JPH0694569B2 - Manufacturing method of steel with excellent low temperature toughness in the heat affected zone - Google Patents
Manufacturing method of steel with excellent low temperature toughness in the heat affected zoneInfo
- Publication number
- JPH0694569B2 JPH0694569B2 JP62042769A JP4276987A JPH0694569B2 JP H0694569 B2 JPH0694569 B2 JP H0694569B2 JP 62042769 A JP62042769 A JP 62042769A JP 4276987 A JP4276987 A JP 4276987A JP H0694569 B2 JPH0694569 B2 JP H0694569B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- steel
- toughness
- temperature
- affected zone
- 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
Landscapes
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Articles (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は小入熱溶接から大入熱溶接に至るまで熱影響部
（HAZ）の低温靭性が優れた鋼の製造法に関するもので
ある。Description: TECHNICAL FIELD The present invention relates to a method for producing a steel having excellent low temperature toughness in a heat affected zone (HAZ) from small heat input welding to large heat input welding.
（従来の技術） 低合金鋼のHAZ靭性は、（１）結晶粒のサイズ、（２）
高炭素島状マルテンサイト、上部ベイナイト（Bu）など
の硬化相の分散状態、（３）粒界脆化の有無、（４）元
素のミクロ偏析など種々の冶金学的要因に支配される。
なかでもHAZの結晶粒のサイズは低温靭性に大きな影響
を与えることが知られており、HAZ組織を微細化するた
めに数多くの技術が開発実用化されている。(Prior Art) HAZ toughness of low alloy steel is (1) grain size, (2)
It is governed by various metallurgical factors such as high carbon island martensite, dispersed state of hardened phase such as upper bainite (Bu), (3) presence or absence of grain boundary embrittlement, and (4) microsegregation of elements.
Especially, it is known that the size of HAZ crystal grains has a great influence on the low temperature toughness, and many techniques have been developed and put to practical use for refining the HAZ structure.
TiNなど高温でも比較的に安定な窒化物を鋼中に微細分
散させ、これによつてHAZのオーステナイト（γ）粒の
粗大化を抑制する技術は、とくに有名である。しかしHA
Zの1400℃以上に加熱される領域では、TiNは粗大化もし
くは溶解し、γ粒の粗化抑制能力は消失する。The technology that finely disperses nitrides such as TiN, which are relatively stable even at high temperatures, in the steel and thereby suppresses the coarsening of the austenite (γ) grains of HAZ is particularly famous. But HA
In the region where Z is heated to 1400 ° C or higher, TiN coarsens or dissolves, and the ability to suppress γ grain coarsening disappears.
このため溶融線近傍での靭性劣化が大きく、HAZの全域
で安定して高靭性を得ることができない。すなわち溶融
線近傍に切欠を入れたシヤルピー試験やCTOD試験におい
て頻度は少ないが、低い値が出現し溶接鋼構造物の安全
性の観点から好ましくない。For this reason, the toughness deteriorates largely in the vicinity of the fusion line, and stable high toughness cannot be obtained in the entire HAZ. That is, although it is infrequent in a shearpy test or a CTOD test in which a notch is provided near the melting line, a low value appears, which is not preferable from the viewpoint of safety of the welded steel structure.
これに対してTi酸化物（主としてTi2O）を微細分散させ
た（特願59−203099号（特開昭61−79745号公報））は
溶融線近傍でもHAZ組織を小さくすることができ、TiN鋼
に比較して優れた低温靭性が得られる。しかし、この鋼
においても大入熱溶接HAZの靭性はシヤルピー遷移温度
−15〜−35℃程度であり、十分とは言えない。この主な
理由は後述するように鋼成分にNbを必須の元素として含
有していないためである。On the other hand, fine dispersion of Ti oxide (mainly Ti 2 O) (Japanese Patent Application No. 59-203099 (Japanese Patent Application Laid-Open No. 61-79745)) can reduce the HAZ structure even near the melting line. Superior low temperature toughness is obtained compared to TiN steel. However, even in this steel, the toughness of the high heat input welding HAZ is not sufficient because the shear transition temperature is about -15 to -35 ° C. The main reason for this is that the steel composition does not contain Nb as an essential element as described later.
このように現在のところ小〜大入熱溶接において溶融線
近傍までHAZ組織を安定して微細化する技術は存在せ
ず、新知見に基づく新しい鋼の開発が強く望まれてい
る。As described above, at present, there is no technique for stably refining the HAZ structure in the vicinity of the fusion line in small to large heat input welding, and the development of new steel based on new knowledge is strongly desired.
（発明が解決しようとする問題点） 本発明は小〜大入熱溶接においてHAZ靭性の極めて優れ
た鋼を安価に製造する技術を提供するものである。本発
明法で製造した鋼は、溶接時に溶融線近傍においてもHA
Z組織が微細化し、HAZの全域で優れた低温靭性を示す。(Problems to be Solved by the Invention) The present invention provides a technique for inexpensively producing steel having excellent HAZ toughness in small to large heat input welding. The steel produced by the method of the present invention has a HA
The Z structure becomes finer, and excellent low temperature toughness is exhibited throughout the HAZ.
（問題点を解決するための手段作用） 本発明の要旨は、重量％で、C;0.01〜0.15％、Si;0.5％
以下、Mn;0.5〜2.0％、P;0.025％以下、S;;0.005％以
下、Al;0.004％以下、Nb;0.005〜0.060％、Ti;0.005〜
0.030％、N;0.0010〜0.0065％、O;0.0015〜0.0060％を
含有し、且つ、 −0.010％≦（Ti）−２（Ｏ）−3.4（Ｎ）≦＋0.015％ を満足し、残部が不可避的不純物からなる実質的にAlを
含有しない鋼を連続鋳造法によってスラブとし、これを
1250℃以下の温度で再加熱後、加工熱処理することを特
徴とする溶接熱影響部の低温靭性が優れた鋼の製造法で
ある。(Means and Actions for Solving Problems) The gist of the present invention is, by weight%, C: 0.01 to 0.15%, Si: 0.5%.
Below, Mn; 0.5-2.0%, P; 0.025% or less, S ;; 0.005% or less, Al; 0.004% or less, Nb; 0.005-0.060%, Ti; 0.005-
0.030%, N; 0.0010 to 0.0065%, O; 0.0015 to 0.0060%, and -0.010% ≤ (Ti) -2 (O) -3.4 (N) ≤ + 0.015% with the balance being Steel made of unavoidable impurities and containing substantially no Al was slabed by the continuous casting method.
It is a method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which is characterized by performing reheating at a temperature of 1250 ° C or less and then performing heat treatment.
更に本発明は重量％で、V;0.005〜0.10％、Ni;0.05〜2.
00％、Cu;0.05〜1.00％、Cr;;0.05〜1.00％、Mo;0.05〜
0.40％、B;0.0003〜0.0020％の一種または二種以上を含
有するものである。Furthermore, the present invention is, by weight, V; 0.005-0.10%, Ni; 0.05-2.
00%, Cu; 0.05 to 1.00%, Cr ;; 0.05 to 1.00%, Mo; 0.05 to
0.40%, B; 0.0003 to 0.0020% of one kind or two or more kinds are contained.
更に本発明は重量％で、Ca;0.0005〜0.0050％、REM;0.0
005〜0.0050％の一種または二種を含有するものであ
る。Furthermore, the present invention is, by weight%, Ca; 0.0005 to 0.0050%, REM; 0.0
It contains 005 to 0.0050% of one or two kinds.
発明者らの研究によれば、HAZ靭性は、１）鋼の化学成
分、２）組織（結晶粒の大きさと硬化相の分布状態）に
大きく依存し、鋼成分の適正化とこれによる結晶粒の微
細化がHAZの高靭性化に不可欠であると考えられた。そ
こで鋼中Ti酸化物を微細に分散させ、これによつてHAZ
組織を微細化する新しい方法を発明した。According to the research conducted by the inventors, the HAZ toughness largely depends on 1) the chemical composition of the steel, 2) the structure (the size of the crystal grains and the distribution state of the hardening phase), and the optimization of the steel components and the resulting crystal grains It was considered that the refinement of Al was indispensable for the toughness of HAZ. Therefore, the Ti oxide in the steel is finely dispersed, which results in HAZ
We invented a new method to refine the texture.
Ti酸化物（主としてTi2O3）はγ粒の粗大化抑制能力は
小さいが、γ−α変態時にγ粒内に存在するTi2O3を核
として、放射状に微細なアシキユラーフエライト（AF）
が生成し、HAZ組織を著しく微細化する。Ti oxides (mainly Ti 2 O 3 ) have a small ability to suppress the coarsening of γ grains, but with Ti 2 O 3 existing in the γ grains at the time of the γ-α transformation as nuclei, radial fine Acquiular ferrule ( AF)
Are generated, and the HAZ structure is remarkably refined.
Ti2O3は溶融線近傍の1400℃以上の加熱される領域（粗
粒域）でも安定であり、この領域でも組織の微細化に効
果を発揮する。またTi,O,Nのバランスが適正であると微
細なTiNも生成し、これは1350℃以下に加熱されたHAZ
（亜粗粒域）のγ粒の粗大化を抑制してHAZ組織を微細
化する。Ti 2 O 3 is stable even in a region (coarse grain region) heated to 1400 ° C. or higher near the melting line, and also in this region, it is effective in refining the structure. Fine TiN is also produced when the balance of Ti, O, and N is proper, and this is due to HAZ heated below 1350 ℃.
The HAZ structure is refined by suppressing the coarsening of γ grains in the (sub-coarse grain region).
その結果、HAZ組織は全域にわたつて微細化し、極めて
優れた低温靭性が得られる。As a result, the HAZ structure becomes finer over the entire area and extremely low temperature toughness is obtained.
特願59−203099号（特開昭61−79745号公報）のように
製鋼におけるTi添加時のO,Al,Si量を限定せずに、通常
の製鋼法において鋼中にTi2O3,TiNを微細分散させるた
めには、とくにTi,OおよびＮ量とそのバランスの適正化
が必須である。このためTi,O,N量を、それぞれTi:0.005
−0.030％,O:0.0015−0.0060％,N:0.0010−0.0065％に
限定し、且つそのバランスを−0.010％≦〔Ti〕−２
〔Ｏ〕−3.4〔Ｎ〕≦＋0.015％とする必要がある。As in Japanese Patent Application No. 59-203099 (Japanese Patent Laid-Open No. 61-79745), the amounts of O, Al, and Si at the time of adding Ti in steelmaking are not limited, and Ti 2 O 3 , In order to finely disperse TiN, it is essential to optimize the amounts of Ti, O and N and their balance. Therefore, the Ti, O, and N contents were changed to Ti: 0.005
-0.030%, O: 0.0015-0.0060%, N: 0.0010-0.0065%, and the balance is -0.010% ≤ [Ti] -2
[O] -3.4 [N] ≦ + 0.015% is required.
Ti,O,N量の下限はTi2O3,TiNを生成するための必要最少
量である。Tiの上限はTiCの生成による低温靭性の劣化
を防止するためであり、Ｏの上限は非金属介在物の生成
による鋼の清浄度、靭性の劣化を防止するためである。
またＮ量の上限は、固溶ＮによるHAZ靭性の劣化を防止
するために0.0065％とした。The lower limit of the amount of Ti, O, N is the minimum amount necessary for producing Ti 2 O 3 , TiN. The upper limit of Ti is to prevent the deterioration of the low temperature toughness due to the formation of TiC, and the upper limit of O is to prevent the deterioration of the cleanliness and toughness of the steel due to the formation of non-metallic inclusions.
Further, the upper limit of the amount of N is set to 0.0065% in order to prevent deterioration of HAZ toughness due to solid solution N.
しかし単に個々の元素量を限定するだけでは微細なTi2O
3,TiNの両析出物を同時に安定して得ることができない
ので、Ti,O,N量のバランスを−0.010％≦〔Ti〕−２
〔Ｏ〕−3.4〔Ｎ〕≦＋0.015％に限定した。Ti,O,N量
が、この範囲にあるとHAZ靭性は飛躍的に向上する。However, if the amount of individual elements is simply limited, fine Ti 2 O
Since both 3 and TiN precipitates cannot be obtained stably at the same time, the balance of Ti, O and N contents is -0.010% ≤ [Ti] -2
It was limited to [O] -3.4 [N] ≤ + 0.015%. If the Ti, O, and N contents are in this range, the HAZ toughness will be dramatically improved.
上式はTi2O3,TiNのみが生成すると考えたとき化学量論
的に見たTiの過、不足量を表現したものである。下限は
Ti量の不足によるTi2O3,TiNの生成量の不足を防ぐため
であり、上限は過剰のTiによるTiCの析出を防止するた
めである。しかし、たとえばTi2O3,TiNが鋼中に微細分
散していても基本成分が適当でないと優れたHAZ靭性は
得られない。The above formula expresses stoichiometric excess and deficiency of Ti when it is considered that only Ti 2 O 3 and TiN are produced. The lower limit is
This is to prevent the generation amount of Ti 2 O 3 and TiN from being insufficient due to the insufficient amount of Ti, and the upper limit is to prevent the precipitation of TiC due to excess Ti. However, even if, for example, Ti 2 O 3 and TiN are finely dispersed in the steel, excellent HAZ toughness cannot be obtained if the basic components are not appropriate.
以下、この点について説明する。Hereinafter, this point will be described.
Ｃの下限0.01％は、母材および溶接部の強度の確保なら
びにNb,Vなどの添加時に、これらの効果を発揮させるた
めの最少量である。しかしＣ量が多過ぎると、母材の低
温靭性に悪影響をおよぼすだけでなく溶接性、HAZ靭性
も劣化させるので、上限を0.15％とした。Ｃ量が多いと
HAZに高炭素島状マルテンサイト、擬似パーライト
（Ｐ′）が生成して低温靭性を著しく劣化させる。The lower limit of 0.01% of C is the minimum amount for ensuring the strength of the base material and the welded portion and exerting these effects when Nb, V and the like are added. However, if the C content is too large, not only the low temperature toughness of the base metal is adversely affected, but also the weldability and HAZ toughness deteriorate, so the upper limit was made 0.15%. When the amount of C is large
High-carbon island martensite and pseudo-pearlite (P ') are formed in the HAZ, which significantly deteriorates low temperature toughness.
Siは脱酸上、鋼に含まれる元素であるが、多く添加する
と溶接性、HAZ靭性が劣化するため、上限を0.5％に限定
した。鋼の脱酸はTiのみでも十分可能であり、高炭素島
状マルテンサイトの生成を防止してHAZ靭性を改善する
観点から0.15％以下が望ましい。Si is an element contained in steel for deoxidation, but if added in large amounts, the weldability and HAZ toughness deteriorate, so the upper limit was limited to 0.5%. Deoxidation of steel is sufficiently possible with only Ti, and 0.15% or less is desirable from the viewpoint of preventing the formation of high carbon island martensite and improving the HAZ toughness.
Mnは強度、靭性を確保する上で不可欠な元素であり、そ
の下限は0.5％である。HAZ靭性を改善するには、γ粒界
に生成する粗大な初析フエライトを防止する必要がある
が、Mn添加は、これを抑制する効果がある。しかしMn量
が多過ぎると焼入性が増加して溶接性、HAZ靭性を劣化
させるだけでなく、スラブの中心偏析を助長するので上
限を2.0％とした。Mn is an essential element for ensuring strength and toughness, and its lower limit is 0.5%. In order to improve the HAZ toughness, it is necessary to prevent the coarse proeutectoid ferrite generated at the γ grain boundary, but the addition of Mn has the effect of suppressing this. However, if the Mn content is too large, not only the hardenability increases, the weldability and HAZ toughness deteriorate, but also the center segregation of the slab is promoted, so the upper limit was made 2.0%.
本発明鋼において不純物であるP,Sをそれぞれ0.025％以
下、0.005％以下とした理由は、母材、溶接部の低温靭
性をより一層向上させるためである。Ｐ量の低減は、HA
Zにおける粒界破壊を減少させ、Ｓ量の低減は、粒界フ
エライトの生成を抑制する傾向がある。最も好ましいP,
S量は、それぞれ0.01％,0.002％以下である。The reason that the impurities P and S in the steel of the present invention are 0.025% or less and 0.005% or less, respectively, is to further improve the low temperature toughness of the base material and the welded portion. Reduction of P amount is due to HA
The reduction of grain boundary fracture in Z and the reduction of S amount tend to suppress the production of grain boundary ferrite. Most preferred P,
The amounts of S are 0.01% and 0.002% or less, respectively.
Alは、一般に脱酸上鋼に含まれる元素であるが、本発明
鋼では好ましくない元素であり、その上限を0.004％と
した。これはAlが鋼中に含まれているとＯと結合してTi
2O3ができないためである。脱酸はTiだけでも可能であ
り、本発明においてAl量は少ないほど良い。Although Al is an element generally contained in deoxidized upper steel, it is an unfavorable element in the steel of the present invention, and its upper limit was set to 0.004%. This is because when Al is contained in the steel, it combines with O to form Ti
This is because 2 O 3 cannot be done. Deoxidation is also possible with Ti alone, and in the present invention, the smaller the amount of Al, the better.
Nbは本発明鋼において必須の元素であり、Nbを添加する
ことなく優れたHAZ靭性を得ることは不可能である。Nb
はγ粒界に生成するフエライトを抑制し、Ti2O3を核と
する微細なAFの生成を促進する働きがある。この効果を
得るためには最低0.005％のNb量が必要である。しかし
ながらNb量が多過ぎると、逆に微細なAFの生成を妨げる
ので、その上限を0.060％とした。Nb is an essential element in the steel of the present invention, and it is impossible to obtain excellent HAZ toughness without adding Nb. Nb
Has a function of suppressing the ferrite generated at the γ grain boundary and promoting the generation of fine AF having Ti 2 O 3 as a nucleus. To obtain this effect, a minimum Nb content of 0.005% is required. However, if the amount of Nb is too large, the formation of fine AF is adversely affected, so the upper limit was made 0.060%.
つぎにV,Ni,Cu,Cr,Mo,Bを添加する理由について説明す
る。Next, the reason for adding V, Ni, Cu, Cr, Mo, B will be explained.
基本となる成分にV,Cr,Mo,Bを添加する主たる目的は、
本発明鋼の母材強度を向上させるためである。The main purpose of adding V, Cr, Mo, B to the basic components is
This is to improve the base metal strength of the steel of the present invention.
ＶはVNおよびV3C4等の析出物を生成し、母材強度を向上
させるが、その添加量が多すぎるとHAZの靭性ばかりか
母材の靭性も害するので上限は0.1％である。しかし、
0.005未満では、母材強度向上の効果が少ないため0.005
％が下限である。V forms precipitates such as VN and V 3 C 4 and improves the base metal strength, but if the addition amount is too large, not only the HAZ toughness but also the base metal toughness are impaired, so the upper limit is 0.1%. But,
If it is less than 0.005, the effect of improving the base metal strength is small, so 0.005
% Is the lower limit.
CrやMo,Bは焼入性を増大させ、母材強度を向上させるた
めである。しかしながら、多すぎると溶接性やHAZ靭性
を害するので、その上限はCr1.0％、Mo0.4％、B0.002％
である。また、Cr,Moともに0.05％未満では、その効果
が少ないので0.05％下限で、Ｂは0.0003％が下限であ
る。This is because Cr, Mo and B increase hardenability and improve the base metal strength. However, if it is too large, the weldability and HAZ toughness are impaired, so the upper limits are Cr1.0%, Mo0.4%, B0.002%.
Is. If both Cr and Mo are less than 0.05%, the effect is small, so the lower limit is 0.05%, and the lower limit for B is 0.0003%.
さらに、基本となる成分にNiやCuを添加する主たる目的
は、溶接性、HAZ靭性に悪影響をおよぼすことが少な
く、マトリックスに固溶して母材の強度、靭性を向上さ
せるためである。Furthermore, the main purpose of adding Ni or Cu to the basic components is to have a small adverse effect on weldability and HAZ toughness, and to improve the strength and toughness of the base metal by forming a solid solution in the matrix.
しかしながら、Niは2.0％を超えると溶接性を害し、コ
スト面からも好ましくないため、Cuは1.0％を超えると
熱間圧延時にCu−クラックが発生し、製造困難となるた
め、上限をそれぞれNi2.0％、Cu1.0％とした。また、Ni
もCuも0.05％未満では、効果が少ないため、0.05％を下
限とした。However, if Ni exceeds 2.0%, the weldability is impaired, and it is not preferable in terms of cost.If Cu exceeds 1.0%, Cu-cracks occur during hot rolling, which makes manufacturing difficult. 0.0% and Cu1.0%. Also, Ni
If Cu and Cu are less than 0.05%, the effect is small, so 0.05% was made the lower limit.
基本となる成分にCa,REMを添加する主たる目的は、延伸
介在物（MnS）の形態を制御し低温靭性を向上させるほ
か、耐水素誘起割れ性の改善にも効果を発揮する。しか
しながら、Ca量が0.005％、REM量が0.005％を超えると
酸化物が多量に生成して、鋼の靭性や溶接性にも悪影響
するのでCa0.005％、REM0.005％を上限とした。また、C
aやREMが少ないと効果がないので、Ca0.0005％、REM0.0
005％を下限とした。The main purpose of adding Ca and REM to the basic components is to control the morphology of stretched inclusions (MnS) to improve low temperature toughness and also to improve hydrogen-induced cracking resistance. However, when the amount of Ca exceeds 0.005% and the amount of REM exceeds 0.005%, a large amount of oxide is generated, which adversely affects the toughness and weldability of steel. Therefore, the upper limits are 0.005% Ca and 0.005% REM. Also, C
If there is little a or REM, there is no effect, so Ca0.0005%, REM0.0
The lower limit was 005%.
鋼の成分を上記のように限定しても、製造法が適切でな
ければ溶接前の鋼中に微細なTi2O3,TiNを分散させるこ
とはできない。このため製造条件についても限定する必
要がある。Even if the steel components are limited as described above, fine Ti 2 O 3 and TiN cannot be dispersed in the steel before welding unless the manufacturing method is appropriate. Therefore, it is necessary to limit the manufacturing conditions.
まず、この鋼は工業的には連続鋳造法で製造することが
必須須である。この理由は、連続鋳造法では溶鋼の凝固
冷却速度が速くスラブ中に微細なTi2O3,TiNが多量に得
られるためである。大型鋼塊による造塊−分塊法では、
Ti2O3,TiNをスラブ中に微細分散させることは難しい。First, industrially, it is essential to manufacture this steel by the continuous casting method. The reason for this is that in the continuous casting method, the solidification cooling rate of molten steel is fast and a large amount of fine Ti 2 O 3 and TiN is obtained in the slab. In the ingot-segmentation method using a large steel ingot,
It is difficult to finely disperse Ti 2 O 3 and TiN in a slab.
連続鋳造法の場合、スラブ厚によつて冷却速度が異なる
が、HAZ靭性の観点からその厚みは350mm以下が望まし
い。さらにスラブの再加熱温度を1250℃以下とする必要
がある。これ以上の温度で再加熱するとTiNが粗大化し
て、溶接前の鋼中に微細なTiNがなくなり、HAZの亜粗粒
域における組織の微細化が不可能になるためである。In the case of the continuous casting method, the cooling rate differs depending on the slab thickness, but the thickness is preferably 350 mm or less from the viewpoint of HAZ toughness. Furthermore, the reheating temperature of the slab must be 1250 ° C or lower. This is because if reheated at a temperature higher than this, TiN becomes coarse and fine TiN disappears in the steel before welding, and it becomes impossible to refine the structure in the HAZ sub-coarse grain region.
なお本発明においては、スラブの再加熱は必ずしも実施
する必要はなく、ホツトチヤージ圧延やダイレクト圧延
を行なつても全く問題はない。In the present invention, it is not always necessary to reheat the slab, and there is no problem even if hot charge rolling or direct rolling is performed.
つぎにスラブ再加熱後の圧延法については、いわゆる加
工熱処理が必須である。これは、たとえば優れたHAZ靭
性が得られても、母材の靭性が劣つていると鋼材として
は不十分なためである。母材の低温靭性を優れたものと
するには加工熱処理によつて鋼の結晶粒を微細化する必
要がある。Next, so-called thermomechanical treatment is essential for the rolling method after the slab is reheated. This is because, for example, even if excellent HAZ toughness is obtained, if the base material has poor toughness, it is insufficient as a steel material. In order to improve the low temperature toughness of the base material, it is necessary to refine the crystal grains of steel by thermomechanical treatment.
加工熱処理の方法としては、１）制御圧延、２）制御圧
延−加速冷却、３）圧延直接焼入−焼戻などが挙げられ
るが、最も好ましいのは制御圧延と加速冷却の組み合わ
せである。Examples of the method of thermo-mechanical treatment include 1) controlled rolling, 2) controlled rolling-accelerated cooling, 3) direct rolling quenching-tempering, and the most preferable is a combination of controlled rolling and accelerated cooling.
なお、この鋼を製造後、脱水素などの目的でAc1変態点
以下の温度に再加熱しても、本発明の特徴を損なうもの
ではない。Even if the steel is reheated to a temperature not higher than the Ac 1 transformation point for the purpose of dehydrogenation or the like after the production, it does not impair the characteristics of the present invention.
（実施例） 転炉−連続鋳造−厚板工程で種々の鋼成分の鋼板（厚み
32mm）を製造し、溶接熱サイクル再現装置を使用してHA
Z靭性を調査した。(Example) Steel plates of various steel components (thickness in the converter-continuous casting-thick plate process
32mm) and HA using a welding heat cycle reproduction device
The Z toughness was investigated.
再現熱サイクルは、板厚1/4tから採取した試験片を用い
ピーク温度（最高到達温度）1400℃および1300℃,800−
500℃の冷却時間192秒で行なつた。この条件は溶接入熱
200KJ/cmにほぼ相当し、またピーク温度1400℃,1300℃
は、それぞれ実際の溶接HAZの粗粒域（溶融線近傍）、
亜粗粒域に相当する。The simulated thermal cycle was performed using test pieces taken from a plate thickness of 1/4 t, and peak temperatures (maximum temperature reached) of 1400 ° C and 1300 ° C, 800-
The cooling time was 500 ° C and the cooling time was 192 seconds. This condition is welding heat input
Almost equivalent to 200KJ / cm, and peak temperature 1400 ℃, 1300 ℃
Are the coarse-grained areas of the actual welded HAZ (near the melting line),
Corresponds to the sub-coarse grain region.
表１に実施例を示す。Examples are shown in Table 1.
本発明法で製造した鋼板（本発明鋼）は全て良好な母材
特性およびHAZ靭性を有するのに対して、本発明法によ
らない比較鋼は母材特性あるいはHAZ靭性が劣り、厳し
い環境下で使用される鋼板として適切でない。The steel sheets produced by the method of the present invention (invention steels) all have good base material properties and HAZ toughness, whereas the comparative steels not produced by the method of the present invention have inferior base material properties or HAZ toughness and are subject to severe environmental conditions. Not suitable as a steel plate used in.
比較鋼において鋼16はC,Si量が多過ぎるために、とくに
ピーク温度1400℃の再現HAZの靭性が悪い。また鋼17はM
n量が高いために低Ｃにもかかわらず、再現HAZの靭性が
劣る。鋼18は本発明の必須の元素であるNbを含まないた
めに粒界フエライトが大きく、再現HAZ靭性は著しく悪
い。Among the comparative steels, steel 16 has too much C and Si, and therefore the toughness of the reproduced HAZ at the peak temperature of 1400 ° C is particularly poor. Steel 17 is M
Despite the low C due to the high n content, the toughness of the reproduced HAZ is poor. Steel 18 has a large grain boundary ferrite because it does not contain Nb, which is an essential element of the present invention, and reproducible HAZ toughness is extremely poor.
鋼19,20の再現HAZ靭性は比較的良好であるが、鋼19はＳ
量が高いために、また鋼20はTi量、ｆ（Ti）が高いため
に本発明鋼におよばない。Reproduced HAZ toughness of steels 19 and 20 is relatively good, but steel 19 has S
Steel 20 is inferior to the steel of the present invention because of its high amount and because of its high Ti content and f (Ti).
鋼21,22はピーク温度1300℃の再現HAZの靭性が十分でな
い。これは鋼21ではTi量が、鋼22ではＮ量が少なく微細
なTiNの量が不足しているためである。Steels 21 and 22 do not have sufficient toughness in the reproduced HAZ with a peak temperature of 1300 ℃. This is because the amount of Ti in steel 21 is small and the amount of N in steel 22 is small and the amount of fine TiN is insufficient.
鋼23はAl量が高く、Ti2O3が生成しないためにピーク温
度1400℃の再現HAZ靭性が著しく劣る。鋼24はｏ量が多
過ぎるために再現HAZ靭性がいま一歩である。また鋼25
は鋼成分は適当であるが、スラブ再加熱温度が高過ぎる
ために、TiNの粗大化が著しくピーク温度1300℃の再現H
AZ靭性が悪い。Steel 23 has a high Al content and does not form Ti 2 O 3, so the reproducible HAZ toughness at a peak temperature of 1400 ° C is extremely poor. Since the steel 24 has too much o, the reproduced HAZ toughness is another step. Also steel 25
Although the steel composition is appropriate, the slab reheating temperature is too high, and TiN is significantly coarsened.
AZ Toughness is poor.
本発明は厚板ミルに適用することが最も好ましいが、ホ
ツトコイル、形鋼などにも適用可能である。The present invention is most preferably applied to a thick plate mill, but is also applicable to hot coils, shaped steel and the like.
また、この方法で製造した厚鋼板は海洋構造物、圧力容
器、ラインパイプなど厳しい環境下で使用される溶接鋼
構造物に用いることができる。Further, the thick steel plate manufactured by this method can be used for a welded steel structure used in a severe environment such as an offshore structure, a pressure vessel, and a line pipe.
（発明の効果） 本発明により、母材はもとより溶接部の全域において優
れた低温靭性を有する鋼を大量、且つ安価に製造するこ
とが可能になつた。その結果、極寒地、海上などの厳し
い環境下で使用される溶接鋼構造物の安全性を大きく向
上させることができた。 (Effects of the Invention) According to the present invention, it becomes possible to manufacture a large amount of steel having excellent low temperature toughness not only in the base metal but also in the entire welded portion at low cost. As a result, it was possible to greatly improve the safety of welded steel structures used in severe environments such as extremely cold regions and the sea.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｃ２２Ｃ 38/58 (72)発明者 山本 広一 神奈川県相模原市淵野辺５−10−１ 新日 本製鐵株式会社第二技術研究所内 (72)発明者 三村 宏 神奈川県相模原市淵野辺５−10−１ 新日 本製鐵株式会社第二技術研究所内 (56)参考文献 特開 昭61−79745（ＪＰ，Ａ) 特公 昭60−1929（ＪＰ，Ｂ２) 特公 昭57−40210（ＪＰ，Ｂ２)─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification number Internal reference number FI Technical indication location C22C 38/58 (72) Inventor Hirokazu Yamamoto 5-10-1 Fuchinobe, Sagamihara-shi, Kanagawa Shin Nihon (2) Inside the Second Technology Research Laboratory of Steel Co., Ltd. (72) Inventor Hiroshi Mimura 5-10-1 Fuchinobe, Sagamihara City, Kanagawa Inside Second Research Laboratory of Nippon Steel Co., Ltd. (56) Reference JP-A-61-79745 (JP , A) JP 60-1929 (JP, B2) JP 57-40210 (JP, B2)
Claims (8)
にAlを含有しない鋼を連続鋳造法によってスラブとし、
これを1250℃以下の温度で再加熱後、加工熱処理するこ
とを特徴とする溶接熱影響部の低温靭性の優れた鋼の製
造法。1. By weight%, C; 0.01 to 0.15% Si; 0.5% or less Mn; 0.5 to 2.0% P; 0.025% or less S; 0.005% or less Al; 0.004% or less Nb; 0.005 to 0.060% Ti; 0.005 ~ 0.030% N; 0.0010-0.0065% O; 0.0015-0.0060% and -0.010% ≤ (Ti) -2 (O) -3.4 (N) ≤ + 0.015% with the balance iron And a steel that does not substantially contain Al consisting of unavoidable impurities as a slab by a continuous casting method,
A method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which comprises reheating this at a temperature of 1250 ° C or lower and then subjecting it to thermomechanical treatment.
にAlを含有しない鋼を連続鋳造法によってスラブとし、
これを1250℃以下の温度で再加熱後、加工熱処理するこ
とを特徴とする溶接熱影響部の低温靭性の優れた鋼の製
造法。2. By weight%, C; 0.01 to 0.15% Si; 0.5% or less Mn; 0.5 to 2.0% P; 0.025% or less S; 0.005% or less Al; 0.004% or less Nb; 0.005 to 0.060% Ti; 0.005 -0.030% N; 0.0010-0.0065% O; 0.0015-0.0060% V; 0.005-0.10% and -0.010% ≤ (Ti) -2 (O) -3.4 (N) ≤ + 0.015% Satisfying, the balance is made of steel containing iron and unavoidable impurities substantially Al-free steel into a slab by a continuous casting method,
A method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which comprises reheating this at a temperature of 1250 ° C or lower and then subjecting it to thermomechanical treatment.
にAlを含有しない鋼を連続鋳造法によってスラブとし、
これを1250℃以下の温度で再加熱後、加工熱処理するこ
とを特徴とする溶接熱影響部の低温靭性の優れた鋼の製
造法。3. By weight%, C; 0.01 to 0.15% Si; 0.5% or less Mn; 0.5 to 2.0% P; 0.025% or less S; 0.005% or less Al; 0.004% or less Nb; 0.005 to 0.060% Ti; 0.005 -0.030% N; 0.0010-0.0065% O; 0.0015-0.0060%, Cr; 0.05-1.00% Mo; 0.05-0.40% B; 0.0003-0.0020% One or more types are added, and -0.010 % Steel (Ti) -2 (O) -3.4 (N) ≦ + 0.015% and the balance of iron and unavoidable impurities, which is substantially free of Al, is formed into a slab by a continuous casting method.
A method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which comprises reheating this at a temperature of 1250 ° C or lower and then subjecting it to thermomechanical treatment.
にAlを含有しない鋼を連続鋳造法によってスラブとし、
これを1250℃以下の温度で再加熱後、加工熱処理するこ
とを特徴とする溶接熱影響部の低温靭性の優れた鋼の製
造法。4. By weight%, C; 0.01 to 0.15% Si; 0.5% or less Mn; 0.5 to 2.0% P; 0.025% or less S; 0.005% or less Al; 0.004% or less Nb; 0.005 to 0.060% Ti; 0.005 -0.030% N; 0.0010-0.0065% O; 0.0015-0.0060%, Ni; 0.05-2.00% Cu; 0.05-1.00%, and one or more of them are added, and -0.010% ≤ (Ti)- Steel satisfying 2 (O) -3.4 (N) ≦ + 0.015% with the balance being iron and unavoidable impurities and containing substantially no Al is made into a slab by a continuous casting method,
A method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which comprises reheating this at a temperature of 1250 ° C or lower and then subjecting it to thermomechanical treatment.
にAlを含有しない鋼を連続鋳造法によってスラブとし、
これを1250℃以下の温度で再加熱後、加工熱処理するこ
とを特徴とする溶接熱影響部の低温靭性の優れた鋼の製
造法。5. By weight%, C; 0.01 to 0.15% Si; 0.5% or less Mn; 0.5 to 2.0% P; 0.025% or less S; 0.005% or less Al; 0.004% or less Nb; 0.005 to 0.060% Ti; 0.005 -0.030% N; 0.0010-0.0065% O; 0.0015-0.0060%, Ca; 0.0005-0.0050% REM; 0.0005-0.0050% One or more additions, and -0.010% ≤ (Ti) -2 A steel which satisfies (O) -3.4 (N) ≦ 0.015% and the balance of which is iron and inevitable impurities and which does not substantially contain Al is made into a slab by a continuous casting method,
A method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which comprises reheating this at a temperature of 1250 ° C or lower and then subjecting it to thermomechanical treatment.
にAlを含有しない鋼を連続鋳造法によってスラブとし、
これを1250℃以下の温度で再加熱後、加工熱処理するこ
とを特徴とする溶接熱影響部の低温靭性の優れた鋼の製
造法。6. By weight%, C; 0.01 to 0.15% Si; 0.5% or less Mn; 0.5 to 2.0% P; 0.025% or less S; 0.005% or less Al; 0.004% or less Nb; 0.005 to 0.060% Ti; 0.005 ~ 0.030% N; 0.0010 ~ 0.0065% O; 0.0015 ~ 0.0060% V; 0.005 ~ 0.10%, Ca; 0.0005 ~ 0.0050% REM; 0.0005 ~ 0.0050% One or two kinds are added, and -0.010% Steel satisfying ≤ (Ti) -2 (O) -3.4 (N) ≤ + 0.015%, the balance of which is iron and unavoidable impurities and does not substantially contain Al is slab by continuous casting method,
A method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which comprises reheating this at a temperature of 1250 ° C or lower and then subjecting it to thermomechanical treatment.
にAlを含有しない鋼を連続鋳造法によってスラブとし、
これを1250℃以下の温度で再加熱後、加工熱処理するこ
とを特徴とする溶接熱影響部の低温靭性の優れた鋼の製
造法。7. By weight%, C; 0.01 to 0.15% Si; 0.5% or less Mn; 0.5 to 2.0% P; 0.025% or less S; 0.005% or less Al; 0.004% or less Nb; 0.005 to 0.060% Ti; 0.005 -0.030% N; 0.0010-0.0065% O; 0.0015-0.0060%, Cr; 0.05-1.00% Mo; 0.05-0.40% B; 0.0003-0.0020% One or more kinds of Ca, 0.0005 ~ 0.0050% REM; 0.0005 ~ 0.0050% of 1 type or 2 types are further added, and -0.010% ≤ (Ti) -2 (O) -3.4 (N) ≤ 0.015% is satisfied, and the balance is iron and unavoidable impurities. A steel containing substantially no Al is formed into a slab by a continuous casting method,
A method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which comprises reheating this at a temperature of 1250 ° C or lower and then subjecting it to thermomechanical treatment.
にAlを含有しない鋼を連鮮鋳造法によってスラブとし、
これを1250℃以下の温度で再加熱後、加工熱処理するこ
とを特徴とする溶接熱影響部の低温靭性の優れた鋼の製
造法。8. By weight%, C; 0.01 to 0.15% Si; 0.5% or less Mn; 0.5 to 2.0% P; 0.025% or less S; 0.005% or less Al; 0.004% or less Nb; 0.005 to 0.060% Ti; 0.005 ~ 0.030% N; 0.0010-0.0065% O; 0.0015-0.0060%, Ni; 0.05-2.00% Cu; 0.05-1.00% One or more kinds are added, Ca; 0.0005-0.0050% REM; 0.0005 ~ 0.0050% of 1 type or 2 types is further added, and -0.010% ≤ (Ti) -2 (O) -3.4 (N) ≤ + 0.015% is satisfied, and the balance is iron and inevitable impurities. A steel containing no Al in a slab by the continuous casting method,
A method for producing steel with excellent low-temperature toughness in the heat-affected zone of welding, which comprises reheating this at a temperature of 1250 ° C or lower and then subjecting it to thermomechanical treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62042769A JPH0694569B2 (en) | 1987-02-27 | 1987-02-27 | Manufacturing method of steel with excellent low temperature toughness in the heat affected zone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62042769A JPH0694569B2 (en) | 1987-02-27 | 1987-02-27 | Manufacturing method of steel with excellent low temperature toughness in the heat affected zone |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63210235A JPS63210235A (en) | 1988-08-31 |
| JPH0694569B2 true JPH0694569B2 (en) | 1994-11-24 |
Family
ID=12645179
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62042769A Expired - Lifetime JPH0694569B2 (en) | 1987-02-27 | 1987-02-27 | Manufacturing method of steel with excellent low temperature toughness in the heat affected zone |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0694569B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102124133A (en) * | 2008-03-31 | 2011-07-13 | 杰富意钢铁株式会社 | High-strength steel and its manufacturing method |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6415321A (en) * | 1987-07-08 | 1989-01-19 | Nippon Steel Corp | Production of steel for electron beam welding having excellent low-temperature toughness |
| JPH06104861B2 (en) * | 1989-03-28 | 1994-12-21 | 新日本製鐵株式会社 | Manufacturing method of V added high toughness high strength steel sheet |
| JPH02267220A (en) * | 1989-04-06 | 1990-11-01 | Nippon Steel Corp | Production of steel sheet for flash butt welding excellent in toughness at low temperature |
| JPH03162522A (en) * | 1989-11-22 | 1991-07-12 | Nippon Steel Corp | Manufacture of high tension steel plate having superior toughness of high heat input weld heat-affected zone |
| JPH0448048A (en) * | 1990-06-15 | 1992-02-18 | Sumitomo Metal Ind Ltd | Steel excellent in toughness in weld heat-affected zone and its manufacture |
| JP5031531B2 (en) * | 2007-11-20 | 2012-09-19 | 新日本製鐵株式会社 | Low yield ratio high strength steel sheet excellent in base metal low temperature toughness and HAZ low temperature toughness and its manufacturing method |
| JP6225439B2 (en) * | 2013-03-14 | 2017-11-08 | 新日鐵住金株式会社 | Steel plate with excellent toughness at the center of plate thickness and method for producing the same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS601929A (en) * | 1983-06-17 | 1985-01-08 | Japanese National Railways<Jnr> | Method and device for reducing echo of hybrid circuit |
| JPS6179745A (en) * | 1984-09-28 | 1986-04-23 | Nippon Steel Corp | Manufacture of steel material superior in welded joint heat affected zone toughness |
-
1987
- 1987-02-27 JP JP62042769A patent/JPH0694569B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102124133A (en) * | 2008-03-31 | 2011-07-13 | 杰富意钢铁株式会社 | High-strength steel and its manufacturing method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63210235A (en) | 1988-08-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3408385B2 (en) | Steel with excellent heat-affected zone toughness | |
| JPH11140580A (en) | Continuous cast slab for high-strength steel with excellent low-temperature toughness and its manufacturing method, and high-strength steel with excellent low-temperature toughness | |
| JPH02194115A (en) | Production of high-strength steel for low temperature service containing titanium oxide and excellent in toughness at weld zone | |
| JP7243826B2 (en) | steel plate | |
| JPH0642979B2 (en) | Manufacturing method of high strength steel for welding and low temperature containing titanium oxide | |
| JP2653594B2 (en) | Manufacturing method of thick steel plate with excellent toughness of weld heat affected zone | |
| JPH0541683B2 (en) | ||
| JP2005187853A (en) | Manufacturing method of high-strength thick steel plates with excellent heat-affected zone toughness for super high heat input welding | |
| JPH0860292A (en) | High-strength steel with excellent toughness | |
| JPH0694569B2 (en) | Manufacturing method of steel with excellent low temperature toughness in the heat affected zone | |
| JPH0527703B2 (en) | ||
| JPH03236419A (en) | Production of thick steel plate excellent in toughness in weld heat-affected zone and lamellar tear resistance | |
| JPH0757886B2 (en) | Process for producing Cu-added steel with excellent weld heat-affected zone toughness | |
| JP7265008B2 (en) | Steel material for pressure vessel excellent in resistance to hydrogen-induced cracking and its manufacturing method | |
| JPH09194990A (en) | High-strength steel with excellent toughness | |
| JPH021208B2 (en) | ||
| JPH0629480B2 (en) | Hot-rolled high-strength steel sheet excellent in strength, ductility, toughness, and fatigue characteristics, and method for producing the same | |
| JPS6117885B2 (en) | ||
| JPH0578740A (en) | Method for producing steel with excellent low temperature toughness in the heat affected zone | |
| JPH05195156A (en) | High-manganese ultrahigh tensile strength steel excellent in toughness in heat affected zone and its production | |
| JP3854412B2 (en) | Sour-resistant steel plate with excellent weld heat-affected zone toughness and its manufacturing method | |
| JP3882701B2 (en) | Method for producing welded structural steel with excellent low temperature toughness | |
| JPH093600A (en) | Weld heat-affected zone steel material with excellent toughness for welded structures | |
| JP3202310B2 (en) | High heat input welding | |
| JP2652538B2 (en) | Method for producing high-strength steel with excellent weldability and low-temperature toughness |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |