JPH1096017A - Manufacture of not tempered and annealed high-strength steel excellent ion resistance to hop dip galvanizing crack - Google Patents
Manufacture of not tempered and annealed high-strength steel excellent ion resistance to hop dip galvanizing crackInfo
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- JPH1096017A JPH1096017A JP25206696A JP25206696A JPH1096017A JP H1096017 A JPH1096017 A JP H1096017A JP 25206696 A JP25206696 A JP 25206696A JP 25206696 A JP25206696 A JP 25206696A JP H1096017 A JPH1096017 A JP H1096017A
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- steel
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- strength
- dip galvanizing
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、主として鉄塔用鋼
材として用いられる耐溶融亜鉛メッキ割れ特性に優れた
非調質高強度鋼の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a non-refined high-strength steel excellent in hot-dip galvanizing crack resistance mainly used as a steel material for a steel tower.
【０００２】[0002]
【従来の技術】近年、使用鋼材の重量低減を目的とした
高強度鋼材が種々の分野で積極的に使用されるようにな
ってきた。送電用鉄塔向け鋼材にもこのような傾向が現
れてきており、現在引張強さが５９０ＭＰａ級の鋼材が
用いられている。また、大型送電鉄塔は、山中に建設さ
れることが多く、資材の運搬におけるコスト低減のため
更なる高張力化が求められている。2. Description of the Related Art In recent years, high-strength steel materials for the purpose of reducing the weight of steel materials used have been actively used in various fields. Such a tendency has also appeared in steel materials for power transmission towers, and steel materials having a tensile strength of 590 MPa class are currently used. In addition, large power transmission towers are often constructed in the mountains, and further higher tension is required to reduce costs in transporting materials.
【０００３】鉄塔用鋼材は建設された後にメンテナンス
フリーとするため溶融亜鉛メッキが施される。鉄塔用の
形鋼（例えば等辺等厚山形鋼）は、現地で溶接施工をす
ることなく鉄塔とすることが可能であるため、母材のメ
ッキ割れ感受性が重要視されるが、７８０ＭＰａ以上の
高強度形鋼ではメッキ処理時に形鋼のボルト接合用の穴
開け部からメッキ割れが生じるおそれがあるので高強度
化の大きな妨げとなっている。[0003] After being constructed, steel materials for steel towers are subjected to hot-dip galvanizing to make them maintenance-free. Since steel sections for steel towers (e.g., equilateral equiangular section steels) can be made into steel towers without welding work on site, plating cracking susceptibility of the base material is regarded as important, but high strength of 780 MPa or more is required. In the case of high-strength section steel, plating cracking may occur from a drilled portion for bolt connection of the section steel at the time of plating treatment, which hinders high strength.
【０００４】溶融亜鉛メッキされる高強度鋼に関しては
従来より特開昭５８−８４９５９号公報および特開昭５
９−１１３１６号公報などの技術が提案されてきたが、
いずれも溶接部において発生する割れの防止を対象とす
るものであり、高強度鋼においてボルト穴加工部からの
割れを防止する観点からの知見は少ないのが現状であ
る。A high strength steel to be hot-dip galvanized has been disclosed in Japanese Patent Application Laid-Open Nos.
Techniques such as 9-1316 have been proposed,
All of them are aimed at preventing cracks generated in the welded portion, and at present, there is little knowledge from the viewpoint of preventing cracks from being formed in bolted portions in high-strength steel.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、上記問題点
を根本的に解決するためのものであり、７８０ＭＰａ以
上の高強度を有し、母材のボルト穴加工部の耐溶融亜鉛
メッキ割れ特性に優れた非調質型高張力鋼の製造方法を
提供するものである。SUMMARY OF THE INVENTION The present invention is to fundamentally solve the above-mentioned problems, and has a high strength of 780 MPa or more, and is resistant to hot-dip galvanizing cracks in bolted portions of a base material. An object of the present invention is to provide a method for producing a non-heat treated high-tensile steel having excellent characteristics.
【０００６】[0006]
【課題を解決するための手段】本発明は、この目的を達
成するためになされたもので、 （１）重量比でＣ：０．０８〜０．２０％、Ｓｉ：０．
６％以下、Ｍｎ：１．０〜２．０％、Ｃｕ：２．０％以
下、Ｎｉ：２．０％以下、Ｃｒ：１．０％以下、Ｍｏ：
１．０％以下、Ｎｂ：０．１〜０．１５％、Ｖ：０．１
〜０．２％、Ｎｂ＋０．５Ｖ＋Ｔｉ≧０．１７５％を含
み、残部がＦｅおよび不可避的不純物からなる鋼を１１
００〜１３５０℃に加熱し、８００℃以下で熱間圧延を
終了させ、引張強度を７８０ＭＰａ級とすることを特徴
とする耐溶融亜鉛メッキ割れ特性に優れた非調質高強度
鋼の製造方法。Means for Solving the Problems The present invention has been made to achieve this object. (1) C: 0.08 to 0.20% by weight, Si: 0.
6% or less, Mn: 1.0 to 2.0%, Cu: 2.0% or less, Ni: 2.0% or less, Cr: 1.0% or less, Mo:
1.0% or less, Nb: 0.1 to 0.15%, V: 0.1
11% of steel containing 0.2% and Nb + 0.5V + Ti ≧ 0.175%, with the balance being Fe and unavoidable impurities.
A method for producing a non-refined high-strength steel excellent in hot-dip galvanizing crack resistance, wherein the steel is heated to 00 to 1350 ° C, hot rolling is completed at 800 ° C or lower, and the tensile strength is set to a 780 MPa class.
【０００７】（２）重量比でＴｉ：０．２％以下を含有
することを特徴とする（１）に記載の耐溶融亜鉛メッキ
割れ特性に優れた非調質高強度鋼の製造方法。(2) The method for producing a non-refined high-strength steel excellent in hot-dip galvanizing crack resistance as described in (1), characterized by containing not more than 0.2% by weight of Ti.
【０００８】（３）重量比でＣａ：０．００４％以下を
添加することを特徴とする（１）または（２）に記載の
耐溶融亜鉛メッキ割れ特性に優れた非調質高強度鋼の製
造方法である。(3) A non-heat treated high-strength steel excellent in hot-dip galvanizing crack resistance according to (1) or (2), wherein Ca: 0.004% or less is added in a weight ratio. It is a manufacturing method.
【０００９】[0009]
【発明の実施の形態】本発明者らは、０．１１Ｃ−０．
２５Ｓｉを基本成分として、Ｍｎ，Ｎｂ，Ｖ，Ｔｉ添加
量を変化させ、さらにＣａを添加した鋼も含め、熱間圧
延により等辺厚山形鋼とし、常温引張強度と溶融亜鉛メ
ッキ浴中で引張試験を行って得られた伸び値との関係に
おける添加元素の影響を検討した。常温引張はＪＩＳ１
Ａ号試験片で、浴中引張は図２に示す試験片で行った。BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have prepared 0.11C-0.
With 25Si as a basic component, the amount of Mn, Nb, V, and Ti added and the amount of Ca added, including steels, were hot-rolled into equilateral thick angle irons, and tensile tests were conducted at room temperature tensile strength and hot-dip galvanizing bath. The effect of the added element on the relationship with the elongation value obtained by performing the above was examined. Room temperature tension is JIS1
For the A test piece, the tensile test in the bath was performed on the test piece shown in FIG.
【００１０】一般にメッキ浴中引張試験における伸びが
２０％以下の場合、実際の溶融亜鉛メッキにおいて割れ
が発生することから、メッキ浴中引張における伸び２０
％をしきい値とした。その結果、Ｎｂ＋０．５Ｖ＋Ｔｉ
値によって両者の関係が整理され、ボルト穴加工等がさ
れる高強度鋼ではＮｂ＋０．５Ｖ＋Ｔｉ≧０．１７５％
を満足させる必要があることを知見した。すなわち、図
１に示すようにＮｂ＋０．５Ｖ＋Ｔｉ値が０．１５％の
場合、伸びは低く、高強度鋼では伸びが２０％以下とな
るが、この値が０．１７５％を超えるようになると、高
強度鋼においても伸びは２０％以上になる。In general, when the elongation in the tensile test in the plating bath is 20% or less, cracks occur in the actual hot-dip galvanizing.
% Was set as the threshold value. As a result, Nb + 0.5V + Ti
Nb + 0.5V + Ti ≧ 0.175% for high-strength steel on which bolt holes are drilled etc.
It was found that it was necessary to satisfy That is, as shown in FIG. 1, when the Nb + 0.5V + Ti value is 0.15%, the elongation is low, and the elongation of the high-strength steel is 20% or less, but when this value exceeds 0.175%, Even in high strength steel, the elongation is 20% or more.
【００１１】更に、ＴｉもしくはＣａ又はＴｉ−Ｃａを
複合添加した場合、浴中引張における伸びが増大する効
果が認められた。Further, when Ti or Ca or Ti-Ca is added in combination, an effect of increasing elongation in tension in a bath was recognized.
【００１２】以下、添加成分の限定理由を説明する。Hereinafter, the reasons for limiting the added components will be described.
【００１３】Ｃ：０．０８〜０．２０％ Ｃは強度を高めるのに必須の元素である。０．０８％未
満では７８０ＭＰａ以上の強度を得るのが困難で、０．
２０％を越えると鋼の靱性が著しく劣化するため、０．
０８％以上、０．２０％以下に限定した。C: 0.08 to 0.20% C is an essential element for increasing the strength. If it is less than 0.08%, it is difficult to obtain a strength of 780 MPa or more.
If it exceeds 20%, the toughness of the steel is significantly deteriorated.
It was limited to not less than 08% and not more than 0.20%.
【００１４】Ｓｉ：０．６０％以下 Ｓｉはメッキ後の外観状況と関係しており、０．６％を
越えるとメッキ焼けが発生しやすくなる。よって、０．
６０％以下に限定した。Si: 0.60% or less Si is related to the appearance after plating, and if it exceeds 0.6%, plating burn is likely to occur. Therefore, 0.
It was limited to 60% or less.
【００１５】Ｍｎ：１．０〜２．０％ Ｍｎは強度、靱性の面から必須の元素であるが、１．０
％未満では７８０ＭＰａ以上の強度を得るのが困難で、
２．０％を越えると焼き入れ性が高くなり粗いベイナイ
トが生成し、靱性が著しく劣化するため、Ｍｎ：１．０
％以上２．０％以下に限定した。Mn: 1.0 to 2.0% Mn is an essential element in view of strength and toughness.
%, It is difficult to obtain a strength of 780 MPa or more,
If it exceeds 2.0%, the hardenability increases, coarse bainite is formed, and the toughness is significantly deteriorated.
% To 2.0%.
【００１６】Ｐ：不可避不純物レベル Ｐは粒界に偏析し、靱性を劣化するが、現状の精錬技術
で十分に低減されているため、上限値は限定しないが、
低いほど望ましい。P: unavoidable impurity level P segregates at the grain boundaries and degrades toughness, but the upper limit value is not limited because it is sufficiently reduced by the current refining technology.
Lower is more desirable.
【００１７】Ｓ：不可避不純物レベル Ｓは主に介在物の形態で鋼中に存在し、脆化により材質
の劣化を引き起こすが、現状の精錬技術では十分に低減
されているため、上限値は限定しないが、低いほど望ま
しい。S: Inevitable impurity level S is mainly present in the form of inclusions in steel and causes deterioration of the material due to embrittlement. However, since the current refining technology is sufficiently reduced, the upper limit is limited. No, but lower is better.
【００１８】Ｃｕ：２．０％以下 Ｃｕは鋼の強度を高めるのに有効な元素であるが、２．
０％を越えて添加した場合にはＣｕ割れが発生しやす
い。よって２．０％以下に限定した。Cu: 2.0% or less Cu is an effective element for increasing the strength of steel.
When added in excess of 0%, Cu cracks are likely to occur. Therefore, it was limited to 2.0% or less.
【００１９】Ｎｉ：２．０％以下 Ｎｉは鋼の強度上昇ならびに靱性向上に有効な元素であ
るが、経済性を考慮し、２．０％以下に限定した。Ni: 2.0% or less Ni is an element effective for increasing the strength and toughness of steel, but is limited to 2.0% or less in consideration of economy.
【００２０】Ｃｒ：１．０％以下 Ｃｒは鋼の強度を高めるのに有効な元素であるが、１．
０％を越えて添加すると鋼の靱性を劣化させるため、
１．０％以下に限定した。Cr: 1.0% or less Cr is an element effective for increasing the strength of steel.
If added in excess of 0%, the toughness of the steel deteriorates.
It was limited to 1.0% or less.
【００２１】Ｍｏ：１．０％以下 Ｍｏは鋼の強度を高めるのに有効な元素であるが、１．
０％を越えて添加すると鋼の靱性を著しく劣化させるた
め、１．０％以下に限定した。Mo: 1.0% or less Mo is an element effective for increasing the strength of steel.
If added in excess of 0%, the toughness of the steel will be significantly degraded, so it was limited to 1.0% or less.
【００２２】Ｔｉ：０．２％以下 Ｔｉは微量の添加で析出強化により鋼の強度を高め、ま
た耐溶融亜鉛メッキ割れ特性に優れた性質を示すため有
効な元素であるが、０．２％を越えて添加すると鋼中析
出物が粗くなり、鋼の靱性が著しく劣化するため、０．
２％以下に限定し、必要に応じて添加できるものとし
た。Ti: 0.2% or less Ti is an effective element because it enhances the strength of steel by precipitation strengthening with a small amount of addition and exhibits excellent properties in hot-dip galvanizing cracking resistance. If added in excess of, the precipitates in the steel become coarse and the toughness of the steel deteriorates significantly.
It was limited to 2% or less, and could be added as needed.
【００２３】Ｎｂ：０．１５％以下、Ｖ：０．２％以下 Ｎｂ、Ｖは微量の添加で析出強化により鋼の強度を高め
るのに有効な元素であり、Ｎｂ含有量が０．１〜０．１
５％の範囲を外れるか、またはＶ含有量が０．１〜０．
２％の範囲を外れて過剰に添加されると、鋼の靭性を著
しく劣化させるため、上記値に限定した。Nb: 0.15% or less, V: 0.2% or less Nb and V are effective elements for increasing the strength of steel by precipitation strengthening with a small amount of addition. 0.1
When the content is out of the range of 5% or the V content is 0.1 to 0.5%.
If added excessively outside the range of 2%, the toughness of the steel is remarkably deteriorated.
【００２４】Ｎｂ＋０．５Ｖ＋Ｔｉ≧０．１７５％ Ｔｉ，Ｎｂ，Ｖはいずれも析出強化により鋼の強度を高
めるのに有効な元素であるが、７８０ＭＰａ以上の強度
を有し、耐溶融亜鉛メッキ割れに優れた特性を示す条件
として、Ｎｂ＋０．５Ｖ＋Ｔｉ≧０．１７５％の関係式
を満足させるものとする。なお、これらの元素は必要に
応じて添加できるものとする。Nb + 0.5V + Ti ≧ 0.175% Ti, Nb, and V are all effective elements for increasing the strength of steel by precipitation strengthening, but have a strength of 780 MPa or more and are resistant to hot-dip galvanizing cracks. As a condition showing excellent characteristics, it is assumed that a relational expression of Nb + 0.5V + Ti ≧ 0.175% is satisfied. Note that these elements can be added as needed.
【００２５】Ｃａ：０．００４％以下 Ｃａは添加することで耐溶融亜鉛メッキ割れ特性を著し
く改善することができる唯一の元素である。しかし、
０．００４％を越えて添加すると、Ｃａ−Ｏ−Ｓのクラ
スターが発生し、鋼の清浄性が低下してしまう。従っ
て、Ｃａを０．００４％以下に限定した。Ca: 0.004% or less Ca is the only element that can significantly improve the hot-dip galvanizing crack resistance by adding Ca. But,
If it is added in excess of 0.004%, Ca-OS clusters are generated and the cleanliness of the steel decreases. Therefore, Ca was limited to 0.004% or less.
【００２６】Ａｌ：Ａｌは本発明においては脱酸のため
に添加する場合もあり、その場合は通常の添加量（０．
００５〜０．０６０％）とする。形鋼などでＳｉ脱酸に
おいては不可避不純物として扱う。Al: In the present invention, Al may be added for deoxidation, in which case the usual addition amount (0.
005 to 0.060%). Treated as inevitable impurities in Si deoxidation in section steel and the like.
【００２７】Ｂ：不可避不純物レベル Ｂは鋼の焼き入れ性を向上させるが、溶接部の耐溶融亜
鉛メッキ割れ性を著しく劣化させるため、溶接される場
合、２ｐｐｍ以下に管理されている。本発明鋼は原則と
して溶接施工を対象としないので、Ｂの上限は５ｐｐｍ
程度の管理とする。しかし、Ｂは低いほど望ましく、溶
接が避けられない場合は上記に従う。B: Inevitable impurity level B improves the hardenability of steel, but significantly deteriorates the hot-dip galvanizing cracking resistance of the welded portion. Therefore, when welding, B is controlled to 2 ppm or less. Since the steel of the present invention is not intended for welding in principle, the upper limit of B is 5 ppm.
Management. However, B is preferably as low as possible, and if welding is inevitable, the above is followed.
【００２８】次に、製造条件の限定理由を説明する。Next, the reasons for limiting the manufacturing conditions will be described.
【００２９】加熱温度：１１００〜１３５０℃ １１００℃以下の加熱温度の場合、析出強化を期待する
添加元素が完全に固溶しないため、十分な強度が得られ
ない。また、１３５０℃以上に加熱した場合、加熱粒径
が著しく粗くなり、靭性が劣化する。従って、加熱温度
を１１００〜１３５０℃の範囲に限定した。Heating temperature: 1100 to 1350 ° C. If the heating temperature is 1100 ° C. or less, sufficient strength cannot be obtained because the added element expected to strengthen precipitation does not completely form a solid solution. Further, when heated to 1350 ° C. or higher, the heated particle size becomes extremely coarse, and the toughness is deteriorated. Therefore, the heating temperature was limited to the range of 1100 to 1350 ° C.
【００３０】圧延仕上温度：８００℃以下 ８００℃を越える温度で圧延を終了した場合、組織が粗
くなり十分な靭性が得られない。従って、圧延仕上温度
を８００℃以下に限定した。なお、厚板等の場合、圧延
終了温度は６５０℃程度となる。Rolling finish temperature: 800 ° C. or less If rolling is completed at a temperature exceeding 800 ° C., the structure becomes coarse and sufficient toughness cannot be obtained. Therefore, the rolling finishing temperature was limited to 800 ° C. or less. In the case of a thick plate or the like, the rolling end temperature is about 650 ° C.
【００３１】[0031]
【実施例】表１に実施例を示す。各鋼は表中に示す各製
造条件で等辺等厚山形鋼に圧延した。表中のメッキ割れ
の有無の項は、圧延した山形鋼に実際の施工と同様に、
接合用ボルトの穴開け加工を施した後に溶融亜鉛メッキ
浴中に浸漬し、穴開け加工部から割れが発生するかどう
かを確認した結果である。Examples are shown in Table 1. Each steel was rolled into an equilateral equal thickness angle steel under the respective manufacturing conditions shown in the table. The term of presence or absence of plating cracks in the table, as in the actual construction for rolled angle iron,
This is a result of confirming whether or not a crack is generated from a drilled portion after immersing the jointing bolt in a hot-dip galvanizing bath after drilling.
【００３２】表１中の「製造」の項は、各鋼の加熱温度
及び圧延仕上温度の条件をそれぞれ記号Ａ〜Ｄで表した
ものである。記号Ａは加熱温度１２３５℃で圧延仕上温
度７６５℃の条件を、記号Ｂは加熱温度９８０℃で圧延
仕上温度６９０℃の条件を、記号Ｃは加熱温度１２４０
℃で圧延仕上温度８８０℃の条件を、記号Ｄは加熱温度
１３８５℃で圧延仕上温度７９５℃の条件をそれぞれ示
す。The term "manufacturing" in Table 1 shows the conditions of the heating temperature and the rolling finishing temperature of each steel by symbols A to D, respectively. The symbol A is a condition at a heating temperature of 1235 ° C and a rolling finish temperature of 765 ° C, the symbol B is a condition at a heating temperature of 980 ° C and a rolling finish temperature of 690 ° C, and the symbol C is a heating temperature of 1240 ° C.
C shows the condition of a rolling finish temperature of 880 ° C, and symbol D shows the condition of a heating temperature of 1385 ° C and a rolling finish temperature of 795 ° C.
【００３３】また、表１中の「ＴＳ」の項は、ＪＩＳ１
Ａ号試験片を用いて調べた常温での引張強度（ＭＰａ）
を示したものである。The term “TS” in Table 1 is based on JIS1
Tensile strength at normal temperature (MPa) investigated using A test piece
It is shown.
【００３４】また、表１中の「ｖＴｒｓ」の項は、各鋼
の破面遷移温度（℃）をそれぞれ表したものである。The term “vTrs” in Table 1 indicates the fracture surface transition temperature (° C.) of each steel.
【００３５】１−１と１−２は本発明の請求範囲の化学
成分、製造条件を満足しているため、７８０ＭＰａ以上
の強度と優れた靭性を有し、メッキ割れも生じない。Since 1-1 and 1-2 satisfy the chemical components and manufacturing conditions of the present invention, they have a strength of 780 MPa or more, excellent toughness, and do not cause plating cracks.
【００３６】１−３は低Ｃで、低い加熱温度のため、７
８０ＭＰａ級の強度を確保することができない。1-3 has a low C and a low heating temperature.
The strength of the 80 MPa class cannot be secured.
【００３７】１−４はＣ量が多く、圧延仕上温度が８８
０℃と高いため、９４２ＭＰａと著しく高強度となり、
靭性が劣化し、メッキ割れが生じている。1-4 have a large C content and a rolling finish temperature of 88.
Because it is as high as 0 ° C., the strength becomes extremely high at 942 MPa,
The toughness has deteriorated and plating cracks have occurred.
【００３８】１−５はＳｉ量が多いためメッキ焼けが生
じ、また加熱温度が高いため強度が高く、靭性が劣化し
ており、メッキ割れが発生している。In the case of 1-5, a large amount of Si causes plating burn, and a high heating temperature results in high strength, poor toughness, and plating cracks.
【００３９】１−６は低Ｍｎ量のため強度が低く、引張
強度が７８０ＭＰａに達しない。1-6 has low strength due to low Mn content, and the tensile strength does not reach 780 MPa.
【００４０】１−７はＭｎ量が多いため、加熱温度は低
いが強度が高く、メッキ割れが発生している。In the case of 1-7, since the amount of Mn is large, the heating temperature is low but the strength is high, and plating cracks occur.
【００４１】１−８はＣｕが多く、圧延仕上温度も高い
ため、靭性が劣化しており、メッキ割れが生じている。In 1-8, since the content of Cu is large and the rolling finish temperature is high, the toughness is deteriorated and plating cracks occur.
【００４２】１−９はＮｉが多く加熱温度も著しく高い
ため、強度が高く、靭性が劣化しており、メッキ割れが
発生する。Since 1-9 contains a large amount of Ni and a remarkably high heating temperature, the strength is high, the toughness is deteriorated, and plating cracks occur.
【００４３】１−１０はＣｒ添加量が多いため、製造条
件は本発明の請求範囲を満足しているが、高強度とな
り、メッキ割れが生じている。In the case of 1-10, since the amount of Cr added is large, the production conditions satisfy the claims of the present invention, but the strength becomes high and plating cracks occur.
【００４４】１−１１はＭｏ添加量が多いため、加熱温
度が低いものの、強度が高く、メッキ割れが生じてい
る。In the case of 1-11, since the amount of Mo added is large, the heating temperature is low, but the strength is high and plating cracks occur.
【００４５】１−１２はＮｂ＋Ｖ＋Ｔｉ添加量が請求範
囲以下であるため、製造条件は請求範囲以内であるが、
メッキ割れが生じている。In the case of No. 1-12, since the added amount of Nb + V + Ti is below the claimed range, the production conditions are within the claimed range.
Plating cracks have occurred.
【００４６】１−１３はＴｉ添加量が多すぎることと、
加熱温度が著しく高いため析出物が粗くなり、靭性も劣
化して、その結果メッキ割れが生じている。1-13 indicates that the amount of Ti added is too large,
Due to the remarkably high heating temperature, the precipitate becomes coarse and the toughness is deteriorated, resulting in plating cracks.
【００４７】１−１４はＮｂ添加量が多いため、製造条
件は請求範囲を満たしているものの、高強度となり、メ
ッキ割れが生じている。In the case of 1-14, since the amount of Nb added is large, the production condition satisfies the claims, but the strength becomes high and plating cracks occur.
【００４８】１−１５はＶ添加量が多いため、加熱温度
が低く引張強度は８３３ＭＰａであるものの、メッキ割
れが生じている。In the case of 1-15, since the amount of V added was large, the heating temperature was low and the tensile strength was 833 MPa, but plating cracks occurred.
【００４９】１−１６はＣａ添加量が高く、鋼の清浄度
が劣るため、割れが発生している。In the case of 1-16, the content of Ca was high and the cleanliness of the steel was inferior, so that cracks occurred.
【００５０】１−１７は成分が請求範囲を満たしている
が、加熱温度が著しく高いため組織が粗くなり、靭性が
劣化し、メッキ割れが生じている。Although the components 1-17 satisfy the claims, the heating temperature is extremely high, so that the structure becomes coarse, the toughness is deteriorated, and plating cracks occur.
【００５１】１−１８は成分および製造条件ともに請求
範囲を満たしているため、強度が高く、高靭性であり、
メッキ割れの発生も認められない。1-18 has high strength and high toughness because both components and manufacturing conditions satisfy the claims.
No generation of plating crack is observed.
【００５２】１−１９は成分は請求範囲を満たしている
ものの、加熱温度が低いため強度不足となっている。The components 1-19 satisfy the claims, but have insufficient strength due to low heating temperature.
【００５３】１−２０は成分は請求範囲を満たしている
が、圧延仕上温度が高いため、靭性が低く、メッキ割れ
が生じている。The component 1-20 satisfies the claims, but the rolling finish temperature is high, so that the toughness is low and plating cracks occur.
【００５４】[0054]
【表１】 [Table 1]
【００５５】[0055]
【発明の効果】本発明によれば、鉄塔や橋梁等の構造物
部材でボルト穴加工等をした後、溶融亜鉛メッキ処理さ
れても割れを生じない耐溶融亜鉛メッキ割れ特性に優れ
た非調質高強度鋼の製造方法を提供することができる。According to the present invention, after forming bolt holes in a structural member such as a steel tower or a bridge, cracks do not occur even when hot-dip galvanizing treatment is performed. A method for producing high-quality high-strength steel can be provided.
【図１】鋼材の常温強度ＴＳ（ＭＰａ）とメッキ浴中引
張試験の伸び（％）との関係を示す図。FIG. 1 is a diagram showing the relationship between the room temperature strength TS (MPa) of a steel material and the elongation (%) of a tensile test in a plating bath.
【図２】溶融亜鉛中における母材の脆化を調べるための
引張試験片を示す図である。FIG. 2 is a diagram showing a tensile test piece for examining embrittlement of a base material in molten zinc.
Claims (3)
ｉ：０．６０％以下，Ｍｎ：１．０〜２．０％，Ｃｕ：
２．０％以下，Ｎｉ：２．０％以下，Ｃｒ：１．０％以
下，Ｍｏ：１．０％以下，Ｎｂ：０．１〜０．１５％、
Ｖ：０．１〜０．２％、Ｎｂ＋０．５Ｖ＋Ｔｉ≧０．１
７５％を含み、残部がＦｅおよび不可避的不純物からな
る鋼を１１００〜１３５０℃に加熱し、８００℃以下で
熱間圧延を終了させ、引張強度を７８０ＭＰａ級とする
ことを特徴とする耐溶融亜鉛メッキ割れ特性に優れた非
調質高強度鋼の製造方法。1. A weight ratio of C: 0.08 to 0.20%, S
i: 0.60% or less, Mn: 1.0 to 2.0%, Cu:
2.0% or less, Ni: 2.0% or less, Cr: 1.0% or less, Mo: 1.0% or less, Nb: 0.1 to 0.15%,
V: 0.1-0.2%, Nb + 0.5V + Ti ≧ 0.1
A molten zinc-resistant steel characterized in that a steel containing 75% and the balance consisting of Fe and unavoidable impurities is heated to 1100 to 1350 ° C, hot rolling is completed at 800 ° C or less, and the tensile strength is 780 MPa class. A method for producing non-heat treated high strength steel with excellent plating cracking characteristics.
ことを特徴とする請求項１記載の耐溶融亜鉛メッキ割れ
特性に優れた非調質高強度鋼の製造方法。2. The method for producing a non-heat treated high-strength steel excellent in hot-dip galvanizing crack resistance according to claim 1, wherein the steel contains Ti: 0.2% or less by weight.
することを特徴とする請求項１または請求項２記載の耐
溶融亜鉛メッキ割れ特性に優れた非調質高強度鋼の製造
方法。3. The method for producing a non-refined high-strength steel excellent in hot-dip galvanizing crack resistance according to claim 1, wherein Ca: 0.004% or less is added in a weight ratio. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25206696A JPH1096017A (en) | 1996-09-24 | 1996-09-24 | Manufacture of not tempered and annealed high-strength steel excellent ion resistance to hop dip galvanizing crack |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25206696A JPH1096017A (en) | 1996-09-24 | 1996-09-24 | Manufacture of not tempered and annealed high-strength steel excellent ion resistance to hop dip galvanizing crack |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH1096017A true JPH1096017A (en) | 1998-04-14 |
Family
ID=17232084
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25206696A Pending JPH1096017A (en) | 1996-09-24 | 1996-09-24 | Manufacture of not tempered and annealed high-strength steel excellent ion resistance to hop dip galvanizing crack |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH1096017A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1365035A1 (en) * | 2002-05-07 | 2003-11-26 | SAG Energieversorgungslösungen GmBH | Method of maintaining the steel lattice work of high tension masts |
-
1996
- 1996-09-24 JP JP25206696A patent/JPH1096017A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1365035A1 (en) * | 2002-05-07 | 2003-11-26 | SAG Energieversorgungslösungen GmBH | Method of maintaining the steel lattice work of high tension masts |
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