KR20170035160A

KR20170035160A - Ceramic Backing Material for Electro Gas Welding and Welding Supporting Apparatus having The Same

Info

Publication number: KR20170035160A
Application number: KR1020150133908A
Authority: KR
Inventors: 정무수; 유석진; 권문수
Original assignee: 정무수
Priority date: 2015-09-22
Filing date: 2015-09-22
Publication date: 2017-03-30

Abstract

The present invention relates to a ceramic backing material for electrogas welding comprising: SiO_2; Al_2O_3; MgO; an alkali oxide; and an alkaline earth oxide. The SiO_2 is 24-38 wt%, the Al_2O_3 is 58-76 wt%, the MgO is 3-8 wt%, and the alkali oxide and alkali earth oxide are 2.5-5.0 wt%. When high heat input electrogas welding is performed, welding workability and welding progression are improved; a low backside bead is generated; and is possible to obtain excellent impact toughness equal to or greater than the welding specifications.

Description

TECHNICAL FIELD [0001] The present invention relates to a ceramic backing material for electrogas welding and a ceramic welding backing material having the same.

TECHNICAL FIELD The present invention relates to a ceramic backing material for electrogas welding, which is used for substitution heat electrogas welding, and which can improve welding workability and excellent impact toughness, and a ceramic welding support having the ceramic backing material.

In general, large structures requiring welding such as shipbuilding, marine, plant, and other steel structures are required to be connected to each other through a process of interconnecting large blocks made of sheet metal. In this case, the thickness of the base material to be welded is varied from 10 mm to 100 mm, and the welding methods include FCAW (Flux Cored Arc Welding) and EGW Electro Gas Welding).

Among them, EGW method is the most widely used welding method at present shipyard. The EGW method is an automatic welding method for exclusive use of the upper and lower sides of the welded joint. The face of the welded part is coated with copper copper that can be cooled by water cooling or air cooling type, the ceramic backing material is attached to the backside, Method. This EGW method is a welding method that can have a higher production efficiency than FCAW which is completed by welding several times to several times.

A conventional ceramic welding support for Erotro gas welding is disclosed in U.S. Patent No. 10-1081238, filed on Nov. 1, 2011, which includes glass fibers that generate slag for the protection of welds, A plurality of ceramic bodies each having a bead groove formed on a surface opposite to the welded portion so as to form a bead, an aluminum case covering the other side surface except for the bead groove forming surface of the plurality of ceramic bodies, And a protective member which is interposed between the aluminum case to protect the ceramic body from external physical impact and protect the aluminum case from a high temperature thermal shock.

The conventional ceramic body is composed of 70 wt% or less of SiO ₂ , about 20 wt% or less of Al ₂ O ₃ , about 5 wt% or less of MgO, less than 1 wt% of CaO, K ₂ O, and Na ₂ O , The ratio of acidic oxides such as SiO2 and P2O5 to basic oxides such as Al2O3, CaO and Fe2O3 is 4, the fire resistance is SK 12 ~ 18 and the volume specific gravity is 1.5 ~ 1.6.

In recent years, as the use of low-temperature steel sheets with a thickness of 25 mm or more has been increased, the number of heat input welds of 200 kJ / cm is increasing. Impact toughness at low temperatures due to poor welding workability and high heat input can not be obtained at the inlet heat of 200 kJ / cm or more, and at present, the impact test on the shipowner side does not measure the central part of the base material, Impact testing is required.

Since the width of the welded portion is narrow, the impact strength of the backside portion is lower than that of the central portion and the surface portion of the base material due to the stress concentration.

For these reasons, in order to improve the low-temperature impact toughness of the backside in large heat welding in which the base material of 25 mm or more is welded, a welding rod containing components such as nickel, chromium, and manganese has been developed and used. However, When used in combination with a conventional ceramic support for electrogas welding, problems such as occurrence of a large amount of spatter due to lowering of arc stability and defective formation of backside beads due to lowering of spreadability of molten metal occur, Such a problem may cause a decrease in impact toughness. In addition, high backside bead is generated during welding of large heat source, resulting in post-processing such as grinding.

Therefore, it is required to improve the welding conditions of the large heat welding and the ceramic backing material capable of coping with the welding wire.

Patent Document 1: 10-1081238 (November 01, 2011)

Accordingly, an object of the present invention is to provide a ceramic backing material for electrogas welding, which can improve welding workability and welding progress when performing high-efficiency electrogas welding, generate low-back beads, And to provide a ceramic welded support.

Another object of the present invention is to provide a ceramic backing material for electrogas welding capable of easily protecting an arc portion and improving arc stability by adding a certain amount of an alkaline oxide and an alkaline earth oxide which are easily ionized, .

In order to achieve the above object, the ceramic backing material of the present invention comprises SiO ₂ , Al ₂ O ₃ , MgO, an alkali oxide and an alkaline earth oxide, and the content of the SiO ₂ is 24 wt% to 38 wt%, the content of the Al ₂ O ₃ is 58 wt% to 76 wt%, the content of the MgO is 3 wt% to 8 wt% 2.5 wt% to 5.0 wt%.

And the alkaline oxide and alkaline earth oxide are CaO, K ₂ O, and Na ₂ O.

The ceramic backing material further includes TiO2, MnO, and ZrO2, and the weight ratio of the TiO2, MnO, and ZrO2 is 0.3 wt% to 2.0 wt%.

The ceramic backing material is characterized in that the ratio of the acidic oxide to the basic oxide is 0.4 to 0.7.

And the refractory degree of the ceramic backing material is SK 20 ~ 38.

And the bulk specific gravity of the ceramic backing material is 1.7 to 2.0.

The ceramic welding support of the present invention includes a ceramic backing member, a protective case that is disposed on both sides of the ceramic backing member to protect the ceramic backing member, and glass fibers that are laminated on the ceramic backing member.

The protective case is formed of a metal material and has a thickness of 0.5 to 1.5 mm.

And the thickness of the glass fiber is 0.05 to 0.4 mm.

As described above, the ceramic backing material for electrogas welding according to the present invention improves the welding workability and weld progress when performing the high-temperature electrogas welding of a thick plate having a thickness of 25 mm or more, produces a low-profile bead of 0.2 mm or less, 3Y grade, it has the advantage of obtaining excellent impact toughness of 47J or more.

Further, the ceramic backing material for electrogas welding according to the present invention can easily protect the arc portion and improve the arc stability by adding a certain amount of an alkaline oxide and an alkaline earth oxide which are easily ionized.

1 is a perspective view of a ceramic welded support according to an embodiment of the present invention.
2 is a cross-sectional view of a ceramic welded support according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The sizes and shapes of the components shown in the drawings may be exaggerated for clarity and convenience. In addition, terms defined in consideration of the configuration and operation of the present invention may be changed according to the intention or custom of the user, the operator. Definitions of these terms should be based on the content of this specification.

FIG. 1 is a perspective view of a ceramic welded support according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a ceramic welded support according to an embodiment of the present invention.

1 and 2, a ceramic welding support according to an embodiment of the present invention includes a ceramic backing member 10, a ceramic backing member 10 and a ceramic backing member 10, And a glass fiber 30 laminated on the upper surface of the ceramic backing member 10. [

The glass fiber 30 is laminated on the upper surface of the ceramic backing material 10 so as to generate slag for protecting the weld formed between the two base materials and the thickness of the glass fiber 30 is 0.05 to 0.4 mm .

The bead groove 40 is formed in a longitudinal direction in order to form a back bead at the center of the top surface and to discharge a welding gas. do.

The protective case 20 may be formed of a metal material, specifically, a metal material, and protects the ceramic backing material 10 from external physical impact. The protective case 20 may have a thickness of 0.5 to 1.5 mm.

Ceramic backing material 10 include _{SiO 2, Al 2 O 3,} MgO, alkali oxides and alkaline earth oxides.

Here, CaO, K ₂ O and Na ₂ O may be used as the alkali oxide and alkaline earth oxide.

The weight percentage of the components constituting the ceramic backing material 10 is in the range of 24 wt% to 38 wt% for SiO ₂ , 58 wt% to 76 wt% for Al ₂ O ₃ , 3 wt% to 8 wt% for MgO, Al and alkaline earth oxides such as ₂ O and Na ₂ O range from 2.5 wt% to 5.0 wt%.

The ceramic backing material 10 may further contain impurities such as TiO2, MnO, and ZrO2 in the range of 0.3 wt% to 2.0 wt% in addition to the main component described above.

The ceramic backing material 10 has an acidic to basic oxide ratio of 0.4 to 0.7, a refractory degree of SK 20 to 38, and a bulk specific gravity of 1.7 to 2.0.

Here, the acidic oxide is SiO ₂ and P ₂ O ₅ And the basic oxide may be Al ₂ O ₃ , CaO, Fe ₂ O _3, or the like.

SiO ₂ is a typical acidic oxide and serves to increase the viscosity of the molten slag, and serves to prevent the molten slag from flowing out of the ceramic backing material for vertical and horizontal welding.

If the content of SiO ₂ is less than 24 wt%, the viscosity of the molten slag is lowered and the molten slag flows down during the welding process. If the content of SiO ₂ is less than 38 wt%, the viscosity of the molten material is higher than that of molten metal. It is not easy to cause impurities in the welded portion and defects such as blow holes.

Al ₂ O ₃ is a component that increases the softening temperature of ceramics, but it is a weak component in thermal shock. When the content is less than 58 wt%, molten slag is mixed into the welded part due to overheating of molten slag in over- And it is also possible to cause defects due to mixing of molten slag. If the content is 76 wt% or more, the refractory is too high, so that molten slag for protecting the welding portion on the back side is reduced during welding, and impurities such as nitrogen, oxygen, hydrogen, etc. are mixed and welding defect occurs, Ceramics broken due to thermal shock can break the welded ceramic.

MgO acts as a high melting point slag forming agent to improve the solidification rate of molten slag, thereby preventing sag deflection and stabilizing the appearance of the slag. If the content is less than 3 wt%, the solidification rate of the slag is decreased in the upward-facing upward welding, and the bead sagging phenomenon occurs when welding. If the content is more than 8 wt%, the solidification rate becomes too fast.

Alkali oxides and alkaline earth oxides are components that are ionizable and play an important role in arc stability. Of these, CaO, K2O and Na2O are easily added components. When the content is less than 2.5 wt%, arc stability And it is not easy to observe a large amount of spatters and to observe the welding portion. If the content is more than 5 wt%, it can not have a high fire resistance which is not suitable for the heat welding.

If the ratio of the acidic oxide to the basic oxide is less than 0.4, the viscosity is too high to lower the progress of welding. If the ratio is more than 0.7, the viscosity is too low to cause the molten slag to flow down.

The refractory degree of the ceramic backing material 10 is preferably SK20 to 38. If the fire resistance is less than SK 20, the bead will be excessively generated at the time of welding at the heat of substitution, the weldability will be lowered and the impact toughness will be lowered. If the fire resistance is higher than SK 38, molten slag will not easily occur. A weld defect occurs, and the slag, which is not completely melted, adheres to the backside bead and needs to be post-processed to remove it.

When the volume specific gravity of the ceramic backing material 10 is less than 1.7, slag is excessively generated and the ceramic is not rigid, so that when the ceramic backing material is removed after welding in the large heat welding, the ceramic adheres to the back bead, If it is 2.0 or more, it is difficult to generate molten slag, so that the bead protection is not smooth and welding defect may occur.

The ceramic backing material adjusts the content ratio of acidic oxides such as SiO ₂ and P ₂ O ₅ , which increase the viscosity of the ceramic melt, and alkaline oxides such as Al ₂ O ₃ , CaO and Fe ₂ O ₃ , which decrease the viscosity of the melt. It is possible to provide a ceramic backing material having an appropriate refractivity and bulk specific gravity. As the welding progress is improved and the amount of heat of welding is lowered, impact toughness suitable for 3Y grade can be obtained.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, these examples are provided for illustrating the present invention, and the present invention is not limited by these examples.

As shown in Table 1 below, ceramic backing materials having different compositions were prepared.

division Example
Comparative Example One
2 3 One 2 3 4 5 6 SiO2 35.2
28.7 27.2 72.0 33.5 64.7 1.1 30.2 90.9 Al2O3 58.2
60.2 66.2 18.1 63.2 17.8 98.0 65.2 5.7 MgO 3.2
5.4 3.1 4.93 1.8 14.1 0.2 0.4 1.8 Alkali oxide, Alkali
Earth oxide 2.6 4.2 2.5 4.07 0.6 2.9 0.2 2.9 1.2 Other 0.8
1.5 1.0 0.9 0.9 0.5 0.5 1.3 0.3 Sum 100
100 100 100 100 100 100 100 100 The acidic oxide /
Basic oxide 0.61
0.48 0.41 4 0.53 3.6 0.01 0.46 15.9 Refractory (SK) 26
22 36 18 40 12 40 35 36 In volume ratio 1.7
1.8 1.9 1.6 1.8 1.5 1.8 1.8 1.8

The welding conditions of the examples are shown in Table 2 below.

Base material Welding Root
Gap Face
Gap Groove
angle Toch '
Angle Copper
shoe electric current
(A) Voltage
(V) Welding speed
(cpm) Heat input
(kJ / cm) EH36 SC-EG3
3Y 8mm 30mm 30 7 28mm 440 44 5.5 211.20

Impact Toughness Measurement Method: KS B 0810: 2003

Impact test specimen: 10 * 10 * 55mm (V-notched)

Impact toughness suitable for 3Y grade is from -20 to 34 J (Single) at least, and 3 values are minimum 47 J or more. Impact Toughness The specimen is to be taken from the section 5 mm away from the backside of the weld. And the results are shown in Table 3.

division Welding test Comparative Example One 2 3 One 2 3 4 5 6 for
Fold
castle Arc
stability ◎ ◎ ◎ ◎ X ◎ X ◎ X Spata ◎ ◎
◎ ◎ X ◎ ○ ◎ X Slag
Peelability ◎ ◎ ◎ X X X X ◎ ○ Blow hole ◎ ◎ ◎ X ○ ▲ ◎ ○
X Backside bead ◎ ◎ ◎ ▲ ▲ ○ ▲
X ○ Backside bead
Height 1.8 1.7 1.4 2.4 1.5 2.6 1.0 1.8 1.2 The back side
Impact toughness
(-20 ° C) One 62 71 68
55 62 37 92 57 62 2 69 66 72 32
57 46 91 59 58 3 72 65 88 63
59 52 85 30 73 Avg 67.7 67.3 76.0 50.0
59.3 45.0 89.3 48.7 64.3

◎ Excellent, ○ Good, ▲ Normal, X bad

Comparative Example No. 1 is a conventional electrogas welding ceramics. However, arc stability and spatter generation are satisfactory when welding is performed with the heat of substitution. However, excessive backside beads due to low refractivity and a ratio of acidic oxide and basic oxide , The viscosity of the molten slag was so high that the progress of the molten slag was lowered and the protection of welds was not easy. Thus, three blowholes were formed on the side of the backside bead, and the impact toughness value which was less than the standard was measured at one place.

In Comparative Example 2, although the ratio of the acidic oxide and the basic island oxide was good, the amount of the alkali oxide and the alkaline earth oxide was so small that the arc stability deteriorated, a large amount of spatta was generated, and the incompletely melted slag stuck to the backside bead A phenomenon has occurred.

In Comparative Example 3, the ceramic backing material for FCAW is good in arc stability and spatter generation, but due to the generation of a high backside bead and a low bulk specificity due to a low heat input, ceramic breakage due to heat of substitution causes the broken ceramic to remain on the backside bead A post-process such as grinding has occurred.

Comparative Example 4 is a ceramic backing material composed of 98% alumina. Although low back bead formation and welding progress are good, arc stability is lowered, spatter is generated in a large amount, ceramic remains due to thermal shock, The backside bead is defective, and a post-grinding process is required.

Comparative Example 5 is a product similar to that of the Example. The arc was stable and the slag peeling property was good, but the flowability of the molten slag was lowered due to the low content of MgO, so that the bead was formed at 2 points and the bead was formed at one point, A value lower than this criterion was measured.

Comparative Example 6 was a ceramic backing material having a proper refractory or bulk specific gravity. However, the arc stability was deteriorated and a large amount of spatters were generated. Because of the high viscosity, it was not easy to protect the welded portion.

On the other hand, it can be seen that the ceramic backing materials 1, 2 and 3 of the present invention have good arc stability, spatter generation rate, molten slag, peelability and backside bead formation and height, .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein. Various changes and modifications may be made by those skilled in the art.

10: ceramic backing material 20: protective case
30: glass fiber 40: bead groove

Claims

SiO ₂ , Al ₂ O ₃ , MgO, an alkali oxide and an alkaline earth oxide,
The Al ₂ O _{3 content} is from 58 to 76 wt%, the MgO content is from 3 to 8 wt%, the alkali oxide and the alkaline earth oxide are from 2.5 to 5.0 wt%, and the content of the SiO ₂ is from 24 wt% to 38 wt% Ceramic backing for electrogas welding.

The method according to claim 1,
Wherein the alkaline oxide and alkaline earth oxide are CaO, K ₂ O, and Na ₂ O. The ceramic backing material for electrogas welding according to claim 1,

The method according to claim 1,
Wherein the ceramic backing material further comprises TiO2, MnO, and ZrO2.

The method of claim 3,
Wherein the weight ratio of TiO2, MnO, and ZrO2 is 0.3 wt% to 2.0 wt%.

The method according to claim 1,
Wherein the ceramic backing material has a ratio of an acidic oxide to a basic oxide of 0.4 to 0.7.

The method according to claim 1,
And the refractory degree of the ceramic backing material is SK 20 to 38. The ceramic backing material for electrogas welding according to claim 1,

The method according to claim 1,
Wherein the volume specific gravity of the ceramic backing material is 1.7 to 2.0.

Ceramic backing material;
A protective case which is disposed to be wrapped around the lower surface and both side surfaces of the ceramic backing material to protect the ceramic backing material;
And a glass fiber laminated on the upper surface of the ceramic backing member,
Wherein the ceramic backing material is a ceramic backing material according to any one of claims 1 to 7.

9. The method of claim 8,
Wherein the protective case is formed of a metal material and has a thickness of 0.5 to 1.5 mm.

9. The method of claim 8,
Wherein the thickness of the glass fiber is 0.05 to 0.4 mm.