JPS643662B2 - - Google Patents
Info
- Publication number
- JPS643662B2 JPS643662B2 JP90584A JP90584A JPS643662B2 JP S643662 B2 JPS643662 B2 JP S643662B2 JP 90584 A JP90584 A JP 90584A JP 90584 A JP90584 A JP 90584A JP S643662 B2 JPS643662 B2 JP S643662B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- tensile strength
- outer layer
- less
- steel plate
- 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 50
- 239000010959 steel Substances 0.000 claims description 50
- 239000012535 impurity Substances 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 239000010410 layer Substances 0.000 description 40
- 238000005253 cladding Methods 0.000 description 13
- 238000000034 method Methods 0.000 description 13
- 230000000694 effects Effects 0.000 description 10
- 238000007654 immersion Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 238000005266 casting Methods 0.000 description 6
- 238000009749 continuous casting Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 229910052719 titanium Inorganic materials 0.000 description 5
- 229910052720 vanadium Inorganic materials 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910052758 niobium Inorganic materials 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 238000002788 crimping Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009661 fatigue test Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/007—Continuous casting of metals, i.e. casting in indefinite lengths of composite ingots, i.e. two or more molten metals of different compositions being used to integrally cast the ingots
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Pressure Welding/Diffusion-Bonding (AREA)
- Laminated Bodies (AREA)
Description
（産業上の利用分野）
本発明は自動車を始めとする機械構造部材や、
一般加工用に使用される疲労限度比が高い良成形
性クラツド鋼板に関する。
（従来技術）
近時、機械部材や構造部材では、単重に比して
強度および疲労限度比の高い鋼材が求められる傾
向が強く、なかでも自動車のホイールデイスクの
ような過酷な用途に採用される鋼板においてその
傾向が高いが、一般に薄鋼板の疲労強度は、ほぼ
素材鋼板の静的引張強さに比例するので、疲労強
度の高い鋼板を得るため高張力化が促進されて来
た。しかしながら、前述の高張力化はとかくコス
ト高になり易く、製造方法も必らずしも容易では
ないと云う問題点がある。
そこで本発明者等は、高張力化を計るのではな
く、疲労強度が高く、プレス成形性の良好な鋼
板、即ち前述のホイールデイスクに適した鋼板の
開発に努力し、本発明のクラツド鋼板を開発する
ことに成功した。
而して本発明の先行技術としては、JIS G3113
SAPH38、 SAPH45あるいはJIS G3101 SS55
などの自動車構造用熱間圧延鋼板および鋼帯や一
般構造用圧延鋼材がある。
（発明の目的）
本発明は、疲労限度比が高くかつプレス加工な
ど成形性の優れた鋼板、即ち自動車構造用や一般
構造用の用途において、低コストで塑性加工が可
能なクラツド鋼板を提供することを目的とする。
（発明の構成・作用）
本発明にかかる鋼板の要旨は下記の通りであ
る。即ち、C0.0015〜0.25％、Si0.003〜2.0％、
Mn0.1〜2.0％、Al0.0001〜0.1％、Ca0.0003〜
0.0075％、S0.005％以下を含有し、かつCa／Ｓが
0.5以上で残余がFeおよび不可避不純物からなる
内層と、C0.03〜0.25％、Si0.003〜2.0％、Mn0.1
〜2.0％、Al0.0001〜0.1％、Ca0.0003〜0.0075％、
S0.005％以下に加えて、Nb0.005〜0.05％、V0.02
〜0.2％、Ti0.005〜0.20％のうちちの１種または
２種以上を含有し、さらにCa／Ｓが0.5以上で残
余Feおよび不可避不純物からなる外層とで三層
構造とし、外層の引張強さを内層の引張強さより
高くしたことを特徴とする疲労限度比が高い良成
形性クラツド鋼板であつて、その製造方法として
は周知の連続鋳造法、造塊法など鋳造方法による
ことを要点とするものである。
まず製造方法の一実施例につき、その概要を図
面に従つて説明する。
第１図は堰１を有するタンデイツシユ２内に、
図示していない取鍋から溶鋼３を注入し、ロング
イマージヨンノズル４から鋳型５内に、また堰１
をオーバーフローした溶鋼６を、シヨートイマー
ジヨンノズル７から鋳型５内に注入する要領を示
したもので、シヨートイマージヨンノズル７から
は、上向き８に溶鋼を噴出させ、ロングイマージ
ヨンノズル４からは、溶鋼を下向き９に噴出させ
る。
かくて鋳片１０の凝固殼（以下シエルと云う）
１１は、シヨートイマージヨンノズル７から出た
溶鋼が、先に凝固した外層１２と、ロングイマー
ジヨンノズル４を出た溶鋼が凝固した内層１３と
から形成されることとなる。従つて、溶鋼６に図
示していない合金投入装置から合金を投入１４す
ると、内外層の成分が異なつた鋳片１０が鋳造で
きる。
而して鋳造方法としては、このほかあらかじめ
成形された固体外層間に、溶融状態の内層を鋳込
む手段や、逆に固体内層を溶融状態外層で鋳ぐる
む手段などが、連続鋳造もしくはインゴツト鋳造
法などとして知られており、本発明ではいずれの
方法も採用することが出来る。
本発明は、前述のようにして得られた鋳片を、
熱間圧延して鋼板（クラツド鋼板）とするもので
あるが、このような三層構成とし、外層の引張り
強さを内層の引張強さより高くすることにより疲
労限度比を高くし、良成形性を付与しうる点につ
き、さらに詳細に説明する。
さて、内外層の成分を変えて特定の目的に適合
したクラツド鋼板を製造すると云う技術手段は周
知であり、ステンレスクラツド鋼板などが特に良
く知られている。
本発明者等も前述のクラツド法を研究し、内外
層の引張り強さを変えることと、それらをそれぞ
れ特定の成分とすることにより、目的とする疲労
限度比が優れ、良成形性の鋼板を得ると云う新知
見を得たもので、本発明における内層の引張強さ
は25〜65Kgｆ／mm2であることが望ましいことが判
明した。即ち25Kgｆ／mm2以下では、現在の圧延技
術水準における通常の熱延、冷延工程で製造する
ことは困難であり、65Kgｆ／mm2以上では加工が困
難となり利益を失う。
次に外層の引張強さは30〜95Kgｆ／mm2が適当
で、30Kgｆ／mm2以下では強度が不足し、95Kgｆ／
mm2以上では加工劣化が生ずるほか、それだけの強
度を出すための添加元素コストが高くなり経済性
を失う。即ち前記内外層の引張強さの差は、５〜
30Kgｆ／mm2程度が好ましい結果が得られる。
前述の物理的特性を付与するための成分特定の
実例について述べると、フエライト−パーライト
鋼では引張強さ（TS）は
TS（Kgｆ／mm2）＝29.6＋2.76（％Mn）＋8.3（％Si）＋
0.392（％pearlite）＋0.77d-1/2＋250（％Nb）＋200（
％Ti）
＋150（％Ｖ）
ただしｄ：フエライト粒径（mm）
低炭素ベイナイト鋼では
TS（Kgｆ／mm2）＝25.1＋194（％ｃ）＋23.5（％Mn）＋
39（％Ｖ＋％Ti）
を用いた。
而して、本発明の鋼板を鋳込圧延クラツド法で
製造した場合、圧着法で製造したクラツド鋼板に
比し、内外層の界面の接合状態が良好で、疲労ク
ラツクが界面で発生し難く、従つて外層成分を硬
度の高いものとし、その引張強さを高くして初期
クラツクの発生を抑制し疲労強度を高くし得る。
第２図は本発明にかかる鋼板（鋳込圧延法）に
ついて、内外層境界面の金属組織の拡大模式図を
示すものであるが、その境界には酸化物等の介在
がなく、組織は極めて健全である。
次に本発明にかかる好適なクラツド率について
説明する。
第３図は、第１表に示す成分の鋳片を、約５mm
に熱延後、表面研磨してクラツド率を変化させた
ときのクラツド率と、疲労限度比（σW／σB）の
関係を示す。
疲労試験は平面曲げ両振りで107回まで行い、
このときのＳ−Ｎ曲線から疲労限度σWを求め
た。またσBは、各クラツド率における引張強さ
である。
(Industrial Application Field) The present invention is applicable to mechanical structural members such as automobiles,
This invention relates to a clad steel plate with good formability and a high fatigue limit ratio used for general processing. (Prior art) In recent years, there has been a strong tendency for mechanical and structural components to require steel materials with high strength and fatigue limit ratio compared to unit weight, and steel materials are being used for harsh applications such as automobile wheel discs. However, in general, the fatigue strength of thin steel sheets is approximately proportional to the static tensile strength of the material steel sheet, so increasing the tensile strength has been promoted in order to obtain steel sheets with high fatigue strength. However, there are problems in that the above-mentioned increase in tension tends to increase costs and the manufacturing method is not necessarily easy. Therefore, instead of aiming to increase the tensile strength, the present inventors made efforts to develop a steel plate with high fatigue strength and good press formability, that is, a steel plate suitable for the above-mentioned wheel disc, and created the clad steel plate of the present invention. succeeded in developing it. As the prior art of the present invention, JIS G3113
SAPH38, SAPH45 or JIS G3101 SS55
There are hot-rolled steel plates and strips for automobile structures, such as hot-rolled steel sheets and strips for automobile structures, and rolled steel materials for general structures. (Objective of the Invention) The present invention provides a steel plate with a high fatigue limit ratio and excellent formability such as press working, that is, a clad steel plate that can be plastic-formed at low cost for use in automobile structures and general structures. The purpose is to (Structure and operation of the invention) The gist of the steel plate according to the invention is as follows. That is, C0.0015~0.25%, Si0.003~2.0%,
Mn0.1~2.0%, Al0.0001~0.1%, Ca0.0003~
Contains 0.0075%, S0.005% or less, and Ca/S
The inner layer is 0.5 or more and the remainder consists of Fe and unavoidable impurities, C0.03~0.25%, Si0.003~2.0%, Mn0.1
~2.0%, Al0.0001~0.1%, Ca0.0003~0.0075%,
In addition to S0.005% or less, Nb0.005~0.05%, V0.02
~0.2%, Ti0.005~0.20%, and an outer layer consisting of Ca/S of 0.5 or more, residual Fe, and unavoidable impurities, and the tensile strength of the outer layer is It is a clad steel plate with good formability and a high fatigue limit ratio, characterized by having a tensile strength higher than the tensile strength of the inner layer, and the main point is that it is produced by a casting method such as a well-known continuous casting method or an ingot method. It is something to do. First, an outline of an embodiment of the manufacturing method will be explained with reference to the drawings. Figure 1 shows a tundish 2 with a weir 1.
Molten steel 3 is poured from a ladle (not shown) into the mold 5 through the long immersion nozzle 4, and into the weir 1.
This figure shows how to inject the overflowing molten steel 6 into the mold 5 from the short immersion nozzle 7. From the short immersion nozzle 7, the molten steel is spouted upward 8, and from the long immersion nozzle 4. The molten steel is spouted downward 9. Thus, the solidified shell of slab 10 (hereinafter referred to as shell)
11 is formed of an outer layer 12 in which the molten steel discharged from the short immersion nozzle 7 has solidified first, and an inner layer 13 in which the molten steel discharged from the long immersion nozzle 4 has solidified. Therefore, by charging 14 an alloy into the molten steel 6 from an alloy charging device (not shown), a slab 10 having different components in the inner and outer layers can be cast. In addition, there are other casting methods such as casting an inner layer in a molten state between pre-formed solid outer layers, or conversely casting a solid inner layer with a molten outer layer, such as continuous casting or ingot casting. Both methods can be adopted in the present invention. The present invention uses the slab obtained as described above,
The steel plate (clad steel plate) is hot-rolled and has a three-layer structure, with the tensile strength of the outer layer being higher than that of the inner layer, which increases the fatigue limit ratio and improves formability. The points that can be given will be explained in more detail. Now, the technical means of manufacturing a clad steel sheet suitable for a specific purpose by changing the composition of the inner and outer layers is well known, and stainless steel clad steel sheets are particularly well known. The present inventors have also studied the above-mentioned cladding method, and by changing the tensile strength of the inner and outer layers and making them each have specific components, we can create a steel plate with an excellent fatigue limit ratio and good formability. Based on the new knowledge obtained, it has been found that the tensile strength of the inner layer in the present invention is desirably 25 to 65 Kgf/mm 2 . That is, if it is less than 25 Kgf/mm 2 , it is difficult to manufacture it by normal hot rolling or cold rolling processes at the current rolling technology level, and if it is more than 65 Kgf/mm 2 , it becomes difficult to process and profits are lost. Next, the appropriate tensile strength of the outer layer is 30 to 95Kgf/ mm2 , and if it is less than 30Kgf/mm2, the strength is insufficient, and 95Kgf/ mm2 or less is insufficient.
If it exceeds mm 2 , processing deterioration will occur, and the cost of added elements to produce that much strength will increase, making it uneconomical. That is, the difference in tensile strength between the inner and outer layers is 5 to
A preferable result can be obtained at about 30 Kgf/mm 2 . To give an example of specifying components to impart the above-mentioned physical properties, in ferrite-pearlite steel, the tensile strength (TS) is TS (Kgf/mm 2 ) = 29.6 + 2.76 (%Mn) + 8.3 ( %Si)＋
0.392 (%pearlite) + 0.77d -1/2 +250 (%Nb) + 200 (
%Ti)
+150 (%V) where d: Ferrite grain size (mm) For low carbon bainite steel, TS (Kgf/mm 2 ) = 25.1 + 194 (%c) + 23.5 (%Mn) +
39 (%V+%Ti) was used. Therefore, when the steel plate of the present invention is manufactured by the cast-rolled cladding method, the bonding condition at the interface between the inner and outer layers is better than that of the cladding steel plate manufactured by the crimping method, and fatigue cracks are less likely to occur at the interface. Therefore, by making the outer layer component high in hardness and increasing its tensile strength, it is possible to suppress the occurrence of initial cracks and increase fatigue strength. Figure 2 shows an enlarged schematic view of the metal structure at the interface between the inner and outer layers of the steel sheet according to the present invention (cast rolling method). It is healthy. Next, a suitable cladding ratio according to the present invention will be explained. Figure 3 shows a slab of about 5mm thick with the ingredients shown in Table 1.
Figure 3 shows the relationship between the cladding ratio and the fatigue limit ratio (σW/σB) when the cladding ratio is varied by surface polishing after hot rolling. Fatigue tests were conducted up to 10 7 times with plane bending on both sides.
The fatigue limit σW was determined from the S-N curve at this time. Moreover, σB is the tensile strength at each cladding ratio.
【表】
このクラツド鋼の内層部引張強さは、約40Kg
ｆ／mm2、外層部引張強さは60Kgｆ／mm2であつた。
また、クラツド率は、外層硬化部と内層軟化部の
遷移領域中の光学顕微鏡で識別できる境界を、外
層〜内層の境界として、両外層部厚みの全厚に対
する割合で示した。
本発明者等の研究では、外層厚は絶対値で
0.050mm（片側のみでは0.025mm）以上で著しい効
果が見られ、またクラツド率で25％を超えると効
果が飽和することが認められる。
第４図は、第３図と同じ鋼のクラツド率と応力
振幅32Kgｆ／mm2の耐久寿命の関係を示す。図から
明らかなように、クラツド率の増加と共に、耐久
寿命が著しく向上している。
次に本発明にかかる成分の限定理由について説
明する。
まず内層の成分について述べると、Ｃは加工性
を向上させるためには少ない方がよいが、0.0015
％未満では製鋼作業が困難になる。また、0.25％
を超えると、溶接性が劣化するので0.0015〜0.25
％の範囲とした。
Mnは固溶強化およびフエライトの細粒化のた
めに必要な元素であるが、0.1％未満では高張力
鋼が得にくく、熱間脆性が生じやすい。また、２
％を超えると、溶接性を劣化させるので0.1〜2.0
％の範囲とした。
Siは延性を損なうことなく、固溶強化によつて
強度を増すことができるが、２％を超えると溶接
性が劣化するので、２％以下とした。また、Siは
必要に応じて添加すればよく、不可避不純物とし
て含まれる程度でも差支えないので、下限は
0.003％とする。
Alはフエライトの細粒化に有効であるが、0.1
％を超えると、その効果は飽和するので0.1％以
下とする。また、不可避不純物として含まれる程
度でも差支えないので、下限は0.0001％とする。
次にCaは、0.0003％以下では介在物球状化の効
果がなく、0.0075％を超えるとクラスター状介在
物が発生し、製鋼工程中の鋳造作業時にノズル詰
りが起り易くなるとともに、製品の加工性にも悪
影響を及ぼすので、0.0075％以下とした。また
Ca／Ｓを0.5以上とする理由は、これ以下では介
在物球状化が充分でなく、加工性改善効果が小さ
くなるからである。
次に外層成分について述べる。Ｃ、Si、Mn、
Al、Caのうち、Si、Mn、Al、Caは内層と同じ
成分範囲でよい。しかし、Ｃのみは外層強度を高
める目的から0.03％以上とする。したがつてＣの
範囲は0.03〜0.25％とする。
また、外層に添加するNb、Ｖ、Tiは下限以下
では強化の効果が小さく、上限以上では飽和する
ので、それぞれの上限、下限を設定した。なお、
Nb、Ti、Ｖの外層添加に加えて、外層のＣ、
Si、Mn量を各制限範囲内で内層より多くしても
差支えない。
またCa／Ｓを0.5以上とする理由は、内層の場
合と等しく、これ以下では介在物球状化による加
工性改善効果が小さくなるためである。
而して、本発明は、前述の通り分塊法もしくは
連続鋳造により鋼片としたものを直接圧延する
か、あるいは途中軽加熱して圧延しても良く、さ
らに温間、あるいは冷間で加熱炉に装入し圧延し
ても良い。
実施例
連続鋳造後熱延した本発明の実施例を第２表に
示す。
鋼Ａ，Ｂ，Ｃは比較鋼で圧延ままの均一成分鋼
板であり、σW／σBは0.43〜0.44である。Ｊは均
一成分の比較鋼であるが、研磨仕上材のため
σW／σBが0.51と、圧延ままよりやや高い。Ｄ〜
Ｉは本発明鋼で、表層にNb、Ti、Ｖが単独また
は複合添加されており、Ｄは研磨仕上材のため
σW／σBが0.67、Ｅ〜Ｉは圧延まま材でσW／σB
が0.56〜0.57と、いずれも比較鋼より高い。第５
図は疲労限度と引張強度の関係を示す。[Table] The inner layer tensile strength of this clad steel is approximately 40Kg.
f/mm 2 , and the tensile strength of the outer layer was 60 Kgf/mm 2 .
Further, the cladding ratio is expressed as the ratio of the thickness of both outer layers to the total thickness, with the boundary that can be identified by an optical microscope in the transition region between the hardened outer layer and the softened inner layer as the boundary between the outer layer and the inner layer. In our research, the outer layer thickness is expressed as an absolute value.
A significant effect is seen at 0.050 mm (0.025 mm on one side only) or more, and the effect is saturated when the cladding rate exceeds 25%. FIG. 4 shows the relationship between the cladding ratio and the durability life of the same steel as in FIG. 3 with a stress amplitude of 32 Kgf/mm 2 . As is clear from the figure, the durability life is significantly improved as the cladding ratio increases. Next, the reasons for limiting the components according to the present invention will be explained. First, regarding the components of the inner layer, it is better to have less C in order to improve workability, but 0.0015
If it is less than %, steel making work becomes difficult. Also, 0.25%
If it exceeds 0.0015 to 0.25, weldability will deteriorate.
% range. Mn is a necessary element for solid solution strengthening and grain refinement of ferrite, but if it is less than 0.1%, it is difficult to obtain high tensile strength steel and hot embrittlement tends to occur. Also, 2
If it exceeds 0.1 to 2.0%, weldability deteriorates.
% range. Si can increase the strength by solid solution strengthening without impairing ductility, but if it exceeds 2%, weldability deteriorates, so it was set to 2% or less. In addition, Si can be added as necessary, and there is no problem even if it is included as an unavoidable impurity, so the lower limit is
It shall be 0.003%. Al is effective for refining ferrite, but 0.1
If it exceeds 0.1%, the effect will be saturated, so it should be 0.1% or less. Further, since it is acceptable even if it is included as an unavoidable impurity, the lower limit is set to 0.0001%. Next, if Ca is less than 0.0003%, it will not have the effect of spheroidizing inclusions, and if it exceeds 0.0075%, cluster-like inclusions will occur, which will easily cause nozzle clogging during casting work during the steelmaking process, and will improve the workability of the product. Since it has a negative effect on Also
The reason why Ca/S is set to 0.5 or more is that if it is less than this, inclusions are not sufficiently spheroidized, and the effect of improving workability becomes small. Next, the outer layer components will be described. C, Si, Mn,
Among Al and Ca, Si, Mn, Al, and Ca may have the same composition range as the inner layer. However, only C is set at 0.03% or more for the purpose of increasing the strength of the outer layer. Therefore, the range of C is 0.03 to 0.25%. Further, Nb, V, and Ti added to the outer layer have a small strengthening effect below the lower limit, and are saturated above the upper limit, so upper and lower limits were set for each. In addition,
In addition to adding Nb, Ti, and V to the outer layer, C,
There is no problem even if the amount of Si and Mn is larger than that of the inner layer within each limit range. The reason why Ca/S is set to 0.5 or more is that, as in the case of the inner layer, if it is less than this, the effect of improving workability due to spheroidization of inclusions becomes small. Therefore, as mentioned above, the present invention may be performed by directly rolling a steel billet by the blooming method or continuous casting, or by lightly heating it during rolling, and by further heating it warmly or coldly. It may be charged into a furnace and rolled. Examples Examples of the present invention in which continuous casting and hot rolling were performed are shown in Table 2. Steels A, B, and C are comparative steels that are as-rolled uniform composition steel plates, and σW/σB is 0.43 to 0.44. J is a comparative steel with uniform composition, but because it is a polished material, σW/σB is 0.51, which is slightly higher than that of as-rolled steel. D~
I is the steel of the present invention, to which Nb, Ti, and V are added singly or in combination to the surface layer, D is a polished material with a σW/σB of 0.67, and E to I are as-rolled materials with a σW/σB of 0.67.
is 0.56 to 0.57, both higher than the comparative steel. Fifth
The figure shows the relationship between fatigue limit and tensile strength.
【表】【table】
【表】
（発明の効果）
本発明によつて低強度で疲労強度の高い鋼板が
得られる。このため、たとえばプレス成形が容易
な低強度鋼板で、ホイールデイスクの厚み減少が
可能となり、ホイールの軽量化・低コスト化が容
易となる効果を持つ。また、これ以外に加工用の
高疲労強度を必要とする鋼板に等しく適用できる
工業的価値がある。[Table] (Effects of the Invention) According to the present invention, a steel plate with low strength and high fatigue strength can be obtained. Therefore, it is possible to reduce the thickness of the wheel disc by using, for example, a low-strength steel plate that is easy to press-form, which has the effect of making it easier to reduce the weight and cost of the wheel. In addition to this, it has industrial value that can equally be applied to steel plates that require high fatigue strength for processing.
第１図は本発明の鋼板を連続鋳造法によつて製
造する概略説明図、第２図は本発明の境界面の金
属組織の模式図、第３図はクラツド率と疲労限度
比（σW／σB）の関係を示す図表、第４図は応力
振幅32Kgｆ／mm2でのクラツド率と耐久寿命の関係
を示す図表、第５図は熱延まゝの引張強さと疲労
限度の関係を示す図表である。
１……堰、２……タンデイツシユ、３……溶
鋼、４……ロングイマージヨンノズル、５……鋳
型、６……溶鋼、７……シヨートイマージヨンノ
ズル、１０……鋳片、１１……凝固殼、１２……
外層、１３……内層。
Fig. 1 is a schematic explanatory diagram of manufacturing the steel plate of the present invention by continuous casting method, Fig. 2 is a schematic diagram of the metallographic structure of the interface of the present invention, and Fig. 3 is the cladding ratio and fatigue limit ratio (σW/ Figure 4 is a diagram showing the relationship between cladding ratio and durability life at a stress amplitude of 32Kgf/ mm2 , Figure 5 is a diagram showing the relationship between hot-rolled tensile strength and fatigue limit. It is. 1... Weir, 2... Tandate, 3... Molten steel, 4... Long immersion nozzle, 5... Mold, 6... Molten steel, 7... Short immersion nozzle, 10... Slab, 11... ...Coagulation shell, 12...
Outer layer, 13...inner layer.
Claims (1)
よび不可避不純物からなる内層と； C0.03〜0.25％、Si0.003〜2.0％ Mn0.1〜2.0％、Al0.0001〜0.1％ Ca0.0003〜0.0075％、S0.005％以下 に加えて、 Nb0.005〜0.05％、V0.02〜0.2％ Ti0.005〜0.20％ のうちの１種または２種以上を含有し、さらに
Ca／Ｓが0.5以上で残余Feおよび不可避不純物か
らなる外層とで三層構成とし、外層の引張強さを
内層の引張強さより高くしたことを特徴とする疲
労限度比が高い良成形性クラツド鋼板。[Claims] 1 Contains 0.0015-0.25% C, 0.003-2.0% Si, 0.1-2.0% Mn, 0.0001-0.1% Al, 0.0003-0.0075% Ca, and 0.005% or less of S, and An inner layer with Ca/S of 0.5 or more, with the remainder consisting of Fe and unavoidable impurities; C0.03~0.25%, Si0.003~2.0% Mn0.1~2.0%, Al0.0001~0.1% Ca0.0003~0.0075 %, S0.005% or less, contains one or more of Nb0.005~0.05%, V0.02~0.2%, Ti0.005~0.20%, and further
Good formability clad steel plate with high fatigue limit ratio, characterized by having a three-layer structure with Ca/S of 0.5 or more and an outer layer consisting of residual Fe and unavoidable impurities, and the tensile strength of the outer layer is higher than that of the inner layer. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP90584A JPS60145384A (en) | 1984-01-09 | 1984-01-09 | Clad steel plate having high fatigue limit ratio and good formability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP90584A JPS60145384A (en) | 1984-01-09 | 1984-01-09 | Clad steel plate having high fatigue limit ratio and good formability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60145384A JPS60145384A (en) | 1985-07-31 |
| JPS643662B2 true JPS643662B2 (en) | 1989-01-23 |
Family
ID=11486692
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP90584A Granted JPS60145384A (en) | 1984-01-09 | 1984-01-09 | Clad steel plate having high fatigue limit ratio and good formability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60145384A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0794112B2 (en) * | 1986-09-22 | 1995-10-11 | 株式会社日立製作所 | Master / slave manipulator |
| DE102008022709A1 (en) * | 2008-05-07 | 2009-11-19 | Thyssenkrupp Steel Ag | Use of a metallic composite material in a vehicle structure |
| JP6631162B2 (en) * | 2015-10-30 | 2020-01-15 | 日本製鉄株式会社 | Continuous casting method and continuous casting apparatus for multilayer slab |
-
1984
- 1984-01-09 JP JP90584A patent/JPS60145384A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60145384A (en) | 1985-07-31 |
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