JPS609824A - Production of tough and hard steel - Google Patents

Production of tough and hard steel

Info

Publication number
JPS609824A
JPS609824A JP11565383A JP11565383A JPS609824A JP S609824 A JPS609824 A JP S609824A JP 11565383 A JP11565383 A JP 11565383A JP 11565383 A JP11565383 A JP 11565383A JP S609824 A JPS609824 A JP S609824A
Authority
JP
Japan
Prior art keywords
steel
quenching
temperature
less
point
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.)
Pending
Application number
JP11565383A
Other languages
Japanese (ja)
Inventor
Terutaka Tsumura
津村 輝隆
Yasuo Otani
大谷 泰夫
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Sumitomo Metal Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Sumitomo Metal Industries Ltd filed Critical Sumitomo Metal Industries Ltd
Priority to JP11565383A priority Critical patent/JPS609824A/en
Publication of JPS609824A publication Critical patent/JPS609824A/en
Pending legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/78Combined heat-treatments not provided for above

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

PURPOSE:To produce easily a steel having high strength and excellent toughness at a low cost by subjecting a steel formed by incorporating a specific ratio of C, Si, Mn, Al, Nb and Ti into Fe and regulating the contents of P and S to hot rolling and hardening under specific conditions then subjecting repeatedly the steel to heating and hardening followed by tempering. CONSTITUTION:A steel contg., by wt%, 0.15-0.45 C, 0.05-1.00 Si, 0.3-2.0 Mn, 0.01-0.10 Al and 0.005-0.150 1 or 2 kinds of Nb and Ti and consisting of the balance Fe and unavoidable impurities and regulating the P in the impurities to <=0.025 and S to <=0.015 is prepd. Such steel is subjected to hot rolling at <=1100 deg.C so as to attain <=20% reduction of area (RA) then to hardening directly from the austenite state. The steel is then subjected further repeatedly by >=1 time to a treatment for heating the steel to a temp. region of Ac3 point -[AC3 point+200 deg.C] then hardening followed by a tempering treatment at the temp. of the Ac1 point or below. Cu, Cr, V, Mo, W, Ca, rate earth elements and B may be adequately added to the steel, if necessary.

Description

【発明の詳細な説明】 この発明は、例えば極寒冷地等のような低温環境で使用
される大型構造物素材として好適な強靭鋼を、高価な合
金元素や格別な設備を要することなく低コストで製造す
る方法に関するものである。
DETAILED DESCRIPTION OF THE INVENTION The present invention provides high-strength steel, which is suitable as a material for large structures used in low-temperature environments such as extremely cold regions, at low cost and without requiring expensive alloying elements or special equipment. It relates to a method of manufacturing.

近年、我々を取り巻く各種産業の進展ぶりには目を見張
るものがあり、これにともなって地下資源の開発、或い
は海洋資源の開発・育成等、様々な資源開発活動も益々
活発化の度合を深めて来ている。
In recent years, the progress of the various industries surrounding us has been remarkable, and along with this, various resource development activities, such as the development of underground resources and the development and cultivation of marine resources, have become more and more active. It's coming.

そして、これらの活動を支えるものとして、種々の分野
に使用されている鋼材構造物の進歩・発展を見逃すこと
ができないが、開発活動の高能率化や、自然条件の苛酷
な未開発地での活動の必要性等から鋼材構造物は一層巨
大化する傾向を見せはじめてきており、同時に極寒冷地
等の厳しい環境での使用をも余儀無くされるようになっ
てきた。
As a support for these activities, we cannot overlook the progress and development of steel structures used in various fields, but we cannot overlook the progress and development of steel structures used in various fields. Due to the necessity of activities, steel structures have begun to show a tendency to become even larger, and at the same time, they have been forced to be used in harsh environments such as extremely cold regions.

ところで、鋼は、一般に、低温になると靭性の急激な劣
化を来たすという低温脆化現象を呈することが知られて
おり、このようなことから、極寒冷地で使用する大型構
造物用鋼材には、高い強度を備えていることはもちろん
のこと、極寒においても優れた靭性を示すものが強く要
望されていだのである。
By the way, steel is generally known to exhibit a low-temperature embrittlement phenomenon in which toughness rapidly deteriorates at low temperatures.For this reason, steel materials for large structures used in extremely cold regions are There was a strong demand for a material that not only had high strength but also showed excellent toughness even in extremely cold temperatures.

従来、このような要望に応えるための鋼の強靭化は、N
l鋼を基本成分鋼として選び、これに熱処理を施すこと
によって微細焼戻しマルテンサイト 5− 組織と焼戻し時に析出する微細な逆変態オーステナイト
を生成せしめるか、或いは微細焼戻しマルテンサイトと
微細焼戻しベイナイトとの混合組織並びに微細な逆変態
オーステナイトを生成せしめるかして達成されるのが普
通であった。
Conventionally, the toughening of steel to meet such demands has been through the use of N
Select steel as the basic component steel and heat treat it to produce a fine tempered martensite structure and fine reverse transformed austenite that precipitates during tempering, or mix fine tempered martensite and fine tempered bainite. This was usually achieved by creating a microstructure and fine reverse transformed austenite.

しかしながら、このようにして得られる強靭鋼ばN1の
多量添加を欠くことができず、従って鋼材コストの大幅
上昇を免れることができないという極めて不利な問題を
抱えていたのである。
However, the strong steel obtained in this way has had the extremely disadvantageous problem that it is necessary to add a large amount of N1, resulting in a significant increase in the cost of the steel material.

そこで、本発明者等は、先に、rNi等の高価な元素を
多量に含有することのない鋼であっても、オーステナイ
ト状態からの冷却条件を特定のものに制限すると、高強
度と優れた靭性とを同時に示すようになる」との知見に
基づいた強靭鋼の製造方法を特開昭57−89424号
として提案し、低価格で、しかも優れた特性を備えた強
靭鋼を提供して来たが、この特開昭5’i’−8942
4号として提案された方法にも、「鋼の成分毎にその冷
却条件を変更しなければならないので、製造作業が幾分
煩わしい」との声が聞かれていたのである。
Therefore, the present inventors first discovered that even if steel does not contain large amounts of expensive elements such as rNi, if the cooling conditions from the austenitic state are limited to specific conditions, high strength and excellent Based on this knowledge, we proposed a manufacturing method for strong steel in Japanese Patent Application Laid-Open No. 57-89424, and have provided strong steel with excellent properties at a low price. However, this Japanese Patent Application Publication No. 5'i'-8942
Regarding the method proposed as No. 4, some people complained that the manufacturing process was somewhat complicated because the cooling conditions had to be changed for each component of the steel.

 6− 本発明者等は、上述のような観点から、Ni元素の添加
が無い安価な成分の鋼を素材とし、しかも煩わしい作業
を要することもなく、極寒冷地等で使用する大型構造物
等として十分に適用が可能な強靭鋼を、簡単容易に、か
つ低コストで製造する方法を見出すべく研究を行った結
果、以下(a)〜(e)に示す如き知見を得るに至った
のである。即ち、(a)従来のように、N]鋼を基本成
分鋼として選び、更にその焼戻し時に析出してくる微細
な逆変態オーステナイトを利用しなくても、鋼の組織を
極微細な焼戻しマルテンサイト組織、或いは極微細な焼
戻しマルテンサイトと焼戻し低温ベイナイトとの混合組
織とするだけで、極寒冷地における大型構造物素材鋼と
し7て十分に満足し得る適度の強度及び靭性を具備した
鋼材が得られること、(b) 一般に、鋼の結晶粒微細
化のためには誘導加熱法等の急速加熱手段を用いて焼入
れを行うと有効であることが知られているが、特定量の
C成分と、特定量のNb及びT1成分の1種以上とを同
時に含有する鋼においては、これに比較的低温度での高
圧下熱間圧延と直接焼入れとを施しだ後、電気炉加熱の
よう々]℃/ see以下程度のゆっくりした加熱速度
で加熱しても、A、c3点〜[A、03点+200℃〕
の温度に加熱後焼入れる処理を少なくとも1回以上繰返
すと、焼入れによって細粒のマルテンサイト組織、又は
マルテンサイトと低温ベイナイトとの微細混合組織が得
られ、しかも形成されるTi(C,N)或いはNb(c
、N)が、次の焼入れ時の加熱の際、オーステナイトへ
の変態直前の高温になる寸でマルテンサイト又はベイナ
イトのラス(tath )を崩さず、転位の減少を防止
することとなるので、オーステナイトが、旧マルテンサ
イト粒界のほかにラス境界からも生成されて微細組織と
なり、焼入れによって一層微細な低温変態組織(マルテ
ンサイト、低温ベイナイト)を生ずる。そして更に、N
b及びT1がオーステナイト結晶粒の粗大化を防ぐため
、加熱温度が少々高くなっても格別な支障を来たすこと
がなく、安定な作業を行うことができる。従って、これ
をAc1点以下の温度で焼戻しすれば、極めて微細な焼
戻しマルテンサイト組織、或いは極微細な、焼戻しマル
テンサイトと焼戻し低温ベイナイトとの混合組織が得ら
れること、 (C)上記化学成分組成を有する鋼を直接焼入れした後
、ゆっくりとした加熱速度での1回以上の焼入れ処理で
細粒化を実現するためには、直接焼入れする前の熱間圧
延で、1100℃以下の温度域での断面圧縮率を20%
以上としなければならないこと、 (d) −を2以上の整数として、直接焼入れをも含め
て(m −1,)回目の焼入れ処理の後、m回目の焼入
れに際しての加熱の前に、置き割れ等を防止するだめの
焼戻し処理(以下、ラフテンパーと称す)を行うと、熱
処理作業性が極めて容易になること、 (e)鋼中に、更にcu、 Cr、 V 、 Mo及び
Wの1種以上を添加含有せしめると鋼の強度等が一層向
上し、まだ、Ca及び希土類元素の1種以上を添加含有
させると鋼中の介在物が球状化されるとともに鋼の清浄
化がなされて靭性の改善を見、そして微 9− 量のBを添加含有せしめると鋼の強度及び靭性が一層改
善されること。
6- From the above-mentioned viewpoint, the present inventors have developed a structure for large-scale structures used in extremely cold regions, etc., which is made from steel of inexpensive composition without the addition of Ni element, and which does not require any troublesome work. As a result of conducting research to find a method to easily and inexpensively produce strong steel that can be sufficiently applied as . That is, (a) the structure of the steel can be changed to ultra-fine tempered martensite without selecting N] steel as the basic component steel and using the fine reverse-transformed austenite that precipitates during tempering, as in the past. By simply forming a microstructure or a mixed structure of ultra-fine tempered martensite and tempered low-temperature bainite, it is possible to obtain a steel material with appropriate strength and toughness that is sufficiently satisfactory as a steel material for large structures in extremely cold regions. (b) It is generally known that quenching using a rapid heating method such as induction heating is effective for refining the grains of steel. , steel containing a specific amount of Nb and one or more of the T1 components at the same time is subjected to hot rolling under high pressure at a relatively low temperature and direct quenching, followed by heating in an electric furnace] Even if heated at a slow heating rate of less than ℃/see, A, c3 points ~ [A, 03 points + 200℃]
When the quenching process is repeated at least once after heating to a temperature of Or Nb(c
, N) during the next quenching process, the laths of martensite or bainite will not be destroyed at a high temperature just before the transformation to austenite, and a reduction in dislocations will be prevented. is generated from the lath boundaries in addition to the old martensite grain boundaries to form a fine structure, and by quenching, an even finer low-temperature transformed structure (martensite, low-temperature bainite) is produced. And furthermore, N
Since b and T1 prevent coarsening of austenite crystal grains, even if the heating temperature becomes a little high, no particular trouble occurs and stable work can be performed. Therefore, if this is tempered at a temperature below Ac1 point, an extremely fine tempered martensite structure or an extremely fine mixed structure of tempered martensite and tempered low-temperature bainite can be obtained; (C) the above chemical composition; After directly quenching steel with The cross-sectional compression ratio of 20%
(d) where − is an integer of 2 or more, after the (m −1,)th quenching treatment including direct quenching, and before heating for the mth quenching, (e) The steel further contains one or more of Cu, Cr, V, Mo, and W. The addition of Ca and one or more rare earth elements further improves the strength of the steel, while the inclusion of Ca and one or more rare earth elements makes the inclusions in the steel spheroidal and cleans the steel, improving toughness. In addition, by adding a small amount of B, the strength and toughness of the steel are further improved.

この発明は、上記知見に基づいてなされたものであり、 C:0.15〜0.45%(以下、係は重量割合とする
)。
This invention was made based on the above findings, and includes: C: 0.15 to 0.45% (hereinafter, the term "weight percentage").

Si:0.05〜1.OO%、Mn:0.3〜2.0%
Si: 0.05-1. OO%, Mn: 0.3-2.0%
.

AA : 0.01−0.10%。AA: 0.01-0.10%.

Nb及びT1の1種又は2種:0.005〜0.150
係。
One or two of Nb and T1: 0.005 to 0.150
Person in charge.

を含有し、必要によシ更に、 第1区分・・・ Cu: 0.05〜0.50%。Contains, and furthermore, 1st category... Cu: 0.05-0.50%.

Cr: 0.05〜2.O0%。Cr: 0.05-2. O0%.

V:0.01〜0.15%。V: 0.01-0.15%.

MO及びWの1種又は2種。One or two of MO and W.

MO+]72Wで005〜120係。MO+] 72W, 005-120 section.

第2区分・・・ Ca: o、o O1〜0.050 %。Second category... Ca: o, o O1-0.050%.

希土類元素:O,001〜0050%。Rare earth element: O,001-0050%.

第3区分・・・ 10− B:O,0O05〜0. OO50%。Third category... 10- B:O,0O05~0. OO50%.

のうちの1種以上をも含むとともに、 Fe及び不可避不純物:残り。It also includes one or more of the following: Fe and inevitable impurities: Remaining.

から成り、かつ不純物中のP及びSの含有量がそれぞれ
、 P:0.025%以下。
and the content of P and S in the impurities is P: 0.025% or less.

S:0.015%以下。S: 0.015% or less.

である鋼を、1100℃以下での断面圧縮率(RA)が
20%以上となるように熱間圧延した後、直接オーステ
ナイト状態から焼入れし、続いて、AC3点〜(AC3
点+200℃〕の温度域に加熱後焼入れする処理を更に
1回以上繰返して行うか、域いはA、c1点以下の温度
での焼戻しくラフテンパー)と、Ac3点〜〔AC3点
+200℃〕ノ温度域に加熱後焼入れする処理とをこの
順序で1回以上繰返して行い、その後再度AC1点以下
の温度で焼戻し処理を行うことにより、高強度と、極寒
冷地等のような低温環境においても優れた靭性を示す強
靭鋼を得る点に特徴を有するものである。
After hot rolling the steel so that the cross-sectional compressibility (RA) at 1100°C or lower becomes 20% or more, it is directly quenched from the austenitic state, and then the steel is heated at AC3 points to (AC3
The process of heating to a temperature range of +200°C] and then quenching is repeated one or more times, or the rough tempering is performed at a temperature below point A, c1), and from 3 points of Ac to [3 points of AC +200°C] By repeating the process of heating to a temperature range of 100 degrees and then quenching in this order one or more times, and then tempering again at a temperature below the AC1 point, it is possible to achieve high strength and to withstand low-temperature environments such as extremely cold regions. It is also characterized in that it produces strong steel exhibiting excellent toughness.

なお、ここで断面圧縮率(RA、 )とは、次に示す式
、 RA<m= SOニー−肚−X 100S。
Note that the cross-sectional compressibility (RA, ) is expressed by the following formula: RA<m=SO knee-axu-X 100S.

で表わされるものである。It is expressed as

つまシ、この発明は[特定量のC成分と、Nb及びT]
酸成分1種以上を同時に含有する鋼においては、加工温
度と加工量(断面圧縮率)を適正に選んで熱間圧延した
後、オーステナイト状態から直ちに直接焼入れすれば、
その後電気炉加熱のようにゆっくりとした加熱速度で加
熱しても、AC3点以上[A、C3点+200℃〕以下
(オーステナイト結晶粒粗大化開始温度以下)の温度に
加熱後焼入れる処理を少なくとも1回以上繰り返せば鋼
が非常に細粒化するので、これをAC1点以下の温度で
焼戻しすれば非常に微細な焼戻しマルテンサイト組織(
或いは、焼戻しマルテンサイトと焼戻し低温ベイナイト
の混合組織)となって、強度と靭性な共に具備せしめる
ことが可能になる」という事項を骨子としたものである
。もちろん、直接焼入れの後の焼入れに際して、急速加
熱処理を採用すれば一層の細粒組織が得られることは当
然のことである。
Tsumashi, this invention [a specific amount of C component, Nb and T]
For steels that simultaneously contain one or more acid components, if the processing temperature and amount of processing (sectional compression ratio) are selected appropriately, hot rolling is performed, and then directly quenched from the austenitic state.
After that, even if heated at a slow heating rate such as electric furnace heating, at least a quenching process is performed after heating to a temperature of AC3 points or higher [A, C3 points + 200°C] or lower (lower than the austenite crystal grain coarsening starting temperature). If repeated one or more times, the steel will become very fine-grained, so if it is tempered at a temperature below AC1, a very fine tempered martensitic structure (
Or, it becomes a mixed structure of tempered martensite and tempered low-temperature bainite), which makes it possible to have both strength and toughness. Of course, it is a matter of course that an even finer grain structure can be obtained by employing rapid heating treatment during quenching after direct quenching.

また、この発明の方法において、直接焼入れの後、ゆっ
くりとした加熱速度での焼入れ処理を2回以上繰り返す
場合には、2回目以降n回目の焼入れに際してのオース
テナイト化のだめの加熱温度を(n−1)回目のオース
テナイト化加熱温度未満とするのが好ましく、このよう
にすることによって鋼の組織は一層細粒で、かつ整粒と
なり、靭性がより改善されることとなる。
In addition, in the method of this invention, when the quenching treatment at a slow heating rate is repeated two or more times after direct quenching, the heating temperature of the austenitizing lump during the second and nth quenching is set to (n- 1) It is preferable to set the temperature to be lower than the second austenitizing heating temperature. By doing so, the structure of the steel becomes finer and more uniform, and the toughness is further improved.

更に、置き割れ等を防止するだめのラフテンパーを実施
する際に、該ラフテンパーの条件をA1= T(Al 
+ tog t )なる式で計算されるA1が、 Ax<19. OX I O” を満足するように設定するのが好ましく、このようにす
ることによってラフテンパく−によるマルテンサイトラ
スや低温ベイナイトラスの崩れが小さく抑えられ、m回
目の焼入れで(m−1)回目よりも細粒な組織を得るこ
とができるのである。
Furthermore, when carrying out rough tempering to prevent cracks etc., the rough tempering conditions are A1=T(Al
+ tog t ) is calculated by the formula Ax<19. It is preferable to set the temperature so as to satisfy OX I O. By doing this, the collapse of martensite laths and low-temperature bainite laths due to rough tempering can be suppressed to a minimum, and the It is also possible to obtain a fine-grained structure.

次に、この発明の強靭鋼の製造方法において、鋼の化学
成分組成、及び圧延・熱処理条件を前記のように限定し
た理由を説明する。
Next, in the method for producing strong steel of the present invention, the reason why the chemical composition of the steel and the rolling and heat treatment conditions are limited as described above will be explained.

A、鋼の化学成分組成 ■ C C成分は、鋼の焼入れ性増加、強度増加に加えて、細粒
化のだめには欠くことのできないものであるが、その含
有量が0.1.51未満では、直接焼入れした後ゆつく
シした加熱速度の場合に1回以14− 上の繰返し焼入れ処理を行っても所望の細粒化が達成で
きず、壕だ強度低下及び焼入れ性劣化を来たすこととな
り、一方045%を越えて含有させると靭性劣化を招く
ようになることから、C含有量は0.15〜○45係と
定めた。
A. Chemical composition of steel■ C C component is essential for increasing the hardenability and strength of steel, as well as for grain refinement, but if its content is less than 0.1.51 However, if the heating rate is slow after direct quenching, the desired grain refinement cannot be achieved even if the quenching treatment is repeated once or more, resulting in a decrease in trench strength and deterioration of hardenability. On the other hand, if the C content exceeds 0.45%, the toughness deteriorates, so the C content was set at 0.15 to 0.45%.

■ 5I S1成分は、鋼の脱酸剤として有効なものであるほか、
強度及び焼入れ性を高める作用を有するものであるが、
その含有量が0.05%未満では前記作用に所望の効果
を得ることができず、他方100チを越えて含有させる
と靭性を劣化するようになるので、S1含有量を0.0
5〜1.00%と定めだ。
■ 5I S1 component is effective as a deoxidizing agent for steel, and
Although it has the effect of increasing strength and hardenability,
If the S1 content is less than 0.05%, the desired effect cannot be obtained, and if the S1 content exceeds 100%, the toughness will deteriorate, so the S1 content should be reduced to 0.0%.
It is set at 5% to 1.00%.

■ Mn Mn成分には、焼入れ性改善作用、強度及び靭性向上作
用、及び鋼の脱酸作用があるが、その含有量が03%未
満では前記作用に所望の効果が得られず、他方2.0係
を越えて含有されると逆に靭性の劣化を招くこととなる
ので、Mn含有量を0.3〜2.0係と定めた。
(2) Mn The Mn component has the effect of improving hardenability, improving strength and toughness, and deoxidizing steel, but if its content is less than 0.3%, the desired effects cannot be obtained; If the Mn content exceeds 0, the toughness will deteriorate, so the Mn content was set at 0.3 to 2.0.

■ AA AQ酸成分、鋼の脱酸の安定化、均質化及び細粒化を図
るために添加するものであるが、その含有量がo、 0
11未満では前記作用に所望の効果が得られず、他方0
.10 %を越えて含有させると脱酸効果は飽和してし
まい、また斤在物増大による疵の発生や靭性の劣化をも
招くことから、AC含有量を0.01〜0.10%と定
めた。
■ AA AQ acid component, added to stabilize the deoxidation of steel, homogenize it, and make it finer, but its content is o, 0.
If it is less than 11, the desired effect cannot be obtained, and if it is less than 0.
.. If the AC content exceeds 10%, the deoxidizing effect will be saturated and this will also lead to the occurrence of scratches and deterioration of toughness due to an increase in inclusions, so the AC content is set at 0.01 to 0.10%. Ta.

■ Nb、及びTl Nb及びT1成分には、鋼の強度増加作用、焼戻し軟化
抵抗の増大作用に加えて、組織を細粒化するという均等
な作用があるが、これらの元素の1種又は2種の合計含
有量がO,OO51未満では、直接焼入れした後、特に
ゆっくりとした加熱速度の場合、1回以上の繰返し焼入
れ処理を行っても所望の細粒化が達成できず、他方これ
らの元素の1種又は2種の合計含有量が0150%を越
えると前記作用にそれ以上の向上効果が得られないばか
りでなく、靭性劣化をも来たすようになるので、Nb及
びTiの1種又は2種の含有量を0.0 O5〜015
0%と定めだ。
■ Nb and Tl Nb and T1 components have the same effect of increasing the strength of steel, increasing resistance to temper softening, and refining the structure, but one or both of these elements If the total content of seeds is less than 51 O, OO, the desired grain refinement cannot be achieved after direct quenching, even with one or more repeated quenching treatments, especially at slow heating rates; If the total content of one or two of the elements exceeds 0.150%, not only will the above effects not be further improved, but the toughness will also deteriorate. The content of the two types is 0.0 O5~015
It is set at 0%.

■ P、及びS P及び8分は、鋼の靭性向上のためには可及的に少ない
方が好ましいものであるが、鋼の製造コストを考慮して
Pの上限を0.025%、Sの上限をo、 015 %
とそれぞれ定めた。
■ P and S It is preferable that P and 8 min be as small as possible in order to improve the toughness of the steel, but considering the manufacturing cost of the steel, the upper limit of P is set to 0.025% and S The upper limit of o, 015%
determined respectively.

@Cu、 Cr、 V’、 Mo、及びWこれらの成分
には鋼の強度を向上する作用があるので、必要に応じて
1種以上を添加含有せしめるものであるが、以下、個々
の元素についてその詳細な特性及び含有量限定理由を説
明する。
@Cu, Cr, V', Mo, and W These components have the effect of improving the strength of steel, so one or more of them may be added as needed, but the individual elements will be explained below. The detailed characteristics and reasons for limiting the content will be explained.

i) Cu Cu成分は、鋼の靭性をそれ程阻害することなく強度上
昇をもたらす好ましい元素であるが、その含有量が0.
05%未満では所望の効果を得ることができず、他方0
50チを越えて含有させると熱間加工性の劣化を招くよ
うになることから、Cu含有量を0.05〜0.50 
%と定めた。
i) Cu The Cu component is a preferable element that increases the strength of steel without significantly impairing its toughness, but if its content is 0.
If it is less than 0.05%, the desired effect cannot be obtained;
If Cu content exceeds 50%, hot workability will deteriorate, so the Cu content should be reduced to 0.05 to 0.50%.
%.

ij) Cr cr酸成分は、鋼の焼入れ性1強度、及び焼戻し軟化抵
抗を増大させる作用があるが、その含17− 有量が0.05%未満では前記作用に所望の効果を得る
ことができず、他方2.00%を越えて含有させると靭
性の劣化を招くことから、Cr含有量を005〜200
係と定めだ。
ij) Cr The Cr acid component has the effect of increasing the hardenability and temper softening resistance of steel, but if its content is less than 0.05%, the desired effect cannot be obtained in the above effects. On the other hand, if the Cr content exceeds 2.00%, the toughness will deteriorate, so the Cr content should be increased to
It is decided that he will be in charge.

:fり Mo、及びW MO及びW成分には、いずれも焼入れ性及び強度を上昇
させ、焼戻し軟化抵抗を増大するという均等な作用があ
るが、WはMoに対して原子量が約2倍であり効果の点
では、Mo含有量がWの半分で丁度均等となるものであ
る。そして、M。
:f Mo and W Both MO and W components have the same effect of increasing hardenability and strength and increasing resistance to temper softening, but W has an atomic weight approximately twice that of Mo. In terms of the dovetail effect, the Mo content is exactly half that of W, making it exactly the same. And M.

−4−V2Wの値が0,05%未満では前記作用に所望
の効果が得られず、MO−1−1//2Wで1.20%
を越えてMO及びWの1種以上を含有させても強度上昇
効果が飽和してしまう上、かえって靭性の劣化を招くよ
うになることから、MO及びWの1種又は2種の含有量
をMo+1/2 Wで0.05〜1.20係と定めた。
If the value of -4-V2W is less than 0.05%, the desired effect cannot be obtained in the above action, and MO-1-1//2W is 1.20%.
Even if one or more of MO and W is contained in an amount exceeding Mo+1/2 W was set at 0.05 to 1.20.

iv) v ■成分には、鋼の強度を上昇するとともに、焼戻し軟化
抵抗を増大する作用を有するもので18− あるが、その含有量が0.01%未満では前記作用に所
望の効果を得ることができず、他方、0.15%を越え
て含有させると靭性の劣化を招くようになることから、
■含有量を001〜○15%と定めた。
iv) Component 18- has the effect of increasing the strength of steel as well as its resistance to temper softening, but if its content is less than 0.01%, the desired effect cannot be obtained. On the other hand, if the content exceeds 0.15%, it will lead to deterioration of toughness.
■The content was determined to be 001 to ○15%.

■ Ca、及び希土類元素 これらの成分には、いずれも鋼中の介在物を球状化する
とともに鋼を清浄化して、圧延方向と直角をなす方向に
おける靭性を改善し鋼の異方性を小さくする作用がある
ので、必要に応じて1種以上添加含有せしめられるもの
であるが、いずれも0.001%未満の含有量では前記
作用に所望の効果を得ることができず、他方、いずれも
O○50係を越えて含有せしめると前記靭性改善効果が
飽和してしまうのみならず、酸化物等の非金属介在物が
増大して鋼の清浄性が低下するので、それぞれの含有量
をともに0001−0.050%と定めた。なお、希土
類元素はミツシュメタルの形で添加することが実用上好
捷しい手段である。
■ Ca and rare earth elements These components both spheroidize inclusions in the steel, clean the steel, improve toughness in the direction perpendicular to the rolling direction, and reduce the anisotropy of the steel. If necessary, one or more of them can be added and contained because they have a certain effect, but if the content of any of them is less than 0.001%, the desired effect cannot be obtained. ○ If the content exceeds 0.50%, not only will the toughness improvement effect be saturated, but also non-metallic inclusions such as oxides will increase and the cleanliness of the steel will decrease. -0.050%. Note that it is practically preferable to add the rare earth element in the form of metal.

■ B B成分には、鋼の焼入れ性を向上させて強度及び靭性夕
改善する作用があるので、必要に応じて添加含有せしめ
られる元素であるが、その含有量が0.0005%未満
では前記作用に所望の効果を得ることができず、他方0
0050%を越えて含有させてもそれ以上の向上効果が
もたらされないことから、B含有量を0.0005〜0
0050%と定めだ。
■ B The B component has the effect of improving the hardenability of steel and improving its strength and toughness, so it is an element that can be added as necessary. However, if its content is less than 0.0005%, the above-mentioned It is not possible to obtain the desired effect in the action, and on the other hand, 0
Since even if the B content exceeds 0.0050%, no further improvement effect will be brought about, the B content should be set at 0.0005 to 0.
It is set at 0050%.

なお、B処理を行った鋼の、場合には、鋼中のN含有量
(@カ(2,5X B(%)−1,5X 10−” )
以下テあるとA、c1点以下での焼戻し時に和犬なポロ
カーバイドが析出して所望の高靭性を有する鋼を得るこ
とができなくなる恐れがあシ、更にN含有量(2)が(
3XB(%)+1.2X10”” )以」二であるとB
の焼入れ性向上作用が十分に発揮されず、強度及び靭性
が劣化する恐れがでてくることがら、2、 5 X B
 (%) −ユ 5X10−”(N (!A<3XB(
働+1.2 X 10−2 なる制限を設けることが望ましい。
In addition, in the case of B-treated steel, the N content in the steel (@ka(2,5X B(%)-1,5X 10-")
If the following conditions exist, there is a risk that polocarbide will precipitate during tempering below point C1, making it impossible to obtain steel with the desired high toughness.
3XB (%) + 1.2X10””
2.5 X B
(%) -Yu 5X10-"(N (!A<3XB(
It is desirable to set a limit of +1.2 x 10-2.

また、この場合に、鋼が0.005%以上のT1を含ん
でいないならば、焼入れ加熱温度を1075℃以下にす
ることが望ましい。
In this case, if the steel does not contain T1 of 0.005% or more, it is desirable that the quenching heating temperature be 1075° C. or less.

B、圧延、及び熱処理条件 この発明の方法は、以上のように構成された鋼を溶製し
、通常の方法にて厚板、形鋼、鋼管等に圧延加工した後
、熱処理を施すものであるが、その圧延・熱処理条件は
次の通シである。
B. Rolling and heat treatment conditions In the method of the present invention, the steel constructed as described above is melted, rolled into thick plates, shaped steel, steel pipes, etc. by a conventional method, and then heat treated. However, the rolling and heat treatment conditions are as follows.

■ 圧延条件 圧延は、1100℃以下のオーステナイト温度域で、断
面圧縮率が20%以上になるように行うものであるが、
このようにすることによってはじめてオーステナイト粒
が微細になり、従って本発明成分鋼を熱間圧延後直ちに
オーステナイト状態から適当な冷却媒体で直接焼入れし
て生ずる低温変態組織をも微細にできるのである。そし
てこのことは、直接焼入れに際しての焼割れ感受性の低
減に有効であるという2次的効果をも生ずることとなる
■ Rolling conditions Rolling is carried out in the austenite temperature range of 1100°C or less and with a cross-sectional compressibility of 20% or more.
By doing so, the austenite grains become fine for the first time, and therefore, the low-temperature transformed structure produced by directly quenching the steel of the present invention from the austenitic state immediately after hot rolling with a suitable cooling medium can also be made fine. This also produces the secondary effect of being effective in reducing susceptibility to quench cracking during direct quenching.

そして、圧延温度が1100℃以下の温度域での断面圧
縮率が20%未満であると、所望の微細21− 組織を達成することができない。
If the cross-sectional compressibility in the rolling temperature range of 1100°C or less is less than 20%, the desired fine 21- structure cannot be achieved.

即ち、1100℃以下の温度域での断面圧縮率が20%
以−Fとなるような熱間圧延を行′って、そのままオー
ステナイト域から直接焼入れすれば、これに続いて、電
気炉加熱のようなゆっくりとした加熱速度であったとし
ても、A、c3点〜(Ac3点+200℃〕の温度域に
加熱後焼入れる処理を1回以上行えば、鋼材組織を極め
て細粒にできるのである。
In other words, the cross-sectional compressibility in the temperature range below 1100°C is 20%.
If hot rolling is carried out to obtain the following results, and then quenched directly from the austenite region, even if the heating rate is slow as in electric furnace heating, A, c3 If the treatment of heating and quenching in the temperature range from point to (Ac3 point + 200°C) is performed one or more times, the steel structure can be made extremely fine-grained.

このように、直接焼入れ処理に続く焼入れに際しての前
組織が微細な低温変態組織であれば、それも、そのラス
の崩れの小さい細粒組織であれば、次の焼入れによって
更に細粒の組織が得られるのである。
In this way, if the pre-structure during quenching following direct quenching is a fine low-temperature transformed structure, and if it is a fine-grained structure with small lath collapse, the next quenching will produce an even finer-grained structure. You can get it.

もちろん、直接焼入れによって粗大な低温変態組織を生
じても、次にA、c3点〜[Ac3点+200℃〕の温
度でオーステナイト化して焼入れる処理を1回以上繰り
返せばある程度の細粒組織を得ることができるが、その
効果は小さくなってしまう。
Of course, even if a coarse low-temperature transformed structure is produced by direct quenching, a certain degree of fine-grained structure can be obtained by repeating the process of austenitizing and quenching at a temperature between A and C3 points to [Ac3 point + 200℃] one or more times. It is possible, but the effect will be small.

■ 直接焼入れ処理後の、再度の焼入れ処理に22− おける焼入れ条件 焼入れ1/i、直接焼入れ材及び又は直接焼入れ後のラ
フテンパー材をAC3点〜[Ac3点+200℃〕の温
度に加熱して組織を完全にオーステナイト化した後、適
当な冷却媒体によって焼入れし、低温変態組織とする操
作を1回以上繰返すものであるが、その際の加熱温度が
Ac3点未満であると当然のことなからオーステナイト
化が達成できず、一方(Ac3点+200℃〕を越えて
加熱するとオーステナイト結晶粒が粗大化してし1つて
、本発明処理によっても所望の微細組織を得ることがで
きなくなる。
■ Quenching conditions for second quenching after direct quenching: Quenching 1/i, directly quenched material and/or rough tempered material after direct quenching are heated to a temperature of 3 AC to [3 AC + 200°C] to determine the structure. After completely austenitizing, the process of quenching with an appropriate cooling medium to obtain a low-temperature transformed structure is repeated one or more times, but if the heating temperature at that time is less than 3 points of Ac, it is natural that the austenite will not be formed. On the other hand, heating above the Ac3 point +200° C. causes the austenite crystal grains to become coarse, making it impossible to obtain the desired fine structure even by the treatment of the present invention.

このように、再度の焼入れ処理の加熱温度を上述のよう
に限定することによシ、電気炉加熱のようなゆっくりと
した加熱速度であっても、加熱焼入れを1回以上繰り返
すことで極微細な低温変態組織を実現することができ、
靭性を大幅に向上し得るのである。
In this way, by limiting the heating temperature for the second quenching treatment as described above, even at a slow heating rate such as electric furnace heating, ultra-fine particles can be obtained by repeating the heating quenching process one or more times. It is possible to realize a low-temperature transformed structure,
Toughness can be significantly improved.

なお、前にも述べたように、2回目以後の焼入れ時の加
熱は、前回のそれの温度よりも低くすることが好ましく
、これによって一層の細粒がっ整粒組織が実現され、鋼
材性能を向上することができる。
As mentioned earlier, it is preferable that the heating temperature for the second and subsequent quenching be lower than the temperature for the previous quenching.This will realize a finer grained structure and improve the performance of the steel material. can be improved.

■ 焼戻し条件 上述のような焼入れ処理によって得た微#1組織を、最
終的にAc1点以下の温度で焼戻し処理すれば、鋼に所
望の強度と靭性とが付与されるのである。
(2) Tempering conditions If the fine #1 structure obtained by the above-mentioned quenching treatment is finally tempered at a temperature below the Ac1 point, the desired strength and toughness will be imparted to the steel.

この場合、焼戻し温度がA、c4点を越えると鋼材強度
が大幅に変動し靭性も劣化することがら、該温度をAc
1点以下と定めだ。
In this case, if the tempering temperature exceeds the A and C4 points, the strength of the steel material will change significantly and the toughness will deteriorate;
The score is set at 1 point or less.

なお、ラフテンパーの温度は、先にも述べたように、 Al”” (A2 +Iogt ) なる式で計算されるAlが A、x < 19. OX 10” を満足するように設定するのが好ましい。As mentioned earlier, the temperature of rough tempering is Al"" (A2 + Iogt) Al calculated by the formula is A, x < 19. OX 10” It is preferable to set it so that it satisfies the following.

次に、この発明を実施例にょシ比較例と対比しながら具
体的に説明する。
Next, the present invention will be specifically explained by comparing it with Examples and Comparative Examples.

実施例 l まず、第1表に示す如き、本発明の範囲内の組成を有す
る鋼1及び2を溶製した後鋼片となし、これを1200
℃に均熱してから熱間圧延機にかけて、1100℃以下
での断面圧縮率が各種の値をとるように熱間圧延した。
Example 1 First, steels 1 and 2 having compositions within the range of the present invention as shown in Table 1 were melted and made into steel billets, which were then heated to 1200
After soaking at a temperature of 1,100° C., the material was hot-rolled using a hot rolling machine so that the cross-sectional compressibility at 1100° C. or lower took various values.

続いて、直ちに930℃がら水焼入れし、その後、0.
75℃/秒のゆっくシした加熱速度で920℃にまで加
熱し、20分間保持してから再度水焼入れを行った。
Subsequently, water quenching was immediately carried out at 930°C, and then 0.
It was heated to 920° C. at a slow heating rate of 75° C./sec, held for 20 minutes, and then water quenched again.

次いで、これを更に540〜580℃程度にて焼戻しし
て、各鋼材の引張強さをほぼ90 kgf/miに揃え
、これをシャルピー衝撃試験に供した。
Next, this was further tempered at about 540 to 580°C to adjust the tensile strength of each steel material to approximately 90 kgf/mi, and this was subjected to a Charpy impact test.

このようにして得られたシャルピー破面遷移温度と断面
圧縮率(RA)の関係を第1図に示した。
The relationship between the Charpy fracture transition temperature and the area compressibility (RA) thus obtained is shown in FIG.

第1図からも明らかなように、1100C以下25− での断面圧縮率(RA)が20%程度以上であれば、良
好な破面遷移温度を確保することができ、本発明法の効
果の大きいことがわかる。
As is clear from Fig. 1, if the cross-sectional compressibility (RA) at 25 - below 1100C is about 20% or more, a good fracture surface transition temperature can be secured, and the effect of the method of the present invention can be improved. You can see that it's big.

実施例 2 第1表に示される如き、本発明の範囲内の組成を有する
鋼3及び4を溶製した後鋼片となし、これを1220℃
に均熱した後熱間圧延機にかけて、1100℃以下での
断面圧縮率(RA)が各種の値をとるように熱間圧延し
た。
Example 2 Steels 3 and 4 having compositions within the range of the present invention as shown in Table 1 were melted into steel slabs, and heated at 1220°C.
After soaking, the sheets were hot-rolled using a hot rolling machine so that the cross-sectional compressibility (RA) at 1100° C. or lower took various values.

続いて、直ちに920℃から水焼入れし、その後、0.
5℃/秒のゆっくりした加熱速度で9oO℃に加熱し、
20分間保持してから再度水焼入れした。
Subsequently, water quenching was immediately performed at 920°C, and then water quenching was performed at 0.
heating to 9oO<0>C at a slow heating rate of 5[deg.]C/sec;
After holding for 20 minutes, water quenching was performed again.

次いで、これを更に540〜580℃程度にて焼戻しし
て、各鋼材の引張強さをほぼ90 kgf/maに揃え
、これをシャルピー衝撃試験に供した。
Next, this was further tempered at about 540 to 580°C to adjust the tensile strength of each steel material to approximately 90 kgf/ma, and this was subjected to a Charpy impact test.

このようにして得られたシャルピー破面遷移温度と断面
圧縮率(RA)の関係を第2図に示す。
The relationship between the Charpy fracture surface transition temperature and the area compressibility (RA) thus obtained is shown in FIG.

第2図からも、1100℃以下での断面圧縮率(RA)
が20%程度以上であれば、良好な破面遷移温度を確保
できることが明らかである。
From Figure 2, the cross-sectional compressibility (RA) below 1100℃
It is clear that a good fracture surface transition temperature can be ensured if the ratio is about 20% or more.

実施例 3 第2表に示す如き化学成分組成の鋼1〜61を通常の方
法によって溶製した。
Example 3 Steels 1 to 61 having the chemical compositions shown in Table 2 were melted by a conventional method.

これらを鋼片にしだ後、1200℃に均熱して熱間圧延
機にかけ、1100℃以下での断面圧縮率(RA、 )
が35チ程度になるように熱間圧延した。続いて、これ
を大気放冷し、第3表に示す温度から直接焼入れし、そ
の後、第3表に示す条件にて焼入れ・焼戻し処理を行っ
た。
After forming these into steel slabs, they were soaked at 1200°C and put through a hot rolling machine, and the cross-sectional compressibility (RA, ) at 1100°C or less was
It was hot rolled so that it had a thickness of about 35 inches. Subsequently, this was left to cool in the atmosphere and directly quenched at the temperature shown in Table 3, and then quenched and tempered under the conditions shown in Table 3.

これらのものについて、強度及び靭性を測定し、その結
果を第3表に併せて示した。
The strength and toughness of these materials were measured, and the results are also shown in Table 3.

第3表に示される結果からも、鋼の化学成分組成及び圧
延・熱処理条件が本発明範囲内であれば、優れた強度と
靭性とのバランスを有する鋼材が得られるのに対して、
前記条件が1つでも本発明の範囲から外れていると、満
足し得る特性を有した鋼材が得られないことが明白であ
る。
The results shown in Table 3 also show that if the chemical composition and rolling/heat treatment conditions of the steel are within the range of the present invention, a steel material with an excellent balance of strength and toughness can be obtained.
It is clear that if even one of the above conditions deviates from the scope of the present invention, a steel material with satisfactory properties cannot be obtained.

実施例 4 前記第2表中の本発明対象鋼である鋼45及び46を、
それぞれ1200℃に均熱後、熱間圧延機にかけて、1
100℃以下での断面圧縮率(RA )が30%程度に
なるように熱間圧延した。その後、大気放冷して第4表
に示す温度から直接焼入れし、その後、更に第4表に示
す条件にて焼入れ焼戻し処理して強度及び靭性を測定し
、その結果を第4表に併せて示した。
Example 4 Steels 45 and 46, which are the steels subject to the present invention in Table 2 above, were
After soaking at 1200℃, each
Hot rolling was performed so that the cross-sectional compressibility (RA) at 100° C. or lower was approximately 30%. After that, it was left to cool in the atmosphere and directly quenched at the temperature shown in Table 4, and then further quenched and tempered under the conditions shown in Table 4 to measure its strength and toughness.The results are also shown in Table 4. Indicated.

第4表に示される結果からも、本発明の方法によって強
度及び靭性の優れた鋼材を製造できることが明らかであ
る。
It is clear from the results shown in Table 4 that steel materials with excellent strength and toughness can be produced by the method of the present invention.

実施例 5 前記第2表中の本発明対象鋼である鋼46を、1250
℃に均熱してから熱間圧延機にかけて、1100℃以下
での断面圧縮率(RA)が10%と35%になるように
熱間圧延した。続いて、これを大気放冷し、950℃又
は250℃から直接焼入れした後、更に第5表に示す条
件にて焼入れ処理して、オーステナイト粒度番号(AS
TMA)を測定した。
Example 5 Steel 46, which is the steel subject to the present invention in Table 2 above, was converted to 1250
After soaking at a temperature of 0.degree. C., the material was hot-rolled using a hot rolling mill so that the area compressibility (RA) at 1100.degree. C. or less was 10% and 35%. Subsequently, this was left to cool in the atmosphere, directly quenched from 950°C or 250°C, and further quenched under the conditions shown in Table 5 to obtain an austenite grain size number (AS
TMA) was measured.

得られた結果も、第5表に併せて示した。The obtained results are also shown in Table 5.

35− 第5表に示される結果からも、本発明方法によれば極め
て細粒の組織が得られることが明らかである。
35- It is clear from the results shown in Table 5 that an extremely fine-grained structure can be obtained by the method of the present invention.

実施例 6 前記第2表中の本発明対象鋼である鋼45を使用し、こ
れを120.0℃に加熱後熱間圧延機にかけて、]、1
0.0℃以下での断面圧縮率(RA)が40%程度にな
るように熱間圧延した。続いて、850℃の温度からこ
れを直接焼入れし、その後第6表に示す条件にてラフテ
ンパー処理を行い、次いで焼入れ・焼戻し処理した後、
その強度及び靭性を測定した。
Example 6 Steel 45, which is the steel subject to the present invention in Table 2 above, was heated to 120.0°C and then subjected to a hot rolling mill.
Hot rolling was performed so that the cross-sectional compressibility (RA) at 0.0° C. or lower was approximately 40%. Subsequently, this was directly quenched at a temperature of 850°C, then rough tempered under the conditions shown in Table 6, and then quenched and tempered.
Its strength and toughness were measured.

得られた結果を第6表に併せて示した。The obtained results are also shown in Table 6.

第6表に示される結果からは、直接焼入れの後に行う焼
入れ処理の前に、置き割れ防止等の意味でラフテンパー
処理を施しても強度及び靭性の優れた鋼材が得られるこ
とが明白であシ、また、この際のラフテンパー条件を、 A4<19. OX 10 にすると、強度・靭性バランスの一層優れた鋼材37− となることもわかる。
From the results shown in Table 6, it is clear that steel materials with excellent strength and toughness can be obtained even if rough tempering treatment is performed to prevent cracking, etc., before the quenching treatment performed after direct quenching. Also, the rough tempering conditions at this time are A4<19. It can also be seen that when OX 10 is used, the steel material 37- has an even better balance of strength and toughness.

上述のように、この発明によれば、N1等の高価な元素
を添加することなく、しかも格別な設備や煩わしい作業
を要することもなく、極寒冷地等で使用する大型溝端物
等に好適な強靭鋼を、簡雫容易に、かつ低コストで製造
できるなど、工業上有用な効果がもたらされるのである
As described above, according to the present invention, there is no need to add expensive elements such as N1, and there is no need for special equipment or troublesome work. Industrially useful effects such as the ability to produce strong steel easily and at low cost are brought about.

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

第1図及び第2図は、共に、本発明実施例における、]
100℃以下での断面圧縮率(%)と破面遷移温度(ト
)との関係を示すグラフである。 出願人 住友金属工業株式会社 代理人 富 1) 和 夫 ほか1名 39− cつ。)I雷jr運(U承ψ
FIG. 1 and FIG. 2 are both in the embodiment of the present invention]
It is a graph showing the relationship between cross-sectional compressibility (%) and fracture surface transition temperature (g) at 100° C. or lower. Applicant Sumitomo Metal Industries Co., Ltd. Agent Tomi 1) Kazuo and one other person 39-c. ) I thunder jr luck (U jo ψ

Claims (1)

【特許請求の範囲】[Claims] (1)重量割合で、 C:0.15〜0.45%。 Si:0.05〜1.00係。 Mn: 0.3〜2.0 %。 AQ : 0.01〜0.10%。 Nb及びTiの1種又は2種: 0、005〜0.150%。 を含有し、必要によシ更に、 第1区分・・・ Cu: 0.05〜0.50%。 Cr 二 〇、05 〜2゜ 00%。 v:0゜01〜0.15%。 MO及びWの1種又は2種: l− Mo −1−1/2Wで0.05〜1.20%。 第2区分・・・ Ca: 0.001〜0.050 %。 希土類元素:O,OO1〜0.050%。 第3区分・・・ B:0.0005〜O,OO50係。 のうちの1種以上をも含むとともに、 Fe及び不可避不純物:残シ。 から成シ、かつ不純物中のP及びSの含有量がそれぞれ
、 P:0.025%以下。 S:0.015%以下。 である鋼を、1.100℃以下での断面圧縮率(RA)
が20%以上となるように熱間圧延した後、直接オース
テナイト状態から焼入れし、続いて、Ac3点〜〔Ac
3点+200℃〕の温度域に加熱後焼入れする処理を更
に1回以上繰返して行い、その後ACI点以下の温度で
焼戻し処理を行うことを特徴とする強靭鋼の製造方法。 (→ 重量割合で、 C:0.15〜0.45 %。 Si:O○ 5〜1.00 %。 Mn: 0.3〜2.0 %。 At! : 0.0 1−0.1 0 %。 Nb及びT]の1種又は2種: 0.005〜0]50%。 を含有し、必要により更に、 第1区分・・ Cu:005〜050%。 Cr : 0.05〜2.00 %。 V : 0.01〜0.15%。 Mo及びWの1種又は2種: M o +VWで0.05〜120係。 第2区分・・・ Ca: 0.001〜0.050%。 希土類元素: 0.001−0.050係。 第3区分・・・ B:0.0005〜0. OO50係。 のうちの1種以上をも含むとともに、 Fe及び不可避不純物:残り。 から成り、かつ不純物中のP及びSの含有量がそれぞれ
、 P:0025係以下。 S:0015%以下。 である鋼を、]−]−〇〇℃以下での断面圧縮率(RA
)が20%以上となるように熱間圧延した後、直接オー
ステナイト状態から焼入れし、続いて、AC1点以下の
温度での焼戻しと、A、C3点〜(Ac3点+200℃
〕の温度域に加熱後焼入れする処理とをこの順序で1回
以上繰返して行い、その後再度A、c1点以下の温度で
焼戻し処理を行うことを特徴とする強靭鋼の製造方法。
(1) C: 0.15 to 0.45% by weight. Si: 0.05 to 1.00. Mn: 0.3-2.0%. AQ: 0.01-0.10%. One or both of Nb and Ti: 0.005 to 0.150%. Contains, if necessary, the first category... Cu: 0.05 to 0.50%. Cr 20,05~2゜00%. v: 0°01-0.15%. One or two of MO and W: l-Mo-1-1/2W at 0.05-1.20%. Second category... Ca: 0.001-0.050%. Rare earth element: O, OO1-0.050%. 3rd division... B: 0.0005~O, OO50 section. Contains one or more of the following: Fe and unavoidable impurities: Residues. The content of P and S in the impurities is P: 0.025% or less. S: 0.015% or less. The cross-sectional compressibility (RA) of steel at 1.100℃ or less
After hot rolling to 20% or more, quenching is performed directly from the austenitic state, followed by Ac 3 points ~ [Ac
3 points + 200°C] and then quenching is repeated one or more times, followed by tempering at a temperature below the ACI point. (→ Weight percentage: C: 0.15-0.45%. Si: O○ 5-1.00%. Mn: 0.3-2.0%. At!: 0.0 1-0.1 0%. One or two of Nb and T: 0.005-0]50%. If necessary, the first category Cu: 005-050%. Cr: 0.05-2 .00%. V: 0.01-0.15%. One or two types of Mo and W: Mo + VW of 0.05-120. Second category... Ca: 0.001-0. 050%. Rare earth elements: 0.001-0.050 ratio. Third category... B: 0.0005-0.OO50 ratio. Contains one or more of the following: Fe and unavoidable impurities: Remaining. and the content of P and S in the impurities is P: 0025% or less, S: 0015% or less.
) is 20% or more, then directly quenched from the austenitic state, followed by tempering at a temperature below AC1 point, A, C3 points ~ (Ac3 point + 200℃
A method for producing strong steel, which comprises heating the steel to a temperature range of 1 and then quenching the steel in this order one or more times, and then tempering the steel again at a temperature below point A and c1.
JP11565383A 1983-06-27 1983-06-27 Production of tough and hard steel Pending JPS609824A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP11565383A JPS609824A (en) 1983-06-27 1983-06-27 Production of tough and hard steel

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP11565383A JPS609824A (en) 1983-06-27 1983-06-27 Production of tough and hard steel

Publications (1)

Publication Number Publication Date
JPS609824A true JPS609824A (en) 1985-01-18

Family

ID=14667965

Family Applications (1)

Application Number Title Priority Date Filing Date
JP11565383A Pending JPS609824A (en) 1983-06-27 1983-06-27 Production of tough and hard steel

Country Status (1)

Country Link
JP (1) JPS609824A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01170256U (en) * 1988-05-23 1989-12-01
US5186768A (en) * 1990-06-14 1993-02-16 Sumitomo Metal Industries, Ltd. Flat spring hose clamp and manufacture of same
CN102776438A (en) * 2012-08-27 2012-11-14 内蒙古包钢钢联股份有限公司 Niobium-lanthanum microalloying Mn-B series superstrength steel plate and heat treatment technology thereof
WO2013133076A1 (en) 2012-03-07 2013-09-12 新日鐵住金株式会社 Method for producing high-strength steel material having excellent sulfide stress cracking resistance
JP2019504192A (en) * 2015-12-15 2019-02-14 ポスコPosco High hardness wear resistant steel with excellent toughness and cut crack resistance, and method for producing the same

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01170256U (en) * 1988-05-23 1989-12-01
US5186768A (en) * 1990-06-14 1993-02-16 Sumitomo Metal Industries, Ltd. Flat spring hose clamp and manufacture of same
WO2013133076A1 (en) 2012-03-07 2013-09-12 新日鐵住金株式会社 Method for producing high-strength steel material having excellent sulfide stress cracking resistance
US10287645B2 (en) 2012-03-07 2019-05-14 Nippon Steel & Sumitomo Metal Corporation Method for producing high-strength steel material excellent in sulfide stress cracking resistance
CN102776438A (en) * 2012-08-27 2012-11-14 内蒙古包钢钢联股份有限公司 Niobium-lanthanum microalloying Mn-B series superstrength steel plate and heat treatment technology thereof
JP2019504192A (en) * 2015-12-15 2019-02-14 ポスコPosco High hardness wear resistant steel with excellent toughness and cut crack resistance, and method for producing the same

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