JP6079611B2 - Ni alloy clad steel plate excellent in low temperature toughness and HAZ toughness of base metal and corrosion resistance of laminated material, and method for producing the same - Google Patents

Ni alloy clad steel plate excellent in low temperature toughness and HAZ toughness of base metal and corrosion resistance of laminated material, and method for producing the same Download PDF

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JP6079611B2
JP6079611B2 JP2013261143A JP2013261143A JP6079611B2 JP 6079611 B2 JP6079611 B2 JP 6079611B2 JP 2013261143 A JP2013261143 A JP 2013261143A JP 2013261143 A JP2013261143 A JP 2013261143A JP 6079611 B2 JP6079611 B2 JP 6079611B2
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俊一 橘
俊一 橘
洋太 黒沼
洋太 黒沼
横田 智之
智之 横田
三田尾 眞司
眞司 三田尾
純二 嶋村
純二 嶋村
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JFE Steel Corp
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Description

本発明は、母材の低温靭性とHAZ靭性及び合せ材の耐食性に優れたNi合金クラッド鋼板およびその製造方法に関するものである。   The present invention relates to a Ni alloy clad steel plate excellent in low-temperature toughness and HAZ toughness of a base material and corrosion resistance of a laminated material, and a method for producing the same.

クラッド鋼板は母材の機械的特性と合せ材の耐食性を兼ね備え、かつ経済性に優れた高機能鋼板である。Ni合金クラッド鋼板の合せ材としてはAlloy825やAlloy625が代表的であるが、Alloy825クラッド鋼板はその合せ材の高耐食性能と経済性のバランスが優れることから、エネルギー開発分野の成長とともにパイプライン用途として需要が特に期待されている。近年、難採掘環境と呼ばれる領域においてもエネルギー資源開発が進んでおり、このような環境は、今まで以上に母材の低温靭性、特に脆性破壊の伝播停止特性や合せ材の耐食性が求められている。   The clad steel plate is a high-performance steel plate that combines the mechanical properties of the base material with the corrosion resistance of the laminated material and is excellent in economy. Alloys such as Alloy 825 and Alloy 625 are representative of Ni alloy clad steel plates, but Alloy 825 clad steel plates have a good balance of high corrosion resistance and economic efficiency, so they can be used as pipeline applications as the energy development field grows. Demand is particularly expected. In recent years, the development of energy resources has progressed even in a region called difficult mining environment, and such an environment requires more than ever the low temperature toughness of the base metal, especially the propagation stop property of brittle fracture and the corrosion resistance of the laminated material. Yes.

クラッド鋼板とは合せ材にステンレス鋼やNi合金、母材に低合金鋼材と、二種類の性質の異なる金属を張り合わせた鋼材である。クラッド鋼は、異種金属を金属学的に接合させたもので、めっきとは異なり剥離する心配がなく単一金属及び合金では達し得ない新たな特性を持たせることができる。   The clad steel plate is a steel material in which two kinds of metals having different properties, such as stainless steel and Ni alloy as a laminated material and a low alloy steel material as a base material, are bonded together. The clad steel is obtained by metallographically bonding dissimilar metals, and unlike the plating, there is no fear of peeling, and it can have new characteristics that cannot be achieved by a single metal and alloy.

クラッド鋼板は、使用環境毎の目的に合った機能を有する合せ材を選択することにより無垢材(全厚が合せ材の金属組織のような場合をいう)と同等の機能を発揮させることができる。さらに、クラッド鋼の母材には、耐食性以外の高靭性、高強度といった厳しい環境に適した炭素鋼や低合金鋼を適用することができる。   The clad steel sheet can exert the same function as a solid material (when the total thickness is like the metal structure of the laminated material) by selecting a laminated material having a function suitable for the purpose of each use environment. . Furthermore, carbon steel and low alloy steel suitable for severe environments such as high toughness and high strength other than corrosion resistance can be applied to the base material of the clad steel.

このように、クラッド鋼は、無垢材よりも合金元素の使用量が少なく、かつ、無垢材と同等の耐食性能を確保でき、さらに炭素鋼や低合金鋼と同等の強度や靭性を確保できるため、経済性と機能性が両立できるという利点を有する。   In this way, clad steel uses less alloying elements than solid wood, can ensure the same corrosion resistance as solid wood, and can also ensure the same strength and toughness as carbon steel and low alloy steel. , It has the advantage that economics and functionality are compatible.

以上から、高合金の合せ材を用いたクラッド鋼は非常に有益な機能性鋼材であると考えられており、近年そのニーズが各種産業分野で益々高まっている。   From the above, clad steel using a high alloy laminated material is considered to be a very useful functional steel material, and in recent years its needs have been increasing in various industrial fields.

しかしながら、合せ材であるNi合金の中でもAlloy825は、クラッド鋼板製造時の熱履歴によって炭化物としてM23(Mは金属元素を表す)が析出する。この炭化物は900℃に析出ノーズが存在し、耐食元素であるCr、Mo、Niを含有し、粒界に沿って析出するため、耐食性劣化の原因となる。 However, in the Ni alloy that is a laminated material, Alloy 825 precipitates M 23 C 6 (M represents a metal element) as carbides due to the thermal history during the production of the clad steel plate. This carbide has a precipitation nose at 900 ° C., contains corrosion-resistant elements such as Cr, Mo, and Ni, and precipitates along grain boundaries, which causes deterioration of corrosion resistance.

通常、無垢材であれば圧延後に溶体化処理を施し析出物を固溶させることができるが、クラッド鋼の場合には析出物が溶け込むような高温に加熱保持すると、母材である低合金鋼の結晶粒が粗大化し、機械的特性が著しく悪化するという問題がある。   Normally, solid materials can be subjected to solution treatment after rolling to solidify the precipitates, but in the case of clad steel, the low alloy steel, which is the base material, can be heated to a high temperature where the precipitates melt. There is a problem that the crystal grains become coarse and the mechanical properties are remarkably deteriorated.

このような背景から、以下に示すようなクラッド鋼板およびクラッド鋼板の製造方法が開示されている。   From such a background, the following clad steel plates and methods for producing clad steel plates are disclosed.

特許文献1および特許文献2には、クラッド鋼の母材の強度と低温靭性を達成する、焼入れ焼戻し処理で製造されたクラッド鋼およびその製造方法が開示されている。しかしながら、上述したように、特定の温度域で保持されると耐食性の劣化が生じるため、高耐食性を達成するためには、焼入れ処理や焼戻し処理を行わない方が良い。また、焼入れ焼戻し処理での製造方法では、低温靭性、特に脆性破壊の伝播停止性能を向上させるのには限界がある。   Patent Document 1 and Patent Document 2 disclose a clad steel manufactured by quenching and tempering and a method for producing the same, which achieves the strength and low temperature toughness of the base material of the clad steel. However, as described above, since the corrosion resistance deteriorates when held in a specific temperature range, in order to achieve high corrosion resistance, it is better not to perform quenching or tempering. In addition, in the manufacturing method by quenching and tempering, there is a limit to improving the low temperature toughness, particularly the propagation stopping performance of brittle fracture.

特許文献3には、母材にNbを0.08〜0.15質量%の範囲で含有した低合金鋼を用いて、1000℃以下での圧下比を3以上とし、圧延終了温度を900℃〜1000℃としたステンレス鋼またはニッケル合金を合せ材としたクラッド鋼板のTMCP(Thermo-mechanical control process)による製造方法が記載されている。しかしながら、Nbを0.08質量%以上含有すると、溶接熱影響部靭性が劣化するため、鋼構造物として用いる以上、Nb含有量は0.08質量%未満とすることが望ましい。但し、Nb含有量を下げた場合には、制御圧延による結晶粒の微細化のためには、より低温での圧延が必要となってくる。   In Patent Document 3, using a low alloy steel containing Nb in the range of 0.08 to 0.15 mass% as a base material, the rolling ratio at 1000 ° C. or less is set to 3 or more, and the rolling end temperature is 900 ° C. A manufacturing method by TMCP (Thermo-mechanical control process) of a clad steel plate made of stainless steel or nickel alloy with a temperature of ˜1000 ° C. is described. However, when Nb is contained in an amount of 0.08% by mass or more, the weld heat affected zone toughness deteriorates. Therefore, as long as it is used as a steel structure, the Nb content is preferably less than 0.08% by mass. However, when the Nb content is lowered, rolling at a lower temperature is required to refine crystal grains by controlled rolling.

特許文献4には、母材にCuを1.5質量%以下、Niを3.0%質量以下、Crを0.3質量%以下、Moを0.3質量%以下等を選択的に含有した低合金鋼を用いて、1100℃以上に加熱した後に、1000℃以上の温度範囲で圧下比を3以上とし、制御圧延として850℃以下から母材のAr点−20℃までの温度範囲で50%以上の圧下を施す、Ni合金クラッド鋼板のTMCPによる製造方法が記載されている。しかしながら、Cuは0.50質量%以上、Niは0.45質量%以上含有すると、溶接性が劣化するという問題がある。また、鋼構造物として重要な溶接熱影響部靭性(HAZ靭性)を確保する点については記載されていない。 Patent Document 4 selectively contains, in a base material, Cu of 1.5% by mass or less, Ni of 3.0% by mass or less, Cr of 0.3% by mass or less, Mo of 0.3% by mass or less, and the like. After heating to 1100 ° C or higher using the low-alloy steel, the rolling ratio is 3 or higher in a temperature range of 1000 ° C or higher, and the temperature range from 850 ° C or lower to Ar 3 point-20 ° C of the base metal as controlled rolling Describes a method for producing a Ni alloy clad steel plate by TMCP, which is subjected to a reduction of 50% or more. However, when Cu is contained in an amount of 0.50% by mass or more and Ni is contained in an amount of 0.45% by mass or more, there is a problem that weldability deteriorates. Moreover, it is not described about the point which ensures the weld heat affected zone toughness (HAZ toughness) important as a steel structure.

特開2006−328460号公報JP 2006-328460 A 特開2004−149821号公報JP 2004-149821 A 特開平5−261567号公報JP-A-5-261567 特開平5−245657号公報JP-A-5-245657

本発明は、圧延ままで、母材の低温靭性とHAZ靭性及び合せ材の耐食性を同時に満たしたNi合金クラッド鋼板およびその製造方法を提供する。   The present invention provides a Ni alloy clad steel sheet that satisfies the low temperature toughness and HAZ toughness of the base metal and the corrosion resistance of the laminated material at the same time, and a method for producing the same.

Ni合金クラッド鋼板は、無垢のNi合金や無垢の低合金鋼と異なり、圧延ままで、合せ材の耐食性の確保、母材の機械的特性の確保、複合材料としての接合性の確保の3つの特性を同時に満たす必要がある。発明者らは、かかる事情に鑑み、合せ材の耐食性については、炭化物を抑制するためにC含有量を低くし、さらに製造条件で圧延終了温度の低温化の防止、また、母材の機械的特性、特に低温靭性と溶接熱影響部(HAZ)の靭性の確保のために、母材の成分と製造条件の加熱温度と制御圧延条件の適正化、また、接合性については、製造条件のスラブ加熱温度と熱間圧延の温度範囲とその際の圧下比について鋭意検討し、全ての特性を満足する条件を知見した。   Unlike solid Ni alloy and solid low-alloy steel, Ni alloy clad steel plates are in the rolled state, ensuring the corrosion resistance of the laminated material, ensuring the mechanical properties of the base material, and ensuring the bondability as a composite material. It is necessary to satisfy the characteristics at the same time. In view of such circumstances, the inventors have reduced the C content in order to suppress carbides and further prevent the rolling end temperature from being lowered under production conditions, and the mechanical properties of the base material. Properties, especially low-temperature toughness and weld heat-affected zone (HAZ) toughness, optimization of base material components, heating conditions of manufacturing conditions and controlled rolling conditions, and slabs of manufacturing conditions We have intensively studied the heating temperature and the temperature range of hot rolling and the reduction ratio at that time, and have found the conditions that satisfy all the characteristics.

本発明は、このような知見に基づいて完成させたもので、その要旨は、以下の通りである。   The present invention has been completed based on such knowledge, and the gist thereof is as follows.

[1] Ni合金を合せ材とし、低合金鋼を母材とするクラッド鋼板において、前記母材の化学成分が質量%で、C:0.020〜0.100%、Si:0.10〜0.50%、Mn:0.75〜1.80%、P:0.015%以下、S:0.0030%以下、Cu:0.01〜0.50%、Ni:0.01〜0.45%、Cr:0.01〜0.50%、Mo:0.01〜0.50%、Nb:0.005〜0.080%、Ti:0.005〜0.030%、N:0.0010〜0.0060%、Al:0.070%以下、Ca:0.0010〜0.0040%を含有し、残部Fe及び不可避的不純物からなることを特徴とする母材の低温靭性とHAZ靭性及び合せ材の耐食性に優れたNi合金クラッド鋼板。   [1] In a clad steel plate using Ni alloy as a combination material and low alloy steel as a base material, the chemical composition of the base material is% by mass, C: 0.020 to 0.100%, Si: 0.10 0.50%, Mn: 0.75 to 1.80%, P: 0.015% or less, S: 0.0030% or less, Cu: 0.01 to 0.50%, Ni: 0.01 to 0 .45%, Cr: 0.01 to 0.50%, Mo: 0.01 to 0.50%, Nb: 0.005 to 0.080%, Ti: 0.005 to 0.030%, N: Low temperature toughness of the base material characterized by containing 0.0010 to 0.0060%, Al: 0.070% or less, Ca: 0.0010 to 0.0040%, and remaining Fe and inevitable impurities Ni alloy clad steel sheet with excellent HAZ toughness and corrosion resistance of laminated materials.

[2] さらに、前記Tiと前記Nとの質量%比であるTi/Nが2.00〜4.00の範囲にあることを特徴とする[1]記載の母材の低温靭性とHAZ靭性及び合せ材の耐食性に優れたNi合金クラッド鋼板。   [2] Further, Ti / N, which is a mass% ratio of Ti and N, is in the range of 2.00 to 4.00. Low-temperature toughness and HAZ toughness of base material according to [1] And Ni alloy clad steel plate with excellent corrosion resistance of laminated materials.

[3] 前記合せ材の化学成分が質量%で、C:0.020%以下、Si:0.05〜0.50%、Mn:0.10〜1.00%、P:0.030%以下、S:0.0050%以下、Ni:38.0〜46.0%、Cr:19.5〜23.5%、Mo:2.50〜3.50%、Cu:1.50〜3.00%、Al:0.01〜0.20%、Ti:0.60〜1.20%を含有し、残部Fe及び不可避的不純物からなることを特徴とする[1]または[2]に記載の母材の低温靭性とHAZ靭性及び合せ材の耐食性に優れたNi合金クラッド鋼板。   [3] The chemical composition of the laminated material is% by mass, C: 0.020% or less, Si: 0.05 to 0.50%, Mn: 0.10 to 1.00%, P: 0.030% Hereinafter, S: 0.0050% or less, Ni: 38.0 to 46.0%, Cr: 19.5 to 23.5%, Mo: 2.50 to 3.50%, Cu: 1.50 to 3 [1] or [2] characterized by containing 0.000%, Al: 0.01-0.20%, Ti: 0.60-1.20%, and the balance being Fe and inevitable impurities A Ni alloy clad steel sheet having excellent low-temperature toughness and HAZ toughness of the base material and corrosion resistance of the laminated material.

[4] [1]乃至[3]の何れかに記載のクラッド鋼板の素材を用いて、1050℃〜1150℃に加熱後、鋼板表面温度が950℃以上での圧下比を1.5以上とし、900℃以下の温度域における累積圧下率を50%以上、圧延終了温度を750℃以上とする熱間圧延を行った後に、冷却速度3℃/s以上、冷却停止温度600℃以下とする加速冷却を行った後に放冷することを特徴とする母材の低温靭性とHAZ靭性及び合せ材の耐食性に優れたNi合金クラッド鋼板の製造方法。   [4] Using the clad steel plate material according to any one of [1] to [3], after heating to 1050 ° C. to 1150 ° C., the rolling ratio when the steel plate surface temperature is 950 ° C. or higher is 1.5 or higher. , After hot rolling with a cumulative rolling reduction in a temperature range of 900 ° C. or lower being 50% or higher and a rolling end temperature of 750 ° C. or higher, an acceleration of cooling rate of 3 ° C./s or higher and cooling stop temperature of 600 ° C. or lower A method for producing a Ni alloy clad steel sheet excellent in low-temperature toughness and HAZ toughness of a base material and corrosion resistance of a laminated material, characterized by cooling after cooling.

本発明によれば、母材の化学成分としてCu、Ni、Cr、Moを必須元素として全て含有し、また、TMCP製造条件を適正化することで、圧延ままで、母材の低温靭性とHAZ靭性及び合せ材の耐食性を同時に満たしたNi合金クラッド鋼板を得ることができる。   According to the present invention, Cu, Ni, Cr, and Mo are all contained as essential elements as chemical components of the base material, and the low temperature toughness and HAZ of the base material are maintained in the rolled state by optimizing the TMCP manufacturing conditions. It is possible to obtain a Ni alloy clad steel plate that simultaneously satisfies the toughness and the corrosion resistance of the laminated material.

以下、本発明における成分の限定範囲について詳細に説明する。各元素の%表示は特に記載が無い限り質量%を意味する。   Hereafter, the limited range of the component in this invention is demonstrated in detail. Unless otherwise indicated, the% display of each element means mass%.

1.母材の化学成分について
C:0.020〜0.100%
Cは鋼の強度を向上させる有効な成分であり、0.020%未満では一般溶接用鋼としては強度が得られないため0.020%以上とする。一方、過剰なCの含有は母材ならびに熱影響部の靭性の劣化を招き、また、溶接性の観点からC量の低減が望ましいため上限を0.100%とする。なお、溶接性及びHAZ靭性の観点から、好ましくは0.020〜0.080%の範囲である。より好ましくは0.030〜0.080%の範囲である。
1. About the chemical composition of the base material C: 0.020 to 0.100%
C is an effective component for improving the strength of the steel. If it is less than 0.020%, the strength cannot be obtained as a general welding steel. On the other hand, excessive C content causes deterioration of the toughness of the base material and the heat-affected zone, and from the viewpoint of weldability, it is desirable to reduce the C content, so the upper limit is made 0.100%. In addition, from the viewpoint of weldability and HAZ toughness, it is preferably in the range of 0.020 to 0.080%. More preferably, it is 0.030 to 0.080% of range.

Si:0.10〜0.50%
Siは製鋼時の脱酸のために添加され、また、母材の強度確保に必要な成分であるため0.10%以上の含有が必要である。一方、0.50%を超えるSiの含有は靭性、加工性に悪影響を及ぼすためSi量は0.10〜0.50%の範囲とする。脱酸の効果と靭性の観点から好ましくは0.20〜0.40%の範囲である。
Si: 0.10 to 0.50%
Si is added for deoxidation at the time of steelmaking, and since it is a component necessary for ensuring the strength of the base material, it must contain 0.10% or more. On the other hand, the Si content exceeding 0.50% adversely affects toughness and workability, so the Si content is in the range of 0.10 to 0.50%. From the viewpoint of deoxidation effect and toughness, it is preferably in the range of 0.20 to 0.40%.

Mn:0.75〜1.80%
Mnは母材の強度及び靭性の確保に有効な成分として0.75%以上の含有が必要であるが、1.80%を超えるMnの含有は靭性、溶接性に悪影響を与えるため、Mn量は0.75〜1.80%の範囲とする。なお、好ましくは、1.00〜1.70%の範囲である。
Mn: 0.75 to 1.80%
Mn needs to be contained in an amount of 0.75% or more as an effective component for ensuring the strength and toughness of the base material. However, if Mn exceeds 1.80%, it adversely affects toughness and weldability. Is in the range of 0.75 to 1.80%. In addition, Preferably, it is 1.00 to 1.70% of range.

P:0.015%以下
母材ならびに溶接熱影響部靭性を確保するため、Pを極力低減することが望ましいが、過度の脱Pはコスト上昇を招くためP量は0.015%以下とする。好ましくは0.010%以下である。
P: 0.015% or less It is desirable to reduce P as much as possible in order to secure the toughness of the base metal and the weld heat affected zone. However, excessive P removal causes an increase in cost, so the amount of P is 0.015% or less. . Preferably it is 0.010% or less.

S:0.0030%以下
Sは鋼中不純物として不可避な元素であるが、低温靭性を確保するためにはS量は0.0030%以下とする。好ましくは0.0010%以下である。
S: 0.0030% or less S is an element that is unavoidable as an impurity in steel, but in order to ensure low temperature toughness, the amount of S is made 0.0030% or less. Preferably it is 0.0010% or less.

Cu:0.01〜0.50%
Cuは靭性の改善と強度の上昇に有効な元素の1つであるため、0.01%以上の含有が必要であるが、0.50%を超えて含有すると溶接性を阻害することがあるので、Cu量は0.01〜0.50%とする。好ましくは、0.10〜0.40%の範囲である。
Cu: 0.01 to 0.50%
Since Cu is an element effective for improving toughness and increasing strength, it is necessary to contain 0.01% or more, but if it exceeds 0.50%, weldability may be impaired. Therefore, the Cu amount is set to 0.01 to 0.50%. Preferably, it is 0.10 to 0.40% of range.

Ni:0.01〜0.45%
Niは靭性の改善と強度の上昇に有効な元素の1つであるため、0.01%以上の含有が必要であるが、0.45%を超えると効果が飽和し、また、Niの含有は製造コストを上昇させるため、Ni量は0.01〜0.45%の範囲とする。好ましくは、0.10〜0.40%の範囲である。
Ni: 0.01 to 0.45%
Since Ni is one of the elements effective for improving toughness and increasing strength, it is necessary to contain 0.01% or more, but if it exceeds 0.45%, the effect is saturated, and the content of Ni Increases the manufacturing cost, so the Ni content is in the range of 0.01 to 0.45%. Preferably, it is 0.10 to 0.40% of range.

Cr:0.01〜0.50%
Crは靭性の改善と強度の上昇に有効な元素の1つであるため、0.01%以上の含有が必要であるが、0.50%を超えて含有すると溶接熱影響部靭性を劣化させることがあるため、Cr量は0.01〜0.50%の範囲とする。好ましくは、0.05%〜0.35%の範囲である。
Cr: 0.01 to 0.50%
Since Cr is one of the elements effective for improving toughness and increasing strength, the content of 0.01% or more is necessary, but if it exceeds 0.50%, the weld heat affected zone toughness is deteriorated. Therefore, the Cr content is in the range of 0.01 to 0.50%. Preferably, it is 0.05 to 0.35% of range.

Mo:0.01〜0.50%
Moは母材の強度と靭性を安定的に向上させる元素であり、0.01%以上の含有が必要である。また、0.50%を超えて含有すると効果が飽和し、また、過剰な含有は溶接熱影響部靭性や溶接性を阻害するため、Mo量は0.01〜0.50%の範囲とする。なお、母材強度と靭性の観点から、好ましくは、0.05〜0.35%の範囲である。
Mo: 0.01 to 0.50%
Mo is an element that stably improves the strength and toughness of the base material and needs to be contained in an amount of 0.01% or more. Further, if the content exceeds 0.50%, the effect is saturated, and excessive content inhibits the weld heat affected zone toughness and weldability, so the Mo amount is in the range of 0.01 to 0.50%. . In addition, from a viewpoint of base material strength and toughness, it is preferably in the range of 0.05 to 0.35%.

Nb:0.005〜0.080%
Nbは細粒化による析出強化を通じて母材の強度および靭性を向上させるのに有効であるが、その量が0.005%未満ではその効果を有効に発揮することができない。一方、0.080%を超えると溶接熱影響部の靭性を劣化させるため、Nb量は0.005〜0.080%の範囲とする。好ましくは、0.010〜0.050%の範囲である。
Nb: 0.005 to 0.080%
Nb is effective in improving the strength and toughness of the base material through precipitation strengthening by refining, but if the amount is less than 0.005%, the effect cannot be exhibited effectively. On the other hand, if it exceeds 0.080%, the toughness of the weld heat-affected zone is deteriorated, so the Nb amount is in the range of 0.005 to 0.080%. Preferably, it is 0.010 to 0.050% of range.

Ti:0.005〜0.030%
TiはTiNを形成してスラブ加熱時や溶接熱影響部の粒成長を抑制し、結果としてミクロ組織の微細化をもたらして強度と母材ならびに溶接熱影響部の靭性を改善する効果がある。その含有量は0.005%未満では効果が少ないため0.005%以上含有させる。また、Tiの含有量が0.030%を超えると、かえって上記効果が得られないのみならず、靭性も劣化させる。したがって、Ti量は0.005〜0.030%の範囲とする。好ましくは、0.010〜0.020%の範囲である。
Ti: 0.005-0.030%
Ti forms TiN and suppresses grain growth at the time of slab heating or welding heat-affected zone, and as a result, it has the effect of reducing the microstructure and improving the strength, the base metal and the toughness of the welding heat-affected zone. If the content is less than 0.005%, the effect is small, so 0.005% or more is contained. On the other hand, if the Ti content exceeds 0.030%, not only the above effects can be obtained, but also the toughness is deteriorated. Therefore, the Ti amount is in the range of 0.005 to 0.030%. Preferably, it is 0.010 to 0.020% of range.

N:0.0010〜0.0060%
NはTiNとして析出することで溶接熱影響部靭性の向上に効果があるが、Nの含有量が0.0010%未満では効果が薄れるため下限を0.0010%とする。しかしながら0.0060%を超えると固溶Nが増大し溶接熱影響部靭性の低下がおこる。Tiの含有量と対応させるTiNの微細析出によるHAZ靭性の向上を考慮しN量は0.0010〜0.0060%の範囲とする。好ましくは0.0020〜0.0050%の範囲である。
N: 0.0010 to 0.0060%
N precipitates as TiN and is effective in improving the weld heat-affected zone toughness. However, if the N content is less than 0.0010%, the effect decreases, so the lower limit is made 0.0010%. However, if it exceeds 0.0060%, the solute N increases and the weld heat affected zone toughness decreases. Considering the improvement of HAZ toughness due to fine precipitation of TiN corresponding to the Ti content, the N content is set in the range of 0.0010 to 0.0060%. Preferably it is 0.0020 to 0.0050% of range.

Al:0.070%以下
Alは、製鋼過程の脱酸用として重要な元素であるとともに、溶接熱影響部の靭性向上にも効力を有する。しかし、0.070%を超えて含有しても溶接熱影響部の靭性改善効果は飽和するので、Al量は0.070%以下とする。一方、溶接熱影響部の靭性改善効果を得るためには、0.010%以上の含有が好ましい。
Al: 0.070% or less Al is an important element for deoxidation in the steelmaking process, and has an effect on improving the toughness of the weld heat affected zone. However, even if the content exceeds 0.070%, the effect of improving the toughness of the weld heat affected zone is saturated, so the Al content is 0.070% or less. On the other hand, in order to obtain the effect of improving the toughness of the weld heat affected zone, the content is preferably 0.010% or more.

Ca:0.0010〜0.0040%
Caは硫化物系介在物の形態を制御し母材の靭性と溶接熱影響部靭性を改善する効果があるため、0.0010%以上含有する。しかし、0.0040%を超えると効果が飽和し、逆に清浄度を低下させ溶接熱影響部靭性を劣化させるためCa量は0.0010〜0.0040%の範囲とする。好ましくは0.0020〜0.0030%の範囲である。
Ca: 0.0010 to 0.0040%
Ca has the effect of controlling the form of sulfide inclusions and improving the toughness of the base metal and the toughness of the weld heat affected zone, so it is contained in an amount of 0.0010% or more. However, if it exceeds 0.0040%, the effect is saturated, and conversely, the cleanness is lowered and the weld heat affected zone toughness is deteriorated, so the Ca content is made 0.0010 to 0.0040%. Preferably it is 0.0020 to 0.0030% of range.

Ti/N:2.00〜4.00
なお、TiおよびNは、各元素の含有量(質量%)を表す。
Ti及びNは、上記のようにTiNを生成してHAZの靱性を改善するのに重要な元素であり、該効果を充分に発揮するためには両元素の含有量の相関関係も重要となる。すなわち、質量%比で、Ti/Nが2.00未満であると結晶粒が粗大化し、靱性値が大きく低下することがある。また、Ti/Nが4.00を超えると同様の理由により靭性値が低下することがある。したがって、Ti/Nは2.00〜4.00の範囲とすることが好ましい。
Ti / N: 2.00 to 4.00
In addition, Ti and N represent content (mass%) of each element.
Ti and N are elements that are important for generating TiN and improving the toughness of HAZ as described above, and the correlation between the contents of both elements is also important in order to fully exhibit this effect. . That is, when the Ti / N ratio is less than 2.00 by mass%, the crystal grains are coarsened and the toughness value may be greatly reduced. Moreover, when Ti / N exceeds 4.00, the toughness value may decrease for the same reason. Therefore, Ti / N is preferably in the range of 2.00 to 4.00.

2.合せ材の化学成分について
C:0.020%以下
Cはクラッド鋼板の製造において、圧延の熱履歴で炭化物として粒界に析出し、耐食性を阻害するため多量の含有は避けるべき元素である。0.020%を超えて含有すると、炭化物の析出が促進されて耐食性が劣化するため、C量は0.020%以下とする。好ましくは、0.015%以下である。
2. Chemical component of laminated material C: 0.020% or less C is an element that should be avoided in the production of clad steel sheets because it precipitates at grain boundaries as carbides due to the thermal history of rolling and inhibits corrosion resistance. If the content exceeds 0.020%, precipitation of carbides is promoted and corrosion resistance deteriorates, so the C content is 0.020% or less. Preferably, it is 0.015% or less.

Si:0.05〜0.50%
Siは製造時の脱酸に有効な成分であり、0.05%以上の含有から効果が発現する。
しかしながら、0.50%を超えて含有すると非金属介在物として残存し、耐食性が劣化し、また熱間加工性も劣化するため、Si量は0.05〜0.50%の範囲とする。好ましくは0.05〜0.20%の範囲である。
Si: 0.05 to 0.50%
Si is an effective component for deoxidation during production, and the effect is manifested when the content is 0.05% or more.
However, if it exceeds 0.50%, it remains as a non-metallic inclusion, the corrosion resistance is deteriorated, and the hot workability is also deteriorated, so the Si amount is made 0.05 to 0.50%. Preferably it is 0.05 to 0.20% of range.

Mn:0.10〜1.00%
Mnは脱酸成分として必要な成分であり、0.10%以上の含有から効果が発現する。
しかしながら、1.00%を超えて含有するとMnS等の非金属介在物として残存し、耐食性が劣化し、また熱間加工性も劣化するため、Mn量は0.10〜1.00%の範囲とする。好ましくは0.10〜0.50%の範囲である。
Mn: 0.10 to 1.00%
Mn is a necessary component as a deoxidizing component, and the effect is manifested when the content is 0.10% or more.
However, if it exceeds 1.00%, it remains as a non-metallic inclusion such as MnS, corrosion resistance is deteriorated, and hot workability is also deteriorated, so the amount of Mn is in the range of 0.10 to 1.00%. And Preferably it is 0.10 to 0.50% of range.

P:0.030%以下
Pは不純物元素であり、熱間加工性劣化および粒界に偏析することによる耐食性の劣化原因となるため、その含有量は低いほど好ましい。したがって、P量は0.030%以下とする。好ましくは、0.020%以下である。
P: 0.030% or less P is an impurity element and causes deterioration of hot workability and corrosion resistance due to segregation at grain boundaries. Therefore, the lower the content, the better. Therefore, the P content is 0.030% or less. Preferably, it is 0.020% or less.

S:0.0050%以下
SはPと同様で不純物元素であり、熱間加工性劣化および粒界に偏析することによる耐食性の劣化原因となるため、その含有量は低いほど好ましい。したがって、S量は0.0050%以下とする。好ましくは、0.0010%以下である。
S: 0.0050% or less S is an impurity element similar to P, and causes deterioration in hot workability and corrosion resistance due to segregation at grain boundaries. Therefore, the lower the content, the better. Therefore, the S content is 0.0050% or less. Preferably, it is 0.0010% or less.

Ni:38.0〜46.0%
NiはNi合金の主成分であり耐全面腐食性を改善する。また、Crとの複合添加によってサワー環境中での耐応力腐食割れ感受性を改善する。しかしながら、Ni含有量が38.0%未満では、所望の耐食性能が得られない。一方、Niは高価な元素であるため、46.0%を超えて含有すると、経済的に不利である。したがって、Ni含有量は38.0〜46.0%とする。なお、Ni合金とは、合金成分のうちでNi含有量が最も多い合金をいう。
Ni: 38.0 to 46.0%
Ni is the main component of the Ni alloy and improves the overall corrosion resistance. In addition, the combined addition with Cr improves the stress corrosion cracking susceptibility in the sour environment. However, if the Ni content is less than 38.0%, the desired corrosion resistance cannot be obtained. On the other hand, since Ni is an expensive element, if it exceeds 46.0%, it is economically disadvantageous. Therefore, the Ni content is 38.0 to 46.0%. The Ni alloy refers to an alloy having the highest Ni content among the alloy components.

Cr:19.5〜23.5%
Crは、金属の表面に保護性の高い酸化物皮膜を形成し、耐孔食性や耐粒界腐食性を向上させる元素である。また、Niとの複合添加によって、サワー環境中での耐応力腐食割れ感受性も改善するため、Niやその他の合金とのバランスも考え、Cr量は19.5〜23.5%の範囲とする。好ましくは21.5〜23.5%の範囲である。
Cr: 19.5 to 23.5%
Cr is an element that forms a highly protective oxide film on the surface of metal and improves pitting corrosion resistance and intergranular corrosion resistance. In addition, the combined addition with Ni improves the stress corrosion cracking susceptibility in sour environment, so considering the balance with Ni and other alloys, the Cr content is in the range of 19.5 to 23.5%. . Preferably it is 21.5 to 23.5% of range.

Mo:2.50〜3.50%
Moは、耐孔食性、耐隙間腐食性を向上させる。また、Niとの複合添加によって、サワー環境中での耐応力腐食割れ感受性も改善するため、Niやその他の合金とのバランスも考え、Mo量は2.50〜3.50%の範囲とする。好ましくは3.00〜3.50%の範囲である。
Mo: 2.50 to 3.50%
Mo improves pitting corrosion resistance and crevice corrosion resistance. In addition, the combined addition with Ni improves the stress corrosion cracking susceptibility in the sour environment. Therefore, considering the balance with Ni and other alloys, the Mo amount is in the range of 2.50 to 3.50%. . Preferably it is 3.00 to 3.50% of range.

Cu:1.50〜3.00%
Cuは耐全面腐食性に有効な元素であり、1.50%以上含有することで、効果が発現する。しかし、3.00%を超えて含有してもその効果が飽和するため、Cu量は1.50〜3.00%の範囲とした。好ましくは1.80〜3.00%の範囲である。
Cu: 1.50 to 3.00%
Cu is an element effective for general corrosion resistance, and the effect is manifested when contained in an amount of 1.50% or more. However, since the effect is saturated even if it contains exceeding 3.00%, Cu amount was made into the range of 1.50 to 3.00%. Preferably it is 1.80 to 3.00% of range.

Al:0.01〜0.20%
Alは有効な脱酸元素であり、0.01%以上から効果が発現する。しかしながら、0.20%を超えて含有すると耐応力腐食割れ性が劣化するため、Al量は0.01〜0.20%の範囲とする。好ましくは0.10〜0.15%の範囲である。
Al: 0.01-0.20%
Al is an effective deoxidizing element, and the effect is manifested from 0.01% or more. However, if the content exceeds 0.20%, the stress corrosion cracking resistance deteriorates, so the Al content is in the range of 0.01 to 0.20%. Preferably it is 0.10 to 0.15% of range.

Ti:0.60〜1.20%以下
TiはCの固定化元素として有効であり、耐食性を劣化させるCr炭化物の析出を抑制することが可能となる。そのためには、0.60%以上の含有が必要であるが、多量に含有すると、クラッド鋼板の接合界面で金属間化合物として析出し、接合性を阻害するため、Ti量は1.20%以下とする。好ましくは0.70〜1.20%の範囲である。
Ti: 0.60 to 1.20% or less Ti is effective as a C-fixing element, and can suppress the precipitation of Cr carbides that deteriorate the corrosion resistance. For that purpose, the content of 0.60% or more is necessary. However, if it is contained in a large amount, it precipitates as an intermetallic compound at the joining interface of the clad steel sheet and inhibits the bonding property, so the Ti content is 1.20% or less. And Preferably it is 0.70 to 1.20% of range.

上記した合せ材の残部はFe及び不可避的不純物である。Feは高温強度の確保のために必要である。含有量は、22.0%以上あれば、高温強度上は問題ない。   The balance of the laminated material is Fe and inevitable impurities. Fe is necessary for securing high-temperature strength. If the content is 22.0% or more, there is no problem in high temperature strength.

3.製造方法について
本発明のNi合金クラッド鋼板の製造方法について以下に述べる。
3. About a manufacturing method The manufacturing method of the Ni alloy clad steel plate of this invention is described below.

加熱温度:1050℃以上、1150℃以下
加熱時に合せ材を十分溶体化するために1050℃以上に加熱する。クラッド鋼の接合性の観点からは、加熱温度は高温である方が好ましいが、1150℃を超えて加熱すると、母材の結晶粒粗大化によって靭性劣化を招く。よって、耐食性、低温靭性、接合性の観点から、加熱温度は1050℃以上、1150℃以下の範囲とする。
Heating temperature: 1050 ° C. or higher, 1150 ° C. or lower Heated to 1050 ° C. or higher in order to sufficiently melt the laminated material during heating. From the viewpoint of the weldability of the clad steel, it is preferable that the heating temperature is high. However, if the heating temperature exceeds 1150 ° C., the toughness deteriorates due to the coarsening of crystal grains of the base material. Therefore, from the viewpoint of corrosion resistance, low temperature toughness, and bondability, the heating temperature is set to a range of 1050 ° C. or higher and 1150 ° C. or lower.

950℃以上での圧下比:1.5以上
クラッド鋼は高温域での圧延によって、接合性が確保される。高温域での圧延が重要な理由としては、合せ材であるNi合金と母材である低合金鋼の変形抵抗差が小さくなるため、圧延で理想的な接合界面となる点と、高温域では合せ材と母材との境界で元素相互拡散が進行しやすいためである。よって、クラッド圧延用組立スラブを作製する段階で、組立スラブ内の真空度が10−4torr以上の高真空を確保できれば、合せ材/母材界面で十分な金属接合を得るためには、950℃以上での圧下比(=(圧延前の板厚)÷(圧延後の板厚))が1.5以上であれば良い。接合性の確保のためには、好ましくは、温度範囲は1000℃以上であり、圧下比は2.0以上である。なお、ここで、クラッド鋼板の素材とは合せ材と母材とを組み合わせたクラッド圧延用組立スラブのことをいう。
Rolling ratio at 950 ° C. or higher: 1.5 or higher Clad steel is secured by rolling in a high temperature region. The reason why rolling in the high temperature range is important is that the difference in deformation resistance between the Ni alloy, which is the laminated material, and the low alloy steel, which is the base material, is small. This is because element interdiffusion easily proceeds at the boundary between the laminated material and the base material. Therefore, if a high vacuum with a degree of vacuum of 10 −4 torr or more can be secured at the stage of manufacturing the clad rolling assembly slab, 950 is sufficient to obtain a sufficient metal joint at the laminated material / base metal interface. It is sufficient that the rolling ratio (= (plate thickness before rolling) ÷ (plate thickness after rolling)) at 1.5 ° C. or more is 1.5 or more. In order to ensure the bondability, the temperature range is preferably 1000 ° C. or higher and the rolling ratio is 2.0 or higher. Here, the material of the clad steel plate refers to an assembly slab for clad rolling in which a laminated material and a base material are combined.

母材の強度、低温靭性、特に脆性破壊の伝播停止特性を改善するには、オーステナイト低温域での高圧下と圧延直後の水冷が有効であることが明らかとなった。そこで制御圧延と圧延後の冷却条件について以下に述べる。なお、圧延、冷却過程における温度は鋼板表面温度を意味するものとする。   In order to improve the strength and low temperature toughness of the base metal, especially the propagation stopping characteristics of brittle fracture, it has become clear that water cooling under high pressure in the low temperature range of austenite and immediately after rolling is effective. Therefore, control rolling and cooling conditions after rolling will be described below. In addition, the temperature in a rolling and cooling process shall mean the steel plate surface temperature.

制御圧延:900℃以下において累積圧下率50%以上、圧延終了温度:750℃以上
母材のオーステナイト未再結晶温度域にて累積圧下率が50%以上の圧延を行うことにより、オーステナイト粒が伸展し、その後の加速冷却で変態生成するベイナイトが微細化し靭性が向上する。圧延終了温度が750℃未満まで低下しすぎると、元素拡散の進行が生じにくく接合性の劣化に繋がり、また、合せ材中の炭化物の析出が促進し、耐食性が劣化する。よって、制御圧延は、母材の強度、低温靭性と合せ材の耐食性、クラッド鋼の接合性を全て確保するために、制御圧延開始温度は900℃以下、累積圧下率は50%以上とし、750℃以上の温度で仕上げ圧延を終了することとした。
Controlled rolling: Cumulative rolling reduction of 50% or more at 900 ° C. or lower, Rolling end temperature: 750 ° C. or higher Rolling with a cumulative rolling reduction of 50% or more in the austenite non-recrystallization temperature range of the base metal causes austenite grains to expand. Then, the bainite transformed by the subsequent accelerated cooling is refined and the toughness is improved. If the rolling end temperature is too low to be less than 750 ° C., the progress of element diffusion hardly occurs, leading to deterioration of the bondability, and the precipitation of carbides in the laminated material is promoted to deteriorate the corrosion resistance. Therefore, in the controlled rolling, in order to ensure all of the strength of the base metal, the low temperature toughness, the corrosion resistance of the laminated material, and the weldability of the clad steel, the controlled rolling start temperature is 900 ° C. or less, the cumulative rolling reduction is 50% or more, 750 Finish rolling was finished at a temperature of ℃ or higher.

冷却速度:3℃/s以上、冷却停止温度:600℃以下
圧延終了後に600℃以下まで加速冷却するのは、母材の強度、低温靭性を担保するためである。冷却速度は、耐食性に大きく影響し、冷却速度は3℃/s未満では、圧延直後からの冷却過程において、合せ材中に炭化物が析出し、耐食性が劣化する。よって、冷却停止温度は600℃以下とし、冷却速度は3℃/s以上とする。冷却速度は、好ましくは、5℃/s以上である。
Cooling rate: 3 ° C./s or more, cooling stop temperature: 600 ° C. or less The reason for accelerated cooling to 600 ° C. or less after the end of rolling is to ensure the strength and low temperature toughness of the base material. The cooling rate greatly affects the corrosion resistance. If the cooling rate is less than 3 ° C./s, carbide precipitates in the laminated material in the cooling process immediately after rolling, and the corrosion resistance deteriorates. Therefore, the cooling stop temperature is 600 ° C. or lower, and the cooling rate is 3 ° C./s or higher. The cooling rate is preferably 5 ° C./s or more.

本発明のクラッド鋼の母材素材ならびに合せ材素材は、前記した成分範囲に調整され、常法等により溶製することができる。クラッド圧延用組立スラブは、母材/合せ材/合せ材/母材というように重ね合わせた形式が製造上効率的であり、また冷却時の反りを考慮すると、母材同士、合せ材同士は等厚であることが望ましい。もちろん、上記で記述した組立方式に限定する必要が無いことは言うまでも無い。   The base material and the laminated material of the clad steel of the present invention are adjusted to the above-described component ranges and can be melted by a conventional method or the like. For the clad rolling assembly slab, the superposition type of base material / lamination material / lamination material / matrix is efficient in manufacturing, and considering the warping during cooling, the base materials and the laminating materials are It is desirable that the thickness is equal. Of course, it goes without saying that it is not necessary to limit to the assembly method described above.

以下に本発明の実施例を比較例と対比しつつ説明する。ここで、溶接部靭性の評価は、シャルピー試験により行った。シャルピー試験片のノッチ位置は、溶接金属と母材の境界であるボンド部から、母材側へ3mm(HAZ3mm)の位置とした。試験温度は、−20℃で実施した。本発明では−20℃の吸収エネルギー(vE−20℃)が100J以上を靭性に優れているものとした。   Examples of the present invention will be described below in comparison with comparative examples. Here, the toughness of the welded portion was evaluated by a Charpy test. The notch position of the Charpy test piece was set to a position of 3 mm (HAZ 3 mm) from the bond part, which is the boundary between the weld metal and the base material, to the base material side. The test temperature was -20 ° C. In the present invention, the absorbed energy (vE-20 ° C.) at −20 ° C. is 100 J or more, and the toughness is excellent.

また、母材の機械的特性は、API−5Lに準拠した引張試験片とDWTT試験片を採取し、引張試験とDWTT試験をおこなった。引張試験は、YSが450MPa以上、TSが535MPa以上を母材強度に優れているものとし、DWTT試験は、−20℃を試験温度とし、延性破面率85%以上を母材の低温靭性に優れているものとした。   As for the mechanical properties of the base material, tensile test pieces and DWTT test pieces based on API-5L were collected and subjected to tensile tests and DWTT tests. In the tensile test, YS is 450 MPa or more and TS is 535 MPa or more, and the base material strength is excellent. In the DWTT test, the test temperature is −20 ° C., and the ductile fracture surface ratio is 85% or more for the low temperature toughness of the base material. It was supposed to be excellent.

また、合せ材の耐食性試験は、JIS G0573 ステンレス鋼の65体積%硝酸腐食試験(ヒューイ試験)方法に準拠した。試験方法は、沸騰させた65体積%硝酸溶液中に試験片を48時間浸漬させ、試験前後の重量変化から腐食速度(g/m・h)を算出し、新たな沸騰65体積%硝酸溶液中に同一試験片を再び浸漬させる。この48時間浸漬試験を5回繰り返し、5回の腐食速度の平均値から耐食性能を評価した。評価基準は、0.50g/m・h以下のものを耐食性能が良好であると判断した。 Moreover, the corrosion resistance test of the laminated material was based on the 65 volume% nitric acid corrosion test (Huey test) method of JIS G0573 stainless steel. In the test method, a test piece was immersed in a boiled 65% by volume nitric acid solution for 48 hours, the corrosion rate (g / m 2 · h) was calculated from the weight change before and after the test, and a new boiled 65% by volume nitric acid solution was obtained. Immerse the same specimen in again. This 48-hour immersion test was repeated 5 times, and the corrosion resistance was evaluated from the average value of the 5 corrosion rates. Evaluation criteria judged that the thing of 0.50 g / m < 2 > h or less has favorable corrosion resistance.

また、クラッド鋼としての接合性は、JIS G0601:2012のクラッド鋼の試験方法に記載のせん断強さ試験に準拠して行った。評価基準はせん断強さが300MPa以上のものを接合性が良好であると判断した。   Moreover, the joining property as clad steel was performed based on the shear strength test described in the test method of clad steel of JIS G0601: 2012. The evaluation criteria were determined to be good bondability when the shear strength was 300 MPa or more.

表1に化学成分を示す母材と表2に化学成分を示す合せ材を用いて、クラッド鋼を製造した。製造条件は、母材/合せ材/合せ材/母材を重ねて一組とし、表3に示す条件で熱間圧延を行い、クラッド鋼板から引張試験、DWTT試験、塩化第二鉄腐食試験の試験片を採取し、各試験に供した。一連のクラッド鋼板を冷間で成型してクラッド鋼管を製造し、母材部と母材の溶接熱影響部について諸特性を調べた。結果を表4に示す。母材の化学成分と合せ材の化学成分と製造条件が本発明の請求項を満足する鋼は、母材部のDWTT特性(低温靭性)とHAZ靭性(溶接熱影響部靭性)と合せ材の耐食性とクラッド鋼としての接合性を満足する。   Clad steel was manufactured using the base material which shows a chemical component in Table 1, and the laminated material which shows a chemical component in Table 2. The manufacturing conditions are a set of base material / lamination material / lamination material / base material, and hot rolling is performed under the conditions shown in Table 3, and the tensile test, DWTT test, and ferric chloride corrosion test are performed from the clad steel plate. Test specimens were collected and used for each test. A series of clad steel sheets were cold-formed to produce clad steel pipes, and various characteristics were investigated for the base metal part and the weld heat affected zone of the base metal. The results are shown in Table 4. Steels whose base material chemical composition and laminated material chemical composition and manufacturing conditions satisfy the claims of the present invention are based on the DWTT characteristics (low temperature toughness) of the base metal part and the HAZ toughness (welding heat affected zone toughness). Satisfies corrosion resistance and bondability as clad steel.

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表1には、母材の化学成分実績を示す。鋼No.A1〜A9は本発明の範囲に属する発明例である。一方、鋼No.B1〜B4は何れかの成分が発明の範囲外となっている比較例である。表2には、合せ材の化学成分実績を示す。鋼No.C1〜C3は本発明の範囲に属する発明例である。一方、No.D1はCが上限を外れた比較例である。表3には、表1に示す化学成分の母材と、表2に示す化学成分の合せ材を使ってクラッド鋼板を製造した製造実績を示す。製造方法No.E1〜E10は、加熱、圧延、冷却のいずれの製造条件とも発明の範囲に属する発明例である。一方、製造方法No.F1〜F5は加熱、圧延、冷却のいずれかの製造条件が発明の範囲外である比較例である。   Table 1 shows the chemical component results of the base material. Steel No. A1 to A9 are invention examples belonging to the scope of the present invention. On the other hand, Steel No. B1 to B4 are comparative examples in which any component is outside the scope of the invention. Table 2 shows the results of chemical components of the laminated material. Steel No. C1 to C3 are invention examples belonging to the scope of the present invention. On the other hand, no. D1 is a comparative example in which C deviates from the upper limit. Table 3 shows the manufacturing results of manufacturing clad steel plates using the base materials of the chemical components shown in Table 1 and the combined materials of the chemical components shown in Table 2. Production Method No. E1 to E10 are invention examples belonging to the scope of the invention under any manufacturing conditions of heating, rolling and cooling. On the other hand, the production method No. F1 to F5 are comparative examples in which any of the production conditions of heating, rolling, and cooling is outside the scope of the invention.

表4には、製造した各種クラッド鋼の試験結果を示す。表には、母材の引張試験、落重試験の結果、溶接試験結果(HAZ3mmでのシャルピー試験)、せん断試験結果および合せ材の腐食試験結果を示す。実施例No.1〜16はいずれの試験も目標値をクリアした発明例である。実施例No.17、18は母材の化学成分が発明の範囲外であり、No.19、20は母材と合せ材の化学成分が発明の範囲外であり、No.21〜25は何れかの製造条件が発明の範囲外であるため各種試験結果が目標値に達しなかった。   Table 4 shows the test results of the various clad steels produced. The table shows the results of the tensile test of the base material, the drop weight test, the welding test result (Charpy test at HAZ 3 mm), the shear test result, and the corrosion test result of the laminated material. Example No. 1-16 are invention examples which cleared the target value in any test. Example No. In Nos. 17 and 18, the chemical composition of the base material is outside the scope of the invention. In Nos. 19 and 20, the chemical components of the base material and the laminated material are out of the scope of the invention. As for any of 21-25, since any manufacturing conditions were outside the scope of the invention, various test results did not reach the target values.

Claims (1)

化学成分が質量%で、C:0.020%以下、Si:0.05〜0.50%、Mn:0.10〜1.00%、P:0.030%以下、S:0.0050%以下、Ni:38.0〜46.0%、Cr:19.5〜23.5%、Mo:2.50〜3.50%、Cu:1.50〜3.00%、Al:0.01〜0.20%、Ti:0.60〜1.20%を含有し、残部Fe及び不可避的不純物からなる合せ材と、化学成分が質量%で、C:0.020〜0.100%、Si:0.10〜0.50%、Mn:0.75〜1.80%、P:0.015%以下、S:0.0030%以下、Cu:0.01〜0.50%、Ni:0.01〜0.45%、Cr:0.01〜0.50%、Mo:0.01〜0.50%、Nb:0.005〜0.080%、Ti:0.005〜0.030%、N:0.0010〜0.0060%、Al:0.070%以下、Ca:0.0010〜0.0040%を含有し、残部Fe及び不可避的不純物からなり、前記Tiと前記Nとの質量%比であるTi/Nが2.00〜4.00の範囲にある母材とを組み合わせたクラッド鋼板の素材を用いて、1050℃〜1150℃に加熱後、鋼板表面温度が950℃以上での圧下比を1.5以上とし、900℃以下の温度域における累積圧下率を50%以上、圧延終了温度を750℃以上とする熱間圧延を行った後に、冷却速度3℃/s以上、冷却停止温度600℃以下とする加速冷却を行った後に放冷することを特徴とする、−20℃DWTT試験で延性破面率85%以上の母材の低温靭性とHAZ3mm位置でのvE−20℃が100J以上のHAZ靭性及びJIS G0573 ステンレス鋼の65体積%硝酸腐食試験(ヒューイ試験)方法に準拠した耐食性試験での5回の腐食速度の平均値が0.50g/m ・h以下の合せ材の耐食性を有する、母材の低温靭性とHAZ靭性及び合せ材の耐食性に優れたNi合金クラッド鋼板の製造方法。 Chemical component is mass%, C: 0.020% or less, Si: 0.05 to 0.50%, Mn: 0.10 to 1.00%, P: 0.030% or less, S: 0.0050 %: Ni: 38.0 to 46.0%, Cr: 19.5 to 23.5%, Mo: 2.50 to 3.50%, Cu: 1.50 to 3.00%, Al: 0 0.01% to 0.20%, Ti: 0.60 to 1.20%, a balance material composed of the balance Fe and inevitable impurities, and a chemical component in mass%, C: 0.020 to 0.100 %, Si: 0.10 to 0.50%, Mn: 0.75 to 1.80%, P: 0.015% or less, S: 0.0030% or less, Cu: 0.01 to 0.50% , Ni: 0.01 to 0.45%, Cr: 0.01 to 0.50%, Mo: 0.01 to 0.50%, Nb: 0.005 to 0.080%, Ti: 0.005 to 0.030%, N: 0.0010 to 0.0060%, Al: 0.070% or less, Ca: 0.0010 to 0.0040%, the balance being Fe and inevitable impurities, After heating to 1050 ° C. to 1150 ° C. using a clad steel plate material combined with a base material in which Ti / N, which is a mass% ratio of Ti and N, is in the range of 2.00 to 4.00, The steel sheet surface temperature is 950 ° C. or higher, the rolling ratio is 1.5 or higher, the hot rolling in the temperature range of 900 ° C. or lower is 50% or higher, and the rolling end temperature is 750 ° C. or higher. Low temperature toughness of a base material having a ductile fracture surface ratio of 85% or more in a -20 ° C DWTT test, characterized by cooling after cooling at a cooling rate of 3 ° C / s or more and a cooling stop temperature of 600 ° C or less . And vE-20 at HAZ 3mm position 5 times of the average value of corrosion rate 0.50g / m 2 · h or less in combined with corrosion resistance test but conforming to 65 vol% nitric acid corrosion test (Huey Test) The method of HAZ toughness and JIS G0573 stainless steel or 100J The manufacturing method of the Ni alloy clad steel plate which has the corrosion resistance of a base material, and was excellent in the low temperature toughness and HAZ toughness of a base material, and the corrosion resistance of a laminated material.
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