JPH0814014B2 - Welded steel pipe - Google Patents
Welded steel pipeInfo
- Publication number
- JPH0814014B2 JPH0814014B2 JP26027189A JP26027189A JPH0814014B2 JP H0814014 B2 JPH0814014 B2 JP H0814014B2 JP 26027189 A JP26027189 A JP 26027189A JP 26027189 A JP26027189 A JP 26027189A JP H0814014 B2 JPH0814014 B2 JP H0814014B2
- Authority
- JP
- Japan
- Prior art keywords
- weld metal
- steel pipe
- toughness
- δni
- metal
- 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 - Fee Related
Links
- 229910000831 Steel Inorganic materials 0.000 title claims description 37
- 239000010959 steel Substances 0.000 title claims description 37
- 239000002184 metal Substances 0.000 claims description 52
- 229910052751 metal Inorganic materials 0.000 claims description 52
- 239000010953 base metal Substances 0.000 claims description 25
- 239000000203 mixture Substances 0.000 claims description 23
- 239000000126 substance Substances 0.000 claims description 20
- 229910052759 nickel Inorganic materials 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 10
- 229910052750 molybdenum Inorganic materials 0.000 claims description 10
- 229910052748 manganese Inorganic materials 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 6
- 229910052758 niobium Inorganic materials 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 229910052720 vanadium Inorganic materials 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 230000007797 corrosion Effects 0.000 description 31
- 238000005260 corrosion Methods 0.000 description 31
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 239000013535 sea water Substances 0.000 description 8
- 229910052802 copper Inorganic materials 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000003466 welding Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 229910000851 Alloy steel Inorganic materials 0.000 description 2
- 230000005587 bubbling Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000008235 industrial water Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Landscapes
- Rigid Pipes And Flexible Pipes (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は、パイプラインにおいて使用される溶接鋼管
特に溶接金属の耐選択腐食性に優れた高強度及び高靱性
の溶接鋼管に関するものである。Description: TECHNICAL FIELD The present invention relates to a welded steel pipe used in a pipeline, particularly to a welded steel pipe having high strength and high toughness which is excellent in selective corrosion resistance of weld metal.
［従来の技術］ 従来、低合金鋼溶接部の選択腐食を防止することを目
的とした溶接鋼管に関する特許は数多く出願されてお
り、例えば特開昭52−113318号公報（登録No.1263605）
のAl、Ｓの低減とTi、Zr、Ｙの１成分以上を添加するも
のや、これにCuを0.2〜0.6％添加し、必要に応じて850
〜950℃で30分以下、局部熱処理を施すもの（特開昭52
−113319号公報）、あるいは0.005〜0.06％Tiを含有す
る鋼を溶接部のみ900〜1050℃で１秒〜５分間、局部加
熱を程すもの（特開昭62−202049号公報）などがある。[Prior Art] A number of patents relating to welded steel pipes for the purpose of preventing selective corrosion of low-alloy steel welds have been filed, for example, JP-A-52-113318 (Registration No.1263605).
Of Al and S and addition of one or more components of Ti, Zr and Y, or Cu of 0.2 to 0.6%, and if necessary 850
Local heat treatment at ~ 950 ° C for 30 minutes or less (JP-A-52)
No. 113319), or a steel containing 0.005 to 0.06% Ti is locally heated at 900 to 1050 ° C. for 1 second to 5 minutes only in the welded portion (JP-A-62-202049). .
しかしながら、これらは、いずれも電気抵抗溶接を用
いた電縫鋼管に関するものであり、選択的に腐食する溶
接部は母材と同じ組成を有している。However, these are all related to the electric resistance welded steel pipe using electric resistance welding, and the selectively corroded weld has the same composition as the base metal.
一方、低合金鋼の選択腐食に関する公表文献中には、
電縫管のほかに、母材と異なる化学組成を持つ溶接金属
の選択腐食防止方法も数多く報告されており、例えば次
のようなものがある。On the other hand, in the published literature on selective corrosion of low alloy steels,
In addition to ERW pipes, many methods for selective corrosion prevention of weld metal having a chemical composition different from that of the base metal have been reported, and examples include the following.
氷海での溶接継手部局部腐食に対して、母材と溶接
金属のNi添加量の差が影響を及ぼすとするもの（安部隆
ほか：鉄と鋼Vol.72,s1266 1988）同じく氷海域鋼の
溶接部局部腐食で、Niと Cuが影響を及ぼし、 3.8ΔCu＋1.1ΔNi＋0.3 （ΔCu,ΔNiは共に母材と溶接金属との差）が選択腐食
性を左右する。It is said that the difference in the amount of Ni added between the base metal and the weld metal has an effect on the local corrosion of welded joints in the ice sea (Takashi Abe et al .: Iron and Steel Vol.72, s1266 1988). Ni and Cu affect the local corrosion of the welded part, and 3.8ΔCu + 1.1ΔNi + 0.3 (ΔCu and ΔNi are the differences between the base metal and the weld metal) influence the selective corrosion.
（伊藤亀太郎ほか：鉄と鋼Vol.72,s1265 1989）炭素
鋼配管円周溶接部の選択腐食防止に、Cu及びNiを含む低
合金鋼溶接棒の使用が有効であるとするもの（幸英昭：
材料Vol.38,No.424 p62〜p.68 1989） 以上のように、溶接金属の選択腐食を改善する方法と
して、Ni及びCuを添加する方法が見出だされていたが、
Moの添加が有効であるとの知見は未だ得られていなかっ
た。(Kametaro Ito et al. Iron and Steel Vol.72, s1265 1989) Use of low alloy steel welding rods containing Cu and Ni is effective for preventing selective corrosion of carbon steel pipe circumferential welds (Hideaki Koyuki) :
Materials Vol.38, No.424 p62 to p.68 1989) As described above, a method of adding Ni and Cu has been found as a method of improving selective corrosion of weld metal,
The knowledge that the addition of Mo is effective has not been obtained yet.
［発明が解決しようとする課題］ 溶接鋼管を海水や工業用水に使用すると、溶接金属が
選択的に腐食する、いわゆる溶接部選択腐食を起す場合
がある。これは、溶接鋼管のように母材と溶接金属との
化学成分が異なることや、電縫管のように溶接熱履歴に
より、金属組織上の差が生ずることにより、この差に依
存して溶接金属部が電気化学的に卑になり、溶接金属部
が選択的に腐食するものである。[Problems to be Solved by the Invention] When a welded steel pipe is used in seawater or industrial water, the weld metal may be selectively corroded, that is, so-called weld portion selective corrosion may occur. This is because the difference in the chemical composition between the base metal and the weld metal, such as in welded steel pipe, and the difference in the metal structure caused by the heat history of welding, such as in electric resistance welded pipes, lead to welding depending on this difference. The metal part becomes electrochemically base, and the weld metal part is selectively corroded.
従来の溶接鋼管では、この選択腐食を考慮した製造法
は検討されていなかった。For conventional welded steel pipes, no manufacturing method considering this selective corrosion has been studied.
しかしながら、実環境では、この種の選択腐食が問題
となることがしばしばあり、この検討が待たれている。However, in a real environment, this type of selective corrosion often poses a problem, and this examination is awaited.
本願発明は、溶接金属部の化学成分を調整することに
より、溶接金属部の選択腐食を防止する為になされたも
のであり、溶接金属部の選択腐食の防止とともに、十分
な強度と靱性を備えた溶接鋼管を提供することを目的と
するものである。The present invention is made to prevent the selective corrosion of the weld metal portion by adjusting the chemical composition of the weld metal portion, and has sufficient strength and toughness as well as preventing the selective corrosion of the weld metal portion. It is intended to provide a welded steel pipe.
［課題を解決するための手段］ 本願発明は、本願発明者等が溶接金属の化学成分及び
その成分値を各種に変化させて、海水を含む腐食環境の
中での溶接部の選択腐食について、綿密な調査を重ねた
結果得られた知見に基づくものである。[Means for Solving the Problems] The present invention relates to selective corrosion of a welded portion in a corrosive environment including seawater by the inventors of the present invention by variously changing the chemical composition of the weld metal and its component value. It is based on the knowledge obtained as a result of careful investigation.
即ち、本発明の第１は、 母材の化学成分組成（重量％）が C;0.03〜0.15％ Si0.05〜0.50％ Mn;0.50〜2.00％ Al;0.005〜0.10％ を含有し、残部がFe及び不可避不純物を含み、且つ溶接
金属の化学成分組成が、下記の式を満足することを特徴
とする溶接鋼管である。That is, the first aspect of the present invention is that the chemical composition (% by weight) of the base material is C; 0.03 to 0.15% Si0.05 to 0.50% Mn; 0.50 to 2.00% Al; 0.005 to 0.10% and the balance is A welded steel pipe containing Fe and inevitable impurities, and having a chemical composition of the weld metal satisfying the following formula.
ΔNi＋7.5ΔMo≧0.1 但し ΔNi＝溶接金属部重量％ ΔMo＝溶接金属部重量％ 又、本発明の第２は、 母材の化学成分組成（重量％）が C;0.03〜0.15％ Si;0.05〜0.50％ Mn;0.50〜2.00％ Al;0.005〜0.10％ を含有し、下記成分の中から１種または２種以上 Cu;0.05〜2.0％ Ni;0.05〜2.0％ Cr;0.05〜2.0％ Mo;0.05〜2.0％ Nb;0.05〜0.20％ V;0.005〜0.20％ Ti;0.005〜0.20％ B;0.0005〜0.0020％ Ca;0.0005〜0.0050％ を含有し、残部がFe及び不可避不純物を含み、且つ溶接
金属の化学成分組成が、下記の式を満足することを特徴
とする溶接鋼管である。ΔNi + 7.5 ΔMo ≧ 0.1 where ΔNi = weight% of weld metal part ΔMo = weight% of weld metal part The second aspect of the present invention is that the chemical composition (% by weight) of the base metal is C: 0.03 to 0.15% Si; 0.05 to 0.50% Mn; 0.50 to 2.00% Al; 0.005 to 0.10%, 1 or 2 or more of the following components Cu; 0.05 to 2.0% Ni; 0.05 to 2.0% Cr; 0.05 to 2.0% Mo; 0.05 ~ 2.0% Nb; 0.05 ~ 0.20% V; 0.005 ~ 0.20% Ti; 0.005 ~ 0.20% B; 0.0005 ~ 0.0020% Ca; 0.0005 ~ 0.0050% with the balance containing Fe and unavoidable impurities A welded steel pipe having a chemical composition satisfying the following formula.
ΔNi＋7.5ΔMo≧0.1 但し ΔNi＝Ni（溶接金属部重量％）−Ni（母材重量％） ΔMo＝Mo（溶接金属部重量％）−Mo（母材重量％） ［作用］ 本発明は、以上の如く、母材の化学成分及びその組成
を限定し、さらに前述の如き式を満足する溶接金属の耐
選択腐食性に富む高強度及び高靱性の溶接鋼管である。ΔNi + 7.5 ΔMo ≧ 0.1 where ΔNi = Ni (wt% of weld metal) -Ni (wt% of base metal) ΔMo = Mo (wt% of weld metal) -Mo (wt% of base metal) [Operation] As described above, it is a high-strength and high-toughness welded steel pipe which has a limited chemical composition of the base metal and its composition, and which further satisfies the above-mentioned formula and is rich in selective corrosion resistance of the weld metal.
次に、鋼中の夫々の化学成分の限定理由について述べ
る。Next, the reasons for limiting the chemical components in steel will be described.
C:鋼中の炭素は、鋼の強度を上昇させる上で有効な元
素であるが、過度の添加は靱性の劣化を招くので好まし
くない。従って、強度並びに靱生とも良好な鋼管を得る
ためには、炭素量の上限は0.15％とする。炭素量の低減
は靱性を向上させるが、0.03％以下になると靱性は劣化
する。また、安定したNb,V,Tiなどの析出硬化を有効に
利用するためにも0.03％以上の炭素は必要となるので、
これ等を考慮して炭素量の下限を0.03％と定めた。C: Carbon in the steel is an element effective in increasing the strength of the steel, but excessive addition thereof is not preferable because it causes deterioration of toughness. Therefore, in order to obtain a steel pipe having excellent strength and toughness, the upper limit of the carbon content is 0.15%. A reduction in carbon content improves toughness, but if it is 0.03% or less, toughness deteriorates. In addition, 0.03% or more of carbon is necessary to effectively utilize stable precipitation hardening of Nb, V, Ti, etc.
Taking these factors into consideration, the lower limit of carbon content was set at 0.03%.
Si:鋼中のSiは、脱酸のため必要であるが過多に添加す
ると靱性は劣化させるので、下限を0.05％、上限を0.5
％とした。Si: Si in steel is necessary for deoxidation, but if added in excess, the toughness deteriorates, so the lower limit is 0.05% and the upper limit is 0.5.
%.
Mn:鋼中のMnは、Siと同様に脱酸のため0.5％以上必要で
あるが、2.0％を越えると溶接性を劣化させるので上限
を2.0％とした。Mn: Mn in steel is required to be 0.5% or more for deoxidation like Si, but if it exceeds 2.0%, the weldability deteriorates, so the upper limit was made 2.0%.
Al:鋼中のAlは、Si及びMnと同様に脱酸のため必要であ
るが、0.005％未満では脱酸が不十分となるので下限を
0.005％とした。一方、0.1％を越えると鋼の清浄並びに
熱影響部（HAZ;Heat Affected Zone）靱性を劣化させる
ので、上限を0.1％とした。Al: Al in steel is necessary for deoxidation like Si and Mn, but if less than 0.005%, deoxidation will be insufficient, so the lower limit is set.
It was set to 0.005%. On the other hand, if it exceeds 0.1%, the cleanliness of the steel and the heat affected zone (HAZ) toughness deteriorate, so the upper limit was made 0.1%.
次に、第２発明においては、上記成分の他、さらに前
述のような選択成分及びその組成を限定する。そして第
３発明においては、上記成分の他NiおよびMo、さらに前
述のような選択成分及びその組成を限定する。Next, in the second invention, in addition to the above-mentioned components, the above-mentioned selective components and their compositions are further limited. In addition, in the third invention, in addition to the above-mentioned components, Ni and Mo, and the above-mentioned selective components and their compositions are limited.
Cu,Ni:Cu並びにNiは、HAZ靱性に悪影響を及ぼすことな
く母材の強度靱性を改善させるが、2.0％を超えるとHAZ
の硬化性並びに靱性に影響を及ぼすので、上限を2.0％
とする。Cu, Ni: Cu and Ni improve the strength and toughness of the base metal without adversely affecting the HAZ toughness, but when it exceeds 2.0%, HAZ
The upper limit is 2.0% because it affects the hardenability and toughness of
And
Ci:Crは、母材及び溶接部の強度を高めるが、2.0％を超
えるとHAZの硬化性並びに靱性を劣化させるので、上限
を2.0％とする。Ci: Cr enhances the strength of the base material and the welded portion, but if it exceeds 2.0%, it deteriorates the hardenability and toughness of the HAZ, so the upper limit is made 2.0%.
Mo:Moは、母材の強度並びに靱性を向上させるが、2.0％
を超えるとHAZの焼入れを増して溶接性を劣化させるの
で、上限を2.0％とする。Mo: Mo improves the strength and toughness of the base metal, but 2.0%
If it exceeds, the quenching of HAZ will increase and the weldability will deteriorate, so the upper limit is made 2.0%.
以上のCu,Ni,Cr及びMoの元素添加量の下限は、材質上
の効果が得られる最小必要量とし、0.05％とする。The lower limit of the above element addition amounts of Cu, Ni, Cr and Mo is set to 0.05%, which is the minimum necessary amount for obtaining the effect on the material.
Ti:Tiは、0.005％以上の添加により、スラブ加熱時のオ
ーステナイトの粗大化を防止する効果を有するので、下
限を0.005％とし、過度に添加すると溶接部の靱性を劣
化させるので、上限を0.20％とした。Ti: Ti has an effect of preventing coarsening of austenite during slab heating by addition of 0.005% or more, so the lower limit is 0.005%, and if added excessively, the toughness of the welded portion is deteriorated, so the upper limit is 0.20. %.
Nb,V:Nb並びにＶは、強度及び靱性に効果が認められる
が、0.20％を超えると、母材及び溶接部の靱性を劣化さ
せるので、上限を0.20％とした。下限は材質上の向上の
認められる0.005％以上とした。Nb, V: Nb and V are effective in strength and toughness, but if they exceed 0.20%, the toughness of the base material and the welded portion deteriorates, so the upper limit was made 0.20%. The lower limit was made 0.005% or more, which is an improvement in material quality.
B:Bは、母材の強度上昇に有効であるが、過度の添加
は、溶接性並びにHAZの靱性の劣化を招くので、上限は
0.0020％とし、下限は強度の上昇に効果が認められる0.
0005％とした。B: B is effective for increasing the strength of the base metal, but excessive addition causes deterioration of weldability and HAZ toughness, so the upper limit is
The lower limit is 0.0020%, and the lower limit is effective in increasing strength.
It was set to 0005%.
Ca:Caの添加は、耐水素誘起割れ性を改善し、下限は効
果の認められる0.0005％とする。過度の添加は酸化物を
形成して有害であるので、上限を0.0050％とする。The addition of Ca: Ca improves the hydrogen-induced cracking resistance, and the lower limit is made 0.0005% at which the effect is recognized. Excessive addition forms an oxide and is harmful, so the upper limit is made 0.0050%.
さらに、海水環境などの腐食環境にあって、溶接金属
部の選択腐食は、腐食環境にさらされた溶接金属部のNi
及びMo量（重量％）、または溶接金属部と母材の鋼のNi
及びMoの夫々の差、 ΔNi＝溶接金属部重量％、またはNi（溶接金属部重量
％）−Ni（母材重量％） ΔMo＝溶接金属部重量％、またはMo（溶接金属部重量
％）−Mo（母材重量％） に大きく影響され、第１図に示すように、溶接部の選択
腐食に及ぼすΔNiとΔMoの係数を検討した結果、溶接部
の選択腐食性と（ΔNi＋7.5ΔMo）との間に良い相関が
認められ、この値が0.1未満では溶接部が選択的に腐食
することを見知した。Furthermore, in a corrosive environment such as a seawater environment, the selective corrosion of the weld metal part is due to the Ni corrosion of the weld metal part exposed to the corrosive environment.
And Mo content (% by weight), or Ni of the weld metal and base steel
And Mo, ΔNi = wt% of weld metal, or Ni (wt% of weld metal) -Ni (wt% of base metal) ΔMo = wt% of weld metal, or Mo (wt% of weld metal) − As shown in Fig. 1, which was greatly affected by Mo (base metal weight%), the coefficients of ΔNi and ΔMo on the selective corrosion of the weld were examined. As a result, it was found that the selective corrosion of the weld and (ΔNi + 7.5ΔMo) There was a good correlation between the two values, and it was found that when this value was less than 0.1, the welds were selectively corroded.
従ってこの式の値を、溶接部の選択腐食性のパラメー
ターとしてPCW（preferential corrosion of welded）
値とし、本願発明の溶接金属は、このPCW値が下記条件
を満足することを要するものである。Therefore, PCW (preferential corrosion of welded) is used as a parameter of the selective corrosion of the welded part.
As a value, the weld metal of the present invention is required to have this PCW value satisfying the following conditions.
PCW＝ΔNi＋7.5ΔMo≧0.1 次に本発明の実施例について述べる。PCW = ΔNi + 7.5ΔMo ≧ 0.1 Next, examples of the present invention will be described.
［実施例］ 第１表に供試母材の化学成分値（重量％）を示す。[Examples] Table 1 shows chemical component values (% by weight) of the test base metal.
第１表に示すＡ〜Ｇ鋼（但しＧ鋼は比較鋼）を用い
て、降伏強さが35〜56kgf/cm2において、外径38インチ
×全長12mの各種の溶接鋼管を試作して、強度、靱性、
海水環境（CO2ガスバブリング）での選択腐食速度をそ
れぞれ測定した。Using the steels A to G shown in Table 1 (however, G steel is a comparative steel), various welded steel pipes having an outer diameter of 38 inches and a total length of 12 m were produced as trials at a yield strength of 35 to 56 kgf / cm 2 . Strength, toughness,
The selective corrosion rate in seawater environment (CO 2 gas bubbling) was measured.
第２表に、強度、靱性及び選択腐食速度の試験成績を
示す。Table 2 shows the test results of strength, toughness and selective corrosion rate.
強度YSはASTM全厚引張り試験法、靱性はJIS Z3128 4
号試験片、選択腐食の測定は、全長50cm鋼管の内部に、
人工海水を入れ、これにCO2ガスを吹き込んで、母材と
溶接金属部の板厚の減量の差を求めることにより、測定
した値である。Strength YS is ASTM full thickness tensile test method, toughness is JIS Z3128 4
No. test piece, selective corrosion is measured inside a 50 cm long steel pipe.
It is a value measured by adding artificial seawater, blowing CO 2 gas into the artificial seawater, and determining the difference in the reduction in plate thickness between the base metal and the weld metal.
第１図は前述の如く、CO2ガスをバブリングした人工
海水中において、 試料面積は、母材：溶接金属＝3.1とし、腐食環境に
さらされた溶接金属部のNi及びMo量（重量％）、または
溶接金属部と母材の鋼のNi及びMoの夫々の差、 ΔNi＝溶接金属部重量％、またはNi（溶接金属部重量
％）−Ni（母材重量％） ΔMo＝溶接金属部重量％、またはMo（溶接金属部重量
％）−Mo（母材重量％） とした場合の母材と溶接金属部の間に流れた選択腐食電
流（μA/cm2）とΔNi＋7.5ΔMo（PCW）との関係グラフ
である。As shown in Fig. 1, in artificial seawater with bubbling CO 2 gas, the sample area was base metal: weld metal = 3.1, and the amount of Ni and Mo in the weld metal exposed to the corrosive environment (% by weight). , Or the difference between Ni and Mo in the weld metal and the base steel, ΔNi = wt% weld metal, or Ni (wt% weld metal) -Ni (wt% base metal) ΔMo = weight weld metal % Or Mo (% by weight of weld metal) -Mo (% by weight of base metal), the selective corrosion current (μA / cm 2 ) flowing between the base metal and the weld metal and ΔNi + 7.5ΔMo (PCW) It is a relationship graph with.
図中、○印は溶接部；陰極（健全）、●印は溶接部；
陽極（選択腐食）を夫々示す。In the figure, ○ indicates welded area; cathode (sound), ● indicates welded area;
Anode (selective corrosion) is shown respectively.
第２表並びに第１図に示すように、母材の化学成分組
成（重量％）が、C;0.03〜0.15％,Si;0.05〜0.50％,Mn;
0.50〜2.00％,Al;0.005〜0.10％を含有し、残部がFe及
び不可避不純物を含み、且つ溶接金属の化学成分組成
が、下記条件を満足する溶接鋼管は、強度、靱性（5kg
f.m以上）、選択腐食速度（溶接部が選択的に腐食しな
い、表２中−符号の場合）に優れた溶接鋼管であること
が確認された。As shown in Table 2 and FIG. 1, the chemical composition of the base material (% by weight) is C: 0.03 to 0.15%, Si; 0.05 to 0.50%, Mn;
Welded steel pipe containing 0.50 to 2.00%, Al; 0.005 to 0.10%, the balance containing Fe and unavoidable impurities, and the chemical composition of the weld metal satisfying the following conditions, strength and toughness (5 kg
It was confirmed that the welded steel pipe was excellent in selective corrosion rate (weld part does not selectively corrode, in Table 2, -sign), and above.
PCW＝ΔNi＋7.5Mo≧0.1 また、母材の化学成分組成（重量％）が、C;0.03〜0.
15％,Si;0.05〜0.50％,Mn;0.50〜2.00％,Al;0.005〜0.1
0％を含有し、残部がFe及び不可避不純物を含み、さら
に、下記成分の中から、 Cu;0.05〜2.0％,Ni;0.05〜2.0％,Cr;0.05〜2.0％,Mo;
0.05〜2.0％,Nb;0.005〜0.20％,V;0.005〜0.20％,Ti;0.
005〜0.20％,B;0.0005〜0.0020％,Ca;0.0005〜0.0050％
の１種または２種以上を含有し、且つ溶接金属の化学成
分組成が、前記溶接金属部と母材とのNi及びMo量（量重
％）の差によって決められるPCW値が、下記条件を満足
する溶接鋼管は、強度、靱性（5kgf.m以上）、選択腐食
速度（溶接部が選択的に腐食しない、表２中−符号の場
合）に優れた溶接鋼管であることが確認された。 PCW = ΔNi + 7.5Mo ≧ 0.1 In addition, the chemical composition (% by weight) of the base material is C: 0.03 to 0.
15%, Si; 0.05 to 0.50%, Mn; 0.50 to 2.00%, Al; 0.005 to 0.1
Contains 0%, the balance contains Fe and unavoidable impurities, further, from among the following components, Cu; 0.05 ~ 2.0%, Ni; 0.05 ~ 2.0%, Cr; 0.05 ~ 2.0%, Mo;
0.05 to 2.0%, Nb; 0.005 to 0.20%, V; 0.005 to 0.20%, Ti; 0.
005 to 0.20%, B; 0.0005 to 0.0020%, Ca; 0.0005 to 0.0050%
1 or 2 or more, and the chemical composition of the weld metal is determined by the difference in the amount of Ni and Mo (mass% by weight) between the weld metal and the base metal, the PCW value is It was confirmed that the satisfied welded steel pipe was excellent in strength, toughness (5 kgf.m or more), and selective corrosion rate (the welded part did not selectively corrode, in the case of -2 in Table 2).
PCW＝ΔNi＋7.5ΔMo≧0.1 ［発明の効果］ 溶接金属部の化学成分及びその組成を調整し、海水環
境などの腐食環境にさらされた溶接金属部の選択腐食に
おいて、溶接金属部のNi及びMo量（量重％）、または溶
接金属部と母材のNi及びMoの夫々のΔNiとΔMo差より新
たにPCW値を求め、このPCW値を前述のように特定するこ
とにより、本発明の溶接鋼管は、高強度と高靱性を有
し、かつ溶接金属部において選択腐食を生じないもので
ある。PCW = ΔNi + 7.5ΔMo ≧ 0.1 [Effect of the invention] Ni and Mo of the weld metal part are selected in the selective corrosion of the weld metal part exposed to corrosive environment such as seawater environment by adjusting the chemical composition and composition of the weld metal part. Welding of the present invention by determining the PCW value newly from the amount (% by weight) or the difference ΔNi and ΔMo between Ni and Mo of the weld metal and the base metal, and specifying the PCW value as described above. The steel pipe has high strength and high toughness and does not cause selective corrosion in the weld metal portion.
第１図は、実施例における母材と溶接金属部の間に流れ
た選択腐食電流（μA/cm2）とΔNi＋7.5ΔMo（PCW）と
の関係グラフである。FIG. 1 is a graph showing the relationship between the selective corrosion current (μA / cm 2 ) flowing between the base metal and the weld metal in the example and ΔNi + 7.5ΔMo (PCW).
───────────────────────────────────────────────────── フロントページの続き (72)発明者 遠藤 茂 東京都千代田区丸の内１丁目１番２号 日 本鋼管株式会社内 (72)発明者 当麻 英夫 東京都千代田区丸の内１丁目１番２号 日 本鋼管株式会社内 (72)発明者 日下 修一 東京都千代田区丸の内１丁目１番２号 日 本鋼管株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Endo Marunouchi, 1-2, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hideo Toma 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Date Inside the Steel Pipe Corporation (72) Inventor Shuichi Kusaka 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Inside the Nippon Steel Pipe Corporation
Claims (2)
金属の化学成分組成が、下記の式を満足することを特徴
とする溶接鋼管。 ΔNi＋7.5ΔMo≧0.1 但し ΔNi＝溶接金属部重量％ ΔMo＝溶接金属部重量％1. The chemical composition of the base material (% by weight) contains C: 0.03 to 0.15% Si; 0.05 to 0.50% Mn; 0.50 to 2.00% Al; 0.005 to 0.10%, with the balance being Fe and inevitable impurities. And a chemical composition of the weld metal satisfies the following formula: Welded steel pipe. ΔNi + 7.5 ΔMo ≧ 0.1 where ΔNi = weld metal part weight% ΔMo = weld metal part weight%
金属の化学成分組成が、下記の式を満足することを特徴
とする溶接鋼管。 ΔNi＋7.5ΔMo≧0.1 但し ΔNi＝Ni（溶接金属部重量％）−Ni（母材重量％） ΔMo＝Mo（溶接金属部重量％）−Mo（母材重量％）2. The chemical composition of the base material (% by weight) contains C: 0.03 to 0.15% Si; 0.05 to 0.50% Mn; 0.50 to 2.00% Al; 0.005 to 0.10%. 1 or 2 or more Cu; 0.05 to 2.0% Ni; 0.05 to 2.0% Cr; 0.05 to 2.0% Mo; 0.05 to 2.0% Nb; 0.005 to 0.20% V; 0.005 to 0.20% Ti: 0.005 to 0.20% B; 0.0005 ~ 0.0020% Ca; 0.0005 to 0.0050%, the balance containing Fe and unavoidable impurities, and the chemical composition of the weld metal satisfies the following formula: Welded steel pipe. ΔNi + 7.5 ΔMo ≧ 0.1 where ΔNi = Ni (wt% of weld metal) -Ni (wt% of base metal) ΔMo = Mo (wt% of weld metal) -Mo (wt% of base metal)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26027189A JPH0814014B2 (en) | 1989-08-11 | 1989-10-06 | Welded steel pipe |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1-206985 | 1989-08-11 | ||
| JP20698589 | 1989-08-11 | ||
| JP26027189A JPH0814014B2 (en) | 1989-08-11 | 1989-10-06 | Welded steel pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03170641A JPH03170641A (en) | 1991-07-24 |
| JPH0814014B2 true JPH0814014B2 (en) | 1996-02-14 |
Family
ID=26515996
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26027189A Expired - Fee Related JPH0814014B2 (en) | 1989-08-11 | 1989-10-06 | Welded steel pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0814014B2 (en) |
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| US7255083B2 (en) | 2002-10-16 | 2007-08-14 | Nissan Motor Co., Ltd. | Sliding structure for automotive engine |
| US7284525B2 (en) | 2003-08-13 | 2007-10-23 | Nissan Motor Co., Ltd. | Structure for connecting piston to crankshaft |
| US7318514B2 (en) | 2003-08-22 | 2008-01-15 | Nissan Motor Co., Ltd. | Low-friction sliding member in transmission, and transmission oil therefor |
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| JP4709568B2 (en) * | 2005-04-01 | 2011-06-22 | 新日本製鐵株式会社 | UO steel pipe with excellent sour resistance |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7255083B2 (en) | 2002-10-16 | 2007-08-14 | Nissan Motor Co., Ltd. | Sliding structure for automotive engine |
| US7322749B2 (en) | 2002-11-06 | 2008-01-29 | Nissan Motor Co., Ltd. | Low-friction sliding mechanism |
| US7500472B2 (en) | 2003-04-15 | 2009-03-10 | Nissan Motor Co., Ltd. | Fuel injection valve |
| US7406940B2 (en) | 2003-05-23 | 2008-08-05 | Nissan Motor Co., Ltd. | Piston for internal combustion engine |
| US7228786B2 (en) | 2003-06-06 | 2007-06-12 | Nissan Motor Co., Ltd. | Engine piston-pin sliding structure |
| US7458585B2 (en) | 2003-08-08 | 2008-12-02 | Nissan Motor Co., Ltd. | Sliding member and production process thereof |
| US7284525B2 (en) | 2003-08-13 | 2007-10-23 | Nissan Motor Co., Ltd. | Structure for connecting piston to crankshaft |
| US7572200B2 (en) | 2003-08-13 | 2009-08-11 | Nissan Motor Co., Ltd. | Chain drive system |
| US7134381B2 (en) | 2003-08-21 | 2006-11-14 | Nissan Motor Co., Ltd. | Refrigerant compressor and friction control process therefor |
| US7318514B2 (en) | 2003-08-22 | 2008-01-15 | Nissan Motor Co., Ltd. | Low-friction sliding member in transmission, and transmission oil therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03170641A (en) | 1991-07-24 |
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