JP4387238B2 - Flux-cored wire for gas shielded arc welding - Google Patents

Description

  The present invention relates to a flux-cored wire for gas shielded arc welding that can obtain excellent welding workability with high efficiency without deteriorating impact performance and bead shape in vertical improvement welding and upward posture welding.

  In the shipbuilding and bridge fields, there are many places where butt joint welding is performed, and high efficiency welding is required. However, with conventional flux-cored wire for gas shielded arc welding, if the welding current is increased in order to increase the welding efficiency in the vertical improvement welding or the upward posture welding, the molten metal droops and the bead is dropped. Since the shape and appearance deteriorated, the welding current was lowered to perform welding. Further, when the first layer of the butt joint is welded, there is a concern that cracking may occur, so that the welding current cannot be increased, and the welding efficiency is lowered. Further, even when a flux-cored wire for gas shielded arc welding with good welding workability is used by increasing the welding current, the welding is performed at a low welding current because the mechanical performance deteriorates.

  On the other hand, as a flux-cored wire for gas shielded arc welding that emphasizes the vertical improvement welding, for example, Japanese Patent Laid-Open No. 9-262663 (Patent Document 1) can perform highly efficient welding and -40 There is a proposal of a flux-cored wire for gas shielded arc welding with good toughness up to about ℃. However, since Al per total mass of the wire is low, the sag resistance of the molten metal and slag is not sufficient, and the bead shape and appearance are not satisfactory. Japanese Patent Laid-Open No. 2004-34078 (Patent Document 2) proposes a wire with improved slag peelability and impact performance of a weld metal. However, even in this technology, since the Al per the total mass of the wire is low, when the welding current is increased and the vertical improvement welding is performed, the weld metal and the slag hang down and the bead shape and appearance are not sufficient.

JP-A-9-262893 JP 2004-34078 A

  The present invention provides a flux-cored wire for gas shielded arc welding capable of obtaining high efficiency and excellent welding workability without deteriorating impact performance and bead shape in vertical improvement welding and upward posture welding. With the goal.

The gist of the present invention is that, in a flux-cored wire for gas shielded arc welding, in which a steel sheath is filled with a flux, the mass is based on the total mass of the wire, the Ti oxide is 4 to 8% in terms of TiO ₂ , SiO 2 ₂ is 0.8 to 1.5%, ZrO ₂ is 0.4% or less, K ₂ O is 0.1 to 0.4%, fluoride is 0.05 to 0.25% in terms of F, Al ₂ O ₃ 0.5% or less, Al 0.2-0.9%, Si 0.3-0.9%, Mn 1.3-2.5%, balance the ratio Mn / Si is 2.3 to 5.0 is characterized that you consisting of Fe and unavoidable impurities. Moreover, it is also characterized by containing 0.2 to 1.5% of Ni and / or 0.001 to 0.010% of B.

  According to the flux-cored wire for gas shielded arc welding of the present invention, it is possible to obtain high efficiency and excellent welding workability without deteriorating impact performance and bead shape in vertical improvement and upward posture welding.

The present inventors have made various types of flux-cored wires for gas shielded arc welding and applied them to vertical welding and upward welding, and investigated the effects of molten metal and molten slag on dripping, bead shape and appearance. Furthermore, the impact performance of the weld metal and the presence or absence of cracks were also investigated. As a result, an appropriate amount of TiO ₂ , SiO ₂ , ZrO ₂ , K ₂ O, Al ₂ O ₃ , F and Al, Si, Mn added in the form of metal and alloy are added to the wire, and the Mn / Si value By making the material suitable, there is no dripping of the molten metal and molten slag during the vertical improvement welding and the upward posture welding, the bead shape is improved, and the addition of appropriate amounts of Ni and B does not cause cracks. It has been found that excellent impact performance can be obtained.

Below, the component composition of the flux-cored wire for gas shielded arc welding of this invention and the reason for limitation of the content are demonstrated. In addition, content of each component composition described below is shown by the mass% with respect to the wire total mass.
TiO ₂ is the main component of the slag forming agent and is added from Ti oxide rutile, titanium oxide, sodium titanate, titanium slag, illuminite, and the like. TiO ₂ plays the role of uniformly covering the entire bead and adjusting the bead shape. In addition, the arc is sustained and stabilized, and the amount of spatter generated is reduced. When the Ti oxide is less than 4% in terms of TiO ₂ , the arc becomes unstable and the slag generation amount is insufficient, and the force to hold down the molten metal becomes weak. Cannot be trimmed into a beautiful flat shape. If it exceeds 8%, the amount of molten slag increases and the molten slag hangs before cooling and solidifying, making it impossible to arrange the bead into a beautiful shape.

SiO ₂ is added from silica sand, zircon sand, feldspar, etc., and acts as a slag forming agent, and has the effect of increasing the viscosity of the molten slag with a small amount. When the SiO ₂ content is less than 0.8%, the effect as a slag forming agent is reduced, the slag encapsulation is deteriorated, and as a result, the bead shape becomes convex. Further, since the solidification temperature of SiO ₂ is low, if it exceeds 1.5%, the solidification temperature of the molten slag is lowered and it becomes impossible to sag before the slag solidifies to make the bead into a beautiful shape.

ZrO ₂ is added from zircon sand, zirconium oxide, and the like, and acts as a slag forming agent that improves the slag encapsulating property and improves the bead shape with a small amount. By adding ZrO ₂ , the solidification temperature of the molten slag is increased and the solidification of the slag is accelerated, so that a small amount is effective for dripping the molten slag. If ZrO ₂ exceeds 0.4%, the arc becomes unstable and the amount of spatter generated increases.

K ₂ O is added as an oxide or fluoride, and acts as an arc stabilizer. If it is less than 0.1%, the effect is small and the arc cannot be stabilized. If it exceeds 0.4%, the viscosity of the slag will decrease, the molten slag will sag and the bead shape will deteriorate.
F is added from alkali metal fluorides, metal fluorides, and the like, and moderates the arc length so as to suppress the arc from being buried in the base material, thereby relaxing the digging into the base material. If the F converted value of fluoride is less than 0.05%, the effect is small and the arc length cannot be adjusted. If it exceeds 0.25%, the fluidity of the molten slag becomes excessive, the bead shape deteriorates, and the amount of spatter and fume generation increases.

Al ₂ O ₃ is added as alumina, cryolite, feldspar, etc., and raises the freezing point of slag to prevent dripping of molten slag. However, if Al ₂ O ₃ exceeds 0.5%, the arc becomes rough and the bead shape deteriorates.
Al is added from metal Al, Al alloy, etc., and has the effect of speeding solidification of the molten slag, and therefore has an effect of preventing dripping of the molten slag. If Al is less than 0.2%, the freezing point of the molten slag is low, and the molten slag droops and the bead shape deteriorates. If it exceeds 0.9%, dripping of the molten slag is prevented, but the slag peeling becomes worse and the bead appearance is deteriorated. In addition, Al is dissolved in the weld metal and the impact performance is deteriorated.

Si is added from metallic silicon, ferrosilicon, silicon manganese, etc., and ensures the mechanical properties of the weld metal. If Si is less than 0.3%, deoxidation is insufficient and impact performance deteriorates. If it exceeds 0.9%, the impact performance deteriorates.
Mn is added from metallic manganese, ferromanganese, etc., and ensures the mechanical properties of the weld metal as with Si. If Mn is less than 1.3%, deoxidation is insufficient and impact performance deteriorates. If it exceeds 2.5%, the impact performance deteriorates.

  Mn / Si affects the viscosity of the weld metal. When Mn / Si increases, the viscosity of the molten metal decreases. Conversely, when Mn / Si decreases, the viscosity of the molten metal increases. If Mn / Si is less than 2.5, the amount of spatter generated increases and welding workability deteriorates. If it exceeds 5.0, the viscosity of the molten metal becomes low and the bead shape becomes convex.

  Furthermore, in order to improve the impact performance of the weld metal, Ni is contained in an amount of 0.2 to 1.5%, B is contained in an amount of 0.001 to 0.010%, and Ni and B are within the specified ranges. It is possible to improve the impact performance by adding both of them. However, if Ni is less than 0.2% and B is less than 0.001%, the impact performance is not improved. If Ni exceeds 1.5%, the strength increases and the impact performance deteriorates. Moreover, when B exceeds 0.010%, a hot crack may arise.

  The slag forming agent affects arc stability, slag encapsulation, and the like. In particular, in the vertical improvement and upward posture welding, it is necessary to cover the molten metal so as to adjust the bead shape into a beautiful flat shape. Therefore, the total of the slag forming agent components is preferably 5.5 to 10%. Furthermore, in order to improve the crack resistance at high current, it is desirable that C added in the form of metal and alloy is 0.03 to 0.08%. Moreover, it is preferable to make low melting point components, such as P, S, and Bi, as low as possible from a viewpoint of hot cracking resistance.

Hereinafter, the effect of the present invention will be described in more detail with reference to examples.
Example 1
First, JIS G3141 SPCC band steel was used for the steel outer sheath, and a flux-cored wire for gas shield arc welding with various components shown in Table 1 and having a diameter of 1.2 mm was prepared by filling with about 16% flux.

  Using these prototype wires, an inorganic zinc primer coated steel sheet (JIS G3106 SM490A, primer film thickness 15-20 μm) with a thickness of 12 mm was used as a T-shaped fillet specimen (length 500 mm), and the welding conditions shown in Table 2 We performed vertical improvement and welding in an upward posture, and investigated arc stability, dripping of molten slag, dripping of molten metal, bead shape and appearance. Further, with a butt joint of a steel plate having a thickness of 20 mm (JIS G3106 SM490A), as shown in FIG. 1, five-pass welding was performed in a vertical improvement posture, and the impact performance of the weld metal was investigated. In FIG. 1, 1 is a steel plate, 2 is a solid backing material, 3 is an impact test piece, and the impact test piece 3 is taken from the center of the plate thickness. The impact performance was evaluated as acceptable when the impact value at 0 ° C. was 27 J or more. These survey results are summarized in Table 3.

In Table 1 and Table 3, No. 1-9 are examples of the present invention, No. 10-23 are comparative examples. No. which is an example of the present invention. Nos. 1 to 9 are suitable for the TiO ₂ , SiO ₂ , ZrO ₂ , K ₂ O, F conversion value, Al ₂ O ₃ , Al, Si, Mn amount and Mn / Si values of the wire, so that the arc is stable In addition, the amount of spatter was small, there was no dripping of molten slag and no dripping of molten metal, the bead shape / appearance and impact performance were good, and the results were very satisfactory.

No. in the comparative examples. In No. 10, since the amount of TiO ₂ was small, the arc was not stable and the slag was insufficient in the force to hold the molten metal, so that the molten metal dripped and the bead shape became poor.
No. No. 11 has a large amount of TiO ₂ , so that the molten slag dripped and the bead shape became poor. Moreover, since there was little Mn, the impact performance was also unsatisfactory.
No. No. 12 had less SiO ₂ , so the slag foreskin was poor and the bead shape was poor. Moreover, since there was much Mn, the impact performance was also unsatisfactory.

No. No. 13 has a large amount of SiO ₂ , so that the solidification temperature of the slag was lowered and the slag was dropped, resulting in a poor bead shape. Moreover, since there was little Si, the impact performance was also unsatisfactory.
No. No. 14 had a large amount of ZrO ₂ , so the arc was unstable and the amount of spatter generated increased. Moreover, since there was much Si, the impact performance was also unsatisfactory.
No. No. 15 had less K ₂ O, so the arc became unstable.
No. No. 16 had a large amount of K ₂ O, so the viscosity of the slag was lowered and the slag was dropped, resulting in a poor bead shape.

No. No. 17 had a small F-converted value, so the arc length was shortened, the arc was not stable, and the bead shape was poor.
No. Since No. 18 had many F conversion values, the fluidity of slag became excessive and the bead shape deteriorated. In addition, the amount of spatter and fumes generated increased.
No. No. 19 had a large amount of Al ₂ O ₃ , so the arc became rough and the bead shape was poor.

No. In No. 20, since the amount of Al was small, the melting point of the slag was low and the slag dripped, resulting in a poor bead shape.
No. No. 21 had a large amount of Al, so the slag peelability was poor and the bead appearance was poor. The impact performance was also poor.
No. No. 22 had a large Mn / Si, resulting in a poor bead shape.
No. In No. 23, since the Mn / Si was small, the amount of spatter generated increased.

(Example 2)
A 1.2 mm diameter flux-cored wire having the components shown in Table 4 was prototyped and the same test as in Example 1 was performed. In the butt joint welding, the presence or absence of cracks in the first layer was investigated. The impact performance was evaluated as acceptable when the impact value at 0 ° C. was 47 J or more. The results are summarized in Table 5.

In Table 4 and Table 5, No. Nos. 24-28 are examples of the present invention. 29 to 32 are comparative examples. No. which is an example of the present invention. 24 to 28, the wires of _{TiO 2, SiO 2, ZrO 2} , K 2 O, F converted _{value, Al 2 O 3, Al,} Si, the value of the amount of Mn and Mn / Si is proper, the arc is stable In addition, the amount of spatter generation is small, there is no slag dripping or molten metal dripping, the bead shape / appearance is good, and the Ni and B amounts are appropriate, so the impact performance is good, and there are no hot cracks. Met.

No. in the comparative examples. No. 29 has less Ni, so no. Since 31 had less B, impact performance was poor in all cases.
No. No. 30 had a large amount of Ni, so the strength was high and the impact performance was poor.
No. Since No. 31 had a lot of B and hot cracking occurred, the investigation of impact performance was stopped.

It is a figure which shows the butt joint welding of the Example of this invention.

Explanation of symbols

1 Steel plate 2 Solid backing material 3 Impact test piece


Patent Applicant Nippon Steel & Sumikin Welding Co., Ltd.
Attorney Attorney Shiina and others 1

Claims (3)

In a flux-cored wire for gas shielded arc welding formed by filling a steel sheath with flux, the Ti oxide is 4 to 8% in terms of TiO ₂ and the SiO ₂ is 0.8 to 0.8% in terms of the total mass of the wire. 1.5%, ZrO ₂ 0.4% or less, K ₂ O 0.1-0.4%, fluoride F-converted value 0.05-0.25%, Al ₂ O ₃ 0.1%. 5% or less, Al: 0.2-0.9%, Si: 0.3-0.9%, Mn: 1.3-2.5%, the ratio of Si to Mn: Mn / Si is 2 gas shielded arc welding flux cored wire and the balance in that it consists of F e and unavoidable impurities .3～5.0. The flux-cored wire for gas shielded arc welding according to claim 1, wherein Ni is contained in an amount of 0.2 to 1.5%. The flux-cored wire for gas shielded arc welding according to claim 1 or 2, wherein B is contained in an amount of 0.001 to 0.010%.

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