JPS60145384A - Clad steel plate having high fatigue limit ratio and good formability - Google Patents

Abstract

PURPOSE:To produce a clad steel plate having a high fatigue limit ratio and excellent formability by casting a continuous casting billet of the three-phase structure having the inside and outside layers which are different in compsn. by making use of a tundish having two immersion nozzles and rolling the billet. CONSTITUTION:A molten steel 3 contg. 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, <0.005% S and >0.5 Ca/S is poured into the part having a long immersion nozzle 4 of a tundish 2 having a gate 1 at the center and provided with the long immersion nozzle 4 and short immersion nozzle 7 in the bottom and further 1 or >=2 kinds 14 among 0.005- 0.05% Nb, 0.02-2.0% V and 0.005-0.20% Ti are added to the molten steel 6 overflowing the gate 1 to form the molten metal contg. the C increased to 0.03- 0.25%. The molten metals are poured through the respective nozzles 4, 7 into a continuous casting mold 5. The molten metal 6 forms an outside layer 12 and the molten metal 3 forms an inside layer 13. The slab for the clad steel plate having the tensile strength layer in the outside layer than in the inside layer, high fatigue limit ratio and good formability is thus obtd.

Description

【発明の詳細な説明】 （章業上の利用分野） 本発明は自ｌ＠車を始めとする機械構造部材や、−膜加
工用に使用される疲労限度比が高い段成形性クラッド鋼
板に関する。Detailed Description of the Invention (Chapter Field of Application) The present invention relates to step-formable clad steel plates with a high fatigue limit ratio used for mechanical structural members such as automobiles and for membrane processing. .

（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められる傾向が強く、なかで
も自動車のホイールディスクのような過酷な用途に採用
される細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、は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。(Prior art) In recent years, there has been a strong tendency to use steel materials with high strength and fatigue limit ratio compared to unit weight for mechanical and structural components, and among them, steel materials are being used for harsh applications such as automobile wheel discs. Although this tendency is high in thin steel sheets, the fatigue strength of thin steel sheets is generally proportional to the static tensile strength of the steel sheet as a material, 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.

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
イールディ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２− に成功した。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. We succeeded in developing 2-.

而して本発明の先行技術としては、Ｊ　ｊＳ　（）３１
１３　５ＡＰＨ’３８　、５ＡＰＨ’４”５あるいＢ’
　Ｊ　Ｉ　Ｓ″Ｇ３１０１ＳＳ５５などの自動車構造用
熱間圧延鋼板およびｍ帯や一般構造用圧延鋼材がある。As a prior art of the present invention, J jS ()31
13 5APH'38, 5APH'4"5 or B'
There are hot-rolled steel sheets for automobile structures such as JIS''G3101SS55, m-strips, and rolled steel materials for general structures.

（発明の目的） 本発明は、疲労限度比が高くかつプレス加工々ど成形性
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々クラッド鋼板を提
供することを目的とする。(Objective of the invention) The present invention provides a steel plate with a high fatigue limit ratio and excellent formability during 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

（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。(Structure and operation of the invention) The gist of the steel plate according to the present invention is as follows.

即ち、ＣＯ，ＯＯ１５〜０２５係、Ｓｉ０．００３〜２
．０　％、Ｍｎ　０．１−２．０　’Ｚ、　Ａｔ！、、
０．００’０１−０．１％、ＣｃＬｏ、ｏ　００３−０
．ＣＩＯ”７．５％、　Ｓ　Ｏ，００５チ以下を含有し
、かつＣ，／Ｓが０．５　ｗｉ上で残余がＦｅ　および
不可避不純物からなる内層と、Ｃ００３−０，２５％　
、Ｓｉ　０．００３−２．０　％　、Ｍｎ　０．１−２
．０係、　ＡＱ、Ｏ，ＯＯＯ１〜０１係、Ｃ，ｚ　０．
０００３〜０．００’７５チ、Ｓｏ、Ｏ０５係以下に加
えて、３− Ｎｂ　０．０　０　５〜００５係、Ｖｏ、０２〜０２％
、Ｔｉ０００５〜０２０％のうちの１種寸だ１ｄ：２種
以」二を含有し、さらにＣａ／Ｓが０．５１２７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ッド鋼板で
あって、その製造方法としては周知の連続朗造法、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。That is, CO, OO15-025, Si0.003-2
．． 0%, Mn 0.1-2.0'Z, At! ,,
0.00'01-0.1%, CcLo, o 003-0
．． An inner layer containing 7.5% of CIO, 0.05% or less of SO, and with C,/S of 0.5 wi and the remainder consisting of Fe and unavoidable impurities, and 0.25% of C003
, Si 0.003-2.0%, Mn 0.1-2
．． Section 0, AQ, O, OOO1-01 Section, C, z 0.
In addition to 0003~0.00'75 Chi, So, O05 or below, 3-Nb 0.005~005, Vo, 02~02%
, Ti 0005~020% 1d: 2 or more types 1d: contains 2 or more types 2, and has a three-layer structure with Ca/S of 0.5127 and an outer layer consisting of residual Fe and unavoidable impurities. A clad steel plate with good formability and a high fatigue limit ratio characterized by having a tensile strength higher than that of the inner layer, which is produced by a well-known casting method such as continuous casting or ingot casting. The main points are:

まず製造方法の一実施例につき、その概要を図面に従っ
て説明する。First, an outline of an embodiment of the manufacturing method will be explained with reference to the drawings.

第１図は堰１を有するタンディツシュ２内に、図示して
いない取鍋から溶鋼３を注入し、ロンゲイマージョンノ
ズル４からａ１型５内に、丑た堰ｌをオーバーフローし
た溶鋼６を、ジョートイマージョンノズル７から鋳型５
内に注入する要領を示しだもので、ジョートイマージョ
ンノズル７からは、上向き８に溶鋼を噴出さぜ、ロンゲ
イマージョンノズル４からは、溶鋼を下向き９に噴出さ
せる。FIG. 1 shows that molten steel 3 is injected from a ladle (not shown) into a tundish 2 having a weir 1, and the molten steel 6 that has overflowed the weir is transferred from a long immersion nozzle 4 into an A1 type 5. Immersion nozzle 7 to mold 5
This figure shows how to inject molten steel upwards 8 from the jaw immersion nozzle 7, and from the long immersion nozzle 4 downwards 9.

かくて鋳片１０の凝固殻（以下シェルと云う）４− ］、］ハ、ジョートイマージョンノズル７から出だ溶鋼
が、先に凝固した外層１２と、ロンゲイマージョンノズ
ル４を出た溶鋼が凝固した内１４１３とから形成される
こととなる。従って、溶鋼６に図示してい々い合金投入
装置から合金を投入１４すると、内外層の成分が異なっ
た鋳片１０が鋳造できる。In this way, the solidified shell (hereinafter referred to as shell) 4 of the slab 10 is formed by solidifying the molten steel coming out of the jaw immersion nozzle 7, the outer layer 12 which solidified first, and the molten steel coming out of the long immersion nozzle 4 solidifying. It will be formed from 1413 of the above. Therefore, when an alloy is first introduced into the molten steel 6 from the alloy injection device 14, a slab 10 having different compositions in the inner and outer layers can be cast.

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、溶融状態の内層を朗込む手段や、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
造もしくはインゴッ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。In addition to this, there are other casting methods such as pouring a molten inner layer between pre-formed solid outer layers, or conversely casting a molten outer layer around a solid inner layer, such as continuous casting or ingot casting. Also known as law,
In the present invention, either method can be adopted.

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。In the present invention, the slab obtained as described above is hot-rolled into a steel plate (clad steel plate), which has a three-layer structure, and the tensile strength of the outer layer is determined by the tensile strength of the inner layer. The point that the fatigue limit ratio can be increased and good formability can be imparted by increasing the fatigue limit ratio will be explained in more detail.

さて、内外層の成分を変えて特定の目的に適合５− 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。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.

本発明者等も前述のクラッド法を研究し、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２５〜６５　Ｋｇ　ｆ　／ｍＡ　
であることが望ましいことが判明した。即ち２５Ｋｑｆ
／−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、６５Ｋｑｆ／
−以上では加工が困難となり利益を失う。The present inventors 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 were able to create a steel plate with an excellent fatigue limit ratio and good formability. The tensile strength of the inner layer in the present invention is 25 to 65 Kg f /mA.
It turns out that it is desirable that That is 25Kqf
/- or less, it is difficult to manufacture by normal hot rolling and cold rolling processes at the current rolling technology level, and 65Kqf/
- Above this, processing becomes difficult and profits are lost.

次に外層の引張強さは３０〜９５　Ｋｇｆ　／ｍＡ　が
適当で、３０　Ｋｇ　ｆ　／ｍＡ　以下では強度が不足
し、９５Ｋｇｆ／πｊ　以上では加工劣化が生ずるほか
、それだけの強度を出すだ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
〜３ｏＫｑｆ／−程度が好ましい結果が得られる。Next, the appropriate tensile strength of the outer layer is 30 to 95 Kgf/mA; if it is less than 30 Kgf/mA, the strength will be insufficient, and if it is more than 95 Kgf/πj, processing deterioration will occur, and additional elements will not be required to achieve that strength. Costs increase and economic efficiency is lost. That is, the difference in tensile strength between the inner and outer layers is 5
A preferable result can be obtained at about 3oKqf/-.

前述の物理的特性を付与するだめの成分特定の６一 実例について述べると、フェライト−パーライト鋼では
引張強さくＴＳ　）は ＴＳ　（ｈｆ／ｍ、ａ）　＝　２９．６　＋２．７６　
（％Ｍｎ）　＋　８．３　（％Ｓ　１　）＋０．３９２
（％ｐｅａｒ１ｉｔｅ）＋０．７’７ｄ−”＋２５０（
％Ｎｂ）＋２００（係Ｔｉ　）　＋１５０　（係■）た
だし　ｄ：フェライト粒径（關） 低炭素ベイナイト鋼では ＴＳ（Ｋｒｆ／＋＋＋ｎ）＝２５．１＋１９４（％ｃ）
＋２３．５（％Ｍｎ　）＋３９（％■十％Ｔｉ） を用いた。To describe 6 examples of identifying the components that impart the above-mentioned physical properties, the tensile strength (TS) of ferrite-pearlite steel is TS (hf/m, a) = 29.6 + 2.76
(%Mn) + 8.3 (%S 1 ) + 0.392
(%pear1ite)+0.7'7d-”+250(
%Nb) + 200 (Ti) + 150 (Ti) However, d: Ferrite grain size (Ti) For low carbon bainite steel, TS (Krf/+++n) = 25.1 + 194 (%c)
+23.5(%Mn)+39(%■10%Ti) was used.

而して、本発明の鋼板を鋳込圧延クラッド法で製造した
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、疲労クラックが界面で発生し
難く、従っ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ックの発生を抑制し疲労強度を
高くし得る。Therefore, when the steel sheet of the present invention is manufactured by the cast-rolled cladding method, compared to a clad steel sheet manufactured by the crimping method, the bonding state at the interface between the inner and outer layers is better, 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.

第２図は本発明にかかる鋼板（鋳込圧延法）について、
内外層境界面の光学顕微鏡組織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。Figure 2 shows the steel plate (cast rolling method) according to the present invention.
This shows the optical microscopic structure of the interface between the inner and outer layers, and there is no intervening oxide or the like at the boundary, and the structure is extremely healthy.

７− 次に本発明にかかる好適なりラッド率について説。7- Next, the preferred rad ratio according to the present invention will be explained.

明する。I will clarify.

第３図は、第１表に示す成分の鋳片を、約５＝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。Figure 3 shows the relationship between crud ratio and fatigue limit ratio (σW/σB) when slabs with the composition shown in Table 1 are hot-rolled to about 5 and then surface polished to change the crud ratio. shows.

疲労試吟は平面曲げ両振りで１０７回まで行い、このと
きの５−Ｎ１１ｌｌ線から疲労限度σＷをめた。Fatigue testing was performed up to 107 times with plane bending in both directions, and the fatigue limit σW was determined from the 5-N11ll line at this time.

またσＢは、各クラツド率における引張強さである。Moreover, σB is the tensile strength at each cladding ratio.

このクラツド鋼の内層部引張強さは、約４０Ｋｇｆ／”
ｍＡ、外層部引張強さは６０　Ｋｑ　ｆ　／ｍＡであっ
た。寸だ、クラツド率は、外層硬化部と内層軟化部の遷
移領域中の光学脂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８− で示しだ。The inner layer tensile strength of this clad steel is approximately 40Kgf/”
mA, and the tensile strength of the outer layer was 60 Kq f /mA. 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 with 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. .

本発明者等の研究では、外層厚は絶対値で０、０５０　
ｍｓ　（片側のみでは０．０２５　ｍｓ　）以上で著し
い効果が見られ、壕だクラツド率で２５係を超えると効
果が飽和することが留められる。In the research conducted by the present inventors, the outer layer thickness is 0.050 in absolute value.
A remarkable effect is seen above ms (0.025 ms on one side only), and the effect is not saturated when the clad ratio exceeds 25.

第４図は、第３図と同じ鋼のクラツド率と応力振幅３２
　Ｋｑｆ／ｍＡ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。Figure 4 shows the cladding ratio and stress amplitude 32 of the same steel as in Figure 3.
The relationship between Kqf/mA and durability life is shown. As is clear from the figure, the durability life is significantly improved as the cladding ratio increases.

次に本発明にかかる成分の限定理由について説明する。Next, the reasons for limiting the components according to the present invention will be explained.

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係朱満て
は製鋼作業が困難になる。また、０２５チを超えると、
溶接性が劣化するので０．００１５〜０．２５％の範囲
とした。First, regarding the components of the inner layer, it is better to have less C in order to improve workability, but if the C content is less than 0.0015, it becomes difficult to make steel. Also, if it exceeds 025chi,
Since weldability deteriorates, the content is set in the range of 0.0015 to 0.25%.

Ｍｎ　は固溶強化およびフェライトの細粒化のために必
要な元素であるが、０．１係未満では高張力儒が得に＜
＜、熱間脆性が生じやすい。まだ、２係を超えると、溶
接性を劣化させるので０．１〜＝９− ２．０係の範囲とした。Mn is an element necessary for solid solution strengthening and grain refinement of ferrite, but when the coefficient is less than 0.1, high tensile strength is particularly low.
<, hot brittleness is likely to occur. If the ratio exceeds 2, the weldability deteriorates, so the range was set at 0.1 to 9-2.0.

Ｓｌ　は延性を損うことなく、固溶強化によって強度を
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係以下としだ。壕だ、Ｓｌは必要に応じて添加
すればよく、不可避不純物として台筐れる程度でも差支
えないので、下限は０００３係とする。Sl can increase strength by solid solution strengthening without impairing ductility, but if it exceeds 2%, weldability deteriorates, so it should be kept at a modulus of 2 or less. However, Sl may be added as necessary, and there is no problem even if it remains as an unavoidable impurity, so the lower limit is set at 0003.

ＡＱはフェライトの細粒化に有効であるが、Ｃ１係を超
えると、その効果は飽和するので０１％以下とする。寸
だ、不可避不純物として含捷れる程度でも差支えないの
で、下限は０．０００１　％とする。AQ is effective in refining the grains of ferrite, but if it exceeds the C1 coefficient, the effect is saturated, so it is set to 01% or less. The lower limit is set at 0.0001%, since there is no problem even if it is included as an unavoidable impurity.

次にＣ６は、Ｏ，ＯＯＯ３％以下では介在物球状化の効
果がなく、０．ＯＯ’ｉ’５％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
か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％以下としだ。またＣ、／Ｓを
０５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。Next, C6 has no effect on inclusion spheroidization when O, OOO is 3% or less, and 0. If OO'i' exceeds 5%, cluster-like inclusions will occur, which will easily cause nozzle clogging during casting work during the steelmaking process, and will also have a negative effect on the workability of the product, so it should be kept below 0.0075%. . Further, the reason why C and /S are set to 05 or more is that below this value, inclusions are not sufficiently spheroidized and the effect of improving workability is reduced.

１０− 次に外層成分について述べる。Ｃ，Ｓｉ、Ｍｎ。10- Next, the outer layer components will be described. C, Si, Mn.

ＡＩ！、ＣｃＬ　のうち、Ｓｊ　、　Ｍｎ　、　ＡＩ’
、　、　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。したがってＣの範囲＊　ｏ、　０３〜０２５係と
する。AI! , CcL, Sj, Mn, AI'
, , Ca may be in the same component range as the inner layer. but,
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*o is set as 03-025.

壕だ、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，Ｓｌ。However, the reinforcing effect of Nb, V, and Ti added to the outer layer is small below the lower limit, and saturates above the upper limit, so upper and lower limits were set for each. In addition to Nb, Ti, and V added to the outer layer, C and Sl were added to the outer layer.

Ｍｎ　量を各制限範囲内で内層より多くしても差支えな
い。There is no problem even if the amount of Mn is greater than that of the inner layer within each limit range.

またＣ４／Ｓを０５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。The reason why C4/S is set to 05 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.

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。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 hot rolling was performed after continuous casting are shown in Table 2.

＠ＦＴＩＡ　、　Ｂ　、　Ｃは比較鋤で圧延１捷の均一
成分鋼板であり、σＷ／σＢｊｄ０．４３〜０４４であ
る。Ｊは均一成分の比較鋼であるが、研磨仕上材のだめ
σＷ／σＢが０．５１と、圧延１捷よりやや高い。Ｄ〜
王は本発明鋼で、表層にＮｂ、Ｔｉ、Ｖが単独まだは複
合添加されており、Ｄは研磨仕上材のだめσＷ／σＢが
０．６’７．Ｅ〜工は圧延まま材でσＷ／σＢが０．５
６〜０５７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。@FTIA, B, and C are uniform component steel plates that have been rolled in one round using a comparative plow, and have a σW/σBjd of 0.43 to 044. J is a comparison steel with a uniform composition, but the polished finish σW/σB is 0.51, which is slightly higher than that of the one-roll rolling process. D~
King is the invention steel, to which Nb, Ti, and V are added singly or in combination to the surface layer, and D is a polished material with σW/σB of 0.6'7. E ~ processing is as-rolled material with σW/σB of 0.5
6 to 057, both higher than the comparative steel. Figure 5 shows the relationship between fatigue limit and tensile strength.

（発明の効果） 本発明によって低強度で疲労強度の高い鋼板が得られる
。このだめ、たとえばプレス成形が容易な低強度鋼板で
、ホイールディ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。捷た、
これ頃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。(Effects of the Invention) According to the present invention, a steel plate with low strength and high fatigue strength can be obtained. For example, by using a low-strength steel plate that can be easily press-formed, it is possible to reduce the thickness of the wheel disc, which has the effect of making it easier to reduce the weight and cost of the wheel. I cut it,
Nowadays, it has industrial value that can equally be applied to steel plates that require high fatigue strength for processing.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の鋼板を連続踏造法によって製造する概
略説明図、第２図１／ｌ１１：クラツド鋼板の境界面の
光学顕微璋写真（倍率］−〇〇倍）、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３２　Ｋ９ｆ／−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＼の引張強さと疲
労限度の関係を示す図表である。 ｌ・・・堰　２・・・タンディツシュ ３・・・溶＠　４・・・ロングイマージョ５・・・鋳型
　ンノズル ６・・・溶鋼　７・・・ジョートイマージ１０・・・鋳
片　ヨンノズル ｌ］−・・・凝固殻　１２・・・外層 １３・・・内層 第３　回 クラツド率（勢） ０　（０，０５０ｍｍ１　Ｉｏ　２０　３０クラツト′
卑　（うも〕 第５図 引張１５に晩）　（ｋ！ｆ／ｍｍジ 手続補正書（方式） ％式％ １事件の表示　昭和５９年特許願第　９０５　号２発明
の名称　疲労限度比が、軒い良成形性りラッド金面４反
３補正をする者　事件との関係　特許出願人性　所　東
京都千代田区大手町２丁目６番３号名　称　（６６５）
　新日本製鐵株式上針代表者　武　１）　豊 ４代　理　人 住　所　東京都中央区日本橋３丁目３番３号加藤ビル４
Ｆ 氏　名　（６１９３）弁理士　茶野木　立　夫５補正命
令の日付　昭和５９年３　月２７日（発送日）６補正に
より増加する発明の数 １　明細書７頁］８行「光学顕微鏡組織」を「金属組織
の拡大模式図」に補正する。 ２　同］、　４．　’ｌ”ｊ：　１１行〜］２行の［第
２図はクラツド鋼板の境界面の光学顕微鏡写真（倍率１
００倍）、］を「第２図は本発明の境界面の金属組織の
模式図、」に補正する。 ５　第２図を別紙の通り補正する。 −］− 境＊面 一　４７つ−Fig. 1 is a schematic explanatory diagram of manufacturing the steel plate of the present invention by the continuous rolling method, Fig. 2: 1/11: Optical micrograph of the interface of the clad steel plate (magnification] - x x), Fig. 3 is Chart showing the relationship between cladding ratio and fatigue limit ratio (σW/σB), No. 4
The figure is a chart showing the relationship between cladding ratio and durability life at a stress amplitude of 32K9f/-, and Figure 5 is a chart showing the relationship between hot-rolled tensile strength and fatigue limit. l...Weir 2...Tandish 3...Melting @ 4...Long Immersion 5...Mold Nozzle 6...Molten Steel 7...Jaw Toy Image 10...Slab Long Nozzle l]- ... Solidified shell 12 ... Outer layer 13 ... Inner layer 3rd crud rate (force) 0 (0,050 mm1 Io 20 30 crat'
Figure 5 Tensile 15 to Night) (k!f/mm Procedural Amendment (Method) % Formula % 1 Display of Case Patent Application No. 905 of 1988 2 Name of Invention The fatigue limit ratio is Person who corrects the eave moldability and 4-sided 3-sided metal surface of the rad metal surface Relationship to the case Patent applicant Location 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (665)
Nippon Steel Corporation stock representative Takeshi 1) Yutaka 4th generation Osamu Address Kato Building 4, 3-3-3 Nihonbashi, Chuo-ku, Tokyo
F Name (6193) Patent attorney Tatsuo Chanoki Date of 5th amendment order March 27, 1980 (shipment date) Number of inventions increased by 6th amendment 1 Specification page 7] Line 8 "Optical microscopic structure" Correct to "enlarged schematic diagram of metal structure". 2 same], 4. 'l''j: Line 11~] Line 2 [Figure 2 is an optical micrograph of the interface of the clad steel plate (magnification 1
00 times), ] is corrected to "Figure 2 is a schematic diagram of the metal structure of the interface of the present invention." 5 Correct Figure 2 as shown in the attached sheet. - ] - Border * One side 47 pieces -

Claims (1)

【特許請求の範囲】 ＣＯ，００１５〜０．２５愛、Ｓｉ０．００３〜２，０
係Ｍｎ　０．１−２．０　％　、　ＡＱ　Ｏ，０００１
〜０．１％Ｃａ　０．０００３〜０．００７５係、Ｓｏ
、００５％以下を含有し、かつＣ，／Ｓが０５以上で、
残余がＦｅおよび不可避不純物からなる内層と； Ｃ０，０３〜０２５％、　Ｓｊ、０．００３〜２０％Ｍ
ｎ　Ｏ，１−２，Ｏ％　、　Ａ１１０．０００１−０．
１％ＣｃＬＯ，０００３−０．００７５％、　Ｓｏ、０
０５％以下に加えて、 Ｎｂ　Ｏ，００５〜００５係、　Ｖｏ、０２〜・０２ヂ
Ｔｉ　０．００５〜０．２０係 のうちの１種寸だけ２種以」二を含有し、さらにｃ　ａ
　／ｓが０５以上で残余Ｆ”ｅ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′よシ高くしたことを特徴とする疲労限度比が高
い段成形性クラッド鋼板。 １−[Claims] CO, 0015~0.25A, Si0.003~2,0
Mn 0.1-2.0%, AQ O,0001
~0.1%Ca 0.0003~0.0075, So
, 005% or less, and C,/S is 05 or more,
Inner layer with remainder consisting of Fe and unavoidable impurities; C0.03~025%, Sj, 0.003~20%M
nO,1-2,O%, A110.0001-0.
1%CcLO,0003-0.0075%, So,0
In addition to 0.05% or less, Nb O, 005 to 005, Vo, 02 to 02, Ti 0.005 to 0.20.
/s is 05 or more and has a three-layer structure with an outer layer consisting of residual F"e and unavoidable impurities, and has a high fatigue limit ratio characterized in that the tensile strength of the outer layer is higher than that of the inner layer. Formable clad steel plate. 1-