JPH11236621A - Production of high tensile strength and high ductility galvanized steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for producing a high tensile strength and high ductility hot dip galvanized or galvanized steel sheet excellent in plating adhesion even in the case of using any of a hot rolled steel plate and a cold rolled steel sheet as a base material. SOLUTION: A cold rolled steel sheet having a compsn, contg. 0.06 to 0.25% C, <=1.0% Si, 0.5 to 3.0% Mn, <=0.03% P, <=0.030% S, 0.4 to 2.5%Al, 0.003 to 0.080% Ti and <=0.010% N, satisfying the condition of (48/14)N<=Ti<=(48/14)N +(48/32)S+0.010, and the balance Fe with inevitable impurities is preoxidized at 550 to 750 deg.C, is annealed at a two phase region temp. of 760 to 900 deg.C for >=5 sec, is cooled to a temp. region of 420 to 600 deg.C at a cooling rate of >=3 deg.C/s, is held in the same temp. region for >=20 sec and is thereafter plated in a hot dip zinc bath to obtain a hot dip galvanized steel plate. Moreover, alloying treatment may be executed at <=600 deg.C. In the case a hot rolled steel plate is used as a base material, the hot rolled steel plate is subjected to descaling treatment and surface strain application working and is thereafter subjected to treatment similar to that for the cold rolled steel sheet.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、自動車の車体軽量
化による燃費向上を目指した高強度化への要求および耐
食性向上に対応する発明であり、溶融亜鉛めっきまたは
合金化溶融亜鉛めっきを施す高張力高延性亜鉛めっき鋼
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 demand for high strength and an improvement in corrosion resistance for the purpose of improving fuel efficiency by reducing the weight of an automobile body. The present invention relates to a method for manufacturing a high tensile ductile galvanized steel sheet.

【０００２】[0002]

【従来の技術】近年、自動車の燃費向上を目的として薄
肉化による車体軽量化が積極的に行われている。一方、
自動車の衝突安全に対する法規制が強化される傾向にあ
り、単純に薄肉化による軽量化だけでは対応することは
できない。そこで、高強度鋼板を使用して薄肉化を図る
必要があり、高強度鋼板への要求が一層強くなってきて
いる。2. Description of the Related Art In recent years, the weight of a vehicle body has been actively reduced by making it thinner in order to improve the fuel efficiency of an automobile. on the other hand,
Laws and regulations on collision safety of automobiles are becoming stricter, and it cannot be dealt with simply by reducing the weight by reducing the thickness. Therefore, it is necessary to reduce the wall thickness by using a high-strength steel plate, and the demand for a high-strength steel plate is becoming stronger.

【０００３】しかし、高強度鋼板を製造するにあたって
は高強度化による成形性の劣化という問題がある。一般
的に高強度化により成形性は劣化し、プレス成形で不具
合（割れ）が発生する。However, when manufacturing a high-strength steel sheet, there is a problem that the formability is deteriorated due to the increase in strength. In general, the moldability is degraded due to the increase in strength, and defects (cracks) occur in press molding.

【０００４】このような問題点を打破すべく、特開昭６
１−１５７６２５号公報には、０．１２〜０．５５重量
％のＣと、０．４〜１．８重量％のＳｉと、０．２〜
２．５重量％のＭｎのほか、必要により適量のＰ、Ｎ
ｉ、Ｃｕ、Ｃｒ、Ｔｉ、Ｎｂ、Ｖ、及びＭｏの１種また
は２種以上を含む鋼板をフェライト＋オーステナイトの
２相域に加熱した後、冷却途中の３５０〜５００℃の温
度域で３０秒〜３０分間保持することでフェライト＋ベ
イナイト＋残留オーステナイトの混合組織を実現し、高
延性を示す高張力鋼板とする方法が開示されている。In order to overcome such problems, Japanese Patent Application Laid-Open No.
In JP-A-157625, 0.12-0.55% by weight of C, 0.4-1.8% by weight of Si,
2.5% by weight of Mn and, if necessary, appropriate amounts of P and N
After heating a steel sheet containing one or more of i, Cu, Cr, Ti, Nb, V, and Mo to a two-phase region of ferrite + austenite, a temperature range of 350 to 500 ° C. during cooling is 30 seconds. A method has been disclosed in which a mixed structure of ferrite + bainite + retained austenite is realized by holding for up to 30 minutes to obtain a high-tensile steel sheet exhibiting high ductility.

【０００５】特開昭６０−４３４６４号公報には、高延
性を示す高張力鋼板の製造方法として、０．３０〜０．
５５重量％のＣと、０．７〜２．０重量％のＳｉ、０．
５〜２．０重量％のＭｎを含有する鋼板（熱延鋼板、冷
延鋼板）をオーステナイト単相域に加熱した後、６５０
〜７５０℃に４〜１５秒間保持した後、冷却過程の４５
０〜６５０℃の間にて合計１０〜５０秒間の保持を行
い、マルテンサイトあるいはベイナイト中に体積率で１
０％以上のフェライトと１０％以上の残留オーステナイ
トを含む混合組織鋼板とする方法が開示されている。Japanese Patent Laid-Open Publication No. Sho 60-43464 discloses a method for producing a high-tensile steel sheet exhibiting high ductility in the range of 0.30-0.
55% by weight of C, 0.7-2.0% by weight of Si,
After heating a steel sheet containing 5 to 2.0% by weight of Mn (hot-rolled steel sheet, cold-rolled steel sheet) to the austenitic single phase region, 650
After holding at に 750 ° C. for 4 to 15 seconds, 45 minutes
Hold for a total of 10 to 50 seconds between 0 and 650 ° C, and add 1% by volume in martensite or bainite.
A method for producing a mixed structure steel sheet containing 0% or more of ferrite and 10% or more of retained austenite is disclosed.

【０００６】しかし、前記特開昭６１−１５７６２５号
公報あるいは特開昭６０−４３４６４号公報に開示され
た鋼板は、加工による変態誘起塑性が変形初期に行われ
てしまうために局部延性が劣る（穴広げ性が劣る）こ
と、およびこの鋼板は７８０Ｎ／ｍｍ² 以上の強度は得
られるが、自動車用として多用される５９０Ｎ／ｍｍ²
級の低強度の高張力鋼板を得ることが困難であるという
欠点を有している。またこのような高強度−高延性を示
す高張力鋼板は、セメンタイトの析出を抑制するために
Ｓｉを多量に添加しており、溶融亜鉛めっきが困難であ
る。However, the steel sheets disclosed in the above-mentioned JP-A-61-157625 or JP-A-60-43464 are inferior in local ductility because transformation-induced plasticity due to working is performed in the initial stage of deformation. This steel sheet has a strength of 780 N / mm ² or more, but 590 N / mm ² which is frequently used for automobiles.
It has a drawback that it is difficult to obtain a high-strength steel sheet of low grade. In addition, such high-strength steel sheets exhibiting high strength and high ductility contain a large amount of Si in order to suppress precipitation of cementite, and it is difficult to perform hot-dip galvanizing.

【０００７】上記問題点を解決するための方法として、
特開平５−７０８８６号公報、特開平５−１９５０５６
号公報、および特開平６−１４５７８８号公報には、Ａ
ｌ添加型残留オーステナイト鋼および低Ｓｉ型残留オー
ステナイト鋼の製造方法が開示されている。As a method for solving the above problems,
JP-A-5-70886, JP-A-5-195056
And JP-A-6-145788, A
Methods for producing l-added retained austenitic steel and low-Si retained austenitic steel are disclosed.

【０００８】これらの高張力鋼板は、穴広げ性等の局部
延性に優れ、溶融亜鉛めっき化を可能とし、ならびに５
９０Ｎ／ｍｍ² 級の低強度の残留オーステナイトを含む
高張力鋼板を得る方法として有効であり、実用化が期待
されている。[0008] These high-tensile steel sheets are excellent in local ductility such as hole-expanding properties, enable hot-dip galvanizing, and
It is effective as a method for obtaining a high-strength steel sheet containing low-strength retained austenite of 90 N / mm ² class, and is expected to be put to practical use.

【０００９】[0009]

【発明が解決しようとする課題】残留オーステナイト
（γ）鋼への溶融亜鉛めっきを可能とするには、(a) め
っきの濡れ性確保（めっきのはじき防止）と、溶融亜鉛
めっき後に合金化処理を行う場合は、(b) 合金化処理過
程での残留オーステナイトの消失抑制という課題があ
る。In order to enable hot-dip galvanizing of retained austenite (γ) steel, it is necessary to (a) ensure the wettability of the plating (prevent repelling of the plating) and perform an alloying treatment after the hot-dip galvanizing. When performing (b), there is a problem of suppressing the disappearance of retained austenite in the alloying process.

【００１０】とくに熱延鋼板においては、後述するよう
に溶融亜鉛めっきを施すための濡れ性の確保が冷間圧延
鋼板に比べて難しい。In particular, in a hot-rolled steel sheet, it is more difficult to secure wettability for hot-dip galvanizing than in a cold-rolled steel sheet, as described later.

【００１１】また上記の残留オーステナイト鋼は、Ｓｉ
やＡｌを多量に含有しているため、熱間圧延時の変形抵
抗が高く、圧延荷重が増大し製造可能範囲が狭くなると
いう問題もある。Further, the above-mentioned retained austenitic steel is made of Si
Since Al and Al are contained in a large amount, there is a problem that the deformation resistance during hot rolling is high, the rolling load increases, and the manufacturable range is narrowed.

【００１２】しかし、現在までの発明においてはこれら
の問題を解決する具体的な方法は開示されておらず、高
張力高延性をあわせ持つ溶融亜鉛めっき鋼板（合金化溶
融亜鉛めっきを含む）を容易には得られなかった。However, no specific method for solving these problems has been disclosed in the inventions up to the present, and hot-dip galvanized steel sheets (including alloyed hot-dip galvanized steel) having both high tensile strength and high ductility can be easily prepared. Could not be obtained.

【００１３】本発明の課題は、熱延鋼板、冷延鋼板のい
ずれに対しても、高張力高延性鋼板に溶融亜鉛めっきを
容易に行い、溶融亜鉛めっき鋼板および合金化溶融亜鉛
めっき鋼板を製造する方法を提供することにある。An object of the present invention is to easily perform hot-dip galvanizing on a high-tensile, high-ductility steel sheet for both hot-rolled steel sheets and cold-rolled steel sheets to produce hot-dip galvanized steel sheets and alloyed hot-dip galvanized steel sheets. It is to provide a way to do it.

【００１４】[0014]

【課題を解決するための手段】本発明者らは高延性を支
配する残留オーステナイト量を確保しつつ、溶融亜鉛め
っきおよび合金化処理を可能にし、冷延鋼板を母材とし
た場合（以下、冷延ベースという）のみならず、熱延鋼
板を母材とした場合（以下、熱延ベースという）でも、
高張力高延性溶融亜鉛めっき鋼板を得るための製造条件
の検討を行った。Means for Solving the Problems The present inventors have made it possible to perform hot dip galvanizing and alloying while securing the amount of retained austenite that governs high ductility, and to use a cold rolled steel sheet as a base material (hereinafter, referred to as a base material). Not only in cold-rolled base) but also when hot-rolled steel sheet is used as base material (hereinafter called hot-rolled base),
Production conditions for obtaining a high-tensile, high-ductility hot-dip galvanized steel sheet were studied.

【００１５】まず、冷延ベースのめっき鋼板について予
備試験を行った。表１に示す鋼成分Ａの鋼を転炉にて溶
製し、連続鋳造法にてスラブとし、冷却した後、加熱炉
で１２４０℃まで加熱し、熱間圧延の粗圧延温度１０８
０℃、仕上げ圧延温度９２０℃で圧延を完了させ、６０
０℃で巻き取り、３．５ｍｍ厚の熱延コイルとした。そ
の後、１．８ｍｍの厚さまで冷間圧延し、得られた冷延
コイルからサンプルを採取し、実験室での溶融亜鉛めっ
きシミュレータでめっき濡れ性に及ぼす前酸化条件の影
響、引張特性および残留オーステナイト量に及ぼす冷却
速度の影響、低温保持時間の影響、合金化処理条件の影
響などを調査した。First, a preliminary test was performed on a cold-rolled base plated steel sheet. A steel having a steel component A shown in Table 1 was melted in a converter, formed into a slab by a continuous casting method, cooled, and then heated to 1240 ° C. in a heating furnace.
Rolling is completed at 0 ° C and finish rolling temperature of 920 ° C,
Winding was performed at 0 ° C. to form a hot-rolled coil having a thickness of 3.5 mm. Thereafter, the sample was cold-rolled to a thickness of 1.8 mm, a sample was taken from the obtained cold-rolled coil, and the effect of pre-oxidation conditions on plating wettability, tensile properties and residual austenite in a galvanizing simulator in a laboratory. The effects of cooling rate, low-temperature holding time, and alloying treatment conditions on the amount were investigated.

【００１６】[0016]

【表１】 [Table 1]

【００１７】前酸化条件の影響調査では、溶融亜鉛めっ
きシミュレータにて前酸化（板温度４５０〜８００℃、
雰囲気酸素濃度５０ｐｐｍ）、焼鈍（板温度８４０℃×
１５ｓ）、次いで５℃／ｓで４７０℃まで冷却し、低温
保持（板温度４７０℃×４０ｓ）、その後溶融亜鉛めっ
き処理（両面６０ｇ／ｍ² 目付）、合金化処理（板温度
６００℃）を行った。この試料で、前酸化とめっき濡れ
性の関係を調査した。In the investigation of the influence of the pre-oxidation conditions, the pre-oxidation (plate temperature 450-800 ° C.,
Atmospheric oxygen concentration 50 ppm), annealing (plate temperature 840 ° C x
15 s), then cooled to 470 ° C. at 5 ° C./s, kept at low temperature (plate temperature 470 ° C. × 40 s), then hot-dip galvanized (both sides 60 g / m ² basis weight), alloyed (plate temperature 600 ° C.) went. With this sample, the relationship between pre-oxidation and plating wettability was investigated.

【００１８】めっき濡れ性の指標にはＦｅ₂ Ｏ₃ 量、拡
散Ｆｅ量およびめっき濡れ性外観を用いた。これは、Ｆ
ｅ₂ Ｏ₃ 量が多いほど前酸化での母材の酸化が進展した
ことを示し、生成した酸化鉄は還元性雰囲気の焼鈍過程
で還元鉄となって、還元鉄量が多い程めっきの濡れ性が
向上するためである。逆に、母材のＳｉ濃度が高いとき
または母材表面にＳｉＯ₂ が濃化していると、前酸化処
理を行っても母材の酸化が進展せず、その後の還元焼鈍
によっても還元鉄が生成しないためめっきの濡れ性が低
下する。また、めっき皮膜中に拡散した拡散Ｆｅ量を測
定するのは、めっきの濡れ性が大きいほど、前記拡散Ｆ
ｅ量が大きくなるからである。As the index of plating wettability, the amount of Fe ₂ O _{3, the} amount of diffused Fe and the appearance of plating wettability were used. This is F
The larger the amount of e ₂ O _{3, the} more the oxidation of the base metal in the pre-oxidation progressed. The generated iron oxide became reduced iron in the annealing process in a reducing atmosphere, and the larger the amount of reduced iron, the greater the wetting of the plating. This is because the property is improved. Conversely, when the Si concentration of the base material is high or when SiO ₂ is concentrated on the base material surface, the oxidation of the base material does not progress even if the pre-oxidation treatment is performed, and the reduced iron is reduced by the subsequent reduction annealing. Since it is not formed, the wettability of the plating decreases. Further, the amount of the diffused Fe diffused into the plating film is measured as the wettability of the plating increases, as the diffusion F
This is because the amount of e increases.

【００１９】Ｆｅ₂ Ｏ₃ 量は前酸化で生成した酸化スケ
ールについてＸ線回折線強度（ＣＰＳ）で評価し、Ｆｅ
拡散量は原子吸光法で分析して得られためっき皮膜中の
Ｆｅ量とした。めっきの濡れ性外観はめっき表面を目視
にて判定した。The amount of Fe ₂ O ₃ was evaluated by X-ray diffraction line intensity (CPS) for the oxidized scale formed by the pre-oxidation,
The amount of diffusion was the amount of Fe in the plating film obtained by analysis by the atomic absorption method. The wettability appearance of the plating was determined by visually observing the plating surface.

【００２０】図１は前酸化温度とめっきの濡れ性指標の
関係を示すグラフである。同図に示すように、前酸化温
度の上昇とともにＦｅ拡散量が増え、めっきの濡れ性が
改善されていることがわかる。FIG. 1 is a graph showing the relationship between the pre-oxidation temperature and the index of plating wettability. As shown in the figure, it can be seen that the Fe diffusion amount increases with an increase in the pre-oxidation temperature, and the wettability of the plating is improved.

【００２１】冷却速度条件の調査では、溶融亜鉛めっき
シミユレータで前酸化し（６００℃、酸素濃度５０ｐｐ
ｍ）、焼鈍し（８４０℃×１５ｓ）、各種の冷却速度で
冷却し、低温保持（４２０℃×４０ｓ）した後、溶融亜
鉛めっき処理（両面６０ｇ／ｍ² 目付）、合金化処理
（５４０℃）を行った。この試料で、冷却速度とＪＩＳ
５号引張試験によるＹＳ、ＴＳ、Ｅｌを測定し、さらに
試験片の厚さの１／４を化学研磨後、Ｘ線回折により残
留オーステナイト量を調査した。In examining the cooling rate conditions, pre-oxidation was performed using a hot-dip galvanizing simulator (600 ° C., oxygen concentration 50 pp.
m), annealing (840 ° C. × 15 s), cooling at various cooling rates, keeping at low temperature (420 ° C. × 40 s), hot-dip galvanizing (both sides 60 g / m ² basis weight), alloying (540 ° C. ) Was done. With this sample, the cooling rate and JIS
YS, TS, and El were measured by a No. 5 tensile test, and after 1/4 of the thickness of the test piece was chemically polished, the amount of retained austenite was investigated by X-ray diffraction.

【００２２】低温保持時間の影響調査では、溶融亜鉛め
っきシミユレータで前酸化し（６００℃、酸素濃度５０
ｐｐｍ）、焼鈍し（８４０℃×１５ｓ）、３℃／ｓで４
２０℃まで冷却し、４２０℃での保持時間を変化させた
後、溶融亜鉛めっき処理し（両面６０ｇ／ｍ² 目付）、
合金化処理（５３０℃）を行い、保持時間とＹＳ、Ｔ
Ｓ、Ｅｌ、残留オーステナイト量の関係を調査した。In the investigation of the effect of the low-temperature holding time, pre-oxidation was performed using a hot-dip galvanizing simulator (600 ° C., oxygen concentration 50%).
ppm), annealing (840 ° C. × 15 s), 4 at 3 ° C./s
After cooling to 20 ° C. and changing the holding time at 420 ° C., hot-dip galvanizing (both sides 60 g / m ² basis weight)
Perform alloying treatment (530 ° C), hold time, YS, T
The relationship between S, El and the amount of retained austenite was investigated.

【００２３】合金化処理条件の影響調査では、溶融亜鉛
めっきシミユレータで前酸化（６００℃、酸素濃度５０
ｐｐｍ）、焼鈍（８４０℃×１５ｓ）、５℃／ｓで４７
０℃まで冷却し、低温保持（４７０℃×４０ｓ）した
後、溶融亜鉛めっき処理（両面６０ｇ／ｍ² 目付）、合
金化処理（４８０〜６４０℃）の順で行い、合金化処理
温度とＹＳ、ＴＳ、Ｅｌ、残留オーステナイト量の関係
を調査した。Investigation of the influence of alloying treatment conditions revealed that pre-oxidation (600 ° C., oxygen concentration 50
ppm), annealing (840 ° C. × 15 s), 47 ° C. at 5 ° C./s
After cooling to 0 ° C. and holding at a low temperature (470 ° C. × 40 s), hot-dip galvanizing (both sides 60 g / m ² basis weight) and alloying (480-640 ° C.) are performed in this order. , TS, El and the amount of retained austenite were investigated.

【００２４】図２は冷却速度と引張特性、残留オーステ
ナイト量の関係を示すグラフである。図３は低温保持時
間と引張特性、残留オーステナイト量の関係を示すグラ
フである。FIG. 2 is a graph showing the relationship between the cooling rate, the tensile properties, and the amount of retained austenite. FIG. 3 is a graph showing the relationship between the low-temperature holding time, the tensile characteristics, and the amount of retained austenite.

【００２５】図４は合金化処理温度と引張特性、残留オ
ーステナイト量の関係を示すグラフである。図２〜４に
示すように、冷却速度が３℃／ｓ以上、低温保持時間が
２０ｓ以上、合金化処理温度が６００℃以下のものが残
留オーステナイト量で５体積％以上を示しＥｌについて
も優れた特性を示している。FIG. 4 is a graph showing the relationship between the alloying temperature, the tensile properties, and the amount of retained austenite. As shown in FIGS. 2 to 4, those having a cooling rate of 3 ° C./s or more, a low-temperature holding time of 20 s or more, and an alloying treatment temperature of 600 ° C. or less show a residual austenite amount of 5% by volume or more, and are also excellent in El. It shows the characteristic.

【００２６】次に、熱延ベースのめっき鋼板について冷
延ベースと同様に予備試験を行った。冷延ベースの場合
と同様に表１に示す鋼成分Ａのスラブを製造し、加熱炉
で１２４０℃まで加熱し、粗圧延温度１０８０℃、仕上
げ圧延温度８９０℃で熱間圧延を完了させ、５８０℃で
巻き取り、２．０ｍｍ厚の熱延コイルを得た。この熱延
コイルを酸洗後２分割し、１本はそのまま、他の１本は
研削ラインのブラシロールにて３ｇ／ｍ² の表面研削を
行った。Next, a preliminary test was performed on the hot-rolled base plated steel sheet in the same manner as the cold-rolled base. A slab of the steel component A shown in Table 1 was manufactured in the same manner as in the case of the cold-rolled base, and heated to 1240 ° C. in a heating furnace, and hot rolling was completed at a rough rolling temperature of 1080 ° C. and a finish rolling temperature of 890 ° C. C. to be wound at 2.0.degree. The hot-rolled coil was pickled and then divided into two parts, one of which was subjected to surface grinding at 3 g / m ² with a brush roll of a grinding line while the other one was kept as it was.

【００２７】次にこれら熱延コイルからサンプルを採取
し、冷延ベースの場合と同様に、実験室での溶融亜鉛め
っきシミュレータでめっき濡れ性に及ぼす前酸化条件の
影響、引張特性、残留オーステナイト量に及ぼす熱処理
条件と合金化処理条件の影響調査を行った。Next, samples were taken from these hot-rolled coils, and in the same way as in the case of the cold-rolled base, the effect of pre-oxidation conditions on plating wettability, tensile properties, residual austenite amount in a galvanizing simulator in a laboratory. The effect of heat treatment conditions and alloying treatment conditions on the temperature was investigated.

【００２８】前酸化条件の影響調査では、溶融亜鉛めっ
きシミュレータにて前酸化し（４５０〜８００℃、酸素
濃度５０ｐｐｍ）、焼鈍し（８４０℃×１５ｓ）、次い
で５℃／ｓで４７０℃まで冷却し、低温保持し（４７０
℃×４０ｓ）、その後溶融亜鉛めっき処理（両面６０ｇ
／ｍ² 目付）を行い、合金化処理（６００℃）を行っ
た。この試料で、前酸化とめっき濡れ性指標との関係を
調査した。めっき濡れ性指標（Ｆｅ₂ Ｏ₃ 量、拡散Ｆｅ
量、めっき濡れ性外観）の測定方法は冷延ベースの場合
と同じである。In investigating the influence of the pre-oxidation conditions, pre-oxidation (450-800 ° C., oxygen concentration 50 ppm) and annealing (840 ° C. × 15 s) were performed in a hot-dip galvanizing simulator, and then cooled to 470 ° C. at 5 ° C./s. And kept at low temperature (470
℃ 40s), then hot-dip galvanizing (60g on both sides)
/ M ² ), and an alloying treatment (600 ° C.) was performed. For this sample, the relationship between the pre-oxidation and the plating wettability index was investigated. Plating wettability index (Fe ₂ O ₃ amount, diffusion Fe
The method for measuring the amount and appearance of plating wettability) is the same as in the case of the cold-rolled base.

【００２９】図５は熱延鋼板に合金化溶融亜鉛めっきを
した場合の、前酸化温度とめっきの濡れ性指標の関係を
示すグラフである。同図に示すように、前酸化温度の上
昇とともにＦｅ拡散量が増え、めっきの濡れ性が改善さ
れていることがわかる。FIG. 5 is a graph showing the relationship between the pre-oxidation temperature and the index of wettability of plating when hot-rolled steel sheet is galvannealed. As shown in the figure, it can be seen that the Fe diffusion amount increases with an increase in the pre-oxidation temperature, and the wettability of the plating is improved.

【００３０】一方、表面をブラシ研削していない試料は
酸化鉄量およびＦｅ拡散量とも少なく、濡れ性も不芳で
ある。冷却速度条件の影響、低温保持時間の影響、合金
化処理条件の影響についても、冷延ベースの場合と同じ
条件の試験および調査を行った。On the other hand, the sample whose surface is not brush-ground has a small amount of iron oxide and a small amount of Fe diffusion, and has poor wettability. Regarding the effects of the cooling rate conditions, the effects of the low-temperature holding time, and the effects of the alloying treatment conditions, tests and investigations were performed under the same conditions as in the case of the cold rolling base.

【００３１】図６は冷却速度と引張特性、残留オーステ
ナイト量の関係を示すグラフである。図７は低温保持時
間と引張特性、残留オーステナイト量の関係を示すグラ
フである。FIG. 6 is a graph showing the relationship between the cooling rate, the tensile properties, and the amount of retained austenite. FIG. 7 is a graph showing the relationship between the low-temperature holding time, the tensile properties, and the amount of retained austenite.

【００３２】図８は合金化処理温度と引張特性、残留オ
ーステナイト量の関係を示すグラフである。図６〜８に
示すように、冷却速度が３℃／ｓ以上、低温保持時間が
２０ｓ以上、合金化処理温度が６００℃以下のものが残
留オーステナイト量で５体積％以上を示しＥｌについて
も優れた特性を示している。FIG. 8 is a graph showing the relationship between the alloying temperature, the tensile properties, and the amount of retained austenite. As shown in FIGS. 6 to 8, those having a cooling rate of 3 ° C./s or more, a low-temperature holding time of 20 s or more, and an alloying treatment temperature of 600 ° C. or less show a residual austenite amount of 5% by volume or more, and are also excellent in El. It shows the characteristic.

【００３３】以上の冷延ベースおよび熱延ベースの予備
試験の結果、以下の知見を得た。まず、冷延ベースの場
合、めっきの濡れ性改善と残留オーステナイト量の確保
は、連続溶融亜鉛めっきラインでの前酸化条件、焼鈍条
件、冷却保持条件、および合金化溶融亜鉛めっきの合金
化処理条件の制御で可能とであることがわかった。As a result of the preliminary tests on the cold-rolled base and the hot-rolled base, the following findings were obtained. First, in the case of the cold-rolled base, the improvement of the wettability of the plating and the securing of the amount of retained austenite are determined by the pre-oxidation condition, annealing condition, cooling holding condition, and alloying treatment condition of the galvannealed steel in the continuous galvanizing line. It was found that control was possible.

【００３４】また、熱延ベースの場合、鋼板表面は焼鈍
された状態にあり、加工ひずみが蓄積された状態ではな
い。従って、前酸化処理を行っても母材表面の酸化が十
分行われず、その後の還元雰囲気中焼鈍でめっき濡れ性
を支配する還元Ｆｅの生成が十分行われないため、冷延
鋼板と比較して溶融亜鉛めっきの濡れ性が劣ることがわ
かった。これに対して熱延鋼板に何らかの表面ひずみを
付与すれば、表面が活性化し、前酸化処理での酸化鉄生
成と、還元雰囲気焼鈍での還元鉄の生成が十分行われる
ため濡れ性が改善されることがわかった。In the case of a hot-rolled base, the surface of the steel sheet is in an annealed state, and is not in a state where working strain is accumulated. Therefore, even if the pre-oxidation treatment is performed, the base material surface is not sufficiently oxidized, and the reduction Fe that governs the plating wettability is not sufficiently generated in the subsequent annealing in a reducing atmosphere. It was found that the hot-dip galvanizing had poor wettability. On the other hand, if any surface strain is imparted to the hot-rolled steel sheet, the surface is activated and the iron oxide is generated by the pre-oxidation treatment and the reduced iron is generated by the annealing in the reducing atmosphere, so that the wettability is improved. I found out.

【００３５】加工ひずみを付与する方法として、発明者
らは熱延鋼板を上記のようにブラシ研削する方法のほ
か、ショットブラストを施す方法および軽圧下する方法
を検討し、これらの処理によって軽度の表面ひずみを与
えてやれば前記の濡れ性改善効果があるという知見を得
た。As a method of imparting working strain, the present inventors studied a method of applying shot blasting and a method of slightly reducing the pressure, in addition to the method of brush grinding a hot-rolled steel sheet as described above. It has been found that the application of surface strain has the effect of improving the wettability.

【００３６】製造可能範囲拡大のための熱間変形抵抗低
下は、熱間圧延の仕上げ温度の高温化で可能であること
を見いだした。連続溶融亜鉛めっきライン以後は冷延鋼
板と同様の製造条件でよいこともわかった。It has been found that a reduction in hot deformation resistance for expanding the range in which production is possible is possible by increasing the finishing temperature of hot rolling. After the continuous hot-dip galvanizing line, it was found that the same production conditions as for the cold-rolled steel sheet were sufficient.

【００３７】上記の知見に基づいて、本発明の要旨は、
次の(1) 〜(6) の高延性高張力溶融亜鉛めっき鋼板の製
造方法にある。Based on the above findings, the gist of the present invention is as follows:
The present invention relates to the following (1) to (6) methods for producing a high ductility and high tensile galvanized steel sheet.

【００３８】(1) 化学組成が重量％で、Ｃ：０．０６〜
０．２５％、Ｓｉ：１．０％以下、Ｍｎ：０．５〜３．
０％、Ｐ：０．０３％以下、Ｓ：０．０３０％以下、Ａ
ｌ：０．４〜２．５％、Ｔｉ：０．００３〜０．０８０
％、Ｎ：０．０１０％以下で、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／１４）Ｎ＋（４８／３２）Ｓ＋０．０１
０の条件を満たし、残部がＦｅおよび不可避的不純物か
らなる鋼組成を有する冷延鋼板に、板温度５５０〜７５
０℃で前酸化を行い、７６０〜９００℃の２相域温度で
５秒以上保持して焼鈍を行い、次いで３℃／ｓ以上の冷
却速度で４２０〜６００℃の温度域まで冷却し、この温
度域で２０秒以上保持する冷却保持を行い、溶融亜鉛浴
に浸入させてめっきを施して、溶融亜鉛めっき鋼板を製
造することを特徴とする高張力高延性亜鉛めっき鋼板の
製造方法。(1) Chemical composition in weight%, C: 0.06 to
0.25%, Si: 1.0% or less, Mn: 0.5-3.
0%, P: 0.03% or less, S: 0.030% or less, A
l: 0.4 to 2.5%, Ti: 0.003 to 0.080
%, N: 0.010% or less, and (48/14) N ≦
Ti ≦ (48/14) N + (48/32) S + 0.01
0, and the balance of the cold-rolled steel sheet having a steel composition consisting of Fe and unavoidable impurities has a sheet temperature of 550-75.
Pre-oxidation is performed at 0 ° C., annealing is performed at a temperature in a two-phase region of 760 to 900 ° C. for 5 seconds or more, and then cooled to a temperature range of 420 to 600 ° C. at a cooling rate of 3 ° C./s or more. A method for producing a high-tensile, high-ductility galvanized steel sheet, which comprises performing cooling and holding at a temperature range of 20 seconds or more, infiltrating into a hot-dip zinc bath, and performing plating to produce a hot-dip galvanized steel sheet.

【００３９】(2) 化学組成が重量％で、Ｃ：０．０６〜
０．２５％、Ｓｉ：１．０％以下、Ｍｎ：０．５〜３．
０％、Ｐ：０．０３％以下、Ｓ：０．０３０％以下、Ａ
ｌ：０．４〜２．５％、Ｔｉ：０．００３〜０．０８０
％、Ｎ：０．０１０％以下で、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／１４）Ｎ＋（４８／３２）Ｓ＋０．０１
０の条件を満たし、残部がＦｅおよび不可避的不純物か
らなる鋼組成を有する冷延鋼板に、板温度５５０〜７５
０℃で前酸化を行い、７６０〜９００℃の２相域温度で
５秒以上保持して焼鈍を行い、次いで３℃／ｓ以上の冷
却速度で４２０〜６００℃の温度域まで冷却し、この温
度域で２０秒以上保持する冷却保持を行い、溶融亜鉛浴
に浸入させてめっきを施し、さらに６００℃以下で合金
化処理を行って、合金化溶融亜鉛めっき鋼板を製造する
ことを特徴とする高張力高延性亜鉛めっき鋼板の製造方
法。(2) The chemical composition is% by weight and C: 0.06 to
0.25%, Si: 1.0% or less, Mn: 0.5-3.
0%, P: 0.03% or less, S: 0.030% or less, A
l: 0.4 to 2.5%, Ti: 0.003 to 0.080
%, N: 0.010% or less, and (48/14) N ≦
Ti ≦ (48/14) N + (48/32) S + 0.01
0, and the balance of the cold-rolled steel sheet having a steel composition consisting of Fe and unavoidable impurities has a sheet temperature of 550-75.
Pre-oxidation is performed at 0 ° C., annealing is performed at a temperature in a two-phase region of 760 to 900 ° C. for 5 seconds or more, and then cooled to a temperature range of 420 to 600 ° C. at a cooling rate of 3 ° C./s or more. It is characterized by producing a galvannealed steel sheet by performing cooling and holding for at least 20 seconds in a temperature range, immersing it in a molten zinc bath, performing plating, and further performing alloying treatment at 600 ° C or less. A method for producing high-tensile, high-ductility galvanized steel sheets.

【００４０】(3) 前記(1) または(2) 項に記載の冷延鋼
板が、さらに、Ｎｉ：０．１％以下、Ｃｒ：１．０％以
下、Ｍｏ：０．６％以下、Ｃｕ：１．０％以下、Ｎｂ：
０．０５％以下、Ｖ：０．０８％以下、Ｚｒ：０．０５
％以下およびＢ：０．００３％以下からなる群から選ん
だ１種または２種以上を含有することを特徴とする高張
力高延性亜鉛めっき鋼板の製造方法。(3) The cold-rolled steel sheet according to the above (1) or (2) further comprises Ni: 0.1% or less, Cr: 1.0% or less, Mo: 0.6% or less, Cu: : 1.0% or less, Nb:
0.05% or less, V: 0.08% or less, Zr: 0.05
% Or less and B: one or more selected from the group consisting of 0.003% or less.

【００４１】(4) 化学組成が重量％で、Ｃ：０．０６〜
０．２５％、Ｓｉ：１．０％以下、Ｍｎ：０．５〜３．
０％、Ｐ：０．０３％以下、Ｓ：０．００５％以下、Ａ
ｌ：０．４〜２．５％、Ｔｉ：０．００３〜０．０８０
％、Ｎ：０．０１０％以下で、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／１４）Ｎ＋（４８／３２）Ｓ＋０．０１
０の条件を満たし、残部がＦｅおよび不可避的不純物か
らなる鋼組成を有する熱延鋼板に、スケール除去処理お
よび少なくともその表面へのひずみ付与加工を行い、板
温度５５０〜７５０℃で前酸化を行い、７６０〜９００
℃の２相域温度で５秒以上保持して焼鈍を行い、次いで
３℃／ｓ以上の冷却速度で４２０〜６００℃の温度域ま
で冷却し、この温度域で２０秒以上保持する冷却保持を
行い、溶融亜鉛浴に浸入させてめっきを施して、溶融亜
鉛めっき鋼板を製造することを特徴とする高張力高延性
亜鉛めっき鋼板の製造方法。(4) The chemical composition is expressed in% by weight, and C: 0.06 to
0.25%, Si: 1.0% or less, Mn: 0.5-3.
0%, P: 0.03% or less, S: 0.005% or less, A
l: 0.4 to 2.5%, Ti: 0.003 to 0.080
%, N: 0.010% or less, and (48/14) N ≦
Ti ≦ (48/14) N + (48/32) S + 0.01
0, the balance of the hot-rolled steel sheet having a steel composition consisting of Fe and unavoidable impurities is subjected to scale removal treatment and strain imparting at least to its surface, and pre-oxidized at a plate temperature of 550 to 750 ° C. , 760-900
Annealing is carried out at a temperature in a two-phase region of at least 5 ° C. for at least 5 seconds, and then cooled to a temperature range of 420 to 600 ° C. at a cooling rate of at least 3 ° C./s. And producing a hot-dip galvanized steel sheet by dipping the steel sheet into a hot-dip galvanizing bath and performing plating.

【００４２】(5) 化学組成が重量％で、Ｃ：０．０６〜
０．２５％、Ｓｉ：１．０％以下、Ｍｎ：０．５〜３．
０％、Ｐ：０．０３％以下、Ｓ：０．００５％以下、Ａ
ｌ：０．４〜２．５％、Ｔｉ：０．００３〜０．０８０
％、Ｎ：０．０１０％以下で、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／１４）Ｎ＋（４８／３２）Ｓ＋０．０１
０の条件を満たし、残部がＦｅおよび不可避的不純物か
らなる鋼組成を有する熱延鋼板に、スケール除去処理お
よび少なくともその表面へのひずみ付与加工を行い、板
温度５５０〜７５０℃で前酸化を行い、７６０〜９００
℃の２相域温度で５秒以上保持して焼鈍を行い、次いで
３℃／ｓ以上の冷却速度で４２０〜６００℃の温度域ま
で冷却し、この温度域で２０秒以上保持する冷却保持を
行い、溶融亜鉛浴に浸入させてめっきを施し、さらに６
００℃以下で合金化処理を行って、合金化溶融亜鉛めっ
き鋼板を製造することを特徴とする高張力高延性亜鉛め
っき鋼板の製造方法。(5) Chemical composition in weight%, C: 0.06 to
0.25%, Si: 1.0% or less, Mn: 0.5-3.
0%, P: 0.03% or less, S: 0.005% or less, A
l: 0.4 to 2.5%, Ti: 0.003 to 0.080
%, N: 0.010% or less, and (48/14) N ≦
Ti ≦ (48/14) N + (48/32) S + 0.01
0, the balance of the hot-rolled steel sheet having a steel composition consisting of Fe and unavoidable impurities is subjected to scale removal treatment and strain imparting at least to its surface, and pre-oxidized at a plate temperature of 550 to 750 ° C. , 760-900
Annealing is carried out at a temperature in a two-phase region of at least 5 ° C. for at least 5 seconds, and then cooled to a temperature range of 420 to 600 ° C. at a cooling rate of at least 3 ° C./s. And then immersion in a molten zinc bath for plating,
A method for producing a galvanized steel sheet having a high tensile strength and a high ductility, wherein an alloying treatment is performed at a temperature of 00 ° C. or less to produce a galvannealed steel sheet.

【００４３】(6) 前記(4) または(5) 項に記載の熱延鋼
板が、さらに、Ｎｉ：０．１％以下、Ｃｒ：１．０％以
下、Ｍｏ：０．６％以下、Ｃｕ：１．０％以下、Ｎｂ：
０．０５％以下、Ｖ：０．０８％以下、Ｚｒ：０．０５
％以下およびＢ：０．００３％以下からなる群から選ん
だ１種または２種以上を含有することを特徴とする高張
力高延性亜鉛めっき鋼板の製造方法。(6) The hot-rolled steel sheet according to the above (4) or (5) further comprises: Ni: 0.1% or less; Cr: 1.0% or less; Mo: 0.6% or less; : 1.0% or less, Nb:
0.05% or less, V: 0.08% or less, Zr: 0.05
% Or less and B: one or more selected from the group consisting of 0.003% or less.

【００４４】[0044]

【発明の実施の形態】本発明における化学組成の限定理
由について説明する。以下の説明において、組成％は重
量％とする。DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the chemical composition in the present invention will be described. In the following description, the composition% is weight%.

【００４５】Ｃ：Ｃは鋼の強化元素であるとともに、本
発明の方法により製造される鋼の特徴である変態誘起塑
性による延性の向上に必要な残留オーステナイトの生成
量、安定性に大きく影響を与える。Ｃはオーステナイト
安定化元素で２相域生成時またはベイナイト変態時にフ
ェライト中からオーステナイト中に濃化し、オーステナ
イトの化学的安定度を向上させるために、室温でオース
テナイトを残留させる効果を有する。C: C is a strengthening element of steel, and has a great influence on the amount and stability of retained austenite necessary for improving ductility due to transformation induced plasticity, which is a feature of steel produced by the method of the present invention. give. C is an austenite-stabilizing element and is concentrated from ferrite to austenite during the formation of the two-phase region or bainite transformation, and has the effect of retaining austenite at room temperature in order to improve the chemical stability of austenite.

【００４６】Ｃが０．０６％未満においては５体積％以
上の残留オーステナイトを確保することが困難である。
また、０．２５％を超えると溶接性の劣化や過剰な強度
上昇を招く。したがってＣの含有量は、０．０６〜０．
２５％とする。好ましくは０．１０〜０．２０％であ
る。When C is less than 0.06%, it is difficult to secure 5% by volume or more of retained austenite.
On the other hand, when the content exceeds 0.25%, the weldability is deteriorated and the strength is excessively increased. Therefore, the content of C is 0.06 to 0.
25%. Preferably it is 0.10 to 0.20%.

【００４７】Ｓｉ：Ｓｉはセメンタイトに固溶せず、そ
の析出を抑制するためにオーステナイトからの変態を遅
れさせ、オーステナイト中へのＣ濃化を促進させる。こ
れにより残留オーステナイトの安定度が増すため、室温
においても変態誘起塑性を示す残留オーステナイトを生
成させる効果がある。ただし、同様の効果はＡｌで得ら
れるし、Ｓｉはめっきの濡れ性に悪影響をもたらすので
特に下限規制はしない。Ｓｉ量が１．０％を超えると表
層にＳｉ酸化物が形成され、強く前酸化を行っても酸化
鉄の生成が抑制されるため、めっきの濡れ性が改善され
ず、合金化溶融亜鉛めっき化が不可能となる。従って上
限を１．０％とする。好ましくは０．８％以下、更に好
ましくは０．３％以下である。Si: Si does not form a solid solution in cementite, but delays transformation from austenite to suppress its precipitation and promotes C enrichment in austenite. Thereby, the stability of the retained austenite is increased, so that there is an effect of generating the retained austenite exhibiting the transformation-induced plasticity even at room temperature. However, the same effect can be obtained with Al, and Si has an adverse effect on the wettability of plating, so there is no particular lower limit. If the Si content exceeds 1.0%, a Si oxide is formed on the surface layer, and the generation of iron oxide is suppressed even if strong pre-oxidation is performed. Is impossible. Therefore, the upper limit is set to 1.0%. Preferably it is 0.8% or less, more preferably 0.3% or less.

【００４８】Ｍｎ：Ｍｎはオーステナイト安定化元素で
あるとともに、冷却する途上でオーステナイトがパーラ
イトに変態するのを防ぐ。０．５％未満ではパーライト
への変態を抑制することが困難である。Mn: Mn is an austenite stabilizing element and also prevents austenite from transforming to pearlite during cooling. If it is less than 0.5%, it is difficult to suppress the transformation to pearlite.

【００４９】また、３．０％を超えると鋼板の焼き入れ
性を高めるため、強度が過度に上昇し、延性の劣化を招
く。したがって、Ｍｎの含有量は、０．５〜３．０％と
する。好ましくは１．０〜２．０％である。On the other hand, if the content exceeds 3.0%, the hardenability of the steel sheet is increased, so that the strength is excessively increased and the ductility is deteriorated. Therefore, the content of Mn is set to 0.5 to 3.0%. Preferably it is 1.0 to 2.0%.

【００５０】Ｐ：合金化溶融亜鉛めっき鋼板の場合、Ｐ
量が高いと合金化処理性が劣化し合金化温度の高温化が
必要になる。合金化温度が高くなると上述したように残
留オーステナイトが消失し高延性を示さなくなる。した
がって、合金化処理性を劣化させない程度にする必要が
あり、Ｐの含有量は０．０３％以下とする。合金化処理
を行わない溶融亜鉛めっきの場合でもＰ量が高いと延性
が低下するため、同様に０．０３％以下とする。いずれ
の場合も好ましくは０．０２％以下である。P: In the case of a galvannealed steel sheet, P
If the amount is high, the alloying processability deteriorates, and it is necessary to raise the alloying temperature. When the alloying temperature increases, the retained austenite disappears as described above, and high ductility is not exhibited. Therefore, it is necessary that the alloying property is not deteriorated, and the P content is set to 0.03% or less. Even in the case of hot-dip galvanizing without alloying treatment, if the P content is high, ductility decreases, so that the content is similarly set to 0.03% or less. In each case, the content is preferably 0.02% or less.

【００５１】Ｓ：Ｓ量の増加に伴いＡ系介在物が多数生
成するために穴広げ性の劣化をもたらす。冷延ベースの
場合、穴広げ性確保のため、Ｓ量は０．０３０％以下と
する。好ましくは０．０１０％以下である。S: As the amount of S increases, a large number of A-based inclusions are generated, which causes deterioration of hole expanding properties. In the case of a cold-rolled base, the amount of S is set to 0.030% or less in order to secure hole expanding properties. Preferably it is 0.010% or less.

【００５２】熱延ベースの場合、自動車用に使用される
板厚は冷延鋼板より厚く、伸び−フランジ性が要求され
る部品への適用が多いため、Ｓ系介在物は冷延ベースの
場合より厳しく上限管理する必要があるため、Ｓ量は
０．００５％以下とする。好ましくは０．００３％以下
である。In the case of a hot-rolled base, the thickness used for automobiles is thicker than that of a cold-rolled steel sheet, and it is often applied to parts that require elongation-flangeability. Since it is necessary to control the upper limit more strictly, the S amount is set to 0.005% or less. Preferably it is 0.003% or less.

【００５３】Ｔｉ：Ｔｉは鋳込み時の表面割れの原因で
あるＡｌＮ生成を抑制し、ＮをＴｉＮとして析出固定す
る。Ｔｉ％が（４８／１４）Ｎ％のときは、ＮをＴｉＮ
として完全に固定することができず、スラブ表面割れの
要因となるＡｌＮが生成する。Ti: Ti suppresses the formation of AlN, which causes surface cracking during casting, and precipitates and fixes N as TiN. When Ti% is (48/14) N%, N is TiN
Cannot be fixed completely, and AlN which causes slab surface cracks is generated.

【００５４】また、Ｔｉ＞（４８／１４）Ｎ＋（４８／
３２）Ｓ＋０．０１０またはＴｉ＞０．０８０％におい
ては、ＴｉＣの生成量が増大し析出強化による過度の強
度上昇、ならびにオーステナイト中に濃化するＣ量の絶
対量が低下し、Ｃ濃化によるオーステナイトの化学的安
定への効果が少なくなるため、残留オーステナイト生成
量が減り延性が劣化する。Also, Ti> (48/14) N + (48 /
32) In the case of S + 0.010 or Ti> 0.080%, the amount of TiC produced increases and the excessive increase in strength due to precipitation strengthening, and the absolute amount of C enriched in austenite decreases, resulting in an increase in C enrichment. Since the effect of austenite on the chemical stability is reduced, the amount of retained austenite is reduced and ductility is deteriorated.

【００５５】また、Ｔｉ量が０．００３％の時に、（４
８／１４）Ｎ≦Ｔｉを満たすには、Ｎ量を０．０００９
％未満にする必要があり、現状の量産製鋼法では達成困
難なレベルである。したがって、Ｔｉ含有量は０．００
３〜０．０８０％の範囲とし、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／３２）Ｓ＋（４８／１４）Ｎ＋０．０１
０の条件を満たすようにする。When the Ti content is 0.003%, (4
8/14) To satisfy N ≦ Ti, the N amount is 0.0009
%, Which is a level that is difficult to achieve with current mass production steelmaking methods. Therefore, the Ti content is 0.00
3 to 0.080%, and (48/14) N ≦
Ti ≦ (48/32) S + (48/14) N + 0.01
The condition of 0 is satisfied.

【００５６】Ａｌ：ＡｌはＳｉと同様、室温で安定な残
留オーステナイトの生成に必要な元素である。Ａｌもセ
メンタイトに固溶せず、３５０〜６００℃に等温保持し
てベイナイト変態させる時にセメンタイトの析出を抑制
し、変態を遅らせる。また、Ｓｉよりもフェライト形成
能が強く、フェライト変態開始は早くなる。そのため、
短時間の等温保持においても２相域共存温度での焼鈍時
にオーステナイト中にＣが濃化され、オーステナイトの
化学的安定が図れ、結果として生成したオーステナイト
のＣ濃度は高く、生成する残留オーステナイト量は多く
なり、高歪域において高い加工硬化特性を示し高延性を
示す。Al: Like Si, Al is an element necessary for producing stable austenite at room temperature. Al also does not form a solid solution in cementite, and suppresses the precipitation of cementite and delays the transformation during bainite transformation while maintaining the isothermal temperature at 350 to 600 ° C. Further, the ferrite forming ability is stronger than that of Si, and the ferrite transformation starts earlier. for that reason,
C is concentrated in austenite during annealing at a two-phase coexistence temperature even during isothermal holding for a short period of time, whereby the chemical stability of austenite can be achieved. As a result, the C concentration of austenite formed is high, and the amount of retained austenite formed is It increases and shows high work hardening characteristics and high ductility in a high strain range.

【００５７】また、合金化溶融亜鉛めっき化を目的とし
てＳｉ量の低減が必要となり、Ｓｉを低下させるとセメ
ンタイトが生成しやすくなる。そこで、Ｓｉを低下させ
るかわりにＡｌ含有量を増大させ、Ｓｉ低下分によるセ
メンタイト生成能の増大を抑制する必要がある。Further, it is necessary to reduce the amount of Si for the purpose of galvannealing, and when Si is reduced, cementite is likely to be generated. Therefore, instead of reducing Si, it is necessary to increase the Al content to suppress the increase in the ability to generate cementite due to the decrease in Si.

【００５８】Ｓｉを１．０％以下とする条件のもとで
は、Ａｌを０．４％以上としなければセメンタイトの生
成能の増大を抑制することができない。しかし、２．５
％を超えて含有させると、冷延ベースの場合は酸洗ライ
ンの通板時に用いられるフラッシュバット溶接性の劣
化、および冷延ベース、熱延ベースともにコスト上昇を
招き、その割には効果があがらない。したがってＡｌの
含有量は、０．４〜２．５％とする。好ましくは０．６
〜２．０％である。Under the condition that the content of Si is 1.0% or less, unless the content of Al is 0.4% or more, it is impossible to suppress an increase in the ability to produce cementite. However, 2.5
%, The cold-rolled base deteriorates the flash butt weldability used when passing the pickling line, and raises the cost of both the cold-rolled base and the hot-rolled base. I don't go up. Therefore, the content of Al is set to 0.4 to 2.5%. Preferably 0.6
~ 2.0%.

【００５９】Ｎ：Ｎを多量に含有させるとＡｌＮの生成
量に大きく影響をおよぼす。また、本発明の主旨である
ＮをＴｉＮとして固定するために必要なＴｉの量が増大
するためその上限を０．０１％とする。好ましくは０．
００５％以下である。N: When N is contained in a large amount, it greatly affects the amount of AlN produced. Further, since the amount of Ti necessary to fix N as TiN, which is the gist of the present invention, increases, the upper limit is made 0.01%. Preferably 0.
005% or less.

【００６０】以上が本発明の方法における化学組成の主
たる限定理由であるが、強度確保、細粒化、耐食性向上
を目的として特性を劣化させない範囲でＮｉ、Ｃｒ、Ｍ
ｏ、Ｃｕ、Ｎｂ、Ｖ、Ｚｒ、Ｂの１種または２種以上を
含有させてもよい。The main reasons for limiting the chemical composition in the method of the present invention are as described above. Ni, Cr, M may be used within the range not deteriorating the properties for the purpose of securing the strength, reducing the grain size, and improving the corrosion resistance.
One, two or more of o, Cu, Nb, V, Zr, and B may be contained.

【００６１】Ｎｉ：ＮｉもＭｎと同様オーステナイトを
安定化させる元素である。しかし、多量に含有させると
コスト上昇ならびに過度の強度上昇を招くためにその上
限を０．１％とする。Ni: Ni is an element that stabilizes austenite as well as Mn. However, if it is contained in a large amount, the cost and excessive strength increase are caused, so the upper limit is made 0.1%.

【００６２】Ｃｒ：Ｃｒは、Ｍｎと同様にオーステナイ
トを安定にする作用を有する元素である。１．０％を超
えて含有させるとコスト上昇を招くほか、焼き入れ性を
不必要に高め、過度の強度上昇を招く。したがってＣｒ
の含有量の上限を１．０％とする。 Ｍｏ：ＭｏもＳｉ、Ａｌと同様炭化物の生成を抑制する
働きがあることからオーステナイト残留効果をもたらす
元素であり、炭化物の生成の抑制ならびにマルテンサイ
ト変態温度の低温化を図り、残留オーステナイトを安定
させる。しかし、０．６％を超えてに多量に含有させる
とコスト上昇を招くほか、焼き入れ性を不必要に高め、
過度の強度上昇を生じる。したがって、その上限を０．
６％とする。Cr: Cr is an element having a function of stabilizing austenite, like Mn. If the content exceeds 1.0%, the cost is increased, the hardenability is unnecessarily increased, and the strength is excessively increased. Therefore Cr
The upper limit of the content is 1.0%. Mo: Mo, like Si and Al, also has the function of suppressing the formation of carbides, and therefore is an element that brings about the austenite residual effect. It suppresses the formation of carbides, lowers the martensitic transformation temperature, and stabilizes retained austenite. . However, if it is contained in a large amount exceeding 0.6%, the cost is increased, and the hardenability is unnecessarily increased.
This causes excessive strength rise. Therefore, the upper limit is set to 0.
6%.

【００６３】Ｃｕ：Ｃｕは、片面めっきを想定した場合
の裸耐食性、あるいは溶接部等めっき脱落部での耐食性
を向上させる目的で含有させてもよい。しかし、１．０
％を超えて含有させるとスラブでのＣｕチェッキングの
ために熱間加工性の劣化を招き表面疵の原因となる。こ
れを抑制するためにＮｉとの複合添加が必須となってく
る。従って、その上限を１．０％とする。Cu: Cu may be contained for the purpose of improving bare corrosion resistance in the case where single-sided plating is assumed, or corrosion resistance in a portion where plating has fallen off such as a welded portion. However, 1.0
%, The hot workability is deteriorated due to Cu checking in the slab, which causes surface flaws. In order to suppress this, composite addition with Ni becomes essential. Therefore, the upper limit is set to 1.0%.

【００６４】Ｎｂ：Ｎｂは適度にオーステナイトのパー
ライト変態を抑制し、残留オーステナイトを得るための
冷却速度制約条件を緩和する。しかし、０．０５％を超
えて含有させても効果は飽和し、経済的にも不利とな
る。したがって上限を０．０５％とする。Nb: Nb moderately suppresses pearlite transformation of austenite and relaxes cooling rate constraints for obtaining retained austenite. However, if the content exceeds 0.05%, the effect is saturated, and it is economically disadvantageous. Therefore, the upper limit is set to 0.05%.

【００６５】Ｖ：Ｖは残留オーステナイトを安定化させ
る効果がある。しかし、０．０８％を超えて多量に含有
させるとコスト上昇ならびに焼き入れ性を高めるため過
度の強度上昇を生じる。したがって、その上限を０．０
８％とする。V: V has the effect of stabilizing retained austenite. However, if it is contained in a large amount exceeding 0.08%, the cost and the hardenability are increased, so that the strength is excessively increased. Therefore, the upper limit is 0.0
8%.

【００６６】Ｚｒ：Ｚｒは、介在物の形状を調整し冷間
加工性を改善する作用を有している。しかし、０．０５
％を超えて含有させるとかえって加工性の劣化を招くた
め、上限を０．０５％とする。Zr: Zr has the effect of adjusting the shape of inclusions and improving cold workability. However, 0.05
%, The upper limit is set to 0.05%, since the workability is degraded when the content exceeds 0.1%.

【００６７】Ｂ：Ｂは、粒界を強化し耐２次加工脆性を
上昇させる。しかし、０．００３％超えて含有させても
効果は飽和する。したがって、その上限を０．００３％
とする。B: B strengthens grain boundaries and increases secondary work brittleness resistance. However, even if the content exceeds 0.003%, the effect is saturated. Therefore, the upper limit is 0.003%
And

【００６８】次に、本発明の製造工程および製造条件に
ついて説明する。本発明の製造方法による高張力高延性
合金化溶融亜鉛めっき鋼板を製造するにあたっては、冷
延ベースのめっき鋼板でも熱延ベースでも、常法に従い
本発明の化学組成の鋼材を転炉などで溶製し、連続鋳造
でスラブとした後、好ましくは下記条件での熱間圧延を
行う。Next, the manufacturing process and manufacturing conditions of the present invention will be described. In producing a high-tensile-high-ductility alloyed hot-dip galvanized steel sheet by the production method of the present invention, a steel material having the chemical composition of the present invention is melted in a converter or the like according to a conventional method, whether it is a cold-rolled base coated steel sheet or a hot-rolled base steel sheet. After the slab is manufactured and slab is formed by continuous casting, hot rolling is preferably performed under the following conditions.

【００６９】熱間圧延条件：本発明の鋼板は、残留オー
ステナイトを確保するための、Ａｌを多量に含有し、Ｓ
ｉを最大１％含有することもあるので熱間圧延時の変形
抵抗が高い。したがって、冷延ベースのめっき鋼板素材
としては、熱間変形抵抗を低下させるために加熱温度は
１２２０℃以上とし、熱間圧延の仕上げ温度９２０℃以
上での高温仕上げ圧延を行うのが望ましい。熱延ベース
の場合も同様の理由で高温仕上げが望ましいが、通常、
熱延ベースで製品とする場合は熱延板厚は冷延用母材を
熱間圧延するときより薄いため、熱間圧延仕上げ温度を
８７０℃以上を許容範囲とするのが望ましい。Hot rolling conditions: The steel sheet of the present invention contains a large amount of Al to secure retained austenite,
Since i may contain up to 1%, deformation resistance during hot rolling is high. Therefore, as for the cold-rolled base plated steel sheet material, it is desirable to set the heating temperature to 1220 ° C. or higher and perform high-temperature finish rolling at a hot rolling finish temperature of 920 ° C. or higher in order to reduce hot deformation resistance. For hot rolled bases, high temperature finishing is desirable for the same reason, but usually,
When a hot-rolled product is used, the thickness of the hot-rolled sheet is thinner than when hot-rolling the base material for cold rolling, so that the hot-rolling finishing temperature is desirably 870 ° C. or higher.

【００７０】冷延ベース、熱延ベースとも、熱間圧延仕
上げ温度の上限は特に定めないが、加熱炉のエネルギー
コスト等を考慮して、９７０℃以下とするのが好まし
い。Although the upper limit of the hot rolling finish temperature is not particularly defined for both the cold-rolled base and the hot-rolled base, it is preferably 970 ° C. or lower in consideration of the energy cost of the heating furnace.

【００７１】冷延ベースの場合、上記にて得られた熱間
圧延鋼板を常法に従い、酸洗、冷間圧延を行う。冷間圧
延時の通板性を確保するため冷間圧延率（以下、冷圧率
という）は４５％以上とするのが望ましい。In the case of a cold-rolled base, the hot-rolled steel sheet obtained above is subjected to pickling and cold rolling according to a conventional method. It is desirable that the cold rolling ratio (hereinafter, referred to as a cold pressure ratio) be 45% or more in order to ensure the sheet passing property during the cold rolling.

【００７２】熱延ベースの場合、前述のように熱延のま
まではめっき濡れ性に劣るため鋼板表面に加工ひずみを
与える。加工ひずみに付与方法としては、ブラシ研削
法、ショットブラスト法、軽圧下法、レベラー法等があ
げられる。In the case of a hot-rolled base, as described above, hot-rolled steel is inferior in plating wettability, so that a work strain is applied to the steel sheet surface. Examples of a method for imparting the processing strain include a brush grinding method, a shot blast method, a light reduction method, and a leveler method.

【００７３】ブラシ研削は熱延鋼板を酸洗した後に行う
が、表面ひずみ付与効果とともに、酸洗によっても除去
しきれない表面のＳｉ系酸化物を除去する効果がある。
ブラシ研削は常法の研削ブラシロールを用いるのが好適
である。ひずみ蓄積を確実にするため、ブラシ研削量は
２ｇ／ｍ² 以上とするのが望ましい。一方１０ｇ／ｍ²
を超えて研削しても効果は飽和する。Brush grinding is performed after pickling a hot-rolled steel sheet, and has an effect of removing surface Si-based oxides that cannot be completely removed by pickling, in addition to an effect of imparting surface strain.
For the brush grinding, it is preferable to use an ordinary grinding brush roll. In order to ensure the accumulation of strain, it is desirable that the brush grinding amount is 2 g / m ² or more. On the other hand, 10 g / m ²
The effect is saturated even if grinding exceeds.

【００７４】ショットブラスト法も熱延鋼板を酸洗した
後に行い、表面ひずみ付与効果とともにＳｉ系酸化物除
去効果がある。処理の程度は、目視で均一に処理されて
いればよい。The shot blast method is also performed after pickling the hot-rolled steel sheet, and has an effect of imparting surface strain and an effect of removing Si-based oxides. The degree of the treatment may be such that the treatment can be carried out uniformly visually.

【００７５】軽圧下法はスキンパスミル等により圧下を
行う方法であるが、この処理は酸洗前、酸洗後のいずれ
でもよい。圧下率は３％以上とするのが望ましい。レベ
ラー法も酸洗前、酸洗後のいずれで行ってもよい。表面
ひずみ率として３％以上を与えるのが望ましい。The light rolling method is a method in which rolling is performed by a skin pass mill or the like. This treatment may be performed before or after pickling. The rolling reduction is desirably 3% or more. The leveler method may be performed before or after pickling. It is desirable to give a surface strain rate of 3% or more.

【００７６】本発明の方法の実施にあたっては、冷間圧
延後の冷延鋼板、または脱スケール処理と加工ひずみ付
与処理した熱延鋼板を連続溶融亜鉛めっきラインを用い
て前酸化、焼鈍、冷却、溶融亜鉛めっきを行い、合金化
溶融亜鉛めっき鋼板の場合はさらに合金化処理を行うの
が好適である。本発明の方法において亜鉛浴への浸漬処
理自体に制限はなく、慣用のものをそのまま使えばよ
い。In carrying out the method of the present invention, a cold-rolled steel sheet after cold rolling or a hot-rolled steel sheet subjected to descaling treatment and processing strain imparting treatment is subjected to pre-oxidation, annealing, cooling, It is preferable to perform hot-dip galvanizing and, in the case of an alloyed hot-dip galvanized steel sheet, to further perform alloying treatment. In the method of the present invention, the immersion treatment in the zinc bath itself is not limited, and a conventional one may be used as it is.

【００７７】残留オーステナイト量の確保と溶融亜鉛め
っき処理、合金化処理を両立させるために、(a) 前酸化
条件、(b) 焼鈍条件、(c) 冷却保持条件、(d) 合金化処
理条件（合金化溶融亜鉛めっきの場合）を次のように制
御する。In order to ensure both the amount of retained austenite and the hot dip galvanizing treatment and alloying treatment, (a) pre-oxidation conditions, (b) annealing conditions, (c) cooling holding conditions, and (d) alloying treatment conditions (In the case of galvannealing) is controlled as follows.

【００７８】(a) 前酸化条件：通常は連続溶融亜鉛めっ
きラインの加熱帯で行う。別の処理ラインで前酸化を実
施しても構わないが、設備的にも省エネルギー的にも実
用的ではない。前酸化の雰囲気は、例えば９０〜９３％
Ｎ₂ ＋残部Ｈ₂ の無酸化雰囲気中で、若干の侵入酸素ま
たは鋼板に付着した酸素で鋼板が酸化される程度の雰囲
気とするのがよい。(A) Pre-oxidation conditions: Usually, pre-oxidation is performed in a heating zone of a continuous galvanizing line. Although pre-oxidation may be performed in another processing line, it is not practical in terms of equipment and energy saving. Pre-oxidation atmosphere is, for example, 90 to 93%.
It is preferable to use an atmosphere in which the steel sheet is oxidized by a slight amount of oxygen or oxygen adhering to the steel sheet in a non-oxidizing atmosphere of N ₂ + remainder H ₂ .

【００７９】Ｓｉ含有鋼は、表層にＳｉ酸化物を形成
し、溶融亜鉛めっき浴に浸入するとき、および合金化処
理のときに、合金相の形成に必要な還元鉄量が少なくな
り、めっきの濡れ性を劣化させる。そこで、本発明では
めっきの濡れ性を確保するためにめっき処理前での還元
Ｆｅ量を確保するため、前酸化をして酸化鉄を形成して
おくのである。そのときの酸化鉄付着量は、通常の条件
下では、約２〜４ｇ／ｍ² であれば十分である。The Si-containing steel forms a Si oxide on the surface layer and reduces the amount of reduced iron necessary for the formation of an alloy phase during infiltration into a hot-dip galvanizing bath and during alloying treatment. Deteriorates wettability. Therefore, in the present invention, in order to secure the amount of reduced Fe before the plating treatment in order to secure the wettability of the plating, pre-oxidation is performed to form iron oxide. Under normal conditions, the amount of iron oxide attached at that time is sufficient if it is about ² to 4 g / m ² .

【００８０】前酸化温度が５５０℃未満であれば生成さ
れる酸化鉄の必要量が確保できず、また、７５０℃を超
える温度では酸化鉄量が多くなりすぎ、かえってめっき
の密着性を劣化させる。したがって、前酸化温度を５５
０℃〜７５０℃とする。If the pre-oxidation temperature is less than 550 ° C., the required amount of iron oxide to be produced cannot be secured, and if the temperature exceeds 750 ° C., the amount of iron oxide becomes too large, which deteriorates the adhesion of the plating. . Therefore, a pre-oxidation temperature of 55
0 ° C. to 750 ° C.

【００８１】(b) 焼鈍条件：焼鈍処理ではフェライト＋
オーステナイト（２相域）に加熱しオーステナイト相中
へのＣ濃化を図る必要がある。したがって２相域温度ま
で加熱する。焼鈍温度が７６０℃未満（Ａｃ₁変態点以
上であるが）ではオーステナイト分率が少なく、生成す
る残留オーステナイト量も少なくなるために特性が好ま
しくない。一方、焼鈍温度が９００℃を超えると、エネ
ルギーコストの増加をまねくという問題がある。従っ
て、焼鈍温度は７６０℃〜９００℃とする。(B) Annealing conditions: Ferrite +
It is necessary to heat to austenite (two-phase region) to concentrate C in the austenite phase. Therefore, it is heated to the two-phase region temperature. If the annealing temperature is lower than 760 ° C. (although it is higher than the Ac ₁ transformation point), the austenite fraction is low, and the amount of generated residual austenite is also low, so that the characteristics are not preferable. On the other hand, when the annealing temperature exceeds 900 ° C., there is a problem that energy cost is increased. Therefore, the annealing temperature is 760 ° C to 900 ° C.

【００８２】焼鈍過程では熱延段階で生成した炭化物を
再固溶させ、オーステナイト相中へのＣ濃化を図るた
め、焼鈍時間も重要である。焼鈍時間が５秒未満ではこ
の効果が不十分で、残留オーステナイトの安定性も悪く
特性も好ましくないため、焼鈍時間は５秒以上とする。
また、焼鈍時間が長時間化すると、生産性の劣化を招く
ため、好ましくは１２０秒以下とするのがよい。In the annealing process, the annealing time is also important in order to re-dissolve the carbide generated in the hot rolling step and to enrich C in the austenite phase. If the annealing time is less than 5 seconds, this effect is insufficient, the stability of the retained austenite is poor, and the characteristics are not preferable. Therefore, the annealing time is 5 seconds or more.
Further, if the annealing time is prolonged, the productivity is deteriorated. Therefore, the annealing time is preferably set to 120 seconds or less.

【００８３】(c) 冷却保持条件：本発明の製造方法の対
象鋼種はＡｌを多量に含んでおり、セメンタイトの生成
を抑制しているが、焼鈍後の冷却速度が３℃／ｓ未満で
はセメンタイトを生成してしまう。したがって、冷却速
度は３℃／ｓ以上とする。冷却速度の上限は特に制限す
る必要はないが、一般的には生産設備の制約上２０℃／
ｓ以下である。(C) Cooling holding condition: The steel type to be subjected to the production method of the present invention contains a large amount of Al and suppresses the formation of cementite. However, when the cooling rate after annealing is less than 3 ° C./s, cementite is not used. Will be generated. Therefore, the cooling rate is set to 3 ° C./s or more. Although the upper limit of the cooling rate need not be particularly limited, it is generally 20 ° C. /
s or less.

【００８４】また、冷却後の保持において、ベイナイト
変態を進行させオーステナイト中へのＣ濃化を図る必要
があるため、３５０℃〜６００℃のベイナイト変態温度
域で２０秒以上保持する必要がある。しかし、その後亜
鉛浴に浸入させるため、４２０℃未満では、亜鉛が凝固
して表面性状が悪化する。従って、保持温度は４２０℃
〜６００℃の範囲とする。保持時間が２０秒未満ではベ
イナイト変態によるオーステナイト相へのＣ濃化が不十
分となる。保持時間の上限は特に規定せず、生産性を低
下させなければ任意である。Further, in holding after cooling, it is necessary to promote bainite transformation to promote C enrichment in austenite. Therefore, it is necessary to maintain the bainite transformation temperature range of 350 ° C. to 600 ° C. for 20 seconds or more. However, since it is then immersed in a zinc bath, if the temperature is lower than 420 ° C., zinc solidifies and the surface properties deteriorate. Therefore, the holding temperature is 420 ° C
~ 600 ° C. If the holding time is less than 20 seconds, C enrichment in the austenite phase due to bainite transformation will be insufficient. The upper limit of the holding time is not particularly defined, and is arbitrary as long as the productivity is not reduced.

【００８５】(d) 合金化処理条件：合金化溶融亜鉛めっ
きの場合、めっき後に合金化処理を行う。残留オーステ
ナイトは、６００℃を超える温度ではセメンタイトに変
態する。残留オーステナイトが消失すると所望の高延性
の特性を得られない。従って、合金化処理温度は６００
℃以下とする。合金化処理温度の下限は特に規定しない
が、一般には板温度で４８０℃以上である。(D) Alloying treatment conditions: In the case of galvannealing, alloying treatment is performed after plating. Retained austenite transforms to cementite at temperatures above 600 ° C. If the retained austenite disappears, the desired high ductility characteristics cannot be obtained. Therefore, the alloying treatment temperature is 600
It should be below ° C. Although the lower limit of the alloying treatment temperature is not particularly defined, it is generally 480 ° C. or higher at the plate temperature.

【００８６】[0086]

【実施例】（実施例１）冷延ベースの合金化溶融亜鉛め
っき鋼板について調査した。表１に示すＡ〜Ｏの鋼種に
ついて前記の予備試験とおなじ熱間圧延条件、冷間圧延
条件で冷延鋼板を製造し、連続溶融亜鉛めっきライン
（板厚１．６ｍｍ、両面６０ｇ／ｍ² 目付）に通板し、
合金化溶融亜鉛めっき鋼板を製造し、各種試験を行っ
た。試験結果を表２に示す。EXAMPLES (Example 1) A cold-rolled alloyed hot-dip galvanized steel sheet was investigated. For the steel types A to O shown in Table 1, cold-rolled steel sheets were manufactured under the same hot rolling conditions and cold rolling conditions as those in the preliminary test, and a continuous hot-dip galvanizing line (sheet thickness 1.6 mm, both sides 60 g / m ²⁾ Basis weight),
An alloyed hot-dip galvanized steel sheet was manufactured and various tests were performed. Table 2 shows the test results.

【００８７】なお、溶融亜鉛めっき鋼板は合金化処理を
行わないため、めっき付着性、残留オーステナイト、各
種特性は合金化処理したものに劣ることはないものとみ
なし、試験は行わなかった。Since the hot dip galvanized steel sheet was not subjected to alloying treatment, it was considered that the plating adhesion, retained austenite, and various properties were not inferior to those subjected to alloying treatment, and no test was performed.

【００８８】表２に記載の引張試験、残留オーステナイ
ト量（残留γ量）の調査は前記予備試験と同様であり、
穴広げ性は打ち抜きクリアランスを１２％として、直径
１０ｍｍの打ち抜き穴を形成し、６０゜円錐パンチで成
形した際の穴広げ率で評価した。The tensile test and the investigation of the amount of retained austenite (the amount of residual γ) shown in Table 2 are the same as those of the preliminary test.
The hole expanding property was evaluated by forming a punched hole having a diameter of 10 mm with a punching clearance of 12% and forming the hole with a 60 ° conical punch.

【００８９】めっきの密着性は以下の方法で調査したパ
ウダリング性で評価した。すなわち、めっき鋼板を絞り
比１．８で円筒成形後テープ剥離を行い、テープに付着
しためっきの付着量を重量法にて測定した。めっきの濡
れ性ならびに合金化処理性は、目視により判定した。こ
れらの結果を表２に示す。The adhesion of the plating was evaluated based on the powdering property examined by the following method. That is, the tape was peeled off after forming the coated steel sheet into a cylindrical shape at a drawing ratio of 1.8, and the amount of plating adhered to the tape was measured by a gravimetric method. The wettability of the plating and the alloying property were visually determined. Table 2 shows the results.

【００９０】[0090]

【表２】 [Table 2]

【００９１】表２に示すように、試料Ｎｏ．１は、成分
が本発明範囲内であるが前酸化の温度が低いために濡れ
性が不芳であった。また、Ｎｏ．４は合金化処理温度が
高い、Ｎｏ．５は焼鈍温度が低い、Ｎｏ．６は低温保持
温度が高い、とそれぞれ本発明の範囲外の条件になって
いるため引張特性も不芳で残留オーステナイト量も少な
かった。As shown in Table 2, Sample No. In No. 1, although the components were within the range of the present invention, the wettability was poor due to the low pre-oxidation temperature. In addition, No. No. 4 has a high alloying treatment temperature. No. 5 has a low annealing temperature. Sample No. 6 had a high low-temperature holding temperature, each of which was out of the range of the present invention, and thus had poor tensile properties and a small amount of retained austenite.

【００９２】Ｎｏ．３は、前酸化温度が高すぎるために
引張特性は良好であるが、パウダリング性が不芳であっ
た。Ｎｏ．２およびＮｏ．７〜Ｎｏ．１２は、鋼の成分
および焼鈍ないしめっきの製造条件が本発明範囲にある
ため、めっき性濡れ性、合金化処理性、機械的特性とも
良好な性能を示している。試験Ｎｏ．２、７および８は
穴広げ性についての試験を行い、良好な結果が得られ
た。No. Sample No. 3 had good tensile properties because the pre-oxidation temperature was too high, but had poor powdering properties. No. 2 and No. 7-No. No. 12 shows good performance in all of the plating wettability, alloying processability, and mechanical properties because the composition of the steel and the manufacturing conditions for annealing or plating are within the scope of the present invention. Test No. 2, 7 and 8 were tested for hole-expandability, and good results were obtained.

【００９３】Ｎｏ．１３〜Ｎｏ．１７は、それぞれ成分
範囲が本発明の規定外のため未処理（合金化処理が未処
理のまま）、はじき、疵多発および残留オーステナイト
量が５体積％以下となった。No. 13-No. Sample No. 17 was untreated (the alloying treatment was left untreated) because of the component range outside the range of the present invention, and repelled, flawed and retained austenite amount was 5% by volume or less.

【００９４】またＮｏ．１８は、Ｓ量が高いためにＮ
ｏ．２、Ｎｏ．７、Ｎｏ．８に比べて穴広げ性が不芳な
結果となっている。Ｎｏ．１９はＴｉ量が（４８／１
４）Ｎを下回っており、スラブ表面割れが発生してい
た。Ｎｏ．２０はＴｉ量が（４８／１４）Ｎ＋（４８／
３２）Ｓ＋０．０１０の値を上回っており、残留オース
テナイト生成量が減り延性が低下していた。No. 18 is N because of the high S content.
o. 2, No. 7, no. As a result, the hole-expanding property was worse than that of No. 8. No. 19 has a Ti content of (48/1
4) It was lower than N, and slab surface cracks occurred. No. 20 has a Ti content of (48/14) N + (48 /
32) The value exceeded S + 0.010, indicating that the amount of retained austenite was reduced and the ductility was reduced.

【００９５】（実施例２）次に、熱延ベースについて調
査した。表１に示すＡ〜Ｍの鋼種について、前記の予備
試験と同じ熱間圧延条件で熱延鋼板を製造し、酸洗、ブ
ラシ研削処理後、連続溶融亜鉛めっきライン（板厚２．
０ｍｍ、両面６０ｇ／ｍ² 目付）に通板し、各種特性に
ついて調査した。結果を表３に示す。(Example 2) Next, a hot rolling base was examined. For the steel types A to M shown in Table 1, hot-rolled steel sheets were manufactured under the same hot rolling conditions as in the above preliminary test, and after pickling and brush grinding, a continuous hot-dip galvanizing line (plate thickness 2.
(0 mm, 60 g / m ^{2 on} both sides), and various characteristics were investigated. Table 3 shows the results.

【００９６】同表に記載の引張試験、残留オーステナイ
ト量、穴広げ性試験条件、めっきの密着性、めっきの濡
れ性ならびに合金化処理性の測定方法、評価方法は表２
の冷延ベースの場合と同じである。結果を表３にまとめ
て示す。The tensile test, residual austenite amount, hole expanding property test conditions, plating adhesion, plating wettability, and alloying property measurement methods and evaluation methods described in the table are shown in Table 2.
This is the same as the case of the cold rolled base. The results are summarized in Table 3.

【００９７】[0097]

【表３】 [Table 3]

【００９８】表３に示すように、試料Ｎｏ．１は、成分
が本発明範囲内であるが前酸化の温度が低いために濡れ
性が不芳であった。また、Ｎｏ．４は合金化処理温度が
高い、Ｎｏ．５は焼鈍温度が低い、Ｎｏ．６は低温保持
温度が高い、とそれぞれ本発明の範囲外の条件になって
いるため引張特性も不芳で残留オーステナイト量も少な
かった。As shown in Table 3, Sample No. In No. 1, although the components were within the range of the present invention, the wettability was poor due to the low pre-oxidation temperature. In addition, No. No. 4 has a high alloying treatment temperature. No. 5 has a low annealing temperature. Sample No. 6 had a high low-temperature holding temperature, each of which was out of the range of the present invention, and thus had poor tensile properties and a small amount of retained austenite.

【００９９】Ｎｏ．３は、前酸化温度が高すぎるために
引張特性は良好であるが、パウダリング性が不芳であっ
た。Ｎｏ．２およびＮｏ．７〜Ｎｏ．１２は、鋼の成分
および焼鈍ないしめっきの製造条件が本発明範囲にある
ため、めっき性濡れ性、合金化処理性、機械的特性とも
良好な性能を示している。試験Ｎｏ．２、７および８は
穴広げ性についての試験を行い、Ｎｏ．２、７、８良好
な結果が得られた。No. Sample No. 3 had good tensile properties because the pre-oxidation temperature was too high, but had poor powdering properties. No. 2 and No. 7-No. No. 12 shows good performance in all of the plating wettability, alloying processability, and mechanical properties because the composition of the steel and the manufacturing conditions for annealing or plating are within the scope of the present invention. Test No. Nos. 2, 7 and 8 were tested for hole spreading properties. 2, 7, 8 Good results were obtained.

【０１００】Ｎｏ．１３〜Ｎｏ．１７は、それぞれ成分
範囲が本発明外のため合金化未処理、はじき、疵多発お
よび残留オーステナイト量が５体積％以下となってい
る。またＮｏ．１８は、Ｓ量が高いためにＮｏ．２、Ｎ
ｏ．７、Ｎｏ．８に比べて穴広げ性が不芳な結果となっ
ている。No. 13-No. Sample No. 17 has an alloying unprocessed, repelling, frequent flaws, and a residual austenite content of 5% by volume or less because the component ranges are outside the present invention. No. No. 18 is No. 18 because of a high S content. 2, N
o. 7, no. As a result, the hole-expanding property was worse than that of No. 8.

【０１０１】[0101]

【発明の効果】本発明の製造方法によれば、冷延鋼板ま
たは熱延鋼板のいずれを母材としても、成形性とめっき
性に優れた高張力高延性合金化溶融亜鉛めっき鋼板を安
定的に製造することができる。According to the production method of the present invention, a hot-rolled steel sheet or a hot-rolled steel sheet can be used as a base material to stably produce a high-tensile, high-ductility alloyed hot-dip galvanized steel sheet having excellent formability and plating properties. Can be manufactured.

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

【図１】冷延鋼板の場合の前酸化温度とめっきの濡れ性
指標の関係を示すグラフである。FIG. 1 is a graph showing a relationship between a pre-oxidation temperature and a wettability index of plating in the case of a cold-rolled steel sheet.

【図２】冷延鋼板の場合の冷却速度と引張特性、残留オ
ーステナイト量の関係を示すグラフである。FIG. 2 is a graph showing a relationship between a cooling rate, a tensile property, and an amount of retained austenite in the case of a cold-rolled steel sheet.

【図３】冷延鋼板の場合の低温保持時間と引張特性、残
留オーステナイト量の関係を示すグラフである。FIG. 3 is a graph showing a relationship between a low-temperature holding time, a tensile characteristic, and an amount of retained austenite in the case of a cold-rolled steel sheet.

【図４】冷延鋼板の場合の合金化処理温度と引張特性、
残留オーステナイト量の関係を示すグラフである。FIG. 4 shows the alloying treatment temperature and tensile properties of a cold rolled steel sheet,
It is a graph which shows the relationship of the amount of retained austenite.

【図５】熱延鋼板の場合の前酸化温度とめっきの濡れ性
指標の関係を示すグラフである。FIG. 5 is a graph showing a relationship between a pre-oxidation temperature and a plating wettability index in the case of a hot-rolled steel sheet.

【図６】熱延鋼板の場合の冷却速度と引張特性、残留オ
ーステナイト量の関係を示すグラフである。FIG. 6 is a graph showing a relationship between a cooling rate, a tensile property, and an amount of retained austenite in the case of a hot-rolled steel sheet.

【図７】熱延鋼板の場合の低温保持時間と引張特性、残
留オーステナイト量の関係を示すグラフである。FIG. 7 is a graph showing a relationship between a low-temperature holding time, a tensile characteristic, and an amount of retained austenite in the case of a hot-rolled steel sheet.

【図８】熱延鋼板の場合の合金化処理温度と引張特性、
残留オーステナイト量の関係を示すグラフである。FIG. 8 shows alloying treatment temperature and tensile properties in the case of a hot-rolled steel sheet,
It is a graph which shows the relationship of the amount of retained austenite.

Claims (6)

【特許請求の範囲】[Claims] 【請求項１】 化学組成が重量％で、Ｃ：０．０６〜
０．２５％、Ｓｉ：１．０％以下、Ｍｎ：０．５〜３．
０％、Ｐ：０．０３％以下、Ｓ：０．０３０％以下、Ａ
ｌ：０．４〜２．５％、Ｔｉ：０．００３〜０．０８０
％、Ｎ：０．０１０％以下で、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／１４）Ｎ＋（４８／３２）Ｓ＋０．０１
０の条件を満たし、残部がＦｅおよび不可避的不純物か
らなる鋼組成を有する冷延鋼板に、板温度５５０〜７５
０℃で前酸化を行い、７６０〜９００℃の２相域温度で
５秒以上保持して焼鈍を行い、次いで３℃／ｓ以上の冷
却速度で４２０〜６００℃の温度域まで冷却し、この温
度域で２０秒以上保持する冷却保持を行い、溶融亜鉛浴
に浸入させてめっきを施して、溶融亜鉛めっき鋼板を製
造することを特徴とする高張力高延性亜鉛めっき鋼板の
製造方法。1. The chemical composition in weight%, C: 0.06 to
0.25%, Si: 1.0% or less, Mn: 0.5-3.
0%, P: 0.03% or less, S: 0.030% or less, A
l: 0.4 to 2.5%, Ti: 0.003 to 0.080
%, N: 0.010% or less, and (48/14) N ≦
Ti ≦ (48/14) N + (48/32) S + 0.01
0, and the balance of the cold-rolled steel sheet having a steel composition consisting of Fe and unavoidable impurities has a sheet temperature of 550-75.
Pre-oxidation is performed at 0 ° C., annealing is performed at a temperature in a two-phase region of 760 to 900 ° C. for 5 seconds or more, and then cooled to a temperature range of 420 to 600 ° C. at a cooling rate of 3 ° C./s or more. A method for producing a high-tensile, high-ductility galvanized steel sheet, which comprises performing cooling and holding at a temperature range of 20 seconds or more, infiltrating into a hot-dip zinc bath, and performing plating to produce a hot-dip galvanized steel sheet. 【請求項２】 化学組成が重量％で、Ｃ：０．０６〜
０．２５％、Ｓｉ：１．０％以下、Ｍｎ：０．５〜３．
０％、Ｐ：０．０３％以下、Ｓ：０．０３０％以下、Ａ
ｌ：０．４〜２．５％、Ｔｉ：０．００３〜０．０８０
％、Ｎ：０．０１０％以下で、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／１４）Ｎ＋（４８／３２）Ｓ＋０．０１
０の条件を満たし、残部がＦｅおよび不可避的不純物か
らなる鋼組成を有する冷延鋼板に、板温度５５０〜７５
０℃で前酸化を行い、７６０〜９００℃の２相域温度で
５秒以上保持して焼鈍を行い、次いで３℃／ｓ以上の冷
却速度で４２０〜６００℃の温度域まで冷却し、この温
度域で２０秒以上保持する冷却保持を行い、溶融亜鉛浴
に浸入させてめっきを施し、さらに６００℃以下で合金
化処理を行って、合金化溶融亜鉛めっき鋼板を製造する
ことを特徴とする高張力高延性亜鉛めっき鋼板の製造方
法。2. The chemical composition in weight%, C: 0.06 to
0.25%, Si: 1.0% or less, Mn: 0.5-3.
0%, P: 0.03% or less, S: 0.030% or less, A
l: 0.4 to 2.5%, Ti: 0.003 to 0.080
%, N: 0.010% or less, and (48/14) N ≦
Ti ≦ (48/14) N + (48/32) S + 0.01
0, and the balance of the steel sheet has a steel composition consisting of Fe and unavoidable impurities.
Pre-oxidation is performed at 0 ° C., annealing is performed at a temperature in a two-phase region of 760 to 900 ° C. for 5 seconds or more, and then cooled to a temperature range of 420 to 600 ° C. at a cooling rate of 3 ° C./s or more. It is characterized by producing a galvannealed steel sheet by performing cooling and holding for at least 20 seconds in a temperature range, immersing it in a molten zinc bath, plating it, and performing alloying treatment at 600 ° C or less. A method for producing high-tensile, high-ductility galvanized steel sheets. 【請求項３】 請求項１または２に記載の冷延鋼板が、
さらに、Ｎｉ：０．１％以下、Ｃｒ：１．０％以下、Ｍ
ｏ：０．６％以下、Ｃｕ：１．０％以下、Ｎｂ：０．０
５％以下、Ｖ：０．０８％以下、Ｚｒ：０．０５％以下
およびＢ：０．００３％以下からなる群から選んだ１種
または２種以上を含有することを特徴とする高張力高延
性亜鉛めっき鋼板の製造方法。3. The cold-rolled steel sheet according to claim 1 or 2,
Furthermore, Ni: 0.1% or less, Cr: 1.0% or less, M
o: 0.6% or less, Cu: 1.0% or less, Nb: 0.0
High tensile strength characterized by containing one or more selected from the group consisting of 5% or less, V: 0.08% or less, Zr: 0.05% or less, and B: 0.003% or less. Manufacturing method of ductile galvanized steel sheet. 【請求項４】 化学組成が重量％で、Ｃ：０．０６〜
０．２５％、Ｓｉ：１．０％以下、Ｍｎ：０．５〜３．
０％、Ｐ：０．０３％以下、Ｓ：０．００５％以下、Ａ
ｌ：０．４〜２．５％、Ｔｉ：０．００３〜０．０８０
％、Ｎ：０．０１０％以下で、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／１４）Ｎ＋（４８／３２）Ｓ＋０．０１
０の条件を満たし、残部がＦｅおよび不可避的不純物か
らなる鋼組成を有する熱延鋼板に、スケール除去処理お
よび少なくともその表面へのひずみ付与加工を行い、板
温度５５０〜７５０℃で前酸化を行い、７６０〜９００
℃の２相域温度で５秒以上保持して焼鈍を行い、次いで
３℃／ｓ以上の冷却速度で４２０〜６００℃の温度域ま
で冷却し、この温度域で２０秒以上保持する冷却保持を
行い、溶融亜鉛浴に浸入させてめっきを施して、溶融亜
鉛めっき鋼板を製造することを特徴とする高張力高延性
亜鉛めっき鋼板の製造方法。4. The chemical composition in% by weight, C: 0.06 to
0.25%, Si: 1.0% or less, Mn: 0.5-3.
0%, P: 0.03% or less, S: 0.005% or less, A
l: 0.4 to 2.5%, Ti: 0.003 to 0.080
%, N: 0.010% or less, and (48/14) N ≦
Ti ≦ (48/14) N + (48/32) S + 0.01
0, and the balance is subjected to scale removal treatment and strain imparting at least to the surface of the hot-rolled steel sheet having a steel composition consisting of Fe and unavoidable impurities, and pre-oxidized at a plate temperature of 550 to 750 ° C. , 760-900
Annealing is performed by holding at a temperature in a two-phase region of 5 ° C. for 5 seconds or more, and then cooled to a temperature range of 420 to 600 ° C. at a cooling rate of 3 ° C./s or more, and held in this temperature range for 20 seconds or more. And producing a hot-dip galvanized steel sheet by subjecting the hot-dip galvanized steel sheet to plating. 【請求項５】 化学組成が重量％で、Ｃ：０．０６〜
０．２５％、Ｓｉ：１．０％以下、Ｍｎ：０．５〜３．
０％、Ｐ：０．０３％以下、Ｓ：０．００５％以下、Ａ
ｌ：０．４〜２．５％、Ｔｉ：０．００３〜０．０８０
％、Ｎ：０．０１０％以下で、かつ（４８／１４）Ｎ≦
Ｔｉ≦（４８／１４）Ｎ＋（４８／３２）Ｓ＋０．０１
０の条件を満たし、残部がＦｅおよび不可避的不純物か
らなる鋼組成を有する熱延鋼板に、スケール除去処理お
よび少なくともその表面へのひずみ付与加工を行い、板
温度５５０〜７５０℃で前酸化を行い、７６０〜９００
℃の２相域温度で５秒以上保持して焼鈍を行い、次いで
３℃／ｓ以上の冷却速度で４２０〜６００℃の温度域ま
で冷却し、この温度域で２０秒以上保持する冷却保持を
行い、溶融亜鉛浴に浸入させてめっきを施し、さらに６
００℃以下で合金化処理を行って、合金化溶融亜鉛めっ
き鋼板を製造することを特徴とする高張力高延性亜鉛め
っき鋼板の製造方法。5. The chemical composition in weight%, C: 0.06 to
0.25%, Si: 1.0% or less, Mn: 0.5-3.
0%, P: 0.03% or less, S: 0.005% or less, A
l: 0.4 to 2.5%, Ti: 0.003 to 0.080
%, N: 0.010% or less, and (48/14) N ≦
Ti ≦ (48/14) N + (48/32) S + 0.01
0, the balance of the hot-rolled steel sheet having a steel composition consisting of Fe and unavoidable impurities is subjected to scale removal treatment and strain imparting at least to its surface, and pre-oxidized at a plate temperature of 550 to 750 ° C. , 760-900
Annealing is carried out at a temperature in a two-phase region of at least 5 ° C. for at least 5 seconds, and then cooled to a temperature range of 420 to 600 ° C. at a cooling rate of at least 3 ° C./s. And then immersion in a molten zinc bath for plating,
A method for producing a galvanized steel sheet having a high tensile strength and a high ductility, wherein an alloying treatment is performed at a temperature of 00 ° C. or less to produce a galvannealed steel sheet. 【請求項６】 請求項４または５に記載の熱延鋼板が、
さらに、Ｎｉ：０．１％以下、Ｃｒ：１．０％以下、Ｍ
ｏ：０．６％以下、Ｃｕ：１．０％以下、Ｎｂ：０．０
５％以下、Ｖ：０．０８％以下、Ｚｒ：０．０５％以下
およびＢ：０．００３％以下からなる群から選んだ１種
または２種以上を含有することを特徴とする高張力高延
性亜鉛めっき鋼板の製造方法。6. The hot-rolled steel sheet according to claim 4 or 5,
Furthermore, Ni: 0.1% or less, Cr: 1.0% or less, M
o: 0.6% or less, Cu: 1.0% or less, Nb: 0.0
High tensile strength characterized by containing one or more selected from the group consisting of 5% or less, V: 0.08% or less, Zr: 0.05% or less, and B: 0.003% or less. Manufacturing method of ductile galvanized steel sheet.