JP3027312B2 - Flux for submerged arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten flux for submerged arc welding suitable for inclined welding.

[0002]

2. Description of the Related Art In tilt welding in which a material to be welded is inclined with respect to a horizontal plane, unsolidified molten metal is affected by weight. In other words, in the downward welding, since the molten metal is pushed forward in the welding direction, the cross-sectional shape is a concave shape with a concave central portion, and conversely, in the upward welding, the molten metal is pushed back in the welding direction,
A convex bead is formed. Further, when the welding speed is increased, undercut and overlap easily occur.

[0003] Therefore, in order to improve these problems, flux components and physical properties have been conventionally adjusted to suppress the fluidity of slag. That is, it has been considered that increasing the viscosity of the molten slag to suppress the flow of the slag is good for improving the problem in the inclined welding.

To increase the viscosity of slag, Japanese Patent Application Laid-Open
In the technique proposed in Japanese Patent No. 75143, it is proposed to change TiO ₂ of a flux component which is usually used to ZrO ₂ . Also, Japanese Patent Application Laid-Open No. 62-1798
The technique disclosed in No. 94 pays attention to the melting temperature of the flux, and proposes a component system in which the melting temperature is 1180 to 1350 ° C.

[0005]

However, in these prior arts, the welding speed is 250 to 350 c.
It is about m / min, and in view of improving the efficiency, welding at a higher speed is demanded. However, using these conventional fluxes, for example, 400 cm / min
When the angle welding is performed at a high welding speed, a defective bead shape and undercut and overlap occur.

[0006] Therefore, there is a demand for the development of a flux of a new component system which has good welding workability even at high speed.

[0007] The present invention has been made in view of the above problems, and a submerged arc having good bead shape and slag releasability without generating undercut and overlap even in high-speed welding during inclined welding. An object of the present invention is to provide a molten flux for welding.

[0008]

The molten flux for submerged arc welding according to the present invention is SiO ₂ ;
0% by weight, TiO ₂ ; 10 to 30% by weight, Al ₂ O ₃ ;
0 to 25% by weight, MgO; 5 to 20% by weight, CaF ₂ ;
5 to 20% by weight, MnO; 2 to 15% by weight, CaO;
% By weight, Na ₂ O and / or K ₂ O; 0.05 in total
5 wt%, TiO ₂ / CaO ratio; 5-30, the balance characterized by comprising the trace elements and unavoidable impurities.

[0009]

The present inventors have repeatedly conducted various experimental studies in order to develop a highly viscous flux capable of achieving the above object, and as a result, have found the following. That is, the conventional S
In a component system mainly composed of iO ₂ —TiO ₂ —Al ₂ O ₃ , it is said that lowering CaO lowers the viscosity.
Conversely, in the present invention, it has been found that when CaO is lowered and the ratio of the combination with TiO ₂ is set in an appropriate range, the viscosity of the flux increases, and good workability of the bead shape can be obtained even in high-speed welding. The present invention has been completed based on such findings.

Next, the reasons for adding the components of the flux according to the present invention and the reasons for limiting the composition will be described.

SiO ₂ : 20 to 40% by weight SiO ₂ is an acidic component and is an effective component for adjusting the melting point and viscosity of slag. The content of SiO ₂ is 2
When the content is less than 0% by weight, the viscosity of the molten slag is insufficient, which causes the bead to meander and undercut. On the other hand, when the content of SiO ₂ exceeds 40% by weight, the slag removability deteriorates.

CaF ₂ : 5 to 20% by weight CaF ₂ is a basic component, and is also a component effective in adjusting the melting point and fluidity of slag. When the content of CaF ₂ is less than 5% by weight, the above effect is not effectively exerted, and the beads meander. On the other hand, when the content of CaF ₂ is 20
If the content is more than 10% by weight, slag entrainment becomes remarkable, slag releasability is deteriorated, and pock marks are easily generated.

MnO: 2 to 15% by weight MnO is an effective component for adjusting the melting point and viscosity of slag. If the content of MnO is less than 2% by weight, slag
Interfacial tension between the metals becomes excessive, and slag is easily seized or undercut is liable to occur. On the other hand, M
If the content of nO exceeds 15% by weight, the bead tends to meander.

MgO: 5 to 20% by weight MgO is a basic component and acts as a viscosity modifier. If the content of MgO is less than 5% by weight, the beads are likely to meander due to insufficient viscosity. On the other hand, MgO
If the content exceeds 0% by weight, the moisture absorption resistance is deteriorated, and a pock mark is easily generated, and the slag peeling property is also deteriorated.

TiO ₂ : 10 to 30% by weight TiO ₂ is an acidic component and is an effective component for adjusting the melting point and viscosity of slag. TiO ₂ content is 1
If the content is less than 0% by weight, the bead tends to meander. On the other hand, when TiO ₂ exceeds 30% by weight, the slag removability is rapidly deteriorated.

Al ₂ O ₃ : 10 to 25% by weight Al ₂ O ₃ is a nearly neutral component (weakly acidic) and adjusts the melting point and viscosity of the slag while minimizing the decrease in the basicity of the flux. It is an effective ingredient. If the content of Al ₂ O ₃ is less than 10%, the resulting slag becomes insufficient in viscosity, which tends to cause undercut,
The slag removability also deteriorates. On the other hand, if the content exceeds 25%, the viscosity of the slag becomes too high, and slag entrainment appears.

CaO: ≦ 4% by weight CaO is a basic component, and is an effective component for adjusting the basicity, viscosity and melting point of slag. Conventional SiO ₂
-TiO ₂ -Al ₂ O ₃ in the main component system is Ca
It has been said that increasing the O content increases the viscosity,
In the flux component system according to the present invention, by restricting the addition of CaO and defining the range of the combination with TiO ₂ , the viscosity increases and welding workability at high speed is improved. Considering the bead shape improvement, Ca
The more preferred range of O is preferably limited to 3% or less.
However, the lower limit of CaO is limited by the ratio of TiO ₂ / CaO described later.

Na ₂ O and / or K ₂ O: 0.05 to 5
Wt% Na ₂ O and K ₂ O is effective as a viscosity modifier of the arc stabilizer and the slag. Since both Na ₂ O and K ₂ O have the same action and effect, either Na ₂ O or K ₂ O may be added alone or in combination of both.

If the total content of these components is less than 0.05% by weight, the arc stability becomes poor, and the unevenness and meandering of the bead become remarkable. However, when the total content of these components exceeds 5% by weight, the moisture absorption resistance is deteriorated, and pits and pock marks are generated.

TiO ₂ / CaO ratio: 5 to 30 It is an essential condition that TiO ₂ and CaO are contained in the above specified ranges, respectively. Further, the ratio of TiO ₂ to CaO is specified in the range of 5 to 30. As a result, good workability can be obtained in high-speed inclined welding.

That is, when the ratio is less than 5, the viscosity of the slag is insufficient, the bead shape is deteriorated, and undercut or overlap is liable to occur. On the other hand, if the ratio exceeds 30, the slag removability deteriorates.

[0022]

Next, examples of the present invention will be described in comparison with comparative examples. A submerged arc welding test was performed using a molten flux having the composition shown in Table 1 below. The welding conditions are as follows. (1) Steel plate: JIS SS400 Plate thickness: 12 mm (2) Groove shape: As shown in FIG.
Distance from the front surface to the groove bottom 3 mm, distance from the groove bottom to the back surface 9 mm (3) Wire: JIS YS-S1 Leading electrode diameter: 4.8 mm Trailing electrode diameter: 4.0 mm (4) Leading electrode polarity: DC-RP (DC-reverse polarity) Trailing electrode polarity: AC (5) Electrode angle: As shown in FIG.
°, the leading electrode is perpendicular to the steel plate, the trailing electrode is inclined backward by 5 ° with respect to the steel plate, and the distance between the electrodes is 20 mm. (6) Current / voltage / speed Leading electrode: 1800A / 32V / 400cm / min Trailing electrode: 900A・ 38V ・ 400cm / min

[0023]

[Table 1]

However, the column of the formula * 1 in Table 1 is TiO ₂
/ CaO ratio. The other columns are BaO, B ₂ O ₃ ,
Minor components and impurities such as ZrO ₂ and Li ₂ O. Further, in the welding workability, ○ is good and X is bad.

As is apparent from Table 1, in Examples 1 to 18 of the present invention, good welding results were obtained.
On the other hand, Comparative Examples 19 to 35 out of the range of the present invention have poor welding workability. That is, in Comparative Examples 19 and 20, SiO 2
₂ was out of the appropriate range, so that the bead meandered in Comparative Example 19, and the slag peelability was poor in Comparative Example 20.
For Comparative Example 2l, 22 the TiO ₂ is out of the proper range, the bead in Comparative Example 21 meanders, in Comparative Example 22, the slag removability were deteriorated. In Comparative Examples 23 and 24, since Al ₂ O ₃ was out of the appropriate range, undercut occurred in Comparative Example 23 and slag entrainment occurred in Comparative Example 24. In Comparative Examples 25 and 26, MgO was out of the proper range, so that the bead meandered in Comparative Example 25, and a pock mark occurred in Comparative Example 26. In Comparative Examples 27 and 28, since CaF ₂ is out of the appropriate range,
In Comparative Example 27, the bead meandered, and in Comparative Example 28, a pock mark occurred. In Comparative Examples 29 and 30, MnO was out of the proper range, so a pock mark was generated in Comparative Example 29, and the bead meandered in Comparative Example 30. Further, in Comparative Example 31, since CaO was out of the proper range, undercut occurred. In Comparative Examples 32 and 33, Na
_{Since 2} O and K ₂ O were out of the proper range, the bead meandered in Comparative Example 32, and a pock mark occurred in Comparative Example 33. In Comparative Examples 34 and 35, the ratio of TiO ₂ / CaO was out of the appropriate range, so that the undercut occurred in Comparative Example 34, and the slag removability was poor in Comparative Example 35.

[Brief description of the drawings]

FIG. 1 is a diagram showing a groove shape.

FIG. 2 is a diagram showing electrode angles.

Claims (1)

(57) [Claims] 1. SiO ₂ ; 20 to 40% by weight, TiO ₂ ;
10 to 30% by weight, Al ₂ O ₃ ; 10 to 25% by weight, Mg
O: 5 to 20% by weight, CaF ₂ : 5 to 20% by weight, Mn
O: 2 to 15% by weight, CaO: 4% by weight or less, Na ₂ O
And / or K ₂ O; 0.05 to 5% by weight in total, TiO ₂
/ CaO ratio; 5 to 30, balance: a molten flux for submerged arc welding, comprising a trace element and unavoidable impurities.