JPH08206832A - Cladding by welding method of carbon steel with flux cored austenitic stainless steel wire - Google Patents

Abstract

PURPOSE: To improve cladding by welding by specifying weaving width, number of times of weaving, ratio between weaving width and number of times of weaving, heat input quantity and penetration depth. CONSTITUTION: A carbon steel is subjected to cladding by welding with a flux cored austenitic stainless steel wire. This case uses weaving welding with CO2 shield gas, the weaving width is 10-30mm. In the case of <10mm width, the bead shape is turned to projecting and flat in excess of 30mm, further, much spatters of large particle are generated. The number of weaving is set to 30-50 time/min. The heat input quantity is set to 25-35KJ/cm while the ratio of weaving width/number of times is a range of 25-0.75, the penetration depth is set to <1.0mm. By this method, good bead shape and penetration depth can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas shielded arc welding method for carbon steel, and more specifically to a flux-cored austenitic system capable of obtaining a good weld by specifying the ratio of the weaving width and the number of times of weaving. The present invention relates to a method for overlay welding of carbon steel with a stainless steel wire.

[0002]

2. Description of the Related Art Gas shielded arc welding using a flux-cored wire is highly popular and can be automated or semi-automated, so that it is rapidly becoming popular in recent years in place of the covered arc welding. Furthermore, in the field of automatic and semi-automatic welding, gas shielded arc welding with flux-cored wire has less spatter and has a good bead appearance. Therefore, the range of welding application is expanding instead of MIG welding or TIG welding using solid wire. It's starting.

The flux-cored wire has a large welding speed and welding efficiency as compared with the coated arc welding method and has a high efficiency, and in addition to its ease of use and economical efficiency, its application range is expanded to joint welding and overlay welding. ing. The overlay welding of stainless steel to the inner surface of the pressure vessel is mainly performed by band arc, but the covered arc welding is used in places where it cannot be applied.

In the overlay welding by the covered arc welding, the chemical composition of the weld metal is apt to change depending on the skill of the welding operator, the habit or the construction method. Particularly in the overlay welding of the first layer, the change in the penetration directly affects the chemical composition of the weld metal of the first layer, so that it is necessary to control the welding conditions correctly. Furthermore, the covered arc welding method is poor in work efficiency and requires man-hours. On the other hand, as the welding method, the gas shield welding method using a flux-cored wire has a wide range of applications as shown in Japanese Patent Application No. 6-58285, which shows the technique of the plug welding method.
The possibility of application to overlay welding is becoming sufficient.

However, the welding with the flux-cored wire has a large penetration as compared with the covered arc welding.
Welding conditions for first layer overlay welding must be controlled more strictly.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its purpose is to build-up weld carbon steel with flux-cored stainless steel wire. Another object of the present invention is to provide a method for overlay welding of carbon steel by using a flux-cored austenitic stainless steel wire that can obtain a good weld bead shape and penetration.

[0007]

In view of the above circumstances, the inventors of the present invention have made extensive studies on conditions for overlay welding of carbon steel with flux-cored stainless steel wires. As a result, it was found that a good weld bead shape and penetration can be obtained by specifying the welding conditions and the weaving conditions.

The present invention is based on the above findings. The gist of the present invention is that when carbon steel is overlay welded with a flux-containing austenitic stainless steel wire, weaving welding with a CO ₂ gas shield is used. ) Weaving width: 10 to 30 mm, (2) Weaving frequency: 30 to 50 times / min, (3) Heat input amount is 25 to 35 kJ / cm, (Weaving width) / (Weaving frequency) ) Ratio is 0.25 to 0.75
And a penetration depth of 1.0 mm or less. A carbon steel build-up welding method using a flux-cored austenitic stainless steel wire is provided.

The present invention will be described in detail below.

[0010]

First of all, among the weaving conditions in the present invention,
The weaving width affects the bead shape, particularly the smoothness of the bead, and when the weaving width is less than 10 mm, the bead shape becomes convex, and when the weaving width exceeds 30 mm, the bead shape becomes flat and a large amount of large-sized spatters are generated. For 1
It was defined as 0 to 30 mm.

On the other hand, as the number of weaving increases, the bead waveform becomes finer and smoother, but if it exceeds 50 times / min, a large amount of spatters of large particles are generated, and 30 times / mi.
If it is less than n, the bead waveform becomes rough, so the number of times of weaving is defined as 30 to 50 times / min. If the welding heat input exceeds 35 kJ / cm, the amount of deposited metal per unit time increases, the bead shape deteriorates, and the heat effect on the base metal becomes large. If it is less than 25 kJ / cm, the amount of penetration increases, the amount of ferrite decreases, and the tendency for hot cracking to increase becomes high, so it was defined as 25 to 35 kJ / cm.

Further, by combining these conditions, in order to suppress the reduction of the main components of stainless steel such as Cr and Ni due to the dilution of the base material as much as possible, the penetration depth was 1.0 mm or less, and the result was investigated. Was found to be appropriate. Therefore, the welding procedure for suppressing the penetration depth to 1.0 mm or less is that the welding heat input is 25 to 35 kJ / c.
m, weaving width / number of weaving = 0.25
The most effective method is welding in the range of 0.75.

The present invention relates to JIS G 3101 rolled steel for general structure, ASTM A387 Gr. It is applied to overlay welding to carbon steel such as No. 22 Cr-Mo steel plate for pressure vessel. The flux-containing austenitic stainless steel wire used is of the type specified in JIS Z 3323.

Further, the welding condition is 100% CO ₂ shielding gas, and the wire diameter is 1.2 mm, the welding temperature is 200 to 240.
A, arc voltage 31 to 33 V, welding speed 10 to 18 cm
/ Min is preferable.

[0015]

EXAMPLES The effects of the present invention will be specifically described below with reference to examples. Steel plates shown in Table 1 and JIS Z 3 shown in Table 2
Using a wire equivalent to 323YF-309L, downward welding was performed with a CO ₂ gas shield as shown in FIG. 2, and the respective states were compared.

The results are shown in Tables 3 and 4, and the test No. having a heat input amount of less than 25 kJ / cm was used. 5, 1
In Nos. 7 and 29, the penetration was excessive and welding workability deteriorated, resulting in poor welding. Test N with heat input exceeding 35 kJ / cm
o. Nos. 4, 16 and 28 were excessively melted and the bead shape was trapezoidal, which is not suitable for overlay welding. Test No. with weaving width / weaving count less than 0.25 11, 2
In Nos. 3 and 35, the penetration was excessive and the bead shape was convex, resulting in poor welding. Test No. in which weaving width / number of weaving exceeds 0.75 Nos. 12, 24, and 36 are not suitable for build-up welding because the bead shape is concave due to excessive melting and a large amount of spatter is generated.

Test N with weaving width less than 10 mm
o. Nos. 6, 18, and 30 are not suitable for overlay welding because the beads have a convex shape. Test N with weaving width over 30 mm
o. Nos. 7, 19, and 31 have flat beads and are apt to generate spatter, which is not suitable for overlay welding. Test No. with a weaving frequency of less than 30 times / min. 9, 21, 3
No. 3 is not suitable for overlay welding because the bead has a convex shape. Test No. in which the number of weaving exceeds 50 times / min.
Nos. 8, 20, and 32 are not suitable for build-up welding because the bead has a flat shape and spatter is often generated.

On the other hand, the test No. 1,
2, 3, 10, 13, 14, 15, 22, 25, 26,
Nos. 27, 34, and 37 showed good results in spatter generation state, weld bead shape, and penetration state. In addition, in Tables 3 and 4, the evaluation of the spatter generation condition is ◯: good, ×: a lot of occurrences, bead shape evaluation is ◯: good,
X: defective, comprehensive evaluation, ◯: spatter generation status,
Good bead shape, penetration of 1.0 mm or less, x:
It shows that one or more defects of spatter generation, defective bead shape, and penetration of 1.1 mm or more were observed.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

As described above, according to the present invention, in the overlay welding of carbon steel, by specifying the heat input amount, the weaving width and the number of times of weaving, a good bead shape and penetration in the overlay welding of the flux-cored wire can be obtained. Can be obtained, which greatly contributes to the improvement of overlay welding.

[Brief description of drawings]

FIG. 1 shows the results of investigating the penetration depth by the heat input amount and the weaving width / number of weaving.

FIG. 2 is a cross-sectional view showing a welding procedure used in Examples.

[Explanation of symbols]

 1 Welding torch 2 Welding wire 3 Weaving width 4 Overlay weld metal 5 Carbon steel base metal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Kaneda 2-6-3 Otemachi, Chiyoda-ku, Tokyo Inside Nippon Steel Corporation

Claims (1)

[Claims] 1. When overlay welding of carbon steel with a flux-containing austenitic stainless steel wire, C
Weaving welding by O ₂ gas shield (1) Weaving width: 10 to 30 mm, (2) Weaving frequency: 30 to 50 times / min, and (3) Heat input 25 to 35 kJ / cm. And the (weaving width) / (number of weaving times) ratio is 0.25 to 0.75.
And a penetration depth of 1.0 mm or less. A method of overlay welding carbon steel with a flux-containing austenitic stainless steel wire.