JP2827740B2 - Method for producing steel sheet with excellent fatigue characteristics and deep drawability - Google Patents
Method for producing steel sheet with excellent fatigue characteristics and deep drawabilityInfo
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- JP2827740B2 JP2827740B2 JP23230292A JP23230292A JP2827740B2 JP 2827740 B2 JP2827740 B2 JP 2827740B2 JP 23230292 A JP23230292 A JP 23230292A JP 23230292 A JP23230292 A JP 23230292A JP 2827740 B2 JP2827740 B2 JP 2827740B2
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Description
【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【0001】[0001]
【産業上の利用分野】本発明は、優れた深絞り成形性と
疲労特性とを兼備えた冷延鋼板、溶融亜鉛めっき鋼板並
びに合金化溶融亜鉛めっき鋼板などの鋼板の製造方法に
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing steel sheets, such as cold-rolled steel sheets, hot-dip galvanized steel sheets and alloyed hot-dip galvanized steel sheets, having both excellent deep drawability and fatigue properties.
【0002】[0002]
【従来の技術】従来から、薄鋼板に高い成形性を付与す
る手法としては、極低炭素鋼にTi,Nb等の炭・窒化
物形成元素を添加してC,Nを析出固定したIF(In
terstitial Free)鋼が知られている。
このようなIF鋼を前提とした成形性に優れた冷延鋼板
及び溶融亜鉛めっき鋼板に関する技術が、例えば特開平
2−34722号、特開平1−225727号に開示さ
れている。近年、自動車車体の形状が複雑化してきてい
るため、IF鋼のように非常に優れた加工性を有してい
る鋼板でなければ加工できない部品が急増しており、I
F鋼が自動車用鋼板の素材として広く用いられている。2. Description of the Related Art Conventionally, as a technique for imparting high formability to a thin steel plate, an IF (carbon and nitride forming element such as Ti, Nb, etc. added to ultra-low carbon steel to precipitate and fix C and N). In
Tertiary Free steel is known.
Techniques relating to such cold-rolled steel sheets and hot-dip galvanized steel sheets having excellent formability based on the IF steel are disclosed in, for example, JP-A-2-34722 and JP-A-1-225727. In recent years, since the shape of automobile bodies has become more complicated, the number of parts that cannot be machined unless steel sheets having extremely excellent workability, such as IF steel, are increasing rapidly.
F steel is widely used as a material for steel plates for automobiles.
【0003】一方、疲労強度を必要とし、かつ深絞り成
形を受けるような部品には、従来から低炭素アルミキル
ド鋼が使用されているが、低炭素アルミキルド鋼の成形
性はIF鋼のそれには及ばない。こうした背景から、疲
労特性および深絞り成形性ともに優れた鋼板が要望され
ている。[0003] On the other hand, low carbon aluminum killed steel is conventionally used for parts requiring fatigue strength and subjected to deep drawing, but the formability of low carbon aluminum killed steel is inferior to that of IF steel. Absent. From such a background, a steel sheet excellent in both fatigue characteristics and deep drawability has been demanded.
【0004】[0004]
【発明が解決しようとする課題】従来のIF鋼では、特
開平1−225727号や特開平2−34722号など
のように、高r値を達成するための手段としてC,Nを
十分析出固定するにたるTi,Nbを含有させること、
およびAc3 変態点を越えない範囲で高温焼鈍すること
を行っている。確かに、これらの方法によれば、高r値
を得ることはできる。しかし、これらの技術は、専ら高
r値を達成するためのものにすぎず、疲労特性の改善を
意図したものではない。In the conventional IF steel, C and N are sufficiently precipitated as a means for achieving a high r value as disclosed in Japanese Patent Application Laid-Open Nos. 1-225727 and 2-34722. Containing Ti, Nb for fixing;
And high-temperature annealing within a range not exceeding the Ac 3 transformation point. Certainly, according to these methods, a high r value can be obtained. However, these techniques are only for achieving a high r-value and are not intended to improve fatigue properties.
【0005】この発明は、かかる事情に鑑みてなされた
ものであって、優れた深絞り成形性を有し、かつ低炭素
アルミキルド鋼板に匹敵する疲労特性を有する鋼板の製
造方法を提供することを目的とする。The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a steel sheet having excellent deep drawing formability and having fatigue characteristics comparable to low carbon aluminum killed steel sheets. Aim.
【0006】[0006]
【課題を解決するための手段及び作用】本発明者らは、
かかる目的を達成するために研究を進めてきた結果、軟
質薄鋼板の疲労強度は材料の降伏強度が高いほど高くな
るという知見を得た。したがって、IF鋼を用いて、高
r値を確保した上で、この降伏強度を上昇させることが
できれば、深絞り性とともに疲労特性にも優れた鋼板を
製造することができるはずである。一般に、深絞り性を
損なうことなく、降伏強度を上昇させるには、焼鈍後に
おける結晶粒の粒径を小さくすることが有効である。本
発明者らは、鋭意研究の結果、鋼中にBを添加すると、
その再結晶温度が上昇し、結晶粒を微細化することがで
き、また、焼鈍温度の上限をSi,Mn,P,Bなどの
元素の添加量によって規定することにより、プレス成形
が可能な降伏強度を達成し、しかも疲労特性を上昇させ
ることができるということを新たに見い出した。Means and Action for Solving the Problems The present inventors have
As a result of researching to achieve such an object, it has been found that the fatigue strength of a soft thin steel plate increases as the yield strength of the material increases. Therefore, if the yield strength can be increased while securing a high r value using IF steel, a steel sheet excellent in deep drawability and fatigue characteristics should be able to be manufactured. Generally, to increase the yield strength without impairing the deep drawability, it is effective to reduce the grain size of the crystal grains after annealing. The present inventors have assiduously studied and, when B is added to steel,
The recrystallization temperature rises, the crystal grains can be refined, and the upper limit of the annealing temperature is defined by the amount of addition of elements such as Si, Mn, P, and B, so that the yield that can be press-formed is obtained. It has been newly found that strength can be achieved and fatigue characteristics can be increased.
【0007】この発明に係る疲労特性及び深絞り性に優
れた鋼板の製造方法は、重量%で、C:0.0050%
以下、Si:0.2%以下、Mn:0.10〜0.5
%、P:0.03%以下、S:0.015%以下、so
l.Al:0.10%以下、N:0.0040%以下、
B:0.0001〜0.0020%を含有し、さらに
0.005〜0.10%のTiと0.005〜0.03
0%のNbの1種又は2種を含有する鋼を熱間圧延し、
酸洗後圧下率60%以上90%以下で冷間圧延し、再結
晶温度以上でかつ、6(10Si+0.5Mn+100
P+800B+14)+710で規定される温度以下で
焼鈍し、疲労限を26.1kgf/mm 2 以上とし、か
つ、下式で与えられる平均ランクフォード(r)値を
1.70以上ととしすることを特徴とする。r=(r 0 +2r 45 +r 90 )/4 ただし、r 0 ,r 45 ,r 90 は圧延方向に対してそれぞれ
0°,45°,90°から採取した試験片を用いて求め
たランクフォード値である。 鋼板の疲労限を26.1k
gf/mm 2 以上とすることが優れた疲労特性を得るう
えで重要である。また、鋼板の平均ランクフォード
(r)値を1.70以上とることが優れた深絞り性を得
るうえで重要である。本発明の方法により製造された鋼
板(番号1〜30)が疲労限と平均ランクフォード
(r)値とのバランスが良好であり、両者ともに高い値
を示すことは、表5および表6に示す結果から明らかで
ある。このように疲労特性及び深絞り性に優れた鋼板を
得るためには、本発明の如く鋼材の成分組成と製造条件
とのバランスの良い組合わせが必要となる。 The fatigue characteristics and deep drawability according to the present invention are excellent.
The production method of the obtained steel sheet is C: 0.0050% by weight%.
Hereinafter, Si: 0.2% or less, Mn: 0.10 to 0.5
%, P: 0.03% or less, S: 0.015% or less, so
l. Al: 0.10% or less, N: 0.0040% or less,
B: 0.0001 to 0.0020%, and
0.005 to 0.10% Ti and 0.005 to 0.03
Hot rolling a steel containing one or two types of 0% Nb,
After pickling, cold-rolled at a draft of 60% or more and 90% or less, and re-solidified
Above the crystallization temperature and 6 (10Si + 0.5Mn + 100
P + 800B + 14) +710 or lower
AnnealingAnd the fatigue limit is 26.1 kgf / mm Two Or more
And the average Rankford (r) value given by
1.70 or moreWhenTo doIt is characterized by the following.r = (r 0 + 2r 45 + R 90 ) / 4 Where r 0 , R 45 , R 90 Is for each rolling direction
Determined using test pieces taken from 0 °, 45 °, and 90 °
Rankford value. 26.1k fatigue limit of steel plate
gf / mm Two Above is to obtain excellent fatigue properties
Is important. Also, the average rank Ford of steel sheet
(R) The value of 1.70 or more provides excellent deep drawability.
Is important for Steel produced by the method of the present invention
Plates (numbers 1 to 30) are fatigue-limited and average Rankford
Good balance with (r) value, both are high values
Is apparent from the results shown in Tables 5 and 6.
is there. A steel sheet with excellent fatigue characteristics and deep drawability
In order to obtain, the composition of steel and the manufacturing conditions as in the present invention
And a well-balanced combination is required.
【0008】さらに、表面に溶融亜鉛めっき層を被成し
てもよい。この場合は、溶融亜鉛めっき層中のFe含有
量が5〜15%であることが望ましい。また、このよう
な亜鉛めっき層の表面に、さらにFe含有量が50%以
上のFe−Zn合金めっき層を被成してもよい。次に、
本発明の鋼成分を上記のように限定する理由について述
べる。 C: Cは高r値を達成するためには低い方がよいが、
実用上本発明の効果を損なわない範囲として、その上限
を0.0050%とした。Further, a hot-dip galvanized layer may be formed on the surface. In this case, the content of Fe in the hot-dip galvanized layer is preferably 5 to 15%. Further, a Fe—Zn alloy plating layer having an Fe content of 50% or more may be further formed on the surface of such a zinc plating layer. next,
The reason for limiting the steel composition of the present invention as described above will be described. C: C should be low to achieve a high r value,
The upper limit is set to 0.0050% as long as the effect of the present invention is not practically impaired.
【0009】Si: Siは強化元素として、鋼板の降
伏強度および引張強度の上昇に寄与して、疲労強度の向
上に有効な元素であるが、0.2%を越えて含有する
と、鋼板のr値が劣化するばかりか、溶融亜鉛めっきの
密着性を著しく悪化させるため、その上限を0.2%と
した。Si: Si is a strengthening element that contributes to the increase in the yield strength and tensile strength of a steel sheet and is effective for improving the fatigue strength. Not only the value deteriorates, but also the adhesion of hot-dip galvanized coating deteriorates remarkably, so the upper limit is made 0.2%.
【0010】Mn: MnもSiと同様に、鋼板の強度
上昇に対して寄与するが、0.10%未満ではその効果
がほとんどなく、0.50%を越えて添加すると、鋼板
のAc3 変態点を低下させ、最適焼鈍温度範囲が狭くな
るばかりか、鋼板のr値を低下させるため、0.10〜
0.50%の範囲とした。Mn: Like Mn, Mn also contributes to an increase in the strength of the steel sheet. However, if it is less than 0.10%, there is almost no effect, and if it exceeds 0.50%, the Ac 3 transformation of the steel sheet occurs. In order to lower the point and not only narrow the optimum annealing temperature range, but also lower the r-value of the steel sheet,
The range was 0.50%.
【0011】P: Pは、最も安価に鋼を強化できる
が、0.03%を越えて含有すると、溶融亜鉛めっきの
合金化反応を極端に遅らせ、合金化ムラ等の欠陥の原因
となるばかりか、鋼板のr値を低下させるため、上限を
0.03%に限定した。P: P can strengthen steel at the lowest cost, but if it is contained in excess of 0.03%, the alloying reaction of hot-dip galvanizing is extremely slowed down, and it only causes defects such as uneven alloying. Alternatively, the upper limit was limited to 0.03% in order to lower the r value of the steel sheet.
【0012】S: Sは鋼板の延性を劣化させるため、
できる限り低減したほうが望ましい。しかし、実用上本
発明の効果を損なわない範囲として、その上限を0.0
15%とした。 sol.Al: Alは脱酸のために必要であるが、あ
まり多量に添加するとコストの上昇を招くため、その上
限を0.10%とした。 N: Nは高r値を得るためには、少ないほうが望まし
い。そのため、0.0040%以下とした。S: S deteriorates the ductility of the steel sheet.
It is desirable to reduce as much as possible. However, as a range that does not impair the effect of the present invention practically, the upper limit is 0.0
15%. sol. Al: Al is necessary for deoxidation, but adding too much increases the cost, so the upper limit was made 0.10%. N: N is preferably as small as possible to obtain a high r value. Therefore, the content is set to 0.0040% or less.
【0013】Ti: Tiは鋼中の固溶C,Nを析出物
として固定し、高r値を得るために添加される。すなわ
ち、0.005%未満ではその効果がなく、0.100
%を越えて含有してもその効果が飽和し、コスト上昇を
招くため、Ti含有量を0.005〜0.100%の範
囲とした。Ti: Ti is added in order to fix solid solution C and N in steel as precipitates and obtain a high r value. That is, if the content is less than 0.005%, the effect is not obtained.
%, The effect is saturated and the cost is increased. Therefore, the Ti content is set in the range of 0.005 to 0.100%.
【0014】Nb: NbもTiと同様に高r値を得る
ために添加される。すなわち、0.005%未満ではそ
の効果がなく、0.030%を越えて含有すると鋼の延
性を著しく低下させるため、Nb含有量を0.005〜
0.030%の範囲とした。Nb: Nb is also added to obtain a high r value like Ti. That is, if the content is less than 0.005%, the effect is not obtained. If the content exceeds 0.030%, the ductility of the steel is significantly reduced.
The range was 0.030%.
【0015】B: Bは本発明において最も重要な添加
元素の1つである。つまり、B添加によって再結晶温度
が上昇し、細粒が得られるのである。すなわち、Bは
0.0001%未満ではその効果が得られず、0.00
20%を越えるとr値が著しく低下するため、B含有量
を0.0001〜0.0020%の範囲とした。次に、
本発明の製造条件を上記のように限定した理由について
述べる。B: B is one of the most important additive elements in the present invention. That is, the recrystallization temperature is increased by the addition of B, and fine grains are obtained. That is, if B is less than 0.0001%, the effect cannot be obtained, and
When the content exceeds 20%, the r value is significantly reduced. Therefore, the B content is set in the range of 0.0001 to 0.0020%. next,
The reason why the manufacturing conditions of the present invention are limited as described above will be described.
【0016】熱間圧延工程は、常法にて行えばよい。す
なわち、連続鋳造によって得られたスラブを加熱処理を
施した後熱間圧延を行う方法でも、高温鋳片のまま圧延
機に直送されたスラブをそのまま熱間圧延する方法でも
よい。得られた熱延鋼帯を常法にて酸洗し、圧下率60
%以上90%以下の条件下で冷間圧延する。圧下率60
%未満では、高r値が得られないため、その下限を60
%に定めた。また、圧下率90%以上で圧延しても、r
値の上昇に対して効果がなくなるばかりか、圧延時の圧
延機に対する負荷が大きくなるため、その上限を90%
に定めた。The hot rolling step may be performed by a conventional method. That is, a method of performing hot rolling after subjecting a slab obtained by continuous casting to a heat treatment, or a method of directly hot rolling a slab directly sent to a rolling mill as a high-temperature slab may be used. The hot-rolled steel strip thus obtained was pickled by a conventional method, and the rolling reduction was 60%.
Cold rolling under the condition of not less than 90% and not more than 90%. Reduction rate 60
%, A high r value cannot be obtained.
%. Further, even if the rolling is performed at a rolling reduction of 90% or more, r
Not only is there no effect on the increase in the value, but the load on the rolling mill during rolling increases, so the upper limit is 90%.
Determined.
【0017】冷間圧延後の焼鈍は、再結晶温度以上で行
うことが肝要である。また、焼鈍温度の上限を6(10
Si+0.5Mn+100P+800B+14)+71
0の式で得られる値とすることが肝要である。本発明者
らは、このような温度範囲で鋼板を焼鈍することによ
り、深絞り成形性に優れ、かつ疲労特性にも優れた薄鋼
板を製造できるという知見を得た。以下に、本発明にお
いて焼鈍温度を上記のように定めた理由について説明す
る。It is important that annealing after cold rolling be performed at a temperature higher than the recrystallization temperature. The upper limit of the annealing temperature is set to 6 (10
Si + 0.5Mn + 100P + 800B + 14) +71
It is important to use a value obtained by the equation of 0. The present inventors have found that by annealing a steel sheet in such a temperature range, a thin steel sheet having excellent deep drawability and excellent fatigue properties can be manufactured. Hereinafter, the reason for setting the annealing temperature as described above in the present invention will be described.
【0018】C:0.0020%、Si:tr〜0.3
%、Mn:0.1〜0.8%、P:0.003〜0.0
3%、S:0.010%、sol.Al:0.055
%、N:0.0025%、Ti:0.005〜0.10
%、Nb:0.005〜0.035%、B:tr〜0.
0030%の組成の鋼を溶解し、得られたスラブを12
50℃で加熱した後に、熱間圧延して板厚を4.0mm
とし、640℃でコイルに巻き取った。酸洗後、0.8
mmまで冷間圧延し、700〜900℃の範囲で連続焼
鈍を行った。焼鈍板を0.5%の調質圧延をし、これか
ら試験片を採取して機械試験および軸引張疲労試験を行
った。疲労試験は、部分片振り条件で行ない、繰り返し
速度は20Hzで行なった。以降、本発明における引張
疲労試験は前記条件下で行なった。C: 0.0020%, Si: tr to 0.3
%, Mn: 0.1 to 0.8%, P: 0.003 to 0.0
3%, S: 0.010%, sol. Al: 0.055
%, N: 0.0025%, Ti: 0.005 to 0.10
%, Nb: 0.005 to 0.035%, B: tr to 0.
0030% of steel was melted and the resulting slab was
After heating at 50 ° C., the sheet was hot-rolled to a thickness of 4.0 mm.
And wound up at 640 ° C. on a coil. 0.8 after pickling
mm, and continuously annealed in the range of 700 to 900 ° C. The annealed plate was subjected to a temper rolling of 0.5%, and a test piece was taken therefrom and subjected to a mechanical test and an axial tensile fatigue test. The fatigue test was performed under partial pulsating conditions, and the repetition rate was 20 Hz. Hereinafter, the tensile fatigue test in the present invention was performed under the above conditions.
【0019】図1に降伏強度と疲労限との関係を示す。
図から明らかなように、疲労限は降伏強度で整理でき、
降伏強度の高い材料ほど疲労限は高くなることが判明し
た。この結果から、疲労特性に優れ、しかも深絞り性の
高い材料を得るためには、成形性の許される範囲内で、
できる限り降伏強度の高い材料を製造しなければならな
いことがわかる。FIG. 1 shows the relationship between yield strength and fatigue limit.
As is clear from the figure, the fatigue limit can be arranged by the yield strength,
It was found that the higher the yield strength, the higher the fatigue limit. From these results, in order to obtain a material with excellent fatigue characteristics and high deep drawability, within the allowable range of formability,
It is understood that a material having as high a yield strength as possible must be manufactured.
【0020】図2は、横軸に焼鈍温度をとり、縦軸に鋼
板の降伏強度およびr値をとって、それぞれの関係につ
いて調べた結果を示すプロット図である。ここで、r値
としては、圧延方向に対して0°,45°,90°から
採取した試験片で求めた値、r0 ,r45,r90を用いて
下記の数式で示される平均r値を採用した。なお、図中
にて、丸は降伏強度の結果をプロットしたものであり、
三角は平均r値の結果をプロットしたものである。FIG. 2 is a plot showing the relationship between the annealing temperature on the horizontal axis and the yield strength and r value of the steel sheet on the vertical axis. Here, as the r value, a value obtained from test pieces taken from 0 °, 45 °, and 90 ° with respect to the rolling direction, r 0 , r 45 , and r 90 are used. The value was adopted. In the figures, circles are plots of the results of yield strength,
The triangle is a plot of the result of the average r value.
【0021】[0021]
【数1】 なお、図1及び図2に示した鋼板の化学成分を表1に示
す。(Equation 1) Table 1 shows the chemical components of the steel sheets shown in FIGS.
【0022】[0022]
【表1】 [Table 1]
【0023】図2から明らかなように、焼鈍温度の上昇
とともに、平均r値は大きくなるが、その反面降状強度
が低下するため、疲労特性の良好な範囲の降伏強度を保
持しながら、平均r値も高くするためには、焼鈍温度に
ある上限値が存在する。その上限値を種々の化学成分の
鋼のSi,Mn,P,Bの添加量によって重回帰分析を
行った結果、図3に示すような関係が得られたのであ
る。すなわち、焼鈍温度の上限値は、6(10Si+
0.5Mn+100P+800B+14)+710の数
式で与えられることが判明した。As is apparent from FIG. 2, the average r value increases as the annealing temperature increases, but on the other hand, the yield strength decreases. Therefore, the average r value is maintained while maintaining the yield strength within a good range of fatigue characteristics. In order to increase the r value, there is an upper limit of the annealing temperature. As a result of performing multiple regression analysis on the upper limit value based on the addition amounts of Si, Mn, P, and B of steels of various chemical components, a relationship as shown in FIG. 3 was obtained. That is, the upper limit of the annealing temperature is 6 (10Si +
0.5Mn + 100P + 800B + 14) +710.
【0024】上記の焼鈍工程を溶融亜鉛めっきラインで
行い、溶融亜鉛めっきを施しても本発明の効果を損なう
ことはなく、製品に防錆性が要求される場合は、溶融亜
鉛めっきを施す。また、溶接性などの特性が要求される
場合は、450〜550℃程度の温度で合金化処理を行
う。また、プレス成形性がとくに要求される場合には、
めっき皮膜上層にFe含有率が50%以上のFe−Zn
合金めっきを施すことで摩擦係数が低下し、成形性が大
きく向上する。得られた鋼板には、必要に応じて0.5
〜1.5%程度の調質圧延を行い、製品とする。また、
冷延鋼板表面にZn系めっきを電気めっきにより施して
も本発明の効果を何ら損なうものではない。このよう
に、本発明の鋼板は、疲労特性及び深絞り性に優れてお
り、しかも安価に、安定に製造することができる。The effect of the present invention is not impaired even if the above annealing step is performed in a hot-dip galvanizing line and hot-dip galvanizing is performed. If the product is required to have rustproofing properties, hot-dip galvanizing is applied. When characteristics such as weldability are required, alloying is performed at a temperature of about 450 to 550 ° C. When press formability is particularly required,
Fe-Zn with Fe content of 50% or more on the plating film
By applying the alloy plating, the coefficient of friction is reduced, and the formability is greatly improved. In the obtained steel sheet, if necessary, 0.5
Perform temper rolling of about 1.5% to obtain a product. Also,
Even if Zn-based plating is applied to the surface of the cold-rolled steel sheet by electroplating, the effect of the present invention is not impaired at all. Thus, the steel sheet of the present invention has excellent fatigue characteristics and deep drawability, and can be manufactured stably at low cost.
【0025】[0025]
【実施例】以下、本発明の実施例について、さらに詳細
に説明する。 (実施例1)EXAMPLES Examples of the present invention will be described below in more detail. (Example 1)
【0026】表2に示す成分の鋼を溶製し、1250℃
に加熱した後に、これを熱間圧延して板厚を4.0mm
とし、620℃でコイルに巻き取った。得られた熱延鋼
帯を酸洗後、0.8mmまで冷間圧延し、780℃で連
続焼鈍した後、溶融亜鉛めっきを施した。その後、50
0℃で合金化処理を行った後、0.5%の調質圧延を行
い、製品とした。得られた鋼板より、引張試験片および
疲労試験片を採取して、試験に供した。A steel having the composition shown in Table 2 was melted,
And then hot-rolled to a thickness of 4.0 mm.
And wound up at 620 ° C. on a coil. After pickling, the obtained hot-rolled steel strip was cold-rolled to 0.8 mm, continuously annealed at 780 ° C., and then subjected to hot-dip galvanizing. Then 50
After alloying at 0 ° C., temper rolling of 0.5% was performed to obtain a product. From the obtained steel plate, a tensile test piece and a fatigue test piece were sampled and subjected to a test.
【0027】その結果を図4に示す。図中にて、丸は降
伏強度を、三角は平均r値をそれぞれ示す。図から明ら
かなように、Bの添加により、降伏強度が上昇し、同時
に疲労限も上昇する。しかし、B添加量が0.0020
%を越えると、降伏強度は上昇するが、平均r値は著し
く低下することが判明した。FIG. 4 shows the result. In the figure, circles indicate the yield strength, and triangles indicate the average r value. As is clear from the figure, the addition of B increases the yield strength and at the same time increases the fatigue limit. However, the amount of B added is 0.0020.
%, It has been found that the yield strength increases but the average r-value significantly decreases.
【0028】[0028]
【表2】 (実施例2)[Table 2] (Example 2)
【0029】表3及び表4に示す成分の鋼を溶製し、1
150〜1250℃の温度で加熱した後、熱間圧延して
板厚を4.0mmとし、500〜680℃の温度範囲で
コイルに巻き取った。酸洗後、0.8mmまで冷間圧延
し、650〜900℃の範囲で連続焼鈍を行った後、調
圧を施して製品としたもの、焼鈍後に溶融亜鉛めっきを
施した後に450〜550℃の温度で合金化処理を施し
たもの、さらに亜鉛めっき皮膜の上層にFe−Zn合金
めっきを施したものについて、機械試験および軸引張疲
労試験を行った。なお、溶融亜鉛めっきの付着量は60
/60g/m2 とした。また、上層めっき付着量は3g
/m2 とした。さらに、溶融亜鉛めっきを施したものに
ついては、耐パウダリング性を調べるため、ドロービー
ド試験を行った。なお、片面当たりの剥離量5g/m2
以上を不良とした。The steels having the components shown in Tables 3 and 4 were melted, and 1
After heating at a temperature of 150-1250 ° C, hot rolling
The plate thickness is set to 4.0 mm, and in the temperature range of 500 to 680 ° C.
Wound on a coil. Cold rolling to 0.8mm after pickling
After performing continuous annealing in the range of 650 to 900 ° C.,
Product by applying pressure, hot-dip galvanized after annealing
After the application, the alloying treatment is performed at a temperature of 450 to 550 ° C.
Fe-Zn alloy on the zinc plating film
Mechanical test and axial tensile fatigue
A labor test was performed. The amount of hot-dip galvanized coating was 60
/ 60g / mTwo And The upper layer plating adhesion amount is 3g.
/ MTwo And In addition, to hot-dip galvanized
In order to determine the powdering resistance,
Test. In addition, the peeling amount per one side is 5 g / m.Two
The above was regarded as defective.
【0030】その結果を表5及び表6に示す。本発明鋼
においては、いずれも疲労限が高く、しかも高い平均r
値が得られている。例えば、鋼材番号1〜30の鋼板で
は疲労限がいずれも26. 1kgf/mm 2 以上と高
く、疲労特性に優れたものとなっている。とくに鋼材番
号1,5〜8,11,17,22,28,29の鋼板で
は28. 0kgf/mm 2 以上という高い疲労限が得ら
れた。また、鋼材番号1〜30の鋼板では平均r値がい
ずれも1. 70以上と高く、深絞り性に優れたものとな
っているるし。とくに鋼材番号1,3,12,14,1
7〜21,23〜27,29,30の鋼板では1. 85
以上という高い平均r値が得られた。これに比して、比
較鋼31はBが添加されていないため疲労限が低く、比
較鋼32はBが過剰に添加されているため平均r値が低
下して深絞り性が劣化している。また、比較鋼33及び
41は焼鈍温度が高いため疲労限が低く、比較鋼42は
焼鈍温度が再結晶温度以下のため平均r値が低下してい
る。比較鋼34,35,36はそれぞれC,Si,Mn
が多いため平均r値が低下している。また、比較鋼37
ではPが高いため平均r値が低下するばかりか、めっき
密着性も劣化している。さらに、比較鋼38はNbが高
いため平均r値が低下して深絞り性が劣化し、比較鋼3
9はTi,Nb無添加のため平均r値が低下して深絞り
性が劣化している。また、さらに、比較鋼40はNが多
いため平均r値が低下して深絞り性が劣化している。The results are shown in Tables 5 and 6. All of the steels of the present invention have a high fatigue limit and a high average r.
Values have been obtained. For example, in steel plate of steel number 1-30
Has a fatigue limit of 26.1 kgf / mm 2 or more
And have excellent fatigue characteristics. Especially steel material number
No. 1,5-8,11,17,22,28,29
Has a high fatigue limit of 28.0 kgf / mm 2 or more.
Was. Further, the average r value is not large in the steel sheets of steel numbers 1 to 30.
The displacement is as high as 1.70 or more, and it is excellent in deep drawability.
It that are me. Especially steel material number 1,3,12,14,1
1.85 for steel plates 7 to 21, 23 to 27, 29, and 30
As a result, a high average r value was obtained. On the other hand, the comparative steel 31 has a low fatigue limit because no B is added, and the comparative steel 32 has a low average r value because the B is excessively added.
The deep drawability has deteriorated. Further, the comparative steels 33 and 41 have a low annealing limit because of the high annealing temperature, and the comparative steel 42 has a low average r value because the annealing temperature is lower than the recrystallization temperature. Comparative steels 34, 35 and 36 are C, Si and Mn, respectively.
, The average r value decreases. In addition, comparative steel 37
Thus, not only the average r-value is lowered due to the high P, but also the plating adhesion is deteriorated. Further, the comparative steel 38 has a high Nb, so that the average r-value is reduced and the deep drawability is deteriorated.
In No. 9, the average r-value was reduced due to the absence of Ti and Nb, and deep drawing was performed.
Has deteriorated . Furthermore, since the comparative steel 40 has a large amount of N, the average r value is reduced and the deep drawability is deteriorated .
【0031】[0031]
【表3】 [Table 3]
【0032】[0032]
【表4】 [Table 4]
【0033】[0033]
【表5】 [Table 5]
【0034】[0034]
【表6】 [Table 6]
【0035】[0035]
【発明の効果】本発明によれば、深絞り成形性に優れ、
かつ疲労特性にも優れた冷延鋼板および溶融亜鉛めっき
鋼板の製造が初めて可能となるものであり、その工業的
価値は大きい。According to the present invention, excellent deep drawability is obtained,
The production of cold-rolled steel sheets and hot-dip galvanized steel sheets having excellent fatigue properties is possible for the first time, and their industrial value is great.
【図1】横軸に鋼板の降伏強度をとり、縦軸に鋼板の疲
労限をとって、両者の関係について調べた結果を示すプ
ロット図。BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plot showing the results of an examination of the relationship between the yield strength of a steel sheet on the horizontal axis and the fatigue limit of the steel sheet on the vertical axis.
【図2】横軸に鋼板の焼鈍温度をとり、縦軸に鋼板の降
伏強度および平均r値をとって、それぞれの関係につい
て調べた結果を示すプロット図。FIG. 2 is a plot showing the results of examining the respective relationships, with the horizontal axis representing the annealing temperature of the steel sheet and the vertical axis representing the yield strength and the average r value of the steel sheet.
【図3】横軸に鋼板の焼鈍温度を規定する数式に各成分
数値を入れて得られる指数をとり、縦軸に焼鈍温度上限
値をとって、両者の関係について調べた結果を示すプロ
ット図。FIG. 3 is a plot showing the result of examining the relationship between an index obtained by putting each component numerical value into a mathematical formula defining the annealing temperature of a steel sheet on the horizontal axis and an upper limit of the annealing temperature on the vertical axis. .
【図4】横軸にB添加量をとり、縦軸にそれぞれ降伏強
度および平均r値をとって、これらの関係について調べ
た結果を示すプロット図である。FIG. 4 is a plot diagram showing the results of examining the relationship between the B addition amount on the horizontal axis and the yield strength and the average r value on the vertical axis.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉武 明英 東京都千代田区丸の内一丁目1番2号 日本鋼管株式会社内 (56)参考文献 特開 昭63−310924(JP,A) 特開 昭63−317625(JP,A) 特公 平4−5732(JP,B2) (58)調査した分野(Int.Cl.6,DB名) C21D 9/48 C21D 8/04──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Akihide Yoshitake 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) References JP-A-63-310924 (JP, A) JP-A Sho 63-317625 (JP, A) JP 4-5732 (JP, B2) (58) Fields investigated (Int. Cl. 6 , DB name) C21D 9/48 C21D 8/04
Claims (4)
i:0.2%以下、Mn:0.10〜0.5%、P:
0.03%以下、S:0.015%以下、sol.A
l:0.10%以下、N:0.0040%以下、B:
0.0001〜0.0020%を含有し、さらに0.0
05〜0.10%のTiと0.005〜0.030%の
Nbの1種又は2種を含有する鋼を熱間圧延し、酸洗後
圧下率60%以上90%以下で冷間圧延し、再結晶温度
以上でかつ、6(10Si+0.5Mn+100P+8
00B+14)+710で規定される温度以下で焼鈍
し、疲労限を26.1kgf/mm 2 以上とし、かつ、
下式で与えられる平均ランクフォード(r)値を1.7
0以上ととしすることを特徴とする疲労特性及び深絞り
性に優れた鋼板の製造方法。r=(r 0 +2r 45 +r 90 )/4 ただし、r 0 ,r 45 ,r 90 は圧延方向に対してそれぞれ
0°,45°,90°から採取した試験片を用いて求め
たランクフォード値である。 1. The method according to claim 1, wherein C: 0.0050% or less,
i: 0.2% or less, Mn: 0.10 to 0.5%, P:
0.03% or less, S: 0.015% or less, sol. A
l: 0.10% or less, N: 0.0040% or less, B:
0.0001 to 0.0020%, and further 0.0%
0.5-0.10% Ti and 0.005-0.030%
After hot rolling steel containing one or two types of Nb and pickling it
Cold rolling at a rolling reduction of 60% or more and 90% or less, recrystallization temperature
6 (10Si + 0.5Mn + 100P + 8
00B + 14) + annealing at a temperature below 710
And the fatigue limit is 26.1 kgf / mm Two And above, and
The average Rankford (r) value given by the following equation is 1.7
0 or moreWhenTo doFatigue characteristics and deep drawing
Method for manufacturing steel sheets with excellent heat resistance.r = (r 0 + 2r 45 + R 90 ) / 4 Where r 0 , R 45 , R 90 Is for each rolling direction
Determined using test pieces taken from 0 °, 45 °, and 90 °
Rankford value.
徴とする請求項1記載の疲労特性及び深絞り性に優れた
鋼板の製造方法。2. The method for producing a steel sheet having excellent fatigue characteristics and deep drawability according to claim 1, further comprising hot-dip galvanizing.
する請求項2記載の疲労特性及び深絞り性に優れた鋼板
の製造方法。3. The method for producing a steel sheet according to claim 2, further comprising an alloying treatment.
量が50%以上のFe−Zn合金めっき層が形成されて
いることを特徴とする請求項3記載の疲労特性及び深絞
り性に優れた鋼板の製造方法。4. The fatigue characteristics and deep drawability according to claim 3, wherein an Fe—Zn alloy plating layer having an Fe content of 50% or more is formed on the zinc plating layer. Excellent steel plate manufacturing method.
Priority Applications (1)
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JP23230292A JP2827740B2 (en) | 1992-08-31 | 1992-08-31 | Method for producing steel sheet with excellent fatigue characteristics and deep drawability |
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Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP23230292A JP2827740B2 (en) | 1992-08-31 | 1992-08-31 | Method for producing steel sheet with excellent fatigue characteristics and deep drawability |
Publications (2)
Publication Number | Publication Date |
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JPH0681044A JPH0681044A (en) | 1994-03-22 |
JP2827740B2 true JP2827740B2 (en) | 1998-11-25 |
Family
ID=16937086
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US5897967A (en) * | 1996-08-01 | 1999-04-27 | Sumitomo Metal Industries, Ltd. | Galvannealed steel sheet and manufacturing method thereof |
JP3912014B2 (en) * | 2001-02-05 | 2007-05-09 | Jfeスチール株式会社 | Alloyed hot-dip galvanized steel sheet and method for producing the same |
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