JPH02259014A - Manufacture of tough and hard bar steel - Google Patents
Manufacture of tough and hard bar steelInfo
- Publication number
- JPH02259014A JPH02259014A JP7850089A JP7850089A JPH02259014A JP H02259014 A JPH02259014 A JP H02259014A JP 7850089 A JP7850089 A JP 7850089A JP 7850089 A JP7850089 A JP 7850089A JP H02259014 A JPH02259014 A JP H02259014A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- rolling
- pearlite
- ferrite
- temperature
- 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 80
- 239000010959 steel Substances 0.000 title claims abstract description 80
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 238000005096 rolling process Methods 0.000 claims abstract description 33
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 19
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 13
- 239000002344 surface layer Substances 0.000 claims abstract description 13
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 12
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 7
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 7
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 abstract description 22
- 239000000463 material Substances 0.000 abstract description 12
- 238000007670 refining Methods 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 17
- 238000010791 quenching Methods 0.000 description 12
- 230000000171 quenching effect Effects 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 239000000203 mixture Substances 0.000 description 9
- 238000003303 reheating Methods 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 238000005496 tempering Methods 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910000851 Alloy steel Inorganic materials 0.000 description 3
- 230000001965 increasing effect Effects 0.000 description 3
- 238000001953 recrystallisation Methods 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 229910052745 lead Inorganic materials 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000003631 expected effect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Landscapes
- Metal Rolling (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
Description
【発明の詳細な説明】
「発明の目的」
（産業上の利用分野）
この発明は非調質強靭棒鋼の製造方法に関するものであ
る。DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a non-thermal toughened steel bar.
（従来の技術）
従来、自動車部品もしくは建設用機械部品等において、
９０〜１１０ ｋｇｆ／ｍｍ２程度の引張強さが要求さ
れるものについては、ＳＣＭ４３５等の低合金鋼を、オ
フラインにおいて焼入れ焼戻し処理を行なった上で使用
してきている。(Prior art) Conventionally, in automobile parts or construction machine parts, etc.
For materials requiring a tensile strength of about 90 to 110 kgf/mm2, low alloy steel such as SCM435 has been used after being quenched and tempered off-line.
然し乍ら、このようなオフラインにおける調質について
は、多大の時間とコストを必要とするところから、かな
り以前からこのような余分の工程の省略が望まれており
、近年においてはＶ等のマイクロアロイングによる非調
質鋼が開発されているが、−船釣にこの種の非調質鋼の
欠点としては靭性の低いことが指摘されている。この欠
点を補うために制御圧延との組合せで動性を向上せしめ
ようとするものに特開昭５９−９１２２号がある。However, since such off-line tempering requires a large amount of time and cost, it has been desired to eliminate such extra steps for a long time, and in recent years, microalloying such as V A non-tempered steel has been developed, but it has been pointed out that a drawback of this type of non-tempered steel for boat fishing is its low toughness. In order to compensate for this drawback, Japanese Patent Application Laid-Open No. 59-9122 attempts to improve the dynamicity by combining it with controlled rolling.
この方法は、０．０５〜０．１５％の■を含む鋼を、９
００℃以下で少なくとも２０％以上の熱間加工を施すも
ので粒を微細化して靭性を向上せしめようとするもので
ある。又、一方、高強度棒鋼を製造する方法としては、
例えば特開昭５１−９９６１９号もしくは特開昭６２−
８６１２５号等が提案されている。これらの方法は仕上
圧延後の鋼を水冷等により直接急冷した移調の保有熱に
より焼戻し処理を行なう方法である。This method uses steel containing 0.05 to 0.15% of 9
This method involves hot working at least 20% or more at temperatures below 00°C to refine the grains and improve toughness. On the other hand, as a method for manufacturing high-strength steel bars,
For example, JP-A-51-99619 or JP-A-62-
No. 86125 etc. have been proposed. These methods are methods in which the steel after finish rolling is directly quenched by water cooling or the like, and tempering is performed using the retained heat of the transposed phase.
（発明が解決しようとする課題）
前述したような改良案にしても、未だ問題点が完全に克
服されたものではない。例えば特開昭５９−９１２２号
について云えば、圧延後は放冷であるため冷却途中にオ
ーステナイト粒の再結晶が進んで、充分微細な組織を得
ることができず、パーライトの間隔も粗大であり高強度
化が達成されたとは云えない。仮に■の添加量を増大せ
しめたとしてもコストアンプとなる他、衝撃値が低下し
てくる始末である。先程の特開昭５１−９９６１９号等
にしても、例えばこれらの発明を３４５Ｃ等の機械構造
用鋼に適用しても、ＳＣＭ４３５調質材と同等の強度も
しくは靭性を得ることはできない。特に６０龍φ以上の
大径材においては、強化されるのは表層に近い部分のみ
であって、内部まで強化するには、より高い焼入れ性を
有する鋼材を使用せざるを得す、３０Ｍ４３５そのもの
にこれ等の方法を適用する場合には内部がベイナイトを
主体とする組織となり靭性が著しく低下することになる
。(Problems to be Solved by the Invention) Even with the above-mentioned improvement plans, the problems have not yet been completely overcome. For example, in the case of JP-A-59-9122, since it was left to cool after rolling, recrystallization of austenite grains progressed during cooling, making it impossible to obtain a sufficiently fine structure, and the spacing between pearlites was also large. It cannot be said that high strength was achieved. Even if the amount of (2) added were increased, it would not only increase the cost but also reduce the impact value. Even if the above-mentioned Japanese Patent Application Laid-Open No. 51-99619 is applied, for example, even if these inventions are applied to machine structural steel such as 345C, it is not possible to obtain strength or toughness equivalent to that of SCM435 tempered material. In particular, for large diameter materials of 60mm diameter or larger, only the parts near the surface are strengthened, and in order to strengthen the inside, a steel material with higher hardenability must be used, 30M435 itself. When these methods are applied to the steel, the internal structure becomes composed mainly of bainite, resulting in a significant decrease in toughness.
本願発明はこのような現状に鑑み創案されたものであり
、特に合金元素の添加量を増大せしめることなく、後述
する所定の化学組成と圧延条件並びに熱処理条件を特定
の範囲に限定することにより、オンラインにおいて３０
Ｍ４３５等の低合金代替の高強度、高靭性の非調質棒鋼
の製造方法を提供することを目的とするものである。The present invention was devised in view of the current situation, and by limiting the predetermined chemical composition, rolling conditions, and heat treatment conditions described below to specific ranges, without particularly increasing the amount of alloying elements added, 30 online
The purpose of the present invention is to provide a method for manufacturing a high-strength, high-toughness non-tempered steel bar as an alternative to low-alloy steel bars such as M435.
「発明の構成」
（課題を解決するための手段）
前述の目的を達成するために本発明者等は、（１１重量
％で、
Ｃ： ０．２０〜０．５０％、 Ｓｉ ： ０．１０〜
１．００％Ｍｎ ： ０．８０〜１．８０％、 Ｖ ：
０．０５〜０．３０％を含有する鋼片を９００〜１１
００℃に加熱して、圧延し７５０〜１０５０℃の間で仕
上げ圧延を行ない、後、鋼の表面をＭｓ点以下の温度に
急冷し、次いで鋼材の内部保有熱により表面温度を４５
０〜６８０℃に復熱せしめ、表層を焼戻しマルテンサイ
ト組織となし、内部を微細なフェライト士パーライトま
たはフェライト＋パーライト→ベイナイトの混合組織と
したことを特徴とする強靭棒鋼の製造方法。"Structure of the Invention" (Means for Solving the Problems) In order to achieve the above-mentioned object, the present inventors have developed (11% by weight, C: 0.20-0.50%, Si: 0.10) ~
1.00%Mn: 0.80-1.80%, V:
900-11 steel pieces containing 0.05-0.30%
After heating to 00°C, rolling and finish rolling at 750 to 1050°C, the surface of the steel is rapidly cooled to a temperature below the Ms point, and then the surface temperature is reduced to 45°C by the internal heat of the steel.
A method for manufacturing a strong steel bar, characterized in that the surface layer is reheated to 0 to 680°C, the surface layer has a tempered martensitic structure, and the inside has a fine ferrite/pearlite or a mixed structure of ferrite + pearlite → bainite.
（２）重量％で、
Ｃ：０．２０〜０．５０％、 Ｓｉ：０．１０〜１．
００％Ｍｎ ： ０．８０〜１．８０％、 Ｖ ：
０．０５〜０．３０％を含有する鋼片を９００〜１１
００℃に加熱して、圧延し７５０〜１０５０℃の間で仕
上げ圧延を行ない、後、鋼の表面をＭｓ点以下の温度に
急冷し、次いで鋼材の内部保有熱により表面温度を４５
０〜６８０℃に復熱せしめ、更に鋼表面を４５０℃未満
まで急冷し、表層を焼戻しマルテンサイト組織となし、
内部を微細なフェライト士パーライトまたはフェライト
＋パーライト＋ベイナイトの混合組織としたことを特徴
とする強靭棒鋼の製造方法を蔵に提案する。本発明方法
の採用により、３０Ｍ４３５等の低合金鋼代替の高強度
高靭性の非調質棒鋼をオンラインにおいて製造すること
ができる。(2) In weight%, C: 0.20-0.50%, Si: 0.10-1.
00%Mn: 0.80-1.80%, V:
900-11 steel pieces containing 0.05-0.30%
After heating to 00°C, rolling and finish rolling at 750 to 1050°C, the surface of the steel is rapidly cooled to a temperature below the Ms point, and then the surface temperature is reduced to 45°C by the internal heat of the steel.
The steel surface is reheated to 0 to 680°C, and the steel surface is rapidly cooled to below 450°C, so that the surface layer becomes a tempered martensitic structure.
We propose to Kura a method for producing a strong steel bar whose interior is characterized by a fine ferritic pearlite structure or a mixed structure of ferrite, pearlite, and bainite. By employing the method of the present invention, it is possible to produce on-line a high-strength, high-toughness non-tempered steel bar that is a substitute for low-alloy steel such as 30M435.
（作用）
本願発明は、内部強靭化棒鋼特に７０鶴φ程度を超える
大径材の棒鋼について内部を強靭化することに特徴があ
る。(Function) The present invention is characterized in that it strengthens the interior of an internally toughened steel bar, particularly a large diameter steel bar that exceeds about 70 φ.
そのためには、以下に述べるような限定された化学組成
の鋼片を使用すると共に、圧延条件、熱処理条件を特定
の範囲内に限定して行なうものである。化学組成、およ
び圧延後のオーステナイト粒の成長を抑制し、表層部に
マルテンサイト組織を生成せしめるための急冷、表層マ
ルテンサイトを焼戻すための内部保有熱による復熱並び
に必要に応じて行なう内部強靭化のための前後２回の急
冷等の条件に従来法に見られない知見がある。For this purpose, a steel billet with a limited chemical composition as described below is used, and the rolling conditions and heat treatment conditions are limited within a specific range. Chemical composition, rapid cooling to suppress the growth of austenite grains after rolling and generate martensite structure in the surface layer, reheating using internal heat to temper the surface martensite, and internal toughening as necessary. There are findings not found in conventional methods regarding conditions such as quenching twice before and after oxidation.
先ず本願発明における化学的組成の限定理由について説
明する。First, the reason for limiting the chemical composition in the present invention will be explained.
Ｃ： ０．２０〜０．５０％
Ｃは綱の強度を確保するための重要な元素である。然し
０．２０％未満では焼入れ時のマルテンサイトの硬度が
充分でないので、０．２０％以上の添加を必要とし、一
方０１５０％を超えると靭性の低下が目立つので、０．
２０〜０．５０％の間に限定した。C: 0.20-0.50% C is an important element for ensuring the strength of the steel. However, if it is less than 0.20%, the hardness of martensite during quenching will not be sufficient, so it is necessary to add 0.20% or more.On the other hand, if it exceeds 0.150%, the decrease in toughness will be noticeable.
It was limited to between 20 and 0.50%.
Ｓｉ：０．１０〜１．００％
Ｓｉは脱酸用元素として重要であり、而もフェライトに
固溶して綱を強化する。これらの効果を期待するには、
０．１０％以上の添加を必要とするが、１．００％を超
えての添加では鋼の清浄性を低下せしめると共に靭性も
劣化せしめることになる。又脱炭を促進することにもな
るので、０．１０〜１．００％の間に限定した。Si: 0.10 to 1.00% Si is important as a deoxidizing element, and is dissolved in ferrite to strengthen the steel. To expect these effects,
It is necessary to add 0.10% or more, but addition of more than 1.00% reduces the cleanliness of the steel and also deteriorates the toughness. Since it also promotes decarburization, it is limited to between 0.10 and 1.00%.
Ｍｎ： ０．８０〜１．８０％
Ｍｎは焼入れ性を高め、鋼を強化する有効な元素である
。然し、０．８０％未満では所望の強靭性を有する鋼を
得ることが困難であり、一方１．８０％を超えて添加し
ても、ベイナイトの占める割合を高くして、かえって靭
性を損なうことになるので、１．００〜１．８０％に限
定した。Mn: 0.80-1.80% Mn is an effective element that improves hardenability and strengthens steel. However, if it is less than 0.80%, it is difficult to obtain steel with the desired toughness, while if it is added in excess of 1.80%, the proportion of bainite increases and the toughness is impaired. Therefore, it was limited to 1.00 to 1.80%.
Ｖ ： ０．０５〜０．３０％
■は焼入れ性を高めると共に、微細な炭化物、窒化物を
析出して鋼を強靭化するのに有効な元素である。然し０
．０５％未満ではその効果は小さく、一方高価な元素で
もあり、期待する効果は、０．３０％までの添加で達成
できるので、上述の範囲に限定した。V: 0.05 to 0.30% (2) is an effective element for enhancing hardenability and precipitating fine carbides and nitrides to strengthen steel. But 0
．． If less than 0.05%, the effect will be small, and on the other hand, it is an expensive element, and the expected effect can be achieved by adding up to 0.30%, so it was limited to the above range.
その他の元素について：
前述の各元素に比較して重要性が低いので、必須元素と
しては記載しなかったが、細粒化元素としてのＮ、窒化
物形成元素としてのＴｉ、 Ｚｒ、 Ｎｂ等を適宜、添
加することができる。更に、鋼の焼入れ性を高めるため
に、内部が完全なベイナイト組織を形成することなく、
室温衝撃値が６ ｋｒｆｍ／ａｍ２未満とならない範囲
でＣｒ、 Ｎｉｓ ＭＯ％ Ｂを添加してもよい。又、
切削性が要求される場合には、Ｓ、Ｐｂ、 Ｃａ、 Ｂ
ｉ等の切削性向上元素を添加し得ることは勿論である。Regarding other elements: Since they are less important than the above-mentioned elements, they are not listed as essential elements, but N as a grain refining element, Ti, Zr, Nb, etc. as nitride forming elements are included. It can be added as appropriate. Furthermore, in order to improve the hardenability of the steel, it is possible to improve the hardenability of the steel without forming a complete bainitic structure inside.
Cr, Nis MO% B may be added to the extent that the room temperature impact value does not become less than 6 krfm/am2. or,
When machinability is required, S, Pb, Ca, B
Of course, machinability-improving elements such as i can be added.
尚、鋼中には不可避的不純物としてＰ、Ｃｕ等が含まれ
ているが異状に含有量の多くない限り問題はない。Although steel contains unavoidable impurities such as P and Cu, there is no problem as long as the content is not abnormally large.
次いで熱処理条件に関する限定条件並びにその理由を述
べる。Next, the limiting conditions regarding the heat treatment conditions and the reasons thereof will be described.
鋼片の加熱温度２９００〜１１００℃
９００℃未満では、圧延機にかかる負荷が非常に太き（
なり、設備保護の見地から、少なくとも９００℃以上と
する必要があり、一方１１００℃を超える場合にはオー
ステナイト粒の成長が著しくなると共に脱炭作用も大き
くなるので９００〜１１００℃の範囲とした。If the heating temperature of the steel billet is 2900-1100℃ or less than 900℃, the load on the rolling mill will be very large (
Therefore, from the viewpoint of equipment protection, it is necessary to set the temperature to at least 900°C or higher.On the other hand, if the temperature exceeds 1100°C, the growth of austenite grains will become significant and the decarburization effect will also become large, so the temperature was set in the range of 900 to 1100°C.
仕上げ圧延温度ニア５０〜１０５０℃
仕上げ圧延の終了温度が７５０℃未満の場合には、鋼の
オーステナイト粒が小さくなり過ぎて焼入れ性が低下す
る。而も、温度低下の場合には、圧延機にかかる負荷が
大きくなり過ぎると同時に、表面疵の発生が著しくなる
ので好ましくない。Finish rolling temperature near 50 to 1050°C If the finishing temperature of finish rolling is less than 750°C, the austenite grains of the steel become too small and the hardenability deteriorates. However, if the temperature is lowered, the load on the rolling mill becomes too large and at the same time the occurrence of surface defects becomes significant, which is not preferable.
方１０５０℃を超える場合には、圧延中の動的再結晶お
よび圧延後の静的再結晶の進行が著しく１、微細な粒を
得ることができず、又、靭性も低下するので、７５０〜
１０５０℃の範囲とする必要がある。If the temperature exceeds 1050°C, dynamic recrystallization during rolling and static recrystallization after rolling will proceed significantly, making it impossible to obtain fine grains and reducing toughness.
The temperature needs to be within the range of 1050°C.
仕上圧延後の急冷時の鋼の表面温度二Ｍｓ点以下急冷時
の鋼の表面温度が、Ｍｓ点を超える場合にはマルテンサ
イト組織を得ることができないので、Ｍｓ点以下に急冷
する必要がある。急冷には普通水が用いられる。The surface temperature of the steel during quenching after finish rolling is below the 2Ms point If the surface temperature of the steel during quenching exceeds the Ms point, it is not possible to obtain a martensitic structure, so it is necessary to rapidly cool the steel below the Ms point. . Ordinary water is used for rapid cooling.
復熱後の表面温度＝４５０〜６８０℃
急冷により得られたマルテンサイト組織はそのままでは
靭性に欠ける。そのため焼入れ歪を開放Ｏ
して棒の曲がりを防止するために焼戻しを行なう必要が
ある。４５０℃未満の復熱では焼戻しが不充分であり表
面の靭性が乏しい。一方６８０℃を超える復熱ではマル
テンサイトの分解が速く、充分に硬化した表層を得るこ
とができないので、４５０〜６８０℃の範囲内とした。Surface temperature after reheating = 450 to 680°C The martensitic structure obtained by rapid cooling lacks toughness as it is. Therefore, it is necessary to perform tempering to release the quenching strain and prevent the rod from bending. If the reheating temperature is lower than 450°C, the tempering will be insufficient and the surface toughness will be poor. On the other hand, if the reheating temperature exceeds 680°C, martensite decomposes quickly and a sufficiently hardened surface layer cannot be obtained, so the temperature was set within the range of 450 to 680°C.
２回目の急冷時の鋼の表面温度：４５０℃未満２回目の
急冷は、７Ｑｍｍφ程度を超える大径の場合に行なう。Surface temperature of steel during second quenching: less than 450°C The second quenching is performed in the case of a large diameter exceeding approximately 7Qmmφ.
例えば、１００鰭φのような大径になると、表層付近は
硬化しても、内部を充分強靭化させることはできない。For example, when the diameter is as large as 100 fins, even if the near surface layer is hardened, the inside cannot be made sufficiently tough.
内部を強靭化するために、１回目の急冷時間を長くする
場合には、逆に表面の復熱が不充分となる恐れがある。If the first quenching time is lengthened in order to strengthen the interior, there is a risk that surface heat recovery may be insufficient.
従って大径材の処理に当っては、先ず適性な急冷−復熱
によって表層に焼戻しマルテンサイトを得た後、更に内
部を強靭化させるために、再度急冷を行なう必要がある
。内部の組織をフェライト士パーライト又はフェライト
＋パーライト＋ベイナイトの混在！ｌ１Ｉｌ織とするた
めに、４５０℃未満の温度まで急冷する。４５０℃以上
の温度では内部を強靭化する度合いが小さいので、４５
０℃未満まで急冷することとした。尚この２回目の急冷
においては表層部は既に変態を完了しているので、表層
部の変化はない。７０ｍ１φ程度未満の棒鋼の場合には
、第１回の急冷−復熱により充分内部まで強靭化させる
ことができるから、本工程の処理を行なう必要はないが
、その適用を妨げるものではない。なお内部の組織が完
全ベイナイトになると靭性が著しく劣るので、強冷を施
した場合でも少量のフェライト士パーライトが残存する
ようにすることが必要である。Therefore, when processing large-diameter materials, it is necessary to first obtain tempered martensite on the surface layer by appropriate quenching and reheating, and then quench again to further strengthen the interior. The internal structure is a mixture of ferrite pearlite or ferrite + pearlite + bainite! Rapid cooling to a temperature below 450° C. to obtain a 1111 weave. At temperatures above 450℃, the degree of internal toughening is small, so 45℃
It was decided to rapidly cool down to below 0°C. In this second quenching, the surface layer has already completed its transformation, so there is no change in the surface layer. In the case of a steel bar with a diameter of less than about 70 m1, the first rapid cooling-reheating process can sufficiently toughen the inside, so it is not necessary to carry out this process, but this does not prevent its application. Note that if the internal structure becomes completely bainite, the toughness will be significantly inferior, so it is necessary to ensure that a small amount of ferrite or pearlite remains even when strong cooling is performed.
本発明方法により得られる棒鋼の特性：（ａ）表層が焼
戻しマルテンサイト組織である。Characteristics of the steel bar obtained by the method of the present invention: (a) The surface layer has a tempered martensitic structure.
（ｂ）内部が微細なフェライト士パーライトまたはフェ
ライト＋パーライト＋ベイナイトの混合組織である。(b) The inside has a fine ferrite/pearlite or a mixed structure of ferrite + pearlite + bainite.
（ｃ）棒の中間部（Ｒ／２、Ｒは半径）の引張強さが８
０Ｋｇｆ／ｍｍ２以上、室温衝撃値９は６ ｋｇｆｍ／
ｃｍ２以上である。(c) The tensile strength of the middle part of the rod (R/2, R is the radius) is 8
0Kgf/mm2 or more, room temperature impact value 9 is 6 kgfm/
cm2 or more.
（＊ＪＩＳ Ｚ ２２０２３号試験片による）上記特性
は、化学的組成が本願規定の範囲内であり、圧延条件、
熱処理条件が遵守される限り、小径のものは勿論１００
鰭φの棒鋼のものまでが具備する特性である。(*Based on JIS Z 22023 test piece) The above characteristics are that the chemical composition is within the range specified in this application, and that the rolling conditions,
As long as the heat treatment conditions are followed, small diameter ones can of course be used.
This is a characteristic that even steel bars with fins of φ have.
（実施例）
本発明方法は、加熱炉において所定の温度に加熱された
鋼片を、棒鋼用圧延機群において所望する直径の棒鋼に
まで圧延する。最終圧延を終えた棒鋼は、圧延機の後に
設置された第１水冷帯において、その直径に応じて適性
な時間水冷され、その後、所定の温度範囲での復熱をさ
せた後、冷却床において冷却される。然し、大径材につ
いては、前記第１水冷帯の後方に、適当な間隔をおいて
設置した第２水冷帯において、再度急冷が行なわれるこ
とになる。(Example) In the method of the present invention, a steel billet heated to a predetermined temperature in a heating furnace is rolled into a steel bar of a desired diameter in a group of steel bar rolling mills. After the final rolling, the steel bar is water-cooled for an appropriate time depending on its diameter in the first water cooling zone installed after the rolling mill, and then recuperated within a predetermined temperature range before being transferred to the cooling bed. cooled down. However, large-diameter materials are rapidly cooled again in a second water cooling zone installed at an appropriate interval behind the first water cooling zone.
第１表には供試材の化学組成を示す。鋼Ａは０．３２％
Ｃ−０，２５Ｓｉ １．７０％Ｍｎ−０，２５％Ｖを
主体とし、これに細粒化元素のＡ５．Ｎｂを含む綱、鋼
Ｂは０．４２％Ｃ−０，２５％５ｔ−１，５０％Ｍｎｏ
、２０％■を主体としこれにＡ同様にＡＪ、Ｎｂを添加
した鋼、鋼Ｃは０１４１％Ｃ−０，７０％５ｔ−１，０
５％Ｍ＋１−０．１０％■を主体とするもので、細粒化
元素としてはＡｊ！、Ｔｉを、焼入れ性向上元素として
Ｃｒ、Ｂを、切削性向上元素としてＰｂ、 Ｃａを含む
鋼であり、鋼りは通常の３０Ｍ４３５である。Table 1 shows the chemical composition of the test materials. Steel A is 0.32%
Mainly composed of C-0,25Si 1.70%Mn-0,25%V, and A5. Steel B, a rope containing Nb, is 0.42%C-0.25%5t-1.50%Mno
, 20%■ is the main component, and AJ and Nb are added to it in the same way as A. Steel C is 0141%C-0,70%5t-1,0
It is mainly composed of 5%M+1-0.10%■, and as a grain refining element Aj! , Ti, Cr and B as elements to improve hardenability, and Pb and Ca as elements to improve machinability, and the steel is normal 30M435.
第２表には比較例法、従来法、 本発明方法側の 試験条件を示し、第３表には各々の試験結果を示す。Table 2 shows the comparative example method, conventional method, On the side of the method of the present invention The test conditions are shown, and Table 3 shows the respective test results.
試験Ｎ１１ｌ〜４は鋼Ｂ、 階ｓは鋼Ｂを用いた３０ｍ
ｕφ棒鋼についての結果である。Test N11l~4 was 30m using steel B, and floor s was steel B.
These are the results for uφ steel bars.
１ｌｌｌ１１は通常の制御圧延の例で、圧延終了後の水
冷を行なっていないものである。隘５の３０Ｍ４３５の
オフライン調質材と比較すると、表面硬度が低く、内部
の組織は粗大なフェライトとパーライトであり、強度、
靭性の何れも不足している。1llll11 is an example of normal controlled rolling, in which water cooling is not performed after rolling. Compared to the offline tempered material of 30M435 in Section 5, the surface hardness is lower, the internal structure is coarse ferrite and pearlite, and the strength and strength are lower.
It lacks both toughness and toughness.
嵐２はやや高めの温度で最終圧延した後水冷した例であ
るが、水冷時間が２秒と云う短かさであり、冷却不足の
ため阻１と同程度の結果しか得られていない。Arashi 2 is an example in which water cooling was performed after the final rolling at a slightly higher temperature, but the water cooling time was only 2 seconds, and the result was only comparable to Arashi 1 due to insufficient cooling.
嵐３は水冷時間を４秒とした本発明方法の例である。表
面硬度が高く耐摩耗性に優れ、内部ｍ織は少量のベイナ
イトと微細なフェライト士パーライトよりなる組織であ
って、良好な強靭性を有する棒鋼が得られていることが
判る。Storm 3 is an example of the method of the present invention in which the water cooling time was 4 seconds. It can be seen that the steel bar has high surface hardness and excellent wear resistance, and the internal weave is a structure consisting of a small amount of bainite and fine ferrite and pearlite, and has good toughness.
陽４も本発明の実施例である。阻３より低い最終圧延温
度のため、粒が微細化してフェライトがで易くなった分
だけ、僅かに強度は低下しているが、靭性は隘３よりも
優れていることが判る。Positive 4 is also an embodiment of the present invention. Due to the final rolling temperature being lower than that of A3, the grains became finer and ferrite was more likely to form, so the strength was slightly lower, but it was found that the toughness was superior to A3.
臘５はオフラインにおける３０Ｍ４３５の調質材である
。臘5 is an off-line tempered material of 30M435.
次のｍ６〜７は鋼Ｂ、ｔｋｇは鋼りを用いた何れも７０
鶴φにおける結果である。The next m6 to 7 are made of steel B, and the tkg is made of steel, both of which are 70
These are the results for Tsuruφ.
阻６は圧延終了後の急冷は１回のみであるが、水冷時間
が適当なため、良好な強靭性が得られている。本発明の
実施例である。Although No. 6 was rapidly cooled only once after rolling, good toughness was obtained because the water cooling time was appropriate. This is an example of the present invention.
隘７これも本発明の例で、急冷−復熱−急冷の２回冷却
を行なっており、途中で５５０℃に復熱せしめており、
隘６よりも高強度のものが得られている。(7) This is also an example of the present invention, in which cooling is performed twice: rapid cooling - reheating - rapid cooling, and the temperature is reheated to 550°C in the middle.
A product with higher strength than No. 6 was obtained.
Ｎａ８はオフラインにおける３０Ｍ４３５の調質材であ
る。Na8 is a 30M435 tempered material offline.
次は１００ｎφについての例でありＮｎ９〜１０は鋼Ｂ
、＋１ｋＬ１１はｗＡＤを用いた結果である。The following is an example for 100nφ, and Nn9~10 is steel B
, +1kL11 are the results using wAD.
１１ｈ９は１回だけの急冷を行なった例であるが、直径
が大きいために、内部が強靭化されていない。11h9 is an example in which quenching was performed only once, but since the diameter is large, the inside is not strengthened.
阻１０は第１回１６秒、第２回２０秒の急冷を実施した
本発明の実施例である。内部組織も微細なフェライト士
パーライトであり、強靭な棒鋼がＣＪられζいる。10 is an example of the present invention in which rapid cooling was performed for 16 seconds for the first time and 20 seconds for the second time. The internal structure is also made of fine ferrite pearlite, making it a strong steel bar.
１１ｋｌｌｌはオフラインにおけるＳＣＭ４３５の富岡
質材である。11klll is SCM435 Tomioka Materials in offline mode.
次は７０龍φ棒鋼を熱処理条件ｇを適用した例であり、
Ｎ１１１２は鋼Ａ、Ｎａ１３は鋼Ｃ１隘１４は鋼りを用
いた結果である。Ｎａ１２〜１３は本発明の実施例であ
る。The following is an example of applying heat treatment condition g to a 70 dragon diameter steel bar.
N1112 is the result of using steel A, Na13 is steel C1, and 14 is the result of using steel. Na12-13 are examples of the present invention.
階１２は炭素量が少ないため、高い衝撃特性値が示され
ている。Floor 12 has a low carbon content and therefore exhibits high impact property values.
隘１３はＭｎｓ Ｖ量を低くしても、３１％ Ｃｒｓ
Ｂの増加により、良好な強靭性を示す棒鋼が得られてい
る。No. 13 is 31% Crs even if the Mns V amount is lowered.
By increasing B, a steel bar exhibiting good toughness is obtained.
Ｎ１１１４はＳＣＭ４３５について行なった例であるが
、組成が本発明と異なるため、強度は充分であるが、内
部組織は完全ベイナイト組織となっており衝撃値が著し
く低下していることが判る。図表は階６．１１ｋＬ７に
おける鋼材表面の温度変化を示すものである。N1114 is an example of SCM435, and since the composition is different from the present invention, the strength is sufficient, but the internal structure is completely bainite structure, and it can be seen that the impact value is significantly reduced. The chart shows the temperature change on the steel surface at floor 6.11kL7.
「発明の効果」
以上詳述したように、本願発明において規定する化学組
成、熱処理条イ′１および圧延条件を遵守する場合には
従来のようにオフラインにおける調質処理は全く必要と
せず、ＳＣＭ４３５等の低合金鋼代替の強靭非調質棒鋼
をオフラインにおいて直接製造することができるから、
本願発明の業界に与える影響は頗る大きいものがある。"Effects of the Invention" As detailed above, when the chemical composition, heat treatment strip '1 and rolling conditions specified in the present invention are complied with, there is no need for off-line tempering treatment at all as in the past, and SCM435 It is possible to directly produce strong non-tempered steel bars as a substitute for low-alloy steels offline, such as
The influence of the present invention on the industry is significant.
図表は本願発明の実施例Ｎｉ１６．１Ｉｋ１．７におけ
る鋼材表面の温度変化を示すものである。
特許出願人 トーテ・スチール株式会社発 明
者 大和用
能
由
同
江
口
豊
明The chart shows temperature changes on the steel surface in Example Ni16.1Ik1.7 of the present invention. Patent applicant: Tote Steel Co., Ltd. Inventor: Yamatoyo Noyudo Eguchi Toyoaki
Claims (1)
％Ｍｎ：０．８０〜１．８０％、Ｖ：０．０５〜０．３
０％を含有する鋼片を９００〜１１００℃に加熱して、
圧延し７５０〜１０５０℃の間で仕上げ圧延を行ない、
後、鋼の表面をＭｓ点以下の温度に急冷し、次いで鋼材
の内部保有熱により表面温度を４５０〜６８０℃に復熱
せしめ、表層を焼戻しマルテンサイト組織となし、内部
を微細なフェライト＋パーライトまたはフェライト＋パ
ーライト＋ベイナイトの混合組織としたことを特徴とす
る強靭棒鋼の製造方法。 （２）重量％で、 Ｃ：０．２０〜０．５０％、Ｓｉ：０．１０〜１．００
％Ｍｎ：０．８０〜１．８０％、Ｖ：０．０５〜０．３
０％を含有する鋼片を９００〜１１００℃に加熱して、
圧延し７５０〜１０５０℃の間で仕上げ圧延を行ない、
後、鋼の表面をＭｓ点以下の温度に急冷し、次いで鋼材
の内部保有熱により表面温度を４５０〜６８０℃に復熱
せしめ、更に鋼表面を４５０℃未満まで急冷し、表層を
焼戻しマルテンサイト組織となし、内部を微細なフェラ
イト＋パーライトまたはフェライト＋パーライト＋ベイ
ナイトの混合組織としたことを特徴とする強靭棒鋼の製
造方法。[Claims] 1) In weight%: C: 0.20 to 0.50%, Si: 0.10 to 1.00
%Mn: 0.80-1.80%, V: 0.05-0.3
Heating a steel piece containing 0% to 900-1100°C,
Rolling and finish rolling at 750 to 1050°C,
After that, the surface of the steel is rapidly cooled to a temperature below the Ms point, and then the surface temperature is reheated to 450 to 680°C using the internal heat of the steel, so that the surface layer becomes a tempered martensitic structure and the inside becomes a fine ferrite + pearlite structure. Alternatively, a method for producing a strong steel bar characterized by having a mixed structure of ferrite + pearlite + bainite. (2) In weight%, C: 0.20-0.50%, Si: 0.10-1.00
%Mn: 0.80-1.80%, V: 0.05-0.3
Heating a steel piece containing 0% to 900-1100°C,
Rolling and finish rolling at 750 to 1050°C,
After that, the surface of the steel is rapidly cooled to a temperature below the Ms point, then the surface temperature is reheated to 450 to 680°C using the internal heat of the steel, and the steel surface is further rapidly cooled to below 450°C, and the surface layer is tempered to form martensite. A method for producing a strong steel bar, characterized in that the inside has a mixed structure of fine ferrite + pearlite or ferrite + pearlite + bainite.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1078500A JP2756535B2 (en) | 1989-03-31 | 1989-03-31 | Manufacturing method for strong steel bars |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1078500A JP2756535B2 (en) | 1989-03-31 | 1989-03-31 | Manufacturing method for strong steel bars |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02259014A true JPH02259014A (en) | 1990-10-19 |
| JP2756535B2 JP2756535B2 (en) | 1998-05-25 |
Family
ID=13663683
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1078500A Expired - Fee Related JP2756535B2 (en) | 1989-03-31 | 1989-03-31 | Manufacturing method for strong steel bars |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2756535B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06136441A (en) * | 1992-10-28 | 1994-05-17 | Sumitomo Metal Ind Ltd | Production of high strength and low yield ratio bar steel for reinforcing bar |
| JP2007100193A (en) * | 2005-10-07 | 2007-04-19 | Topy Ind Ltd | Method for manufacturing roller shell in carrier at lower part of construction machine |
| WO2015076242A1 (en) * | 2013-11-19 | 2015-05-28 | 新日鐵住金株式会社 | Rod steel |
| JP2017115230A (en) * | 2015-12-25 | 2017-06-29 | Ｊｆｅスチール株式会社 | Steel material and method for producing the same |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53146218A (en) * | 1977-05-26 | 1978-12-20 | Kobe Steel Ltd | Manufacture of high tensile steel wire or rod |
| JPS62139818A (en) * | 1985-12-13 | 1987-06-23 | Kobe Steel Ltd | Production of high-strength and high-toughness wire |
| WO1988002031A1 (en) * | 1986-09-19 | 1988-03-24 | Aicher, Max | Process for manufacturing rolled steel products |
-
1989
- 1989-03-31 JP JP1078500A patent/JP2756535B2/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53146218A (en) * | 1977-05-26 | 1978-12-20 | Kobe Steel Ltd | Manufacture of high tensile steel wire or rod |
| JPS62139818A (en) * | 1985-12-13 | 1987-06-23 | Kobe Steel Ltd | Production of high-strength and high-toughness wire |
| WO1988002031A1 (en) * | 1986-09-19 | 1988-03-24 | Aicher, Max | Process for manufacturing rolled steel products |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06136441A (en) * | 1992-10-28 | 1994-05-17 | Sumitomo Metal Ind Ltd | Production of high strength and low yield ratio bar steel for reinforcing bar |
| JP2007100193A (en) * | 2005-10-07 | 2007-04-19 | Topy Ind Ltd | Method for manufacturing roller shell in carrier at lower part of construction machine |
| WO2007043307A1 (en) * | 2005-10-07 | 2007-04-19 | Topy Kogyo Kabushiki Kaisha | Process for manufacturing roller shell of lower running body of construction machine |
| WO2015076242A1 (en) * | 2013-11-19 | 2015-05-28 | 新日鐵住金株式会社 | Rod steel |
| JPWO2015076242A1 (en) * | 2013-11-19 | 2017-03-16 | 新日鐵住金株式会社 | Steel bar |
| US10131965B2 (en) | 2013-11-19 | 2018-11-20 | Nippon Steel & Sumitomo Metal Corporation | Steel bar |
| JP2017115230A (en) * | 2015-12-25 | 2017-06-29 | Ｊｆｅスチール株式会社 | Steel material and method for producing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2756535B2 (en) | 1998-05-25 |
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