JP2563021B2 - Method for producing high-strength hot-rolled hot-dip galvannealed steel sheet with excellent stretch flangeability - Google Patents
Method for producing high-strength hot-rolled hot-dip galvannealed steel sheet with excellent stretch flangeabilityInfo
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- JP2563021B2 JP2563021B2 JP3306756A JP30675691A JP2563021B2 JP 2563021 B2 JP2563021 B2 JP 2563021B2 JP 3306756 A JP3306756 A JP 3306756A JP 30675691 A JP30675691 A JP 30675691A JP 2563021 B2 JP2563021 B2 JP 2563021B2
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、引張強度４５キロ以上
の高強度熱延鋼板を原板として、冷間圧延することなし
に、連続焼鈍溶融亜鉛めっきラインにおいて、強度が殆
ど低下することなく、熱延原板と同等又は同等以上の優
れた加工性、特に伸びフランジ性の優れた高強度溶融亜
鉛めっき鋼板を製造する方法に関するものである。FIELD OF THE INVENTION The present invention uses a high-strength hot-rolled steel sheet having a tensile strength of 45 kg or more as a base sheet, without cold rolling, in a continuous annealing hot-dip galvanizing line, with almost no decrease in strength. The present invention relates to a method for producing a high-strength hot-dip galvanized steel sheet having excellent workability equal to or higher than that of a hot-rolled raw sheet, particularly excellent in stretch flangeability.
【０００２】[0002]
【従来の技術】近年、自動車等の補強部材や足回り部材
の軽量化及び防錆性能の向上という観点から、強加工と
高強度を有する熱延原板溶融亜鉛めっき鋼板のニーズが
強くなっている。2. Description of the Related Art In recent years, from the viewpoint of reducing the weight of reinforcing members and underbody members of automobiles and improving rust-prevention performance, there is an increasing need for hot-rolled hot-dip galvanized steel sheets having strong working and high strength. .
【０００３】溶融亜鉛めっき鋼板は冷延鋼板が主体であ
り、熱延鋼板を用いる場合でも、溶融亜鉛めっき鋼板は
軟鋼板が主体となっており(特開昭６３−１７９０２４
号、特開昭６０−２０４８２７号)、高強度熱間圧延鋼
板の溶融亜鉛めっき化は未だ殆ど実用化されていない。The hot-dip galvanized steel sheet is mainly a cold-rolled steel sheet, and even when a hot-rolled steel sheet is used, the hot-dip galvanized steel sheet is mainly a mild steel sheet (Japanese Patent Laid-Open No. 63-179024).
No. 60-204827), hot dip galvanizing of high-strength hot-rolled steel sheets has not been put to practical use yet.
【０００４】[0004]
【発明が解決しようとする課題】一方、最近になって、
高強度熱間圧延鋼板をめっき化する動きにあり、特開平
３−４４４２３号(加工性に優れた亜鉛めっき熱延鋼板
の製造方法)が提案されている。しかし、この方法はめ
っき前の均熱温度のみを規定しているものであり、この
規定のみでは、ＴＳ５０キロ以上の高強度熱間圧延鋼板
の場合には必ずしも十分な加工性、特に伸びフランジ性
(λ値)が得られない。On the other hand, recently,
There is a movement to plate high-strength hot-rolled steel sheets, and JP-A-3-44423 (a method for producing a galvanized hot-rolled steel sheet having excellent workability) has been proposed. However, this method regulates only the soaking temperature before plating, and with this regulation alone, sufficient workability, especially stretch flangeability, is always achieved in the case of high-strength hot-rolled steel sheet of TS 50 kg or more.
(λ value) cannot be obtained.
【０００５】局部延性の優れた高強度熱延鋼板について
は、熱延まま材では、変態組織強化タイプのフェライト
・ベイナイト組織鋼が既に開発されている(特願昭５９
−２５２２４２号、特願昭６０−２９８５４２号)。し
かし、このような変態組織強化材を溶融亜鉛めっきする
と、めっき化による熱履歴を被るため、局部延性の低下
が著しくなり、加工に不安があるため、前述のめっき化
には踏み切れない状況にある。Regarding the high-strength hot-rolled steel sheet having excellent local ductility, a transformation-structure-strengthened ferrite / bainite-structured steel has already been developed as an as-hot-rolled steel sheet (Japanese Patent Application No. 59-59).
-252242, Japanese Patent Application No. 60-298542). However, when hot-dip galvanizing such a transformation structure reinforcing material is subjected to heat history due to plating, local ductility is significantly reduced, and there is concern about processing. .
【０００６】本発明は、上記従来技術の問題点を解決
し、局部延性の優れた変態組織強化タイプの熱延まま高
強度熱延鋼板に対して、溶融亜鉛めっきを施しても、加
工性、特に伸びフランジ性の優れた高強度溶融亜鉛めっ
き鋼板を安定して製造し得る方法を提供することを目的
とするものである。The present invention solves the above-mentioned problems of the prior art and, even when hot-rolled high-strength as-rolled high-strength hot-rolled steel sheet of a transformation structure strengthening type having excellent local ductility, is workable, In particular, it is an object of the present invention to provide a method capable of stably producing a high-strength hot-dip galvanized steel sheet having excellent stretch flangeability.
【０００７】[0007]
【課題を解決するための手段】本発明者は、前記課題を
解決するために鋭意研究を重ねた結果、局部延性の優れ
た変態組織強化タイプの熱延まま高強度熱延鋼板に対し
て、最適なめっき化熱履歴を施すことにより、組織、炭
化物形状、固溶Ｃを適切に制御し、伸びフランジ性の優
れた高強度合金化溶融亜鉛めっき鋼板が得られることを
見い出し、ここに本発明を完成したものである。Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventor has found that for the as-rolled high-strength hot-rolled high-strength hot-rolled steel sheet of a transformation structure reinforced type having excellent local ductility, It was found that a structure, a carbide shape, and a solid solution C are appropriately controlled by applying an optimum heat history of plating, and a high-strength hot-dip galvanized steel sheet having excellent stretch flangeability can be obtained. Is completed.
【０００８】すなわち、本発明は、Ｃ：０．００１〜
０．３０％、Ｓｉ：２．００％以下、Ｍｎ：０．２〜
２．０％、Ｐ：０．１０％以下、Ｓ：０．０１％以下、
Ａｌ：０．００５〜０．１０％及びＮｂ：０．０１〜
０．２０％を含有し、必要に応じて更にＣｒ：１．０％
以下、Ｖ：０．５％以下、Ｔｉ：０．５％以下、Ｃｕ：
０．５％以下、Ｎｉ：０．５％以下及びＣａ：０．０１
％以下のうちの１種又は２種以上を含有し、残部がＦｅ
及び不可避的不純物よりなる組成を有する鋼を熱間圧延
し、６００℃未満２５０℃を超える温度で巻取ってフェ
ライト及びべイナイト組織の熱延鋼板とし、酸洗後、冷
間圧延することなく、均熱加熱し、溶融亜鉛めっきし、
その後合金化加熱する連続焼鈍合金化溶融亜鉛めっきラ
インにおいて、均熱最高温度Ｔ（℃）、合金化加熱後の
冷却速度ＣＲ（℃／ｓｅｃ）を鋼成分係数（Ｋ）に応じ
て、 Ｋ＜０．３４％のとき： Ｔ≦８００℃ Ｋ≧０．３４％のとき： Ｔ≦８００℃、かつ、 ２８２．５×［ｌｏｇ ＣＲ］＋Ｔ≦１１００℃ 但し、Ｋ＝Ｃ＋（１／５） （Ｍｎ＋Ｓｉ）＋（１／４）Ｃｒ を満たす条件で加熱冷却することを特徴とする伸びフラ
ンジ性の優れた高強度熱延原板合金化溶融亜鉛めっき鋼
板の製造方法を要旨とするものである。That is, according to the present invention, C: 0.001 to
0.30%, Si: 2.00% or less, Mn: 0.2 to
2.0%, P: 0.10% or less, S: 0.01% or less,
Al: 0.005 to 0.10% and Nb: 0.01 to
0.20%, if necessary, further Cr: 1.0%
Hereinafter, V: 0.5% or less, Ti: 0.5% or less, Cu:
0.5% or less, Ni: 0.5% or less and Ca: 0.01
% Or less of one or more, and the balance is Fe
And a steel hot-rolled with a composition consisting of unavoidable impurities, Fe and wound at a temperature exceeding 250 ° C. lower than 600 ° C.
A hot rolled steel sheet of light and bainite structure , after pickling, without cold rolling, soaking and heating, hot dip galvanizing,
In a continuous annealing alloying hot-dip galvanizing line for subsequent alloying heating , the soaking maximum temperature T (° C) and the cooling rate CR (° C / sec) after the alloying heating are set according to the steel composition coefficient (K), K < When 0.34%: T ≦ 800 ° C. When K ≧ 0.34%: T ≦ 800 ° C. and 282.5 × [log CR] + T ≦ 1100 ° C. However, K = C + (1/5) ( It is intended to provide a method for producing a high-strength hot-rolled sheet alloyed hot-dip galvanized steel sheet having excellent stretch flangeability, which comprises heating and cooling under conditions satisfying Mn + Si) + (1/4) Cr.
【０００９】以下に本発明を更に詳述する。The present invention will be described in more detail below.
【００１０】[0010]
【００１１】まず、本発明における化学成分の限定理由
を示す。First, the reasons for limiting the chemical components in the present invention will be shown.
【００１２】Ｃ：Ｃ成分は鋼の強度を向上する作用を有
しているが、その含有量が０.００１％未満では所望の
強度を確保することができず、一方、０.３０％を超え
ると溶接性の劣化を招くことから、Ｃ含有量は０.００
１〜０.３０％の範囲とする。C: C component has the effect of improving the strength of steel, but if the content is less than 0.001%, the desired strength cannot be secured, while 0.30% is required. If it exceeds, the weldability will deteriorate, so the C content is 0.00.
The range is from 1 to 0.30%.
【００１３】Ｓi：Ｓiは固溶体硬化を通じ、微量添加で
あっても鋼の強度上昇と延性の向上に有効な働きをする
元素である。しかし、２.０％を超えて含有させると、
溶接性の劣化を招くことから、Ｓi含有量は２.０％以下
とする。なお、特に鋼板表面のスケール性に厳しい要求
がなされる場合には、０.０７％以下にすることが好ま
しい。Si: Si is an element that effectively works to increase the strength and the ductility of steel even if added in a small amount through solid solution hardening. However, if the content exceeds 2.0%,
Since the weldability is deteriorated, the Si content is set to 2.0% or less. It should be noted that, particularly when the scale property of the steel sheet surface is strictly demanded, it is preferably made 0.07% or less.
【００１４】Ｍn：Ｍnは固溶体強化、変態強化、細粒化
強化により鋼の強度と靭性の両方を向上させる作用があ
る。しかし、その含有量が０.２０％未満では所望の効
果が得られず、一方、２.０％を超えて含有させると溶
接性が劣化することから、Ｍn含有量は０.２０〜２.０
％の範囲とする。Mn: Mn has a function of improving both strength and toughness of steel by solid solution strengthening, transformation strengthening and grain refining strengthening. However, if its content is less than 0.20%, the desired effect cannot be obtained, while if it exceeds 2.0%, the weldability deteriorates, so the Mn content is 0.20-2. 0
The range is%.
【００１５】Ｐ：Ｐは鋼の延性に対して好ましくない元
素であり、可能な限り少ない方がよい。本発明において
は、熱延の低温巻取りにおいてＰの悪影響を軽減するこ
と及び経済性を考慮して、上限を０.１０％とする。好
ましくは０.０２０％以下である。P: P is an element which is unfavorable for the ductility of steel, and it is preferable that it is as small as possible. In the present invention, the upper limit is set to 0.10% in consideration of reducing the adverse effect of P in the low temperature winding of hot rolling and economical efficiency. It is preferably 0.020% or less.
【００１６】Ｓ：ＳはＭnと結合してＡ系介在物を生
じ、延性の低下や耐縦割れ性の劣化を招くので、可及的
に少ない方がよい。経済性を考慮して上限を０.０１０
％とする。好ましくは０.００５％以下である。S: S combines with Mn to form an A-type inclusion, which leads to a decrease in ductility and deterioration in vertical cracking resistance. Considering economy, the upper limit is 0.010
%. It is preferably 0.005% or less.
【００１７】Ａl：Ａlは鋼の脱酸のために必要な元素で
あり、充分な脱酸効果を確保するためには０.００５％
以上含有させる必要がある。一方、０.１０％を超える
とその効果が飽和すると共に、クラスター状の介在物が
多くなり、加工性が劣化するので、上限を０.１０％と
する。Al: Al is an element necessary for deoxidizing steel, and 0.005% is necessary for ensuring a sufficient deoxidizing effect.
It is necessary to contain the above. On the other hand, if it exceeds 0.10%, the effect is saturated, and the number of cluster-like inclusions increases and the workability deteriorates, so the upper limit is made 0.10%.
【００１８】Ｎｂ： Ｎｂは微量添加で大幅な強度上昇と優れた低温靭性を付
与する好ましい元素である。また、比較的複雑な冷却パ
ターンをとらなくても局部延性の改善に有効なベイナイ
トを生じ易くする効果がある。下限はかかる効果が大い
に期待できる量として０．０１％とし、一方、０．２０
％を超えて含有させると溶接性が劣化するので、上限を
０．２０％とする。Nb: Nb is a preferable element that imparts a large increase in strength and excellent low temperature toughness when added in a small amount. Further, effective improvement of local elongation without taking a relatively complex cooling pattern bainite
There is an effect that tends to occur at the door. The lower limit is 0.01%, which is the amount at which such effects can be expected, while 0.20
%, The weldability deteriorates, so the upper limit is made 0.20%.
【００１９】更に、本発明においては、必要に応じて、
熱延鋼板の機械的性質の改善、特に強度の向上と延性、
靭性の強化を図るため、以下の元素の１種又は２種以上
を適量で添加してもよい。Further, in the present invention, if necessary,
Improvement of mechanical properties of hot-rolled steel sheet, especially improvement of strength and ductility,
In order to enhance the toughness, one or more of the following elements may be added in an appropriate amount.
【００２０】Ｃr、Ｖ、Ｔi、Ｃu、Ｎi：これらの成分は
鋼の強靭化に有効な元素である。しかし、経済性を考慮
して、Ｃrの上限を１.０％、他の元素の上限をそれぞれ
０.５％とする。Cr, V, Ti, Cu, Ni: These components are elements effective for toughening steel. However, considering economic efficiency, the upper limit of Cr is set to 1.0%, and the upper limits of other elements are set to 0.5%.
【００２１】Ｃa：Ｃaは、介在物の形態制御により、低
温靭性、延性の向上に好ましいが、多すぎると鋼中の介
在物量が増加して延性の劣化が生じるので、上限を０.
０１％とする。[0021] Ca: Ca is preferable for improving the low temperature toughness and ductility by controlling the morphology of inclusions, but if it is too large, the amount of inclusions in the steel increases and ductility deteriorates.
It is set to 01%.
【００２２】上記成分組成の鋼については、常法により
鋳造、熱間圧延を行い、酸洗後、冷間圧延することな
く、連続焼鈍合金化溶融亜鉛めっきラインにてめっきを
行うが、本発明においては、以下の条件を規制する必要
がある。The steel having the above-described composition is cast, hot-rolled by a conventional method, pickled, and then plated in a continuous annealed alloy galvanizing line without cold rolling. In, it is necessary to regulate the following conditions.
【００２３】熱延鋼板の巻取温度： 本発明において熱延後２５０℃を超え６００℃未満で巻
き取る理由は、極めて局部延性に優れた（穴拡げ率の高
い）材質を熱延原板で得るためである。巻取温度が６０
０℃以上では局部延性に優れたフェライト−ベイナイト
組織が得られず、また２５０℃以下では第二相がマルテ
ンサイトなど硬質の低温変態生成相となり、局部延性が
極めて劣化する。なお、冷却速度は前記巻取温度が確保
できる通常の熱延実操業範囲内でよい。Winding temperature of hot rolled steel sheet: In the present invention, the reason why the hot rolled steel sheet is wound at more than 250 ° C. and less than 600 ° C. is to obtain a material having extremely excellent local ductility (high hole expansion ratio) from the hot rolled steel sheet. This is because. Winding temperature is 60
At 0 ° C. or higher, a ferrite-bainite structure having excellent local ductility cannot be obtained, and at 250 ° C. or lower, the second phase becomes a hard low-temperature transformation forming phase such as martensite, resulting in extremely deteriorated local ductility. The cooling rate may be within a normal hot rolling actual operation range where the winding temperature can be secured.
【００２４】連続焼鈍溶融亜鉛めっきラインにおける熱
履歴条件：図１はThermal history condition in continuous annealing hot dip galvanizing line:
【表１】 に示す化学成分の熱延原板を用いて、合金化加熱後の冷
却速度(ＣＲ)一定(７℃／s)のもとで均熱最高温度(Ｔ)
が、めっき後の強度(ＴＳ)、穴拡げ率(λ値)に及ぼす影
響を示している。なお、熱延鋼板は５００℃で巻取り、
酸洗後冷間圧延することなく合金化加熱した。また、鋼
成分係数(Ｋ)を、Ｋ(％)＝Ｃ＋(１／５)(Ｓi＋Ｍn)＋
(１／４)Ｃrと定義する。λ値(穴拡げ率)は、λ＝{(割
れ時の穴径−初期穴径)／(初期穴径)}×１００(％)であ
る。[Table 1] Using a hot-rolled plate with the chemical composition shown in Fig. 2, the soaking maximum temperature (T) is maintained under a constant cooling rate (CR) (7 ℃ / s) after alloying
Shows the influence on the strength (TS) and the hole expansion ratio (λ value) after plating. The hot-rolled steel sheet is wound at 500 ° C,
After pickling, the alloy was heated without cold rolling. In addition, the steel component coefficient (K) is K (%) = C + (1/5) (Si + Mn) +
It is defined as (1/4) Cr. The λ value (hole expansion ratio) is λ = {(hole diameter at break-initial hole diameter) / (initial hole diameter)} × 100 (%).
【００２５】図１において、比較的高成分係数の鋼Ｂ
（Ｋ＝０．４３％）では、均熱最高温度７００℃前後で
λ値が最も低くなり、また８００℃以上では組織が崩れ
て強度が大幅に低下している。セメンタイトが球状化す
る６００℃前後の均熱最高温度で機械的特性は最も良好
となる。また、均熱最高温度が６７０℃以下の場合と、
７５０℃以上８００℃以下の場合とで良好なλ値を示し
ている。しかし、λ値は、均熱最高温度だけで定まるの
ではなく、均熱最高温度が高くなるほど冷却速度（Ｃ
Ｒ）の影響が大きい。In FIG. 1, steel B having a relatively high component coefficient
In the case of (K = 0.43%), the λ value becomes the lowest at around the maximum soaking temperature of 700 ° C., and at 800 ° C. or higher, the structure collapses and the strength decreases significantly. The mechanical properties become the best at the maximum soaking temperature around 600 ° C. at which cementite becomes spherical. In addition, when the maximum soaking temperature is 670 ° C or lower,
A good λ value is shown when the temperature is between 750 ° C and 800 ° C.
ing. However, the λ value is not determined only by the maximum soaking temperature, but the cooling rate (C
R) has a great influence.
【００２６】一方、低成分係数の鋼Ａ（Ｋ＝０．３１
％）については、ＣＲ＝７℃／ｓのもとでの均熱温度依
存性については、鋼Ｂ（Ｋ＝０．４３％）とほぼ同様、
均熱最高温度が８００℃以上では組織が崩れて強度が大
幅に低下しているが、λ値については、均熱最高温度７
００℃前後で最も低くなるものの、鋼Ｂよりも良好なλ
値である。λ値は均熱最高温度が９００℃の如く高い場
合だけ冷却速度（ＣＲ）の影響が見られる。On the other hand, steel A having a low component coefficient (K = 0.31)
%), The soaking temperature dependence under CR = 7 ° C./s is almost the same as that of steel B (K = 0.43%).
When the maximum soaking temperature is 800 ° C or higher, the structure collapses and the strength decreases significantly.
Although it becomes the lowest around 00 ° C, it has better λ than Steel B.
It is a value . The λ value is affected by the cooling rate (CR) only when the soaking maximum temperature is as high as 900 ° C.
【００２７】図２は供試鋼のλ値に及ぼすＣＲ依存性を
示しており、Ａ鋼(Ｋ＝０.３１％)のような低成分係数
の鋼では均熱最高温度が８８０℃のように高い場合だけ
λ値のＣＲ依存性が大きいが、Ｂ鋼(Ｋ＝０.４３％)の
ような高成分係数鋼になればλ値のＣＲ依存性が大にな
ることがわかる。この理由は、高成分係数鋼ほど再加熱
時にオーステナイト化され易く、また、その後の冷却に
よりマルテンサイトなどの硬質第２相が生成され易く、
この第２相がλ値を低下させるためであると考えられ
る。FIG. 2 shows the CR dependence on the λ value of the steel under test. The maximum soaking temperature is 880 ° C. for steels with a low compositional coefficient such as A steel (K = 0.31%). It can be seen that the CR dependence of the λ value is large only when it is extremely high, but the CR dependence of the λ value becomes large in the case of a steel having a high component coefficient such as B steel (K = 0.43%). The reason for this is that the higher the composition factor steel, the easier it is to become austenite during reheating, and the harder second phase such as martensite is likely to be generated by subsequent cooling,
It is considered that this second phase is for decreasing the λ value.
【００２８】図１、図２の結果より、熱延原板の特性を
そのまま確保するための条件範囲を示すと図３の如くに
なる。Ａ鋼のようなＫ＜０．３４％の低成分係数鋼で
は、最高均熱温度が８００℃より高い場合だけ冷却速度
（ＣＲ）の影響を受け、ＣＲが大きくなるとλ値が低く
なる。８００℃以下では冷却速度依存性がない。なお、
図１に示したように、λ値に関しては、Ｋ≧０．３４％
の場合、Ｔ≦６７０℃又は７５０℃≦Ｔ≦８００℃が好
ましい。From the results of FIGS. 1 and 2, the condition range for ensuring the characteristics of the hot-rolled original sheet as it is is as shown in FIG. For steels with a low composition such as steel A with K <0.34%, the cooling rate is only when the maximum soaking temperature is higher than 800 ° C.
Under the influence of (CR), the λ value decreases as CR increases . Below 800 ° C, there is no cooling rate dependency. In addition,
As shown in FIG. 1, regarding the λ value, K ≧ 0.34%
In the case of, T ≦ 670 ° C. or 750 ° C. ≦ T ≦ 800 ° C. is preferable.
【００２９】一方、Ｂ鋼のようなＫ≧０.３４％の高成
分係数鋼では、８００℃以下の均熱温度の範囲内におい
ても、冷却速度(ＣＲ)が速くなると適正な均熱最高温度
は狭くなる。具体的には、Ｋ≧０.４３％の高成分係数
Ｂ鋼の場合、その適正範囲はＴ≦８００℃、かつ１１０
０℃≧Ｔ＋２８２.５×[logＣＲ]である。On the other hand, in the case of a steel having a high composition coefficient of K ≧ 0.34% such as B steel, even if the cooling rate (CR) is high even within the temperature range of the soaking temperature of 800 ° C. or less, the proper soaking maximum temperature is obtained. Becomes narrower. Specifically, in the case of a high component coefficient B steel with K ≧ 0.43%, the appropriate range is T ≦ 800 ° C. and 110
0 ° C. ≧ T + 282.5 × [log CR].
【００２９】本発明においては、以上の基礎実験結果を
踏まえ、更に多数の実験を行った結果、上述のめっき条
件とするものである。In the present invention, based on the results of the above basic experiments, as a result of conducting a large number of experiments, the above plating conditions are established.
【００３０】次に本発明の実施例を示す。Next, examples of the present invention will be described.
【００３１】[0031]
【表２】 [Table 2]
【表３】 [Table 3]
【表４】 表２に示す化学成分の鋼を溶製し、鋳型に鋳込んで、直
接的に又は熱間圧延にて３０ｍｍ厚のスラブとした。次
いで、このスラブを表３に示す条件で熱間圧延して２ｍ
ｍ厚さの熱延板となし、酸洗後、更に溶融亜鉛めっきを
施した。表４に溶融亜鉛めっき後の機械的性質と熱延原
板の機械的性質を示す。 [Table 4] Steel having the chemical composition shown in Table 2 was melted and cast into a mold to obtain a slab having a thickness of 30 mm directly or by hot rolling. Then, this slab was hot-rolled under the conditions shown in Table 3 to 2 m.
A hot-rolled sheet having a thickness of m was formed, and after pickling, hot dip galvanizing was performed. Table 4 shows the mechanical properties after hot dip galvanizing and the mechanical properties of the hot rolled sheet.
【００３２】表４から明らかなように、本発明例の合金
化溶融亜鉛めっき熱延鋼板は、熱延原板と同等の優れた
強度(ＴＳ)及び穴拡げ値(λ)を有しているのに対して、
比較例の合金化溶融亜鉛めっき熱延鋼板では、めっき後
強度(ＴＳ)や穴拡げ値(λ)が著しく低下している。As is apparent from Table 4, the hot-dip galvannealed steel sheet of the present invention has the same excellent strength (TS) and hole expansion value (λ) as the hot-rolled base sheet. Against
In the hot-dip galvannealed steel sheet of Comparative Example, the strength (TS) after plating and the hole expansion value (λ) are remarkably reduced.
【００３３】なお、低成分係数の鋼に関しては、表１に
示した鋼Ａ(Ｋ＝０.３１)を本発明範囲内の条件で製造
すれば、強度及びλ値とも優れた合金化溶融亜鉛めっき
熱延鋼板が得られることを確認した。Regarding steel having a low component coefficient, when steel A (K = 0.31) shown in Table 1 is manufactured under the conditions within the scope of the present invention, alloyed molten zinc excellent in strength and λ value is obtained. It was confirmed that a galvanized hot rolled steel sheet was obtained.
【００３４】[0034]
【発明の効果】以上詳述したように、本発明によれば、
十分な強度、穴拡げ性を始めとする加工性の優れた合金
化溶融亜鉛めっき熱延鋼板を安定して製造することがで
き、産業上極めて有用な効果を有している。As described in detail above, according to the present invention,
It is possible to stably produce an alloyed hot-dip galvanized hot-rolled steel sheet having excellent workability such as sufficient strength and hole expandability, and it has an extremely useful effect industrially.
【図１】合金化溶融亜鉛めっき熱延鋼板の強度(ＴＳ)、
λ(穴拡げ率)に及ぼす均熱温度依存性(ＣＲ：７℃／se
c)を示す図である。1] Strength (TS) of hot dip galvannealed steel sheet,
Dependence of soaking temperature on λ (hole expansion rate) (CR: 7 ℃ / se
It is a figure which shows c).
【図２】合金化溶融亜鉛めっき熱延鋼板のλ(穴拡げ率)
に及ぼす冷却速度依存性(Ｔ：６６０℃、７８０℃、８
８０℃)を示す図である。[Fig. 2] λ (hole expansion ratio) of hot-dip galvannealed steel sheet
On cooling rate (T: 660 ℃, 780 ℃, 8
It is a figure which shows 80 degreeC.
【図３】熱延原板と同等の機械的特性値を得るための均
熱最高温度Ｔと冷却速度ＣＲの適正範囲を示す図であ
る。FIG. 3 is a diagram showing appropriate ranges of a soaking maximum temperature T and a cooling rate CR for obtaining mechanical characteristic values equivalent to those of a hot-rolled original sheet.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｃ２２Ｃ 38/12 Ｃ２２Ｃ 38/12 38/50 38/50 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI Technical indication C22C 38/12 C22C 38/12 38/50 38/50
Claims (3)
１〜０．３０％、Ｓｉ：２．００％以下、Ｍｎ：０．２
〜２．０％、Ｐ：０．１０％以下、Ｓ：０．０１％以
下、Ａｌ：０．００５〜０．１０％及びＮｂ：０．０１
〜０．２０％を含有し、残部がＦｅ及び不可避的不純物
よりなる組成を有する鋼を熱間圧延し、６００℃未満２
５０℃を超える温度で巻取ってフェライト及びベイナイ
ト組織の熱延鋼板とし、酸洗後、冷間圧延することな
く、均熱加熱し、溶融亜鉛めっきし、その後合金化加熱
する連続焼鈍合金化溶融亜鉛めっきラインにおいて、均
熱最高温度Ｔ（℃）、合金化加熱後の冷却速度ＣＲ（℃
／ｓｅｃ）を鋼成分係数（Ｋ）に応じて、 Ｋ＜０．３４％のとき： Ｔ≦８００℃ Ｋ≧０．３４％のとき： Ｔ≦８００℃、かつ、 ２８２．５×［ｌｏｇ ＣＲ］＋Ｔ≦１１００℃ 但し、Ｋ＝Ｃ＋（１／５） （Ｍｎ＋Ｓｉ）＋（１／４）Ｃｒ を満たす条件で加熱冷却することを特徴とする伸びフラ
ンジ性の優れた高強度熱延原板合金化溶融亜鉛めっき鋼
板の製造方法。1. In weight% (hereinafter the same), C: 0.00
1 to 0.30%, Si: 2.00% or less, Mn: 0.2
-2.0%, P: 0.10% or less, S: 0.01% or less, Al: 0.005-0.10% and Nb: 0.01
~ 0.20% with the balance being Fe and inevitable impurities, hot-rolled steel, less than 600 ° C 2
Winding at temperatures above 50 ° C for ferrite and bainay
The hot-rolled steel sheet of the bets tissue, pickling, without cold rolling and soaking heat, and galvanized, then alloying heat
In the continuous annealed alloying hot dip galvanizing line, the soaking maximum temperature T (° C) and the cooling rate after alloying heating CR (° C
/ Sec) according to the steel component coefficient (K): When K <0.34%: T ≦ 800 ° C. When K ≧ 0.34%: T ≦ 800 ° C. and 282.5 × [log CR ] + T ≦ 1100 ° C. However, high-strength hot-rolled sheet alloy with excellent stretch-flangeability, characterized by heating and cooling under conditions satisfying K = C + (1/5) (Mn + Si) + (1/4) Cr Manufacturing method of hot-dip galvanized steel sheet.
０.５％以下、Ｔi:０.５％以下、Ｃu:０.５％以下、Ｎ
i:０.５％以下及びＣa:０.０１％以下のうちの１種又は
２種以上を含有するものである請求項１に記載の方法。2. The steel further comprises Cr: 1.0% or less and V:
0.5% or less, Ti: 0.5% or less, Cu: 0.5% or less, N
The method according to claim 1, which contains one or more of i: 0.5% or less and Ca: 0.01% or less.
は７５０≦Ｔ≦８００℃を満たす条件で加熱冷却する請
求項１又は２に記載の方法。3. The method according to claim 1, wherein when K ≧ 0.34% , heating and cooling are performed under the condition that T ≦ 670 ° C. or 750 ≦ T ≦ 800 ° C. is satisfied.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3306756A JP2563021B2 (en) | 1991-10-25 | 1991-10-25 | Method for producing high-strength hot-rolled hot-dip galvannealed steel sheet with excellent stretch flangeability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3306756A JP2563021B2 (en) | 1991-10-25 | 1991-10-25 | Method for producing high-strength hot-rolled hot-dip galvannealed steel sheet with excellent stretch flangeability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05117834A JPH05117834A (en) | 1993-05-14 |
| JP2563021B2 true JP2563021B2 (en) | 1996-12-11 |
Family
ID=17960930
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3306756A Expired - Fee Related JP2563021B2 (en) | 1991-10-25 | 1991-10-25 | Method for producing high-strength hot-rolled hot-dip galvannealed steel sheet with excellent stretch flangeability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2563021B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102341521A (en) * | 2009-05-27 | 2012-02-01 | 新日本制铁株式会社 | High-strength steel sheet, hot-dipped steel sheet, and alloy hot-dipped steel sheet that have excellent fatigue, elongation, and collision characteristics, and manufacturing method for said steel sheets |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000313936A (en) | 1999-04-27 | 2000-11-14 | Kobe Steel Ltd | Galvannealed steel sheet excellent in ductility and production thereof |
| PL2835440T3 (en) | 2012-04-06 | 2019-02-28 | Nippon Steel & Sumitomo Metal Corporation | Hot-dip galvannealed hot-rolled steel sheet and process for producing same |
| KR101657799B1 (en) * | 2014-12-18 | 2016-09-20 | 주식회사 포스코 | Galvanized steel sheet having excellent elogation and method for manufacturing the same |
| KR101746995B1 (en) * | 2015-12-24 | 2017-06-28 | 주식회사 포스코 | Plated hot rolled steel sheet having excellent formability and method for manufacturing same |
| CN113881832B (en) * | 2021-08-19 | 2024-04-12 | 广州Jfe钢板有限公司 | Flexible annealing method for obtaining carbon-manganese 590 MPa-level dual-phase steel with stable mechanical properties |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6223975A (en) * | 1985-07-23 | 1987-01-31 | Kawasaki Steel Corp | Alloyed hot dip galvanized high-tension hot-rolled steel sheet and its manufacture |
| JPS62133059A (en) * | 1985-12-04 | 1987-06-16 | Kawasaki Steel Corp | Alloyed zinc hot dipped hot rolled high tensile steel sheet and its production |
| JPH0756053B2 (en) * | 1989-07-12 | 1995-06-14 | 住友金属工業株式会社 | Manufacturing method of galvanized hot rolled steel sheet with excellent workability |
-
1991
- 1991-10-25 JP JP3306756A patent/JP2563021B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102341521A (en) * | 2009-05-27 | 2012-02-01 | 新日本制铁株式会社 | High-strength steel sheet, hot-dipped steel sheet, and alloy hot-dipped steel sheet that have excellent fatigue, elongation, and collision characteristics, and manufacturing method for said steel sheets |
| CN102341521B (en) * | 2009-05-27 | 2013-08-28 | 新日铁住金株式会社 | High-strength steel sheet, hot-dipped steel sheet, and alloy hot-dipped steel sheet that have excellent fatigue, elongation, and collision characteristics, and manufacturing method for said steel sheets |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05117834A (en) | 1993-05-14 |
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