には、プレス成形
する前にレーザ等の照射を行う方が、平板状態での処理
が可能であるため照射処理性が良好であり、且つ処理材
の特性の信頼性の確保も容易であるから、プレス成形す
る前にレーザ等によって高強度化しても、製品の強度と
プレス成形時の加工性を合わせ持たせることが可能であ
る。Depending on the type of the molded product, only the portion that does not affect the press molding may be strengthened by laser irradiation or the like. In such a case, irradiation of the laser or the like is performed before press molding. Since it is possible to perform the treatment in the flat plate state, it is possible to perform the irradiation treatment, and it is easy to ensure the reliability of the characteristics of the treated material. It is also possible to combine the strength of the product with the workability during press molding.
【0033】[0033]
【実施例】表1に示した成分の材料を溶製し、圧延によ
って1.4mm厚さの板とし、組織調整を行った。特性の
評価はレーザ照射をしていないサンプルと、レーザ照射
をしたサンプルの2種類について行った。特に成形性の
評価は素材の成形性を問題としている為、レーザ照射前
のサンプルについて行った。レーザ照射は直線状に行
い、5mm間隔に3本の照射を行った。なおそのときのレ
ーザ出力は3kw、走査速度は3m/min とし、レーザの
焦点位置を板内として、溶融相が板厚を貫通する状態で
走査した。レーザ照射線が試験片の中央部に位置するよ
うにJIS5号引張試験片を加工して引張試験を行っ
た。[Examples] The materials having the components shown in Table 1 were melted and rolled into a plate having a thickness of 1.4 mm, and the structure was adjusted. The evaluation of the characteristics was performed on two types of samples, a sample not irradiated with laser and a sample irradiated with laser. In particular, since the evaluation of the formability is concerned with the formability of the material, the sample before laser irradiation was performed. Laser irradiation was performed linearly and three irradiations were performed at 5 mm intervals. The laser output at that time was 3 kW, the scanning speed was 3 m / min, the focal position of the laser was within the plate, and scanning was performed with the molten phase penetrating the plate thickness. A JIS No. 5 tensile test piece was processed so that the laser irradiation line was located at the center of the test piece, and a tensile test was performed.
【0034】表2はその試験結果を示すものである。表
2において照射前として示した値はレーザ照射を行わな
い試験片における引張試験の結果であり、また加工性の
指標(r値)はレーザ照射を行わない試験片における試
験結果を示すものである。Table 2 shows the test results. The values shown as “before irradiation” in Table 2 are the results of the tensile test on the test piece not subjected to the laser irradiation, and the workability index (r value) shows the test result on the test piece not subjected to the laser irradiation. .
【0035】[0035]
【表1】 [Table 1]
【0036】[0036]
【表2】 [Table 2]
【0037】鋼28,29はC,Mnが少ない為、レー
ザ処理による強度上層効果が少ない。鋼27はCが多い
為r値が1.1と低い。鋼1,2はTi無添加のアルミ
キルド鋼であるが、やはりC,Mnが少ない為、レーザ
処理による強度上層効果が少ない。図5は発明鋼11の
レーザ照射部の電子顕微鏡写真(15,000倍)を示
すものである。Since the steels 28 and 29 have a small amount of C and Mn, the strength upper layer effect by the laser treatment is small. Steel 27 has a large amount of C and thus has a low r value of 1.1. Steels 1 and 2 are aluminum-killed steels without addition of Ti, but since the amounts of C and Mn are also small, the strength upper layer effect by laser treatment is small. FIG. 5 shows an electron micrograph (15,000 times) of the laser irradiation portion of Invention Steel 11.
【図面の簡単な説明】[Brief description of drawings]
【図1】レーザ照射条件と強度上昇率の関係。FIG. 1 shows the relationship between laser irradiation conditions and intensity increase rate.
【図2】T値と降伏応力の上昇量との関係を示す図。FIG. 2 is a diagram showing a relationship between a T value and an amount of increase in yield stress.
【図3】Nb,Ti添加鋼のC濃度とr値の関係を示す
図。FIG. 3 is a diagram showing the relationship between the C concentration and the r value of Nb and Ti-added steel.
【図4】実施例における加工とレーザ処理を示す図。FIG. 4 is a diagram showing processing and laser processing in an example.
【図5】発明鋼11のレーザ照射部の金属組織を示す図
面代用写真。FIG. 5 is a drawing-substituting photograph showing a metallographic structure of a laser-irradiated portion of Inventive Steel 11.
フロントページの続き (72)発明者 鈴木 裕 愛知県豊田市トヨタ町1番地 トヨタ自動 車株式会社内 (72)発明者 中村 真一郎 愛知県豊田市トヨタ町1番地 トヨタ自動 車株式会社内 (72)発明者 槙井 浩一 兵庫県加古川市金沢町1番地 株式会社神 戸製鋼所加古川製鉄所内 (72)発明者 十代田 哲夫 兵庫県加古川市金沢町1番地 株式会社神 戸製鋼所加古川製鉄所内 (72)発明者 加瀬 友博 兵庫県加古川市金沢町1番地 株式会社神 戸製鋼所加古川製鉄所内Front Page Continuation (72) Inventor Hiroshi Suzuki, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor: Shinichiro Nakamura, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Invention Koichi Makii 1 Kanazawa-machi, Kakogawa-shi, Hyogo Prefecture Kamido Steel Works, Ltd. Kakogawa Steel Works (72) Inventor Tetsuo Tatsuda Kanazawa-machi, Kakogawa City, Hyogo Prefecture Kakogawa Works (72) Invention Tomohiro Kase 1 Kanazawa-cho, Kakogawa-shi, Hyogo Prefecture Kadogawa Steel Works Kakogawa Works
Claims (6)
板厚を貫通した凝固域を形成することにより高強度化し
て使用する、高強度化特性に優れた高加工性鋼板であっ
て、 C :0.002〜0.02%(重量%の意味、以下同
じ) Si:2.0%以下 Mn:0.1〜2.5% を含み、残部がFe及び不可避的不純物よりなり、かつ
フェライトを主体とした組織からなるものであることを
特徴とする、高密度エネルギー源照射処理により優れた
高強度化特性を発揮することを特徴とする高加工性鋼
板。1. A high workability steel sheet having excellent strength-enhancing properties, which is used by increasing the strength by irradiating the surface of the steel sheet with a high-density energy source to form a solidified region penetrating the thickness of the steel sheet. : 0.002 to 0.02% (meaning% by weight, the same applies hereinafter) Si: 2.0% or less Mn: 0.1 to 2.5%, with the balance being Fe and inevitable impurities, and ferrite A high workability steel plate characterized by exhibiting excellent strength-enhancing properties by a high-density energy source irradiation treatment, which is characterized by having a structure mainly composed of.
高加工性鋼板。2. The high workability steel sheet according to claim 1, further comprising, as an alloying element, any one or more of Ti: 0.1% or less and Nb: 0.1% or less.
Si%)×C% の計算式で与えられるT値が0.01以上である請求項
1に記載の高加工性鋼板。3. An alloying element further containing any one or more of P: 0.06 to 0.2% B: 50 ppm or less, and T = (Mn% + 20.P% + 250.B% + 0.25.・
The high workability steel sheet according to claim 1, wherein a T value given by a calculation formula of (Si%) × C% is 0.01 or more.
板厚を貫通した凝固域を形成することにより高強度化し
て使用する、高強度化特性に優れた高加工性鋼板であっ
て、 C :0.005〜0.02% Si:2.0%以下 Mn:1.2〜2.5% P :0.06〜0.2% B :50ppm 以下 を含み、更に、 Ti:0.01〜0.1% Nb:0.005〜0.1%以下 のいずれか1種以上を含むと共に、 T=(Mn%+20・P%+250・B%+0.25・
Si%)×C% の計算式で与えられるT値が0.01以上である請求項
1に記載の高加工性鋼板。4. A high workability steel sheet having excellent strength-enhancing properties, which is used by increasing the strength by irradiating the surface of the steel sheet with a high-density energy source to form a solidified region penetrating the thickness of the steel sheet. : 0.005-0.02% Si: 2.0% or less Mn: 1.2-2.5% P: 0.06-0.2% B: 50ppm or less, and further Ti: 0.01 -0.1% Nb: 0.005-0.1% or less Any one or more types are included, and T = (Mn% + 20 * P% + 250 * B% + 0.25 *).
The high workability steel sheet according to claim 1, wherein a T value given by a calculation formula of (Si%) × C% is 0.01 or more.
板厚を貫通した凝固域を形成することにより高強度化し
て使用する、高強度化特性に優れた高加工性鋼板であっ
て、 C :0.002〜0.02% Si:2.0%以下 Mn:0.1〜2.5% を含み、更に、 Cu:2.5%以下 Ni:1.5%以下 Cr:2.5%以下 Mo:1.0%以下 P :0.15%以下 B :50ppm以下 Nb:0.1%以下 Ti:0.1%以下 Zr:0.1%以下 V :0.1%以下 W :0.1%以下 のいずれか1種以上を含み、残部がFe及び不可避的不
純物よりなり、かつフェライトを主体とした組織からな
るものであることを特徴とする、高密度エネルギー源照
射処理により優れた高強度化特性を発揮することを特徴
とする高加工性鋼板。5. A high workability steel sheet having excellent strength-enhancing properties, which is used by increasing the strength by irradiating the surface of the steel sheet with a high-density energy source to form a solidified region penetrating the thickness of the steel sheet. : 0.002-0.02% Si: 2.0% or less Mn: 0.1-2.5% is included, Furthermore, Cu: 2.5% or less Ni: 1.5% or less Cr: 2.5 % Or less Mo: 1.0% or less P: 0.15% or less B: 50 ppm or less Nb: 0.1% or less Ti: 0.1% or less Zr: 0.1% or less V: 0.1% or less W: Excellent in high-density energy source irradiation treatment, characterized by containing at least one of 0.1% or less, the balance being Fe and unavoidable impurities, and having a structure mainly composed of ferrite. Highly workable steel sheet characterized by exhibiting high strength characteristics.
板厚を貫通した凝固域を形成することにより高強度化し
て使用する、高強度化特性に優れた高加工性鋼板であっ
て、 C :0.002〜0.02% Si:2.0%以下 Mn:0.1〜2.5% を含み、更に、 Ti:0.1%以下 Nb:0.1%以下 の1種以上と、 Cu:2.5%以下 Ni:1.5%以下 Cr:2.5%以下 Mo:1.0%以下 P :0.15%以下 B :50ppm以下 Zr:0.1%以下 V :0.1%以下 W :0.1%以下 のいずれか1種以上を含み、残部がFe及び不可避的不
純物よりなり、かつフェライトを主体とした組織からな
るものであることを特徴とする、高密度エネルギー源照
射処理により優れた高強度化特性を発揮することを特徴
とする高加工性鋼板。6. A high workability steel sheet having excellent strength-enhancing properties, which is used by increasing the strength by irradiating the surface of the steel sheet with a high-density energy source to form a solidified region penetrating the thickness of the steel sheet. : 0.002 to 0.02% Si: 2.0% or less Mn: 0.1 to 2.5% inclusive, and further Ti: 0.1% or less Nb: 0.1% or less , Cu: 2.5% or less Ni: 1.5% or less Cr: 2.5% or less Mo: 1.0% or less P: 0.15% or less B: 50 ppm or less Zr: 0.1% or less V: 0 1% or less W: 0.1% or less Any one kind or more, the balance is Fe and inevitable impurities, and is characterized by having a structure mainly composed of ferrite, high density High strength characterized by exerting excellent strength-enhancing properties by energy source irradiation treatment Sex steel plate.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP23057092A JPH0673439A (en) | 1992-08-28 | 1992-08-28 | High workability steel sheet excellent in high strengthening characteristic by irradiation with high density energy source |
EP93113769A EP0585843A3 (en) | 1992-08-28 | 1993-08-27 | High-formability steel plate with a great potential for strength enhancement by high-density energy treatment |
US08/308,611 US5529646A (en) | 1992-08-28 | 1994-09-19 | Process of Producing high-formability steel plate with a great potential for strength enhancement by high-density energy |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP23057092A JPH0673439A (en) | 1992-08-28 | 1992-08-28 | High workability steel sheet excellent in high strengthening characteristic by irradiation with high density energy source |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0673439A true JPH0673439A (en) | 1994-03-15 |
Family
ID=16909827
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP23057092A Pending JPH0673439A (en) | 1992-08-28 | 1992-08-28 | High workability steel sheet excellent in high strengthening characteristic by irradiation with high density energy source |
Country Status (1)
Country | Link |
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JP (1) | JPH0673439A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012026580A1 (en) | 2010-08-26 | 2012-03-01 | 新日本製鐵株式会社 | Impact absorbing member |
KR20160078676A (en) * | 2014-12-24 | 2016-07-05 | 주식회사 포스코 | Method for manufacturing self-quenched low carbon steel sheet |
-
1992
- 1992-08-28 JP JP23057092A patent/JPH0673439A/en active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012026580A1 (en) | 2010-08-26 | 2012-03-01 | 新日本製鐵株式会社 | Impact absorbing member |
JP5310950B2 (en) * | 2010-08-26 | 2013-10-09 | 新日鐵住金株式会社 | Shock absorbing member |
JPWO2012026580A1 (en) * | 2010-08-26 | 2013-10-28 | 新日鐵住金株式会社 | Shock absorbing member |
KR20160078676A (en) * | 2014-12-24 | 2016-07-05 | 주식회사 포스코 | Method for manufacturing self-quenched low carbon steel sheet |
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