JPH032321A - Manufacture of high strength weather-resisting hot rolled steel sheet - Google Patents
Manufacture of high strength weather-resisting hot rolled steel sheetInfo
- Publication number
- JPH032321A JPH032321A JP13662589A JP13662589A JPH032321A JP H032321 A JPH032321 A JP H032321A JP 13662589 A JP13662589 A JP 13662589A JP 13662589 A JP13662589 A JP 13662589A JP H032321 A JPH032321 A JP H032321A
- Authority
- JP
- Japan
- Prior art keywords
- strength
- hot
- rolled steel
- steel sheet
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 52
- 239000010959 steel Substances 0.000 title claims abstract description 52
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 229910052802 copper Inorganic materials 0.000 claims abstract description 11
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 10
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 9
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 5
- 238000004804 winding Methods 0.000 claims description 4
- 238000009749 continuous casting Methods 0.000 claims description 3
- 238000005098 hot rolling Methods 0.000 abstract description 23
- 230000007797 corrosion Effects 0.000 abstract description 8
- 238000005260 corrosion Methods 0.000 abstract description 8
- 229910052782 aluminium Inorganic materials 0.000 abstract description 5
- 238000001816 cooling Methods 0.000 abstract description 3
- 230000001105 regulatory effect Effects 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 13
- 238000010438 heat treatment Methods 0.000 description 12
- 238000005452 bending Methods 0.000 description 11
- 238000005096 rolling process Methods 0.000 description 8
- 229910000870 Weathering steel Inorganic materials 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 239000002244 precipitate Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000003303 reheating Methods 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910017813 Cu—Cr Inorganic materials 0.000 description 1
- 101100351804 Schizosaccharomyces pombe (strain 972 / ATCC 24843) pfl8 gene Proteins 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000003562 lightweight material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 235000019640 taste Nutrition 0.000 description 1
- 229910052716 thallium Inorganic materials 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Landscapes
- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は強度および耐候性が要求される鉄道車輌、コン
テナー 自動車、建築、土木等の鋼素材の製造方法に関
するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing steel materials for railway vehicles, container automobiles, architecture, civil engineering, etc., which require strength and weather resistance.
［従来の技術］
従来、鉄道車輌は軽量、長寿命化を目的としてステンレ
ス車輌あるいはアルミ車輌が開発されてきたが、価格が
極めて高かった。このことは、車輌が３０年以上の長寿
命であることからこれまでは大きな欠点ではなかった。[Prior Art] Conventionally, stainless steel or aluminum railway vehicles have been developed with the aim of making them lighter and have a longer lifespan, but these have been extremely expensive. This has not been a major drawback until now because the vehicles have a long lifespan of over 30 years.
、しかし、鉄道会社間および他の交通機関との競争激化
にともない、多様化する乗客の要望にこたえるため鉄道
車輌にも高速、軽量、ファツション性といった機能が要
求されるようになった。フフッジョン性を持った車輌に
は種々の色に塗装が可能で、しかも好みに合わせた改造
が容易であることが必要で、このような車輌の素材とし
ては古くから使用され、しかも経済的な耐候性鋼が見立
されてきた。さらに軽量化の観点から高耐候性と同時に
高強度が得られれば理想的である。However, with the intensification of competition between railway companies and other means of transportation, railway vehicles are now required to have features such as high speed, light weight, and fashionability in order to meet the diversifying needs of passengers. Vehicles with fusion properties must be able to be painted in a variety of colors and be easily modified to suit individual tastes. Weathering steel has been on the rise. Furthermore, from the viewpoint of weight reduction, it would be ideal if high strength could be obtained at the same time as high weather resistance.
高耐候性圧延鋼材として、ＪＩＳ Ｇ３１２５ （記
号ＳＰ＾−Ｈ）があるが、この鋼の引張強さは５０ｋｇ
ｆ／ｍｍ２級であり、目的とする強度が得られない。ま
た、引張強さ６０ ｋｇｆ／＋ｎｍ２級として溶接構造
用耐候性熱間圧延鋼材ＪＩＳ Ｇ３１１４ （ＳＭＡ５
８）があるが、これは溶接性を重視し、やや耐候性が低
下するので鉄道車輌用としては用いられていなかった。JIS G3125 (symbol SP^-H) is a highly weather-resistant rolled steel material, and the tensile strength of this steel is 50 kg.
f/mm2 class, and the desired strength cannot be obtained. In addition, the tensile strength is 60 kgf/+nm class 2, and weather-resistant hot-rolled steel for welded structures JIS G3114 (SMA5
8), but this was not used for railway vehicles because it placed emphasis on weldability and had a slightly lower weather resistance.
そこで、鉄道車輌用として、高耐候性の６０ ｋｇｆ／
ｍＣＱ２級以上の鋼板の開発が必要になった。Therefore, a highly weather-resistant 60 kgf/
It became necessary to develop steel plates of mCQ grade 2 or higher.
また、コンテナーは輸送システムに大きな経済効果をも
たらし、その需要市場は拡大の傾向にある。さらに輸送
効率を高めるためコンテナーの軽量化が注目され、その
代表としてアルミニウムコンテナーがある。しかし、ア
ルミニウムコンテナーは価格が高いことが欠点で、コン
テナー用としても経済的な高強度で耐候性の良い鋼板の
開発が必要となった。Containers also have a significant economic effect on transportation systems, and the demand market for them is on the rise. Furthermore, lightweight containers are attracting attention in order to improve transportation efficiency, and aluminum containers are a typical example of this. However, the disadvantage of aluminum containers is that they are expensive, so it became necessary to develop a steel plate with high strength and good weather resistance that was also economical for use in containers.
［発明が解決しようとする課題］
これまで、特開昭６３−７２８５３号で塗膜下腐食の少
ないコンテナー用耐蝕性熱延鋼板が提案されている。こ
の鋼板は海上コンテナー用として塗膜下腐食を改善した
高強度の耐蝕性熱延鋼板である。しかし、この鋼板は高
強度化に伴って低下する曲げ加工性の低下には考慮がは
られれておらず、しかも、引張強さは最大８８ ｋｇｆ
／ｍｍ”までしか得られていない。[Problems to be Solved by the Invention] Until now, a corrosion-resistant hot-rolled steel sheet for containers with less under-coating corrosion has been proposed in JP-A-63-72853. This steel plate is a high-strength, corrosion-resistant hot-rolled steel plate with improved under-coating corrosion for marine containers. However, this steel plate does not take into consideration the decrease in bending workability that occurs with increasing strength, and furthermore, the tensile strength is only 88 kgf at maximum.
/mm” has been obtained.
本発明は加工性の良好な６０ ｋｇｆ／＋ｎｍ２以上の
高強度鋼板で、しかも、高耐候性の熱延鋼板の製造方法
を提供するものである。The present invention provides a method for producing a hot-rolled steel sheet that is a high-strength steel sheet of 60 kgf/+nm2 or more that has good workability and has high weather resistance.
［課題を解決するための手段］
本発明は上述の課題を有利に解決したものでありその要
旨は以下の通りである。[Means for Solving the Problems] The present invention advantageously solves the above-mentioned problems, and the gist thereof is as follows.
Ｃ： ０．０２〜０．０５０． Ｓｉ≦０．５０％、
Ｍｎ：０．１０〜２．００％、 Ｐ ： ０．０
７０ 〜０．１５０ ％、 Ｓ ≦０．０２０％、Ａ
ｌ： ０．０１０ 〜０．０５０ ％、 Ｃｕ：
０．２５〜０．５５％、 Ｃｒ ： ０．３０
〜１．２５％、 Ｎ≦０．００８０％、Ｔｌ：０．０６
〜０．０５０
１．０（ここで、Ｔｉ ＊ｔｔ（９６） ＝Ｔｉ（％ｉ
）−３，４ｘ Ｎ（豹−１，５Ｘ Ｏ（ｋ））、残部不
可避的成分および鉄を含有した鋳片を連続鋳造で製造し
、１１８０℃以上に再加熱後熱間圧延し、熱間圧延温度
を８８０〜９５０℃とし、巻取温度を６５０℃以下とす
ることにより、引張強さ６０ ｋｇｆ／ｍｍ”以上で冷
間加工性の良い耐候性熱延鋼板を得ることを特徴とする
高強度耐候性熱延鋼板の製造方法。C: 0.02-0.050. Si≦0.50%,
Mn: 0.10-2.00%, P: 0.0
70 ~ 0.150%, S ≦0.020%, A
l: 0.010 to 0.050%, Cu:
0.25-0.55%, Cr: 0.30
~1.25%, N≦0.0080%, Tl: 0.06
~0.050 1.0 (where Ti *tt(96) = Ti(%i
)-3,4x N (Leopard-1,5x O(k)), the balance containing unavoidable components and iron is manufactured by continuous casting, reheated to 1180°C or higher, hot rolled, and hot-rolled. By setting the rolling temperature to 880 to 950°C and the coiling temperature to 650°C or less, a weather-resistant hot-rolled steel sheet with a tensile strength of 60 kgf/mm or more and good cold workability can be obtained. A method for producing strong and weather-resistant hot-rolled steel sheets.
以下、本発明の内容を詳述する。Hereinafter, the content of the present invention will be explained in detail.
高耐候性圧延鋼材であるＪＩＳ Ｇ３１２５ （記号
５ＰＡ−Ｈ）が普通鋼に比べ４〜８倍の耐候性を持って
いる理由は、大気中にさらされた初めの期間は普通鋼と
同様に錆が発生するが、年月の経過と共にその錆の一部
が徐々にきわめて緻密な母材に密着した錆になり、その
錆層が環境に対して保護膜となり腐食進行を阻止するよ
うになるからである。ＰやＣｕ、Ｃｒなどを少量含むこ
とによってこのような錆ができることはよく知られてい
る。その錆層の構造は、開田、細井。The reason why JIS G3125 (symbol 5PA-H), a highly weather resistant rolled steel material, has weather resistance 4 to 8 times that of ordinary steel is that during the initial period of exposure to the atmosphere, it does not rust like ordinary steel. However, as time passes, some of that rust gradually becomes rust that adheres to the extremely dense base material, and this rust layer becomes a protective film against the environment and prevents corrosion from progressing. It is. It is well known that this kind of rust is caused by the presence of small amounts of P, Cu, Cr, etc. The structure of the rust layer is Kaida and Hosoi.
湯用、内藤二鉄と鋼５５ （１９６９） ｐ、３５５に
示され、これを第１図に図示した。即ち、
■ 耐候性鋼の錆層は地峡上に密着したＦｅ００１（（
Ｆｅ、０．Ｈ２Ｏ）がほとんどなく、ＦｅｏｏＨ層と地
峡間に非常に緻密な層が存在している。これに反し、普
通鋼の錆層には地鉄上にＦｅ０Ｏ）Ｉがあり、かつ亀裂
が多い。This is shown in Yuyo, Naito Nitetsu to Hagane 55 (1969) p. 355, and is illustrated in Figure 1. That is, ■ The rust layer of weathering steel is Fe001 ((
Fe, 0. There is almost no H2O), and a very dense layer exists between the FeooH layer and the isthmus. On the other hand, the rust layer of ordinary steel has Fe0O)I on the base metal and has many cracks.
■ 耐候性鋼の錆の下層に存在する緻密な層は、非晶質
である。■ The dense layer beneath the rust on weathering steel is amorphous.
■ ＰやＣｕ、Ｃｒなどはこの非晶Ｘ層に濃縮されてい
る。■P, Cu, Cr, etc. are concentrated in this amorphous X layer.
即ち、耐候性には安定な非晶質層を形成することが必要
であり、そのためにＰやＣｕ 、 Ｃｒの添加が有効で
ある。第１図（ａ）は耐候性鋼、（ｂ）は普通鋼を示す
。図中１はクラックを示す。That is, it is necessary to form a stable amorphous layer for weather resistance, and for this purpose, addition of P, Cu, and Cr is effective. FIG. 1(a) shows weathering steel, and FIG. 1(b) shows normal steel. 1 in the figure indicates a crack.
そこで、本発明者等は高強度耐候性鋼を開発するにあた
って、耐候性に必要な元素ＣｕやＰ。Therefore, in developing a high-strength weathering steel, the present inventors introduced the elements Cu and P necessary for weather resistance.
ＣｒはＪＩＳ Ｇ３１２５ （記号５ＰＡ−Ｈ）と同
一とし、冷間曲げ加工性を低下させないで強度を向上さ
せる方法を鋭意検討した。Cr was set to be the same as JIS G3125 (symbol 5PA-H), and a method of improving strength without reducing cold bending workability was intensively studied.
鋼の強度を増加する方法として、合金元素を添加する、
金属組織を制御する、あるいは微細析出物を利用するこ
とが良く知られている。このなかでＰ−Ｃｕ−Ｃｒ系鋼
を基本にしてＴｉＣにより析出強化させる方法を適用し
、そして成分および製造条件を最適に制御することによ
って、高強度で冷間加工性の良い耐候性熱延鋼板を製造
しうることを種々実験の結果見出した。なお、ＴＩは安
定錯生成にも有効な元素であることは良く知られている
。Adding alloying elements as a way to increase the strength of steel,
It is well known to control metal structure or utilize fine precipitates. Among these, by applying a method of precipitation strengthening with TiC based on P-Cu-Cr steel, and by optimally controlling the composition and manufacturing conditions, we have developed a weather-resistant hot rolled steel with high strength and good cold workability. As a result of various experiments, we found that it is possible to manufacture steel plates. It is well known that TI is an element that is also effective in forming stable complexes.
まず、冷間曲げ加工性は熱間圧延により圧延方向に伸ば
されたＭｎＳ系の介在物が鋼材中に存在すると低下する
ので、ＭｎＳをＴｉ添加により熱間圧延時に変形しにく
□いＴｉＳに変えることが必要である。そのためにはＴ
ｉ／Ｍｎを大きくするとＭｎＳからＴｉＳへの変換割合
が増える。First, cold bending workability deteriorates when MnS-based inclusions elongated in the rolling direction by hot rolling are present in the steel material. It is necessary to change. For that purpose, T
Increasing i/Mn increases the conversion rate from MnS to TiS.
第２図は１２．１ｘ Ｔｉ 、ｒｒ（％Ｆ）／Ｍｎ（％
Ｆ） と限界曲げ半径／板厚との関係を示した。これは
、ｏ 、 ｏａ＊ｃ−０，４０！ｋＳＩ−０，０１０零
Ｓ−０，１０％ＦＰ−０．３零Ｃｕ−０．２ｋＮｉ−０
，４零Ｃｒｆ１４を基本としてＴｉ！Ｉ；およびＭｎ零
を種々変化させた種々の鋼を製造し、加熱温度１２８０
℃で加熱し、熱間圧延仕上温度を８８０℃で板厚６ｍｍ
に熱間圧延し、６００℃で巻き取った熱延鋼板を用いて
実験が行われた。ここに、Ｔｉ 、ｒｒ（％１）−Ｔｉ
（！ｋ）−３，４ｘ Ｎ（％１）−１，５ｘ Ｏ（％Ｆ
）である。これによると、１２．１ｘ Ｔｉ ａｒｆ（
Ｘ）／Ｍｎ（Ｕが小さいときは曲げ割れが発生するが、
この比が１．０以上になると密着臼げでも割れないこと
が明らかになった。そこでＴｉ添加量は！２．１ｘ Ｔ
ｉ 、ｒｒ（ｋ）／ Ｍｎ（零）≧１．０必要である。Figure 2 shows 12.1x Ti, rr(%F)/Mn(%
F) and the relationship between limit bending radius/plate thickness. This is o, oa*c-0,40! kSI-0,010 zero S-0,10%FP-0.3 zero Cu-0.2kNi-0
, 40 Ti! based on Crf14! Various steels with various changes in I; and Mn zero were produced, and the heating temperature was 1280
℃, hot rolling finish temperature to 880℃, plate thickness 6mm
The experiment was conducted using a hot-rolled steel plate that was hot-rolled and wound at 600°C. Here, Ti, rr(%1)-Ti
(!k)-3,4x N(%1)-1,5x O(%F
). According to this, 12.1x Ti arf (
X)/Mn(When U is small, bending cracks occur, but
It has become clear that when this ratio is 1.0 or more, the material will not crack even when it is closely ground. So what is the amount of Ti added? 2.1xT
i, rr(k)/Mn(zero)≧1.0 is required.
鋼にＴｉを添加することによりＴｉはＮ、ＯおよびＳと
結合するが、さらに過剰のＴｉはＣと結合して微細Ｔｉ
Ｃとして析出することにより強度を向上させる。Ｔｉに
より強度を向上させるためには、まず熱間圧延前にはＴ
ｉが固溶状態であることが必要である。そのためには熱
間圧延前の再加熱温度をＴｉｃの溶体化温度以上にする
必要がある。このように溶体化しているＴｉが熱間圧延
後の冷却時に微細析出して強度を向上させると考えられ
る。By adding Ti to steel, Ti combines with N, O, and S, but excess Ti also combines with C and forms fine Ti.
Strength is improved by precipitating as C. In order to improve the strength with Ti, first of all, T should be added before hot rolling.
It is necessary that i be in a solid solution state. For this purpose, it is necessary to make the reheating temperature before hot rolling equal to or higher than the solution temperature of Tic. It is thought that the solutionized Ti is finely precipitated during cooling after hot rolling and improves the strength.
第３図は加熱温度およびＴｉ添加量と強度の関係を示す
。これによると、１２８０℃加熱の場合は、Ｔｉ添加量
が多くなってもＴｉｃの溶体化温度以上であるので、析
出微細ＴｉＣ量が多くなり、従って強度が高くなり、０
．１７零Ｔｉで８５ｋｇｆ／ｍｍ”の引張強さを示す。FIG. 3 shows the relationship between heating temperature, amount of Ti added, and strength. According to this, in the case of heating at 1280°C, even if the amount of Ti added is large, the temperature is above the solution temperature of Tic, so the amount of precipitated fine TiC increases, and therefore the strength increases, and the
．． 17 Zero Ti exhibits a tensile strength of 85 kgf/mm''.
また、加熱温度が１１８０℃の場合は、Ｔ１の添加量が
０．０７！にで引張強さ６５ｋｇｆ／ａｍ”を示し、そ
れ以上のＴｉ添加でも引張強さは同じである。一方、加
熱温度が１１００℃と低い場合はＴｉの添加量を増加さ
せても強度は殆ど向上しない。これは、Ｔｉは鋳片製造
時に大きなＴｉＣが析出し、低温では加熱時に有効に溶
体化しないため、強度向上に有効に作用しない。Also, when the heating temperature is 1180°C, the amount of T1 added is 0.07! It shows a tensile strength of 65 kgf/am'', and the tensile strength remains the same even if more Ti is added.On the other hand, when the heating temperature is as low as 1100°C, the strength hardly improves even if the amount of Ti added is increased. No. This is because large TiC precipitates during the production of a slab and does not effectively dissolve into a solution during heating at low temperatures, so it does not work effectively to improve strength.
このため、加熱温度は１１８０℃以上にする必要がある
。For this reason, the heating temperature needs to be 1180° C. or higher.
第４図は０．０７！ｋＴｉ鋼での熱間圧延仕上温度、巻
取温度と引張強さとの関係を示したものである。これに
示すように、熱間圧延仕上温度が８８０℃の場合は巻取
温度６５０℃以下で引張強さ６０ ｋｇｆ／ｍｍ”以上
を示すが、熱間圧延仕上温度が８００℃では引張強さ６
０ ｋｇｆ／ｍｍ２以下である。これは、熱間圧延仕上
温度が８８０℃以下ではＴｉＣは熱間圧延中に粗大析出
して、引張強さ゛を高めるために有効に働かず、また、
巻取温度が６５０℃より高い場合もＴｉｃは粗大化し引
張強さを高めるために有効に働かないためである。Figure 4 is 0.07! This figure shows the relationship between hot rolling finishing temperature, coiling temperature, and tensile strength in kTi steel. As shown in this figure, when the hot rolling finishing temperature is 880°C, the tensile strength is 60 kgf/mm” or more when the coiling temperature is 650°C or lower, but when the hot rolling finishing temperature is 800°C, the tensile strength is 60 kgf/mm” or more.
0 kgf/mm2 or less. This is because if the hot rolling finishing temperature is below 880°C, TiC will coarsely precipitate during hot rolling and will not work effectively to increase the tensile strength.
This is because when the winding temperature is higher than 650° C., Tic becomes coarse and does not work effectively to increase the tensile strength.
本発明者等はこれらの知見にもとづいて、Ｐ−Ｃｕ−Ｃ
ｒ系鋼を基本にして種々実験を行った結果、ＴｉＣの溶
体化処理に加えて熱延条件を最適に制御することにより
、耐候性が良く、１ｉ０ｋｇｆ／ｍｍ２以上の引張強さ
を持ち、しかも冷間加工性が極めて優れた熱延鋼板を発
明した。Based on these findings, the present inventors have developed P-Cu-C
As a result of conducting various experiments based on R-series steel, we found that by solution treatment of TiC and optimal control of hot rolling conditions, it has good weather resistance and tensile strength of 1i0 kgf/mm2 or more. We have invented a hot-rolled steel sheet with extremely excellent cold workability.
以下、本発明の鋼成分を限定した理由について詳細に説
明する。Hereinafter, the reason for limiting the steel components of the present invention will be explained in detail.
Ｃは、ＴｉＣによる析出物による鋼の強度を増加せしめ
る有効な成分として、０．０２％以上を含有させる。し
かし、Ｃの過剰な含有は、鋼中に多量の炭化物を形成し
て腐食発生の活性点となり、錆発生の安定化を遅らせた
り、加工性を低下させたりするので、その上限を０．１
２％とした。C is an effective component that increases the strength of steel due to TiC precipitates, and is contained in an amount of 0.02% or more. However, excessive C content forms a large amount of carbide in the steel, which becomes an active site for corrosion, which delays the stabilization of rust and reduces workability, so the upper limit is set at 0.1
It was set at 2%.
Ｓｔは、強度を向上させる成分として含有させるが、熱
延鋼板の表面性状を劣化させないために上限を０．５％
とした。St is included as a component to improve strength, but the upper limit is set at 0.5% to prevent deterioration of the surface quality of the hot rolled steel sheet.
And so.
Ｍｎは、鋼の耐蝕性に影響する度合いが小さく、鋼の強
度を向上するのに必要な元素である。しかし、過剰な含
有は加工性を損なうことがある。したがって、本発明に
おいてＭｎは０、ｌＯ〜２．００％の含有量に規制した
。Mn has a small effect on the corrosion resistance of steel and is an element necessary to improve the strength of steel. However, excessive content may impair processability. Therefore, in the present invention, the Mn content is regulated to 0.10 to 2.00%.
Ｐは、本発明において耐候性を支配する成分である。一
般にＰは、耐候性鋼の錆層に濃縮されることによって、
安定な錆の促進に効果があり、これらは必ずＣｕ、Ｃｒ
の共存によって安定績が形成されることに基づいている
。そこで、その添加量を０．０７０％以上とする。しか
し、過剰な含有は強度、靭性や溶接性など鋼に要求され
る諸特性を損うのでその上限を０．１５０％とした。P is a component that controls weather resistance in the present invention. Generally, P is concentrated in the rust layer of weathering steel.
It is effective in promoting stable rust, and these are always Cu and Cr.
It is based on the fact that stable performance is formed through the coexistence of the following. Therefore, the amount added is set to 0.070% or more. However, excessive content impairs various properties required of steel, such as strength, toughness, and weldability, so the upper limit was set at 0.150%.
Ｓは、加工性を害するので、少ない程望ましいが、経済
的に達成可能な上限を０．０２０％とした。Since S impairs processability, it is desirable to have less S, but the economically achievable upper limit was set at 0.020%.
Ｃｕは、安定績を形成させるのに有効な成分として腐食
環境に応じて０．２５％以上含有させる。Cu is an effective component for forming a stable performance, and is contained in an amount of 0.25% or more depending on the corrosive environment.
しかし、過剰な含有は熱延鋼板の表面性状を劣化させる
ために上限を０．５％とした。However, excessive content deteriorates the surface quality of the hot rolled steel sheet, so the upper limit was set at 0.5%.
Ｃｒは、Ｃｕ同様に安定績を形成させるのに有効な成分
として腐食環境に応じてＯＪＯ〜１．２５％含有させる
。Like Cu, Cr is an effective component for forming stability, and is contained in OJO to 1.25% depending on the corrosive environment.
Ａ交は、清浄鋼を得るために脱酸剤として添加されるも
のであるが、必要量は０．０１０％以上で、０．０５０
％を超える過剰な含有量では鋼を脆化する。したがって
、鋼に含まれるＡｎはｏ、ｏｔ。A-ac is added as a deoxidizing agent to obtain clean steel, and the required amount is 0.010% or more, and 0.050% or more.
Excess content exceeding % will make the steel brittle. Therefore, An contained in the steel is o, ot.
〜０．０５０％の含有量に規制した。The content was regulated to ~0.050%.
Ｎは、加工性を害するので、少ない程望ましいが、経済
的に達成可能な上限を０．００５０％とした。Since N impairs workability, it is desirable to have a small amount, but the economically achievable upper limit was set at 0.0050%.
Ｔｉは、本発明において加工性を損なわないで強度を向
上させる主要な元素である。すなわち、Ｔｉは熱間圧延
前に溶体化していると熱間圧延後にＴｉｃとして微細析
出して強度を向上させる。また、Ｔｉは鋼中のＳと結合
して熱間圧延時に変形しにくいＴｉＳとなり、圧延方向
に延ばされた介在物がなくなり、圧延方向に沿った曲げ
加工性を著しく改善する。そこで、Ｔｉは酸素（０）、
窒素（Ｎ） と結合するのに必要な等量を含有させた
上で、Ｓと結合するのに必要な条件１２、Ｉ Ｘ Ｔｉ
、１（／Ｍｎ≧１．０を十分確保する必要がある。Ti is a main element that improves strength without impairing workability in the present invention. That is, if Ti is solutionized before hot rolling, it will finely precipitate as TiC after hot rolling and improve the strength. Furthermore, Ti combines with S in the steel to become TiS, which is difficult to deform during hot rolling, eliminating inclusions stretched in the rolling direction, and significantly improving bending workability along the rolling direction. Therefore, Ti is oxygen (0),
Condition 12, I
, 1(/Mn≧1.0).
Ｔｉ含有量が０．０６０％以下であると引張強さ６０
ｋｇｆ／ｍｍ’以上が確保できないのでその下限を０．
０６０％とした。また、Ｔｉ含有量が０．２０％を超え
ると現状の加熱条件では有効に強度が上昇しないので、
上限を０．２０％とした。When the Ti content is 0.060% or less, the tensile strength is 60%.
Since it is not possible to secure more than kgf/mm', the lower limit is set to 0.
060%. Furthermore, if the Ti content exceeds 0.20%, the strength will not increase effectively under the current heating conditions.
The upper limit was set at 0.20%.
また、強度上昇に有効に働く微細なＴｉｃを熱間圧延後
に析出させるために、加熱圧延条件を以下のように限定
した。In addition, in order to precipitate fine Tic that effectively increases the strength after hot rolling, the hot rolling conditions were limited as follows.
再加熱圧延の場合は連続鋳造後の冷却課程でＴｉＣが析
出しているので、再加熱時に溶体化する必要がある。溶
体化に必要な再加熱温度は下限が１１８０℃である。In the case of reheat rolling, since TiC precipitates during the cooling process after continuous casting, it is necessary to dissolve it during reheating. The lower limit of the reheating temperature required for solutionization is 1180°C.
熱間圧延温度は強度に影響する重要な条件である。Ａｒ
３変態点以上でも８８０℃以下では引張強さが低下して
いる。これは、圧延温度が低いと熱間圧延中にＴｉＣが
析出してしまい、引張強さ向上に有効に働かないためで
ある。そこで、熱間圧延温度の下限を８８０℃とした。Hot rolling temperature is an important condition that affects strength. Ar
Even at 3 transformation points or higher, the tensile strength decreases below 880°C. This is because if the rolling temperature is low, TiC will precipitate during hot rolling and will not work effectively to improve the tensile strength. Therefore, the lower limit of the hot rolling temperature was set to 880°C.
しかし、熱間圧延温度が高すぎるとスケールの発生が多
くなり表面性状を害するので上限を９５０℃とした。However, if the hot rolling temperature is too high, scale will increase and the surface quality will be impaired, so the upper limit was set at 950°C.
巻取温度は高すぎるとＴｉｃが粗大化し強度向上に有効
に働かないので、上限を６５０℃とした。If the winding temperature is too high, the Tic will become coarse and will not work effectively to improve the strength, so the upper limit was set at 650°C.
上記のようにＰ、Ｃｕ、Ｃｒ 添加で安定績を形成して
耐候性を向上させ、かつ、Ｔｉにより硫化物を制御して
冷間曲げ加工性を向上させると同時にＴｉｃが微細析出
するよう熱延条件を制御して強度を向上させた、高強度
耐候性熱延鋼板が製造できる。As mentioned above, the addition of P, Cu, and Cr improves weather resistance by forming a stable structure, and Ti controls sulfides and improves cold bending workability. High-strength, weather-resistant hot-rolled steel sheets with improved strength can be produced by controlling rolling conditions.
［実 施 例］
第１表は供試材の化学成分、加熱温度と引張強さ、曲げ
性を示す。[Example] Table 1 shows the chemical composition, heating temperature, tensile strength, and bendability of the test materials.
試験番号１番から９番は本発明例を示し、試験番号１０
番から１８番は比較例を示す。Test numbers 1 to 9 indicate examples of the present invention, and test number 10
Numbers 1 to 18 show comparative examples.
試験番号１番〜２番および８番〜９番はＴｉを０．０７
〜０．０９％添加した６ ０ ｋｇｆ／ｍｍ”級、試験
番。Test numbers 1 to 2 and 8 to 9 have Ti of 0.07.
60 kgf/mm'' class with ~0.09% addition, test number.
号３番〜４番はＴｉを０．０９〜０．１２％添加した７
０ｋｇｆ／ｍｍ２級、試験番号５番〜７番はＴｉを０．
１５〜０．１７％添加した８ ０ ｋｇｆ／ｍｍ２級の
耐候性熱延鋼板である。これらはいずれも加熱温度が１
２８０℃でＴＩＣは十分固溶している。また、試験番号
１０番〜１３番は比較例で化学成分は試験番号２番から
５番までと同じであるが加熱温度が１１００℃と低かっ
た場合で、強度が６０ ｋｇｆ／ｍｍ２を満足していな
い。また、試験番号１４番は巻取温度が７００℃と高く
、試験番号１５番〜１６番は熱延仕上温度が８００℃と
低いため強度が６０ ｋｇｆ／ｍｍ２を満足していない
。つぎに、試験番号１７番〜１８番は比較例でＴｉ添加
量が少なく曲げ加工性を満足していない鋼である。Nos. 3 and 4 are 7 containing 0.09 to 0.12% Ti.
0kgf/mm2 class, test numbers 5 to 7 have Ti of 0.
It is an 80 kgf/mm2 grade weather-resistant hot-rolled steel sheet containing 15 to 0.17% additive. All of these have a heating temperature of 1
At 280°C, TIC is sufficiently dissolved in solid solution. In addition, test numbers 10 to 13 are comparative examples, and the chemical composition is the same as test numbers 2 to 5, but the heating temperature was as low as 1100℃, and the strength satisfied 60 kgf/mm2. do not have. Further, test number 14 has a high winding temperature of 700°C, and test numbers 15 and 16 have a low hot rolling finishing temperature of 800°C, so the strength does not satisfy 60 kgf/mm2. Next, test numbers 17 and 18 are comparative examples, and the steels have a small amount of Ti added and do not satisfy bending workability.
［発明の効果］
引張強さ６０ ｋｇｆ／ｍｍ’以上でしかも冷間曲げ加
工性の良い耐候性熱延鋼板が製造されることにより軽量
な鉄道車輌およびコンテナー用の素材が提供できる。[Effects of the Invention] By producing a weather-resistant hot-rolled steel sheet having a tensile strength of 60 kgf/mm' or more and good cold bending workability, a lightweight material for railway vehicles and containers can be provided.
第１図（ａ） 、 （ｂ）は耐候性鋼と普通鋼の錆層の
模式図、第２図は１２．］ＸＴｆ ｓｒｒ／Ｍ口と限界
曲げ半径／板厚との関係を示す図、第３図は加熱温度、
Ｔｉ添加量と引張強さの関係を示す図、第４図は圧延仕
上温度、巻取温度と引張強さの関係を示す図である。
Ｃ・・・クラック
限界曲げ半径／板厚Figures 1 (a) and (b) are schematic diagrams of rust layers on weathering steel and ordinary steel, and Figure 2 is 12. ] A diagram showing the relationship between XTf srr/M port and limit bending radius/plate thickness, Figure 3 shows the heating temperature,
FIG. 4 is a diagram showing the relationship between Ti addition amount and tensile strength, and FIG. 4 is a diagram showing the relationship between rolling finishing temperature, coiling temperature, and tensile strength. C...Crack limit bending radius/plate thickness
Claims (1)
０（ここで、Ｔｉ＿ｅ＿ｆ＿ｆ（％）＝Ｔｉ（％）−３
．４×Ｎ（％）−１．５×Ｏ（％））、 残部不可避的成分および鉄を含有した鋳片 を連続鋳造で製造し、１１８０℃以上に再加熱後熱間圧
延し、熱間圧延温度を８８０〜９５０℃とし、巻取温度
を６５０℃以下とすることにより、引張強さ６０ｋｇｆ
／ｍｍ＾２以上で冷間加工性の良い耐候性熱延鋼板を得
ることを特徴とする高強度耐候性熱延鋼板の製造方法。[Claims] 1 C: 0.02-0.12%, Si≦0.50%, Mn: 0.10-2.00%, P: 0.070-0.150%, S≦0 .020%. Al: 0.010-0.050%, Cu: 0.25-0.55%, Cr: 0.30-1.25%, N≦0.0060%, Ti: 0.06-0.20% and 12.1×Ti_e_f_f(%)/Mn(%)≧1.
0 (here, Ti_e_f_f(%)=Ti(%)-3
．． 4 × N (%) - 1.5 × O (%)), the balance containing unavoidable components and iron is produced by continuous casting, reheated to 1180 ° C or higher, hot rolled, and hot rolled. By setting the temperature to 880 to 950°C and the winding temperature to 650°C or less, the tensile strength is 60 kgf.
1. A method for producing a high-strength weather-resistant hot-rolled steel sheet, which is characterized by obtaining a weather-resistant hot-rolled steel sheet with good cold workability at /mm^2 or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1136625A JPH06104858B2 (en) | 1989-05-30 | 1989-05-30 | Method for producing high strength weather resistant hot rolled steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1136625A JPH06104858B2 (en) | 1989-05-30 | 1989-05-30 | Method for producing high strength weather resistant hot rolled steel sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH032321A true JPH032321A (en) | 1991-01-08 |
| JPH06104858B2 JPH06104858B2 (en) | 1994-12-21 |
Family
ID=15179679
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1136625A Expired - Fee Related JPH06104858B2 (en) | 1989-05-30 | 1989-05-30 | Method for producing high strength weather resistant hot rolled steel sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06104858B2 (en) |
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|---|---|---|---|---|
| KR20020040213A (en) * | 2000-11-24 | 2002-05-30 | 이구택 | A METHOD FOR MANUFACTURING HOT ROLLED STEEL SHEET OF TENSILE STRENGTH 80kg/㎟ GRADE WITH EXCELLENT WEATHER RESISTANCE AND WORKABILITY |
| WO2003072841A1 (en) * | 2002-02-27 | 2003-09-04 | Nippon Steel Corporation | Atmosphere corrosion resisting steel plate having high strength and excellent bending formability and method for production thereof |
| WO2020169077A1 (en) * | 2019-02-21 | 2020-08-27 | 江苏沙钢集团有限公司 | Low-cost weathering steel and production method thereof |
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1989
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20020040213A (en) * | 2000-11-24 | 2002-05-30 | 이구택 | A METHOD FOR MANUFACTURING HOT ROLLED STEEL SHEET OF TENSILE STRENGTH 80kg/㎟ GRADE WITH EXCELLENT WEATHER RESISTANCE AND WORKABILITY |
| WO2003072841A1 (en) * | 2002-02-27 | 2003-09-04 | Nippon Steel Corporation | Atmosphere corrosion resisting steel plate having high strength and excellent bending formability and method for production thereof |
| WO2020169077A1 (en) * | 2019-02-21 | 2020-08-27 | 江苏沙钢集团有限公司 | Low-cost weathering steel and production method thereof |
| CN111850396A (en) * | 2020-07-02 | 2020-10-30 | 武汉科技大学 | Economical bainite weathering steel for container and CSP (cast steel plate) line production method |
| CN112063920A (en) * | 2020-08-06 | 2020-12-11 | 湖南华菱涟钢薄板有限公司 | Thin container plate and preparation method thereof |
| CN112063920B (en) * | 2020-08-06 | 2021-12-24 | 湖南华菱涟钢特种新材料有限公司 | Thin container plate and preparation method thereof |
| CN114438409A (en) * | 2022-01-07 | 2022-05-06 | 日照钢铁控股集团有限公司 | Seawater corrosion resistant high-strength steel and preparation process thereof |
| CN115386801A (en) * | 2022-08-30 | 2022-11-25 | 马鞍山钢铁股份有限公司 | 400 MPa-grade Ni-free hot-rolled weather-resistant steel plate and production method thereof |
| CN116005069A (en) * | 2022-12-22 | 2023-04-25 | 武汉钢铁有限公司 | High-weather-resistance hot-rolled rod wire and rolling process thereof |
| CN116005069B (en) * | 2022-12-22 | 2024-05-10 | 武汉钢铁有限公司 | High-weather-resistance hot-rolled rod wire and rolling process thereof |
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| Publication number | Publication date |
|---|---|
| JPH06104858B2 (en) | 1994-12-21 |
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