JP6386918B2 - Solid wire for gas shielded arc welding - Google Patents

Solid wire for gas shielded arc welding Download PDF

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JP6386918B2
JP6386918B2 JP2015002376A JP2015002376A JP6386918B2 JP 6386918 B2 JP6386918 B2 JP 6386918B2 JP 2015002376 A JP2015002376 A JP 2015002376A JP 2015002376 A JP2015002376 A JP 2015002376A JP 6386918 B2 JP6386918 B2 JP 6386918B2
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pwht
weld metal
aw
wire
low
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JP2016124025A (en
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直樹 坂林
直樹 坂林
雅哉 齋藤
雅哉 齋藤
木本 勇
勇 木本
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日鐵住金溶接工業株式会社
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Description

  The present invention relates to a solid wire for gas shielded arc welding, and a tensile strength of a long-time post-weld heat treatment (heat treatment performed for the purpose of removing welding residual stress and improving mechanical properties of a welded portion: hereinafter referred to as PWHT). Further, the present invention relates to a solid wire for gas shielded arc welding in which a weld metal having excellent toughness in a low temperature region can be obtained and welding workability and weld crack resistance are good.

  In recent years, in the fields of oil and gas energy related fields (offshore structures), transportation (gas carriers, pipelines), storage (pressure vessels), etc., low temperature steels with excellent mechanical properties in the low temperature range (for example, Aluminum killed steel, Ni-containing steel, etc.) are widely used. For such low-temperature steel welding, gas shielded arc welding solid wires with high efficiency and excellent mechanical properties of weld metal are used. For example, Patent Document 1, Patent Document 2, and Patent Document 3 describe weld metal. A solid wire for gas shielded arc welding for low temperature steel having good low temperature toughness and tensile strength is disclosed.

  In the welding of low temperature steel, a long time PWHT (Post Weld Heat Treatment) is often performed for the purpose of further improving the residual stress and mechanical properties of the weld metal. In this case, the welding of the solid wire for gas shielded arc welding disclosed in Patent Documents 1 to 3 can ensure the strength and low temperature toughness of the weld metal as it is (hereinafter referred to as “AW”), but for a long time. After PWHT, the strength and low temperature toughness of the weld metal are lowered, and there is a problem that necessary mechanical properties cannot be obtained.

  As a means for preventing a decrease in the strength and toughness of the weld metal after PWHT, for example, Patent Document 4 and Patent Document 5 include a high amount of Ni that has an effect of improving the strength without decreasing the low temperature toughness of the weld metal. A solid wire for gas shielded arc welding for tensile steel is disclosed. However, in the solid wire for gas shielded arc welding described in Patent Document 4 and Patent Document 5, in the case of PWHT for a long time, the strength and low temperature toughness of the weld metal are lowered, and the required mechanical properties cannot be obtained. There's a problem. Patent Document 6 discloses a solid wire for gas shielded arc welding to which Ti, Ni, Cr, Mo or the like, which has an effect of increasing the toughness and strength of a weld metal, is added. However, since the solid wire for gas shielded arc welding described in Patent Document 6 is not a solid wire for gas shielded arc welding that assumes welding of low temperature steel, sufficient low temperature toughness of the weld metal cannot be ensured. In addition, the wire feedability is poor, the arc is not stable, and there is a problem that welding workability is poor, such as a large amount of spatter generation.

JP 60-96394 A Japanese Patent Laid-Open No. 62-238094 JP-A-3-294083 Japanese Patent Laid-Open No. 1-233088 JP 2003-31471 A JP-A 63-157795

  The present invention has been made in order to solve the above-mentioned problems. In welding of low-temperature steel, a weld metal having an appropriate strength and good and stable toughness in a low-temperature region even after AW and long-time PWHT is obtained. Another object of the present invention is to provide a solid wire for gas shielded arc welding that is excellent in welding workability, such as being excellent in welding crack resistance, having a stable arc and a small amount of spatter generation.

In order to solve the above-mentioned problems, the present inventors have studied in detail, focusing on the composition of the solid wire for gas shielded arc welding.
As a result, C, Si, Mn, Cu, Ni, Mo, Ti in the wire are required to simultaneously achieve the proper strength of the weld metal and at the same time improve the stable low temperature toughness even after AW and long-time PWHT. By optimizing the amounts of B and B, it is possible to improve the low-temperature toughness and increase the strength of the weld metal after PWHT for a long time while ensuring the necessary strength and low-temperature toughness of the AW weld metal. I found out. We also found that by optimizing C, Cu, Ni, Ti, and B in the wire, the weld cracking resistance was improved, the arc during welding was stabilized, and the amount of spatter was reduced, improving welding workability. .

  The present invention has been completed based on these findings, and the gist of the invention is as follows.

(1)% by mass with respect to the total mass of the wire,
C: 0.01 to 0.08%,
Si: 0.2-0.6%
Mn: 0.5 to 1.5%
Cu: 0.15-0.40%,
Ni: 3.0-4.0%,
Mo: 0.10 to 0.40%,
Ti: 0.020 to 0.100%,
B: A solid wire for gas shielded arc welding containing 0.0010 to 0.0100%, the balance being Fe and inevitable impurities.

  According to the solid wire for gas shielded arc welding of the present invention, in gas shielded arc welding of low-temperature steel, the welding arc is stable and the amount of spatter generation is small, so that the welding workability is good and the weld crack resistance is improved. In addition, it is possible to provide a solid wire for gas shielded arc welding that can ensure the strength and low temperature toughness of an appropriate weld metal even after a long period of PWHT, and obtain a high-quality weld metal free from defects.

  In gas shielded arc welding of low-temperature steel, the present inventors can obtain a weld metal having appropriate strength and low-temperature toughness even after AW and long-time PWHT, and have excellent weld crack resistance and stable arc. The composition of the solid wire for gas shielded arc welding, which provides good welding workability such as low spatter generation, was studied in detail.

As a result, C, Si, Mn, Cu, Ni, Mo, Ti in the wire are required to simultaneously achieve the proper strength of the weld metal and at the same time improve the stable low temperature toughness even after AW and long-time PWHT. By optimizing the amounts of B and B, it is possible to improve the low-temperature toughness and increase the strength of the weld metal after PWHT for a long time while ensuring the necessary strength and low-temperature toughness of the AW weld metal. I found out. We also found that by optimizing C, Cu, Ni, Ti, and B in the wire, the weld cracking resistance was improved, the arc during welding was stabilized, and the amount of spatter was reduced, improving welding workability. .
In the present invention, the component composition of the solid wire for gas shielded arc welding was determined based on these findings.

  The solid wire for gas shielded arc welding of the present invention achieves the intended effect of the present invention due to the synergistic effect of each component composition alone and coexistence. Give reasons and reasons for limitation. In the following description, the chemical component of the solid wire is expressed by mass%, which is a ratio with respect to the total mass of the wire, and description relating to the mass% is simply described as%.

[C: 0.01 to 0.08%]
C is an element necessary for improving the strength of the weld metal after AW and PWHT by solid solution strengthening. When C is less than 0.01%, the strength of the weld metal after AW and PWHT cannot be obtained. On the other hand, when C exceeds 0.08%, C is excessively yielded in the weld metal, the strength of the weld metal after AW and PWHT becomes excessively high, and the low temperature toughness is lowered. Moreover, the weld crack sensitivity is increased. Therefore, C is set to 0.01 to 0.08%.

[Si: 0.2 to 0.6%]
Si is added for deoxidation of the weld metal. When Si is less than 0.2%, the weld metal becomes insufficiently deoxidized, and the low temperature toughness after AW and PWHT decreases. On the other hand, if Si exceeds 0.6%, the low temperature toughness of AW and PWHT cannot be obtained stably. Therefore, Si is 0.2 to 0.6%.

[Mn: 0.5 to 1.5%]
Mn is added to secure low temperature toughness and improve strength of the weld metal after AW and PWHT. When Mn is less than 0.5%, the strength of the weld metal after AW and PWHT is low, and the low temperature toughness cannot be sufficiently ensured. On the other hand, if Mn exceeds 1.5%, low temperature toughness after AW and PWHT cannot be obtained stably. Therefore, Mn is 0.5 to 1.5%.

[Cu: 0.15 to 0.40%]
Cu has precipitation strengthening action, lowers the transformation temperature and refines the structure of the weld metal, especially improves the low temperature toughness after PWHT, and coats the wire surface as copper plating, wire feedability and energization It has the effect of stabilizing the arc and stabilizing the arc. If the Cu content is less than 0.15%, the structure of the weld metal is not refined, and the low temperature toughness of the weld metal after PWHT cannot be obtained stably. In addition, the required wire feedability and electrical conductivity cannot be obtained, the arc becomes unstable, and the amount of spatter generated increases. On the other hand, when Cu exceeds 0.40%, the weld cracking sensitivity becomes high. Therefore, Cu is 0.15 to 0.40%. In addition, it is preferable that the copper plating thickness of the wire surface is 0.2-1.0 micrometer from a viewpoint of chip wear resistance.

[Ni: 3.0-4.0%]
Ni lowers the transformation temperature and refines the structure of the weld metal, improves the low temperature toughness after AW and PWHT, and has the effect of increasing the strength without dissolving in the weld metal and reducing the low temperature toughness. . When Ni is less than 3.0%, the effect of preventing the decrease in low temperature toughness cannot be sufficiently obtained, and the low temperature toughness of the weld metal after AW and PWHT cannot be stably obtained. On the other hand, if Ni exceeds 4.0%, the weld cracking sensitivity becomes high, the grain boundary becomes brittle, and the low temperature toughness after AW and PWHT decreases. Therefore, Ni is set to 3.0 to 4.0%.

[Mo: 0.10 to 0.40%]
Mo has the effect of reducing the transformation temperature to refine the microstructure of the weld metal, and in particular, improving the low temperature toughness while preventing a decrease in strength after PWHT. If Mo is less than 0.10%, these effects cannot be sufficiently obtained, and the strength and low-temperature toughness of the weld metal after PWHT are lowered. On the other hand, if Mo exceeds 0.40%, the strength of the weld metal after AW and PWHT becomes excessively high, and low-temperature toughness cannot be stably obtained. Therefore, Mo is set to 0.10 to 0.40%.

[Ti: 0.020 to 0.100%]
Ti is a deoxidizer, and is an important element that lowers the oxygen in the weld metal, fixes nitrogen in the weld metal mixed during welding, and improves low-temperature toughness after AW and PWHT. In addition, there is an effect of reducing the amount of spatter generated by stabilizing the arc. When Ti is less than 0.020%, the arc becomes unstable and the amount of spatter generated increases. Further, the low temperature toughness of the weld metal after AW and PWHT cannot be obtained stably. On the other hand, when Ti exceeds 0.100%, precipitation of TiC and solid solution strengthening are caused, the strength of the weld metal after AW and PWHT becomes excessively high, and the low temperature toughness is lowered. Therefore, Ti is set to 0.020 to 0.100%.

[B: 0.0010 to 0.0100%]
B coexists with Ti and becomes a nucleus of ash-like ferrite, and has an effect of improving low temperature toughness especially after PWHT. If B is less than 0.0010%, this effect cannot be obtained, and the low temperature toughness after PWHT decreases. On the other hand, when B exceeds 0.0100%, the weld cracking sensitivity becomes high and the low temperature toughness after AW and PWHT decreases. Therefore, B is 0.0010 to 0.0100%.

  The balance of the solid for gas shielded arc welding of the present invention is unavoidable impurities such as Fe and P, S, N, O, which are main components. P and S are each preferably 0.01% or less because they lower the low temperature toughness of the weld metal after AW and PWHT and increase the weld crack sensitivity.

N is required to reduce the solid solution N in order to stabilize the low temperature toughness of the weld metal after AW and PWHT, and is preferably 0.005% or less.
O becomes an oxide (non-metallic inclusion) such as Si or Mn in the weld metal and lowers the low-temperature toughness after AW and PWHT, so 0.007% or less is preferable.

The shield gas is a mixed gas of Ar and CO 2 , but the mixed amount of CO 2 is preferably in the range of 5 to 25% by volume in order to reduce the amount of oxygen in the weld metal. In addition, the flow rate of the shielding gas is preferably 20 to 35 liters / minute in order to prevent defect resistance and nitrogen contamination from the atmosphere.

  Hereinafter, the effect of the present invention will be described in detail with reference to examples.

  The raw steel was vacuum melted, forged, rolled, drawn, annealed, copper-plated on the wire surface, and then finished drawn to a product diameter of 1.2 mm to obtain a 20 kg spool. Table 1 shows the chemical composition of the prototype solid wire.

  We investigated welding workability and weld metal performance using the prototype solid wire.

  For welding workability and weld metal performance, a weld metal test was carried out under the welding conditions shown in Table 2 in accordance with JIS Z3111 using a steel plate having a thickness of 20 mm specified in JIS G3127 SL3N440.

  The survey items for welding workability were the arc stability during the weld metal test, the occurrence of spatter, and the presence of hot cracks. In addition, the wire supply at the time of welding used the conduit cable of 6 m length.

  In the weld metal test, the weld metal after AW and the weld metal after PWHT according to the post-weld heat treatment conditions shown in Table 3 were evaluated. The performance was investigated.

  In the evaluation of the tensile test of the weld metal, the tensile strength of the weld metal after AW and PWHT was 600 to 700 MPa. The impact test was evaluated by conducting a Charpy impact test at −60 ° C., and the average value of the absorbed energy of the deposited metal after AW and PWHT was 80 J or more, and the minimum value was 60 J or more. These results are summarized in Table 4.

In Table 1 and Table 4, wire symbols W1 , W3 to W5 are examples of the present invention, and wire symbols W6 to W19 are comparative examples. In the wire symbols W1 , W3 to W5 , which are examples of the present invention , the amount of C, Si, Mn, Cu, Ni, Mo, Ti, and B in the wire is appropriate, so that the wire feedability is good and the arc is stable and spattered. The amount of generation was small, and the average and minimum values of the tensile strength and absorbed energy of the deposited metal after AW and PWHT were good, and the results were extremely satisfactory.

  Since the wire symbol W6 in the comparative example has a small amount of C, the tensile strength of the weld metal after AW and PWHT was low. Further, since Cu is small, the minimum value of the absorbed energy of the deposited metal after PWHT is low, the arc is unstable, and the amount of spatter generated is large.

  Since the wire symbol W7 has a lot of C, the tensile strength of the deposited metal after AW and PWHT was high, and the average value and the minimum value of the absorbed energy were low. Moreover, the crater part cracked.

  Since the wire symbol W8 has a small amount of Si, the average value of the absorbed energy of the deposited metal after AW and PWHT was low. Moreover, since there was much Cu, the crater part cracked.

  Since the wire symbol W9 has a large amount of Si, the minimum value of the absorbed energy of the weld metal after AW and PWHT was low.

  Since the wire symbol W10 had a small amount of Mn, the tensile strength of the weld metal after AW and PWHT was low, and the average value of the absorbed energy was low.

  Since the wire symbol W11 has much Mn, the minimum value of the absorbed energy of the weld metal after AW and PWHT was low.

  Since the wire symbol W12 has a small amount of Ni, the minimum value of the absorbed energy of the weld metal after AW and PWHT was low.

  Since the wire symbol W13 contains a large amount of Ni, the average value of the absorbed energy of the deposited metal after AW and PWHT was low. Moreover, the crater part cracked.

  Since the wire symbol W14 has a small amount of Mo, the tensile strength of the weld metal after PWHT was low, and the average value and the minimum value of the absorbed energy were low.

  Since the wire symbol W15 has a lot of Mo, the tensile strength of the weld metal after AW and PWHT was high, and the minimum value of absorbed energy was low.

  Since the wire symbol W16 has a small amount of Ti, the arc is unstable and the amount of spatter generated is large, and the minimum value of the absorbed energy of the deposited metal after AW and PWHT is low.

  Since the wire symbol W17 has a large amount of Ti, the tensile strength of the deposited metal after AW and PWHT was high, and the average value and the minimum value of the absorbed energy were low.

  Since the wire symbol W18 has a small amount of B, the average value and the minimum value of the absorbed energy of the weld metal after PWHT were low.

  Since the wire symbol W19 has a large amount of B, the average value and the minimum value of the absorbed energy after AW and PWHT were low. Moreover, the crater part cracked.

Claims (1)

  1. In mass% of the total mass of the wire
    C: 0.01 to 0.08%,
    Si: 0.2-0.6%
    Mn: 0.5 to 1.5%
    Cu: 0.15-0.40%,
    Ni: 3.0-4.0%,
    Mo: 0.10 to 0.40%,
    Ti: 0.020 to 0.100%,
    B: A solid wire for gas shielded arc welding containing 0.0010 to 0.0100%, the balance being Fe and inevitable impurities.
JP2015002376A 2015-01-08 2015-01-08 Solid wire for gas shielded arc welding Active JP6386918B2 (en)

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Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5653472B2 (en) * 1974-11-27 1981-12-18
JPS5440250A (en) * 1977-09-05 1979-03-29 Nippon Steel Corp Wire for gas shielded arc welding of high efficiency
JPS5666383A (en) * 1979-11-06 1981-06-04 Nippon Steel Corp Gas shielded arc welding method
JPH0249832B2 (en) * 1981-06-05 1990-10-31 Nippon Steel Corp
JPS63157795A (en) * 1986-12-19 1988-06-30 Nippon Steel Corp Wire for high tensile steel
JPH07195193A (en) * 1993-12-29 1995-08-01 Kobe Steel Ltd Solid wire for thin sheet of high tension steel
US5744782A (en) * 1996-03-07 1998-04-28 Concurrent Technologies Corporation Advanced consumable electrodes for gas metal arc (GMA) welding of high strength low alloy (HSLA) steels
JP2000225465A (en) * 1999-02-02 2000-08-15 Nippon Steel Weld Prod & Eng Co Ltd Gas shield pulse arc welding method
JP4469226B2 (en) * 2004-06-15 2010-05-26 新日本製鐵株式会社 Solid wire for gas shielded arc welding for underlay welding.
JP4441372B2 (en) * 2004-10-13 2010-03-31 新日本製鐵株式会社 High strength and high toughness gas shielded arc welding wire

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