JPH0453938B2 - - Google Patents
Info
- Publication number
- JPH0453938B2 JPH0453938B2 JP60167141A JP16714185A JPH0453938B2 JP H0453938 B2 JPH0453938 B2 JP H0453938B2 JP 60167141 A JP60167141 A JP 60167141A JP 16714185 A JP16714185 A JP 16714185A JP H0453938 B2 JPH0453938 B2 JP H0453938B2
- Authority
- JP
- Japan
- Prior art keywords
- rolled steel
- content
- steel plate
- clamps
- strength hot
- 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.)
- Expired - Lifetime
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 44
- 239000010959 steel Substances 0.000 claims description 44
- 229910001563 bainite Inorganic materials 0.000 claims description 16
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 12
- 229910001568 polygonal ferrite Inorganic materials 0.000 claims description 11
- 239000012535 impurity Substances 0.000 claims description 10
- 229910052742 iron Inorganic materials 0.000 claims description 9
- 150000002910 rare earth metals Chemical class 0.000 claims description 9
- 230000007797 corrosion Effects 0.000 description 11
- 238000005260 corrosion Methods 0.000 description 11
- 238000001816 cooling Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 9
- 238000005452 bending Methods 0.000 description 8
- 229910000859 α-Fe Inorganic materials 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- LRXTYHSAJDENHV-UHFFFAOYSA-H zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 description 4
- 229910000165 zinc phosphate Inorganic materials 0.000 description 4
- 241000219307 Atriplex rosea Species 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910000398 iron phosphate Inorganic materials 0.000 description 2
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
Landscapes
- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Steel (AREA)
Description
［産業上の利用分野］
本発明はクランプ用高強度熱間圧延鋼板に関
し、さらに詳しくは、表面性状および加工性の優
れたクランプ用高強度熱間圧延鋼板に関する。
［従来技術］
最近になつて、建築足場用クランプ等各種構造
物を軽量化するために高強度熱間圧延鋼板を使用
することが検討されてきており、即ち、引張強さ
が40Kgｆ／mm2以下の鋼板に代えて、引張強さが50
Kgｆ／mm2以上の高強度熱間圧延鋼板を使用するこ
とが検討されてきている。
そして、このような引張強さが50Kgｆ／mm2以上
の高強度熱間圧延鋼板にも、引張強さが40Kgｆ／
mm2である鋼板と同様な延性およびその他の特性を
具備することが望まれているが、従来の50Kgｆ／
mm2以上の高強度熱間圧延鋼板では、高強度化にな
ると共に延性は劣化するため、クランプの成形加
工時の曲げ応力に耐えられず、また、種々の含有
元素の含有量が増加すると表面性状および耐蝕性
が劣化する。
［発明が解決しようとする問題点］
本発明は上記に説明したように、引張強さが高
くなることによる従来の高強度熱間圧延鋼板の特
性が劣化することに鑑み、本発明者が鋭意研究を
行なつた結果、引張強さが50Kgｆ／mm2以上の高強
度熱間圧延鋼板であつても、各種の特性、例え
ば、延性、表面性状および耐蝕性を劣化させない
ようにするため、特に、伸びフランジ性に代表さ
れるような局部延性に対してフエライト−ベイナ
イト組織とすることおよび表面性状についてはSi
含有量を抑制することを見出し、表面性状や加工
性が優れているクランプ用高強度熱間圧延鋼板を
開発したのである。
［問題点を解決するための手段］
本発明に係るクランプ用高強度熱間圧延鋼板
は、
(1) C0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8
〜1.8wt％、S0.01wt％以下、Al0.01〜0.08wt％
を含有し、残部Feおよび不純物からなり、か
つ、ポリゴナルフエライト95〜40％およびベイ
ナイト５〜60％の面積比率であることを特徴と
するクランプ用高強度熱間圧延鋼板を第１の発
明とし、
(2) C0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8
〜1.8wt％、S0.01wt％以下、Al0.01〜0.08wt％
を含有し、また、
Nb0.01〜0.06wt％、Ti0.03〜0.1wt％の１種
または２種
を含有し、残部Feおよび不純物からなり、か
つ、ポリゴナルフエライト95〜40％およびベイ
ナイト５〜60％の面積比率であることを特徴と
するクランプ用高強度熱間圧延鋼板を第２の発
明とし、
(3) C0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8
〜1.8wt％、S0.01wt％以下、Al0.01〜0.08wt％
を含有し、また、
Ca0.0005〜0.01wt％、レア・アース・メタル
0.005〜0.1wt％の１種または２種
を含有し、残部Feおよび不純物からなり、か
つ、ポリゴナルフエライト95〜40％およびベイ
ナイト５〜60％の面積比率であることを特徴と
するクランプ用高強度熱間圧延鋼板を第３の発
明とし、
(4) C0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8
〜1.8wt％、S0.01wt％以下、Al0.01〜0.08wt％
を含有し、また、
Nb0.01〜0.06wt％、Ti0.03〜0.1wt％１種ま
たは２種
を含有し、さらに、
Ca0.0005〜0.01wt％、レア・アース・メタル
0.005〜0.1wt％の１種または２種
を含有し、残部Feおよび不純物からなり、か
つ、ポリゴナルフエライト95〜40％およびベイ
ナイト５〜60％の面積比率であることを特徴と
するクランプ用高強度熱間圧延鋼板を第４の発
明とし、
(5) 0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8〜
1.8wt％、S0.01wt％、Al0.01〜0.08wt％
を含有し、また、
Nb0.01〜0.06wt％、Ti0.03〜0.1wt％の１種
または２種
を含有し、さらに、
Ca0.0005〜0.01wt％、レア・アース・メタル
0.005〜0.1wt％の１種または２種
を含有し、および、
Cr0.1〜0.4wt％
を含有し、残部Feおよび不純物からなり、か
つ、ポリゴナルフエライト95〜40％およびベイ
ナイト５〜60％の面積比率であることを特徴と
するクランプ用高強度熱間圧延鋼板を第５の発
明とする５つの発明よりなるものである。
本発明に係るクランプ用高強度熱間圧延鋼板に
ついて以下詳細に説明する。
先ず、本発明に係るクランプ用高強度熱間圧延
鋼板の含有成分および含有割合について説明す
る。
Ｃは鋼の強化および焼入れ性向上に寄与する元
素であり、含有量が0.05wt％未満ではこのような
効果は少なく、また、0.2wt％を越えると溶接性
が悪くなり、特に、溶接が行なわれる部材に適用
すよ場合には溶接強度の信頼性が低下する。よつ
て、Ｃ含有量は0.05〜0.2wt％とする。
Siは含有量が低い程表面性状、耐蝕性は向上す
るが、Si含有量を0.01wt％未満まで減少しても効
果に著しい向上がなく、逆に製造費用が上昇し、
また、表面性状が厳しく要求される場合、或い
は、耐蝕性を充分に確保しなければならない場合
に、Si含有量を0.05wt％以下に抑制する必要があ
る。よつて、Si含有量は0.01〜0.05wt％とする。
しかして、熱間圧延鋼板の表面はSi含有量の増
加と共に縞状のスケールが生成し、酸洗後もその
痕跡が残り外観状問題となることが知られてお
り、種々の解決法が提案されており、また、ホイ
ールリムのようにロールフオーミングにより製造
されるものでは、ロールフオーミング過程で表面
がこすられて殆んど目立たなくなるという製造さ
れるものによつては問題とならない場合もある。
しかしながら、プレス成形で部品が作製されて、
その上にクロメート処理のような白色系の塗装が
施こされる場合には、酸洗状態における表面状況
がより強調された状態となり、素板で全くスケー
ル模様のないように仕上げることが必須となり、
Siが0.1wt％以上含有されるといままでの低温加
熱法、デスケール水圧、デスケーリング時のスラ
ブ温度或いはタイミングの調整等のいかなる方法
によつても100％問題にならない鋼板表面を得る
ことは第３図の斜線で示すSi含有量が0.05wt％以
下でないところでは不可能である。また、Si含有
量を0.05wt％以下に抑制されると必要最小限の工
程管理を行なうだけで略100％赤スケール発生が
抑制されることは第３図に示すように明らかであ
る。いままでは、Siの含有は強度−全伸びの関係
を向上させるのに必要な含有成分とされていた
が、Siを0.05wt％以下としても後述するようにフ
エライト面積率を40〜95％に制御することにより
問題とならない水準にまで強度と全伸びの関係を
改善することができ、さらに、伸びフランジ性や
側曲げ性等実用上ネツクとなる局部延性に対して
はSi含有量の影響は殆んどないから、完全な表面
性状と実用上問題とならない延性の両者を兼ね備
えさせるためには、Si含有量を0.05wt％以下に抑
制することが必要である。
さらに、Si含有量は耐蝕性にも大きな影響を与
えるものであり、プレス成形された部品は化成処
理され、その上にクロームメツキ等が施される
が、部品の耐蝕性は化成処理材の塩水噴霧試験後
のクロスカツト膨れ幅により評価され、第４図に
示すように、燐酸鉄、スプレータイプの燐酸亜
鉛、デイツプタイプの燐酸亜鉛の３種の化成処理
法を実施し、480時間塩水噴霧試験後のテープ剥
離幅を測定した。その結果は、燐酸鉄、スプレー
タイプ燐酸亜鉛およびデイツプタイプ燐酸亜鉛の
順に膨れ幅が小さくなり、耐蝕性が向上するが同
時にSi含有量が第４図斜線の0.05wt％以下におい
て著しく向上しており、このことからも、Si含有
量は0.05wt％以下に抑制するのが耐蝕性の向上に
も重要である。
Mnは焼入れ性を向上させるためと第２相をベ
イナイトとするための必須の元素であり、含有量
が0.8wt％未満ではパーライトが生成し易くなり
所望の組織が得られず、また、1.8wt％を越える
と組織が層状となり圧延直角方向の延性が劣化す
るようになる。よつて、Mn含有量は0.8〜1.8wt
％とする。
ＳはMnS系介在物を増加させて、伸ぴフラン
ジ性の劣化を招来するので、含有量は0.01wt％以
下に抑制する必要があり、Ｓ含有量が低い程局部
延性には好ましいが、実用上は0.05wt％以下であ
れば問題はないけれども、Ca、レア・アース・
メタル（REM）を含有することにより無害化す
ることができるので、含有量は0.01wt％以下とす
る。
Alは脱酸剤として使用され、その含有量は0.01
〜0.08wt％の範囲とする
Nb、Tiは析出強化元素として強度向上に補助
的な効果を付与すると共に圧延中のオーステナイ
トの再結晶を抑制し、フエライト粒を微細化し、
局部延性を高めるのに有効な元素であり、これら
の効果を発揮させるためには、Nb含有量は0.01
〜0.06wt％、Ti含有量は0.03〜0.1wt％とする。
Ca、レア・アース・メタル（REM）は硫化物
の形状制御効果により介在物を無害化し、局部延
性を高める効果があり、この効果を発揮させるた
めには、Ca含有量は0.0005〜0.01wt％、レア・ア
ース・メタル（REM）は0.005〜0.1wt％とする。
CrはMnと同様に焼入れ性を高める元素であ
り、含有量が0.1wt％未満ではこの効果が期待で
きず、また、0.4wt％を越えるとマルテンサイト
が生成し、伸びフランジ性、側曲げ性の著しい劣
化を招く。よつて、Cr含有量は0.1〜0.4wt％とす
る
次に、ポリゴナルフエライト95〜40％およびベ
イナイト５〜60％の面積比率について説明する。
熱間圧延鋼板をプレス成形する上で要求される
特性は、全伸びと共に伸びフランジ性やシヤー端
面の曲げ、ねじり等の局部延性であり、この局部
延性を評価するために、第１図に示すように10mm
φの打抜き穴を60゜円錐ポンチにより押し拡げる
穴拡げ試験および第２図ａのシヤー面Ｓを第２図
ｂのように半径Ｒのように側曲げ試験を行なつた
結果を第２図ｃに示す。供試材はフエライト−ベ
イナイト組織鋼｛Ｆ−Ｂ、第１図、第２図ｃ●で
示す。｝、フエライト−マルテンサイト組織鋼｛Ｆ
−Ｍ、第１図、第２図ｃ△｝およびフエライト−
パーライト組織鋼｛Ｆ−Ｐ、第１図、第２図ｃ
○｝の３種の組織を有する鋼である。第２図ｃよ
りTSが増加するとＲが大きくなるが、ミクロ組
織の影響を顕著に受ける。即ち、同一強度で比較
すると、Ｆ−Ｂ、Ｆ−Ｐ、Ｆ−Ｍ組織の順に著し
く劣化し、穴拡げ、シヤー端面の曲げを受ける成
形が多い部材、例えば、建築足場用クランプや自
動車のバンパー等に高強度熱間圧延鋼板を適用す
る際には、フエライト−ベイナイト組織に制御す
ることが必須条件である。さらに、強度と全伸び
との関係は伸びフランジ性或いは側曲げ性程組織
の影響を受けないが、フエライトの面積率が40％
以下になると全伸びの劣化が著しくなり、例え
ば、フエライト面積率が75〜80％の鋼板ではTS
×Elは1800以上であるが、フエライト面積率が30
％或いは20％の鋼板では、板ではTS×Elは1632、
1539と低下している。これらの説明から、強度−
全伸びの関係を高水準に維持するためには、フエ
ライト面積率は95〜40％としなければならない。
従つて、ベイナイト５〜60％である。
［実施例］
本発明に係る高強度熱間圧延鋼板の実施例を説
明する。
実施例 １
第１表に示す含有成分および成分割合の鋼を溶
製して鋳造し、この鋳塊を830〜930℃の温度の仕
上温度で熱間圧延し、2.9mm厚の熱間圧延鋼板を
製作し、その後、各種の冷却、巻取り状件により
鋼板を製造した。
この場合、フエライト−パーライト（Ｆ−Ｐ）
組織を得るには、巻取り温度を650℃、フエライ
ト−ベイナイト（Ｆ−Ｂ）組織を得るには、巻取
り温度450〜550℃、フエライト−マルテンサイト
（Ｆ−Ｍ）組織を得るには、巻取り温度250℃以下
とした。
熱間圧延終了後巻取りに至るまでの冷却パター
ンは、30〜50℃／secの平均冷却速度で一様に冷
却する場合、700℃前後で約５℃／secの冷却速度
で３〜15secの徐冷を行ない、その前後を30〜50
℃／secの平均冷却速度で冷却するステツプパタ
ーンの２種類の冷却パターンを実施した。
第２表に組織、機械的性質、側曲げ、表面性
状、耐蝕性について示す。
実施例 ２
第１表に示すSi含有量の異なるNo.４、11、12、
13、14の鋼を、1150℃の温度に加熱後通常の工程
により熱間圧延鋼板を製造した。
各鋼種３本を圧延して赤スケール発生率を求め
た。さらに、これらの鋼板に各種の化成処理を施
し、480時間の塩水噴霧悟のクロスカツト膨れ幅
を調査し、結果を第２表に示す。
この第２表から明らかなように、本発明に係る
高強度熱間圧延鋼板は、比較鋼に比し、表面性
状、側曲げ、機械的性質において優れ、さらに、
耐蝕性も優れていることがわかる。
[Industrial Application Field] The present invention relates to a high-strength hot-rolled steel plate for clamps, and more particularly to a high-strength hot-rolled steel plate for clamps with excellent surface texture and workability. [Prior Art] Recently, in order to reduce the weight of various structures such as clamps for construction scaffolding, the use of high-strength hot-rolled steel plates has been considered . Instead of the steel plate below, the tensile strength is 50
The use of high-strength hot-rolled steel sheets with a strength of Kgf/mm 2 or more has been considered. In addition, even high-strength hot-rolled steel sheets with a tensile strength of 50 Kgf/mm 2 or more have a tensile strength of 40 Kgf/mm 2 or more.
Although it is desired to have ductility and other properties similar to steel sheets that are 50Kgf/ mm2 ,
In high-strength hot-rolled steel sheets with a diameter of mm 2 or more, as the strength increases, the ductility deteriorates, making it difficult to withstand the bending stress during clamp forming, and as the content of various elements increases, the surface Properties and corrosion resistance deteriorate. [Problems to be Solved by the Invention] As explained above, the present inventor has made efforts to solve the problem in view of the deterioration of the properties of conventional high-strength hot rolled steel sheets due to the increase in tensile strength. As a result of our research, we have found that even with high-strength hot-rolled steel sheets with a tensile strength of 50 Kgf/mm2 or higher , in order to prevent deterioration of various properties, such as ductility, surface texture, and corrosion resistance, we have found that , Si
They discovered that the content could be suppressed and developed a high-strength hot-rolled steel plate for clamps that has excellent surface texture and workability. [Means for solving the problems] The high-strength hot-rolled steel plate for clamps according to the present invention includes: (1) C0.05-0.2wt%, Si0.01-0.05wt%, Mn0.8
~1.8wt%, S 0.01wt% or less, Al 0.01~0.08wt%, the balance consisting of Fe and impurities, and an area ratio of 95~40% polygonal ferrite and 5~60% bainite. The first invention is a high-strength hot-rolled steel plate for clamps characterized by: (2) C0.05-0.2wt%, Si0.01-0.05wt%, Mn0.8
~1.8wt%, S0.01wt% or less, Al0.01~0.08wt%, and also contains one or two of Nb0.01~0.06wt%, Ti0.03~0.1wt%, and the remainder A second invention provides a high-strength hot-rolled steel plate for clamps comprising Fe and impurities and having an area ratio of 95-40% polygonal ferrite and 5-60% bainite, (3) C0 .05~0.2wt%, Si0.01~0.05wt%, Mn0.8
Contains ~1.8wt%, S0.01wt% or less, Al0.01~0.08wt%, and Ca0.0005~0.01wt%, rare earth metal.
A height for clamps containing 0.005 to 0.1 wt% of one or two types, the remainder consisting of Fe and impurities, and having an area ratio of 95 to 40% polygonal ferrite and 5 to 60% bainite. The third invention is a high-strength hot-rolled steel plate, (4) C0.05-0.2wt%, Si0.01-0.05wt%, Mn0.8
Contains ~1.8wt%, S0.01wt% or less, Al0.01~0.08wt%, and also contains one or two types of Nb0.01~0.06wt%, Ti0.03~0.1wt%, and further, Ca0.0005~0.01wt%, rare earth metal
A height for clamps containing 0.005 to 0.1 wt% of one or two types, the remainder consisting of Fe and impurities, and having an area ratio of 95 to 40% polygonal ferrite and 5 to 60% bainite. A fourth invention provides a high-strength hot-rolled steel plate, (5) 0.05-0.2wt%, Si0.01-0.05wt%, Mn0.8-
Contains 1.8wt%, S0.01wt%, Al0.01~0.08wt%, and also contains one or two of Nb0.01~0.06wt%, Ti0.03~0.1wt%, and Ca0 .0005~0.01wt%, rare earth metal
Contains 0.005 to 0.1 wt% of one or two types, and 0.1 to 0.4 wt% of Cr, with the balance consisting of Fe and impurities, and 95 to 40% of polygonal ferrite and 5 to 60% of bainite. The fifth invention is a high-strength hot-rolled steel plate for clamps characterized by an area ratio of . The high-strength hot-rolled steel plate for clamps according to the present invention will be described in detail below. First, the components and content ratios of the high-strength hot-rolled steel plate for clamps according to the present invention will be explained. C is an element that contributes to strengthening steel and improving hardenability, and if the content is less than 0.05wt%, this effect will be small, and if it exceeds 0.2wt%, weldability will deteriorate, especially when welding is performed. If it is applied to parts that will be welded, the reliability of the welding strength will decrease. Therefore, the C content is set to 0.05 to 0.2 wt%. The lower the Si content, the better the surface quality and corrosion resistance, but even if the Si content is reduced to less than 0.01wt%, there is no significant improvement in effectiveness, and on the contrary, manufacturing costs increase.
Furthermore, when the surface properties are strictly required or when sufficient corrosion resistance must be ensured, it is necessary to suppress the Si content to 0.05 wt% or less. Therefore, the Si content is set to 0.01 to 0.05 wt%. However, it is known that striped scales are formed on the surface of hot rolled steel sheets as the Si content increases, and traces of these scales remain even after pickling, causing problems in appearance. Various solutions have been proposed. In addition, for items manufactured by roll forming, such as wheel rims, the surface may be rubbed during the roll forming process and become hardly noticeable, which may not be a problem depending on the item being manufactured. be.
However, parts are made by press molding,
If a white paint such as chromate treatment is applied on top of it, the surface condition in the pickling state will be more emphasized, and it is essential to finish the bare board without any scale patterns. ,
When Si is contained at 0.1wt% or more, it is impossible to obtain a 100% problem-free steel plate surface using any method such as conventional low-temperature heating, descaling water pressure, or adjusting the slab temperature or timing during descaling. This is not possible in areas where the Si content shown by diagonal lines in Figure 3 is less than 0.05wt%. Furthermore, as shown in FIG. 3, it is clear that when the Si content is suppressed to 0.05 wt% or less, the generation of red scale can be suppressed by approximately 100% with only the minimum necessary process control. Until now, the inclusion of Si was considered to be a necessary component to improve the relationship between strength and total elongation, but even if Si is 0.05wt% or less, the area ratio of ferrite can be increased to 40 to 95%, as described below. By controlling the relationship between strength and total elongation, it is possible to improve the relationship between strength and total elongation to a level that does not pose a problem.Furthermore, the influence of Si content on local ductility, which is a practical problem such as stretch flangeability and side bendability, can be improved. Since there is almost no Si content, it is necessary to suppress the Si content to 0.05 wt% or less in order to have both perfect surface texture and ductility that does not pose a problem in practice. Furthermore, the Si content has a large effect on corrosion resistance, and press-formed parts are chemically treated and chrome plating is applied on top of it, but the corrosion resistance of parts is affected by the salt water of the chemically treated material. As shown in Figure 4, three types of chemical conversion treatment methods were carried out: iron phosphate, spray type zinc phosphate, and dip type zinc phosphate. The tape peeling width was measured. The results show that the blistering width decreases in the order of iron phosphate, spray type zinc phosphate, and dip type zinc phosphate, and corrosion resistance improves, but at the same time, the Si content significantly improves below 0.05 wt% as shown by the diagonal line in Figure 4. For this reason, it is also important to suppress the Si content to 0.05 wt% or less in order to improve corrosion resistance. Mn is an essential element for improving hardenability and making the second phase bainite. If the content is less than 0.8wt%, pearlite tends to form and the desired structure cannot be obtained; %, the structure becomes layered and the ductility in the direction perpendicular to the rolling direction deteriorates. Therefore, the Mn content is 0.8~1.8wt
%. S increases MnS-based inclusions and causes deterioration of stretch flangeability, so the content must be suppressed to 0.01wt% or less. A lower S content is better for local ductility, but it is not suitable for practical use. There is no problem with the above as long as it is below 0.05wt%, but Ca, rare earth,
Since the metal (REM) can be rendered harmless by containing it, the content should be 0.01wt% or less. Al is used as a deoxidizer, and its content is 0.01
In the range of ~0.08wt% Nb and Ti have an auxiliary effect on improving strength as precipitation strengthening elements, and also suppress recrystallization of austenite during rolling, making ferrite grains finer,
It is an effective element for increasing local ductility, and in order to exhibit these effects, the Nb content must be 0.01
~0.06wt%, and the Ti content is 0.03~0.1wt%. Ca, a rare earth metal (REM), has the effect of making inclusions harmless and increasing local ductility due to the shape control effect of sulfide. , rare earth metals (REM) should be 0.005 to 0.1wt%. Cr, like Mn, is an element that improves hardenability, and if the content is less than 0.1wt%, this effect cannot be expected, and if it exceeds 0.4wt%, martensite will be formed, resulting in poor stretch flangeability and side bendability. leading to significant deterioration of Therefore, the Cr content is set to 0.1 to 0.4 wt%.Next, the area ratios of 95 to 40% polygonal ferrite and 5 to 60% of bainite will be explained. The properties required for press forming hot-rolled steel sheets are total elongation as well as local ductility such as stretch flangeability and bending and torsion of the shear end face. like 10mm
Figure 2c shows the results of a hole expansion test in which a punched hole of φ is expanded by pushing it open with a 60° conical punch, and a side bending test of the shear surface S in Figure 2a to have a radius R as in Figure 2b. Shown below. The test material is a ferrite-bainite structural steel {F-B, shown in Figs. 1 and 2 c●. }, ferrite-martensitic steel {F
-M, Fig. 1, Fig. 2 c△} and ferrite-
Pearlitic structure steel {F-P, Fig. 1, Fig. 2 c
It is a steel that has three types of structures: ○}. As shown in Fig. 2c, as TS increases, R increases, but it is significantly influenced by the microstructure. In other words, when comparing the same strength, the F-B, F-P, and F-M structures deteriorate significantly in the order of order, and members that are often subjected to hole expansion and bending of the shear end face, such as construction scaffolding clamps and automobile bumpers. When applying high-strength hot-rolled steel sheets to, etc., it is essential to control the structure to a ferrite-bainite structure. Furthermore, the relationship between strength and total elongation is not affected by the structure as much as stretch flangeability or side bendability, but when the area ratio of ferrite is 40%
Below this, the total elongation deteriorates significantly.For example, in a steel plate with a ferrite area ratio of 75 to 80%, the TS
×El is 1800 or more, but the ferrite area ratio is 30
% or 20% steel plate, TS×El is 1632,
It has decreased to 1539. From these explanations, the strength −
In order to maintain a high level of total elongation relationship, the ferrite area fraction must be between 95 and 40%.
Therefore, the bainite content is 5 to 60%. [Example] An example of a high-strength hot rolled steel plate according to the present invention will be described. Example 1 Steel having the components and ratios shown in Table 1 was melted and cast, and the ingot was hot rolled at a finishing temperature of 830 to 930°C to produce a 2.9 mm thick hot rolled steel plate. After that, steel plates were manufactured using various cooling and winding conditions. In this case, ferrite-pearlite (F-P)
To obtain a structure, the coiling temperature is 650°C. To obtain a ferrite-bainite (F-B) structure, the coiling temperature is 450 to 550°C. To obtain a ferrite-martensite (F-M) structure, The winding temperature was set to 250°C or less. The cooling pattern after hot rolling until winding is uniform cooling at an average cooling rate of 30 to 50°C/sec, and 3 to 15 seconds at a cooling rate of approximately 5°C/sec at around 700°C. Perform gradual cooling, then cool for 30 to 50 minutes before and after cooling.
Two types of cooling patterns were carried out: a step pattern in which the sample was cooled at an average cooling rate of °C/sec. Table 2 shows the structure, mechanical properties, side bending, surface texture, and corrosion resistance. Example 2 Nos. 4, 11, 12, with different Si contents shown in Table 1
After heating the steels Nos. 13 and 14 to a temperature of 1150°C, a hot-rolled steel plate was manufactured using a normal process. Three pieces of each steel type were rolled and the red scale occurrence rate was determined. Furthermore, these steel plates were subjected to various chemical conversion treatments, and the cross-cut bulge width after 480 hours of salt water spraying was investigated, and the results are shown in Table 2. As is clear from Table 2, the high-strength hot-rolled steel sheet according to the present invention is superior in surface texture, side bending, and mechanical properties compared to comparative steels, and furthermore,
It can be seen that the corrosion resistance is also excellent.
【表】【table】
【表】【table】
【表】
［発明の効果］
以上説明したように、本発明に係る高強度熱間
圧延鋼板は上記に説明したような構成であるか
ら、全伸びおよび伸びフランジ性、シヤー端面の
曲げ、ねじり等の局部延性に優れ、かつ、表面性
状にも優れ、さらに、耐蝕性にも優れているとい
う効果を有するものである。[Table] [Effects of the Invention] As explained above, the high-strength hot-rolled steel sheet according to the present invention has the above-described structure, so it has excellent properties such as total elongation, stretch flangeability, bending of shear end face, torsion, etc. It has the effects of excellent local ductility, excellent surface properties, and excellent corrosion resistance.
第１図はλにおよぼすT.S.と組織の影響を示す
図、第２図は側曲げ肩ＲにおよぼすT.S.と組織の
影響を示す図、第３図は赤スケール発生におよぼ
すSi含有量の影響を示す図、第４図は塩水噴霧ク
ロスカツト膨れ幅におよぼすSi含有量の影響を示
す図である。
Figure 1 shows the influence of TS and texture on λ, Figure 2 shows the influence of TS and texture on side bending shoulder R, and Figure 3 shows the influence of Si content on red scale generation. The figure shown in FIG. 4 is a diagram showing the influence of Si content on the blistering width of the salt water spray crosscut.
Claims (1)
〜1.8wt％、S0.01wt％以下、Al0.01〜0.08wt％ を含有し、残部Feおよび不純物からなり、かつ、
ポリゴナルフエライト95〜40％およびベイナイト
５〜60％の面積比率であることを特徴とするクラ
ンプ用高強度熱間圧延鋼板。 ２ C0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8
〜1.8wt％、S0.01wt％以下、Al0.01〜0.08wt％ を含有し、また、 Nb0.01〜0.06wt％、Ti0.03〜0.1wt％の１種ま
たは２種 を含有し、残部Feおよび不純物からなり、かつ、
ポリゴナルフエライト95〜40％およびベイナイト
５〜60％の面積比率であることを特徴とするクラ
ンプ用高強度熱間圧延鋼板。 ３ C0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8
〜1.8wt％、S0.01wt％以下、Al0.01〜0.08wt％ を含有し、また、 Ca0.0005〜0.01wt％、レア・アース・メタル
0.005〜0.1wt％の１種または２種 を含有し、残部Feおよび不純物からなり、かつ、
ポリゴナルフエライト95〜40％およびベイナイト
５〜60％の面積比率であることを特徴とするクラ
ンプ用高強度熱間圧延鋼板。 ４ C0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8
〜1.8wt％、S0.01wt％以下、Al0.01〜0.08wt％ を含有し、また、 Nb0.01〜0.06wt％、Ti0.03〜0.1wt％１種また
は２種 を含有し、さらに、 Ca0.0005〜0.01wt％、レア・アース・メタル
0.005〜0.1wt％の１種または２種 を含有し、残部Feおよび不純物からなり、かつ、
ポリゴナルフエライト95〜40％およびベイナイト
５〜60％の面積比率であることを特徴とするクラ
ンプ用高強度熱間圧延鋼板。 ５ C0.05〜0.2wt％、Si0.01〜0.05wt％、Mn0.8
〜1.8wt％、S0.01wt％、Al0.01〜0.08wt％ を含有し、また、 Nb0.01〜0.06wt％、Ti0.03〜0.1wt％の１種ま
たは２種 を含有し、さらに、 Ca0.0005〜0.01wt％、レア・アース・メタル
0.005〜0.1wt％の１種または２種 を含有し、および、 Cr0.1〜0.4wt％ を含有し、残部Feおよび不純物からなり、かつ、
ポリゴナルフエライト95〜40％およびベイナイト
５〜60％の面積比率であることを特徴とするクラ
ンプ用高強度熱間圧延鋼板。[Claims] 1 C0.05-0.2wt%, Si0.01-0.05wt%, Mn0.8
Contains ~1.8wt%, S0.01wt% or less, Al0.01~0.08wt%, and the balance consists of Fe and impurities, and
A high-strength hot-rolled steel plate for clamps, characterized by an area ratio of 95 to 40% polygonal ferrite and 5 to 60% bainite. 2 C0.05~0.2wt%, Si0.01~0.05wt%, Mn0.8
~1.8wt%, S0.01wt% or less, Al0.01~0.08wt%, and also contains one or two of Nb0.01~0.06wt%, Ti0.03~0.1wt%, and the remainder consisting of Fe and impurities, and
A high-strength hot-rolled steel plate for clamps, characterized by an area ratio of 95 to 40% polygonal ferrite and 5 to 60% bainite. 3 C0.05~0.2wt%, Si0.01~0.05wt%, Mn0.8
Contains ~1.8wt%, S0.01wt% or less, Al0.01~0.08wt%, and Ca0.0005~0.01wt%, rare earth metal.
Contains 0.005 to 0.1 wt% of one or two types, with the balance consisting of Fe and impurities, and
A high-strength hot-rolled steel plate for clamps, characterized by an area ratio of 95 to 40% polygonal ferrite and 5 to 60% bainite. 4 C0.05~0.2wt%, Si0.01~0.05wt%, Mn0.8
Contains ~1.8wt%, S0.01wt% or less, Al0.01~0.08wt%, and also contains one or two types of Nb0.01~0.06wt%, Ti0.03~0.1wt%, and further, Ca0.0005~0.01wt%, rare earth metal
Contains 0.005 to 0.1 wt% of one or two types, with the balance consisting of Fe and impurities, and
A high-strength hot-rolled steel plate for clamps, characterized by an area ratio of 95 to 40% polygonal ferrite and 5 to 60% bainite. 5 C0.05~0.2wt%, Si0.01~0.05wt%, Mn0.8
~1.8wt%, S0.01wt%, Al0.01~0.08wt%, and also contains one or two of Nb0.01~0.06wt%, Ti0.03~0.1wt%, and further, Ca0.0005~0.01wt%, rare earth metal
Contains 0.005-0.1wt% of one or two types, and Cr0.1-0.4wt%, with the balance consisting of Fe and impurities, and
A high-strength hot-rolled steel plate for clamps, characterized by an area ratio of 95 to 40% polygonal ferrite and 5 to 60% bainite.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16714185A JPS6227549A (en) | 1985-07-29 | 1985-07-29 | High-strength hot-rolled steel plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16714185A JPS6227549A (en) | 1985-07-29 | 1985-07-29 | High-strength hot-rolled steel plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6227549A JPS6227549A (en) | 1987-02-05 |
| JPH0453938B2 true JPH0453938B2 (en) | 1992-08-28 |
Family
ID=15844186
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16714185A Granted JPS6227549A (en) | 1985-07-29 | 1985-07-29 | High-strength hot-rolled steel plate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6227549A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5077210A (en) * | 1973-11-12 | 1975-06-24 | ||
| JPS5935653A (en) * | 1982-08-19 | 1984-02-27 | Kawasaki Steel Corp | High-tension hot-rolled steel plate |
| JPS59126719A (en) * | 1983-01-11 | 1984-07-21 | Nippon Steel Corp | Production of high tension hot rolled steel sheet having excellent processability |
| JPS59129725A (en) * | 1983-01-17 | 1984-07-26 | Kobe Steel Ltd | Production of hot rolled high tension steel sheet having excellent cold workability |
-
1985
- 1985-07-29 JP JP16714185A patent/JPS6227549A/en active Granted
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5077210A (en) * | 1973-11-12 | 1975-06-24 | ||
| JPS5935653A (en) * | 1982-08-19 | 1984-02-27 | Kawasaki Steel Corp | High-tension hot-rolled steel plate |
| JPS59126719A (en) * | 1983-01-11 | 1984-07-21 | Nippon Steel Corp | Production of high tension hot rolled steel sheet having excellent processability |
| JPS59129725A (en) * | 1983-01-17 | 1984-07-26 | Kobe Steel Ltd | Production of hot rolled high tension steel sheet having excellent cold workability |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6227549A (en) | 1987-02-05 |
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