WO2023286338A1 - Ni-cr-mo-based alloy for welded pipe having excellent workability and corrosion resistance - Google Patents

Ni-cr-mo-based alloy for welded pipe having excellent workability and corrosion resistance Download PDF

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WO2023286338A1
WO2023286338A1 PCT/JP2022/009729 JP2022009729W WO2023286338A1 WO 2023286338 A1 WO2023286338 A1 WO 2023286338A1 JP 2022009729 W JP2022009729 W JP 2022009729W WO 2023286338 A1 WO2023286338 A1 WO 2023286338A1
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corrosion resistance
weld
less
ductility
cracks
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PCT/JP2022/009729
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French (fr)
Japanese (ja)
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大樹 前田
富高 韋
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日本冶金工業株式会社
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Priority to CN202280049165.0A priority Critical patent/CN117651784A/en
Priority to DE112022003529.3T priority patent/DE112022003529T5/en
Publication of WO2023286338A1 publication Critical patent/WO2023286338A1/en

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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C19/00Alloys based on nickel or cobalt
    • C22C19/03Alloys based on nickel or cobalt based on nickel
    • C22C19/05Alloys based on nickel or cobalt based on nickel with chromium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon

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  • the present invention relates to Ni--Cr--Mo alloys, and more particularly to Ni--Cr--Mo alloys that can maintain workability and corrosion resistance even after welding.
  • Ni-Cr-Mo alloys are widely used in harsh corrosive environments such as chemical plants, natural gas fields, and oil fields because they are materials with extremely high corrosion resistance. It is also used in the cladding of heaters, etc., and is also used in severe environments where it is prone to corrosion. For use in such fields, various welding and processing are required, and in many cases, processing is applied to the welded portion. Therefore, workability and corrosion resistance are required for the welded portion as well as for the base material portion. However, since the weld zone becomes a solidified structure, the workability is lowered due to the occurrence of cracks and the ductility deterioration of the weld zone as well as the deterioration of corrosion resistance. Therefore, improvement is required.
  • Patent Document 1 For such Ni--Cr--Mo alloys, a manufacturing method in which Mo segregation is reduced for the purpose of improving corrosion resistance (see, for example, Patent Document 1), and a technique for controlling carbides that affect corrosion resistance (for example, Patent Document 2) is shown.
  • Patent Document 2 a manufacturing method in which Mo segregation is reduced for the purpose of improving corrosion resistance
  • Patent Document 2 a technique for controlling carbides that affect corrosion resistance
  • an object of the present invention is to provide a Ni-Cr-Mo alloy that is excellent in weld workability and corrosion resistance.
  • the present invention was completed through experiments. : 0.02 to 1.00%, P: 0.030% or less, S: 0.005% or less, Cr: 18.0 to 24.0%, Mo: 7.5 to 9.0%, Cu: 0.01-0.20%, Al: 0.005-0.400%, Ti: 0.1-1.0%, Fe: 3.0-6.0%, Nb: 2.5-4. 0%, Co: 0.01-0.50%, V: 0.05-0.50%, N: 0.002-0.020%, Sn: 0.003-0.030%, W: 0 .05 to 0.50%, Nb+Ti+V: 2.5 to 4.5%, Cu+10Sn: 0.40 or less, and the balance being Ni and unavoidable impurities.
  • O 0.005% or less
  • Mg 0.001-0.010%
  • Ca 0.0001-0.0100%
  • FIG. 2 is a schematic diagram of sample collection in Examples.
  • the test piece had a plate thickness of 3 mm, a width of 30 mm and a length of 100 mm, and was sampled with the tensile direction parallel to the rolling direction.
  • the workability after welding was evaluated by the elongation ratio defined below.
  • Welds were made by non-filler plasma welding.
  • the welding conditions are a current of 100 A, a voltage of 30 V, a speed of 500 mm/min, a center gas and a back gas of 100% Ar gas, a shield gas of 93% Ar + 7% H2 gas, and a groove shape of I type.
  • the welded portion was made smooth by bead cutting. The test piece was taken so that the weld bead was perpendicular to the tensile direction and the welded part was in the center of the parallel part of the test piece.
  • Table 1 shows the above test results.
  • the total amount of Nb + Ti + V is low even if any one of Ti, Nb, and V is not added (Nos. 8, 9, and 10) and Ti, Nb, and V are all included.
  • the elongation was significantly reduced in sample (#11).
  • the C content and N content were high (Nos. 12 and 13), the elongation was remarkably lowered.
  • Fig. 1 shows the relationship between the amount of Co and the elongation ratio of samples Nos. 1 to 7
  • Fig. 2 shows the relationship between the amount of Cu and the elongation ratio for Nos. 1 to 6. Improvement in elongation was confirmed when Cu or Co was added compared to no addition of Cu or Co (Nos. 6 and 7), and improvement in elongation of the weld zone was observed as the amount of Cu and the amount of Co increased.
  • a test piece with a length of 500 mm was taken in the pipe-making direction of the pipe, and a steel cylinder of 135R (mm) was subjected to a bending test based on the press bending method.
  • the bead was placed on the lower side of the pipe, and the cylinder was pushed in from above.
  • FIG. 3 plots the bending test results at 135R, with the horizontal axis representing the Sn content and the vertical axis representing the Cu content. A sample with no defect was indicated by ⁇ , and a sample with a defect was indicated by ⁇ . In the figure, cracking was not observed in the region where Cu+10 ⁇ Sn was 0.40 or less, but cracking was observed when Cu and Sn exceeded 0.40 and were high. Therefore, it is necessary to limit the amount of Cu and the amount of Sn and to set Cu+10 ⁇ Sn to 0.40 or less.
  • C 0.002-0.020%
  • C is an element that affects workability and corrosion resistance.
  • C combines with Nb, Ti and V in the Ni--Cr--Mo alloy to form carbides. Excess carbide in the weld reduces ductility and initiates cracks during welding. Furthermore, in the heat affected zone due to heat treatment and welding, it combines with Cr and Mo, which are effective for maintaining corrosion resistance, and M6C (M is mainly Mo, Ni, Cr, Si), M23C6 (M is mainly Cr, Mo, Fe) tends to form carbides.
  • C is defined as 0.002 to 0.020%. It is preferably 0.003 to 0.015%. Most preferably, it is between 0.003 and 0.010%.
  • Si 0.02-1.00% Si is an element effective for deoxidation and also needs to be 0.02% or more in order to improve fluidity during welding. However, if the fluidity of molten metal becomes too good, a convex bead cannot be secured in the shape of the welded portion, so it must be suppressed to 1.00% or less. In addition, it is an element that promotes the formation of M6C and M23C6 and lowers intergranular corrosion resistance. Therefore, Si is defined as 0.02 to 1.00%. It is preferably 0.03 to 0.80%, more preferably 0.05 to 0.50%.
  • Mn 0.02-1.00% 0.02% or more is necessary because Mn segregates at grain boundaries and fixes P and S that cause weld cracks and suppresses weld cracks. However, it is an element that promotes the formation of MnS and lowers the pitting corrosion resistance, so the content should be 1.00% or less. Therefore, Mn is defined as 0.02 to 1.00%. It is preferably 0.03 to 0.80%, more preferably 0.05 to 0.50%.
  • P 0.030% or less
  • P is an element that segregates at grain boundaries and deteriorates hot workability and corrosion resistance.
  • the susceptibility to weld cracking is increased by forming a eutectic with a low melting point with Ni. Therefore, it is desirable to reduce P. Therefore, P is set to 0.030% or less. It is preferably 0.028% or less, more preferably 0.020% or less.
  • S 0.005% or less
  • S is an element that segregates at grain boundaries and degrades hot workability, and forms MnS to degrade corrosion resistance.
  • S is defined as 0.005% or less. It is preferably 0.002% or less, more preferably 0.0015% or less.
  • Cr 18.0-24.0% Cr is a very important element for forming a passive film on the surface of the alloy to maintain corrosion resistance. However, the addition of excessive Cr promotes precipitation of M23C6, resulting in deterioration of corrosion resistance. Therefore, Cr is defined as 18.0 to 24.0%. It is preferably 20.0 to 24.0%, more preferably 21.0 to 23.0%.
  • Mo 7.5-9.0% Mo, like Cr, is an important element for forming a passive film and maintaining corrosion resistance. However, excessive addition of Mo promotes precipitation of M6C, resulting in deterioration of corrosion resistance. Also, excessive addition of Mo increases strength but decreases ductility. Therefore, Mo is defined as 7.5-9.0%. Preferably, it is 8.0-9.0%, more preferably 8.0-8.5%.
  • Cu 0.01-0.20%
  • Cu is an important element for improving the ductility of the base material and the weld zone, so 0.01% is necessary. However, excessive addition reduces hot workability and causes weld cracks.
  • Cu is defined as 0.01 to 0.20%. Preferably, it is 0.02-0.15%, more preferably 0.02-0.10%.
  • Al 0.005-0.400% Since Al is an element effective for deoxidation, 0.005% is required. By making Al 0.005% or more, O can be made 0.005% or less. However, excessive addition reduces hot workability. In addition, it forms alumina clusters, resulting in linear defects on the surface of the alloy plate. Therefore, Al is set to 0.005 to 0.400%. It is preferably 0.020 to 0.300%, more preferably 0.050 to 0.300%.
  • Ti 0.1-1.0% Ti combines with C and N to form carbides (TiC) and nitrides (TiN), which refines the solidification structure of the weld zone and improves ductility, while suppressing the formation of M6C and M23C6, which cause a decrease in corrosion resistance. do.
  • TiC carbides
  • TiN nitrides
  • TiO 2 oxides
  • Fe 3.0-6.0% Fe is added to reduce the production cost and at the same time has the effect of reducing the amount of O in the alloy. However, since excessive addition causes deterioration of corrosion resistance, it is defined as 3.0 to 6.0% or less. It is preferably 3.0 to 5.0%, more preferably 3.0 to 4.5%.
  • Nb 2.5-4.5%
  • Nb combines with C and N to form carbides (NbC) and nitrides (NbN), thereby refining the solidified structure of the weld zone and improving ductility. Also, it suppresses the formation of M6C and M23C6, which cause deterioration of corrosion resistance. On the other hand, it dissolves and increases the strength, but reduces the ductility. Moreover, excessive addition of Nb causes a decrease in hot workability due to a decrease in ductility development temperature. Therefore, Nb is defined as 2.5 to 4.5%. Preferably, it is 2.8-4.0%, more preferably 2.8-3.8%.
  • Co 0.01-0.50% Since Co is an important element for improving the ductility of the base material and weld zone, 0.01% is necessary. However, excessive addition reduces hot workability and causes weld cracks. Therefore, Co is defined as 0.01 to 0.50%. Preferably, it is 0.01 to 0.30%. More preferably 0.01 to 0.20%.
  • V 0.05-0.50% Like Nb and Ti, V combines with C and N to form carbides (VC) and nitrides, thereby refining the solidified structure of the weld zone and improving ductility. Also, it suppresses the formation of M6C and M23C6, which cause deterioration of corrosion resistance. On the other hand, it dissolves and increases the strength, but reduces the ductility. V was defined as 0.05-0.50%. Preferably, it is 0.10 to 0.50%. More preferably 0.10 to 0.30%.
  • N 0.002-0.020%
  • N combines with Nb, Ti and V to form nitrides and carbonitrides.
  • An optimum amount of nitrides and carbonitrides improves ductility by refining the solidified structure of the weld zone.
  • excessive nitrides and carbonitrides in the weld zone reduce ductility and become starting points for cracks during welding.
  • N is defined as 0.002 to 0.020%.
  • it is 0.002 to 0.016%. More preferably, it is 0.002 to 0.010%.
  • Sn 0.003-0.030%
  • Sn is an element that improves corrosion resistance when added in a very small amount.
  • Sn is defined as 0.003 to 0.030%. It is preferably 0.004 to 0.020%, more preferably 0.006 to 0.010%.
  • W 0.05-0.50% Like Mo, W has the effect of improving corrosion resistance, but excessive addition forms carbides and lowers corrosion resistance. Therefore, W is defined as 0.05 to 0.50%. Preferably, it is 0.10 to 0.40%. More preferably, it is 0.10 to 0.30%.
  • Nb+Ti+V 2.5-4.5%
  • Nb, Ti and V combine with C and N to form carbides, nitrides and carbonitrides.
  • An optimum amount of nitrides and carbonitrides improves the ductility of the weld zone by refining the solidified structure of the weld zone.
  • excessive nitrides and carbonitrides in the weld zone reduce ductility and become starting points for cracks during welding.
  • Nb+Ti+V 2.5 to 4.5%.
  • it is 2.8-4.5%, more preferably 3.0-4.0%.
  • Cu+10Sn 0.40 or less
  • the amount of Sn added to Cu increases, a compound with a low melting point is formed, which causes cracks in the weld zone. Therefore, it is set to 0.40 or less. It is preferably 0.35 or less, more preferably 0.30 or less.
  • O 0.005% or less
  • O forms oxides and deteriorates weldability and hot workability. It also forms blow holes during welding and improves melt flow during welding. Therefore, it is desirable to reduce it.
  • the formation of Al 2 O 3 clusters and Ti oxides lowers the hot workability and causes linear defects. Therefore, O is set to 0.005% or less. Preferably, it is 0.004% or less, more preferably 0.003% or less.
  • Mg 0.001-0.010% Like Mn, Mg segregates at grain boundaries and fixes P and S, which cause weld cracks, to suppress weld cracks. On the other hand, when Mg is contained in a certain amount or more, inclusions aggregate on the weld bead, causing deterioration of workability and deterioration of corrosion resistance due to starting points of corrosion. In addition, MgO inclusions are formed and clustered, which causes surface defects in the product. Therefore, Mg was defined as 0.001 to 0.010%. Preferably, it is 0.002 to 0.008%. More preferably, it is 0.002 to 0.005%.
  • Ca 0.0010 to 0.0100%
  • Ca like Mn, segregates at grain boundaries and fixes P and S, which cause weld cracks, to suppress weld cracks.
  • Ca when Ca is contained in a certain amount or more, inclusions aggregate on the weld bead, causing deterioration of workability and deterioration of corrosion resistance due to starting points of corrosion.
  • CaO inclusions are formed and clustered, which causes surface defects in products. Therefore, Ca is defined as 0.0010 to 0.0100%. Preferably, it is 0.0020 to 0.0070%. More preferably, it is 0.0020 to 0.0050%.
  • the Vickers hardness of the base metal, welded zone, and heat-affected zone after welding is 280HV or less.
  • the above balance consists of Ni and unavoidable impurities.
  • the unavoidable impurities are components that are mixed due to various factors during the industrial production of the Ni-based alloy, and those that are allowed to be contained within a range that does not adversely affect the effects of the present invention. means.
  • heat treatment it is more desirable to apply heat treatment to the entire processed part and the part including the welded part.
  • a heat treatment of about 1000° C. ⁇ 1 min in an air atmosphere is sufficient. That is, it is possible to avoid heat treatment at a high temperature, for example, up to 1160° C. for a long time, for example, up to about 1 hour.
  • oxide scale is generated in an air atmosphere, and it is necessary to remove this by pickling or mechanical polishing, but there is an advantage that this can be avoided.
  • Ni--Cr--Mo alloy a method for producing a Ni--Cr--Mo alloy according to the present invention.
  • the method for producing the Ni--Cr--Mo alloy of the present invention is not particularly limited, it is desirable to produce it by the following method.
  • raw materials such as scrap, Ni, Cr, and Mo are melted in an electric furnace and decarburized by oxygen blowing in AOD (Argon Oxygen Decarburization) and/or VOD (Vacuum Oxygen Decarburization).
  • FIG. 4 shows a schematic diagram of sampling of the test piece.
  • a cold-rolled sheet 1 includes a weld bead 2 .
  • a test piece 3 containing only the base material portion and a test piece 4 containing the base material portion and the welded portion were prepared and subjected to a tensile test.
  • Welds were made by non-filler plasma welding.
  • the welding conditions are a current of 100 A, a voltage of 30 V, a speed of 500 mm/min, a center gas and a back gas of 100% Ar gas, a shield gas of 93% Ar + 7% H2 gas, and a groove shape of I type.
  • the welded portion was made smooth by bead cutting.
  • the test piece 4 was sampled so that the weld bead was perpendicular to the tensile direction and the welded portion was in the center of the parallel portion of the test piece.
  • Both test pieces 3 and 4 had a plate thickness of 3 mm, a width of 30 mm and a length of 100 mm, and were sampled with the tensile direction parallel to the rolling direction.
  • Elongation ratio (% of elongation of test piece including weld zone) / (% of elongation of test piece of base metal part only)
  • test piece having a length of 500 mm was taken in the pipe-making direction of the pipe, and bending tests of 135R, 115R, and 95R were performed using a steel cylinder based on the press bending method.
  • the bead was placed on the lower side of the pipe, and the cylinder was pushed in from above.
  • Defects (cracks) in the bending part were confirmed by using an optical microscope and magnifying them 20 to 400 times to confirm the presence or absence of defects. In addition, when the crack exceeded 0.1 mm, it was regarded as defective. D indicates that cracks occurred at 135R, no cracks occurred at 135R, C indicates that cracks occurred at 115R, no cracks occurred at 115R, and cracks occurred at 95R. A was rated as B, and a rated as A was that no cracks occurred even in 95R.
  • Hardness of Weld Zone Vickers hardness was measured in the base metal, weld zone, and heat-affected zone to evaluate the hardness of the weld zone.
  • a 3 mm material was used for the test piece, and the cross section was finished by polishing with #120 emery paper.
  • a load of 1 kgf during measurement was applied to each of the base material, the weld zone, and the heat-affected zone, and the average hardness was evaluated by performing three-point measurements.
  • Numbers 1 to 20 have only one C among the judgments and are within the allowable range, and are examples of the invention.
  • Nos. 21 to 38 contain D or have two or more Cs even if they do not contain D, are outside the allowable range, and are comparative examples. Comparative examples Nos. 21 to 38 will be described below.
  • No. 21 has no Co added, so the ductility is D, which is out of range.
  • No. 22 has a high C content, the ductility, cracking, and corrosion resistance are C, and the hardness of the weld zone is also high, which is out of the range.
  • Nb+Ti+V is high and out of range, so the crack is D, and the hardness at the weld is also high and out of range.
  • Number 31 has no V added, so the ductility is D, which is out of range.
  • Number 32 is out of range with high N and D in ductility and cracking.
  • the Cu+10Sn was high, so the crack was D, which is out of range.
  • Number 35 is out of range with a low W and a D in corrosion resistance, which is out of range.
  • Number 36 is out of range with a high W and a D in corrosion resistance, which is out of range.
  • Cu+10Sn is high, so the crack is D, which is out of range.
  • C and N are low, so the ductility is D, which is out of range.

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Abstract

[Problem] To provide an Ni-Cr-Mo-based alloy having excellent workability and corrosion resistance at a welded part. [Solution] An Ni-Cr-Mo-based alloy comprising, by mass%, 0.002 to 0.020% of C, 0.02 to 1.00% of Si, 0.02 to 1.00% of Mn, 0.030% or less of P, 0.005% or less of S, 18.0 to 24.0% of Cr, 7.5 to 9.0% of Mo, 0.01 to 0.20% of Cu, 0.005 to 0.400% of Al, 0.1 to 1.0% of Ti, 3.0 to 6.0% of Fe, 2.5 to 4.0% of Nb, 0.01 to 0.50% of Co, 0.05 to 0.50% of V, 0.002 to 0.020% of N, 0.003 to 0.030% of Sn, 0.05 to 0.50% of W, 2.5 to 4.5% of Nb + Ti + V, 0.40% or less of Cu + 10 Sn, and the balance Ni and inevitable impurities.

Description

加工性、耐食性に優れる溶接管用Ni-Cr-Mo系合金Ni-Cr-Mo alloy for welded pipes with excellent workability and corrosion resistance
 本発明は、Ni-Cr-Mo合金に係り、特に、溶接後も加工性および耐食性を維持することができるNi-Cr-Mo合金に関する。 The present invention relates to Ni--Cr--Mo alloys, and more particularly to Ni--Cr--Mo alloys that can maintain workability and corrosion resistance even after welding.
 Ni-Cr-Mo合金は、極めて耐食性に優れた材料であるため、化学プラント、天然ガス田、油田など過酷な腐食環境下にて広く用いられている。また、ヒーターの被覆管などにも用いられ、こちらも腐食し易い厳しい環境で使用されている。このような分野で使用するには、様々な溶接や加工が必要となり、溶接部に加工を施す場合も多い。そのため、母材部と同様に溶接部においても加工性や耐食性が求められる。しかしながら、溶接部は凝固組織となるため、耐食性の低下とともに割れの発生や溶接部の延性低下により加工性が低下するため、改善が求められている。  Ni-Cr-Mo alloys are widely used in harsh corrosive environments such as chemical plants, natural gas fields, and oil fields because they are materials with extremely high corrosion resistance. It is also used in the cladding of heaters, etc., and is also used in severe environments where it is prone to corrosion. For use in such fields, various welding and processing are required, and in many cases, processing is applied to the welded portion. Therefore, workability and corrosion resistance are required for the welded portion as well as for the base material portion. However, since the weld zone becomes a solidified structure, the workability is lowered due to the occurrence of cracks and the ductility deterioration of the weld zone as well as the deterioration of corrosion resistance. Therefore, improvement is required.
 このようなNi-Cr-Mo合金について、耐食性を改善する目的でMoの偏析を低減した製造方法(例えば、特許文献1参照)や、耐食性へ影響を与える炭化物を制御する技術(例えば、特許文献2参照)が示されている。しかしながら、これら文献においては溶接性や溶接部の加工性については何ら述べられていない。 For such Ni--Cr--Mo alloys, a manufacturing method in which Mo segregation is reduced for the purpose of improving corrosion resistance (see, for example, Patent Document 1), and a technique for controlling carbides that affect corrosion resistance (for example, Patent Document 2) is shown. However, these documents do not mention anything about weldability or weld workability.
 一方、溶接部の加工性や耐食性について、フェライト系ステンレス鋼における文献(例えば特許文献3、4参照)は知られているものの、合金系が異なるため、これらの技術をNi-Cr-Mo合金にそのまま適用することはできない。 On the other hand, regarding the workability and corrosion resistance of welds, although the literature on ferritic stainless steel (see, for example, Patent Documents 3 and 4) is known, the alloy system is different, so these techniques are applied to Ni-Cr-Mo alloys. It cannot be applied as is.
国際公開第2019/107456号公報International Publication No. 2019/107456 特開2019-52349号公報JP 2019-52349 A 特開2002-275590号公報JP-A-2002-275590 特開2008-231542号公報JP 2008-231542 A
 上記の技術を鑑み、本発明では、溶接部の加工性、耐食性に優れるNi-Cr-Mo系合金を提供することを目的とする。 In view of the above technology, an object of the present invention is to provide a Ni-Cr-Mo alloy that is excellent in weld workability and corrosion resistance.
 発明者らは、上記の課題の解決に向けて鋭意研究を行った。その結果、溶接部において優れた加工性とするためには、溶接部自体の延性を向上することが必要であり、材料自体の延性を向上させるためCu、Co、C、N量を制御するとともに、溶接部の凝固組織の微細化するためNb、Ti、Vの適量添加が効果的であることを見出した。さらに、溶接部においては炭化物や炭窒化物、低融点化する共晶析出物の抑制することによって割れの発生を低減できることが分かった。特にCuとSnにおいては添加量を制御し、適切な量とすることによって溶接部の延性が向上できることが分かった。さらに耐食性においてはSnやWといった元素の添加、耐食性劣化の原因となる炭化物や腐食の起点となる酸化物を低減することが効果的であることを見出した。 The inventors conducted intensive research to solve the above problems. As a result, in order to achieve excellent workability in the weld, it is necessary to improve the ductility of the weld itself. It has been found that the addition of appropriate amounts of Nb, Ti, and V is effective in refining the solidified structure of the weld zone. Furthermore, it was found that the occurrence of cracks can be reduced in the weld by suppressing carbides, carbonitrides, and eutectic precipitates that lower the melting point. In particular, it was found that the ductility of the weld zone can be improved by controlling the amount of addition of Cu and Sn to an appropriate amount. Furthermore, it has been found that addition of elements such as Sn and W and reduction of carbides that cause deterioration of corrosion resistance and oxides that cause corrosion start points are effective in terms of corrosion resistance.
 このように、本願発明は実験を通して完成したものであり、すなわち本発明は、以下、質量%にて、C:0.002~0.020%、Si:0.02~1.00%、Mn:0.02~1.00%、P:0.030%以下、S:0.005%以下、Cr:18.0~24.0%、Mo:7.5~9.0%、Cu:0.01~0.20%、Al:0.005~0.400%、Ti:0.1~1.0%、Fe:3.0~6.0%、Nb:2.5~4.0%、Co:0.01~0.50%、V:0.05~0.50%、N:0.002~0.020%、Sn:0.003~0.030%、W:0.05~0.50%、Nb+Ti+V:2.5~4.5%、Cu+10Sn:0.40以下、残部Niおよび不可避的不純物からなるNi-Cr-Mo系合金である。 Thus, the present invention was completed through experiments. : 0.02 to 1.00%, P: 0.030% or less, S: 0.005% or less, Cr: 18.0 to 24.0%, Mo: 7.5 to 9.0%, Cu: 0.01-0.20%, Al: 0.005-0.400%, Ti: 0.1-1.0%, Fe: 3.0-6.0%, Nb: 2.5-4. 0%, Co: 0.01-0.50%, V: 0.05-0.50%, N: 0.002-0.020%, Sn: 0.003-0.030%, W: 0 .05 to 0.50%, Nb+Ti+V: 2.5 to 4.5%, Cu+10Sn: 0.40 or less, and the balance being Ni and unavoidable impurities.
 本発明においては、O:0.005%以下、Mg:0.001~0.010%、Ca:0.0001~0.0100%であることが好ましい。 In the present invention, it is preferable that O: 0.005% or less, Mg: 0.001-0.010%, and Ca: 0.0001-0.0100%.
本発明の予備実験におけるCo量と伸び比の関係を示すグラフである。It is a graph which shows the relationship between the amount of Co in the preliminary experiment of this invention, and an elongation ratio. 本発明の予備実験におけるCu量と伸び比の関係を示すグラフである。It is a graph which shows the relationship between the amount of Cu in the preliminary experiment of this invention, and an elongation ratio. 本発明の予備実験の曲げ試験におけるSn量とCu量と、欠陥の有無の関係を示すプロット図である。It is a plot figure which shows the relationship between the amount of Sn, the amount of Cu, and the presence or absence of a defect in the bending test of the preliminary experiment of this invention. 実施例における試験片採取の模式図である。FIG. 2 is a schematic diagram of sample collection in Examples.
 発明者らは、上記の課題の解決に向けて以下の実験1~実験3を行って、本発明を完成させるに至った。以下にその検討について説明する。 The inventors conducted the following Experiments 1 to 3 to solve the above problems, and completed the present invention. The study will be described below.
<実験1>
溶接部の延性評価
 実験室において、Ni-21%Cr-8%Mo-4.5%Feを基本組成とし、これにC、N、Mn、Cu、Ti、Nb、Co、V、Sn、Wを添加した種々の成分を有するNi-Cr-Mo系合金を高周波誘導炉にて溶解し、鋳型に鋳込み合金塊を得た。これを熱間鍛造により厚さ8mmの鍛造材とし、1100℃にて焼鈍、その後酸洗を行い、冷間圧延により厚み3mm冷延板を得た。さらにこれを1100℃にて焼鈍を行った後、母材部のみと溶接部を含む試験片を作製した。試験片は板厚3mm、幅30mm、長さ100mmのサイズであり、引張方向が圧延方向に平行な方向で採取した。下記の定義する伸び比にて、溶接後の加工性を評価した。なお、伸び比は溶接部の延性が母材に対してどの程度維持されているかを示す。
 伸び比=(溶接部を含む試験片の伸び%)/(母材部のみの試験片の伸び%)
<Experiment 1>
Evaluation of ductility of weld zone In a laboratory, Ni-21%Cr-8%Mo-4.5%Fe was used as a basic composition, and C, N, Mn, Cu, Ti, Nb, Co, V, Sn, W was melted in a high-frequency induction furnace and cast into a mold to obtain an alloy ingot. This was hot forged into a forged material having a thickness of 8 mm, annealed at 1100° C., pickled after that, and cold rolled to obtain a cold-rolled sheet having a thickness of 3 mm. Further, after annealing this at 1100° C., a test piece including only the base metal portion and the weld portion was produced. The test piece had a plate thickness of 3 mm, a width of 30 mm and a length of 100 mm, and was sampled with the tensile direction parallel to the rolling direction. The workability after welding was evaluated by the elongation ratio defined below. The elongation ratio indicates how much the ductility of the weld zone is maintained with respect to the base metal.
Elongation ratio = (% of elongation of test piece including weld zone) / (% of elongation of test piece of base metal part only)
 溶接部はノンフィラープラズマ溶接によって作製した。溶接条件は、電流100A、電圧30V、速度500mm/min、センターガスおよびバックガスは100%Arガス、シールドガスは93%Ar+7%Hガスを使用、開先形状はI型である。また、溶接部はビードカットにより平滑となるようにした。試験片は溶接ビードが引張方向と垂直かつ溶接部が試験片平行部中央になるようになるように採取した。 Welds were made by non-filler plasma welding. The welding conditions are a current of 100 A, a voltage of 30 V, a speed of 500 mm/min, a center gas and a back gas of 100% Ar gas, a shield gas of 93% Ar + 7% H2 gas, and a groove shape of I type. In addition, the welded portion was made smooth by bead cutting. The test piece was taken so that the weld bead was perpendicular to the tensile direction and the welded part was in the center of the parallel part of the test piece.
 表1に上記の試験結果を示す。種々の成分の影響を調査した結果、Ti、Nb、Vのいずれか1つが無添加の試料(番号8、9、10)およびTi、Nb、Vが全て含まれていても合計Nb+Ti+V量の低い試料(番号11)において伸びが著しく低下していた。また、C量、N量が高い(番号12、13)場合においても伸びが著しく低下していた。 Table 1 shows the above test results. As a result of investigating the effects of various components, the total amount of Nb + Ti + V is low even if any one of Ti, Nb, and V is not added (Nos. 8, 9, and 10) and Ti, Nb, and V are all included. The elongation was significantly reduced in sample (#11). In addition, when the C content and N content were high (Nos. 12 and 13), the elongation was remarkably lowered.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
 図1に番号1~7の試料のCo量と伸び比の関係、図2に番号1~6のCu量と伸び比の関係を示す。CuやCo無添加(番号6、7)に比べて添加した場合、伸びの改善が確認され、Cu量およびCo量の増加にともなう溶接部の伸びの向上がみられた。 Fig. 1 shows the relationship between the amount of Co and the elongation ratio of samples Nos. 1 to 7, and Fig. 2 shows the relationship between the amount of Cu and the elongation ratio for Nos. 1 to 6. Improvement in elongation was confirmed when Cu or Co was added compared to no addition of Cu or Co (Nos. 6 and 7), and improvement in elongation of the weld zone was observed as the amount of Cu and the amount of Co increased.
 溶接部の延性を向上するためには材料自体の延性を確保するためCu、Co、C、N量を制御することが効果的であることを見出した。さらに、溶接部においては炭化物や炭窒化物、低融点化する共晶析出物が割れの起点となって加工性が低下する場合がある。そこで以下のように溶接部の割れの評価を行った。  In order to improve the ductility of the welded part, it was found that controlling the amount of Cu, Co, C, and N was effective in ensuring the ductility of the material itself. Furthermore, in the welded portion, carbides, carbonitrides, and eutectic precipitates that lower the melting point may cause cracks and deteriorate the workability. Therefore, cracks in the weld zone were evaluated as follows.
<実験2>
溶接部の割れ評価
 実験室において、Ni-21%Cr-8%Mo-4.5%Fe-3.5%Nb-0.010%C-0.010%Nを基本組成とし、これにMn、Cu、Ti、Nb、Co、V、Sn、Wを添加した種々の成分を有するNi-Cr-Mo系合金を高周波誘導炉にて溶解し、鋳型に鋳込み合金塊を得た。これを熱間圧延により厚さ8mmのコイル材とし、1100℃にて焼鈍、その後酸洗を行い、冷間圧延により厚み0.7mmとした。されにこれを1100℃にて焼鈍を行った後、スリットを行い狭幅コイル(31.4mm)とした。これを連続ラインにて成形、溶接を施した。溶接部はノンフィラープラズマ溶接によって作製した。溶接条件は、電流100A、電圧10V、速度1000mm/min、センターガスおよびバックガスは100%Arガス、シールドガスは93%Ar+7%Hガスを使用した。このようにして、外径10mmのパイプを作製し曲げ試験を実施した。
<Experiment 2>
Crack evaluation of weld zone In the laboratory, Ni-21%Cr-8%Mo-4.5%Fe-3.5%Nb-0.010%C-0.010%N was used as a basic composition, and Mn was added to this. , Cu, Ti, Nb, Co, V, Sn, and W were melted in a high-frequency induction furnace and cast into a mold to obtain an alloy ingot. This was hot-rolled into a coil material having a thickness of 8 mm, annealed at 1100° C., pickled after that, and cold-rolled to a thickness of 0.7 mm. Further, after annealing this at 1100° C., it was slit to form a narrow coil (31.4 mm). This was molded and welded on a continuous line. Welds were made by non-filler plasma welding. The welding conditions were a current of 100 A, a voltage of 10 V, a speed of 1000 mm/min, a center gas and a back gas of 100% Ar gas, and a shield gas of 93% Ar + 7% H2 gas. In this manner, a pipe having an outer diameter of 10 mm was produced and subjected to a bending test.
 すなわち、パイプの造管方向に500mmの長さの試験片を採取し、鉄鋼製の135R(mm)のシリンダをプレス曲げ方式に基づいて曲げ試験を行った。なお、ビードはパイプの下側になるように配置して、上側よりシリンダを押し込んだ。 That is, a test piece with a length of 500 mm was taken in the pipe-making direction of the pipe, and a steel cylinder of 135R (mm) was subjected to a bending test based on the press bending method. The bead was placed on the lower side of the pipe, and the cylinder was pushed in from above.
 曲げ部の欠陥(割れ)の確認は光学顕微鏡を用いて20~400倍に拡大して、欠陥の有無を確認した。なお、割れは0.1mmを超える場合、欠陥有りとした。 Defects (cracks) in the bending part were confirmed by using an optical microscope and magnifying them 20 to 400 times to confirm the presence or absence of defects. In addition, when the crack exceeded 0.1 mm, it was regarded as defective.
 表2に上記の試験結果を示す。また、図3は135Rでの曲げ試験結果をプロットしたものであり、横軸がSn量、縦軸がCu量を示したものである。欠陥が無かったものを〇、欠陥が観察されたものを×で表した。図中にはCu+10×Snが0.40以下となる領域においては割れの発生は観察されなかったが、0.40を超えるCuとSnが高い場合、割れの発生が観察された。よって、Cu量とSn量の制限とともにCu+10×Snを0.40以下とする必要がある。 Table 2 shows the above test results. FIG. 3 plots the bending test results at 135R, with the horizontal axis representing the Sn content and the vertical axis representing the Cu content. A sample with no defect was indicated by ◯, and a sample with a defect was indicated by ×. In the figure, cracking was not observed in the region where Cu+10×Sn was 0.40 or less, but cracking was observed when Cu and Sn exceeded 0.40 and were high. Therefore, it is necessary to limit the amount of Cu and the amount of Sn and to set Cu+10×Sn to 0.40 or less.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
<実験3>
溶接部の耐食性評価
 実験1と同様の試料を用いて溶接部の耐食性の評価として腐食試験を実施した。溶接部はビードカットにより平滑となるようにした後、#120のエメリー紙で研磨して仕上げた。この試験片を6%FeClと1%HClからなる600mlの溶液に120時間浸漬した。試験温度は80、85、90、95℃にて試験を行い、臨界孔食発生温度(CPT)を測定した。孔食は25μm以上のものを孔食発生とみなした。結果を表1に併記した。
<Experiment 3>
Evaluation of Corrosion Resistance of Welded Portion Using the same sample as in Experiment 1, a corrosion test was performed to evaluate the corrosion resistance of the welded portion. The welded portion was made smooth by bead cutting, and then finished by polishing with #120 emery paper. The specimen was immersed in a 600 ml solution consisting of 6% FeCl3 and 1 % HCl for 120 hours. The test temperature was 80, 85, 90 and 95° C., and the critical pitting initiation temperature (CPT) was measured. A pitting corrosion of 25 μm or more was regarded as occurrence of pitting corrosion. The results are also shown in Table 1.
 W、Snを添加していない番号1、番号3およびC量、N量が高い番号12、番号13においては試験温度が80℃においても孔食の発生が確認された。一方でWやSnの添加量が高かった番号5においてはCPTが95℃であり、番号6においてもCPTが90℃であり耐食性の向上が確認された。この結果より、溶接部の耐食性においてはSnやWといった元素の添加、耐食性劣化の原因となる炭化物や腐食の起点となる酸化物を低減することが効果的である。 Pitting corrosion was confirmed even at a test temperature of 80°C in Nos. 1 and 3, to which W and Sn were not added, and Nos. 12 and 13, in which the amounts of C and N were high. On the other hand, No. 5, in which the amounts of W and Sn added were high, had a CPT of 95° C., and No. 6 also had a CPT of 90° C., confirming an improvement in corrosion resistance. From this result, it is effective to add elements such as Sn and W, and to reduce carbides that cause deterioration of corrosion resistance and oxides that cause corrosion to improve the corrosion resistance of welds.
 次に、本発明のNi-Cr-Mo系合金の成分組成を限定する理由について説明する。なお、%はすべてmass%(質量%)である。
C:0.002~0.020%
 Cは加工性および耐食性に影響する元素である。Ni-Cr-Mo系合金中においてCはNb、Ti、Vと結合し、炭化物を形成する。溶接部の過剰な炭化物は延性を低下させるとともに溶接時の割れの起点となる。さらに、熱処理工程や溶接による熱影響部において、耐食性の維持に有効なCr、Moと結合し、M6C(Mは主にMo、Ni、Cr、Si)、M23C6(Mは主にCr、Mo、Fe)の炭化物を形成しやすい。これらの炭化物の周囲にはCr、Moの欠乏層が生じてしまい、必要とされる耐食性を低下させてしまうため0.020%以下とする。一方で、溶接部の炭化物は凝固組織を微細化することによって延性を向上するため0.002%以上の含有が必要である。
 以上のことから、Cは0.002~0.020%と規定した。好ましくは0.003~0.015%である。最も好ましくは、0.003~0.010%である。
Next, the reason for limiting the chemical composition of the Ni--Cr--Mo alloy of the present invention will be explained. In addition, all % are mass% (mass%).
C: 0.002-0.020%
C is an element that affects workability and corrosion resistance. C combines with Nb, Ti and V in the Ni--Cr--Mo alloy to form carbides. Excess carbide in the weld reduces ductility and initiates cracks during welding. Furthermore, in the heat affected zone due to heat treatment and welding, it combines with Cr and Mo, which are effective for maintaining corrosion resistance, and M6C (M is mainly Mo, Ni, Cr, Si), M23C6 (M is mainly Cr, Mo, Fe) tends to form carbides. A Cr and Mo depleted layer is formed around these carbides, which lowers the required corrosion resistance. On the other hand, the carbides in the weld must be contained in an amount of 0.002% or more in order to improve the ductility by refining the solidified structure.
Based on the above, C is defined as 0.002 to 0.020%. It is preferably 0.003 to 0.015%. Most preferably, it is between 0.003 and 0.010%.
Si:0.02~1.00%
 Siは脱酸のために有効な元素であるとともに溶接時の湯流れ性を向上するため0.02%以上は必要である。しかしながら、湯流れ性が良くなりすぎると、溶接部形状においては凸ビードを確保できなくなるため、1.00%以下に抑えなければならない。また、M6C、M23C6の形成を助長して、耐粒界腐食性を低下させる元素である。したがって、Siは0.02~1.00%と規定した。好ましくは0.03~0.80%、より好ましくは、0.05~0.50%である。
Si: 0.02-1.00%
Si is an element effective for deoxidation and also needs to be 0.02% or more in order to improve fluidity during welding. However, if the fluidity of molten metal becomes too good, a convex bead cannot be secured in the shape of the welded portion, so it must be suppressed to 1.00% or less. In addition, it is an element that promotes the formation of M6C and M23C6 and lowers intergranular corrosion resistance. Therefore, Si is defined as 0.02 to 1.00%. It is preferably 0.03 to 0.80%, more preferably 0.05 to 0.50%.
Mn:0.02~1.00%
 Mnは粒界に偏析して、溶接割れを起こすP、Sを固定して溶接割れを抑制するため、0.02%以上は必要である。しかしながら、MnSの形成を助長し、耐孔食性を低下させる元素であるため1.00%以下とする必要がある。したがって、Mnは0.02~1.00%と規定した。好ましくは、0.03~0.80%であり、より好ましくは、0.05~0.50%である。
Mn: 0.02-1.00%
0.02% or more is necessary because Mn segregates at grain boundaries and fixes P and S that cause weld cracks and suppresses weld cracks. However, it is an element that promotes the formation of MnS and lowers the pitting corrosion resistance, so the content should be 1.00% or less. Therefore, Mn is defined as 0.02 to 1.00%. It is preferably 0.03 to 0.80%, more preferably 0.05 to 0.50%.
P:0.030%以下
 Pは粒界に偏析および、熱間加工性と耐食性を劣化させる元素である。またNiと低融点の共晶を生成することで溶接割れ感受性を高める。そのため、Pは低減することが望ましい。よって、Pは0.030%以下とした。好ましくは、0.028%以下であり、より好ましくは0.020%以下である。
P: 0.030% or less P is an element that segregates at grain boundaries and deteriorates hot workability and corrosion resistance. In addition, the susceptibility to weld cracking is increased by forming a eutectic with a low melting point with Ni. Therefore, it is desirable to reduce P. Therefore, P is set to 0.030% or less. It is preferably 0.028% or less, more preferably 0.020% or less.
S:0.005%以下
 Sは、Pと同様に粒界に偏析して、熱間加工性を低下させる元素であるとともに、MnSを形成し耐食性を低下させるため、極力低減することが望ましい。また、溶接時に湯流れ性を良くするが、湯流れ性が良くなりすぎると、溶接部形状においては凸ビードを確保できなくなる。よって、Sは0.005%以下と定めた。好ましくは、0.002%以下であり、より好ましくは0.0015%以下である。
S: 0.005% or less Like P, S is an element that segregates at grain boundaries and degrades hot workability, and forms MnS to degrade corrosion resistance. In addition, although the molten metal flow property is improved during welding, if the molten metal flow property becomes too good, it becomes impossible to secure a convex bead in the shape of the welded portion. Therefore, S is defined as 0.005% or less. It is preferably 0.002% or less, more preferably 0.0015% or less.
Cr:18.0~24.0%
 Crは合金の表面に不働態被膜を形成して耐食性を維持するために、とても重要な元素である。しかしながら、過剰なCrの添加はM23C6の析出を助長するために、耐食性の低下を引き起こしてしまう。したがって、Crは18.0~24.0%と規定した。好ましくは20.0~24.0%であり、より好ましくは、21.0~23.0%である。
Cr: 18.0-24.0%
Cr is a very important element for forming a passive film on the surface of the alloy to maintain corrosion resistance. However, the addition of excessive Cr promotes precipitation of M23C6, resulting in deterioration of corrosion resistance. Therefore, Cr is defined as 18.0 to 24.0%. It is preferably 20.0 to 24.0%, more preferably 21.0 to 23.0%.
Mo:7.5~9.0%
 MoはCrと同様に不働態被膜を形成して耐食性を維持するために重要な元素である。しかしながら、過剰なMoの添加はM6Cの析出を助長することによる耐食性の低化を引き起こしてしまう。また、過剰なMoの添加は強度が上昇する一方で、延性を低下させる。したがって、Moは7.5~9.0%と規定した。好ましくは、8.0~9.0%であり、より好ましくは8.0~8.5%である。
Mo: 7.5-9.0%
Mo, like Cr, is an important element for forming a passive film and maintaining corrosion resistance. However, excessive addition of Mo promotes precipitation of M6C, resulting in deterioration of corrosion resistance. Also, excessive addition of Mo increases strength but decreases ductility. Therefore, Mo is defined as 7.5-9.0%. Preferably, it is 8.0-9.0%, more preferably 8.0-8.5%.
Cu:0.01~0.20%
 Cuは母材部および溶接部の延性を向上する重要な元素であるので、0.01%は必要となる。しかしながら、過度の添加は熱間加工性を低下させ、溶接割れを引き起こす。また、溶接時に湯流れ性を良くするが、湯流れ性が良くなりすぎると、溶接部形状においては凸ビードを確保できなくなる。したがって、Cuは0.01~0.20%と規定した。好ましくは、0.02~0.15%であり、より好ましくは0.02~0.10%である。
Cu: 0.01-0.20%
Cu is an important element for improving the ductility of the base material and the weld zone, so 0.01% is necessary. However, excessive addition reduces hot workability and causes weld cracks. In addition, although the molten metal flow property is improved during welding, if the molten metal flow property becomes too good, it becomes impossible to secure a convex bead in the shape of the welded portion. Therefore, Cu is defined as 0.01 to 0.20%. Preferably, it is 0.02-0.15%, more preferably 0.02-0.10%.
Al:0.005~0.400%
 Alは、脱酸に効果的な元素であるので、0.005%は必要となる。Alを0.005%以上とすることにより、Oを0.005%以下とすることができる。しかしながら、過度の添加は熱間加工性を低下させる。また、アルミナのクラスターを形成し、合金板表面に線状の欠陥をもたらしてしまう。そのため、Alは0.005~0.400%と定めた。好ましくは、0.020~0.300%であり、より好ましくは0.050~0.300%である。
Al: 0.005-0.400%
Since Al is an element effective for deoxidation, 0.005% is required. By making Al 0.005% or more, O can be made 0.005% or less. However, excessive addition reduces hot workability. In addition, it forms alumina clusters, resulting in linear defects on the surface of the alloy plate. Therefore, Al is set to 0.005 to 0.400%. It is preferably 0.020 to 0.300%, more preferably 0.050 to 0.300%.
Ti:0.1~1.0%
 TiはC、Nと結合し炭化物(TiC)、窒化物(TiN)を形成することにより溶接部の凝固組織を微細化、延性を向上するとともに、耐食性の低下を引き起こすM6C、M23C6の形成を抑制する。一方で、過剰の添加は、多量の炭化物(TiC)、窒化物(TiN)および酸化物(TiO)を形成して熱間加工性や延性の低下を引き起こす。したがって、Tiは0.1~1.0%と規定した。好ましくは、0.1~0.8%であり、より好ましくは0.1~0.5%である。
Ti: 0.1-1.0%
Ti combines with C and N to form carbides (TiC) and nitrides (TiN), which refines the solidification structure of the weld zone and improves ductility, while suppressing the formation of M6C and M23C6, which cause a decrease in corrosion resistance. do. On the other hand, excessive addition forms a large amount of carbides (TiC), nitrides (TiN) and oxides (TiO 2 ), causing deterioration of hot workability and ductility. Therefore, Ti is defined as 0.1 to 1.0%. Preferably, it is 0.1-0.8%, more preferably 0.1-0.5%.
Fe:3.0~6.0%
 Feは製造コストを低減させるために添加されると同時に、合金中のO量を低下する効果がある。しかしながら、過剰な添加は耐食性の低下を引き起こすため3.0~6.0%以下と規定した。好ましくは、3.0~5.0%であり、より好ましくは3.0~4.5%である。
Fe: 3.0-6.0%
Fe is added to reduce the production cost and at the same time has the effect of reducing the amount of O in the alloy. However, since excessive addition causes deterioration of corrosion resistance, it is defined as 3.0 to 6.0% or less. It is preferably 3.0 to 5.0%, more preferably 3.0 to 4.5%.
Nb:2.5~4.5%
 NbはTiと同様C、Nと結合し炭化物(NbC)、窒化物(NbN)を形成することにより溶接部の凝固組織を微細化、延性を向上する。また、耐食性の低下を引き起こすM6C、M23C6の形成を抑制する。一方で、固溶して強度が上昇する一方で、延性を低下させる。また、Nbの過剰の添加は延性発現温度が低下による熱間加工性が低下を引き起こす。そこで、Nbは2.5~4.5%と規定した。好ましくは、2.8~4.0%であり、より好ましくは2.8~3.8%である。
Nb: 2.5-4.5%
Like Ti, Nb combines with C and N to form carbides (NbC) and nitrides (NbN), thereby refining the solidified structure of the weld zone and improving ductility. Also, it suppresses the formation of M6C and M23C6, which cause deterioration of corrosion resistance. On the other hand, it dissolves and increases the strength, but reduces the ductility. Moreover, excessive addition of Nb causes a decrease in hot workability due to a decrease in ductility development temperature. Therefore, Nb is defined as 2.5 to 4.5%. Preferably, it is 2.8-4.0%, more preferably 2.8-3.8%.
Co:0.01~0.50%
 Coは母材部および溶接部の延性を向上する重要な元素であるので、0.01%は必要となる。しかしながら、過度の添加は熱間加工性を低下させ、溶接割れを引き起こす。したがって、Coは0.01~0.50%と規定した。好ましくは、0.01~0.30%である。より好ましくは0.01~0.20%である。
Co: 0.01-0.50%
Since Co is an important element for improving the ductility of the base material and weld zone, 0.01% is necessary. However, excessive addition reduces hot workability and causes weld cracks. Therefore, Co is defined as 0.01 to 0.50%. Preferably, it is 0.01 to 0.30%. More preferably 0.01 to 0.20%.
V:0.05~0.50%
 VはNb、Tiと同様C、Nと結合し炭化物(VC)、窒化物を形成することにより溶接部の凝固組織を微細化し、延性を向上する。また、耐食性の低下を引き起こすM6C、M23C6の形成を抑制する。一方で、固溶して強度が上昇する一方で、延性を低下させる。Vは0.05~0.50%と規定した。好ましくは、0.10~0.50%である。より好ましくは0.10~0.30%である。
V: 0.05-0.50%
Like Nb and Ti, V combines with C and N to form carbides (VC) and nitrides, thereby refining the solidified structure of the weld zone and improving ductility. Also, it suppresses the formation of M6C and M23C6, which cause deterioration of corrosion resistance. On the other hand, it dissolves and increases the strength, but reduces the ductility. V was defined as 0.05-0.50%. Preferably, it is 0.10 to 0.50%. More preferably 0.10 to 0.30%.
N:0.002~0.020%
 NはNb、Ti、Vと結合し、窒化物や炭窒化物を形成する。最適な量の窒化物、炭窒化物は溶接部の凝固組織を微細化することによって、延性を向上する。一方で溶接部の過剰な窒化物、炭窒化物は延性を低下させるとともに溶接時の割れの起点となる。また、N量が高くなると溶接部のブローホール数が増加する。したがって、Nは0.002~0.020%と規定した。好ましくは、0.002~0.016%である。さらに好ましくは、0.002~0.010%である。
N: 0.002-0.020%
N combines with Nb, Ti and V to form nitrides and carbonitrides. An optimum amount of nitrides and carbonitrides improves ductility by refining the solidified structure of the weld zone. On the other hand, excessive nitrides and carbonitrides in the weld zone reduce ductility and become starting points for cracks during welding. In addition, when the amount of N increases, the number of blowholes in the weld increases. Therefore, N is defined as 0.002 to 0.020%. Preferably, it is 0.002 to 0.016%. More preferably, it is 0.002 to 0.010%.
Sn:0.003~0.030%
 Snは微量の添加により耐食性を向上させる元素である。一方で、低融点の化合物を形成することにより、溶接部での割れの原因となる。したがって、Snは0.003~0.030%と規定した。好ましくは、0.004~0.020%であり、より好ましくは0.006~0.010%である。
Sn: 0.003-0.030%
Sn is an element that improves corrosion resistance when added in a very small amount. On the other hand, the formation of compounds with low melting points causes cracks in welds. Therefore, Sn is defined as 0.003 to 0.030%. It is preferably 0.004 to 0.020%, more preferably 0.006 to 0.010%.
W:0.05~0.50%
 WはMoと同様に耐食性を向上する効果があるが、過度の添加は炭化物を形成して、耐食性を低下する。したがって、Wは0.05~0.50%と規定した。好ましくは、0.10~0.40%である。より好ましくは、0.10~0.30%である。
W: 0.05-0.50%
Like Mo, W has the effect of improving corrosion resistance, but excessive addition forms carbides and lowers corrosion resistance. Therefore, W is defined as 0.05 to 0.50%. Preferably, it is 0.10 to 0.40%. More preferably, it is 0.10 to 0.30%.
Nb+Ti+V:2.5~4.5%
 Nb、Ti、VはCやNと結合し、炭化物、窒化物および炭窒化物を形成する。最適な量の窒化物、炭窒化物は溶接部の凝固組織を微細化することによって、溶接部の延性を向上する。一方で溶接部の過剰な窒化物、炭窒化物は延性を低下させるとともに溶接時の割れの起点となる。Nb+Ti+V:2.5~4.5%とする。好ましくは、2.8~4.5%であり、より好ましくは3.0~4.0%である。
Nb+Ti+V: 2.5-4.5%
Nb, Ti and V combine with C and N to form carbides, nitrides and carbonitrides. An optimum amount of nitrides and carbonitrides improves the ductility of the weld zone by refining the solidified structure of the weld zone. On the other hand, excessive nitrides and carbonitrides in the weld zone reduce ductility and become starting points for cracks during welding. Nb+Ti+V: 2.5 to 4.5%. Preferably, it is 2.8-4.5%, more preferably 3.0-4.0%.
Cu+10Sn:0.40以下
 CuおよびSnを添加した場合、Cuに対するSnの添加量が多くなると低融点の化合物を形成することにより、溶接部での割れの原因となる。そこで0.40以下とする。好ましくは0.35以下、より好ましくは、0.30以下である。
Cu+10Sn: 0.40 or less When Cu and Sn are added, if the amount of Sn added to Cu increases, a compound with a low melting point is formed, which causes cracks in the weld zone. Therefore, it is set to 0.40 or less. It is preferably 0.35 or less, more preferably 0.30 or less.
 本合金ではO、Mg、Caの濃度を以下の通り制御することが望ましい。
O:0.005%以下
 Oは酸化物を形成し、溶接性、熱間加工性を低下させる。また溶接時のブローホールを形成、また、溶接時に湯流れ性を良くするが、湯流れ性が良くなりすぎると、溶接部形状においては凸ビードを確保できなくなる。そのため低減することが望ましい。さらにAlのクラスターやTiの酸化物の形成によって熱間加工性を低下させてしまうとともに、線状の欠陥をもたらしてしまう。よって、Oは0.005%以下とした。好ましくは、0.004%以下であり、より好ましくは0.003%以下である。
In this alloy, it is desirable to control the concentrations of O, Mg and Ca as follows.
O: 0.005% or less O forms oxides and deteriorates weldability and hot workability. It also forms blow holes during welding and improves melt flow during welding. Therefore, it is desirable to reduce it. Furthermore, the formation of Al 2 O 3 clusters and Ti oxides lowers the hot workability and causes linear defects. Therefore, O is set to 0.005% or less. Preferably, it is 0.004% or less, more preferably 0.003% or less.
Mg:0.001~0.010%
 MgはMnと同様に粒界に偏析して、溶接割れを起こすP、Sを固定して溶接割れを抑制する。一方で、Mgを一定量以上に含有すると溶接ビード上に介在物が凝集、加工性の劣化や腐食の起点となることによる耐食性の低下を引き起こす。また、MgOの介在物を形成し、クラスター化することによりとなり、製品において表面欠陥の原因となる。したがって、Mgは0.001~0.010%と規定した。好ましくは、0.002~0.008%である。より好ましくは、0.002~0.005%である。
Mg: 0.001-0.010%
Like Mn, Mg segregates at grain boundaries and fixes P and S, which cause weld cracks, to suppress weld cracks. On the other hand, when Mg is contained in a certain amount or more, inclusions aggregate on the weld bead, causing deterioration of workability and deterioration of corrosion resistance due to starting points of corrosion. In addition, MgO inclusions are formed and clustered, which causes surface defects in the product. Therefore, Mg was defined as 0.001 to 0.010%. Preferably, it is 0.002 to 0.008%. More preferably, it is 0.002 to 0.005%.
Ca:0.0010~0.0100%、
 CaはMnと同様に粒界に偏析して、溶接割れを起こすP、Sを固定して溶接割れを抑制する。一方で、Caを一定量以上に含有すると溶接ビード上に介在物が凝集、加工性の劣化や腐食の起点となることによる耐食性の低下を引き起こす。また、CaOの介在物を形成し、クラスター化することによりとなり、製品において表面欠陥の原因となる。したがって、Caは0.0010~0.0100%と規定した。好ましくは、0.0020~0.0070%である。より好ましくは、0.0020~0.0050%である。
Ca: 0.0010 to 0.0100%,
Ca, like Mn, segregates at grain boundaries and fixes P and S, which cause weld cracks, to suppress weld cracks. On the other hand, when Ca is contained in a certain amount or more, inclusions aggregate on the weld bead, causing deterioration of workability and deterioration of corrosion resistance due to starting points of corrosion. In addition, CaO inclusions are formed and clustered, which causes surface defects in products. Therefore, Ca is defined as 0.0010 to 0.0100%. Preferably, it is 0.0020 to 0.0070%. More preferably, it is 0.0020 to 0.0050%.
溶接後の母材部、溶接部、熱影響部のビッカース硬さがそれぞれ280HV以下
 溶接後の溶接部、熱影響部においては炭化物や炭窒化物の形成や組織の変化によって硬さが大きくなる可能性があるが、硬さが上昇すると、加工性が悪くなる。そこで、溶接ままでの母材部、溶接部、熱影響部のビッカース硬さがそれぞれ280HV以下とする。好ましくは270HV以下、さらに好ましくは260以下である。ここでは特に限定しないが、強度を保つ観点から180HV以上が好ましい。
The Vickers hardness of the base metal, welded zone, and heat-affected zone after welding is 280HV or less.The hardness of the welded zone and heat-affected zone after welding can increase due to the formation of carbides and carbonitrides and changes in the structure. However, as the hardness increases, workability deteriorates. Therefore, the Vickers hardness of the base metal portion, welded portion, and heat-affected zone as welded is set to 280 HV or less. It is preferably 270 HV or less, more preferably 260 HV or less. Although not particularly limited here, 180 HV or more is preferable from the viewpoint of maintaining the strength.
 本発明のNi-Cr-Mo系合金では、上記の残部はNiおよび不可避的不純物からなる。ここで、不可避的不純物とはNi基合金を工業的に製造する際、種々の要因によって混入してくる成分であり、本発明の作用効果に悪影響を及ぼさない範囲で含有を許容されるものを意味する。 In the Ni--Cr--Mo alloy of the present invention, the above balance consists of Ni and unavoidable impurities. Here, the unavoidable impurities are components that are mixed due to various factors during the industrial production of the Ni-based alloy, and those that are allowed to be contained within a range that does not adversely affect the effects of the present invention. means.
 また、加工性の向上には、加工を受けた全体部分、および溶接部を含む部分に熱処理を施すとより望ましい。本発明合金であれば、大気雰囲気中1000℃×1min程度の熱処理でも十分である。つまり、高温、例えば1160℃まで、長時間、例えば最長1h程度の熱処理を避けることができる。このような、高温、長時間の熱処理の場合、大気雰囲気では酸化スケールが生成し、これを酸洗あるいは機械的研磨などにより除去する必要がでてくるが、これを回避できる利点がある。 Also, in order to improve workability, it is more desirable to apply heat treatment to the entire processed part and the part including the welded part. For the alloy of the present invention, a heat treatment of about 1000° C.×1 min in an air atmosphere is sufficient. That is, it is possible to avoid heat treatment at a high temperature, for example, up to 1160° C. for a long time, for example, up to about 1 hour. In the case of such high-temperature, long-time heat treatment, oxide scale is generated in an air atmosphere, and it is necessary to remove this by pickling or mechanical polishing, but there is an advantage that this can be avoided.
 次に本発明のNi-Cr-Mo系合金の製造方法について説明する。本発明のNi-Cr-Mo系合金の製造方法は特に限定されるものではないが、以下の方法で製造するのが望ましい。まずスクラップ、Ni、Cr、Moなどの原料を電気炉で溶解し、AOD(Argon Oxygen Decarburization)および/またはVOD(Vacuum Oxygen Decarburization)にて酸素吹精して脱炭を行う。その後、Alと石灰石を投入してCr還元を行い、さらに石灰石と蛍石を投入し、溶融合金上にCaO-SiO-Al-MgO-F系スラグを形成して脱酸、脱硫を行い、得られた溶融合金を、連続鋳造機にて鋳造しスラブ製造し、その後、熱間圧延、必要に応じて冷間圧延を行い、厚板や熱延鋼板、冷延鋼板などの薄板とする。 Next, a method for producing a Ni--Cr--Mo alloy according to the present invention will be described. Although the method for producing the Ni--Cr--Mo alloy of the present invention is not particularly limited, it is desirable to produce it by the following method. First, raw materials such as scrap, Ni, Cr, and Mo are melted in an electric furnace and decarburized by oxygen blowing in AOD (Argon Oxygen Decarburization) and/or VOD (Vacuum Oxygen Decarburization). After that, Al and limestone are added for Cr reduction, and then limestone and fluorite are added to form CaO-- SiO.sub.2 --Al.sub.2O.sub.3--MgO--F system slag on the molten alloy for deoxidation and desulfurization. Then, the resulting molten alloy is cast with a continuous casting machine to produce a slab, then hot rolled and, if necessary, cold rolled to form thin plates such as thick plates, hot-rolled steel plates, and cold-rolled steel plates. and
 以下の実施例によってさらに本発明を詳細に説明する。ただし、本発明はその趣旨を超えない限りこれらの例に限定されるものではない。まず、まずスクラップ、Ni、Cr、Moなどの原料を電気炉で溶解し、AODおよびVODにて酸素吹精して脱炭を行った。その後、Alと石灰石を投入してCr還元を行い、さらに石灰石と蛍石を投入し、溶融合金上にCaO-SiO-Al-MgO-F系スラグを形成して脱酸、脱硫を行った。このようにして精錬した溶融合金を、連続鋳造機にて鋳造しスラブを得た。その後、スラブをステッケルミルで熱間圧延し、引き続き冷間圧延して板厚3mmの冷延板を製造した。表3に製造した合金の化学成分を、表4に測定条件、評価結果を示す。 The following examples further illustrate the invention. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. First, raw materials such as scrap, Ni, Cr, and Mo were melted in an electric furnace and decarburized by oxygen blowing with AOD and VOD. After that, Al and limestone are added for Cr reduction, and then limestone and fluorite are added to form CaO-- SiO.sub.2 --Al.sub.2O.sub.3--MgO--F system slag on the molten alloy for deoxidation and desulfurization. did The molten alloy thus refined was cast by a continuous casting machine to obtain a slab. After that, the slab was hot-rolled in a Steckel mill and then cold-rolled to produce a cold-rolled sheet with a thickness of 3 mm. Table 3 shows the chemical compositions of the alloys produced, and Table 4 shows the measurement conditions and evaluation results.
溶接部の延性評価
 3mmtの冷延板を1100℃にて焼鈍を行った後、溶接部の延性評価を行った。図4に試験片の採取の模式図を示す。冷延板1は、溶接ビード2を含む。この溶接した冷延板1より、母材部のみを含む試験片3と、母材部および溶接部を含む試験片4を作製し、引張試験を実施した。溶接部はノンフィラープラズマ溶接によって作製した。溶接条件は、電流100A、電圧30V、速度500mm/min、センターガスおよびバックガスは100%Arガス、シールドガスは93%Ar+7%Hガスを使用、開先形状はI型である。また、溶接部はビードカットにより平滑となるようにした。試験片4は溶接ビードが引張方向と垂直かつ溶接部が試験片平行部中央になるようになるように採取した。なお試験片3、4はいずれも板厚3mm、幅30mm、長さ100mmのサイズであり、引張方向が圧延方向に平行な方向で採取した。下記の定義する伸び比にて、溶接後の加工性を評価した。伸び比が0.6未満の場合をD、0.6以上0.7未満をC、0.7以上0.8未満をB、0.8以上をAとした。
 伸び比=(溶接部を含む試験片の伸び%)/(母材部のみの試験片の伸び%)
Evaluation of Ductility of Weld Zone After annealing a 3 mmt cold-rolled sheet at 1100° C., ductility evaluation of the weld zone was carried out. FIG. 4 shows a schematic diagram of sampling of the test piece. A cold-rolled sheet 1 includes a weld bead 2 . From this welded cold-rolled sheet 1, a test piece 3 containing only the base material portion and a test piece 4 containing the base material portion and the welded portion were prepared and subjected to a tensile test. Welds were made by non-filler plasma welding. The welding conditions are a current of 100 A, a voltage of 30 V, a speed of 500 mm/min, a center gas and a back gas of 100% Ar gas, a shield gas of 93% Ar + 7% H2 gas, and a groove shape of I type. In addition, the welded portion was made smooth by bead cutting. The test piece 4 was sampled so that the weld bead was perpendicular to the tensile direction and the welded portion was in the center of the parallel portion of the test piece. Both test pieces 3 and 4 had a plate thickness of 3 mm, a width of 30 mm and a length of 100 mm, and were sampled with the tensile direction parallel to the rolling direction. The workability after welding was evaluated by the elongation ratio defined below. When the elongation ratio is less than 0.6, D is 0.6 or more and less than 0.7, C is 0.7 or more and less than 0.8, and A is 0.8 or more.
Elongation ratio = (% of elongation of test piece including weld zone) / (% of elongation of test piece of base metal part only)
溶接部の割れ評価
 3mmtの冷延板を1100℃にて焼鈍、その後酸洗を行い、さらに冷間圧延により厚み0.7mmtまで圧延した。その後、連続ラインにて成形、溶接を施してハイプの製造を行った。溶接部の割れの評価として0.7mm材を用いて直径10mmのパイプを作製し曲げ試験を実施した。溶接条件は、電流100A、電圧10V、速度1000mm/min、センターガスおよびバックガスは100%Arガス、シールドガスは93%Ar+7%Hガスを使用した。また、パイプの造管方向に500mmの長さの試験片を採取し、鉄鋼製のシリンダを使用して、プレス曲げ方式に基づいて135R、115R、95Rの曲げ試験を行った。なお、ビードはパイプの下側になるように配置して、上側よりシリンダを押し込んだ。
Crack Evaluation of Weld Portion A 3 mmt cold-rolled sheet was annealed at 1100° C., then pickled, and further cold-rolled to a thickness of 0.7 mmt. After that, molding and welding were performed in a continuous line to manufacture hype. For the evaluation of cracks in the welded part, a pipe with a diameter of 10 mm was produced using a 0.7 mm material and a bending test was carried out. The welding conditions were a current of 100 A, a voltage of 10 V, a speed of 1000 mm/min, a center gas and a back gas of 100% Ar gas, and a shield gas of 93% Ar + 7% H2 gas. Further, a test piece having a length of 500 mm was taken in the pipe-making direction of the pipe, and bending tests of 135R, 115R, and 95R were performed using a steel cylinder based on the press bending method. The bead was placed on the lower side of the pipe, and the cylinder was pushed in from above.
 曲げ部の欠陥(割れ)の確認は光学顕微鏡を用いて20~400倍に拡大して、欠陥の有無を確認した。なお、割れは0.1mmを超える場合、欠陥有りとした。135Rにて割れが発生したものをD、135Rにて割れが発生しておらず、115Rにて割れが発生したものをC、115Rにて割れが発生しておらず、95Rにて割れが発生したものをB、95Rにおいても割れが発生しなかったものをAとした。 Defects (cracks) in the bending part were confirmed by using an optical microscope and magnifying them 20 to 400 times to confirm the presence or absence of defects. In addition, when the crack exceeded 0.1 mm, it was regarded as defective. D indicates that cracks occurred at 135R, no cracks occurred at 135R, C indicates that cracks occurred at 115R, no cracks occurred at 115R, and cracks occurred at 95R. A was rated as B, and a rated as A was that no cracks occurred even in 95R.
溶接部の耐食性評価
 溶接部の耐食性の評価として腐食試験を実施した。試験片は3mm材を用いた。また、溶接部はビードカットにより平滑となるようにした後、#120 のエメリー紙で研磨して仕上げた。この試験片を6%FeClと1%HClからなる600mlの溶液に120時間浸漬した。試験温度は80、85、90、95℃にて試験を行い、臨界孔食発生温度(CPT)を測定した。孔食は25μm以上のものを孔食発生とみなした。CPTが80℃のものをD、CPTが85℃のものをC、CPTが90℃のものをB、CPTが95℃のものをAとした。
Evaluation of Corrosion Resistance of Welds A corrosion test was performed to evaluate the corrosion resistance of welds. A 3 mm material was used for the test piece. The welded portion was made smooth by bead cutting, and then finished by polishing with #120 emery paper. The specimen was immersed in a 600 ml solution consisting of 6% FeCl3 and 1 % HCl for 120 hours. The test temperature was 80, 85, 90 and 95° C., and the critical pitting initiation temperature (CPT) was measured. A pitting corrosion of 25 μm or more was regarded as occurrence of pitting corrosion. D indicates that the CPT is 80°C, C indicates that the CPT is 85°C, B indicates that the CPT is 90°C, and A indicates that the CPT is 95°C.
溶接部の硬さ評価
 溶接部の硬さ評価として母材および溶接部、熱影響部でのビッカース硬さを測定した。試験片は3mm材を用い、断面を#120のエメリー紙で研磨して仕上げた。測定時の荷重1kgfにて母材および溶接部、熱影響部それぞれで三点測定を行い平均の硬さを評価した。
Evaluation of Hardness of Weld Zone Vickers hardness was measured in the base metal, weld zone, and heat-affected zone to evaluate the hardness of the weld zone. A 3 mm material was used for the test piece, and the cross section was finished by polishing with #120 emery paper. A load of 1 kgf during measurement was applied to each of the base material, the weld zone, and the heat-affected zone, and the average hardness was evaluated by performing three-point measurements.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
 以下に表3、4に示した実施例について説明する。番号1~20は、判定のうちCが1個までしかなく許容範囲内であり、発明例であり、本発明の範囲を満たすことから溶接部においても加工性、耐食性に優れる。 The examples shown in Tables 3 and 4 are described below. Numbers 1 to 20 have only one C among the judgments and are within the allowable range, and are examples of the invention.
 番号21~38は、Dを含むか、含まないとしてもCが2個以上あり、許容範囲外であり、比較例である。以下に番号21~38の比較例について説明する。
番号21はCoが添加されていないため、延性がDであり範囲外である。
番号22はC量が高いため、延性、割れ、耐食性がCであり、溶接部の硬さも高く、範囲外である。
番号23はNb+Ti+Vが高く外れたため、割れがDであり、溶接部での硬さも高く外れてしまっており、範囲外である。
番号24はNbが低く、Nb+Ti+Vが低く外れたため、延性がDであり、範囲外である。
番号25はCoが高く外れたため、割れがDであり、範囲外である。
番号26はSnが低く外れたため、耐食性がDであり、範囲外である。
番号27はCuが添加されていないため、延性がDであり、範囲外である。
番号28はCuが高く外れたため、割れがDであり、範囲外である。
番号29はNbが高く外れ、延性および割れがDであり、溶接部での硬さも高く外れてしまっており、範囲外である。
番号30はVが高く外れ、延性および割れがDであり、範囲外である。
番号31はVが添加されていないため、延性がDであり範囲外である。
番号32はNが高く外れ、延性および割れがDであり、範囲外である。
番号33、34はCu+10Snが高く外れたため、割れがDであり、範囲外である。
番号35はWが低く外れており、耐食性がDであり、範囲外である。
番号36はWが高く外れており、耐食性がDであり、範囲外である。
番号37はCu+10Snが高く外れたため、割れがDであり、範囲外である。
番号38はC、Nが低く外れたため、延性がDであり範囲外である。
Nos. 21 to 38 contain D or have two or more Cs even if they do not contain D, are outside the allowable range, and are comparative examples. Comparative examples Nos. 21 to 38 will be described below.
No. 21 has no Co added, so the ductility is D, which is out of range.
Since No. 22 has a high C content, the ductility, cracking, and corrosion resistance are C, and the hardness of the weld zone is also high, which is out of the range.
In No. 23, Nb+Ti+V is high and out of range, so the crack is D, and the hardness at the weld is also high and out of range.
No. 24 has a low Nb and a low Nb+Ti+V, so the ductility is D, which is out of range.
No. 25 has a high Co content, so the crack is D, which is out of range.
No. 26 has a low Sn value, so the corrosion resistance is D, which is out of range.
No. 27 has no Cu added, so the ductility is D, which is out of range.
In No. 28, the Cu content is high, so the crack is D, which is out of the range.
No. 29 is out of the range because Nb is high, ductility and cracking are D, and the hardness at the weld is also high and out of range.
Number 30 is out of range with high V and D in ductility and cracking.
No. 31 has no V added, so the ductility is D, which is out of range.
Number 32 is out of range with high N and D in ductility and cracking.
In Nos. 33 and 34, the Cu+10Sn was high, so the crack was D, which is out of range.
Number 35 is out of range with a low W and a D in corrosion resistance, which is out of range.
Number 36 is out of range with a high W and a D in corrosion resistance, which is out of range.
In No. 37, Cu+10Sn is high, so the crack is D, which is out of range.
In No. 38, C and N are low, so the ductility is D, which is out of range.
 1:(焼鈍された)冷延板、2:溶接ビード、3:母材部のみを含む試験片、4:母材部と溶接部を含む試験片

 
1: (annealed) cold-rolled sheet, 2: weld bead, 3: test piece containing only base material, 4: test piece containing base material and weld

Claims (2)

  1.  以下、質量%にて、C:0.002~0.020%、Si:0.02~1.00%、Mn:0.02~1.00%、P:0.030%以下、S:0.005%以下、Cr:18.0~24.0%、Mo:7.5~9.0%、Cu:0.01~0.20%、Al:0.005~0.400%、Ti:0.1~1.0%、Fe:3.0~6.0%、Nb:2.5~4.0%、Co:0.01~0.50%、V:0.05~0.50%、N:0.002~0.020%、Sn:0.003~0.030%、W:0.05~0.50%、Nb+Ti+V:2.5~4.5%、Cu+10Sn:0.40以下、残部Niおよび不可避的不純物からなるNi-Cr-Mo系合金。 C: 0.002 to 0.020%, Si: 0.02 to 1.00%, Mn: 0.02 to 1.00%, P: 0.030% or less, S: 0.005% or less, Cr: 18.0 to 24.0%, Mo: 7.5 to 9.0%, Cu: 0.01 to 0.20%, Al: 0.005 to 0.400%, Ti: 0.1-1.0%, Fe: 3.0-6.0%, Nb: 2.5-4.0%, Co: 0.01-0.50%, V: 0.05- 0.50%, N: 0.002-0.020%, Sn: 0.003-0.030%, W: 0.05-0.50%, Nb+Ti+V: 2.5-4.5%, Cu+10Sn : 0.40 or less, Ni--Cr--Mo based alloy consisting of the balance Ni and unavoidable impurities.
  2.  O:0.005%以下、Mg:0.001~0.010%、Ca:0.0001~0.0100%であることを特徴とする請求項1に記載のNi-Cr-Mo系合金。

     
    The Ni--Cr--Mo alloy according to claim 1, characterized by O: 0.005% or less, Mg: 0.001-0.010%, and Ca: 0.0001-0.0100%.

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JPH1030140A (en) * 1996-07-15 1998-02-03 Sumitomo Metal Ind Ltd Nickel-base alloy excellent in corrosion resistance and workability
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JPS53108022A (en) * 1977-03-04 1978-09-20 Hitachi Ltd Iron-nickel-chromium-molybdenum alloy of high ductility
JPH0483841A (en) * 1990-07-26 1992-03-17 Nippon Yakin Kogyo Co Ltd Fe-ni series alloy excellent in high temperature corrosion resistance and weldability
JPH1030140A (en) * 1996-07-15 1998-02-03 Sumitomo Metal Ind Ltd Nickel-base alloy excellent in corrosion resistance and workability
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JP2021183720A (en) * 2020-05-22 2021-12-02 日本製鉄株式会社 Ni-BASED ALLOY TUBE AND WELDED JOINT

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