JPS5852476B2 - Melt flux for horizontal submerged arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a melt flux for horizontal submerged arc welding.

The horizontal submerged arc welding method is applied to a wide range of steels, including mild steel to T-60 steel and low-temperature steel. Performance is required.

In other words, unlike general downward welding, horizontal submerged arc welding has a small welding heat input, so the weld metal and molten slag solidify quickly on the bead surface, which tends to cause flutter and pock marks, and a narrow bevel angle. is adopted, so the slag removability becomes poor.

Also, the solidification direction inside the weld metal is downward 1 on the upper side of the bead.
As a result, there is a problem in that slag entrainment and blowholes tend to remain in the bead.

That is, in lateral welding, which involves low heat input and creates a part where the solidification direction is downward, blowholes and slag entrainment are likely to occur, resulting in the bead surface being sluggish and having pockmarks.

Therefore, in order to obtain a good weld metal without the above defects even when performing latent arc welding using dwarf heat in such a special welding position, the inventors investigated the melt flux composition and found the following. It has been found that composition range 1 satisfies these requirements.

That is, in the present invention, the essential flux components are 5i0221~
30%, Mn05-15%, CaO3-15□, A12
0321-30%, CaF220-30%, and the above essential components S 102 + N1203 + CaF2-
68 to 83%, limits MgO to less than 2%, and has a bulk density of more than 1.49/i.

That is, in addition to CaF2 and Al2O3, SiO2, MnO
, by adding an appropriate amount of CaO and reducing as much as possible MgO, which deteriorates the fluidity of the slag1.Thus, welding workability is improved to suit the horizontal position of the dwarf heat, and as a result, the solidification of columnar crystals is Even in an unnatural welding position in which the welding progresses in the opposite direction, the molten slag easily floats up and scrapes, as well as the escape of CO, CO□ gas, etc., which causes pockmarks, abductions, etc. It made it easier to get out.

Furthermore, since the CaF2 content is high, the amount of oxygen and hydrogen in the weld metal part is also low, and the notch toughness is also good, and since MnO is added, the bead shape is also good.

The present invention will be described in detail below.

First, the reasons for the limitations on each component are as follows.

If S i02 is less than 21%, pock marks tend to occur and the amount of hydrogen in the weld metal increases, which is not preferable.

Since the melting point of flux exceeding 30% increases, good slag releasability cannot be obtained.

Therefore, if 8102 is less than 21 to 30%, pock marks occur and slag removability becomes poor, which is not preferable.

If CaO exceeds 15%, the melting point of the flux will rise, the fluidity of the slag will deteriorate, slag entrainment will occur, and the bead appearance will also deteriorate.

If MnO exceeds 15%, the melting point will drop too much and the appearance of the bead will deteriorate.

Therefore, each of MnO and CaO must be in the range of 5 to 15%.

Al2O3 is necessary to improve the fire resistance of high CaF2-based molten slag and the peelability of the slag, but at 21%
If it is less than that, the effect is not achieved and the bead tends to sag, which is not preferable.

If it exceeds 30%, the melting point will become too high, and the slag removability will deteriorate.
This is not preferable because the bead shape deteriorates.

Therefore, A4203 needs to be rubbed in the range 21-30%.

If CaF2 is less than 20%, the fluidity of the slag is poor and slag entrainment and blowholes are more likely to occur, and pock marks are more likely to occur on the bead surface, which is not preferable.

If it exceeds 30%, the fluidity of the slag will be good, but the melting point will drop too much and the arc will become unstable, making it impossible to obtain a good bead shape, so it must be below this range.

In addition, the essential components S i02 , Ae 203 and CaF
The reason why the total of the three factors in 2 was set in the range of 68 to 83% was based on the knowledge obtained from the following experiment 1).

That is, the essential components Ca010%, MnOL fixed at 1%, 5i0221~30%A120321~30%, Ca
SiO2+Al2O3 within the component range of F220-30%
Using flux with +CaF2 addition amount varying from 63 to 88%, the amount of diffusible hydrogen in the weld metal, pockmarks, slag peeling elegance, bead shape, arc stability t
I researched it carefully.

As for the experimental method, the diffusible hydrogen of the weld metal is determined according to JIS Z31.
．． The hydrogen content was measured in accordance with the method for measuring the amount of hydrogen in weld metal specified in 13-1951.1.

The chemical composition of the test plate and wire at that time is shown in Table 1, and the welding conditions are shown in Table 2.

In addition, regarding pockmarks, bead shape, slag removability, and arc stability, the groove shape shown in Figure 1 (dimension unit: m)
vt'), the welding conditions shown in Table 4 and the weld bead stacking method shown in FIG. 2 (the numbers in the figure indicate the order of stacking) were used.

The chemical composition of the test plate and wire at that time is shown in Table 3. The test plate was made of SP50Q steel with a thickness of 25 mm, width of 200 mm, and length of 7501 m as shown in Figure 1. A groove was prepared and horizontal submerged arc welding was performed.

As a result, the relationship between the amount of 5i02+A6203+CaF2 added and the amount of diffusible hydrogen, pockmarks, slag removability, bead shape, and arc stability is shown in FIG.

SiO2+Al2O3+CaF2 in flux is 68
If it is less than %, the amount of diffusible hydrogen in the weld metal increases, pock marks are likely to occur, and the bead appearance deteriorates, which is not preferable.

On the other hand, if it exceeds 83%, the slag removability deteriorates.

Furthermore, the arc becomes unstable and the bead shape deteriorates, so it is necessary to rub SiO2 + Al2O3 + CaF2 in a range of 68 to 83%.

In addition to the above-mentioned essential components, it is necessary to limit the MgO component to less than 2%.

MgO can be used up to less than 2% to improve the appearance of the bead, but if it exceeds 2%, the amount of hydrogen in the weld metal increases and pock marks are likely to occur, so it is necessary to keep it below 2%. It is.

Moreover, the bulk density needs to be more than 1.4 g/-.

If the bulk density is less than 1.4 g/-, the slag removability will be poor, the bead shape will tend to sag, and the amount of hydrogen and nitrogen in the weld metal will increase, which is undesirable. Therefore, the bulk density is 1.4 g. /-Super.

Note that the upper limit is not particularly high, but considering the flux component composition, etc., it will not be greater than about 1.8 g/i.

The bulk density in this case was measured by a loose packing method, specifically in accordance with JIS K67211966 "Method for measuring bulk specific gravity in vinyl chloride resin testing method".

In the flux of the present invention, the performance can be sufficiently satisfied with one of the above additive components, but one additional component T 102 is added for the purpose of adjusting toughness, fluidity, and melting point.

Ba0Zr02 and 20. Na2O, LiO2 (necessary) may be added accordingly, up to a total amount of 10% or less of one or more of them.

First, 1% TlO2 is effective in increasing notch toughness, but if it exceeds 3%, the slag removability deteriorates, so 3% TlO2 is effective.
The following are appropriate.

Bang says that Zr 02 can be used for the purpose of adjusting the fluidity and melting point of the slag, but if it exceeds 5%, pock marks and slag entrainment are likely to occur, and the bead appearance deteriorates, so it is preferably 5% or less.

Na2O, 20 or Li02 is preferable (to improve the bead appearance and stabilize the arc), but if it exceeds 5%, the reverse arc will blow up and the bead appearance will worsen, so it should not exceed 5%. It is desirable that

By using the flux 1 of the present invention having such a component composition, all of the various problems that have conventionally occurred in horizontal welding can be solved.

The present invention will be described below with reference to Example 1.

EXAMPLE In order to confirm the differences between the flux of the present invention and a comparative flux, horizontal submerged arc welding was performed to examine the slag releasability, the presence or absence of pock marks on the bead surface, the bead shape, and the slag inclusions and welding by X-rays. Comparative tests were conducted on the notch toughness and oxygen content of metals.

Table 5 shows the chemical composition of the sample flux.

F-L to F-7 are the fluxes of the present invention, and F8 is the comparative flux.

Note that F-8 is a commercially available flux of 12XI 50 mesh.

The fluxes of the present invention F-1 to F-7 are all made by mixing and melting various powdered or granular raw materials, and cooling the melted product in water with an F trowel, and each is sized to a 32 x D mesh. and set the bulk density of the flux to 1.4. g
It is manufactured to exceed lct&.

Using these fluxes, the groove shape shown in Fig. 1 (dimensional unit rnr/L), the welding conditions shown in Table 7, and the weld bead lamination method shown in Fig. 5 (the numbers in the figure indicate lamination 10) Lateral submerged arc welding was performed using

The chemical composition of the test plate and wire at that time is shown in Table 6.

The test plate was made of 5PV-50Q steel with a thickness of 25 mm and a width of 4.0 O.
Two plates having a length of 750 nm were assembled and used by cutting a single bevel as shown in FIG. 4.

Using the welding conditions described above, a 2mm V notch Charpy impact test piece was taken from 2rILrIL below the plate surface on the FP side for welding workability, adjustment of internal defects, or storage required as shown in FIG.

In the figure, N indicates the notch position.

The results of these tests are summarized in Table 8.

As is clear from Table 8, the fluxes of the present invention F1 to F-7
has good slag removability, good bead shape, no pockmarks, and no slag inclusions.
In addition, good impact values were obtained and the amount of oxygen in the weld metal was small.

In contrast, the comparative flux F-8 has good slag releasability and shape, but generates pock marks and has a low impact value.
There were problems such as high oxygen levels.

As detailed above, the flux of the present invention not only has good slag releasability in horizontal submerged arc welding, is free from pockmarks, and provides a good bead appearance;
It has no slag inclusions and has high notch toughness in welded parts, so it has extremely high industrial value as a flux for horizontal submerged arc welding.

[Brief explanation of drawings]

Figure 1 shows S 102 + Al, 203 + Ca F2
Fig. 2 is a schematic diagram showing the composition range investigation of S i 02 + Al2O3 + CaF2 (component range investigation 1) showing the groove shape and dimensions used here, and Fig. 2 is a schematic diagram showing the stacking order of the weld bead used
Figure 3 shows S i02 + Aj! ! 203 + Ca
Relationship diagram between the amount of F2 added and the amount of diffusible hydrogen in the weld metal, No. 4
The figure is a schematic diagram showing the shape and dimensions of the groove used in the example. Figure 5 is a schematic diagram showing the stacking order of weld beads in the example. Figure 6 is a schematic diagram showing the stacking order of the weld beads in the example. It is a schematic diagram showing a collection procedure.

Claims (1)

[Claims] I5i0221%~30%, MnO3~15%, C
aO3~15%, N12032I~30%, CaF22
S 102 +A l 20 with 0 to 30% as essential components
3 +CaF2-68 to 83%, and MgO to 2
%, and the bulk density is 1.4. ! i2/c111. A melt flux for horizontal submerged arc welding that is characterized by its super strength.